Abstract
The disclosure relates to a roller crusher having two generally parallel rollers arranged to rotate in opposite directions, towards each other, and separated by a gap, each roller having two ends, the roller crusher comprising: a flange attached to at least one of the ends of one of the rollers, the flange extending in a radial direction of the roller, the flange having a height above an outer surface of the roller, wherein the roller crusher further comprises at least one scraper arranged at an end of the roller with a flange for at least partially removing material accumulated on the flange and/or on the outer surface at the end of the roller. According to the invention, the at least one scraper comprises a scraping element having a scraping surface which scraping surface comprises a polycrystalline diamond (PCD).
Claims
1. A roller crusher having two generally parallel rollers arranged to rotate in opposite directions, towards each other, and separated by a gap, each roller having two ends, the roller crusher comprising: a flange attached to at least one of the ends of one of the rollers, the flange extending in a radial direction of the roller, the flange having a height (H) above an outer surface of the roller, wherein the roller crusher further comprises at least one scraper arranged at an end of the roller with a flange for at least partially removing material accumulated on the flange and/or on the outer surface at the end of the roller, and wherein each of the at least one scraper comprises a scraping element having a scraping surface which scraping surface comprises a polycrystalline diamond (PCD).
2. The roller crusher as claimed in claim 1, wherein the scraping element further comprises a wear resistant material in which the polycrystalline diamond (PCD) is at least partly embedded.
3. The roller crusher as claimed in claim 2, wherein the wear resistant material is one from the list of: a ceramic material, a metal ceramic composite material, and a metal matrix composite material.
4. The roller crusher as claimed in claim 1, wherein the scraping surface of the at least one scraper is arranged to incline in a relation to a normal to the inner surface of the flange, and incline such that a distance between the normal to the inner surface of the flange and the scraping surface decreases towards the flange.
5. The roller crusher as claimed in claim 1, wherein the at least one scraper has a surface facing the flange, which surface has an extension from the scraping element towards a rear end of the at least one scraper, wherein the at least one scraper is structured and arranged such that a distance between the surface facing the flange and an inner surface of the flange decreases towards the scraping element over at least a part of the extension.
6. The roller crusher as claimed in claim 1, wherein the at least one scraper has a surface facing away from the flange, which surface has an extension from the scraping element towards a rear end of the at least one scraper, wherein the at least one scraper is structured and arranged such that a distance between the surface facing away from the flange and an inner surface of the flange decreases towards the scraping element over at least a part of the extension.
7. The roller crusher as claimed in claim 1, wherein the scraping element comprises a front portion and a back portion which are attached to each other, and wherein the front portion has the scraping surface.
8. The roller crusher as claimed in claim 7, wherein the back portion has a surface facing the flange and a surface facing away from the flange, said surfaces being substantially parallel with an inner surface of the flange.
9. The roller crusher as claimed in claim 1, wherein the at least one scraper is arranged at a lower part of the roller crusher.
10. The roller crusher as claimed in claim 1, wherein the at least one scraper is arranged such that the scraping surface of the at least one scraper at least partly faces downwards for allowing removed material to leave from the roller and the scraping surface by gravitational force.
11. The roller crusher as claimed in claim 1, wherein the at least one scraper has a fastening position located at a distance from the outer surface of the roller, wherein the at least one scraper is arranged such that a position of the scraping surface of the at least one scraper is located at, or consecutive to, a radial axis which extends from a rotational axis of the roller and through the fastening position.
12. The roller crusher as claimed in claim 1, wherein the roller crusher further comprises at least one holding fixture for the at least one scraper, which at least one holding fixture connects to a frame of the roller crusher at a fastening position of the at least one scraper.
13. The roller crusher as claimed in claim 12, wherein the at least one holding fixture comprises at least one bracket and at least one wedge element, which wedge element is structured and arranged to attach the at least one scraper to the at least one bracket such that an angular position of the at least one scraper is shifted in relation to an angular position of the at least one bracket in a rotational plane of the roller.
14. The roller crusher as claimed in claim 1, wherein the roller crusher further comprises a flexible retaining arrangement arranged to intercouple at the at least one scraper with a frame of the roller crusher.
15. The roller crusher as claimed in claim 1, wherein the at least one scraper is at least two scrapers arranged consecutive to each other at an end of the roller with a flange for at least partially removing material accumulated on the flange and/or on the outer surface at the end of the roller.
16. The roller crusher as claimed in claim 15, wherein the at least two consecutive scrapers are arranged at equal distances to the flange and/or to the outer surface at the end of the roller.
17. The roller crusher as claimed in claim 15, wherein the at least two consecutive scrapers are arranged at different distances to the flange and/or to the outer surface at the end of the roller.
18. The roller crusher as claimed in claim 17, wherein the at least two consecutive scrapers are arranged in decreasing distance from the flange and/or from the outer surface of the roller seen from a front scraper to consecutive scraper(s).
19. The roller crusher as claimed in claim 17, wherein the at least two consecutive scrapers comprise at least two subsets of at least two consecutive scrapers, wherein the at least two consecutive scrapers within each subset are arranged at the same distance from the flange and/or roller surface, and wherein the at least two subsets of consecutive scrapers are arranged at different distance to the flange and/or the outer surface at the end of the roller.
20. The roller crusher as claimed in claim 19, wherein the at least two subsets of consecutive scrapers are arranged at a decreasing distances to the flange and/or the outer surface at the end of the roller seen from a front subset to consecutive subset(s).
21. The roller crusher as claimed in claim 1, wherein the roller crusher comprises two flanges attached to opposite ends of one of the rollers, and wherein the at least one scraper comprises a first subset of at least one scraper and a second subset of at least one scraper which first and second subsets are each disposed on a respective end region of the roller with the two flanges.
22. The roller crusher as claimed in claim 1, wherein the roller crusher further comprises a remote material removal device configured to output a material removing beam towards a target area, wherein the remote material removal device and the at least one scraper are arranged consecutive to each other at an end of the roller with a flange for at least partially removing material accumulated on the flange and/or on the outer surface at the end of the roller.
23. The roller crusher as claimed in claim 22, wherein the target area of the remote material removal device is located in front of the at least one scraper.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0145] The disclosure will be described in more detail with reference to the appended schematic drawings, which show an example of a presently preferred embodiment of the disclosure.
[0146] FIG. 1 is a perspective view of a roller crusher according to prior art.
[0147] FIG. 2A is a schematic top view of two rollers of the roller crusher of FIG. 1.
[0148] FIG. 2B is a schematic top view of two rollers of a roller crusher of the prior art according to an alternative embodiment.
[0149] FIG. 3A is a top cross-sectional view of segments of a roller crusher according to the prior art.
[0150] FIG. 3B is a side cross-sectional view of segments of a roller crusher according to an embodiment of the disclosure.
[0151] FIG. 3C is a top view of parts of a roller crusher according to an embodiment of the disclosure.
[0152] FIG. 4A is a part-sectional side view of a roller crusher according to an embodiment of the disclosure.
[0153] FIG. 4B is a part-sectional side view of a roller crusher according to another embodiment of the disclosure.
[0154] FIG. 4C is a part-sectional side view of a roller crusher according to another embodiment of the disclosure.
[0155] FIG. 4D is a part-sectional side view of a roller crusher according to another embodiment of the disclosure.
[0156] FIG. 5A is a part-sectional side view illustrating relative dimensions of scrapers of the roller crusher of FIG. 4A.
[0157] FIG. 5B is a part-sectional side view illustrating relative dimensions of scrapers of the roller crusher of FIG. 4D.
[0158] FIG. 6 is a perspective view of a scraper and a holding fixture for mounting the scraper on a roller crusher according to one embodiment of the disclosure.
[0159] FIG. 7 is a perspective view of three scrapers and their associated fixtures of FIG. 6 mounted consecutively to each other on a roller with a flange of a roller crusher according to an embodiment of the disclosure.
[0160] FIG. 8 is a perspective view of two pairs of consecutive scrapers mounted on a common fixture on a roller crusher according to another embodiment of the disclosure.
[0161] FIG. 9A-C is part-sectional side views of a roller crusher according to another embodiment of the disclosure illustrating a removal of built-up material using an air knife at three consecutive time positions.
[0162] FIG. 10 is a part-sectional side views of a roller crusher according to another embodiment of the disclosure.
[0163] FIG. 11 is a part-sectional side views of a roller crusher according to another embodiment of the disclosure.
[0164] FIG. 12 is a schematic side view of a monitoring system for a roller crusher.
[0165] FIG. 13A is a perspective view of a material removal system comprising a mechanical scraper and an air knife according to an embodiment of the disclosure.
[0166] FIG. 13B is a perspective cut-through view of the material removal system of FIG. 13A.
[0167] FIG. 13C is a side view of the cut-through illustrated in FIG. 13B together with parts of a roller with a flange.
[0168] FIG. 14A is a perspective view of a scraper for a roller crusher according to an embodiment of the disclosure.
[0169] FIG. 14B is a top view of parts of a roller crusher according to an embodiment of the disclosure.
[0170] FIG. 14C is an exploded view of the scraper of FIG. 14A.
[0171] FIG. 15A is a perspective view of a scraper for a roller crusher according to an embodiment of the disclosure.
