ABRASIVE TOOLS FOR GRINDING AND POLISHING CONCRETE SURFACES

Abstract

An abrasive tool (200) for a floor grinder, the abrasive tool (200) comprising an attachment plate (230) arranged to releasably attach to a tool holder of the floor grinder, the abrasive tool (200) also comprising an abrasive tool section (220) at least partly formed in an abrasive material, wherein the attachment plate (230) comprises a supporting surface (235) at least partly formed in a plastic material, wherein the supporting surface (235) is configured to align with a corresponding surface (510) on the abrasive tool section (220), wherein the attachment plate (230) and the abrasive tool section (220) are held together by one or more welds.

Claims

1. An abrasive tool for a floor grinder, the abrasive tool comprising an attachment plate arranged to releasably attach to a tool holder of the floor grinder, the abrasive tool also comprising an abrasive tool section at least partly formed in an abrasive material, wherein the attachment plate comprises a supporting surface at least partly formed in a plastic material, wherein the supporting surface is configured to align with a corresponding surface on the abrasive tool section, and wherein the attachment plate and the abrasive tool section are held together by one or more welds.

2. The abrasive tool according to claim 1, wherein the one or more welds comprises any of an ultrasonic weld, a laser weld, a vibration weld, or a melted plastic material weld.

3. The abrasive tool according to any previous claim 1, wherein a plurality of protrusions extends from the supporting surface of the attachment plate along a normal vector of the supporting surface.

4. The abrasive tool according to any previous claim 1, wherein the attachment plate comprises a rim portion extending along a perimeter of the supporting surface, wherein the rim portion is arranged to hold the abrasive tool section laterally with respect to the normal vector of the supporting surface.

5. The abrasive tool according to any previous claim 1, wherein the abrasive tool section comprises a planar support element and a plurality of abrasive elements arranged protruding from the planar support element in a direction normal to the supporting surface.

6. The abrasive tool according to claim 1, wherein the abrasive tool section comprises an abrasive material embedded in an at least partly plastic material.

7. The abrasive tool according to claim 6, wherein the plastic material is phenolic novolac.

8. The abrasive tool according to claim 1, wherein the abrasive tool section comprises any of: talc, rubber, silicon carbide, green chromium oxide and diamond granules.

9. The abrasive tool according to claim 1, wherein the abrasive tool section is associated with a grit between 30-200 and wherein the abrasive tool section comprises a relative volume percentage of silicon carbide between 10-20%.

10. The abrasive tool according to claim 1, wherein the abrasive tool section is associated with a grit between 30-200 and wherein the abrasive tool section comprises a relative volume percentage of talc between 5-15%.

11. The abrasive tool according to claim 1, further comprising a cage part, wherein the cage part comprises apertures arranged to receive abrasive elements extending from a planar support element of the abrasive tool section.

12. The abrasive tool according to claim 11, wherein the cage part is at least partly formed in a plastic material and where the cage part is welded to the attachment plate and/or to the abrasive tool section, thereby holding the attachment plate and the abrasive tool section together by the one or more welds.

13. The abrasive tool according to claim 11, wherein the cage part comprises one or more ridges arranged facing in a direction of the attachment plate, wherein the ridges are configured to facilitate ultrasonic welding of the cage part to the attachment plate and/or to the abrasive tool section.

14. The abrasive tool according to claim 11, wherein the cage part comprises at least two apertures, wherein each aperture of the at least two apertures is configured to receive one abrasive element arranged protruding from a planar support element on the abrasive tool section.

15. The abrasive tool according to claim 11, wherein the apertures constitute at least half of a total surface area of the cage part, or wherein one of the apertures is substantially polygon shaped with at least three sides.

16. (canceled)

17. The abrasive tool according to claim 11, wherein the cage part comprises a centrally positioned solid portion.

18. The abrasive tool according to claim 1, wherein the attachment plate comprises two opposing and angled wings for releasably mounting the attachment plate to a tool holder of the floor grinder.

19. A set of tools for injection molding of the attachment plate, the abrasive tool section and the cage part according to claim 11.

