LASER-ASSISTED PRODUCTION METHOD FOR A GEARING COMPONENT AND GEARING

Abstract

In a method for making a tooth system of a gearing component, an unfinished tooth-system part is heat-treated. At least part of an oxide layer on the unfinished tooth-system part is mechanically removed, while leaving a residual oxide layer in at least one region, and the residual oxide layer is at least partially removed by irradiating with a laser at least a portion of the residual oxide layer.

Claims

1. A method for making a tooth system of a gearing component, comprising: heat-treating an unfinished tooth-system part; mechanically removing at least partially an oxide layer on the unfinished tooth-system part, while leaving a residual oxide layer in at least one region; and removing at least partially the residual oxide layer by irradiating with a laser at least a portion of the residual oxide layer.

2. The method of claim 1, wherein the laser causes a melting and/or vaporizing of the residual oxide layer or of a base material layer covered directly by the residual oxide layer.

3. The method of claim 1, further comprising mechanical strengthening the unfinished tooth-system part after at least partially removing the residual oxide layer.

4. The method of claim 1, wherein the mechanical removal of the oxide layer is executed by a process selected from the group consisting of abrasive blast cleaning, brushing, and a combination thereof.

5. The method of claim 4, wherein the abrasive blast cleaning includes shot blasting and water jet blasting.

6. The method of claim 1, wherein the unfinished tooth-system part is produced from a free-machining steel, a case-hardened steel, a heat-treatable steel, a nitrided steel or a hardened steel.

7. The method of claim 1, wherein the residual oxide layer is in the form of surface oxidation and has a thickness of 10 m to 100 m.

8. The method of claim 1, wherein the at least one region in which the residual oxide layer remains is a tooth base.

9. The method of claim 1, wherein the laser is oriented on the basis of a reference profile of the tooth system to be produced or on the basis of a detected actual profile of the unfinished tooth-system part.

10. The method of claim 1, wherein the laser is arranged equidistant from a tooth profile to be irradiated.

11. The method of claim 3, wherein the unfinished tooth-system part remains in a same clamp in a clamping mechanism while the residual oxide layer is at least partially removed and the unfinished tooth-system part is mechanically strengthened.

12. A non-transitory computer program product for defining orientation, intensity and/or focal point of a laser, said computer program product comprising program instructions which when loaded into a memory of a controller causes the controller to perform the steps of heat-treating an unfinished tooth-system part; mechanically removing at least partially an oxide layer on the unfinished tooth-system part, while leaving a residual oxide layer in at least one region; and removing at least partially the residual oxide layer by irradiating with a laser at least a portion of the residual oxide layer.

13. Apparatus, comprising: a clamping mechanism for fixing an unfinished tooth-system part; a first tool unit configured to mechanically remove an oxide layer on the unfinished tooth-system part; a laser unit configured to irradiate at least one region of the unfinished tooth-system part; and a controller including a memory for storing and executing a computer program product as set forth in claim 12.

14. A gearing component, comprising a main body having a tooth system and embodied as a ring gear, a planet gear, or a sun gear of a planetary gearset, or as a gear wheel of a spur gearset or of a bevel gearset, wherein the tooth system is produced by a method as set forth in claim 1.

15. A gearing embodied as a planetary gearset, as a spur gearset, or as a bevel gearset, said gearing comprising a gearing component as set forth in claim 14.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0022] Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

[0023] FIG. 1 is a schematic microscopic sectional view of a surface of an unfinished tooth-system part between two method steps according to the present invention;

[0024] FIG. 2 is a schematic view of an unfinished tooth-system part during a third method step according to a first embodiment of a method according to the present invention;

[0025] FIG. 3 is a schematic view of an unfinished tooth-system part during a third method step according to a second embodiment of a method according to the present invention;

[0026] FIG. 4 is a schematic microscopic sectional view of a surface of an unfinished tooth-system during the third method step;

[0027] FIG. 5 is a schematic illustration of an apparatus according to the present invention; and

[0028] FIG. 6 is a sequence diagram of making a tooth system of a gearing component in accordance with the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0029] Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

[0030] Turning now to the drawing, and in particular to FIG. 1, there is shown a schematic microscopic sectional view of a surface 13 of an unfinished tooth-system part, generally designated by reference numeral 25 and intended to be processed into a gearing component. The surface 13 shown in FIG. 1 is part of a tooth system 12 to be produced. The unfinished tooth-system part 25 includes a base material layer 24, which is located mainly inside the unfinished tooth-system part 25. The base material layer 24 is made of a metallic material, for instance a free-machining steel, a case-hardened steel, a heat-treatable steel, a nitrified steel or a hardened steel. In a first method step 110 (FIG. 6), residual compressive stress is introduced in the unfinished tooth-system part 25 as a result of a heat treatment in the form of case hardening. Alternatively, other forms of heat treatment can also be used. Formed on the base material layer 24 is a residual oxide layer, which remains on the surface 13 after partial removal of an oxide layer (not shown).

