JP4485179B2 - Gasket bead formation method - Google Patents

Description

  The present invention relates to a method for forming a bead of a gasket, and more specifically, a thin-walled gasket base material made of a rubber material or a composite material containing a rubber material interposed between a pair of sealed members arranged opposite to each other is used. The present invention relates to a method for forming a bead of a gasket.

  Generally, a gasket is a sealing member interposed between sealed members facing each other in a fixed state (stationary state), between a cylinder block and a cylinder head, between a cylinder head and a head cover, It is often used in places where sealing properties are required, such as between the intake manifold or between the engine case and the transmission case. It is known to form a bead as an effective means for improving the sealing performance of the gasket. As such a gasket with a bead, what was shown by the following patent documents 1 and patent documents 2, for example is known.

The technique disclosed in Patent Document 1 is a means for forming a bead by subjecting an elastomer gasket to a hot press process, and the technique disclosed in Patent Document 2 is performed by beading a metal plate gasket by coining. It is a means to form.
Japanese Patent Publication No.56-35780 Japanese Patent Laid-Open No. 11-201287

  In recent years, it is advantageous in that the gasket base material is made of a rubber having good conformability and high elasticity, so that it can have excellent sealing properties. Furthermore, since the sealing performance is improved by forming beads, it is predicted that rubber gaskets with beads will be used in the future. In this case, when creating a bead, first, it is conceivable to refer to the bead forming method described in the above-described prior art.

  As shown in the former prior art, when the method of forming a bead by hot pressing is applied to a rubber gasket, the restoring action (spring back) after press molding is strong because of a rubber material rich in elasticity, and molding is performed well. There are inconveniences that are difficult to do.

  On the other hand, as shown in the latter prior art, when the method of forming a bead by coining is applied to a rubber gasket, even if the mold is pressed against the rubber material having abundant elasticity, the rubber material The deformation is also restored and cannot be molded. As described above, even if any of the above-described conventional techniques is used, a bead cannot be successfully formed on the rubber gasket, and a new device is required.

An object of the present invention is to review the bead forming method so that a bead effective on a seal can be formed with good productivity even in a rubber gasket.
The problem to be solved is a point.

The method of claim 1 is a method for forming a bead of a gasket using a thin gasket base material made of a rubber material or a composite material containing a rubber material interposed between seal members arranged opposite to each other.
The press die has vertical side walls that protrude perpendicularly and protrude from the reference surface of the press die on both outer sides of the recessed die portion having a bottom surface deeper than the reference surface of the press die and formed in a valley shape. A pair of protruding molds,
The recessed mold part and the protruding mold part are formed by pressing with the protruding mold part on the basis of the surface position of the gasket base material, and the sectional area S1 of the biting part of the gasket base material and The relationship of the cross-sectional area S2 of the bead formed by flowing in the recessed mold part is 2S1> S2,
When the gasket base material is pressed with the press die in a state of being vulcanized or semi-vulcanized, the protruding mold part bites into a pair of biting parts and is adjacent to the biting part. A portion is sandwiched between the pair of protruding mold parts and flows into the recessed mold part to form the bead, and thereafter, the gasket base material is taken out from the press mold and vulcanized.

The method of claim 2 is the method of forming a bead of the gasket of claim 1 ,
An inclined surface is provided in the protruding mold part to promote the material flow from the biting part to the bead by press molding to the unvulcanized gasket.

The method of claim 3 is the gasket forming method of claim 1 or 2 ,
As the gasket base material, a composite material in which fibers are mixed in a rubber material is used.

The method of claim 4 is the gasket forming method according to any one of claims 1 to 3 ,
The gasket is characterized by using a plate-shaped metal core coated with the gasket base material.

