Production method for resin molding, injection molding mold, and resin molding

Abstract

To facilitate demolding a resin molding.SOLUTION: The present invention is for producing an arc-like resin molding that has a first surface and a second surface situated on mutually opposite sides along an axial direction, has an inner circumferential surface and an outer circumferential surface between the first and second surfaces, and includes a first end and a second end. In a molding step P2, a resin material is supplied to an interior space of an injection molding mold that includes an inner metallic mold having an inner circumferential molding surface for forming the inner circumferential surface and an outer metallic mold having an outer circumferential molding surface for forming the outer circumferential surface to thereby form an intermediate molding including a resin molding and one or more projections connected to the circumferential surface of the resin molding. In a mold opening step P3, the inner metallic mold is removed. In a demolding step P4, the intermediate molding is demolded from the outer metallic mold by moving the one or more projections.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a resin molded product such as a seal ring or a backup ring. [Background technology]

[0002] A resin molded product such as a seal ring is used to seal the gap between opposing members. For example, Patent Document 1 discloses a seal ring having a joint formed at one location in the circumferential direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-133571 A Summary of the Invention [Problem to be solved by the invention]

[0004] It is important that a resin molded product can be released from a mold without forcibly deforming it (hereinafter referred to as "mold releasability"). However, in order to ensure mold releasability, the positions of the parting surfaces (parting lines) of multiple molds are restricted, and as a result, linear burrs (hereinafter referred to as "linear burrs") corresponding to the parting surfaces of the molds may be formed in areas of the resin molded product that contribute to sealing. In order to ensure sealing performance, it is necessary to remove the linear burrs, for example, by grinding, which increases the manufacturing cost. In consideration of the above circumstances, one aspect of the present disclosure aims to facilitate the release of a resin molded product from a mold. [Means for solving the problem]

[0005] A manufacturing method for a resin molded product according to one embodiment of the present disclosure is a method for manufacturing an arc-shaped resin molded product having a first surface and a second surface located opposite each other along an axial direction, an inner peripheral surface and an outer peripheral surface between the first surface and the second surface, and including a first end and a second end, the method including a molding process for forming an intermediate molded product including the resin molded product and one or more protrusions connected to the inner peripheral surface of the resin molded product by supplying a resin material into an internal space of an injection molding die including an inner mold having an inner peripheral molding surface that forms the inner peripheral surface, and an outer mold having an outer peripheral molding surface that forms the outer peripheral surface, a mold opening process for removing the inner mold, and a demolding process for releasing the intermediate molded product from the outer mold by moving the one or more protrusions.

[0006] An injection molding die according to one embodiment of the present disclosure is an injection molding die used for manufacturing an arc-shaped resin molded product having a first surface and a second surface located opposite each other, and an inner peripheral surface and an outer peripheral surface between the first surface and the second surface, and including a first end and a second end, the injection molding die comprising an inner mold having an inner peripheral molding surface that forms the inner peripheral surface, and an outer mold having an outer peripheral molding surface that forms the outer peripheral surface, a molding groove is formed on the inner peripheral surface of the outer mold along the circumferential direction, the molding groove has a first side surface that forms a first outer region of the first surface and a second side surface that forms a second outer region of the second surface, with the outer peripheral molding surface as a bottom surface, and the inner mold includes a first molding surface that forms a first inner region on the inside of the first outer region of the first surface, and a second molding surface that forms a second inner region on the inside of the second outer region of the second surface.

[0007] A resin molded product according to one embodiment of the present disclosure is an arc-shaped resin molded product including a first surface and a second surface located opposite each other along an axial direction, an inner circumferential surface and an outer circumferential surface between the first surface and the second surface, and a first end surface and a second end surface, wherein a first linear protrusion extending along the circumferential direction is formed between a first outer region of the first surface and a first inner region inside the first outer region, and a second linear protrusion extending along the circumferential direction is formed between a second outer region of the second surface and a second inner region inside the second outer region. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a sealing structure according to a first embodiment. [Diagram 2] FIG. [Diagram 3] 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. [Diagram 5] 5 is a cross-sectional view taken along line VV in FIG. 4. [Figure 6] FIG. 2 is a cross-sectional view of an injection molding die. [Figure 7] FIG. 7 is an enlarged view of region VII in FIG. [Figure 8] FIG. 2 is a plan view of a first mold. [Figure 9] FIG. [Figure 10] FIG. 2 is a plan view of the internal space of an injection molding die. [Figure 11] FIG. 2 is a cross-sectional view of the outer mold. [Figure 12] FIG. 12 is an enlarged view of region XII in FIG. [Figure 13] 4 is a flowchart of a process for manufacturing a seal ring. [Figure 14] 4A to 4C are explanatory views of a mold opening step and a mold releasing step. [Figure 15] FIG. 13 is a schematic diagram of an injection molding die in comparison. [Figure 16] FIG. 13 is an explanatory diagram of a problem in the comparative example. [Figure 17] FIG. 11 is a plan view of the internal space of an injection molding die according to a second embodiment. [Figure 18] 13A to 13C are explanatory views of a mold opening step and a mold releasing step in the second embodiment. [Figure 19] FIG. 13 is a plan view of the internal space of an injection molding die according to a third embodiment. [Figure 20] 13A to 13C are explanatory views of a mold opening step and a mold releasing step in the third embodiment. [Figure 21] FIG. 11 is a cross-sectional view of a sealing structure in a modified example. [Figure 22]FIG. 11 is a cross-sectional view of a sealing structure in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A: First embodiment A-1: Sealed structure 100 Fig. 1 is a cross-sectional view illustrating the configuration of a sealing structure 100 according to a first embodiment. The sealing structure 100 is a mechanism adopted in a transmission such as an automatic transmission (AT) or a continuously variable transmission (CVT). As illustrated in Fig. 1, the sealing structure 100 includes a housing 11, a shaft member 12, and a seal ring 20.

[0010] The housing 11 is a housing in which an axial hole 112 is formed. The axial hole 112 is an opening having a circular cross-sectional shape. The shaft member 12 is a cylindrical structure inserted into the axial hole 112. An annular gap 15 is formed between an inner peripheral surface 113 of the axial hole 112 in the housing 11 and an outer peripheral surface 122 of the shaft member 12. The seal ring 20 is an annular resin molded product that seals the gap 15. The gap 15 is divided into a space 151 and a space 152 by the seal ring 20. The space 151 is maintained at a higher pressure than the space 152. For example, the space 151 is filled with a fluid such as oil, and the space 152 is open to the atmosphere.

[0011] In the following description, a central axis C of the seal ring 20 is assumed. One direction along the central axis C is referred to as the X1 direction, and the direction opposite to the X1 direction is referred to as the X2 direction. The space 152 is located in the X2 direction of the space 151. In the following description, the X1 direction and the X2 direction are collectively referred to as the "axial direction X". The central axis C is also referred to as the central axis of the shaft hole 112 of the housing 11, or the central axis of the shaft member 12. The shaft member 12 is rotatable about the central axis C.

[0012] The direction along the circumference of an imaginary circle of any diameter centered on the central axis C is referred to as the "circumferential direction," and the direction of the radius of the imaginary circle is referred to as the "radial direction." In the radial direction, the direction toward the central axis C is referred to as the "inner side," and the direction away from the central axis C is referred to as the "outer side."

[0013] As illustrated in FIG. 1 , a mounting groove 13 is formed in the outer circumferential surface 122 of the shaft member 12. The mounting groove 13 is a recessed portion that extends in the circumferential direction around the entire circumference of the shaft member 12. The mounting groove 13 includes a side surface 131, a side surface 132, and a bottom surface 133. The side surface 131 and the side surface 132 face each other with a gap therebetween in the axial direction X. The side surface 131 is positioned in the X1 direction relative to the side surface 132. The bottom surface 133 is an arcuate surface that connects the side surface 131 and the side surface 132. The seal ring 20 of the first embodiment is accommodated in the mounting groove 13.

