Method for manufacturing tire vulcanization mold, method for manufacturing tire, and tire

Abstract

To improve the degree of freedom in processing a wear indicator to be applied to a tread part of a tire.SOLUTION: The method for manufacturing the tire vulcanizing mold includes a master model body preparing step S10, an attachment preparing step S20, and a mounting step S30. The master model body 80 has a tread surface 81 in which at least one groove 82 is formed. The groove 82 has a pair of wall surfaces 82a connected from the tread surface 81. A part of the master model body 80 is provided with a depression 83 depressed from the tread surface 81 and the 82a of the wall surface. The attachment 90 has a shape that fits into the recess 83. The attachment 90 includes a first surface 91 continuous with the tread surface 81, and a second surface 92 continuous with the 82a of the wall surface. A wear indicator 103a1 corresponding to the wear indicator 92a of the tire 100 is formed on the second surface 92.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a tire vulcanizing mold, a method for manufacturing a tire, and a tire. [Background technology]

[0002] JP 2015-502275 A discloses a molding element for a mold for vulcanizing a tire tread. The molding element has a base and a rib. The base is a portion for molding a portion of the tread surface of the tread. The rib is a portion for molding grooves in the tread. The rib has two longitudinal faces protruding from the base and an upper face connecting the longitudinal faces to each other. The molding element has a contact edge formed by the base and the rib. The contact edge contacts another molding element to form all or part of the vulcanization mold. The rib has a recess. The recess is open on the upper face and the contact edge. The recess is not open on the longitudinal face of the rib. A mold composed of such a molding element is said to have improved mechanical strength while optimizing manufacturing costs.

[0003] Japanese Patent Publication No. 5746159 discloses a tire vulcanization mold having a tread-forming element. The tread-forming element has a protrusion extending along the inner surface of the tread-forming element for forming a groove in the tread. The vulcanization mold has an insert member that can be inserted into a receiving portion formed in the tread-forming element. The insert member forms a part of the protrusion by being inserted into the receiving portion. Inserting the insert member into the receiving portion forms a slot that opens into the space inside the mold. The slot is oriented perpendicular to the protrusion. The slot is configured to form a flexible wall with a reduced thickness that is integral with at least one wall of the groove formed by the protrusion. This is said to solve the problem of gypsum becoming excessively brittle when forming the slot. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-502275 [Patent Document 2] Patent No. 5746159 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors wish to improve the degree of freedom in processing wear indicators that are applied to the tread portion of a tire. [Means for solving the problem]

[0006] The method for manufacturing a tire curing mold disclosed herein includes a master model body preparing step, an attachment preparing step, and an attachment step. The master model body has a tread surface in which at least one groove is formed. The groove has a pair of wall surfaces connected to the tread surface. A recess recessed from the tread surface and wall surface is provided in a portion of the master model body. The attachment has a shape that fits into the recess. The attachment has a first surface that is continuous with the tread surface and a second surface that is continuous with the wall surface. A wear indicator portion corresponding to the tire wear indicator is formed on the second surface. [Effects of the Invention]

[0007] This manufacturing method improves the degree of freedom in processing when attaching a wear indicator to the trend portion of the tire. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a tire vulcanizer 1. As shown in FIG. [Figure 2] FIG. 2 is a flowchart showing a method for manufacturing a tire vulcanizing mold. [Figure 3] FIG. 3 is a schematic diagram of the master model 70. [Figure 4] FIG. 4 is a schematic diagram of the master model body 80 and the attachment 90. [Figure 5] FIG. 5 is a schematic diagram showing the rubber mold forming step S40. [Figure 6] FIG. 6 is a schematic diagram showing the template formation step S50. [Figure 7] FIG. 7 is a schematic diagram showing the tread mold forming step S60. [Figure 8] FIG. 8 is a schematic diagram showing the wear indicator 103a1 of the tire 100. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiment. Each drawing is a schematic representation and does not necessarily reflect the actual product. Furthermore, each drawing shows only an example and does not limit the present invention unless otherwise specified. Furthermore, members and parts that perform the same function are appropriately designated by the same reference numerals, and redundant explanations will be omitted.

