JP2777997B2 - Method for manufacturing shaft-shaped part having spherical head - Google Patents

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-like component having a spherical head, and more particularly, to a method of manufacturing a shaft joint used mainly for a ball joint of an automobile, in which a neck groove having a diameter smaller than that of the shaft is provided. The present invention relates to a method of manufacturing a ball stud having a spherical head formed thereon.

[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 secure a large swing angle of the shaft portion of the ball stud, a neck groove portion having a smaller diameter than 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.

[0003] 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 ball portion and the spherical shaft portion. There is a method in which the above-mentioned neck groove is separately formed by cutting. However, this manufacturing method has a problem in that consistent manufacturing cannot be performed by a pressure forming machine and the productivity is extremely poor. Therefore, for example,
As disclosed in Japanese Patent No. 0, there is known an apparatus in which not only a shaft part and a spherical head part but also the above-mentioned neck groove part are formed by a forging process to improve the productivity.

In this manufacturing method, a ball stud to be manufactured is made of a material having a diameter equal to the minimum diameter of the neck groove portion. First, a large-diameter spherical head and one of the spherical heads have the same diameter as the minimum diameter of the neck groove portion. An intermediate molding material having a columnar portion and a neck groove portion that has been hardened higher than the columnar portion by drawing between the spherical head and the columnar portion, and then the intermediate molding material is set in the axial direction. The intermediate portion of the columnar portion is bulged to form a shaft portion having a predetermined diameter.

[0005]

According to the conventional manufacturing method described above, 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 is replaced with the shaft. Direction, and swell 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 at all with respect to the die. Therefore, deformation occurs not only in the columnar portion but also in the neck groove portion, and the dimension of the neck shaft portion varies. In other words, although the work is hardened in advance in the neck groove portion higher than the columnar portion, a very large pressing force acts on the neck groove portion at the time of upsetting. Deformation occurs, causing variations in the dimensions of the neck groove. Also, when performing the work hardening of the neck groove portion, the degree of work hardening is not stable due to a difference in the material of the material and the like, and thus, when the shaft portion having a predetermined diameter is formed by expanding the intermediate portion of the shaft portion. In addition, there is a problem in that the neck groove is deformed and the dimensional accuracy is deteriorated.

Therefore, an object of the present invention is to produce a shaft-shaped member having a spherical head with a neck groove from a rod-shaped material through a productive die-forming process through a forging process. It is an object of the present invention to provide a method of manufacturing a shaft-like component having a spherical head capable of forming a neck groove at a boundary portion with high accuracy.

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

[0008]

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

That is, the invention according to claim 1 of the present application (hereinafter, referred to as a first invention) is to sequentially supply a raw material to a plurality of forging stations constituted by dies and punches facing each other, and to step the raw material. A method of manufacturing a shaft-shaped part having a spherical head formed at one end of the shaft portion through a neck groove portion having a smaller diameter than the shaft portion, by performing forging work,
First, at a predetermined forging station among the plurality of forging stations, an intermediate molding material in which a spherical head is formed at one end of a columnar portion having a smaller diameter than the shaft portion of the shaft-like component as a final product is formed. Then, at a forging station downstream of the predetermined forging station, a column-shaped portion and a spherical head of the intermediate molding material are formed by a split opening / closing die which is divided into a plurality of mold members and whose diameter can be reduced by a pushing operation by a punch. In the state where the entire circumference of the boundary with the portion is held from the direction orthogonal to the center line of the columnar portion, the columnar portion is driven into the fixed die by upsetting, and the columnar portion is expanded to have a predetermined diameter. At the same time as forming the shaft, a neck groove having a smaller diameter than the shaft is formed at the boundary between the shaft and the spherical head.

The invention according to claim 2 (hereinafter referred to as the second invention) is characterized in that, in addition to the structure of the first invention, a punching operation by a punch is performed at a forging station downstream of a forging station for forming a neck groove. Shaft drawing is performed on the shaft, and it is continuous with the outer periphery of the shaft at the tip side of the shaft,
And a finishing step of forming a tapered portion having a smaller diameter toward the distal end side.

[0011]

According to the above arrangement, the following operations can be obtained.