  In the method of claim 1, since the rubber material that has not been completely vulcanized has fluidity, when an external force is applied, if it is thin, it is not elastically deformed like rubber after vulcanization. Thus, it was found that the plastic deformation was easy, and good fluidity and plastic deformation in the unvulcanized state were utilized. That is, when a press mold having a protruding mold part that can be eaten into the gasket base material and a recessed mold part formed in a valley shape in the vicinity thereof is pressed, the protruding mold part is formed in the gasket in the thickness direction. The gasket base material bites into the gasket base material, and the bite base material moves laterally by the bite. However, the swept gasket base material has no lateral direction.

  Accordingly, the gasket base material that moves laterally enters the recessed mold part located in the vicinity of the protruding mold part in the press die, and the vicinity of the biting part formed on the gasket base material by biting of the protruding mold part. In addition, the swollen gasket base material rises upward to form a raised bead. In addition, since beads can be formed simply by press molding, gasket beads can be made at low cost, and by setting the size, shape, etc. of the projecting mold part and the biting part, a narrow raised part can be formed. It is also possible to form an elongated bead or a delicate bead on the gasket without difficulty.

  As a result, a bead suitable for gaskets that require strict pressure resistance and airtightness is obtained by press molding the gasket base material in an unvulcanized or semi-cured state, then removing it from the press die and vulcanizing it. In addition, the gasket base material, which is an elastic material, can be formed so as to rise in the thickness of the gasket by moving laterally, and it can be formed at a low cost and with a high degree of freedom in setting the shape.

And according to the method of Claim 1 , since a bead which raised between them is formed by making a pair of biting parts adjoin, flow of a gasket base material from a biting part to a bead at the time of press It is possible to increase the amount and increase the density, increase the material density, or increase the bead formation position accuracy and shape accuracy. Therefore, it becomes possible to contribute to improvement of the function of the bead.

According to the method of claim 2, an inclined surface is provided in the protruding mold part that forms the biting part in the press mold so as to promote the material flow from the biting part to the bead by press molding in the unvulcanized gasket. Therefore, for example, the height and size of the bead are clarified more than in the case of a press die having a flat top surface, or the biting portion for obtaining the necessary bead is reduced in size. It becomes possible. Further, since the dimensions and shape of the bead can be stabilized, the bead of the gasket can be obtained with excellent reliability.

According to the method of claim 3 , compared to the case where the gasket base material is made of only a rubber material, the material strength and characteristics can be improved, the heat-resistant temperature can be increased, and the crushing due to tightening of the sealed member can be reduced. It is possible to obtain advantages such as that it is difficult to cause a torque down in which the tightening force by the bolt decreases with time, and that it is possible to increase the thickness. And when the rubber material which comprises a gasket base material is a composite material with which the fiber material was mixed, the bead formation method by this invention will be in the state where a material density will become higher than the circumference | surroundings, and a cylinder head gasket etc. There is an advantage that it becomes more suitable as a bead of a gasket that further requires pressure resistance and airtightness.

According to the method of claim 4 , since the gasket base material is reinforced with the core metal, it is possible to provide a bead forming method suitable for a gasket capable of exerting power in a severe environment where strength and durability are more required. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a cylinder head gasket 1 interposed between a cylinder and a cylinder head in an engine. This cylinder head gasket 1 is composed of a steel core 3 and a composite material (compound material) in which a fiber material as a reinforcing material is mixed in a rubber material. An example of a gasket base material) 2 is used. The gasket substrate 2 may be made of only a rubber material.

  Fiber materials include glass fiber, ceramic fiber, rock wool, mineral wool, fused quartz fiber, chemically treated high silica fiber, molten oxalic acid alumina fiber, alumina continuous fiber, stabilized zirconia fiber, boron nitride fiber, alkali titanate fiber Inorganic fibers such as whiskers, carbon fibers, metal fibers, and boron fibers can be used. Also, aromatic polyamide fiber, polyamide fiber, polyolefin fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, polyester fiber, polyvinyl chloride fiber, polyurea fiber, polyurethane fiber, polyfluorocarbon fiber, phenol Organic fibers such as fibers and cellulosic fibers can also be used. In addition to the SPCC, various types such as a rolled steel plate such as SPHC, an aluminum plate, and a stainless steel plate can be used as the core metal 3.

