JPH0698433B2 - Sizing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sizing method, and more particularly, to a sizing method of an automobile having a hollow cup shape and an inner periphery having a track groove for rolling a roller bearing. When sizing the outer ring of the constant velocity joint in the cold working process, the axial end of the undercut portion formed along the track groove in the hollow portion of the preformed cup-shaped material is restricted by the tapered surface. The present invention relates to a sizing method capable of finishing the track groove with high accuracy by squeezing the outer peripheral portion of the material with a die while inserting a punch.

BACKGROUND OF THE INVENTION Conventionally, a cold working method for making an article processed by forging, casting or the like into a final finished dimension is called sizing. For example, in a wheel drive unit of an automobile, the sizing method is adopted in a manufacturing process of an outer ring of a constant velocity joint that connects a differential device and a front wheel shaft.

Therefore, the outer ring structure of the constant velocity joint submitted by the applicant based on FIGS. 1 and 2 (Japanese Patent Application No. 62-250).
No. 98) and its sizing process will be briefly described.

First, the billet is forged to form a blank 2 which is a preform having the shape shown in FIGS. 1A and 1B.
In this case, the blank 2 has a cup shape in which the driven shaft 4 is integrally formed at one end and the end is open,
Inside the blank 2, there are three recesses extending parallel to the axial direction and receiving trunnions (not shown).
6a to 6c and three convex portions 8a to 8c projecting into the hollow portion of the blank 2 are formed between the concave portions 6a to 6c. Each of the recessed portions 6a to 6c has ceiling surfaces 10a to 10c and track grooves 12a to 12f on both sides of the ceiling surfaces 10a to 10c for rolling the slide rollers constituting the trunnion. Further, the track grooves 12a to 12f and the convex portion 8a
8a to 8c are bulged in the hollow portion to project the protrusions 14a.
To 14f between the protrusions 14a to 14f and the track grooves 12a to 12f, the lateral movement range of the slide roller rolling in the track grooves 12a to 12f is restricted to improve the performance of the constant velocity joint. Undercut part 16a for making
To 16f are formed respectively.

Next, in the blank 2 configured as described above, the punch 18 corresponding to the finished shape of the outer ring is inserted into the hollow portion, and in this state the outer peripheral portion is squeezed by the die 20 (Fig. 2a).
And b)). As a result, the inner peripheral surface of the blank 2 is sized according to the outer peripheral shape of the punch 18.

By the way, the blank 2 sized in this way
Among them, the track grooves 12a to 12f need to be formed with considerable accuracy in order to improve the performance of the constant velocity joint, as described above. Therefore, in the sizing step, the track grooves 12a to 12f must be finished so as to have high dimensional accuracy and rigidity.

However, since the undercut portions 16a to 16f are formed along the track grooves 12a to 12f in the blank 2,
It is extremely difficult to maintain the dimensions of the track grooves 12a to 12f with high accuracy. That is, in the state before sizing, a predetermined clearance δ is provided between the inner peripheral surface of the blank 2 and the outer peripheral surface of the punch 18 (Fig. 2a), and the protrusion occurs during sizing shown in Fig. 2b. Part 14a
To 14f and the track grooves 12a to 12f, it is extremely difficult to effectively wrap the material forming the blank 2 around the undercut portions 16a to 16f. Therefore, when sizing is performed in this manner, there arises a problem that the dimensional accuracy of the undercut portions 16a to 16f cannot be sufficiently obtained.

Further, the undercut portions 16a to 16f have the clearance δ
Due to the presence of the above, the sizing tends to be formed toward the punch 18 side (see FIG. 2B). This tendency occurs not only at the time of sizing but also at the time of forming the blank 2 by forging, and the longer the axial length of the blank 2, the greater the tendency. As a result, there arises a disadvantage that sufficient accuracy cannot be obtained for the track grooves 12a to 12f in the vicinity of the opening 2a of the blank 2. Moreover, since the undercut portions 16a to 16f are formed to be inclined toward the punch 18 in the vicinity of the opening 2a, galling occurs at this portion, which not only makes it difficult to release the mold, but also is formed at the time of release. The outer ring or punch 18 may be defective.

