JPH08312785A - Metallic gasket and manufacture thereof - Google Patents

Abstract

PURPOSE: To improve sealing performance of a metallic gasket wherein after a blanking processing, such as a fluid flow hole and a bolt hole, and molding processing, such as a bead and a folding, to produce a difference in a level and an inclination part are applied on a metallic sheet, the surface of the metallic sheet is covered with a sealant layer. CONSTITUTION: A metallic gasket consists of at least a single metallic sheet, a metallic sheet 2 has fluid flow holes 5 and 6 and a bolt hole, and a difference in level and an inclination part, such as beads 9 and 10, with which the fluid flow hole is surrounded are provided. A sealant layer 12 with which the surface of the metallic sheet 2 is covered is applied on the surface of the metallic sheet for covering after blanking processing of the fluid flow hole and the bolt hole and molding processing of the beads to produce a difference in level and inclination are applied on the metallic sheet 2. The sealant layer has hardness of 68-82 according to hardness specified in JISK6301.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket used as, for example, a cylinder head gasket of an engine and a method for manufacturing the same.

[0002]

2. Description of the Related Art For example, in an engine cylinder head metal gasket or the like, irregularities such as roughness, distortion, and scratches on the metal surface are present between the outer surface of the gasket that abuts the surface to be sealed and the metal plate that constitutes the gasket. It is well known and widely practiced to coat a sealing material layer made of vulcanized rubber for a so-called microseal that compensates for the above.

Conventionally, in order to manufacture a metal gasket having such a seal material layer, first, a flat metal plate is coated with the seal material layer and vulcanized, and then a fluid passage hole such as a cylinder bore or a fluid passage hole is formed. Punching of the bolt holes and the outer periphery of the gasket and processing of forming beads, folds, etc., which surround and seal the fluid circulation holes, have been performed. Therefore, the sealing material layer needs to withstand handling and machining after coating, and normally, a relatively hard rubber having a hardness of 90 or more according to JIS K6301 was used.

[0004]

However, it is often expensive to coat a flat metal plate with a sealing material layer and then punch out fluid passage holes, bolt holes, gasket outer circumference, etc. Since it is wasteful and uneconomical, it is considered to coat the sealing material layer after machining such as punching. In this case, the punching process for the fluid flow holes and the like and the forming process for the beads and folds that cause a step or inclination in the metal plate are divided, and the sealing material layer is covered after the punching process, and then the bead and folds are formed. Although it is possible to perform the forming process, the pressing process is divided into two, resulting in an increase in cost. Therefore, in addition to punching, after performing steps to create steps and inclinations on the metal plate that forms beads, folds, etc.,
It is desired to coat the surface of the metal plate with a sealing material layer.

However, in this case, since the sealing material layer is coated on the metal plate having a step or an inclination due to the formation of beads, folds, etc., it is unavoidable that the film thickness of the sealing material layer varies considerably. . Therefore, when the sealing material layer is relatively hard as in the conventional case, it is difficult to obtain sufficient sealing properties, and it is necessary to make the sealing material layer softer than in the conventional case.
On the other hand, if the sealing material layer is too soft, after the gasket is assembled between the surfaces to be sealed, flow of the sealing material layer occurs in the direction perpendicular to the tightening force of the bolts, that is, in the direction parallel to the sealing surface, and the coating film is formed. There is a risk of destruction and it seems that high pressure fluid cannot be sealed.

The inventor of the present application paid attention to the above points, and as a result of the research, punched the fluid circulation hole, the bolt hole and the outer periphery of the gasket, and formed the metal plate such as a bead or a fold that causes a step or an inclination. After that, in the case of covering the metal plate with the seal material layer, the optimum hardness range of the seal material layer in which the sealability and the flow resistance are balanced is clarified,
The present invention has been completed.

[0007]

The metal gasket of the present invention comprises at least one metal plate, and the metal plate has a fluid passage hole and a bolt hole, and a bead for folding and surrounding the fluid passage hole and a folded back. A sealing material layer made of vulcanized rubber on the surface of the metal plate, which is provided with a step or an inclined portion such as the above, after the punching of the hole and the forming of the step or the inclined portion, has a hardness of 68 to 82 specified by JISK6301.
It is characterized by being.

Further, the method for manufacturing a metal gasket according to the present invention includes a punching process for punching a fluid flow hole and a bolt hole, and a process for forming a step or a sloped portion such as a bead and a turn that surrounds and seals the fluid flow hole. After applying to a metal plate, a vulcanizable rubber paint in which a rubber, a vulcanizing agent, etc. are dissolved in a solvent is applied to the surface of the metal plate, and then the coating film is heated and vulcanized to JIS K6301 on the surface of the metal plate. 6 with the specified hardness
A sealing material layer having a hardness of 8 to 82 is formed.