[0014] A-2: Seal ring 20 Fig. 2 is a plan view of the seal ring 20, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. As illustrated in Fig. 2, the seal ring 20 of the first embodiment is a solid seal ring portion including a joint portion 21 and a body portion 22.

[0015] Specifically, the seal ring 20 is an arc-shaped structure including a first end E1 and a second end E2. The first end E1 and the second end E2 overlap each other in the circumferential direction. The first end E1 and the second end E2 form a joint portion 21 located at one point in the circumferential direction. That is, the seal ring 20 of the first embodiment is an arc-shaped member in which a circular member is cut at one point, and the cut portion is the joint portion 21. The first end E1 and the second end E2 are configured to be relatively movable along the circumferential direction. For example, the seal ring 20 is attached to the shaft member 12 with the first end E1 and the second end E2 spaced apart from each other.

[0016] The arc-shaped portion of the seal ring 20 other than the joint portion 21 is the body portion 22. The dimensions and shape of a cross section perpendicular to the circumferential direction of the seal ring 20 are substantially uniform throughout the entire body portion 22 other than each end portion (first end portion E1, second end portion E2).

[0017] The seal ring 20 is formed of various resin materials. For example, the seal ring 20 is formed of a thermoplastic resin such as PEEK (Poly Ether Ether Ketone), PPS (Poly Phenylene Sulfide), or PA (Poly Amide). The seal ring 20 is formed by injection molding of the resin material using an injection molding die 200, which will be described in detail later.

[0018] As illustrated in Fig. 3, the cross-sectional shape of the seal ring 20 of the first embodiment is substantially rectangular. Specifically, the seal ring 20 includes a first surface F1, a second surface F2, an inner peripheral surface Ga, and an outer peripheral surface Gb. The first surface F1 and the second surface F2 are located on opposite sides of each other along the axial direction X. That is, the first surface F1 is an arc-shaped flat surface whose normal line is along the X1 direction, and the second surface F2 is an arc-shaped flat surface whose normal line is along the X2 direction. The inner peripheral surface Ga and the outer peripheral surface Gb are located between the first surface F1 and the second surface F2.

[0019] As described above, the space 151 has a higher pressure than the space 152. Therefore, as illustrated in Fig. 1, the seal ring 20 is pressed in the X2 direction inside the mounting groove 13. The first surface F1 faces the side surface 131 of the mounting groove 13 with a gap therebetween, and the second surface F2 is in close contact with the side surface 132 of the mounting groove 13. The inner circumferential surface Ga faces the bottom surface 133 of the mounting groove 13 with a gap therebetween, and the entire outer circumferential surface Gb is in close contact with the inner circumferential surface 113 of the housing 11.

[0020] As illustrated in FIG. 3, the first surface F1 includes a first inner region F1a and a first outer region F1b. The first inner region F1a is an arc-shaped region of a predetermined width including the inner peripheral edge of the first surface F1. The first outer region F1b is an arc-shaped region of a predetermined width including the outer peripheral edge of the first surface F1. Therefore, the first inner region F1a is located inside the first outer region F1b. FIG. 3 illustrates a boundary B1 between the first outer region F1b and the first inner region F1a. The boundary B1 corresponds to a parting line (PL) of the injection molding die 200 used to mold the seal ring 20.

[0021] The second surface F2 includes a second inner region F2a and a second outer region F2b. The second inner region F2a is an arc-shaped region of a predetermined width including the inner peripheral edge of the second surface F2. The second outer region F2b is an arc-shaped region of a predetermined width including the outer peripheral edge of the second surface F2. Therefore, the second inner region F2a is located inside the second outer region F2b. FIG. 3 illustrates a boundary B2 between the second outer region F2b and the second inner region F2a. The boundary B2 corresponds to the parting line of the injection molding die 200. As illustrated in FIG. 1, a part of the second inner region F2a of the second surface F2 is in close contact with the side surface 132 of the mounting groove 13. The second outer region F2b and the boundary B2 of the second surface F2 do not contact the side surface 132.

[0022] As illustrated in FIG. 3, the inner circumferential surface Ga of the seal ring 20 includes a first portion Ga1 and a second portion Ga2. The first portion Ga1 is a region adjacent to the first surface F1, and the second portion Ga2 is a region adjacent to the second surface F2. Therefore, the first portion Ga1 is located in the X1 direction relative to the second portion Ga2. FIG. 3 illustrates a boundary B12 between the first portion Ga1 and the second portion Ga2. The boundary B12 corresponds to a parting line of the injection molding die 200.

[0023] As illustrated in FIG. 3, the corner A1 between the first surface F1 and the outer circumferential surface Gb is R-shaped. That is, the corner A1 is an arc surface that continuously connects the first surface F1 and the outer circumferential surface Gb. For example, the radius of the corner A1 is about 0.1 mm (R0.1). The corner A1 is a portion corresponding to the intersection of the first surface F1 and the outer circumferential surface Gb. Similarly, the corner A2 between the second surface F2 and the outer circumferential surface Gb is R-shaped. That is, the corner A2 is an arc surface that continuously connects the second surface F2 and the outer circumferential surface Gb. For example, the radius of the corner A2 is about 0.1 mm (R0.1). The corner A2 is a portion corresponding to the intersection of the second surface F2 and the outer circumferential surface Gb.

[0024] A-3: Intermediate molded product 300 Prior to describing the injection molding die 200, we will describe an intermediate molded product (hereinafter referred to as "intermediate molded product 300") molded by the injection molding die 200 in the process of manufacturing the seal ring 20. Fig. 4 is a plan view of the intermediate molded product 300, and Fig. 5 is a cross-sectional view taken along line VV in Fig. 4. The injection molding die 200 is a metal mold for molding the intermediate molded product 300.

[0025] 4 and 5, the intermediate molded product 300 includes an auxiliary molded part 30, a first tab 41, and a second tab 42 in addition to the seal ring 20, which is the final production target. The auxiliary molded part 30, the first tab 41, and the second tab 42 are protrusions connected to the inner circumferential surface Ga of the seal ring 20.

[0026] The auxiliary molding portion 30 is connected to a midpoint between a first end E1 and a second end E2 of the seal ring 20 in the circumferential direction. The auxiliary molding portion 30 includes a columnar portion 31 and a branch portion 32. The columnar portion 31 is a cylindrical portion centered on a central axis C. The branch portion 32 is a portion that protrudes linearly in the radial direction from the outer circumferential surface of the columnar portion 31. A tip portion (gate) of the branch portion 32 is continuous with the inner circumferential surface Ga of the seal ring 20.

[0027] The first tab 41 and the second tab 42 are provided at different positions of the seal ring 20 in the circumferential direction. The first tab 41 is provided between the first end E1 and the auxiliary molding portion 30. Specifically, the first tab 41 is connected to the seal ring 20 in the vicinity of the first end E1. Furthermore, the second tab 42 is provided between the second end E2 and the auxiliary molding portion 30. Specifically, the second tab 42 is provided between the second end E2 and the auxiliary molding portion 30.

[0028] Each of the first tab 41 and the second tab 42 includes a gripping portion 44 and a connecting portion 45. The gripping portion 44 is a cylindrical portion extending along the axial direction X. The connecting portion 45 is a portion that connects the seal ring 20 and the gripping portion 44.

[0029] 5, the dimension H1 (height) of the gripping portion 44 in the axial direction X is greater than the dimension T (thickness) of the seal ring 20 in the axial direction X (H1>T). The end 441 in the X1 direction of the gripping portion 44 is located further in the X1 direction than the first surface F1 of the seal ring 20. Also, the end 442 in the X2 direction of the gripping portion 44 is located further in the X2 direction than the second surface F2 of the seal ring 20. Also, the dimension H2 of the connecting portion 45 in the axial direction X is less than the dimension T of the seal ring 20 in the axial direction X (H2 <T)。

[0030] A-4: Injection mold 200 6 is a cross-sectional view of the injection molding die 200. In the following description, the central axis C of the seal ring 20 will also be used to describe the injection molding die 200.

