JPH0688096B2 - Ball stud manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for cold forging a ball stud used for a ball joint of an automobile or the like.

(Conventional Example) Conventionally, a ball stud manufactured by the cold forging method is manufactured in the process shown in FIG. 4, for example.

Explaining this manufacturing process, first, as shown in FIG. 3A, the screw forming portion 2, the hanging shaft portion 3, the inferior neck shaft portion 4, and the ball portion 5 having the burr portion 5a are formed by extrusion molding. The intermediate molded product 1 which it has is manufactured by the cold forging method, and then this intermediate molded product 1
(B) of the circular shaft part 3, the inferior neck shaft part 4 and the ball part 5 of FIG.
As shown in (c) and (d), the lower neck shaft portion 4, the collar portion 4a and the ball portion 5 having predetermined dimensions are formed by cutting with a cutting tool 6, respectively.

(Problems to be Solved by the Invention) However, in such a conventional manufacturing method,
Since the shape of a predetermined size is obtained in the cutting process, it takes time to manufacture, and it is difficult to maintain accuracy because each cutting process is performed separately. More material loss,
Further, there is a problem that automation becomes difficult and hinders improvement in productivity.

(Means for Solving the Problem) The present invention has been made in view of such problems,
The purpose of the present invention is to provide a method for manufacturing a ball stud that can reduce the processing man-hours and improve the processing accuracy. To achieve this purpose, a diameter that is almost equal to the diameter of the ball portion of the ball stud at the time of completion is set. A columnar material having a volume substantially equal to the entire volume of the ball stud at the time of completion is formed, and then by extrusion molding, a screw forming portion, a drooping shaft portion, and a lower neck shaft portion in order from one end of the columnar material. And the ball, and then
The spherical portion is hermetically sealed with the spherical portion by a spherical split mold configured so as to seal the spherical portion when integrally connected and to provide an annular space around a predetermined position of the lower neck shaft portion. While holding the shaft portion and the screw forming portion, punch forming is performed in the axial direction to enlarge the collar portion on the lower neck shaft portion to form the spherical portion and the lower neck shaft portion without cutting. The technical point is to be able to do it.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing the shape of each ball stud manufactured in this embodiment in each manufacturing step. First, in FIG. 1 (a) showing the first step, a ball stud at the time of completion is shown. A cylindrical material having a volume substantially equal to the total volume and having a diameter substantially equal to the diameter of the spherical portion of the ball stud described later.
Form 10 by cutting.

In the second step shown in FIG. 2B, the screw forming portion 11 and the tapered conical shaft portion 12 are formed from one end by a so-called cold forging method.

In the same figure (c) showing the third step, a columnar lower neck shaft portion 13 and a spherical portion forming portion 14 are further formed by the cold forging method to the other end side by the cone shaft portion 12. To do.

In FIG. 4D showing the fourth step, the peripheral end face of the ball portion forming portion 14 is formed into a barrel-like curved surface by the cold forging method and the end face is corrected.

Next, in the step of FIG. 5, as shown in FIG. 5 (e), the spherical portion forming portion 14 is press-molded by a cold forging method to form a spherical spherical portion 15 having a predetermined diameter.

Next, in FIG. 6 (f) showing the process of FIG. 6, a flange-shaped collar portion 17 is formed at a predetermined position of the lower neck shaft portion 13 by a cold forging method.

2 and 3 are sectional views showing the construction of a cold forging device for molding the collar portion 17 on the lower neck shaft portion 13 in FIG. 1 (f).

First, referring to FIG. 2, the structure of the cold forging device will be described.
A fixed die 110 is fixed in the die case 100, and a fitting hole 110a for fixing and holding the screw forming portion 11 and the conical shaft portion 12 of the intermediate molded product molded in FIG. 1 (e) is provided.
The knock pin 120 is inserted from the side of the screw forming portion 11. A punch 140 is fixed to a punch case 130 arranged so as to move in the hollow portion of the die case 100, that is, opposite to the fixed die 110. Further, punches 160, 170 divided in two are slidably attached to a tapered inner peripheral surface 130c provided on the fixed die 110 side of the punch case 130, and the punches 140, 160, 170 constitute a split mold. ing. The punch 140 has an axially formed 140a of an intermediate molded product, and a punch pin 150 slidably provided in the hole 140a comes into contact with one end of the ball portion 15. In addition, a concave curved surface 140b that is equal to the spherical curved surface of the spherical portion 15 is formed on the punch 140 so as to face the spherical portion 15.

