Metal seal and sealing structure using same

Abstract

This metal seal comprises: an annular seal body (2); a pair of fork portions (3) extending in a radial direction from either an inner peripheral surface or an outer peripheral surface of the seal body so that tips are spaced apart from each other; and projection portions (4) respectively formed at the tips of the pair of fork portions and brought into contact with a pair of flat surfaces (11, 12) at an installation site to exhibit seal performance. The width (W2) in the radial direction of the seal body is 0.6 to 1.0 mm, the ratio of a thickness (t2) of a root of the fork portion to a front thickness (t1) of the projection portion is 0.45 to 0.70, and the ratio of the length (W1) in the radial direction from the seal body to the tip of the fork portion to the thickness (t2) of the root of the fork portion is 0.10 to 0.15. The metal seal is composed of a metallic material having a yield strength of 450N / mm2 to 1,000N / mm2 or less, a tensile strength of 650N / mm2 to 1,400N / mm2 or less, and an HV hardness of 200 to 450.

Description

Metal Seal and Sealing Structure Using the Same

[0001] The present invention relates to a metal seal and a sealing structure using the same.

[0002] Conventionally, for example, as disclosed in Japanese Patent Application Laid-Open No. 2009-24838, a compression-elasticity deformable U-shaped metal seal having a metal as a main material is known. The small protrusions on the outer side of the opening side of this metal seal come into contact with the first and second metal flat surfaces to receive a compressive force and perform a sealing action.

[0003] However, since the conventional metal seal is used in applications where internal pressure is applied, the seal body and the fork portion are made thick in order to prevent plastic deformation or breakage due to internal pressure.

[0004] Then, in order to deform the fork portion so as to exhibit seal performance, for example, a high tightening force of 33 to 70 N / mm was required.

[0005] In order to exert such a high tightening force, it is necessary to increase the size and number of fastening bolts compared to the case of tightening a rubber seal, and there is a problem that the device must be significantly changed from the configuration in the case of a rubber seal.

[0006] The present invention has been made in view of such points, and an object thereof is to be able to exhibit required seal performance with a relatively low tightening force even when a metal seal is used as an alternative to a rubber seal, and to be able to use it without significant design changes.

[0007] In order to achieve the above object, in this invention, the seal body and the fork portion are made thin, and the metal seal is constituted by a metal material having high mechanical strength.

[0008] Specifically, the first invention comprises: an annular seal body; a pair of fork portions extending radially from one of the inner and outer circumferential surfaces of the seal body such that their tips are separated from each other; and projections formed at the tips of each of the pair of fork portions, which contact a pair of flat surfaces of the installation site to provide sealing performance; the radial width (W2) of the seal body is 0.6 mm or more and 1.0 mm or less; the ratio (t1 / t2) of the thickness at the base (t2) of the projection on the fork portion to the thickness (t1) before the projection is 0.45 or more and 0.70 or less; the ratio (t2 / W1) of the radial length W1 from the seal body to the tip of the projection on the fork portion to the thickness (t2) at the base (t2) of the fork portion is 0.10 or more and 0.15 or less; and the yield strength is 450 N / mm ２ More than 1000N / mm ２ The following is a tensile strength of 650 N / mm ２ More than 1400N / mm ２ It is composed of the following metal materials with an HV hardness of 200 to 450.

[0009] According to the above configuration, since the metal seal is made of a metal material with high mechanical strength and moderate Vickers hardness (HV hardness), the seal body and fork portion can be made thinner in situations where almost no internal pressure is applied, and as a result, the required sealing performance can be ensured with a low fastening force.

[0010] In the second invention, in the first invention, at least the projection and its surrounding area are plated with a material softer than the metal material.

[0011] In the above configuration, if a plating material softer than the metal material of the first invention, particularly one with a Vickers hardness of 80 or less such as "tin," is applied, minute irregularities on the surface of the pair of flat surfaces where the metal seal is installed are filled in by the plating, resulting in sufficient sealing performance with a smaller reaction force.

[0012] In the sealing structure using the metal seal of the third invention, the clamping force when the metal seal of the first or second invention is sandwiched between a pair of flat surfaces is 20 N / mm or less, and the sealing performance is achieved when there is no pressure difference between the inside and outside of the metal seal.

