JPH08187542A - Manufacture of shaft-like parts with spherical head - Google Patents

Abstract

PURPOSE: To provide a method of through manufacture of shaft-like parts having a spherical head with a neck groove from a base stock by heading, which is capable of precisely forming the neck groove part between the spherical head and the shaft. CONSTITUTION: First, an intermediary formed base stock X3 is formed in which a spherical head part (c) is formed at one end of a columnar part (a) having a diameter smaller than the shaft part (e) of a shaft-like part B as the final product. Next, by means of a split opening/closing die 60 which is split into plural die members 61 and which is made possible to reduce the diameter through a thrusting motion with a punch 14, in a state where the whole circumference of a boundary part between the columnar part (a) and the spherical head part (c) of the intermediary formed base stock X3 is retained from a direction orthogonally crossing the center line of the columnar part (a), the columnar part (a) is wedged into a fixed die 62 for upsetting and bulged out to form a shaft part with a prescribed diameter. Simultaneously, a neck grooved part (f) with a diameter smaller than that of the shaft part (e) is formed at the boundary part between the shaft part (e) and the spherical head part (c).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a shaft-shaped component having a spherical head, and more specifically, to a neck groove portion having a diameter smaller than that of the shaft portion used at a ball joint of an automobile. A method of manufacturing a ball stud having a spherical head formed therethrough.

[0002]

2. Description of the Related Art A ball stud used for a ball joint has a spherical head supported in a socket, and a shaft protruding outward from an opening of the socket so as to be swingable. Further, in order to ensure a large swing angle of the shaft portion of the ball stud, a neck groove portion having a diameter smaller than that of the shaft portion and the spherical head portion is usually formed between the shaft portion of the ball stud and the spherical head portion. ing.

As a method of manufacturing the ball stud, a ball stud body having a shaft portion and a spherical head portion is formed by forging, and thereafter, a ball stud body is formed between the shaft portion and the spherical shaft portion. Although there is one in which the neck groove is separately formed by cutting, this manufacturing method has a problem that the productivity cannot be consistently manufactured by a forging machine and its productivity is very poor. Therefore, for example, Japanese Patent Publication No. 6-3897
As disclosed in No. 0, it is known that not only the shaft portion and the spherical head portion but also the neck groove portion are molded in a forging process so as to improve the productivity.

This manufacturing method uses a material having a diameter equal to the minimum diameter of the neck groove portion of the ball stud to be manufactured. First, a large diameter spherical head and one of the spherical heads has the same diameter as the minimum diameter of the neck groove portion. An intermediate molding material having a columnar part and a neck groove part which is work-hardened higher than the columnar part by drawing between the spherical head part and the columnar part, and then the intermediate molding material is installed in the axial direction. The intermediate part of the columnar part is bulged to form a shaft part having a predetermined diameter.

[0005]

By the way, according to the above-mentioned conventional manufacturing method, the intermediate molding material is set up in the axial direction, and the intermediate portion of the columnar portion having the same diameter as the minimum diameter of the neck groove portion is formed in the axial direction. Direction, and bulges in the outer peripheral direction to form a shaft portion having a predetermined diameter.At this time, the upsetting process is performed in a state where the neck groove portion is not held by the die at all. Therefore, not only the columnar portion but also the neck groove portion is deformed and the dimension of the neck shaft portion is varied. That is, although the neck groove portion is work hardened in advance higher than the columnar portion, a very large pressing force acts on the neck groove portion during upsetting, and therefore, the neck groove portion Deformation occurs and the dimensions of the neck groove part vary. Further, when performing work hardening of the neck groove portion, the degree of work hardening is not stable due to the difference in the material of the material, etc., and when the shaft portion of a predetermined diameter is formed by bulging the intermediate portion of the shaft portion as well. In addition, there is a problem in that the neck groove portion is deformed to deteriorate the dimensional accuracy.

