Grinding tool and method for producing a grinding tool

Abstract

A grinding tool has a main body having at least one fiber ply embedded in a binder. An abrasive layer is arranged on the main body. The at least one fiber ply is arranged in the binder in a partially movable manner. As a result, a relative movement that ensures high vibration and noise damping is achieved within the main body and within the at least one fiber ply.

Claims

1-20. (canceled)

21. A grinding tool comprising a main body having a binder, at least one fiber ply embedded in the binder, and an abrasive layer, wherein the at least one fiber ply is arranged in the binder in a partially movable manner.

22. The grinding tool as claimed in claim 21, wherein each fiber ply comprises a plurality of yarns that are embedded in the binder in a partially movable manner relative to one another.

23. The grinding tool as claimed in claim 21, wherein the main body comprises a plurality of fiber plies that are embedded in the binder and are movable relative to one another in some region or regions.

24. The grinding tool as claimed in claim 21, wherein the main body comprises a plurality of fiber plies having a plurality of yarns, and the yarns are embedded in the binder in a partially movable manner relative to one another.

25. The grinding tool as claimed in claim 21, wherein the at least one fiber ply comprises at least one of at least one woven fabric and at least one non-crimp fabric.

26. The grinding tool as claimed in claim 21, wherein the main body comprises a number N of fiber plies, wherein: 1≤N≤12.

27. The grinding tool as claimed in claim 21, wherein, for a ratio M of a mass ins of the binder to a mass mF of the at least one fiber ply, the following applies: 1/25≤M≤1/2.

28. The grinding tool as claimed in claim 21, wherein the main body comprises damping particles.

29. The grinding tool as claimed in claim 21, wherein the binder is an organic adhesive.

30. The grinding tool as claimed in claim 21, wherein the main body is of curved design.

31. The grinding tool as claimed in claim 21, comprising a supporting layer, which is connected to the main body and on which the abrasive layer is arranged.

32. The grinding tool as claimed in claim 21, wherein the abrasive layer is shaped three-dimensionally.

33. A method for producing a grinding tool having the following steps: preparing at least one fiber ply and a binder, producing a main body by heating and then cooling the binder, wherein the at least one fiber ply is arranged in a partially movable manner in the binder after cooling, and forming an abrasive layer.

34. The method as claimed in claim 33, wherein a plurality of fiber plies are used to produce the main body.

35. The method as claimed in claim 33, wherein the heating of the binder takes place under pressure.

36. The method as claimed in claim 33, wherein preparation takes place in such a way that the at least one fiber ply is provided with the binder on one side.

37. The method as claimed in claim 33, wherein preparation takes place in such a way that the at least one fiber ply is provided with the binder in one of some region and regions on two sides.

38. The method as claimed in claim 33, wherein preparation takes place in such a way that a first fiber ply without binder is arranged adjacent to a second fiber ply provided with binder.

39. The method as claimed in claim 33, wherein preparation takes place in such a way that the at least one fiber ply is arranged adjacent to a layer of binder.

40. The method as claimed in claim 33, wherein a supporting layer is arranged on the main body.

41. The method as claimed in claim 33, wherein the formation of the abrasive layer is performed by electrostatic application of abrasive particles.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0034] FIG. 1 shows a sectional view of a grinding tool according to a first illustrative embodiment with a main body and an abrasive layer arranged thereon,

[0035] FIG. 2 shows an enlarged sectional view of the grinding tool in FIG. 1 to illustrate a structure of the main body with a binder and with fiber plies embedded in a partially movable manner in the binder,

[0036] FIG. 3 shows a schematic illustration of the production of the main body according to a first method,

[0037] FIG. 4 shows a schematic illustration of the production of the main body according to a second method,

[0038] FIG. 5 shows a schematic illustration of the production of the main body according to a third method,

[0039] FIG. 6 shows a schematic illustration of the production of the main body according to a fourth method,

[0040] FIG. 7 shows a schematic illustration of the electrostatic application of abrasive particles to the main body,

[0041] FIG. 8 shows a schematic sectional illustration of a grinding tool according to a second illustrative embodiment, and

[0042] FIG. 9 shows a schematic illustration of the production of the main body of the grinding tool in FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] A first illustrative embodiment of the invention is described below with reference to FIGS. 1 to 7. A handheld grinding machine (not illustrated specifically) is used in operation to drive a grinding tool 1 in rotation.

