JPH07236929A - Method for working tapped hole - Google Patents

Abstract

PURPOSE:To facilitate the manufacturing and fully improve the strength of the part where a tapped hole is formed by carrying out a plastic working with a reinforcing ring attached to the periphery of a round hole on a surface where a boss is projected and by compounding the reinforcing ring on the outer periphery of the boss. CONSTITUTION:A punch 27 is used whose diameter of an inserting part is almost the same as that of a through-hole 21 of a die 20; and the inserting part is strongly force-fitted from above into the round hole of a steel plate 11. As a result, the surrounding part of the round hole is plastically worked, and simultaneously a boss 14 is formed which is provided with a through-hole 13 in the center. A reinforcing ring 15 is combined to the outer periphery of the boss 14 and also restrained with a restraining part 28. Consequently, the boss 14 is reinforced by the reinforcing ring 15 combined to the outer periphery of the boss 14, imparting a sufficient rigidity when a female screw is formed on the inner periphery of the boss 14. Thus, when this female screw and a male screw of a pipe or a joint are fastened, a sufficient airtightness is produced between them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a screw hole, and in particular, a circular hole is formed in a plate-like member, and a peripheral portion of the circular hole is plastically processed to provide a boss. The present invention relates to a method for processing a screw hole in which a female screw is formed on the inner peripheral surface of the.

[0002]

2. Description of the Related Art An air tank for filling air compressed by a compressor is made of steel plate. Then, in order to connect the portion to which the pipe for filling the air compressed by the compressor is connected and the air pipeline for guiding the compressed air filled in this air tank to a predetermined portion, a female screw is provided at a predetermined position of the air tank. The connection portion having the above is provided, and the male screw of the pipe or the joint is screwed into the connection portion to make 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 of a plate-shaped body 1 made of a steel plate for manufacturing an air tank. The hole 2 is formed in advance, and the portion in which the circular hole 2 is formed is subjected to plastic working (burring) with a punch die to form 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 a joint connected to the female screw 5 is screwed in.

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

[0005]

In the case of burring as shown in FIGS. 7 to 9, the wall thickness of the boss 4, that is, as shown in FIG. 9, the female screw 5 is formed on the inner peripheral surface of the boss 4. 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 when the male screw portion on the tip side of the pipe or joint is screwed in, and sufficient mechanical strength cannot be obtained, thereby impairing the airtightness of the air tank. There was a problem.

As shown in FIGS. 10 and 11, the through hole 7
A boss 8 made of another 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, there is a drawback that a welding process is required, which makes the manufacturing troublesome and increases the cost. Further, if the welding is not performed uniformly over the entire circumference of the root portion of the boss 8, there is a problem that an airtight defect in which air leaks from the welding portion occurs.

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

[0008]

According to the present invention, a circular hole is formed in a plate-like body, a peripheral portion of the circular hole is plastically processed to provide a boss, and an internal thread is formed on an inner peripheral surface of the through hole of the boss. In the method of processing a screw hole configured to form a boss of the plate-shaped body is a surface formed by protruding, the plastic working is performed in a state of applying a reinforcing ring around the circular hole,
The present invention relates to a method for processing a screw hole, wherein the reinforcing ring is compounded on the outer peripheral side of the boss.

[0009]

[Function] A boss of a plate-like body is formed on the surface of the circular hole, and a punch is used to perform plastic working (burring) while a reinforcing ring is applied around the circular hole. The portion is deformed to form a boss, and a reinforcing ring is compounded on the outer peripheral side of the boss. Such a reinforcing ring functions to increase the rigidity of the boss.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a main part of a steel plate 11 for manufacturing an air tank according to an 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) by a punch, and thus, as shown in FIG.
As shown in FIG. 2, a boss 14 having a through hole 13 in the center is formed, and the steel plate 1 is formed so as to correspond to the circular hole 12.
The reinforcing ring 15 arranged on the lower side of the boss 1 is combined with the outer peripheral side of the boss 14. An internal thread 16 is formed on the inner peripheral surface of the through hole 13, and the internal thread 16
The connecting pipe or the male screw of the joint is screwed to the part.