Therefore, an object of the present invention is to provide a spherical head and a shaft portion in a case where a shaft-shaped member having a spherical head portion with a neck groove is made from a rod-shaped material by penetrating it through a press-forming process with high productivity. It is an object of the present invention to provide a method for manufacturing a shaft-shaped component having a spherical head portion capable of accurately forming a neck groove portion at a boundary portion.

Another object of the present invention is to provide a method of manufacturing a shaft-shaped part having a spherical head capable of finishing the shaft portion without impairing the size of the neck groove portion and molding the shaft portion with high accuracy. To provide.

[0008]

In order to achieve the above object, the present invention is characterized in that it is configured as follows.

That is, in the invention according to claim 1 of the present application (hereinafter, referred to as the first invention), the raw material is sequentially supplied to a plurality of forging stations constituted by dies and punches facing each other, and the raw material is stepped. A method of manufacturing a shaft-shaped component in which a spherical head portion is formed at one end of the shaft portion through a neck groove portion having a diameter smaller than that of the shaft portion by mechanically forging.
First, in a predetermined forging station among the above-mentioned multiple stages of forging stations, an intermediate forming material in which a spherical head is formed at one end of a columnar portion having a diameter smaller than that of a shaft portion of a final product is molded. Then, at a forging station downstream of the predetermined forging station, a columnar portion and a spherical head of the intermediate forming material are divided by a split opening / closing die which is divided into a plurality of mold members and can be reduced in diameter by a pushing operation by a punch. The columnar portion is hammered into the fixed die in a state of holding the entire circumference of the boundary portion from the direction orthogonal to the center line of the columnar portion for upsetting, and the columnar portion is expanded to have a predetermined diameter. At the same time as forming the shaft portion, a neck groove portion having a diameter smaller than that of the shaft portion is formed at a boundary portion between the shaft portion and the spherical head portion.

In addition to the structure of the first aspect of the invention, the invention according to claim 2 (hereinafter referred to as the second aspect of the invention) is characterized by a punching operation at a forging station downstream of the forging station forming the neck groove. Shaft drawing is applied to the shaft part, and the tip side of the shaft part is continuous with the outer circumference of the shaft part,
Further, it is characterized by including a finishing step of forming a taper portion having a smaller diameter toward the tip side.

[0011]

According to the above construction, the following actions are obtained respectively.

First, according to the first aspect of the present invention, among a plurality of stages of forging stations, in a predetermined forging station,
An intermediate molding material is formed in which a spherical head is formed at one end of a columnar part having a diameter smaller than that of the shaft part of the final product. Next, in the forging station on the downstream side of the above-mentioned predetermined forging station, the columnar portion and the spherical head of the intermediate forming material are divided by a split opening / closing die that is divided into a plurality of mold members and can be reduced in diameter by a pushing operation by a punch. While holding the entire circumference of the boundary portion from the direction perpendicular to the center line of the columnar portion, the columnar portion is driven into the fixed die for upsetting, and the columnar portion is bulged to form a shaft having a predetermined diameter. At the same time when the shaft portion is formed, a neck groove portion having a diameter smaller than that of the shaft portion is formed at the boundary portion between the shaft portion and the spherical head portion.

As a result, when a shaft-shaped member having a spherical head portion with a neck groove is manufactured consistently by forging from a rod-shaped material, the neck groove portion formed between the spherical head portion and the shaft portion can be accurately formed. Can be formed.