20. A method for producing an abrasive tool, the method comprising forming at least an attachment plate and an abrasive tool section, wherein the attachment plate is at least partly formed in a plastic material, the method also comprises assembling the attachment plate and the abrasive tool section, by attaching the components in fixed relation to each other by means of one or more welds.

21. The method according to claim 20, also comprising forming a cage part and assembling the cage part with the attachment plate and the abrasive tool section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present disclosure will now be described in more detail with reference to the appended drawings, where

[0019] FIGS. 1A-B illustrate an example floor grinder;

[0020] FIGS. 2-3 show an abrasive grinding tool for a floor grinder;

[0021] FIGS. 4A-B illustrates an attachment plate for an abrasive tool;

[0022] FIGS. 5A-C illustrates an abrasive tool section for an abrasive tool;

[0023] FIGS. 6A-C illustrates a cage part for an abrasive tool;

[0024] FIG. 7 is a flow chart illustrating a manufacturing method; and

[0025] FIGS. 8-10 show alternative abrasive grinding tools.

DETAILED DESCRIPTION

[0026] The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0027] It is to be understood that the present invention is not limited to the embodiments described herein and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

[0028] FIGS. 1A and 1B illustrate an example floor grinder 100 for processing a concrete surface 101. The floor grinder 100 comprises a first electric motor 110 arranged to rotatably drive a number of tool holders 120 about respective axes A. The tool holders 120 on the example machine 100 are comprised on a rotatable body section 130. This body section is often referred to as a planet. A second optional electric motor 115 is arranged to rotate the planet about a central axis B. The type of drive system shown in FIG. 1 is generally referred to as a planetary drive system. Abrasive tools of varying grit and specifications can be mounted onto the tool holders 120.

[0029] Electrically powered floor grinders like that illustrated in FIG. 1 are generally known. Floor grinders driven by combustion engines, such as propane-fueled combustion engines, are also known. The tools and techniques disclosed herein are applicable with both electrically powered and combustion engine machines.

[0030] The machine 100 can be used to grind and to polish concrete surfaces. Depending on the desired concrete processing operation to be performed, tools of varying grit size are attached to the tool holders 120. The grit size of an abrasive element is usually stated as a number that is inversely related to the abrasive particle size. A small number such as 20 or 40 indicates a coarse grit, while a large number such as 1500 indicates a fine grit. The techniques disclosed herein may be used with advantage for a wide variety of different grit seize, ranging from, e.g., 30 to about 3000.

[0031] The cost of abrasive tools is often a substantial part of the overall cost of concrete surface processing. It is therefore desired to produce abrasive tools in a cost efficient manner. However, the abrasive tools still need to meet requirements on robustness and durability. A tool which breaks during use leads to unwanted delay and may also damage both the concrete surface and the floor grinder.

[0032] The abrasive tools disclosed herein are preferably but not necessarily formed in a plastic material. Plastics are a wide range of synthetic or semi-synthetic materials, that use polymers as a main ingredient. The plasticity during production makes it possible for plastic to be molded, extruded, or pressed into solid objects of various shapes, making it an adaptable material for many different uses. The components disclosed herein are suitable for injection molding, which is the preferred method of manufacturing the components. However, other methods for producing the components of the tools disclosed herein are of course also possible.

[0033] FIG. 2 illustrates an abrasive tool 200 for use, e.g., with the floor grinder 100. FIG. 3 shows an exploded view of the abrasive tool 200. The abrasive tool 200 comprises an attachment plate 230 arranged to releasably attach to a tool holder 120 of the floor grinder 100 by angled wings 310. This mechanism comprises opposing and angled wings 310 for attaching the attachment plate of the abrasive tool 200 to the tool holder 120 is previously known and will therefore not be discussed in more detail herein.

[0034] The abrasive tool 200 comprises an abrasive tool section 220 at least partly formed in an abrasive material. This abrasive material preferably comprises diamond granules held in a supporting matrix of, e.g., phenolic novolac, although other binding matrix materials can also be used. The abrasive tool section 220 comprises two or more protruding abrasive elements (FIG. 2 shows six such protruding elements) which are brought into rotating contact with the concrete surface by the tool holder 120, whereupon the concrete surface is ground or polished, depending on the grit size of the abrasive material.

