EP1165272B1 - Method of producing homokinetic joints - Google Patents

Abstract

The invention relates to a method of manufacturing the outer part of a constant velocity joint, the outer part having in the finished condition a hollow chamber with a cylinder-shaped inner wall, in which there are provided ball raceways (1c) which run obliquely of the cylinder axis and are inclined with respect to one another. First, a wobble press die (4) is axially introduced into a goblet-shaped preliminary workpiece (1a) for the outer part having a conically developing inner and outer wall and pre-formed ball raceways (1c) in the inner wall. The preliminary workpiece (1a) is pressed (drawing process) by means of the wobble press die (4), sitting on the floor of the hollow chamber, through an opening in an outer die (2), so that a drawing process is carried out in which the preliminary workpiece (1a) is so cold formed that the inner wall of the hollow chamber is given a cylindrical shape. Thereafter the outer die (2) and the wobble press die (4), having a truncated cone-shaped outer contour, and having elevations (4a) on its outer side corresponding to the ball raceways (1c) and having a lesser diameter than the cylindrical hollow chamber of the drawn preliminary workpiece (1a), are set into a wobbling circular movement relative to one another such that the elevations (4a) of the wobble press die (4) move over the pre-formed ball raceways (1c) on the inner wall of the hollow chamber in a pressing and material shaping manner. Thereafter the wobble press die (4) is axially drawn out of the preliminary workpiece (1a) and finally, the finished joint outer part is ejected from the outer die (2).

Description

The present invention relates to a method for producing outer parts of Cross groove constant velocity joints according to the preamble of claim 1.

With constant velocity joints of this type, e.g. in the publication "Universal Joint and Driveshaft Design Manual, Advances in Engineering Series No. 7 "of the Society of Automotive Engineers, Inc., the outer part has a cylindrical shape Inner contour, in which elongated recesses are made. they form Ball raceways for the balls arranged in a cage of the inner part. The cylindrical inner contour of the outer joint part naturally has none Undercut on. Nevertheless, there is a separation of the outer part and the inner part of the Constant velocity joint not easily possible, since the ball raceways are not axially parallel and also inclined to each other.

A method for producing outer joint parts of the type just described is in of patent EP 0 270 538. A pre-workpiece has the shape a goblet diverging towards the open end, with the inside of the Ball races are already preformed. By pressing the Prework in a cylindrical opening of an outer tool, that is Pre-workpiece deformed so that it finally has a cylindrical inner contour having. The required force is exerted by a press ram, which is made of a plurality of mutually movable segments is formed. These point mutually inclined elevations. In one located in the press ram Cavity, an expanding body is axially inserted before pressing the pre-workpiece, which keeps the segments in their operating position. When pulling in and deforming the The workpiece elevations exert pressure on the inside of the workpiece Vorwerkstück out and cold-deform on the inclined against each other Ball raceways.

To remove the press ram from the joint outer part machined in this way, first the expansion body is removed from the press ram. As a result, the segments pivot in the direction of the central axis of the entire arrangement and thus disengaged with the ball tracks. In a second step, the segments can also be made be removed from the finished workpiece.

Another method for producing outer parts of constant velocity joints is from the German patent DE 196 37 839 known, which, however, on the Limited production of so-called Rzeppa constant velocity joints. In contrast to the Cross groove outer joint parts run the ball raceways with this type of joint in the axial direction. An axial separation of the outer and inner part of the Constant velocity joint is prevented here by either the ball raceways and / or the cage guide surface has an axial undercut. With this known methods, the pre-workpiece is also carried out in one operation Subjected to cold working. This is done differently by a segment convex curved wobble die, which is first in the cavity of the in one Outside tool stored and fixed pre-workpiece is immersed. by virtue of the wobble press stamp indicates the different curvatures of the segments Its surface has rib-shaped contours that are used to machine the Ball raceways are used.