First, according to the first invention, in a predetermined forging station of the plurality of forging stations,
An intermediate molding material in which a spherical head is formed at one end of a columnar portion having a smaller diameter than a shaft portion of a shaft-shaped component as a final product is formed. Next, at a forging station downstream of the predetermined forging station, a split opening / closing die which is divided into a plurality of mold members and whose diameter can be reduced by a pushing operation by a punch, thereby forming a columnar portion and a spherical head of the intermediate molding material. With the entire periphery of the columnar portion held in a direction orthogonal to the center line of the columnar portion, the columnar portion is driven into the fixed die by upsetting, and the columnar portion is expanded to form a shaft having a predetermined diameter. At the same time when the portion is formed, a neck groove having a smaller diameter than the shaft is formed at the boundary between the shaft and the spherical head.

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

According to the second aspect of the present invention, in the forging station downstream of the forging station for forming the neck groove, the shaft drawing is performed with a pressing force in a range where the neck groove is not deformed by the punch. It is possible to form a tapered portion on the distal end side which is continuous with the outer periphery of the shaft portion and has a smaller diameter toward the distal end side as a finishing process. In other words, since the shaft portion is finished by a shaft drawing process that has a smaller load on the neck groove portion than the upsetting process, it is possible to suppress the dimensions of the neck groove portion from being damaged,
It is possible to precisely finish the tapered portion or 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 a shaft-shaped part having a spherical head. FIG. 2 shows a change in shape in a molding process when ball studs B are consistently manufactured by a forging machine. In a first forging station S1, a solid rod-shaped material X cut to a predetermined length is shown. From the above, an intermediate material X in which a columnar portion a having a smaller diameter than the shaft portion e of the ball stud B to be manufactured and a large diameter portion b continuous to one end of the columnar portion a are formed.
In the next second-stage forging station S2, an intermediate molding material X2 in which the large-diameter portion b of the intermediate molding material X1 has been further shaped into a more spherical shape is formed, and a third-stage forging station S3 is formed. In step (1), an intermediate molding material X3 in which a large-diameter portion b of the intermediate molding material X2 is formed on the spherical head c and a chamfered portion d is formed at the corner of the tip of the columnar portion a. Next, at the fourth forging station S4,
The columnar portion a of the intermediate molding material X3 swells to form a shaft portion e having a predetermined diameter, and a neck groove f having a smaller diameter than the shaft portion e is formed at a boundary between the shaft portion e and the spherical head c. The intermediate molding material X4 is formed and has a small-diameter shaft portion h having a chamfered portion d at the tip end side of the shaft portion e via an inclined step portion g.
Then, at the fifth stage forging station S5, an intermediate molding material X5 in which the shaft portion e, the inclined step portion g, and the small-diameter shaft portion h of the intermediate molding material X4 are further shaped is formed, and at the final stage forging station S6. Shaft e of intermediate molding material X5
On the side of the small-diameter shaft portion h, there is formed a tapered portion i having a gentle slope that is continuous with the outer periphery of the shaft portion e and has a smaller diameter toward the small-diameter shaft portion h. Formed to length. Thus, the ball studs B are sequentially formed.

Next, the manufacturing process of the ball studs B and the structure of the head forming machine 1 for forming the ball studs B will be described. As shown in FIG. 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 as to correspond to the dies 3 to 8, respectively. Punches 1 corresponding to 8
A plurality of forging stations S1 to S6 including 0 to 15
The material is sequentially driven into each die at each forging station by the advancement of the ram 9 to perform forging processing. The transfer of the material X between these forging stations S1 to S6 is performed sequentially from the upstream forging station to the downstream forging station by a known material transfer chuck (not shown).

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, a first-stage forging station S1 includes a die 3 having a forming recess 3a having the columnar portion a and the large-diameter portion b, and a predetermined length. And a punch 10 for driving a solid rod material X cut into a die 8 into a die 8. The punch 10 drives the rod material X into the die 3 to form a neck of a ball stud B to be manufactured. An intermediate material X1 composed of 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, with the retraction of the punch 10, the formed intermediate forming material X1 is discharged out of the die 3 by the knockout pins 16, and the discharged intermediate forming material X1 is transported to the second-stage forging station S2. .