According to the second aspect of the invention, in the forging station on the downstream side of the forging station for forming the neck groove portion, shaft drawing is performed with a pressing force within a range in which the neck groove portion is not deformed by the punch, and the shaft portion It is possible to form, as a finishing process, a tapered portion that is continuous with the outer periphery of the shaft portion on the tip side and has a diameter that decreases toward the tip side. In other words, compared to upsetting, the shaft groove is finished with a smaller load on the neck groove, so the shaft is finished, so it is possible to prevent the dimensions of the neck groove from being impaired.
It is possible to accurately finish the tapered portion and the like on the shaft portion.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

The drawings show an embodiment in which a ball stud B is manufactured as an example of an axial part having a spherical head. FIG. 2 shows a change in shape in the molding process when the ball stud B is manufactured by a forging machine consistently. In the first forging station S1, a solid rod-shaped material X cut into a predetermined length. From the intermediate material X, a columnar portion a having a smaller diameter than the shaft portion e of the manufactured ball stud B and a large-diameter portion b continuous with one end of the columnar portion a are formed.
1 is formed, and in the next second-stage forging station S2, the large-diameter portion b of the intermediate-forming material X1 is shaped into a shape closer to a sphere, and the third-stage forging station S3 is further formed. In step 3, the large diameter portion b of the intermediate forming material X2 is formed in the spherical head portion c, and the intermediate forming material X3 in which the chamfered portion d is formed at the tip corner portion of the columnar portion a is formed. Next, in the fourth-stage forging station S4,
The columnar portion a of the intermediate forming material X3 is bulged to form a shaft portion e having a predetermined diameter, and a neck groove portion f having a smaller diameter than the shaft portion e is formed at a boundary portion between the shaft portion e and the spherical head c. The formed intermediate material X4 is formed, and the small diameter shaft portion h having the chamfered portion d is formed on the tip side of the shaft portion e via the inclined step portion g.
Thereafter, in the fifth forging station S5, the intermediate forming material X5 in which the shaft portion e, the inclined step portion g, and the small diameter shaft portion h of the intermediate forming material X4 are further shaped is formed, and in the final stage forging station S6. Shaft part e of intermediate forming material X5
Is formed on the side of the small-diameter shaft portion h, which is continuous with the outer circumference of the shaft portion e, and has a taper portion i having a gentle inclination whose diameter decreases toward the small-diameter shaft portion h, and the length of the small-diameter shaft portion d is predetermined. Formed in length. Thus, the ball studs B are sequentially molded.

Next, the manufacturing process of the ball stud B and the structure of the forging machine 1 for forging the ball stud B will be described. As shown in FIG. 1, the die block 2 of the machine base is laterally predetermined. Multiple dies at intervals of 3 ~
8 are attached, and a plurality of punches 10 to 15 are attached to the front surface of the ram 9 which is moved back and forth with respect to the die block 2, so that the punches 10 to 15 are attached to the dies 9. Multiple punches 1 corresponding to 8
A plurality of forging stations S1 to S6 consisting of 0 to 15
With the advancement of the ram 9, the material is sequentially punched into each die at each forging station to perform forging processing. The material X is transferred between the forging stations S1 to S6 by a known material transfer chuck (not shown) from the upstream forging station to the downstream forging station.

The first to third forging stations S1 to S3 in the forging stations S1 to S6 are spherical heads c.
As shown in FIG. 1, the forging station S1 of the first stage, which is a forging station for molding, includes a die 3 having a forming recess 3a of the columnar portion a and the large diameter portion b, and a predetermined length. A punch 10 for driving the solid rod-shaped material X cut into the die 8 into the die 8 is provided, and the rod 10 is punched into the die 3 by the punch 10 to produce the neck of the ball stud B to be manufactured. An intermediate material X1 including a columnar portion a having the same diameter as the minimum diameter of the groove portion f and a large diameter portion b integrally formed at one end thereof is formed. Further, as the punch 10 moves backward, the intermediate molding material X1 after molding is discharged to the outside of the die 3 by the knockout pin 16, and the discharged intermediate molding material X1 is conveyed to the second-stage forging station S2. .

