JP2001004028A - Metal gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uneven fastening hard to be caused when the bolt number is remarkably small or a bolt diameter is thin by forming hardness of a ring outer edge part so as to become larger than hardness of a ring inner edge part. SOLUTION: This metal gasket 1 is used for a bolt fastening flange joint, and is composed of a bolt side ring part 2 being the side for installing a fastening bolt and a ring part 3 on the side for flowing fluid of a sealing object. Hardness of upper/lower outer edge parts 2a, 2b of the bolt side ring part 2 is larger than that of upper/lower inner edge parts 3a, 3b of the fluid side ring part 3, and a hardness difference between these is set not less than Hv 20, desirably, not less than 50. Height H of the inner edge parts 3a, 3b is desirably finished higher by 0 to 0.2 mm, desirably, by 0 to 0.05 mm than a height (h) of the outer edge parts 2a, 2b. Uneven fastening can be prevented even when fastened by the small number of bolts or by thin bolts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal gasket, and more particularly to a metal gasket used for a bolted flange joint.

[0002]

2. Description of the Related Art Metal solid gaskets represented by metal flat gaskets and ring joint gaskets have excellent heat resistance, pressure resistance and corrosion resistance, and are used for fluid sealing in a wide range from vacuum to high pressure.

A metal gasket is mounted between flanges constituting a joint and is fastened by a fastening means such as a bolt or a fastening mechanism instead of the bolt.

[0004] When tightened by the fastening means, the metal constituting the flange and the gasket is plastically deformed between the contact surfaces of the flange and the gasket, thereby achieving the seal (sealing) by the gasket.

[0005] However, once the metal material is plastically deformed by being tightened by the fastening means, even if it is tightened again, the seal originally achieved cannot be achieved again. That is, a desired seal cannot be achieved by opening the once-sealed sealing joint, using the flange and gasket as they are, and retightening.

[0006] This is because the metal once plastically deformed undergoes work hardening, and as a result, the hardness increases, so that plastic deformation hardly occurs even when the metal is tightened again. Also,
The surface of the metal material is not actually uniform, so that a portion that is easily plastically deformed in a microscopic sense is plastically deformed at the time of initial fastening. At the time of the next fastening, there is no portion that easily undergoes plastic deformation, so that plastic deformation is unlikely to occur again.

As described above, in a sealed joint, a member for achieving sealing needs to be made of a material which is easily plastically deformed, and an unused product must be used each time the sealed joint is opened and closed.

[0008] In the sealed joint, a metal gasket functions as a sealing member as a replaceable gasket. Then, each time the sealing joint is opened and closed, the metal gasket is replaced. An important property of the material of the metal gasket is that it is easily plastically deformed, and soft metals such as aluminum and copper are often used.

However, from the viewpoint of heat resistance and corrosion resistance,
In some cases, the same material must be selected for the gasket and the flange. For example, if the flange is SUS30
No. 4,316, in which the gasket must use the same austenitic stainless steel.

[0010] Even in such a case, the gasket material is made of SUS3 so that the gasket is more easily plastically deformed than the flange.
04L, 316L, and SUS304,
It is customary to anneal 316 or SUS304L, 316L or to forge the flange to provide a hardness difference between the gasket and the flange.

In the bolted flange joint, the metal gasket thus selected is mounted on the flange, alternately tightened, and the torque is increased stepwise to tighten the bolt, thereby completing the sealing.

[0012]

However, in a bolted flange joint, when the number of bolts is extremely small, it is difficult to uniformly tighten the flanges, and it is easy to perform one-sided tightening, or when the bolt diameter is small, small. Since a large bolt load is generated by the bolt torque, one-sided tightening is likely to occur.

On the other hand, the softness of the gasket facilitates plastic deformation and easily achieves a sealing property, but on the other hand, the gasket is easily deformed and promotes one-sided tightening.

That is, in the case of a bolted flange joint, when the number of bolts is extremely small, when the bolt diameter is small, or when the gasket is soft and easily plastically deformed and easily deformed, it is easy to perform one-sided tightening. There is a problem that cannot be achieved.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a metal gasket which solves the above-mentioned problems of the prior art and hardly causes one-sided tightening even when the number of bolts is extremely small or the bolt diameter is small.