[0013] According to the above configuration, even in situations where no internal pressure is applied to the metal seal, and in environments where corrosion resistance is required and rubber seals cannot be used, the necessary sealing performance can be ensured with a low fastening force. "A state in which there is no pressure difference between the inside and outside of the metal seal" does not mean that the pressure difference must be completely zero; a small pressure difference is acceptable.

[0014] As explained above, according to the present invention, even when a metal seal is used as a substitute for a rubber seal, the required sealing performance can be achieved with a low tightening force.

[0015] This is a perspective view showing a metal seal according to an embodiment of the present invention. This is an enlarged cross-sectional view showing the metal seal sandwiched between a pair of planes. This is a front view showing the metal seal. This is a plan view showing the metal seal. This is a cross-sectional view taken along line V-V in Figure 4. This is an enlarged cross-sectional view of section VI in Figure 5. This is a table showing the mechanical properties of each material. This is a graph showing the reaction forces for each material. This is a table comparing the examples and comparative examples. This is a cross-sectional view corresponding to Figure 6 for Modification Example 1. This is a cross-sectional view corresponding to Figure 6 for Modification Example 2. This is a cross-sectional view of the metal seal of Comparative Example 1. This is a cross-sectional view of the metal seal of Comparative Example 2.

[0016] Embodiments of the present invention will be described below with reference to the drawings.

[0017] Figure 1 shows a metal seal 1 according to an embodiment of the present invention. This metal seal 1 comprises an annular seal body 2 having substantially the same cross-sectional shape continuous in the circumferential direction, and a pair of fork portions 3 extending radially from either the inner or outer circumferential surface of the seal body 2, with their tips separated from each other. In this embodiment, the pair of fork portions 3 extend from the inner circumferential surface of the seal body 2 toward the center of the metal seal 1. Alternatively, the pair of fork portions 3 may extend radially outward from the outer circumferential surface of the seal body 2.

[0018] As shown in Figure 2, the tips of these pair of fork portions 3 each have projections 4 that contact a pair of flat surfaces 11 and 12, which are provided on a pair of piping members or the like, and are sandwiched between them to provide a sealing performance. The cross-sectional shape of these projections 4 is semicircular, but it may also be semi-elliptical, triangular, or rectangular.

[0019] In this embodiment, the seal body 2 is used in locations where there is no or small pressure difference between the inner and outer diameter sides of the metal seal 1, and the radial width W2 of the seal body 2 is 0.6 mm or more and 1.0 mm or less (0.6 ≤ W2 ≤ 1.0). Preferably, the width W2 is 0.7 ≤ W2 ≤ 0.9 or less. For this reason, the width W2 of the seal body 2 is smaller than that of conventional metal seals. The height H2 of the seal body 2 is, for example, 1.76 mm. The shape of the seal body 2 is not particularly limited, but in this embodiment, it is generally rectangular in cross-section with a long vertical orientation, and chamfers are formed at the four corners of the rectangular cross-section. Even in the usage state shown in Figure 2, the seal body 2 is basically used so as not to touch the pair of flat surfaces 11 and 12.

[0020] In this embodiment, the ratio of the thickness t2 at the base of the projection 4 to the thickness t1 in front of the projection 4 in the fork portion 3 is 0.45 or more and 0.70 or less (0.45 ≤ t1 / t2 ≤ 0.70). Preferably, it is 0.50 ≤ t1 / t2 ≤ 0.60.

[0021] Furthermore, the ratio of the radial length W1 of the fork portion 3 from the seal body 2 to the tip to the thickness t2 at the base of the fork portion 3 is 0.10 or more and 0.15 or less (0.10 ≤ t2 / W1 ≤ 0.15).

[0022] In an uncompressed state, the maximum height H1 of the fork section 3 is, for example, 2.41 mm, and the value of t2 / H1 is between 0.100 and 0.125 (0.100 ≤ t2 / H1 ≤ 0.125).

[0023] Metal seal 1 has a yield strength of 450 N / mm². ２ More than 1000N / mm ２ The following is a tensile strength of 650 N / mm ２ More than 1400N / mm ２The following materials are composed of metallic materials with an HV hardness of 200 to 450. Examples include, but are not limited to, nickel alloy X-750 and carbon steel S45C.