As shown in FIG. 1, the second stage forging station S2 includes a punch 11 having a molding recess 11a having the large diameter portion b and a die 4 having a molding 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 intermediate molding material X2 in which the large-diameter portion b of the intermediate molding material X1 is further shaped into a more spherical shape is formed. Further, the intermediate material X2 after molding is moved along with the retraction of the punch 11 so that the knockout pin 1
7, the intermediate molding material X2 discharged from the die 4 is conveyed to the third forging station S3.

As shown in FIG. 1, the third-stage forging station S3 includes a punch 12 having a hemispherical concave portion 12a, a molded concave portion 5a into which the columnar portion a is fitted, and a hemispherical concave portion 5b communicating therewith. When the intermediate molding material X2 is driven into the die 5 by the punch 12,
The large-diameter portion b of the intermediate molding material X2 is formed into a spherical head c, and a chamfered portion d is formed at the corner of the tip of the columnar portion a to form the intermediate molding material X3. The punch 12
With the retreat, the formed intermediate forming material X3 is discharged out of the die 5 by the knockout pin 18, and the discharged intermediate forming material X3 is transported to the fourth-stage forging station S4.

The fourth stage forging station S4 is a forging station for forming the neck groove f, and is shown in FIGS.
As shown in FIG. 6, a punch 13 having a hemispherical molding recess 13a, a split opening / closing die 60 divided into a plurality of mold members 61 and reduced in diameter by a pushing operation by the punch 13, and a columnar portion a are press-fitted. And a fixed die 62 having a stepped concave portion 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 part of the spherical head c and a bulging portion 60e for forming a neck groove f are formed, and the opening / closing die 60 fits into the hole 2a of the die block 2. It is fitted into a cylindrical die case 63 that is fixed together. As shown in FIG. 6, the split opening / closing die 60 is constituted by four mold members 61 divided into four in the circumferential direction, and concave portions 61a facing each other are formed on the mating surfaces of the mold members 61. The coil springs 64 that urge the mold members 61 in the direction of separating the mold members 61 are provided between the concave portions 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 is shown in FIG. As shown in FIG. 5, a first large-diameter hole 63d having a diameter larger than the hole 63a and a second large-diameter hole having a diameter larger than the first large-diameter hole 63d are provided via two inclined steps 63b and 63c. A radial hole 63e is formed. As shown in FIG. 4, the split opening / closing die 60 has a large-diameter outer peripheral portion 60a in the die case 63, a second large-diameter hole portion 63e, and a small-diameter outer peripheral portion 60b in the first large-diameter hole portion 63d.
Are inserted so as to be in contact with each other. FIG.
As shown in the figure, a pressing member 65 that comes into contact with the rear end face of the split opening / closing die 60 is provided inside the die case 63 behind the split opening / closing die 60 so as to be able to move forward and backward. The fixing die 62 is fixed to the center of the pressing member 65, and a recess 65 formed on the rear end face of the pressing member 65.
a, the front recess 6 of the load receiving block 66 fixed to the rear end of the die case 63 and supported by the die block.
6a, a coil spring 67 is provided, and the pressing member 65 is urged toward the punch by the coil spring 67. Thus, the entire split opening / closing die 60 is always attached to the punch side. It is being rushed. In addition, on the front surface of the die case 63, a retaining member 68 for preventing the split opening / closing die 60 from dropping out of the die case 63 is provided.

In the fourth stage forging station S4, the intermediate molding material X3 is driven into the die 6 by the punch 13 as shown in FIGS. Each die member 6 of the split opening / closing die 60 contacts the front surface of the die 60 and is
1 is pushed behind 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 axial center portion of the split opening / closing die 60 is reduced in diameter. 60b is pushed into the second large-diameter hole 63d via the inclined step 63c, and the small-diameter outer peripheral part 60a is pushed into the second large-diameter hole 63e via the inclined step 63b while being reduced in diameter. As the axis of the split opening / closing die 60 is reduced in diameter, the holding portion 6 of the split opening / closing die 60 is
0d and the bulging portion 60e hold the entire periphery of the boundary between the columnar portion a and the spherical head c of the intermediate molding material X3 in a 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, only the columnar portion a is swelled by the upsetting to form a shaft portion e having a predetermined diameter, and at the same time, at the boundary between the shaft portion e and the spherical head c, the shaft portion e Also, the small-diameter neck groove portion f is accurately formed based on the shapes of the embedment portion 60d and the bulging portion 60e of the split opening / closing die 60. At the same time as the formation of the shaft portion e, the fixed die 62 forms a small-diameter shaft portion h having a chamfered portion d at the tip end side of the shaft portion e via the inclined portion f, and the intermediate molding material X4 is formed. Will be.