[0031] As illustrated in FIG. 6, the injection molding die 200 of the first embodiment includes an inner die 50 and an outer die 60. The inner die 50 is a cylindrical or disc-shaped movable die. The outer die 60 is an annular fixed die surrounding the inner die 50. An outer peripheral surface 51 of the inner die 50 and an inner peripheral surface 61 of the outer die 60 are in close contact with each other. An arc-shaped molding space S for forming the seal ring 20 is formed between the inner die 50 and the outer die 60. FIG. 7 is an enlarged view of region VII in FIG. 6.

[0032] A-4-1: Inner mold 50 The inner mold 50 includes a first mold 70 and a second mold 80 which are configured as separate bodies. Each of the first mold 70 and the second mold 80 is a cylindrical or disk-shaped structure. The first mold 70 and the second mold 80 are fixed in a state of facing each other. Specifically, the first mold 70 and the second mold 80 are arranged so that a surface of the first mold 70 facing the second mold 80 (hereinafter referred to as a "first opposing surface 71") and a surface of the second mold 80 facing the first mold 70 (hereinafter referred to as a "second opposing surface 81") are in close contact with each other.

[0033] Fig. 8 is a plan view of the first opposing surface 71 of the first mold 70. For convenience, the first opposing surface 71 is shaded in Fig. 8. As illustrated in Fig. 8, a molding flow path 72, a flow path 73, a molding hole 74a, and a molding hole 74b are formed in the first opposing surface 71 of the first mold 70.

[0034] The molding flow path 72 is a space for molding the seal ring 20. Specifically, the molding flow path 72 is formed in an arc shape from end e11 to end e12 along the outer circumferential edge of the first opposing surface 71. The end e11 is an end corresponding to the first end E1 of the seal ring 20, and the end e12 is an end corresponding to the second end E2 of the seal ring 20.

[0035] 7 and 8, the molding flow path 72 is a groove space defined by a first molding surface 721 and a first inner circumferential surface 722 that intersect with each other. The first molding surface 721 is an arc-shaped region in a plane perpendicular to the central axis C, and corresponds to the bottom surface of the molding flow path 72. The first inner circumferential surface 722 is an arc-shaped surface centered on the central axis C, and corresponds to the side surface of the molding flow path 72. As described above, the first mold 70 includes the first molding surface 721 and the first inner circumferential surface 722.

[0036] 8 is a space for forming a portion of the columnar portion 31 of the auxiliary molding part 30 located in the X1 direction. Specifically, the flow path 73 is a through hole having a circular cross-sectional shape, and is located at the center of the first opposing surface 71.

[0037] Molding hole 74a is a bottomed hole for molding a portion of gripping portion 44 of first tab 41 including end 441, and is formed near end e11. Molding hole 74b is a bottomed hole for molding a portion of gripping portion 44 of second tab 42 including end 441, and is formed near end e12. Molding hole 74a and molding hole 74b are examples of a "first molding hole".

[0038] Fig. 9 is a plan view of the second opposing surface 81 of the second mold 80. For convenience, the second opposing surface 81 is shaded in Fig. 9. As illustrated in Fig. 9, the second opposing surface 81 of the second mold 80 is formed with a molding flow path 82, a flow path 831, a flow path 832, a molding hole 84a, a molding hole 84b, a communication path 85a, and a communication path 85b.

[0039] The molding flow path 82 is a space for molding the seal ring 20. Specifically, the molding flow path 82 is formed in an arc shape from end e21 to end e22 along the outer circumferential edge of the second opposing surface 81. The end e21 is an end corresponding to the first end E1 of the seal ring 20, and the end e22 is an end corresponding to the second end E2 of the seal ring 20.

[0040] 7 and 9, the molding flow path 82 is a groove space defined by a second molding surface 821 and a second inner circumferential surface 822 that intersect with each other. The second molding surface 821 is an arc-shaped region in a plane perpendicular to the central axis C, and corresponds to the bottom surface of the molding flow path 82. The second inner circumferential surface 822 is an arc-shaped surface centered on the central axis C, and corresponds to the side surface of the molding flow path 82. As described above, the second mold 80 includes the second molding surface 821 and the second inner circumferential surface 822.

[0041] The flow path 831 is a space for forming a portion of the columnar portion 31 of the auxiliary molding part 30 located in the X2 direction. Specifically, the flow path 831 is a through hole having a circular cross section, and is located at the center of the second opposing surface 81. The flow path 832 is a space for forming the branched portion 32 of the auxiliary molding part 30. The flow path 832 extends in the radial direction from the flow path 831, thereby connecting the flow path 831 and the molding flow path 82. The portion of the flow path 832 near the molding flow path 82 is a gate that is narrowed compared to other portions of the flow path 831.

[0042] The molding hole 84a is a bottomed hole for molding a portion of the gripping portion 44 of the first tab 41, including the end 442. The communication passage 85a is a passage that communicates the molding hole 84a with the molding passage 82. The molding hole 84a and the communication passage 85a are formed near the end e21. On the other hand, the molding hole 84b is a bottomed hole for molding a portion of the gripping portion 44 of the second tab 42, including the end 442. The communication passage 85b is a passage that communicates the molding hole 84b with the molding passage 82. The molding hole 84b and the communication passage 85b are formed near the end e22. The molding hole 84a and the molding hole 84b are examples of a "second molding hole".

[0043] 7, when the first opposing surface 71 and the second opposing surface 81 are in contact with each other, the first inner circumferential surface 722 of the first mold 70 and the second inner circumferential surface 822 of the second mold 80 are continuous without any steps to form the inner circumferential molding surface 55. The inner circumferential molding surface 55 is an inner wall surface for forming the inner circumferential surface Ga of the seal ring 20 in the molding space S. As illustrated above, the inner mold 50 of the first embodiment has the inner circumferential molding surface 55 that forms the inner circumferential surface Ga of the seal ring 20.

[0044] Specifically, the first inner circumferential surface 722 is a molding surface for forming a first portion Ga1 of the inner circumferential surface Ga of the seal ring 20. The second inner circumferential surface 822 is a molding surface for forming a second portion Ga2 of the inner circumferential surface Ga of the seal ring 20. That is, the region of the inner circumferential surface Ga formed by the first inner circumferential surface 722 is the first portion Ga1, and the region of the inner circumferential surface Ga formed by the second inner circumferential surface 822 is the second portion Ga2.

[0045] As illustrated in Fig. 7, the boundary between the first inner circumferential surface 722 and the second inner circumferential surface 822 is located between the first surface F1 and the second surface F2 of the seal ring 20 in the axial direction X. That is, as illustrated in Fig. 3, the linear burr L12 formed between the first portion Ga1 and the second portion Ga2 of the inner circumferential surface Ga due to the boundary B12 between the first inner circumferential surface 722 and the second inner circumferential surface 822 is located between the first surface F1 and the second surface F2. That is, according to the first embodiment, it is possible to prevent the linear burr L12 corresponding to the boundary between the first mold 70 and the second mold 80 from being formed along the edge of the inner circumferential surface Ga of the seal ring 20 on the first surface F1 side or the edge of the second surface F2 side.

[0046] The flow path 73 of the first mold 70 and the flow paths 831 and 832 of the second mold 80 communicate with each other to form the supply flow path 52 in Fig. 6. The supply flow path 52 is a flow path for supplying the resin material to the molding space S. The resin material remaining in the supply flow path 52 forms the auxiliary molding portion 30 described above.

[0047] The molding hole 74a of the first mold 70 and the molding hole 84a of the second mold 80 communicate with each other to form a first space 531. The first space 531 is a space for forming the gripping portion 44 of the first tab 41. The first space 531 communicates with the molding space S via a communication path 85a. The communication path 85a is a space for forming the connecting portion 45 of the first tab 41. The communication path 85a may be formed in the first mold 70.

[0048] The molding hole 74b of the first mold 70 and the molding hole 84b of the second mold 80 communicate with each other to form a second space 532. The second space 532 is a space for forming the gripping portion 44 of the second tab 42. The second space 532 communicates with the molding space S via a communication path 85b. The communication path 85b is a space for forming the connecting portion 45 of the second tab 42. The communication path 85b may be formed in the first mold 70.

