Mold for tires and tire manufacturing method

Abstract

To provide a mold for tires 4 capable of suppressing damage to a blade for meshing a sipe.SOLUTION: A mold 4 is provided with a tread ring 14 for forming a tread part 40 of a tire 10. An inner peripheral surface of the tread ring 14 is provided with a tread molding surface 36. The tread molding surface 36 is provided with a plurality of circumferential protrusions 62 and a plurality of transverse blades 70. The tread ring 14 is provided with a plurality of parting planes 24 traversing the tread molding surface 36. A plurality of parting planes 24 divides the tread ring 14 into a plurality of segments 20. The number of segments 20 included in the tread ring 14 is 17 or over. The parting planes 24 include a plurality of straight lines SL arranged in the axial direction and a plurality of arcs AC connecting adjacent two straight lines SL. The parting planes 24 do not intersect the transverse blades 70.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a tire mold and a tire manufacturing method. More specifically, the present invention relates to a mold for a tire having a large number of sipes cut into the tread portion and a tire manufacturing method using the mold. [Background technology]

[0002] Tires are formed using a mold. The mold has a tread ring that forms the tread portion. In a split mold type mold, the tread ring has multiple segments. Each segment has a mating surface that comes into close contact with the adjacent segment. The part of the tread ring where the segments come into close contact with each other is the dividing surface. The dividing surface is formed by the mating surfaces of adjacent segments coming into close contact with each other.

[0003] A large number of sipes extending in the approximately axial direction are carved into the tread portion of tires such as studless tires and snow tires, more specifically, into a large number of blocks provided in the tread portion. To carve these lateral sipes, the segments have a large number of lateral blades protruding inward. The groove width of the lateral sipes is extremely narrow. Therefore, the lateral blades are made of extremely thin blades.

[0004] When the mold is opened, the segments move entirely outward along the tire radial direction, and therefore, among the lateral blades of the segments, there are normal blades that extend in a direction generally coinciding with the movement direction of the segments, and unique blades that extend at an angle to the movement direction of the segments.

[0005] When a tire is removed from a mold, a force greater than that acting on a normal blade acts on the special blade. Therefore, the special blade is prone to damage such as breakage or bending. There is a concern that such damage will impair the quality of the tire. Therefore, in order to stably manufacture high-quality tires, a mold that is less likely to cause damage to the lateral blades is required. For example, in the following Patent Document 1, it is considered to suppress damage to the lateral blades by increasing the number of segments included in the tread ring. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-62547 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a tire mold that can suppress damage to a blade used to cut sipes. [Means for solving the problem]

[0008] The tire mold according to the present invention is a mold for forming a tire having a tread portion, the tread portion having a tread pattern including a plurality of circumferential grooves arranged in an axial direction and a plurality of lateral sipes arranged in a circumferential direction, a plurality of land portions formed in the tread portion by the plurality of circumferential grooves, a plurality of the lateral sipes being engraved in each land portion, an angle formed by each of the lateral sipes with respect to the circumferential direction being 20 degrees or more, and a straight line extending in an axial direction on the outer surface of the tread portion intersects with at least one lateral sipe, or if the straight line does not intersect with the lateral sipe, passes through a position where the distance to the lateral sipe is less than 1.5 mm. The mold includes a tread ring for forming the tread portion. The inner peripheral surface of the tread ring includes a tread molding surface for forming the tread pattern in the tread portion. The tread molding surface includes a plurality of circumferential protrusions for forming the plurality of circumferential grooves and a plurality of lateral blades for forming the plurality of lateral sipes. The tread ring has a plurality of dividing surfaces that cross the tread molding surface. The dividing surfaces divide the tread ring into a plurality of segments. The number of the segments included in the tread ring is 17 or more. In a development view of the tread molding surface, the dividing surface includes a plurality of straight lines arranged in the axial direction and a plurality of circular arcs connecting two adjacent straight lines. Of the plurality of straight lines, two straight lines located at the outermost positions in the axial direction are each a reference straight line extending substantially parallel to the axial direction. The dividing surface does not intersect with the lateral blades.

[0009] The method for manufacturing a tire according to the present invention includes a step of pressurizing and heating a green tire in a mold, the mold being the above-described mold. Effect of the Invention

[0010] According to the present invention, a tire mold can be obtained that can suppress damage to a blade used for cutting sipes. This mold can contribute to the stable production of high-quality tires. [Brief description of the drawings]

[0011] [Figure 1]FIG. 2 is a cross-sectional view showing a portion of a vulcanizer incorporating a tire mold. [Diagram 2] FIG. 4 is a plan view illustrating opening and closing of a mold. [Diagram 3] FIG. 2 is a development view showing a part of the outer circumferential surface of the tread portion. [Figure 4] FIG. 2 is a development view showing a portion of the tread molding surface of the mold. [Diagram 5] FIG. 4 is a plan view showing the relationship between the arrangement of segments and the arrangement of pitch elements. [Figure 6] FIG. 4 is a development view showing an example of a division surface. [Figure 7] FIG. 13 is a development view showing a modified example of the dividing surface. [Figure 8] FIG. 13 is a development view showing another modified example of the dividing surface. [Figure 9] FIG. 7 is a development view showing a part of the division surface shown in FIG. 6. [Figure 10] FIG. 7 is a development showing the division surface shown in FIG. 6. [Figure 11] FIG. 2 is a perspective view showing an example of a horizontal blade. [Figure 12] FIG. 11 is a cross-sectional view showing a modified example of a horizontal blade. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In the present invention, a state in which a tire is mounted on a standard rim, the internal pressure of the tire is adjusted to a standard internal pressure, and no load is applied to the tire is referred to as a standard state.

[0013] A genuine rim is a rim that is specified in the standard on which the tire is based. The "standard rim" in the JATMA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are genuine rims.

[0014] Normal tire pressure means the internal pressure specified in the standard on which the tire is based. The "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are normal tire pressures.

[0015] Normal load refers to the load specified in the standard on which the tire is based. The "maximum load capacity" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard are normal loads.

[0016] In the present invention, the tread portion of a tire is the portion of the tire that comes into contact with the road surface. The bead portion is the portion of the tire that fits onto the rim. The sidewall portion is the portion of the tire that bridges between the tread portion and the bead portion. A tire has the following portions: a tread portion, a pair of bead portions, and a pair of sidewall portions.