As rubber (rubber material), nitrile rubber (NBR), styrene butadiene rubber (SBR), isoprene rubber (IR), chloroprene rubber (CR), butadiene rubber (BR), butyl rubber (IIR), ethylene-propylene rubber (EPM), fluoro rubber (FPM), silicone rubber (Si), chlorosulfonated polyethylene (CSM), ethylene vinyl acetate rubber (EVA), chlorinated polyethylene (CPE), butyl chloride rubber (CIR), epichlorohydrin rubber (ECO), nitrilo Isoprene rubber (NIR), natural rubber (NR), etc. can be used. In addition, these rubber materials, for example, oil-extended rubber obtained by adding naphthenic process oil to SBR can also be used.

  In the cylinder head gasket 1 shown in FIGS. 1 and 2, 4 is a large circular hole for a cylinder bore, and a large number of 5 are cooling holes for passage of cooling water. The large circular hole 4 that requires particularly high airtightness. As for the surrounding portion, an annular bead 6 surrounding the large circular hole 4 is configured as a double-sided bead structure formed on both the front and back compound layers 2.

  The bead 6 is processed into each compound layer 2 so as to protrude from the outer surface 2a of the compound layer 2, and is formed by the following method. That is, in a state in which each compound layer 2 is semi-vulcanized, it is a production method in which a bead 6 is formed by press molding with upper and lower press dies 7, 8 and then taken out from the press die and completely vulcanized. Details will be described below.

  The upper and lower press dies (metal molds) 7 and 8 to be used have a vertically symmetric shape, and will be described in the upper press die 7. As shown in FIG. 3, the upper press die 7 includes an annular inner projecting die portion 9, an annular outer projecting die portion 10, and an annular concave recess located between the inner and outer projecting die portions 9, 10. The recessed mold part 11 is formed. In FIGS. 3 and 4, for convenience, an unvulcanized compound layer before vulcanization or semi-vulcanized is 2 ′ and an unvulcanized gasket having this layer is 1 ′, and the rubber material is vulcanized and treated. The reference numerals are properly used, such as 2 for the cured and stabilized compound layer and 1 for the vulcanized gasket having the compound layer.

  Each projecting mold part 9, 10 projects outward from the reference press surface 12 in the gasket thickness direction, and the inner diameter side of the inner projecting mold part 9 and the outer diameter side of the outer projecting mold part 10 are vertically cut. A curved inclined surface 9b that is formed on the vertical side walls 9a and 10a, and whose outer diameter side of the inner projecting mold part 9 and inner diameter side of the outer projecting mold part 10 are lowered toward the recessed mold part 11 , 10b. Further, the recessed mold part 11 recessed inward from the reference press surface 12 in the gasket thickness direction is formed to have an inwardly curved surface 11a with a curved line following the curved inclined surfaces 9b and 10b.

  The procedure for forming the bead 6 is as follows. First, as shown in FIG. 3 (a), a semi-vulcanized gasket 1 ′ having a compound layer 2 ′ coated on a core metal 3 and in a semi-vulcanized state is formed into upper and lower press dies 7,8. Prepare in between. Next, the upper and lower press molds 7 and 8 are moved closer to each other, and as shown in FIG. 3B, the respective protruding mold parts 9 and 10 bite into each compound layer 2 ′, and the compound layer 2 ′ of that portion. Start compressing up and down. At this time, horizontal component force is generated depending on the inclination angle of the inner and outer curved inclined surfaces 9b and 10b, but the main rubber material constituting the compound layer 2 ′ is easy to flow because it is in a semi-vulcanized state. A phenomenon occurs in which the compound layer 2 ′ moves laterally toward the portion sandwiched between the inner and outer protruding mold parts 9 and 10.