[0049] As described above, in the first embodiment, spaces (molding holes 74a and 84a) for forming the grip portion 44 of the first tab 41 are formed in both the first mold 70 and the second mold 80. Similarly, spaces (molding holes 74b and 84b) for forming the grip portion 44 of the second tab 42 are formed in both the first mold 70 and the second mold 80. Therefore, it is possible to form the first tab 41 and the second tab 42 that are easy to grip and have a sufficiently ensured dimension H1 of the grip portion 44 in the axial direction X.

[0050] Fig. 10 is a plan view illustrating the positional relationship between the supply flow path 52, the first space 531, the second space 532, and the molding space S. As illustrated in Fig. 10, the end e1 and the end e2 of the molding space S are spaced apart from each other in the circumferential direction. The end e1 is one end (ends e11 and e21) of the molding space S that corresponds to the first end E1 of the seal ring 20, and the end e2 is the other end (ends e12 and e22) of the molding space S that corresponds to the second end E2 of the seal ring 20.

[0051] 10, the supply passage 52 communicates with a point Q in the molding space S, which corresponds to one location in the circumferential direction of the seal ring 20. Specifically, the point Q is a midpoint between the end e1 and the end e2 in the circumferential direction of the molding space S. The point Q is an example of a "specific point."

[0052] The first space 531 communicates between a point Q in the molding space S where the supply passage 52 communicates and the end e1. Specifically, the first space 531 communicates with the vicinity of the end e1 of the molding space S. On the other hand, the second space 532 communicates between a point Q in the molding space S where the supply passage 52 communicates and the end e2. Specifically, the second space 532 communicates with the vicinity of the end e2 of the molding space S.

[0053] As described above, the internal space of the injection molding die 200 includes the molding space S, the supply flow path 52, the first space 531, and the second space 532. In the first embodiment, the first space 531 and the second space 532 are disposed on both circumferential sides of the point Q at which the supply flow path 52 communicates in the molding space S. Therefore, as shown by the dashed arrows in Fig. 10, the resin material supplied from the supply flow path 52 can be effectively filled into both ends (ends e1 and e2) of the molding space S, the first space 531, and the second space 532.

[0054] A-4-2: Outer mold 60 Fig. 11 is a cross-sectional view of the outer mold 60. Fig. 12 is an enlarged view of region XII in Fig. 11. As illustrated in Figs. 11 and 12, a molding groove 62 is formed in the inner peripheral surface 61 of the outer mold 60 along the circumferential direction. The molding groove 62 is a bottomed groove having a rectangular cross-sectional shape. Specifically, the molding groove 62 is defined by a first side surface 631, a second side surface 632, and an outer peripheral molding surface 64, as illustrated in Fig. 12.

[0055] The outer peripheral molding surface 64 constitutes the bottom surface of the molding groove 62. The outer peripheral molding surface 64 is an arc-shaped inner wall surface for forming the outer peripheral surface Gb of the seal ring 20 in the molding space S. That is, as illustrated in Fig. 7, in a state in which the inner mold 50 and the outer mold 60 are fixed to each other (hereinafter referred to as the "mold fixed state"), the inner peripheral molding surface 55 of the inner mold 50 and the outer peripheral molding surface 64 of the outer mold 60 face each other with a gap corresponding to the molding space S.

[0056] 12, the first side surface 631 and the second side surface 632 are wall surfaces that intersect with the outer peripheral molding surface 64. The first side surface 631 and the second side surface 632 are arc-shaped surfaces in a plane perpendicular to the central axis C, and face each other with a predetermined gap between them. The first side surface 631 is located in the X1 direction with respect to the second side surface 632.

[0057] As illustrated in FIG. 7, in the mold fixed state, the first side surface 631 of the outer mold 60 and the first molding surface 721 of the inner mold 50 (first mold 70) are located in the same plane. That is, the first side surface 631 and the first molding surface 721 are continuous without any step. The first side surface 631 and the first molding surface 721 are planes for forming the first surface F1 of the seal ring 20. Specifically, the first molding surface 721 is an inner wall surface for forming the first inner region F1a of the first surface F1, and the first side surface 631 is an inner wall surface for forming the first outer region F1b of the first surface F1. That is, the region of the first surface F1 formed by the first molding surface 721 is the first inner region F1a, and the region of the first surface F1 formed by the first side surface 631 is the first outer region F1b.

[0058] In addition, in the mold fixed state, the second side surface 632 of the outer mold 60 and the second molding surface 821 of the inner mold 50 (second mold 80) are located in the same plane. That is, the second side surface 632 and the second molding surface 821 are continuous without any step. The second side surface 632 and the second molding surface 821 are planes for forming the second surface F2 of the seal ring 20. Specifically, the second molding surface 821 is an inner wall surface for forming the second inner region F2a of the second surface F2, and the second side surface 632 is an inner wall surface for forming the second outer region F2b of the second surface F2. That is, the region of the second surface F2 formed by the second molding surface 821 is the second inner region F2a, and the region of the second surface F2 formed by the second side surface 632 is the second outer region F2b.

[0059] As can be understood from the above explanation, molding space S is an arc-shaped space surrounded by inner molding surface 55, first molding surface 721, second molding surface 821, outer molding surface 64, first side surface 631, and second side surface 632.

[0060] In the first embodiment, the boundary B1 between the first molding surface 721 of the inner mold 50 and the first side surface 631 of the outer mold 60 faces the first surface F1 of the seal ring 20, and the boundary B2 between the second molding surface 821 of the inner mold 50 and the second side surface 632 of the outer mold 60 faces the second surface F2 of the seal ring 20. That is, the boundary (B1, B2) between the outer mold 60 and the inner mold 50 does not face the outer peripheral surface Gb of the seal ring 20. With the above configuration, it is possible to prevent linear burrs corresponding to the boundary between the inner mold 50 and the outer mold 60 from being formed on the outer peripheral surface Gb of the seal ring 20. Therefore, it is possible to maintain a high level of sealing performance of the outer peripheral surface Gb of the seal ring 20 without requiring a process of removing linear burrs by polishing the outer peripheral surface Gb of the seal ring 20.

[0061] The boundary B1 between the first side surface 631 and the first molding surface 721 faces the first surface F1 of the seal ring 20. Therefore, as illustrated in Fig. 3, a linear burr L1 is formed along the circumferential direction between the first inner region F1a and the first outer region F1b of the first surface F1. Similarly, the boundary between the second side surface 632 and the second molding surface 821 faces the second surface F2 of the seal ring 20. Therefore, a linear burr L2 is formed along the circumferential direction between the second inner region F2a and the second outer region F2b of the second surface F2.

[0062] As can be understood from the above description, the presence of linear burrs L1 on the first surface F1 of the seal ring 20 and linear burrs L2 on the second surface F2 means that the boundary (B1, B2) between the inner mold 50 and the outer mold 60 faces the first surface F1 and the second surface F2. According to the above configuration, as described above, the boundary between the inner mold 50 and the outer mold 60 does not face the outer peripheral surface Gb of the seal ring 20. Therefore, the sealing performance of the outer peripheral surface Gb of the seal ring 20 can be maintained at a high level without the need for a process of removing the linear burrs by polishing the outer peripheral surface Gb or the like. The linear burrs L1 are an example of a "first protrusion," and the linear burrs L2 are an example of a "second protrusion."

[0063] As illustrated in FIG. 12, the corner a1 between the first side surface 631 and the outer peripheral molding surface 64 in the outer mold 60 is rounded. That is, the corner a1 is an arc surface that continuously connects the first side surface 631 and the outer peripheral molding surface 64. For example, the radius of the corner a1 is about 0.1 mm (R0.1). Therefore, as described above with reference to FIG. 3, the corner A1 between the first surface F1 and the outer peripheral surface Gb in the seal ring 20 is rounded. The corner a1 is an example of a "first corner."

