JPH0947838A - Method for forming hollow ball stud - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form the ball head of a ball stud with high precision by forming a recessed part at both ends of a cylindrical base stock, forming a partition wall at a position in the axial direction for forming the ball head, pressing the partition wall so as to bulge out the ball head to the outer circumferential side, and punching out the partition wall to form a through-hole. SOLUTION: First, a steel wire rod is cut in he direction perpendicular to the axial line to form a cylindrical base stock W0; successively, a preliminary base stock W1 is formed by making slightly recessed preliminary holes 2, 3 at both ends of the base stock W0. Then, the one preliminary hole 2 of the preliminary base stock W1 is further extended to the other end side to form one opening W2 into a recessed part 4; continuously, the other preliminary hole 3 is also extended to form a recessed part 5; and a stock W3 with two openings is thereby formed having a partition wall 6 near the center in the axial direction. After that, the partition wall 6 is depressed, and bulged out simultaneously to the outer circumferential side to form an intermediary stock W4 having a ball head 7, so that finally the partition wall 6 of the intermediary stock W4 is punched out to form a through hole 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a hollow ball stud having a substantially spherical ball head and a shaft portion protruding from the ball head.

[0002]

2. Description of the Related Art A ball joint used in a suspension system of an automobile has a structure as shown in FIG. The ball joint 171 is a biaxial type ball joint 171. W104 is a ball stud, which is composed of a spherical ball head 107 and two shaft portions 109 and 109 that coaxially project from the ball head 107. The ball stud W104 has a hollow shape. A cylindrical bearing 73 made of synthetic resin is arranged on the outer peripheral side of the ball head 107 of the ball stud W104, and a metallic cylindrical housing 72 is arranged on the outer peripheral side of the bearing 73. . One end of the boots 74, 74 is directly or indirectly mounted on the inner circumference of the end of the housing 72.
The other end of 4, 74 is the shaft portion 1 of the ball stud W104.
It is attached to the outer circumference of 09,109.

A method of molding the ball stud W104 used in the ball joint 171 will be described with reference to FIGS. 6 to 8.

FIG. 6 shows the ball stud W starting from the material W100.
A molding process for molding 104 is shown. First, a steel wire rod is cut in a direction perpendicular to the axis to form a cylindrical material W100 ((A) in FIG. 6). Next, a preliminary material W101 formed by forming a slightly recessed preliminary hole 102 at one end of the material W100.
(A in FIG. 6) is formed, and subsequently, the preliminary hole 102 is further extended to the other end portion side to form the recess 104, whereby the partition wall portion 106 is formed at the other end portion.
2 ((c) in FIG. 6) is formed. Then, the partition 106
Cylindrical intermediate material W punched out to form through-hole 108
103 ((D) in FIG. 6 is formed, and finally the intermediate material W103
The spherical central portion 107 and the shaft portion 10 that coaxially protrudes from the spherical head portion 107 by bulging the central portion in the axial direction of the
The ball stud W104 made of 9,109 ((e) in FIG. 6) was formed.

In the process of forming the ball stud W104, particularly from the intermediate material W103 to the ball stud W104.
The process of forming the film will be described with reference to FIGS.

FIG. 7 shows a state before forging and FIG. 8 shows a state after forging. First, the configuration of the forging device 110 will be described with reference to FIG. This forging device 110 has a ball stud W at the top.
A static carving space 134 having the same curvature as that of the ball head 107 of 104 and having a substantially lower hemispherical shape is disposed. And a static die 131 provided with a static fixing pin 137, and a dynamic engraving space 114 having a substantially hemispherical shape with the same curvature as the ball head 107 of the ball stud W104 in the lower part. And a movable die 111 having a dynamic fixing pin 117 arranged on the inner circumference of the ring punch 115.

When forging is carried out with this forging device 110,
The intermediate material W103 that has been formed in a cylindrical shape in advance is used as the static engraving space 1
34, and is supported on the upper surface of the knockout ring 135. Then, the moving die 111 is moved forward to advance the ring punch 1
15 is brought into contact with the intermediate material W103, and the moving die 11
1 is moved forward and the ring punch 115 is housed inside the moving die 111. After that, the moving die 111 further advances, the ring punch 115 applies a load to the intermediate material W103, and as shown in FIG.
The ball studs W104 were formed by bulging toward the outer peripheral side along 14,134.

[0008]

As described above, after the cylindrical intermediate member W103 is formed in advance and the ball stud W104 is formed by bulging the vicinity of the center in the axial direction toward the outer peripheral side, as shown in FIG. In addition to the bulging, the extra thickness 199 may bulge out on the inner peripheral side. In this case, the bulge on the outer peripheral side is reduced by the extra thickness 199 protruding on the inner peripheral side, and the ball head 10
There is a case that the thickness of the ball head 107 is reduced and the accuracy of the ball head 107 is lowered.

