JPH0289533A - Forming method for synchronous joint - Google Patents

Abstract

PURPOSE:To improve the durability and working accuracy of a punch by extruding a rolling contact surface of a track groove and the end part in the axial direction of an undercut part regulating with a tapered sided provided on a punch and ironing the outer peripheral part. CONSTITUTION:A blank 8 is formed for an outer wheel of a synchronous joint having track grooves 12 extending in the direction of a shaft in a hollow cup shape and having undercut parts 22 in the hollow part. Accordingly, the outer peripheral shape corresponds nearly to the shape of the inner peripheral surface of the blank 8 and a preform 4 is extruded by a punch 30 having tapered sides 42, 44. The tapered sides enlarged to the opened side are formed by the tapered sides 42, 44 at the end parts of the opened sides such as rolling contact surfaces 18, etc., of the blank 8. Thus, galling at the time of releasing is prevented, load to the punch 30 is reduced and the durability is elongated. A 2nd punch having the same tapered sides as the tapered sides 42, 44 is inserted into the hollow part of the blank 8 and the outer peripheral surface of the blank 8 is formed by a die with ironing toward the axial direction. At this time, since the position of the preform to the punch is controlled by the tapered side, the accuracy for positioning can be improved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for forming a constant velocity joint which is an automobile part, and more specifically, a track having a hollow cup shape and having roller bearings disposed on its inner periphery. A molding method comprising a step of extruding a preformed outer ring of a constant velocity joint having a groove, and a sizing step of obtaining a final shaped product by squeezing the outer periphery of the preform, the method comprising a punch used for molding. The present invention relates to a method for forming a constant velocity joint that can improve the durability of the track groove and improve the shape accuracy of the track groove.

[Background of the Invention] For example, a constant velocity joint outer ring that connects a differential device and a front wheel axle in a wheel drive unit of an automobile can be produced by a cold forging process in which a first preform is formed by forging a billet;
Manufactured by an extrusion molding process of forming a second preform from the first preform using an extrusion die, and a sizing process of forming a finished product with final finished dimensions from the second preform. has been done.

First, the cold forging process, which is the first process, will be explained based on FIG. In this process, a cylindrical billet) 2a
After forging the billet 2b into a billet 2C, a first preformed body 4 having an upsetting portion 4a at the end thereof is formed.
form. Next, in a second extrusion molding step, the upsetting portion 4a is molded into a cup shape by an extrusion punch 6 shown in FIG. 2 to form a blank 8, which is a second preform.

Here, the blank 8 formed by the extrusion punch 6 is a preformed outer ring of a constant velocity joint that has already been proposed by the applicant (see Japanese Patent Application No. 62-25098). That is, as shown in FIG. 3, the blank 8 that is the second preform has a cup shape in which the driven shaft 10 is integrally formed at one end and is open at the other end. Inside, there are three track grooves 12a to 12c extending in the axial direction and receiving trunnions (not shown), and three convex portions 14a projecting into the hollow part of the blank 8 between each track groove 12a to 100. to 1
4C is formed.

Each track groove 12a to 12C has a ceiling surface 16a to 16
C, and a transfer surface 1 on both sides of the ceiling surfaces 16a to 16C, on which slide rollers constituting a trunnion are transferred.
8a to 18f. Furthermore, the spaces between the transfer surfaces 18a to 18f and the convex portions 14a to 14c bulge into the hollow portions to become protrusions 20a to 2Of, respectively, and these protrusions 20a to 2Of and the transfer surfaces tea to 18f
Undercut portions 22a to 22f are formed between them, respectively, for regulating the lateral movement range of the slide rollers transferring on the transfer surfaces 18a to 18f and improving the performance of the constant velocity joint.

On the other hand, the extrusion punch 6 for forming the blank 8 has an outer circumferential shape corresponding to the inner circumferential shape of the blank 8, and the extrusion punch 6 has an outer circumferential shape that corresponds to the inner circumferential shape of the blank 8. A land portion 24 is provided around the entire circumference to facilitate release from the mold (see FIG. 2).

By the way, the blank 8 formed in this way has
As described above, the undercut portions 22a to 22f are formed to improve the performance of the constant velocity joint. Therefore, the protruding parts 20a to 2Of adjacent to the undercut parts 22a to 22f have a thin wall shape with relatively low rigidity. Therefore, during extrusion molding, the undercut portions 22a to 22f tend to be formed to be inclined toward the pressing die 26 side (see FIG. 2). Note that this tendency increases as the length of the blank 8 formed by the extrusion punch 6 in the axial direction increases.

