Method for surface treatment, roller bearing component and device

Abstract

A method for surface treatment of a workpiece includes providing the workpiece with hardened workpiece surface, clamping the workpiece, removing material from the hardened workpiece surface with a material removal tool to produce a machined surface with first machining tracks, and rolling the machined surface with a rolling tool by overlapping the first machining tracks to produce a rolled surface with second machining tracks. A distance between the material removal tool and the rolling tool measured in an axial direction of the workpiece is varied in an oscillating manner. The material removal tool may be advanced in the axial direction at a constant speed and the rolling tool may be advanced in the axial direction at an oscillating speed, or the rolling tool may be advanced in the axial direction at a constant speed and the material removal tool may be advanced in the axial direction at an oscillating speed.

Claims

1. A method for surface treatment of a workpiece, the method comprising: providing the workpiece, the workpiece comprising a hardened workpiece surface; providing a material removal tool and a rolling tool, the rolling tool being independently clamped relative to the material removal tool and arranged at a distance offset from the material removal tool in an axial direction of the workpiece; clamping the workpiece; simultaneously machining the workpiece by: removing material from the hardened workpiece surface with the material removal tool to produce a machined surface with first machining tracks; and rolling the machined surface with the rolling tool by overlapping the first machining tracks to produce a rolled surface with second machining tracks, wherein the distance between the material removal tool and the rolling tool measured in the axial direction of the workpiece is varied in an oscillating manner.

2. The method of claim 1, wherein the material removal tool is advanced in the axial direction at a constant speed and the rolling tool is advanced in the axial direction at an oscillating speed.

3. The method of claim 1, wherein the rolling tool is advanced in the axial direction at a constant speed and the material removal tool is advanced in the axial direction at an oscillating speed.

4. The method of claim 1, wherein the rolling tool is advanced in the axial direction at a first oscillating speed and the material removal tool is advanced in the axial direction at a second oscillating speed, different than the first oscillating speed.

5. The method of claim 1, wherein: a feed direction of the rolling tool is reversed in an oscillating manner while a feed direction of the material removal tool is maintained; or a feed direction of the material removal tool is reversed in an oscillating manner while a feed direction of the rolling tool is maintained.

6. The method of claim 1, wherein: a feed direction of the material removal tool is reversed in an oscillating manner; and a feed direction of the rolling tool is reversed in an oscillating manner.

7. A method for surface treatment of a workpiece, the method comprising: providing the workpiece, the workpiece comprising a hardened workpiece surface; providing a material removal tool and a rolling tool, the rolling tool being independently clamped relative to the material rolling tool and arranged at a distance offset from the material removal tool in an axial direction of the workpiece; clamping the workpiece; simultaneously machining the workpiece by: removing material from the hardened workpiece surface with the material removal tool to produce a machined surface with first machining tracks; and rolling the machined surface with the rolling tool by overlapping the first machining tracks to produce a rolled surface with second machining tracks, wherein a feed direction of the material removal tool or the rolling tool in the axial direction of the workpiece is reversed in an oscillating manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, several exemplary embodiments of the disclosure are explained by way of example by means of the drawings. In the figures:

(2) FIG. 1 shows a schematic representation of a section of a first device for surface treatment of a workpiece,

(3) FIG. 2 shows a schematic representation of a section of another device for surface treatment of a workpiece, and

(4) FIGS. 3 to 5 show different variants of machining tracks which can be generated with the device according to FIG. 2.

DETAILED DESCRIPTION

(5) A first device, identified as a whole by the reference symbol 11, includes a material removal tool 3 in the form of a turning tool and a rolling tool 12. The tools 3, 12 are provided for the simultaneous machining of a workpiece 1 (shown only partially and in section), namely a bearing ring of a roller bearing. In the process, a workpiece surface 2 is generated which is intended to function as a roll body raceway within the roller bearing to be produced.