Therefore, it is an object of the present invention to solve the above-mentioned problems and to provide a method for molding a ball stud with a high precision ball head.

[0010]

The present invention is as follows.

In a method of forming a hollow ball stud having a substantially spherical ball head and a shaft portion projecting from the ball head and having a through hole penetrating in the axial direction, a recess is formed at both ends of a cylindrical material. By molding, an extrusion step of forming a partition wall portion at an axial position for molding the ball head portion, a bulging step of pressing the partition wall portion to bulge the ball head portion toward the outer peripheral side, and a partition wall portion punched through hole And a punching step for molding.

[0012]

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

FIG. 1 shows a ball joint 71 using a ball stud W5 molded according to an embodiment of the present invention. The ball stud W5 has a hollow shape and is made of metal and has a spherical ball head 7 and two shaft portions 9, 9 that coaxially project from the ball head 7. Reference numeral 73 denotes a synthetic resin cylindrical bearing, which is disposed on the outer peripheral side of the ball head 7 of the ball stud W5. The bearing 73 has openings at both ends for projecting the shaft portions 9, 9 of the ball stud W5, has an inner spherical surface 73a having substantially the same curvature as the ball head 7 of the ball stud W5, and has an inner spherical surface 73a of the ball stud W5. The ball head 7 is swingably and rotatably held. Reference numeral 72 denotes a housing having a substantially cylindrical shape and openings at both ends. A retaining ring 75 having a substantially cylindrical shape and extending inward is fixed to the inner peripheral side of one end portion, and the bearing 73 moves in the axial direction. Is regulated. 74 is a substantially cylindrical boot made of a rubber elastic body, both ends of which are open, and an annular collar 76 made of metal and having an L-shaped cross section is embedded in the large opening. The boots 74, 74 are provided between the inner circumference of the retaining ring 75 and the outer circumference of the one handle 9 of the ball stud W5, and between the inner circumference of one end of the housing 72 and the outer circumference of the other handle 9 of the ball stud W5. Are installed respectively.

A method of forming the ball stud W5 used in the ball joint 71 will be described with reference to FIGS.

FIG. 2 shows a forming process for forming the ball stud W5 from the material W0. First, a steel wire rod is cut in the direction perpendicular to the axis to form a cylindrical material W0 ((A) in FIG. 2), and subsequently, preliminary holes 2 and 3 slightly recessed at both ends of the material W0.
A preliminary material W1 (FIG. 2A) formed by molding is formed.
Next, the one-side opening material W2 in which the one preliminary hole 2 of the preliminary material W1 is further extended to the other end side and the concave portion 4 is formed ((C) of FIG. 2)
Both opening materials W3 in which the partition wall portion 6 is formed near the center in the axial direction by forming the concave portion 5 by continuously extending the other preliminary hole 3 of the one-side opening material W2 ((2) in FIG. 2). To form. Thereafter, the partition wall portion 6 is pressed, and at the same time, the partition wall portion 6 is bulged to the outer peripheral side to form the ball head 7, thereby forming an intermediate material W4.
(FIG. 2E) is molded, and finally the partition wall portion 6 of the intermediate material W4 is punched to form the through hole 8 to form the ball stud W5 (FIG. 2F).

Among the forming steps of the ball stud W5, a step of forming the intermediate material W4 from both the opening materials W3 will be described with reference to FIGS. 3 and 4.

FIG. 3 shows a state before forging and FIG. 8 shows a state after forging. First, the configuration of the forging device 10 will be described with reference to FIG. The forging device 10 includes a stationary die 31 and a moving die 11 that is provided to be movable back and forth with respect to the stationary die 31.

The static mold 31 has a ball stud W5 on the top.
The die 32 is provided with a die engraving space 34 having the same curvature as that of the ball head 7 and having a static engraving space 34 into which both opening materials W3 are charged, and a die holder 42 holding the die 32. A knockout hole 33 is provided continuously to the space 34 and penetrating the interior in the axial direction. In the knockout hole 33, a knockout ring 35 and a collar 36 that can slide forward and backward with respect to the static engraving space 34 are arranged, and a static fixing pin 37 fixed by a static pin guide 38 is inserted on the inner periphery thereof. It is fitted. Further, the static pin guide 38 has a knockout hole 33.
A static support pin 41 that is fixed integrally with a static cover 39 that closes the static cover 39 is inserted into the static pin guide 38 and the static cover 39 that are fixed and that penetrates the interior thereof and contacts the collar 36.

