JP2003148616A - Weld metal bellows - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weld metal bellows which provides sufficient durability even if it is made of a material having low material strength such as an aluminum alloy material. SOLUTION: The peripheral parts 13 of all annular plates 10 constituting this weld metal bellows are formed into inclined surfaces non-parallel to a virtual plane P orthogonal to the bellows axis line A and entirely inclined in the same direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welded metal bellows, and more particularly to a semiconductor manufacturing device, a valve / pipe joint,
The present invention relates to a welded metal bellows used as a stretchable seal member in a coupler or the like.

[0002]

2. Description of the Related Art A welded metal bellows is welded over the entire circumference of the inner peripheral edge of each of a plurality of annular plates made of metal to the inner peripheral edge of another annular plate adjacent on one side. The outer peripheral edge is welded over the entire outer peripheral edge of another annular plate adjacent on the other side, and has a tubular shape that can expand and contract in the axial direction. For example, it is shown in Japanese Patent Publication No. 3-249480. Has been done.

A welded metal bellows of this type is shown in FIG.
7A and 7B, a flat mold composed of an annular plate having a flat plate shape and an annular plate press-formed into a concentric waveform as shown in FIGS. 7A and 7B. The corrugated shape is conventionally known.

[0004]

The conventional welded metal bellows in either flat type or corrugated type are shown in FIGS.
As illustrated in FIG. 2, the joining neutral planes N of the two adjacent annular plates 100 having the outer peripheral edges 101 welded to each other (outer peripheral edge welded portions 102) on the outer peripheral edge sides are orthogonal to the bellows axis A. It forms a plane parallel to the virtual plane P.

When the welded metal bellows expands and contracts in the axial direction, the outer peripheral edge welded portion 102 becomes a fixed point and the two annular plates 100 adjacent to each other are displaced in a direction in which they are brought into contact with each other.
Stress concentration occurs in the outer peripheral edge welded portion 102, and maximum stress is generated in the second welded portion of the outer peripheral edge welded portion 102. This is
It can be confirmed by finite element stress analysis.

Here, the problem is that the place where the maximum stress occurs matches the place where the material structure is mechanically lower than other parts due to the thermal effect of welding. The durability of the bellows is greatly reduced. For this reason, due to repeated expansion and contraction, a crack is likely to occur in the second welded portion relatively early, the airtightness of the bellows cannot be maintained, and it becomes unusable.

In the field of semiconductor manufacturing, in order to increase the density of patterns and improve the yield, in order to increase the degree of vacuum in the vacuum chamber (reaction chamber) of the film forming apparatus, the amount of outgas generated is higher than that of stainless steel materials. A vacuum chamber is being constructed with an aluminum alloy material that has a low content. Accordingly, the weld metal bellows used in the vacuum chamber is also required to be made of an aluminum alloy material having a lower material strength than stainless steel material, and the above-mentioned problems become more and more prominent.

The present invention has been made in order to solve the above-mentioned problems, and by devising the bellows cross-sectional shape, the place where the maximum stress is generated during the expansion and contraction operation is a welded portion having a low strength. Avoid aluminum alloy materials, etc.
An object of the present invention is to provide a welded metal bellows having sufficient durability even if it is made of a material having low material strength.

[0009]

In order to achieve the above object, a welded metal bellows according to the present invention has a plurality of metal annular plates each having an inner peripheral edge adjacent to one another on the inner peripheral edge thereof. A welded metal bellows formed by welding the entire circumference of the inner peripheral edge of an annular plate and the entire outer periphery of the outer peripheral edge of the adjacent annular plate on the other side. The outer peripheral edge portions of all the annular plates constituting the above are non-parallel to an imaginary plane orthogonal to the bellows axis, and all are inclined surfaces inclined in the same direction.

