JP2511682B2 - Stud manufacturing method for stud welding - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a novel method for manufacturing studs for stud welding, and more particularly, to efficiently manufacture two studs at a time from a rod having a short columnar shape. Regarding the method.

[Prior Art] As is well known, stud welding is a method of welding a stud made of a metal material to a base material by heat generated by arc discharge. To briefly describe an example of the method, first, the stud and the base metal are brought into contact with each other, then the welding gun is energized to the stud, and then the stud is separated from the base metal to cause an arc discharge between the two members. The part is melted to form a molten pool. Next, after stopping energization, both members are welded by rapidly pressing the stud against the molten pool. As another method, the capacitor of the welding machine is once charged, the iron stud is pressed against the surface of the base material, and the electric charge of the capacitor is momentarily discharged to weld the iron stud and the base material. There is a way. Furthermore, in the case of an aluminum stud, the electric charge in the capacitor is instantaneously discharged while the space between the base material and the tip of the stud is slightly held, and the aluminum stud is supported by the elastic force of the spring. There is a method of pressing the material and welding between the two.

As a stud used in such a stud welding method, a cylindrical stud having an electrode tip on the bottom is often used. An inner screw is often formed on the cylindrical inner wall. The electrode tip constitutes the tip of the stud and is provided to facilitate the initiation of arc discharge.

A conventional method of manufacturing a stud having such a structure is to cut a metal rod into a predetermined length, make an axial hole from one end face of the metal rod, and integrally cut an electrode tip at the center of the bottom. The method of processing or providing by embedding separately is adopted.

[Problems to be solved by the invention]

However, such a conventional stud manufacturing method requires a troublesome cutting process for making a hole in a bar, and also requires such a process for each stud, which requires man-hours. There was a problem of low productivity. This problem has been especially acute when mass-producing relatively small studs.

It is an object of the present invention to solve the problems of the conventional stud manufacturing method and to provide a highly productive manufacturing method.

[Means for solving problems]

In the method for manufacturing a stud for stud welding according to the present invention, a pair of recessed portions are axially formed from both end surfaces of a rod-shaped rod material by pressing, and then the pair of recessed portions of the rod material does not reach. The undepressed portion is cut in the radial direction so as to be separated into two cylindrical stud bodies each having a closed bottom portion, and an electrode tip portion is provided outside the bottom portion of each of the main bodies. Is the way.

Here, the short column is a column having a relatively short length,
It refers to a column having a length sufficient to manufacture two desired studs, and the column includes not only a column but also an elliptic column, a polygonal column, and the like.

In addition, the forging means that the material is deformed by applying pressure from the outside and is molded into a predetermined shape.

According to a preferred embodiment of the present invention, the concave portion has a circular cross-sectional shape, and an inner thread is formed on the inner peripheral surface thereof. This form of stud can be joined to other members by screwing.

[Examples and functions]

Next, an embodiment of the stud manufacturing method of the present invention will be described with reference to the drawings.

FIG. 2 is a perspective view showing an example of a short rod material used in the method of the present invention. The rod 1 has a columnar shape, and its length is previously cut to a length sufficient to manufacture two studs. The material of the rod 1 is, for example, a metal or alloy such as S / S steel, stainless steel, copper, or brass according to the purpose of use of the stud, but the material selection is to have forgeability so that it can be pressed. Needed above.

FIG. 3 is a cross-sectional view showing an example of a state in which a bar is incorporated in a forging device. A well-known forging machine can be used, and only necessary parts are shown in the drawings and other parts are omitted. The forging die 2 has an inner diameter into which the rod 1 can be inserted, and has a cylindrical space portion 3 having both ends opened. A pair of forging punches 4 are coaxially opposed to each other at both ends of the space 3. A forging plug 5 is provided at the tip of the forging punch 4. The shape and size of the forging plug 5 are made in conformity with the inner surface shape of the recessed portion formed in the stud, but when forming the recessed portion provided with the internal screw, it is formed into a cylindrical shape.

The pair of forging punches 4 are synchronously driven by a driving device (not shown). As the driving device, a pressing force or striking force generating device by fluid pressure, electromagnetic force, explosive force or other mechanical force known in this field can be used.