[0172] FIG. 15B is a top view of parts of a roller crusher according to an embodiment of the disclosure.
[0173] FIG. 15C is an exploded view of the scraper of FIG. 15A.
[0174] FIG. 16 is a perspective view of two scrapers mounted on a common fixture on a roller crusher according to another embodiment of the disclosure.
DETAILED DESCRIPTION
[0175] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and to fully convey the scope of the disclosure to the skilled addressee. Like reference characters refer to like elements throughout.
[0176] As discussed in the background part of this disclosure, the arrangement of flanges to the ends of the crushing rollers (as shown in FIG. 2A and further discussed below), either one flange in each end of one of the grinding rollers (as shown in FIG. 2A and further discussed below), or one flange on each grinding roller (as shown in FIG. 2B and further discussed below), the crushing effect along the length of the grinding rollers are maintained. However, these flanges and also the edges of opposite crusher roller are under a lot of stress and wear during operation of the grinding roller due to accumulation of grinded material in the transition between the flange and an outer surface of the roller crusher. Prior art has suggested a scraper element for removing this accumulation of material, but an object of the present disclosure to proceed from there and ensure that flanges and edges of opposing roller crusher are subjected to less stress and wear and at the same time ensure effective removal of accumulation of material as well as economically acceptable time periods of operation of the roller crusher without need to adjust position or replace any scrapers within the roller crusher.
[0177] With reference to FIGS. 1, 2A, 2B, 4A, 4B, 4C, 4D, 5A, 5B, 7, 8, 10, this is achieved, in full or at least in part, by a roller crusher 1 having two generally parallel rollers 3, 4, 3, 4 arranged to rotate in opposite directions, towards each other, and separated by a gap G (see FIG. 3A), each roller having two ends. The roller crusher 1 further comprises a flange 36, 36 attached to at least one of the ends of one of the rollers 3, 4, 3, 4, which flange 36, 36 extends in a radial direction of the roller 3, 4, 3, 4 and has a height above an outer surface 37, 37 of the roller 3, 4, 3, 4. The roller crusher 1 further comprises at least one scraper 100, 200, 300, 100a, 100b, 100c, 100d, 100t arranged at an end of the roller 3, 4, 3, 4 with a flange 36, 36 for at least partially removing material accumulated on the flange 36, 36 and/or on the outer surface 37, 37 at the end of the roller 3, 4, 3, 4.
[0178] With reference to FIGS. 1, 2A, 2B, 4A, 4B, 4C, 4D, 5A, 5B, 7, 8, 10, this is also achieved, in full or at least in part by a method for operating a roller crusher 1 for grinding granular material, which roller crusher 1 has two generally parallel rollers 3, 4, 3, 4 arranged to rotate in opposite directions, towards each other, and separated by a gap G, each roller having two ends, the roller crusher 1 further comprises a flange 36, 36 attached to at least one of the ends of one of the rollers 3, 4, 3, 4, which flange 36, 36 extends in a radial direction of the roller 3, 4, 3, 4 and has a height above an outer surface 37, 37 of the roller 3, 4, 3, 4. The roller crusher 1 further comprises at least one scraper 100, 200, 300, 100a, 100b, 100c, 100d, 100t arranged at an end of the roller 3, 4, 3, 4 with a flange 36, 36. The disclosed method comprises at least a step of at least partially removing material accumulated on the flange 36, 36 and/or on the outer surface 37, 37 at the end of the roller 3, 4, 3, 4 by means of the at least one scraper 100, 200, 300, 100a, 100b, 100c, 100d, 100t.
[0179] For some example embodiments, two or more scrapers 100, 100a, 100b, 100c, 100t are provided arranged consecutively to each other at an end of the roller 3, 4, 3, 4 with a flange 36, 36. The arrangement of the at least two consecutively arranged scrapers 100, 100a, 100b, 100c, 100d, 100t allows a prolong operational time. The scraper 100, 100a, 100c which will first encounter the build-up material (herein termed: the front scraper or first-in-line scraper) will be exposed to significant wear. With time, the material of the front scraper 100, 100a, 100c will therefore gradually be worn off as a result of wear hence increasing the distance between the front scraper 100, 100a, 100c and the roller surface 37, 37 and/or flange 36, 36. As this wear process gradually occurs, the scraper 100, 100b, 100c, 100d, 100t arranged consecutively to, and behind, the front scraper 100, 100a, 100c (herein termed the second scraper or first following-scraper) will be increasingly more exposed to the build-up material and thereby gradually take on more and more of the task that the front scraper 100, 100a, 100c performed when the scrapers were new. This gradual transfer of scraping responsibility from the front scraper 100, 100a, 100c to the first following scraper 100, 100b, 100c, 100d, 100t thus allows prolonged operating time before the scrapers have to be replaced, thus reducing down-time of the roller crusher 1 and contribute to overall plant efficiency.
[0180] The disclosure should however not be construed as limited to the provision of two or more scrapers at an end of the roller with a flange. As will be detailed later herein, the inventive concept will be realized also with one scraper at an end of the roller with a flange. Example embodiments with only one scraper at an end of the roller with a flange will be described with reference to FIGS. 11 to 16.
[0181] FIG. 1 shows a roller crusher 1 according to the prior art. Such roller crusher 1 comprises a frame 2 in which a first, fixed crusher roller 3 is arranged in bearings 5, 5. The bearing housings 35, 35 of these bearings 5, 5 are fixedly attached to the frame 2 and are thus immoveable. A second crusher roller 4 is arranged in the frame 2 in bearings 6, 6 which are arranged in the frame 2 in a slidable moveable manner. The bearings 6, 6 can move in the frame 2 in a direction perpendicular to a longitudinal direction of the first and second crusher rollers 3, 4. Typically a guiding structure 7, 7 is arranged in the frame on first and second sides 50, 50 along upper and lower longitudinal frame elements 12, 12, 13, 13 of the roller crusher 1. The bearings 6, 6 are arranged in moveable bearing housings 8, 8 which can slide along the guiding structure 7, 7. Further, a number of hydraulic cylinders 9, 9 are arranged between the moveable bearing housing 8, 8 and first and second end supports 11, 11 which are arranged near or at a first end 51 of the roller crusher 1. These end supports 11, 11 attach the upper and lower longitudinal frame elements 12, 12, 13, 13 and also act as support for the forces occurring at the hydraulic cylinders 9, 9 as these are adjusting the gap width and reacting to forces occurring at the crusher rollers due to material fed to the roller crusher 1.
[0182] Such roller crushers work according to a technique called interparticle crushing. The crushing rollers 3, 4 rotates counter to each other as illustrated schematically in FIG. 1 using the arrows. The gap between the crushing rollers 3, 4 is adjusted by the interaction of feed load and the hydraulic system effecting the position of the second crusher roller 4. As shown in FIG. 1 and also in FIG. 2A which shows the rollers 3, 4 from above, one of the grinding rollers 3 further comprises flanges 36, 36 arranged at opposite ends of the grinding roller 3, wherein each flange 36, 36 has an outer edge that extends a height H (see FIG. 3A) radially past the outer surface 37 of the roller body of the grinding roller 3, and positioned axially outward of the roller body of the opposite grinding roller 4.
[0183] Another prior art roller crusher is disclosed in e.g. WO2013/156968, in which each of the grinding rollers with bearings is arranged in interconnected arch-shaped frame sections, wherein each interconnected arch shaped frame sections are pivotably connected to a base frame. The disclosed subject matter within this disclosure is equally applicable in such a prior art roller crusher arrangement.
[0184] As also illustrated in FIG. 3A, each flange 36 is arranged on an end of the roller 3 such that an inner surface 39 of the flange 36 is located at a distance F from the end of the opposing roller 4. The distance F is necessary to avoid contact between the flange 36 and roller 4 which could lead to material damage. At the same time, the distance F should not be too large, as that increases the risk of material leaving the roller crusher through the gap thus formed. The distance F may be realized by mounting the flange 36 to the roller 3 via shims 15, best illustrated in FIG. 3A. The purpose of the flanges 36, 36 is to prevent material from exiting the gap at the end thereof, thereby forcing all material that enters the roller crusher to pass through the crushing gap to be crushed. An alternative embodiment of a roller crusher with flanges is illustrated in FIG. 2B. The only difference between the two embodiments is that the roller crusher in FIG. 2B has flange 36 disposed on the second grind roller 4 instead of the first grind roller 3, which means that each of the grinding rollers 3, 4 has one flange 36, 36 each. As readily appreciated by the person skilled in the art, the technical effect of preventing material to exit the crusher 1, 1 at the ends of the gap will be equally well achieved for both disclosed embodiments. Importantly, the disclosed inventive concept is equally applicable to both these embodiments.
[0185] As previously mentioned, the gap between the rollers 3, 4 can be adjusted. For crushing operation, the roller crusher 1 is preset to have a specific distance between the rollers, the so-called start-up gap G. This is illustrated in FIG. 3A. The start-up gap G is selected based on several different factors, such as the roller crusher size (i.e. grinding roller diameter), the desired properties of crushed material etc. The start-up gap G may be in the range 10 to 140 mm. However, typically, the start-up gap G is within the range 60 to 90 mm.
