Grinding disc and use of such a grinding disc

Abstract

A grinding disc comprises a grinding layer formed of grinding grains bound by means of a binding agent. Reinforcing fabrics are embedded in the grinding layer on the outer sides of the grinding layer. At least one additional fabric is arranged on at least one of the reinforcing fabrics and has a respective diameter which is smaller than the diameter of the rein-forcing fabrics. The at least one additional fabric stiffens the grinding disc in a region around a central opening and improves the properties of the grinding disc during rough machining and/or cutting off.

Claims

1. A grinding disc comprising: a grinding layer, having a grinding layer diameter, the grinding layer comprising grinding grains bound by a binding agent, and forming a first outer side and a second outer side of the grinding disc, a first reinforcing fabric, which is embedded inside the first outer side of the grinding layer such that the first outer side comprises a first surface of the grinding disc, and which has a first fabric diameter, wherein the first fabric diameter is larger than or equal to 80% of the grinding layer diameter, a second reinforcing fabric, which is embedded inside the second outer side of the grinding layer such that the second outer side comprises a second surface of the grinding disc, and which has a second fabric diameter, wherein the second fabric diameter is larger than or equal to 80% of the grinding layer diameter, wherein at least one fabric is arranged on at least one of the first reinforcing fabric or the second reinforcing fabric, wherein the at least one fabric is embedded in the grinding layer between the first outer side and the second outer side, wherein the at least one fabric has a respective fabric diameter, wherein the at least one fabric diameter is smaller than the first fabric diameter, and the at least one fabric diameter is smaller than the second fabric diameter, wherein the at least one fabric has a respective value Ri, wherein the respective value Ri is larger than or equal to 0.2 and the respective value Ri is less than or equal to 1.2, wherein the following applies to Ri:
R.sub.i=R.sub.xi+R.sub.yi,
with
R.sub.xi=b.sub.xi.Math.n.sub.xi/l.sub.xi,
R.sub.yi=b.sub.yi.Math.n.sub.yi/l.sub.yi, wherein b.sub.xi, b.sub.yi is a thread width or a web width of threads in a x-direction and a y-direction, respectively, n.sub.xi, n.sub.yi is a number of threads or a number of webs in the x-direction and the y-direction, respectively, and l.sub.xi, l.sub.yi is a length in the x-direction and the y-direction.

2. The grinding disc according to claim 1, wherein no internal reinforcing fabric is arranged in the grinding layer between the first reinforcing fabric and the second reinforcing fabric.

3. The grinding disc according to claim 1, wherein the at least one fabric is arranged relative to the at least one of the first or second reinforcing fabrics on a side facing away from the grinding layer.

4. The grinding disc according to claim 1, wherein the at least one fabric is arranged on the first reinforcing fabric and at least one fabric is arranged on the second reinforcing fabric.

5. The grinding disc according to claim 1, wherein the at least one fabric comprises a plurality of fabrics arranged on at least one of the first or second reinforcing fabrics.

6. The grinding disc according to claim 1, wherein the at least one fabric diameter is larger than or equal to 25% of the grinding layer diameter, and the at least one fabric diameter is less than or equal to 75% of the grinding layer diameter.

7. The grinding disc according to claim 1, wherein the at least one fabric is arranged in a clamping region and in an inner working region, which is usable for rough machining, and wherein the at least one fabric is arranged outside an outer working region, which is usable for cutting.

8. The grinding disc according to claim 7, wherein the at least one fabric delimits a reinforced region of the grinding disc from an unreinforced region of the grinding disc, wherein the at least one fabric is arranged in the reinforced region, wherein the clamping region and the inner working region form the reinforced region, and wherein the outer working region forms the unreinforced region.

9. The grinding disc according to claim 1, wherein the at least one fabric delimits a reinforced region of the grinding disc with a first thickness and an unreinforced region of the grinding disc with a second thickness, wherein a ratio between the first thickness and the second thickness is between 0.95 and 1.05.

