JPH102342A - Yoke for shaft coupling and manufacture of shaft coupling yoke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight of a yoke for a shaft coupling and improve dimensional accuracy and strength thereof by forming at least two coupling arm parts projected from one end of a shaft part and a bottomed coupling hole part having a deformed section extending from the other end of the shaft part to one end part by plastic working. SOLUTION: Two coupling arm parts 2 projected to be U-shaped and bilaterally symmetrical from one end of a shaft part 10 of a yoke for a shaft coupling are formed by cold forging, a spline 11a is provided from the other end side of the shaft part 10 to one end side, and a bottomed coupling hole part 11 is formed by cold forging. A recess hole 11b having a diameter larger than the diameter of the valley of the spline 11a is formed at the depth part of the spline 11a. The recess hole 11b is not pierced through one end side of the shaft part 10, and one end side is taken as a base 11c for continuously connecting one coupling arm part 2 and the other coupling arm part 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a yoke for a shaft joint having a joint arm for rotatably supporting a cruciform joint in a universal joint and a method of manufacturing the yoke for a shaft joint.

[0002]

2. Description of the Related Art As this type of yoke for a shaft coupling, for example, the one shown in FIGS. 15 and 16 is known. The yoke for a shaft coupling shown in this figure is configured as a part of a universal joint for a propulsion shaft of an automobile or the like, and is usually formed by hot forging (hot working) and machining.

[0003] That is, from one end of the shaft 1 symmetrically U
Two joint arms 2 projecting in the shape of a letter are formed by hot forging, and a bottomed bottom hole is formed by hot forging from the other end of the shaft 1 to one end thereof. Then, a portion remaining as a bottom at one end of the shaft portion 1 is removed by a drill from the other end side, and then a larger hole is drilled from one end side to form a through clearance hole 1a. Further, an annular step portion 1b for attaching the cap 3 coaxially with the through escape hole 1a is formed by machining.

Then, a spline 1c is formed in the pilot hole using a broach (not shown). The through-hole 1a is formed so as to penetrate the shaft portion 1 so that the broach can pass therethrough.

In each joint arm 2, a through hole 2a for rotatably supporting a cross joint (not shown) is formed by machining.

The cap 3 is fixed to the annular end 1b with an adhesive having a sealing property for preventing oil leakage, and is securely fixed to the annular end 1b by caulking 1d.

In the yoke for a shaft coupling constructed as described above, for example, a spline 1c is fitted to a spline shaft (not shown) provided in a transmission, and the spline 1c moves along the spline shaft and reduces the driving force. It will be transmitted to the propulsion axis. At this time, the lubricating oil in the transmission is supplied to the spline 1c,
And the spline shaft are smoothly slid. Since the portion of the through-hole 1a is covered with the cap 3, and the cap 3 is securely fixed to the annular end portion 1b by an adhesive and a caulking 1d having a sealing property, the through-hole 1a is formed. The lubricating oil does not leak from the part.

[0008]

However, in the above-mentioned yoke for a shaft coupling, since the through-hole 1a is formed by machining, the fiber flow (flow of the structure of the metal material) formed by hot forging is formed. Is cut off, resulting in a decrease in strength. Moreover, the rigidity in the torsion direction is reduced by the through-hole 1a. For this reason, it is necessary to improve the strength by increasing the thickness around the through-hole 1a, and there is a problem that the weight increases and the cost increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a yoke for a shaft coupling and a method of manufacturing the yoke for a shaft coupling, which can reduce the weight and cost. It is in.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, at least two joint arms (2) projecting from one end of a shaft (10) are formed by plastic working. A joint hole (11) having a different cross section and a bottom is formed by plastic working from the other end to the one end of the shaft (10).

According to a second aspect of the present invention, in the first aspect of the invention, the plastic working is cold working.

According to a third aspect of the present invention, in the first or second aspect, the joint hole (11) is formed by a vertical groove extending in the axial direction such as a spline or serration.
It is characterized in that it is formed in a different shape in cross section.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the joint hole (11) is formed to have a different cross-sectional shape by a polygonal cross-section. I have.

