JP2003343592A - TRIPOD ASSEMBLY AND METHOD OF COLD FORMING FORGING OF TRIPOD Rough Bar - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve machining efficiency and constant velocity universal joint by reducing the machining process and shortening the trunnion shaft by changing the mounting structure of the retainer for retaining the bearing to the tripod. Provided is a tripod assembly that contributes to downsizing of the device. SOLUTION: In a tripod assembly 10 in which a roller 6 is fitted to a trunnion shaft 3 of a tripod 4 which is a cold closed forged product via a bearing 5, and the bearing 5 is prevented from being removed by a retainer 11 attached to the trunnion shaft 3. When cold forging the tripod 4, the material is caused to flow into a relief portion connected to the tip of the impression of the closing forging die, and a small-diameter boss 17 is coaxially formed integrally with the tip of the trunnion shaft 3. The retainer 11 is joined and fixed to the end face 3a of the forged skin of the trunnion shaft 3 by swaging the boss portion 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant velocity universal joint, particularly a tripod assembly which is a subassembly of a tripod type constant velocity universal joint, and a tripod rough material which is an intermediate body of the tripod which constitutes the tripod assembly. The present invention relates to a cold closed forging method for forging.

[0002]

2. Description of the Related Art A tripod assembly of this type has three trunnion shafts 3 radially around a shaft main body 2 having a shaft hole (with spline) 2a, as shown by reference numeral 1 in FIG.
(One is omitted), a roller 6 fitted to each trunnion shaft 3 of the tripod 4 via a bearing 5, and an annular shape for retaining the bearing 5 with respect to the trunnion shaft 3. It consists of a retainer 7. In such a tripod assembly 1, the retainer 7 has conventionally been structured so as to be retained by a snap ring 9 mounted in an annular groove 8 formed at the tip of the trunnion shaft 3. The tripod assembly 1 forms a constant velocity universal joint together with the tulip by fitting the three rollers 6 into the holding groove of the tulip (not shown).

[0003]

By the way, in the prior art, the tripod 4 is formed by forming a rough shape of the tripod by cold closing forging, and then punching out a portion corresponding to the shaft hole 2a. It was manufactured by machining the hole 2a, the outer peripheral surface of the trunnion shaft 3 which becomes the fitting surface of the bearing 5, the annular groove (snap ring groove) 8 for mounting the snap ring 9, and the end surface of the trunnion shaft 3. . Here, the reason why the end face machining of the trunnion shaft 3 is required is
If the closed forging die is completely sealed, there is a risk that the surface pressure applied to the die will be too large and the die may be damaged.To avoid this, the length of the impression trunnion shaft forming part is set longer than necessary. Is. That is, conventionally, a considerable amount of machining is required until the tripod 4 is completed, and in particular, groove machining for forming the snap ring groove 8 requires a lot of time, and the machining is reduced to improve productivity. Therefore, there is a problem that the advantage of cold closing forging intended for that purpose is lost. Further, while the plate thickness required for the retainer 7 is small, the length L required for the tip side of the trunnion shaft 3 including the snap ring groove 8 is considerably large, and as a result, the trunnion shaft 3 There was also a problem that the overall length of the product became longer and the constant velocity universal joint as a finished product became larger. Note that, for example,
In the constant velocity universal joint described in JP 2001-330047 A, the retainer is bolted to the tip of the trunnion shaft, but even in this case, the end face machining of the trunnion shaft still remains, and Since it requires machining of screw holes, it hardly contributes to the reduction of machining.

The present invention has been made in view of the above-mentioned conventional problems. The problem is to reduce machining by changing the mounting structure of the retainer for retaining the bearing to the tripod. At the same time, the trunnion shaft is shortened to provide a tripod assembly that contributes to improved productivity and downsizing of the constant velocity universal joint. In addition, the tripod rough type which is the intermediate of the tripod that constitutes this tripod assembly is provided. The object is to provide a closed forging method capable of smoothly forging a material.

[0005]

A tripod assembly according to the present invention for solving the above-mentioned problems is such that a roller is fitted through a bearing to a trunnion shaft of a tripod, which is a cold-closed forged product, and the bearing is mounted on the trunnion shaft. In a tripod assembly for a constant velocity universal joint that is retained by a retainer attached to the trunnion shaft, the retainer is joined to the end face of the trunnion shaft by caulking a boss portion integrally formed in advance with the tip of the trunnion shaft. It is characterized by being fixed. In the tripod assembly configured as described above, the retainer is attached by caulking the boss at the tip of the trunnion shaft, so that it is not necessary to form a troublesome snap ring groove for the trunnion shaft, and the snap ring groove is also unnecessary. The trunnion axis is shortened. In the present tripod assembly, the tripod can make the end face of the trunnion shaft to which the retainer is joined and fixed as a forged skin, and in this case, processing of the snap ring groove becomes unnecessary, and in addition, the trunnion shaft No need for end face processing.