10. The grinding disc according to claim 1, having a grinding disc thickness, wherein the grinding disc thickness is larger than or equal to 2 mm and less than or equal to 7 mm.

11. The grinding disc according to claim 1, having a grinding disc thickness, wherein the grinding disc thickness is larger than or equal to 0.8 mm and less than or equal to 4 mm.

12. The grinding disc according to claim 1, wherein the at least one fabric arranged on the at least one of the first or second reinforcing fabrics has, in total, a respective weight per unit area, wherein the respective weight per unit area is larger than or equal to 50 g/m.sup.2, and the respective weight per unit is less than or equal to 500 g/m.sup.2.

13. The grinding disc according to claim 1, wherein the at least one fabric has a respective thread width, wherein the respective thread width is larger than or equal to 0.1 mm and the respective thread width is less than or equal to 1.8 mm.

14. The grinding disc according to claim 1, comprising a clamping ring for clamping the grinding disc on a grinding machine.

15. A method of at least one of rough machining and cutting off, the method comprising using the grinding disc according to claim 1, wherein a cutting speed is at least 80 m/s.

16. The grinding disc according to claim 1, wherein the at least one fabric is arranged on the first reinforcing fabric and at least one fabric is arranged on the second reinforcing fabric, and wherein the at least one fabric delimits a reinforced region of the grinding disc with a first thickness and an unreinforced region of the grinding disc with a second thickness, wherein a ratio between the first thickness and the second thickness is between 0.95 and 1.05.

17. A grinding disc comprising: a grinding layer, having a grinding layer diameter, the grinding layer comprising grinding grains bound by a binding agent, and forming a first outer side and a second outer side of the grinding disc, a first reinforcing fabric embedded inside in the grinding layer on the first outer side of the grinding layer such that the first outer side comprises a first surface of the grinding disc, the first reinforcing fabric having a first fabric diameter, wherein the first fabric diameter is larger than or equal to 80% of the grinding layer diameter, a second reinforcing fabric embedded inside in the grinding layer on the second outer side of the grinding layer such that the second outer side comprises a second surface of the grinding disc, the second reinforcing fabric having a second fabric diameter, wherein the second fabric diameter is larger than or equal to 80% of the grinding layer diameter, wherein at least one fabric is arranged on at least one of the first reinforcing fabric or the second reinforcing fabric, wherein the at least one fabric is embedded in the grinding layer between the first outer side and the second outer side of the grinding layer, wherein the at least one fabric has a respective fabric diameter, wherein the at least one fabric diameter is smaller than the first fabric diameter, and the at least one fabric diameter is smaller than the second fabric diameter, wherein the at least one fabric is arranged in a clamping region and in an inner working region of the grinding disc, wherein the inner working region is usable for rough grinding, wherein the at least one fabric is not arranged in an outer working region of the grinding disc, and wherein the outer working region is usable for cutting.

18. The grinding disc according to claim 17, wherein the grinding disc forms the clamping region and a working region surrounding the clamping region, wherein the working region is divided in a radial direction to an axis of rotation into the inner working region and the outer working region surrounding the inner working region.

19. The grinding disc according to claim 17, wherein the at least one fabric diameter is larger than or equal to 35% of the grinding layer diameter, and the at least one fabric diameter is less than or equal to 70% of the grinding layer diameter.

20. The grinding disc according to claim 17, wherein the at least one fabric is arranged on the first reinforcing fabric and at least one fabric is arranged on the second reinforcing fabric.

21. The grinding disc according to claim 17, wherein the at least one fabric delimits a reinforced region of the grinding disc with a first thickness and an unreinforced region of the grinding disc with a second thickness, wherein a ratio between the first thickness and the second thickness is between 0.95 and 1.05.

22. The grinding disc according to claim 17, wherein the at least one fabric is arranged on the first reinforcing fabric and at least one fabric is arranged on the second reinforcing fabric, and wherein the at least one fabric delimits a reinforced region of the grinding disc with a first thickness and an unreinforced region of the grinding disc with a second thickness, wherein a ratio between the first thickness and the second thickness is between 0.95 and 1.05.