[0016]

To achieve the above object, the metal gasket of the present invention is characterized in that the hardness of the outer edge of the ring is greater than the hardness of the inner edge of the ring.

The hardness of the outer edge of the ring is higher than the hardness of the inner edge of the ring by at least Hv20, preferably Hv50.
It is characterized by being larger.

Further, the outer edge of the ring is work-hardened by forging or physical polishing.

The ring outer edge has a ring height of 0 to 0.2 compared to the ring height of the ring inner edge.
mm, preferably 0 to 0.05 mm.

The ring outer edge is worked and hardened by forging or physical polishing, and the ring outer edge has a ring height of the ring outer edge before the work hardening. Is formed at a height equal to or higher than the ring height.

In the above invention, the metal gasket is mounted between the flanges constituting the bolted flange joint,
When a plurality of bolts are used for fastening, if the bolts on one side are fastened first, the flange and the outer edge of the ring on the fastening bolt contact first, but the hardness of this ring outer edge is high and deformed. Therefore, the inner edge of the ring on the side of the fastening bolt, which is inside the outer edge of the ring, has not yet been plastically deformed.

Next, when the opposite bolt is fastened,
The part where the metal gasket comes into contact with the flange transitions from the ring outer edge on the bolt side tightened earlier to the ring outer edge on the opposite bolt side to be newly tightened. The contact at the outer edge of the ring is opened. Here, since the contact portion of the outer edge portion of the bolt tightened earlier has a high hardness, the inner edge portion of the ring of the bolt tightened earlier has not yet undergone plastic deformation. Then, next, the previously tightened bolt is further tightened, and the tightening torque is gradually increased. By repeating the alternate fastening in this manner, the metal gasket is fastened in parallel, the inner edge of the ring is almost uniformly compressed, and plastic deformation suitable for sealing is obtained.

[0023]

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

FIG. 1 shows a ring-shaped metal gasket 1 according to one embodiment of the present invention. Metal gasket 1
Is a bolt-side ring portion 2 which is used for a bolted flange joint and on which a fastening bolt is mounted.
And a fluid-side ring portion 3 on the side where the fluid to be sealed flows. The hardness of the upper and lower outer edges 2a and 2b of the bolt side ring portion 2 is greater than the hardness of the upper and lower inner edges 3a and 3b of the fluid side ring portion 3. The hardness difference between the hardness of the outer edges 2a and 2b and the hardness of the inner edges 3a and 3b is Hv (Vickers hardness) of 20 or more, and more preferably Hv5.
0 or more.

To increase the hardness of the outer edges 2a, 2b of the bolt-side ring 2 more than the hardness of the inner edges 3a, 3b of the fluid-side ring 3, the workability of the outer edges 2a, 2b is increased.
This is because the working degree is higher than the working degree of a or 3b.

For this purpose, first, a ring-shaped metal gasket is formed by turning or other methods, and then the outer edges 2a and 2b of the ring on the bolt side are forged. Due to such forging, the outer edges 2a, 2b have a higher degree of compression working than the inner edges 3a, 3b. As a result, the hardness of the outer edges 2a, 2b is increased by work hardening, so that the hardness of the inner edges 3a, 3b is further increased.

In order to increase the hardness of the outer edge portions 2a and 2b by work hardening, not only the forging method but also any other finishing method that increases the working degree may be used. Physical polishing, such as polishing by using, is also effective.

Furthermore, in order to make the difference in hardness between the flange and the gasket larger, it is extremely effective to anneal the material of the gasket in a step before the work hardening step by forging or the work hardening step by physical polishing. .

Next, referring to FIG. 4 to FIG.
The relationship between the height H of a and 3b and the height h of the outer edges 2a and 2b will be described.

When the inner edges 3a and 3b of the fluid side ring 3 are subjected to processing such as forging and physical polishing, the inner edges 3a and 3b
work hardening including the b), the inner edge 3
a, 3b and a difference in hardness between the outer edge portions 2a, 2b cannot be formed. In order to prevent this, it is necessary to limit the range in which processing such as forging or physical polishing is performed to the outer edge portions 2a and 2b.

The height h of the outer edges 2a, 2b is the same or smaller than the height H of the inner edges 3a, 3b.