[0186] The roller crusher further comprises a movement blocking arrangement 20 structured and arranged to limit the gap between the rollers to a minimum gap M. There are many different ways to provide such a movement blocking arrangement known in the art, and it is therefore not discussed in detail herein. One common solution, which is the solution illustrated in FIG. 1, is to provide a pair of mechanical engagement elements 20a, 20b on the bearing houses 35, 35. The minimum gap M may be relatively small for some roller crushers and/or materials to be crushed, such as in the range 10 to 30 mm. However, typically, the minimum gap M is at least 45 mm. It is however conceivable that the minimum gap is larger, such as e.g. at least 55 mm, or at least 60 mm or at least 65 mm or at least 70 mm.
[0187] As initially described, a problem with this type of grinding assemblies is that material tend to build up at the corner 40 (see FIG. 3A) between the outer surface 37 of the grinding roller 3 and the inner surface 39 of the flange 36, 36. Such material build-up 41 is schematically illustrated in FIG. 3A for the roller crusher 1 of FIGS. 1 and 2A, and is generally unwanted as it generates increased local loads in this area during operation, which may cause wear, damage and/or deformation on the opposite grinding roller 4 which does not have a flange. To provide a solution to this problem, means for removing at least a part of this build-up material 41 is provided. The current disclosure relates to two different such means, mechanical scrapers and a remote material removal device. The mechanical scrapers will be discussed with reference to FIGS. 2 to 8, 14 to 16, and the remote material removal device will then be discussed with reference to FIGS. 9 to 13.
[0188] FIG. 3B illustrates a mechanical scraper 100 according to an embodiment of the disclosure in a front view. The mechanical scraper 100 is attached to the roller crusher, e.g. in the frame or other supporting feature, but is here illustrated in isolation with respect to the crusher rollers to enhance clarity. The mechanical scraper 100 comprises two wear members 102a, 102b disposed at an end of the scraper 100 so as to define a scraping surface 104 generally facing the material to be removed. The statement generally facing the material to be removed implies that the scraping surface 104 is arranged substantially tangentially to the roller surface. The wear members 102a, 102b are attached to scraper main body 103 (not visible in the front view of FIG. 3B but can be seen in FIG. 3C). As illustrated in FIG. 3C, which shows the scraper 100 of FIG. 3B in a top view together with parts of a roller 3 with a flange 36 when rotating towards the scraper 100 as indicated by the arrow which indicates the tangential velocity of the rotating roller 3, the wear members 102a, 102b may be arranged on the scraper main body 103 such that the scraping surface 104 of the scraper 100 is arranged to incline in a relation to a normal N to the inner surface 39 of the flange 36, and incline such that a distance L1 between the normal N to the inner surface 39 of the flange 36 and the scraping surface 104 decreases towards the flange 36. The normal N is defined as a line which is orthogonal to a plane defined by the inner surface 39 of the flange 36. This allows for material to more easily be transported away from the corner 40 between the inner surface 39 of the flange 36 and the outer surface 37 of the roller 3 once scraped off, thus contributing to an efficient material removal process.
[0189] The nature of the material build-up 41 and the speed at which the at least one mechanical scraper 100 and the material build-up 41 meets, tend to make material removal substantially impact-driven. Hence, instead of the scraper with time creating a carved recess in the build-up material, large surface portions of the material build-up 41 are more or less instantaneously broken off when encountering the scraper. This is schematically illustrated in FIGS. 3B and 3C. The remaining portion of the material build-up 41 has been found to present a relatively uniform outer surface. It is not necessary to remove the material build-up 41 completely. Preferably, only parts of the build-up 41 should be removed. The partial removal of the material build-up 41 will reduce overall wear of the scraper 100 as it is exposed to a significantly less degree of wear when positioned further away from the roller surface 37. It has been realized that a preferred position of the scraper 100 may be when the scraper 100 is positioned such that a minimum roller distance S1 between each of the at least one scraper 100 and the outer surface 37 of the roller 3 is at least 70% of the minimum gap M. The minimum roller distance S1 is defined in FIG. 3B. It should be noted that for the example embodiment illustrated in FIG. 3B, the scraper 100 is structured and arranged such that the distance between the scraper 100 and the outer surface 37 of the roller 3 is substantially constant. This implies that the minimum roller distance S1 will coincide with said the substantially constant distance. However, for other not disclosed embodiments, the scraper may be structured and/or arranged such that the distance between the scraper 100 and the outer surface 37 of the roller 3 varies. For such an embodiment, the minimum roller distance S1 will be the shortest distance between the scraper and the outer surface 37 of the roller 3. At this position of the scraper 100 with a minimum roller distance S1, the roller crusher 1 may be in operation for economically acceptable time periods before the scraper 100 has been worn down to an extent at which the distance between the scraper 100 and the outer surface 37 of the roller 3 will become close to the minimum gap M, and the scraper 100 has to be either adjusted in position or replaced. As illustrated in FIG. 3B, the scraper 100 is positioned at a minimum flange distance S2 from the inner surface of the flange 26. As can be seen in FIGS. 3A and B, this minimum flange distance S2 is larger than the distance F between the roller 4 and the inner surface 39 of the flange 36. This may appear somewhat surprising, as it can be expected that the scraper 100 may miss removing material necessary to be removed in order to completely avoid contact between roller 4 and the material build-up 41. However, positioning the scraper 100 closer to the flange 36 is associated with other disadvantages. Firstly, it increases the risk of the scraper 100 being damaged by the flange 36 and/or material build-up 41 on the flange 36, a risk that increases with decreasing distance to any moving surface. Secondly, it increases the risk of damaging the flange 36 itself. By positioning the scraper 100 at a minimum flange distance S2 being larger than the distance F, a reasonable trade-off is obtained. A sufficient amount of material is removed from the build-up material 41 at the flange 36, while keeping the scraper 100 at a safe distance from the flange, which results in a prolonged scraper life as well as flange life. Preferably, the scraper 100 is positioned such that a minimum flange distance S2 between the at least one scraper 100 and an inner surface 39 of the flange 36 is 1-25 mm. More preferably, the scraper 100 is positioned such that a minimum flange distance S2 between the at least one scraper 100 and an inner surface 39 of the flange 36 is at least 11 mm. The risk of flange damage has been found to be significantly reduced at this distance. Needless to say, flange bending is unwanted as it will allow material to slip out from the crusher gap at the sides, hence leading to parts of the material bypassing the roller crusher, with an end result that the material output from the roller crusher will not have the specified size distribution.
[0190] The scraper 100 is only schematically illustrated in FIGS. 3B and 3C to allow defining the preferred position of the scraper 100 in relation to the roller crusher 1, or more specifically, in relation to the roller surface 37 and/or flange 36. Turning instead to FIGS. 4 to 8, it will be described in detail how scrapers, such as the scraper 100 of FIG. 3B, may be used in combination on a roller crusher.
[0191] FIGS. 4A to D illustrates four different example embodiments of a scraper assembly for a roller crusher. For each scraper included in these assemblies, the preferred positioning described hereinabove with reference to scraper 100 in FIG. 3B may apply. When describing the example embodiments, focus will instead be put on the differences between the individual scrapers with regards to positioning as well as other properties.
[0192] FIG. 4A illustrates a scraper assembly 1000 according to a first example embodiment. The scraper assembly 1000 consists of two scrapers 100a, 100b arranged consecutively to each other at an end of the roller 3 with flange 36. The scrapers 100a, 100b are positioned in relation to the roller 3 such that the scraper is located at the same or substantially the same minimum distance from the roller surface 37 (in other words: the same minimum roller distance S1, see FIG. 3B). Furthermore, the scrapers 100a, 100b are positioned such that the scraper is located at the same or substantially the same minimum distance from the flange 36 (in other words: the same minimum flange distance S2, see FIG. 3B). Thus, for the scraper assembly 1000, the front scraper, i.e. scraper 100a, will, at least the first time period after installation of the scraper assembly 100, be the only scraper actually performing any material removal. This is illustrated in FIG. 4A by only the front scraper 100a removing material 60a. Scraper 100b will act as a pure backup scraper, in case the front scraper 100a fails. This is advantageous as it prolongs the time period of operation before the crusher has to be shut down for replacement.
[0193] With time in operation, the wear elements 102a, 102b of front scraper 100a will gradually be worn, thus effectively moving the scraper away from the roller surface 37 and/or inner surface 39 of the flange 36. This wear process will lead to increasingly more material of the material build-up 41 not being removed by the first scraper 100a, resulting in an increasing thickness of the material build-up 41 advancing towards the second scraper 100b. Since the second scraper 100b was initially positioned in the same relative position with respect to the roller surface 37 and flange 36 as the front scraper 100a, it has thus far been protected from wear by the front scraper 100a. This means that the second scraper 100b will at this time still maintain its original minimum distance to the roller surface 37. Consequently, the second scraper 100b is now available to remove the excess material that the worn front scraper 100a is not any more able to remove. This way, the second scraper 100b will, with wear, become increasingly more important to overall material removal of the scraper assembly 100. The scraper 100b thus starts of in the role as a pure backup scraper, and end in the role of a scraper in operation. The front 100a and second 100b scraper may each be mounted on a respective holding fixture 110a, 110b which, in turn, may be mounted onto support structure 150, which may be a part of the frame of the roller crusher, or a bracket or supporting element attached to that frame. The holding fixtures will be described in more detail later with reference to FIG. 5.