The wobble press die is then set in a wobble movement, wherein it is in several circular revolutions over the surfaces to be deformed Prework is rolled. The wobble point of this movement is close below the underside of the pre-workpiece. During the wobble press each deformed only a small area of the ball raceways to be deformed. are When the pre-workpiece reaches the desired deformations, the The wobble process ended and the wobble stamp removed. It is advantageous for this known method that a one-part wobble stamp can be used can, which is cheaper to produce than a multi-part segment stamp and a ensures greater precision in the production of outer joint parts.

The invention has for its object that for the production of Rzeppa constant velocity joints well-known wobble process with one-piece wobble stamp also to be used for the production of cross groove constant velocity joints.

The object is achieved with the method specified in claim 1, namely under Application of a wobble stamp with the features according to claim 6. The wobble punch according to the invention has - in a perpendicular to its axis directional projection - rectilinear projection edges and is particularly simple and inexpensive to manufacture.

According to the invention, the outer tool and the one frustoconical Outer contour wobble stamp, which on the outside Ball raceways has corresponding surveys and a lower one Diameter than the cylindrical cavity of the drawn-in workpiece, relative to each other in a wobbling circular motion with one above the bottom of the Cavity arranged wobble point, such that the elevations of the Wobble press stamping and molding over the preformed Move ball raceways on the inner wall of the cavity. Then you can the wobble punch axially pulled out of the pre-workpiece and finally that finished outer joint part are ejected from the outer tool.

Fig. 1 die Anordnungen des Vorwerkstückes, des Außenwerkzeuges und des Taumelpreßstempels zu Beginn eines Verfahrens zur Herstellung des Außenteiles eines Cross Groove-Gelenkes;

Fig. 2a das Einziehen des Vorwerkstückes in das Außenwerkzeug;

Fig. 2b im Schnitt die Anordnung des Taumelpreßstempels in dem Vorwerkstück während des Einziehens;

Fig. 3a die Umformung des Vorwerkstückes durch den Taumelpreßstempel;

Fig. 3b im Schnitt die Anordnung des Taumelpreßstempels in dem Vorwerkstück während des Taumelpressens;

Fig. 4 ein fertiges Cross Groove-Gelenkaußenteil in Aufsicht.

The invention is explained in more detail below with reference to the figures in the accompanying drawing. Show it:

Figure 1 shows the arrangements of the pre-workpiece, the outer tool and the wobble die at the beginning of a method for manufacturing the outer part of a cross groove joint.

2a the drawing of the pre-workpiece into the external tool;

2b shows in section the arrangement of the wobble punch in the preliminary workpiece during the drawing in;

3a shows the shaping of the pre-workpiece by the wobble die;

3b shows in section the arrangement of the wobble punch in the pre-workpiece during the wobble pressing;

Fig. 4 is a finished cross groove outer joint part in supervision.

An embodiment of the method is first of all based on FIGS. 1 to 3b explained.

The pre-workpiece 1, the upper part 1a at the beginning of the shape of an open end has diverging goblets in a first step, which is shown in FIG is shown in a funnel-shaped opening 2a of the External tool 2 of a wobble press arranged centrally to the machine axis. On The ball raceways 1c are already preformed on the inner wall of the upper part 1a. In the lower area, the preliminary workpiece 1 has one piece in the axial direction extending pin 1b. To stabilize this pin 1b from one in axially displaceable jacket 3 enclosed, on the upper edge of which cup-shaped upper part 1a of the workpiece 1 rests. To twist the Avoid pre-workpiece 1 during the subsequent wobble process the pin 1b has a toothing, not shown, on its surface have, which engages in a corresponding toothing of the jacket 3. Would be conceivable but also that the pin 1b seen in cross section has a non-circular shape.

A wobble punch 4 is then centered on the bottom of the upper part 1a attached to the machine axis. This wobble punch 4 is in its lower Area designed in the shape of a truncated cone, with the outside being integral with the Ball raceways 1c corresponding line-like elevations 4a are arranged, which in Longitudinal direction with respect to the truncated cone axis of the wobble punch 4 are inclined.