According to a fifth aspect of the present invention, at least two joint arms (2) projecting from one end of the shaft (10) are formed by plastic working, and the other end of the shaft (10) is connected to one end of the shaft (10). A method of manufacturing a yoke for a shaft coupling, wherein a joint hole (11) having a cross section with a different shape and having a bottom is formed by plastic working. After forming a pilot hole (B2a) reaching the depth by plastic working,
By inserting a mandrel (M3) having a different cross section into the prepared hole (B2a) from the other end side, the prepared hole (B2a) is formed.
It is characterized in that a) is subjected to plastic working into a different cross section.

According to a sixth aspect of the present invention, at least two joint arms (2) projecting from one end of the shaft (10) are formed by plastic working, and the other end of the shaft (10) is connected to one end of the shaft (10). A method of manufacturing a yoke for a shaft coupling, wherein a joint hole (11) having a cross section with a different shape and having a bottom is formed by plastic working. After forming a pilot hole (B2a) reaching the depth by plastic working,
An escape hole (1) is formed at one end of the pilot hole (B2a).
1b), a portion on the other end side of the relief hole (11b) is reduced in diameter by plastic working by drawing to form a reduced diameter pilot hole (B3a). By press-fitting a mandrel (M3) having a different cross section from above, the pilot hole (B3a) having the same reduced diameter is plastically processed into a different cross section.

According to a seventh aspect of the present invention, at least two joint arms (2) projecting from one end of the shaft (10) are formed by plastic working, and the other end of the shaft (10) is connected to one end of the shaft (10). A method of manufacturing a yoke for a shaft coupling, wherein a joint hole (11) having a cross section with a different shape and having a bottom is formed by plastic working. After forming a pilot hole (B2a) reaching the depth by plastic working,
In the pilot hole (B2a), a mandrel (M1
2) is inserted, and the pilot hole (B2a) is plastically worked into an irregular cross section by squeezing from the outside of the portion where the mandrel (M12) is inserted.

The invention according to claim 8 is characterized in that, in the invention according to claim 5, 6, or 7, the plastic working is cold working.

[0018] The present invention is configured as described above.
In the invention according to the first aspect, the joint hole portion (11) having an irregular cross section is provided.
Is formed by plastic working, so that the joint hole (1
It is not necessary to form a hole that penetrates from 1) to one end of the shaft portion (10). That is, the joint hole (11) can be formed as a bottomed one. Therefore, the fiber flow is continuous at one end of the shaft (10),
In addition, since there is no hole at one end, the strength of the portion at one end can be improved. Therefore, the shaft (1
Since the thickness of one end side of (0) and the periphery thereof can be reduced, the weight and cost can be reduced.

Moreover, since there is no need to machine the conventionally formed through clearance hole, the machining cost for the through clearance hole, the machining cost for the annular step portion for attaching the cap, and the cap for the annular step portion are reduced. The work cost for mounting, the cost of parts as a cap, and the like become unnecessary. Therefore, there is a great cost reduction effect.

In the invention according to claim 2, since the cold working is used as the plastic working, the surface becomes clean,
The dimensional accuracy can be improved, and the strength due to work hardening can be improved.

The third and fourth aspects of the invention have the same functions and effects as those of the first or second aspect of the invention.

According to the fifth aspect of the present invention, the mandrel (M3) having a different cross section is press-fitted into the pilot hole (B2a), whereby the pilot hole (B2a) can be easily formed with a different cross section. .

In the invention according to claim 6, the relief hole (11b) is provided at the back of the reduced diameter pilot hole (B3a).
The mandrel (M3) can be press-fitted so as to penetrate the reduced diameter pilot hole (B3a) and reach the escape hole (11b). Therefore, the diameter-reduced pilot hole (B3a) can be reliably formed in a cross-sectionally irregular shape. Further, for example, a shaft provided so as to be fitted to a section having a different cross-section has a relief hole (11).
Since it is possible to enter the inside of b), there is an advantage that the stroke that can be moved along the axis can be increased even if the length of the section having the irregular shape is short. In addition, by shortening the reduced diameter pilot hole (M3a), the mandrel (M3
3) Since the press-in resistance is reduced, there is an advantage that the production efficiency can be improved and the production cost can be reduced.