23. The grinding disc according to claim 17, wherein the at least one fabric delimits a reinforced region of the grinding disc from an unreinforced region of the grinding disc, wherein the at least one fabric is arranged in the reinforced region, wherein the clamping region and the inner working region form the reinforced region, and wherein the outer working region forms the unreinforced region.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a sectional view of a grinding disc according to the invention with reinforcing fabrics and additional fabrics,

(2) FIG. 2 shows an exploded view of the grinding disc in FIG. 1,

(3) FIG. 3 shows an enlarged top view of an additional fabric, and

(4) FIG. 4 shows an enlarged view of a portion IV of the grinding disc in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(5) The grinding disc 1 shown in FIG. 1 is for the use on a hand-held angle grinder. The grinding disc 1 comprises a grinding layer 2, which is formed of grinding grains 4 bonded by means of a binding agent 3. The binding agent 3, for example, is a phenolic resin. The grinding layer 2 has a grinding layer diameter D.sub.S which corresponds to a nominal diameter of the grinding disc 1.

(6) A first reinforcing fabric 6 is embedded in the grinding layer 2 on a first outer side 5. Correspondingly, a second reinforcing fabric 8 is embedded in the grinding layer 2 on a second outer side 7. The first reinforcing fabric 6 has a first fabric diameter D.sub.A1, which corresponds to the grinding layer diameter D.sub.S. Correspondingly, the second reinforcing fabric 8 has a second fabric diameter D.sub.A2, which corresponds to the grinding layer diameter D.sub.S.

(7) The reinforcing fabrics 6, 8 are construed as glass fiber fabrics, for example.

(8) The grinding disc 1 comprises additional fabrics W.sub.1, W.sub.2, W.sub.3 and W.sub.4. The fabrics W.sub.1 and W.sub.2 are arranged on a side of the first reinforcing fabric 6 facing away from the grinding layer 2 and are embedded in the grinding layer 2, whereas the fabrics W.sub.3 and W.sub.4 are arranged on a side of the second reinforcing fabric 8 facing away from the grinding layer 2 and are embedded in the grinding layer 2.

(9) FIG. 4 shows an enlarged view of the portion IV of FIG. 1. This view shows that a first reinforcing fabric 6 is embedded inside the first outer side of the grinding layer such that the first outer side comprises a first surface of the grinding disc, a second reinforcing fabric 8 is embedded inside the second outer side of the grinding layer such that the second outer side comprises a second surface of the grinding disc, and at least one fabric (of fabrics W.sub.1, W.sub.2, W.sub.3 and W.sub.4) is embedded in the grinding layer between the first outer side and the second outer side.

(10) The grinding disc 1 comprises a central opening 9 for attachment to an angle grinding machine. The central opening 9 defines an axis of rotation M of the grinding disc 1. For clamping to an angle grinding machine, the grinding disc 1 has a clamping ring 10 which is arranged in the central opening 9. The clamping ring 10, for example, is construed as a steel ring. The clamping ring 10 abuts the fabric W.sub.1 on the first outer side 5 and is connected to the grinding layer 2.

(11) The grinding disc 1 is circular in shape. The reinforcing fabrics 6, 8 and/or the fabrics W.sub.1 to W.sub.4 are arranged concentrically to the axis of rotation M. The reinforcing fabrics 6, 8 and/or the fabrics W.sub.1 to W.sub.4 are annular.

(12) The fabrics W.sub.1 to W.sub.4 have a respective diameter D.sub.1 to D.sub.4. The fabrics are generally designated W.sub.i and the corresponding diameter D.sub.i with i=1, 2, 3, 4. The index i specifies the respective fabric W.sub.i. The following applies to the respective diameter D.sub.i:D.sub.i<D.sub.A1 and D.sub.i<D.sub.A2. In particular, the following applies to the respective diameter D.sub.i: 0.25.Math.D.sub.SD.sub.i0.75.Math.D.sub.S, in particular 0.3.Math.D.sub.SD.sub.i0.7.Math.D.sub.S, and in particular 0.35.Math.D.sub.SD.sub.i0.65.Math.D.sub.S. Preferably, D.sub.1=D.sub.2=D.sub.3=D.sub.4.