[0194] FIG. 4B illustrates a scraper assembly 2000 according to a second example embodiment. The scraper assembly 2000 differs from the first embodiment 100 only in so far as scrapers 100a and 100b arranged at different minimum distances from the roller surface 37 (in other words: they have different minimum roller distances S1), with the minimum roller distance S1 being smaller for second scraper 100b than for front scraper 100a. As readily appreciated by the person skilled in the art, this means that both the front scraper 100a and the second scraper 100b will remove material already from start in the first period of operation. This is illustrated in FIG. 4B by only the front scraper 100a removing material 60a and the second scraper 100b removing material 60b. Consequently, the second example embodiment will share the technical effects that the first example embodiment presents after the first time period. The front scraper 100a and second scraper 100b are preferably positions to have the same or substantially the same minimum distance from the inner surface of the flange (i.e. as for the first example embodiment). However, it is also conceivable that the second scraper 100b is positioned such that a minimum distance between the scraper 100a and the inner surface 39 of the flange 37 is larger than the corresponding distance for the second scraper 100b (i.e. the minimum flange distance S2 is larger for the front scraper 100a than for the second scraper 100b). As readily appreciated by the person skilled in the art, such a relative positioning provides a similar technical effect as already described for the different minimum roller distances S1.
[0195] FIG. 4C illustrates a scraper assembly 3000 according to a third example embodiment. The scraper assembly 3000 differs from the second example embodiment only in so far as scrapers 100a and 100b are followed by yet another consecutively arranged scraper, third scraper 100c directly followed by a trigger scraper 100t. As illustrated in FIG. 4C, the first three scrapers 100a-c are arranged at different minimum distances from the roller surface 37 (in other words: they have different minimum roller distances S1), with the minimum roller distance S1 gradually decreasing for every consecutive scraper in the line of scrapers starting with front scraper 100a. As readily appreciated by the person skilled in the art, this means that all three scrapers 100a-c will remove material already from the start of operation. This is illustrated in FIG. 4C by the front scraper 100a removing material 60a, the second scraper 100b removing material 60b, and the third scraper 100c removing material 60c. The trigger scraper 100t is arranged at the very end of the line of consecutive scrapers and is therefore acting as a rear scraper. The trigger scraper 100t is arranged at a maximum tolerable distance T from the roller surface 37 and is configured to provide a trigger signal in response to contacting the material build-up 41. In the example embodiment, this is achieved by means of a strain gauge 96 mounted onto the holding fixture 110t. Therefore, during normal operation of the roller crusher, the trigger scraper 100t is not in contact with the material build-up 41. However, with time, the scrapers 100a-c will gradually wear and as a result the material build-up 41 will gradually become thicker and thicker. As the build-up material 41 has reached the maximum tolerable distance T, it will make contact with the trigger scraper 100t. This will create mechanical strain in the holding fixture 110t, which will be reflected in the signal output from the strain gauge 96. Monitoring this signal allows for determining when the acting scrapers, i.e. scraper 100a-c have all served their time and are in need of replacement. Thus, a trigger signal from the strain gauge 96 can be used to determine when the machine must be shut down for scraper replacement. Although preferably not intended to, trigger scraper 100t is still a scraper on its own. This means that if the roller crusher would be operated some time after trigger scraper 100t first induced a signal for crusher shut down, trigger scraper 100t will provide the scraping. Thus, the trigger scraper 100t is more than just a sensorit is also an extra backup scraper. To prevent rolls and/or flange damage, the maximum tolerable distance T may be chosen such that the roller crusher can be operated some time also after scraping with the trigger scraper 100t has commenced. The term trigger scraper should not be construed as meaning a special kind of scraper per se. The scraper 100t may be identical to any other scraper disclosed herein, such as scraper 100a, b and c. The term is instead used to identify a specific scraper among the at least one scraper which specific scraper is configured to act as a sensing means to provide information pertaining the material build-up 41. This may be accomplished in different ways as long as mechanical interaction between the build-up material and the trigger scraper is converted to an output signal.
[0196] FIG. 4D illustrates a scraper assembly 4000 according to a fourth example embodiment. The scraper assembly 4000 differs from the second example embodiment in so far as scrapers 100a and 100b are here mounted on one common holding fixture 410a which together with the scrapers 100a and 100b form a first subset 400a of scrapers and that the scraper assembly 4000 further comprises a second subset 400b of scrapers comprising scrapers 100c and 100d, which second subset 400b is consecutively arranged with the first subset 400a. Each common holding fixture 410a, 410b may be mounted onto support structure 450, which may be a part of the frame of the roller crusher, or a bracket or supporting element attached to that frame. As can be seen in FIG. 4D, the pair of scrapers of a subset are arranged at equal minimum distance S1 from the roller surface. However, the minimum distance S1 for the first subset 400a is larger than the minimum distance S1 for the second subset 400b. As readily appreciated by the person skilled in the art, during the first time period or crushing operation, the first scraper 100a of subset 400a and the first scraper 100c of subset 400b will perform material removal in the same manner as previously described for the scraper assembly 2000 of the second example embodiment. However, a difference between the fourth and second example embodiments is that the fourth example embodiment will provide backup scrapers in the form of a second-in-line scraper in each subset (i.e. scraper 100b for the first subset 400a, and scraper 100d for the second subset 400b). As the scrapers 100a and 100c have become worn, the scrapers 100b and 100d will gradually enter into operation. Thus, the fourth example embodiment provides both a backup and a shared scraping. Another difference between the fourth example embodiment and the previously described example embodiments is that each subset of scrapers 400a, 400b constitutes its own unit. Specifically, front scraper 100a and second scraper 100b of the first subset of scrapers 400a may be mounted on a common fixture 410a and scrapers 100c and 100d of the second subset 400b of scrapers may be mounted onto common holding fixture 410b. The significance of the common holding fixture versus the single holding fixtures of the previous example embodiments will be described in what follows.
[0197] The four example embodiments described hereinabove constitute different combinations or permutations of single inventive aspects, such as the use of two or more scrapers, the use of backup scrapers, the use of scrapers together sharing scraping operation etc. The person skilled in the art realizes that many other combinations of these inventive aspects are possible. For example, a trigger scraper may be added to any one of the other example embodiments or any other example embodiment within the scope of protection of the claims. As another nonlimiting example, two or more scrapers may be arranged with equal minimum distance to the roller surface (minimum roller distance S1) but varying minimum distance to the flange (minimum flange distance S2). Scrapers may also be positioned at different angular positions with respect to the rotational axis of the roller 3. It is conceivable to locate scrapers at basically any angular position along the roller except at the gap. However, preferably the scrapers are arranged at a lower part of the roller crusher. This implies that the scrapers are arranged below a horizontal plane which intersects the rotational axes R1, R2 of the two rollers 3,4. Even more preferably, the scrapers are arranged such that scraping surfaces of the scrapers at least partly face downwards for allowing removed material to leave from the roller and scraping surfaces by gravitational force. Preferably, the scrapers are arranged at about 6 to 9 o'clock, 7-9 o'clock or 7-8 o'clock of the roller 3, when viewing the roller 3 from a side showing clockwise rotation.
[0198] The holding fixtures for the scrapers will now be described in detail with reference to FIGS. 5A and B. FIG. 5A illustrates the scraper assembly 1000 illustrated in FIG. 4A. Each scraper 100a, 100b may be attached to a respective holding fixture 110a, 110b which in turn may be attached to a support structure 150 at a fastening position P2 located at a distance from the outer surface 37 of the roller 3 by means of fasteners 120a, 120b. As illustrated in FIG. 4A, the holding fixture 110a, 110b is shaped in a particular way. In particular, each scraper 100a, 100b is arranged in relation to the roller crusher 1 such that a position P1 of each scraping surface 104 of the scraper 100a, 100b is located at, or consecutive to, a radial axis A which extends from a rotational axis R1 of the roller 3 and through the respective fastening position P2. By this provision, it is ensured that any unintentional movement of the scraper 100a, 100b due to e.g. strong impact forces arising through the interaction with the built-up material 41 will force the scraper to move away from the roller surface 37. This is indicated for scraper 100b in FIG. 5A by the dashed lines illustrating how a broken-off holding fixture 110b and its scraper 100b would pivot clockwise, hence outwardly around its fastening position P2, after having been exposed to a strong impact force. This process implies that fasteners 120b break at fastening position P2. This represents one conceivable way of achieving the preferred effect, namely to intentionally design a weak-spot at the fastening position P2. It is not necessary for the holding fixture to be fixedly attached at the fastening position. It is equally well conceivable that the holding fixture is pivotable attached at the fastening position P2. To ensure that the scraper 100a, 100b is kept in their intended position during operation, such pivotably arranged scrapers may be mechanically locked into said intended positions by means of a locking system such as a gear, cam or the like. One example of this will be given in what follows.
