Method for producing a workpiece provided with a toothing or profiling

Abstract

A method for producing a workpiece having a toothing or profiling, including the steps: a) soft machining the workpiece to produce the toothing or profiling; b) hardening the toothing or profiling; c) hard fine machining the toothing or profiling with a first tool that is a grinding worm, a grinding wheel or a honing wheel, wherein the first tool has a base body with a first elastic modulus; d) reinforcement of at least a section of the workpiece by shot blasting; and, following step d), e) repeated hard fine machining of the toothing or profiling with a second tool that is a grinding worm, a grinding wheel, a set of grinding wheels or a honing wheel. The second tool has a plastic or rubber base body with a second elastic modulus which is at most 33% of the first elastic modulus.

Claims

1. A method for producing a workpiece provided with a toothing or profiling, comprising the sequence of steps: a) soft machining of the workpiece to produce the toothing or profiling; b) hardening of the manufactured toothing or profiling; c) hard fine machining of the hardened toothing or profiling, wherein the toothing or profiling is machined with a first tool in the form of a grinding worm, a grinding wheel or a honing wheel, wherein the tool has a base body which has a first elastic modulus; d) subsequent reinforcement of at least a section of the toothing or profiling by carrying out a shot blasting process; e) following step d): repeated hard fine machining of the toothing or profiling, wherein the toothing or profiling being machined with a second tool in the form of a grinding worm, a grinding wheel, a set of grinding wheels or a honing wheel, wherein the second tool having a base body which has a second elastic modulus which is at most 33% of the first elastic modulus and wherein the second tool has a base body made of a plastic or rubber.

2. The method according to claim 1, wherein the second elastic modulus is at most 10% of the first elastic modulus.

3. The method according to claim 2, wherein the second elastic modulus is at most 5% of the first elastic modulus.

4. The method according to claim 1, wherein the first tool used according to step c) has a base body of steel or of ceramic material with embedded corundum.

5. The method according to claim 4, wherein the first tool used according to step c) is a grinding worm which is profiled or dressed according to the toothing or profile to be machined.

6. The method according to claim 1, wherein the shot blasting process carried out according to step d) is a shot peening process.

7. The method according to claim 6, wherein the shot peening process uses metal spheres or glass spheres.

8. The method according to claim 1, wherein after step d) and before step e) the workpiece is cleaned.

9. The method according to claim 8, wherein after step d) and before step e) the workpiece is washed.

10. The method according to claim 1, wherein the first tool used according to step c) is a steel grinding wheel or set of grinding wheels coated with abrasive material.

11. The method according to claim 1, wherein the second tool used according to step e) has a base body made of polyurethane.

12. The method according to claim 1, wherein the second tool used according to step e) has a base body in which abrasive material is embedded and which is shaped according to the toothing or profiling to be machined.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the drawings:

(2) FIG. 1 show in perspective view a workpiece to be machined in the form of a gear wheel which is polished ground by a worm-shaped tool, and

(3) FIG. 2 shows a flow chart for the method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) In FIG. 1 a partial step of the proposed manufacturing process for the production of a workpiece 2 in the form of a gearwheel is depicted; workpiece 2 has a toothing 1, which is to be produced with high geometric precision and high surface quality.

(5) Shown is the step of polishing grinding by means of a tool 3 in the form of a grinding worm. The grinding worm 3 has a base body 4, which in the shown embodiment consists of polyurethane. Abrasive particles are embedded in the material of the base body 4, so that abrasive areas 5 are formed on the surface of the grinding worm 3, which are used for machining the toothing 1.

(6) The entire production process of workpiece 2 is shown in FIG. 2.

(7) Accordingly, the soft machining is carried out first, in which the toothing 1 is machined into a metallic base body. This can be done by hobbing, for example.

(8) The soft machining is followed by the heat treatment which hardens the tooth flanks.

(9) Once workpiece 2 has been hardened, the next machining step is hard finishing. FIG. 2 shows three alternative options, namely generative grinding (generative grinding), profile grinding and gear honing. If generative grinding is carried out with a grinding worm, the situation is the same as shown in FIG. 1, except that a largely rigid tool 3 is used, which undergoes practically no deformation when the forces occur during grinding. For this purpose, for example, a ceramic base body 4 is used as the grinding worm, in which corundum grains are embedded, whereby the grinding worm is provided with the required abrasive areas 5 by a dressing process. In the same way, it is also possible to use a steel base body tool which is coated with abrasive material on the surface to provide the abrasive areas 5.

(10) FIG. 2 also shows that after hard finishing, reinforcement shot blasting is performed. This involves for example shot peening to strengthen areas of the workpiece or gear teeth. The areas to be hardened are bombarded with balls made of, for example, cast steel, wire mesh, ceramics or glass, so that the surface hardens or is reinforced.

(11) After reinforcing, the polish grinding already described above is then carried out, which is done with a grinding worm 3 in the depicted embodiment, but this can also be done with a profile grinding wheel, for example.

(12) Essential for this repeated hard fine machining of toothing 1 is that the tool 3, in the depicted embodiment thus the grinding worm, has a base body 4 whose elastic modulus is considerably lower than the elastic modulus of the base body of the tool with which the generative grinding, the profile grinding or the gear honing were performed after the heat treatment.

(13) So, for example, grinding is carried out after heat treatment with a grinding worm, which has a base body of ceramic material in which corundum grains are embedded, whereby the base body was dressed according to the required shape and thus provided with the abrasive areas 5. The elastic modulus for ceramics with embedded corundum is in the range between 18,000 and 32,500 N/mm.sup.2. Alternatively, the basic body can also be made of steel and have the areas or surfaces 5 coated with abrasive material; in this case the elastic modulus is 210,000 N/mm.sup.2.

(14) On the other hand, tool 3 shown in FIG. 1 is used for polish grinding, the base body 4 of which consists of polyurethane, for example, in which abrasive particles are embedded. After profiling tool 3 in the form shown in FIG. 1 (for example by casting the polyurethane with abrasive particles into a corresponding mould), similar abrasive areas 5 are thus present. The elastic modulus here, for example, is 3,500 N/mm.sup.2. As an example of a material useful for the present invention, “ARTIFEX” from ARTIFEX Dr. Lohmann GmbH & Co. KG, Kaltenkirchen, DE, should be mentioned.

(15) It follows that the elastic modulus E.sub.1 of the first tool used for hard finishing after heat treatment is much higher than the elastic modulus E.sub.2 of the tool used for polishing after reinforcement shot blasting. The ratio of the elastic modulus is at least 3:1, but can also be considerably higher.

(16) The tool used for polish grinding is therefore relatively elastic and adapts to the prefabricated shape of toothing 1 without removing relevant parts of the hardened material.

(17) While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.