[Object of the Invention] The present invention has been made to overcome the above-mentioned inconvenience, and has a cup shape like an outer ring which is a component of a constant velocity joint, and has an undercut portion in its hollow portion. In squeezing the formed article into a final shape, a punch for regulating the axial end of the undercut portion with a tapered surface is inserted into the article, and the outer peripheral portion of the punch is inserted into the axial end. By directionally ironing and forming, it is possible to improve the dimensional accuracy when processing the groove along the undercut portion, and it is possible to obtain a good product with no defects and to use punches or the like. An object of the present invention is to provide a sizing method capable of improving the durability of a sizing device.

[Means for Achieving the Object] In order to achieve the above-mentioned object, the present invention uses a die and a punch for a preform having an undercut portion in a portion that bulges into a hollow portion. A sizing method in which molding is performed to obtain a predetermined dimensional accuracy, wherein a punch for restricting an axial end of the undercut portion with a tapered surface is inserted into a hollow portion of the preform, and then an outer periphery of the preform is obtained. It is characterized in that the part is ironed by using a die so as to be directed to the end in the axial direction.

Further, according to the present invention, the undercut portion is formed symmetrically with respect to the axial direction, and the axial end portions of the respective undercut portions are sandwiched by two tapered surfaces provided symmetrically with respect to the axial direction of the punch. Is characterized by.

[Embodiment] Next, a preferred embodiment of the sizing method according to the present invention will be described in detail below with reference to the accompanying drawings.

First, a sizing apparatus for carrying out the sizing method according to the present invention will be described with reference to FIG. In this case, the sizing target is the blank 2 which is a preformed body of the outer ring used in the constant velocity joint shown in FIG.

Therefore, in FIG. 3, the sizing device 30 includes a first mold 32 and a second mold 34, and the first mold 32 and the second mold 34 are as indicated by arrows in the drawing. , Are relatively displaceable in the direction of approaching and separating from each other under the driving action of an actuator (not shown). The punch 36 is attached to the upper surface of the first die 32. The punch 36 is formed such that its outer shape corresponds to the inner shape of the outer ring of the constant velocity joint, and has three prismatic portions 40a to 40c corresponding to the three concave portions 6a to 6c of the blank 2, respectively. 40c is bulged, and long grooves 42a to 42c corresponding to the convex portions 8a to 8c of the blank 2 are formed between the prismatic portions 40a to 40c, respectively.

Here, the prismatic portions 40a to 40c are the ceiling surfaces 10 of the concave portions 6a to 6c.
a to 10c for finishing the flat portions 44a to 44c, side portions 46a to 46f for finishing the track grooves 12a to 12f on both side portions of the flat portions 44a to 44c, and the long grooves 42a to 42c and the aforementioned each Undercut portion between the side portions 46a to 46f
Jaws 48a to 48f for finishing 16a to 16f.
In this case, when the punch 36 is substantially completely fitted in the hollow portion of the blank 2 in each of the jaw portions 48a to 48f, the taper is formed so as to be pressed against the undercut portions 16a to 16f in the vicinity of the opening 2a of the blank 2. Surfaces 50a to 50f are formed respectively (see FIG. 4). The facing tapered surface 50a is 50f, and the tapered surface 50a
b is provided to face 50c, and tapered surface 50d is provided to face 50e.

In contrast to the first die 32 and punch 36 configured as described above, the second die 34 has a substantially cylindrical shape, and the die 52 is attached to the lower end portion thereof. As shown in FIG. 5, the die
52 has a substantially ring shape, and a bulged portion 56 having a tapered portion 54 is provided on the side periphery thereof.

The apparatus for carrying out the sizing method according to the present invention is basically constructed as described above. Next, the blank 2 is sized by using the sizing apparatus 30, and the blank 2 is finally sized. The case of forming the outer ring shape of a constant velocity joint will be described.

First, as shown in FIG. 5a, the first die is inserted into the hollow portion of the blank 2 which is a preform formed by forging.
The punch 36 fixed on the upper surface of 32 is inserted. At this time,
The inner surface of the blank 2 and the long grooves 42a to 42c of the punch 36 corresponding to the respective parts of the inner surface, the flat surface portions 44a to 44c, and the side surface portion 46a.
Through 46f and jaws 48a through 48f, there is a predetermined clearance δ.

