Technical Field

[0001] The invention relates to a flexible abrasive member comprising a substrate which carries deposits with embedded abrasive particles, and to a belt, disc, sheet, cylinder, reamer, or block comprising such a flexible abrasive member. Furthermore, the invention relates to method for manufacturing such flexible abrasive members.

Background Art

[0002] Such a flexible abrasive member is generally known and can be used for various kinds of grinding or polishing operations. Such operations may include the treatment of stone, marble, or wooden objects, such as floors, furniture and the like. Also the treatment of glass and the like is possible, for instance for working the edges of a glass panel. Grinding or polishing treatment may also be performed on metals (e.g. aluminum, titanium, steel), ceramics (e.g. tungsten carbide), composites, other rock types (e.g. granite), etc. Depending on the product to be treated, the flexible abrasive member may be applied in the form of a belt, a block, a disc, a sheet, a cylinder, or a reamer.

[0003] An example of a flexible abrasive member is described in EP-A-910496. This known flexible member has certain advantages both with respect to useful life, the quality of the polishing and grinding process and the production time required. Nevertheless further improvements are desirable.

[0004] Furthermore, various methods are known for manufacturing flexible abrasive members, such as electroplating, electroless plating, gas deposition, sintering, or screening by using resin. A well-known and preferred method is electroplating, which allows a mixture of metal particles and abrasive particles to be electro-deposited on a metallized screen. Presently known deposit patterns may exhibit a less than optimum distribution of the metal and abrasive particles.

[0005] It would be desirable to provide a flexible abrasive member which offers the possibility to obtain a higher production output while avoiding a higher production time. It may also be desirable to provide a flexible abrasive member which offers a stronger and/or more aggressive polishing and/or grinding action, without undue extension of production time. It may further be desirable to provide a flexible abrasive member which allows a more efficient way of manufacturing a deposit pattern with regularly distributed metal particles and abrasive particles.

Summary of Invention

[0006] Therefore, according to a first aspect of the invention, there is provided a flexible abrasive member comprising a substrate, which carries a plurality of deposits with embedded abrasive particles. Each deposit has an elongated continuous structure that extends along a center trajectory predominantly in a longitudinal direction X across the substrate. The structure of a deposit comprises inset portions and recessed portions, which protrude in opposite transverse directions from the center trajectory. The inset portions of a deposit are accommodated in recessed portions of a preceding deposit, and the recessed portions of the deposit accommodate inset portions of a following deposit, so that the inset portions and recessed portions of neighboring deposits mutually overlap in said transverse directions.

[0007] The pattern of elongated continuous structures has several advantages. It provides an increased mechanical strength to the flexible abrasive member which results from the interlocking portions. These parts protect the porous layer against extreme deformations which otherwise may occur under the loads exerted between the flexible abrasive member and the object under treatment.

[0008] In the flexible abrasive members according to this aspect, the substrate surface is associated with longitudinal and transverse directions X, Y. The transverse direction Y preferably corresponds to the direction in which the substrate of the abrasive member is to be tensioned or otherwise subjected to force, in order to cause motion relative to the object to be treated (e.g . ground or polished). The overlap of inset portions and recessed portions of neighboring deposits implies that (at least part of) the inset and recessed portions extend along each other in the transverse directions ±Y, and partly cover each other if viewed along the longitudinal direction X. This does not necessarily imply that the inset and recessed portions are in direct physical contact. Instead, the mutually overlapping inset and recessed portions may be spaced along the longitudinal direction X by an intermediate void (or by a structure of a different material). Due to the overlapping arrangement of inset and recessed portions of neighboring deposits, the resistance against tearing of the porous layer is increased as well.

[0009] Furthermore, the relatively long dimensions of the deposits or elongated structures have a favorable influence on heat dissipation. In use heat is generated due to frictional forces between the flexible abrasive member and the object; the heat which is locally generated is dissipated via the elongated structures thus avoiding overheating and deterioration of the flexible abrasive member.

[0010] The deposits may be arranged on the substrate in various ways. According to a preferred embodiment, each deposit extends up to at least one of opposite boundaries of the porous layer. More preferably, each deposit extends up to two opposite boundaries of the porous layer. Such arrangement is useful in case the deposits are obtained through electro-deposition, as will be addressed below.

[001 1 ] In embodiments, the center trajectories of the elongated deposit structures are linear and correspond to longitudinal axes that extend mutually parallel across the substrate. Preferably, the center trajectories of all deposits are parallel to each other.