[0024] As shown in Figure 7A, the yield strength, tensile strength, and HV hardness decrease in the order of X-750, S45C, and SUS316L. As can be seen from this, the mechanical properties of SUS316L are inferior to those of X-750 and S45C.

[0025] As shown in Figure 7B, when a metal seal identical in shape to the metal seal 1, but without plating, is prepared between a pair of flat surfaces 11 and 12, and the set height is gradually reduced, the reaction force (line load) decreases in the order of X-750, S45C, and SUS316L. In particular, the reaction force of SUS316L never exceeds 7 N / mm, and the necessary line load cannot be secured, so it cannot exhibit sufficient sealing performance.

[0026] The area including the projection 4 and its surroundings may be plated with a material softer than the base material made of the metal. Specifically, plating with tin, silver, nickel, etc. is performed. In particular, when plating with a Vickers hardness of 80 or less, such as tin or silver, is applied, it is thought that the material can easily penetrate due to the surface irregularities of the pair of flat surfaces 11 and 12, and the sealing performance is further improved. The thickness of the plating is not particularly limited, but a plating of an appropriate thickness is applied according to the size of the metal seal 1.

[0027] In the sealing structure of this embodiment shown in Figure 2, when the metal seal 1 is sandwiched between a pair of flat surfaces 11 and 12, the clamping force of the pair of flat surfaces 11 and 12 is 20 N / mm or less, with only the pair of fork portions 3 in contact with the pair of flat surfaces 11 and 12. In this state, sealing performance is achieved with no pressure difference between the inside and outside of the metal seal 1. As a result, the fluid on the inner diameter side and the fluid on the outer diameter side of the metal seal 1, where there is little to no pressure difference, do not mix.

[0028] -Examples- Figure 8 shows a table comparing the metal seals of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 of the present invention.

[0029] Example 1 is a metal seal without plating, as described above for the metal seal 1. Example 2 is the metal seal 1 described above, but with tin plating.

[0030] Comparative Example 1 is a metal seal 101 as shown in Figure 11, in which the width W2 of the seal body 102 is large at 1.40 mm. The height H2 of the seal body 102 is, for example, 1.96 mm. On the other hand, the length W1 of the pair of fork portions 103 is short at 1.40 mm, and the maximum height H1 is 2.41 mm. Compared to Examples 1 and 2, this metal seal 101 is intended for use in applications where internal pressure is applied. This metal seal 101 is silver-plated. The t1 / t2 value of the fork portion 103 is 0.73, and it does not taper as much towards the tip compared to Examples 1 and 2. Thus, it has a relatively rigid structure so that the fork portion 103 does not undergo plastic deformation or break due to internal pressure.

[0031] Comparative Example 2 is a metal seal 201 as shown in Figure 12, used in applications where internal pressure is applied. The seal body 202 is not as thick as the pair of fork portions 203 as in Examples 1 and 2 and Comparative Example 1, and its width W2 is about 1.15 mm. The height H2 of the seal body 202 is 3.27 mm. The length W1 of the fork portion 203 is 4.25 mm, and the maximum height H1 is 3.925 mm, which is larger in size compared to the other examples. On the other hand, the value of t1 / t2 is 0.85, and it does not become very thin towards the tip. Thus, Comparative Example 2 also has a relatively rigid structure so that the fork portion 203 does not undergo plastic deformation or break due to internal pressure.

[0032] Then, for these examples and comparative examples, as shown in Figure 2, the reaction force was measured when the set height was gradually reduced while the product was sandwiched between a pair of flat surfaces 11 and 12. This allowed us to determine the reaction force at the set height that provided the required sealing performance. For example, in Examples 1 and 2, as shown in Figure 7B, the reaction force was measured when the set height was narrowed from approximately 2.4 mm to 1.9 mm. The reaction force that provided the required sealing performance was 17 N / mm at a set height of 2.00 mm in Example 1, but decreased to 10 N / mm at a set height of 2.32 mm in Example 2, which was tin-plated.

[0033] This is thought to be because the tin in the tin plating is more effective at filling in minute irregularities on the surfaces of the pair of flat surfaces 11 and 12, thus enabling the required sealing performance to be achieved with less force.

