JP2003156147A - Metal gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal gasket having a small tightening force and a good sealing property and more suitable for a mass production, even in the case where a plating and a coating are not applied onto a surface of the metal gasket and a projection and a reverse projection are not applied to a contact surface of the metal gasket with a flange surface of a member to be sealed. SOLUTION: The metal gasket is characterized by that a recessed groove is provided on a side surface of an outer diameter part or a side surface of an inner diameter part of the metal gasket.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket that is widely used as a seal member under severe conditions such as high temperature and high pressure to vacuum applications, and more particularly to a metal gasket that has a good sealing property with a low tightening force.

[0002]

2. Description of the Related Art Metal gaskets are superior in corrosion resistance and heat resistance to elastomer gaskets and are therefore used as gaskets to replace elastomer gaskets in harsh environments such as high temperature / high pressure and radiation environments. . In addition, the metal gasket has significantly less permeation amount and released gas amount than the elastomer gasket, and is superior in heat resistance against baking,
It is also used as a gasket for ultra-high vacuum.

Particularly, in recent years, the metal gasket has been used under various plasma and radiation environments, and further under corrosive gas and toxic gas, and the environment for use of the metal gasket has only become severe. Corrosion resistance is required. Furthermore, in semiconductor lines, etc., due to the ultra-miniaturization and ultra-high integration of LSI,
The demands for ultra-purity such as particleless and removal of eluted ions are increasing further.

There are various metals that can be used as the material of the metal gasket even under such a severe environment of use. Among them, SUS materials, Ni and Ni alloys are mainly used. However, while these metal materials have excellent corrosion resistance and heat resistance, they have high strength and high hardness. Generally, a metal gasket requires a larger tightening force than an elastomer gasket in order to maintain the sealing effect by causing plastic deformation of the metal gasket. Therefore, for example, in order to withstand such a large tightening force of the flange of the joint of the pipe or the bolt for fastening the same, the flange thickness and the bolt diameter must be increased, and However, there is a problem that the size becomes large and the cost becomes high, and it has been desired to reduce the tightening force required for sealing.

In order to further reduce the tightening force in the metal gasket using such a high strength and high hardness material, the flange surface of the member to be sealed by the metal gasket,
In order to improve compatibility with the sealing surface of the metal gasket, the surface of the metal gasket is plated with a metal such as silver or nickel, or a resin coating typified by PTFE resin is applied. However, performing such a plating process or a coating process increases the number of steps and increases the cost. In addition, such plated material or coating resin is thermally deteriorated and corroded,
The desired sealing property cannot be ensured, and such a surface-treated material may become particles due to wear and the like and may contaminate the semiconductor line and the like.

Further, in order to further reduce the tightening force and improve the sealing property, the contact surface with the flange surface of the metal gasket is made small to increase the actual gasket surface pressure. For example, in the case of a metal flat gasket often used for general piping and equipment as shown in FIG.
By reducing the gasket width as shown in (b),
Even with a lower tightening force, the actual gasket surface pressure can be increased. Further, as shown in FIG. 10, both the contact surface 101 between the flange surface of the member to be sealed by the metal gasket and the sealing surface of the metal gasket is serrated, or as shown in FIG. The actual gasket surface pressure can be further increased by forming the metal gasket into an O-ring shape in cross section. However, even when such measures are taken, the tightening force is still several tens of times higher than that of the elastomer gasket, leaving room for improvement.

Under such circumstances, as a metal gasket having a reduced tightening force, a metal hollow O-ring having a hollow structure and an O-ring in cross section as shown in FIG. 12 (Japanese Patent Laid-Open No. 9-177976) and A metal C ring as shown in FIG. 13 (Japanese Patent Laid-Open No. 11-30333) and a spring-loaded metal gasket in which a coil spring is covered with an outer cover as shown in FIG. 14 (a) have been developed.

The metal hollow O-ring as shown in FIG. 12 is an O-ring having a hollow structure in cross section. The metal hollow O-ring is tightened by reducing its thickness or applying metal plating or resin coating on its surface. The effort is being reduced. Also, as shown in FIG.
In the metal C ring described in Japanese Patent Publication No. 3, a predetermined opening is formed to reduce the tightening force, and the opening is closed at the time of tightening so that it is as if it is an O-ring. As described above, since there are two fulcrums, in the closed state, a wide seal portion is formed along the flange surface of the member to be sealed by the metal C ring to achieve stable sealing performance.

