Manufacturing method for gasket, and gasket

Abstract

To provide a manufacturing method for a gasket capable of suppressing generation of molding failure, and a gasket.SOLUTION: A manufacturing method for a gasket comprises using a mold having: a cavity cv for forming a gasket body; an annular burr pool br provided on an inner peripheral surface side with respect to the cavity cv; an annular burr path bd provided between the cavity cv and the burr pool br; and a plurality of gates provided at positions corresponding to a plurality of recess parts 311 provided on an inner peripheral surface of a reinforcing ring 310.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a gasket and a gasket. [Background technology]

[0002] Conventionally, there is known a gasket that seals the gap between the end faces of two components, which has a gasket body integrally formed on the inner peripheral surface of a reinforcing ring. In this gasket, the reinforcing ring functions as a spacer to keep the distance between the end faces of the two components constant, as a backup ring to suppress abnormal deformation of the gasket body, and to increase the rigidity of the gasket. The gasket configured as described above is obtained by molding the gasket body by insert molding using the reinforcing ring as an insert part.

[0003] A method for manufacturing a gasket according to the conventional technology will be described with reference to Fig. 6 to Fig. 8. Fig. 6 is a plan view of a mold according to the conventional technology, showing the main components inside the mold in a see-through manner. Fig. 7 and Fig. 8 are manufacturing process diagrams of a gasket according to the conventional technology. Note that the cross-sectional view of the mold in Fig. 7(a) corresponds to the CC cross-sectional view in Fig. 6, and the cross-sectional views of a molded product such as a gasket in Fig. 7 and Fig. 8 correspond to the CC cross-sectional view of the molded product after molding in the mold shown in Fig. 6.

[0004] In the mold 600 used for insert molding, a cavity 620A for forming a gasket main body 620, a burr path 630A, and a burr pool 640A are provided in the order from the outside to the inside in the radial direction inside a reinforcing ring 610 arranged in the mold 600. The mold 600 includes a lower mold 600A and an upper mold 600B. The upper mold 600B includes a pot 650, which is a material chamber for supplying molding material, and a gate 660 for supplying the molding material in the pot 650 toward the cavity 620A. In the conventional technology, a tip 661 of the gate 660 is provided so as to open to the burr pool 640A. As a result, the molding material supplied from the gate 660 is supplied from the burr pool 640A through the burr path 630A to the cavity 620A.

[0005] FIG. 7(a) shows a state in which cavity 620A has been filled with molding material. When the mold is opened after molding is completed, burrs 640 are separated from the molding material inside gate 660. FIG. 7(b) shows a state in which the insert molded product (intermediate product 615A) has been removed from mold 600. In the case of a molding material with high fluidity, the thickness of burr path 630A can be made thin. In this case, since the film 630 formed by burr path 630A is thin, burrs 640 can be removed manually, for example by tearing burrs 640 off with fingers. In this way, gasket 615, which is the final product, is obtained.

[0006] However, in the case of a material with low fluidity (for example, a rubber material such as HNBR), if the thickness of the burr passage 630A is made thin, the molding material does not flow easily into the cavity 620A, which can result in air pockets due to insufficient filling of the material, or flow marks and weld lines that adversely affect the quality of the product.

[0007] Therefore, it is necessary to make the thickness of the burr path 630A part a predetermined thickness or more. Generally, if this thickness is set to 0.1 mm or more, it is not possible to remove the burr 640 manually. Therefore, in such a case, as shown in Fig. 8, a work process is required in which, with the insert molded product placed in the die 710, a punch 720 is moved downward (see Fig. 8(a)) to punch out the burr 640 (see Fig. 8(b)).

[0008] However, the size of the gasket 615 is large (generally, the inner diameter is 100 mm or more). If the thickness of the gasket body 620 is increased, the waviness of the gasket body 620 in the planar direction also increases, making it difficult to punch out the burrs 640. In other words, the surface of the inner peripheral surface (punched cross section) of the gasket body 620 becomes rough, and thread-like punched waste is generated. In addition, in the conventional manufacturing method, even if the thickness of the burr path 630A is increased, it cannot be said that the problems of air pockets, flow marks, and weld lines described above are sufficiently solved. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 4993077 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a method for manufacturing a gasket, and a gasket, which are capable of suppressing the occurrence of molding defects. [Means for solving the problem]

[0011] The present invention employs the following means to solve the above problems.

[0012] That is, the method for producing a gasket of the present invention is as follows: A method for manufacturing a gasket comprising: an annular member having an inner peripheral surface on which a plurality of recesses recessed toward an outer peripheral surface are provided at intervals in the circumferential direction; and an annular gasket body made of an elastomer, the gasket body having a plurality of protrusions provided so as to fit into the plurality of recesses, respectively, and integrally provided on the inner peripheral surface of the annular member, the method comprising the steps of: a step of clamping the annular member in a state in which the annular member is disposed in the mold using a mold having a cavity for forming the gasket body, an annular space provided on the inner peripheral side of the cavity, an annular flow path provided between the cavity and the annular space, and a plurality of gates provided at positions corresponding to the plurality of recesses; filling the molding material through the plurality of gates; A mold opening step of the mold; A step of removing the insert molded product from the mold; removing the portion formed by the annular space from the molded article formed by the cavity such that the portion formed by the annular passage is separated; The present invention is characterized by having the following.

[0013] According to the present invention, the molding material is supplied directly from the gate to the cavity for molding the gasket body, and flows through the annular flow path into the annular space provided on the inner peripheral surface side of the cavity. Therefore, the formation of air pockets due to insufficient filling of the material in the cavity is suppressed, and the formation of flow marks and weld lines that adversely affect the quality of the gasket body can also be suppressed. In addition, when a material with low fluidity is used, there is no problem with the product even if the thickness of the annular flow path portion is thinned and insufficient filling of the material occurs in the annular space or flow marks and weld lines are formed on the burrs. Therefore, by thinning the thickness of the annular flow path portion, the burrs can be manually torn off from the molded product molded by the cavity. This eliminates the need for a process of punching out the burrs using a punch or the like, and does not cause problems that may occur due to the punching operation.

[0014] In the mold used for molding the gasket body, The tip of the gate may be configured to expand in diameter toward the cavity.

[0015] This allows the gasket body to be easily attached to the molded part inside the gate when it is released from the mold. A portion that protrudes toward the gate side is likely to be formed in the portion that is separated from the material, and this portion can be prevented from becoming recessed.

[0016] In the mold used for molding the gasket body, The cavity may have a surface facing the tip of the gate that has a protrusion protruding in a direction away from the tip of the gate.

[0017] This prevents the gasket body from becoming partially thin even if the portion of the gasket body where the gasket body and the molding material in the gate are separated during demolding becomes concave.

[0018] In the mold used for molding the gasket body, It is preferable that a material pool for forming a weld line with material supplied from adjacent gates be provided on the inner peripheral surface side of the annular space.

[0019] This prevents the formation of weld lines in the burrs, and more reliably prevents the formation of weld lines in the gasket body.

[0020] In the mold used for molding the gasket body, The annular passage may have a portion closer to the pool of material that is thicker than a portion further away from the pool of material.

[0021] This prevents flow marks from being formed on the burrs, and therefore more reliably prevents flow marks from being formed on the gasket body.

[0022] The gasket of the present invention is an annular member having an inner circumferential surface on which a plurality of recesses are provided at intervals in a circumferential direction, the recesses being recessed toward an outer circumferential surface side; a ring-shaped gasket body made of an elastomer, the gasket body having a plurality of protrusions each provided to fit into the plurality of recesses, and integrally provided on an inner peripheral surface of the ring-shaped member; A gasket comprising: The gasket is characterized in that a gate mark is provided on each of the plurality of protrusions, and a mark where burrs have been removed is provided on the inner peripheral surface of the gasket body.

[0023] Each of the plurality of convex portions may be provided with a protruding portion that protrudes in a direction away from the gate mark.

[0024] The above configurations may be combined as much as possible. Effect of the Invention

[0025] As described above, according to the present invention, the occurrence of molding defects can be suppressed. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a plan view of a mold according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a manufacturing process diagram of a gasket according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a manufacturing process diagram of a gasket according to an embodiment of the present invention. [Figure 4] FIG. 4 is a plan view of a gasket according to an embodiment of the present invention. [Diagram 5] FIG. 5 is an explanatory diagram of a gasket according to an embodiment of the present invention. [Figure 6] FIG. 6 is a plan view of a mold according to the prior art. [Figure 7] FIG. 7 is a manufacturing process diagram of a gasket according to the conventional technology. [Figure 8] FIG. 8 is a manufacturing process diagram of a gasket according to the conventional technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions, and the like of the components described in the embodiment are not intended to limit the scope of the present invention unless otherwise specified.

[0028] (Example) A method for manufacturing a gasket according to an embodiment of the present invention and a gasket will be described with reference to Figs. 1 to 5. Fig. 1 is a plan view of a mold according to an embodiment of the present invention, and shows the main components inside the mold in a see-through manner. Figs. 2 and 3 are manufacturing process diagrams of a gasket according to an embodiment of the present invention. The cross-sectional view of the mold in Fig. 2 corresponds to the AA cross-sectional view in Fig. 1, and the cross-sectional views of a molded product such as a gasket in Figs. 2 and 3 correspond to the AA cross-sectional view of the molded product after molding in the mold shown in Fig. 1. Fig. 4 is a plan view of a gasket according to an embodiment of the present invention. Fig. 5 is an explanatory view of a gasket according to an embodiment of the present invention, Fig. 5(a) is a schematic cross-sectional view showing an example of a sealing structure including a gasket according to an embodiment of the present invention, and Fig. 5(b) is a schematic cross-sectional view showing an example of a molded state of a gasket according to an embodiment of the present invention.

[0029] <Gasket manufacturing method> As shown in FIG. 4, the gasket 300 obtained by the manufacturing method according to the present embodiment includes a reinforcing ring 310 as an annular member made of metal or the like, and an elastomer gasket body 320 integrally provided on the inner peripheral surface of the reinforcing ring 310. In the gasket 300 according to the present embodiment, a plurality of recesses 311 recessed toward the outer peripheral surface side are provided at intervals in the circumferential direction on the inner peripheral surface of the reinforcing ring 310. The reinforcing ring 310 also has a plurality of through holes 315 through which the shafts of bolts for fixing the gasket 300 to the cases of various devices or the like are inserted. In addition, the outer peripheral surface of the gasket body 320 has a plurality of protrusions 321 provided to fit into the plurality of recesses 311, respectively. The gasket 300 configured as described above can be obtained by molding the gasket body 320 by insert molding using the reinforcing ring 310 as an insert part. The manufacturing method will be described below.

[0030] First, the basic configuration of the mold 10 used for insert molding will be described. The mold 10 includes a lower mold 100 and an upper mold 200. The mold 10 is configured so that a reinforcing ring 310, which is an insert part, is arranged along the outer circumferential surface of the engraved portion 110 of the lower mold 100. The mold 10 includes a cavity cv for forming the gasket main body 320, an annular burr pool br as an annular space provided on the inner circumferential surface side of the cavity cv, and an annular burr path bd as an annular flow path provided between the cavity cv and the burr pool br. Inside the reinforcing ring 310 arranged in the mold 10, the cavity cv, the burr path bd, and the burr pool br are provided in this order from the outer side to the inner side in the radial direction.

[0031] In addition to the engraved portion 210, the upper mold 200 is provided with a pot 220, which is a material chamber for supplying the molding material E, and a gate 230 for supplying the molding material E in the pot 220 toward the cavity cv. In this embodiment, the tip 231 of the gate 230 is provided so as to open into the cavity cv. More specifically, the tips 231 of the multiple gates 230 are each open at positions corresponding to the multiple recesses 311 provided on the inner peripheral surface of the reinforcing ring 310 (i.e., the positions of the cavities cv1 for forming the multiple protrusions 321 provided on the outer peripheral surface of the gasket main body 320). As a result, the molding material E supplied from the gate 230 is configured to flow from the cavity cv through the burr path bd to the burr pool br. The pot 220 is provided at one point on the upper portion of the upper mold 200. 1, the position of the outer wall surface on the outer periphery side of the annular pot 220 is indicated by a thick dotted line 220O, and the position of the inner wall surface on the inner periphery side is indicated by a thick dotted line 220I. However, the shape of the pot is not limited to this configuration. For example, the planar shape of the pot may be circular, and the pot may have a circular planar shape whose inner wall surface is the thick dotted line 220O in FIG. 1.

[0032] Using the mold 10 configured as above, first, the reinforcing ring 310 is placed in the lower mold 100, and then the mold is closed (see FIG. 2(a)). After the mold is closed, the molding material E is filled into the cavity cv and the like through the multiple gates 230 (see FIG. 2(b)). Then, the mold 10 is opened, and the insert molded product (intermediate product 300A) is taken out from the mold 10 (see FIG. 3(a)). When the mold is opened, the gasket body 320 is separated from the molding material in the gate 230. As a result, the intermediate product 300A is composed of the reinforcing ring 310, the gasket body 320 integrally provided on the inner peripheral surface of the reinforcing ring 310, and the burr 325 integrally provided on the inner peripheral surface of the gasket body 320 via the film 326 molded at the portion of the burr path bd. Then, in this intermediate product 300A, the burr 325 is manually torn off from the molded product (gasket body 320) molded by the cavity cv so that the molded portion (film 326) molded by the burr path bd is torn off (see FIG. 3(b)). Through the above steps, the portion of the intermediate product 300A where the film 326 and the burr 325 are integrated is removed, and the final product, gasket 300, is obtained (see FIG. 3(c)). The gasket 300 shown in FIG. 3(c) corresponds to the cross section taken along line BB in FIG. 4.

[0033] In the gasket 300 obtained by the above manufacturing method, each of the multiple protrusions 321 in the gasket body 320 has a gate mark 322. Also, the inner peripheral surface of the gasket body 320 has a mark 324 where burrs 325 have been removed. Note that, in the gasket 300 according to this embodiment, one bead is provided on each of both sides of the gasket body 320, but in the present invention, the gasket body is not limited to such a configuration.

[0034] The gasket 300 configured as above is, for example, sandwiched between a case body 510 having an opening and a lid 520 closing the opening, and the case body 510 and the lid 520 are fixed together. This makes it possible to seal the gap between the end faces of the case body 510 and the lid 520 (see FIG. 5(a)). According to this gasket 300, the reinforcing ring 310 exerts a spacer function for keeping the distance between the end faces of the case body 510 and the lid 520 constant, a backup ring function for suppressing abnormal deformation of the gasket body 320, and a function for increasing the rigidity of the gasket 300.

[0035] Next, additional configurations for further suppressing the occurrence of molding defects will be described. In this embodiment, all of the additional configurations described below are provided, but depending on the dimensions and shape of the product, the fluidity of the molding material, and the like, the following additional configurations may not be adopted as long as they do not impede moldability.

[0036] In the above mold 10, the tip 231 of the gate 230 may be configured to expand in diameter toward the cavity cv (see, for example, FIG. 2(a)). This makes it easier for a portion of the gasket body 320 that protrudes toward the gate 230 at the portion where the gasket body 320 and the molding material in the gate 230 are separated during demolding to be formed. That is, as shown in FIG. 3, the gate mark 322 formed on the gasket body 320 tends to be configured to protrude. Generally, when the molding part and the molding material in the gate are separated during demolding, a dent is easily formed in the portion of the molding part that is separated from the molding material in the gate, but by employing the above configuration, it is possible to suppress the occurrence of the dent.

[0037] In addition, in the above mold 10, the surface of the cavity cv facing the tip 231 of the gate 230 may have a protruding portion 111 protruding in a direction away from the tip 231 of the gate 230 (see, for example, FIG. 2(a)). This makes it possible to suppress the occurrence of a portion where the thickness of the gasket body 320 is partially thinned even if the portion of the gasket body 320 where the gasket body 320 and the molding material in the gate 230 are separated from each other is recessed during mold release. That is, by adopting the mold 10 configured as above, the surface of the gasket body 320 opposite the portion where the gasket body 320 is separated (i.e., the portion where the gate mark is formed) is provided with a protruding portion 323 protruding in a direction away from the gate mark. This makes it possible to suppress the occurrence of a portion where the thickness of the gasket body 320 is partially thinned even if a recessed gate mark 322X is formed as shown in FIG. 5(b). Therefore, it is possible to suppress the decrease in sealing performance.

[0038] In addition, in the mold 10, a material pool zd for forming a weld line by the material supplied from the adjacent gate 230 may be provided on the inner peripheral side of the flash pool br (see FIG. 1). In FIG. 1, a plurality of material pools zd are provided at intervals in the circumferential direction. As a result, the material supplied from each gate 230 flows from the cavity cv through the flash pool br to the material pool zd. Then, the materials supplied from the adjacent gates 230 join in the material pool zd, so that a weld line is formed in the material pool zd. In FIG. 1, the dotted line wl indicates the position where the weld line is formed. Therefore, the formation of the weld line in the flash 325 is suppressed, and the formation of the weld line in the gasket main body 320 can be more reliably suppressed. Therefore, the deterioration of the sealing performance can be further suppressed.

[0039] Furthermore, in the case of adopting a configuration having a material pool zd, when the material is sent from the burr path bd to the material pool zd, if the difference between the flow rate of the material sent from one gate 230 and the flow rate of the material sent from the other gate 230 in the adjacent gates 230 is large, flow marks may be formed. Such a phenomenon is more likely to occur as the thickness of the burr path bd is thinner. Therefore, it is preferable that the burr path bd is provided with a portion (burr path bd1 surrounded by a dotted line in FIG. 1) that is thicker at a position closer to the material pool zd than at a position farther from the material pool zd. This makes it difficult for a difference in flow rate to occur, and the formation of flow marks in the burr 325 is suppressed, so that the formation of flow marks in the gasket main body 320 can be more reliably suppressed. Therefore, the deterioration of the sealing performance can be further suppressed.

[0040] <Advantages of the manufacturing method of the gasket according to the present embodiment and the gasket> According to this embodiment, the molding material E is supplied directly from the gate 230 to the cavity cv for molding the gasket body 320, and flows through the annular burr path bd to the annular burr pool br provided on the inner peripheral surface side of the cavity cv. Therefore, the formation of air pockets due to insufficient filling of the material in the cavity cv is suppressed. In addition, the formation of flow marks and weld lines that adversely affect the quality of the gasket body 320 can also be suppressed. The gate marks 322 are provided on the protrusions 321 provided respectively so as to fit into the recesses 311 provided on the inner peripheral surface of the reinforcing ring 310, so that they do not adversely affect the sealing performance. In addition, since the molding material E is supplied directly to the cavity cv, the molding pressure can be lowered compared to the conventional technology, and the amount of molding material E can be reduced.

[0041] And even if a material with low fluidity (for example, a rubber material such as HNBR) is used, there is no problem as a product even if the thickness of the burr path bd portion is thinned and insufficient filling of the material occurs in the burr pool br or flow marks or weld lines are formed in the burr 325. Also, the volume of the burr pool bd can be made smaller than the cavity cv. Combined with this, the thickness of the burr path bd can be thinned. Therefore, by thinning the thickness of the burr path bd, the burr 325 can be torn off manually from the molded product (gasket body 320) molded by the cavity cv. By making the thickness of the burr path bd about 0.05 mm, for example, the burr 325 can be torn off manually. This eliminates the need for a process of punching out the burrs using a punch or the like, and does not cause problems that may occur due to punching. Therefore, even when the size of the gasket 300 is large (generally an inner diameter of 100 mm or more), a high-quality gasket 300 can be obtained by adopting the manufacturing method of this embodiment.

[0042] As described above, according to this embodiment, not only can the occurrence of molding defects be suppressed, but also the manufacturing process can be reduced. This can improve the sealing performance of the gasket 300 and reduce manufacturing costs. Furthermore, by appropriately adopting additional configurations as described above, the occurrence of molding defects can be further suppressed and the sealing performance of the gasket 300 can be improved. [Explanation of symbols]

[0043] 10:Mold 100: Lower mold 110: Carved section 111:Protrusion 200: Upper mold 210: Engraved section 220: Pot 230: Gate 231: Tip 300: Gasket 300A: Intermediate product 310: Reinforcement ring 311: Recess 315:Through hole 320: Gasket body 321: Convex 322,322X: Gate Remains 323:Protrusion 324: (burr removal) marks 325: Bali 326: Membrane 510: Case body 520: Lid E: Molding material bd: Bali road br: Bali pool cv: cavity

Claims

1. A method for manufacturing a gasket comprising: an annular member having an inner peripheral surface on which a plurality of recesses recessed toward an outer peripheral surface are provided at intervals in the circumferential direction; and an annular gasket body made of an elastomer, the gasket body having a plurality of protrusions provided so as to fit into the plurality of recesses, respectively, and integrally provided on the inner peripheral surface of the annular member, the method comprising the steps of: a step of clamping the annular member in a state in which the annular member is disposed in the mold using a mold having a cavity for forming the gasket body, an annular space provided on the inner peripheral side of the cavity, an annular flow path provided between the cavity and the annular space, and a plurality of gates provided at positions corresponding to the plurality of recesses; filling the molding material through the plurality of gates; A mold opening step of the mold; A step of removing the insert molded product from the mold; removing the portion formed by the annular space from the molded article formed by the cavity such that the portion formed by the annular passage is separated; A method for producing a gasket, comprising the steps of:

2. In the mold used for molding the gasket body, The method for manufacturing a gasket according to claim 1, wherein a tip of the gate is configured to expand in diameter toward the cavity.

3. In the mold used for molding the gasket body, 3. The method for manufacturing a gasket according to claim 1, wherein the cavity has a protruding portion on a surface thereof facing the tip of the gate, the protruding portion protruding in a direction away from the tip of the gate.

4. In the mold used for molding the gasket body, 3. The method for manufacturing a gasket according to claim 1, further comprising providing a material pool on the inner peripheral surface side of the annular space, the material being supplied from adjacent gates to form a weld line.

5. In the mold used for molding the gasket body, The method for manufacturing a gasket according to claim 4, wherein the annular passage has a portion closer to the pool of material and thicker than a portion farther from the pool of material.

6. an annular member having an inner circumferential surface on which a plurality of recesses are provided at intervals in a circumferential direction, the recesses being recessed toward an outer circumferential surface side; a ring-shaped gasket body made of an elastomer, the gasket body having a plurality of protrusions each provided to fit into the plurality of recesses, and integrally provided on an inner peripheral surface of the ring-shaped member; A gasket comprising: A gasket, characterized in that a gate mark is provided on each of the plurality of protrusions, and a mark where burrs have been removed is provided on the inner peripheral surface of the gasket body.

7. The gasket according to claim 6, wherein each of the plurality of protrusions has a protruding portion protruding in a direction away from the gate mark.

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