JPH0481661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a welded bellows used for high-pressure seals such as mechanical seals and valves.

[Conventional technology]

Conventionally, some bellows of this type have a structure in which the bellows body 1 is continuously integrally molded from a thin plate, as shown in FIG.

However, in the case of such so-called molded bellows, if the plate thickness is increased in order to increase the pressure resistance, it is impossible to form them, so it is not possible to form them in two or three layers with the same thin plate thickness. Although the pressure resistance is improved by
Currently, only about 100 kg/cm ² can be obtained at most.

Therefore, as an alternative to the above-mentioned molded bellows, as shown in FIG.
It is formed by a single bellows 2 consisting of a plurality of thin ring plates, and each of these single bellows 2...
There is a welded bellows formed by alternately welding the inner circumferential end 2A and outer circumferential end 2B of ... to a, welding a, a.

[Problem to be solved by the invention]

However, in the welded bellows of the conventional structure described above, when increasing the pressure resistance, each bellows unit 2,
Currently, this is done by reducing the pitch between the two and increasing the thickness, and stacking plates of the same thickness in double or triple layers, similar to molded bellows. Not only does the welding work require a great deal of effort and effort, but the welded part is located at the inner peripheral end of the bellows, where the maximum stress occurs, which causes problems such as poor reliability of the welded part.

The present invention has been made in view of the above circumstances, and its purpose is to improve pressure resistance without stacking plates of the same thickness in double or triple layers, and to An object of the present invention is to provide a welded bellows that can improve the reliability of a welded part.

[Means to solve the problem]

In order to solve the above problems, the method for manufacturing a welded bellows according to the present invention includes an inner circumferential portion curved toward the inner diameter side,
A plurality of individual bellows having a cylindrical outer peripheral end extending from the inner peripheral part to the outer diameter side and further extending from the outer peripheral part opposite to each other in the axial direction are cut out from a steel material, and are placed next to each other in the axial direction. The outer peripheral ends of the single bellows are butt welded to each other.

[Effect]

According to the present invention, since the bellows alone is shaped by cutting out a steel material, residual stress is not generated during shaping even if the thickness of the bellows alone is increased. Furthermore, since there is no welded part on the inner periphery where the maximum stress occurs when high pressure is applied from the outer periphery of the bellows, and the butt-welded outer periphery end is cylindrical, the pressure from the outer periphery is reduced. This creates a structure that prevents excessive loads from being generated in the welded parts when the bellows deforms.

〔Example〕

The present invention will be described below with reference to an embodiment shown in FIGS. 1 to 3.

As shown in FIG. 1, reference numeral 11 is a welded bellows main body according to the present invention manufactured by a manufacturing process described below. The bellows main body 11 has a structure in which a plurality of bellows units 12 are connected to each other in the direction in which the axis X extends.

To manufacture the bellows body 11, as shown in FIG. 2, for example, a ring-shaped steel material 21 is used, and by cutting this steel material 21, a single bellows body 12 as shown in FIG. 3 is produced. to form. This single bellows 12 has an inner peripheral part 13 whose cross section cut along a plane passing through the axis X is approximately U-shaped and curved inward, and an inner peripheral part 13 that extends from the inner peripheral part 13 to the outer diameter side and further extends from the outer peripheral part to the shaft. It is composed of outer circumferential end portions 14A and 14B that extend oppositely to each other in both directions, and no residual stress is generated as in the case of shaping by drawing or pressing. A plurality of these single bellows 12 are arranged adjacent to each other so as to face each other in the direction in which the axis X extends, and are joined together by butt welding only the outer peripheral ends 14A, 14A of each of them, as shown in FIG. The bellows body 11 is obtained.

Welded bellows body 1 manufactured in this way
1 is particularly suitable for using the outer peripheral space as a high pressure side. That is, the inner circumferential portion 13, which is the part where the maximum stress occurs in this case, is made of a single material with no welded parts, and the pressure in the outer circumferential space is applied from both sides in the axial direction to the outer circumferential ends 14A, 14B at the welded parts. They act in the direction of pressing each other at point a. Moreover, bending deformation due to bellows contraction (deformation such that welded part a becomes the apex) is difficult to act on the cylindrical outer peripheral ends 14A, 14B, and the fluid pressure on the outer peripheral side is directed toward the inner diameter to suppress this bending deformation. Therefore, excessive stress is less likely to be generated in the welded part a.

〔Effect of the invention〕

In the present invention, each bellows is formed by cutting it out of a steel material, so no residual stress is generated inside the bellows, and for this reason, the bellows can be formed thickly from a single material. Pressure resistance can be improved. In addition, since the cylindrical outer peripheral ends of the single bellows are butt welded together, bending stress is less likely to be applied to the welded part when contracting and deforming due to pressure in the outer space of the bellows. Since there is no welded portion on the inner circumference, this has the excellent effect of increasing the reliability of the welded portion.

[Brief explanation of the drawing]

FIG. 1 is a schematic half-sectional view showing one embodiment of the welded bellows according to the present invention, FIGS. 2 and 3 are schematic half-sectional views showing the manufacturing process of the bellows alone, and FIG. 4 is a conventional one. FIG. 5 is a schematic half-sectional view of a formed bellows, and FIG. 5 is a schematic half-sectional view of a conventional welded bellows. DESCRIPTION OF SYMBOLS 11... Welded bellows main body, 12... Bellows unit, 13... Inner peripheral part, 14A, 14B... Outer peripheral end part, 21... Steel material, a... Welded part.

Claims (1)

[Claims] 1. A single bellows having an inner circumferential portion curved toward the inner diameter side, and a cylindrical outer circumferential end portion extending from the inner circumferential portion toward the outer diameter side and further extending from the outer circumference to opposite sides in the axial direction is made from steel material. 1. A method for manufacturing a welded bellows, characterized in that a plurality of bellows are formed by cutting, and the outer circumferential ends of the single bellows adjacent in the axial direction are butt-welded to each other.