[0044] The grinding tool 1 is of disk-shaped design. The grinding tool 1 comprises a main body 2 and an abrasive layer 3 arranged thereon. In a clamping region 4, the main body 2 has a circular opening 5 to receive a drive shaft of the grinding machine. The opening 5 defines an axis of rotation 6 of the grinding tool 1. As an alternative to the opening 5, the grinding tool 1 can have a shaft.

[0045] The grinding tool 1 comprises a working region 7, which surrounds the clamping region 4 in a ring shape. In the working region 7, the abrasive layer 3 is arranged on the main body 2. The working region 7 is divided into an inner region 8 and an outer region 9. The inner region 8 is of annular design and surrounds the clamping region 4. In the inner region 8, the surface of the main body 2 on which the abrasive layer 3 is arranged is of substantially level design. The outer region 9 is of annular design and surrounds the inner region 8. In the outer region 9, the surface of the main body 2 on which the abrasive layer 3 is arranged is of substantially curved design. In the outer region 9, the main body 2 is curved relative to the axis of rotation 6 along a radial direction R and along a circumferential direction U. By virtue of the curvature of the main body 2, the abrasive layer 3 is formed in a correspondingly curved and three-dimensional way.

[0046] The main body 2 comprises a number N of fiber plies, wherein the following applies in general: 1≤N≤12, in particular 2≤N≤10, and in particular 4≤N≤8. The fiber plies are denoted individually by F.sub.i, where i denotes a running index for the individual fiber plies and depends on the number N. By way of example, the grinding tool 1 illustrated in FIG. 1 comprises four fiber plies, which are denoted individually by F.sub.1 to F.sub.4. The fiber plies F.sub.1 to F.sub.4 are illustrated only schematically in FIG. 1. The fiber plies F.sub.1 to F.sub.4 are designed as woven fabric and/or non-crimp fabric.

[0047] The main body 2 comprises a binder B, in which the fiber plies F.sub.1 to F.sub.4 are embedded in such a way that the fiber plies F.sub.1 to F.sub.4 are connected partially firmly to the binder B and are arranged in such a way as to be partially movable relative to the binder B and relative to one another. To achieve this, a mass m.sub.B of the binder B to a mass m.sub.F of the fiber plies F.sub.1 to F.sub.4 is relatively small. For a ratio M=m.sub.B/m.sub.F of the mass m.sub.B of the binder B to the mass mF of the fiber plies F.sub.1 to F.sub.4, the following applies: 1/25≤M≤1/2, in particular 1/20≤M≤1/3, in particular 1/15≤M≤1/4, and in particular 1/12≤M≤1/6. The binder B is an organic adhesive, in particular phenolic resin, epoxy resin and/or natural rubber.

[0048] FIG. 2 illustrates the partially movable arrangement of the fiber plies F.sub.1 to F.sub.4 in the binder B. The adjacent fiber plies F.sub.1 and F.sub.2 are illustrated by way of example in FIG. 2. The fiber plies F.sub.1 to F.sub.4 are designed as woven fabrics, for example, and each have a plurality of weft yarns S and warp yarns K extending transversely thereto. In FIG. 2, the weft yarns S.sub.1 and the warp yarns K.sub.1 of the first fiber ply F.sub.1 and the weft yarns S.sub.2 and the warp yarns K.sub.2 of the second fiber ply F.sub.2 are illustrated. Owing to the relatively small quantity of binder B, connection-free regions V, in which the fiber plies F.sub.1 to F.sub.4 are not connected by the binder B, are formed in the main body 2. In these connection-free regions V, the fiber plies F.sub.1 to F.sub.4 are movable in themselves and relative to the binder B. The fiber plies F.sub.1 to F.sub.4 embedded in the binder B are thus movable in themselves and/or relative to one another in some regions. In the connection-free regions V, the weft yarns S.sub.1, S.sub.2 and/or the warp yarns K.sub.1, K.sub.2 are movable relative to one another, for example. The connection-free regions V allow a relative movement of the fiber plies F.sub.1 to F.sub.4 in some regions within the main body 2.

