SUPPORTING BODY FOR A GRINDING TOOL AND METHOD OF PRODUCING A SUPPORTING BODY

Abstract

A supporting body for a grinding tool, the supporting body including an abrasive pad having a preferably circumferential supporting surface for an abrasive material, particularly a superabrasive material. The supporting body consisting substantially of a composite material which is free of abrasive material and consists of a plurality of layers of a natural fiber material which are arranged one atop the other and are connected to each other by plastic, preferably phenolic resin. The natural fiber material preferably is a cotton fabric or paper, and the supporting body includes a first, preferably cylindrical or hollow cylindrical body and at least one additional, preferably cylindrical or hollow cylindrical body, in which the bodies are connected, preferably adhesively bonded, to each other.

Claims

1. A support body for a grinding tool which includes a preferably circumferential support surface for an abrasive layer having abrasive means, in particular superabrasive means, wherein the support body substantially comprises an abrasive means-free composite material comprising a plurality of mutually superposed layers of a natural fibre material which are connected together by plastic, preferably phenolic resin, preferably wherein the natural fibre material is a cotton fabric or paper, wherein the support body has a first, preferably cylindrical or hollow-cylindrical body and at least one further, preferably cylindrical or hollow-cylindrical body, wherein the bodies are connected together, preferably adhesively bonded.

2. The support body according to claim 1, wherein the composite material is of a density of 1.0 to 2.0 g/cm.sup.3, preferably 1.4 g/cm.sup.3 and/or has a water absorption of 1.5 to 7.5%, preferably 2.4% or 5.2%.

3. The support body according to claim 1, wherein the composite material has a length extension coefficient of 20 to 4010.sup.6 K.sup.1, preferably 3010.sup.6 K.sup.1 and/or thermal conductivity of 0.1 to 0.3 W/mK, preferably 0.2 W/mK.

4. The support body according to claim 1, wherein the composite material has a compressive strength at 23 C. of 200 to 400 N/mm.sup.2, preferably 300 N/mm.sup.2 or 320 N/mm.sup.2 and/or a flexural strength at 23 C. of 50 to 150 N/mm.sup.2, preferably 100 N/mm.sup.2 or 135 N/mm.sup.2 and/or a modulus of elasticity of 6000 to 8000 N/mm.sup.2, preferably 7000 N/mm.sup.2 and/or a tensile strength of 50 to 150 N/mm.sup.2, preferably 80 N/mm.sup.2 or 120 N/mm.sup.2 and/or a splitting force of 1500 to 3500 N, preferably 1900 N or 3000 N.

5. The support body according to claim 1, wherein the support body has at least one side surface which is separate from the support surface for the abrasive layer and at which a layer of the natural fibre material is arranged flat.

6. The support body according to claim 1, wherein the support body has a central coupling region, preferably with a central bore, for connection to a rotary drive for rotating the support body or a grinding tool formed therewith about an axis of rotation extending through the coupling region and/or the support body is of a substantially rotationally symmetrical configuration.

7. The support body according to claim 1, wherein the first and the at least one further body are cylindrical or hollow-cylindrical bodies which are connected together at side surfaces, preferably wherein axes of symmetry of the bodies are substantially congruent.

8. The support body according to claim 1, wherein the support body has an adaptor for connecting the support body or a grinding tool formed therewith to a rotary drive connected, preferably glued to at least one of the bodies, preferably wherein the adaptor substantially comprises a metal and/or is of a substantially hollow-cylindrical configuration.

9. The support body according to claim 8, wherein the support body has a central bore and the adaptor is at least region-wise arranged in the central bore, preferably wherein the adaptor extends only over a part of the length of the central bore, particularly preferably wherein the central bore has a funnel-shaped insertion opening.

10. A grinding tool having the support body according to claim 1 and an abrasive layer which has abrasive means, in particular superabrasive means, and which is arranged on the preferably circumferential support surface of the support body, preferably wherein the abrasive layer is formed from a continuous abrasive ring or individual abrasive segments.

