WO2001021349A1

WO2001021349A1 - Device for turning ball cages intended for homocinetic joints

Info

Publication number: WO2001021349A1
Application number: PCT/EP2000/009296
Authority: WO
Inventors: Guido Kochsiek
Original assignee: Iprotec Maschinen- Und Edelstahlprodukte Gmbh
Priority date: 1999-09-23
Filing date: 2000-09-22
Publication date: 2001-03-29
Also published as: AU7906300A

Abstract

The invention relates to a device containing a blade holder (9, 10) in which at least one blade is held in an exchangeable manner. Said device is used for turning ball cages which are intended for homocinetic joints and which have ball ring-shaped inner and outer bearing surfaces. The aim of the invention is to create a device of this type which makes a simple, economical and fully automatic production possible while observing the narrowest tolerances. To this end, the blade holder (9, 10), with regard to a center of rotation (7) located in a machining plane (16), can be moved within the machining plane (16) in a rotatory manner and, optionally, in a translatory manner.

Description

Device for turning machining of Kuqelkäfiq intended for constant velocity joints

The invention relates to a device, comprising a cutter holder, which interchangeably accommodates at least one cutting edge, for turning machined ball cages for constant velocity joints with spherical ring-shaped inner and outer bearing surfaces.

The use of constant velocity joints is known in particular in connection with motor vehicles. Steered wheels are driven in front wheel drive vehicles. For this reason, front or, if necessary, rear wheel axle shafts must have joints that allow both the compression and rebound of the wheels and their steering angle. Therefore, constant velocity joints are used to enable the wheels to be driven as uniformly as possible. In the case of joints on front wheel axle shafts, constant velocity fixed joints designed as cup joints are used here, while in the case of joints on rear axle shafts, constant velocity sliding joints designed as cup joints are used which, in addition to bending the joint, enable axial displacement.

In the case of the constant velocity joints known from practice, the ball cages provided with spherical inner and outer bearing surfaces and ball pockets for receiving the torque-transmitting balls are first produced in a variety of rolling, forging, punching and turning operations on various machines as blanks. Starting from these blanks, the Finishing of the ball cages then in turn in a multitude of work steps on different machines, with grinding processes for machining the bearing surfaces and for machining the contact surfaces being used in particular as machining processes. It is also known from the prior art to use the turning machining method instead of the grinding method as a machining method. Here it is known to use CNC-controlled lathes, the cutting edge holder of which is arranged to be continuously movable in the translatory direction. To form both the inner and the outer spherical bearing surface, it is therefore necessary to simultaneously move the cutter holder both in one direction of movement and in the other direction of movement in order to obtain a spherical ring-shaped configuration. A disadvantage of the previously known lathes, however, is that, in the case of an embodiment of a spherical ring-shaped ring surface, the cutting edge rests on the surface to be machined at a constantly changing angle by moving the cutting edge holder in the translational direction. In other words, the pressure angle of the cutting edges on the workpiece changes continuously in the course of the surface treatment. As a consequence, inaccuracies in the material removal result disadvantageously. In addition, the cutting edges are worn unevenly under the influence of different cutting angles, so that tolerances can only be maintained within certain limits. This uneven wear leads to a faulty end geometry on the workpiece. The permissible wear limits of the inserts can therefore not be exploited, which reduces the tool life. The finishing of the ball cages according to the methods known from the prior art is therefore time-consuming and costly.

To avoid the disadvantages mentioned above, the invention is therefore based on the object of providing a device for turning ball cages intended for constant velocity joints, which allows simple, inexpensive and fully automated production while observing the narrowest tolerances. The solution of this task is characterized according to the invention characterized ^'in that the blade holder onto a machining plane lying in a pivot point is movable relative rotationally within the working plane.

With the device according to the invention for turning ball cages intended for constant velocity joints, it is possible for the first time to carry out production in a simple and economical manner while maintaining the tightest tolerances. The device according to the invention includes a cutter holder that has at least one cutting edge that can be exchanged and that can be rotated within the processing plane. Advantageously, this creates the possibility of forming both the inner and the outer spherical bearing surfaces while always maintaining the same pressure angle of the cutting edge to the workpiece to be machined. It is hereby achieved that regardless of the position of the cutters held by the cutter holder, the surface is always processed in the same way. This ensures compliance with tolerances within very narrow limits. In addition, it advantageously results that wear of the cutting edges occurs selectively on the cutting edge as a result of the signs of wear that occur during operation, and a defined readjustment is thus made possible. Regardless of the wear on the cutting edge, the process always results in an exact spherical geometry. An inaccurate production that does not meet a narrow tolerance range can therefore be excluded. Due to the fact that spherical geometries are always generated due to the process, there is also the advantage that only spherical radius or diameter have to be checked with regard to quality assurance. Checks of the spherical geometry that have hitherto been necessary can thus advantageously be omitted. Advantageously, in addition to the rotational movability given within the machining plane, translational movability within the machining plane is also realized.

According to a further feature of the invention, the axis of rotation of the ball cage lies in the working plane. This ensures that a movement carried out by the cutting holder leads to a precisely specifiable surface treatment. The precise reproducibility of a high Geometry accuracy and a high surface quality bearing surface is thus ensured.