[0049] The abrasive layer 3 comprises abrasive particles 10 with a geometrically determined shape, which are secured on the main body 2 by means of an adhesive agent 11. The adhesive agent 11 is a resin, in particular phenolic resin, for example. The abrasive particles 10 are arranged directionally relative to one another and relative to a surface of the main body 2. The abrasive particles 10 form an abrasive particle layer 12. A top binding 13 and a top layer 14 are arranged on the abrasive particle layer 12 in the usual way. The top binding 13 and/or the top layer 14 preferably have/has fillers with a grinding action.

[0050] By virtue of the fact that the fiber plies F.sub.1 to F.sub.4 allow a relative movement in themselves and/or relative to one another, forces which arise during grinding are absorbed by the main body 2, thereby ensuring high vibration and noise damping. The main body 2 nevertheless has sufficient stability and strength, and therefore the grinding tool 1 has a long life. The main body 2 can be produced easily and in any geometrical shape, and therefore the grinding tool 1 is flexible in application. The abrasive layer 3 is easy to apply to the main body 2 shaped in the desired manner, and therefore the abrasive layer 3 ensures high cutting performance of the grinding tool 1.

[0051] The production of the main body 2 is described below:

[0052] A first production method is illustrated in FIG. 3. In the first production method, the fiber plies F.sub.1 to F.sub.4 are prepared without binder. Layers of binder B are arranged between the fiber plies F.sub.1 to F.sub.4 that are arranged one above the other. The layers of binder B are designed as binder films. The fiber plies F.sub.1 to F.sub.4 and the layers of binder B arranged therebetween are then pressed against a main body form G under a pressure p and heated in such a way that the binder B becomes fluid. The binder B connects the fiber plies F.sub.1 to F.sub.4 in the manner described. The main body 2 is formed by cooling the binder B.

[0053] A second production method for the main body 2 is illustrated in FIG. 4. In the second production method, fiber plies F.sub.1 and F.sub.4 are prepared without binder B, and fiber plies F.sub.2 and F.sub.3 are prepared with binder B. Fiber plies F.sub.2 and F.sub.3 are each impregnated with the binder B on both sides. The fiber plies F.sub.1 to F.sub.4 are arranged one above the other and pressed against the main body form G under a pressure p and heated in such a way that the binder B becomes fluid. The binder B connects the fiber plies F.sub.1 to F.sub.4 in the manner described. The main body 2 is formed after the cooling of the binder B.

[0054] A third production method for the main body 2 is illustrated in FIG. 5. In the third production method, the fiber plies F.sub.1 to F.sub.4 are impregnated on one side with the binder B during preparation. The fiber plies F.sub.1 to F.sub.4 are arranged one above the other and pressed against the main body form G under a pressure p and heated in such a way that the binder B becomes fluid. The binder B connects the fiber plies F.sub.1 to F.sub.4 in the manner described. The main body 2 is formed after cooling 4.

[0055] A fourth production method for the main body 2 is illustrated in FIG. 6. In this production method, the prepared fiber plies F.sub.1 to F.sub.4 are each provided in some region or regions with the binder B on two sides. The fiber plies F.sub.1 to F.sub.4 are impregnated with the binder B in some region or regions. The fiber plies F.sub.1 to F.sub.4 are arranged one above the other, pressed against the main body form G under a pressure p and heated in such a way that the binder B becomes fluid. The binder B connects the fiber plies F.sub.1 to F.sub.4 in the manner described. After cooling, the connected fiber plies F.sub.1 to F.sub.4 form the main body 2.