On the other hand, a method of cold closing forging of a roughened tripod material according to the present invention for solving the above-mentioned problems is to provide a relief portion having a reduced cross section continuously to the tip of an impression of a closed forging die, and the material is forged during the forging. Is flowed into the relief portion, and the caulking boss portion is integrally formed at the tip of the trunnion shaft corresponding portion. In the cold closing forging method for the roughened tripod material performed in this way, the material escapes into the relief portion continuously provided at the tip of the impression, so that the surface pressure applied to the die does not increase so much, and therefore the die is not damaged. Absent. In the method of the present invention, the material may be allowed to flow into the escape portion while being filled up at the tip of the impression, and in this case, since the accuracy of the end face is sufficient, the end face remains as a forged skin, It can be used as a joint surface of a retainer.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a tripod assembly (subassembly) 10 according to the present invention. Since the entire structure of the tripod assembly 10 is the same as the conventional one shown in FIG. 8, the same parts as those shown in FIG. 8 are designated by the same reference numerals, and the duplicated description will be omitted. I decided to. The feature of the present embodiment is that when cold-forging the tripod rough shape material 15 described later (FIG. 4), the small-diameter boss portion 17 is integrally formed at the tip of the trunnion shaft equivalent portion 16, The retainer 11 for retaining the bearing 5 is fixed to the end face 3 a of the trunnion shaft 3 by caulking the boss 17.

The tripod 4 before subassembly is shown in FIG.
As shown in FIG. 3, each trunnion shaft 3 is coaxially provided with the small-diameter boss portion 17 at the tip thereof. The tripod 4 is in a state in which the forged skin of the tripod rough material 15 is left as it is, except for the shaft hole 2a having the inner diameter spline 2b and the outer peripheral surface of the trunnion shaft 3 which is a fitting surface of the bearing 5. Therefore, the end surface 3a of the trunnion shaft 3 and the outer surface of the boss portion 17 before caulking remain the forged skin. On the other hand, the retainer 11 has a flat plate ring-like simple shape and has an outer diameter slightly smaller than the outer diameter of the bearing 5 and an inner diameter slightly larger than the outer diameter of the boss portion 17. It is set. It should be noted that the bearing 5 here is a roller with a cage in which both ends of the roller 5a are supported by the cage 5b, but the type of the bearing 5 used in the present invention is arbitrary, and for example, an inner ring and an outer ring may be used. It is possible to use a so-called needle roller bearing in which rollers are arranged between the outer ring and the roller 6, and in this case, the outer ring is replaced with the roller 6 by forming the outer peripheral surface of the outer ring into a curved surface having a predetermined curvature. can do.

To assemble the tripod assembly 10, as shown in FIG. 3, the trunnion shaft 3 of the tripod 4 (FIG. 2) is fitted with the bearing 5 and the roller 6 for subassembly, and then the assembly is shown. The retainer 11 prepared separately is fitted into the boss portion 17 at the tip of the trunnion shaft 3 (), and then the automatic crimping machine is started. Then, a head (not shown) in the automatic caulking machine advances to crush the boss portion 17 in the axial direction, whereby the retainer 11 is joined and fixed to the end surface of the trunnion shaft 3 by the caulking portion 12 ().

The tripod assembly 10 having the above structure
In the above, the snap ring 9 (FIG. 8), which has been conventionally required, is unnecessary, and therefore the machining of the annular groove 8 (FIG. 8) on the trunnion shaft 3 is also unnecessary. Further, since the end surface 3a of the trunnion shaft 3 and the outer surface of the boss portion 17 before caulking are used as they are forged skin, the end surface processing (machining) for the trunnion shaft 3 which is conventionally required is not necessary. That is, in the present embodiment,
Grooving and end face machining of the trunnion shaft 3 of the tripod 4 are not necessary at all, and the productivity of the tripod 4 is remarkably improved because the machining of these is unnecessary. Further, since the caulking portion 12 formed by crushing the boss portion 17 only exists on the front side of the retainer 11 in a flat shape, the retainer 11
The total length of the trunnion shaft 3 including the caulking portion 12 is significantly reduced as compared with the conventional one. That is, since the total length of the trunnion shaft 3 is reduced, the tripod assembly 10 becomes smaller, and as a result, the constant velocity universal joint including the tripod assembly 10 and the tulip (not shown) also becomes smaller.