According to the seventh aspect of the present invention, since the pilot hole (B2a) can be formed to have a different cross-sectional shape by squeezing from the outside of the portion where the mandrel (M12) is inserted, the axially longer cross-sectional shape can be formed. Shape portions can be easily formed.

In the invention according to claim 8, since the cold working is used as the plastic working, the surface becomes clean,
The dimensional accuracy can be improved, and the strength due to work hardening can be improved.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 11 show a first embodiment, and FIGS. 12 to 14 show a second embodiment.

First, a first embodiment will be described with reference to FIGS. Elements common to those of the conventional example shown in FIGS. 15 and 16 are denoted by the same reference numerals, and description thereof will be simplified. The main points of the first embodiment different from the conventional example are that the relief hole 11b does not penetrate and that the spline 11a is formed by cold forging (cold working).

That is, the yoke for the shaft coupling is composed of two joint arms 2 projecting symmetrically from one end of the shaft 10 in a U-shape.
Is formed by cold forging, has a spline 11a from the other end of the shaft portion 10 to one end thereof, and has a joint hole 1 having a bottom.
No. 1 was formed by cold forging. Spline 1
An escape hole 11b having a diameter larger than the diameter of the valley of the spline 11a is formed at the back of 1a. This escape hole 11
b does not penetrate one end side of the shaft portion 10, and this one end portion is a bottom portion 11 c that continuously connects one joint arm portion 2 and the other joint arm portion 2.

Next, a description will be given of a method of manufacturing the yoke for a shaft coupling configured as described above.

First, a raw material is produced by cutting a round bar into a predetermined length, and this material is softened by spheroidizing annealing. Then, the scale on the surface of the material is removed by shot blasting, and the material is subjected to a bonding process (lubrication process). Thereby, the columnar material B1 as shown in FIG.
Is formed.

The material B1 thus processed is shown in FIGS.
It supplies to the press machine for cold forging shown in each process of FIG. First, as shown in FIG.
Insert inside. At this time, the mandrel M1 is set in the die D1 in advance as illustrated. Then, as shown in FIG. 4, the material B1 is pressed from above with the punch P1. Thereby, the material B2 as shown in FIG. 11B is formed by cold forging. This material B2 has a pilot hole B2a for forming the joint hole 11 in the shaft portion 10.

Next, as shown in FIG. 5, a punch P2 is press-fitted into a material B2 in a die D2, and a U-shaped joint arm 2 is formed above the material B2. At the same time, the deep portion on one end side of the prepared hole B2a is left as an escape hole 11b.
The portion on the other end side from 1b is narrowed down to the outer diameter of the mandrel M2 to form a reduced diameter pilot hole B3a. As a result, FIG.
A material B3 as shown in (c) is formed by cold forging. This material B3 has the joint arm portion 2 and the relief hole 11b and the reduced diameter pilot hole B3a in the shaft portion 10.

Next, as shown in FIG. 6, the material B3 is pressed into the die D3 by the punch P3. Then,
The mandrel M3 arranged in the die D3 is shown in FIGS.
As shown in FIG. 9, the mandrel M3 enters the reduced diameter pilot hole B3a, and finally, the tip of the mandrel M3 penetrates the reduced diameter pilot hole B3a to reach the relief hole 11b.

A spline tooth M3a is formed on the outer periphery of the tip of the mandrel M3.
Thereby, the spline 11a is formed in the reduced diameter prepared hole B3a. Further, since the diameter of the peak of the spline teeth M3a is smaller than the diameter of the relief hole 11b, the spline 11a is not formed in the relief hole 11b.

As described above, the material B4 as shown in FIG.
Are formed by cold forging. This material B4 has the joint arm 2 and the joint hole 11 with the spline 11a.

Then, the through-hole 2a is machined in the joint arm 2 to complete the shaft joint yoke shown in FIG.

The above-mentioned dies D1, D2, D3
As shown in FIG. 10, is tightened by a cylindrical ring R, so that a compressive stress is generated in advance on the surface on which each of the materials B1, B2, B3, B4 is formed. Thereby, at the time of formation, each die D1, D2, D3
Of the dies D1, D
2. The durability of D3 is improved.

