JP3391807B2 - Metal gasket - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket,
In particular, the present invention relates to a metal gasket suitable for a cylinder head gasket or the like of an internal combustion engine by applying a coating layer to a metal substrate. It is well known that a gasket is interposed between joining members in order to prevent leakage of a pressure fluid from a joining surface. For example, a gasket is provided between a cylinder head and a cylinder block of an internal combustion engine. A cylinder head gasket is interposed between them. With regard to this type of gasket, a metal gasket made of a metal plate has recently been receiving attention. For example, Japanese Utility Model Laid-Open Publication No. 61-41960 discloses a method in which a vulcanized first coating layer is coated on the surface of a bead formed on an elastic metal plate, and a non-vulcanized second coating layer is formed thereon. A metal gasket is disclosed that is applied to form two paint layers. Further, Japanese Utility Model Laid-Open No. 1-146064 discloses a metal gasket in which an unvulcanized coating layer containing a vulcanizing agent is applied on a substrate of an elastic metal plate. still,
In the latter publication, a softened layer containing no vulcanizing agent is defined as a non-vulcanized layer, and a softened layer containing a vulcanizing agent and not yet subjected to a vulcanization treatment is defined as an unvulcanized layer. The real opening 61
In Japanese Patent No. 41960, vulcanization and non-vulcanization are distinguished in the same meaning. Further, Japanese Patent Application Laid-Open No. 2-227217 discloses that the metal gasket described in Japanese Utility Model Application Laid-Open No. 61-41960 has weak adhesion between the vulcanized rubber layer and the non-vulcanized rubber layer and causes peeling. There is a possibility that this may occur, and the manufacturing process is complicated and requires a long time, and a method for solving this problem has been proposed. That is, after forming a vulcanizing agent layer containing a vulcanizing agent on the material surface, a non-vulcanized rubber layer is formed on the vulcanizing agent layer, and the non-vulcanized rubber layer is vulcanized. This is a method of forming a vulcanized rubber layer in which the degree of vulcanization becomes smaller toward the surface side of the rubber layer. SUMMARY OF THE INVENTION [0005] Japanese Unexamined Utility Model Publication No. 1-14606.
In the metal gasket described in Japanese Patent Publication No.
In a metal gasket in which a non-vulcanized second coating layer is applied on a vulcanized first coating layer described in JP-A-41960, the problem is that the non-vulcanized layer flows out and the sealing performance deteriorates, An unvulcanized coating layer is to be applied to simultaneously satisfy the properties and durability. However, since the unvulcanized coating layer is gradually heated and hardened after being mounted between the fastening members, the bonding strength between the vulcanized coating layer and the unvulcanized coating layer before mounting is sufficient. I can't say. For this reason, it is necessary to pay attention to handling during transportation and assembly. In particular, since the unvulcanized coating layer has fluidity, there is a possibility that the unvulcanized coating layer may flow out of the portion of the metal gasket before the unvulcanized coating layer is heated and hardened at a portion that receives a high compression force at the time of tightening. . Also, after applying and applying a vulcanized coating layer to the substrate, the temperature is raised and vulcanization is performed,
This is a step of applying an unvulcanized coating layer thereon, and is unlikely to be a continuous step. On the other hand, according to the method described in JP-A-2-227217, the vulcanizing agent in the vulcanizing agent layer is compounded while diffusing into the non-vulcanized rubber layer to form a vulcanized rubber layer. Therefore, sealing performance and durability can be ensured, and the manufacturing process is simplified. However, since the diffusion of the vulcanizing agent into the non-vulcanized rubber layer depends on various conditions such as the thickness of the vulcanizing agent layer and the temperature, it is not always easy to make the uniformity in each metal gasket. . For this reason, the distribution in the vulcanized rubber layer varies among products, and it is difficult to ensure a certain quality. Accordingly, the present invention provides a metal gasket for coating a metal substrate with a coating layer, the first and second coating layers each containing a predetermined amount of a vulcanizing agent being appropriately coated on the substrate. It is another object of the present invention to ensure the sealing performance while maintaining the durability of these coating layers. [0009] In order to achieve the above object, the present invention provides a method in which at least one surface of a metal substrate is provided with a predetermined