Abstract
Screening media for screening material includes a main body and a plurality of openings extending through the main body between a contact face and back face. The openings are of a shape of a convex and non-regular polygon, and are arranged in an orientation such that a line through the most proximal vertex of the polygon and parallel to a defined material flow direction divides the most proximal interior angle of the polygon. Such a configuration allows the openings to not easily get pegged and to improve screening performance.
Claims
1. A screening media for being arranged in a screening equipment for screening material, the media comprising: a main body having a contact face arranged to contact material to be screened and a back face located opposite the contact face; and a plurality of openings extending through the main body between the contact and back faces, wherein a cross sectional area of the plurality of openings in a plane perpendicular to a thickness of the media is a polygon that is a convex and non-regular polygon, and wherein the plurality of openings are arranged in an orientation such that a line through a most proximal vertex of the polygon and parallel to a defined material flow direction divides a most proximal interior angle of the polygon.
2. The media as claimed in claim 1, wherein the most proximal interior angle is substantially a right angle, and the line through the proximal vertex bisects the most proximal interior angle.
3. The media as claimed in claim 1, wherein the non-regular polygon is a parallelogon being derivable from a regular polygon by expanding the regular polygon in such a way that a separation defined between the most proximal vertex and a most distal vertex is increased, wherein the regular polygon having a side length corresponding to a desired maximal material particle size.
4. The media as claimed in claim 1, wherein the non-regular polygon has a rectangular shape having two short sides, the short sides of the non-regular polygon having a length corresponding to a desired maximal material particle size.
5. The media as claimed in claim 1, wherein the non-regular polygon is a hexagon that includes a first pair of parallel opposite sides, a second pair of parallel opposite sides, and a third pair of parallel opposite sides, the first and second pairs of sides having an equal length, the first and second pairs of sides having a length corresponding to the desired maximal material particle size, the third pair of sides having a shorter length than the first and second pairs of sides, wherein the first and second pairs of sides are perpendicular to each other.
6. The media as claimed in claim 1, wherein the main body has a textured pattern provided at the contact face, the pattern extending over all or a majority of the contact face.
7. The media as claimed in claim 6, wherein the pattern is represented by peaks and troughs at the contact face, a depth of the pattern being defined as a separation distance between projections of the peaks and troughs on an axis parallel to the thickness of the media, wherein the depth of the pattern is in a range of 5% to 70% of a total thickness of the media between the bottom face and the peaks of the contact face.
8. The media as claimed in claim 7, wherein the range of the depth is 0.05 mm to 10 mm.
9. The media as claimed in claim 1, wherein a tessellation scheme of the plurality of openings is a lattice structure.
10. The media as claimed in claim 1, wherein the main body is a single piece of material and is made of a rubber or polymer material.
11. The media as claimed in claim 1, wherein the main body includes at least a first layer and a second layer bonded or attached together to form a composite structure, the first layer defining the contact face and the second layer defining the bottom face, the first layer being made of a first material and the second layer being made of a second material, wherein the second material has material characteristics that are different from material characteristics of the first material.
12. The media as claimed in claim 1, wherein a width, length or diameter of each of the plurality of openings in a plane perpendicular to the thickness of the media is in a range of 1 mm to 50 mm.
13. The media as claimed in claim 1, wherein a cross sectional area of the plurality of openings in a plane perpendicular to the thickness of the media is generally uniform or increases through the thickness of the main body between the contact and bottom faces.
14. The media as claimed in claim 1, wherein the main body includes a support structure for supporting the screening media, the support structure being formed together with the screening media as an integral structure.
15. A screening equipment for screening material, comprising: at least one screening media as claimed in claim 1; a frame for supporting the at least one screening media; and a vibration generating means for imparting circular or reciprocating vibratory motion onto the at least one screening media.
16. A method for processing material in a screening equipment as claimed in claim 15, the screening equipment including the at least one screening media, the method comprising: setting the screening equipment to match a defined material flow direction; generating vibration of the screening media with the screening equipment; and driving the material moving on the screening media or passing through the openings of the screening media by the generated vibration and gravity, wherein a cross sectional area of the plurality of openings of the screening media in a plane perpendicular to the thickness of the media is of a polygon that is convex and non-regular polygon, and wherein a line through a most proximal vertex of the polygon and parallel to the defined material flow direction divides the most proximal interior angle of the polygon.
17. A screening module for screening bulk material, the module comprising: a pair of sidewalls; a plurality of support means, wherein the plurality of support means together with the pair of sidewalls form a frame structure; and at least one screening media as claimed in claim 1, mounted or indirectly mounted upon the plurality of support means and extending between the sidewalls.