[0035] Each of the components 210, 220, and 230 in FIG. 3 has a front side and a back side, where the front side of each component faces in the direction of the normal vector N indicated by the arrow in FIG. 3. Thus, the front side of each component faces in the direction of the concrete surface to be processed when the tool is in use, and the back side faces towards the tool holder 120 on the machine 100.

[0036] With reference also to FIGS. 4A and 4B, the attachment plate 230 comprises a supporting surface 235 at least partly formed in a plastic material. This supporting surface 235 is configured to align with a corresponding back surface 510 (shown in FIG. 5B) on the abrasive tool section 220. This means that the front surface of the attachment plate 230, i.e., the surface facing away from the tool holder side of the attachment plate, may be arranged parallel to the back surface of the abrasive tool section 220, such that the two surfaces make contact with each other in a mating position.

[0037] Advantageously, the attachment plate 230 and the abrasive tool section 220 are held together by one or more welds. These welds are preferably ultrasonic welds which can be formed in a cost efficient manner during assembly, and which provide a sufficient bond strength for the abrasive tool. However, other types of welds are also possible, such as laser welds, vibration welds, or simply welds formed by melting plastic components together to form welded sections.

[0038] According to one example, the abrasive tool section 220 is welded directly to the attachment plate.

[0039] According to another example, the abrasive tool section 220 is held in position by a cage part 210 which is welded to the attachment plate 230. In this case the abrasive tool section 220 does not necessarily need to be welded or otherwise directly attached to any other component of the abrasive tool 200, although this is certainly an option also.

[0040] According to a third and preferred example, the abrasive tool section 220 is first welded to the attachment plate 230, whereupon the cage part 210 is welded to the attachment plate to reinforce the abrasive tool structure.

[0041] Further alternatives for assembling an abrasive tool will be discussed below in connection to FIGS. 8-10.

[0042] FIG. 4A shows a front side view of the attachment plate 230 and FIG. 4B shows a back side view of the attachment plate 230, i.e., the side facing the tool holder 120. The front side of the attachment plate 230, as mentioned above, faces in the direction of the concrete surface during a grinding or polishing operation, while the back side of the attachment plate faces towards the tool holder 120 on the floor grinding machine 100. With reference to FIG. 4A, a plurality of protrusions optionally extends from the supporting surface 235 of the attachment plate 230 along the normal vector N of the supporting surface. These protrusions facilitate ultrasonic welding of the abrasive tool section 220 to the attachment plate 230.

[0043] The attachment plate 230 optionally also comprises a rim portion 320 as shown in FIG. 4A extending along a perimeter of the supporting surface 235. This rim portion 320 is arranged to hold the abrasive tool section 220 laterally with respect to the normal vector N of the supporting surface 235 when the supporting surface 235 and the corresponding surface 510 are in contact with each other in the mated position. This rim portion 320 further increases the mechanical integrity of the abrasive tool 200 since the tool is now able to withstand a higher degree of lateral forces.

[0044] The opposing and angled wings 310 configured for mounting the attachment plate to the tool holder 120 are located at an offset 0 from the edge of the attachment plate 230. Thus, the supporting surface 235 extends beyond the opposing and angled wings 310.

[0045] FIGS. 5A-C show views of the abrasive tool section 220; FIG. 5A shows a front side view, FIG. 5B shows a back side view, and FIG. 5C shows a side view. Again, the front side is the side facing the concrete surface during processing, while the back side is the side facing the tool holder. The abrasive tool section 220 illustrated in FIGS. 5A-C comprises a planar support element 530 and a plurality of abrasive elements 520 arranged protruding from the planar support element 530 in a direction D normal to the supporting surface 510. Thus, the abrasive tool section is integrally formed in one piece, which allows for a cost efficient molding process for producing the abrasive tool section in one step. By integrally forming the abrasive elements together with the planar support element an increased mechanical strength is also obtained compared to if separate abrasive elements would have been comprised in the abrasive tool section 220.

[0046] There are at least two abrasive elements 520, and preferably six abrasive elements.