According to the weld metal bellows of the present invention, the outer peripheral edge portions of all annular plates constituting the weld metal bellows are non-parallel to an imaginary plane orthogonal to the bellows axis and are inclined in the same direction. Due to its shape, due to its shape, the place where maximum stress is generated during expansion and contraction is biased to other parts from the periphery of the welded part on the side of the outer peripheral edge where strength is low. It is possible to avoid the place where the maximum stress is generated around the welded part on the outer peripheral edge side where the strength is low.

In the welded metal bellows according to the present invention, the inclined surface of the outer peripheral edge portion of the annular plate is smoothly connected to the inner peripheral side of the annular plate by the curved surface so that there is no sharp bent portion which causes stress concentration. ing.

In the welded metal bellows according to the present invention, the inclination angle of the outer peripheral edge portion of the annular plate with respect to the virtual plane is 10 degrees or more in order to sufficiently reduce the stress generated in the welded portion on the outer peripheral edge portion side during the expansion and contraction operation. Preferably there is. More preferably, the inclination angle of the outer peripheral edge portion of the annular plate with respect to the virtual plane is about 30 degrees.

In the welded metal bellows according to the present invention, the annular plate is made of aluminum alloy and is welded by laser welding.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 1 and 2 show one embodiment of a welded metal bellows according to the present invention.

The welded metal bellows comprises a plurality of annular plates 10 laminated in the axial direction and end members 2 at both ends.
It is composed of 0 and.

The annular plate 10 has a plate thickness of 0.1 to 10.
All of the press-formed products are made of a metal plate such as a stainless steel plate or an aluminum alloy plate having a size of about 0.2 mm, and have the same shape as a concentric corrugated press-molded product. The entire circumference and the entire circumference of the outer peripheral edge portion 12 are alternately joined by welding to form a cylindrical shape as a whole. In addition, in FIG.
i is the inner peripheral edge welded portion of the annular plate 10, and the symbol W
o is an outer peripheral edge weld portion of the annular plate 10.

Suitable welding methods for welding the inner peripheral edge portion 11 and the outer peripheral edge portion 12 of the annular plate 10 include a Tig welding method, an electron beam welding method, a laser (YAG) welding method, and the like. In the case of, a laser (YAG) that can respond for a short time by concentrating high-density energy
Welding methods are preferred.

Of the plurality of annular plates 10, FIG.
In FIG. 1, the uppermost one is welded to the connecting portion 21 of the upper end member 20 all around, and the lowermost one in FIG. End member 20
It is welded all around with the connecting portion 21. The end member 20 is made of the same metal material as the annular plate 10.

The outer peripheral edge portions 13 of all annular plates 10 constituting the welded metal bellows are non-parallel to an imaginary plane P orthogonal to the bellows axis A and are inclined in the same direction at the same inclination angle θ. It has an inclined surface. The outer peripheral edge portion (slope surface portion) 13 of the annular plate 10 is smoothly connected to the inner peripheral side of the annular plate 10 by the curved surface portion 14. FIG. 3 shows a state of the outer peripheral edge side of the annular plate 10 at the time of free length, and FIG. 4 shows a state of the outer peripheral edge side of the annular plate 10 at the time of contraction.

Since the outer peripheral edge side of the annular plate 10 has the above-mentioned shape, as shown in FIG. 5, the forces F1 and F2 acting on the annular plate 10 by the internal pressure of the bellows are the bellows axis lines. Direction force F1y,
It is decomposed into F2y and forces F1x and F2x perpendicular to the bellows axis. The forces F1y and F2y act as forces to extend the bellows, while the forces F1x and F2x act as forces to bend the annular plate 10.

As a result, there is no stress concentration on the outer peripheral edge welded portion Wo of the annular plate 10, and the place where the maximum stress occurs during the expansion / contraction operation is lower in strength than the outer peripheral edge welded portion Wo. It is possible to avoid deviation from the intermediate region (portion indicated by circle mark MAX in FIG. 2), which is a portion, so that the place where the maximum stress occurs during the expansion and contraction operation is around the outer peripheral edge weld Wo, which is weak in strength. As a result, sufficient durability can be obtained even with a material having a low material strength such as an aluminum alloy material.