[0017] [Foundations underlying the present invention] As described above, the tread ring has a plurality of split surfaces. The split surfaces cross the tread ring. Depending on the position of the split surfaces, the split surfaces may split the transverse blades. As described above, the transverse blades are extremely thin. If the transverse blades are split by the split surfaces, the strength of the transverse blade as a whole is reduced. In this case, the risk of damage to the transverse blades increases. It is possible to reduce the risk of damage by increasing the strength of the lateral blades by making them thicker or reducing their protruding height. However, if thick lateral blades are used, lateral sipes with a wide groove width are formed. If lateral blades with a low protruding height are used, shallow lateral sipes are formed. In either case, the rigidity of the block is affected. As mentioned above, if the number of segments constituting the tread ring is increased, the processing for strengthening the lateral blades also increases. In this case, blocks with changed rigidity are formed in many parts of the tread, which may reduce the uneven wear resistance of the tire. There is a concern that the reduced uneven wear resistance may lead to early tire replacement. Therefore, in order to stably manufacture high-quality tires, the present inventors have conducted research focusing on the dividing surface, and have completed the present invention described below.

[0018] [Details of the embodiment of the present invention] Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

[0019] [Tire manufacturing method] In a tire manufacturing method according to one embodiment of the present invention, a raw tire (a tire in an uncrosslinked state) is prepared by combining elements such as a tread and a sidewall prepared as parts. The raw tire is placed in a tire mold described below, and the raw tire is pressurized and heated in the mold. This crosslinks the uncrosslinked rubber composition contained in the raw tire, and a tire is obtained as a crosslinked product of the raw tire. The method of manufacturing a tire includes the steps of providing a green tire and pressurizing and heating the green tire in a mold. In the present invention, pressurizing and heating the green tire in a mold is also called vulcanization molding, and the process of pressurizing and heating the green tire in a mold is also called a vulcanization process. In this manufacturing method, there are no particular limitations on manufacturing conditions such as vulcanization temperature and vulcanization time, and general tire manufacturing conditions are applied.

[0020] [Vulcanizer] In the vulcanization process, a vulcanizer is used, which will be described below. FIG. 1 shows an example of a vulcanizer 2. The direction indicated by the double-headed arrow AD in FIG. 1 corresponds to the axial direction of a tire manufactured by this vulcanizer 2. The axial direction of a tire means the direction parallel to the rotation axis of the tire. The direction indicated by the double-headed arrow RD corresponds to the radial direction of the tire. The direction perpendicular to the paper surface of FIG. 1 corresponds to the circumferential direction of the tire.

[0021] A tire mold 4 according to one embodiment of the present invention is incorporated into the vulcanizer 2. The vulcanizer 2 includes the mold 4 and a bladder 6. In the vulcanizer 2, the configuration other than the mold 4 is the same as that of a conventional vulcanizer. Detailed description of the configuration other than the mold 4 will be omitted.

[0022] As shown in Fig. 1, a green tire 10r is placed in a cavity 8 formed between a mold 4 and a bladder 6. The green tire 10r is pressurized and heated in the cavity 8. In this way, a tire 10 is obtained. The mold 4 is a mold for forming the tire 10.

[0023] The mold 4 has an inner surface that is provided with a cavity surface 12. The cavity surface 12 abuts against the outer surface of the green tire 10r and shapes the outer surface of the tire 10 into the green tire 10r. The bladder 6 is located inside the mold 4. The bladder 6 is made of crosslinked rubber. A heating medium such as steam is filled inside the bladder 6, which causes the bladder 6 to expand. The bladder 6 shown in FIG. 1 is in an expanded state filled with a heating medium. The bladder 6 comes into contact with the inner surface of the green tire 10r, and shapes the inner surface of the tire 10 to the inner surface of the green tire 10r. The above-mentioned cavity 8 is a space surrounded by the cavity surface 12 of the mold 4 and the bladder 6 . In this tire manufacturing method, a metal rigid core (not shown) may be used in place of the bladder 6. The rigid core has a toroidal outer surface that approximates the shape of the inner surface of the tire 10 when it is filled with air and the internal pressure is maintained at 5% of the normal internal pressure.

[0024] [Mold] The mold 4 shown in Fig. 1 is a split mold type mold. The mold 4 includes, as components, a tread ring 14, a pair of side plates 16, and a pair of bead rings 18. The aforementioned cavity surface 12 is formed by combining these components. The mold 4 in Fig. 1 is in a state where these components are combined, in other words, in a closed state.

[0025] The tread ring 14 forms a tread portion of the tire 10. Each side plate 16 forms a sidewall portion of the tire 10. Each bead ring 18 forms a bead portion of the tire 10.

[0026] 2 shows the tread ring 14. In FIG. 2, the position indicated by the reference symbol TRc is the center of the tread ring 14. The center TRc corresponds to the rotation axis of the tire 10.

[0027] The tread ring 14 has a plurality of segments 20. The plurality of segments 20 are arranged in the circumferential direction. The tread ring 14 is formed by combining a plurality of segments 20. Each segment 20 has a mating surface 22 that comes into close contact with an adjacent segment 20. In the tread ring 14, the portion where the segments 20 come into close contact with each other is a dividing surface 24. The dividing surface 24 is formed by the mating surfaces 22 of adjacent segments 20 coming into close contact with each other. The number of segments 20 included in the tread ring 14 is equal to or greater than 17 and equal to or less than 29.

[0028] The tread ring 14 has a tread molding surface 36 on its inner peripheral surface. The tread molding surface 36 forms the outer peripheral surface of the tread portion (also called the tread surface). As described above, the tread ring 14 has a plurality of segments 20, and the portion where the segments 20 are in close contact with each other is the dividing surface 24. The dividing surface 24 crosses the tread molding surface 36. The tread ring 14 includes a plurality of dividing surfaces 24. The plurality of dividing surfaces 24 divide the tread ring 14 into a plurality of segments 20. Each of the plurality of segments 20 includes a partial molding surface 38. The partial molding surface 38 forms a part of the tread molding surface 36.

[0029] The vulcanizer 2 further includes an opening / closing frame 26 for opening and closing the mold 4 . The opening / closing frame 26 includes a plurality of sector shoes 28, an actuator 30, an upper support plate 32, and a lower support plate 34. Each of the multiple sector shoes 28 is located radially outside the segments 20. One segment 20 is fixed to one sector shoe 28. The number of sector shoes 28 is the same as the number of segments 20. The actuator 30 is ring-shaped. The actuator 30 is located radially outside the sector shoe 28. The sector shoe 28 is slidably connected to the actuator 30. Although not described in detail, the actuator 30 is movable up and down. The upper support plate 32 is disk-shaped. The upper side plate 16 and the bead ring 18 are fixed to this upper support plate 32. Although not described in detail, the upper support plate 32 is movable up and down. The lower support plate 34 is disk-shaped. The lower side plate 16 and the bead ring 18 are fixed to the lower support plate 34. Although not shown, the lower support plate 34 is fixed to the frame of the vulcanizer 2.