[0064] Similarly, in the outer mold 60, the corner a2 between the second side surface 632 and the outer peripheral molding surface 64 is rounded. That is, the corner a2 is an arc surface that continuously connects the second side surface 632 and the outer peripheral molding surface 64. For example, the radius of the corner a2 is about 0.1 mm (R0.1). Therefore, as described above with reference to FIG. 3, the corner A2 between the second surface F2 and the outer peripheral surface Gb in the seal ring 20 is rounded. The corner a2 is an example of a "second corner."

[0065] As described above, in the first embodiment, the corners a1 and a2 of the outer mold 60 are rounded. Therefore, the corners A1 and A2 of the seal ring 20 can be rounded without requiring polishing or other operations.

[0066] A-5: Manufacturing method of seal ring 20 13 is a flowchart of the steps for manufacturing the seal ring 20. First, in a preparation step P1, the injection molding die 200 is prepared. As described above, the injection molding die 200 includes the inner die 50 (the first die 70 and the second die 80) and the outer die 60. The injection molding die 200 is configured in a die fixed state.

[0067] In the molding step P2 after the preparation step P1, the intermediate molded product 300 shown in Fig. 4 is formed by injection molding using the injection mold 200. Specifically, a liquid resin material is supplied to the internal space of the injection mold 200, and the intermediate molded product 300 is formed by hardening the resin material. As described above, the intermediate molded product 300 includes the auxiliary molding portion 30, the first tab 41, and the second tab 42 in addition to the seal ring 20, which is the final manufacturing target. At the stage where the molding step P2 is performed, the first end E1 and the second end E2 of the seal ring 20 are spaced apart from each other in the circumferential direction.

[0068] As shown by the arrows in FIG. 10, the resin material supplied to the supply flow path 52 flows into the molding space S from the point Q and branches into a first component N1 toward the end e1 of the molding space S and a second component N2 toward the end e2. A part of the first component N1 reaches the end e1, and the other component flows into the first space 531 from the communication path 85a. Air bubbles in the molding space S advance into the first space 531 due to the flow of the resin material. Therefore, the air bubbles do not reach the end e1. Similarly, a part of the second component N2 reaches the end e2, and the other component flows into the second space 532 from the communication path 85b. Air bubbles in the molding space S advance into the second space 532 due to the flow of the resin material. Therefore, the air bubbles do not reach the end e2.

[0069] As can be understood from the above description, the first space 531 and the second space 532 function as spaces for accommodating air bubbles in the molding space S, thereby making it possible for the resin material to reach the entire molding space S. In other words, the first space 531 and the second space 532 are spaces for ensuring the filling of the resin material in the molding space S. As a result of ensuring the filling of the resin material, it is possible to form a seal ring 20 that is free from defects such as defects caused by air bubbles.

[0070] In the mold-opening step P3 after the molding step P2 in Fig. 13 is performed, the inner mold 50 is removed. Specifically, the first mold 70 and the second mold 80 are sequentially removed from the outer mold 60. When the mold-opening step P3 is performed, the outer peripheral surface Gb, the first outer region F1b, and the second outer region F2b of the seal ring 20 of the intermediate molded product 300 are fixed to the outer mold 60, as illustrated in Fig. 14. In the above state, the auxiliary molding portion 30, the first tab 41, and the second tab 42 protrude from the inner peripheral surface Ga of the seal ring 20.

[0071] In the demolding step P4 after the mold opening step P3, the intermediate molded product 300 is demolded from the outer mold 60. In the demolding step P4, the first tab 41 and the second tab 42 are moved to demold the intermediate molded product 300 from the outer mold 60. For example, the gripping portions 44 of the first tab 41 and the second tab 42 are gripped by a gripping mechanism such as a jig, and the first tab 41 and the second tab 42 are moved by displacing the gripping mechanism. Specifically, the gripping mechanism moves the first tab 41 and the second tab 42 in a plane perpendicular to the axial direction X. For example, the gripping mechanism moves the first tab 41 and the second tab 42 closer to each other in the circumferential direction, as illustrated by the dashed arrow in FIG. 14. That is, the first tab 41 and the second tab 42 are operated so that the diameter of the seal ring 20 is reduced. As the first tab 41 and the second tab 42 approach each other, the seal ring 20 gradually peels off from the outer mold 60 from each of the first end E1 and the second end E2 toward point Q, and is eventually completely released from the outer mold 60.

[0072] As described above, in the first embodiment, the intermediate molded product 300 is released from the outer mold 60 by moving the first tab 41 and the second tab 42 molded together with the seal ring 20. Therefore, the intermediate molded product 300 can be easily released from the outer mold 60. Specifically, the intermediate molded product 300 can be released from the outer mold 60 by a simple process of bringing the first tab 41 and the second tab 42 close to each other. In the first embodiment, the first tab 41 is formed in the vicinity of the first end E1, and the second tab 42 is formed in the vicinity of the second end E2. Therefore, compared with a form in which the first tab 41 is formed at a position sufficiently separated from the first end E1 or a form in which the second tab 42 is formed at a position sufficiently separated from the second end E2, the effect of easily releasing the intermediate molded product 300 from the outer mold 60 is particularly remarkable.

[0073] 13, in a removal step P5 after the demolding step P4 is performed, the auxiliary molding part 30, the first tab 41, and the second tab 42 are removed from the intermediate molded product 300. For example, the auxiliary molding part 30, the first tab 41, and the second tab 42 are cut out from the inner circumferential surface Ga by a cutting mechanism such as a cutter. The cut-out portion of the inner circumferential surface Ga may be polished.

[0074] Immediately after the removal step P5, the first end E1 and the second end E2 of the seal ring 20 are spaced apart from each other in the circumferential direction. In the deformation step P6 after the removal step P5, a forming process is performed on the seal ring 20. Specifically, the seal ring 20 is deformed by the forming process so that the first end E1 and the second end E2 overlap each other in the circumferential direction. The seal ring 20 is completed by the above steps.

[0075] Meanwhile, if only consideration is given to facilitating release from the injection molding die 200, a configuration in which the outer die 60 and the inner die 50 are shaped as shown in FIG. 15 (hereinafter referred to as the "comparative embodiment") is also possible. In the comparative embodiment, the upper surface of the outer die 60 and the lower surface of the first die 70 come into contact with each other at the boundary B1 to form the molding space S. In the comparative embodiment, the first die 70 is removed after the resin material filled in the molding space S has hardened. With the first die 70 removed, the seal ring 20 can be easily released from the outer die 60 by moving it upward.

[0076] 16, a linear burr L1 corresponding to the boundary B1 between the outer mold 60 and the first mold 70 inevitably occurs along the edge of the outer peripheral surface Gb of the seal ring 20 on the first surface F1 side. The linear burr L1 protrudes outward from the outer peripheral surface Gb.

[0077] 1, the outer peripheral surface Gb is in close contact with the inner peripheral surface 113 of the housing 11. If the outer peripheral surface Gb has irregularities, the close contact with the inner peripheral surface 113 of the housing 11 decreases. That is, in order to maintain a high level of sealing performance of the seal ring 20, a high degree of flatness is required for the outer peripheral surface Gb. Therefore, in the comparative example, a flattening process such as polishing is essential to remove the linear burrs L1 on the outer peripheral surface Gb.

[0078] In contrast to the comparative example, in the first embodiment, the boundary (B1, B2) between the inner mold 50 and the outer mold 60 faces the first face F1 and the second face F2 of the seal ring 20, so that linear burrs L1 are not formed on the outer peripheral surface Gb. Therefore, the flattening step, which is essential in the comparative example, is not necessary in the first embodiment. Since the flattening step is omitted as described above, according to the first embodiment, the manufacturing cost of the seal ring 20 can be reduced compared to the comparative example.