18. The screening module as claimed in claim 17, wherein the screening module includes two or more screening media arranged sequentially along the defined material flow direction, wherein a downstream screening media has a lowered contact face relative to an upstream neighbouring screening media.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1) A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:
(2) FIG. 1 is a plan view of a screening media according to a specific implementation of the present invention;
(3) FIG. 2 is a magnified plan view of a part at upper right corner of a screening media of FIG. 1;
(4) FIG. 3A is a cross sectional view taken in the direction of arrows along line I-I of FIG. 1;
(5) FIG. 3B is alternative cross sectional view taken in the direction of arrows along line I-I of FIG. 1;
(6) FIG. 4 is a magnified plan view of a part of a screening media according to another specific implementation of the present invention;
(7) FIG. 5 is a plan view of a screening media according to a further specific implementation of the present invention;
(8) FIG. 6 is a magnified plan view of a part at upper left corner of a screening media of FIG. 5;
(9) FIG. 7 is plan view of a screening media according to another specific implementation of the present invention;
(10) FIG. 8 is a magnified plan view of a part at upper right corner of a screening media of FIG. 7;
(11) FIG. 9 is a magnified section view through part of the screening media of FIG. 4;
(12) FIG. 10 is a perspective view of screening media according to a specific implementation of the present invention;
(13) FIG. 11A is a perspective view of a screening apparatus having lengthwise and widthwise extending support beams to seat screening media between respective sidewalls according to a specific implementation of the present invention;
(14) FIG. 11B is a perspective view of a screening apparatus according to another specific implementation of the present invention;
(15) FIG. 12 is a perspective view of a screening equipment according to a specific implementation of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION
(16) FIG. 1 shows a plan view of screening media 100, also called a screen cloth or a screen mat, which includes a plurality of openings 102 on the main body 101. Openings 102 comprise a generally rectangular cross sectional profile (in the plane of the contact face 301) and comprise a width and a corresponding length in a range 1 mm to 50 mm, typically 10 mm to 20 mm. Accordingly, the contact face 301 is defined in part by what may be regarded as cross beams 103 and 104 that extend between and at least partially define the openings 102. A relative width of the cross beams 103 and 104 (in a plane of contact face 301) is in a range 30% to 60% of the width of the openings 102. A defined flow direction of the material to be screened is indicated generally by arrow 105. The major axes MN of the rectangular apertures incline approximate 45 degrees relative to the material flow direction 105, in counter-clockwise direction from material flow direction 105 as indicated in angle β in FIG. 2. The openings are arranged in a tessellation scheme of a lattice structure, with the intention to ensure structure rigidity, whilst have maximal number of holes on the sheet. The screening sheet 101 may be made of rubber or polymer material such as polyurethane and the like. The openings may be produced by punch or perforation.
(17) Referring to FIG. 3A, a cross sectional view taken in the direction of arrows along line I-I of FIG. 1 is shown, the main body 101 has a contact face 301 adapted to contact material to be screened and a back face 302 opposite to the contact face, the cross-sectional shape profile of the openings is uniform through the thickness of the media 100 between the contact face 301 and the bottom face 302. According to another specific implementation, as shown in FIG. 3B, the width of the openings increases through the media 100 in a direction from the contact face 301 to the bottom face 302 such that a corresponding cross sectional area of the openings 102 perpendicular to the thickness of the media increases from the contact face 301 to the bottom face 302.
(18) FIG. 2 shows a magnified plan view of a part of a screening media shown in FIG. 1. The rectangle hole may have round corners, but not necessarily to be so. The four vertices of the hole are denoted by ABCD, rectangle ABCD may be considered as being scaled from a square AB.sub.1C.sub.1D along the axis OM that is parallel to edge AB. Rectangle AB.sub.1C.sub.1D is seen as a virtual hole, its inscribed circle is subject to and corresponds to the desired maximal material particle size. In this example, the edge AD has a length of 14 mm, AB is 16 mm. The hole is oriented such that diagonal AC.sub.1 is aligned with the material flow direction 105 and bisects the proximal interior angle ∠BAD. Diagonal AC and the line AC.sub.1 (aligned with material flow direction 105) may form an acute angle which may range from 0 to 30 degrees. Now, edges AB and BC, AD and DC form respectively a plow-shaped bank (as the opening sinks below the contact face 301) relative to the material flow direction 105, where the edges AB and BC are substantially normal to each other. According to another specific implementation, edges AB and CD may not necessarily be strictly parallel to each other, certain deviation is acceptable, so are with edges AD and BC.