[0030] 1, when the vulcanization process is completed, the actuator 30 is raised to move the sector shoes 28 radially outward. Since the segments 20 are fixed to the sector shoes 28, this causes the segments 20 to move radially outward as shown in FIG. 2. Then, the upper holding plate 32 is raised to move the upper side plate 16 and the bead ring 18 upward. Then, the actuator 30 is further raised to move the segments 20 upward together with the sector shoes 28. This opens the mold 4 and the tire 10 is removed.

[0031] In the vulcanization process, the green tire 10r is placed into the opened mold 4. The green tire 10r is placed on the lower side plate 16 and the bead ring 18. The actuator 30 is lowered, and the segments 20 are moved downward together with the sector shoes 28. Then, the upper holding plate 32 is lowered, and the upper side plate 16 and the bead ring 18 are moved downward. Then, the actuator 30 is further lowered, and the segments 20 are moved radially inward together with the sector shoes 28. This closes the mold 4, and the green tire 10r is pressurized and heated.

[0032] In the vulcanization process, the raw tire 10r is pressed against the tread molding surface 36 of the tread ring 14. As a result, the outer peripheral surface of the tread portion is shaped into the tread portion of the raw tire 10r.

[0033] Fig. 3 shows an example of the outer peripheral surface of the tread portion 40 formed by the mold 4, i.e., a tread surface 42. The direction indicated by the double arrow AD in Fig. 3 is the axial direction of the tire 10. The direction indicated by the double arrow CD is the circumferential direction of the tire 10. The dashed dotted line CL in Fig. 3 is the equatorial plane of the tire 10. The tire 10 having this tread portion 40 is a heavy-duty tire that is fitted to trucks and buses. Fig. 3 shows a tread pattern formed by cutting grooves into the tread portion 40 of this tire 10. The tread portion 40 has a tread pattern.

[0034] The tread portion 40 has a plurality of circumferential grooves 44 aligned in the axial direction. The tread pattern of the tread portion 40 includes a plurality of circumferential grooves 44. The plurality of circumferential grooves 44 are continuous in the circumferential direction and extend in a zigzag pattern. The plurality of circumferential grooves 44 may be continuous in the circumferential direction and extend straight. The circumferential groove 44 has a groove width of 5 mm or more and 20 mm or less. The circumferential groove 44 has a groove depth of 10 mm or more and 20 mm or less.

[0035] The tread portion 40 shown in Fig. 3 has three circumferential grooves 44. The circumferential groove 44 located at the outermost side in the axial direction is a shoulder circumferential groove 44s. The circumferential groove 44 located at the innermost side in the axial direction is a center circumferential groove 44c. This tread portion 40 has one center circumferential groove 44c and two shoulder circumferential grooves 44s. This center circumferential groove 44c of the tread portion 40 is located on the equatorial plane.

[0036] The multiple circumferential grooves 44 define multiple land portions 46 in the tread portion 40. Four land portions 46 are defined in the tread portion 40 shown in Fig. 3. The land portion 46 located on the outermost side in the axial direction is a shoulder land portion 46s. The shoulder land portion 46s includes an end TE of the tread surface 42. The land portion 46 located on the innermost side in the axial direction is a center land portion 46c. The tread portion 40 shown in Fig. 3 has two center land portions 46c and two shoulder land portions 46s. The equator plane is located between the two center land portions 46c.

[0037] Each land portion 46 has a longitudinal groove 48 extending continuously in the circumferential direction. The groove width of the longitudinal groove 48 is narrower than the groove width of the circumferential groove 44. Specifically, the groove width of the longitudinal groove 48 is 4 mm or less. The groove depth of the longitudinal groove 48 is appropriately determined in consideration of the specifications of the tire 10. The longitudinal groove 48 may be shallower or deeper than the circumferential groove 44. The groove depth of the longitudinal groove 48 may be the same as the groove depth of the circumferential groove 44.

[0038] In the tread portion 40 shown in Fig. 3, the longitudinal grooves 48 (hereinafter also referred to as center longitudinal grooves 48c) cut in the center land portion 46c extend in a zigzag manner. The center longitudinal grooves 48c may also extend straight. The longitudinal grooves 48 cut in the shoulder land portion 46s (hereinafter also referred to as shoulder longitudinal grooves 48s) extend straight. The shoulder longitudinal grooves 48s may extend in a zigzag pattern.

[0039] In this tread portion 40, the shoulder longitudinal grooves 48s are sipes 50. The groove width of the shoulder longitudinal grooves 48s is narrower than the groove width of the center longitudinal grooves 48c. Specifically, the groove width of the shoulder longitudinal grooves 48s is less than 4 mm. The shoulder longitudinal grooves 48s extend in the circumferential direction, and are therefore also called longitudinal sipes 50L. In contrast, the center longitudinal grooves 48c are also called narrow longitudinal grooves 48L.

[0040] The longitudinal groove 48 forms two small land portions 52 in the land portion 46. Of the two small land portions 52, the small land portion 52 located axially inner is an inner small land portion 52u, and the small land portion 52 located axially outer is an outer small land portion 52s. Although not shown, when the land portion 46 is located on the equatorial plane, the small land portion 52 located on one end TE side of the tread surface 42 is also called the first small land portion, and the small land portion 52 located on the other end TE side of the tread surface 42 is also called the second small land portion.

[0041] Each land portion 52 has a lateral groove 54 extending in the axial direction. The lateral groove 54 extends in the axial direction. The angle that the lateral groove 54 makes with the circumferential direction is equal to or greater than 45 degrees and equal to or less than 90 degrees. This angle is represented by the angle that a line segment connecting one end and the other end of the groove width center line of the lateral groove 54 makes with the circumferential direction.

[0042] The lateral grooves 54 formed in the outer land portion 52s of the shoulder land portion 46s bridge between the end TE of the tread surface 42 and the longitudinal groove 48. The lateral grooves 54 formed in the other land portions 52 bridge between the circumferential groove 44 and the longitudinal groove 48. The groove width of the lateral grooves 54 in the tread portion 40 is narrower than the groove width of the circumferential grooves 44. The groove width of the lateral grooves 54 may be the same as the groove width of the circumferential grooves 44. The lateral grooves 54 are shallower than the circumferential grooves 44. The groove depth of the lateral grooves 54 may be the same as the groove depth of the circumferential grooves 44. The groove width and groove depth of the lateral grooves 54 are appropriately determined in consideration of the specifications of the tire 10. The lateral grooves 54 are not sipes 50.