As shown in FIG. 1, the second-stage forging station S2 is provided with a punch 11 having a forming recess 11a having the large diameter portion b and a die 4 having a forming recess 4a into which the columnar portion a is fitted. By punching the intermediate molding material X1 into the die 4 by the punch 11, the large diameter part b of the intermediate molding material X1 is shaped into a shape closer to a sphere, thereby molding the intermediate molding material X2. Further, as the punch 11 moves backward, the intermediate material X2 that has been formed is knocked out by the knockout pin 1.
The intermediate molding material X2 discharged to the outside of the die 4 by 7 is conveyed to the third-stage forging station S3.

As shown in FIG. 1, the third-stage forging station S3 includes a punch 12 having a hemispherical recess 12a, a forming recess 5a into which the columnar part a is fitted, and a hemispherical recess 5b communicating with the punching recess 5a. Since the punch 12 drives the intermediate forming material X2 into the die 5,
The large diameter portion b of the intermediate forming material X2 is formed into the spherical head portion c, and the chamfered portion d is formed at the tip corner portion of the columnar portion a to form the intermediate forming material X3. Also, punch 12
The intermediate molding material X3 after molding is discharged to the outside of the die 5 by the knockout pin 18 in accordance with the retreat of No. 3, and the discharged intermediate molding material X3 is conveyed to the forging station S4 at the fourth stage.

The forging station S4 at the fourth stage is a forging station for forming the neck groove portion f and is shown in FIGS.
As shown in FIG. 6, a punch 13 having a hemispherical forming recess 13a, a split opening / closing die 60 which is divided into a plurality of mold members 61 and whose diameter can be reduced by a pressing operation by the punch 13, and a columnar portion a are press-fitted. And a die 6 including a fixed die 62 having a stepped molding recess 62a. The split opening / closing die 60 has a stepped cylindrical shape in which a large-diameter outer peripheral portion 60a and a small-diameter outer peripheral portion 60b are formed via an inclined step portion 60c as shown in FIGS. Is
A concave holding portion 60d for holding the lower portion of the spherical head c and a bulging portion 60e for forming a neck groove portion f are formed, and the opening / closing die 60 is fitted in the hole 2a of the die block 2. It is fitted and inserted in a cylindrical die case 63 that is fixedly fitted. As shown in FIG. 6, the split opening / closing die 60 is composed of mold members 61 divided into four in the circumferential direction, and the mating surfaces of the mold members 61 are formed with concave portions 61a facing each other. The coil springs 64 for urging the mold members 61 in the direction of separating the mold members 61 are provided between the recesses 61a. On the other hand, the inner diameter of the hole 63a in the die case 63 is almost the same as the outer diameter of the small-diameter outer peripheral portion of the split opening / closing die 63c, and the front side of the hole 63a, that is, the inner peripheral surface on the punch side, has the shape shown in FIG. As shown in FIG. 5, a first large-diameter hole portion 63d having a larger diameter than the hole 63a and a second large-diameter portion having a larger diameter than the first large-diameter hole portion 63d are formed through two inclined step portions 63b and 63c. A radial hole portion 63e is formed. As shown in FIG. 4, in the die case 63, the split opening / closing die 60 has a large diameter outer peripheral portion 60a as a second large diameter hole portion 63e and a small diameter outer peripheral portion 60b as a first large diameter hole portion 63d.
Are inserted so as to face each other. Also, FIG.
As shown in FIG. 5, a pressing member 65 that comes into contact with the rear end surface of the split opening / closing die 60 is provided inside the die case 63 behind the split opening / closing die 60 so as to move back and forth. The fixed die 62 is fixed to the central portion of the pressing member 65, and a recess 65 formed on the rear end surface of the pressing member 65.
a and the front concave portion 6 of the load receiving block 66 fixed to the rear end side of the die case 63 and supported on the die block side.
A coil spring 67 is disposed between the coil spring 67 and 6a, and the pressing member 65 is biased toward the punch side by the coil spring 67, whereby the entire split opening / closing die 60 is always biased toward the punch side. It is energized. A retaining member 68 is provided on the front surface of the die case 63 to prevent the split opening / closing die 60 from falling out of the die case 63.