Here, the tripod rough shape member 15 is formed by cold closing forging by a closing forging die (FIGS. 5 and 6) described later, and corresponds to the shaft main body 2 as shown in FIG. Around the shaft main body corresponding part 18, three trunnion shaft corresponding parts 16 are radially provided. On the upper and lower end surfaces of the shaft main body corresponding portion 18, a recessed hole 1 as a pushing mark of the punch 22 (FIGS. 5 and 6) forming the closed forging die is formed.
9 and 19 are formed, and the bottom of the recess 19 has a residual thickness portion 18a having a predetermined thickness. In order to manufacture the tripod 4, the residual portion 18a remaining in the shaft main body corresponding portion 18 of the tripod rough shaped material 15 is punched with a punching die, and then the necessary machining is performed on this. The range of machining in this case is the inner diameter spline 2 as described above.
Only the outer peripheral surface of the trunnion shaft 3 which is the fitting surface of the shaft hole 2a having b and the bearing 5 is provided.

A closed forging die for cold closing and forging the tripod crude material 15 has a structure shown in FIGS. In both figures, 20 is a pair of upper and lower dies, 21 is a pair of upper and lower reinforcing rings for fitting and holding the respective dies 20, and 22
Is a pair of upper and lower punches (assembly punches) slidably fitted in the through holes 20a of each die 20. Reinforcement ring 2
The pair of upper and lower dies 20 including 1 and the pair of upper and lower punches 22 are incorporated into a double-action press machine, and are respectively driven up and down by a dedicated drive mechanism. The pair of upper and lower dies 20 including the reinforcing ring 21 are closed by a predetermined mold clamping force F during forging, and in this mold closed state, an impression 23 that follows the outer shape of the tripod 4 is drawn between them. Is made. On the other hand, a pair of upper and lower punches 22
During forging, is driven in a direction in which the through holes 20a of the corresponding dies 20 approach each other, and operates so as to push the material W previously supplied between the two into the impression 23. The assembly punch 22 includes a solid inner punch 22a and a cylindrical outer punch 22b surrounding the inner punch 22a.
Is always positioned so as to protrude from the tip of the outer punch 22b by a predetermined length. Further, a guide hole (bush) 24 and a guide pin 25 are provided between the pair of upper and lower reinforcing rings 21 for guiding the mold opening and closing and for accurately positioning the pair of upper and lower dies 20.

A relief section 26 having a reduced cross section is connected to the tip of the trunnion shaft molding section 23a of the impression 23 defined between the pair of upper and lower dies 20. The relief portion 26 is for integrally molding the boss portion 17 at the tip of the trunnion shaft-corresponding portion 16 (FIG. 4). Here, the inner volume of the relief portion 26 is larger than that required for the boss portion 17. Is set.

The cold closing forging method using the closing forging die will be described below with reference to FIG. In the cold closing forging, first, the pair of upper and lower dies 20 including the reinforcing ring 21 are closed with a predetermined mold clamping force F by the operation of a dedicated drive mechanism, and then the upper side is closed. The blank (W) W having a predetermined size is loaded into the through hole 20a of the die 20 and is supported by the lower punch 22 which is previously fitted into the through hole 20a of the lower die 20. next,
The upper punch 22 is lowered by the operation of an elevating mechanism (not shown), the tip of the punch 22 is fitted into the through hole 20a of the upper die 20 that abuts the upper end of the material W, and then the upper and lower sides are moved by the operation of a dedicated drive mechanism. The pair of punches 22 are driven so as to approach each other.

Then, the material W is installed by the pair of upper and lower punches 22, and as shown in FIG. 7, the material W'flows into the trunnion shaft forming portion 23a of the impression 23, and subsequently shown in FIG. Thus, the tip of the material W ′ reaches the tip of the impression 23. A part of the material W ′ that has reached the tip of the impression 23 is a trunnion shaft forming portion 23 a, as indicated by a small arrow in FIG.
Along with going to the corner portion P1 at the tip of the, the rest goes into the escape portion 26. Finally, as shown in FIG. 7, the material W
Inflow until the tip of ′ comes into contact with the bottom surface of the escape portion 26, and at this stage, the press becomes the bottom dead center as shown in FIG. 6, and the tripod rough shaped material provided with the boss portion 17 at the tip of each trunnion equivalent portion 16 15 is completed.