[0043] The land portion 52 has a plurality of lateral grooves 54. The plurality of lateral grooves 54 are arranged at predetermined intervals in the circumferential direction. By carving the plurality of lateral grooves 54 in the land portion 52, a plurality of blocks 56 are formed in the land portion 52. In each land portion 52, the plurality of blocks 56 are lined up in the circumferential direction. In each land portion 46, the lateral grooves 54 of the inner land portion 52u and the lateral grooves 54 of the outer land portion 52s are arranged alternately in the circumferential direction. The blocks 56 formed in the inner land portion 52u and the blocks 56 formed in the outer land portion 52s are arranged alternately in the circumferential direction. A block 56 is located next to the lateral groove 54. The lateral groove 54 crosses the land portion 52 but does not cross the land portion 46. The lateral groove 54 abuts against the block 56 located next to it.

[0044] Each block 56 includes a sipe 50. In this tread portion 40, the sipes 50 provided in the blocks 56 are lateral sipes 50W extending in the axial direction. The angle that the lateral sipes 50W form with respect to the circumferential direction is equal to or greater than 20 degrees and equal to or less than 90 degrees. This angle is represented by the angle that a line segment connecting one end and the other end of the groove width center line of the lateral sipe 50W forms with respect to the circumferential direction. The lateral sipes 50W engraved in the blocks 56 of the shoulder land portion 46s bridge between the end TE of the tread surface 42 and the longitudinal grooves 48. The lateral sipes 50W engraved in the other blocks bridge between the circumferential grooves 44 and the longitudinal grooves 48.

[0045] The lateral sipes 50W extend in a zigzag pattern on the tread surface 42. The lateral sipes 50W are three-dimensional sipes. The lateral sipes 50W may be two-dimensional sipes. In this case, the lateral sipes 50W extend straight on the tread surface 42.

[0046] Each block 56 has a plurality of lateral sipes 50W. In each block 56, the plurality of lateral sipes 50W are arranged at predetermined intervals in the circumferential direction. In the tread portion 40, five lateral sipes 50W are provided in the block 56 formed in the outer land portion 52s of the shoulder land portion 46s. Four lateral sipes 50W are provided in the other blocks 56. The blocks 56 form part of the land portions 46. Transverse sipes 50W are formed in each of the land portions 46 formed in the tread portion 40.

[0047] The circumferential grooves 44, the narrow longitudinal grooves 48L, the longitudinal sipes 50L, the lateral grooves 54, and the lateral sipes 50W constitute a tread pattern. In other words, the tread pattern of the tire 10 includes the circumferential grooves 44, the narrow longitudinal grooves 48L, the longitudinal sipes 50L, the lateral grooves 54, and the lateral sipes 50W.

[0048] 3, the straight line indicated by the symbol VDL is an imaginary straight line drawn on the outer surface of the tread portion 40. This straight line VDL extends in the axial direction. As shown in FIG. 3, the straight line VDL intersects with the lateral sipe 50W. In the tread pattern of this tire 10, when a straight line VDL extending in the axial direction is drawn on the outer surface of the tread portion 40, this straight line VDL intersects with at least one lateral sipe 50W, or even if this straight line VDL does not intersect with the lateral sipe 50W, it passes through a position where the distance from this straight line VDL to the lateral sipe 50W is less than 1.5 mm.

[0049] The tread pattern described above is engraved by the tread molding surface 36 shown in FIG. 4. The tread molding surface 36 has an uneven pattern corresponding to the tread pattern shown in FIG. 3. In FIG. 4, the dashed-dotted line CLm corresponds to the equatorial plane CL of the tire 10. The direction indicated by the double-headed arrow ADm in FIG. 4 corresponds to the axial direction of the tire 10. The direction indicated by the double-headed arrow CD corresponds to the circumferential direction of the tire 10. The double-dotted line TEL is a position corresponding to the end TE of the tread surface 42. For convenience of explanation, the dimensions of the mold 4 are expressed in terms of the dimensions of the tire 10.

[0050] In this manufacturing method, the circumferential groove 44 is formed by a circumferential protrusion. As shown in FIG. 3, the narrow longitudinal groove 48L merges with the lateral groove 54. Therefore, the portion of the narrow longitudinal groove 48L between the two lateral grooves 54 aligned in the circumferential direction is formed by a vertical plate 64. The narrow longitudinal groove 48L is formed by a plurality of vertical plates 64. The longitudinal sipe 50L also merges with the lateral groove 54. Therefore, the portion of the longitudinal sipe 50L between the two lateral grooves 54 aligned in the circumferential direction is formed by a vertical blade 66. The longitudinal sipe 50L is formed by a plurality of longitudinal blades 66. The lateral groove 54 is formed by a lateral protrusion 68. And the lateral sipe 50W is formed by a lateral blade 70. Thus, the tread molding surface 36 includes a circumferential protrusion 62 that forms the circumferential groove 44, a plurality of longitudinal plates 64 that form the narrow longitudinal grooves 48L, a plurality of longitudinal blades 66 that form the longitudinal sipes 50L, a lateral protrusion 68 that forms the lateral grooves 54, and a lateral blade 70 that forms the lateral sipes 50W. The circumferential protrusions 62 , the vertical plates 64 , the vertical blades 66 , the lateral protrusions 68 , and the lateral blades 70 form the concave-convex pattern of the tread molding surface 36 .

[0051] As described above, the angle that the lateral sipe 50W makes with respect to the circumferential direction is equal to or greater than 20 degrees and equal to or less than 90 degrees. As described above, the lateral sipe 50W is formed by the lateral blade 70. Therefore, the angle that the lateral blade 70 makes with respect to the circumferential direction is equal to or greater than 20 degrees and equal to or less than 90 degrees.

[0052] As shown in FIG. 1, the segment 20 constituting the tread ring 14 includes a main body 72 and a holder 74 that holds the main body 72 . As described above, the tread ring 14 is formed by combining a plurality of segments 20. This forms a body ring 76 made of a plurality of bodies 72 arranged in the circumferential direction, and a holder ring 78 made of a plurality of holders 74 arranged in the circumferential direction. The body ring 76 has the tread molding surface 36.

[0053] As shown in Fig. 4, the concave-convex pattern of the tread molding surface 36 is divided into a plurality of pitch elements 80 arranged in the circumferential direction. A solid line BL extending in the axial direction in Fig. 4 is a boundary between two adjacent pitch elements 80.