11. A method of producing a support body for a grinding tool, wherein the support body includes a preferably circumferential support surface for an abrasive layer having abrasive means, in particular superabrasive means, and substantially comprises an abrasive means-free composite material comprising a plurality of mutually superposed layers of a natural fibre material, which are connected together by plastic, preferably phenolic resin, wherein the natural fibre material is a cotton fabric or paper, wherein the abrasive means-free composite material is provided in the form of a plate in a first method step and in a second method step a preferably cylindrical or hollow-cylindrical body is cut out of the plate with predetermined dimensions preferably by water jet cutting or by means of a band saw.

12. The method according to claim 11, wherein, in the course of the second method step, at least one further, preferably cylindrical or hollow-cylindrical body is cut out of the plate with predetermined dimensions and connected to the first body, preferably by adhesive.

13. The method according to claim 12, wherein the first and the at least one further body is cylindrical or hollow-cylindrical bodies, the bodies being connected together at side surfaces, preferably wherein axes of symmetry of the bodies are brought substantially into congruent relationship.

14. The method according to claim 11, wherein in a third method step the body or bodies is or are re-worked, preferably by cutting machining and/or balancing and/or by fitting a central bore.

15. The method according to claim 11, wherein at least one of the bodies in a further method step which follows the second method step or the third method step is connected to an adaptor for connecting the support body or a grinding tool formed therewith to a rotary drive, preferably by adhesive, preferably wherein the adaptor substantially comprises a metal and/or is of a substantially hollow-cylindrical configuration.

16. A method of producing a grinding tool having a support body which includes a preferably circumferential support surface for an abrasive layer having abrasive means, in particular superabrasive means, and substantially comprises an abrasive means-free composite material comprising a plurality of mutually superposed layers of a natural fibre material, which are connected together by plastic, preferably phenolic resin, preferably wherein the natural fibre material is a cotton fabric or paper, and an abrasive layer which has abrasive means, in particular superabrasive means and which is arranged on the preferably circumferential support surface of the support body, preferably wherein the abrasive layer is formed from a continuous abrasive ring or individual abrasive segments, wherein firstly a support body produced by the method according to claim 11 is provided and then an abrasive layer having abrasive means, preferably superabrasive means, is arranged on a preferably circumferential support surface of the support body, preferably by pressing thereon and/or adhesive bonding, preferably wherein the abrasive layer is formed from a continuous abrasive ring or individual abrasive segments.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Further details and advantages of the invention will be described more fully hereinafter by means of the specific description with reference to the drawings in which:

[0039] FIG. 1a is a diagrammatic side view of a support body,

[0040] FIG. 1b is a diagrammatic cross-sectional view along section plane 24 of the support body of FIG. 1a,

[0041] FIG. 2 is a diagrammatic side view of a grinding tool according to a first preferred embodiment,

[0042] FIG. 3a is a photograph of a grinding tool according to a second preferred embodiment as a side view,

[0043] FIG. 3b is a microscope image of a cross-sectional surface of the composite material used in the grinding tool according to the second preferred embodiment,

[0044] FIGS. 4a and 4b show microscope images of a further composite material which is preferably used of a side surface (FIG. 4a) and a cross-sectional surface,

[0045] FIG. 5 shows a diagrammatic view by means of a flow chart of a method of producing a support body and a cutting tool, and

[0046] FIGS. 6a and 6b show a further grinding tool as a diagrammatic perspective view (FIG. 6a) and a diagrammatic cross-sectional view (FIG. 6b).

DETAILED DESCRIPTION OF THE INVENTION

[0047] FIGS. 1a and 1b show a support body 1 for a grinding tool 2 (see also FIG. 2) which is substantially rotationally symmetrical and includes a circumferential support surface 3 for an abrasive layer 5 having abrasive means 4, in particular superabrasive means.