According to a further feature of the invention, the translational movement of the cutter holder is possible in two directions that are linearly independent of one another. Additional reclamping of the ball cage to be machined is avoided in this way, since the cutter holder can approach every point of the ball cage to be machined. Furthermore, it is proposed according to the invention that a circular movement of the cutting edge holder can be carried out around a pivot point within the working plane. In this way it is ensured that, in addition to the accessibility of each surface point of the ball cage to be machined, the machining edge can be placed on the workpiece at a constant angle. The formation of spherical bearing surfaces, both the inner and the outer, is thus carried out according to the invention while adhering to narrow tolerances and avoiding wear-related uneven wear.

According to a further feature of the invention, the cutting edge holder can be moved linearly to form the front-side contact surface and the cylindrical receiving surface, all machining operations being able to be carried out with one and the same device. This avoids unnecessarily frequent reclamping of the ball cage. It is shown overall that the turning can be carried out on the same lathe, it being only necessary to machine the different surfaces in a first step to form the inner bearing surface as well as the receiving surface and the contact surface and to produce the outer bearing surface in a second step. Since the turning process can be carried out on the same machine on the one hand and the cutter holder can also be moved both translationally and rotatably within the processing plane, it is possible to use the device according to the invention fully automatically, quickly and inexpensively while maintaining the tightest tolerances to form individual ring areas.

In addition to the rotational and translational movability of the cutting edge holder within the working plane, it advantageously also has an additional possibility of movement. This consists in ^'that the blade holder is movable along the feed axis in a small area. This enables the ball radius to be precisely defined, for example if the cutting edges have changed due to wear. A continuous movement of the cutter holder is also possible, so that geometries deviating from the circular geometry can also be generated in partial areas.

Further features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings. Show:

Figure 1 is a sectional side view of a ball cage.

Fig. 2 starting position of the cutter holder before forming the front contact surface;

Fig. 3 end position of the cutter holder after formation of the front contact surface;

Fig. 4 starting position of the cutter holder before forming the cylindrical receiving surfaces;

Fig. 5 end position of the cutter holder after formation of the cylindrical receiving surfaces;

Fig. 6 starting position of the cutter holder before forming the inner spherical bearing surface;

7 end position of the cutter holder after formation of the inner spherical bearing surface;

Fig. 8 rest position of the cutter holder after formation of the inner contour of the ball cage;

Fig. 9 rest position of the cutter holder before forming the outer contour of the ball cage; Fig. 10 starting position of the cutter holder before forming the outer spherical bearing surface;

Fig. 11 end position of the cutter holder after formation of the outer spherical bearing surface.

1 shows a cut side view of a finished machined ball cage 1. The ball cage 1 has an outer spherical bearing surface 2, an inner spherical bearing surface 3 and ball pockets 4 for receiving torque-transmitting balls (not shown here).

Starting from a ball cage blank produced from a tube, the further processing of the ball cage 1 takes place by means of a turning process. For turning both the inner and the outer spherical bearing surfaces 2 and 3 as well as for turning the cylindrical receiving surfaces 5 and the front bearing surfaces 6, the ball cage 1 has to be reclamped once. This reclamping can take place automatically, so that the entire turning of the ball cage 1 can also take place fully automatically and therefore continuously.

In a first setup, the ball cage 1 to be machined is clamped in such a way that the inner contour can first be rotated in a first process step. This is shown in FIGS. 2 to 8. During this first section of the process, in a first step the end face 6 is formed according to FIGS. 2 and 3. For this purpose, the cutting edge holder 10 of the device according to the invention moves linearly along the coordinates X and Z in the direction shown in FIG. 2 shown starting position. By moving the cutting edge holder 10 in the X direction according to FIG. 3, the front-side contact surface 6 is formed by means of the cutting edge 11. This second process step is followed by the second process step shown in FIGS. 4 and 5, in which the cylindrical receiving surfaces are formed. For this purpose, the cutting edge holder moves linearly into the starting position 4 shown in FIG. 4, in which the cutting edges 11 and 12 rest on the workpiece. The cylindrical receiving surface 5 is formed by moving the cutter holder in the Z direction according to FIG. 5. Both images are taken simultaneously within a movement cycle. surface 5 formed. The method steps one and two shown in FIGS. 1 to 5 can alternatively also be interchanged. In the third process step of this process section, the inner spherical bearing surface 3 is finally formed. For this purpose, the cutter holder 10 first moves into the starting position shown in FIG. 6, in which the cutters 13 and 14 rest against the workpiece. To form the spherical ring-shaped inner bearing surface 3, the cutter holder 10 now moves on a circular path 15 into the end position shown in FIG. 7. This circular movement of the cutter holder 10 forms the spherical inner bearing surface 3. Here, in the processing plane 16, the pivot point 7, around which the cutter holder 10 rotates in its circular movement, and the center point 8, the workpiece holder not shown in the figures, are congruent one above the other. After the inner bearing surface 3 has been formed, the cutter holder 10 moves back into its rest position shown in FIG. 8. In FIG. 6, arrow 20 also shows the ability of the cutter holder to move in the infeed direction, for example to compensate for cutter tolerances. While in the prior art the point of attack of the tip radius of a cutting edge is continuously changed by CNC control, which results in corresponding wear and geometry deviations, the point of application of the tip radius is always the same in the invention. Corresponding cutting edge wear can be compensated for by the additional movability of the tool holder in the machining direction 20.