[0012] The inset portions and recessed portions of the elongated structures may have any desirable shape, such an undulating shape or an angular shape. Preference is given to an embodiment wherein the elongated structure of each deposit comprises transverse segments, which extend with a substantial component or entirely along the transverse directions, and which are mutually spaced in the longitudinal and transverse directions. The transverse segments may be parallel to each other, and perpendicular to the longitudinal direction. [0013] The transverse segments form successive portions of the elongated structure of a deposit. The successive transverse segments may be interconnected via oblique segments, so that the deposit forms a piecewise linear structure.

[0014] The transverse segments may have local widths W that are substantially identical. The oblique segments may also have identical local widths W, so that the deposit forms a piecewise linear strip-shaped structure that has a uniform width W along the entire structure.

[0015] In embodiments, the inset portion comprises a first pair of transverse segments that extend alongside each other to protrude from one side of the center trajectory. This first pair of transverse segments jointly define an external dimension along the longitudinal direction. In addition, the recessed portion may comprise a second pair of transverse segments that extend alongside each to protrude from an opposite side of the center trajectory. This second pair of transverse segments are mutually spaced along the longitudinal direction over an internal dimension that is larger than the external dimension.

[0016] The deposits are nested into each other by virtue of their meandering (e.g. undulated, seesaw, or zigzag) shape. This arrangement results in a greatly enhanced stability of the flexible abrasive member, even under high loadings and temperatures.

[0017] In embodiments, an inset portion and a recessed portion of one deposit jointly form a unit cell. The elongated structure of each deposit may then comprises a periodic sequence of such unit cells that are interconnected and extend along the center trajectory. Such unit cells may for instance be formed by a piecewise linear sequence of interconnected linear deposit segments. To improve the tearing strength of such abrasive member in the transverse direction Y, all these line segments preferably extend with a non-zero component along the transverse direction Y.

[0018] In a further embodiment, the unit cell extends with a unit length AXu along the longitudinal direction. Adjacent distal segments of two subsequent recess portions of a deposit may then jointly form a further inset portion that is congruent to an inset portion, so that the sequence of unit cells is symmetric over a transformation that consists of (i) a 180° rotation of the sequence about the nominal axis and a translation of the sequence over half a cell length ½ AXu along the nominal axis, or of (ii) a reflection of the sequence with respect to the nominal axis and a translation of the sequence over half a cell length along the nominal axis.

[0019] An inset portion of a deposit and an inset portion of a following deposit may jointly border a void from longitudinal and transverse directions. The substrate is exposed through such a void, which may contribute to improved cooling rates during grinding or polishing operations. Different sizes (i.e. surface areas) of the voids may be selected to achieve desired cooling rates and/or grinding/polishing rates.

[0020] Alternatively, the inset portion may form a first transverse tongue segment, which protrudes on one side from the center trajectory and has an external dimension along the longitudinal direction. In addition, the recessed portion may be formed between two second transverse tongue segments, which protrude on an opposite side from the center trajectory, and are mutually spaced along the longitudinal direction over an internal dimension that is larger than the external dimension. [0021] The tongue segments form continuous patches of (abrasive) deposit material. These continuous patches may help to prolong the technical lifespan of the abrasive member. In addition, use of an abrasive member with tongue segments including fine grit abrasive particles may yield improved finishing of a treated product.

[0022] The first tongue segments and second tongue segments may have congruent shapes. Alternatively or in addition, the first tongue segments may be interconnected with the second tongue segments via medial oblique segments.

[0023] The flexible abrasive member may be manufactured in several ways, as mentioned before. Preference is given to a manufacturing process based on electrodeposition. In that case, the substrate may comprise a porous layer (such as a metallized wire mesh), and the deposits may be formed by electrodeposition of metal (e.g. nickel) containing abrasive particles (e.g. diamond particles). The elongated structures lend themselves in particular for an efficient application of electric current and voltage distribution, whereby the electro-deposition process is enhanced. As an example, the metallized wire mesh and the metal deposition comprise nickel. Another manufacturing process may be based on automated liquid resin deposition deposited on fabrics, like woven fabrics or non-woven fabrics made from e.g. cotton or polyester.

[0024] According to further aspects, there is provided a belt, a disc, a sheet, a cylinder, a reamer, or a block for carrying out a grinding and/or polishing process, wherein the belt, disc, sheet, cylinder, reamer, or block comprises a flexible abrasive member in accordance with the first aspect.

Brief Description of Drawings

[0025] Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts. In the drawings, like numerals designate like elements. Multiple instances of an element may each include separate letters appended to the reference number. For example, two instances of a particular element "20" may be labeled as "20a" and "20b". The reference number may be used without an appended letter (e.g. "20") to generally refer to an unspecified instance or to all instances of that element, while the reference number will include an appended letter (e.g. "20a") to refer to a specific instance of the element.