Further, since the inclined surface portion 13 of the annular plate 10 is smoothly connected to the inner peripheral side of the annular plate 10 by the curved surface portion 14, there is no sharp bent portion which causes stress concentration, and this portion does not exist. Stress concentration does not occur in

The inclination angle θ of the inclined surface portion 13 is 5 °, 10
When finite element stress analysis was performed under the same pressure condition for three types of materials having the angle of 30 ° and 30 °, when the inclination angle θ was 5 °, the location where the maximum stress was generated was around the outer peripheral edge weld Wo. When the inclination angle θ is 10 ° and 30 °, it can be confirmed that the place where the maximum stress is generated is the non-welded portion apart from the periphery of the outer peripheral edge weld Wo, and the stress value around the outer peripheral edge weld Wo is small. It was It was also confirmed that the force for expanding the inside of the weld zone decreased as the tilt angle θ increased.

The larger the inclination angle θ of the inclined surface portion 13 is, the smaller the stress value around the outer peripheral edge welded portion Wo is. Therefore, the larger the inclination angle θ of the inclined surface portion 13 is, the better. There is a limit in press-molding the plate 10, and it is about 45 °.

[0025]

As can be understood from the above description, according to the weld metal bellows of the present invention, the outer peripheral edge portions of all the annular plates constituting the weld metal bellows are in relation to the virtual plane orthogonal to the bellows axis. Since they are non-parallel and all have inclined surfaces that are inclined in the same direction, the place where maximum stress occurs during expansion and contraction does not become a welded part with low strength, and is not affected by the heat of welding. become,
Sufficient durability can be obtained even with a material having a low material strength such as an aluminum alloy material.

[Brief description of drawings]

FIG. 1 is a sectional view showing the overall structure of one embodiment of a welded metal bellows according to the present invention.

FIG. 2 is a view showing a main part of one embodiment of a welded metal bellows according to the present invention.

FIG. 3 is a cross-sectional view showing a state of the outer peripheral edge side of the annular plate when the weld metal bellows according to the present invention is in a free length.

FIG. 4 is a cross-sectional view showing a state of the outer peripheral edge side of the annular plate when the weld metal bellows according to the present invention is contracted.

FIG. 5 is an explanatory view showing a force direction acting on an outer peripheral edge portion of the annular plate of the weld metal bellows according to the present invention.

FIG. 6 is a view showing a conventional flat type welded metal bellows.

7 (a) and 7 (b) are views showing a conventional corrugated weld metal bellows.

[Explanation of symbols]

10 annular plate 11 Inner peripheral edge 12 Outer periphery 13 Outer peripheral edge (slope) 14 curved surface 20 End member 21 Connection

Claims (4)

[Claims] 1. An inner peripheral edge of each of a plurality of annular plates made of metal is welded to an inner peripheral edge of another annular plate adjacent on one side over the entire circumference, and an outer peripheral edge of the other annular plate is In the welded metal bellows that is welded over the entire circumference of the outer peripheral edge of another adjacent annular plate, the outer peripheral edge portions of all the annular plates that make up the welded metal bellows form an imaginary plane orthogonal to the bellows axis. Welded metal bellows, which are non-parallel to each other and are all inclined in the same direction. 2. The welded metal bellows according to claim 1, wherein the inclined surface of the outer peripheral edge portion of the annular plate is smoothly connected to the inner peripheral side of the annular plate by a curved surface. 3. The welded metal bellows according to claim 1, wherein an inclination angle of an outer peripheral edge portion of the annular plate with respect to the virtual plane is 10 degrees or more. 4. The annular plate is made of an aluminum alloy,
The welded metal bellows according to any one of claims 1 to 3, which is welded by laser welding.