Then, with the retraction of the punch 13, the formed intermediate forming material X4 is discharged out of the die 6 by the knockout pin 19, and the discharged intermediate forming material X4 is transported to the fifth-stage forging station S5. Will be. Further, as the punch 13 retreats, the split opening / closing die 60 is pressed by the coil spring 66 to the punch side via the pressing member 65, and returns to the original position where it comes into contact with the retaining member 68 as shown in FIG. Will be.

The fifth and sixth forging stations S
Reference numerals 5 and S6 denote a forging station for performing the finishing of the shaft portion e in stages. And the fifth stage forging station S
5 includes a punch 14 having a hemispherical concave portion 14a for holding the spherical head c, and a die 7 having a molded concave portion 7a for performing axial drawing as a finishing step on the columnar portion a. 7 and the intermediate molding material X4
A shaft drawing process is applied to the shaft portion e and the inclined step portion g with a pressing force in a range where the neck groove portion is not deformed, and an intermediate molding material X5 in which the shaft portion e and the small diameter shaft portion h are further shaped is formed. Will be. Further, with the retraction of the punch 14, the formed intermediate forming material X4 is discharged out of the die 7 by the knockout pin 20, and the discharged intermediate forming material X5 is transported to the sixth-stage forging station S6. .

On the other hand, the sixth forging station S6 is
A punch 15 having a hemispherical concave portion 15a for holding the spherical head c, a rear die 8a for axially drawing the shaft portion e, and a front portion for holding a die-side hemispherical concave portion excluding the neck groove f of the spherical head c. And a die 8 composed of a die 8b, and a shaft drawing process is performed on the inclined portion f and the shaft portion e of the intermediate molding material X5 by driving the punch 15 with a pressing force in a range where 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, the taper portion i being continuous with the outer periphery of the shaft portion e, and having a smaller diameter toward the small diameter shaft portion h side, and the length of the small diameter shaft portion h Is formed to a predetermined length, whereby a ball stud B in which the shaft e is finished is formed.

The ball stud B formed with the retreat of the punch 15 is discharged out of the die 8 by the knockout pin 21 and is taken out of the machine base through an appropriate take-out means.

Thus, when a ball stud B having a spherical head c with a neck groove is consistently manufactured from a rod-shaped material by forging, a neck groove f formed between the spherical head c and the shaft e. Without any variation in the dimensions of
The neck groove f can be accurately formed. Also,
From the third-stage forging station to the fourth-stage forging station, a chamfered portion d, a small-diameter shaft portion h, an inclined step portion g, and the like are formed stepwise on the columnar portion a of the intermediate molding material X2 to preform the shaft portion e. Is performed, and a neck groove e is formed thereon.
In the fifth and sixth stage forging stations S5 and S6 downstream of the stage forging station S4, the shaft drawing is further performed stepwise with a pressing force in a range where the neck groove e is not deformed by the punch 14 or 15. The shaft portion e having the tapered portion i and the small-diameter shaft portion h can be formed so that the shape and dimensions thereof are accurate and the structure is dense. In particular, since the shaft portion is finished by a shaft drawing process that has a smaller load on the neck groove portion than the upsetting process, it is possible to effectively suppress the loss of the dimension of the neck groove portion f, The shaft portion e having the portion i and the small diameter shaft portion h can be formed with high precision.

In the embodiment shown in the figure, as shown in FIG.
Extruding pins 22 to 26 are inserted through the shaft center portions of No. to No. 15, so that each material is pushed out from a forming recess of each punch as the punch after processing is retracted, and each of the pushing pins 22 to 26 is pushed out. Coil springs 32 to 36 are interposed between the rear end portions of the load receiving members 27 to 31 and the push pins 22 to 26 are constantly urged toward the die side by the coil springs 32 to 36.