[0009]

EXAMPLES First, experimental examples of the present invention will be described. First, 0.25 mm thick SUS 301 CSP
A step bead of a 3 / 4H stainless steel plate, having a diameter of 55 mm and a step (height) of 0.45 mm and a width of 2.2 mm surrounding the water hole at a distance of 1.4 mm from the outer periphery of the water hole. After preparing a gasket sample of the provided single plate, a rubber paint in which fluororubber (Viton E60C manufactured by DuPont) was dissolved in a solvent was applied to both surfaces of the sample, dried, and then vulcanized to obtain various types shown in Table 1. Hardness (JISK
A sealing material layer having a film thickness of 27 μm and having a hardness of 6301 normal) was formed. The rubber hardness of the sealing material layer was adjusted by the filling amount of the filled carbon.

The above gasket samples were subjected to a water pressure test under various tightening forces shown in Table 1 to determine a water pressure (kg / cm ² ) at which sealing was possible. Whether or not the seal was possible was visually determined by using a white paint Super Check (trade name of Mark Tech Co., Ltd.) that easily dissolves in water. The tightening force was measured by a load cell, and the water was pressurized by a manual pump. The test results are as shown in Table 1. The test was conducted on three samples for each level.

[0011]

[Table 1]

From the test results shown in Table 1, it can be seen that when the rubber hardness exceeds 82, the sealing property is deteriorated and the sealable water pressure is decreased. Further, if the rubber hardness is lower than 68, the water pressure capable of sealing decreases when the tightening force is large. in this case,
It was confirmed by visual inspection of the sample after the test that a flow was generated in the sealing material layer. From this test result, it can be seen that the range of rubber hardness 68 to 82 is a suitable rubber hardness range in which both sealing property and flow resistance are compatible. For cylinder head gaskets,
Usually, it is required to be able to seal a water pressure of at least 10 kg / cm ² .

An embodiment of a metal gasket according to the present invention is shown in FIGS. 1 is a plan view of a gasket according to a first embodiment of the present invention, and FIG. 2 is an enlarged sectional view taken along the line AA of FIG. FIG. 3 is an enlarged sectional view similar to FIG. 2 of the second embodiment of the present invention. The same reference numerals in the drawings indicate the same parts.

1 and 2, a cylinder head gasket 1 according to the present invention comprises a single plate of an elastic metal plate 2 such as a stainless steel plate or a steel plate, and has a combustion chamber opening 5 as a fluid passage hole, a water hole, an oil hole, etc. Liquid passage hole 6 and bolt hole 7. A chevron bead 9 that surrounds and seals the combustion chamber opening 5 is provided, and a step bead 10 that surrounds and seals the liquid passage hole 6 is provided around the combustion chamber opening 5. Have a section.

Both surfaces of the metal plate 2 are covered with rubber such as fluororubber, silicone rubber, nitrile rubber or acrylic rubber. The sealing material layer 12 is formed by punching the combustion chamber opening 5, the liquid passage hole 6, the bolt hole 7 and the outer peripheral edge 8 of the gasket in the metal plate 2, and the chevron bead 9 and the step forming the step and the inclined portion. The metal plate is coated on the surface of the metal plate after being processed to form the bead 10, and is softer than the conventional sealing material layer.
The hardness defined by 01 is 68 to 82. Since the sealing material layer is formed by applying a rubber coating on the surface of a metal plate having steps and slopes as described above, and drying and vulcanizing it, there is considerable variation in thickness, but the hardness of the sealing material layer is large. Is selected to have a hardness of 68 to 82, which is softer than before, and therefore, as is clear from the above-mentioned experimental results, the sealing property is good and the flow resistance is also sufficient.

According to the present invention, as described above, first, the punching process for punching the combustion chamber opening 5, the liquid passage hole 6, the bolt hole 7 and the outer peripheral edge and the step, the chevron bead 9 forming the inclined portion, and the step bead are formed. Processing for forming 10 and metal plate 2
After that, a vulcanizable rubber paint in which a rubber and a vulcanizing agent are dissolved in a solvent is applied to the surface of the metal plate 2 and dried and vulcanized to form a sealing material layer. No expensive rubber is wasted because rubber is not painted on the punched parts. Further, since the punching process and the bead forming process are not separated, the press process can be efficiently performed.
Therefore, according to the present invention, the metal gasket provided with the sealing material layer can be manufactured at a lower cost than before.