(6) The starting point of the method that can be carried out with the device 11 is an already hardened workpiece surface 10. The hard turning by means of the turning tool results in a surface 9 which has a typical structure produced by turning. The process of turning takes place with a translational speed V.sub.ax3 and a tangential speed V.sub.tan. The direction of the translational speed V.sub.ax3 corresponds to the alignment of the axis of rotation of the workpiece 1, i.e., its axial direction.

(7) The rolling tool 12 is arranged offset to the material removal tool 3 in the longitudinal direction of the axis of rotation of the workpiece 1 and includes a ball as the rolling element 4. The ball is subjected to the pressure of a hydraulic medium in a manner known per se. During the machining of the workpiece 1, the rolling tool 12, including the ball, is advanced relative thereto at a translational speed V.sub.ax12, which can be varied in various ways relative to the translational speed V.sub.ax3, as will be explained in more detail below. In contrast, the tangential speed of the rolling tool 12 relative to the workpiece 1, denoted by V.sub.tan, corresponds to the tangential speed V.sub.tan of the material removal tool 3. This applies in cases in which the surface to be machined of the workpiece 1 is cylindrical, as outlined in the exemplary embodiment. In the case of a conical or spherically curved surface of the workpiece 1, the tangential speeds deviate from one another without fundamentally changing the machining process. In any case, the finished surface 2 is produced by the rolling tool 12.

(8) Both tools 3, 12, i.e., the material removal tool 3, on the one hand, and the rolling tool 12, on the other hand, are independently clamped in the first device 11, which carries out the method according to the disclosure, so that the necessary oscillation of the feed rate takes place from the machine axes. Here, the feed rate V.sub.ax3 of the material removal tool 3 and/or the feed rate V.sub.ax12 of the rolling tool 12 can be changed in an oscillating manner in order to specifically influence the formation of the intersection points in the area of the machining tracks that are formed during turning and rolling.

(9) FIG. 2 now shows a further device, identified as a whole by the reference symbol 11′, comprising a material removal tool 3 in the form of a turning tool and a rolling tool 12. The same reference characters as in FIG. 1 indicate identical elements.

(10) The starting point of the method that can be carried out with the further device 11′ is likewise an already hardened workpiece surface 10. The hard turning by means of the turning tool results in a surface 9 which has a typical structure produced by turning. The process of turning takes place with a translational speed V.sub.ax3 and a tangential speed V.sub.tan. The direction of the translational speed V.sub.ax3 corresponds to the alignment of the axis of rotation of the workpiece 1, i.e., its axial direction.

(11) The rolling tool 12 is arranged offset to the material removal tool 3 in the longitudinal direction of the axis of rotation of the workpiece 1 and includes a ball as the rolling element 4. The ball is subjected to the pressure of a hydraulic medium in a manner known per se. During the machining of the workpiece 1, the rolling tool 12, including the ball, is advanced relative thereto at a translational speed V.sub.ax12, which can be varied in various ways relative to the translational speed V.sub.ax3, as will be explained in more detail below. In contrast, the tangential speed of the rolling tool 12 relative to the workpiece 1, denoted by V.sub.tan, corresponds to the tangential speed V.sub.tan of the material removal tool 3. This applies in cases in which the surface to be machined of the workpiece 1 is cylindrical, as outlined in the exemplary embodiment. In the case of a conical or spherically curved surface of the workpiece 1, the tangential speeds deviate from one another without fundamentally changing the machining process. In any case, the finished surface 2 is produced by the rolling tool 12.

(12) The material removal tool 3, on the one hand, and the rolling tool 12, on the other hand, each comprise a carriage S.sub.3, S.sub.12 which, in accordance with its deflectability, allows for an oscillating reversal of the feed direction (here from left to right in the picture) of the material removal tool 3 and the rolling tool 12. The further device 11′, in which the material removal tool 3 and the rolling tool 12 are attached, is equipped with two oscillation units which excite each of the two carriages S.sub.3, S.sub.12 to an oscillatory movement Ow, Oz in the horizontal direction.

(13) Thus, the position of the material removal tool 3 relative to the workpiece 1 can be changed—caused by the oscillation of the carriage S.sub.3—in the horizontal direction so that areas already machined with the turning tool come again into engagement with the turning tool.