[0054] As described above, the main body ring 76 has the tread molding surface 36. The main body ring 76 is composed of a plurality of pitch elements 80 arranged in the circumferential direction. As shown in Fig. 5, the plurality of pitch elements 80 constituting the main body ring 76 include pitch elements 80 intersecting with the dividing surface 24 of the tread ring 14 (hereinafter also referred to as boundary pitch elements 80b) and pitch elements 80 not intersecting with the dividing surface 24 (hereinafter also referred to as normal pitch elements 80n). The parting surface 24 crosses the boundary pitch element 80b. As shown in Fig. 4, the parting surface 24 of the mold 4 is represented by a line extending in a zigzag manner in the axial direction, rather than a straight line extending in the axial direction.

[0055] Fig. 6 is a development view showing the boundary pitch element 80b shown in Fig. 4. The dividing surface 24 shown in Fig. 6 is an example of the dividing surface 24 provided in this mold 4. The dividing surface 24 will be described with the CDm1 side of the paper as the first circumferential side and the CDm2 side as the second circumferential side. The end PE of the dividing surface 24 on the ADm1 side of the paper is called the first end PE1, and the end PE of the dividing surface 24 on the ADm2 side of the paper is called the second end PE2.

[0056] The divided surface 24 (specifically, the contour line of the divided surface 24) includes a plurality of straight lines SL and a plurality of circular arcs AC. The number of circular arcs AC included in the divided surface 24 is preferably 2 to 8. The divided surface 24 shown in Fig. 6 is made up of seven straight lines SL and six circular arcs AC.

[0057] Fig. 7 shows a modified example of the dividing surface 24. This dividing surface 24 is made up of six straight lines SL and five circular arcs AC. This dividing surface 24 is located on the first circumferential side of the dividing surface 24 shown in Fig. 6. Fig. 8 shows another modified example of the dividing surface 24. This dividing surface 24 is made up of five straight lines SL and four circular arcs AC. This dividing surface 24 is located on the second circumferential side of the dividing surface 24 shown in Fig. 6. Three different boundary pitch elements 80b, shown in FIGS. 6-8, are used to adjust the size of the body 72 relative to the segment 20. As shown in FIG. Although there are differences in shape, all of the parting surfaces 24 shown in Figures 6 to 8 have the configuration of the parting surface 24 described below. Based on the parting surface 24 shown in Figure 6, the parting surface 24 provided in the mold 4 of the present invention will be described.

[0058] 6, the seven straight lines SL are arranged in the axial direction. The seven straight lines SL are, from the first end PE1 side of the dividing surface 24, a first straight line SL1, a second straight line SL2, a third straight line SL3, a fourth straight line SL4, a fifth straight line SL5, a sixth straight line SL6, and a seventh straight line SL7.

[0059] The six circular arcs AC are also arranged in the axial direction. The six circular arcs AC are a first circular arc AC1, a second circular arc AC2, a third circular arc AC3, a fourth circular arc AC4, a fifth circular arc AC5, and a sixth circular arc AC6 from the first end PE1 side of the dividing surface 24. As shown in Fig. 6, all of the six circular arcs AC are located axially inward of the corresponding positions TEL of the end TE of the tread surface 42. Each arc AC connects two adjacent straight lines SL. The first arc AC1 connects the first straight line SL1 and the second straight line SL2. The second arc AC2 connects the second straight line SL2 and the third straight line SL3. The third arc AC3 connects the third straight line SL3 and the fourth straight line SL4. The fourth arc AC4 connects the fourth straight line SL4 and the fifth straight line SL5. The fifth arc AC5 connects the fifth straight line SL5 and the sixth straight line SL6. The sixth arc AC6 connects the sixth straight line SL6 and the seventh straight line SL7.

[0060] Among the seven straight lines SL, the straight lines SL located on the outermost sides in the axial direction are straight lines extending substantially parallel to the axial direction and are also called reference straight lines SLB. In this dividing surface 24, the first straight line SL1 and the seventh straight line SL7 are the reference straight lines SLB. The five straight lines SL located between the first straight line SL1 and the seventh straight line SL7 are either straight lines extending substantially parallel to the axial direction or straight lines inclined relative to the axial direction. The five straight lines SL located between the first straight line SL1 and the seventh straight line SL7 are also called adjustment straight lines SLA. In the present invention, the reference line SLB extends substantially parallel to the axial direction means that the angle between the reference line SLB and the axial direction is 0 degrees or more and 5 degrees or less. When the angle between the reference line SLB and the axial direction is 0 degrees, the reference line SLB extends parallel to the axial direction.

[0061] When the lateral blade 70 intersects with the dividing surface 24, the lateral blade 70 is composed of two small blade pieces. In this case, the rigidity of the entire lateral blade 70 decreases. Even if the number of segments 20 included in the tread ring 14 is set to 17 or more and the mold 4 is configured so that a specific force is unlikely to act on the lateral blade 70 when the tire 10 is removed from the mold 4, the lateral blade 70 may be damaged, such as broken or bent. However, in this mold 4, in the development view of the tread molding surface 36, the dividing surface 24 extends from the first end PE of the dividing surface 24 to the second end PE, bypassing the lateral blade 70. In other words, the dividing surface 24 does not intersect with the lateral blade 70. Since the lateral blade 70 is composed of a single blade, the mold 4 can form the lateral blade 70 having the desired rigidity. Even if a specific force acts on the lateral blade 70 when removing the tire 10 from the mold 4, the lateral blade 70 is unlikely to be damaged. The mold 4 can suppress damage to the blade for cutting the sipes. The mold 4 can contribute to the stable production of high-quality tires. By using the mold 4, the tire manufacturing method can stably manufacture high-quality tires.

[0062] By using this mold 4, there is no need to increase the strength of the lateral blades 70 by processing such as thickening the lateral blades 70 or reducing the protruding height of the lateral blades 70. The tire 10 manufactured with this mold 4 is configured so that many of the blocks 56 provided in the tread portion 40 have the same rigidity. This mold 4 can contribute to improving the uneven wear resistance of the tire 10.

[0063] Fig. 9 is an enlarged development showing a part of the dividing surface 24 shown in Fig. 6. The length indicated by the double arrow DP in Fig. 9 is the distance from the lateral blade 70 to the dividing surface 24. This distance DP is expressed as the distance from the lateral blade 70 to the dividing surface 24 at the position where the distance from the lateral blade 70 to the dividing surface 24 is the shortest in the development view of the tread molding surface 36, on the lateral blade 70 located near the dividing surface 24.