As a result, during extrusion molding, a situation occurs in which the undercut portions 22a to 22f in the vicinity of the opening of the blank 8 come into contact with the extrusion punch 6, which causes galling between the extrusion punch 6 and the blank 8. occurs. In this case, not only is it difficult to release the extrusion punch 6 and the blank 8 from the mold, but also the land portion 24 of the extrusion punch 6 is
Therefore, there is a possibility that the vicinity of the opening of the blank 8 may be damaged.

Therefore, the present applicant proposed in Utility Application No. 63-69980 to solve the above-mentioned inconvenience by providing a tapered surface at the corresponding portion of the extrusion punch 6 for forming the undercuts 122a to 22f of the blank 8. . Subsequent research revealed that in the blank 8, galling between the extrusion punch 6 and the transfer surfaces 18a to 18f on both sides of the track grooves 12a to 12C cannot be ignored.

In addition, in the sizing process following such an extrusion process, the present applicant similarly provided the ironing punch with a tapered surface to prevent galling between the blank 8 and the ironing punch and improve the mold release property. A sizing method is proposed in Japanese Patent Application No. 63-129958.

In this case, it became necessary to balance mold releasability and processing accuracy.

[Object of the invention] The present invention was made in connection with the above application, and
Extrusion molding is performed using an extrusion punch having a tapered surface that comes into contact with the transfer surface of the track groove of the blank and the axial end of the undercut portion, and then the blank is regulated with an ironing punch having a tapered surface that is the same as the tapered surface. To provide a method for forming a constant velocity joint that can improve the durability of a punch by ironing and particularly improve the machining accuracy of a transfer part of a track groove.

[Means for Achieving the Object] In order to achieve the above-mentioned object, the present invention provides a constant-velocity pump having a hollow cup shape and having a track groove extending in the axial direction and an undercut portion in a portion bulging into the hollow portion. A method for forming an outer ring of a joint, the method comprising: inserting a first punch that regulates the side surface of the track groove along the undercut portion and the axial end portion of the undercut portion with a tapered surface, and performing extrusion processing. A first step of molding a preform, and controlling the undercut portion of the inner circumferential surface of the preform and the axial end of the side surface of the track groove with a second punch, while shaping the outer circumferential surface of the preform using a die. and a second step of applying ironing forming in the axial direction.

[Embodiments] Next, preferred embodiments of the method for forming a constant velocity joint according to the present invention will be described in detail with reference to the accompanying drawings.

First, an extrusion bunch for carrying out the extrusion process in the molding method according to the present invention will be explained based on FIG. 4.

In this case, the object of extrusion molding is the first one shown in Figure 1.
The preformed body 4 is used to form a blank 8, which is a second preformed body of the outer ring constituting the constant velocity joint shown in FIG. 3, from the first preformed body 4.

Therefore, in FIG. 4, the extrusion bunch 30 is formed so that its outer peripheral shape substantially corresponds to the inner peripheral surface shape of the blank 8.

That is, the three track grooves 12a to 1 of the blank 8
The part corresponding to 2c has three prismatic sections 32a to 32c.
are formed to bulge, and long grooves 34a to 34C corresponding to the convex portions 14a to 14c of the blank 8 are formed between the polygonal column parts 32a to 32a, respectively.

The prismatic portions 32a to 32c are track grooves 12a to 12c.
plane parts 36a to 36c forming the ceiling surfaces 16a to 16c; side parts 38a to 3 on both sides of the plane parts 36a to 36c forming transfer surfaces 18a to 18f;
8f, the long grooves 34a to 34C, and each side surface portion 38a.
The undercut portions 22a to 22a are located between the undercut portions 22a to 38f.
2f. Step portions 41a to 41f1, first tapered surfaces 42a to 42f, and relief portions 43a to 43f are connected to each jaw-shaped portion 40a to 40f from the base end side. Moreover, in the side parts 38a to 38f, the first part of the jaw-shaped parts 40a to 40f is
Second tapered surfaces 44a to 44'' are formed at the same height positions as the tapered surfaces 42a to 42f.
Relief surfaces 46a to 46f are continuous via 4a to 44f.

Note that there is a land on the tip end on the first preformed body 4 side. 4g is formed. The land portion 48 is formed so as to go around the entire circumference of the extrusion bunch 30.