(14) Furthermore, the position of the rolling tool 12 relative to the workpiece 1 can be changed—caused by the oscillation of the carriage S.sub.12 in the horizontal direction so that areas already traversed by the rolling tool 12 again come into engagement with the rolling tool 12.

(15) As a result, the distance between the material removal tool 3 and the rolling tool 12 here can also be changed in an oscillating manner in order to specifically influence the formation of the intersection points in the area of the machining tracks that are formed during turning and rolling.

(16) Of course, a device according to the disclosure can also be embodied with only one of the carriages S.sub.3, S.sub.12. An embodiment of a device, not shown in FIGS. 1 and 2, according to a combination of the embodiment according to FIG. 1 and the embodiment according to FIG. 2 is also possible.

(17) In FIGS. 3 to 5, various machining tracks BW, BS are sketched, generated by the rolling tool 12 or by the material removal tool 3 on the finished workpiece surface 2, using a further device 11′ according to FIG. 2. The tangential direction designated by Ta corresponds to the direction in which the tangential velocity V.sub.tan is to be measured. The translational direction Tr, orthogonal thereto, corresponds to the longitudinal direction of the axis of rotation of the workpiece 1, i.e., the direction in which the speeds V.sub.ax3, V.sub.ax12 are to be measured.

(18) In the case of FIG. 3, the material removal tool 3 is advanced at a constant translational speed V.sub.ax3 during hard turning. In contrast thereto, the rolling tool 12 performs oscillations in the translational direction Tr. In the present case, these oscillations are approximately sinusoidal. In a modified execution of the method, it could be, for example, zigzag-shaped tracks.

(19) As a result, numerous crossing points KP arise between the machining track BS of the material removal tool 3 and the machining track BW of the rolling tool 12. Depending on the machining parameters, the machining tracks BS, BW on the finished surface 2 of the workpiece 1 can be weak or no longer recognizable by conventional means. By controlling the device 11′, however, the machining tracks BS, BW are predetermined in a defined manner in all cases. This also applies to the machining variants according to FIGS. 4 and 5.

(20) In the case of FIG. 4, the material removal tool 3 performs oscillations in the translational direction Tr. In contrast, the rolling tool 12 in this case moves at a constant translational speed V.sub.ax12 with respect to the workpiece 1. This creates an overall helically wound shape of the machining track BW, whereas an oscillation in the axial direction Tr, i.e., in the direction of the axis of rotation of the workpiece 1, is superimposed on the machining track BS of the helical shape.

(21) In the case outlined in FIG. 5, there is both an oscillation of the material removal tool 3 and an oscillation of the rolling tool 12, each in the translational direction Tr. In this case, too, numerous crossing points KP arise between the different machining tracks BS, BW. Each crossing point KP lies within a surface element OE, in which none of the machining tracks BS, BW run exactly in the tangential direction Ta. The frequency with which the translational speed V.sub.ax3 oscillates in the case of FIG. 5 is identical to the frequency with which the translational speed V.sub.ax12 oscillates. In an alternative, other ratios between the frequencies mentioned can also be selected. In any case, the frequency with which the translational speed V.sub.ax3, V.sub.ax12 of at least one of the tools 3, 12 oscillates is higher than the frequency with which the workpiece 1 rotates.

REFERENCE NUMERALS

(22) 1 Workpiece, bearing ring 2 Workpiece surface, finished 3 Material removal tool 4 Ball, rolling element 9 Surface, hard turned, but not yet rolled 10 Workpiece surface, hardened, otherwise not yet further processed 11 Device 11′ Device 12 Rolling tool S3 Carriage on the material removal tool S12 Carriage on the rolling tool BS Machining track of the material removal tool BW Machining track of the rolling tool KP Crossing point OE Surface element Oz Oscillation movement of the carriage S3 Ow Oscillation movement of the carriage S12 Tr Translational direction, axial direction Ta Tangential direction Vax3 Translational speed of the material removal tool Vax12 Translational speed of the rolling tool V tan Tangential speed