(13) The grinding layer 2 is free of further reinforcing fabrics between the reinforcing fabrics 6, 8, so that the grinding layer 2 is in particular free of a reinforcing fabric arranged centrally in the grinding layer 2. Preferably, the grinding layer 2 is also free of further additional fabrics between the reinforcing fabrics 6, 8.

(14) The grinding disc 1 forms a clamping region 11 in the radial direction to the axis of rotation M and a working region 12 surrounding the clamping region 11. The working region 12 is divided in the radial direction to the axis of rotation M into an inner working region 13 and an outer working region 14 surrounding it. The working region 12, i.e. the inner working region 13 and the outer working region 14, are annular. The inner working region 13 extends in the radial direction as far as the fabrics W.sub.1 to W.sub.4 extend. The clamping region 11 and the inner working region 13 thus form a reinforced region 15 in which the fabrics W.sub.1 to W.sub.4 are arranged. The outer working region 14, on the other hand, forms an unreinforced region 16 which is free of additional fabrics W.sub.1 to W.sub.4. The outer working region 14 is preferably used for cutting off a workpiece, whereas the inner working region 13 and the outer working region 14 are used for rough machining a workpiece.

(15) The reinforced region 15 has a thickness d.sub.1, whereas the unreinforced region 16 has a thickness d.sub.2. The grinding disc 1 has a substantially constant thickness in the radial direction to the axis of rotation M, wherein: 0.95d.sub.1/d.sub.21.05, in particular 0.99d.sub.1/d.sub.21.01, and in particular 0.995d.sub.1/d.sub.21.005. A thickness d of the grinding disc 1 results from the maximum of the thicknesses d.sub.1 and d.sub.2. Preferably, the following applies: d=d.sub.1=d.sub.2.

(16) In a preferred use of the grinding disc 1 for rough machining a workpiece, the following preferably applies to the thickness d: 2 mmd7 mm, in particular 3 mmd6 mm, and in particular 4 mmd5 mm. In a preferred use of the grinding disc 1 for cutting off a workpiece, the following preferably applies for the thickness d: 0.8 mmd4 mm, in particular 1.2 mmd3.2 mm, and in particular 1.6 mmd2.5 mm.

(17) FIG. 3 illustrates in general the structure of a fabric W.sub.i. The fabric W.sub.i has a plurality of weft threads 17 running in a y-direction and a plurality of warp threads 18 running transversely thereto in an x-direction. The respective fabric W.sub.i is construed as a glass fibre fabric, for example.

(18) The weft threads 17 have a thread width b.sub.xi, whereas the warp threads 18 have a thread width b.sub.yi. The thread width b.sub.xi or b.sub.yi is also referred to as the web width. For the thread width b.sub.xi, the following preferably applies: 0.1 mmb.sub.xi1.8 mm, in particular 0.3 mmb.sub.xi1.5 mm, and in particular 1 mmb.sub.xi1.2 mm. For the thread width b.sub.yi, the following preferably applies: 0.1 mmb.sub.yi1.8 mm, in particular 0.3 mmb.sub.yi1.5 mm, and in particular 1 mmb.sub.yi1.2 mm. The thread widths b.sub.xi and b.sub.xi are generally referred to as thread width b.sub.i. The thread widths b.sub.xi and b.sub.yi of the respective fabric W; may be the same and/or different. Furthermore, the thread widths b.sub.xi and b.sub.yi of the fabrics W.sub.i can be the same among each other and/or be different from each other.