In addition, in a spring-loaded metal gasket as shown in FIG. 14A, both of the contact surfaces 141 of the metal gasket with the flange surface of the member to be sealed are shown in FIG.
4 (b), the V-shaped projection described in JP-A-2-113171, and JP-A-9-264427, as shown in FIG. 14 (c). In the case where the V-shaped reverse projection is provided, since the annular convex portion or the concave groove is formed in the circumferential direction of the metal gasket along the flange surface of the member to be sealed by the metal gasket, the same tightening force is applied. Since the stress generated also increases, the airtight start stress can be reduced, thereby reducing the tightening force required for the seal.

[0010]

As described above, among the metal gaskets, the metal hollow O-ring, the metal C-ring, and the spring-loaded metal C-ring are metal gaskets with a low tightening force. However, even in this case, the tightening force requires several tens of times that of the elastomer gasket. Further, the material of the metal hollow O-ring is limited to a weldable material, and a high hardness material such as SUS is generally used. Therefore, when high sealability is required, it is necessary to apply metal plating or resin coating to the ring surface in order to improve compatibility with the flange surface, resulting in high cost. Also,
Since the manufacturing of the metal hollow O-ring includes a welding process, the cost is increased due to the increase in the number of processes.

Although the metal C-ring can be manufactured from any material, the gasket is deformed at the center of the C-ring at the time of tightening, and the fulcrum is one point. The repulsive force required for sealing cannot be transmitted, resulting in poor sealing performance. Further, if the tightening force is further increased, the tightening load cannot be received at the fulcrum, buckling occurs, and the sealing performance deteriorates.

On the other hand, the spring-loaded metal C-ring does not require a welding process in its manufacturing process, so that a low hardness, low strength material such as aluminum can be used for the outer cover. In this way, by using a low hardness material for the outer cover, it is possible to obtain familiarity with the flange surface without applying plating or coating, and the tightening force is also reduced. Furthermore, FIG.
With a protrusion as shown in (b) (JP-A-2-11317).
No. 1) or a spring-loaded metal gasket with a reverse protrusion as shown in FIG. 14 (c) (Japanese Patent Laid-Open No. 9-264427) is provided with a protrusion to further reduce the tightening force. ing.

However, in order to form such protrusions, it generally takes time to process, and there is room for improvement in terms of cost and productivity. Further, even in the case of the spring-loaded metal gasket with protrusions or reverse protrusions, which has a particularly high tightening effect, the tightening force thereof is 10 to 20 times or more that of the elastomer gasket, and the lower tightening force is much higher. Is desired. In addition, indentations may occur on the flange surface, especially due to the effects of protrusions provided on the contact surface with the flange surface, which may deteriorate the sealing performance. There is room for improvement.

According to the present invention, the tightening force is small even if the metal gasket surface is not plated or coated and the contact surface of the metal gasket with the flange surface of the member to be sealed is not provided with projections or reverse projections. In addition, it is an object of the present invention to provide a metal gasket which has good sealing property and is more producible.

[0015]

The present invention has been made in order to achieve the above-mentioned problems and objects in the prior art. The metal gasket of the present invention has It is characterized in that a concave groove is provided on the side surface of the inner diameter portion. In this case, it is preferable that the metal gasket has a circular cross section, a vertically elongated elliptical shape, or a horizontally elongated elliptical shape.

Further, the the radial width of the metal gasket to the outer diameter and W ₁ from the inner diameter portion of the metal gasket, among the width W _1, a width excluding the width of the groove and W ₂ In this case, it is preferable that W ₁ and W ₂ satisfy W ₂ / W ₁ <1/2.

Further, it is preferable that the concave groove provided in the metal gasket has a substantially U-shaped cross section, a trapezoidal cross section, or an elliptical cross section. With this configuration, the tightening force can be applied without plating or coating on the surface of the metal gasket, or without providing protrusions or reverse protrusions on the contact surface of the metal gasket with the flange surface of the member to be sealed. It is possible to reduce the size and obtain a good sealing property.

Further, in manufacturing, the metal gasket of the present invention can be manufactured by a method similar to the conventional method, and since plating or coating is not required and projections are not required, a complicated manufacturing process is not required. In addition, it can be manufactured at low cost and is excellent in mass productivity.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a metal gasket according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view of a first embodiment of a metal gasket according to the present invention, and FIG. 2 (a) is an AA line of FIG.
2 is a partial cross-sectional perspective view in the line direction, FIG. 2 (b) is a partial cross-sectional view in the AA line direction in FIG. 1, and FIG. 3 is a metal gasket of FIG. 1 for a flange of a joint such as a pipe. It is a partial expanded sectional view showing the state where it was.