Next, as shown in FIG. 5B, the die 52 mounted on the second mold 34 is displaced toward the punch 36, and the outer peripheral portion of the blank 2 is ironed. At this time, the bulging portion 56 formed on the inner side of the die 52 extends the outer peripheral portion of the blank 2 toward the first die 32 and extends the inner surface of the blank 2 toward the punch 36. Run. Therefore, in FIG. 5, when the die 52 is lowered toward the punch 36, the outer peripheral portion of the blank 2 is squeezed by the taper portion 54 of the die 52 and the inside of the blank is moved toward the first die 32 side. While being stretched, the end portions of the undercut portions 16a to 16f are regulated by the tapered surfaces 50a to 50f of the punch 36, and the material (meat portion) forming the blank 2 is driven by the die 52 and is driven by the driven shaft 4 side. Flow toward the undercut portions 16a to 16f. As a result, at the time when the sizing is completed, the convex portions 8a to 8c between the undercut portions 16b, 16c, 16d, 16e and 16f, 16a have two tapered surfaces 50b opposite to each other.
And 50c, 50d and 50e, and 50f and 50a, respectively, so that the undercut portions 16a to 1a are provided near the opening 2a.
The situation where 6f tilts to the punch 36 side does not occur. Therefore, the track grooves 12a to 12f formed along the undercut portions 16a to 16f have extremely excellent dimensional accuracy.

Since the blanks 2 are accurately positioned with respect to the punch 36 by the tapered surfaces 50a to 50f formed on both sides of the long grooves 42a to 42c in the punch 36, the dimensional accuracy of the outer ring obtained by sizing is further improved. When the sizing is completed, the end portions of the undercut portions 16a to 16f are chamfered by the tapered surfaces 50a to 50f (see FIG. 5b). In this case, the second
As in the prior art shown in FIG.
The end of 6f does not bite against the punch 36, and therefore the punch 36 and the blank 2 can be released from each other very easily. As a result, the protruding portion 14a formed to be relatively thin
It is possible to obtain a very good product without fear that the 14 to 14f will be missing during the mold release, and the punch 36 will not be overloaded at the time of mold release, and the punch 36 will have a long life. Also has the advantage of being promoted.

[Effects of the Invention] As described above, according to the present invention, when the punch and the die are made to cooperate with each other, when the preform having the undercut portion extending in the axial direction in the hollow portion is finished, The outer peripheral portion of the preformed product is ironed by a die while the axial end of the cut portion is regulated by a tapered surface formed on the punch. In this case, since a compressive force is applied to the undercut portion by the opposing tapered surfaces, the undercut portion appropriately follows the outer surface of the punch.
Therefore, the undercut portion is molded with excellent dimensional accuracy, and a good product can be obtained. In addition, since the position of the preform with respect to the punch is regulated by the tapered surface during ironing, the positioning accuracy is improved and a better product can be obtained.

[Brief description of drawings]

1a and 1b are partially omitted vertical and horizontal sectional views showing the structure of a blank machined into the outer ring of a constant velocity joint, and FIGS. 2a and 2b are sectional views taken along line II-II of FIG. 1b. FIG. 3 is an explanatory view of a sizing method according to the related art shown in FIG. 3, FIG. 3 is a partially omitted perspective view of a sizing device for carrying out the sizing method according to the present invention, and FIG. 4 is a punch of the sizing device shown in FIG. Side views and FIGS. 5A and 5B are explanatory views when the sizing method according to the present invention is applied to a portion in the II-II line cross section of FIG. 2 ... Blank, 6a-6c ... Recessed part 8a-8c Convex part, 12a-12f ... Track groove 16a-16f ... Undercut part, 30 ... Sizing device 32, 34 ... Mold, 36 ... … Punch 40a-40c …… Square column part, 42a ～ 42c …… Long groove 48a ～ 48f …… Jaw-shaped part, 50a-50f …… Tapered surface 52 …… Die

Claims (2)

[Claims] 1. A sizing method for obtaining a predetermined dimensional accuracy by performing ironing forming on a preform having an undercut portion at a portion bulging in a hollow portion by using a die and a punch. After inserting a punch that regulates the axial end portion of the undercut portion with a tapered surface into the hollow portion of the preform, the outer peripheral portion of the preform is ironed using a die. . 2. The method according to claim 1, wherein the undercut portions are formed symmetrically, and the ends of the respective undercut portions are sandwiched by two tapered surfaces symmetrically provided on the punch. Sizing method.