According to the yoke for a shaft coupling constructed as described above, the joint hole 11 having the spline 11a is formed by cold forging. Need not be formed. That is, the joint hole 11 can be formed as a bottomed one. For this reason, the fiber flow is continuous at one end of the shaft portion 10 and there is no hole, so that the strength of the portion at one end can be improved. Therefore, the thickness of one end side of the shaft portion 10 and the periphery thereof can be reduced, so that the weight and cost can be reduced.

In addition, since the conventionally formed through hole is eliminated, the machining cost for machining the through hole, the machining cost for the annular step for mounting the cap, and the work for attaching the cap to the annular step are eliminated. Cost, parts cost as a cap, etc. become unnecessary. Therefore, there is a great effect on cost reduction.

Further, since it is formed by cold forging, the surface becomes clean, the dimensional accuracy is improved, and the strength by work hardening can be improved.

Further, the mandrel M3 having the spline teeth M3a is press-fitted into the reduced-diameter pilot hole B3a.
The joint hole 11 having the spline 11a can be easily formed.

A relief hole 11 is provided at the back of the reduced diameter pilot hole B3a.
Since the b is provided, the mandrel M3 can be press-fitted so as to penetrate the reduced diameter prepared hole B3a. Therefore, the spline 11a can be reliably formed in the portion of the reduced diameter prepared hole B3a. Further, a spline shaft (not shown) provided to fit into the joint hole 11 is provided with a relief hole 1.
1b, the stroke that can move along the spline axis can be increased even if the length of the spline 11a is short. Therefore, it is advantageous when the yoke for a shaft coupling cannot be assembled unless it is pushed deeply into a spline shaft provided in a transmission, for example.

Furthermore, since the press-in resistance of the mandrel M3 is reduced by shortening the diameter-reduced pilot hole B3a, there is an advantage that the production efficiency can be improved and the production cost can be reduced.

Lastly, the through hole 2a is drilled in the joint arm portion 2. However, since the joint hole portion 11 is closed at one end side, chips when cutting the through hole 2 are formed. Does not enter the joint hole 11. Therefore, there is an advantage that cleaning in the joint hole 11 is simplified.

In the above embodiment, the spline 11a is formed in the reduced diameter prepared hole B3a after forming the reduced diameter prepared hole B3a. However, the spline 11a is formed in the state of the prepared hole B2 as shown in FIG. The spline 11a may be formed in the pilot hole B2. In this case, since it is not necessary to form the reduced diameter pilot hole B3a, the manufacturing cost can be reduced accordingly. However, if the movement range of the yoke for a shaft coupling is to be large, the spline 11a must be formed long, and a large force is required for processing the spline 11a.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. However, since the steps up to the processing of the material B2 shown in FIG. 4 are the same as those of the first embodiment, the description of the manufacturing method before FIG. 4 is omitted.

That is, the material B processed in FIG.
2 is a die D11, a punch P11 and a mandrel M11.
Thereby, the material B13 having the joint arm 2 is formed. That is, as shown in FIG. 13, the material B13 has the joint arm 2 and the shaft 10 has the pilot hole B13a.

Next, as shown in FIG. 14, a mandrel M12 having spline teeth M12a
13a, the mandrel M12 and the material B13
While rotating integrally, the die D12 is
Press. As a result, the deep portion on one end side of the prepared hole B13a is left as the escape hole 11b, and the escape hole 11
A spline 11a is formed in the prepared hole B13a on the other end side of b from the spline teeth M12a of the mandrel M12. That is, the spline 11a is formed on the inner surface by squeezing with the die D12 from the outside of the portion where the mandrel M12 is inserted.

As described above, the material B14 having the joint arm 2 and the relief hole 11b and the spline 11a in the shaft 10 is obtained. Then, a through hole 2 is formed in the joint arm 2.
The yoke for a shaft coupling shown in FIG. 1 is completed by machining a.

In the yoke for a shaft coupling constituted as described above, there is an advantage that the joint hole 11 having the spline 11a long in the axial direction can be easily formed.

In each of the above embodiments, the spline 11a is formed in the joint hole 11, but a serration and a key groove may be formed instead of the spline 11a. Further, instead of the spline 11a, an inner surface having a polygonal cross section such as a triangle, a quadrangle, a pentagon,... May be formed. In other words, the joint hole 11 may be formed with an inner surface having a different cross section different from that of a spline or the like.