[0010] <Tire vulcanizer 1> Fig. 1 is a schematic diagram of a tire vulcanizer 1. Fig. 1 shows a schematic cross section of the tire vulcanizer 1 during vulcanization of a raw cover 110. In Fig. 1, hatching of the raw cover 110 and the bladder 68 is omitted.

[0011] As shown in Fig. 1, the tire vulcanizer 1 includes a tire vulcanizing mold 10 and a bladder center mechanism 60. The bladder center mechanism 60 includes a bladder 68 disposed at the center of the tire vulcanizer 1. In the tire vulcanizer 1, a raw cover 110 supported by the bladder 68 is pressed against the tire vulcanizing mold 10 and vulcanized to form a tire.

[0012] <Low Cover 110> The raw cover 110 is an unvulcanized tire before vulcanization and is also called a green tire. Although not shown, the raw cover 110 is a tubular member in which unvulcanized sidewall rubber and tread rubber are bonded to a base material such as a bead wire, carcass, or belt. The raw cover 110 has a tread portion 112 and a sidewall portion 114. The tread portion 112 is the portion that forms the surface of the tire that comes into contact with the road after vulcanization. The sidewall portion 114 is the portion that forms the side surface of the tire after vulcanization.

[0013] <Tire curing mold 10> The tire vulcanizing mold 10 includes a plurality of segments 20, 30, 40. The plurality of segments 20, 30, 40 are arranged in a toroidal shape so as to surround the bladder 68. The tire vulcanizing mold 10 includes a plurality of segments 20, 30, 40 arranged around the bladder 68. The material of the tire vulcanizing mold 10 may be a metal such as aluminum or an aluminum alloy. The material of the tire vulcanizing mold 10 is not particularly limited.

[0014] When the tire is vulcanized, the segments 20, 30, and 40 are heated by a heater (not shown). The segments 20, 30, and 40 have molding surfaces 22, 32, and 42 that form the outer shape of the tire. When the tire is vulcanized, the molding surfaces 22, 32, and 42 of the segments 20, 30, and 40 become continuous, forming an in-mold space 10a. The raw cover 110 is heated and pressurized while pressed against the molding surfaces 22, 32, and 42 in the in-mold space 10a, and is vulcanized and molded.

[0015] The molding surfaces 22, 32, 42 of the segments 20, 30, 40 are provided with protrusions and recesses that correspond to the desired outer shape of the tire. For example, the molding surfaces 22, 32 of the segments 20, 30 may be provided with protrusions and recesses for displaying tire information on the tire sidewall. The molding surface 42 of the segment 40 is provided with protrusions and recesses for forming a tread pattern, wear indicator, or the like in accordance with the desired function in the tire tread.

[0016] <Segments 20 and 30> The segments 20 and 30 are also called side molds. The sidewall portion 114 of the raw cover 110 is pressed against the molding surfaces 22 and 32 of the segments 20 and 30. This causes the sidewall portion of the tire to be vulcanized and molded. The segment 40 is also called a tread mold. The tread portion 112 of the raw cover 110 is pressed against the molding surface 42 of the segment 40. This causes the tread portion of the tire to be vulcanized and molded.

[0017] The segment 20 is annular. The segment 20 is provided below the tire vulcanizing mold 10. The segment 20 is attached to a mold base 12. The mold base 12 is attached to, for example, a press table (not shown). The segment 20 is provided with a bead ring 24 that holds the bead portion of the raw cover 110.

[0018] Like segment 20, segment 30 is annular. Segment 30 is provided above the tire curing mold 10. Segment 30 faces segment 20 in the up-down direction. Segment 30 is attached to a mold base 14. In this embodiment, the mold base 14 is attached to a press machine and is configured to be movable up and down. Segment 30 is provided with a bead ring 34 that holds the bead portion of the raw cover 110. Segments 20 and 30 may be composed of multiple mold components.