(19) In the following, the screening process will be illustrated in exemplary scenarios, with aid of virtual square hole AB.sub.1C.sub.1D as comparison. Supposing a particle is moving along direction P.sub.1 or P.sub.2 to enter the hole and approach an end vertex C.sub.1 of the virtual square hole, and is not successful in passing through the virtual hole, it may be stuck there or flit over the hole. However, due to the hole already being scaled to ABCD, the particle shall move further forward along the curve V and may further bump on edge BC and bounce back to the centre of the hole. Considering another scenario: a particle is moving along the plow-shaped bank to enter the hole and reach point Q in direction P.sub.3, but with failure to fall into the virtual hole, probably owing to the speed being a little too high; with the scaled hole, the particle may have further spacing QF to allow it descend until reaching point F (see FIGS. 2 and 3A), due to the drop movement in vertical plane, there is no longer chance for the particle to escape from the hole, but bounce back to further collide with edge CD. This will increase the likelihood of the particle being entrapped by the hole.
(20) FIG. 4 is a magnified plan view of a part of a screening media according to another specific implementation. The screening media has similar structure as in FIGS. 1 to 3, comprising a generally planar shape profile having a generally planar contact face 301 and a generally planar opposite face 302, however, a textured pattern 401 is provided at the contact face 301 that accordingly comprises a surface roughness relative to the bottom face 302 that may be considered to be relatively smooth or non-profiled in comparison. The textured pattern provided at contact face 301 extends over the entire contact face 301 including the cross beams 103 and 104 defined between the openings 102. The textured pattern is formed from peaks 901 and respective troughs 902 that collectively define a repeating pattern at contact face 301. A relative depth of the textured pattern at the contact face 301 (defined as the separation distance between the projections of the peaks 901 and troughs 902 on an axis parallel to the thickness of the media 100) is much less than the total thickness W of the media 100 and the thickness W.sub.1 of the first layer 903. In particular, the depth may be in a range 0.5 mm to 5 mm depending upon the thickness W.sub.1 of the first layer 903.
(21) The textured pattern may be a kind of ‘repeating textured pattern’ encompassing a profiled surface having regions of different height including raised and recessed parts. This term encompasses texturing provided at a surface by any one or a combination of ridges, ribs, lumps, projections, protuberances, grooves, cavities, pimples or channels. This term also encompasses the pattern being a regular repeating pattern and not a random collection of raised or recessed regions so as to be generally consistent and uniform over the contact face.
(22) The texture profile design can be applied to any other embodiments of the present invention.
(23) FIG. 5 discloses a plan view of a screening media according to another embodiment. FIG. 6 is a magnified plan view of a part at upper left corner of a screening media of FIG. 5. The screening media has similar opening shape as in FIGS. 1 to 3, except that the openings are arranged in different orientation. The major axes MN of the rectangular apertures incline about 45 degrees relative to the material flow direction 105, but in clockwise direction from material flow direction 105 as indicated in angle β in FIG. 6. Rectangle opening ABCD may be considered as being scaled from a virtual square opening ABC.sub.1D.sub.1 along the axis NM that is parallel to edge AD, wherein the inscribed circle of ABC.sub.1D.sub.1 corresponds to the desired maximal material particle size. The hole is oriented such that diagonal AC.sub.1 is in line with the material flow direction 105 and bisects the proximal interior angle ∠BAD. Now, edges AB and BC, AD and DC form respectively a plow-shaped bank relative to the material flow direction 105, where the edges AB and BC are substantially normal to each other. With such a design, similar screening efficiency improvement can be achieved as the design shown in FIGS. 1 to 3.
(24) Referring to FIG. 7, a plan view of a screening media according to another specific implementation is shown. FIG. 8 is a magnified plan view of a part of the screening media of FIG. 7. In this design, the openings are in hexagon form, the openings are also arranged in a tessellation scheme of a lattice structure. It is optional that, from consideration of stiffness etc., certain columns 701 and 702 of main body may be not punched with holes, the hexagon opening AB.sub.1BCDD.sub.1 can be considered as being expanded from a virtual square opening AB.sub.1C.sub.1D.sub.1 along the axis AC.sub.1, that is, the area of AB.sub.1C.sub.1D.sub.1 is expanded as if the edge BC and CD are translated respectively along the direction AC.sub.1, wherein the inscribed circle of AB.sub.1C.sub.1D.sub.1 corresponds to the desired maximal material particle size. The hole is oriented such that diagonal AC.sub.1 is in line with the material flow direction 105 and bisects the proximal interior angle ∠B.sub.1AD.sub.1. Now, edges AB.sub.1 together with B.sub.1B and BC, edges AD.sub.1 together with D.sub.1D and DC form respectively a plow-shaped bank relative to the material flow direction 105, where the edges AB.sub.1 and BC are substantially normal to each other. In such a design, edge AB.sub.1 has a length of 14 mm, B.sub.1B is set as 4 mm, similar screening efficiency improvement can be achieved as the design shown in FIGS. 1 to 3.