[0056] The production method and the fiber plies F.sub.1 to F.sub.4 prepared can be combined with one another in a desired manner.

[0057] The formation of the abrasive layer 3 on the main body 2 and the production of the grinding tool 1 are described below:

[0058] By means of an application device 15, the abrasive particles 10 are applied electrostatically to the main body 2. The application device 15 comprises a handling device 16 for handling and positioning the main body 2, a first electrode 17 and an associated second electrode 18 for generating an electrostatic field E, and a metering device 19 for feeding the abrasive particles 10 to a conveyor 20.

[0059] The conveyor 20 comprises an endless conveyor belt 21, which is tensioned by means of two deflection pulleys 22, 23. Deflection pulley 22 is driven in rotation by means of an electric drive motor 24. A part of the conveyor belt 21 arranged above the deflection pulleys 22, 23 in relation to the force of gravity F.sub.G forms a conveying region 25, which extends in a horizontal x direction and a horizontal y direction.

[0060] The metering device 19 is arranged ahead of the electrodes 17, 18 in a conveying direction 26. The first electrode 17 is of plate-shaped design and is arranged below the upper part of the conveyor belt 21 and below the conveying region 25 in the direction of the force of gravity F.sub.G. In contrast, the second electrode 18 is arranged above the conveyor belt 21 and the conveying region 25 in relation to the force of gravity F.sub.G. The second electrode 18 is thus spaced apart from the first electrode 17 in a vertical z direction, with the result that the conveying region 25 extends between the electrodes 17, 18. The second electrode 18 is secured on the handling device 16. The x, y and z directions form a Cartesian coordinate system.

[0061] The second electrode 18 is shaped to match the main body 2. The main body 2 is held by means of the handling device 16 in such a way that the second electrode 18 rests substantially over the full area against a rear side of the main body 2. The handling device 16 holds the main body 2 mechanically and/or pneumatically, for example. An electric voltage U.sub.E, which is generated and can be set by means of a voltage source 27, is applied between the first electrode 17 and the second electrode 18.

[0062] The adhesive agent 11 is first of all applied on a surface facing away from the second electrode 18, with the result that the adhesive agent 11 arranged on the main body 2 forms a three-dimensionally shaped adhesion surface. The adhesive agent 11 is applied manually, for example, or by means of the handling device 16. The surface of the main body 2 is dipped into the adhesive agent 11 by means of the handling device 16, for example.

[0063] The main body 2 is then positioned above the first electrode 17 in the z direction by means of the handling device 16, with the result that the adhesion surface is arranged partially in the electrostatic field E between the electrodes 17, 18. The field lines emanate vertically from the surface of the first electrode 17 and enter the surface of the second electrode 18 vertically, with the result that the field lines run substantially vertically through the adhesion surface.

[0064] By means of the conveying device 20, the abrasive particles 10 for the formation of the three-dimensionally shaped abrasive particle layer 12 are transported into the electrostatic field E. For this purpose, the metering device 19 supplies the abrasive particles 10. The abrasive particles 10 are fed to the conveyor belt 21 and distributed thereon in a metered manner by means of the metering device 19. By means of the electric drive motor 24, the conveyor belt 21 with the abrasive particles 10 arranged thereon is moved in the conveying direction 26, thus ensuring that the abrasive particles 10 are brought into the electrostatic field E. The speed of transfer in the conveying direction 26 can be set by means of the electric drive motor 24.

[0065] By means of the electrostatic field E, the abrasive particles 10 are moved to the adhesive agent 11 and the adhesion surface counter to the force of gravity F.sub.G, and are aligned along the field lines. When the abrasive particles 10 touch the adhesion surface, they remain stuck there. By means of the adhering abrasive particles 10, the abrasive particle layer 12 is formed on the main body 2. In order to apply the abrasive particles 10 uniformly and homogeneously, the main body 2 is rotated about a central longitudinal axis 28 by means of the handling device 16.