[0019] Segment 40 The segment 40 is a mold component that molds the tread portion of the tire. The molding surface 42 of the segment 40 is the surface that molds the tread portion of the tire. The molding surface 42 is provided with protrusions 42a that form depressions such as grooves, sipes, and slits on the tread surface of the tire. The tire vulcanizing mold 10 is provided with a plurality of segments 40 that are divided along the circumferential direction. The plurality of segments 40 are arranged at predetermined intervals in the circumferential direction.

[0020] The multiple segments 40 are driven radially inward and outward by the mold opening / closing mechanism 16. The mold opening / closing mechanism 16 includes a slider 16a to which the segments 40 are attached, and a pusher 16b that is driven vertically. The outer surface of the slider 16a is formed with an inclined surface that widens outward as it extends downward. The pusher 16b is formed with an inclined surface that widens outward as it extends downward, facing the inclined surface of the slider 16a. When the inclined surface of the pusher 16b comes into contact with the inclined surface of the slider 16a, the slider 16a moves inward and outward. This causes the segments 40 to open and close radially.

[0021] Although not shown in the figures, before the tire is vulcanized, the segments 40 are arranged radially outward, separated from adjacent segments 40. At this time, the segments 30 are held above the raw cover 110. When the tire is vulcanized, the segments 40 move radially inward. The multiple segments 40 are continuous in the circumferential direction. At the same time, the segments 30 held above the raw cover 110 move downward. This closes the tire vulcanization mold 10, and the segments 20, 30, and 40 become continuous. When the tire is vulcanized, with the tire vulcanization mold 10 closed, the raw cover 110 supported by the bladder 68 is pressed against the molding surfaces 22, 32, and 42 of the segments 20, 30, and 40.

[0022] <Bladder center mechanism 60> The bladder center mechanism 60 includes a center post 62 , clamp rings 64 and 66 , and a bladder 68 .

[0023] The bladder 68 is provided in the mold space 10a. The bladder 68 is a member that is pressed against the inner surface of the raw cover 110. The bladder 68 is a cylindrical elastic body made of rubber. As the bladder 68 expands, the raw cover 110 is pressed against the molding surfaces 22, 32, 42 of the segments 20, 30, 40, and the outer shape of the tire is formed. The bladder 68 is disposed in the center between the segments 20, 30 that face each other in the vertical direction. The bladder 68 is held with the center post 62 as its central axis.

[0024] The center post 62 is an axial member extending in the direction in which the segments 20, 30 face each other. The center post 62 penetrates the center of the segment 20 that forms the lower sidewall portion 114. A pair of clamp rings 64, 66 facing each other are attached to the center post 62.

[0025] The clamp ring 66 is a disk-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, the clamp ring 66 may be, for example, a member that can be separated into upper and lower halves and has a structure that sandwiches and holds the peripheral edge portion on the upper end side of the bladder 68. The clamp ring 64 is a disk-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.

[0026] A fluid (water vapor, nitrogen, etc.) is supplied from a fluid supply device (not shown) to the space surrounded by the clamp rings 64, 66 and the bladder 68. Heat and pressure are applied from the inside to the raw cover 110 in the mold space 10a of the tire vulcanizing mold 10. As a result, the raw cover 110 is heated while being pressed against the tire vulcanizing mold 10, and the tire is vulcanized and molded.

[0027] Hereinafter, a method for manufacturing the tire vulcanizing mold 10 used in the tire vulcanizer 1 will be described using a method for manufacturing the tread mold 40 as an example.

[0028] <Method for manufacturing tire vulcanization mold> Fig. 2 is a flowchart showing a method for manufacturing a tire vulcanizing mold. Fig. 3 is a schematic diagram of a master model 70. Fig. 4 is a schematic diagram of a master model main body 80 and an attachment 90. Fig. 5 is a schematic diagram showing a rubber mold forming step S40. Fig. 6 is a schematic diagram showing a casting mold forming step S50. Fig. 7 is a schematic diagram showing a tread mold forming step S60.

[0029] 2, the manufacturing method for a tire vulcanizing mold includes a master model body preparing step S10, an attachment preparing step S20, an attachment step S30, a rubber mold forming step S40, a casting mold forming step S50, and a tread mold forming step S60. In the manufacturing method for a tire vulcanizing mold, a master model 70 is used to manufacture the tire vulcanizing mold.

