JPS59232627A - Manufacture of multilayer bellows - Google Patents

Abstract

PURPOSE:To obtain a noncontact-multilayer bellows, having gaps between layers, press-forming plural cylindrical bodies disposed concentrically which is formed by packing a gap between the cylindrical bodies with an intermediate material to be melted and removed by heating. CONSTITUTION:Plural cylindrical bodies 21, 22 having different diameters are disposed by forming an approximately concentrical gap between them. Next, the gap is packed with an intermediate material 23 consisting of a metal of low melting point to be melted and removed by heating. Next, the cylindrical bodies 21, 22, 23 are press-formed in a state filled with the material 23. And after press-forming, the material 23 is removed from the gap. Thus a noncontact- multilayer bellows 20 having a gap 24 between the layers is easily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a bellows, and particularly to a method for easily manufacturing a non-contact multilayer bellows.

[Technical background of the invention and its problems]

Conventionally, the method for manufacturing bellows is welding method 2.
A method using compression molding is known. In general, molded bellows are suitable for cases where a large diameter and relatively high strength are required, and are molded by the method shown in FIG. That is, the top,
The lid member 12 is brought into contact with the lid member 12 from below to seal it, and the mold 1 for molding is placed around the lid member 12.
3 are arranged in multiple stages. Next, one lid member 1
The high-pressure liquid H is injected from 2 and the lid members 12 are pressed in the direction toward each other (FIG. 1(A)). As a result, the cylindrical body 11 comes into contact with the mold 13, and its outer shape is deformed into an uneven step shape. Further press down on the lid member 12 as shown in Fig. 1 (
B)) When the lid portion 12 and the molding die 13 finally come into contact with each other, the molding process is completed and a bellows is obtained (FIG. 1(C)).

By the way, when the bellows is used as an expansion pipe joint, a two-layered bellows may be used, in which a predetermined gap is provided on the outside of the bellows as a boundary, and another bellows is provided as a back-up bellows. This is because if there is a large difference between the temperature of the fluid flowing inside and the outside temperature, the gas in the gap can be expected to have an insulating effect and maintain the fluid temperature, and if the fluid inside is a dangerous substance, A detector (sensor) can be installed in the gap to prevent leakage in the event of damage.
This is due to the fact that by installing a system, it is possible to detect fluid leakage, and furthermore, it is possible to ensure long-term soundness.

When manufacturing such a two-layer or multi-layer bellows using the manufacturing method described above, simply arranging two cylindrical bodies with different diameters approximately concentrically and compression-molding them at the same time will not work.
The two layers are molded in close contact with each other, making it impossible to form a predetermined gap between the two layers. Therefore, it is necessary to adopt a method of dividing the backup side of the outer layer and assembling it by welding or the like, which requires a large number of manufacturing steps and increases costs. If you mold each bellows individually and then insert and combine them later, the inner diameter of the outer bellows must be larger than the outer diameter of the inner bellows, and after assembly, the gap between the inner and outer layers will be reduced. The disadvantage is that it can become too thick.

[Purpose of the invention]

The present invention has been made in consideration of these points,
It is an object of the present invention to provide a method for manufacturing non-contact multilayer bellows having a predetermined gap between each layer by compression molding.

[Summary of the invention]

The method for manufacturing a non-contact multilayer bellows according to the present invention includes arranging a plurality of cylindrical bodies having different diameters substantially concentrically with each other giving a predetermined gap, filling the gap with an intermediate material, and The process consists of compression molding a shaped body filled with an intermediate material, and finally removing the intermediate phase from within the gap.

According to the present invention, a non-contact multilayer bellows having a predetermined gap between each layer can be manufactured by compression molding.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a process diagram showing a method for manufacturing a multilayer bellows according to the present invention, and the multilayer bellows is manufactured in the steps shown in FIGS. 2(A), (B), and CC). In this embodiment, for ease of explanation, the inner bellows 21 and the outer backup bellows 4 are used.

A method for manufacturing a multilayer bellows with the simplest structure consisting of two outer layers will be described.

First, a round cylinder 21 and a backup cylinder n having different diameters are prepared, and they are arranged approximately concentrically with a predetermined gap.

The gap between the two cylindrical bodies 21 and 22 arranged in this manner is filled with an intermediate material n (FIG. 2(A)).

The intermediate material part must be one that can be easily removed from the gap after forming the cylindrical bodies 21 and 22, and has enough strength to transmit the stress applied by the inner layer to the outer layer. Be used. For example, when manufacturing bellows from Fe-based alloys such as stainless steel, the material of the bellows may be made of pure metals with low melting points such as Ga or Zn5n-based alloys with low melting points such as shimmering. A metal with a melting point below the annealing temperature.

Alloys can be used. In addition to the intermediate material, it may be a substance that is melted by a specific solution, gas, or the like, or a movable fluid.

The two cylindrical bodies 21 and 22 are compression-molded into a desired shape while being filled with the intermediate material n (FIG. 2(B)).

This compression molding can be performed, for example, by hydraulic molding using a mold, as described above. In this compression molding process, the deformation stress that the inner cylindrical member 21 receives is transmitted to the outer cylindrical part side 22 via the intermediary n, causing the inner and outer cylindrical members 2 and 22 to plastically deform at the same time. It will be done.

After compression molding, when the bellows is heated above the melting point of the intermediate In, the intermediate material Z3 melts and forms two cylindrical bodies 2],
22, leaving a gap U behind (second
Figure (C)). This results in a two-layer bellows pad with a gap.

〔Effect of the invention〕

As explained above, according to the present invention, a non-contact multilayer bellows having a predetermined gap between each layer can be easily manufactured.

The multilayer bellows obtained in this way has a heat insulating effect due to the gas existing in the gap m1, the strength and safety of the inner bellows is improved, and the internal fluid flow is improved by installing a detector in the gap. It has characteristics such as being able to detect leaks, and can be used as an expansion pipe joint that can be used for a long time even in places with severe thermal conditions.

[Brief explanation of the drawing]

FIGS. 1A to 1C are process diagrams showing a conventional compression molding method, and FIGS. 2A to 2C are process diagrams showing a method for manufacturing a multilayer bellows according to the present invention. 21... Inner cylindrical body, 22... Outer cylindrical body, 2
3...Intermediate material, 27! ···gap.

Claims (1)

[Claims] 1. A plurality of cylindrical bodies having different diameters are arranged substantially concentrically with a predetermined gap between each other, an intermediate material is filled in the gap, and the plurality of cylindrical bodies are A method for manufacturing a non-contact multilayer bellows, which comprises compression molding a state filled with an intermediate material, and then removing the intermediate material from within the gap. 2. The method for manufacturing a multilayer bellows according to claim 1, wherein the intermediate material is a low melting point metal that is melted and removed by heating.