The dynamic die 11 has a lower portion of the dynamic die engraving space 1 having substantially the same curvature as that of the ball head 7 of the ball stud W5.
4 and a guide holder 22 that holds the punch guide 12, and the punch guide 12 is provided with a punch hole 13 that is continuous with the moving engraving space 14 and penetrates the inside in the axial direction. . In the punch hole 13,
Ring punch 1 that can slide back and forth with respect to the dynamic engraving space 14
5 and the collar 16 are arranged, and the dynamic fixing pin 17 fixed by the dynamic pin guide 18 is inserted into the inner periphery thereof. Further, the moving pin guide 18 serves as the moving cover 1 for closing the punch hole 13.
9 is integrally fixed to the movable pin 9 by a bolt 20, and a dynamic support pin 21 that penetrates the inside and abuts the collar 16 is inserted into the fixed dynamic pin guide 18 and the dynamic cover 19. The ring punch 15 projects from the end surface of the punch guide 12 before forming, and the collar 16 and the moving pin guide 18 also move to the dynamic engraving space 14 side following the ring punch 15.

When forging is performed by the forging device 10, both opening members W3 having an H-shaped cross section, in which the recesses 4 and 5 are previously formed at both ends.
Is put into the static engraving space 34 of the static die 31, and is supported by the upper surface of the knockout ring 35. Then, the moving die 11 is moved forward to bring the ring punch 15 into contact with both openings W3, and the moving die 11 is moved forward to house the ring punch 15 inside the moving die 11. Instead of the ring punch 15 housed at this time, the tip of the moving fixing pin 17 is
The partition wall portion 6 of both opening materials W3 is sandwiched and pressed between the static fixing pin 37 and the dynamic fixing pin 17 by projecting from the tip end, and the excess thickness bulges in the static engraving space 34 and the dynamic engraving space 14 on the outer peripheral side. hand,
As shown in FIG. 4, an intermediate material W4 for molding the ball head 7 is formed. After that, the moving die 11 is retracted, and the knockout ring 35 is moved by the static support pin 41 so that the static die space 34
The intermediate material W4 protruding to the side is taken out from the static mold 31, and the molding in this step is completed.

Therefore, the static fixing pin 37 and the dynamic fixing pin 17
Since the partition wall portions 6 of both the opening members W3 are sandwiched and pressed between and, the excess thickness can be easily bulged in the static engraving space 34 and the dynamic engraving space 14 on the outer peripheral side by a predetermined amount.

In the above embodiment, the molding method has been described by taking the biaxial type ball stud W5 as an example, but the present invention is not limited to such a biaxial type ball stud W5, and FIG. As shown in, a single-axis type ball stud W6 may be used. In this case, the partition wall portion is formed at the end of the shaft, and after the ball head 97 is formed, the partition wall portion is punched out and the through hole 98 is formed.
Is molded.

[0023]

As described above, according to the present invention, a hollow ball stud having a substantially spherical ball head and a shaft portion protruding from the ball head and having a through hole penetrating in the axial direction is formed. In the method, an extrusion step of forming recesses at both ends of a cylindrical material to form partition walls at axial positions for molding the ball head, and pressing the partition wall to expand the ball head to the outer peripheral side. Since it consists of an overhanging process of projecting and a punching process of punching the partition wall to form a through hole, the surplus wall of the partition wall bulges to the outer peripheral side by a predetermined amount, so the ball head of the ball stud is molded with high accuracy. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional plan view of a ball joint using a ball stud molded by a molding method according to an embodiment of the present invention.

FIG. 2 is a sectional plan view showing a molding process of a ball stud according to an embodiment of the present invention.

FIG. 3 is a sectional plan view showing a state before an intermediate material is molded from both opening materials according to the embodiment of the present invention.

FIG. 4 is a cross-sectional plan view showing a state after molding an intermediate material from both opening materials according to the embodiment of the present invention.

FIG. 5 is a sectional plan view showing a ball stud according to another embodiment of the present invention.

FIG. 6 is a cross-sectional plan view showing a conventional ball stud forming process.

FIG. 7 is a cross-sectional plan view showing a state before molding a ball stud from a conventional intermediate material.

FIG. 8 is a cross-sectional plan view showing a state after molding a ball stud from a conventional intermediate material.

9 is an enlarged view of a main part of FIG.

[Explanation of symbols]

 4 Concave part 5 Concave part 6 Partition part 7 Ball head 8 Through hole 9 Shaft part W0 material

Claims (1)

[Claims] 1. A substantially spherical ball head (7) and the ball head (7)
In a method of forming a hollow ball stud having a through hole (8) penetrating in the axial direction, which has a shaft portion (9) protruding from the recessed portion (4) at both ends of a cylindrical material (W0),
An extrusion step of forming the partition wall portion (6) at an axial position where the ball head (7) is formed by forming (5);
A step of pressing the partition wall (6) to bulge the ball head (7) to the outer peripheral side, and a punching step of punching the partition wall (6) to form a through hole (8). A method of forming hollow ball studs.