[0199] FIG. 5B illustrates the scraper assembly 4000 illustrated in FIG. 4D. As previously described, scrapers 100a and 100b may here be mounted on common holding fixture 410a which together with the scrapers 100a and 100b form a first subset 400a of scrapers. In the same manner, scrapers 100c and 100d may be mounted on common holding fixture 410b which together with the scrapers 100c and 100d form a second subset 400b of scrapers. Each common holding fixture 410a, 410b may be attached to support structure 450 at a respective fastening position P3. The fastening for this embodiment is however different than for the scraper assembly 3000. Instead of being fastened rigidly by means of fasteners 120a, 120b, the holding fixtures 410a, 410b are instead pivotably fastened and biased towards a working position. This is achieved by means of fasteners 420a and 420b respectively. The bias should be in the magnitude to keep the scrapers 100a-d in working position up to a predetermined threshold force. Again, such a predetermined threshold force is set to ensure that the flanges and/or the outer surface at the end of the roller do not risk of becoming damaged by a collision between a scraper and the non-removable material. Biasing could be achieved by means of a spring. It is also conceivable to use an unbiased pivotable fastening combined with a torque-limiter. For such an embodiment, the holding fixture would be seemingly rigidly attached to the roller crusher until the scrapers have been exposed to a force exceeding a certain threshold force at which the torque limiter is activated and the holding fixture is allowed to swingably move the scrapers away from the roller surface. The toque-limiter may be combined with biasing means, such as a spring.
[0200] Discussing the second subset 400b, since more than one scraper is attached to the same common holding fixture, that holding fixture must preferably be designed such that a position P1 of the two scrapers 100a, 100b is located at, or consecutive to, a radial axis A which extends from a rotational axis R1 of the roller and through the common fastening position R3. This implies that it must be ensured that scraping surfaces 104 of both scraper 100a and scraper 100b is located at, or consecutive to, the radial axis A. This will ensure that any unintentional movement of the scraper 100a, 100b due to e.g. strong impact forces arising through the interaction with the built-up material 41 will force the scraper to move away from the roller surface 37. This is indicated for the second subset 400b of scrapers in FIG. 5B by the dashed lines illustrating how a broken-off first subset 400b of scrapers would pivot clockwise around its respective common fastening position P3, and hence outwardly, after having been exposed to a strong impact force.
[0201] FIG. 6 illustrates already described scraper 100 together with a holding fixture 510 according to another example embodiment. The holding fixture 510 may comprise a square beam 512 structured and arranged to be attachable to a support structure of the roller crusher. Attached to the square beam 512 is bracket 514 which presents an attachment surface 516 with through-holes 518. The scraper 100 is attachable to the bracket 518 via wedge element 520. Wedge element 520 has a first surface 522 configured to be attachable to the attachment surface 516 by fasteners, such as e.g. bolts and screws, and a second surface 524 at which the main body 103 of scraper 100 is attached e.g. by welding. Chain 526 interconnects wedge element 520 with square beam 512 and acts as an extra security measure. In case a sudden impact force would break the attachment between wedge element 520 and bracket 514, the chain 526 will prevent the scraper 100 and wedge element 520 from falling into the material output section of the roller crusher (not shown). This is advantageous as it may prevent damage to underlying structures, such as e.g. conveyor belts, screens, and surfaces of chutes etc.
[0202] FIG. 7 illustrates a scraper assembly 6000 consisting of three scrapers 100 mounted on respective holding fixtures 510 already described with reference to FIG. 6. The three scrapers 100 are here arranged consecutively to each other and the scraper assembly 6000 is intended to be arranged along a roller with a flange in the same manner as previously described with reference to FIGS. 4A to D for at least partially removing material accumulated on the flange and/or on the outer surface at the end of the roller. Each holding fixture 510 is mounted onto the roller crusher via a respective plate 620 which may be attached to frame elements 610. The position of each scraper 100 is adjusted during instalment by carefully adjusting the plate 620 prior to attaching the same to the frame elements 620. The relative position between each scraper and the roller surface and/or flange can be selected in many different ways following what has been outlined before with reference to FIGS. 4A to D. Thus, it is conceivable that the scrapers 100 of scraper assembly 6000 has an equal minimum roller distance S1 to the roller surface 37 but may alternatively have different minimum roller distances S1 to the roller surface 37. In the same manner, it is conceivable that scrapers 100 of the scraper assembly 6000 has an equal minimum flange distance S2 to the inner surface 39 of the flange 36 but may alternatively have different minimum flange distances S2 to the inner surface of the flange.
[0203] FIG. 8 illustrates scraper assembly 7000 according to yet another example embodiment. Scraper assembly 7000 comprises four scrapers 100 arranged in pairs along both ends of a roller 3 having dual flanges 36. Each scraper 100 of a pair is arranged consecutively to the other scraper 100 of that pair and may be mounted according to any one of the previously described combinations or any not described combination within the scope of protection of the claims. In particular, the scrapers 100 of a pair may have substantially the same minimum roller distances S1 and/or minimum flange distances S2 or may have different minimum roller distances S1 and/or minimum flange distances S2. The scrapers 100 are each mounted onto a support structure 710, which in turn is mounted onto the frame of the roller crusher. As readily appreciated by the person skilled in the art, the scraper assembly 7000 is structured and arranged to be located at about 6 to 9 o'clock of the roller 4, when viewing the roller 4 from a side showing clockwise rotation.
[0204] FIG. 9A to C illustrates a scraper assembly 8000 according to another example embodiment. The scraper assembly 8000 comprises a scraper 100 and an air knife 800 arranged consecutive to each other at an end of the roller 3 with a flange 36 for at least partially removing material accumulated on the flange 36 and/or on the outer surface 37 at the end of the roller 3. From here on, scraper 100 will be referred to herein as mechanical scraper 100 to clearly differentiate the same from the air knife 800 which also removes material but not by mechanical interaction (an air knife could be regarded as a non-contact scraper). The air knife 800 is structured and arranged to, at least intermittently, direct an air plume 820 of pressurised air towards a target area 822 located at the outer surface 37 at the end of the roller 3. The air plume 820 provides a sufficient impact of air at the target area 822 for at least partially removing material accumulated thereon. With the term intermittently is here meant that the air knife directs a plume towards the target area at irregular or regular time intervals during operation of the roller crusher. This implies that the air knife may not be in continuous or steady operation. However, for some applications, and some embodiments of the remote material removal device, the device may be in continuous or steady operation.
[0205] The air knife 800 comprises a main body 802 having an elongated extension. For the present example embodiment, the main body 802 is arranged substantially horizontally at a lower part of the roller crusher. Pressurised air is supplied to the air knife 800 through tubing 806 which are connected to a high-pressure air supply 98. The air knife 800 will be described in more detail later. As readily appreciated by the person skilled in the art, the efficiency of material removal will depend both on the distance between an exit nozzle of the air knife and the target area 822, and the angle formed between the air plume 820 and the target area 822. The distance may be within the range 50-500 mm from the target area 822.
[0206] The air knife 800 is an example of a fluid jet knife, which is an example of a class of devices which are capable of removing material from a distance. These devices are referred to herein as remote material removal devices. These devices are configured to output a material removing beam towards a target area and be interaction between the material removing beam and material present at said target area, at least partially remove said material. Dependent on the type of remote material removal device, the material is removed by different processes, such as e.g. mechanical impact, heating, ablation, exothermic reactions etc. The fluid jet knives make us of a high-velocity fluid to remove material by impact. Other examples of remote material removal devices are lasers which may be used to remove material by laser heating and material ablation. Although the example embodiments disclosed herein are mainly focused on air knives, the inventive concept should not be construed as limited thereto, and it is envisaged that any suitable alternative remote material removal device may be used instead of an air knife in any of the example embodiments.
[0207] As illustrated in FIG. 9A, the target area 822 of the air knife 800 is located in front of the mechanical scraper 100. This means that, when in operation, the build-up material 41 at the flange 36 will encounter the target area 822 of the air knife 800 before encountering the mechanical scraper 100. Although the inventive concept is not limited to this particular order, it is regarded as a preferred order, because the air knife 800 can then be used to remove extra hard and/or excessive amounts of build-up material 41 at the flange 36 before said material impinges onto the mechanical scraper 100. As readily appreciated by the person skilled in the art, this reduces the risk of structural damage of the mechanical scraper 100.
[0208] An advantage of the air knife 800 over the mechanical scraper 100 is that the air knife 800 allows controlling. This advantage is equally well applicable for other remote material removal devices, such as fluid jet knives and lasers. Thus, the air knife may be used only at specific positions in time where it is most needed. For the purpose, the air knife 800 may be connected to a control system. The control system may be or form a part of a control system 80 for the roller crusher (illustrated as control system 80 in FIG. 12), a control system of the scraper assembly 8000, or even an external system such as a common control system at the plant. As the roller crusher is started up with clean rollers 3, 4 without any build-up material 41 at the flanges 36, 36, material will, during a first time period of crushing operation, accumulate in the corner transition between the roller surface 37 and the flange 36 so as to create a material build-up 41. During the first time period after startup, such as e.g. the first hour in operation, the material buildup 41 will be relatively soft through the depth of the material, and the mechanical scraper 100 will therefore be able to remove any excess buildup effectively at an acceptable wear rate of the mechanical scraper 100 and acceptable mechanical stress levels on the holding fixture 110 keeping the mechanical scraper 100 in place in relation to the roller crusher. This time period and the operation of the scraper assembly 8000 during the same is illustrated in FIG. 9A.
