JPS62228756A - Bellows - Google Patents

Abstract

PURPOSE:To prevent a foreign matter from remaining within bellows and eliminate the need of after-treatment process by inserting a cylindrical elastic body inside a metal pipe and molding bellows by means of the elastic deformation of said cylindrical elastic body. CONSTITUTION:One end part a1 of an easily deformable metal pipe A is supported by a pipe holder 2. Mold piece 5 having a sectional form corresponding to each meandering section b1 of a bellows B to be molded, are arranged in between the pipe holder 2 and a punch 3. When molding a metal pipe A, a cylindrical elastic body 6 made of urethane rubber, etc. is inserted inside the metal pipe A. When molding bellows, the mold members 5 are placed in a mutually separate condition, and the cylindrical elastic member 6 is inserted inside the metal member A one end of which is supported by the pipe holder 2. Thereby, when the punch 3 is advanced, each part of the pipe wall of the metal pipe A where the mold member 5 does not exist is projected out in the radial direction due to the compression of the cylindrical elastic body 6. After that, as the punch 3 is retracted, the bellows B is completed.

Description

[Detailed description of the invention] 1. Industrial application field 1. The present invention relates to a bellows made of metal pipe.

1. Prior Art 1. As is well known, bellows with a bellows-shaped peripheral surface made of metal pipes are used in piping systems for fluid pipes to absorb expansion and contraction due to curvature of the pipe or thermal expansion. A bellows with such a structure is manufactured as follows. In other words, the metal pipe that becomes the material for the bellows is first made of
It is placed in a removable molding piece that defines the external shape of the bellows-shaped cross section, and after sealing both ends of the metal pipe in a liquid-tight state, high-pressure fluid such as water or lubricating oil is injected into the inside of the metal pipe, and this fluid The pressure causes the wall of the metal pipe to bulge in the radial direction. Therefore, in such conventional manufacturing equipment, the wall of the metal pipe is warped into a bellows shape based on the cross-sectional shape of the forming piece, so after the pressure inside the metal pipe is removed, the forming piece is A bellows can be obtained by removing the formed metal pipe from the mold, but the bellows thus obtained must be thoroughly washed or dried. In other words, in manufacturing equipment that uses pressure water, if moisture remains inside the molded bellows, this residual moisture will cause "rust", so a drying process is always required after the bellows are completed. In addition, when lubricating oil is used, if any lubricating oil remains inside the bellows, the residual lubricating oil may become an impurity when the bellows is in use, so thoroughly wash the completed bellows. I needed to.

-Object of the Invention 1 In view of the above-mentioned problems of conventional bellows, it is an object of the present invention to obtain a bellows without using pressurized water or lubricating oil that requires post-treatment.

Structure of the Invention - In order to achieve this object, the present invention arranges a large number of molding pieces that can regulate the outer shape of the metal pipe around the outer circumference of an easily deformable metal pipe, and forms a cylindrical shape approximately equal to the inner diameter of the metal pipe. An elastic body is inserted into the metal pipe, and a punch inserted into the metal pipe compresses and expands the cylindrical elastic body, thereby deforming the peripheral wall of the metal pipe into a shape corresponding to the molding piece. This is what I propose.

One example- Embodiments of the invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a forming apparatus used in the present invention, in which an easily deformable metal pipe A, which is the material of the bellows, is supported at one end a1 by a tube holder 2 fixed to a base 1 of the forming apparatus. Ru. This tube holder 2 is facing the punch 3, which will be detailed later! A mounting hole 4 having the same diameter as the metal pipe A is formed in the distal end surface of the metal pipe A.

A large number of molding pieces 5 are arranged between the tube holder 2 and the punch 3 to form a cross-sectional shape corresponding to the bellows part b1 of the bellows to be molded. Although not shown, these molding pieces 5 are movable in the length direction of the metal pipe A along guide rods provided on the base l, and are spaced at a constant distance from each other as shown in FIG. In the present invention, it is possible to take a first position in which the wafer is formed and a second position in close proximity to each other as shown in FIG.

When forming the metal pipe A, a cylindrical elastic body 6 made of urethane rubber or the like is inserted inside the metal pipe A.
1′! t1, this cylindrical elastic body 6 is made by molding an elastic material with high elastic recovery properties whose volume hardly changes upon compression into a cylindrical shape with an outer diameter approximately equal to the diameter of the metal pipe A.

Further, on the end surface of the punch 3 having an outer shape substantially the same as that of the tube holder 2, there is provided an opposite end a of the metal pipe A supported by the tube holder 2.
A central portion 3a surrounded by the annular groove 7 is inserted into the metal pipe A to apply pressure to the cylindrical elastic body 6. In the illustrated embodiment, the base 1 has an internal pressure adjusting member 8 attached thereto that is moved in synchronization with the pressurizing movement of the punch 3. This internal pressure adjusting member 8 has a tip 8a inserted into the metal pipe A and receives the right end surface of the cylindrical elastic body 6, but the internal pressure adjusting member 8 has a male thread that engages with the female thread 2a on the inner surface of the tube holder 2. 8b retreats to the right at low speed in synchronization with the punch 3, so when the cylindrical elastic body 6 is pressurized by the punch 3, the pressure state inside the cylindrical elastic body 6 is constant throughout its length. and become uniform.

Since the illustrated molding apparatus has the above structure, the molding pieces 5 are placed in the mutually spaced state shown in FIG. 1 when molding the bellows.

A cylindrical elastic body 6 is inserted into a metal pipe A whose one end is supported by a tube holder 2 . Therefore, when the punch 3 is moved in the direction of the arrow X in FIG. 1 and advanced to the position indicated by the imaginary line in FIG. metal pipe A
The tube wall a3 of bulges out in the radial direction.

After this, when the punch 3 is further advanced in the direction of arrow
A bellows portion b1 having a shape corresponding to the cross-sectional shape of is formed as shown in FIG. In this process, the rate of change in the amount of expansion due to compression of the cylindrical elastic body 6 and the mold clamping movement of the molding piece 5 do not completely match, and the internal pressure state of the cylindrical elastic body 6 is partially different. However, this non-uniformity of the pressure state is prevented by the movement of the internal pressure adjustment member 8, which is gradually retreated to the right in synchronization with the forward movement of the punch 3.

After the above steps, when the punch 3 is retreated, the cylindrical elastic body 6 naturally returns from the state shown in FIG. 2 to the state shown in FIG. Disassemble frame 5 in the radial direction of metal pipe A, and
A bellows B as shown in the third figure can be completed by simply taking out the cylindrical elastic body 6 from inside.

Effects of the Invention As is clear from the above description, according to the present invention, a cylindrical elastic body is inserted into the inside of a metal pipe as a raw material, and a bellows is made by elastic deformation of the cylindrical elastic body. No foreign matter remains inside the bellows, and there is no need for a drying process or a cleaning process for the bellows after completion.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the molding device used in the present invention, FIG. 2 is a cross-sectional view of the same molding device during molding, and FIG. 3 is a cross-sectional view of the completed bellows. A...Metal pipe, B...Bellows. 3... Punch, 5... Molding piece, 6... Cylindrical elastic body.

Claims (1)

[Claims] 1) A large number of molding pieces capable of regulating the outer shape of the metal pipe are arranged around the outer circumference of the metal pipe, which is easily deformed, and a cylindrical elastic body approximately equal to the inner diameter of the metal pipe is placed inside the metal pipe. The bellows is obtained by compressing and expanding the cylindrical elastic body with a punch inserted into the metal pipe, and warpingly deforming the peripheral wall of the metal pipe into a shape corresponding to the molding piece.