  Then, when the upper and lower press dies 7 and 8 are forcibly moved to a limit position where their reference press surfaces 12 are in light contact with the outer surface of the compound layer 2 ′, as shown in FIG. 3C, the compound layer 2 ′. Is plastically deformed to form a concavo-convex shape that conforms to the shape of both protruding mold parts 9 and 10 and the recessed mold part 11. That is, the annular inner and outer biting portions 13 and 14 that are recessed due to the biting of the protruding mold portions 9 and 10 and the bead 6 that is raised in an annular shape by the rubber material flowing laterally into the concave mold portion 11 are formed.

  Then, as shown in FIG. 4 (a), the upper and lower press dies 7, 8 are returned and moved away from each other, and the semi-vulcanized gasket 1 in a state where the annular beads 6 are formed on the upper and lower compound layers 2 ′. 'Take out. Then, as shown in FIG. 4 (b), the half-vulcanized gasket 1 'after press molding is vulcanized by, for example, putting it in the vulcanizing pot 16, cured by vulcanization, and having a shape and composition. This is to obtain a vulcanized gasket 1 [see FIG. 4 (c), FIG. 1] having a stabilized compound layer 2.

  The depth of biting into the compound layer 2 ′ of the protrusions 9 and 10 of the press dies 7 and 8 is set to about 20 to 80% of the thickness (about 10 μm to 1.0 mm) of the compound layer 2 ′. . Although the press pressure depends on the size of the gasket, it is compression molded at about 50 to 300 tons by a hydraulic press.

  That is, in the gasket forming method according to the present invention, an unvulcanized gasket 1 ′ having a compound layer 2 ′ mainly composed of an unvulcanized rubber material is prepared, and the unvulcanized gasket 1 ′ is formed with a thickness thereof. By press-molding the press dies 7 and 8 so as to bite in the direction, the portions of the unvulcanized gasket 1 ′ adjacent to the biting portions 13 and 14 where the press dies 7 and 8 bite are not yet formed before press molding. It is formed on a bead 6 that rises and rises above the surface position 2a of the vulcanized gasket 1 ', and is then taken out from the press die and vulcanized.

  In this way, the means for forming the bead 6 by forcibly flowing and moving the compound layer by the pressure of the press molding with respect to the compound layer that is a rubber material mixed with the reinforcing fiber material is used as the biting portion 13. It is confirmed that the material density of the beads 6 formed by the movement from, 14 is larger than that of the normal compound layer 2. That is, there is an advantage that the density of the bead 6 that requires more adhesion to the member to be sealed can be increased in the formation process.

That is, in order to increase the material density of the bead 6, as shown in FIG. 13, the relationship between the cross-sectional area S1 of the biting portions 13 and 14 and the cross-sectional area S2 of the bead 6 is 2S1> It is desirable to set so as to be S2. Since the build-up of the bead 6 is determined by the displacement volume of the compound layer 2 by press (the volume of the biting portions 13 and 14), the total cross-sectional area of both the biting portions 13 and 14 is larger than the cross-sectional area of the bead 6. If it exists, the compound layer 2 of the part of the bead 6 can be formed in a compressed state, that is, in a higher density state than the original state.
[Another embodiment]

<1> A gasket forming method is also possible in which the beads 6 are formed only by the protrusions on one side. That is, as shown in FIG. 5, due to the presence of the curved inclined surface 10 b of the projecting mold part 10, when the press mold 17 is lowered to enter the gasket 1 having the compound layer 2 and the cored bar 3, The compound layer 2 compressed in the insertion portion 13 moves laterally toward the recessed mold portion 11 (to the right in FIG. 5), and a bead 6 protruding upward from the outer surface 2a can be formed. For example, if the protruding mold 10 has a ring shape with the vertical wall 10a on the large diameter side, the ring-shaped bead 6 is formed on the inner diameter side.