[0079] On the other hand, in the first embodiment, after the mold opening step P3 is performed, the seal ring 20 is held between the first side surface 631 and the second side surface 632 of the outer mold 60. Therefore, the seal ring 20 may not be released from the outer mold 60 only by moving in the axial direction X. In consideration of the above circumstances, the first embodiment employs a step (mold releasing step P4) in which the first tab 41 and the second tab 42 are moved to release the intermediate molded product 300 from the outer mold 60. According to the above method, even though the seal ring 20 is held between the first side surface 631 and the second side surface 632 of the outer mold 60, the intermediate molded product 300 can be easily released from the outer mold 60. As can be understood from the above description, according to the first embodiment, it is possible to achieve both a reduction in manufacturing cost for ensuring the adhesion of the outer peripheral surface Gb and ease of release of the intermediate molded product 300. Note that a form in which a flattening step is performed on the outer peripheral surface Gb is not excluded from the scope of the present disclosure.

[0080] In addition, the first tab 41 and the second tab 42 used for releasing the intermediate molded product 300 are formed by the first space 531 and the second space 532 for ensuring the filling of the resin material in the molding space S. That is, the first tab 41 and the second tab 42 are used for both ensuring the filling of the resin material and ensuring the releasability of the intermediate molded product 300. Therefore, there is an advantage that the manufacturing process of the seal ring 20 can be simplified compared to a form in which the filling of the resin material and the releasability of the intermediate molded product 300 are achieved by separate elements.

[0081] B: Second embodiment A second embodiment of the present disclosure will be described. Note that, for elements having the same functions as those in the first embodiment in each of the following exemplary aspects, the same reference numerals as those in the first embodiment will be used, and detailed descriptions of each will be omitted as appropriate.

[0082] Fig. 17 is an explanatory diagram of the internal space of the injection molding die 200 in the second embodiment. As illustrated in Fig. 17, the injection molding die 200 of the second embodiment includes a supply flow path 52 and a first space 531 in addition to the molding space S. As in the first embodiment, the supply flow path 52 is a space for forming the auxiliary molding portion 30, and the first space 531 is a space for forming the first tab 41. The injection molding die 200 of the second embodiment does not include the second space 532 of the first embodiment.

[0083] The supply flow passage 52 in the second embodiment communicates with the molding space S in the vicinity of the end e2. On the other hand, the first space 531 communicates with the molding space S in the vicinity of the end e1. Therefore, of the resin material supplied from the supply flow passage 52 to the molding space S, the first component N1 reaches the end e2, and the second component N2 flows in an arc shape in the molding space S and reaches the end e1. Also, a part of the second component N2 flows into the first space 531.

[0084] 18 is a plan view illustrating the state of the intermediate molded product 300 immediately after the mold opening step P3. When the mold opening step P3 is performed, the outer peripheral surface Gb, the first outer region F1b, and the second outer region F2b of the seal ring 20 of the intermediate molded product 300 are fixed to the outer mold 60, as in the first embodiment. In the second embodiment, the auxiliary molding part 30 and the first tab 41 protrude from the inner peripheral surface Ga of the seal ring 20. The auxiliary molding part 30 is connected to the vicinity of the second end E2, and the first tab 41 is connected to the vicinity of the first end E1.

[0085] In the demolding step P4 of the second embodiment, the intermediate molded product 300 is demolded from the outer mold 60 by moving the first tab 41 and the auxiliary molding part 30. For example, the gripping mechanism moves the first tab 41 and the auxiliary molding part 30 closer to each other in the circumferential direction, as illustrated by the dashed arrow in Fig. 18. As the first tab 41 and the auxiliary molding part 30 move closer to each other, the seal ring 20 is gradually peeled off from the outer mold 60 from each of the first end E1 and the second end E2, and is finally completely demolded from the outer mold 60.

[0086] The second embodiment achieves the same effects as the first embodiment. In the second embodiment, the second tab 42 of the first embodiment is omitted, so there is no need to remove the second tab 42 in the removal step P5. Therefore, the removal step P5 can be simplified compared to the first embodiment.

[0087] C: Third embodiment 19 is an explanatory diagram of the internal space of the injection molding die 200 in the third embodiment. As illustrated in FIG. 19, the injection molding die 200 in the third embodiment includes a first supply flow path 521, a second supply flow path 522, and a first space 531 in addition to the molding space S. The first supply flow path 521 and the second supply flow path 522 are flow paths for supplying the resin material to the molding space S in the molding process P2. The first supply flow path 521 communicates with the vicinity of the end e1 of the molding space S, and the second supply flow path 522 communicates with the vicinity of the end e2 of the molding space S. On the other hand, the first space 531 is a space for forming the first tab 41, and communicates with the midpoint between the end e1 and the end e2 in the circumferential direction of the molding space S.

[0088] In the molding process P2, a part of the resin material supplied from the first supply flow path 521 to the molding space S reaches the end e1, and the other part flows in an arc shape toward the first space 531. Similarly, a part of the resin material supplied from the second supply flow path 522 to the molding space S reaches the end e2, and the other part flows in an arc shape toward the first space 531. The resin materials supplied from the first supply flow path 521 and the second supply flow path 522 join together and flow into the first space 531.

[0089] 20 is a plan view illustrating a state of the intermediate molded product 300 immediately after the mold-opening step P3. When the mold-opening step P3 is performed, the outer peripheral surface Gb, the first outer region F1b, and the second outer region F2b of the seal ring 20 of the intermediate molded product 300 are fixed to the outer mold 60, as in the first embodiment. In the third embodiment, the first auxiliary molded portion 301, the second auxiliary molded portion 302, and the first tab 41 protrude from the inner peripheral surface Ga of the seal ring 20.

[0090] The first auxiliary molding portion 301 is a portion molded by the first supply flow path 521, and is connected to the vicinity of the first end E1 of the seal ring 20. The second auxiliary molding portion 302 is a portion molded by the second supply flow path 522, and is connected to the vicinity of the second end E2 of the seal ring 20.

[0091] In the demolding step P4 of the third embodiment, the intermediate molded product 300 is demolded from the outer mold 60 by moving the first auxiliary molding part 301 and the second auxiliary molding part 302. For example, the gripping mechanism moves the first auxiliary molding part 301 and the second auxiliary molding part 302 closer to each other in the circumferential direction, as illustrated by the dashed arrow in Fig. 20. As the first auxiliary molding part 301 and the second auxiliary molding part 302 approach each other, the seal ring 20 is gradually peeled off from the outer mold 60 from each of the first end part E1 and the second end part E2, and is finally completely demolded from the outer mold 60.

[0092] The third embodiment also achieves the same effects as the first embodiment. In the third embodiment, the resin material can be efficiently supplied to the molding space S by the two systems of the first supply flow path 521 and the second supply flow path 522.

[0093] As can be understood from the examples of the first to third embodiments, in the demolding process P4, the intermediate molded product 300 is demolded from the outer mold 60 by moving the protrusions connected to the inner circumferential surface Ga of the seal ring 20. The first tab 41 and the second tab 42 in the first embodiment, the first tab 41 and the auxiliary molding portion 30 in the second embodiment (FIG. 18), and the first auxiliary molding portion 301 and the second auxiliary molding portion 302 in the third embodiment (FIG. 20) are examples of the "protrusions".

[0094] Specifically, one of the first tab 41 and the second tab 42 in the first embodiment is an example of a "first protrusion", and the other is an example of a "second protrusion". One of the first tab 41 and the auxiliary molding portion 30 in the second embodiment is an example of a "first protrusion", and the other is an example of a "second protrusion". One of the first auxiliary molding portions 301 in the third embodiment is an example of a "first protrusion", and the other is an example of a "second protrusion".

[0095] D: Variation Specific modified embodiments added to each of the above-mentioned embodiments are exemplified below. Two or more embodiments selected from the following examples may be appropriately combined as long as they are not mutually contradictory.

[0096] (1) In each of the above-described embodiments, the intermediate molded product 300 is released from the outer mold 60 by the movement of two protrusions in the demolding step P4, but the number of protrusions that move in the demolding step P4 is not limited to the above examples. The intermediate molded product 300 may be released by the movement of one protrusion in the demolding step P4.