[0031] FIG. 1 depicts the unfinished tooth-system part 25 between a second method step 120 (FIG. 6), in which the oxide layer is partially removed, and a third method step 130 (FIG. 6), in which the residual oxide layer is treated. The residual oxide layer is formed mainly as oxide inclusions 26, which lie in the region of the surface 13. Measured relative to a surface reference plane 17, which lies in the region of a highest roughness point 28 of the surface 13, the oxide inclusions 26 are situated at a depth of 10 m to 100 m in the unfinished tooth-system part 25. This defines a layer thickness 27, represented by a double-ended arrow, of the residual oxide layer. In addition, the oxide layer may also have a cracked structure.

[0032] FIG. 2 shows schematically a segment of the unfinished tooth-system part 25, which is to be processed into a gearing component, such as a gear tooth 16. The unfinished tooth-system part 25 includes a main body 11, on which the tooth system 12 is to be formed. FIG. 2 represents a schematic view of the unfinished tooth-system part according to a first embodiment of a method of the present invention. The tooth system 12 has a plurality of teeth 16. After undergoing the heat treatment, in particular case hardening, in method step 110, and partial removal of the oxide layer formed thereby on the surface 13 in method step 120, a residual oxide layer is formed on a tooth flank 15 in the region of a tooth base 18. The residual oxide layer includes oxide inclusions 26, which are contained in the surface 13. During the third method step 130 depicted in FIG. 2, a processing region 20 on the surface 13 of the unfinished tooth-system part 25 is irradiated. A laser 32 associated with a laser unit 30 (FIG. 4) performs the irradiation. For this purpose, the laser 32 directs laser beams 33 onto the processing region 20, in which a residual oxide layer in the form of oxide inclusions 26 is located. Irradiation by the laser 32 causes melting and/or vaporization of oxide inclusions 26. Material from the base material layer 24 may also be melted or vaporized as well by the irradiation.

[0033] The laser 32 can be controlled by a user or a computer program product (not shown in further detail), e.g. by controlling intensity. The laser 32 can move along a profile of the tooth base 18 and/or of the tooth flanks 15. By an appropriate processing movement as indicated by dash-dotted arrow 35, the tooth flanks 15 and the tooth base 18 can be irradiated by the laser 32 in portions, i.e. in a plurality of processing regions 20. The irradiation by the laser 32 removes the residual oxide layer at least partially. Irradiation by the laser 32 enables to counteract the strength-reducing effect of the oxide inclusions 26 while preserving any residual compressive stress present in the unfinished tooth-system part 25. The laser 32 is positioned substantially equidistant from the tooth flanks 15 and the tooth base 18. By means of a simple, substantially linear, movement of the laser 32, it is possible to irradiate a large region of the unfinished tooth-system part 25 without a change in the settings of the laser 32. In particular, during the processing movement 35, the surface 13 is irradiated at a constant focal-point distance as indicated by arrow 36. This facilitates rapid manufacture.

[0034] FIG. 3 shows schematically a second embodiment of the third method step 130. Same reference characters in FIG. 3 have a same technical meaning as in FIG. 2. According to the embodiment shown in FIG. 3, the laser beams 33 in the processing region 20 are directed substantially linearly onto the surface 13. In addition to a processing movement 35 along the tooth base 18, a rotational movement of the laser 32 as indicated by arrow 39 is executed. During the rotational movement 39, by virtue of a known profile of the surface 13 in the region of the tooth flanks 15 and of the tooth base 18, it is easily possible to adjust the settings of the laser 32, in particular the focal-point distance 36. This allows the laser 32 to be adapted easily to the shape of the unfinished tooth-system part 25 to be processed, and provides particularly thorough removal of the residual oxide layer. This is accordingly repeated portion by portion for a plurality of processing regions 20.

[0035] FIG. 4 shows a schematic microscopic sectional view of the surface 13 of the unfinished tooth-system during the third method step 130, as the surface 13 is irradiated by the laser 32 of laser unit 30. The third method step 130 is performed in a processing region 20, in which the surface 13 of the tooth system 12 on the unfinished tooth-system part 25 is being processed. The unfinished tooth-system part 25 is in particular a gearing component. A laser beam 33 is directed with selectable intensity onto the surface 13 which has formed thereon at least on a portion thereof a residual oxide layer in the form of a plurality of oxide inclusions 26, which are disposed in the base material layer 24. The position of the oxide inclusions 26 defines in relation to the reference plane 17 a layer thickness 27 which is selected such that the reference plane 17 envelops the roughness points 28 lying on the surface 13. The layer thickness 27 equals between 10 m and 100 m. The base material layer 24 contains no oxide inclusions 26 below the residual oxide layer, and is interspersed with oxide inclusions 26 in the region of the residual oxide layer.