Next, a method of forming a stud body by using this forging device will be described. First, as shown in FIG. 3, the short columnar bar 1 is inserted into the space 3 of the forging die 2, and then the driving device of the forging device is activated to move the pair of forging punches 4 at a constant speed in the arrow direction. Or it is driven instantaneously. By driving the forging punch 4, the tip portion of the forging plug 5 presses or strikes both end surfaces 6 of the bar material 1, and as shown in FIG.
A pair of recesses 7 are formed in the axial direction. Forging plug 5
The drive stroke of (1) is set so that both recessed portions 7 do not communicate with each other, and an undepressed portion 8 that does not reach is left. The axial length of the undepressed portion 8 is set to a dimension that allows the stud bottom portion, which will be described later, to be sufficiently processed.

FIG. 5 shows a cross section of the bar 1 that has been press-formed by the press device in this manner. Next, the rod 1 is radially cut at the position of the undepressed portion 8. The cutting can be performed by cutting or cutting with a lathe or a rotary cutting machine.

FIG. 1 is a sectional view showing a state in which two studs 9 are formed by cutting in this way. As shown in FIG. 1, the stud 9 is composed of a stud body 11 having a closed bottom portion 10 and an electrode tip portion 12 integrally provided outside the central portion of the bottom portion 10. The two studs 9 are shown in contact with each other at the tip end surface of the electrode tip portion 12, but this facilitates understanding of how these studs 9 are formed from the state of FIG. Of course, the two studs 9 are cut and separated from each other at the tip end surface of the electrode tip portion 12.

In the example of FIG. 1, the outer surface of the bottom portion 10 is formed in a tapered shape, but this does not necessarily have to be a tapered shape, and may be a flat surface.

FIG. 6 shows an example in which an inner threaded portion 13 is formed on the inner peripheral surface of the recessed portion 7 of the stud 9 shown in FIG. 1, if necessary.

7 and 8 are sectional views showing another embodiment of the method of the present invention. FIG. 7 shows that two stud bodies 11 are cut and separated from the state of FIG. 5, an internal thread portion 13 is formed on the inner peripheral surface of the recessed portion 7, and the outer surface of the central portion of the closed bottom portion 10 is formed. FIG. 8 shows a state where the fitting hole 14 is formed from the above, and FIG. 8 shows a state in which the separately prepared electrode tip portion 12 is fitted into the fitting hole 14 of FIG.

〔The invention's effect〕

According to the method of manufacturing a stud for stud welding of the present invention, two studs can be easily manufactured at one time from a short columnar bar material by using the above-described structure, and compared with the conventional manufacturing method. The productivity can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which two studs 9 manufactured in one embodiment of the method of the present invention are arranged in contact with each other at the tip surfaces of their electrode tip portions 12, and FIG. 2 is a method of the present invention. Fig. 4 is a perspective view showing an example of a short columnar bar material used in Fig. 3, Fig. 3 is a cross-sectional view showing an example of a state where the bar material is incorporated in a forging device for carrying out the method of the present invention, Fig. 4 Is a cross-sectional view showing a place where a recessed portion 7 is formed in the bar 1 by driving the forging punch 4 in FIG. 3, and FIG. 5 is a cross-sectional view of the bar 1 molded as shown in FIG. FIG. 6 is a sectional view showing an example in which an inner threaded portion 13 is formed on the inner peripheral surface of the recessed portion 7 of the stud 9 shown in FIG. 1, and FIGS. 7 and 8 are other embodiments of the method of the present invention. FIG. 1 ... Bar material, 2 ... Pressing die 3 ... Space part, 4 ... Pressing punch 5 ... Pressing plug, 6 ... End face 7 ... Recessed part, 8 ... Undepressed part 9 ... Stud, 10 …… Bottom 11 …… Stud body, 12 …… Electrode tip 13 …… Inner screw, 14 …… Mating hole

Claims (1)

(57) [Claims] 1. A pair of recessed portions (7) are axially formed from both end surfaces (6) of a short columnar rod (1) by forging, and then the pair of recessed portions of the rod (1) is formed. The undepressed part (8) which the concave part (7) does not reach is separated into two cylindrical stud bodies (11) having a closed bottom part (10) by being cut in the radial direction, and each said main body. A method for manufacturing a stud for stud welding, characterized in that an electrode tip portion (12) is provided outside the bottom portion (10) of (11).