Next, a sizing device used in a sizing step, which is the next step of the extrusion process using the extrusion bunch 30 as described above, will be explained.

Therefore, in FIG. 5, the sizing device 50 is
The first mold 5 includes a mold 52 and a second mold 54.
2 and the second mold 54 are relatively movable in directions toward and away from each other under the driving action of an actuator (not shown), as indicated by arrows in the figure. First mold 5
A punch 56 is attached to the upper surface of 2. The punch 5
Reference numeral 6 has an outer shape that corresponds to the inner peripheral shape of the outer ring of the constant velocity joint, and has three prismatic portions 58a to 58C corresponding to the three track grooves 12a to 12C of the blank 8, respectively. is formed to bulge, and a convex portion 14 of the blank 8 is formed between these prismatic portions 58a to 58C.
Long grooves 60a to 60c corresponding to a to 14C are formed, respectively.

Here, the prismatic portions 58a to 58c are flat portions 62a to 62c that finish the ceiling surfaces 16a to 16c of the track grooves 12a to 12c, and are located on both sides of the flat portions 62a to 62C to finish the transfer surfaces 18a to 18f. and jaw-like portions 66a to 66f that are located between the long grooves 60a to 60c and the respective side portions 64a to 64f and finish the undercut portions 22a to 22f. In this case, the large portions 66a to 66f
are formed with first tapered surfaces 68a to 68f, respectively, which contact the undercut portions 22a to 22f near the open end of the blank 8 when the punch 56 is inserted into the hollow portion of the blank 8.

Further, the jaw portions 66 are provided on each of the side surfaces 64a to 64f.
First tapered surfaces 68a to 68f formed at a to 66f
Second tapered surfaces 70a to 70f are formed at the same height position. Incidentally, the inclination angles of the first tapered surfaces 68a to 68f and the second tapered surfaces 70a to 70f are the same as the first tapered surfaces 42a to 42f and the side surface portion 38a of the jaw-shaped portions 40a to 40f of the extrusion punch 30 shown in FIG. ~38f
This is the same as the second tapered surfaces 44a to 44f.

Next, in contrast to the first mold 52 and punch 56, the second mold 54 has a substantially cylindrical shape, and the diamond 2 is attached to the lower end thereof. As shown in FIG. 7, the diamond 2 has a substantially ring shape, and a circular bulging portion 76 having a tapered portion 74 on the punch 56 side is formed on the inner periphery thereof.

The apparatus for carrying out the method of forming a constant velocity joint according to the present invention is basically configured as described above. Next, such an apparatus is used to form the final shape of a constant velocity joint. The process to do this will be explained.

First, as shown in FIG. 4, extrusion processing is performed on the first preform 4 that has been formed into a predetermined shape by forging. That is, the land portion 48 side of the extrusion punch 30 is brought into contact with the upsetting portion 4a of the first preform 4, and the extrusion punch 3
0 in the direction of the arrow shown in FIG. 4 to start the extrusion molding process. The land portion 48 of the extrusion punch 30 is the first
A hollow portion is gradually defined in the preformed body 4, and finally a blank 8, which is a second preformed body, having a hollow portion having a shape corresponding to the outer peripheral shape of the land portion 48 is formed.

Here, the extrusion punch 30 is inserted into the upsetting portion 4 of the first preform 4.
When the blank 8 is formed by pushing the punch into the
The tapered surfaces 42a to 42f and the second tapered surfaces 44a to 44f of the side surfaces 38a to 38f press the vicinity of the opening of the blank 8. As a result, in particular, the rolling surfaces 18a to 18f of the blank 8 are formed with tapered surfaces that widen toward the opening side. Therefore, since the opening side end portions of the transfer surfaces 18a to 18f widen widely in the direction in which the extrusion punch 30 is pulled out, the blank 8 does not bite against the extrusion punch 30 during demolding, and smooth demolding is possible. Work can be carried out (see Figure 6).

Moreover, the load placed on the extrusion punch 30 during demolding is reduced, and its useful life can be extended.

Next, the blank 8 that has been extruded in this way is subjected to a sizing process by squeezing the outer periphery, and the blank 8 is
is formed into the final shape of the outer ring of the constant velocity joint.

Therefore, as shown in FIG. 5, a punch 56 fixed to the upper surface of the first mold 52 is inserted into the hollow part of the blank 8. At this time, there is a predetermined gap between the inner circumferential surface of the blank 8 and the long grooves 60a to 60C1 of the punch 56 corresponding to each part of the inner circumferential surface; A clearance is defined.