On the other hand, a concave curved surface 160a, 170a equal to the spherical curved surface shape of the spherical portion 15 is formed at the end of the punch 160, 170 on the spherical portion 15 side, and a semi-circular groove portion is formed at one end facing the inferior neck shaft portion forming portion 13. 160b, 170
b is formed.

That is, when the punches 160 and 170 are combined together, the space portion forming the spherical portion 15 shown in FIG. 1 (f) becomes concave portions 160a and 170a.
In addition to the above, the semi-arcuate groove portions 160b and 170b forming the collar portion 17 are formed, and the spherical surface can be sealed by the concave curved surfaces 160a and 170a and the concave curved surface 150a of the punch 150. It has become.

Next, referring to FIG. 3, the manufacturing process of the ball stud shown in FIG. 1F will be described. First, the intermediate molded product shown in FIG. And cone shaft
12 and the under-neck shaft portion 13 are held in the fitting hole 110a, and the punch 140 is moved to the ball portion 15 side integrally with the punch case 130 from the left side of FIG. At this time, since the contact surfaces of the punch case 130 and the punches 160 and 170 are in contact with each other by tapered surfaces, the punch cases 130 and 170 are moved as the punch case 130 moves.
Move to the side of the spherical part 15 and the concave curved surfaces 160a and 170a
Sticks to the ball 15. With the ball portion 15 being further sealed, the punches 140, 150, 160, 170 are moved until they come into contact with the fixed die 110, and punching is performed. The surplus portion generated by this punching overhangs the groove portions 160b, 170b, as shown in FIG. 1 (f). A flange portion 17 having a simple flange shape is formed.

In this way, as shown in FIGS. 2 and 3, since the collar portion 17 is formed in the lower neck shaft forming portion 13 by so-called overhang molding, conventional cutting work is not required, and therefore, Since there is no material loss and the punches 160, 170 having a predetermined shape are used for integral molding, the molding time can be shortened and the molding accuracy can be improved.

(Effects of the Invention) As described above, according to the present invention, the lower neck portion of the intermediate molding member for molding the ball stud is sealed with the spherical split type punch while punching and overhanging to form the neck. Since the collar portion is integrally formed on the lower shaft portion, the time required for manufacturing can be shortened, and machining is not required after cutting and the like, so that productivity can be improved. In addition, since there is no need for cutting out due to cutting or the like, processing accuracy is high, and there is no material loss, and manufacturing can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a manufacturing process in an embodiment of the present invention, and FIG. 2 is a sectional view showing an essential part of a cold forging device used for manufacturing the ball stud shown in FIG. 1 (f). 3 is the second
FIG. 4 is an explanatory view showing the operation of the cold forging device shown in FIG. 4, and FIG. 4 is an explanatory view showing a conventional ball stud manufacturing process. 10: Cylindrical material 11: Screw forming part 12: Conical shaft part 13: Under neck shaft part 14: Sphere forming part 15: Sphere part 17: Collar part 140,160,170: Punch 140b, 160a, 170a: Recessed curved surface 160b, 170b: Groove

Claims (1)

[Claims] 1. A method of manufacturing a ball stud by a cold forging method, which is a cylinder having a diameter substantially equal to a diameter of a ball portion of the completed ball stud and having a volume substantially equal to a total volume of the completed ball stud. The process of forming the material, and the process of forming the thread forming part, the conical shaft part, the inferior neck shaft part and the ball part in order from one end of the columnar material by extrusion molding. The spherical portion and the lower neck shaft portion are hermetically sealed by a spherical split die configured to provide an annular space around a predetermined position of the lower neck shaft portion, and the pendular shaft portion and the screw forming portion are sealed. A method of manufacturing a ball stud, comprising a processing step of punch-molding in the axial direction while holding, and enlarging and molding a flange portion on the lower neck shaft portion.