Method for manufacturing a tire vulcanization mold and a tire vulcanization mold

Abstract

To improve the quality of tire vulcanization molds. [Solution] The method for manufacturing a tire vulcanization mold includes a mold forming step S40 and a casting step S50. In the mold forming step S40, a mold 90 is formed in which a protruding member 80 is embedded so as to protrude from the outer surface 91. The protruding member 80 has a cavity 83 inside the portion embedded in the mold 90. In the casting step S50, molten metal is poured into the mold 90 to cast a mold 40 in which the protruding member 80 is integrated.

Description

Technical Field

[0006] , , ,

[0007] , , , , [Figure 1] ,<000003​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Figure 1 is a schematic diagram of a tire vulcanizing machine 1. [Figure 2] Figure 2 is a schematic diagram of the tread surface 100a of a tire 100 that has been vulcanized and molded in a tire vulcanizing machine 1. [Figure 3] Figure 3 is a flowchart showing the manufacturing method for tire vulcanization molds. [Figure 4] Figure 4 is a schematic diagram showing the process of forming the rubber mold 76 from the master model 70. [Figure 5] Figure 5 is a schematic diagram showing an example of a mold manufacturing process. [Figure 6] Figure 6 is a plan view of the protruding member 80. [Figure 7] Figure 7 is a plan view of the protruding member 80. [Figure 8] Figure 8 is a schematic diagram showing the process of forming the mold 90 from the rubber mold 76. [Figure 9] Figure 9 is a schematic diagram showing the casting process S50. [Figure 10] Figure 10 is a cross-sectional view of the protruding member 80 integrated with the mold 40. [Figure 11] Figure 11 is a schematic diagram showing a casting process S50 according to another embodiment. [Figure 12] Figure 12 is a schematic diagram of a protruding member 180 according to another embodiment. [Modes for carrying out the invention]

[0008] One embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following embodiments. Each drawing is schematic and does not necessarily reflect the actual object. Furthermore, each drawing is merely an example and does not limit the present invention unless specifically mentioned. Also, components and parts that perform the same function are appropriately denoted by the same reference numerals, and redundant explanations are omitted.

[0009] <Tire vulcanizing machine 1> Figure 1 is a schematic diagram of a tire vulcanizing machine 1. Figure 1 schematically shows a cross-section of the tire vulcanizing machine 1 during the vulcanization of the low cover 110. In Figure 1, the hatching of the low cover 110 and bladder 68 is omitted.

[0010] As shown in Figure 1, the tire vulcanizing machine 1 comprises a tire vulcanizing mold 10 and a bladder centering mechanism 60. The bladder centering mechanism 60 includes a bladder 68 located at the center of the tire vulcanizing machine 1. In the tire vulcanizing machine 1, a low cover 110 supported by the bladder 68 is pressed against the tire vulcanizing mold 10 and vulcanized to form the tire.

[0011] <Low Cover 110> The low cover 110 is an unvulcanized tire before vulcanization molding, and is also called a green tire. Although not shown in the diagram, the low cover 110 is a cylindrical member in which unvulcanized sidewall rubber and tread rubber are bonded to a base material such as bead wire, carcass, or belt. The low cover 110 has a tread portion 112 and a sidewall portion 114. The tread portion 112 is the part of the tire that comes into contact with the road surface after vulcanization. The sidewall portion 114 is the part of the tire that comes into contact with the side surface after vulcanization.

[0012] <Tire vulcanization mold 10> The tire vulcanization mold 10 comprises a plurality of molds 20, 30, and 40. The plurality of molds 20, 30, and 40 are arranged in a toroidal manner so as to surround the bladder 68. The tire vulcanization mold 10 comprises a plurality of molds 20, 30, and 40 arranged around the bladder 68. The material of the tire vulcanization mold 10 may be a metal such as aluminum or an aluminum alloy. The material of the tire vulcanization mold 10 is not particularly limited.

[0013] When the tire is vulcanized, the molds 20, 30, 40 are heated by a heater (not shown). The molds 20, 30, 40 have molding surfaces 22, 32, 42 for forming the outer shape of the tire. When the tire is vulcanized, the molding surfaces 22, 32, 42 of the molds 20, 30, 40 are continuous, and the mold inner space 10a is formed. The local cover 110 is heated and pressurized while being pressed against the molding surfaces 22, 32, 42 in the mold inner space 10a, and is vulcanized and molded.

[0014] The molding surfaces 22, 32, 42 of the molds 20, 30, 40 are provided with concavities and convexities adapted to the intended outer shape of the tire. For example, the molding surfaces 22, 32 of the molds 20, 30 may be formed with concavities and convexities for displaying tire information on the sidewall portion of the tire. The molding surface 42 of the mold 40 is formed with concavities 42a for forming a tread pattern, a wear indicator, etc. according to the intended function on the tread portion of the tire.