<2> A gasket forming method is also possible in which two protruding beads 18 are formed in one protruding mold portion 18. That is, as shown in FIG. 6, using a press die 20 in which a pointed protruding mold portion 18 having inclined surfaces 18a on both sides and a recessed mold portion 19 formed on both sides thereof are formed. The unvulcanized compound layer 2 is press-molded. As a result, the compound layer 2 pushed away by the downward movement of the protruding mold part 18 moves laterally toward the respective recessed mold parts 19. As a result, small beads 6 are formed on both the left and right sides of the relatively large biting portion 21. If these beads 6 are continuously formed, a gasket with beads is obtained.

<3> A press die 23 having a protruding die portion 22 that does not have an inclined surface that promotes the material flow from the biting portion to the raised portion by press molding in the unvulcanized gasket may be used. That is, as shown in FIG. 7, the top surface 22 a of the protruding mold portion 22 is formed in a plane parallel to the reference press surface 12. In this case, the recessed mold portion 24 is interposed between the left and right protruding mold portions 22. Therefore, the lateral flow due to the biting into the compound layer 2 flows toward the recessed portion 24 having a marginal space, and the bead 6 is interposed between the pair of rectangular shaped biting portions 13 and 14. Can be formed.

<4> In the gasket using the rubber material containing the fiber material, the height of the bead 6 may be the same as the outer surface 2a which is the reference gasket surface. That is, as shown in FIG. 8, the top surface 26 a of the recessed mold part 26 formed between the protruding mold parts 9 and 10 in the press mold 25 is the same as the reference press surface 12. In the gasket 1 formed using the press die 25, the material density of the beads 6 formed in the vicinity of the lateral side of the biting portion 15 can be made larger than that shown in FIG. .

  Therefore, when viewed as the bead 6, the bead 6 is substantially not compressed when it is compressed between the sealed members facing each other due to the material density that is higher than the surrounding area because it does not protrude from the outer surface 2a. This makes it possible to exert the same reinforcing function of the seal as that of the bead that has been raised. Therefore, in claim 4, the content of “bead that rises above the surface position” may be expressed as the content of “bead that rises above the surface position”.

<5> As shown in FIG. 9 and FIG. 10, two sets of inner and outer annular beads 6r, 6s are formed on the outer peripheral side of the large circular hole 4 with an appropriate interval, and these inner beads 6r and outer beads 6s are formed. A cylinder head gasket 1 in which a plurality of horizontal bead portions 6 y that short-circuit each other is formed radially with the large circular hole 4 as the center and a double annular composite bead is formed around the large circular hole 4 may be used. This composite bead 6 can also be formed by press molding in a biting state. 10A is a cross-sectional view taken along the line II of FIG. 9, and FIG. 10B is a cross-sectional view taken along the line of FIG.

  Thus, if a composite bead is formed by the double beads 6r and 6s and the horizontal bead 6y, it is extremely effective for countermeasures against a cast hole. A cast hole is a hollow part formed inside a casting due to air bubbles mixed in a cast iron (including die cast) cylinder block or cylinder head, and the cast hole is formed on the joint surface of the cylinder block or the like. When it appears, there is a disadvantage that there is a hole there. 9 is an example of a plan view shape of a hole by a cast hole appearing on the joint surface of the cylinder block or the cylinder head (hereinafter referred to as a cast hole), which is denoted by reference numerals 27 to 29 in FIG. It is.

  For example, as shown in FIG. 9, when there is a cast hole 29 straddling the inner bead 6r, the inner and outer sides of the inner bead 6r are communicated by the cast hole 29, and the sealing function by the inner bead 6r is achieved. Although there is a risk of damage, the outer beads 6s and the horizontal beads 6y are blocked so as not to communicate with each other, so that good sealing performance can be maintained. Similarly, even when there is a cast hole 27 straddling the outer bead 6s inside and outside, good sealing performance can be maintained by the inner bead 6r and the horizontal bead 6y.