[0030] <Master model body preparation process S10> In the master model body preparation step S10, a master model body 80 is prepared. As shown in FIG. 3, the master model body 80 has a shape corresponding to the shape of a tire divided circumferentially (for example, into 4 to 12 parts). The master model body 80 corresponds to the surface shape of the tire, except for recesses 83 to which attachments 90 are attached. The master model body 80 can be formed from chemical wood. The master model body 80 is formed by cutting the chemical wood or the like. By processing the chemical wood, a master model body 80 having a desired shape can be prepared.

[0031] The master model main body 80 has a tread surface 81. The tread surface 81 corresponds to the surface shape of the tread portion of the target tire. At least one groove 82 is formed in the tread surface 81. In this embodiment, four grooves 82 are formed in the tread surface 81. The grooves 82 correspond to grooves (main grooves) in the tread portion of the tire. The grooves 82 are formed along the circumferential direction of the tire. The grooves 82 are approximately trapezoidal in a cross-sectional view perpendicular to the direction in which the grooves 82 extend.

[0032] The groove 82 in the tread surface 81 has a pair of wall surfaces 82a and a bottom surface 82b. The pair of wall surfaces 82a are each connected to the tread surface 81. The wall surfaces 82a are inclined from the tread surface 81 toward the bottom surface 82b at a required angle. The wall surfaces 82a may be perpendicular to the tread surface 81. The bottom surface 82b connects the pair of wall surfaces 82a. The bottom surface 82b constitutes the deepest portion of the groove 82 formed in the tread surface 81. The wall surfaces 82a and the bottom surface 82b may be connected via a gently curved R (see FIG. 4). The bottom surface 82b relative to the tread surface 81 has a substantially constant depth along the direction in which the groove 82 extends (in this embodiment, the circumferential direction).

[0033] The grooves 82 do not necessarily have to be formed along the circumferential direction of the tire. The grooves 82 may be formed along the width direction of the tire (a direction perpendicular to the circumferential direction), or may be formed at an angle relative to the circumferential and width directions of the tire. The grooves 82 may be configured with multiple patterns of grooves along different directions.

[0034] Grooves 84 are formed in the tread surface 81, inclined relative to the grooves 82. The grooves 84 are narrower than the grooves 82. The grooves 84 may correspond to tire grooves also known as sipes, slits, etc. The grooves 84 have a generally rectangular shape with a depth dimension greater than a width dimension in a cross-sectional view perpendicular to the direction in which the grooves 84 extend. The grooves 84 do not necessarily have to be provided.

[0035] The grooves 82, 84 may correspond to the surface pattern of the tread portion of the tire, also called the tread pattern. The grooves 82, 84 may also function as air passages when forming a rubber mold.

[0036] As shown in FIG. 4, a portion of the master model main body 80 has a recess 83 recessed from the tread surface 81 and wall surface 82a. The recess 83 is formed in a portion of the master model main body 80 where the groove 82 is formed. The recess 83 is recessed in the depth direction from the tread surface 81 and is recessed from the wall surface 82a of the groove 82 along the width direction of the groove 82. The recess 83 has a substantially rectangular parallelepiped shape with rounded corners 83a. The recess 83 includes a bottom surface 83b, a back surface 83c, and a pair of side surfaces 83d. The bottom surface 83b is substantially parallel to the bottom surface 82b of the groove 82. The back surface 83c is substantially parallel to the wall surface 82a of the groove 82. The pair of side surfaces 83d are inclined at an angle less than 90 degrees with respect to the extension direction of the groove 82. This makes it easier to attach the attachment 90.

[0037] <Attachment preparation process S20> In the attachment preparation step S20, an attachment 90 to be attached to the master model main body 80 is prepared. The attachment 90 has a shape that fits into the recess 83. In this embodiment, the attachment 90 is made of chemical wood, just like the master model main body 80. The attachment 90 is formed by cutting the chemical wood. This allows the attachment 90 to have a desired outer shape and surface shape.

[0038] The attachment 90 has an outer shape that corresponds to the recess 83 of the master model main body 80. The attachment 90 is a roughly rectangular parallelepiped with rounded corners 93a. The attachment 90 has a surface 93 that fits into the recess 83. The surface 93 that fits into the recess 83 includes a bottom surface 93b, a back surface 93c, and a pair of side surfaces 93d. The bottom surface 93b of the attachment 90 corresponds to the bottom surface 83b of the recess 83. The back surface 93c of the attachment 90 corresponds to the back surface 83c of the recess 83. The pair of side surfaces 93d of the attachment 90 correspond to the pair of side surfaces 83d of the recess 83.

[0039] The thickness of the attachment 90 (the dimension along the width direction of the groove 82) can be set to 2 mm or more from the viewpoint of component strength. Furthermore, the attachment 90 can be set to a dimension slightly smaller than the recess 83 so that it can easily fit into the recess 83 of the master model main body 80. From this viewpoint, the dimensional difference between the attachment 90 and the recess 83 in the width direction and the extension direction of the groove 82 can be set to 0.01 mm or more. However, the dimensional difference between the attachment 90 and the recess 83 can be set not too large so as to prevent the rubber from flowing in when forming the rubber mold, as described below. From this viewpoint, the dimensional difference between the attachment 90 and the recess 83 can be set to 0.05 mm or less. The dimensional difference between the attachment 90 and the recess 83 can be set to 0.02 mm or more and 0.04 mm or less. In this embodiment, the dimensional difference between the attachment 90 and the recess 83 is set to 0.03 mm. By setting such a dimensional difference, the positional accuracy of the attachment 90 relative to the master model body 80 is excellent.

[0040] The attachment 90 has a surface that is continuous with the surface of the master model main body 80 when fitted into the recess 83. The attachment 90 has a first surface 91 and a second surface 92. The first surface 91 is continuous with the tread surface 81. The first surface 91 forms approximately the same plane as the tread surface 81 in the master model 70. The first surface 91, together with the tread surface 81 of the master model main body 80, forms the tread surface of the master model 70. The second surface 92 is continuous with the wall surface 82a of the groove 82. The second surface 92 forms approximately the same plane as the wall surface 82a in the master model 70. The first surface 91 may be provided with grooves corresponding to the tread pattern of the tire. The second surface 92 is formed with a wear indicator portion 92a corresponding to a tire indicator. The indicator is a sign that indicates the wear limit of the tread portion of the tire and may be provided in the grooves of the tread portion of the tire. The wear indicator portion 92a is provided approximately 2 mm away from the boundary between the master model body 80 and the attachment 90.

[0041] As shown in FIG. 4, the wear indicator portion 92a is formed in multiple stages (four stages in this embodiment) along the depth direction of the groove 82. The wear indicator portion 92a includes a line 92a1 and a life indicator 92a2. The lines 92a1 are arranged at equal intervals along the extension direction of the groove 82, dividing the bottom surface 82b of the groove 82 from the tread surface 81 into four parts. The four stages of the wear indicator portion 92a make it easier to determine when to rotate the tire. The line 92a1 becomes shorter as it extends in the depth direction. The life indicator 92a2 is provided next to the line 92a1 and is indicated by the numbers 75, 50, and 25 from top to bottom. These numbers may correspond to the percentage of the groove remaining until the tread portion reaches its wear limit depending on tire use. The configuration of the wear indicator portion 92a is not particularly limited. The wear indicator portion 92a may be just a line, just a life indicator, or another pattern.

[0042] In this embodiment, the wear indicator portion 92a is a protrusion that protrudes from the second surface 92. The height of the wear indicator portion 92a may be set to 0.3 mm or more from the perspective of visibility during tire manufacturing. The height of the wear indicator portion 92a may be set to less than 0.6 mm from the perspective of ensuring strength during the manufacturing process of the tread mold 40. The wear indicator portion 92a may also be a recess that is recessed into the second surface 92.