[0209] After continuous operation of the roller crusher during a longer time period, the material buildup 41 will get increasingly more compacted and thus harden through the depth of the material. This will increase the wear rate of the mechanical scraper 100 as well as the mechanical stress levels on the holding fixture 110, thus increasing the risk of damaging the mechanical scraper 100. This problem may be solved by removing buildup material before it has become too hard by means of the air knife 800. By applying an air plume 820 onto the target area 822 located at an end of the roller 3 with a flange 36, the air plume 820 may remove, in part or in full, the material build-up 41 located there. By removing the material build-up 41, the wear life of the mechanical scraper 100 and its holding fixture 110 will be increased, thus providing a more reliable system for keeping build-up material 41 at the flange within acceptable levels. This is illustrated in FIGS. 8B and C showing the onset of (FIG. 9B) and last phase of (FIG. 9C) a substantially complete removal of the particle build-up 41 using the air knife 800. As indicated in FIG. 9C, the removed material 60a may be guided into a dedicated container 99. The contained 99 may be advantageous as it allows reducing dust cloud formation at the roller crusher when using the air knife.
[0210] The air knife 800 may be operably connected to a control unit. In an example embodiment, the air knife 800 is operably connected to a control unit 80 of the roller crusher. This is illustrated in FIG. 12. The air knife 800 may be controlled in different ways. For example, the air knife 800 may be turned on within predetermined time ranges, such as e.g. every 3rd, 4th, or 5th revolution of the roller 3. Alternatively, the air knife 800 may be turned on at time positions determined by roller crusher monitoring system data pertaining to the build-up level of material accumulated on the flange 36 and/or on the outer surface 37 at the end of the roller 3. Such roller crusher monitoring system data may be obtained by means of a monitoring system 90 of the roller crusher, as will be further described later. It is also preferred to turn on the air knife 800 during a time period prior to shut-down of the roller crusher for allowing removing material accumulated on the flange 36 and/or on the outer surface 37 at the end of the roller 3. By removing the accumulated build-up material 41 prior to shut-down, maintenance of the mechanical scrapers (such as scraper 100), such as replacing, adjusting or inspecting the same, will be easier.
[0211] Within the inventive concept there are several conceivable combinations of mechanical scrapers and remote material removing devices. Specifically, any combination of mechanical scrapers discussed with reference to FIGS. 4 to 8 may be combined with a remote material removing device such as e.g. an air scraper. Serving as non-limiting examples only, FIG. 10 illustrates a scraper assembly 8000 according to an alternative example embodiment. The scraper assembly 8000 differs from scraper assembly 8000 of FIG. 9 in the following: Firstly, instead of a single mechanical scraper, scraper assembly 8000 has three consecutively arranged scrapers 100a, 100b and 100t, of which the first two scrapers 100a, 100b are working scrapers and the last scraper 100t is a trigger scraper. The functionality of the trigger scraper 100t has been detailed with reference to FIG. 4C and will not be repeated here. The two working scrapers 100a, 100b are arranged similarly to the ones previously described with reference to FIG. 4A, i.e. such that the minimum roller distance S1 for scraper 100a is substantially the same as the minimum roller distance S1 for scraper 100b. A further difference is that instead of an air knife, the remote material removing device in scraper assembly 8000 is a high-energy laser. For the example embodiment, a high-energy continuous-wave CO2 laser is used, but other preferably pulsed high-power lasers are also conceivable. The material removing beam, which here thus constitutes laser beam 820, is directed toward the target area 822 and removes build-up material by laser ablation. It may be required to move (i.e. scan) the laser beam during operation to adequately remove the material build-up. This may be achieved by an optical system based on lenses and/or mirrors and are well known in the art.
[0212] FIG. 11 illustrates yet another non-limiting example embodiment, namely scraper assembly 8000. Scraper assembly 8000 differs from scraper assembly 8000 in that the remote material removing device is a water jet knife 800 connected to a pressurized water supply 98 which water jet knife 800 is configured to output a water jet 820 towards target area 822, and that the relative position of the scraper 100 and the water jet knife 800 on the roller crusher is in the region 9 to 12 of the roller, when viewing the roller from a side showing clockwise rotation. An advantage of using a water jet knife over an air jet knife may be reduced dust formation. The advantage of the position may be that the material will be more easily removed from the roller crusher, since the direction of impact is generally downwardsin contrast to the substantially horizontal impact direction of previously described embodiments.
[0213] FIG. 12 illustrates a monitoring system 90 for a roller crusher here exemplified in the context of the scraper assembly 8000. In the example, crushing roller 3 has a flange 36 at which build-up material 41 has been accumulated as described in detail earlier. The monitoring system 90 may comprise a controller connected to a series of sensor peripherals. In the example embodiment illustrated in FIG. 12, the control unit 80 of the roller crusher act as control unit also for the monitoring system 90. Specifically, these sensor peripherals may include first monitoring camera 92 arranged to have the build-up material 41 within view. By analysing the signal transmitted from the first monitoring camera 92, a level of material build-up may be inferred by the control system 80. By allowing the first monitoring camera 92 to view the flange 36, it is also conceivable to infer a degree of flange deformation from an analysis of the signal from the first monitoring camera 92. The monitoring system 90 may further comprise a second monitoring camera 93 arranged to have the scraper 100 and/or the jet plume of the air knife 800 within view. By analysing the signal transmitted from the second monitoring camera 93, the condition of the scraper 100 and/or the air knife 800 may be inferred by the control system 80. The monitoring system 90 may further comprise a plurality of strain gauges 94 arranged on the flange 36. By analysing the signal transmitted by the strain gauges 94, the condition of the flange 36 may be monitored. The strain gauges 94 may be arranged to transmit signals wirelessly. The monitoring system 90 may further comprise a strain gauge 96 mounted onto the scraper 100. By analysing the signal transmitted by the strain gauge 96, the condition of the mechanical scraper 100 may be monitored. Although illustrated here as mounted onto the scraper 100, it is also conceivable to provide a strain gauge on the holding fixture 110.
[0214] FIG. 13A to C illustrates a scraper assembly 9000 according to another example embodiment. The scraper assembly 9000 is similar to the scraper assembly 8000 described earlier and is based on a combination of an air knife and a mechanical scraper. However, the scraper assembly 9000 includes some further features which will now be discussed in detail.
[0215] The scraper assembly 9000 comprises a scraper 900 having two wear elements 904a, 904b. Scraper 900 is mounted onto wedge element 920 which is attached to bracket 914 by bolting. Bracket 914 is attached in beams 912 which may be mounted on a frame of the roller crusher. Openings are provided in both wedge element 920 and bracket 914 which when mounted together forms a through-opening 921 in said elements. The purpose of the through-opening 921 is to allow an air plume 820 from the air knife 800 to pass though the structure. The air jet 800 is disposed with its air nozzle 804 located just behind the through-opening 921. As best illustrated in FIGS. 13B and C the air knife 800 includes a pipe 806 which fluidly connects the air nozzle 804 with an air inlet opening 808 located at the opposite end of the air knife body 802. Immediately downstream of the air inlet opening 808, a valve system 810 is provided. The valve system 810 may be controlled from a distance, such as e.g. by a control system as detailed earlier. The air knife 800 is attached to a supporting structure 960 of the roller crusher by means of beams 926.
[0216] The scraper assembly further comprises a wear-protective arrangement 950 for protecting the air knife 800. For the example embodiment, the wear protective arrangement includes two separate features: Firstly, the body 802 of the air knife 800 is protected by a wear guard 952 disposed on top of the main body 802. The wear guard 952 presents an angled top surface for allowing falling material to be deflected away from the air knife 800. Secondly, the air nozzle 804 of the air knife 800 is protected by means of the bracket 914 and the wedge element 920. As said elements are disposed very close to the air nozzle 804, they will act as a shield for the air nozzle 804, thus protecting the same from foreign objects such as falling crushing material or the like. The through-opening 921 allows for the air plume 820 to pass the wear-protective structure as best illustrated in FIG. 13C.
[0217] FIGS. 14A to 14C illustrate a scraper 200 according to a second example embodiment of the disclosure. The scraper 200 may be used instead of already described scraper 100 substituting the same in any one of the FIGS. 4 to 13. In FIG. 14B the scraper 200 is illustrated in its intended position at a flange 36 of a roller 3. The black arrow indicates the tangential velocity of the rotating roller 3.
[0218] The scraper 200 comprises a scraping element 210. The scraping element 210 has a scraping surface 204. As can be seen in FIGS. 14A to C, the scraping surface 204 is for the scraper 200 defined on a single element, namely the scraping element 210. This differs from the scraper 100 of the first example embodiment, where the scraping surface 104 is defined by wear members 102a and 102b together. Another difference between the scraper 200 and the scraper 100 is that the scraping surface 204 of the scraping element 210 comprises polycrystalline diamond (PCD).
