JP2888410B2 - Screw hole processing method - Google Patents

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 screw hole, and more particularly to a method for forming a circular hole in a plate-like body, and forming a boss by plastically processing a portion around the circular hole. The present invention relates to a method for forming a screw hole in which a female screw is formed on the inner peripheral surface of the screw hole.

[0002]

2. Description of the Related Art An air tank for filling air compressed by a compressor is made of a steel plate. A female screw is inserted in a predetermined position of the air tank to connect a portion to which a pipe for filling the air compressed by the compressor is connected and an air pipe for guiding the compressed air filled in the air tank to a predetermined portion. And a male thread of a pipe or a joint is screwed into the connection to perform the connection.

In order to form a connecting portion for connecting such pipes or joints, conventionally, as shown in FIG. 7, a circular plate is formed at a predetermined position on a plate 1 made of a steel plate for manufacturing an air tank. The hole 2 is formed in advance, and the portion where the circular hole 2 is formed is subjected to plastic working (burring) using a punch die, thereby forming a boss 4 having a through hole 3 in the center as shown in FIG. I was trying to do it. Then, as shown in FIG. 9, a female screw 5 is formed on the inner peripheral surface of the boss 4, and a male screw formed on the outer peripheral surface of a pipe or joint connected to the female screw 5 is screwed.

As another method of forming the connecting portion, as shown in FIG. 10, a boss 8 having a through hole 7 is manufactured in advance by another member, and this boss 8 is formed into a circular hole 2 as shown in FIG. The plate-like body 1 is attached by welding.

[0005]

In the case of burring as shown in FIGS. 7 to 9, the thickness of the boss 4, that is, the boss 4 in which the female screw 5 is formed on the inner peripheral surface as shown in FIG. There was a problem that the value of the wall thickness t became small, and the portion of the boss 4 did not have sufficient strength. When the wall thickness t of the boss 4 is small, the boss 4 is deformed by screwing a male thread portion on the tip side of the pipe or the joint, and sufficient mechanical strength cannot be obtained, thereby impairing the airtightness of the air tank. There was a problem.

As shown in FIG. 10 and FIG.
A boss 8 made of a separate member having
According to the method of forming the female screw 5 on the inner peripheral surface of the through hole 7 of the boss 8, a welding step is required, which has a drawback that the production is complicated and the cost is increased. Further, if welding is not performed uniformly over the entire periphery of the root portion of the boss 8, there is a problem that an airtight defect occurs in which air leaks from the welded portion.

The present invention has been made in view of the above problems, and provides a method of forming a screw hole which is easy to manufacture and has a sufficient strength at a portion where the screw hole is formed. The purpose is to do so.

[0008]

According to the present invention, a circular hole is formed in a plate-like body, a boss is formed by plastically processing a portion around the circular hole, and a female screw is formed on an inner peripheral surface of a through hole of the boss. In the method of processing a screw hole so as to form, the plastic processing is performed in a state where a boss of the plate-shaped body is formed to protrude and a reinforcing ring is applied around the circular hole,
The present invention relates to a method for processing a screw hole, wherein the reinforcing ring is combined with an outer peripheral side of the boss.

[0009]

The boss of the plate-shaped body is formed by protruding, and plastic processing (burring) is performed by a punch in a state where a reinforcing ring is applied to the periphery of the circular hole. The portion is deformed to form a boss, and a reinforcing ring is combined with the outer peripheral side of the boss. Such a reinforcing ring functions to increase the rigidity of the boss.

[0010]

FIG. 1 shows a main part of a steel plate 11 for manufacturing an air tank according to one embodiment of the present invention. A circular hole 12 is formed at a predetermined position of the steel plate 11. Then, the portion in which the circular hole 12 is formed is subjected to plastic working (burring) using a punch, thereby obtaining a structure shown in FIG.
A boss 14 having a through hole 13 at the center as shown in FIG.
The reinforcing ring 15 disposed below the boss 14 is combined with the outer peripheral side of the boss 14. A female screw 16 is formed on the inner peripheral surface of the through hole 13.
The connecting pipe or the male screw of the joint is screwed into the portion.