  In addition, when a hole 28 is formed in a cast hole in a portion surrounded by a pair of adjacent horizontal bead portions 6y and inner and outer beads 6r and 6s, no communication is made except for a portion surrounded by the four sides. As a result, good sealing performance by the cylinder head gasket 1 can be maintained. In this way, if a composite bead is formed by the inner and outer double beads 6r, 6s and the plurality of horizontal beads 6y, there is an advantage that the adverse effects caused by the hollow holes of the cylinder block and cylinder head can be prevented in most cases. It is done.

<6> As shown in FIG. 11, a gasket 1 having a structure in which a gasket base material 2 is coated only on one side of a core metal 3 may be prepared, and a bead 6 may be formed thereon. In this case, it is formed only in the protruding mold parts 9 and 10, the recessed mold part 11 and the upper press mold 7, and the lower press mold 15 exists as a receiving mold having a flat upper surface. The gasket base material 2 in this case may be made of only a rubber material or may be reinforced by mixing a fiber material into the rubber material.

<7> As shown in FIG. 12, the gasket 1 having a structure including only the gasket base material 2 without the core metal 3 may be prepared, and the beads 6 may be formed thereon. Also in this case, it is formed only in the protruding mold parts 9 and 10, the recessed mold part 11 and the upper press mold 7, and the lower press mold 15 exists as a receiving mold having a flat upper surface. The gasket base material 2 in this case may be made of only a rubber material or may be reinforced by mixing a fiber material into the rubber material.

Although various gaskets have been described above, here, “rubber-made gasket base materials” can be summarized into the following types 1) to 4).
1) Rubber material with fiber material + mandrel (coating rubber material with fiber on mandrel)
1) those that have been coated on one side only of -a core metal 1) those that have been coated on both sides of -b cored 2) fibrous material containing a rubber material only 3) rubber (fiber Mu) + core metal (the fiber-free rubber material coating the metal core)
3) 3 as coated only on one side of -a core metal) that were coated on both surfaces of -b core metal 4) rubber material only (fibers Mu)

  These are all methods for forming a raised bead in the rubber material portion, and the operational effects are as follows. In the gasket 1), there is no generation of burrs at the time of bead formation, continuous processing is possible, and efficient production becomes possible. The material usage efficiency is improved and there is little waste. The bead can be formed at a higher density than the surrounding area. Sealability improves (sufficient sealing performance can be obtained with low compression). Finer beads can be formed compared to conventional beads. Since only the coating layer is processed, processing is easy.

  In the gasket of 2), there is no generation of burrs at the time of bead formation, continuous processing is possible, and efficient processing is possible. The material usage efficiency is improved and there is little waste. The bead can be formed at a higher density than the surrounding area. Sealability is improved. In the gasket 3), there is no generation of burrs when beads are formed, continuous processing is possible, and efficient production becomes possible. The material usage efficiency is improved and there is little waste. Finer beads can be formed compared to conventional beads. Since only the coating layer is processed, processing is easy. Sealability improves (sufficient sealing performance can be obtained with low compression). With the gasket 4), there is no generation of burrs when beads are formed, continuous processing is possible, and efficient production becomes possible. The material usage efficiency is improved and there is little waste.

  As described above, the present invention relates to a press die having a protruding mold part that can be eaten into a gasket base material, and a recessed mold part formed in a valley shape in the vicinity thereof, and the gasket base material is vulcanized. A part adjacent to the biting part where the protruding mold part bites into the unvulcanized gasket by preparing an unvulcanized gasket in a pre- or semi-cured state and pressing the unvulcanized gasket with a press die. Is a bead forming method for a gasket that is formed into a bead that rises above the surface position of the unvulcanized gasket before press molding, and is then taken out from the press die and vulcanized. It is characterized by that.