[0034] On the other hand, when similar tests were conducted on Comparative Examples 1 and 2, and the set height was lowered until the required sealing performance was achieved, the measured reaction force in Comparative Example 1 was 36 to 39 N / mm when the set height was 2.10 mm to 2.15 mm, which was more than twice as large as that of Example 1. Furthermore, in Comparative Example 2, the measured reaction force was 50 to 55 N / mm when the set height was 3.40 mm to 3.45 mm, which was approximately three times as large as that of Example 1.

[0035] Thus, in this embodiment, the metal seal 1 is constructed from a metal material such as X-750, which has high mechanical strength and appropriate HV hardness. Therefore, in situations where there is virtually no internal pressure, the seal body 2 and the fork portion 3 can be made thinner, and as a result, the required sealing performance can be ensured with a low fastening force.

[0036] In this embodiment, a plating softer than the base material may be applied to the area including the projection 4 that contacts the pair of flat surfaces 11 and 12 and its surrounding area. In particular, when a plating with a Vickers hardness of 80 or less, such as tin or silver, is applied, minute irregularities on the flange side are filled in by the plating, and sufficient sealing performance is achieved with a smaller reaction force.

[0037] In this embodiment, even in a situation where no internal pressure is applied to the metal seal 1 and in an environment where corrosion resistance is required more than that of a rubber seal, the required sealing performance can be ensured with a low fastening force.

[0038] Therefore, according to the metal seal 1 according to this embodiment, even when the metal seal 1 is used as an alternative to the rubber seal, the required sealing performance can be exhibited with a low tightening force.

[0039] - Modification Example 1 - FIG. 9 shows a metal seal 1' according to Modification Example 1 of the embodiment of the present invention, which is different from the above embodiment in that the shape of the seal body 2' is different. In each of the following modification examples, the same parts as those in FIGS. 1 to 6 are denoted by the same reference numerals and the detailed description thereof is omitted.

[0040] The seal body 2' of the metal seal 1' according to Modification Example 1 has no chamfer, and the slopes of the upper and lower surfaces of the fork portion 3 are continuous with the upper and lower surfaces of the seal body 2' as they are. Even with such a shape, the same operational effects as those of the above embodiment can be achieved.

[0041] - Modification Example 2 - FIG. 10 shows a metal seal 1'' according to Modification Example 2 of the embodiment of the present invention, which is different from the above embodiment in that the shape of the seal body 2'' is different.

[0042] The seal body 2'' of the metal seal 1'' according to Modification Example 2 has no chamfer at the four corners and has a rectangular shape. Even with such a shape, the same operational effects as those of the above embodiment can be achieved.

[0043] In addition, the above embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

[0044] 1 Metal seal 2 Seal body 3 Fork portion 4 Projection 11, 12 Flat surface

Claims

1. The seal comprises an annular seal body, a pair of fork portions extending radially from one of the inner and outer circumferential surfaces of the seal body such that their tips are separated from each other, and projections formed at the tips of each pair of fork portions, which contact a pair of flat surfaces of the installation site to provide sealing performance, wherein the radial width (W2) of the seal body is 0.6 mm or more and 1.0 mm or less, the ratio (t1 / t2) of the thickness at the base (t2) of the projection on the fork portion to the thickness (t1) in front of the projection is 0.45 or more and 0.70 or less, the ratio (t2 / W1) of the radial length W1 from the seal body to the tip to the thickness at the base (t2) of the fork portion is 0.10 or more and 0.15 or less, and the yield strength is 450 N / mm ２ More than 1000N / mm ２ The following is a tensile strength of 650 N / mm ２ More than 1400N / mm ２ A metal seal characterized by being composed of the following and a metal material with an HV hardness of 200 to 450.

2. The metal seal according to claim 1, characterized in that at least the projection and its surrounding area are plated with a material softer than the metal material.

3. A sealing structure using a metal seal, characterized in that when the metal seal described in claim 1 or 2 is sandwiched between a pair of flat surfaces, only the pair of fork portions are in contact with the pair of flat surfaces, the clamping force of the pair of flat surfaces is 20 N / mm or less, and the sealing performance is achieved when there is no pressure difference between the inside and outside of the metal seal.

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