[0219] As readily appreciated by the person skilled in the art, diamond can be one single, continuous crystal or it can be made up of many smaller crystals (polycrystal). Large, clear and transparent single-crystal diamonds are typically used as gemstones. Polycrystalline diamond (PCD) consists of numerous small grains, which are easily seen by the naked eye through strong light absorption and scattering; it is unsuitable for gems and is instead used for industrial applications such as mining and cutting tools. Polycrystalline diamond is often described by the average size (or grain size) of the crystals that make it up. Grain sizes range from nanometres to hundreds of micrometres, usually referred to as nanocrystalline and microcrystalline diamond, respectively.
[0220] For the scraper 200, the scraping element 210 further comprises a wear resistant material in which the polycrystalline diamond (PCD) is at least partly embedded. The polycrystalline diamond (PCD) may in an alternative embodiment be attached to a surface of a wear resistant material of the scraping element 210. For the example embodiment, the wear resistant material is a cemented carbide comprising Tungsten carbide and, as a binder, cobalt. The binder content may typically be 10-15 wt %. Other wear resistant materials are conceivable. Such alternative materials include other ceramic materials, such as Titanium carbides or Vanadium carbides; metal ceramics composite materials, such as cemented carbides e.g. Titanium carbide, Tungsten carbide or Vanadium carbide with cobalt as a binder; or metal matrix composite materials comprising Titanium carbide, Tungsten carbide or Vanadium carbide.
[0221] In one embodiment, the polycrystalline diamond (PCD) is embedded in Tungsten carbide, Vanadium carbide, or Titanium carbide.
[0222] An advantage of the scraping surface 204 comprising the polycrystalline diamond (PCD) is that the wear life of the scraper 200 may be considerably prolonged. Normally such scraping surfaces 204 would comprise wear resistant material such as ceramic or composite materials comprising Tungsten carbide, Titanium carbide, and Vanadium carbide, but with a scraping surface 204 comprising polycrystalline diamond (PCD), the wear life may be prolonged with up to about 50 times in comparison with only comprising e.g. a composite material comprising Tungsten carbide.
[0223] The scraping element may comprise a layer of polycrystalline diamond (PCD). The layer of polycrystalline diamond (PCD) may have a thickness of 0.4 to 3.2 mm, or 1.0 to 2.0 mm, or 1.35 to 1.8 mm, or 1.4 to 1.6 mm, or about 1.5 mm.
[0224] The diamond grain size of the polycrystalline diamond (PCD) of the scraping surface may be 0.8 to 30 m, as determined by image analysis using a Scanning Electron Microscope (SEM).
[0225] The grain size of diamond may be measured by various measurement techniques, such as laser size analysers or scanning electronic microscopes (SEM). One example of a laser size analyser is a Malvern Particle size analyser equipment which is based on laser diffraction. The values determined using the laser size analyser may be the initial diamond grain size that for some embodiments may later be subjected to High Pressure High Temperature Sintering. When the diamond particles have been sintered and compacted to form the polycrystalline diamond (PCD) of the scraping surface, an image analysis by means of scanning electron microscopy is used to determine the end microstructural grain size distribution, i.e. the diamond grain size of the polycrystalline diamond (PCD) of the scraping surface.
[0226] The scraper 200 further comprises a scraper main body 203 which is structured and arranged to support the scraper element 204 during use. The scraper main body 203 may be made from a resilient material such as steel. However, other materials are also conceivable such as hardened white iron and/or manganese steel.
[0227] Although not shown herein, it is also conceivable to provide further surfaces of the scraper element 210 with a polycrystalline diamond (PCD). For example, side surfaces of the scraper element 210 may comprise a polycrystalline diamond (PCD). Termed in an alternative way, the scraping surface 210 may extend to encompass also side surfaces of the scraper element 210.
[0228] The scraping element 210 and the scraper main body may be attached to each other by brazing. However, other alternative attachments are also possible, such as welding, gluing, hook and loop fasteners, screwed or bolted or in combination.
[0229] As best illustrated in FIG. 14B, just like for the scraper 100 illustrated in FIG. 3C, the scraping surface 204 is arranged to incline in a relation to a normal N to the inner surface of the flange 39, and incline such that a distance L1 between the normal N to the inner surface 39 of the flange 36 and the scraping surface 204 decreases towards the flange 36. The advantage of having the scraping surface 204 in an inclination in relation to the normal of the inner surface 39 of the flange 36 with a decreasing distance L1 towards the flange 36, is that the material removed from the position in the corner formed by the outer surface 37 of the roller 3 and the inner surface 39 of the flange 36 will be urged by the inclined scraping surface 204 towards the centre of the roller 3 instead of being squeezed and compacted between the scraper element 210 and the inner surface 39 of the flange 36. For the example embodiment, the scraping surface 204 is substantially planar. Therefore, the varying distance L1 as described hereinabove may, for the example embodiment, be further expressed in terms of an angle defined between the scraping surface 204 and the normal N. This is illustrated in FIG. 14B. The angle may be 1 to 15, or 2 to 10, or 3 to 8, or 4 to 6, or 5.
[0230] The scraper 200 has an extension from the scraping element 210 towards a rear end 209 of the scraper 200. As best illustrated in FIG. 14B, the scraper main body 203 has a surface 206 facing the flange 36 and two surfaces 207, 208 which faces away from the flange 36. Some of these surfaces 206, 207, 208 form oblique angles with the inner surface 39 of the flange 36 when the scraper 200 is mounted in its intended position on the roller crusher 1. In particular, the scraper 200 is structured and arranged such that a distance L2 between the surface 206 facing the flange 36 and an inner surface of the flange 39 decreases towards the scraping element 210 over at least a part of the extension. This shape may allow the material removed from the position in the corner formed by the outer surface 37 of the roller 3 and the inner surface 39 of the flange 36 to be prone to flow along this surface 206 of the scraper 200 facing the flange 36, and as the distance is increasing away from and downstream of the scraping surface 204, the removed material will be allowed to be removed towards the centre of the roller instead of being squeezed and compacted between the scraper 200 and the inner surface 39 of the flange 36. For the example embodiment, the surface 206 is substantially planar. Therefore, the varying distance L2 as described hereinabove may, for the example embodiment, be further expressed in terms of an angle R defined between the surface 206 which faces the flange 36 and the inner surface 39 of the flange 36. This is also illustrated in FIG. 14B. The angle R may be 5 to 25, or 5 to 20, or 5 to 15, or 8 to 12, or 10.
[0231] Moreover, the scraper 200 is further structured and arranged such that a distance L3 between the surface 207, 208 facing away from the flange 36 and an inner surface 39 of the flange 36 decreases towards the scraping element 210 over at least a part of the extension. For the scraper 200, the surface 207 will have this varying distance starting at the minimum distance S3 to the inner surface 39 of the flange 36 and extending away from the inner surface 39 of the flange 36, whereas the surface 208 is substantially parallel with the inner surface 39 of the flange. The surfaces 207, 208 facing away from the flange 36 are opposite to the surface 206 facing the flange 36. Again, the scraper 200 provides a surface 207 which will urge the removed material to be moved towards the centre of the roller 3, which is beneficial. For the example embodiment, the surface 207, 208 facing away from the flange 36 includes surface 207 and surface 208 which are both substantially planar. As clearly illustrated in FIG. 14B, surface 207 is substantially parallel with the inner surface 39 of the flange 36. Therefore, the varying distance L3 as described hereinabove may, for the example embodiment, be further expressed in terms of an angle defined between the surface 207 which faces away from the flange 36 and the inner surface 39 of the flange 36. This is also illustrated in FIG. 14B. The angle may be 5 to 25, or 5 to 20, or 5 to 15, or 8 to 12, or 10. The angle R and the angle may for some embodiments be equal to each other.
[0232] The person skilled in the art realises that it is not only the shape of the scraper, i.e. the scraper main body 203, and the scraper element 210 which must comply to these geometrical restrictions, but also the orientation at which the scraper 200 is mounted to the roller crusher 1. In other words, the scraper 200 is both structured and arranged in relation to the roller crusher 1 to achieve the described technical effect.
[0233] The scraper 200 is, alike in FIG. 6 illustrated, attached to a previously described wedge element 520. Through-holes 527 are used to attach the wedge element 520 to an attachment surface, such as the attachment surface 516 illustrated in FIG. 6, by fasteners. Through-hole 528 is used to connect chain 526 with adjacent structures, such as square beam 512 as illustrated in FIG. 6.
[0234] FIG. 16 illustrates scraper 200 and scraper 200 when installed on a roller crusher. Scraper 200 is differs from scraper 200 only in that it is mirrored since it is arranged at a flange 36 being opposite to the flange 36 where the scraper 200 is arranged. Specifically, FIG. 16 illustrates scraper assembly 7000 according to yet another example embodiment. Scraper assembly 7000 is similar to previously described scraper assembly 7000 but differs in that the scrapers 100 are replaced by the scrapers 200, 200, and that there is only one scraper 200, 200 at each flange 36. In other words, scraper assembly 7000 comprises two scrapers 200, 200, each arranged along a respective end of a roller 3 having dual flanges 36. Each scraper 200, 200 may be mounted according to any one of the previously described combinations or any not described combination within the scope of protection of the claims. The scrapers 200, 200 are each mounted onto a support structure 710, which in turn is mounted onto the frame of the roller crusher. As readily appreciated by the person skilled in the art, the scraper assembly 7000 is structured and arranged to be located at about 6 to 9 o'clock of the roller 4, when viewing the roller 4 from a side showing clockwise rotation.