Here, when the metal gasket 1 is fastened in parallel, it is an essential requirement for sealing that the soft inner edges 3a, 3b come into contact with the flange and undergo sufficient plastic deformation. As compared with the height H of the inner edges 3a, 3b, the outer edges 2a,
The small height h of 2b does not hinder the achievement of the seal. However, if the height h of the outer edges 2a, 2b is too small compared to the height H of the inner edges 3a, 3b,
One-sided tightening is likely to occur, and the predetermined sealing performance cannot be achieved. Therefore, the inner edges 3a, 3b of the metal gasket 1
As shown in FIG. 4, the height H of the inner edges 3a, 3b is 0-0.2 mm, preferably 0-0.2 mm, from the height h of the outer edges 2a, 2b. 0.05mm
It is desirable that the finish be as high as possible.

The height H of the inner edges 3a, 3b and the outer edges 2a,
The difference from the height h of 2b is 0 to 0.2 mm, preferably 0 to 0.2 mm.
In order to finish to be 0.05 mm, in consideration of the processing allowance by forging or physical polishing, in the ring forming step before work hardening, as shown in FIG. 5 or FIG. The height h of 2a, 2b is formed higher than the height H of the inner edges 3a, 3b of the fluid side ring 3. FIG. 5 shows a case where the height h of the outer edges 2a, 2b is increased stepwise with respect to the height H of the inner edges 3a, 3b. FIG.
Shows a case where the height h of the outer edges 2a, 2b is continuously increased in a tapered manner with respect to the height H of the inner edges 3a, 3b.

Next, the operation of the present embodiment will be described with reference to FIGS. In FIG. 2, a work hardened portion is displayed as indicated by reference numeral A, and a plastically deformed portion is displayed as indicated by reference numeral B.

FIG. 2 shows a case where the metal gasket 1 according to the present embodiment is mounted between the flange 5 and the flange 6 constituting the bolted flange joint, and is fastened using the bolts 7, 8 and the like. FIG. 3 shows a conventional metal gasket 11 mounted between the flanges 5 and 6 for comparison.
The case of fastening using bolts 7, 8 and the like is shown. The metal gasket 11 includes an outer edge 12 a of the bolt-side ring 12,
12b and inner edges 13a, 13 of the fluid side ring 13
b is formed so that there is no difference in hardness.

First, a case where the metal gasket 1 according to the present embodiment is used will be described with reference to FIG.

FIG. 2A shows a state before the metal gasket 1 is mounted on the bolted flange joints 5 and 6 and is tightened with the bolts 7 and 8. Next, as shown in FIG.
When the bolt 7 on one side is first fastened, the outer edges 2a, 2b on the bolt 7 side to be fastened come into contact with the flanges 5, 6, but are hardly deformed due to the high hardness of the outer edges 2a, 2b, The inner edges 3a, 3b just inside the outer edges 2a, 2b on the bolt 7 side have not yet undergone plastic deformation.

Next, as shown in FIG. 2 (c), when the bolt 8 on the opposite side is fastened, the contact portion between the metal gasket 1 and the flanges 5 and 6 becomes the outer edge of the bolt 7 which has been tightened earlier. From the portions 2a, 2b, the outer edge portions 2a, 2b on the bolt 8 side on the opposite side to be newly tightened are shifted, and the contact portions of the outer edge portions 2a, 2b on the bolt 7 side generated in the first fastening are the surfaces of the flanges 5, 6. Open from.

However, since the contact portions of the outer edges 2a, 2b on the bolt 7 side opened from the surfaces of the flanges 5, 6 are high in hardness, the inner edges 3a, 3b on the bolt 7 side immediately inside the outer edges 2a, 2b. Has not yet reached plastic deformation.

By gradually increasing the tightening torque and repeating such alternate tightening, the metal gasket 1 is tightened in parallel as shown in FIG.
Inner edges 3a, 3b and bolts 8 side inner edges 3a, 3b
Is compressed almost evenly and the inner edge 3 of the metal gasket 1
Plastic deformation suitable for sealing is obtained on the surfaces a and 3b.
In FIG. 2D, the inner edges 3a, 3b of the gasket 1
Is plastically deformed, and is indicated as indicated by reference numeral B. The outer edges 2a, 2b are indicated as indicated by the reference symbol A.