[0026] Figure 1 shows a top view of the abrasive member according to an embodiment;

[0027] Figure 2 shows a cross-sectional side view of a portion of the abrasive member according to II in figure 1 ;

[0028] Figure 3 shows a top view of a portion of the abrasive member according to figure 1 , and

[0029] Figure 4 shows a top view of a portion of an abrasive member according to an alternative embodiment.

[0030] The figures are meant for illustrative purposes only, and do not serve as restriction of the scope or the protection as laid down by the claims. Description of Embodiments

[0031] The following is a description of certain embodiments of the invention, given by way of example only and with reference to the figures.

[0032] The flexible abrasive member 10 according to figures 1-3 has a substrate 12 in the form of the porous layer, which can be carried out as a wire mesh. This wire mesh may be formed of a plastic coated with a metal such as nickel. By means of electrodeposition, a mixture of metal and abrasive particles and metal particles 22 can be deposed onto the porous layer 12. Thereby, deposits 20a, 20b, 20c, 20d, 20e, etc. are formed, which include metal and abrasive particles 22 embedded therein. Figure 1 shows a top view of the abrasive member 10, along a normal direction Z and onto the substrate 12 that extends along a longitudinal direction X and a transverse direction Y. Figure 2 depicts a cross-sectional side view of a portion of the abrasive member 10 according to section II in figure 1 , corresponding with a sectional plane along the longitudinal and normal directions X, Z.

[0033] As shown in figures 1 and 3, each of the deposits 20 has a continuous elongated structure. In this exemplary embodiment, the deposits 20 extend in a meandering way between and up to the two opposite boundaries 14, 16 of the porous layer 12. Each deposit 20 extends in the longitudinal direction X along an associated nominal center axis Ax, and has a piecewise- linear meandering shape that is centered on its axis Ax. Each deposit 20 is separated at least in the longitudinal direction X from each of its adjacent two deposits by a non-zero inter-deposit spacing, which is in the order of millimeters or less.

[0034] Each deposit 20 comprises a plurality of inset portions 24 and recessed portions 26, which protrude in opposite transverse directions ±Y from the center axis Ax. The inset portions 24, of a specific deposit 20i (i = b, c, d,...) are accommodated in aligned recessed portions 26i-i of a preceding deposit 20i-i (i-1 = a, b, c, ..). Similarly, the recessed portions 26i of this specific deposit 20i accommodate inset portions 24i+i of a following deposit 20i+i (i+1 = c, d, e, ...). The adjacent inset and recessed portions 24, 26 of all neighboring deposits 20 are arranged in this interlocking manner. As a result, the inset portions 24 and recessed portions 26 of neighboring deposits 20 mutually overlap in the transverse directions ±Y.

[0035] Figure 3 shows a top view of a portion of the exemplary abrasive member 10 from figures 1-2 in more detail. In this example, the elongated structure of each deposit 20 comprises transverse segments 30, 32, 34, 36 and oblique segments 40, 42, 44, 46, 48, 50, which jointly form a piecewise linear structure. The transverse segments 30-36 and the oblique segments 40- 50 have local widths W that are substantially identical. The transverse segments 30-36 and oblique segments 40-50 of each elongated structure 20 form the inset portions 24 and the recessed portions 26 mentioned above. The inset portions 24 and recessed portions 26 of each deposit 20 protrude in opposite transverse directions ±Y away from the center axis Ax of this deposit 20, and in this example upwards and downwards respectively. It should be understood that the directional definitions and orientations presented herein merely serve to elucidate geometrical relations for specific embodiments. Directional terms in the specification and claims (e.g. "upwards" and "downwards") are used herein solely to indicate relative directions and are not otherwise intended to limit the scope of the invention or claims.

[0036] As illustrated in figure 3, an inset portion 24b and a recessed portion 26b of one deposit 20b jointly form a unit cell 28. The unit cell 28 spans over a unit length AXu along the longitudinal direction X. The unit cells 28 of the deposit 20b are interconnected and extend along the center axis Ax, to form a periodic sequence of unit cells.

[0037] The inset portion 24b comprises a first pair of transverse segments 32, 34, which extend alongside each other and along the positive transverse direction +Y, and protrude upwards away from the center axis Ax. The first transverse segments 32, 34 jointly define an external dimension ΔΧ1 along the longitudinal direction X. The recessed portion 26b comprises a second pair of transverse segments 30, 36, which extend alongside each other and along the negative transverse direction -Y, and protrude downwards away from the center axis Ax. The second transverse segments 30, 36 are mutually spaced along the longitudinal direction X over an internal dimension ΔΧ2. This internal dimension ΔΧ2 is larger than the external dimension ΔΧ1 of the first transverse segments 32, 34. This allows an inset portion 24c of a following deposit 20c to be accommodated in the recessed portion 26b of this one deposit 20b, with a mutual overlap along the transverse direction Y. A non-zero inter-deposit spacing along the longitudinal direction X, which is defined between the first transverse segment 34 of deposit 20b and a second transverse segment 36 of deposit 20a, and which can be associated with a distance ½ (ΔΧ2 - ΔΧ1 ), is in the order of millimeters or less. Similar non-zero inter-deposit spacings are defined between other first and second transverse segments of directly adjacent deposits.