[0043] In this embodiment, the second surface 92, on which the wear indicator portion 92a is formed, is formed by cutting the surface of the attachment 90 made from chemical wood. Forming the wear indicator portion 92a by cutting the chemical wood allows for good surface workability. This makes it easy to form the desired wear indicator portion 92a on the second surface 92. Furthermore, when processing the wear indicator portion 92a into a convex portion, it is easy to form a convex portion with good strength. Note that in trials conducted by the inventors, the shape of the wear indicator portion 92a was more precise in the attachment 90 made from chemical wood than in attachments formed by resin molding, and transfer failures were less likely to occur.

[0044] <Installation process S30> In the attachment step S30, the attachment 90 is attached to the master model main body 80. Here, the attachment 90 is attached to the master model main body 80 in a state where a surface 93 of the attachment 90 excluding a first surface 91 and a second surface 92 is positioned to fit into the recess 83. The method for attaching the attachment 90 to the master model main body 80 is not particularly limited, and the attachment may be attached using an adhesive or a mounting member such as a bolt.

[0045] <Rubber mold forming process S40> In the rubber mold forming step S40, a rubber mold 72 is formed from the master model 70 to which the attachment 90 is attached. The rubber mold 72 is formed, for example, by the following method.

[0046] As shown in FIG. 5 , the master model 70 is placed in a mold 71 for molding the rubber mold 72. A space 71a for filling with rubber is formed between the master model 70 and the mold 71. Rubber (e.g., silicone rubber) is filled into the space 71a and the rubber is cured. This forms the rubber mold 72. The outer surface 72a of the rubber mold 72 is molded by the mold 71. The inner surface 72b of the rubber mold 72 is formed by the master model 70. The inner surface 72b of the rubber mold 72 has an inverted shape of the tread surfaces 81, 91 of the master model 70. A portion 72b1 of the inner surface 72b of the rubber mold 72 against which the wear indicator portion 92a is pressed forms an inverted shape of the wear indicator portion 92a (in this embodiment, a recess). After the rubber mold 72 is formed, the rubber mold 72 is removed from the mold 71.

[0047] <Mold forming step S50> In the mold formation step S50, a mold 74 is formed from the rubber mold 72. The mold 74 is formed, for example, by the following method.

[0048] As shown in FIG. 6 , the rubber mold 72 is placed in a mold 73 for forming a casting mold 74. Here, the outer surface 72a of the rubber mold 72 is placed in the mold 73. A space 73a into which plaster is poured is formed between the rubber mold 72 and the mold 73. The plaster is poured into the space 73a and allowed to harden. This forms the casting mold 74. The outer surface 74a of the casting mold 74 is formed by the inner surface 72b of the rubber mold 72. The outer surface 74a of the casting mold 74 has an inverted shape of the outer surface 72a of the rubber mold 72. Therefore, a shape (a convex portion in this embodiment) corresponding to the wear indicator portion 92a is formed in the portion 74a1 of the outer surface 74a of the casting mold 74 against which the portion 72b1 of the rubber mold 72 is pressed. After the casting mold 74 is formed, the casting mold 74 is removed from the mold 73.

[0049] <Tread mold forming process S60> In the tread mold forming step S60, the tread mold 40 is formed from the casting mold 74. The tread mold 40 is formed, for example, by the following method.

[0050] As shown in FIG. 7 , the casting mold 74 is placed in a mold 75 for molding the tread mold 40. A space 75a into which molten metal is poured is formed between the casting molds 74 and 75. Molten metal (for example, molten aluminum) is poured into the space 75a. The molten metal is cooled and solidified. This forms the tread mold 40. The outer surface 41 of the tread mold 40 is formed by the inner surface 75b of the mold 75. The inner surface (molding surface) 42 of the tread mold 40 is formed by the outer surface 74a of the casting mold 74. The molding surface 42 of the tread mold 40 has an inverted shape of the outer surface 74a of the casting mold 74. Therefore, ridges 42a are formed on the molding surface 22 of the tread mold 40, and a shape (a recess in this embodiment) that is an inverted version of the wear indicator portion 92a is formed on the wall surface 42a1 of the ridges 42a.