[0015] The molds 20, 30 are also referred to as side molds. The sidewall portion 114 of the local cover 110 is pressed against the molding surfaces 22, 32 of the molds 20, 30. Thereby, the sidewall portion of the tire is vulcanized and molded. The mold 40 is also referred to as a tread mold. The tread portion 112 of the local cover 110 is pressed against the molding surface 42 of the mold 40. Thereby, the tread portion of the tire is vulcanized and molded.

[0016] The mold 20 is annular. The mold 20 is provided below the tire vulcanization mold 10. The mold 20 is attached to the mold base 12. The mold base 12 is attached to, for example, a press table (not shown). The mold 20 is provided with a bead ring 24 for holding the bead portion of the local cover 110.

[0017] The mold 30, like the mold 20, is annular in shape. The mold 30 is located above the tire vulcanization mold 10. The mold 30 faces the mold 20 in the vertical direction. The mold 30 is attached to the mold base 14. In this embodiment, the mold base 14 is attached to a press machine and is configured to be movable vertically. The mold 30 is provided with a bead ring 34 for holding the bead portion of the low cover 110. The molds 20 and 30 may be composed of multiple mold members.

[0018] The mold 40 is a mold component for forming the tread portion of the tire. The molding surface 42 of the mold 40 is the surface for forming the tread portion of the tire. The tire vulcanization mold 10 is provided with a plurality of molds 40 divided along the circumferential direction. The plurality of molds 40 are arranged at predetermined intervals in the circumferential direction.

[0019] Multiple molds 40 are driven radially inward and outward by a mold opening / closing mechanism 16. The mold opening / closing mechanism 16 comprises a slider 16a to which the molds 40 are attached, and a pusher 16b that is driven vertically. The outer surface of the slider 16a has an inclined surface that widens outward as it extends downward. The pusher 16b has an inclined surface that widens outward as it extends downward, opposite to the inclined surface of the slider 16a. The contact between the inclined surface of the pusher 16b and the inclined surface of the slider 16a causes the slider 16a to move inward and outward. This opens and closes the molds 40 radially.

[0020] Although not shown in the diagram, before the tire is vulcanized, the molds 40 are positioned radially outward, separated from adjacent molds 40. At this time, mold 30 is held above the low cover 110. During tire vulcanization, the molds 40 move radially inward. The multiple molds 40 are continuous in the circumferential direction. Simultaneously, mold 30, which was held above the low cover 110, moves downward. As a result, the tire vulcanization mold 10 is closed, and molds 20, 30, and 40 become continuous. During tire vulcanization, with the tire vulcanization mold 10 closed, the low cover 110, supported by the bladder 68, is pressed against the molding surfaces 22, 32, and 42 of molds 20, 30, and 40.

[0021] <Bladder center mechanism 60> The bladder center mechanism 60 comprises a center post 62, clamp rings 64 and 66, and a bladder 68.

[0022] The bladder 68 is located in the mold space 10a. The bladder 68 is a component that is pressed against the inner surface of the low cover 110. The bladder 68 is a cylindrical elastic body made of rubber. As the bladder 68 expands, the low cover 110 is pressed against the molding surfaces 22, 32, and 42 of the molds 20, 30, and 40, and the outer shape of the tire is formed. The bladder 68 is located in the center between the vertically opposing molds 20 and 30. The bladder 68 is held with the center post 62 as its central axis.

[0023] The center post 62 is an axial member that extends along the direction in which the molds 20 and 30 face each other. The center post 62 penetrates the central part of the mold 20 that forms the lower sidewall portion 114. A pair of opposing clamping rings 64 and 66 are attached to the center post 62.

[0024] The clamp ring 66 is a disc-shaped member attached to the upper end of the center post 62. The clamp ring 66 is a member that grips the upper end of the bladder 68. Although not shown in the illustration, the clamp ring 66 may be, for example, a member that can be divided into upper and lower parts, and may have a structure that holds the peripheral edge on the upper end side of the bladder 68 by clamping it. The clamp ring 64 is a disc-shaped member attached to the upper surface of the bead ring 24. The clamp ring 64 may be attached to the center post 62. The clamp ring 64 is a member that grips the lower end of the bladder 68. The lower end of the bladder 68 may be held by being sandwiched between the clamp ring 64 and the bead ring 24.

[0025] A fluid (such as steam or nitrogen) is supplied from a fluid supply device (not shown) to the space surrounded by the clamp rings 64 and 66 and the bladder 68. Heat and pressure are applied to the low cover 110 from the inside in the mold space 10a of the tire vulcanization mold 10. As a result, the low cover 110 is heated while being pressed against the tire vulcanization mold 10, and the tire is vulcanized.

[0026] Figure 2 is a schematic diagram of the tread surface 100a of a tire 100 that has been vulcanized and molded in a tire vulcanizing machine 1. In Figure 2, a portion of the tread pattern of the tread surface 100a of the tire 100 is schematically shown. In Figure 2, the circumferential direction of the tire 100 is indicated by an X arrow, and the width direction of the tire 100 is indicated by a Y arrow. In Figure 2, the portion of the tread surface 100a of the tire 100 where grooves 101 to 103 have not been formed is indicated by diagonal hatching. The tire 100 shown in Figure 2 is a studless tire. However, the tire 100 is not limited to a studless tire.