[0036] The laser beam 33 is directed with selectable intensity onto a surface fragment 40, on which a focal point 37 of the laser beam 33 is located. The position of the focal point 37 can be selected, inter alia, by setting the focal-point distance 36. Thus the laser 32 supplies the surface fragment 40 with energy, which is converted there into thermal energy. The supply of thermal energy causes vaporization of the surface fragment 40 at least to some extent. Remaining pieces of the surface fragment 40 are removed mechanically by resultant pressure during at least partial vaporization. In this process, non-vaporized pieces of the surface fragment 40 peel off as indicated by arrow 44. In addition, vaporization and peeling-off of the surface fragment 40 can be adjusted by an irradiation period that can be selected by the user and/or a computer program product. Heat input by the laser beam 33 from surface fragment 40 to be removed into the base material layer 24, as indicated by arrow 45, is reduced by performing vaporization and peeling-off in a short time interval. At least irradiation period, intensity and the focal-point distance 36 can be suitably selected such that at least partial vaporization and peeling-off of the surface fragment 40 in method step 130 takes places reliably in as short a time period as possible with minimum energy input from the laser 32.

[0037] Referring now to FIG. 5, there is shown a schematic illustration of a processing apparatus according to the present invention, generally designated by reference numeral 70, for implementing a production method according to the present invention. The processing apparatus 70 includes a clamping mechanism 72, in which an unfinished tooth-system part 25 is clamped during the production method. The processing apparatus 70 is used to process a tooth system 12 on the unfinished tooth-system part 25, in order to produce thereby a gearing component from the unfinished tooth-system part 25. In the course of the first method step 110, the unfinished tooth-system part 25, which is case-hardened, is clamped in the clamping mechanism 72. The processing apparatus 70 includes a first tool unit 74, e.g. a shot blasting system, to remove, in the second method step 120, mechanically at least partially the oxide layer produced on the surface 13 of the unfinished tooth-system part 25 during heat treatment, such as case hardening for instance. After partial mechanical removal, remaining parts of the oxide layer form the residual oxide layer. The residual oxide layer is removed at least partially by the laser unit 30 in the third method step 130. For this purpose the laser 32 of the laser unit 30 emits a laser beam 33. The laser unit 30 is designed to be moved along a plurality of movement axes indicated by arrows 38 so as to achieve, for example, a desired orientation and/or a rotational movement of the laser 32, and to guide the laser 32 along the direction of the desired processing movement 35. In addition, the laser beam 33 emitted by the laser 32 can be adjusted, at least in terms of intensity, focal-point distance 36 and irradiation period. The adjustment is implemented by an input from a user and/or by a computer program product, by means of which, inter alia, the laser unit 30 is controlled.

[0038] The processing apparatus 70 further includes a second tool unit 76, e.g. a shot blasting system. The second tool unit 76 is intended to process the unfinished tooth-system part 25 in the fourth method step 140, and thereby achieve mechanical strengthening of the surface 13 of the unfinished tooth-system part 25. The processing apparatus 70 also includes a first controller 47, which is assigned directly to the processing apparatus 70. A computer program product remanently stored in the first controller 47 is executed there. The computer program product is designed to execute at least part of the production method according to the present invention. For this purpose, the computer program product can control the first tool unit 74, the second tool unit 76 and/or the laser unit 30 In an open-loop and/or closed-loop manner. The first controller 47 Is connected via a data link 48 to a second controller 49, on which is also remanently stored a computer program product, which can be executed on the second controller 49. The computer program products in the first and second controllers 47, 49 communicate via the data link 48. Individual functions of the production method, for instance individual method steps 110, 120, 130, 140, or inputs of parameters, for instance irradiation period and/or intensity of the laser beam 33, can be implemented separately on the two controllers 47, 49. The data link 48 realizes, in conjunction with the first and second controllers 47, 49, the production method using the production apparatus 70.

[0039] FIG. 6 is a sequence diagram of making a tooth system 12 of, e.g., a gearing component in accordance with the present invention. The production method includes the first method step 110, in which the unfinished tooth-system part 25 is in the state after case hardening, and has an oxide layer on its surface 13. In the following second method step 120, the first tool unit 74 performs at least partial mechanical removal of the oxide layer. As a result of the second method step 120, a residual oxide layer still remains from the oxide layer on the unfinished tooth-system part 25. In the following third method step 130, the laser unit 30 is used to remove the residual oxide layer at least partially. The laser unit 30 directs the laser 32 onto the unfinished tooth-system part 25. Intensity of the laser 32 is adjustable by a setting from a user and/or from a computer program product In the fourth method step 140, the second tool unit 76 is used to achieve mechanical strengthening on the surface 13 of the unfinished tooth-system part 25. The fourth method step 140 is followed by an end state 200 of the production method. In the end state 200, the unfinished tooth-system part 25 is removed as gearing component for optional further processing.

[0040] The production method as shown in FIG. 6 can be used to produce ring gears, planet gears, and sun gears for a gearing 61, in particular a planetary gearing. It is equally possible to use the described production method to produce also gear wheels for spur gearing or bevel gearing.

[0041] While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

[0042] What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: