JP2004223766A - Gasket manufacturing method and press mold structure used in the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasket manufacturing method capable of molding a unmolded structure without damaging a resin film material by excluding the gap around a cavity in the pressing state of a pressing machine and capable of easily obtaining a resin coated gasket excellent in capacity at a low cost, and a press mold structure used in the method. <P>SOLUTION: An elastic member 13 facing to a cavity 30 is arranged in one mold 11 in a pressing machine and quickly brought into close contact with another mold 12 at the time of mold clamping to eliminate the gap between the mating surfaces 14 around the cavity 30 so as not to cause a state that a rubber material goes toward the gap by an increase in the internal pressure of the cavity 30. The film material can be prevented from being torn by the pressure from the rubber material ready to go toward the gap, and the rubber material and the film material are together molded under pressure to efficiently manufacture a single wrapping type gasket excellent in sealability. The shortening and cost reduction of a manufacturing process can be achieved. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is an ion-exchange membrane method for electrolyzing an aqueous alkali metal chloride solution to produce chlorine and an alkali metal hydroxide, and is disposed between an anode chamber flange surface and a cation exchange membrane in an electrolytic cell for alkali chloride electrolysis. The present invention relates to a method for manufacturing a gasket, and more particularly to a method for manufacturing a gasket in which a resin film material having excellent corrosion resistance can be appropriately arranged on a gasket surface, and a press die structure used for the method.
[0002]
[Prior art]
Among the electrolyzers for electrolyzing an aqueous alkali chloride solution using an ion-exchange membrane, an electrolyzer for producing high-purity alkali metal hydroxides with high current efficiency is equipped with a cathode chamber with a cathode and an anode There is widely known a filter press type electrolytic cell in which the anode chamber frame is closely attached via an ion exchange membrane and a gasket. The inside of such an electrolytic cell is filled with an electrolytic solution such as an alkali and an alkali chloride, and a gas such as chlorine and hydrogen.In order to prevent substances harmful to the environment and the human body from leaking outside, the electrolytic cell is used. Various devices have been proposed to reliably seal between frames. However, since the electrolytic solution and gas containing a large amount of chlorine and hypochlorite ions are flowing in the electrolytic cell, the portion exposed to the anode chamber of the rubber gasket is gradually corroded and falls off. However, there is a problem that the sealing performance is reduced.
[0003]
In order to increase the durability of the gasket with respect to such chlorine and sodium hypochlorite, a gasket whose surface is partially covered with a fluororesin has recently been used. Many of the frame-shaped fluororesin-coated gaskets used in the electrolytic cell are large, and have a length of up to 1200 mm and a width of 2400 mm. Therefore, a special manufacturing method for obtaining an appropriate resin coating state has been proposed. . As an example of this manufacturing method, there is one described in JP-A-5-340478.
[0004]
In this conventional gasket manufacturing method, an ultra-thin fluororesin film is placed on the upper surface of a smooth unvulcanized rubber sheet, and bonded and bonded while press-vulcanizing, and at the same time giving a predetermined uneven shape to the surface. The laminated sheet is folded from the center to the back side so that the surface becomes a fluororesin film, and adhered to obtain a single-wrapped gasket whose inner core is made of rubber and whose surface is made of a fluororesin film.
[0005]
Such a resin-coated gasket has excellent corrosion resistance and is unlikely to corrode the gasket itself even when used for a long period of time. Thus, there is a problem that crevice corrosion of titanium is likely to occur. Such corrosion of titanium impairs the smoothness of the flange surface, and may cause not only the occurrence of poor sealing but also a situation in which the entire electrolytic cell becomes unusable. However, in order to solve such a problem, a technology for preventing the occurrence of crevice corrosion by backing a 0.1 to 1 mm-thick rubber on the surface of the fluororesin film on the side of the fluororesin-coated gasket that comes into contact with titanium has been disclosed in, for example, It is proposed in, for example, Japanese Patent No. 3128269.
[0006]
[Problems to be solved by the invention]
Conventional gasket production is performed as described above.Because the fluororesin film and rubber sheet are pressed and laminated and then bent, the film is arranged in a single U-shape cross-sectional shape. There was a problem that the process was complicated and the cost was high. In addition, since the bonded sheets are folded and adhered with an adhesive, it takes time to correctly align the concave and convex patterns on the front and back surfaces, and there is a problem that if the deviations occur, the sealing performance is adversely affected. Further, there is a problem that the thickness accuracy of the product is affected by the amount of the adhesive applied, and it is difficult to obtain strict accuracy, and the product is likely to be defective.
[0007]
For this reason, as a method of shortening the process and reducing cost, vulcanization is performed by heating and pressing between the upper and lower molds in a state where the fluororesin film and unvulcanized rubber are combined in a form close to the product shape in advance. There is a demand for a manufacturing method for molding, but there have been many problems in realizing this method.
[0008]
In general, when a rubber product is vulcanized by heating and pressing using a press machine, a gap is created between the upper and lower mold mating surfaces that should originally come into contact with each other in the mold clamping state at the time of pressing around the cavity. And the thickness of the product may vary. The generation of the gap in the mating surfaces of the upper and lower molds is caused by distortion of the mold due to heating, thickness accuracy of the mold, deviation of the position when unvulcanized rubber is placed on the mold, and the like. As the mold becomes larger, the gap becomes larger.
[0009]
On the other hand, when vulcanizing a sheet or block of unvulcanized rubber by heating and pressing with upper and lower molds, the amount of unvulcanized rubber supplied to the cavity is usually slightly more than the required amount of the product. However, during vulcanization molding, voids due to air or gas are not generated in the product. In this way, the unvulcanized rubber is excessively supplied to the cavity of the mold. Therefore, during the vulcanization by heating and pressurizing, the pressure of the unvulcanized rubber flowing out to the gap between the mold mating surfaces around the cavity and the unvulcanized rubber are not reduced. A pressing force is applied to the gap due to the thermal expansion of the vulcanized rubber.
[0010]
If the fluororesin film is placed in the cavity together with the unvulcanized rubber, and it is located on the rubber surface side and faces the gap between the mating surfaces, the unvulcanized resin will face this gap with the mold clamped and pressed. The extremely thin fluororesin film cannot withstand the pressure from the rubber, the fluororesin film is damaged and the rubber leaks into the gaps, and the final molded product may be defective with the rubber exposed. However, there is a problem that the property is extremely high, and such integral molding has not been conventionally performed.
[0011]
The present invention has been made in order to solve the above-mentioned problems, and it is possible to mold an unmolded component without breaking a resin film material by eliminating a gap around a cavity in a pressurized state of a press machine, and a resin having excellent performance. It is an object of the present invention to provide a gasket manufacturing method capable of obtaining a coated gasket easily and at low cost, and a press die structure used in the manufacturing method.
[0012]
[Means for Solving the Problems]
The gasket manufacturing method according to the present invention uses a mold composed of upper and lower molds, and at least an unmolded component obtained by previously combining at least a substantially sheet-like rubber material and a resin film material in a cavity between the molds. In the gasket manufacturing method of integrally press-molding while heating, the film material, the rubber material, the rubber material in a predetermined range from one surface of the rubber material around the edge to the other surface side The unmolded component is formed in combination in a wrapped state covering a substantially U-shaped cross section, and a substantially band-shaped portion is formed around the cavity periphery facing the film material arrangement portion of the unmolded component in one of the dies. The elastic member is disposed as a state at least protruding toward the other mold from the mating surface position of one mold, and the elastic member and the other mold are pressed against each other before the mold is in a mold clamped state, Elastic part Between the one type and, as well as with obtaining a state where there is no gap between the elastic member and the other type is to utilize the side surface of the elastic member facing the cavity as part of the mold.
[0013]
As described above, in the present invention, the elastic member facing the cavity is provided in one of the molds of the press machine, and the elastic member is brought into contact with the other mold as soon as possible when the mold is clamped, so that the elastic member is brought into close contact with the mold mating surface around the cavity. By eliminating the gap between the rubber materials and preventing the rubber material from going to the gap with the increase in the pressure inside the cavity from the beginning, it is possible to prevent the film material from being broken by the pressure from the rubber material going to the gap. In addition to the fact that the pressure exerted on the film material can be offset by the elastic repulsive force of the elastic member, the deformation and breakage of the film material can be reliably prevented. An excellent single-package type gasket can be manufactured, thereby shortening the manufacturing process and reducing costs. In addition, since the rubber material and the film material are pressurized at the time of molding and integrated in a product shape, the film material is hardly peeled off, and a gasket excellent in durability can be obtained.
[0014]
In the gasket manufacturing method according to the present invention, if necessary, a groove is provided in a predetermined range of a peripheral edge of a cavity facing a film material arrangement portion of the unmolded component in one of the molds. The elastic member is detachably fitted in the groove.
As described above, in the present invention, a groove is provided around the periphery of the cavity of one of the molds, an elastic member is fitted into the groove, and the elastic member is retained in the groove and used for molding of an unmolded component. There is no need to use a member for fixing the elastic member that hinders the deformation of the elastic member, and the compression and restoration of the elastic member is allowed for the entire elastic member including the inside of the groove, and it is not molded facing the cavity of the elastic member. The elastic member can be securely brought into close contact with the other mold while suppressing excessive deformation of the portion of the component that comes into contact with the film material, and deterioration of the shape of the molded product can be prevented.
[0015]
In addition, the gasket manufacturing method according to the present invention may include, as necessary, a mating surface portion in which one of the upper and lower molds is located on the opposite side of the one mold between the grooves with the cavity therebetween. A burr groove communicating with the inside of the cavity in a predetermined range is provided along the cavity, and allows a surplus of the rubber material forming the unmolded component to flow into the burr groove in a mold-clamped state. is there.
As described above, in the present invention, a burr groove communicating with the inside of the cavity is provided on the mating surface of any one of the molds on the side opposite to the elastic member with the cavity interposed therebetween. Of these, the excess amount at the time of mold clamping can be escaped into the burr groove, so that the pressure of the rubber material in the cavity in the mold clamping state does not become excessively large, and the rubber material from the inside of the film material faces outward. By suppressing the pressing force, deformation and breakage of the film material can be prevented.
[0016]
In the gasket manufacturing method according to the present invention, the contact surface between the mold and the elastic member of the other mold facing the groove of one mold may be pressurized by the other mold, if necessary. It is arranged so as to be retracted in the pressing direction from the position of the tip of the convex portion in the direction, and a predetermined range of the cavity forming surface adjacent to the contact surface is made to be the same plane continuous with the contact surface, During the pressure molding, the elastic member and the other mold are brought into contact with each other immediately before the convex portion of the other mold hits the unmolded component.
As described above, in the present invention, the contact surface of the other mold with the elastic member is retreated from the tip of the convex portion in the pressing direction of the other mold and is formed to be continuous with the cavity side. Even when the rubber material starts to be pressed by being pressed by the convex part of the other mold that comes into contact with the rubber material, the pressurization is still performed because the space is still left in the vicinity of the contact surface and the elastic member in the cavity. After a little progress, the rubber material and the film material forming the unmolded component reach the space portion and fill it, and the pressure rise of the rubber material near the contact surface and the elastic member is kept within an appropriate range, In the mold clamping state, the pressure of the rubber material does not become excessively high inside the film material, and the deformation and breakage of the film material can be more reliably prevented.
[0017]
Further, the press die structure according to the present invention comprises upper and lower pairs of dies which are disposed close to and separated from each other in a press machine, and at least a substantially sheet-like rubber material and a resin material are formed in a cavity between the dies. In a press mold structure for gasket molding to obtain a molded product by applying pressure while heating an unmolded component previously combined with a film material, one of the dies is one of the unmolded components. A groove is provided in a predetermined range of the cavity periphery facing the film material arrangement portion, and a substantially belt-shaped elastic member is detachably attached to the groove at least in a state protruding from the mating surface position of one mold toward the other mold side. The elastic member and the other mold are pressed against each other before the mold enters the mold-clamped state, and there is no gap between the elastic member and the groove and between the elastic member and the other mold. Along with Side of the elastic member facing the cavity in which is part of the type.
As described above, in the present invention, the elastic member facing the cavity is provided in one of the press dies, and the elastic member is brought into contact with the other mold as soon as possible during mold clamping, so that the mold around the cavity can be aligned. By eliminating the gap between the surfaces and preventing the rubber material from going to the gap with the increase in the pressure inside the cavity from the beginning, the film material can be broken by the pressure from the rubber material going to the gap. In addition to being able to cancel the pressure applied to the film material by the elastic repulsion of the elastic member, the deformation and breakage of the film material can be reliably prevented. Can be manufactured, and the manufacturing process can be shortened and the cost can be reduced.
[0018]
In addition, the press mold structure according to the present invention may have a mating surface portion in which one of the upper and lower sides of the mold is located on the opposite side of the groove portion of the one mold with the cavity as needed. A burr groove communicating with the inside of the cavity is provided along the cavity in a predetermined range, and in a mold clamped state, a surplus of the rubber material forming the unmolded component is allowed to flow into the burr groove. It is.
As described above, in the present invention, a burr groove communicating with the inside of the cavity is provided on the mating surface of any one of the molds on the side opposite to the elastic member with the cavity interposed therebetween. Of these, the excess amount at the time of mold clamping can be escaped into the burr groove, so that the pressure of the rubber material in the cavity in the mold clamping state does not become excessively large, and the rubber material from the inside of the film material faces outward. By suppressing the pressing force, deformation and breakage of the film material can be prevented.
[0019]
Further, in the press die structure according to the present invention, if necessary, the contact surface of the other die facing the groove portion of one die with the elastic member may be added to the other die. It is arranged so as to be retracted in the pressing direction from the tip position of the convex portion in the pressing direction, and a predetermined range of the cavity forming surface adjacent to the contact surface is made the same plane that is continuous with the contact surface. The elastic member and the other mold come into contact with each other immediately before the convex portion of the other mold hits the unmolded component during pressure molding.
As described above, in the present invention, the contact surface of the other mold with the elastic member is formed to be receded from the tip of the convex portion of the other mold and to be continuous with the cavity side, so that the rubber member first contacts the rubber material at the time of mold clamping. Even if the rubber material starts to be pressed by being pressed by the convex part of the other mold, the space is still left near the contact surface in the cavity and the elastic member. The rubber material and the film material forming the mold component reach the space portion and fill the space portion, so that the pressure rise of the rubber material in the contact surface and the vicinity of the elastic member is kept within an appropriate range, and the rubber material in the mold clamped state The pressure of the material is not excessively increased inside the film material, and the deformation and breakage of the film material can be more reliably prevented.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a gasket manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. 1 is a cross-sectional view of a main part of a mold used in the gasket manufacturing method according to the present embodiment in a separated state and a mold-clamped state. FIG. 2 is a schematic perspective view of a gasket obtained by the gasket manufacturing method according to the present embodiment. FIG. 3 is a sectional view of an essential part of an unmolded component used in the gasket manufacturing method according to the present embodiment and the obtained gasket.
[0021]
As shown in each of the drawings, the gasket manufacturing method according to the present embodiment includes a substantially band-shaped elastic member 13 at an inner peripheral edge position of a substantially frame-shaped cavity 30 in a lower mold 11 of a pair of upper and lower molds 10 of a press. Are arranged so as to protrude slightly upward from the mold mating surface 14, and the elastic member 13 of the lower mold 11 and the upper mold 12 are pressed against each other before the mold 10 enters the mold clamped state. A state where there is no gap between the member 13 and the upper mold 12 and the lower mold 11 is obtained, and the rubber material 21 is placed between the molds 10 while using the side surface of the elastic member 13 facing the cavity 30 as a part of the mold. The non-molded component 20 composed of the film material 22 is heated and pressed to mold the gasket 1 in a resin-coated state.
[0022]
The lower mold 11 is provided with a groove 15 along the inner peripheral edge of the substantially frame-shaped cavity 30. An elastic member 13 is provided in the groove 15 so that the upper portion of the lower mold 11 is slightly larger than the mating surface 14 of the lower mold 11. It is configured to be detachably fitted to the side, that is, to protrude upward, so that there is no gap between the elastic member 13 and the groove 15 at the time of mold clamping. The protrusion height of the elastic member 13 is preferably about 0.5 to 2 mm from the position of the mating surface 14 of the lower die. However, the thickness of the rubber material 21 serving as a gasket core material, the product height, and a pressing machine It can also be adjusted according to the thickness direction accuracy of production equipment such as a mold.
[0023]
In the lower mold 11, the outer peripheral side of the cavity 30, which is opposite to the groove 15 in the portion of the mating surface 14 around the cavity 30 across the cavity 30, that is, the film material 22 of the unmolded component 20 is disposed. The configuration is such that the burr groove 16 is provided around the cavity 30 corresponding to the portion not to be formed. The burr groove 16 communicates with the inside of the cavity 30 to make it easy for excess rubber material 21 to flow out of the cavity 30 toward the outer periphery of the cavity 30 when the mold is clamped, thereby suppressing an increase in the internal pressure of the cavity 30. The size of the burr groove 16 is such that a larger capacity than a preset margin can be secured for the cavity 30 of the rubber material 21 to be supplied.
[0024]
The elastic member 13 is a substantially band-shaped rubber body having a substantially rectangular cross section in a state where no external force is applied. As a constituent material of the elastic member 13, it is desirable to use a heat-resistant rubber, for example, silicone rubber, fluorine rubber, hydrogenated acrylonitrile butadiene rubber (HNBR), or the like. When the elastic member 13 is in direct contact with the fluororesin, any of the rubbers described above can be used. In particular, in view of cost and durability, silicone rubber is preferable. In the case of manufacturing a gasket having a thin rubber backing on one side, silicone rubber is desirable in terms of mold release properties. The hardness (JIS K6253 type A) of the elastic member 13 is preferably from 65 to 85.
[0025]
The unmolded component 20 is a film-like material 22 made of a fluororesin, which is formed on a substantially sheet-like rubber material 21 having a rectangular frame shape, by turning the inner peripheral edge from one surface of the rubber material 21 to the other surface side. The rubber material 21 is partially wrapped so as to partially cover the rubber material 21 in a substantially U-shape in a predetermined range, and another thin rubber sheet 23 for backing is overlaid on the surface of the film material 22 on one surface side of the rubber material 21. It is a combination. The rubber material 21 of the unmolded component 20 is formed into a sheet in advance in a larger amount than that required for the product in the same manner as in the prior art so that no air or gas voids are formed in the product during pressure molding. The entire product may be supplied and arranged between the molds 10 in an amount exceeding the cavity capacity of the mold 10 that defines the product shape. When the rubber material 21 and the film material 22 are bonded and combined as the unmolded component 20, it is desirable to perform a predetermined surface treatment on the fluororesin film material 22 in order to ensure mutual bonding.
[0026]
The rubber material 21 is an uncrosslinked rubber material constituting a main part of the gasket, and is crosslinked (vulcanized) by heating and pressing by the mold 10. The material of the rubber material 21 can be appropriately selected according to the use conditions of the gasket 1. For example, ethylene propylene rubber (EPDM), acrylonitrile butadiene rubber (NBR), hydrogenated acrylonitrile butadiene rubber (HNBR), and fluorine rubber (FKM) or the like can be used.
[0027]
The film material 22 is a thin film made of a fluororesin having excellent corrosion resistance. Examples of the fluororesin used for the film material include polytetrafluoroethylene (PTFE) and tetrafluoroethylene perfluoroalkyl vinyl ether. Copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), and polyvinylidene fluoride (PVDF) And the like, but are not limited thereto, and other fluororesins may be used. The thickness of the film material 22 is preferably in the range of 0.01 mm to 0.5 mm in consideration of sealing properties, chemical resistance, and the like. A more preferable thickness range is 0.05 mm to 0.25 mm.
[0028]
Next, a gasket manufacturing process based on the gasket manufacturing method according to the present embodiment will be described. A rectangular frame-shaped unformed component 20 in which a rubber material 21, a resin film material 22, and a rubber sheet 23 are combined in advance is placed in the cavity 30 of the lower die 11, and then heated and pressed by the upper and lower dies. When the operation is started, the upper mold 12 approaches the unmolded component 20, and the convex portion in the pressing direction of the upper mold 12 that presses the portion that becomes the concave portion of the gasket 1 after molding contacts the unmolded component 20. Immediately before, the elastic member 13 and the upper mold 12 come into contact with each other. Next, the pressing of the unmolded component 20 is started by the convex portion of the upper mold 12.
[0029]
The elastic member 13 comes into contact with the upper mold 12 before the upper and lower molds enter the mold-clamped state, and comes into close contact with the upper mold 12 by a repulsive force accompanying compression to eliminate a gap, and the side surface of the elastic member 13 facing the cavity 30 is It becomes a part of the mold and cancels the pressure applied to the film material 22 in the mold clamping state, thereby preventing the film material 22 from being deformed. In addition, the excess rubber material 21 can flow out into the burr groove 16 on the opposite side of the elastic member 13 with the cavity 30 therebetween, so that even when the mold is clamped, the internal pressure of the cavity 30 excessively increases. The extremely thin film material 22 is not damaged, and the rubber material 21 is not exposed.
[0030]
In this way, the unmolded component 20 is integrally molded under pressure while being heated in the cavity 30, and the rubber material 21 is also in a vulcanized state to have a substantially frame-shaped gasket product shape. Since the rubber material 21 and the film material 22 are integrated in a product shape, the film material 22 is hardly peeled off and has excellent durability. The gasket 1 obtained by molding has a shape in which a part of the surface is covered with a film material 22 and one side is rubber-backed, so that crevice corrosion of titanium which is an anode chamber frame material of an electrolytic cell can be prevented.
[0031]
As described above, in the gasket manufacturing method according to the present embodiment, the elastic member 13 facing the cavity 30 is disposed in the lower mold 11, and the elastic member 13 is brought into contact with the upper mold 12 as soon as possible when the mold is clamped. Since the gap between the mold mating surfaces 14 around the cavity 30 is eliminated to prevent the rubber material 21 from going to the gap with the increase in the pressure in the cavity 30 from the beginning, the film material 22 is directed to the gap. In addition to being able to prevent the film material 22 from being broken by the pressure from the rubber material 21 and to cancel the pressure applied to the film material 22 by the elastic repulsive force of the elastic member 13, the deformation and breakage of the film material 22 can be reliably prevented. The gasket 21 having excellent sealing properties can be manufactured efficiently by press-molding the film material 21 and the film material 22 together, and the manufacturing process can be shortened and the cost can be reduced. In addition, a burr groove 16 communicating with the cavity 30 is provided around the mating surface 14 on the outer peripheral side of the cavity 30, and the excess amount of the rubber material 21 previously supplied to the cavity 30 during mold clamping is used as the burr groove 16. As a result, the pressure of the rubber material 21 in the cavity 30 in the mold-clamped state is not excessively increased, and the outward pressing force of the rubber material 21 from the inside of the film material 22 is suppressed, so that the Deformation and breakage can be prevented.
[0032]
In the gasket manufacturing method according to the embodiment, the contact portion of the upper mold 12 with the elastic member 13 is on the same plane as the convex portion of the upper mold 12 in the pressing direction (downward), At the same time as the pressing by the upper mold 12 is started, the vicinity of the elastic member 13 is filled with the rubber material 21 and the film material 22 forming the unmolded component 20, but is not limited thereto, and as shown in FIG. The contact surface 17 of the upper die 12 with the elastic member 13 is set back in the pressing direction from the position of the tip of the convex portion of the upper die 12, that is, displaced upward, and is adjacent to the contact surface 17. It is also possible to adopt a configuration in which a predetermined range among the constituent surfaces of the cavity 30 is formed as the same plane that is continuous with the contact surface 17, and the convex portion of the upper mold 12 that first contacts the rubber material 21 at the time of mold clamping is pressed. Even if the rubber material 21 starts to be pressed, the space is still left in the vicinity of the contact surface 17 and the elastic member 13 in the cavity 30, so that the rubber material 21 and the film material 22 Reaches the space portion and fills the space portion, the pressure rise of the rubber material 21 in the vicinity of the contact surface 17 and the elastic member 13 is kept within an appropriate range, and the pressure of the rubber material 21 is reduced in the mold-clamped state. The inside of the film 22 does not become excessively high, and the deformation and breakage of the film material 22 can be more reliably prevented.
[0033]
Further, in the gasket manufacturing method according to the embodiment, the side surface of the elastic member 13 opposite to the side surface facing the cavity 30 is in close contact with the lower mold 11 or the upper mold 12 in a mold-clamped state without any gap. Is a configuration in which no space is generated unlike the cavity 30 side, but is not limited to this. As shown in FIG. 4, the vicinity of the opposite side surface of the elastic member 13 in the lower mold 11 or the upper mold 12 is defined by each mold. It is also possible to adopt a configuration in which the elastic member 13 is retreated in the pressing direction, and a separate space 31 is formed on the side opposite to the cavity 30 of the elastic member 13 in the mold clamping state. Since the swelling deformation can be performed not only on the cavity 30 side but also on the space 31 side, the amount of deformation of the elastic member 13 toward the cavity 30 can be suppressed to an appropriate range. It is to improve the molding shape accuracy of which is molded Te.
[0034]
In the gasket manufacturing method according to the above-described embodiment, the product gasket 1 and the unmolded component 20 before molding are formed in a rectangular frame shape. However, the present invention is not limited to this. As in the case of gasket manufacturing, a cavity 30 having an elastic member 13 on the inner peripheral side and a burr groove 16 on the outer peripheral side is formed in a frame shape other than an annular or rectangular shape, and an unmolded component 20 having a shape corresponding to this is formed. A gasket other than a rectangular frame shape may be manufactured by press-molding between molds. Furthermore, although the elastic member 13 and the burr groove 16 in the mold 10 are arranged on the lower mold 11 side, the present invention is not limited to this, and the elastic members 13 and the burr grooves 16 may be arranged on the upper mold 12 side.
[0035]
Further, in the gasket manufacturing method according to the embodiment, the rubber is lined on the surface of the film material 22 on one surface of the gasket 1, but between the flange surface of the gasket 1 and the surface of the gasket 1. In a use environment in which crevice corrosion or the like cannot occur, as shown in FIG. 5, a structure in which no rubber for lining is provided and the film material 22 is exposed on the surface as it is can be provided, and a simpler structure can be obtained. The cost can be reduced.
[0036]
【Example】
Hereinafter, the results of manufacturing a gasket based on the gasket manufacturing method according to the present invention and evaluating the post-molding state of the obtained molded product will be described.
The gasket manufactured by the gasket manufacturing method according to the present invention is a single-wrapped fluororesin-coated gasket with a rubber backing on one side, and the product shape is a rectangular frame having a length of 1200 mm, a width of 2400 mm, a width of 30 mm, and a thickness of 2 mm, Ethylene propylene rubber is used as the rubber material, and polytetrafluoroethylene is used as the fluororesin film material.
[0037]
Next, a manufacturing process to which the gasket manufacturing method according to the present invention is applied will be described. First, as a first step, a rubber material as an unmolded component was manufactured. The rubber material was prepared by rolling several pieces of rubber material having a predetermined composition into a sheet having a smooth width of 30 mm and a thickness of 2 mm using a calender roll machine, and cutting it into lengths of 1200 mm and 2400 mm.
On the other hand, for the surface treatment of the fluororesin film material to ensure adhesion, a complex compound solution obtained by adding metallic sodium to a naphthalene tetrahydrofuran solution was used. An organosiloxane was used as an adhesive between the rubber material and the film material. The rubber material is wrapped with the fluororesin film material (width 50 mm, thickness 0.05 mm) which has been subjected to the surface treatment for bonding in this manner, and the backing rubber is formed on the fluororesin film material which has also been subjected to the surface treatment in advance on the upper surface. A vulcanized rubber sheet (thickness 0.5 mm) was overlaid to obtain an unmolded component.
This unmolded component was placed on the lower mold of the mold, and the vulcanization temperature was 160 ° C., the vulcanization time was 20 minutes, the press pressure was 68.6 MPa (70 kgf / cm) ² ). As a result, a gasket as a molded product was manufactured. The obtained gasket had no damage to the film material and had a good adhesion state and appearance between the rubber material and the film material.
[0038]
Further, as another example of applying the gasket manufacturing method according to the present invention, a gasket was obtained by performing molding while changing the thickness of the film material. As Example 2, molding was performed in the same manner as described above using a fluororesin film material having a thickness of 0.1 mm. In addition, as Example 3, molding was performed in the same manner as described above using a fluororesin film material having a thickness of 0.25 mm. The conditions other than the thickness of the film material in each embodiment are the same.
After the molding, gaskets having good adhesion and appearance were obtained in Examples 2 and 3 without damage to the film material.
From the above, it was confirmed that, even if the thickness of the fluororesin film material used was as thin as 0.05 mm to 0.25 mm, a good gasket as a product could be obtained without any problem by the manufacturing process based on the gasket manufacturing method according to the present invention. did it.
[0039]
【The invention's effect】
As described above, according to the present invention, the elastic member facing the cavity is disposed in one of the dies in the press machine, and the elastic member is quickly brought into contact with the other die when the mold is clamped, and is brought into close contact with the other die to perform mold matching around the cavity. By eliminating the gap between the surfaces and preventing the rubber material from going to the gap with the increase in the pressure inside the cavity from the beginning, the film material can be broken by the pressure from the rubber material going to the gap. In addition to being able to cancel the pressure applied to the film material by the elastic repulsive force of the elastic member, the deformation and breakage of the film material can be reliably prevented, and the rubber material and the film material are pressed together and efficiently sealed. This makes it possible to manufacture a single-package type gasket having excellent properties, and has the effect of shortening the manufacturing process and reducing costs. In addition, since the rubber material and the film material are pressurized during molding and integrated in a product shape, the film material is less likely to peel off, and an effect of obtaining a gasket having excellent durability can be obtained.
[0040]
Further, according to the present invention, a groove is provided around the periphery of the cavity of one of the molds, an elastic member is fitted into the groove, and the elastic member is used for molding an unmolded component while holding the elastic member in the groove. There is no need to use a member for fixing the elastic member that hinders the deformation of the elastic member, and the compression and restoration of the elastic member is allowed for the entire elastic member including the inside of the groove, and it is not molded facing the cavity of the elastic member. The elastic member can be securely brought into close contact with the other mold while suppressing excessive deformation of the portion of the component that comes into contact with the film material, and the effect of preventing deterioration of the shape of the molded product can be obtained.
[0041]
Further, according to the present invention, a burr groove communicating with the inside of the cavity is provided around the mating surface of any of the molds on the side opposed to the elastic member with the cavity interposed therebetween, so that the rubber material previously supplied to the cavity in a large amount is formed. Of these, the excess amount at the time of mold clamping can be escaped into the burr groove, so that the pressure of the rubber material in the cavity in the mold clamping state does not become excessively large, and the rubber material from the inside of the film material faces outward. This has the effect that deformation and breakage of the film material can be prevented by suppressing the pressing force.
[0042]
Further, according to the present invention, the contact surface of the other mold with the elastic member is retreated from the tip of the convex portion in the pressing direction of the other mold and has a shape that is continuous with the cavity side, and the first mold is closed at the time of mold clamping. Even when the rubber material starts to be pressed by being pressed by the convex part of the other mold that comes into contact with the rubber material, the pressurization is still performed because the space is still left in the vicinity of the contact surface and the elastic member in the cavity. After a little progress, the rubber material and the film material forming the unmolded component reach the space portion and fill it, and the pressure rise of the rubber material near the contact surface and the elastic member is kept within an appropriate range, In the clamped state, the pressure of the rubber material does not become excessively high inside the film material, which has an effect that deformation and breakage of the film material can be more reliably prevented.