After the first section of the process has been completed, the ball cage 1 machined in this way is reclamped. In this setting, the ball cage 1 is now held from the inside such that it cannot rotate, so that the spherical ring-shaped outer bearing surface 2 according to FIGS. 9 to 11 can be machined in the course of the second section of the process. To form the spherical outer bearing surface 2, the cutter holder 9 first moves from its rest position shown in FIG. 9 into the starting position shown in FIG. 10, in which the cutting edges 17 and 18 rest on the outer bearing surface 2 to be machined. In this starting position, the pivot point 7, around which the cutter holder 9 moves during its rotational movement, and the center point 8 of the workpiece are congruent with one another with respect to the processing plane 16. To train the outside ball-shaped bearing surface 2 now moves the cutter holder 9 in a circular rotary movement into the end position shown in FIG. 11. Here, the outer bearing surface 2 is formed.

Due to the fact that the blades 11 to 14 arranged on the blade holder 10 to form the inner contour and the blades 17 and 18 arranged on the blade holder 9 to form the outer contour with respect to the working plane 16 are not only translationally movable in the X and Z directions, but also If the device according to the invention enables the rotary method within the machining plane 16, the cutting edges 17 and 18 or 11 to 14 are always applied under the same pressure angle of the cutting edge to the workpiece to be machined. As a result, an optimally designed surface can be produced in compliance with the tightest tolerances. In addition, inaccuracies that occur as a result of wear of the cutting edges can be compensated for by simply readjusting the cutting tool.

Instead of the cutter holders 9 and 10 shown by way of example in the figures with the cutters 11 to 14 or 17 and 18 arranged on the cutter holder head, it is of course also possible to use differently designed cutter holders. It is only essential that the cutter holder is not only translational but also rotatable with respect to a pivot point that lies in a plane defined by the axis of rotation of the ball cage 1 to be machined, so that any point on the workpiece always has the same angular geometry of the cutting edge Workpiece can be approached. This creates the possibility of also manufacturing individual ring areas while maintaining extremely tight tolerances. The rotational mobility as well as the translational mobility relates to a relative movement between the cutting edges and the workpiece, and can therefore also be realized by moving the workpiece relative to the tool or by combined movements of the two. LIST OF REFERENCES

1 ball cage 17 cutting edge

2 outer bearing surface 18 cutting edge

3 inner bearing surface 19 axis of rotation

4 ball pocket 20 travel direction

5 receiving surface 21 travel direction

6 contact surface

7 pivot point

8 center point

9 cutter holders

10 knife holders

11 cutting edge

12 cutting edge

13 cutting edge

14 cutting edge

15 circular path

16 working plane

Claims

Patent claims

1. Apparatus, comprising a cutting holder (9, 10), which receives at least one cutting edge, for the rotary machining of ball cages intended for constant velocity joints with spherical ring-shaped inner and outer bearing surfaces (2, 3), characterized in that the cutting holder (9, 10) related to a in A fulcrum (7) lying on a working plane (16) can be rotated within the working plane (16).

2. Device according to claim 1, characterized in that the cutting edge holder (9, 10) in addition to the rotational mobility is also translationally movable in relation to a pivot point (7) lying in the working plane (16).

3. Apparatus according to claim 1 or 2, characterized in that the axis of rotation (19) of the ball cage is in the working plane (16).

4. Device according to one of claims 1 to 3, characterized in that the translational movement of the cutter holder (9, 10) in two mutually linear independent directions is possible.

5. Device according to one of the preceding claims, characterized in that for the formation of both the inner and the outer spherical bearing surfaces (2, 3) of the cutter holder (9, 10) within the processing plane (16) can be rotated.

6. Device according to one of the preceding claims, characterized in that the cutting holder (10) can be moved linearly to form the end contact surface (6) and the cylindrical receiving surface (5).

7. Device according to one of the preceding claims, characterized in that all turning operations can be carried out with one and the same turning device.

8. Device according to one of the preceding claims, characterized in that the cutter holder (9) for machining the outer spherical bearing surfaces (2) has two cutting edges (17, 18).

9. Device according to one of the preceding claims, characterized in that the cutter holder (10) for forming both the end-face contact surfaces (6) and the cylindrical receiving surfaces (5) and the inner spherical bearing surfaces (3) four cutting edges (11 - 14) having.

10. Device according to one of the preceding claims, characterized in that the cutter holder (9, 10) for compensating wear-related wear of the cutting edges is adjustable.

11. Device according to one of the preceding claims, characterized in that the cutter holder (9, 10) is continuously movable.

12. Device according to one of the preceding claims, characterized in that the cutter holder (9, 10) is automatically replaceable.