[0047] The abrasive tool section 220 comprises an abrasive material which is preferably embedded in an at least partly plastic material. This allows the abrasive tool section 220 to be ultrasonically welded directly to the attachment plate 230, which is an advantage since it enables a cost efficient assembly. However, it is noted that the abrasive tool section 220 may also be attached by other means of the attachment plate 230, e.g., by means of the cage part 210 which will be discussed below in connection to FIGS. 6A-C. To facilitate ultrasonic welding of the abrasive tool section to other components of the abrasive tool, the abrasive tool section may be at least party formed in the plastic material phenolic novolac, which also contributes to the mechanical integrity and strength of the abrasive tool section.

[0048] Various compositions can be used with advantage for various grit sizes. The table below illustrates a number of examples which have been found to yield favorable results in terms of both concrete processing efficiency, wear rate, and mechanical resilience and endurance. The example grit sizes range from grit which is a relatively coarse grit used for grinding operations, to a very fine grit of 3000 which is suitable for polishing operations. The percentage values given are volume percentages. The diamond concentration in the rightmost column is given in carats per cm.sup.3. It is understood that the relative percentages below are approximate values, and that a similar technical effect can be achieved by altering the relative percentages somewhat.

TABLE-US-00001 Phenolic SiC Green Novolac Talc Rubber 1000 Chromium Diamonds Diamond Grit [%] [%] [%] [%] oxide [%] [%] [cts/cm.sup.3] grit 30 59.75 10 8.5 15 0.1 6.65 1.17 grit 50 59.75 10 8.5 15 0.1 6.65 1.17 grit 100 59.75 10 8.5 15 0.1 6.65 1.17 grit 200 57.71 10 8.5 15 0.1 8.69 1.53 grit 400 53.83 30.79 8.63 0 0.08 6.67 1.174 grit 800 50.52 35.79 8.63 0 0.08 4.98 0.876 grit 1500 50.52 35.79 8.63 0 0.08 4.98 0.876 grit 3000 50.52 35.79 8.63 0 0.08 4.98 0.876

[0049] The silicon carbide (SiC) content of about 15% in the course grit variants 30-200 together with the reduced talc content of about 10% provides for an increased wear resistance at the same time as an improved grinding efficiency is obtained.

[0050] Thus, according to various aspects, the abrasive tool section 220 comprises any of talc, rubber, silicon carbide, green chromium oxide and diamond granules. The abrasive tool section 220 is optionally associated with a grit between 30-200 in which case the abrasive tool section advantageously comprises a relative volume percentage of silicon carbide between 10-20%, and preferably about 15%. Also, the abrasive tool section 220 optionally comprises a relative volume percentage of talc between 5-15%, and preferably about 10%.

[0051] FIGS. 6A-C illustrate an optional cage part 210 which can be used to reinforce the mechanical structure of the abrasive tool 200. This cage part comprises apertures 610 arranged to receive the abrasive elements 520 extending from the planar support element 530 of the abrasive tool section 220. The cage part is then attached to the attachment plate 230 and/or to the abrasive tool section 220 in order to hold the structure together more robustly.

[0052] The cage part 210 may be at least partly formed in a plastic material. In this case the cage part 210 can be ultrasonically welded to the attachment plate 230 and/or to the abrasive tool section 220, thereby holding the attachment plate 230 and the abrasive tool section 220 together by the one or more welds. Towards this end, the abrasive tool 200 may comprise one or more ridges 620 extending from the back side of the cage part in the direction of the attachment plate 230. These ridges are configured to facilitate ultrasonic welding of the cage part 210 to the attachment plate 230 and/or to the abrasive tool section 220.

[0053] According to aspects, the cage part 210 comprises at least two apertures, and preferably six apertures as shown in FIGS. 6A and 6B. Each aperture is configured to receive one abrasive element and has a shape matched to that element, e.g., one of the abrasive elements 520 arranged protruding from the planar support element 530 on the abrasive tool section 220 as shown in FIG. 5A. The apertures in FIGS. 6A and 6B are arranged surrounding a central solid portion 630 of the cage part 210.