In the figure, 10 indicates the metal gasket as a whole, and the metal gasket 10 is shown in FIG.
As shown in (a) and (b), it is composed of an annular metal gasket main body 1 having a substantially circular cross section in which a groove 12 is formed. The cross-sectional shape of the metal gasket body 1 of the present invention is not limited to the circular shape, and the shape shown in FIG.
It may be a vertically long elliptical shape as shown in FIG. 4 or may be a horizontally long elliptical shape as shown in FIG.

Then, the metal gasket 10 of this embodiment.
Then, in the outer diameter side surface 11 of the metal gasket body 1, a concave groove 12 having a substantially U-shaped cross section is formed in the circumferential direction of the metal gasket body 1 over the entire circumference of the metal gasket body 1. Various shapes can be applied to the shape of the concave groove 12, and the shape is not limited to the substantially U-shaped cross section as shown in FIG. 2B, but is shown in FIG. 5A, for example. Such a trapezoidal cross section and an elliptical cross section as shown in FIG. However, since a retainer may be used to prevent gasket damage due to excessive tightening of the gasket or to align the gasket core,
In such a case, it is preferable to have a U-shaped cross section as shown in FIG.

As shown in FIG. 2B, the groove 12 provided in the metal gasket 10 extends in the radial direction of the metal gasket 10 from the inner diameter side surface 13 to the outer diameter portion of the metal gasket 10. the width is W _1, among the width W _1, if the width except for the width of the groove 12 was set to W _2,
Namely, of the said width W _1, the width of the inner diameter side 13 of the metal gasket 10 to the groove 12 formed in the metal gasket 10 in the case of the W _2, the W ₁ and W
₂ preferably satisfies W ₂ / W ₁ <1/2, and more preferably 1/3 ≦ W ₂ / W ₁ ≦ 12/25.

When W ₂ / W ₁ is less than 1/3, the solid portion is increased, so the rigidity of the gasket is increased and the deformation of the gasket is limited. Therefore, sufficient plastic deformation, that is, familiarity cannot be obtained and the sealing property is poor. on the other hand,
When W ₂ / W ₁ is 1/2 or more, the solid portion becomes small, so the rigidity of the gasket becomes low and the deformation amount of the gasket becomes large. Therefore, it is considered that excessive deformation occurs and buckling easily occurs, and the buckling deteriorates the sealability.

Further, the width d between the tips 15 of the metal gasket 10 in which the concave groove 12 is formed and the height D of the metal gasket 10 in the direction perpendicular to the radial direction are 1 / 6≤d / D≤1 / It is desirable to satisfy 2. In the metal gasket 10 having such a groove 12, the surface hardness of the contact surface with the flange surfaces 22 and 23 of the member to be sealed of the metal gasket 10 is preferably 200 Hv or less in Vickers hardness, more preferably 130 Hv. It is the following.

Such a metal gasket 10 is manufactured, for example, by cutting a metal rod material or by injecting molten metal into a mold and solidifying the metal into a predetermined shape. However, the method of processing the metal gasket of the present invention is not limited to these, and a conventionally known method can be adopted as long as it can be processed into a desired shape, and it can be appropriately selected from the dimensional accuracy of the groove and the economical efficiency. Just select it.

The material of the metal rod forming the metal gasket 10 has a Vickers hardness of 200 Hv.
The following is not particularly limited as long as it is preferably 130 Hv or less, and may be appropriately selected according to the material of the flange of the member to be sealed. Specifically, a relatively low hardness material such as aluminum can be used. Further, even a relatively hard material such as Ni or SUS material can be adopted by performing a predetermined heat treatment. As the predetermined heat treatment, for example, in the case of austenitic stainless steel represented by SUS304 and SUS316, solution heat treatment for performing heat treatment under temperature conditions of 1030 ° C. or higher and 1100 ° C. or higher can be mentioned.

FIG. 6A is a partial cross-sectional perspective view of the second embodiment of the metal gasket according to the present invention.
(B) is a partial sectional view of a second embodiment of the metal gasket according to the present invention. The metal gasket 18 of this embodiment is basically the same in configuration as the metal gasket 10 of the first embodiment shown in FIGS. 2A and 2B.