amount of a vulcanizing agent necessary for vulcanization and curing. A first coating layer containing a second vulcanizing agent is coated on the first coating layer, the second vulcanizing agent containing a vulcanizing agent in a predetermined ratio of less than 1 with respect to the predetermined amount of the vulcanizing agent. And vulcanizing the second coating layer and the first coating layer. In the metal gasket described above, it is preferable that the second coating layer and the first coating layer are simultaneously vulcanized. Further, the ratio of the vulcanizing agent contained in the second coating layer is preferably 10% to 80% of a predetermined amount of the vulcanizing agent contained in the first coating layer. In the metal gasket having the above structure,
When the first and second coating layers are vulcanized, the first coating layer adheres and cures to the surface of the substrate, and the second coating layer adheres and cures to this. At this time, the second coating layer contains only a predetermined ratio of the vulcanizing agent less than 1 with respect to the vulcanizing agent contained in the first coating layer. As a result, the first coating layer is in close contact with the first coating layer, and has good flexibility and good sealing properties with respect to the joint surface. In addition, by adjusting the amount of the vulcanizing agent in the second coating layer to a constant amount, the metal gasket can be maintained and managed at a constant quality. Even if the metal gasket is interposed between the joining members facing each other, for example, between the cylinder head and the cylinder block, and the two are fastened with a predetermined tightening force, the second The coating layer is surely adhered to the joining surface without flowing out, and fine irregularities on the joining surface are absorbed by the second coating layer, so that good sealing properties are secured. If the first and second coating layers are simultaneously vulcanized, the bonding strength between the two coating layers increases, so that the interposition between the bonding members having a large difference in coefficient of thermal expansion. Even with this, there is no possibility of peeling, and better durability can be obtained. An embodiment of a metal gasket according to the present invention will be described below with reference to the drawings. FIG. 1 shows, as one embodiment of the present invention, a cross section of a metal gasket provided for a cylinder head gasket of an internal combustion engine, which has a substrate 1 formed of an elastic metal plate, for example, a stainless steel plate (SUS). For example, as shown in FIG. 2, a combustion chamber hole 1a, a bolt hole 1b, a cooling water hole (not shown), a lubricating oil hole (not shown) and the like are formed. A bead 1c is formed around the combustion chamber hole 1a. As shown in FIG. 1, a coating layer of an unvulcanized fluoro rubber to which a predetermined amount (vulcanization equivalent) required for vulcanization and curing is added on the surface of the substrate 1 is vulcanized. After the treatment, a vulcanized coating layer 2 is formed on the entire surface, and a semi-vulcanized coating layer 3 is laminated thereon. Here, the unvulcanized coating layer refers to a layer that contains a vulcanizing agent but has not been vulcanized as described above. Further, the semi-vulcanized coating layer is a vulcanizing agent having a predetermined ratio of less than 1 to the vulcanizing agent of the vulcanizing equivalent of the vulcanized coating layer 2, that is, it is not suitable for curing like the vulcanized coating layer 2. A vulcanization treatment in which a sufficient amount of a vulcanizing agent is added. Next, a process for manufacturing the metal gasket having the above-described structure will be described. First, a predetermined amount (100 parts) of a fluororubber is added with a predetermined amount necessary for vulcanization and curing, that is, a vulcanizing agent of a vulcanizing equivalent (for example, 5 parts) and applied to the surface of the substrate 1. A coating layer having a predetermined thickness (for example, 10 μm) is applied. Subsequently, on this, 10% with respect to the vulcanization equivalent
(0.5 parts) to 80% (4 parts) of a fluororubber containing a vulcanizing agent is applied, and a coating layer having a predetermined thickness (10 μm) is applied. Then, the substrate 1 coated with these coating layers is placed in a vulcanizing furnace (not shown) and heated to vulcanize. As a result, as shown in FIG. 1, the vulcanized coating layer 2 is formed in close contact with the surface of the substrate 1, and the semi-vulcanized coating layer 3 is further formed in close contact with this. Since the semi-vulcanized coating layer 3 is vulcanized by containing a predetermined amount of a vulcanizing agent, fluidity is suppressed, and there is no possibility that the semi-vulcanized coating layer 3 flows out of the vulcanized coating layer 2. In addition, since the vulcanizing agent is less than the vulcanizing equivalent, it