[0064] The distance DP from the lateral blade 70 to the parting surface 24 is preferably 1.5 mm or more. This prevents specific forces from acting on the lateral blade 70 when the tire 10 is removed from the mold 4. The lateral blade 70 is less likely to be damaged. This mold 4 can prevent damage to the blades used to cut the sipes. The distance DP is more preferably 1.5 mm or more, and even more preferably 3.0 mm or more. The farther the lateral blade 70 is from the parting surface 24, the more preferable it is, so no preferred upper limit is set for the distance DP.

[0065] In FIG. 9, an arrow R indicates the radius of a circular arc AC included in the dividing surface 24 . The radius R of the arc AC of the parting surface 24 is preferably 10.0 mm or more. This prevents the force acting on the parting surface 24 during vulcanization from concentrating on the part of the arc AC. Since the force is distributed over the entire parting surface 24, local fatigue of the part of the arc AC and damage to this part are prevented. This mold 4 has good durability. From this viewpoint, the radius R of the arc AC is more preferably 10 mm or more, and further preferably 20 mm or more. The larger the radius R of the arc AC, the better, so no preferred upper limit is set.

[0066] In Fig. 9, the third straight line SL3, which is the adjustment straight line SLA, is inclined with respect to the circumferential direction. The angle α is the angle that the adjustment straight line SLA makes with the circumferential direction. If the angle α is small, when the mold 4 is closed, the length of the portion where the opposing mating surfaces 22 rub against each other and come into close contact becomes long, and a portion where wear has progressed is formed on the mating surfaces 22. In this case, a gap is formed on the parting surface 24, and there is a concern that overspew is more likely to occur. From the viewpoint of suppressing the occurrence of overspew, the angle α is preferably equal to or greater than 45 degrees, and more preferably equal to or greater than 60 degrees. When the angle α exceeds 90 degrees, the direction of the adjustment straight line SLA is reversed, so the upper limit of this angle α is 90 degrees. When the angle α is 90 degrees, the straight line SLA normally extends in the axial direction.

[0067] As described above, the arc AC of the dividing surface 24 connects between two adjacent straight lines SL. The straight line SL on one side of the arc AC is inclined with respect to the straight line SL on the other side. The angle β is the angle between the straight line SL on one side and the straight line SL on the other side that are connected to the arc AC. If the angle β is small, there is a concern that when the opposing mating surfaces 22 come into close contact with each other, rubber will get in between the mating surfaces 22, making overspew more likely to occur. From the viewpoint of suppressing the occurrence of overspew, this angle β is preferably equal to or greater than 90 degrees, and more preferably equal to or greater than 110 degrees. The larger the angle β, the more preferable it is, but when the angle β is 180 degrees, no circular arc is formed between the two adjacent straight lines SL. From the viewpoint that the two adjacent straight lines SL are connected by a circular arc AC, this angle β is less than 180 degrees.

[0068] FIG. 10 shows the entire parting surface 24 shown in FIG. As described above, the parting surface 24 of this mold 4 is represented by a line extending in a zigzag manner in the axial direction, rather than a straight line extending in the axial direction. As shown in Fig. 10, the dividing surface 24 includes a portion bulging toward the first circumferential side and a portion bulging toward the second circumferential side. The position indicated by the symbol PT1 in Fig. 10 is the position on the dividing surface 24 that is closest to the boundary BL of the boundary pitch element 80b on the first circumferential side. The position indicated by the symbol PT2 is the position on the dividing surface 24 that is closest to the boundary BL of the boundary pitch element 80b on the second circumferential side. The length indicated by the symbol AM is the circumferential distance from the position PT1 to the position PT2. This circumferential distance AM is also called the amplitude of the dividing surface 24.

[0069] The amplitude AM of the parting surface 24 is preferably 30 mm or less. This prevents localized forces from acting on the parting surface 24 during vulcanization molding. Since the forces are distributed over the entire parting surface 24, localized fatigue of the parting surface 24 and damage to the parting surface 24 are prevented. This mold 4 has good durability. From this viewpoint, it is more preferable that the amplitude AM of the parting surface 24 is 20 mm or less. The smaller the amplitude AM, the more preferable it is, so no preferred lower limit is set.

[0070] As described above, the dividing surface 24 crosses the tread molding surface 36. Therefore, there are cases where the dividing surface 24 intersects with the vertical plate 64 that forms the narrow vertical groove 48L. In this case, as shown in FIG. 10, the vertical plate 64 is composed of two small piece plates 64s. In FIG. 10, the double arrow LP indicates the length of the small piece plate 64s. When there is a difference between the two small piece plates 64s, this length LP is represented by the length of the shorter small piece plate 64s.

[0071] If the vertical plate 64 is composed of two small plates 64s, the rigidity of the vertical plate 64 will decrease, and there is a concern that an unusual force will act on the vertical plate 64 when the tire 10 is removed from the mold 4, causing damage to the vertical plate 64. From the viewpoint of suppressing damage to the vertical plate 64, the length LP of the small plate 64s is preferably 3.0 mm or more, and more preferably 10 mm or more. The longer the length LP, the more preferable it is, so no preferred upper limit is set.

[0072] There may also be a case where the dividing surface 24 intersects with the vertical blade 66 forming the vertical sipe 50L. In this case, as shown in Fig. 10, the vertical blade 66 is composed of two small piece blades 66s. In Fig. 10, the double arrow LB indicates the length of the small piece blade 66s. When there is a difference between the two small piece blades 66s, this length LB is represented by the length of the shorter small piece blade 66s.

[0073] If the vertical blade 66 is composed of two small blade pieces 66s, the rigidity of the vertical blade 66 will decrease, and there is a concern that an unusual force will act on the vertical blade 66 when the tire 10 is removed from the mold 4, causing damage to the vertical blade 66. From the viewpoint of suppressing damage to the vertical blade 66, the length LB of the small blade 66s is preferably 3.0 mm or more, and more preferably 10 mm or more. The longer the length LB, the more preferable it is, so no upper limit is set.

[0074] If the dividing surface 24 intersects with the lateral convex portion 68, there is a concern that when the adjacent segments 20 come into close contact with each other, a part of the raw tire 10r may be caught between the two segments 20. From the viewpoint of preventing jamming, it is preferable that the dividing surface 24 does not intersect with the lateral protrusion 68, for example, as shown in FIG.