The funnel-shaped section 2a of the outer tool 2 is by a cylindrical second section 2b continued, the shape of the outer contour of the finished top part 1a of the outer joint part corresponds. By exercising one Axial pressure on the wobble 4, the workpiece 1 is down pressed, the cup-shaped upper part 1a from the funnel-shaped section 2a in the cylindrical section 2b of the outer tool 2 is drawn in and the Pin 1b and the jacket 3 surrounding it can be pushed further down. The side walls of the upper part 1a so that they are at the end of Retraction run parallel to the machine axis and the inner wall of the The cavity of the upper part 1a thus becomes cylindrical, as can be seen in FIG. 2a can be. The shape of the wobble punch 4 including its elevations 4a is chosen so that it does not touch the side walls of the upper part 1a. His The arrangement in the pre-workpiece 1 during the drawing is in section in Fig. 2b shown.

Then the wobble punch 4 and the preliminary workpiece 1 are relative set in a wobbling circular motion with each other, the wobble angle α, i.e. the angle between the machine axis and the axis of the wobble punch 4, is adjustable. If the wobble angle α is greater than 0 °, the two axes intersect at the wobble point 5, which in the example shown is above the external tool 2 located. The wobble die 4 rolls with its outer contour on the cylindrical inner wall of the cavity. He is trained so that the Upper part 1a of the pre-workpiece 1 and the corresponding outside Elevation 4a parallel to the machine axis and to those already erected Side walls of the upper part 1a run. This is chosen by the Truncated cone shape achieved taking into account the parameters of the wobble movement. The relative arrangement between the side walls of the upper part 1a, the Wobble press die 4 and the elevations 4a is a side view in Fig. 3a and in Section shown in Fig. 3b.

With the embodiment just described it is achieved that the wobble press punch 4th during the thawing of the pre-workpiece 1 always over the entire height of the Side wall of the upper part 1a processed. This allows an extremely precise as well also a very effective machining, so that with this method a close contour Shape on the inside of the cup-shaped top 1a can be achieved by pulling in and pressing alone would not be achievable. In particular, do not apply machining post-processing of the pre-workpiece 1, thereby reducing the time required the production and also the manufacturing costs of an outer joint part clearly be reduced.

After the wobble machining process has ended, the wobble die 4 is turned off pulled out the finished workpiece 1. As when pulling in the Prework 1 is the wobble die 4 parallel to the machine axis aligned, i.e. α is equal to 0 °. Accordingly, in the design of the Wobble stamp 4 are taken into account that including its outer contour that located on the surface of the frustoconical section line-like elevations 4a, not a larger diameter than the cavity of the may have finished joint outer part.

Finally, the jacket 3 is pushed up again, so that the finished Workpiece 1 simply out of the funnel-shaped opening 2a of the external tool 2 can be removed or ejected. The outer part produced in this way of a cross groove joint is shown in a top view in FIG. 4.

The shape of the wobble punch proposed here is particularly noteworthy characterized in that the greatest possible contact between the wobble die and the workpiece is reached, with which a very effective machining of the workpiece is achieved is made possible. Furthermore, a wobble stamp of this shape is not only less expensive and easier, but also with lower fault tolerances than that from the manufacturing process for external parts of a Rzeppa constant velocity joint to produce known segment or spread stamps.

It should also be noted that in the method described above different types of wobble presses can be used. The The most common wobble presses are divided into several according to their tool movements Classify types.

In the type 1 wobble press, the outer tool 2 guides with the one inserted therein Workpiece 1 a driven rotational movement around the machine axis. The The wobble punch 4 rotates synchronously with the rotational movement of the outer tool 2 around the wobble axis inclined by the wobble angle α. A Translational movement, the lifting movement during the forming process corresponds, is also introduced hydraulically by the wobble ram 4. This Translation movement is carried out to the wobble punch 4 to each To hold the time at a suitable height in relation to the workpiece 1. Is the Rotational movement of the wobble punch 4 is not driven, i.e. this turns freely with the workpiece 1 about the wobble axis, one speaks of the Swash press type 1A. In contrast, the rotational movement of the wobble punch 4 additionally driven, this is the name of this type 1B wobble press.