Therefore, a portion of the boss 14 having a through hole 13 in which a female screw 16 is formed, which is a connection portion, is shown in FIG.
The boss 14 is formed in a state where the boss 14 is reinforced by the reinforcing ring 15 as shown in FIG. Such a reinforcing ring 15 enhances the rigidity of the female screw 16 formed on the outer peripheral surface of the through hole 13 and can satisfy the airtightness when a male screw of a pipe or a joint is connected.

FIGS. 4 to 6 show such a method of forming a screw hole. In this case, a jig 20 composed of a mold is used. A through hole 21 is formed at the center of the mold 20, and a first step 22 is formed at an upper edge portion of the through hole 21. A second step 23 is formed on the side. The reinforcing ring 15 is arranged on the first step portion 22, and the steel plate 11 is arranged on the reinforcing ring 15, and processing is performed by the punch 27. At this time, a gap 24 is formed by the second step 23 in the lower part of the reinforcing ring 15 attached to the first step 22.

In such a state, the diameter of the insertion portion is substantially equal to the inner diameter of the through hole 21 of the mold 20.
As shown in FIGS. 4 and 5, as shown in FIG. 4 and FIG. Twelve edge portions are introduced into the gap 24 so that a locking portion 28 is formed. That is, by performing such processing, a boss 14 having a through hole 13 at the center as shown in FIG. 6 is formed. The reinforcing ring 15 is locked by the locking portion 28.

According to such a method, the reinforcing ring 15 compounded on the outer peripheral side of the boss 14 reinforces the boss 14, whereby the female screw 16 formed on the inner peripheral surface of the boss 14 (see FIG. 2)). Therefore, when the female screw 16 and the male screw of the pipe or the joint are screwed, sufficient airtightness can be generated between the two.

Further, the reinforcement of the boss 14 is achieved by the reinforcing ring 15 having a very simple shape, and is combined with the outer peripheral portion of the boss 14 during plastic working (burring) by the punch 27. The cost does not increase, and the manufacturing process does not become complicated. Moreover, the reinforcing ring 15 is a circular hole 1 of the steel plate 11.
2 is locked by the locking portion 28 caused by entering the gap 24 (see FIG. 5),
The reinforcing ring 15 does not fall off later.

[0016]

As described above, according to the present invention, plastic working is performed in a state where a reinforcing ring is applied around a circular hole on a surface formed by projecting a boss of a plate-like body, and the outer periphery of the boss is formed. The reinforcing ring is compounded on the surface.

Therefore, according to the present invention, the boss can be reinforced by the reinforcing ring, and the rigidity of the screw portion when the internal thread is formed on the inner peripheral surface of the through hole of the boss can be made sufficient. It is possible to connect a pipe or joint with external threads to this part,
It becomes possible to produce sufficient airtightness.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a relationship between a steel plate and a reinforcing ring.

FIG. 2 is a cross-sectional view of a steel plate on which a boss combined with a reinforcing ring is formed.

FIG. 3 is a perspective view showing a boss on which a reinforcing ring is combined.

FIG. 4 is a longitudinal sectional view of a state before processing by a punch.

FIG. 5 is a longitudinal sectional view of a state in the middle of processing by a punch.

FIG. 6 is a longitudinal sectional view showing a state after processing.

FIG. 7 is a longitudinal sectional view of a steel sheet showing a conventional processing method.

FIG. 8 is a longitudinal sectional view of a steel plate on which a boss is formed.

FIG. 9 is a longitudinal sectional view of a steel plate having a boss in which a female screw is formed on an inner peripheral surface.

FIG. 10 is a sectional view showing a relationship between a boss of another piece and a steel plate.

FIG. 11 is a longitudinal sectional view of a steel plate to which a boss is welded.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Steel plate 12 Circular hole 13 Through hole 14 Boss 15 Reinforcement ring 16 Female screw 20 Die (jig) 21 Through hole 22 First step 23 Second step 24 Gap 27 Punch 28 Locking part

Claims (1)

(57) [Claims] 1. A screw hole in which a circular hole is formed in a plate-like body, a boss is provided by plastically processing a portion around the circular hole, and a female screw is formed on an inner peripheral surface of a through hole of the boss. In the processing method, the plastic working is performed in a state where a boss of the plate-like body is formed by projecting and a reinforcing ring is applied around the circular hole, and the reinforcing is performed on an outer peripheral side of the boss. A method of processing a screw hole, wherein a ring is combined.