JPH0459058B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a precision forging method for an inner ring of a constant velocity automatic joint.

Before explaining the prior art, as a typical example of a constant velocity automatic joint, a well-known bar field type constant velocity automatic joint will be briefly described with reference to FIG. Install 20,
Between the inner ring 20 and the outer ring 13 of the drive shaft 12, normally six balls 15 held by a cage 14 are arranged via respective ball grooves 13a, 20a of each ring 13, 20. The drive shaft 12 and the driven shaft 10 are designed to maintain constant velocity regardless of the bending angle. As shown in FIGS. 2 and 3, the inner ring 20 has a circular H-shaped cross section with a central extra wall portion 22, and has ball grooves 20a on the outer periphery.
The intermediate molded product 21 having a shape of ~20a is punched out by punching out the excess thickness 22, and the driven shaft 1
It is manufactured by performing various post-processing such as grinding to form a spline that fits into the spline portion 11 of No. 0.

[Prior art]

The intermediate molded product 21 of the inner ring 20 described above is conventionally
As shown in FIG. 4, the central excess wall portion 22 is punched out with a punch 24 while placed on the die 23, and then, as shown in FIG. After cutting the surface 25 with the cutting tool 26, the inner ring 20 is completed by forming spline grooves on the inner peripheral surface.

Therefore, during the above-mentioned punching process, the punching load applied to the central excess wall portion 22 of the intermediate molded product 21 causes distortion in the molded product 21, which particularly impairs the accuracy of the ball grooves 20a to 20a. There were flaws.

[Purpose of the invention]

Therefore, this invention was devised in view of the above-mentioned drawbacks of the conventional art, and its purpose is to reduce the central excess thickness of the intermediate molded product of the inner ring of a constant-velocity left-hand joint, impairing the accuracy of the molded product. It is an object of the present invention to provide a precision forging method that can perform punching without any scratches and improve the precision of the ball groove of the molded product.

[Structure of the invention]

To achieve the above-mentioned object, the present invention is directed to the manufacturing process of the inner ring of a constant velocity universal joint, in which the inner ring is formed into a circular shape with an H-shaped cross section in the previous step, and a predetermined ball groove is formed on the outer periphery of the inner ring. This is a precision forging method that involves punching out the excess thickness at the center of the molded product while supporting it with upper and lower support dies, and ironing the inner peripheral surface of the molded product. The feature is that the center excess thickness is punched out while the molded product is restrained by the upper and lower support dies, and the inner peripheral surface of the molded product is squeezed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 6 and 7.
This will be explained according to the diagram. In FIG. 6, which shows the punching state in cross section, the intermediate molded product 21 is supported by upper and lower support dies 30 and 31. The support molds 30 and 31 are formed with concave surfaces 32 and 33 corresponding to the outer shape of the inner ring 20 (see FIG. 1) of the constant velocity automatic joint, that is, the outer peripheral surface and the annular upper and lower end surfaces, and are also formed with concave surfaces 32 and 33 that correspond to the outer circumferential surface and the annular upper and lower end surfaces. 21 central excess portion 22
Opening holes 34 and 35 are opened in the vertical direction. Then, the punch 24 is moved downwardly through the opening hole 34 of the upper support mold 30 by a press device (not shown) to the central excess wall part 22 of the intermediate molded product 21 supported by the upper and lower support molds 30 and 31. Seshime, cut out the same extra flesh part 22 (punching process)
and discharged through the opening hole 35 of the lower support mold 31.

After that, as shown in FIG.
Instead of the ironing punch 36, use the punching punch 24.
The inner peripheral surface 2 of the intermediate molded product 21 is operated in the same manner as
5 with the bulging part 37 of the ironing punch 36 to plastically deform it (ironing process), the inner circumferential surface 25 can be formed without cutting and with a low load, and the ball groove 20
The accuracy of a to 20a is corrected.

Further, the following may be considered as a modification of the above embodiment.

(a) As shown in FIG. 8, an ironing bulge 37 is integrally formed on the outer periphery of the punch 24, and the punch 24 is connected to the
By operating the intermediate molded product 21 supported at 0 and 31 in the same manner as in the embodiment, the punching process (9th
(see figure) and ironing of the inner circumferential surface 25 (see figure 10) can be achieved continuously in one step.

(b) As shown in FIG. 11, an ironing bulge 37 and a spline forming land 38 adjacent to the bulge 37 are integrally formed on the outer periphery of the punch 24. , this punch 2
4 on the intermediate molded product 21 supported by the upper and lower support molds 30 and 31 in the same manner as in the embodiment, the central surplus portion 22 of the intermediate molded product 21 is
(see Figure 12) and the inner peripheral surface 25
To achieve the rolling process and the spline forming process (see FIG. 13) continuously in one process.

(c) After lubricating the intermediate molded product 21 from which the excess thickness 22 has been removed by the punch 24 in the above embodiment, as shown in FIG. Swelling part 3 for squeezing
A composite punch 39 in which a spline-forming land part 38 and a spline-forming land part 38 are arranged side by side is operated in the same manner as a punching punch 24, and ironing of an inner circumferential surface 25 and spline-forming process are continuously achieved in one step.

〔Effect of the invention〕

That is, the present invention has the above-mentioned structure as its gist, and uses a forging method in which an intermediate molded product of the inner ring of a constant velocity automatic joint is restrained by upper and lower support dies, and the center surplus part is punched out, and the inner circumferential surface of the molded product is squeezed. Therefore, it is possible to prevent the occurrence of distortion in the intermediate molded product due to the punching load, and the punching process can be performed without impairing the precision of the molded product. The accuracy of the ball groove is improved at the same time as machining the peripheral surface.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a bar field type constant velocity universal joint, Fig. 2 is a plan view of an intermediate molded product of the inner ring, Fig. 3 is a sectional view taken along the - line in Fig. 2, and Figs. 4 and 5 are conventional joints. Examples are shown in Fig. 4, a cross-sectional view of the punching state, Fig. 5, a cross-sectional view of the cutting state, and Fig. 6.
7 and 7 show an embodiment of the present invention. FIG. 6 is a sectional view of the punching state, FIG. 7 is a sectional view of the ironing state, and FIGS. 8 to 14 are sectional views of the embodiment. Fig. 8 is a front view of another example of the punch, Figs. 9 and 10 are cross-sectional views showing the machining state of the same punch, and Fig. 1 shows a modified example.
1 is a front view of another example of a punch, FIGS. 12 and 13 are cross-sectional views showing the state of processing by the same punch, and FIG. 14 is a cross-sectional view showing the state of processing in the post-process of punching. 20...Inner ring, 20a...Ball groove, 21...
Intermediate molded product, 22...Excess wall portion, 24...Punching punch, 25...Inner peripheral surface of intermediate molded product, 30, 31
... Support type, 36 ... Shigoki punch.

Claims (1)

[Claims] 1. In the manufacturing process of the inner ring of a constant velocity universal joint, an intermediate molded product formed into a circular shape with an H-shaped cross section in the previous process and with a predetermined ball groove formed on its outer periphery is supported by upper and lower support molds. A precision forging method for the inner ring of a constant velocity universal joint, which is characterized by punching out the central excess thickness of the molded product and ironing the inner peripheral surface of the molded product.