JP2008190675A - Metal o-ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal O-ring having both high airtightness with an allowable leakage amount of 1 x 10<SP>-10</SP>Pa*m<SP>3</SP>/sec or less and high corrosive resistance against corrosive gases used for manufacturing semiconductors and formed in a simple structure. <P>SOLUTION: This metal O-ring 1 is annularly formed of an austenitic stainless steel formed hollow in cross section. The surface hardness of the O-ring is 200 to 250 Hv in Vickers hardness, and the wall thickness thereof in cross section is 0.27 to 0.30 mm. The outer diameter d of the O-ring in cross section is desirably 0.8 to 1.0 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a metal O-ring used for, for example, airtightly connecting piping members for semiconductor manufacturing.

In general, for semiconductor manufacturing, process gases such as ammonia, odor gas, nitrogen trifluoride, and fluorine-based gases such as fluorine are used as materials for forming thin films. When these process gases contain impurities, the magnitude of the reaction becomes unstable, or reaction products adhere to the flow path of the fluid control device that supplies the process gas, resulting in unstable fluid control. High purity is demanded.
Moreover, in a line handling corrosive gas, there are many cases where rubber or resin cannot be used in terms of gas permeability and corrosion resistance. For this reason, normally, a metal gasket or a metal ring having a C-shaped cross section is used for the connecting portion of such a piping member or fluid control device. For example, the allowable leakage amount of these connecting portions is 1 × 10 ⁻¹⁰ Pa · m ³ / sec or less.

  For example, in Patent Document 1, a metal gasket for a vacuum device, which is sandwiched between vacuum joints and pressed against a contact part of the joint to be crushed, deformed and sealed, is pressed against the contact part. The seal surface that is crushed and deformed is made thinner in the thickness direction than the land portion that does not contact the contact portion, and the land portion is against the seal surface so that the seal surface is not damaged. A metal gasket is provided which is protected. Moreover, this metal gasket is made of stainless steel, and is described to be adjusted to a Vickers hardness of 120 to 180 Hv by annealing in a heat treatment process.

  Further, Patent Document 2 discloses a metal gasket including a jacket made of a metal jacket material having a C-shaped cross section and a spring made of a spring material attached to the jacket, wherein the spring material is precipitation hardened stainless steel. A metal gasket made of steel is described, and the metal jacket material is described as a jacket material whose surface hardness can be reduced to Hv 80 to 150 by annealing or solution heat treatment.

  Furthermore, in Patent Document 3, Ni is 12.90 to 15.00% by weight, Cr is 16.50 to 18.00%, Mo is 2.00 to 3.00%, and C is 0.02% or less. Si is 0.30% or less, Mn is 0.40% or less, P is 0.03% or less, S is 0.003% or less, Cu is 0.25% or less, and Al is 0.01% or less. A gasket made of stainless steel and having a surface Vickers hardness of 90-160 is described.

JP 2003-90437 A JP 2001-182833 A Japanese Patent Application Laid-Open No. 11-236652

  According to the techniques described in Patent Literature 1 to Patent Literature 3 described above, high airtightness is ensured and the fluid flowing inside the pipe can be maintained with high purity, both of which are annealed or solution heat treated. Therefore, there is a problem that a manufacturing process for keeping the surface hardness low is required. In addition, it has a complicated shape and structure including a spring mounted on a cross-sectional C-ring-shaped jacket, and there is a problem that it is difficult to downsize the connecting portion of the piping member.

On the other hand, a metal O-ring in which a nickel plating layer is provided on the surface of a stainless steel O-ring having a hollow cross section has a simple structure and is suitable for downsizing a pipe connection portion.
However, some of the process gases described above chemically react with nickel, such as oxygen. Therefore, there is a problem that it cannot be used for such a process gas that reacts with nickel.
On the other hand, a stainless steel O-ring not provided with a nickel plating layer has a problem that high airtightness cannot be maintained.

  Accordingly, it is an object of the present invention to provide a metal O-ring that solves the above-described problems, has both high airtightness and high corrosion resistance, and has a simple structure.

In order to achieve the above object, the metal O-ring of the present invention is formed in an annular shape with austenitic stainless steel having a hollow cross section, the surface hardness is set to 200 to 250 Hv, and the cross section thickness is set to 0.27 to 0. .. 30 mm.
The outer diameter d of the cross section is preferably φ0.8 to 1.0 mm.

  According to the present invention, the austenitic stainless steel having a hollow cross section is formed in an annular shape, the surface hardness is Vickers hardness 200 to 250 Hv, and the cross section thickness is 0.27 to 0.30 mm. A metal O-ring with high corrosion resistance and a simple structure can be obtained.