[0048] The support body 1 substantially comprises an abrasive means-free composite material 6 comprising a plurality of mutually superposed layers 7 of a natural fibre material connected together by plastic 8. That is diagrammatically indicated in the view on an enlarged scale of the portion in FIG. 1b. The plastic 8 can be a hardened synthetic resin, preferably phenolic resin.

[0049] Directly adjacent layers 7 can be at a very small spacing relative to each other and even at least region-wise touch. The layers 7 are oriented substantially parallel to side surfaces.

[0050] Two embodiments have proven to be particularly advantageous in relation to the composite material 6.

[0051] In the first embodiment the natural fibre material is a cotton fabric. In that case the composite material 6 is of a density of 1.4 g/cm.sup.3 and has water absorption of 2.4%. In addition the composite material 6 has a length extension coefficient of 3010.sup.6 K.sup.1 and a thermal conductivity of 0.2 W/mK. And finally the composite material 6 has a compressive strength at 23 C. of 320 N/mm.sup.2, a flexural strength at 23 of 100 N/mm.sup.2, a modulus of elasticity of 7000 N/mm.sup.2, a tensile strength of 80 N/mm.sup.2 and a splitting force of 3000 N.

[0052] In the second embodiment the natural fibre material is paper. In that case the composite material 6 is of a density of 1.4 g/cm.sup.3 and has water absorption of 5.2%. In addition the composite material 6 has a length extension coefficient of 3010.sup.6 K.sup.1 and a thermal conductivity of 0.2 W/mK. And finally the composite material 6 has a compressive strength at 23 C. of 300 N/mm.sup.2, a flexural strength at 23 of 135 N/mm.sup.2, a modulus of elasticity of 7000 N/mm.sup.2, a tensile strength of 120 N/mm.sup.2 and a splitting force of 1900 N.

[0053] The support body 1 has two oppositely disposed side surfaces 9 which are separate from the support surface 3 for the abrasive layer 5 and at which a respective layer 7 of the natural fibre material is arranged flat (see also FIG. 3a).

[0054] The support body 1 includes a central coupling region 10 having a central bore 11 for connection to a rotary drive for rotating the support body 1 or a grinding tool 2 formed therewith about an axis of rotation 12 extending through the coupling region 10. The axis of rotation 12 extends through the centre 25 of the central bore 11 and is oriented substantially normal to the side surfaces 9.

[0055] The dimensions of the support body 1 can be characterised by its diameter 17, its thickness 18 and the diameter 19 of the central bore 11.

[0056] The grinding tool 2 shown in FIG. 2 includes a support body 1 and an abrasive layer 5 having abrasive means 4, in particular superabrasive means, arranged on the circumferential support surface 3 of the support body 1. The abrasive means 4 is diagrammatically indicated in the enlarged portion. The abrasive means 4 is embedded in a binding, for example a ceramic binding.

[0057] The abrasive layer 5 can be formed from a continuous abrasive ring or, as indicated in the lower region of the grinding tool 2, individual abrasive elements 13.

[0058] In the grinding tool 2 shown in FIG. 3a the support body 1 has a side surface 9 which is separate from the support surface 3 for the abrasive layer 5 and at which a layer 7 of a natural fibre material in the form of a cotton fabric is arranged flat. That can be seen in particular from the enlarged view in which the fabric structure comprising substantially perpendicularly crossing fabric threads with weft and warp threads 26 can be seen.

[0059] To improve the rotary characteristic of the grinding tool 2 the support body 1 can have balancing bores 22 and/or a step 23.

[0060] FIG. 3b shows a microscope image of a cross-sectional surface of the composite material used in the grinding tool 2 of the second preferred embodiment. It is possible clearly to see the layers 7 of the cotton fabric, which are arranged in mutually superposed relationship in the direction of the axis of rotation 12 and which are made up of individual cotton fibres 26.

[0061] FIGS. 4a and 4b show microscope images of a further composite material which is preferably used, more specifically a side surface (FIG. 4a) and a cross-sectional surface (FIG. 4b). In this case the natural fibre material is paper. FIG. 4a shows individual paper fibres 27 arranged stochastically within a layer 7. FIG. 4b shows a structure comprising mutually superposed layers 7.