(25) Analogously, the screening process will be briefly illustrated in a virtual manner, with aid of virtual square hole AB.sub.1C.sub.1D.sub.1 as comparison. Supposing a particle is moving along direction P.sub.1 to enter the hole and approach the end vertex C.sub.1 of the virtual hole, and is not successful in passing through the virtual hole, it may be stuck there or flit the hole. However, due to the hole already being expanded, the particle has further spacing to allow it descend until reaching point C, due to the drop movement in vertical plane (reference to FIG. 3A), there is no longer chance for the particle to escape from the hole, but fall through the hole. If a particle is moving along the plow-shaped bank to enter the hole and reach point Q in direction P.sub.3, the effect is similar as illustrated with respect to FIG. 2.
(26) FIG. 9 shows a magnified section view through part of the screening media of FIG. 4. Screen media 100 according to the specific implementation is formed as a two-piece composite having an uppermost first layer 903 and a lowermost second layer 904, the two layers may be bonded together. First layer 903 is formed from a rubber material whilst second layer 904 is formed from a polyester material having a hardness greater than that of first layer. A thickness W.sub.1 of the first layer is greater than a corresponding thickness W.sub.2 of the second layer 904. According to one specific implementation, a thickness of first layer 903 is in a range 1 mm to 6 mm and the thickness W.sub.2 of second layer 904 is in a range 0.4 mm to 1.0 mm. The function of second layer 904 is to provide rigidity and support to the relatively softer first layer 903.
(27) FIG. 10 discloses a screening media 1000 according to a specific implementation of the present invention. The screening media comprises a screen sheet 1001 and a support structure 1002 at its back face. Support structure 1002 serves as a carrier frame to the relatively softer screen sheet 1001 and provides strength and rigidity. The screen sheet 1001 and support structure 1002 may be made of the same material and be formed into integral structure as a single piece, thus the screening media can be a modular design. Support structure 1002 may include a number of fixing arrangements such as mortise or groove or wedge or tongue etc. 1003 for attaching the screening media 1000 onto a screening equipment, or for inter-connecting to a neighbouring screening media in assembly.
(28) FIG. 11A illustrates a part of a screening apparatus (or called a screen deck, or a screening module) 1100 in which a mat-like screen media 1101 is pre-tensioned to extend lengthwise and widthwise between a pair of respective sidewalls 1104. Media 1101 is supported at its underside by a plurality of lengthwise extending beams 1103 that are in turn mounted on a lower support frame 1102 formed from one or a plurality of cross beams extending between sidewalls 1104. Media 1101 is clamped on to the sidewalls 1104 by clamp bars 1106. The screening apparatus also uses rubber capping 1105 to prevent the screen media from wear. Media 1101 may be pre-tensioned in the widthwise direction between sidewalls 1104 and/or in the lengthwise direction between a first end and a second end (not shown) where the length of the media 1101 corresponds to a flow direction of the material to be screened indicated generally by arrow 105.
(29) FIG. 11B illustrates a part of a screening apparatus 1100 which includes multiple pieces of screen media according to FIG. 10. The screen media are mounted sequentially along the defined material flow direction 105 on a lower support frame 1102 formed from one or a plurality of cross beams extending between sidewalls 1104, the media are arranged in rows transverse to the defined material flow direction 105, a downstream screening media 1101A has a sunk or lower contact face relative to an upstream neighbouring screening media 1101B.
(30) FIG. 12 shows a screening equipment according to a specific implementation of the present invention. The screening equipment 1200 comprises one or more screening media 1202 as disclosed herein (referring to FIGS. 1 to 10), a trough-alike frame 1201 for supporting the screening media 1202, a suspension or articulation mechanism 1203, a vibration generating means 1204 and undercarriage 1205. The frame 1201 is movably coupled to undercarriage 1205 via the suspension mechanism 1203 such as a spring system. Vibration generating means 1204 is adapted to impart consecutive circular or reciprocating vibratory motion onto the screening media, it may include an electric vibration motor (not shown) capable of exerting vertical vibration movements of certain frequency, it is appreciated that other vibration generating means operable to bring back and forth movements of certain frequency may be used. The defined material flow direction 105 of the screening media 1202 is parallel to the sidewalls or longitudinal direction of the screening equipment.
(31) In operation, the screening equipment 1200 is brought to an intended position, the next step is to set the screening equipment to match a defined material flow direction, i.e. to let the defined material flow direction (associated with the screening equipment) be in line with the actual material flow direction; start the motor to generate vibrations onto the screening media; the generated vibration and gravity drive the material moving on the screening media or passing through the openings of the screening media.
(32) It is to be understood that the embodiments of the invention disclosed herein are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.
(33) The forgoing examples are illustrative of the principles of the present invention in one or more particular applications, accordingly, it is not intended that the invention be limited.