Next, a case where the conventional metal gasket 11 is used will be described with reference to FIG.

The inner edges 13a, 1 of the metal gasket 11
The hardness of the outer edges 3a and the outer edges 12a and 12b is lower than the hardness of the outer edges 2a and 2b of the metal gasket 1. FIG. 3A shows a state where the bolted flange joints 7 and 8 are mounted. Next, as shown in FIG. 3 (b), when the bolt 7 on one side is fastened, the outer edges 12a, 12b on the bolt 7 side are greatly deformed, and at the same time, the inner edges 13a, 13b also accompanies plastic deformation, and so-called one-sided tightening is likely to occur.

As a result, when the bolt 8 on the opposite side is fastened, as shown in FIG.
The plastic deformation portions of the inner edges 13a, 13b of the bolts 7 are opened. Therefore, if you repeat this operation,
As shown in FIG. 3D, no plastic deformation suitable for sealing is obtained on the gasket surface.

As described above, according to the present embodiment, the hardness of the outer edges 2a, 2b of the metal gasket 1
b, the bolts 7 and 8
In the case of fastening by, for example, one-side tightening can be prevented, and plastic deformation suitable for sealing to the gasket 5 and 6 surfaces can be obtained at the inner edges 3a and 3b. And bolt 7,
The number of bolts such as 8
Even when the diameter of 8 is small, one-sided tightening can be made difficult to occur.

The metal gasket 1 is applied to a full surface seat, a flat seat, and a groove flange. When applying to the full seat, the gasket outer diameter should be the same or smaller than the bolt inscribed circle, and when applying to the flat seat,
The outer diameter of the gasket must be the same or smaller than the outer diameter of the flat seat. It is more preferable to apply to a channel-shaped flange from the convenience of mounting.

When applied to a grooved flange,
The effect of heat and external stress can be reduced by closing the flanges 5 and 6 until they come into contact, and excessive deformation of the outer edge can be suppressed by the contact between the flanges 5 and 6 during the fastening.

[0047]

As described above, according to the structure of the present invention,
Since the hardness of the outer edge of the ring is formed larger than the hardness of the inner edge of the ring, when fastening with bolts, it is possible to prevent one-sided tightening, when the number of bolts is extremely small or the bolt diameter is small. Even in such a case, it is possible to make it difficult to perform one-sided tightening.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a metal gasket according to the present invention.

FIG. 2 is a diagram illustrating the operation of the metal gasket according to the present invention.

FIG. 3 is a view for explaining the operation of a conventional metal gasket for comparison with FIG. 2;

FIG. 4 is a sectional view showing one embodiment of a metal gasket according to the present invention.

FIG. 5 is a sectional view showing an example of a shape of the metal gasket according to the present invention before work hardening.

FIG. 6 is a cross-sectional view showing another example of the shape of the metal gasket according to the present invention before work hardening.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal gasket 2 Bolt side ring part 2a, 2b Ring outer edge part 3 Fluid side ring part 3a, 3b Ring inner edge part 5, 6 Flange 7, 8 bolt

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J040 AA01 AA12 AA15 BA04 EA15 EA17 EA50 FA02 HA01 HA03 HA06 HA07 HA09 4E087 HB08

Claims (5)

[Claims] 1. A metal gasket, wherein the hardness of the outer edge of the ring is greater than the hardness of the inner edge of the ring. 2. The metal gasket according to claim 1, wherein the hardness of the outer edge of the ring is higher than the hardness of the inner edge of the ring by at least Hv20. 3. The metal gasket according to claim 1, wherein the outer edge of the ring is worked and hardened by forging or physical polishing. 4. The ring outer edge has a ring height of 0 to 0.05 m compared to the ring height of the ring inner edge.
2. The semiconductor device according to claim 1, wherein the distance is smaller by m.
Metal gasket as described in. 5. The ring outer edge portion is hardened by forging or physical polishing, and the ring outer edge portion has a ring height of the ring inner edge portion before the work hardening. The metal gasket according to claim 1, wherein the metal gasket is formed at a height equal to or higher than the ring height.