Thus, in the fourth-stage forging station S4, as shown in FIGS. 5 and 6, the punch 13 drives the intermediate forming material X3 into the die 6 side, whereby the tip end of the punch 13 is divided into open and close positions. Each die member 6 of the split opening / closing die 60 is brought into contact with the front surface of the die 60 and is punched by the punch 9.
1 is pushed to the rear side of the die block 2. As a result, the inclined step portion 60c of the split opening / closing die 60 interferes with the inclined step portion 63c of the die case 63, and the diameter of the axial center portion of the split opening / closing die 60 is reduced. The diameter 60b is pushed into the second large diameter hole portion 63d via the inclined step portion 63c, and the small diameter outer peripheral portion 60a is pushed into the second large diameter hole portion 63e via the inclined step portion 63b while reducing the diameter. Then, as the axial center portion of the split opening / closing die 60 is reduced in diameter, the holding portion 6 of the split opening / closing die 60 is formed.
0d and the bulging portion 60e hold the entire circumference of the boundary portion between the columnar portion a and the spherical head c of the intermediate forming material X3 from the direction orthogonal to the axial direction of the columnar portion a. In this state, the columnar portion a is driven into the fixed die 62 to be upset. As a result, by this upsetting, only the columnar portion a is bulged to form the shaft portion e having a predetermined diameter, and at the same time, the shaft portion e is formed at the boundary between the shaft portion e and the spherical head c. Also, the neck groove portion f having a small diameter is accurately formed based on the shapes of the holding portion 60d and the bulging portion 60e of the split opening / closing die 60. At the same time when the shaft portion e is formed, the fixed die 62 forms a small-diameter shaft portion h having a chamfered portion d on the distal end side of the shaft portion e via an inclined portion f, and the intermediate forming material X4 is formed. It will be.

The intermediate molding material X4 after molding is discharged to the outside of the die 6 by the knockout pin 19 as the punch 13 retreats, and the discharged intermediate molding material X4 is conveyed to the fifth forging station S5. It will be. Further, the split opening / closing die 60 is pressed toward the punch side by the coil spring 66 via the pressing member 65 as the punch 13 moves backward, and is moved back to the original position where it comes into contact with the retaining member 68 as shown in FIG. It will be.

The forging station S of the fifth and sixth stages
Reference numerals 5 and S6 are forging stations that perform finishing of the shaft portion e in stages. And the fifth-stage forging station S
5 includes a punch 14 having a hemispherical recess 14a for holding the spherical head portion c, and a die 7 having a forming recess 7a for subjecting the columnar portion a to a shaft drawing process as a finishing step. Intermediate molding material X4 by 7
The shaft portion e and the inclined step portion g are subjected to axial drawing by a pressing force within a range in which the neck groove portion is not deformed to form an intermediate forming material X5 in which the shaft portion e and the small diameter shaft portion h are further shaped. Will be. Further, as the punch 14 moves backward, the intermediate molding material X4 after molding is discharged to the outside of the die 7 by the knockout pin 20, and the discharged intermediate molding material X5 is conveyed to the forging station S6 of the sixth stage. .

On the other hand, the forging station S6 at the sixth stage is
The punch 15 having the hemispherical recess 15a for holding the spherical head c, the rear die 8a for axially drawing the shaft e, and the front for holding the die side hemispherical recess except the neck groove f of the spherical head c. A die 8 including a die 8b is provided, and when the punch 15 is driven, the inclined portion f and the shaft portion e of the intermediate forming material X5 are subjected to axial drawing processing with a pressing force within a range in which the neck groove portion f is not deformed. A tapered portion i is formed on the small-diameter shaft portion h side of the shaft portion e, which is continuous with the outer circumference of the shaft portion e and has a smaller diameter toward the small-diameter shaft portion h side, and the length of the small-diameter shaft portion h. Is formed to have a predetermined length, so that the ball stud B having the shaft portion e finished is formed.