[0027] As shown in Figure 2, grooves 101 to 103 are formed on the tread surface 100a of the tire 100. The grooves 101 to 103 are recessed relative to the tread surface 100a.

[0028] The groove 101 extends along the circumferential direction X of the tire 100. The groove 101 is recessed relative to the tread surface 100a such that its cross-sectional shape, when viewed along the direction in which the groove 101 extends, is approximately rectangular.

[0029] The groove 102 extends along the width direction Y of the tire 100. The groove 102 intersects with the groove 101. The angle of the groove 102 with respect to the groove 101 is not particularly limited. Like the groove 101, the groove 102 is recessed relative to the tread surface 100a such that the cross-sectional shape viewed along the direction in which the groove 102 extends is approximately rectangular. A pair of side surfaces 102a of the groove 102 have a plurality of recesses 102a1 that are recessed outwards. This can improve the frictional force between the tread surface 100a and the road surface. The recesses 102a1 are recessed toward the opposite direction from the direction in which the pair of side surfaces 102a of the groove 102 face each other. The shape of the recesses 102a1 is not particularly limited. In this embodiment, each recess 102a1 is recessed from the side surface 102a in a roughly triangular pyramidal shape. Multiple recesses 102a1 are arranged at predetermined intervals along the direction in which the groove 102 extends (width direction Y) and along the depth direction of the groove 102.

[0030] The grooves 103 extend along the width direction Y of the tire 100. Multiple grooves 103 are formed in the region sandwiched between grooves 102. The grooves 103 extend along the width direction Y while being folded back in a zigzag pattern. The grooves 103 are notches provided in the tread surface 100a, also called sipes. The grooves 103 are narrower than grooves 101 and 102. The grooves 103 may be provided to adjust the hardness of different parts of the tread surface 100a. For example, in a studless tire, the grooves 103 may be provided to increase the contact area with the road surface and increase the frictional force.

[0031] The following describes a mold (tread mold) 40 for manufacturing a tire 100 having such a tread pattern, along with its manufacturing method. Note that the tire tread pattern is not limited to the embodiment described above, and can be modified in various ways depending on the tire's intended use.

[0032] <Method for manufacturing tire vulcanization molds> Figure 3 is a flowchart showing the manufacturing method of a tire vulcanization mold. Figure 4 is a schematic diagram showing the formation of a rubber mold 76 from a master model 70.

[0033] As shown in Figure 3, the method for manufacturing a tire vulcanization mold includes a master model preparation step S10, a rubber mold forming step S20, a protruding member preparation step S30, a mold forming step S40, and a casting step S50.

[0034] <Master model preparation process S10> In the master model preparation step S10, a master model 70 (see Figure 4) is prepared. The master model 70 has a shape corresponding to the shape obtained by dividing the tire along the circumferential direction (for example, 4 to 12 divisions). The master model 70 may be formed from chemical wood. In the master model preparation step S10, a master model 70 of the desired shape may be prepared by cutting or other processes of the chemical wood.

[0035] As shown in Figure 4, the master model 70 has a surface corresponding to the surface shape of the target tire. The master model 70 is provided with recess-forming members 73 and 74 that form recesses in the rubber mold 76. The recess-forming members 73 and 74 protrude from the surface 71 of the master model 70. The recess-forming member 73 is thicker than the recess-forming member 74. The recess-forming members 73 and 74 may be embedded in recessed portions relative to the surface 71 of the master model 70.

[0036] <Rubber mold forming process S20> In the rubber mold forming process S20, a rubber mold 76 is formed from a master model 70. The master model 70 is placed in a mold 75 for molding the rubber mold 76. A space 75a for filling with rubber is formed between the master model 70 and the mold 75. Rubber (for example, silicone rubber) is filled into the space 75a and the rubber is cured. This forms the rubber mold 76. The outer surface 76a of the rubber mold 76 is formed by the mold 75. The inner surface 76b of the rubber mold 76 is formed by the master model 70. The inner surface 76b of the rubber mold 76 has a shape that is an inversion of the surface of the master model 70. Therefore, recesses 77 and 78 (see Figure 8) are formed on the inner surface 76b of the rubber mold 76 by recess-forming members 73 and 74 that protrude from the surface 71. After the formation of the rubber mold 76, the rubber mold 76 is removed from the mold 75.

[0037] <Protruding member preparation process S30> In the protruding member preparation step S30, a protruding member 80 is prepared to be held in a recess 77 (see Figure 8) formed on the inner surface 76b of the rubber mold 76. The protruding member 80 is plate-shaped and is a component that is integrated with the mold 40. As will be described later, the protruding member 80 is embedded in the mold 90 in the mold forming step S40, and then integrated with the mold 40 in the casting step S50. As a result, part of the protruding member 80 is held embedded in the mold 40, and part of it protrudes from the molding surface 42.

[0038] Incidentally, the inventors have found that molds with integrated protruding members for forming tire grooves sometimes exhibit casting defects after casting. For example, burrs or other defects sometimes appeared on the mold surface near the protruding members after casting. When such casting defects occurred, damage such as cracks or fissures was observed in the mold at the location where the protruding members were held. This phenomenon is particularly likely to occur when the plate-shaped protruding members for forming tire grooves are thick. If tires are vulcanized using molds with casting defects, vulcanization defects in the tires may occur, such as a decrease in the roundness of the tires.

[0039] Figure 5 is a schematic diagram showing an example of the mold manufacturing process. As shown in Figure 5, solid, metal protruding members 280 and 289 are embedded in the mold 290. The protruding members 280 and 289 protrude from the surface of the mold 290. The protruding member 280 is embedded in a recess 292 of the mold 290. The inventors considered the following reasons for the casting defects described above. A space is formed between the surface of the mold 290 and the mold 295 through which molten metal flows. When molten metal flows into this space, the temperature of the mold 290 and the protruding members 280 and 289 rises. At this time, the metal protruding members 280 and 289 expand more than the mold 290. When the protruding members 280 and 289 expand significantly in the thickness direction, a greater load is placed on the mold 290. The thicker the portion of the mold to which the protruding member is embedded, the greater the volume change during thermal expansion, and the greater the load on the mold 290. In particular, the load is greater near the recess 292 to which the protruding member 280 is embedded. If the mold can no longer withstand the load, cracks, fissures, and other damage may occur in the mold 290. Molten metal may flow into the damaged portion 291. When the molten metal cools, it hardens, and casting defects may occur, such as burrs 241 remaining on the surface of the mold 240.

[0040] In contrast, in the manufacturing method disclosed herein, a protruding member 80, as described below, is prepared in the protruding member preparation step S30. In this embodiment, the protruding member 80 is used to form a groove 102 in the tire 100, but is not limited to this form and may be used to form a groove 101 in the tire 100. Figures 6 and 7 are plan views of the protruding member 80. Figure 6 shows the protruding member 80 as viewed along the thickness direction. In Figure 6, the boundary between the portion embedded in the mold 40 and the portion protruding from the mold 40 is indicated by a dashed line. Figure 7 shows the protruding member 80 as viewed from the side embedded in the mold 40.

[0041] As shown in Figure 6, the protruding member 80 is a substantially plate-shaped member. The protruding member 80 is a member held in the mold 40 so as to protrude from the molding surface 42 of the mold 40 (see Figure 9). The protruding member 80 is made of metal. The protruding member 80 is made of a different metal than the mold 40. The protruding member 80 may be made of, for example, stainless steel, stainless steel alloy, iron, etc.

[0042] The protruding member 80 comprises a base portion 81 and a protruding portion 82. The base portion 81 is the part that is embedded in the mold 40 when it is integrated with the mold 40. The protruding portion 82 is the part that protrudes from the molding surface 42 of the mold 40. The shape and dimensions of the protruding portion 82 correspond to the shape and dimensions of the groove 102 of the tire 100. The boundary between the base portion 81 and the protruding portion 82 corresponds to the surface shape of the tire 100 and the mold 40, and is substantially arc-shaped. The protruding member 80 has a cavity 83 inside.

[0043] As shown in Figures 6 and 7, the protruding member 80 comprises a first surface 80a and a second surface 80b. The first surface 80a and the second surface 80b are the larger surfaces of the plate-shaped protruding member 80. The first surface 80a and the second surface 80b straddle the base 81 and the protruding portion 82, respectively. The first surface 80a and the second surface 80b face each other with a cavity 83 in between. In other words, a cavity 83 is provided between the first surface 80a and the second surface 80b. The second surface 80b has protruding pieces 80b1 at both ends and in the center in the longitudinal direction. The protruding pieces 80b1 are provided on the base 81. In a plan view, the protruding pieces 80b1 protrude in a predetermined direction relative to the first surface 80a (downward in the configuration shown in Figure 6).

[0044] The first surface 80a and the second surface 80b have shapes corresponding to the side surface 102a of the groove 102 of the tire 100 (see Figure 2). In this embodiment, protrusions 85 are formed on the outer surfaces of the first surface 80a and the second surface 80b, respectively. The protrusions 85 are parts for forming recesses 102a1 on the side surface 102a of the groove 102 of the tire 100 (see Figure 2). The protrusions 85 are approximately triangular pyramidal in shape. Multiple protrusions 85 are provided on the outer surfaces of the first surface 80a and the second surface 80b at predetermined intervals along the direction in which the groove 102 extends and the direction corresponding to the depth of the groove 102. The shape, dimensions, number, etc. of the protrusions 85 are set according to the configuration of the groove 102 of the target tire 100. Note that the protrusions 85 are not necessarily required.

[0045] The protruding member 80 has a first side surface 80c, a second side surface 80d, and a third side surface 80e that connect the first surface 80a and the second surface 80b. The first side surface 80c and the second side surface 80d each straddle the base 81 and the protruding portion 82. The first side surface 80c and the second side surface 80d each connect the distant sides of the first surface 80a and the second surface 80b. The first side surface 80c and the second side surface 80d may form a boundary with other protruding members (members that form grooves on the tread surface of the tire). The first side surface 80c and the second side surface 80d are substantially straight. The third side surface 80e connects the first surface 80a, the second surface 80b, the first side surface 80c, and the second side surface 80d. The third side surface 80e is provided on the protruding portion 82. The third side surface 80e has a shape that corresponds to the bottom surface of the groove 102 of the tire 100. The third side surface 80e is curved in a roughly arc shape.

[0046] As shown in Figure 7, the protruding member 80 has an opening 84. The opening 84 is connected to the cavity 83. The opening 84 is formed on the protruding member 80 at a position opposite the third side surface 80e. Therefore, one of the four sides of the protruding member 80 is open. The opening 84 is provided on the base portion 81.

[0047] Such protruding members 80 can be formed, for example, by metal additive manufacturing. Metal additive manufacturing is a technique for forming three-dimensional shapes by melting or sintering metal powder and layering it. Metal additive manufacturing can be performed using a 3D printer. In metal additive manufacturing, the metal can be melted or sintered by methods such as selective laser sintering (SLS), selective laser melting (SLM), or electron beam melting (EBM). In this embodiment, the protruding members 80 are formed by powder bed fusion, also known as powder bed fusion (PBF). The metal additive manufacturing method for forming the protruding members 80 is not limited to powder bed fusion, and other methods may be used.

[0048] In the protruding member preparation step S30, a member 89 to be held in a recess 78 formed on the inner surface 76b of the rubber mold 76, and a member to be held in a recess (not shown) that intersects with the recess 77 may be prepared (see Figure 8). Member 89, like the protruding member 80, is held in the mold 40 and protrudes from the molding surface 42. Member 89 is thinner than the protruding member 80 and has a shape and dimensions corresponding to the groove 103. Member 89, like the protruding member 80, is made of a different metal than the mold 40. Member 89 may be made of, for example, stainless steel, stainless steel alloy, iron, etc.

[0049] <Mold formation process S40> In the mold forming process S40, a mold 90 is formed in which the protruding member 80 is embedded so as to protrude from the surface (outer surface) 91 (see Figure 8). In the mold forming process S40, the mold 90 is formed from the rubber mold 76.

[0050] Figure 8 is a schematic diagram showing how a mold 90 is formed from a rubber mold 76. As shown in Figure 8, a protruding member 80 is mounted in a recess 77 of the rubber mold 76. In this embodiment, the protruding member 80 is held on the surface (outer surface) 91 of the mold 90 such that the opening 84 is exposed on the surface 91 of the mold 90. Here, the base 81 of the protruding member 80 is embedded in the recess 77 of the rubber mold 76 such that the protruding portion 82 protrudes from the outer surface 76a of the rubber mold 76. In this embodiment, a portion of the projection 85 is housed in the rubber mold 76. A member 89 is mounted in a recess 78 of the rubber mold 76.

[0051] The rubber mold 76, with the protruding members 80 and 89 attached, is placed in the mold 86 for forming the casting mold 90. Spaces 86a for pouring plaster are formed in the rubber mold 76 and the mold 86. Plaster is poured into the space 86a and allowed to harden. This forms a casting mold 90 in which the protruding members 80 are embedded so as to protrude from the surface. The casting mold 90 has recesses 92 in which the protruding portions 82 of the protruding members 80 are embedded.

[0052] The mold 90 is an inverted version of the rubber mold 76. When the mold 90 is formed by inverting the rubber mold 76, the protruding members 80 and 89 that protrude from the inner surface 76b of the rubber mold 76 are transferred to the mold 90. The protruding member 80 was held in the rubber mold 76 so that its protruding portion 82 protruded from the inner surface 76b. Therefore, in the mold 90, which is the inverted rubber mold 76, the protruding portion 82 is embedded in the mold 90. As a result, the protruding member 80 has a cavity 83 in the portion embedded in the mold 90. Also, the base portion 81 is exposed from the surface 91 of the mold 90. Therefore, the opening 84 connected to the cavity 83 is exposed from the surface 91 of the mold 90. After the formation of the mold 90, the mold 90 is removed from the mold 86.

[0053] <Casting process S50> In casting process S50, the mold 40 is cast from the mold 90. In casting process S50, molten metal is poured between the mold 90 and the mold 95 to form the mold 40 into which the protruding member 80 is integrated. The formation of the mold 40 is carried out, for example, by the following method.

[0054] Figure 9 is a schematic diagram showing the casting process S50. In Figure 9, the member 89 is not shown. Figure 10 is a cross-sectional view of the protruding member 80 integrated with the mold 40. As shown in Figure 9, the mold 90 is placed in the mold 95 for shaping the mold 40. A space 95a into which molten metal is poured is formed between the mold 90 and the mold 95. Molten metal (for example, molten aluminum) is poured into the space 95a. The opening 84 of the protruding member 80 (see Figures 6 and 7) is exposed in the space 95a. As a result, the molten metal flows from the opening 84 towards the cavity 83.

[0055] As the molten metal cools and solidifies, the solidified metal becomes integrated with the protruding member 80 and member 89 (not shown). As shown in Figure 10, a portion 40a of the solidified mold 40 is integrated with the protruding member 80, filling the cavity 83. At this time, the protruding member 80 is transferred from the mold 90 to the mold 40. The mold 90 and mold 95 are removed, and the solidified metal is taken out. This forms the mold 40 with the protruding member 80 integrated into it. The outer surface 41 of the mold 40 is formed by the inner surface 95b of the mold 95. The inner surface (molding surface) 42 of the mold 40 is formed by the outer surface 91 of the mold 90. The molding surface 42 of the mold 40 is the inverted shape of the outer surface 91 of the mold 90. Therefore, the protruding portion 82 of the protruding member 80 and member 89 protrude from the molding surface 42 of the mold 40. By performing downstream molding using the mold 40, a tire is formed in which grooves 101 to 103 are formed on the tread surface 100a, as shown in Figure 2.

[0056] By the above manufacturing method, a tire vulcanization mold 10 (mold 40) is manufactured, as shown in Figure 10, which is equipped with a protruding member 80 that protrudes from the molding surface 42 for forming the tire tread, and which has a cavity 83 in the portion of the protruding member 80 that protrudes from the molding surface 42.

[0057] In the embodiment described above, the method for manufacturing a tire vulcanization mold includes a mold forming step S40 and a casting step S50. In the mold forming step S40, a mold 90 is formed in which a protruding member 80 is embedded so as to protrude from the outer surface 91. In the casting step S50, as shown in Figures 8 and 9, molten metal is poured into the mold 90 to cast a mold 40 in which the protruding member 80 is integrated. In the casting step S50, the molten metal constituting the mold 40 flows into the space 95a between the mold 90 and the mold 95. Here, the protruding member 80 has a cavity 83 inside the portion embedded in the mold 90. The outside of the portion of the protruding member 80 embedded in the mold 90 is covered by the mold 90. During casting, the protruding member 80 and the mold 90 expand due to heat from the molten metal. The thermal expansion coefficient of the protruding member 80 is greater than that of the mold 90. The outer part of the protruding member 80 that is embedded in the mold 90 is covered by the mold 90, so even if thermal expansion occurs, a gap is unlikely to form between the protruding member 80 and the mold 90. On the other hand, although the protruding member 80 does not expand easily outward, there is a cavity inside the protruding member 80. During casting, molten metal flows into the cavity inside the protruding member 80, but the molten metal has not completely solidified. Therefore, during casting, deformation of the internal cavity of the protruding member 80 is permitted in accordance with thermal expansion. In this way, a gap is unlikely to form between the protruding member 80 and the mold 90 during casting, and the mold 90 is less likely to be damaged. As a result, casting defects of the mold 40 caused by cracking of the mold 90 are less likely to occur, and the quality of the molded mold 40 is improved.

[0058] In the embodiment described above, the base portion 81 has an opening 84 connected to the cavity 83. In the mold forming process S40, the protruding member 80 is held against the outer surface 91 of the mold 90 so that the opening 84 is exposed to the outer surface 91 of the mold 90. In the casting process S50, the molten metal flows from the opening 84 exposed to the outer surface 91 of the mold 90 towards the cavity 83. After the molten metal cools, the cavity 83 of the protruding member 80 is filled with the metal constituting the mold 40, as shown in Figure 10. This makes it easier for the protruding member 80 to be firmly held in the mold 40. Also, during the vulcanization molding of the tire, the protruding member 80 becomes less likely to move relative to the mold 40. As a result, the dimensional accuracy of the grooves 102 of the vulcanized tire 100 and the durability of the protruding member can be improved.

[0059] Furthermore, according to the inventors' knowledge, conventionally, when integrating a protruding member with a mold, it was necessary to make a hole in a part of the protruding member, pour molten metal into the hole, and integrate the protruding member with the mold. However, in this case, there was a concern that the mounting strength of the protruding member would decrease if a molding defect occurred when forming the hole. In the above-described embodiment, the protruding member 80 can be held in the mold 40 because the cavity 83 is filled with the metal that constitutes the mold 40. Therefore, there is no need to add a separate structure to the protruding member 80 to hold the protruding member 80 in the mold 40. As a result, concerns about a decrease in the mounting strength of the protruding member 80 to the mold 40 due to molding defects are less likely to occur.

[0060] Furthermore, the inventors have observed that when a solid, metal protruding member is embedded in a mold, it undergoes significant thermal expansion not only in the thickness direction but also in the length direction, as described above. When a protruding member expands in the length direction, the mold is prone to stress near the recess in which the protruding member is embedded. As a result, as described above, the mold may be damaged, and casting defects may occur where molten metal flows into the damaged area. The inventors have considered using the protruding member in segments to suppress thermal expansion in the length direction. Multiple protruding members 80 may be connected along the length direction to suppress thermal expansion in the length direction. When protruding members 80 are connected along the length direction, the ends of the protruding members 80 in the length direction may be provided with protrusions that allow them to be positioned relative to adjacent protruding members. For example, a convex portion may be formed at one end of the protruding member in the length direction, and a corresponding recess may be formed at the other end. This makes it easier to connect and use protruding members 80 of the same shape along the length direction.

[0061] The method for manufacturing the mold is not limited to the embodiments described above. The parts and manufacturing processes used in the manufacture of the mold may be changed in various ways. For example, in the mold forming process S40, a mold may be formed in which a protruding member different from the protruding member 80 is embedded. Figure 11 is a schematic diagram showing the casting process S50 according to another embodiment. Figure 12 is a schematic diagram of the protruding member 180 according to another embodiment. In Figure 12, the protruding member 180 is shown integrated with the mold 140.

[0062] As shown in Figure 11, the protruding member 180 is a plate-shaped member comprising a base portion 181 and a protruding portion 182. The protruding member 180 has a cavity 183 inside the portion that is embedded in the mold 90. Like the protruding member 80, the protruding member 180 may be made of stainless steel, stainless steel alloy, iron, etc. The protruding member 180 does not have an opening that connects to the internal cavity 183. The cavity 183 contains metal powder made of the same type of metal as the protruding member 180. A so-called infill structure is formed in the internal cavity 183 of the protruding member 180.

[0063] As shown in Figure 12, in this embodiment, the cavity 183 inside the protruding member 180 is filled with metal powder 180c made of the same type of metal as the protruding member 180. In this embodiment, the protruding member 180 is provided with a skeleton 180b connecting the inner wall surfaces 180a. The cavity 183 is partitioned in a grid-like cross-section by the same type of metal as the protruding member 180. The dimensions of the partitions, the thickness of the metal partitioning the cavity 183, the filling rate of the metal powder 180c, and other conditions of the grid-like partitioned interior are not particularly limited. The above conditions are set appropriately according to the casting conditions of the target mold 140, the vulcanization conditions when vulcanizing using the mold 140, etc. The partitioning pattern of the cavity 183 is not limited to a grid shape, but may be polygonal, honeycomb, linear, etc. Furthermore, the cavity 183 does not necessarily have to be provided with a skeleton 180b, but providing a skeleton 180b can improve the strength of the protruding member 180.

[0064] Such a protruding member 180 can be formed, for example, by a so-called powder bed method. In this method, a laser is irradiated onto metal powder along the shape of the protruding member 180 and the framework 180b such that a cavity 183 remains inside the protruding member 180. The protruding member 180 is formed by melting and sintering the metal powder and stacking layers.

[0065] The protruding member 180 has a cavity 183 in which an infill structure is formed. Even when a mold 90 with such a protruding member 180 embedded is formed in the mold forming process S40, expansion outward is less likely in the casting process S50, and the expansion is absorbed in the internal cavity. As a result, gaps are less likely to form between the protruding member 180 and the mold 90, and the mold 90 is less likely to be damaged. As a result, casting defects in the mold 40 are less likely to occur, and the quality of the mold 40 is improved.

[0066] The configuration for integrating the protruding member 180 with the mold 140 is not particularly limited. For example, a protruding piece 181b1 may be provided on the base 181 of the protruding member 180, and a hole 181b2 may be formed in the protruding piece 181b1 through which molten metal flows.

[0067] In the embodiment described above, since an infill structure is formed in the cavity 183, when the protruding member 180 is heated by the molten metal in the casting process S50, the protruding member 180 is less likely to undergo thermal expansion. As a result, the load on the mold 90 is less likely to increase, and damage to the mold 90 is less likely to occur. Furthermore, by forming an infill structure in the cavity 183, heat conduction of the protruding member 180 can be suppressed. This allows the heat conduction during the vulcanization molding of the tire at the point where the protruding member 180 makes contact to be adjusted during the manufacturing stage of the mold 140. The heat conduction during vulcanization molding can be adjusted by the dimensions and shape of the cavity 183 compartments, etc.

[0068] In the embodiment described above, the cavity 183 contains metal powder 180c made of the same type of metal as the protruding member 180. This can improve the strength of the protruding member 180. Furthermore, by adjusting the filling ratio of the metal powder 180c, the heat conduction during vulcanization molding can be adjusted, allowing the tire to be vulcanized under appropriate conditions.

[0069] In the embodiment described above, in the protruding member preparation step S30, the protruding members 80 and 180 are formed by metal additive manufacturing. This makes it possible to manufacture parts with complex shapes, such as the protruding member 80 having a protrusion 85 formed on its outer surface, and the protruding member 180 having an infill structure formed in its internal cavity 183.

[0070] The technologies disclosed herein have been described in various ways. However, the technologies disclosed herein are not limited to the embodiments described above unless otherwise specified. Furthermore, the various configurations described can be combined as appropriate, provided that they do not interfere with one another. This specification includes the following disclosures, which are not limited to the embodiments described above.

[0071] The present invention (1) relates to a method for manufacturing a tire vulcanization mold. The method for manufacturing a tire vulcanization mold according to the present invention (1) is: A mold forming process in which a mold is formed in which a protruding member is embedded so as to protrude from the surface, A casting process in which molten metal is poured into the mold and a mold in which the protruding member is integrated is cast. Includes, The protruding member has a cavity in the portion embedded in the mold.

[0072] The present invention (2) is a method for manufacturing a tire vulcanization mold as described in the present invention (1), The protruding member comprises a base that is embedded in the mold when it is integrated with the mold, An opening is formed in the base portion that connects to the cavity. In the mold forming step, the protruding member is held on the surface of the mold such that the opening is exposed on the surface of the mold.

[0073] The present invention (3) is a method for manufacturing a tire vulcanization mold as described in the present invention (1), An infill structure is formed in the aforementioned cavity.

[0074] The present invention (4) is a method for manufacturing a tire vulcanization mold as described in the present invention (3), The cavity contains metal powder made of the same type of metal as the protruding member.

[0075] The present invention (5) is a method for manufacturing a tire vulcanization mold as described in any of the present inventions (1) to (4), The process further includes a step of preparing the protruding member, which is formed by metal additive manufacturing.

[0076] The present invention (6) relates to a tire vulcanization mold. The tire vulcanization mold in the present invention (6) is It is equipped with a protruding member that protrudes from the molding surface that forms the tread portion of the tire, The protruding member has a cavity in the portion that protrudes from the molded surface.

[0077] The present invention (7) is a tire vulcanization mold described in the present invention (6), The protruding member has a base that is embedded inward from the molded surface, An opening is formed in the base portion that connects to the cavity.

[0078] The present invention (8) is a tire vulcanization mold described in the present invention (6), An infill structure is formed in the aforementioned cavity.

[0079] The present invention (9) is a tire vulcanization mold described in the present invention (8), The cavity contains metal powder made of the same type of metal as the protruding member. [Explanation of Symbols]

[0080] 1. Vulcanizing machine for tires 10 Tire vulcanization molds 10a Mold internal space 12,14 mold base 16. Mold opening and closing mechanism 16a Slider 16b Pusher 20, 30, 40 molds 22,32,42 Molding surface 24,34 beading 41 External surface 42 Inner surface (molded surface) 42a Unevenness 60 Bladder center mechanism 62 Centerpost 64, 66 Clamp Rings 68 Brada 70 Master Model 71 Surface 73,74 Recess-forming member 75 type 75a Space 76 Rubber type 76a External surface 76b Inside surface 77,78 recess 80,180 Protruding member 80a 1st page 80b 2nd side 80b1 Projecting piece 80c 1st side 80d Second side 80e 3rd side 81 Base 82 Protrusion 83 Cavity 84 Aperture 85 Protrusion 86 type 86a Space 89 components 90 molds 91 Surface (outer surface) 92 recess Type 95 95a Space 95b Inner surface 100 tires 100a tread surface 101~103 Groove 102a side 102a1 Recess 110 Low Cover 112 Tread section 114 Sidewall section 140 molds 180 Protruding member 180a Interior wall surface 180b Skeleton 180c metal powder 181 Base 181b1 Projecting piece 181b2 hole 182 Protrusion 183 Cavity

Claims

1. A mold forming process in which a mold is formed in which a protruding member is embedded so as to protrude from the surface, A casting process in which molten metal is poured into the mold and a mold in which the protruding member is integrated is cast. Includes, The protruding member has a cavity in the portion embedded in the mold. A method for manufacturing tire vulcanization molds.

2. The protruding member comprises a base that is embedded in the mold when it is integrated with the mold, An opening is formed in the base portion that connects to the cavity. The method for manufacturing a tire vulcanizing mold according to claim 1, wherein in the mold forming step, the protruding member is held on the surface of the mold such that the opening is exposed on the surface of the mold.

3. A method for manufacturing a tire vulcanization mold according to claim 1, wherein an infill structure is formed in the cavity.

4. The method for manufacturing a tire vulcanizing mold according to claim 3, wherein the cavity contains metal powder made of the same type of metal as the protruding member.

5. A method for manufacturing a tire vulcanizing mold according to any one of claims 1 to 4, further comprising a step of preparing a protruding member to form the protruding member by metal additive manufacturing.

6. It is equipped with a protruding member that protrudes from the molding surface that forms the tread portion of the tire, The protruding member has a cavity in the portion that protrudes from the molded surface. Tire vulcanization mold.

7. The protruding member has a base that is embedded inward from the molded surface, The tire vulcanizing mold according to claim 6, wherein an opening is formed in the base portion that connects to the cavity.

8. The tire vulcanizing mold according to claim 6, wherein an infill structure is formed in the cavity.

9. The tire vulcanizing mold according to claim 8, wherein the cavity contains metal powder made of the same type of metal as the protruding member.

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