[0062] Particularly preferred embodiments of the method of producing a support body and the method of producing a grinding tool are illustrated by reference to the flow chart shown in FIG. 5.

[0063] In the method 14 of producing a support body 1 in a first method step 15 the abrasive means-free composite material 6 comprising a plurality of mutually superposed layers 7 of a natural fibre material, that are connected together by plastic 8, preferably phenolic resin, is provided in the form of a plate.

[0064] In a second method step 16 a body is cut out of the plate with predetermined dimensions 17, 18, 19 (see FIGS. 1a and 1b), preferably by water jet cutting or by means of a band saw. In the case of the support body 1 shown in FIG. 1 the body is a round disc.

[0065] In a third method step 20 the body is re-worked, preferably by cutting machining and/or balancing.

[0066] That method 14 can be expanded to constitute a method 21 of producing a grinding tool 2 insofar as, in a further method step 28, an abrasive layer 5 having abrasive means 4, preferably superabrasive means, is arranged on a preferably circumferential support surface 3 of the support body 1, preferably by pressing and/or adhesive bonding thereon, preferably wherein the abrasive layer 5 is formed from a continuous abrasive ring or individual abrasive segments 13.

[0067] The third method step 20 can optionally also be carried out only after the abrasive layer 5 is arranged on the support surface 3 of the support body 1.

[0068] FIGS. 6a and 6b show a grinding tool 2 having a support body 1 which is made up of five hollow-cylindrical bodies 29, 30, 31, 32, 33, wherein the bodies 29, 30, 31, 32, 33 are glued together at side surfaces 9. The axes of symmetry 12 of the bodies 29, 30, 31, 32, 33 are substantially coincident. Depending on the respective shape of the support body 1 it is also possible to use another number of cylindrical or hollow-cylindrical bodies 29, 30, 31, 32, 33.

[0069] The support body 1 has an adaptor 34 for connecting the support body 1 or the grinding tool 2 formed therewith to a rotary drive which is adhesively secured to the bodies 32 and 33. The adaptor 34 can also be connected to more than two or only to one of the bodies 29, 30, 31, 32, 33, in particular in dependence on the stiffness to be achieved for the grinding tool 2.

[0070] The adaptor 34 can substantially comprise a metal and, as in the illustrated case, can be substantially hollow-cylindrical.

[0071] As in the illustrated case the adaptor 34 can have bores 37 for receiving fixing means, by way of which the adaptor 34 can be connected to a machine spindle.

[0072] The support body 1 has a central bore 11. The adaptor 34 is arranged in the central bore 11, with the adaptor 34 extending only over a part of the length 35 of the central bore 11. The central bore 11 has a funnel-shaped insertion opening 36.

[0073] A respective abrasive disc 5 is circumferentially arranged on the bodies 29 and 31.

[0074] For producing the support body 1 it is appropriate in a first method step 15 to provide a plate of a thickness 18 and in a second method step 16 to cut out of the plate with predetermined dimensions 17, 18, 19, three cylindrical or hollow-cylindrical bodies 30, 32 and 33, preferably by water jet cutting or by means of a band saw.

[0075] It is also appropriate in the course of the first method step 15 to provide a further plate of a differing thickness 18 and in the course of the second method step 16 to cut out of the plate two cylindrical or hollow cylindrical bodies 29 and 31, of predetermined dimensions 17, 18, 19, preferably by water jet cutting or by means of a band saw.

[0076] In the course of the second method step 16 the bodies 29, 30, 31, 32, 33 are connected together after they have been cut out of the plates at side surfaces 9, wherein axes of symmetry 12 of the bodies 29, 30, 31, 32, 33 are brought substantially into coincident relationship.

[0077] In a third method step 20 the bodies 29, 30, 31, 32, 33 are re-worked by cutting machining, in particular to impart predetermined dimensions to the central bore 11.

[0078] In a further method step the bodies 32, 33 are connected to the adaptor 34.