[0075] FIG. 11 shows a lateral blade 70. In FIG. 11, the double-headed arrow LD indicates the length direction of the lateral blade 70. The angle that the lateral blade 70 makes with respect to the circumferential direction is set by adjusting the angle that the length direction of the lateral blade 70 makes with respect to the circumferential direction. The double-headed arrow HD indicates the height direction of the lateral blade 70. The depth of the lateral sipe 50W is adjusted by adjusting the height of the lateral blade 70. The double-headed arrow TB indicates the thickness of the lateral blade 70 (more specifically, the blade body described later). The groove width of the lateral sipe 50W is set by adjusting the thickness TB.

[0076] The lateral blade 70 includes a blade body 86 extending in the length and height directions. As shown in FIG. 8, the blade body 86 is a blade (hereinafter also referred to as a three-dimensional blade) extending in a zigzag manner in the length and height directions of the lateral blade 70. The zigzag amplitude of the blade body 86 is, for example, 0.5 mm to 3.0 mm. The blade body 86 forms a three-dimensional sipe in the tread portion 40 as the lateral sipe 50W. The blade body 86 may be a flat blade extending straight in the length and height directions of the lateral blade 70. In this case, the blade body 86 forms a two-dimensional sipe in the tread portion 40 as the lateral sipe 50W. When the block 56 deforms and the wall surfaces of the horizontal sipe 50W come into close contact with each other, the wall surfaces restrain each other, thereby increasing the apparent rigidity of the block 56. From the viewpoint of improving resistance to uneven wear, it is preferable that the blade body 86 is a blade that extends in a zigzag pattern in the length and height directions of the horizontal blade 70.

[0077] FIG. 12 shows a modified example of the horizontal blade 70. FIG. 12 shows a cross section of the horizontal blade 70. As shown in FIG. 12, the horizontal blade 70 includes, in addition to the blade body 86 described above, a columnar portion 88 extending in the length direction of the horizontal blade 70. The columnar portion 88 is provided on the lower side of the blade body 86. The cross-sectional shape of the columnar portion 88 may be circular, elliptical, or track-shaped. In FIG. 12, the double arrow WP indicates the maximum width of the columnar portion 88. The maximum width WP of the columnar portion 88 is preferably 5 to 13 times the thickness TB of the blade body 86. Although not shown, the columnar portion 88 forms a tubular portion on the bottom side of the lateral sipe 50W. This tubular portion functions as a lateral groove when the tread portion 40 wears and the tubular portion becomes exposed.

[0078] A larger force acts on the lateral blade 70 shown in Figs. 11 and 12 when the tire 10 is removed from the mold 4, compared to the lateral blade 70 made of a flat blade. Therefore, there is a concern that the lateral blade 70 may be damaged when the tire 10 is removed from the mold 4. However, as described above, the dividing surface 24 does not intersect with the lateral blade 70. Since the lateral blade 70 is composed of a single blade, the mold 4 can configure the lateral blade 70 having the desired rigidity. Even if a specific force acts on the lateral blade 70 when the tire 10 is removed from the mold 4, the lateral blade 70 is unlikely to be damaged. The mold 4 can suppress damage to the blade for cutting the sipes. Moreover, the lateral sipes 50W formed by the lateral blade 70 apparently increase the rigidity of the block 56, improving uneven wear resistance. When the lateral blade 70 has a columnar portion 88 as shown in FIG. 12, the tubular portion formed by this columnar portion 88 can contribute to improving driving performance on wet roads when the tread portion 40 is worn. Since damage to the lateral blade 70 can be suppressed when the tire 10 is removed from the mold 4, it is possible to employ the lateral blade 70 in which the thickness TB of the blade body 86 is set to 0.6 mm or less. In this case, the tire 10 can have further improved resistance to uneven wear. From this viewpoint, it is preferable that the thickness TB of the blade body 86 of this lateral blade 70 is 0.6 mm or less.

[0079] As described above, the number of segments 20 included in the tread ring 14 is equal to or greater than 17 and equal to or less than 29. In the tire 10 manufactured by this mold 4, from the viewpoint of effectively suppressing the occurrence of noise, vibration, and uneven wear, it is preferable that the number of segments 20 included in the tread ring 14 is a prime number. In this case, there is a concern that it may become difficult to adjust the size of the main body 72 relative to the segments 20. However, as described above, this mold 4 can prepare multiple types of boundary pitch elements 80b with different specifications for the parting surface 24. Therefore, with this mold 4, it is easy to adjust the size of the main body 72 relative to the segments 20.

[0080] From the viewpoints of the degree of freedom in designing the dividing surface 24 and ensuring the circularity of the tire 10, when the number of segments 20 included in the tread ring 14 is a prime number, it is more preferable that the number of segments 20 is 19. As a result, this manufacturing method can stably manufacture high-quality tires and further improve the uneven wear resistance of the tires.

[0081] As is clear from the above description, the present invention provides a tire mold that can suppress damage to the blades used to cut sipes. This mold can contribute to the stable manufacture of high-quality tires. This mold can improve the uneven wear resistance of tires. EXAMPLES

[0082] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0083] [Example 1] A tire (size = 275 / 80R22.5) having the outer peripheral surface shown in Fig. 3 was manufactured using a vulcanizer incorporating a mold having the basic configuration shown in Fig. 2 and 4-10. The mold used the blade shown in Fig. 11 as a lateral blade. The thickness TB of this lateral blade is 0.3 mm, and the height is 18.0 mm. The number of divisions of the tread ring of the mold was set to 19. Therefore, the number of segments constituting the tread ring was 19. For the dividing surface, the boundary pitch elements shown in Figures 6 to 8 were used to adjust the size of the body so that the size of the body relative to the segments was the same. The distance DP from the dividing surface to the transverse blade was set to be 1.5 mm or more.

[0084] [Examples 2-4 and Comparative Examples 1-3] A tire was manufactured in the same manner as in Example 1, except that the number of divisions into the tread rings was set as shown in Table 1 below.

[0085] [Comparative Example 4] A tire was manufactured in the same manner as in Example 1, except that the dividing surface of the boundary pitch element was made straight and was configured to intersect with the lateral blade.

[0086] [Uneven wear] The prototype tire was mounted on a regular rim and filled with air to adjust the tire's internal pressure to 900 kPa. This tire was attached to the drive axle of a test vehicle (truckhead). A trailer loaded with cargo was towed by this test vehicle, and the test vehicle was driven on a public road. When the tire's wear rate reached 30% in mass terms, the difference between the amount of wear at the position corresponding to the split surface and the amount of wear at other parts was calculated. The results are shown in Table 1 below, with Comparative Example 1 set as an index of 100. The larger the value, the more uneven wear is suppressed and the better the uneven wear resistance is.

