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JP-2026074655-A - Sealing structure using metal seals

JP2026074655AJP 2026074655 AJP2026074655 AJP 2026074655AJP-2026074655-A

Abstract

[Problem] To enable the necessary sealing performance with low tightening force, even when using metal seals as a substitute for rubber seals. [Solution] The seal comprises an annular seal body 2, a pair of fork portions 3 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 4 formed at the tips of the pair of fork portions, which contact a pair of flat surfaces 11 and 12 to exhibit sealing performance. The seal body has a radial width W2 of 0.6 mm or more and 1.0 mm or less, the ratio of the thickness t2 at the base of the fork portion to the thickness t1 before the projection is 0.45 or more and 0.70 or less, the ratio of the radial length W1 from the seal body to the tip of the fork portion to the thickness t2 at the base of the fork portion is 0.10 or more and 0.15 or less, and is made of a metal material with a yield strength of 450 N/mm² or more and 1000 N/mm² or less , a tensile strength of 650 N/ mm² or more and 1400 N/ mm² or less, and an HV hardness of 200 or more and 450 or less. [Selection Diagram] Figure 6

Inventors

  • 藤堂 聡
  • 古林 舜平

Assignees

  • 三菱電線工業株式会社

Dates

Publication Date
20260507
Application Date
20241021

Claims (3)

  1. The ring-shaped seal body, A pair of fork portions extending radially from one of the inner and outer circumferential surfaces of the seal body, with their tips separated from each other, Each of the pair of fork sections has a projection formed at its tip that contacts a pair of flat surfaces to provide a sealing effect, 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 in the fork portion to the thickness at the front (t1) 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 (t2) of the base of the fork portion is 0.10 or more and 0.15 or less. A metal seal characterized by being made of a metal material having a yield strength of 450 N/ mm² to 1000 N/ mm² , a tensile strength of 650 N/ mm² to 1400 N/ mm² , and 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.

Description

This invention relates to a metal seal and a sealing structure using the same. Conventionally, a U-shaped metal seal with a compressible and elastically deformable cross-section, primarily made of metal, is known, for example, as described in Patent Document 1. The small projections on the outer side of the opening of this metal seal contact the first and second flat metal surfaces, receiving compressive force and thus providing a sealing effect. Japanese Patent Publication No. 2009-24838 This is a perspective view showing a metal seal according to an embodiment of the present invention.This is a magnified cross-sectional view showing a metal seal sandwiched between a pair of planes.This is a front view showing a metal seal.A plan view showing a metal seal.This is a cross-sectional view taken along line V-V in Figure 4.Figure 5 is an enlarged cross-sectional view of section VI.This table shows the mechanical properties of each material.This is a graph showing the relationship between each material and its reaction force.This is a table comparing the examples and comparative examples.This is a cross-sectional view corresponding to Figure 6, relating to Modification 1.This is a cross-sectional view corresponding to Figure 6, relating to a modified 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. The embodiments of the present invention will be described below with reference to the drawings. 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 continuously in the circumferential direction, and a pair of fork portions 3 extending radially from one of the inner and outer circumferential surfaces of the seal body 2, with their tips separated from each other. 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 provided on a pair of piping members or the like to provide a sealing effect. While the cross-sectional shape of these projections 4 is semicircular, it could also be semi-elliptical, triangular, or rectangular. In this embodiment, the seal body 2 is used in locations where there is little or no pressure difference between the inner and outer diameters of the metal seal 1. 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. Therefore, 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 elongated vertical dimensions, 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. In this embodiment, the ratio of the thickness t2 at the base of the projection 4 to the thickness t1 at the 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. Furthermore, the ratio of the radial length W1 from the seal body 2 to the tip of the fork portion 3 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). In its 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). The metal seal 1 is made of a metallic material with a yield strength of 450 N/ mm² to 1000 N/ mm² , a tensile strength of 650 N/ mm² to 1400 N/ mm² , and an HV hardness of 200 to 450. Examples include, but are not limited to, nickel alloy X-750 and carbon steel S45C. 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. 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, failing to secure the necessary line load and thus unable to exhibit sufficient sealing performance. The area including the projection 4 and its surroundings may be plated with a material softer than the base material made of the aforementioned metal. Specifically, plating with tin, silver, nickel, etc., may be performed. In particular, when plating with a Vickers hardness of 80 or less, such as tin or silver, i