[Brief description of the drawings]
FIG. 1 is a sectional view of a main part of a mold used in a gasket manufacturing method according to an embodiment of the present invention in a separated state and a mold clamped state.
FIG. 2 is a schematic perspective view of a gasket obtained by a gasket manufacturing method according to one embodiment of the present invention.
FIG. 3 is a cross-sectional view of a main part of an unmolded component and a gasket obtained in a gasket manufacturing method according to an embodiment of the present invention.
FIG. 4 is a sectional view of a main part of a separated state and a closed state of another mold used in the gasket manufacturing method according to the embodiment of the present invention.
FIG. 5 is a cross-sectional view of main parts of another unmolded structure used in the method of manufacturing a gasket according to one embodiment of the present invention and a gasket to be obtained.
[Explanation of symbols]
1 gasket
10 Mold
11 Lower mold
12 Upper type
13 Elastic member
14 mating surface
15 Groove
16 Burr groove
17 Abutment surface
20 unformed components
21 Rubber materials
22 Film materials
23 Rubber sheet
30 cavities
31 space

Claims (7)

Using a mold composed of an upper and lower mold, an unmolded component obtained by previously combining at least a substantially sheet-like rubber material and a resin film material is integrally pressed while heating in a cavity between the molds. In the method of manufacturing a gasket to be molded,
Combining the film material with the rubber material in a single wrapped state covering the rubber material in a substantially U-shaped cross section in a predetermined range from one surface of the rubber material around the edge to the other surface side. With and without mold components
A state in which a substantially band-shaped elastic member is at least protruded from the mating surface position of one of the molds toward the other mold on the periphery of the cavity facing the film material arrangement portion of the unmolded component in one of the molds. Arrange,
The elastic member and the other mold are pressed against each other before the mold enters the mold-clamped state, to obtain a state without a gap between the elastic member and the one mold, and between the elastic member and the other mold, A method for manufacturing a gasket, wherein a side surface of an elastic member facing the cavity is used as a part of a mold. The method for manufacturing a gasket according to claim 1,
A groove is provided in a predetermined range of a cavity periphery facing a film material arrangement portion of the unmolded component in one of the molds, and the elastic member is detachably fitted in the groove. Gasket manufacturing method. The method of manufacturing a gasket according to claim 1 or 2,
One of the upper and lower molds is formed along a cavity with a burr groove communicating with the cavity within a predetermined range of a mating surface portion located on the opposite side of the one mold with the groove portion separated from the cavity. A method of manufacturing a gasket, wherein a surplus of a rubber material constituting the unmolded component is allowed to flow into the burr groove in a mold-clamped state. The gasket manufacturing method according to any one of claims 1 to 3,
The contact surface between the mold and the elastic member of the other mold facing the groove of one mold has receded in the pressing direction from the tip of the convex portion in the pressing direction in the other mold. While being arranged, a predetermined range of the cavity constituting surface adjacent to the contact surface is made to be the same plane that is continuous with the contact surface, and at the time of pressure molding, the convex portion of the other mold is A gasket manufacturing method, wherein an elastic member and the other mold are brought into contact with each other immediately before hitting an unformed component. An unmolded structure comprising upper and lower sets of dies which are disposed close to and separated from each other in a press machine, and at least a substantially sheet-like rubber material and a resin film material are previously combined in a cavity between the dies. In the press mold structure for gasket molding to obtain a molded product by pressing while heating the product,
One of the molds is provided with a groove in a predetermined range of a peripheral edge of the cavity facing the film material arrangement portion of the unmolded component, and a substantially band-shaped elastic member is provided in the groove with a mating surface of the one mold. It is detachably fitted as a state at least protruding toward the other mold side from the position,
The elastic member and the other mold are pressed against each other before the mold enters the mold-clamped state, so that there is no gap between the elastic member and the groove, and between the elastic member and the other mold, and the cavity is formed. Wherein the side surface of the elastic member facing the surface becomes a part of the mold. The press die structure according to claim 5,
One of the upper and lower molds is formed along a cavity with a burr groove communicating with the cavity within a predetermined range of a mating surface portion located on the opposite side of the one mold with the groove portion separated from the cavity. A press die structure, which is provided around and allows a surplus of the rubber material constituting the unmolded component to flow into the burr groove in a mold-clamped state. The press mold structure according to claim 5 or 6,
The contact surface between the mold and the elastic member of the other mold facing the groove of one mold has receded in the pressing direction from the tip of the convex portion in the pressing direction in the other mold. While being arranged, a predetermined range of the cavity constituting surface adjacent to the contact surface is a coplanar surface continuous with the contact surface,
A press die structure, wherein the elastic member and the other die abut each other immediately before the convex portion of the other die hits the unformed component during pressure molding.

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