[0087] [Damage to side blade] A stress analysis was performed using FEM to calculate the amount of deformation of the lateral blade when 1,000 tires were manufactured. The results are shown in Table 1 below, with Comparative Example 1 indexed to 100. The larger the value, the smaller the amount of deformation, and the more the damage to the lateral blade is suppressed.

[0088] [Workability] The mold was assembled and cleaned, and the time required for the work was measured. The results are shown in Table 1 below as an index, with Comparative Example 1 being set at 100. The larger the value, the longer the work took.

[0089] [cost] The cost of producing the mold was estimated. The results are shown in Table 1 below, with Comparative Example 1 indexed to 100. The higher the value, the higher the production cost.

[0090] Circularity The circularity of the prototype tires was measured. The results are shown in Table 1 below as an index, with Comparative Example 1 being set at 100. The larger the value, the higher the circularity.

[0091] [Table 1]

[0092] As shown in Table 1, in the embodiment, damage to the side blade is suppressed and uneven wear resistance is improved. From this evaluation result, the superiority of the present invention is clear. Note that for Comparative Example 4, roundness was not evaluated. [Industrial Applicability]

[0093] The above-described technology capable of suppressing damage to the blade can be applied to various tire molds.

[0094] [Note] The present invention includes the following aspects.

[0095] [1] A mold for forming a tire having a tread portion, the tread portion having a tread pattern including a plurality of circumferential grooves arranged in an axial direction and a plurality of lateral sipes arranged in a circumferential direction, a plurality of land portions formed in the tread portion by the plurality of circumferential grooves, a plurality of the lateral sipes being engraved in each land portion, an angle formed by each of the lateral sipes with respect to the circumferential direction being 20 degrees or more, and a straight line extending in the axial direction on an outer surface of the tread portion intersects with at least one lateral sipe, or, even if the straight line does not intersect with the lateral sipe, passes through a position where the distance to the lateral sipe is less than 1.5 mm, the mold having a tread ring forming the tread portion, an inner circumferential surface of the tread ring forms the tread pattern on the tread portion. a tread molding surface that forms a tread ring with a tread groove, the tread molding surface having a plurality of circumferential convex portions that form a plurality of the circumferential grooves and a plurality of lateral blades that form a plurality of the lateral sipes, the tread ring having a plurality of dividing surfaces that cross the tread molding surface, the dividing surfaces dividing the tread ring into a plurality of segments, the number of the segments included in the tread ring being 17 or more, in a development view of the tread molding surface, the dividing surface includes a plurality of straight lines aligned in the axial direction and a plurality of circular arcs connecting two adjacent straight lines, and among the plurality of straight lines, two straight lines located at the outermost positions in the axial direction are each reference straight lines extending substantially parallel to the axial direction, and the dividing surface does not intersect with the lateral blades. [2] The tire mold according to [1] above, wherein in a development view of the tread molding surface, the distance from the lateral blade to the dividing surface is 1.5 mm or more. [3] The tire mold according to [1] or [2] above, wherein the radius of the arc is 10.0 mm or more. [4] A tire mold as described in any one of [1] to [3] above, wherein the lateral blade has a blade body extending in the length and height directions of the lateral blade, and the thickness of the blade body is 0.6 mm or less. [5] The tire mold according to [4] above, wherein the blade body is a blade extending in a zigzag pattern in the length and height directions of the lateral blade. [6] The tire mold according to any one of [1] to [5] above, wherein the number of segments included in the tread ring is a prime number. [7] A method for manufacturing a tire, comprising the steps of pressurizing and heating a green tire in a mold, the mold being the mold described in any one of [1] to [6] above. [Explanation of symbols]

[0096] 2. Vulcanizer 4. Mold 8. Cavity 10. Tires 12. Cavity surface 14 Tread ring 20 segments 22. Mating surface 24...Divided plane 36 Tread molding surface 40 Tread section 42 Tread surface 44...Circumferential groove 46... Rikubu 48...Vertical groove 48L...Narrow vertical groove 50L: Vertical sipes 50W: Horizontal sipes 52, 52u, 52s...Korikube 54 Yokomizo 56... Block 62 Circumferential convex portion 64 Vertical plate 66...Vertical blade 68...Horizontal convex part 70···Horizontal blade 80···Pitch element 80b Boundary pitch element 86 Blade body

Claims

1. A mold for forming a tire, comprising: a tread portion, the tread portion having a tread pattern including a plurality of circumferential grooves aligned in an axial direction and a plurality of lateral sipes aligned in a circumferential direction, a plurality of land portions formed in the tread portion by the plurality of circumferential grooves, a plurality of the lateral sipes being engraved in each land portion, an angle formed by each of the lateral sipes with respect to the circumferential direction being 20 degrees or more, and a straight line extending in the axial direction on an outer surface of the tread portion intersects with at least one lateral sipe, or, even if the straight line does not intersect with the lateral sipe, passes through a position where the distance to the lateral sipe is less than 1.5 mm, The mold includes a tread ring that forms the tread portion, an inner circumferential surface of the tread ring includes a tread molding surface that forms the tread pattern in the tread portion; The tread molding surface includes a plurality of circumferential convex portions that form a plurality of the circumferential grooves, and a plurality of lateral blades that form a plurality of the lateral sipes, the tread ring has a plurality of split surfaces that intersect the tread molding surface; A plurality of said dividing surfaces divide said tread ring into a plurality of segments; The number of the segments included in the tread ring is 17 or more, In a development view of the tread molding surface, the dividing surface includes a plurality of straight lines arranged in an axial direction and a plurality of circular arcs connecting two adjacent straight lines, Among the plurality of straight lines, two straight lines located at the outermost positions in the axial direction are reference straight lines extending substantially parallel to the axial direction, The dividing surface does not intersect with the transverse blade. Tire mould.

2. In a development view of the tread molding surface, the distance from the lateral blade to the dividing surface is 1.5 mm or more.

2. The tire mold of claim 1.

3. The radius of the arc is 10.0 mm or more. The tire mold of claim 2.

4. the transverse blade comprises a blade body extending in a length direction and a height direction of the transverse blade; The thickness of the blade body is 0.6 mm or less.

2. The tire mold of claim 1.

5. The blade body is a blade extending in a zigzag manner in the length direction and height direction of the lateral blade. The tire mold of claim 4.

6. the number of segments included in the tread ring is a prime number; 2. The tire mold of claim 1.

7. The method includes the steps of pressurizing and heating the green tire in a mold, The mold is a mold according to any one of claims 1 to 6. A method for manufacturing tires.

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