The ball stud B formed as the punch 15 retracts is discharged to the outside of the die 8 by the knockout pin 21 and is taken out from the machine base through the taking-out means as appropriate.

Thus, in the case where the ball stud B having the spherical head portion c with the neck groove is manufactured consistently by forging from the rod-shaped material, the neck groove portion f formed between the spherical head portion c and the shaft portion e. There is no variation in the dimensions of
It is possible to accurately form the neck groove portion f. Also,
Preliminary forming of the shaft portion e by forming the chamfered portion d, the small-diameter shaft portion h, the inclined step portion g, and the like stepwise on the columnar portion a of the intermediate forming material X2 from the third-stage pressing station to the fourth-stage pressing station. Then, the neck groove part e is formed on it 4
In the 5th to 6th stage forging stations S5 and S6, which are on the downstream side of the 8th stage forging station S4, the axial drawing is further stepwise performed by applying a pressing force within a range in which the punch groove 14 or 15 does not deform the neck groove portion e. , The shaft portion e having the tapered portion i and the small-diameter shaft portion h can be formed so that the shape and dimension are accurate and the structure is also dense. In particular, since the shaft portion is finished by shaft drawing, which has a smaller burden on the neck groove portion than the upsetting, it is possible to effectively prevent the dimension of the neck groove portion f from being impaired, but to reduce the taper. It is possible to mold the portion i and the shaft portion e having the small diameter shaft portion h with high accuracy.

In the embodiment shown in the drawing, as shown in FIG. 1, the punch 10 in the second to sixth stage forging stations is used.
The push pins 22 to 26 are inserted through the shaft center portions of the through holes 15. The push pins 22 to 26 are configured to push out the respective materials from the forming recesses of the punches as the punches move back after the working. Coil springs 32 to 36 are interposed between the rear end portions of to 26 and the load receiving members 27 to 31, and the push pins 22 to 26 are constantly urged toward the die by the coil springs 32 to 36.

In the above embodiments, the spherical head c is formed into a solid spherical shape, but the spherical head c is not limited to the solid spherical head c, but is a hollow spherical head c. May be.

In this case, as shown in FIG. 7 and FIG.
The second forging station S2 includes a punch 11 having a punch pin 11b and a die 4 into which the punch pin 11b is inserted. The punch 11 drives the intermediate forming material X1 into the die 4 to perform intermediate forming. Material X
The tip end portion of the punch pin 11b is press-fitted into the large-diameter portion b of No. 1 to form the intermediate forming material X2 in which the cup-shaped head portion p is formed.

After that, using the third-stage forging station S3 similar to the above-mentioned embodiment, the punch 12 having the hemispherical recess 12a is provided on the die 5 side similarly to the above-mentioned embodiment. By driving, the cup-shaped head p of the intermediate forming material X2 is formed into a hollow spherical head c as shown in FIG.
After that, regarding the formation of the neck groove portion f and the formation of the taper portion i7 small-diameter shaft portion h and the like on the shaft portion e, the neck groove portion f and the taper portion are formed by the forging stations from the fourth stage to the sixth stage as in the above-described embodiment. i and the small-diameter shaft portion h may be formed.

Further, although the method of manufacturing the ball stud B has been described in the above embodiment, the method of manufacturing the ball stud B is not limited to the method of manufacturing the ball stud B, and may be, for example, a method of manufacturing a screw part having a spherical head. Of course, it can be applied.

