JPS6138730A - Under neck working method of ball stud head - Google Patents

Abstract

PURPOSE:To reduce an equipment cost and work cost with simple equipment and to improve a working accuracy by forming a cylindrical part of the under neck of the head of a form rolling ball stud work in a recessed peripheral shape with the form rolling of a roll die. CONSTITUTION:A forged ball stud work is supported freely rotatably by a form rolling device and a form rolling work is started with pressing a pair of roll dies 14, 15 as shown by an arrow mark to the cylindrical part 3a of the under neck of a head with rotating reversely each other and with moving to the side of the ball stud work. The plastic deformation of the cylindrical part 3a of the under neck of the head is performed with the rotation of the ball stud work as well by the pressing of the roll die 14 thereof. The form rolling work shape of the cylindrical part 3a of the underneck of the head coinciding with the peripheral ends 14a, 15a of the rolling dies 14, 15 is made out. When this working condition is obtd. the feeding of the rolling die 14 is stopped and by keeping it for a fixed time the uniform plastic deformation of the head underneck 3 is obtd. over the whole periphery and the underneck work is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for processing the underneck of a ball stud head used in a ball joint for an automobile or the like.

(Prior Art) Conventionally, as a method for processing the neck of a ball stud head, there is a method as shown in FIG. 7, for example.

In FIG. 7, 1 is a ball stud, which is equipped with a spherical head 2, a lower head and neck 3, a tapered shaft portion 4, and a threaded portion 5, and is a ball stud workpiece formed into a specified shape by cold forging. The tip or cutting tool 7 is fixed to the jack 9 and rotated in a restrained manner, and the lower part of the head and neck 3 is attached to the cutting tool stand 6.
We use a cutting method.

(Problems to be Solved by the Invention) However, in this conventional method for machining the head and neck by cutting, equipment costs and processing costs are high ( However, there is a problem in that the chips generated during under-neck cutting become entangled in the under-neck machining section, shortening the tool life, and furthermore, since it is a cutting process, the cost of materials increases by the amount of material removed. Ta.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and it is possible to reduce machining costs, reduce material II costs, and improve machining accuracy. The purpose is to provide a method for machining the underneck of the head, and to achieve this purpose, the ball stud work is sequentially fabricated by cold forging into a spherical head, a cylindrical portion under the neck, a tapered shaft portion, and a threaded cylindrical portion. The head and neck cylindrical portion of this forged ball stud workpiece is formed into a concave peripheral shape by rolling with a roll die.

(Example) Fig. 1 shows a state in which a ball stud work is attached to a rolling device in the underneck processing method of the present invention, and Fig. 2 shows a plan view thereof.

First, the configuration of an apparatus for realizing the under-neck machining method of the present invention will be described. Reference numeral 10 denotes a ball stud for which under-neck machining has been completed, including a spherical head 2, a head under-neck 3, a tapered shaft portion 4, and a threaded cylinder. It has a prescribed shape including portions 5a in sequence. This ball stud 10 is manufactured in a pre-process before neck processing.
By cold forging, it has a shape as a ball stud work which sequentially includes a head 2, a cylindrical part 3a below the head and neck, a tapered shaft part 4, and a threaded cylindrical part 5a. The threaded cylindrical portion 5a and the 202 spherical heads are supported from below by support blades 11.12, and a stopper 13 is attached to the tip of the spherical head 2 from the axial direction.
Position the ball stud workpiece by touching the ball stud.

For the ball stud work set as shown in Fig. 1, as is clear from the plan view of Fig. 2,
A pair of roll dies 14. ．． 15 are arranged, and the peripheral ends 14a of the roll dies 14, 15,
The shape of 15a is adapted to the shape of the head and neck 3 to be processed and formed.

Next, the processing method of the present invention will be explained in order of processing.

First, a ball stud workpiece is formed by cold forging into a prescribed shape in which the spherical head 2, the lower neck cylindrical portion 3a, the lever shaft portion 4, and the threaded cylindrical portion 5a are sequentially formed.

Subsequently, as shown in FIG. 1.2, the ball stud workpiece which has been subjected to the @-forming process is rotatably supported on the rolling device by the supporting blades 11, 12 and the stopper 13. In this set state of the ball stud work, the pair of roll dies 14 and 15 shown in FIG. Press to start rolling process. Due to this pressing of the roll die 14, the ball stud workpiece is also rotated, and the head and neck lower cylindrical portion 3a is plastically deformed, and the peripheral end 14a of the roll die 14.15.

A rolled shape of the head and neck lower cylindrical portion 3a corresponding to 15a is created, and when this processed shape is 1q, the feed of the roll die 14 is stopped and held for a certain period of time to make it uniform over the entire circumference. Plastic deformation of the head and neck lower part 3 is obtained, and the neck lower part machining is completed.