Therefore, a portion on the outer peripheral side of the boss 14 having a through hole 13 in which a female screw 16 is formed, which is a connecting portion, is shown in FIG.
As shown in FIG. 5, the boss 14 is formed while being reinforced by the reinforcing ring 15. 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 the male screw of the pipe or the joint is connected.

FIGS. 4 to 6 show such a screw hole machining method, in which a jig 20 made of a mold is used. A through hole 21 is formed in the center of the mold 20, and a first step portion 22 is formed at the edge portion on the upper end side of the through hole 21, and further below the first step portion 22. A second step portion 23 is formed on the side. Then, the reinforcing ring 15 is arranged on the first step portion 22, and the steel sheet 11 is arranged on the reinforcing ring 15, and the punch 27 is used for processing. At this time, a gap 24 is formed by the second step portion 23 in the lower portion of the reinforcing ring 15 attached to the first step portion 22.

In such a state, the punch 2 has a diameter of the insertion portion substantially equal to the inner diameter of the through hole 21 of the die 20.
As shown in FIGS. 4 and 5, the punch 27 strongly press-fits the circular hole 12 of the steel plate 11 from above, and the punch 27 plastically processes the peripheral portion of the circular hole 12 of the steel plate 11. The edge portion of 12 is introduced into the gap 24, and thereby the locking portion 28 is formed. That is, by performing such processing, the boss 14 having the through hole 13 at the center is formed as shown in FIG. 6, and the reinforcing ring 15 is compounded on the outer peripheral side of the boss 14 and 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. Sufficient rigidity is imparted to (see 2). Therefore, when the female screw 16 and the male screw of the pipe or the joint are screwed together, sufficient airtightness can be generated between them.

Further, the reinforcement of the boss 14 is achieved by the reinforcement ring 15 having an extremely simple shape, and further, it is combined with the outer peripheral portion of the boss 14 during the 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 the circular hole 1 of the steel plate 11.
Since the edge portion of 2 is locked by the locking portion 28 generated by entering the gap 24 (see FIG. 5),
The reinforcing ring 15 will not fall off later.

[0016]

As described above, according to the present invention, the plastic working is performed in a state where the reinforcing ring is applied to the periphery of the circular hole on the surface of the plate-shaped body on which the boss is projecting, and the outer periphery of the boss. It is a composite of reinforcing rings on the surface.

Therefore, according to the present invention, the boss can be reinforced by the reinforcing ring, and the rigidity of the threaded portion when the internal thread of the through hole of the boss is formed is sufficient. It becomes possible, and when connecting a pipe or joint equipped with a male screw to this part,
It is possible to create a sufficient hermeticity.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of a steel sheet on which a boss having a composite reinforcing ring is formed.

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

FIG. 4 is a vertical cross-sectional view of a state before processing by punching.

FIG. 5 is a vertical cross-sectional view showing a state in the middle of processing with a punch.

FIG. 6 is a vertical cross-sectional view of a state in which processing has been completed.

FIG. 7 is a vertical cross-sectional view of a steel plate showing a conventional processing method.

FIG. 8 is a vertical cross-sectional view of a steel plate on which a boss is formed.

FIG. 9 is a vertical cross-sectional view of a steel plate having a boss with an internal thread formed on the inner peripheral surface thereof.

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

FIG. 11 is a vertical sectional view of a steel plate having a boss welded thereto.

[Explanation of symbols]

 11 Steel Plate 12 Circular Hole 13 Through Hole 14 Boss 15 Reinforcement Ring 16 Female Thread 20 Mold (Jig) 21 Through Hole 22 First Step 23 Second Step 24 Gap 27 Punch 28 Locking Part

Claims (1)

[Claims] 1. A screw hole in which a circular hole is formed in a plate-like member, a peripheral portion of the circular hole is plastically processed to provide a boss, and a female screw is formed on the inner peripheral surface of the through hole of the boss. In the processing method, the plastic processing is performed in a state in which a reinforcing ring is applied around the circular hole, which is a surface formed by projecting the boss of the plate-shaped body, and the reinforcement is provided on the outer peripheral side of the boss. A method for processing a screw hole, characterized in that a ring is combined.