[0033]

As described above, according to the first aspect of the present invention, among a plurality of stages of forging stations, at a certain forging station, one end of the columnar portion having a diameter smaller than that of the shaft portion of the final product is formed. The intermediate forming material with the spherical head is formed, and then, at the forging station on the downstream side of the above-mentioned predetermined forging station, it is divided into a plurality of mold members and the split opening and closing is made possible by the pushing operation by the punch Upsetting by driving the columnar section into the fixed die while holding the entire circumference of the boundary between the columnar section and the spherical head of the intermediate forming material from the direction orthogonal to the center line of the columnar section by the die. Then, the columnar portion is bulged to form a shaft portion having a predetermined diameter, and at the same time, a neck groove portion having a diameter smaller than that of the shaft portion is formed at a boundary portion between the shaft portion and the spherical head.

As a result, in the case where a shaft-shaped member having a spherical head portion with a neck groove is manufactured consistently by forging from a rod-shaped material, the dimension of the neck groove portion formed between the spherical head portion and the shaft portion is determined. The neck groove portion can be accurately formed without causing variations.

According to the second aspect of the invention, in the forging station on the downstream side of the forging station for forming the neck groove portion, the shaft drawing processing is performed by the pressing force within the range in which the neck groove portion is not deformed by the punch, and the shaft portion It is possible to form, as a finishing process, a tapered portion that is continuous with the outer periphery of the shaft portion on the tip side and has a diameter that decreases toward the tip side. In other words, compared to upsetting, the shaft groove is finished with a smaller load on the neck groove, so the shaft is finished, so it is possible to prevent the dimensions of the neck groove from being impaired.
It is possible to accurately perform finish processing such as a tapered portion on the shaft portion.

[Brief description of drawings]

FIG. 1 is a partially omitted transverse sectional view of a forging machine used in a manufacturing method according to the present invention.

FIG. 2 is an explanatory diagram showing a change in shape of a ball stud manufactured by the same press forming machine in a press forming sequence.

FIG. 3 is a cross-sectional view before forming a neck groove portion by a fourth-stage forging station in the same forging machine.

FIG. 4 is an enlarged cross-sectional view of the main part.

FIG. 5 is an enlarged transverse cross-sectional view of a main part after the neck groove is formed by the fourth forging station.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a cross-sectional view of a second and third stage forging station showing another embodiment.

FIG. 8 is a partially cutaway front view of an intermediate molding material having a hollow spherical head.

[Explanation of symbols]

 3-8 Die 10-15 Punch B Shaft-shaped part a Columnar part c Spherical head e Shaft part f Neck groove part i Tapered part S1-S6 Pressing station

Claims (2)

[Claims] 1. A material is sequentially supplied to a plurality of forging stations composed of dies and punches which face each other, and the material is subjected to step-by-step forging, so that one end of the shaft portion is more than the shaft portion. A method for manufacturing a shaft-shaped part having a spherical head formed through a small-diameter neck groove part, first of all, in a predetermined forging station among the forging stations of the plurality of stages, a shaft-shaped part as a final product is An intermediate forming material in which a spherical head is formed at one end of a columnar portion having a diameter smaller than that of the shaft portion is formed, and then, at a forging station downstream from the above-mentioned predetermined forging station, it is divided into a plurality of die members and punched. With a split opening / closing die that can be reduced in diameter by a pushing operation by, the whole circumference of the boundary between the columnar portion of the intermediate forming material and the spherical head is held from a direction orthogonal to the center line of the columnar portion. In this state, the columnar portion is driven into a fixed die and upset, and the columnar portion is expanded to form a shaft portion having a predetermined diameter, and at the same time, the shaft portion is formed at the boundary between the shaft portion and the spherical head. A method of manufacturing a shaft-shaped component having a spherical head, characterized in that a neck groove portion having a diameter smaller than that of the above is formed. 2. In the forging station downstream of the forging station that forms the neck groove portion, the shaft portion is subjected to axial drawing processing by the pushing operation by the punch, and the tip end side of the shaft portion is continuous with the outer periphery of the shaft portion, The method of manufacturing a shaft-shaped component having a spherical head according to claim 1, further comprising a finishing step of forming a tapered portion having a smaller diameter toward the tip side.