Next, the diamond 2 mounted on the second mold 54 is punched 56
The outer periphery of the blank 8 is subjected to ironing. At this time, the bulge 76 formed on the inner circumference of the diamond 2 extends the outer circumference of the blank 8 toward the first mold 52, and the inner circumference of the blank 8 is expanded by the punch 5.
It has the effect of following the outer peripheral surface of 6.

In fact, as the diamond 2 is displaced toward the punch 56, the outer circumferential portion of the blank 8 is extended toward the first mold 52 by the tapered portion 74 of the diamond 2, while on the inner circumferential surface of the blank 8, The ends of the transfer surfaces 18a to 18f along the undercut portions 22a to 22f are connected to the driven shaft 10 of the blank 8 by the second tapered surfaces 70a to 70f of the punch 56.
This leads to being pushed to the side. Similarly, undercut portion 22
The ends of a to 22f are pressed against the first tapered surfaces 68a to 68f.

Then, when the sizing is completed, transfer surface 1
8a to 18f and undercut portions 22a to 22f
The outer ring is suitably in close contact with the punch 56 without any clearance, and an outer ring having a highly accurate shape of the inner circumferential surface is obtained.

That is, in the extrusion process, a tapered surface is formed on the opening side of the blank 8, and each tapered surface of the punch 56 is located at a symmetrical position with respect to the axis of the punch 56 and has the same slope as the tapered surface on the blank 8 side. Blank 8 by
Since the undercuts 22a to 22f and the track grooves 12a to 12c are centered near the opening, there is no possibility that the undercuts 22a to 22f and the track grooves 12a to 12c are inclined toward the punch 56 side. Therefore, in particular, the undercut portions 22a to 22f
The transfer surfaces 18a to 18f formed along the axial direction of the blank 8 are formed with extremely high precision (see FIG. 7).

[Effects of the Invention] As described above, according to the present invention, when finishing a preformed outer ring of a constant velocity joint having an undercut portion extending in the axial direction in the hollow portion, the undercut portion Extrusion processing and ironing of the outer periphery are performed by regulating the axial ends of the transfer surface of the trunk groove and the trunk groove by a tapered surface formed on the punch. In this case, during extrusion processing, the tapered surface facilitates release of the extrusion punch and reduces the load acting on the extrusion punch, making it possible to improve its durability. Moreover, in particular, since the position of the preform relative to the punch during ironing is controlled by the tapered surface, positioning accuracy is improved and a product with good layer processing accuracy can be obtained.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of drawings]

Figures 1 a to d are explanatory diagrams of the casting process for forming the first preform from a billet, Figure 2 is an explanatory diagram of extrusion molding according to the prior art, and Figures 3 a and b are the outer ring of the constant velocity joint. A partially omitted longitudinal section and a cross-sectional view showing the structure of the blank; FIG. 4 is a perspective view of the structure of an extrusion punch used in the molding method according to the present invention and a preform formed by the punch; FIG. A partially omitted perspective explanatory view of the sizing device used in the molding method, FIG. 6 is an explanatory view of extrusion molding of the extrusion punch in FIG. 4, and FIG. 7 is an explanatory view of ironing molding of the sizing device in FIG. 5. 8...Blank 12a-12f...Track groove 22a-22f...Undercut portion 30...Extrusion punch 32a-32c...
Square column parts 42 a to 42 c, 44 a to 44 f-
... Tapered surface 50 ... Sizing device 52.54
...Molds 68a to 68f, 70a to 70f-
Taber surface (b)

Claims (2)

[Claims] (1) A method for forming an outer ring of a constant velocity joint having a hollow cup-shaped track groove extending in the axial direction and an undercut portion in a portion that bulges into the hollow portion, the method comprising forming a track groove along the undercut portion. a first step of forming a preform by inserting a first punch that restricts the side surfaces of the groove and the axial end of the undercut portion with a tapered surface and applying extrusion processing; A second step of controlling the undercut portion of the circumferential surface and the axial end portion of the side surface of the track groove with a second punch, and applying ironing to the outer circumferential surface using a die in the axial direction. A method for forming a constant velocity joint characterized by: (2) In the method according to claim 1, the first punch and the second punch have tapered surfaces having the same inclination angle at a portion corresponding to the undercut portion of the preform and the axial end portion of the side surface of the track groove. A method for forming a constant velocity joint, which is characterized by: