JPH0968281A - Metal gasket and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the sealing performance of a gasket, and to provide a method to manufacture such a gasket profitably, by making a sealant layer not only exercise a microsealing function, but also form seal lines, so as to multiplex the seal lines, when a metal gasket is fastened between junction surfaces. SOLUTION: A gasket furnishes a projecting bead 5 surrounding a fluid communicating hole, and a sealant layer 8 to cover the surface, and the thickness of the sealant layers 84 and 83 at the reverse side surface 54 of a bead base, and at the rear surface of a bead top 53, is made two times, or more than three times, favorably, of the thickness of the sealant layer 80 at the plane part 7. As the manufacturing method, after forming the projecting bead 5 to surround the fluid communicating hole, a sealant layer is formed by applying a rubber paint with a specific viscosity scope on the upper surface maintaining horizontal, and then it is turned over, and the painting is applied in the same way on the reversed upper surface, so as to form a sealant layer.

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 a gasket for a cylinder head of an engine.

[0002]

2. Description of the Related Art In a metal plate gasket having a bead for surrounding and sealing a fluid passage hole such as a cylinder bore, a cooling water or an oil passage hole, a joining surface to be sealed such as a cylinder head or a cylinder block. Compensate for roughness, distortion, scratches, etc. on the joint surface or the metal plate surface on the surface of the gasket that is in contact with, and also on the facing surface of the stacked metal plates when the gasket is formed by stacking multiple metal plates For the so-called micro-seal, a so-called sealing material layer made of rubber or plastic is coated.

This sealing material layer is coated to have a uniform thickness. For example, although it has been proposed that the thickness of the sealing material layer be different on the side contacting the cylinder head and the side contacting the cylinder block, the gasket or its constituent metal plate is used. Since the same surface is covered with a uniform thickness, it has been considered that the nonuniform thickness of the sealing material layer impairs the sealing performance.

Therefore, even in the production of a metal gasket, the metal plate is sealed on a flat metal plate before being subjected to processing such as beading or folding to form an inclination or a step so that the sealing material layer can be coated with a uniform thickness. The material layer was coated, and after the sealing material layer was coated, processing such as beading or folding was performed to generate an inclination or a step.

[0005]

In a conventional metal gasket having a seal material layer having a uniform thickness, a seal line having a high surface pressure formed when the gasket is clamped between the joint surfaces is exclusively formed by a bead. It is formed by convex portions and spring elastic portions formed on the metal plate surface by metal processing such as folding, grommets, etc., and the sealing material layer only performs the so-called micro-sealing function described above, and the sealing material layer has a high surface pressure. It does not contribute to the formation of the seal line at all.

The present invention focuses on this point. When the metal gasket is mounted between the joint surfaces to be sealed and tightened, not only the sealing material layer functions as a so-called microseal but also the surface pressure is increased. The purpose of the present invention is to make it possible to form a high sealing line, to multiplex the sealing line around the opening to be sealed, and to improve the sealing performance. The present invention also proposes a manufacturing method capable of advantageously manufacturing such a metal gasket.

[0007]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention is such that a metal plate having elasticity is provided with a fluid passage hole and a projecting bead which surrounds and seals the fluid passage hole. In the metal gasket in which both sides of the metal plate are covered with a sealing material layer made of rubber, plastic, etc., the thickness of the sealing material layer on the surface opposite to the bead base and the back surface of the bead top is set to It is characterized in that the thickness of the sealing material layer in the flat portion is twice or more, preferably three times or more.

The invention according to claim 4 of the present invention, which proposes a manufacturing method capable of advantageously manufacturing the metal gasket of the above-mentioned invention 1, encloses a fluid passage hole in a flat plate of an elastic metal plate. After forming the protruding beads, the surface of the metal plate was kept horizontal and the viscosity was 10,000 on the upper surface.
To 30,000 CP of rubber or plastic paint to form a sealing material layer, then the metal plate is turned over, and the above-mentioned rubber or plastic coating is applied to the upper surface of the metal plate overturned to form a sealing material layer. A sealing material layer having a thickness that is at least twice the thickness of the sealing material layer in the flat portion of the metal plate is formed on the opposite surface of the base portion and the back surface of the bead top portion.

The reason why the portion where the thickness of the sealing material layer is increased is the opposite surface of the bead base and the back surface of the bead top is as follows. That is, in the bead base portion of the conventional gasket having a uniform thickness of the sealing material layer, when tightened, the surface pressure is high only at the joint surface with which the bead base abuts, that is, the joint surface in contact with the surface opposite to the bead protruding side. The seal line is formed, and the seal line is not formed on the joint surface in contact with the surface of the bead protruding side. Further, at the bead top portion, when tightened, the seal line is formed only on the joint surface with which the bead top portion abuts, that is, the joint surface in contact with the surface of the bead protruding side, and the seal line is not formed on the opposite joint surface. Therefore, in the present invention, a seal line is formed by the seal material layer in the above-mentioned region where the seal line is not formed in the conventional bead, and the thickness of the seal material layer in the above region is increased in order to multiplex the seal line.

Then, the thickness of the sealing material layer in the above portion is set to the thickness of the sealing material layer in the flat portion, that is, the standard thickness of 2
Even if the thickness of the sealing material layer on the back surface side of the part is thinner than the standard thickness, the thickness of the sealing material layer on the entire front and back surfaces is sufficient to form a seal line. This is to secure the material layer thickness, and preferably,
The thickness of the sealing material layer in the above portion is set to be three times or more the thickness of the sealing material layer in the flat portion of the metal plate. Further, in order to effectively form a seal line on the joint surface by the effect of the local thickness of the seal material layer, the seal material layer has a roughness of the joint surface or the surface of the metal plate,
It is desirable to have a certain degree of hardness while having sufficient flexibility to fulfill the function of a microseal for compensating for distortion, scratches, etc. From such a point, according to the invention of claim 3 of the present invention, The sealing material layer has a hardness of 7 according to JIS K6301.
It preferably has a hardness of 5 to 90.

According to the manufacturing method of the fourth aspect of the present invention, the bead and the folded portion, the grommet and the like are formed on the elastic metal plate, and then the surface of the metal plate is kept horizontal. A rubber having a viscosity of 10,000 to 30,000 CP on its upper surface in a state of being upside down,
Since it applies plastic paint, it will be the lower part of the slope,
The paint naturally flows down to the surface on the opposite side of the bead base and the back surface of the bead top, and the thickness of the sealing material layer at these portions becomes thicker, which is at least twice the thickness of the sealing material layer at the flat portion. be able to.

At this time, if the thickness of the sealing material layer formed by one coating of rubber or plastic coating is less than 10 μm, the thickness of the coating layer is thin, so that the surface tension affects the amount of spontaneous flow of the coating. Therefore, the thickness of the sealing material layer formed by coating the coating material once is preferably 10 μm or more. In addition, since the natural flow rate of the paint decreases even if the applied paint is dried too early, it is preferable to use a solvent having a boiling point of 130 ° C. or higher, such as isoamyl acetate or isobutyl ketone, as the solvent for the rubber or plastic paint. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention described in claim 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a cylinder head gasket to which the present invention is applied,
The gasket is composed of a single metal plate 1, and has a cylinder bore 2, a liquid passage hole 3 such as a cooling water passage hole or an oil passage hole, and a bolt hole 4 for inserting a fastening bolt (not shown). Around each cylinder bore 2, there is a chevron bead 5 that surrounds and seals the cylinder bore 2, and around the liquid passage hole 3 there is a step bead 6 that surrounds and seals the hole 3. In FIG. 1, both beads 5 and 6 are shown by dotted lines at their tops.

2 and 3 are enlarged sectional views taken along the line AA of FIG. 1, showing a state in which they are mounted between the cylinder head H and the cylinder block B. However, FIG. 2 shows a state in which bolts (not shown) have not been tightened and the gasket has not been tightened, and FIG. 3 shows a state in which bolts have been tightened and the gasket has been tightened. The pressure is also displayed.

As clearly shown in FIG. 2, the metal gasket according to the present invention is provided with a sealing material layer 8 made of vulcanized rubber or the like on both front and back surfaces of the metal plate 1, the thickness of which is a bead portion. Is different depending on the part, and Yamagata beads 5
The thickness of the sealing material layer 84 on the surface 54 on the opposite side of the bead base 52 and the thickness of the sealing material layer 83 on the back surface 53 of the bead top 51 are thicker than the thicknesses of the sealing material layers of other parts, and the flat portion 7 of the metal plate 1 is At least twice the thickness of the sealing material layer 80,
The thickness is preferably three times or more.

The thickness of the sealing material layer of the bead top portion 51 and the sealing material layer of the bead base portion 52 is smaller than the sealing material layer thickness of other portions, which is the same as the metal gasket shown in FIG. This is because it is manufactured by the manufacturing method according to the fourth aspect of the invention, and the details will be described later. Even in the sealing material layer at the above-mentioned portion, which is thinner than the other portions, the thickness is sufficient to fulfill the function of the microseal.

When the above metal gasket is tightened and pressed between the cylinder head H and the cylinder block B as shown in FIG. 3, a high surface pressure as shown in the drawing is applied to the joint surface between the cylinder head H and the cylinder block B. The seal line of occurs. Compared with FIG. 4, which shows a seal line having a high surface pressure generated when a conventional metal gasket having a uniform thickness of the sealing material layer is clamped between the cylinder head H and the cylinder block B and pressed, On the back surface 53 of the bead top portion 51 and the surface 54 on the opposite side of the bead base portion 52 where no seal line is formed in the gasket, the gasket according to the present invention, in the gasket of the present invention, has a high surface pressure due to the effect of locally increasing the thickness of the sealing material layer at the above-mentioned portion. It is understood that the seal line is formed and the seal line is multiplexed so much that the seal performance is improved.

Next, FIG. 5 is an enlarged cross-sectional view taken along the line CC of FIG. 1, showing a state in which it is mounted between the cylinder head H and the cylinder block B (however, not tightened). . As clearly shown in the figure, the thickness of the sealing material layer 8 coated on both sides of the metal plate 1 is different depending on the portion of the step bead 6 around the liquid passage hole 3. There is. That is, the bead base 6
The thickness of the sealing material layer 86 on the surface 64 on the opposite side of 2 and the sealing material layer 87 on the back surface 63 of the bead top portion 61 is thicker than the thickness of the sealing material layer of the other part, and the sealing material layer of the flat portion 7 of the metal plate 1 is It is formed to have a thickness of 2 times or more, preferably 3 times or more of the thickness of 80. The thickness of the sealing material layer of the bead top portion 61 and the sealing material layer of the bead base portion 62 is thinner than the sealing material layer thickness of other portions, but the thickness is sufficient to perform the above-mentioned micro sealing function. Is the same as that of the above-mentioned Yamagata bead.

When the above gasket is tightened and pressed between the joint surfaces of the cylinder head H and the cylinder block B, it is generated on the joint surface of the cylinder head H and the block B,
FIG. 6 shows a high surface pressure seal line surrounding the liquid passage hole 3. FIG. 7 shows a seal line of high surface pressure generated in the cylinder head H and the block B when a conventional metal gasket having a sealing material layer having a uniform thickness is clamped and pressed by the cylinder head H and the cylinder block B. ing. By comparing FIG. 6 and FIG. 7, in the bead base portion 52 on the rear surface side and the bead protruding side surface of the bead top portion 61 where the seal line is not formed in the conventional gasket, in the gasket according to the present invention, the sealing material layer of that portion is formed. It can be seen that a seal line having a high surface pressure is formed based on the local increase in the thickness of the seal line, and the seal line is multiplexed as much, thereby improving the sealing performance.

The invention according to claim 1 of the present invention has been described above for the cylinder head gasket having a single plate construction.
The metal gasket of the present invention is not limited to a single plate construction, and for example, one or both sides of the above-mentioned metal plate 1 may be laminated with a sub-plate or a surface plate, or the above-mentioned metal plate 1 may be an intermediate plate. It may be laminated on both sides of the plate, and can be appropriately laminated according to a known laminated metal gasket laminating technique. Further, the application target is not limited to the cylinder head gasket described above.
Furthermore, although the mountain-shaped beads and the step beads are described in the above description, the present invention is not limited thereto, and the same can be applied to a metal gasket having a trapezoidal bead.
The sealing material layer 8 does not necessarily need to cover the entire surface of the metal plate 1, and may cover only the bead portion, preferably about twice the width of the bead. In this case, an expensive seal is used. The material of the timber layer can be saved.

Next, an embodiment and an example of the invention according to claim 4 of the present invention will be described. In the method for manufacturing a metal gasket according to the present invention, a chevron bead surrounding a fluid flow hole to be sealed before coating a sealing material layer,
Protruding beads such as step beads are formed. This protruding bead can be formed simultaneously or continuously with metal working such as punching of cylinder bore, liquid passage hole, bolt hole and outer periphery of gasket, and formation of folded-back portion and grommet. Can be streamlined. Further, since the cylinder bore and the like are punched before the coating of the sealing material layer, the material for forming the sealing material layer is not wasted. The height of the beads is usually 150 to 250 μm.

Rubber or plastic paint for forming a sealing material layer on the upper surface of the metal plate on which the fluid flow holes such as cylinder bores and liquid passage holes and the beads surrounding and sealing the fluid flow holes are formed while keeping the surface horizontal. For example, paint mainly composed of fluororubber is applied. The viscosity of the paint is 10,000
To 30,000 CP, preferably 15,000 to 2
It is 10,000 CP and is preferably applied by screen coating or flow coating. The coating thickness of the sealing material layer is usually 15 to 3 in the flat portion of the metal plate.
It is preferable that the thickness of the sealing material layer formed by applying the coating material once is 10 μm or more, as described above.

When the upper surface to be coated is the bead protruding side surface, the coating material applied to the bead portion by the above-mentioned rubber or plastic coating material is the high side of the bead, that is, the top side to the low side, that is, the side opposite to the bead base. The inclined surface is allowed to flow down to the surface, and the surface on the opposite side of the bead base is thickly coated so that the coating thickness is twice or more than three times the coating thickness in the flat portion.
On the other hand, the paint flows down to the low side at the top of the bead and the surrounding high places, but it does not flow down beyond a certain limit due to the surface tension, and a thin coating film is formed on the top of the bead.

After the coating film is dried, the metal plate is turned upside down, and the horizontally turned upside-down upper surface is coated with the rubber and the plastic paint as described above. Then, in the same manner as described above, a thick coating film is formed on the back surface of the bead top portion which is a low place on the turned upside surface, and a thin coating film is formed on the bead base portion which is a high place side. The metal according to claim 1, further comprising a sealing material layer having a locally increased thickness at the specific portion of the bead portion by drying the coating film and then heating and vulcanizing the coating film, if necessary. A gasket can be obtained.

[0025]

EXAMPLE A cylinder plate having a diameter of 90 mm is provided on a metal plate 1 having a thickness of 0.2 mm and made of SUS301CSP3 / 4H, and a height of 200 μ surrounding the cylinder bore.
An angled bead of m and 2 mm in width was provided. Then, a fluororubber paint (Viton E60C from DuPont) was dissolved in isoamyl acetate on the surface of the metal plate, which was held horizontally with the bead protruding side surface facing upward, and the viscosity was adjusted to 18,000 CP. Painted by coating. The coating thickness was adjusted so that the thickness of the sealing material layer on the flat portion of the metal plate was 20 μm. After the coating film was naturally dried, the metal plate was turned over and the horizontal upper surface thereof was coated with the fluororubber paint in the same manner as above and dried. Then, it was vulcanized at 220 ° C. for 20 minutes.

The thickness of the sealing material layer on each portion of the bead portion of the metal gasket thus obtained and on the flat portion of the metal plate was measured. Bead Top 5-10 μm Back of Bead Top 45-60 μm Opposite Side of Bead Base 45-60 μm Bead Base 5-10 μm Flat 15-20 μm

[0027]

Since the invention according to claim 1 of the present invention is as described above, it has the following significant effects. Since the seal lines having a higher surface pressure are formed around the fluid passage hole to be sealed more than in the conventional case, the sealing performance of the metal gasket is improved. Since the thick sealing material layer is coated on the back side of the bead top portion, the crushing of the bead when the metal gasket is clamped and pressed is reduced, and the bead is prevented from cracking or settling. Since the number of high surface pressure seal lines around the fluid passage hole to be sealed increases, the requirement for high surface pressure for each seal line can be relaxed. Therefore, the present invention can be advantageously applied to a cylinder head gasket having a large head lift (a large change in the distance between the joint surfaces).

The invention according to claim 4 of the present invention can not only advantageously manufacture the metal gasket, but also has the following remarkable effects. Since the sealing material layer can be coated after the opening of the cylinder bore or the like and the outer peripheral punching of the gasket, the material of the sealing material layer is not wasted. Opening of cylinder bores and punching around the gasket,
It is possible to perform the forming process of the bead and the folded portion at the same time or continuously, and only one press process is required, and the process can be rationalized.

[Brief description of drawings]

FIG. 1 is a plan view of a cylinder head gasket according to a first aspect of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

3 is a cross-sectional view showing a state where the gasket of FIG. 2 is pressed by a cylinder head and a cylinder block.

FIG. 4 is a cross-sectional view of a conventional gasket pressed by a cylinder head and a cylinder block.

5 is a cross-sectional view taken along the line CC of FIG.

6 is a sectional view of the gasket of FIG. 5 pressed by a cylinder head and a cylinder block.

FIG. 7 is a cross-sectional view of a conventional gasket pressed by a cylinder head and a cylinder block.

[Explanation of symbols]

 2 cylinder bore 3 liquid passage hole 5 chevron bead 6 step bead 8 sealant layer 51 and 61 bead top 52 and 62 bead base

Claims (6)

[Claims] 1. A metal gasket in which a metal plate having elasticity is provided with a fluid passage hole and a projecting bead surrounding and sealing the fluid passage hole, and both surfaces of the metal plate are covered with a sealing material layer such as rubber or plastic. 2. The metal gasket according to, wherein the thickness of the sealing material layer on the opposite surface of the bead base and the back surface of the bead top is twice or more the thickness of the sealing material layer on the flat portion of the metal plate. 2. The gasket according to claim 1, wherein the thickness of the sealing material layer on the surface opposite to the bead base and the back surface of the bead top is three times or more the thickness of the sealing material on the flat portion of the metal plate. A metal gasket characterized in that 3. The metal gasket according to claim 1 or 2, wherein the sealing material layer has a hardness of 75 to 90 in accordance with JISK6301. 4. A projecting bead that surrounds a fluid flow hole is formed on a flat plate of an elastic metal plate, and the viscosity of the upper surface of the metal plate is 10,000 to 30,000 CP while the surface of the metal plate is kept horizontal. The rubber and plastic paints are applied to form a sealing material layer, then the metal plate is turned upside down, and the rubber and plastics paint is applied to the upper surface of the inside upside down to form a sealing material layer. A method for producing a metal gasket, characterized in that a sealing material layer having a thickness that is at least twice the thickness of the sealing material layer in the flat portion of the metal plate is formed on the front surface and the back surface of the bead top. 5. The viscosity of the rubber or plastic paint is 1
The method for producing a metal gasket according to claim 4, wherein the pressure is 5,000 to 20,000 CP. 6. The method for producing a metal gasket according to claim 4, wherein the thickness of the sealing material layer formed by coating the rubber or plastic paint once is 10 μm or more.