Fig. 3 shows another embodiment of the present invention, in which a flange is formed integrally with the large-diameter end of the tapered shaft extending below the head and neck by rolling. It is characterized by

That is, as shown in FIG. 3, when a pair of roll dies 14 and 15 are pressed against the head and neck lower cylindrical portion 3a of the ball stud work 10a obtained by cold forging, the spherical head 2
The roll dies 14° 15 are positioned so as to provide a predetermined gap 16 between the end near the head and neck lower cylindrical portion 3a and the roll die 14.15, and with this gap 16 set, the roll die 14.15 When the head and neck lower cylindrical portion 3a is rolled, the gap 16 on the spherical head 2 side is filled with plastic deformation due to the pushing of the roll die 14. As a result, as shown in FIG. 4, the flange 17 can be integrally formed on the large diameter end of the tapered shaft section 4 at the same time as the under-neck processing by rolling processing. . This collar portion 17 is used to lock one end of the dust cover when the ball stud is assembled into the ball joint via the bearing seat.

FIG. 5 shows another embodiment of the present invention. In this embodiment, the cylindrical part under the head and neck is rolled using a roll die, so that the flange is not integrally formed on the tapered shaft side. It is characterized by a continuous shape that gently continues from the bottom of the radical to the tapered shaft part.

That is, as shown in FIG. 5, in processing and forming the ball stud workpiece 10a by cold forging, the diameter of the tapered shaft portion 4 side of the head and neck lower cylindrical portion 3a is formed to be slightly smaller. That is, the diameter D of the head and neck lower cylindrical portion 3a
1, the tapered shaft portion 4 side is stepped down to a slightly smaller diameter, D2.

Ball stud work 10 with such a stepped shape
A pair of roll dies 14.1
When the rolling process is performed in Step 5, the large diameter side of the tapered shaft portion 4 is slightly
Even if the meat bulges due to plastic deformation due to the small diameter, the under-neck rolled shape continues gently from the under-neck part 3 towards the tapered shaft part 4 as shown in Fig. 6. can be obtained.

(Effects of the Invention) As described above, according to the present invention, a ball stud workpiece is formed into a spherical head by cold forging.

The cylindrical part under the neck, the tapered shaft part, and the threaded cylindrical part are sequentially formed into a prescribed shape, and the cylindrical part under the head neck of this rolled ball stud work is processed and formed into a concave circumferential shape by rolling with a roll die. As a result, the equipment configuration is simpler than conventional machining under the cutting head, which required a copying device. In addition, since the plastic deformation is caused by rolling, the material can be used more effectively than the conventional underhead processing by cutting and removing, reducing equipment costs and processing costs, and it is a T for rolling. Therefore, the machining accuracy is higher than that of cutting, and the machined surface under the head and neck can be finished neatly.

Furthermore, the flange can be formed on the tapered shaft side at the same time as the rolling process, and ball studs that require a flange on the large diameter part of the tapered shaft can be created only by the rolling process below the neck. This allows for a significant reduction in the number of processing steps compared to the case where the flange is processed and formed separately.

Furthermore, if you want to prevent the meat from swelling up at the flange, by forming the tapered shaft side of the cylindrical part under the head and neck into a slightly smaller diameter during cold forging, the taper shaft can be removed from under the head and neck. It is possible to obtain a machined shape under the neck that is gently connected to the part,
Since it is not necessary to remove the bulge of meat produced by the rolling process by cutting or the like, it is possible to reduce the number of processing steps and save materials at the same time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the set state of the ball stud in the rolling process of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. An explanatory diagram showing an example of the above, and Fig. 4 is a cross-sectional view of the ball stud obtained by the rolling process shown in Fig. 3.
Fig. 5 is an explanatory diagram showing another embodiment of the present invention for gently connecting the ball stud from the bottom of the head and neck to the tapered shaft portion, and Fig. 6 is a ball stud obtained by the rolling process shown in Fig. 5. FIG. 7 is an explanatory view showing a conventional under-neck processing method. 2: Spherical head 3: Head lower neck 3a: Head lower neck cylindrical portion 4: Tapered shaft portion 5: Threaded portion 5a: Threaded cylindrical portion 10: Ball stud 10a: Ball stud work 11.12: Support blade 13 : Stopper 14.15: Roll die 16: Gap 17: Flange part 0 is d Fig. 5 $ 0 12N Fig. 4 17'H part Fig. 6

Claims (3)

[Claims] (1) A ball stud workpiece is formed into a prescribed shape having a spherical head, a cylindrical part under the neck, a tapered shaft part, and a threaded cylindrical part sequentially by cold forging, and the cylindrical part under the head and neck of the forged ball stud work is formed. A method for processing the underneck of a ball stud head, characterized by processing and forming the ball stud head into a concave peripheral shape by rolling with a roll die. (2) The rolling process using the roll die is performed by forming a predetermined gap between the end face of the roll die and the head end of the ball stud workpiece near the cylindrical part under the neck, thereby forming the tapered shaft part of the ball stud. 2. The method for processing the underneck of a ball stud head according to claim 1, wherein a flange is simultaneously molded on the large diameter end. (3) In the processing and forming of the ball stud work by cold forging, the tapered shaft part of the cylindrical part under the head and neck is formed into a slightly smaller diameter, and the part formed under the neck is formed by the rolling process using the roll die. 2. The method for processing a ball stud head under the neck according to claim 1, wherein the under-neck rolling shape is loosely connected to the tapered shaft portion.