[0051] A tire may be provided with a wear indicator that indicates the wear limit of the tread portion. The wear indicator may be provided in a groove in the tread portion. When a tire curing mold is manufactured using a master model and a tire is cured and molded using the tire curing mold, it is necessary to form a shape corresponding to the wear indicator in the master model. According to the inventor's findings, the workability when forming a shape corresponding to the wear indicator in the groove of the master model was not good. For this reason, it was not possible to freely form a shape corresponding to the wear indicator in the master model. For example, it was difficult to form a shape for processing a wear indicator in the wall surface of the groove of the master model.

[0052] In the embodiment described above, the manufacturing method for a tire curing mold includes a master model main body preparation step S10, an attachment preparation step S20, and an attachment step S30 (see FIG. 2). As shown in FIGS. 3 and 4, the master model main body 80 has a tread surface 81 in which at least one groove 82 is formed. The groove 82 has a pair of wall surfaces 82a connected to the tread surface 81. A recess 83 recessed from the tread surface 81 and the wall surface 82a is provided in a portion of the master model main body 80. The attachment 90 has a shape that fits into the recess 83. The attachment 90 has a first surface 91 that is continuous with the tread surface 81 and a second surface 92 that is continuous with the wall surface 82a. The second surface 92 is formed with a wear indicator portion 92a that corresponds to the tire wear indicator. In this manufacturing method, the attachment 90 is separately prepared and attached to the master model main body 80. The attachment 90 is attached to the master model main body 80 after being processed as desired. This increases the degree of freedom in the wear indicator portion 92a that is applied to the wall surface 82a of the groove 82 of the master model 70. As a result, the degree of freedom in the wear indicator that is applied to the tire increases.

[0053] The tread mold 40 manufactured by the above method can be used to manufacture the tire 100. By using such a tread mold 40 to vulcanize and mold the tire 100, the tire 100 having a tread portion 102 corresponding to the tread surfaces 81, 91 of the master model 70 is manufactured.

[0054] FIG. 8 is a schematic diagram showing a wear indicator 103a1 of a tire 100. As shown in FIG. 8, the tire 100, which is vulcanized using the tread mold 40 (see FIG. 7), has a tread portion 102 and a groove 103 formed in the tread portion 102. At least one groove 103 (four in this embodiment) is formed. The groove 103 has a wall surface 103a that connects to the tread surface 102a of the tread portion 102, and a bottom surface 103b that continues from the wall surface 103a. A wear indicator 103a1 is provided on the wall surface 103a.

[0055] According to the inventor's knowledge, it has not been possible to freely form a shape corresponding to a wear indicator on a master model. It has been particularly difficult to provide a wear indicator that protrudes from the wall surface of a tire groove. In the above-described embodiment, the wear indicator portion 92a is a protrusion that protrudes from the second surface 92. As a result, the wear indicator 103a1 provided on the tire 100 has a shape that protrudes from the wall surface 103a of the groove 103 in the tread portion 102. This configuration allows a highly visible wear indicator 103a1 to be provided on the wall surface 103a of the groove 103.

[0056] There are no particular limitations on the height (amount of protrusion) of the wear indicator portion 92a protruding from the second surface 92. From the standpoints of visibility and ease of processing, the height of the wear indicator portion 92a relative to the second surface 92 is preferably 0.3 mm to 0.6 mm.

[0057] The technology disclosed herein has been described in various ways. However, the technology disclosed herein is not limited to the above-described embodiments unless otherwise specified. Furthermore, the configurations of the various described embodiments can be combined as appropriate as long as they do not interfere with each other. This specification includes the following disclosure, but the following disclosure is not limited to the above-described embodiments.

[0058] The present invention (1) relates to a method for manufacturing a tire vulcanizing mold. The method for manufacturing a tire vulcanizing mold in the present invention (1) includes the following steps: a master model body preparation step of preparing a master model body; an attachment preparation step of preparing an attachment to be attached to the master model body; an attachment step of attaching the attachment to the master model body; Including, The master model body has a tread surface on which at least one groove is formed, The groove has a pair of wall surfaces that are connected to the tread surface, a recess recessed from the tread surface and the wall surface is provided in a portion of the master model body, The attachment is The recess has a shape that fits into the recess, A first surface continuous with the tread surface and a second surface continuous with the wall surface, The second surface is formed with a wear indicator portion that corresponds to a wear indicator of the tire.

[0059] The present invention (2) is a method for manufacturing the tire vulcanizing mold according to the present invention (1), The attachment is made of chemical wood, The attachment preparing step includes forming the second surface on which the wear indicator portion is formed by cutting the surface of the attachment.

[0060] The present invention (3) is a method for manufacturing a tire vulcanizing mold according to the present invention (1) or (2), The wear indicator portion is a protrusion that protrudes from the second surface.

[0061] The present invention (4) is a method for manufacturing a tire vulcanizing mold according to any one of the present inventions (1) to (3), The difference in size between the recess and the attachment is 0.05 mm or less.

[0062] The present invention (5) relates to a method for manufacturing a tire. The tire manufacturing method in the present invention (5) includes a step of vulcanizing and molding a tire using a tire vulcanizing mold manufactured by the method for manufacturing a tire vulcanizing mold described in any one of the present inventions (1) to (4).

[0063] The present invention (6) relates to a tire. The tire in the present invention (6) is A tread portion; At least one groove formed in the tread portion; Equipped with The groove has a wall surface that is connected to a tread surface of the tread portion, A wear indicator is provided on the wall surface. [Explanation of symbols]

[0064] 1. Tire vulcanizer 10 Tire curing mold 10a Mold space 12,14 Mold base 16 Mold opening and closing mechanism 16a slider 16b Pusher 20, 30, 40 segments 22,32,42 Molding surface 24,34 bead ring 40 Tread mold 41 External surface 42a Projection 42a1 Wall 60 Bladder center mechanism 62 Center Post 64,66 Clamp ring 68 Brada 70 Master Model 71, 73, 75 types 71a,73a,75a space 72 Rubber mold 72a,74a outer surface 72b,75b Inside surface 72b1,74a1 part 74 Mold 80 Master Model body 81,91 Tread surface 82,84 groove 82a Wall 82b Bottom 83 Depression 83a Corner 83b Bottom 83c back 83d side 90 Attachment 91 1st surface (tread surface) 92 Side 2 92a Wear indicator section 92a1 line 92a2 Life 93 sides 93a Corner 93b Bottom 93c back 93d side 100 tires 102 Tread 102a Tread surface 103 Groove 103a Wall 103a1 Wear Indicator 103b Bottom 110 Low Cover 112 Tread 114 Sidewall

Claims

1. a master model body preparation step of preparing a master model body; an attachment preparation step of preparing an attachment to be attached to the master model body; an attachment step of attaching the attachment to the master model body; Including, The master model body has a tread surface on which at least one groove is formed, The groove has a pair of wall surfaces that are connected to the tread surface, a recess recessed from the tread surface and the wall surface is provided in a portion of the master model body, The attachment is The recess has a shape that fits into the recess, a first surface continuous with the tread surface and a second surface continuous with the wall surface, The second surface is formed with a wear indicator portion corresponding to a tire wear indicator. A method for manufacturing tire vulcanization molds.

2. The attachment is made of chemical wood, 2. The method for manufacturing a tire vulcanizing mold according to claim 1, wherein the attachment preparing step includes forming the second surface on which the wear indicator portion is formed by cutting the surface of the attachment.

3. 3. The method for manufacturing a tire vulcanizing mold according to claim 1, wherein the wear indicator portion is a protrusion protruding from the second surface.

4. 3. The method for manufacturing a tire vulcanizing mold according to claim 1, wherein a difference in size between the recess and the attachment is 0.05 mm or less.

5. A method for manufacturing a tire, comprising a step of vulcanizing and molding a tire using a tire vulcanizing mold manufactured by the method for manufacturing a tire vulcanizing mold according to claim 1 or 2.

6. A tread portion; At least one groove formed in the tread portion; Equipped with The groove has a wall surface that is connected to a tread surface of the tread portion, A wear indicator is provided on the wall surface. tire.

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