[0054] According to aspects, the apertures constitute at least half of a total surface area of the cage part 210. This means that the cage part 210 is shaped as a frame to hold the abrasive tool section in place, and to reinforce the structure, but does not comprise a lot of plastic material. The primary function of the cage part is to keep the abrasive tool section 220 pressed in position against the attachment plate 230.

[0055] The apertures of the cage part 210 are substantially polygon shaped with at least three sides. The cage part 210 illustrated in FIGS. 6A and 6B has two three-sided polygon-shaped apertures and four four-sided polygon-shaped apertures.

[0056] The cage part 210 may, as mentioned above, further comprise a centrally positioned solid portion 630, as shown in FIG. 6A.

[0057] Any of the parts 210, 220, 230 may be formed by an injection molding process in a cost efficient manner.

[0058] FIG. 7 illustrates a method for producing an abrasive tool 200. The method comprises forming S1 at least an attachment plate 230 and an abrasive tool section 220 at least partly from a plastic material, preferably by an injection molding process. The method optionally also comprises forming the cage part 210 discussed above. The method further comprises assembling S2 the attachment plate 230 and the abrasive tool section 220 (and optionally also the cage part 210) and attaching the components in fixed relation to each other by means of one or more welds, where the one or more welds preferably comprise one or more ultra-sonic welds.

[0059] FIGS. 8A-B illustrate an abrasive grinding tool 800 comprising an attachment plate 230 and an abrasive tool section 220. The abrasive tool section 220 is the same as described above, i.e., comprises the same set of optional technical features and advantages. However, the attachment plate 230 is integrally formed with a rim portion 810 which extends along a perimeter of the attachment plate 230 as shown in FIG. 8A. The rim portion 810 is shaped to match the shape of the abrasive tool section 220, such that the abrasive tool section can be snugly received inside the rim portion 810 of the attachment plate 230. The rim portion is arranged to be deformed by melted during assembly of the abrasive tool 800, such that a protuberance is formed which holds the abrasive tool section 220 in position relative to the attachment plate 230. This way a cost effective abrasive tool 800 is produced. It is an advantage that different kinds of grit can be provided by selection of the abrasive tool section to be held in position relative to the attachment plate 230 by the deformed rim portion 810.

[0060] FIGS. 9A-B illustrate another example of how an abrasive tool 900 can be assembled to obtain a cost efficient tool. This abrasive tool 900 comprises an attachment plate 230 where holes 910 have been formed along a circumferential flange or rim portion 920 of the attachment plate 230. An abrasive tool section 220 according to the above discussion is arranged on the attachment plate 230 and held in position by a frame 930 which partly overlaps the abrasive tool section 220 along its periphery as shown in FIG. 9A. The frame 930 comprises pins 940 arranged to be received in the holes 910 when the frame 930 is in mating position with the attachment plate 230, as shown in FIG. 9B. The pins 940 can be secured in the holes by, e.g., melting or gluing.

[0061] FIG. 10 shows yet another example of an abrasive tool 1000. This tool 1000 also comprises an attachment plate 230. This attachment plate has through-holes 1010 for receiving corresponding pins 1020 of a holding plate 1030, which has a shape matched to the abrasive tool section 220, i.e., the holding plate 1030 generally has a shape matched to the plurality of abrasive elements arranged protruding from the planar support element of the abrasive tool section 220, such that the holding plate fits in-between the abrasive elements. The through holes 1010 formed in the attachment plate are matched with corresponding through-holes formed in the abrasive tool section 220. One example of such as shape is the lozenge-shaped holding plate 1030 illustrated in FIG. 10. The pins 1020 can be melted or glued in the mating position, i.e., when the pins are received in the holes of the attachment plate, in order to hold the abrasive tool section 220 in position relative to the attachment plate. The attachment plate may optionally comprise the rim portion 810 discussed above in connection to FIG. 8A, to hold the abrasive tool section in lateral position.

[0062] It is appreciated that the assembly methods shown in FIGS. 8-10 can be combined with the assembly methods discussed in connection to FIGS. 2-6, in order to provide even stronger bonds between the different parts of the abrasive tool.