The type 2 wobble press has a fixed outer tool 2 that neither Can still perform translational or rotational movements. The workpiece 1 is during of the entire machining process stationary. The wobble punch 4 leads for it a total of three movements, one rotation around the wobble axis, one Wobble around the machine axis, as well as a hydraulically driven Stroke movement in the axial direction.

Type 3 wobble presses, on the other hand, are the most common type of wobble presses. Here the hydraulically driven lifting movement takes place through a cylinder in the lower one Part of the machine. The translational movement is thus through the external tool executed. The wobble movement is initiated by the wobble die 4, External tool 2 and workpiece 1 remain with respect to the rotational movement stationary.

Regardless of the type of wobble press used, however, it does The inventive method only that the outer tool 2 relative to the Wobble punch 4 performs a wobbling circular movement. Like the individual Movement components of the wobble movement on the different tool parts of the the respective wobble press used is fundamental irrelevant.

Claims (6)

1. Method of manufacturing an outer part of a constant velocity joint, the outer part having in the finished condition a hollow chamber with a cylindrical inner wall, in which there are provided ball raceways (1c), which run obliquely to the cylinder axis and are inclined with respect to one another, having the following method steps:

   a) a wobble press die (4) is axially introduced into a goblet-shaped preliminary workpiece (1a) for the outer part having a conically developing inner and outer wall and pre-formed ball raceways (1c) in the inner wall,

   b) the preliminary workpiece (1a) is pressed by means of the wobble press die (4), against a bottom of the hollow chamber, through an opening in an outer die (2), so that a drawing process is carried out in which the preliminary workpiece (1a) is so cold-formed that the inner wall of the hollow chamber is given a cylindrical shape, characterized by the following method steps:

   c) the outer die (2) and the wobble press die (4), having a truncated cone-shaped outer contour, and having elevations (4a) on its outer side corresponding to the ball raceways (1c) and having a lesser diameter than the cylindrical hollow chamber of the drawn preliminary workpiece (1a), are, with a wobbling movement of the wobble press die (4) around a wobble point (5) arranged above the floor of the hollow chamber, set into a wobbling circular movement relative to one another such that the elevations (4a) of the wobble press die (4) move over the pre-formed ball raceways (1c) on the inner wall of the hollow chamber in a pressing and material shaping manner,

   d) thereafter the wobble press die (4) is axially drawn out of the preliminary workpiece (1a) and

   e) finally, the finished joint outer part is ejected from the outer die (2).
2. Method according to Claim 1, characterized in that, in step c) the outer die (2), with the workpiece (1) placed therein, carries out a driven rotational movement around a machine axis and the wobble press die (4) rotates therewith around a wobble axis inclined by a wobble angle α, synchronously with the rotational movement of the outer die (2).
3. Method according to Claim 2, characterized in that the rotational movement of the wobble press die (4) is additionally driven.
4. Method according to Claim 1, characterized in that, in step c) the outer die (2) is stationary and the wobble press die (4) simultaneously carries out a rotation around the wobble axis, a wobble movement around the machine axis and a stroke movement in axial direction.
5. Method according to Claim 1, characterized in that, in step c) the outer die (2) carries out a stroke movement in axial direction and the wobble press die (4) simultaneously carries out a rotation around the wobble axis and a wobble movement around the machine axis.
6. A wobble press die (4) for the manufacture of the outer part for a constant velocity joint, which has a hollow chamber having a cylindrical inner wall in which there are provided ball raceways (1c) running obliquely to the cylinder axis and inclined with respect to one another, characterized in that it has a truncated cone-shaped outer contour with line-like elevations (4a) arranged thereon, which elevations run obliquely to the truncated cone axis and are inclined with respect to one another, the truncated cone-shaped outer contour and the line-like elevations (4a) arranged thereon are so formed with reference to a wobble point (5), which is located spaced from a thickened end of an outer contour of the wobble press die (4) on a middle axis thereof, that during the wobbling they run parallel to the cylindrical inner wall of the hollow chamber while rolling on the cylindrical inner wall of the hollow space.

Images