In the cold closing forging, as shown in FIG. 7, the material W'reaching the tip of the impression 23 is shunted toward the corner P1 of the trunnion shaft forming portion 23a and the escape portion 26. As a result, the surface pressure does not rise so much, which prevents damage to the mold. Moreover, since the inner volume of the escape portion 26 is set to be larger than the volume required for the boss portion 17, at the final stage of forging, as shown in FIG.
As shown in, the material W'does not fill up in the escape portion 26, and a gap exists in the corner P2,
Therefore, even in this final stage, the surface pressure does not rise so much, and the damage to the mold is prevented. On the other hand, since the material W ′ is sufficiently filled up in the trunnion shaft forming portion 23a including the corner portion P1, the end surface 16a of the trunnion shaft corresponding portion 16 in the obtained tripod rough shaped material 15 (FIG. 4). The shape precision of the end face 16 is also sufficient.
Even if a is used as a forged surface as the joint surface of the retainer 11 (the end surface 3a of the trunnion shaft 3), no problem occurs.

In the above embodiment, the end surface 16a of the tripod rough shaped material 15 is used as the joint surface of the retainer 11, but in the present invention, the joint surface of the retainer 11 is finished by machining. It's okay. In this case, since it is not necessary to fill up the material up to the corner portion P1 of the trunnion shaft forming portion 23a of the impression 23, the increase of the surface pressure is further suppressed, and the die damage is more reliably prevented. However, since the trunnion shaft forming portion 23a needs to be extended by the machining allowance, the trunnion shaft 3 in the tripod 4 as a finished product is slightly longer than in the above-described embodiment.

[0018]

As described above, according to the tripod assembly of the present invention, the retainer for retaining the bearing is attached by caulking the boss portion integrally formed in advance at the tip of the trunnion shaft. Since it is not necessary to process the snap ring groove for the trunnion shaft,
Productivity is improved. Further, since the trunnion shaft is shortened by the amount that the snap ring groove is unnecessary, it contributes to downsizing of the constant velocity universal joint. And, if the end face of the trunnion shaft to which the retainer is joined and fixed is forged skin, in addition to the need for processing the snap ring groove,
Since the end face machining of the trunnion shaft is unnecessary, the productivity is further improved. On the other hand, according to the cold closing forging of the roughened tripod material according to the present invention, the material escapes into the escape portion that is continuous with the tip of the impression, so that the surface pressure applied to the die does not increase so much, and thus the die is damaged. There is no such thing. When the material is made to flow into the clearance while filling up the tip of the impression, the accuracy of the end face of the trunnion shaft is sufficient, so it is possible to use the end face as a retainer joint surface without changing the forged skin. Therefore, the cost of the tripod assembly is greatly reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing the entire structure of a tripod assembly according to the present invention as a partial cross section.

FIG. 2 is a cross-sectional view showing a structure of a tripod which constitutes the present tripod assembly.

FIG. 3 is a cross-sectional view showing the steps of assembling the tripod assembly in sequence.

FIG. 4 is a cross-sectional view showing the shape of a rough tripod material used as a tripod that constitutes the present tripod assembly.

FIG. 5 is a cross-sectional view showing the structure of a closed forging die for cold closed forging of a roughened tripod material and an initial stage of use.

FIG. 6 is a cross-sectional view showing a structure of a closed forging die for cold closing and forging a roughened tripod material and a final stage of use.

7A to 7C are cross-sectional views sequentially showing the behavior of a material during cold closing forging.

FIG. 8 is a plan view showing the entire structure of a conventional tripod assembly as a partial cross section.

[Explanation of symbols]

3 Tripod trunnion shaft 4 tripod 5 bearings 6 roller 10 tripod assembly 11 retainer 12 Caulking part 15 Tripod rough shape material 16 Trunnion shaft equivalent part 17 Boss 20 dies 22 punch 23 impressions 26 Runaway

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Suzuki             1-1 Asahi-cho, Kariya city, Aichi             Machine Co., Ltd. (72) Inventor Yoshimi Aoki             1-1 Asahi-cho, Kariya city, Aichi             Machine Co., Ltd. F-term (reference) 4E087 AA10 CA33 CC03 DB01 DB24                       EC13 HA21

Claims (4)

[Claims] 1. A tripod assembly for a constant velocity universal joint in which a roller is fitted through a bearing to a trunnion shaft of a tripod which is a cold closed forged product, and the bearing is retained by a retainer attached to the trunnion shaft. The tripod assembly is characterized in that the retainer is joined and fixed to the end face of the trunnion shaft by caulking a boss portion integrally formed in advance with the tip of the trunnion shaft. 2. The tripod assembly according to claim 1, wherein an end surface of the trunnion shaft to which the retainer is joined and fixed has a forged surface. 3. A relief section having a reduced cross section is continuously provided at the tip of an impression of a closed forging die, and a material is caused to flow into the relief section during forging, and a caulking boss portion is integrally formed at the tip of the trunnion shaft-corresponding section. A cold-closed forging method for a rough tripod material characterized by being formed. 4. The method of cold closing forging of a tripod crude material according to claim 3, wherein the material is caused to flow into the relief portion while being filled up at the tip of the impression.