In the above embodiment, the spherical head c is formed in a solid spherical shape. However, the present invention is not limited to the solid spherical head c, but may be a hollow spherical head c. You may.

In this case, as shown in FIGS.
The stage 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 molding material X1 into the die 4 to perform intermediate molding. Material X
The intermediate molding material X2 in which the tip of the punch pin 11b is press-fitted into the large-diameter portion b and the cup-shaped head p is formed.

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

Further, in the above embodiment, the method of manufacturing the ball stud B has been described. However, the present invention is not limited to the method of manufacturing the ball stud B. Of course, it can be applied.

[0033]

As described above, according to the first aspect of the present invention, at a predetermined forging station among a plurality of forging stations, one end of a columnar portion having a smaller diameter than the shaft portion of a shaft-shaped component as a final product is provided. An intermediate molding material having a spherical head formed thereon is formed, and then divided into a plurality of mold members at a forging station downstream of the predetermined forging station, and the opening and closing can be reduced by a punching operation with a punch. Upsetting by driving the columnar portion into a fixed die while holding the entire periphery of the boundary between the columnar portion and the spherical head of the intermediate molding material from a direction orthogonal to the center line of the columnar portion by a 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 smaller in diameter than the shaft portion is formed at a boundary portion between the shaft portion and the spherical head.

As a result, when a shaft-like member having a spherical head with a neck groove is manufactured from a rod-like material by consistently forging, the dimension of the neck groove formed between the spherical head and the shaft is reduced. The neck groove portion can be formed with high precision without causing variation.

According to the second aspect of the present invention, in the forging station downstream of the forging station for forming the neck groove portion, the shaft drawing is performed with a pressing force in a range where the neck groove portion is not deformed by the punch, and the shaft portion is formed. It is possible to form a tapered portion on the distal end side which is continuous with the outer periphery of the shaft portion and has a smaller diameter toward the distal end side as a finishing process. In other words, since the shaft portion is finished by a shaft drawing process that has a smaller load on the neck groove portion than the upsetting process, it is possible to suppress the dimensions of the neck groove portion from being damaged,
The finishing process of the tapered portion or the like can be accurately performed on the shaft portion.

[Brief description of the drawings]

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

FIG. 2 is an explanatory view showing a change in shape of a ball stud manufactured by the same forging machine in a forging order.

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

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

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

FIG. 6 is a sectional view taken along line AA of FIG. 4;

FIG. 7 is a cross-sectional view of a second and third stage forging stations 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 part a columnar part c spherical head e shaft part f neck groove part i taper part S1-S6 heading station

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) B21K 1/44 B21K 27/00 F16C 11/06

Claims (2)

(57) [Claims] 1. A material is sequentially supplied to a plurality of forging stations constituted by a die and a punch opposed to each other, and the material is stepwise forged, so that one end of the shaft portion is formed at one end of the shaft portion more than the shaft portion. A method of manufacturing a shaft-shaped part having a spherical head formed through a small-diameter neck groove portion.First, of the plurality of step-forming stations, at a predetermined forging station, a shaft-shaped part as a final product is manufactured. An intermediate molding material having a spherical head formed at one end of a columnar portion having a smaller diameter than the shaft portion is formed, and then, at a forging station downstream from the predetermined forging station, divided into a plurality of mold members and punched. By the split opening / closing die that can be reduced in diameter by the pushing operation by the above, the entire circumference of the boundary between the columnar portion of the intermediate molding material and the spherical head is held in a direction perpendicular to the center line of the columnar portion. In this state, the columnar portion is driven into the stationary die by upsetting, and the columnar portion is bulged to form a shaft having a predetermined diameter, and at the same time, the shaft is formed at the boundary between the shaft and the spherical head. A method for manufacturing a shaft-shaped part having a spherical head, wherein a neck groove having a smaller diameter is formed. 2. At a forging station downstream of a forging station for forming a neck groove portion, a shaft drawing process is performed on a shaft portion by a punching operation by a punch, and the shaft portion is connected to an outer periphery of the shaft portion at a tip end side of the shaft portion. The method for producing 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 distal end side.