The details of the present invention will be described with reference to the accompanying drawings.
1 is a cross-sectional view of a metal O-ring according to an embodiment of the present invention, FIG. 2 is a cross-sectional view illustrating a state in which the metal O-ring of the present invention is incorporated in a pipe connecting member, and FIG. 3 is a metal O-ring of the present invention. It is a graph which shows the result of having evaluated the airtightness of.

  As shown in FIG. 1, the metal O-ring 1 is formed in a ring shape as a whole, and the cross section is formed in a hollow circle. The material is austenitic stainless steel, and SUS304, SUS316, SUS321, or the like can be selected. In particular, SUS316L is suitable in terms of corrosion resistance.

The metal O-ring 1 can be manufactured through the following steps.
First, a hoop material whose thickness, hardness and width are appropriately controlled is bent into a cylindrical shape, and the butt portion of the hoop is seam welded to form a tube shape. Subsequently, the drawing die is passed to correct the unevenness of the seam weld to a minimum. Furthermore, after cutting to the circumference length of a metal O-ring and bending it into a ring shape, both ends are seam welded. Finally, barrel polishing is performed to finish the surface roughness (hereinafter, this series of steps is also referred to as semi-seamless).
In this step, the hardness and thickness of the hoop material can be appropriately set in consideration of the thickness reduction in the work hardening or drawing process. Further, the dimensional difference of the seam welded portion is controlled to 0.04 mm or less at the wire diameter φd.

The metal O-ring 1 can also be obtained from a so-called seamless pipe. However, since it is difficult to manage delicate thicknesses seamlessly, the semi-seamless described above is desirable.
The barrel polishing in the final step may be chemical polishing or electrolytic polishing, or a combination thereof.

The metal O-ring thus obtained has a surface hardness of 200 to 250 Hv, a cross-sectional thickness t of 0.27 to 0.30 mm, and a cross-sectional outer diameter d of φ0.9 mm. The outer diameter D of the ring is, for example, φ25.4 mm, but can be set as appropriate depending on the size of the piping member.
As shown in FIG. 2, the metal O-ring 1 is sandwiched between a piping member 2 in which a mirror-finished stamping part 21 is formed and a flange member 3 in which a mirror-finished stamping part 31 is formed. By fastening the member 2 and the flange member 3 with a bolt or the like (not shown), the metal O-ring is compressed and hermetically sealed. For example, the compression allowance of the metal O-ring 1 is 0.15 mm.

(Example)
FIG. 3 shows the result of evaluating the airtightness of the metal O-ring 1 attached to the piping member 2 and the flange member 3 as shown in FIG.
In the evaluation, the other end side (upper side in FIG. 2) of the piping member 2 was sealed, and the other end side (lower side in FIG. 2) of the flange member 3 was connected to a vacuum pump to make the inside high vacuum. Thereafter, a helium leak detector for measuring the amount of helium invading from the metal O-ring portion was prepared by providing a surrounding environment in a helium environment. In the evaluation, a sample having a leakage amount of 1 × 10 ⁻¹⁰ Pa · m ³ / sec or less is a black circle, and a sample having a leakage amount of 1 × 10 ⁻¹⁰ Pa · m ³ / sec or more is a white diamond. Show. In FIG. 3, the vertical axis indicates the thickness t of the metal O-ring 1, and the horizontal axis indicates the surface hardness of the metal O-ring 1 by Vickers Hv.

As shown in FIG. 3, it can be seen that in the region where the thickness t is 0.27 mm or more and the Vickers hardness is 250 Hv or less, the leakage amount satisfies 1 × 10 ⁻¹⁰ Pa · m ³ / sec or less. .
If the wall thickness t is 0.30 mm or more, the bending process is affected, and the material cost increases, so the upper limit is preferably set to 0.30 mm. In addition, even if the Vickers hardness is 200 Hv or less, it can satisfy the standard leakage amount, but in order to stabilize 200 Hv or less, annealing or solution heat treatment is required, so the cost is increased. End up.

  Therefore, in order to maintain the high airtight sealability of the metal O-ring 1, the surface hardness should be Vickers hardness 200 to 250 Hv, and the cross-sectional thickness should be 0.27 to 0.30 mm.

It is sectional drawing of the metal O-ring concerning embodiment of this invention. It is sectional drawing explaining the state which incorporated the metal O-ring of this invention in the pipe connection member. It is a graph which shows the result of having evaluated the airtightness of the metal O-ring of this invention.

Explanation of symbols

1: Metal O-ring, 2: Piping member, 3: Flange member

Claims (2)

A metal O-ring formed of an austenitic stainless steel having a hollow cross section, having a surface hardness of 200 to 250 Hv and a cross-sectional thickness of 0.27 to 0.30 mm. 2. The metal O-ring according to claim 1, wherein a cross-sectional outer diameter d is φ0.8 to 1.0 mm.

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