In the metal gasket 10 of the first embodiment, the metal gasket body 1 having a substantially circular cross section has an outer diameter side surface 11 in the circumferential direction of the metal gasket body 1 over the entire circumference of the metal gasket body 1. Although the concave groove 12 is formed in a square shape, in the metal gasket 18 of the second embodiment shown in FIG. 6A, the concave groove 14 is formed in the inner surface 13 of the metal gasket body 1 having a substantially circular cross section. is doing. That is, a concave groove 14 having a substantially U-shaped cross section is formed on the inner side surface 13 of the metal gasket body 1 having a substantially circular cross section in the circumferential direction of the metal gasket body 1 over the entire circumference of the metal gasket body 1.

The shape of the concave groove 14 is not limited to the substantially U-shaped cross-section like the concave groove 12 described in the first embodiment. May be Further, the concave groove 14 provided in the metal gasket 18 is similar to that of the first embodiment, as shown in FIG.
As shown in (b), the width in the radial direction of the metal gasket 18 from the inner diameter portion of the metal gasket 18 to the side surface 11 of the outer diameter portion is W _1, and the width of the groove 14 is the width W ₁ of the width W _1. When W ₂ is the width excluding, that is, the width W ₁ from the outer diameter side surface 11 of the metal gasket 10 to the concave groove 14 formed in the metal gasket 10 is W ₂
In this case, it is preferable that W ₁ and W ₂ satisfy W ₂ / W ₁ <1/2, and further, 1/3 ≦ W ₂ / W ₁ ≦ 12/25.

With such a shape, the same effect as that of the first embodiment shown in FIGS. 2A and 2B can be obtained.

[0031]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited to these examples.

[0032]

Example 1 FIG. 7 formed from SUS316L material
Inner diameter 4.7 mm, outer diameter 7.1 m as shown in (a)
A compression-restoration airtight test was performed on a metal gasket having a height m (m) and a height (D) of 1.7 mm and a groove (height d = 0.7 mm) having a substantially U-shaped cross section on the outer diameter side. It was

FIG. 8 shows the tightening load on the vertical axis and the strain amount, that is, the deformation amount of the metal gasket on the horizontal axis. The load is increased stepwise, and at each tightening load stage, the helium leak detector (hereinafter , “HeL.D.”). In FIG. 8, S ₀ (airtightness starting point) is HeL.
D. The seal starting stress is equal to or lower than the sensitivity of (1 × 10 ⁻¹² Pa · m ³ / s), and S (tightening force) is the tightening force when a predetermined tightening margin is applied.

This tightening force is, for example, the tightening load when the screw is cut to a predetermined groove size and the flanges are metal-touched or the retainer height manufactured to a predetermined size is metal-touched. Is. In Example 1, a groove having a depth of 0.35 mm was formed on one side, and a test was performed using a flat flange on one side. S ₁
The (airtightness limit point) is HeL.V, when the residual stress of the metal gasket is reduced due to stress relaxation of the metal gasket after tightening to the tightening load S. D. It is the minimum tightening load that satisfies the sensitivity below. That is, the sealing property between the tightening loads S ₀ , S and S ₁ is HeL. D. The sensitivity below is satisfied. The results are shown in Table 1.

[0035]

[Comparative Examples 1 and 2] A metal gasket made of the same material as the metal gasket of Example 1 but having the same inner and outer diameter sizes and having no recessed groove on the outer diameter side.
A solid gasket having a vertically long rectangular cross section as shown in FIG. 7B was used, and in Comparative Example 2, a solid gasket having a vertically long elliptical cross section as shown in FIG. Tested and measured S ₀ , S and S ₁ . The results are shown in Table 1.

[0036]

[Table 1]

From Table 1, it can be seen that the metal gasket provided with the concave groove as in the case of the present invention (Example 1) has a lower tightening force S than the metal gasket not provided with the concave groove, and the starting point of the airtightness is further improved. HeLa S _0, also in the airtight limit point S _1. D. It is shown that the excellent sealing property of less than the sensitivity of 1 is satisfied.

[0038]

[Example 2] A SUS316L material having a vertically elongated elliptical cross section with a width (W ₁ ) from the inner diameter to the outer diameter of a metal gasket of 1.2 mm, excluding the width of a groove provided in the metal gasket. The same test as in Example 1 was conducted using a metal gasket having a width (W ₂ ) of 0.5 mm. The results are shown in Table 2.