  As a result, a bead suitable for gaskets that require strict pressure resistance and airtightness is obtained by press molding the gasket base material in an unvulcanized or semi-cured state, then removing it from the press die and vulcanizing it. Further, the gasket base material, which is an elastic material, can be formed so as to rise up from the thickness of the gasket by laterally moving, and has a high degree of freedom in setting the shape, and can be formed at low cost by continuous processing.

  When the rubber material composing the gasket base material is a composite material mixed with fiber material, it becomes possible to form the material in a state where the material density is higher than the surrounding by bead formation, and pressure resistance and air tightness Can be formed in a preferable state in which the material density of the beads required further increases. Furthermore, if a composite bead composed of inner and outer double beads and a plurality of horizontal beads is formed, there is also an advantage that adverse effects caused by the hollow holes in the cylinder block and cylinder head can be prevented in most cases.

Partial plan view showing an example of a gasket Sectional view taken along line II in FIG. The operation diagram of bead forming is shown, (a) is a cross-sectional view immediately before the start of mold forming, (b) is a cross-sectional view in the middle of the press die biting, (c) is a cross-sectional view at the time of maximum press biting (A) is a sectional view of a gasket at the end of press forming for bead forming, (b) is a view showing a vulcanization process, (c) is an overall perspective view showing a gasket after bead formation. The figure which shows the forming action of a press die with one protrusion mold part, and a bead by it The figure which shows the effect | action which forms a bead on the both sides of the press type | mold with one protrusion type | mold part Sectional view showing a modified example of the bead Partial cross-sectional view of a gasket formed with a pair of non-projecting beads Plan view showing the relationship between composite shaped bead and cast hole (A) is a cross-sectional view taken along the line II in FIG. 9, and (b) is a cross-sectional view taken along the line in FIG. Bead forming action diagram of gasket with one side coating structure Action diagram for bead formation of gaskets with no metal core Sectional drawing which shows the relationship of the cross-sectional area of a bead and a bite-in part

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasket 1 'Unvulcanized or semi-cured gasket 2 Gasket base material 2' Unvulcanized or semi-vulcanized gasket base material 3 Core metal 6 Bead 7 Press type | mold 9,10 Protrusion type | mold part 9b, 10b Inclined surface 11 Recessed Mold part 12 Surface position 13, 14 Biting part

Claims (4)

The gasket base material is formed by pressing a press die from above a thin gasket base material made of a rubber material or a composite material containing a rubber material interposed between seal members arranged opposite to each other. In the method of forming a bead in
The press die has vertical side walls that protrude perpendicularly and protrude from the reference surface of the press die on both outer sides of the recessed die portion having a bottom surface deeper than the reference surface of the press die and formed in a valley shape. A pair of protruding molds,
The recessed mold part and the protruding mold part are formed by pressing with the protruding mold part on the basis of the surface position of the gasket base material, and the sectional area S1 of the biting part of the gasket base material and The relationship of the cross-sectional area S2 of the bead formed by flowing in the recessed mold part is 2S1> S2,
When the gasket base material is pressed with the press die in a state of being vulcanized or semi-vulcanized, the protruding mold part bites into a pair of biting parts and is adjacent to the biting part. A bead of a gasket characterized in that a part is sandwiched between a pair of protruding mold parts and flows into the recessed mold part to form the bead, and then the gasket base material is vulcanized by taking out from the press mold. Forming method. A method for forming a bead on a gasket according to claim 1 , comprising:
A method for forming a bead of a gasket, in which an inclined surface is provided in the protruding mold part to promote a material flow from a biting part to a bead by press molding to an unvulcanized gasket. A method for forming a bead on a gasket according to claim 1 or 2 ,
A gasket bead forming method using a composite material in which fibers are mixed in a rubber material as the gasket base material. It is a gasket formation method in any one of Claims 1-3 , Comprising:
A method for forming a bead of a gasket, wherein the gasket is formed by coating the gasket base material on a plate-shaped metal core.

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