[0066] After the abrasive particle layer 12 has been fully applied to the main body 2, the main body 2 with the adhesive agent 11 and the abrasive particle layer 12 forms a semifinished product. The semifinished product is released by the handling device 16 and arranged in a heating device, where the adhesive agent 11 is cured. The top binding 13 and the top layer 14 are then applied to the abrasive particle layer 12 in the usual way. In respect of further details and features of the grinding tool 1 and of the electrostatic application of the abrasive particles 10, attention is drawn explicitly to WO 2018/149 483 A1, the contents of which are incorporated by reference at this point.

[0067] A second illustrative embodiment of the invention is described below with reference to FIGS. 8 and 9. In contrast to the previous illustrative embodiment, the main body 2 comprises damping particles D. The damping particles D are natural rubber particles and/or foam particles, for example. The damping particles D are incorporated into the main body 2 during the production of the latter. The damping particles D form additional connection-free regions V and themselves have noise- and vibration-damping properties.

[0068] The grinding tool 2 furthermore comprises a supporting layer 29, which is connected to the main body 2 and provides a surface for the arrangement of the abrasive layer 2. The supporting layer 29 is composed of a metallic material. The supporting layer 29 is connected monolithically to the main body 2. For this purpose, the supporting layer 29 is produced together with the main body 2. This is illustrated in FIG. 9. The supporting layer 29 is covered electrostatically with abrasive particles 10 in the manner described before and/or after being connected to the main body 2. In respect of further aspects of the construction, production and operation of the grinding tool 1, attention is drawn to the previous illustrative embodiment.

[0069] In general, the following applies:

[0070] The grinding tool 1 according to the invention does not have continuous or full-area bonding with the binder within the main body 2, and therefore there are connection-free free spaces or regions within the main body 2, e.g. air inclusions. The main body 2 has a quantity of binder B such that, on the one hand, a relative movement is made possible within the main body 2 but, on the other hand, the main body 2 is sufficiently firm and does not delaminate during grinding. This is achieved by means of insular or fine wetting of the fiber plies F.sub.i. The free relative movement within the fiber plies F.sub.i or the respective fiber ply F.sub.i allows high vibration and noise damping. By virtue of the fiber plies F.sub.i connected to one another by means of the binder B and by virtue of the possible relative movement within the respective fiber ply F.sub.i, a construction of the main body 2 such that there are alternating hard and soft layers is achieved. An additional rubber ply is not required to achieve high vibration and noise damping. The fiber plies F.sub.i moving one inside the other make possible the high vibration and noise damping but ensure that there is no wrinkling. The main body 2 can be produced with any desired three-dimensional shape, in particular by draping the fiber plies F.sub.i and connecting the fiber plies F.sub.i by means of the binder B.

[0071] The respective fiber ply F.sub.i has a connection on both sides to the binder B, thus ensuring that there is no delamination of the fiber plies F.sub.i. The binder B connects the individual fiber plies F.sub.i, which remain inherently flexible. The binder B is an elastomer, for example, thereby assisting the vibration and noise damping of the main body 2. The at least one fiber ply F.sub.i is padded, for example. The at least one fiber ply F.sub.i is coated, laminated, sheathed or silanized with the binder B, for example. The respective fiber ply F.sub.i is designed as a woven fabric or non-crimp fabric. The fiber plies F.sub.i within the main body 2 are designed as woven fabrics and/or non-crimp fabrics. The woven fabric has a twill weave, for example. A twill weave ensures movement or mobility within the woven fabric and simplicity of draping. The fiber plies F.sub.i are arranged as inner fiber plies and/or outer fiber plies in the main body 2. The abrasive layer 3 can comprise an abrasive particle layer 12 or an abrasive fleece. The abrasive particle 10 is a coated ceramic particle, for example. The supporting layer 29 serves as an intermediate layer between the main body 2 and the abrasive layer 3. The supporting layer 29 can be designed as paper, film and/or woven fabric. The supporting layer 29 is composed of a metallic material, for example. Abrasive particle 10 is preferably applied directly to the main body 2 or the supporting layer 29.