(19) The respective fabric W has a value R.sub.i which characterizes the openness of the fabric W.sub.i. The following applies to the respective value R.sub.i:
R.sub.i=R.sub.xi+R.sub.yi(1)
with
R.sub.xi=b.sub.xi.Math.n.sub.xi/l.sub.xi(2)
and
R.sub.yi=b.sub.yi.Math.n.sub.yi/l.sub.yi(3)

(20) In equations (2) and (3): b.sub.xi denotes the thread width of the weft threads 17, n.sub.xi/l.sub.xi denotes the number of weft threads 17 in relation to a length l.sub.xi in the x-direction, b.sub.yi denotes the thread width of the warp threads 18, n.sub.yi/l.sub.yi denotes a number of warp threads 18 in relation to a length l.sub.yi in the y-direction.

(21) The values R.sub.xi and R.sub.yi of the respective fabric W.sub.i can be the same or different. The values R.sub.xi and R.sub.yi of the fabrics W.sub.i can be the same among each other and/or different. The values R.sub.i of the fabrics W.sub.i can be the same and/or different. The following preferably applies to the values R.sub.i: 0.2R.sub.i1.2, in particular 0.3R.sub.i1.

(22) The fabrics W.sub.1 and W.sub.2 are associated to the first reinforcing fabric 6 and have a total first weight per unit area G.sub.1. Correspondingly, the fabrics W.sub.3 and W.sub.4 are associated to the second reinforcing fabric 8 and have a total second weight per unit area G.sub.2. The respective weight per unit area is generally denoted by G.sub.j, wherein the index j denotes the respective reinforcing fabric 6, 8 or the respective outer side of the grinding layer 2 to which the fabrics W.sub.1, W.sub.2 or W.sub.3, W.sub.4 are associated. For the index j, the following applies: j=1, 2. For the respective summed weight per unit area G.sub.j, the following applies preferably: 50 g/m.sup.2G.sub.j500 g/m.sup.2, in particular 75 g/m.sup.2G.sub.j450 g/m.sup.2, and in particular 100 g/m.sup.2G.sub.j400 g/m.sup.2. The weights per unit area G.sub.j may be the same and/or different. The weights per unit area of the individual fabrics W.sub.i may be the same and/or different.

(23) The mode of operation and the use of the grinding disc 1 are as follows:

(24) The additional fabrics W.sub.1 to W.sub.4 reinforce and stiffen the grinding disc 1 so that the grinding disc 1 can be operated at a comparatively higher rotational speed and a higher cutting speed v during rough machining and/or cutting off. The cutting speed v is at least 80 m/s, in particular at least 90 m/s, and in particular at least 100 m/s at the outer circumference of the grinding disc 1 or at the grinding layer diameter D.sub.S. This increases the grinding performance and/or cutting-off performance.

(25) When the grinding disc 1 is designed as a cut-off grinding disc, the additional fabrics W.sub.1 to W.sub.4 prevent vibration or fluttering at high rotational speeds or high cutting speeds v. When the grinding disc 1 is designed as a cut-off grinding disc, in particular it also allows for a curved cut, as the reinforcing fabric 6 is protected by the fabrics W.sub.1 and W.sub.2 when it is bent on fastening means of an angle grinding machine.

(26) When the grinding disc 1 is designed as a rough grinding disc, the additional fabrics W.sub.1 to W.sub.4 enable the number of additional reinforcing fabrics within the grinding layer 2 to be reduced between the reinforcing fabrics 6, 8. This increases the grinding performance with comparable stability and stiffness, as additional reinforcing fabrics in the working region 12 have an adverse effect on the grinding properties or grinding performance. Furthermore, it is possible to make the rough grinding disc comparatively thin so that it can also be used for cutting off. For example, the outer working region 14 can be used for cutting off, whereas the inner working region 13 and additionally the outer working region 14 can be used for rough machining.

(27) In general:

(28) The preferred structure of the grinding disc 1 is label/Nfabric W.sub.i/reinforcing fabric 6/grinding layer 2/reinforcing fabric 8/Nfabric W.sub.i/label/clamping ring 10. The grinding disc 1 can be configured in a cranked manner in the clamping region 11. The additional fabrics W.sub.i may be finer-meshed and/or coarser-meshed and/or of the same mesh size as the first reinforcing fabric 6 and/or the second reinforcing fabric 8.