JPS632697B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing ball studs by cold forging, which are used for various vehicles such as automobiles and other mechanical parts.

Conventional cold-forged ball studs absorb the volumetric error of the rough material by creating a convex part on the circumference near the center of the ball, resulting in poor ball accuracy.The convex part is removed by machining and the ball is roughened. After that, it was finished with spherical rolling. In other words, there is a preforming process for the sphere before the ball forming process to reduce the deformation resistance, but the difference between the preforming heading load of the sphere and the ball forming heading load is large, and the same heading machine cannot apply the appropriate amount of force. The inability to obtain pressure results in a lack of accuracy, and the forging process also requires multiple steps, including cutting the rough material. The present invention is an improvement and modification of the conventional method for the purpose of simplifying the process and ensuring improved molding accuracy.

That is, the present invention provides a method for cold forging ball studs, including the step of cutting a blank material having approximately the same volume as a completed ball stud and an outer diameter approximately the same as the shaft diameter of the ball stud; This process consists of a step of forming a warped portion, a tapered portion, and a substantially hemispherical shape by forward extrusion and upsetting, and a step of providing a concave portion following the hemispherical portion and forming the tip portion into a hemispherical shape.

As mentioned above, in the past, the volume error of the rough material A was absorbed by creating a circumferential convex part 5 near the center of the sphere, and the convex part was removed by machining, and the spherical surface was rolled after rough machining. (Figs. 1 to 4 are shown as examples according to the order of the manufacturing process), but the method of the present invention is performed in steps 5, 6,
As sequentially illustrated in FIG. 7, it is similar to the conventional method to precede the cutting process of the rough material A having approximately the same volume as the completed ball stud and approximately the same outer diameter as the shaft diameter of the ball stud. By forward extrusion and upsetting, the threaded diameter portion 1 and tapered portion 2 of the raw material A are formed by forward extrusion, and at the same time, an approximately hemispherical shape 3' is upset formed. Next, by forming a recess 4 and shaping the tip into a hemisphere, the recess 4 can absorb errors in the rough material during machining, making it possible to reduce the spherical surface area and uniformizing the deformation resistance during the process. As a result, the applied force can be optimized and accuracy can be ensured.

As described above, the present invention eliminates the need for preliminary machining, greatly simplifies the process, performs forward extrusion processing and natural upsetting processing, and optimizes the pressing force to reduce the forging process and reduce the ball forming process in the final process. Later, the accuracy of the ball was improved and mass production was possible as a cold-forged ball stud, which would meet the rationalization objective from a cost standpoint.

[Brief explanation of the drawing]

Figures 1 to 4 sequentially illustrate the conventional cold forging method. The figure shows the rough material, Figure 6 shows the molded view of the shaft side head, and Figure 7 shows the completed view. A... Rough material, 1... Thread diameter portion, 2... Tapered part, 3'... Almost hemispherical part, 3... Hemispherical part,
4... Concavity.

Claims (1)

[Claims] 1. A step of cutting a blank material having approximately the same volume as the finished ball stud and an outer diameter approximately the same as the shaft diameter of the finished ball stud;
A ball stud comprising the steps of forward extrusion molding the tapered part and upsetting the hemispherical part at the same time by upsetting the hemispherical part, and forming a concave part following the hemispherical part and molding the tip part into a hemispherical part. Cold forging method.