[0038] By forming all unit cells and all deposits 20 in the same manner, al inset and recessed portions of neighboring deposits 20 can be accommodated in similar overlapping manner. In alternative embodiments, the inset portions and/or recessed portions may be formed by more than two transverse segments

[0039] Successive transverse segments 30-36 are pair-wise interconnected via the oblique segments 40-50, to form the meandering piece-wise linear structure. Each of the first transverse segments 32, 34 is connected to one of a second transverse segment 30, 36 via a first medial segment 40 or a second medial segment 42. The medial segments 40, 42 extend obliquely to the longitudinal and transverse directions X, Y and cross the center axis Ax.

[0040] The first transverse segments 32, 34 are mutually interconnected via distal segments 44, 46, 48, 50, which also extend obliquely to the longitudinal and transverse directions X, Y. A first distal segment 44 of the depicted unit cell is connected to a fourth distal oblique segment of a preceding unit cell. Similarly, the fourth distal oblique segment 50 of the depicted unit cell is connected to a first distal oblique segment of a following unit cell. The transverse segments 30, 36 and the oblique segments 44, 50 of subsequent recess portions 26 are thus interconnected, to jointly form lower inset portions that are congruent to the upper inset portions 24. The resulting sequence of unit cells is symmetric over a transformation that consists of a 180° rotation of the sequence about the center axis Ax and a translation of the sequence over half a cell length Vr/sX along the center axis Ax. [0041] Each time, an inset portion 24b of a deposit 20b and an inset portion 24c of a following deposit 20c jointly border a void 52, viewed along the longitudinal and transverse directions X, Y. The substrate 12 is exposed via this void 52, if viewed along the normal direction Z.

[0042] Figure 4 shows a top view of a portion of an alternative embodiment of a flexible abrasive member 1 10. Features that have already been described above with reference to the abrasive member 10 in figures 1-3 may also be present in this abrasive member 1 10, and will not all be discussed here again. For the discussion with reference to figure 4, like features are designated with similar reference numerals preceded by 100 to distinguish the embodiments.

[0043] The inset portions 124 of this flexible abrasive member 1 10 comprises first transverse tongue segments 137 that protrude on an upper side from the center axis Ax. Each first tongue segment 137 forms a continuous patch of deposit material including metal and abrasive particles, and has an external dimension ΔΧ1 along the longitudinal direction X. Recessed portions 126 are each formed between two subsequent second transverse tongue segments 138, 139. The second tongue segments 138, 139 also form continuous patches, and protrude on a lower side from the center axis Ax. The second tongue segments 138, 139 are mutually spaced along the longitudinal direction X over an internal dimension ΔΧ2 that is larger than the external dimension ΔΧ1 , to accommodate an adjacent first tongue segment 137c of a following deposit 120c.

[0044] The first tongue segments 137 and second tongue segments 138, 139 have congruent shapes, and are pair-wise interconnected via medial oblique segments 140, 142 to form a continuous deposit 120. The resulting sequence of unit cells in each deposit 120 is again symmetric over a transformation that consists of a 180° rotation of the sequence about the center axis Ax and a translation of the sequence over half a cell length ½ AXu along the center axis Ax.

[0045] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. It will be apparent to the person skilled in the art that alternative and equivalent embodiments of the invention can be conceived and reduced to practice. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

List of Reference Symbols

Similar reference numbers that have been used in the description to indicate similar elements (but differing only in the hundreds) should be considered implicitly included.

10 flexible abrasive member

12 substrate

14 first substrate boundary

16 second substrate boundary

20 deposit

22 abrasive particle

24 inset portion

26 recessed portion

28 unit cell

30 first transverse segment

32 second transverse segment

34 third transverse segment

36 fourth transverse segment

40 first medial oblique segment

42 second medial oblique segment

44 first distal oblique segment

46 second distal oblique segment

48 third distal oblique segment

50 fourth distal oblique segment

52 void

137 first tongue segment

138 second tongue segment

139 further second tongue segment

Ax center trajectory (e.g. longitudinal axis)

Ay transverse axis

X first direction (longitudinal direction)

Y second direction (transverse direction)

Z third direction (out-of-substrate i.e. normal direction)

AXu unit cell length

ΔΧ1 inset extent (external dimension)

ΔΧ2 recess extent (internal dimension)

W deposit width