has flexibility and a sufficient sealing property to the joint surface is reserved. The ratio of the semi-vulcanized coating layer 3 to the vulcanization equivalent is a predetermined value within the range of 10% to 80% from the characteristics of FIG. 3 showing the relationship between the flow resistance and the sealing force and the amount of the vulcanizing agent. Set to percentage. A more desirable ratio is 40 to 80%. In FIG. 3, 100% indicates a vulcanization equivalent, and when a vulcanizing agent more than this is added, the coating layer is cured to form a vulcanized coating layer. As described above, the amount of the vulcanizing agent to be added to the semi-vulcanized coating layer 3 can be measured in the form of a predetermined ratio to the vulcanization equivalent. Quality can be maintained and managed. The metal gasket having the above structure is disposed between a cylinder head (not shown) made of, for example, aluminum die casting and a cylinder block (not shown) made of cast iron. When a tightening force is applied between the blocks, the semi-vulcanized coating layers 3 and 3 come into close contact with both joint surfaces. Thereby, even if there are minute irregularities on the joining surface, the semi-vulcanized coating layer 3 absorbs the unevenness, so that a good sealing property is secured. And even if it is interposed between joining members having a large difference in the coefficient of thermal expansion, such as aluminum die cast and cast iron, good durability can be obtained without peeling. In the above embodiment, the vulcanized coating layer 2 and the semi-vulcanized coating layer 3 are formed on both the front and back surfaces of the substrate 1. However, both coating layers are formed only on one surface and the other is formed. No coating layer may be formed on the surface, or only various coating layers such as the vulcanized coating layer 2 may be formed. Alternatively, the vulcanized coating layer 2 may be formed after applying a primer to the surface of the substrate 1. Further, the number of substrates is not limited to one and can be used as a laminated structure. The present invention is configured as described above, and has the following effects. That is, in the metal gasket of the present invention, the vulcanization treatment cures the first coating layer in close contact with the surface of the base material, and cures the first coating layer at a predetermined ratio of less than 1 to the vulcanizing agent of the first coating layer. Not only does the second coating layer containing the vulcanizing agent adhere to the first coating layer and has good durability, but also the second coating layer is rich in flexibility even after vulcanization, so that it is bonded. Good sealing performance can be ensured for the surface. In addition, by adjusting the amount of the vulcanizing agent for the second coating layer to a constant amount, the metal gasket can be maintained and controlled at a constant quality, so that the production is easy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross-sectional view of a metal gasket according to one embodiment of the present invention. FIG. 2 is a plan view of a part of the metal gasket according to one embodiment of the present invention. FIG. 3 is a graph showing the relationship between the amount of a vulcanizing agent and the flow resistance and sealability in one example of the present invention. [Description of Signs] 1 Substrate 2 Vulcanized coating layer (first coating layer) 3 Semi-vulcanized coating layer (second coating layer)

   ────────────────────────────────────────────────── ─── Continuation of front page    (73) Patent holder 000142436               Kinyosha Co., Ltd.               1-324 Osaki, Shinagawa-ku, Tokyo (72) Inventor Kazuhiko Tateishi               1-324 Osaki, Shinagawa-ku, Tokyo Stock               Company Kimyang company (72) Inventor Zenichi Shinbo               1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor               Dosha Co., Ltd. (72) Inventor Kazuya Nakata               1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor               Dosha Co., Ltd. (72) Inventor Hironao Daito               3308 Exit, Kumagaya-shi, Saitama                 Nippon Metal Gasket Co., Ltd. (72) Inventor Osamu Jinno               3-65 Midorigaoka, Toyota-shi, Aichi               Industrial Co., Ltd.                (56) References JP-A-2-227217 (JP, A)                 JP-A-58-118373 (JP, A)                 JP-A-2-38760 (JP, A)                 JP-A-3-197135 (JP, A)                 JP-A-63-264691 (JP, A)                 Hirakai 1-146064 (JP, U)                 Shokai 61-61960 (JP, U)

Claims (1)

(57) [Claim 1] At least one surface of a metal substrate is coated with a first coating layer containing a predetermined amount of a vulcanizing agent necessary for vulcanization and curing. And applying a second coating layer containing a predetermined ratio of less than 1 to the predetermined amount of the vulcanizing agent on the first coating layer, the second coating layer And a metal gasket obtained by vulcanizing the first coating layer.