[0052]

According to the first aspect of the present invention, since the joint hole (11) having an irregular cross section is formed by plastic working, the joint hole (11) extends from the joint hole (11) to one end of the shaft (10). There is no need to form a hole to penetrate. That is,
The joint hole (11) can be formed as a bottomed one. For this reason, the fiber flow is continuous at one end of the shaft (10) and there is no hole at one end, so that the strength of the portion at one end can be improved. Therefore, the thickness of one end side of the shaft portion (10) and the periphery thereof can be reduced, so that the weight and cost can be reduced.

Moreover, since there is no need to machine the conventionally formed through clearance hole, the machining cost for the through clearance hole, the machining cost for the annular step portion for attaching the cap, and the cap to the annular step portion are reduced. The work cost for mounting, the cost of parts as a cap, and the like become unnecessary. Therefore, there is a great cost reduction effect.

In the invention according to claim 2, since cold working is used as the plastic working, the surface becomes clean,
The dimensional accuracy can be improved, and the strength due to work hardening can be improved.

According to the third and fourth aspects of the invention, the same functions and effects as those of the first or second aspect of the invention are obtained.

According to the fifth aspect of the present invention, the mandrel (M3) having a different cross section is press-fitted into the lower hole (B2a), so that the lower hole (B2a) can be easily formed to have a different cross section. .

In the invention according to claim 6, the relief hole (11b) is provided at the back of the reduced diameter pilot hole (B3a).
The mandrel (M3) can be press-fitted so as to penetrate the reduced diameter pilot hole (B3a) and reach the escape hole (11b). Therefore, the diameter-reduced pilot hole (B3a) can be reliably formed in a cross-sectionally irregular shape. Further, for example, a shaft provided so as to be fitted to a section having a different cross-section has a relief hole (11).
Since it is possible to enter the inside of b), there is an advantage that the stroke that can be moved along the axis can be increased even if the length of the section having the irregular shape is short. In addition, by shortening the reduced diameter pilot hole (M3a), the mandrel (M3
3) Since the press-in resistance is reduced, there is an advantage that the production efficiency can be improved and the production cost can be reduced.

According to the seventh aspect of the present invention, since the pilot hole (B2a) can be formed to have an irregular cross-sectional shape by squeezing from the outside of the portion where the mandrel (M12) is inserted, the axially long cross-sectional irregularity can be formed. Shape portions can be easily formed.

In the invention according to claim 8, since the cold working is used as the plastic working, the surface becomes clean,
The dimensional accuracy can be improved, and the strength due to work hardening can be improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a yoke for a shaft coupling shown as a first embodiment of the present invention.

FIG. 2 is a plan view of a yoke for a coaxial joint.

FIG. 3 is a cross-sectional view illustrating a method of manufacturing a yoke for a coaxial joint, showing a state in which a material is put into a die.

FIG. 4 is a cross-sectional view illustrating a method of manufacturing a yoke for a coaxial joint, in which a prepared hole is cold forged in a material.

FIG. 5 is a cross-sectional view showing a method of manufacturing a yoke for a coaxial joint, in which a joint arm portion and a reduced diameter pilot hole are cold forged in a material.

FIG. 6 is a cross-sectional view showing a method of manufacturing the yoke for a coaxial joint, showing a state where cold forging of a spline into a material is started.

FIG. 7 is a cross-sectional view illustrating a method of manufacturing a yoke for a coaxial joint, which is in the process of cold forging a spline into a material.

FIG. 8 is a cross-sectional view illustrating a method of manufacturing the yoke for a coaxial joint, which is in the process of cold forging a spline into a material.

FIG. 9 is a cross-sectional view showing a method of manufacturing a yoke for a coaxial joint, showing a state in which a spline has been cold forged into a material.

FIG. 10 is a view showing the method of manufacturing the yoke for the coaxial joint, and is a cross-sectional view along the line XX of FIG. 5;

FIG. 11 is a view showing a material of a yoke for a coaxial joint,
(A) is a side view showing a material before cold forging, (b) is a half sectional view showing a material after cold forging a pilot hole, and (c) is a drawing showing a joint arm portion and a reduced diameter pilot hole in a cold state. FIG. 3D is a half-sectional view showing the material after forging, and FIG. 4D is a half-sectional view showing the material after cold forging a spline in a reduced diameter pilot hole.