[0039]

[Comparative Example 3] In Example 2, the width (W ₁ ) from the inner diameter to the outer diameter of the metal gasket was 1.2 mm, and the width (W ₂ ) excluding the width of the groove provided in the metal gasket was 0. Example 1 is the same as Example 2 except that the thickness is 0.8 mm.
The same test was performed. The results are shown in Table 2.

[0040]

[Table 2]

From Table 2, even in the metal gasket provided with the concave groove as in Example 2, the relationship (W ₂ / W ₁ ) between the radial width of the metal gasket and the width of the concave groove is predetermined. It is shown that the tightening force S can be further reduced by being within the range.

[0042]

According to the metal gasket of the present invention, since the groove is provided on the outer diameter side surface or the inner diameter side surface of the metal gasket, the metal gasket can be formed without plating or coating. Even if the contact surface of the member to be sealed with the flange surface is not provided with a projection or a reverse projection, the tightening force can be reduced and good sealing performance can be obtained.

Further, in manufacturing, the metal gasket of the present invention can be manufactured by a method similar to the conventional method, and since plating or coating is not required and projections are not required, a complicated manufacturing process is not required. In addition, it can be manufactured at low cost and is excellent in mass productivity.

[Brief description of drawings]

FIG. 1 shows a first metal gasket according to the present invention.
2 is a plan view of the embodiment of FIG.

2 (a) is a partial cross-sectional perspective view taken along the line AA of FIG. 1, and FIG. 2 (b) is a partial cross-sectional view taken along the line AA of FIG.

FIG. 3 is a partially enlarged cross-sectional view showing a state where the metal gasket of FIG. 1 is used for a flange of a joint such as a pipe.

FIG. 4 (a) and FIG. 4 (b) are partial cross-sectional views showing another embodiment of the metal gasket according to the present invention.

5 (a) and 5 (b) are partial cross-sectional views showing another embodiment of the concave groove of the metal gasket according to the present invention.

6 (a) is a partial cross-sectional perspective view of a second embodiment of the metal gasket according to the present invention, and FIG.
FIG. 6 is a partial cross-sectional view of a second embodiment of the metal gasket according to the present invention.

FIG. 7A is a partial cross-sectional view showing the metal gasket used in Example 1. 7 (b) and 7
(C) is a partial cross-sectional view showing the metal gaskets used in Comparative Example 1 and Comparative Example 2, respectively.

FIG. 8 is a graph showing the results of the compression restoration airtightness test of Example 1.

9 (a) is a partial cross-sectional view of a conventional metal flat gasket, and FIG. 9 (b) is a partial cross-sectional view of a metal flat gasket having a reduced width.

FIG. 10 is a partial cross-sectional view of a conventional metal gasket that has undergone a saw-toothed process.

FIG. 11 is a partial cross-sectional view of a conventional metal O-ring.

FIG. 12 is a partial cross-sectional view of a conventional metal hollow O-ring.

FIG. 13 is a partial cross-sectional view of a conventional metal C ring.

FIG. 14A is a partial cross-sectional view of a conventional spring-loaded metal C ring. FIG. 14B is a partial cross-sectional view of a conventional V-shaped spring-loaded metal C ring with protrusions, and FIG. 14C is a conventional V-shaped inverted metal spring-loaded metal C ring with protrusions. FIG.

[Explanation of symbols]

1 Metal gasket body 10, 18 Metal gasket 11 Outer side surface 12 Outer diameter concave groove 13 Inside surface 14 Inner groove 15 Tip

Claims (4)

[Claims] 1. A metal gasket, wherein a concave groove is provided on a side surface of an outer diameter portion or a side surface of an inner diameter portion of the metal gasket. 2. The metal gasket according to claim 1, wherein the metal gasket has a circular cross section, a vertically elongated elliptical shape, or a horizontally elongated elliptical shape. From wherein the inside diameter portion of the metal gasket of the radial width of the metal gasket to the outer diameter and W _1, among the width W _1, a width excluding the width of the groove and W ₂ The metal gasket according to claim 1 or 2, characterized in that, in this case, W ₁ and W ₂ satisfy W ₂ / W ₁ <1/2. 4. The groove according to claim 1, wherein the groove provided in the metal gasket has a substantially U-shaped cross section, a trapezoidal cross section, or an elliptical cross section. Metal gasket.