[0097] For example, in the first embodiment, only one of the first tab 41 and the second tab 42 may be moved. In the second embodiment, only one of the first tab 41 and the auxiliary molding portion 30 may be moved. In the third embodiment, only one of the first auxiliary molding portion 301 and the second auxiliary molding portion 302 may be moved. Also, the intermediate molded product 300 may be released from the outer mold 60 by moving three or more protrusions.

[0098] (2) In each of the above-described embodiments, the seal ring 20 is exemplified, but the resin molded product to which the present disclosure is applicable is not limited to the seal ring 20. For example, the present disclosure is also applicable to a backup ring that is arranged next to an annular seal to prevent the seal from wedging into a gap, as in the above-described embodiments. The backup ring is an arc-shaped member formed by cutting an annular member at one location. Thus, the backup ring is an arc-shaped resin molded product including a first end and a second end, as in the seal ring 20 in each of the above-described embodiments.

[0099] (3) In each of the above-described embodiments, both corners A1 and A2 of seal ring 20 are rounded, but embodiments in which only one of corners A1 and A2 is rounded are also envisioned. Therefore, only one of corners a1 and a2 of outer mold 60 may be rounded. Also, the rounded shape of corners A1 or A2 may be omitted. The rounded shape of corners a1 or a2 may be omitted.

[0100] (4) In each of the above-described embodiments, the cross-sectional shape of the seal ring 20 is substantially rectangular, but the cross-sectional shape of the seal ring 20 is not limited to the above examples. For example, the embodiment 1 illustrated in Fig. 21 or the embodiment 2 illustrated in Fig. 22 may also be envisioned.

[0101] [Aspect 1] 21, the seal ring 20 of the embodiment 1 is formed with a step portion 23 and a step portion 24. The step portion 23 is a recess formed in an arc shape along the inner circumferential edge of the first surface F1. The step portion 24 is a recess formed in an arc shape along the inner circumferential edge of the second surface F2. That is, the cross-sectional shape of the seal ring 20 in the embodiment 1 is T-shaped.

[0102] A linear burr L1 is formed on the first surface F1 in an area other than the step portion 23, and a linear burr L2 is formed on the second surface F2 in an area other than the step portion 24. In the first aspect, the area (sliding area) of the second surface F2 in contact with the side surface 132 of the mounting groove 13 is reduced compared to the above-mentioned embodiments. Therefore, the sliding resistance between the second surface F2 and the side surface 132 is reduced, resulting in low friction and low torque.

[0103] [Aspect 2] As illustrated in Fig. 22, the seal ring 20 of the second embodiment is formed with a step portion 25 and a step portion 26. The step portion 25 is a recess formed in an arc shape along the outer periphery of the surface of the seal ring 20 facing the X1 direction. The bottom surface of the step portion 25 is the first surface F1. The step portion 26 is a recess formed in an arc shape along the outer periphery of the surface of the seal ring 20 facing the X2 direction. The bottom surface of the step portion 26 is the second surface F2. A linear burr L1 is formed on the first surface F1, and a linear burr L2 is formed on the second surface F2.

[0104] The outer peripheral surface Gb in the second embodiment is the outer peripheral surface of an arc-shaped protrusion protruding outward from the inner wall surfaces of the stepped portions 25 and 26. In the second embodiment, the area (sliding area) of the outer peripheral surface Gb in contact with the inner peripheral surface 113 of the shaft hole 112 is reduced compared to the above-mentioned embodiments. Therefore, the sliding resistance between the outer peripheral surface Gb and the inner peripheral surface 113 is reduced, resulting in low friction and low torque.

[0105] (5) In each of the above embodiments, the sealing structure 100 is used in a transmission, but the applications of the sealing structure 100 are not limited to the above examples. For example, the sealing structure 100 in each of the above embodiments can be used for any application, such as an engine seal, a differential seal, a motor seal, or a hub bearing seal.

[0106] (6) The term "nth" (n is a natural number) in this application is used only as a formal and convenient label to distinguish each element in the description and does not have any substantial meaning. Therefore, there is no room for restrictive interpretation of the position of each element or the order of production, etc., based on the term "nth".

[0107] E: Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0108] A method for producing a resin molded product according to one embodiment (embodiment 1) of the present disclosure is a method for producing an arc-shaped resin molded product having a first surface and a second surface located on opposite sides of each other along an axial direction, an inner peripheral surface and an outer peripheral surface between the first surface and the second surface, and including a first end and a second end, and includes a molding step of forming an intermediate molded product including the resin molded product and one or more protrusions connected to the inner peripheral surface of the resin molded product by supplying a resin material to an internal space of an injection mold including an inner mold having an inner peripheral molding surface that forms the inner peripheral surface and an outer mold having an outer peripheral molding surface that forms the outer peripheral surface, a mold opening step of removing the inner mold, and a demolding step of releasing the intermediate molded product from the outer mold by moving the one or more protrusions. In the above embodiment, the resin molded product is released from the outer mold by moving one or more protrusions molded together with the resin molded product. Therefore, the resin molded product can be easily demolded. Note that after the demolding step, a removal step of removing one or more protrusions from the intermediate molded product may be performed.

[0109] In a specific example (Aspect 2) of Aspect 1, the one or more protrusions include a first protrusion and a second protrusion, and in the demolding step, the first protrusion and the second protrusion are brought close to each other to release the resin molded product from the outer mold. According to the above aspect, the resin molded product can be released from the outer mold by the simple step of bringing the first protrusion and the second protrusion close to each other.

[0110] In a specific example (Aspect 3) of Aspect 2, the internal space includes an arc-shaped molding space that forms the resin molded product, a supply flow path for supplying the resin material to the molding space, a first space that forms the first protrusion, and a second space that forms the second protrusion, and the supply flow path communicates with a specific point of the molding space in the circumferential direction, the first space communicates with an end of the molding space that corresponds to the specific point and the first end, and the second space communicates with an end of the molding space that corresponds to the specific point and the second end. According to the above aspect, the first space and the second space are installed on both sides in the circumferential direction of the molding space, sandwiching a specific position where the supply flow path (gate) communicates. Therefore, the resin material supplied from the supply flow path can be effectively filled up to both ends of the molding space, the first space, and the second space. In addition, a form in which the first protrusion is formed near the first end, and the second protrusion is formed near the second end can be adopted. According to the above embodiment, the resin molded product can be easily released from the outer mold by bringing the first protrusion and the second protrusion closer to each other.

[0111] In a specific example (Aspect 4) of any one of Aspects 1 to 3, a molding groove is formed in the inner peripheral surface of the outer mold along the circumferential direction, and the molding groove has a first side surface forming a first outer region of the first surface and a second side surface forming a second outer region of the second surface, with the outer peripheral molding surface as a bottom surface, and the inner mold includes a first molding surface forming a first inner region inside the first outer region of the first surface, and a second molding surface forming a second inner region inside the second outer region of the second surface. In the above aspects, the boundary between the first side surface of the outer mold and the first molding surface of the inner mold faces the first surface of the resin molded product, and the boundary between the second side surface of the outer mold and the second molding surface of the inner mold faces the second surface of the resin molded product. That is, the boundary between the outer mold and the inner mold does not face the outer peripheral surface of the resin molded product. According to the above configuration, it is possible to prevent linear burrs corresponding to the boundary between the outer mold and the inner mold from being formed on the outer peripheral surface of the resin molded product. Therefore, it is possible to maintain a high level of sealing performance on the outer circumferential surface of the resin molded product without the need for polishing the outer circumferential surface of the resin molded product to remove burrs.

[0112] In a specific example (Aspect 5) of Aspect 4, at least one of the first corner between the first side surface and the outer peripheral molding surface and the second corner between the second side surface and the outer peripheral molding surface is rounded. In the above aspect, at least one of the corner between the first side surface and the outer peripheral molding surface and the corner between the second side surface and the outer peripheral molding surface is rounded. Therefore, it is possible to make the corner between at least one of the first surface and the second surface of the resin molded product and the outer peripheral surface rounded without requiring work such as polishing.

[0113] In a specific example (Aspect 6) of Aspect 4 or Aspect 5, the inner mold includes a first mold including the first molding surface and a first inner peripheral surface of the inner peripheral molding surface, and a second mold including the second molding surface and a second inner peripheral surface of the inner peripheral molding surface, and the boundary between the first inner peripheral surface and the second inner peripheral surface is located between the first surface and the second surface in the axial direction. In the above aspects, the boundary between the first inner peripheral surface of the first mold and the second inner peripheral surface of the second mold is located between the first surface and the second surface. Therefore, it is possible to prevent linear burrs corresponding to the boundary between the first mold and the second mold from being formed along the edge of the first surface side or the edge of the second surface side of the inner peripheral surface of the resin molded product.

[0114] In a specific example (Aspect 7) of Aspect 6, a first molding hole that forms a part of the one or more protrusions is formed in a first opposing surface of the first mold that faces the second mold, and a second molding hole that forms another part of the one or more protrusions is formed in a second opposing surface of the second mold that faces the first mold. In the above aspect, since spaces (first molding hole, second molding hole) for forming the protrusions are formed in both the first mold and the second mold, it is possible to form a protrusion that is easy to grip and has a sufficient axial dimension.

[0115] An injection molding mold according to one embodiment (embodiment 8) of the present disclosure is an injection molding mold used for manufacturing an arc-shaped resin molded product having a first surface and a second surface located opposite each other along an axial direction, and an inner peripheral surface and an outer peripheral surface between the first surface and the second surface, and including a first end and a second end, and comprises an inner mold having an inner peripheral molding surface that forms the inner peripheral surface, and an outer mold having an outer peripheral molding surface that forms the outer peripheral surface, and a molding groove is formed on the inner peripheral surface of the outer mold along the circumferential direction, and the molding groove has a first side surface that forms a first outer region of the first surface and a second side surface that forms a second outer region of the second surface, with the outer peripheral molding surface as a bottom surface, and the inner mold includes a first molding surface that forms a first inner region inside the first outer region of the first surface, and a second molding surface that forms a second inner region inside the second outer region of the second surface.

[0116] A resin molded product according to one embodiment (embodiment 9) of the present disclosure is an arc-shaped resin molded product including a first surface and a second surface located opposite each other along the axial direction, an inner circumferential surface and an outer circumferential surface between the first surface and the second surface, and a first end surface and a second end surface, wherein a first linear protrusion extending along the circumferential direction is formed between a first outer region of the first surface and a first inner region inside the first outer region, and a second linear protrusion extending along the circumferential direction is formed between a second outer region of the second surface and a second inner region inside the second outer region. [Explanation of symbols]

[0117] 100...sealing structure, 11...casing, 12...shaft member, 13...mounting groove, 15...gap, 20...seal ring, 21...joint portion, 22...body portion, 30...auxiliary molding portion, 31...columnar portion, 32...branch portion, 41...first tab, 42...second tab, 44...gripping portion, 45...connecting portion, 50...inner mold, 51...outer peripheral surface, 52...supply flow passage, 55...inner peripheral molding surface, 60...outer mold, 61...inner peripheral surface, 62...molding groove, 64...outer peripheral molding surface, 70...first mold, 71...first opposing surface, 72...molding flow passage, 73...flow passage, 74a ...molding hole, 74b...molding hole, 80...second mold, 81...second opposing surface, 82...molding flow path, 84a...molding hole, 84b...molding hole, 85a...communicating passage, 85b...communicating passage, 200...injection molding mold, 300...intermediate molded product, 301...first auxiliary molding portion, 302...second auxiliary molding portion, 521...first supply flow path, 522...second supply flow path, 531...first space, 532...second space, 631...first side, 632...second side, 721...first molding surface, 722...first inner surface, 821...second molding surface, 822...second inner surface.

Claims

1. A method for manufacturing an arc-shaped resin molded product having a first surface and a second surface located opposite to each other along an axial direction, an inner peripheral surface and an outer peripheral surface between the first surface and the second surface, and including a first end portion and a second end portion, a molding process in which a resin material is supplied into an internal space of an injection molding die including an inner mold having an inner peripheral molding surface that forms the inner peripheral surface, and an outer mold having an outer peripheral molding surface that forms the outer peripheral surface, thereby forming an intermediate molded product that includes the resin molded product and one or more protrusions connected to the inner peripheral surface of the resin molded product; a mold opening step of removing the inner mold; a demolding step of demolding the intermediate molded product from the outer mold by moving the one or more protrusions; A method for producing a resin molded product comprising the steps of:

2. the one or more protrusions include a first protrusion and a second protrusion; In the demolding step, the first protrusion and the second protrusion are moved closer to each other to demold the resin molded product from the outer mold. A method for producing the resin molded product of claim 1.

3. The internal space is an arc-shaped molding space in which the resin molded product is formed; a supply flow path for supplying the resin material to the molding space; a first space forming the first protrusion; a second space that forms the second protrusion, the supply flow path communicates with a specific point in the molding space in a circumferential direction, the first space communicates with the specific point in the molding space and an end portion corresponding to the first end portion; The second space communicates with the specific point in the molding space and an end portion corresponding to the second end portion. The method for producing a resin molded product according to claim 2.

4. A molding groove is formed in the inner peripheral surface of the outer mold along the circumferential direction, the forming groove has the outer peripheral forming surface as a bottom surface, a first side surface that forms a first outer region of the first surface, and a second side surface that forms a second outer region of the second surface, The inner mold includes a first molding surface that forms a first inner region of the first surface that is inside the first outer region, and a second molding surface that forms a second inner region of the second surface that is inside the second outer region. A method for producing the resin molded product of claim 1.

5. At least one of a first corner between the first side surface and the outer peripheral molding surface and a second corner between the second side surface and the outer peripheral molding surface is rounded. The method for producing a resin molded product according to claim 4.

6. The inner mold is a first mold including the first molding surface and a first inner peripheral surface of the inner peripheral molding surface; a second mold including the second molding surface and a second inner peripheral surface of the inner peripheral molding surface; The boundary between the first inner circumferential surface and the second inner circumferential surface is located between the first surface and the second surface in the axial direction. The method for producing a resin molded product according to claim 4 or 5.

7. a first molding hole that forms a part of the one or more protrusions is formed in a first opposing surface of the first mold that faces the second mold; A second molding hole for forming another part of the one or more protrusions is formed in a second opposing surface of the second mold that faces the first mold. The method for producing a resin molded product according to claim 6.

8. an injection molding die used for manufacturing an intermediate molded product having a first surface and a second surface located opposite each other along an axial direction, and an inner circumferential surface and an outer circumferential surface between the first surface and the second surface, the intermediate molded product having a circular arc-shaped resin molded product including a first end portion and a second end portion, and a first protrusion portion and a second protrusion portion connected to the inner circumferential surface; an inner mold having an inner peripheral molding surface that forms the inner peripheral surface; an outer mold having an outer circumferential molding surface that forms the outer circumferential surface; The internal space formed by the inner mold and the outer mold is an arc-shaped molding space in which the resin molded product is formed; a first space forming the first protrusion; a second space that forms the second protrusion Injection mold.

9. The internal space is further comprising a supply flow path for supplying a resin material to the molding space; the supply flow path communicates with a specific point in the molding space in a circumferential direction, the first space communicates with the specific point in the molding space and an end portion corresponding to the first end portion; The second space communicates with the specific point in the molding space and an end portion corresponding to the second end portion.

9. The injection mold of claim 8.

10. A molding groove is formed in the inner peripheral surface of the outer mold along the circumferential direction, the forming groove has the outer peripheral forming surface as a bottom surface, a first side surface that forms a first outer region of the first surface, and a second side surface that forms a second outer region of the second surface, The inner mold includes a first molding surface that forms a first inner region of the first surface that is inside the first outer region, and a second molding surface that forms a second inner region of the second surface that is inside the second outer region.

10. The injection molding die of claim 8 or claim 9.

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