[0235] FIGS. 15A to 15C illustrate a scraper 300 according to a third example embodiment of the disclosure. The scraper 300 may be used instead of already described scraper 100 or scraper 200 substituting the same in any one of the FIGS. 4 to 14. The scraper 300 differs from the scraper 200 only in that the scraping element 310 comprises a front portion 310a and a back portion 310b which are attached to each other. The front portion 310a has a scraping surface 304. Although the front portion 310a of the scraper 300 and the scraping element 210 of scraper 200 may be embodied differently from each other, such as by choice of wear resistant material, thickness, or the like, it is also conceivable that the front portion 310a of the scraper 300 and the scraping element 210 of scraper 200 are identical to each other. The back portion 310b has a surface 305 which faces the flange 36 and a surface 301 which faces away from the flange 36. The surface 305 and the surface 301 are substantially parallel with each other. Moreover, the surface 305 and the surface 301 may be substantially parallel with the inner surface 39 of the flange 36. It is conceivable that the surface 305 and the surface 301 comprises a polycrystalline diamond (PCD). It is also conceivable that other, or all, side surfaces of the back portion 310b comprises a polycrystalline diamond (PCD). The scraper 300 further comprises a scraper main body 303 which is structured and arranged to support the scraper element 310 during use. The scraper main body 303 may be made from the same kind of materials as previously listed for the scraper main body 203. A difference between the scraper main body 303 and the scraper main body 203 is that the scraper body 303 has a shorter extension from the scraping element 310 to the rear end 309 to accommodate the larger size of the scraping element 310. The scraper element 303 has surfaces 307, 308 which faces away from the flange 36, and surface 306 which faces the flange 36. The shape and the arrangement of the scraper 300, and in particular the scraper main body 303, in relation to the roller 3 may be the same as for the scraper 200, and its scraper main body 203, already described in detail hereinabove. Specifically, the distances L1, L2 and L3 which may be defined for scraping surface 304, and surfaces 307, 308 and 306 may vary in the same general manner as for the scraper 200. The angle intervals for angles , and may also follow the ranges provided hereinabove for the scraper 200.
[0236] The front portion 310a and the back portion 310b may be attached to each other by brazing but may also be manufactured in one piece with the polycrystalline diamond arranged at the scraping surface 304 of the scraping element 310. The back portion 310b and the scraper main body 303 may be attached to each other also by brazing. However, other alternative attachments are also possible, such as welding, gluing, hook and loop fasteners, screwed or bolted or in combination.
[0237] The person skilled in the art realizes that the present disclosure by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed, from a study of the drawings, the disclosure, and the appended claims.
LIST OF EMBODIMENTS
[0238] Embodiment 1. A roller crusher having two generally parallel rollers arranged to rotate in opposite directions, towards each other, and separated by a gap, each roller having two ends, the roller crusher comprising: [0239] a flange attached to at least one of the ends of one of the rollers, [0240] the flange extending in a radial direction of the roller, [0241] the flange having a height (H) above an outer surface of the roller,
[0242] wherein the roller crusher further comprises at least one scraper arranged at an end of the roller with a flange for at least partially removing material accumulated on the flange and/or on the outer surface at the end of the roller, and
[0243] wherein each of the at least one scraper comprises a scraping element having a scraping surface which scraping surface comprises a polycrystalline diamond (PCD).
[0244] Embodiment 2. The roller crusher as claimed in Embodiment 1, wherein the scraping element further comprises a wear resistant material in which the polycrystalline diamond (PCD) is at least partly embedded.
[0245] Embodiment 3. The roller crusher as claimed in Embodiment 2, wherein the wear resistant material is one from the list of: a ceramic material, a metal ceramic composite material, and a metal matrix composite material.
[0246] Embodiment 4. The roller crusher as claimed in any one of Embodiment 1 to 3, wherein the scraping surface of the at least one scraper is arranged to incline in a relation to a normal to the inner surface of the flange, and incline such that a distance between the normal to the inner surface of the flange and the scraping surface decreases towards the flange.
[0247] Embodiment 5. The roller crusher as claimed in any one of Embodiment 1 to 4, wherein the at least one scraper has a surface facing the flange, which surface has an extension from the scraping element towards a rear end of the at least one scraper, wherein the at least one scraper is structured and arranged such that a distance between the surface facing the flange and an inner surface of the flange decreases towards the scraping element over at least a part of the extension.
[0248] Embodiment 6. The roller crusher as claimed in any one of Embodiment 1 to 5, wherein the at least one scraper has a surface facing away from the flange, which surface has an extension from the scraping element towards a rear end of the at least one scraper, wherein the at least one scraper is structured and arranged such that a distance between the surface facing away from the flange and an inner surface of the flange decreases towards the scraping element over at least a part of the extension.
[0249] Embodiment 7. The roller crusher as claimed in any one of Embodiment 1 to 6, wherein the scraping element comprises a front portion and a back portion which are attached to each other, and wherein the front portion has the scraping surface.
[0250] Embodiment 8. The roller crusher as claimed in Embodiment 7, wherein the back portion has a surface facing the flange and a surface facing away from the flange, said surfaces being substantially parallel with an inner surface of the flange.
[0251] Embodiment 9. The roller crusher as claimed in any one of Embodiment 1 to 8, wherein the at least one scraper is arranged at a lower part of the roller crusher.
[0252] Embodiment 10. The roller crusher as claimed in any one of Embodiment 1 to 9, wherein the at least one scraper is arranged such that the scraping surface of the at least one scraper at least partly faces downwards for allowing removed material to leave from the roller and the scraping surface by gravitational force.
[0253] Embodiment 11. The roller crusher as claimed in any one of Embodiment 1 to 10, wherein the at least one scraper has a fastening position located at a distance from the outer surface of the roller, wherein the at least one scraper is arranged such that a position of the scraping surface of the at least one scraper is located at, or consecutive to, a radial axis which extends from a rotational axis of the roller and through the fastening position.
[0254] Embodiment 12. The roller crusher as claimed in any one of Embodiment 1 to 11, wherein the roller crusher further comprises at least one holding fixture for the at least one scraper, which at least one holding fixture connects to a frame of the roller crusher at a fastening position of the at least one scraper.
[0255] Embodiment 13. The roller crusher as claimed in Embodiment 12, wherein the at least one holding fixture comprises at least one bracket and at least one wedge element, which wedge element is structured and arranged to attach the at least one scraper to the at least one bracket such that an angular position of the at least one scraper is shifted in relation to an angular position of the at least one bracket in a rotational plane of the roller.
[0256] Embodiment 14. The roller crusher as claimed in any one of Embodiment 1 to 13, wherein the roller crusher further comprises a flexible retaining arrangement arranged to intercouple at the at least one scraper with a frame of the roller crusher.
[0257] Embodiment 15. The roller crusher as claimed in any one of Embodiment 1 to 14, wherein the at least one scraper is at least two scrapers arranged consecutive to each other at an end of the roller with a flange for at least partially removing material accumulated on the flange and/or on the outer surface at the end of the roller.
[0258] Embodiment 16. The roller crusher as claimed in Embodiment 15, wherein the at least two consecutive scrapers are arranged at equal distances to the flange and/or to the outer surface at the end of the roller.
[0259] Embodiment 17. The roller crusher as claimed in Embodiment 15, wherein the at least two consecutive scrapers are arranged at different distances to the flange and/or to the outer surface at the end of the roller.
[0260] Embodiment 18. The roller crusher as claimed in Embodiment 17, wherein the at least two consecutive scrapers are arranged in decreasing distance from the flange and/or from the outer surface of the roller seen from a front scraper to consecutive scraper(s).
[0261] Embodiment 19. The roller crusher as claimed in Embodiment 17, wherein the at least two consecutive scrapers comprise at least two subsets of at least two consecutive scrapers, wherein the at least two consecutive scrapers within each subset are arranged at the same distance from the flange and/or roller surface, and wherein the at least two subsets of consecutive scrapers are arranged at different distance to the flange and/or the outer surface at the end of the roller.
[0262] Embodiment 20. The roller crusher as claimed in Embodiment 19, wherein the at least two subsets of consecutive scrapers are arranged at a decreasing distances to the flange and/or the outer surface at the end of the roller seen from a front subset to consecutive subset(s).
[0263] Embodiment 21. The roller crusher as claimed in any one of Embodiment 1 to 20, wherein the roller crusher comprises two flanges attached to opposite ends of one of the rollers, and wherein the at least one scraper comprises a first subset of at least one scraper and a second subset of at least one scraper which first and second subsets are each disposed on a respective end region of the roller with the two flanges.
[0264] Embodiment 22. The roller crusher as claimed in any one of Embodiment 1 to 21, wherein the roller crusher further comprises a remote material removal device configured to output a material removing beam towards a target area, wherein the remote material removal device and the at least one scraper are arranged consecutive to each other at an end of the roller with a flange for at least partially removing material accumulated on the flange and/or on the outer surface at the end of the roller.
[0265] Embodiment 23. The roller crusher as claimed in Embodiment 22, wherein the target area of the remote material removal device is located in front of the at least one scraper.