FIG. 12 is a cross-sectional view showing a method of manufacturing the yoke for a shaft coupling shown as the second embodiment of the present invention, showing a state where a joint arm portion and a pilot hole are cold forged in a material.

FIG. 13 is a view showing a material of a yoke for a coaxial joint,
Sectional drawing which shows the raw material after cold forging a joint arm part and a pilot hole.

FIG. 14 is a cross-sectional view showing a method of manufacturing a yoke for a coaxial joint, showing a state where a spline is cold forged in a pilot hole.

FIG. 15 is a cross-sectional view of a shaft coupling yoke shown as a conventional example.

FIG. 16 is a plan view of a yoke for a coaxial joint.

[Explanation of symbols]

 2 Joint arm 10 Shaft 11 Joint hole 11a Spline 11b Relief hole B2a Prepared hole B3a Reduced diameter prepared hole M3 Mandrel M12 Mandrel

Claims (8)

[Claims] At least two joint arms (2) protruding from one end of a shaft (10) are formed by plastic working, and have a cross-sectional irregular shape from the other end of the shaft (10) to one end thereof. A yoke for a shaft coupling, wherein a bottomed joint hole (11) is formed by plastic working. 2. The yoke for a shaft coupling according to claim 1, wherein the plastic working is cold working. 3. The shaft coupling according to claim 1, wherein the joint hole is formed in a cross-sectionally irregular shape by a longitudinal groove extending in an axial direction such as a spline or a serration. For yoke. 4. The yoke for a shaft coupling according to claim 1, wherein the joint hole (11) is formed to have a cross-sectional irregular shape by a polygonal cross-section. 5. At least two joint arms (2) protruding from one end of the shaft (10) are formed by plastic working, and have a cross-sectional irregular shape from the other end to the one end of the shaft (10). A method of manufacturing a yoke for a shaft coupling, wherein a bottomed joint hole (11) is formed by plastic working, wherein the shaft (10) has a pilot hole reaching a predetermined depth from the other end side. (B2a) is formed by plastic working, and then the mandrel (M2) having an irregular cross section is inserted into the prepared hole (B2a) from the other end.
3) A method of manufacturing a yoke for a shaft coupling, wherein the pilot hole (B2a) is plastically worked into a different cross-section by press-fitting. 6. At least two joint arms (2) protruding from one end of the shaft (10) are formed by plastic working, and have a cross-sectional irregular shape from the other end to the one end of the shaft (10). A method of manufacturing a yoke for a shaft coupling, wherein a bottomed joint hole (11) is formed by plastic working, wherein the shaft (10) has a pilot hole reaching a predetermined depth from the other end side. After (B2a) is formed by plastic working, one end of the pilot hole (B2a) is left as a relief hole (11b), and the other end of the pilot hole (11b) is reduced by plastic working by drawing. Diameter and reduced diameter pilot hole (B3a)
Is formed, and a mandrel (M3) having a different cross section is press-fitted into the reduced diameter pilot hole (B3a) from the other end side to plastically process the same diameter reduction pilot hole (B3a) into a different cross section. Manufacturing method of a yoke for a shaft coupling. 7. At least two joint arms (2) protruding from one end of a shaft (10) are formed by plastic working, and have a cross-sectional irregular shape from the other end to the one end of the shaft (10). A method of manufacturing a yoke for a shaft coupling, wherein a bottomed joint hole (11) is formed by plastic working, wherein the shaft (10) has a pilot hole reaching a predetermined depth from the other end side. After forming (B2a) by plastic working, a mandrel (M12) having a cross-sectionally irregular shape is inserted into the prepared hole (B2a), and the mandrel (M12) is squeezed from the outside of the inserted portion. A method for manufacturing a yoke for a shaft coupling, wherein B2a) is plastically worked into a cross-sectionally different shape. 8. The method of manufacturing a yoke for a shaft coupling according to claim 5, wherein the plastic working is cold working.