The second embodiment shown in FIG. 3 is a stainless steel plate,
A laminated gasket for a cylinder head in which a substrate 3 made of an elastic metal plate such as a steel plate and a sub plate 4 made of a stainless steel plate having a hardness smaller than that of the substrate and an iron plate are laminated. A fold-back portion 11 is formed at the periphery of the combustion chamber opening 5 of the sub plate 4 by folding the rim portion inward, and the substrate 3 surrounds the combustion chamber opening 5 at a position outside the fold-back portion 11. A convex chevron bead 9 is provided on the side of the sub plate 4. Around the liquid passage hole, only the step bead 10 surrounding the liquid passage hole is provided on the substrate 3,
The sub plate 4 is flat.

The sealing material layers 12 and 12 coated on the surfaces on both sides of the substrate 3 are exactly the same as the sealing material layer 12 in the first embodiment, and are coated after punching and bead molding and have a hardness of 68. It is selected in the range of 82 to 82. The sub-plate 4 has a sealing material layer 13 only on the upper outer surface in the drawing.
Is provided. In this sealing material layer 13, the outer surface of the sub-plate 4 is a flat surface having no steps or slopes and can be applied to a uniform thickness, so that a relatively hard sealing material having a hardness of 90 or more is coated as in the conventional case. are doing.

Therefore, in the joint surface of the cylinder head and the block, the thermal expansion is larger, and the joint surface of the cylinder head, which causes relative movement when the engine starts or stops, and the above-mentioned relatively hard sealing material. It is preferable to arrange the gasket so as to abut the outer surface of the sub-plate 4 covered with the layer.

In the illustrated example, since the sealing material layer 12 is provided on the inner surface of the substrate 3 facing the sub plate 4, the sealing material layer is provided on the inner surface of the sub plate 4 facing the substrate. However, the sealing material layer may be doubly provided on the inner surface of the sub plate 4. In this case, since the folded-back portion 11 of the stepped portion is present on the inner surface, a soft sealing material layer may be coated similarly to the sealing material layer 12 of the substrate 3, but it is doubled with the inner surface of the substrate 3. Since the sealing material layer is provided, even if the thickness of the sealing material layer on the inner surface of the sub-plate is slightly large, the sealing property is not impaired, and a relatively hard sealing material layer is covered like the outer surface of the sub-plate 4. You may do it.

[0021]

As described above, according to the present invention, since the stamped portion of the metal plate is not covered with the sealing material layer, the expensive rubber paint can be saved without wasting, and the punching process can be performed. Since the step, the bead to be the inclined part, and the forming process of the folded part are not separated, the press process can be efficiently performed, and the metal gasket having the sealing material layer on the surface of the metal plate can be manufactured at a lower cost than before. be able to. Further, according to the present invention, since the sealing material layer is coated on the surface of the metal plate having steps and slopes, the thickness of the sealing material layer varies greatly, but the hardness of the sealing material layer is softer than before. Since it is selected in the range of 68 to 82, the sealing material layer has good sealing properties and sufficient flow resistance, and the gasket of the present invention can maintain good sealing performance.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view similar to FIG. 2 of a second embodiment of the present invention.

[Explanation of symbols]

 5 Combustion chamber opening 6 Liquid passage hole 7 Bolt hole 9 Angled bead 10 Step bead 12 Sealing material layer (hardness 68 to 82) 13 Sealing material layer

[Procedure amendment]

[Submission date] June 23, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (2)

[Claims] 1. A metal plate having at least one metal plate, the metal plate having a fluid passage hole and a bolt hole, and a step or sloped portion such as a bead or a fold that surrounds and seals the fluid passage hole. After the punching process and the step or slope forming process described above, the sealing material layer made of vulcanized rubber on the surface of the metal plate has a hardness of 6 according to JIS K6301.
A metal gasket characterized by being 8 to 82. 2. A metal plate, which is subjected to a punching process for punching a fluid flow hole and a bolt hole and a process for forming a step or a sloped portion such as a bead, a fold or the like which surrounds and seals the fluid flow hole. A vulcanizable rubber paint in which a rubber, a vulcanizing agent, etc. are dissolved in a solvent is applied to the surface of the metal plate, and then the coating film is heat-vulcanized to a hardness of 68 to 82 with a hardness specified in JIS K6301. A method of manufacturing a metal gasket, comprising forming a sealing material layer having: