Tire mold, method for manufacturing tire, and tire

Abstract

The present invention provides a tire mold (56) that optimizes the shape of the contact patch and the distribution of contact pressure. The mold (56) has a tread forming surface (64) for shaping the tread surface (22). The tread forming surface (64) has a rib (74) forming a circumferential groove (42) and a land surface forming portion (76) forming a land surface (46). Among the three land surface forming portions (76) arranged axially separated by the ribs (74), the land surface forming portion (76) located between two ribs (74) is a curved land surface forming portion (76B). The outline of the curved land surface forming portion (76B) is represented by one or more arcs. The boundary between the reference side surface (80a) of the rib (74) and the curved land surface forming portion (76B) is a reference boundary point (BBm), which is located inside the reference forming surface (FBL) of the tread forming surface (64).

Description

Technical Field

[0001] This invention relates to tire molds, tire manufacturing methods, and tires. Background Technology

[0002] A tire is obtained by pressurizing and heating an uncrosslinked tire (hereinafter referred to as a green tire) within a mold. The tire tread has multiple circumferential grooves arranged axially to form the land portion. On the tread forming surface of the mold, ridges corresponding to the circumferential grooves are provided to form them. The green tire is pressed against these ridges, thereby forming the circumferential grooves on the tread.

[0003] The tire has, for example, a belt containing a plurality of cords arranged in a radial direction on the inner side of the tread. In order to prevent the belt from undulating when the green tire is pressed against the rib, various countermeasures are implemented in the tire manufacturing process (for example, Patent Document 1 below).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2014-61602

[0005] If the rib is pressed onto the green tire, a portion of the uncured rubber component (hereinafter referred to as uncured rubber) pressed by the rib will flow into the part forming the land section. If the uncured rubber has difficulty flowing, it may cause irregularities in the inner surface shape of the tread and undulations in the belt. This is especially true for tires with groove widths of 9 mm or more and a tread width of 45 mm or more. 2 When a circumferential groove with a larger cross-sectional area is formed in the tread, the large amount of unvulcanized rubber pressed against the ridge may disrupt the overall flow of unvulcanized rubber into the portion forming the land area. In this case, it is difficult to form a land area that reflects the shape of the portion forming the land area of ​​the mold. It is possible to form a land area that is thinner in the central part and thicker at the edges. In other words, it is possible to form a land area with a land surface that is formed with an inwardly protruding shape.

[0006] Figure 9 The diagram shows the contact patch shape of a conventional tire (size = 205 / 55R16) manufactured without considering the flow of uncured rubber pushed aside by the ribs. Figure 9 The outline of each land portion L included in the ground plane is shown. Figure 10 The image shows the ground pressure distribution of the tire. Figure 10 The right side shows the ground pressure distribution of the land section Ls on the tire shoulder, and the left side shows the ground pressure distribution of the land section Lm in the middle.

[0007] like Figure 9 As shown, in the shape of the ground surface, the circumferential outer edge of each land portion L has an inwardly protruding shape. For example... Figure 10As shown, it can be confirmed that the ground pressure locally increases at the edges of each land section L. Specifically, a ground pressure difference of approximately 200 kPa can be confirmed within the middle land section Lm, and a ground pressure difference of approximately 250 kPa can be confirmed within the shoulder land section Ls. Furthermore, it can be confirmed that the inner surface shape of the tread is disordered in this tire.

[0008] The flow of uncured rubber within the mold affects the tire's contact patch shape and ground pressure distribution. In other words, by controlling the flow of uncured rubber within the mold, the tire can make more complete contact with the road surface, potentially leading to further improvements in handling stability. Furthermore, since localized increases in ground pressure are also suppressed, improved wear resistance is also expected. Summary of the Invention

[0009] The present invention was made in view of the actual situation, and aims to provide a tire mold and a tire manufacturing method that can optimize the ground contact surface shape and ground pressure distribution, and to provide a tire that optimizes the ground contact surface shape and ground pressure distribution.

[0010] One aspect of the present invention is a tire mold for manufacturing a tire having a tread surface that contacts the road surface. At least two circumferential grooves are etched into the tread to form at least three land portions. The tread surface includes the at least two circumferential grooves and the outer surfaces of the at least three land portions, i.e., at least three land surfaces. The tire mold includes a tread forming surface for shaping the tread surface. The tread forming surface includes ribs forming the circumferential grooves and land surface forming portions forming the land surfaces. A surface having a profile represented by at least one arc and tangent to the three land surface forming portions arranged axially across the ribs is a reference forming surface of the tread forming surface. One of the three land surface forming portions, located between two of the ribs, is a curved land surface forming portion. The rib includes a side surface on the land surface forming portion side, i.e., a reference side surface, and a side surface on the back side of the reference side surface, i.e., a back side surface. The point of tangency between the curved land surface forming portion and the reference forming surface is the reference tangency point. The boundary between the reference side surface and the curved land surface forming portion is the reference boundary point. The intersection of the imaginary line extending from the reference boundary point toward the reference forming surface and the reference forming surface is the reference imaginary intersection point. The outline of the curved land surface forming portion is represented by one or more circular arcs. The reference boundary point is located inside the reference forming surface. When one convex rib has a small cross-sectional area and the other convex rib has a large cross-sectional area, the distance from the reference imaginary intersection point to the reference boundary point on the side of one convex rib is shorter, and the distance from the reference imaginary intersection point to the reference boundary point on the side of the other convex rib is longer.

[0011] Preferably, in this tire mold, when the distance from the reference imaginary intersection point on one side of the rib to the reference tangent point is set to Xw1m, the distance from the reference imaginary intersection point on one side of the rib to the reference imaginary intersection point on the other side of the rib is set to Wcm, the cross-sectional area of ​​one rib is set to Sam, and the cross-sectional area of ​​the other rib is set to Sbm, the distance Xw1m from the reference imaginary intersection point on one side of the rib is set to Xw1m in a manner that satisfies the following formula (1).

[0012] Sam / (Sam+Sbm)×100-10≤Xw1m / Wcm×100≤Sam / (Sam+Sbm)×100+10…(1).

[0013] Preferably, in the tire mold, the ratio of the distance from the reference imaginary intersection point to the reference boundary point to the cross-sectional area of ​​the ridge is 0.0008 or more and 0.0040 or less.

[0014] Preferably, in the mold for the tire, the contour of the curved land surface forming part, from the reference tangent point to the reference boundary point, is represented by an arc that passes through the reference boundary point and is tangent to the reference forming surface at the reference tangent point.

[0015] Preferably, in this tire mold, the land surface forming portion located axially outward among the land surface forming portions included in the tread forming surface is the shoulder land surface forming portion. The land surface forming portion located next to the curved land surface forming portion among the three land surface forming portions is the shoulder land surface forming portion. The side of the ridge located between the shoulder land surface forming portion and the curved land surface forming portion, on the side of the curved land surface forming portion, is the reference side surface, and the side of the shoulder land surface forming portion is the back side surface. The tangent point between the shoulder land surface forming portion and the reference forming surface is the shoulder reference tangent point. The boundary between the back side surface and the shoulder land surface forming portion is the shoulder reference boundary point. The intersection of the imaginary line extending from the shoulder reference boundary point toward the reference forming surface and the reference forming surface is the shoulder reference imaginary intersection point. The distance from the shoulder reference imaginary intersection point to the shoulder reference boundary point on the back side surface is the same as the distance from the reference imaginary intersection point to the reference boundary point on the reference side surface. The distance from the imaginary intersection point of the shoulder reference to the tangent point of the shoulder reference is the same as the distance from the imaginary intersection point of the reference to the tangent point of the reference. The contour of the shoulder land surface forming portion, from the tangent point of the shoulder reference to the boundary point of the shoulder reference, is represented by an arc that passes through the boundary point of the shoulder reference and is tangent to the reference forming surface at the tangent point of the shoulder reference.

[0016] Preferably, in this tire mold, a longitudinal point is any position on an imaginary line on the reference side surface between the reference boundary point and the reference imaginary intersection point. An arc passing through the longitudinal point and tangent to the reference forming surface at the reference tangent point is a tangent-side arc. A transverse point is any position on the reference forming surface between the reference tangent point and the reference imaginary intersection point. The intersection point of the normal to the reference forming surface passing through the transverse point and the tangent-side arc is an intermediate boundary point. An arc passing through the reference boundary point and tangent to the tangent-side arc at the intermediate boundary point is a boundary-side arc. The contour of the curved land surface forming portion from the reference tangent point to the intermediate boundary point is represented by the tangent-side arc, and the contour from the intermediate boundary point to the reference boundary point is represented by the boundary-side arc.

[0017] Preferably, in this tire mold, the ratio of the distance from the reference imaginary intersection point to the longitudinal point to the distance from the reference imaginary intersection point to the reference boundary point is 0.40 or more and 0.60 or less. The ratio of the distance from the reference imaginary intersection point to the transverse point to the distance from the reference imaginary intersection point to the reference tangent point is 0.40 or more and 0.60 or less.

[0018] Preferably, in this tire mold, the land surface forming portion located axially outward among the land surface forming portions included in the tread forming surface is the shoulder land surface forming portion. The land surface forming portion located next to the curved land surface forming portion among the three land surface forming portions is the shoulder land surface forming portion. The side of the ridge located between the shoulder land surface forming portion and the curved land surface forming portion, on the side of the curved land surface forming portion, is the reference side surface, and the side of the shoulder land surface forming portion is the back side surface. The tangent point between the shoulder land surface forming portion and the reference forming surface is the shoulder reference tangent point. The boundary between the back side surface and the shoulder land surface forming portion is the shoulder reference boundary point. The intersection of the imaginary line extending from the shoulder reference boundary point toward the reference forming surface and the reference forming surface is the shoulder reference imaginary intersection point. The distance from the shoulder reference imaginary intersection point to the shoulder reference boundary point in the back side surface is the same as the distance from the reference imaginary intersection point to the reference boundary point in the reference side surface. The distance from the imaginary intersection point of the shoulder reference to the shoulder reference tangent point is the same as the distance from the imaginary intersection point of the reference to the reference tangent point. Any position on the imaginary line on the dorsal side, between the shoulder reference boundary point and the imaginary intersection point of the shoulder reference, is the shoulder longitudinal point. The arc passing through the shoulder longitudinal point and tangent to the reference forming surface at the shoulder reference tangent point is the shoulder tangent point side arc. Any position on the reference forming surface, between the shoulder reference tangent point and the imaginary intersection point of the shoulder reference, is the shoulder transverse point. The intersection point of the normal to the reference forming surface passing through the shoulder transverse point and the shoulder tangent point side arc is the shoulder middle boundary point. The arc passing through the shoulder reference boundary point and tangent to the shoulder boundary side arc at the shoulder middle boundary point is the shoulder boundary side arc. The contour of the shoulder land surface forming portion, from the shoulder reference tangent point to the shoulder mid-boundary point, is represented by an arc on the shoulder tangent point side, and the contour from the shoulder mid-boundary point to the shoulder reference boundary point is represented by an arc on the shoulder boundary side. The distance from the shoulder reference imaginary intersection point to the shoulder longitudinal point is the same as the distance from the reference imaginary intersection point to the longitudinal point. The distance from the shoulder reference imaginary intersection point to the shoulder transverse point is the same as the distance from the reference imaginary intersection point to the transverse point.

[0019] Preferably, in the mold for the tire, the tread has a top that includes the tread surface, and the Mooney viscosity of the uncured rubber used for the top is 80 or higher.

[0020] One aspect of the present invention is a tire manufacturing method comprising the steps of pressurizing and heating a green tire using the tire mold described above.

[0021] One aspect of the present invention provides a tire having a tread surface that contacts the road surface. At least two circumferential grooves are etched into the tread to form at least three land portions. The tread surface includes the at least two circumferential grooves and the outer surfaces of the at least three land portions, i.e., at least three land surfaces. In this tire, a surface having a profile represented by at least one arc and tangent to the three land surfaces arranged axially across the circumferential grooves is a reference surface of the tread surface. One of the three land surfaces, located between two of the circumferential grooves, is a curved land surface. The circumferential groove has a wall on the side of the curved land surface, i.e., a reference wall, and a wall opposite to the reference wall, i.e., an opposing wall. The point of tangency between the curved land surface and the reference surface is a reference tangency point. The boundary between the reference wall and the curved land surface is a reference boundary point. The intersection of an imaginary line extending from the reference boundary point toward the reference surface and the reference surface is a reference imaginary intersection point. The profile of the curved land surface is represented by one or more arcs. The reference boundary point is located inside the reference surface. When one circumferential groove has a small cross-sectional area and the other circumferential groove has a large cross-sectional area, the distance from the imaginary intersection point of the reference point to the reference boundary point on the side of one circumferential groove is shorter, and the distance from the imaginary intersection point of the reference point to the reference boundary point on the side of the other circumferential groove is longer.

[0022] According to the tire mold and tire manufacturing method of the present invention, the tire's contact patch shape and contact pressure distribution can be optimized. Furthermore, the tire obtained by this tire mold and tire manufacturing method has an appropriate contact patch shape and contact pressure distribution, thus improving handling stability and wear resistance. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view showing a portion of a tire according to one embodiment of the present invention.

[0024] Figure 2 It means Figure 1 A cross-sectional view of a portion of a tire.

[0025] Figure 3 This is a cross-sectional view showing a portion of a tire mold according to one embodiment of the present invention.

[0026] Figure 4 It means Figure 3 A cross-sectional view of a portion of the mold.

[0027] Figure 5 It means to use with Figure 4 A schematic diagram of an example of the contact patch shape of a tire manufactured by a mold with the structure shown.

[0028] Figure 6 It means to use with Figure 4 The graph shows an example of the ground pressure distribution of a tire manufactured using a mold with the structure shown.

[0029] Figure 7 It means Figure 2 A cross-sectional view of a deformed example of the tire tread surface shown.

[0030] Figure 8 It means Figure 4 A cross-sectional view of a modified example of the tread forming surface shown.

[0031] Figure 9 This is a schematic diagram illustrating an example of the contact patch shape of a tire manufactured using existing molds.

[0032] Figure 10 This is a graph representing an example of the ground pressure distribution of a tire manufactured using existing molds.

[0033] Explanation of reference numerals: 2, 92… tire; 2r… green tire; 4, 94… tread; 14… cord reinforcement layer; 22, 96… tread surface; 24… base; 26… top; 34… belt; 36… belt; 40… groove; 42, 42s, 42m… circumferential groove; 44, 44s, 44m… land section; 46, 46s, 46m, 46B, 46f, 46n… Land surface; 48… Bottom of circumferential groove 42; 50, 50a, 50b… Wall of circumferential groove 42; 56, 98… Mold; 58, 100… Tread ring; 64, 102… Tread forming surface; 72… Cavity surface; 74… Raised bar; 76, 76B, 76f, 76n… Land surface forming part; 78… Top surface of raised bar 74; 80, 80a, 80b… Side surface of raised bar 74. Detailed Implementation

[0034] Hereinafter, the present invention will be described in detail with appropriate reference to the accompanying drawings and based on preferred embodiments.

[0035] In this disclosure, the state in which a tire is assembled into a standard rim, the tire's internal pressure is adjusted to the standard internal pressure, and no load is applied to the tire is referred to as the standard state. Unless otherwise specified, the dimensions and angles of all parts of the tire are measured in the standard state in this invention.

[0036] A standard rim refers to a rim specified in the tire's specifications. Standard rims are defined as "Standard Rim" in JATMA specifications, "Design Rim" in TRA specifications, and "Measuring Rim" in ETRTO specifications.

[0037] Standard tire pressure refers to the pressure specified in the tire's specifications. This includes the "maximum pressure" in JATMA specifications, the "maximum value" listed in TRA specifications ("TIRE LOAD LIMITS AT VARIOUS COLDINFLATION PRESSURES"), and the "INFLATION PRESSURE" in ETRTO specifications. For example, the standard tire pressure for passenger cars is 180 kPa.

[0038] Regular load refers to the load specified in the tire's specifications. The "maximum load capacity" in JATMA specifications, the "maximum value" listed in TRA specifications under "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and the "LOADCAPACITY" in ETRTO specifications are regular loads. For example, the regular load for passenger car tires is equivalent to 88% of the aforementioned loads.

[0039] Figure 1 This represents a portion of an inflatable tire 2 (hereinafter, sometimes simply referred to as "tire 2") according to one embodiment of the present disclosure. The tire 2 is mounted on a passenger vehicle.

[0040] Figure 1 This represents a portion of the cross-section of tire 2 along a plane containing the axis of rotation of tire 2. Figure 1 The left-right direction is the axial direction of tire 2, and the up-down direction is the radial direction of tire 2. Figure 1 The direction perpendicular to the plane of the paper is the circumferential direction of tire 2. Figure 1 In the diagram, the dashed line CL represents the equatorial plane of tire 2.

[0041] The tire 2 comprises: a tread 4, a pair of sidewalls 6, a pair of beaded sections 8, a pair of beaded sections 10, a carcass 12, a cord reinforcement layer 14, a pair of anti-friction cloths 16, an inner liner 18, and a pair of rubber reinforcement layers 20.

[0042] The outer surface of the tread 4 is the tread surface 22. The tread 4 contacts the road surface at the tread surface 22. The tread 4 has a tread surface 22 that contacts the road surface. The tread 4 is located radially outside the cord reinforcement layer 14.

[0043] The tread 4 has a base 24 and a top 26. The base 24 forms the radially inner portion of the tread 4. The base 24 is made of cross-linked rubber with heat generation in mind. The top 26 is located radially outer of the base 24. In this tire 2, the top 26 is in contact with the road surface. The outer surface of the top 26 is the aforementioned tread surface 22. The top 26 is made of cross-linked rubber with wear resistance and grip performance in mind. The tread 4 may also consist only of the top 26.

[0044] Each sidewall 6 extends radially inward from the end of the tread 4 along the tire body 12. The sidewall 6 is made of cross-linked rubber.

[0045] Each edge portion 8 is located radially inward from the side wall 6. Although not shown, the edge portion 8 contacts the rim (not shown). The edge portion 8 is made of cross-linked rubber with wear resistance in mind.

[0046] Each bead 10 is located axially inside the bead portion 8. Each bead 10 has a core 28 and a triangular rubber 30. The core 28 contains steel wire. The triangular rubber 30 is located radially outside the core 28. The triangular rubber 30 is made of a cross-linked rubber with high rigidity. Figure 1 As shown, the size of this triangular adhesive 30 is smaller than that of the previous triangular adhesive.

[0047] Although not illustrated, the core 28 can also be composed of two cores arranged axially. In this case, the carcass ply described later is not folded back around the core 28, but rather the ends of the carcass ply are clamped between the two cores.

[0048] The tire carcass 12 is located inside the tread 4, a pair of sidewalls 6, and a pair of bead portions 8. The tire carcass 12 spans one bead 10 and the other bead 10. The tire carcass 12 has a radial structure. The tire carcass 12 includes at least one carcass cord 32. The tire carcass 12 of the tire 2 is composed of a single carcass cord 32. The carcass cord 32 is folded back around the core 28 of each bead 10. Although not shown, the carcass cord 32 comprises a plurality of arranged cords.

[0049] The cord reinforcement layer 14 includes a belt 34 and a strap 36. The belt 34 forms the inner portion of the cord reinforcement layer 14, and the strap 36 forms the outer portion of the cord reinforcement layer 14. The cord reinforcement layer 14 may also be composed of only the belt 34 or only the strap 36.

[0050] The belt 34 is laminated to the tire carcass 12 radially inside the tread 4. The belt 34 consists of at least two layers of belt plies 38 laminated radially. The belt 34 of the tire 2 consists of two layers of belt plies 38. Although not shown, each layer of belt plies 38 contains a plurality of cords arranged in a specific pattern. These cords are inclined relative to the equatorial plane. The cords are made of steel.

[0051] The belt 36 is located radially inside the tread 4. The belt 36 is located radially between the tread 4 and the belt 34. The belt 36 of the tire 2 consists of a full belt 36f and a pair of end belts 36e located outside the full belt 36f. The belt 36 may also consist only of the full belt 36f, or only of the pair of end belts 36e.

[0052] Although not illustrated, the belt 36 includes cords. In both the full belt 36f and the end belts 36e, the cords are wound in a spiral shape circumferentially. The cords, made of organic fibers, are used as the cords of the belt 36.

[0053] Each anti-friction cloth 16 is located radially inside the bead 10. Although not shown, the anti-friction cloth 16 contacts the rim. The anti-friction cloth 16 is composed of cloth and rubber impregnated therein. The anti-friction cloth 16 can also be constructed from components made of cross-linked rubber.

[0054] The inner liner 18 is located inside the tire carcass 12. The inner liner 18 forms the inner surface of the tire 2. The inner liner 18 is made of cross-linked rubber with low air permeability.

[0055] Each rubber reinforcing layer 20 is located axially outside the triangular rubber 30. The rubber reinforcing layer 20 is located between the tire body 12 and the edge portion 8. The rubber reinforcing layer 20 is made of cross-linked rubber. In this tire 2, the material of the rubber reinforcing layer 20 is the same as that of the triangular rubber 30. Alternatively, the rubber reinforcing layer 20 may not be provided in the tire 2. In this case, a triangular rubber of conventional size is used.

[0056] like Figure 1 As shown, grooves 40 are engraved on the tread 4 (specifically the top 26) of the tire 2. This forms the tread pattern. Figure 1 The groove 42 of the tire 2 shown is part of the groove 40 that forms the tread pattern. This groove 42 extends circumferentially. This groove 42 is a circumferential groove. Appropriately set according to the specifications of the tire 2, the circumferential groove 42 has a groove width of 9 mm or more and 20 mm or less. The circumferential groove 42 has a groove depth of 5 mm or more and 15 mm or less. The groove width is expressed as the distance from one edge of the groove 40 to the other edge. The groove depth is expressed as the distance from the edge to the bottom. In the case where the edges are rounded, the groove width and depth are determined based on an imaginary edge obtained assuming the edges are not rounded.

[0057] Figure 1 This illustrates an example where multiple circumferential grooves 42 etched on the tread 4 are symmetrically arranged with respect to the equatorial plane. These circumferential grooves 42 can also be arranged asymmetrically with respect to the equatorial plane.

[0058] The tire 2 has at least two circumferential grooves 42 etched into its tread 4. This forms at least three land portions 44 on the tread 4. In the tire 2, the circumferential grooves 42 are part of the tread surface 22. The tread surface 22 includes the outer surface of at least two circumferential grooves 42 and at least three land portions 44, i.e., at least three land surfaces 46. In the tread surface 22, the at least three land surfaces 46 are arranged axially, separated by the circumferential grooves 42.

[0059] exist Figure 1The tread 4 shown has three circumferential grooves 42. The outermost circumferential groove 42 in the axial direction is the shoulder circumferential groove 42s. The circumferential groove 42 located next to the shoulder circumferential groove 42s is the middle circumferential groove 42m. In this tire 2, the middle circumferential groove 42m is located on the equator. The middle circumferential groove 42m is also referred to as the crown circumferential groove.

[0060] In this tire 2, the shoulder circumferential groove 42s has the same depth as the intermediate circumferential groove 42m. In this tire 2, the shoulder circumferential groove 42s may be shallower than the intermediate circumferential groove 42m, or the intermediate circumferential groove 42m may be shallower than the shoulder circumferential groove 42s. When comparing two circumferential grooves 42, if the ratio of the depth of one circumferential groove 42 to the depth of the other circumferential groove 42 is 0.9 or more and 1.1 or less, the two circumferential grooves 42 are judged to have equal depths.

[0061] In this tire 2, four land portions 44 are formed by etching three circumferential grooves 42 arranged axially on the tread 4. The land portions 44 located axially on the outer side are called shoulder land portions 44s. The land portion 44 located axially inside the shoulder land portion 44s is called the middle land portion 44m. The middle land portion 44m, being located in the central portion of the tread 4, is also called the crown land portion. In this tire 2, the four land portions 44 formed on the tread 4 include a pair of middle land portions 44m and a pair of shoulder land portions 44s.

[0062] Figure 2 express Figure 1 A portion of the tread 4 shown. Figure 2 In the diagram, the left-right direction is the axial direction of tire 2, and the up-down direction is the radial direction of tire 2. The direction perpendicular to the plane of the paper is the circumferential direction of tire 2. Figure 2 The outline of the tread surface 22 is schematically shown in the figure.

[0063] The land portion 44 of the tire 2 includes a land portion 44 with a rounded corner shape and a land surface 46. Figure 2 For ease of explanation, the shape of the land surface 46 with rounded corners is exaggerated.

[0064] In this tire 2, the shoulder circumferential groove 42s is located between the land surface 46s (hereinafter referred to as the shoulder land surface) of the shoulder land portion 44s and the land surface 46m (hereinafter referred to as the intermediate land surface) of the middle land portion 44m. The circumferential groove 42 between the left and right intermediate land surfaces 46m is the intermediate circumferential groove 42m. Figure 2In the diagram, the land surface 46 on the left is the middle land surface 46m. The middle circumferential groove 42m is located next to this middle land surface 46m. Another middle land surface 46m is located next to the middle circumferential groove 42m. The shoulder circumferential groove 42s is located next to this middle land surface 46m. The shoulder land surface 46s is located next to the shoulder circumferential groove 42s. That is, the three land surfaces 46 are arranged axially, separated by circumferential grooves 42.

[0065] exist Figure 2 In the three land surfaces 46 arranged axially along the circumferential groove 42, the land surface 46 located between two circumferential grooves 42, i.e., the intermediate land surface 46m of one side, has an outwardly protruding shape. This intermediate land surface 46m is also referred to as the curved land surface 46B. The land surface 46 located next to the curved land surface 46B, separated by the intermediate circumferential groove 42m, i.e., the intermediate land surface 46m of the other side, is also referred to as the first land surface 46f. In this case, the intermediate circumferential groove 42m is also referred to as the first circumferential groove 42f. The land surface 46 located next to the curved land surface 46B, separated by the shoulder circumferential groove 42s, i.e., the shoulder land surface 46s, is also referred to as the second land surface 46n. In this case, the shoulder circumferential groove 42s is also referred to as the second circumferential groove 42n.

[0066] In this tire 2, the cross-sectional area of ​​the first circumferential groove 42f is smaller than the cross-sectional area of ​​the second circumferential groove 42n. The first circumferential groove 42f has a smaller cross-sectional area, and the second circumferential groove 42n has a larger cross-sectional area. In this tire 2, the cross-sectional area of ​​the first circumferential groove 42f may also be larger than the cross-sectional area of ​​the second circumferential groove 42n, or the cross-sectional areas of the first circumferential groove 42f and the second circumferential groove 42n may be the same.

[0067] In this tire 2, if the ratio of the cross-sectional area of ​​one circumferential groove 42 to the cross-sectional area of ​​the other circumferential groove 42 is greater than 0.95 and less than 1.05, the two adjacent circumferential grooves 42 are considered to have equal cross-sectional areas. The method for calculating the cross-sectional area will be described later.

[0068] exist Figure 2 In this tire 2, the double-dotted line TBL is the reference plane of the tread surface 22. This reference plane TBL of the tread surface 22 represents an imaginary tread surface assuming there are no grooves 40 in the tread 4. In this tire 2, the surface having a profile represented by at least one arc and tangent to three land surfaces 46 arranged axially across circumferential grooves 42 is the reference plane TBL of the tread surface 22. Figure 2 In the middle, the reference plane TBL of the tread surface 22 is tangent to the first land surface 46f, the curved land surface 46B and the second land surface 46n.

[0069] Although not illustrated, when the outline of the reference plane TBL is represented by multiple arcs arranged axially, the outline of the reference plane TBL is formed such that one arc is tangent to another arc located next to it at the boundary between the two arcs, and the arc located inside in the axial direction has a larger radius than the arc located outside. In this case, one arc and another arc may also be connected by a straight line tangent to the two arcs.

[0070] The tire 2 is assembled into a standard rim, and the internal pressure of the tire 2 is adjusted to 5% of the standard internal pressure without applying any load to the tire 2; this state is called the reference state. The profile of the tread surface 22 of this tire 2 is represented using the profile of the tread surface 22 in the reference state or the profile of the tread forming surface of the mold described later. Alternatively, if the profile structure of the tread surface 22 is unclear, for example, the profile of the reference plane TBL of the tread surface 22 can be determined based on the profile obtained by analyzing cross-sectional image data of the tire 2 in the reference state taken using X-ray computed tomography (hereinafter referred to as X-ray CT), or shape data of the tread surface 22 of the tire 2 in the reference state measured using a profile measuring instrument with a laser displacement gauge (not shown). In this case, the profile of the reference plane TBL of the tread surface 22 is represented by a single arc tangent to the three land surfaces 46 arranged axially.

[0071] The circumferential ditch 42 has a bottom 48 and a pair of walls 50. Figure 2 In the attached figure, reference numeral Bt represents the boundary between wall 50 and land surface 46. This boundary Bt is also referred to as the boundary point. The double-dotted line Lt is a straight line extending from the boundary point Bt towards the reference plane TBL, and tangent to the outline of wall 50 at the boundary point Bt. This straight line Lt is an imaginary line of wall 50. Reference numeral Vt represents the intersection of the imaginary line Lt and the reference plane TBL. The intersection point Vt is also referred to as the imaginary intersection point.

[0072] In this tire 2, the cross-sectional area of ​​the circumferential groove 42 is represented by the area of ​​the region surrounded by one wall 50, bottom 48, the other wall 50, the imaginary line Lt of the other wall 50, the reference plane TBL, and the imaginary line Lt of one wall 50.

[0073] As described above, the curved land surface 46B is located between two circumferential trenches 42. In the circumferential trenches 42 located beside the curved land surface 46B, the wall 50 on the side of the curved land surface 46B is also referred to as the reference wall 50a. The wall 50 opposite to the reference wall 50a is also referred to as the opposing wall 50b. The circumferential trenches 42 located beside the curved land surface 46B have the wall 50 on the side of the curved land surface 46B, i.e., the reference wall 50a, and the wall 50 opposite to the reference wall 50a, i.e., the opposing wall 50b.

[0074] exist Figure 2 In the attached drawing, reference BB1t represents the boundary between the reference wall 50a (hereinafter referred to as the first reference wall) of the first circumferential trench 42f and the curved land surface 46B. The boundary BB1t is a reference boundary point (hereinafter referred to as the first reference boundary point). The double-dotted line BL1t is an imaginary line of the first reference wall 50a. Reference BB1t represents the imaginary intersection point indicated by the intersection of the imaginary line BL1t of the first reference wall 50a and the reference surface TBL. The imaginary intersection point BV1t is a reference imaginary intersection point (hereinafter referred to as the first reference imaginary intersection point). The double-arrow Xd1t is the distance from the first reference imaginary intersection point BV1t to the first reference boundary point BB1t. This distance Xd1t is measured along the imaginary line BL1t of the first reference wall 50a.

[0075] exist Figure 2 In the attached diagram, reference BB2t represents the boundary between the reference wall 50a (hereinafter referred to as the second reference wall) of the second circumferential trench 42n and the curved land surface 46B. The boundary BB2t is a reference boundary point (hereinafter referred to as the second reference boundary point). The double-dotted line BL2t is an imaginary line of the second reference wall 50a. Reference BB2t represents the imaginary intersection point indicated by the intersection of the imaginary line BL2t of the second reference wall 50a and the reference surface TBL. The imaginary intersection point BV2t is a reference imaginary intersection point (hereinafter referred to as the second reference imaginary intersection point). The double-arrow Xd2t represents the distance from the second reference imaginary intersection point BV2t to the second reference boundary point BB2t. This distance Xd2t is measured along the imaginary line BL2t of the second reference wall 50a.

[0076] The tire 2 described above is manufactured as follows. Although not detailed, in the manufacture of this tire 2, an unvulcanized rubber composition (hereinafter also referred to as unvulcanized rubber) is prepared for use in the elements constituting the tire 2, such as the tread 4, sidewall 6, and bead 10. The unvulcanized rubber is obtained by mixing the base rubber and chemicals using a mixing mill (not shown) such as a Banbury mixer.

[0077] Examples of base rubbers include natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), ethylene propylene diene monomer (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and butyl rubber (IIR). Examples of chemicals include reinforcing agents such as carbon black and silica, plasticizers such as aromatic oils, fillers such as zinc oxide, lubricants such as stearic acid, anti-aging agents, processing aids, sulfur, and vulcanization accelerators. Although not described in detail, the selection of base rubbers and chemicals, as well as the content of the selected chemicals, are appropriately determined according to the specifications of the constituent elements of the rubber used.

[0078] In the manufacture of this tire 2, the shape of uncured rubber is adjusted in a rubber molding machine (not shown) such as an extruder to prepare preforms of tire components. In a tire forming machine (not shown), the preforms such as tread 4, sidewall 6, and bead 10 are assembled to prepare an uncured tire 2 (hereinafter also referred to as a green tire).

[0079] In the manufacture of tire 2, a green tire is placed into a mold in a vulcanizing machine (not shown). The green tire is pressurized and heated within the mold to obtain tire 2. Tire 2 is a vulcanized molded product of the green tire.

[0080] The manufacturing method of this tire 2 includes a process of preparing a green tire and a process of pressurizing and heating the green tire using a mold. In addition, although not described in detail, there are no particular restrictions on vulcanization conditions such as temperature, pressure, and time in the manufacturing of this tire 2, and ordinary vulcanization conditions can be used.

[0081] exist Figure 3 The image shows a portion of a cross-section of a tire mold 56, cut along a plane including the axis of rotation of the tire 2. This mold 56 is used for... Figure 1 The manufacturing process of tire 2 is shown. Figure 3 In the diagram, the left-right direction is the radial direction of tire 2, and the up-down direction is the axial direction of tire 2. The direction perpendicular to this plane of the paper is the circumferential direction of tire 2. The dotted line CL is the equatorial plane of tire 2. For ease of explanation, the dimensions of mold 56 will be expressed using the dimensions of tire 2 below.

[0082] The mold 56 includes a tread ring 58, a pair of side plates 60, and a pair of bead rings 62. The mold 56 is a dividing mold. Figure 3 In the middle, the mold 56 is in a state where the tread ring 58, a pair of side plates 60 and a pair of bead rings 62 are combined, that is, in a closed state.

[0083] The tread ring 58 forms the radially outer portion of the mold 56. The tread ring 58 has a tread forming surface 64 on its inner surface. The tread forming surface 64 shapes the tread surface 22 of the tire 2 on the outer surface of the green tire 2r. The tread ring 58 of the mold 56 is composed of a plurality of sector-shaped elements 66. These sector-shaped elements 66 are arranged in a ring.

[0084] Each sideplate 60 is located radially inside the tread ring 58. The sideplate 60 is connected to the end of the tread ring 58. The sideplate 60 has a sidewall forming surface 68 on its inner surface. The sidewall forming surface 68 is shaped on the outer surface of the green tire 2r to the sidewall of the tire 2.

[0085] Each bead ring 62 is located radially inside the side plate 60. The bead ring 62 is connected to the end of the side plate 60. The bead ring 62 has a bead forming surface 70 on its inner surface. The bead forming surface 70 is shaped on the outer surface of the green tire 2r towards the bead 10 portion of the tire 2, specifically the portion that fits into the rim.

[0086] In this mold 56, a cavity surface 72 for shaping the outer surface of the tire 2 is formed by the combination of multiple fan-shaped parts 66, a pair of side plates 60, and a pair of bead rings 62. The cavity surface 72 is composed of a tread forming surface 64, a pair of sidewall forming surfaces 68, and a pair of bead forming surfaces 70.

[0087] Although not illustrated, during the pressurization and heating process, the green tire 2r is pressed against the cavity surface 72 of the mold 56 by a rigid core or an inflated air bladder. This shapes the outer surface of the tire 2.

[0088] Figure 4 Indicates formation Figure 3 The cross-section of a portion of the tread ring 58 of the mold 56 shown. Figure 4 The outline of the tread forming surface 64, which shapes the tread surface 22, is schematically shown. Figure 4 In the diagram, the left-right direction is the axial direction of tire 2, and the up-down direction is the radial direction of tire 2. The direction perpendicular to the plane of the paper is the circumferential direction of tire 2.

[0089] As described above, the tread surface 22 of the tire 2 includes at least two circumferential grooves 42 and an outer surface of at least three land portions 44, i.e., at least three land surfaces 46. Therefore, in the mold 56, the tread forming surface 64 that shapes the tread surface 22 has at least two ridges 74 forming at least two circumferential grooves 42 and at least three land surface forming portions 76 forming at least three land surfaces 46.

[0090] In the mold 56, the protrusion 74 that shapes the first circumferential groove 42f is the first protrusion 74f. The protrusion 74 that shapes the second circumferential groove 42n is the second protrusion 74n.

[0091] As described above, in this mold 56, the cross-sectional area of ​​the first circumferential groove 42f is smaller than the cross-sectional area of ​​the second circumferential groove 42n. The cross-sectional area of ​​the first convex 74f is smaller than the cross-sectional area of ​​the second convex 74n. The first convex 74f has a smaller cross-sectional area, and the second convex 74n has a larger cross-sectional area.

[0092] In this mold 56, the land surface forming part 76 that shapes the curved land surface 46B is the curved land surface forming part 76B. The land surface forming part 76 that shapes the first land surface 46f is the first land surface forming part 76f. The land surface forming part 76 that shapes the second land surface 46n is the second land surface forming part 76n.

[0093] exist Figure 4 In the paper, the first ridge 74f is located next to the first land surface forming portion 76f. The curved land surface forming portion 76B is located next to the first ridge 74f. The second ridge 74n is located next to the curved land surface forming portion 76B. The second land surface forming portion 76n is located next to the second ridge 74n. That is, in the axial direction, the three land surface forming portions 76 are arranged with the ridges 74 apart. The land surface forming portion 76 located between the two ridges 74 is the curved land surface forming portion 76B. The two land surface forming portions 76 located next to the curved land surface forming portion 76B are the first land surface forming portion 76f and the second land surface forming portion 76n.

[0094] The land surface forming portion 76 included in the tread forming surface 64, located axially on the outer side, is the shoulder land surface forming portion 76s that shapes the shoulder land surface 46s. In the mold 56, the curved land surface forming portion 76B, one of the three land surface forming portions 76 arranged axially with ridges 74, is the intermediate land surface forming portion 76m that shapes one intermediate land surface 46m. The first land surface forming portion 76f, located next to the curved land surface forming portion 76B, is the intermediate land surface forming portion 76m that shapes another intermediate land surface 46m. The first ridge 74f, located between the first land surface forming portion 76f and the curved land surface forming portion 76B, is the intermediate ridge 74m that shapes the intermediate circumferential groove 42m. The second land surface forming portion 76n, located next to the curved land surface forming portion 76B, is the shoulder land surface forming portion 76s. The second ridge 74n, located between the second land surface forming section 76n and the curved land surface forming section 76B, is a tire shoulder ridge 74s that shapes the tire shoulder circumferential groove 42s.

[0095] exist Figure 4 In the mold 56, the double-dotted line FBL is the reference forming surface of the tread forming surface 64. This reference forming surface FBL of the tread forming surface 64 corresponds to the reference surface TBL of the aforementioned tread surface 22. In this mold 56, the surface having a profile represented by at least one arc and tangent to the three land surface forming portions 76 arranged axially with ridges 74 is the reference forming surface FBL of the tread forming surface 64. Figure 4In the middle, the reference forming surface FBL of the tread forming surface 64 is tangent to the first land surface forming part 76f, the curved land surface forming part 76B and the second land surface forming part 76n from the left side of the paper.

[0096] Although not illustrated, when the outline of the reference forming surface FBL is represented by a plurality of arcs arranged along the axial direction, the outline of the reference forming surface FBL is formed in such a way that one arc and another arc next to the one arc are tangent at the boundary between the two arcs, and the arc located inside in the axial direction has a radius larger than that of the arc located outside.

[0097] The convex strip 74 has a top surface 78 and a pair of side surfaces 80. Figure 4 In the attached drawing, reference numeral Bm represents the boundary between the side surface 80 and the land surface forming section 76. This boundary Bm is also referred to as the boundary point. The double-dotted line Lm is a straight line extending from the boundary point Bm toward the reference forming surface FBL, and tangent to the outline of the side surface 80 at the boundary point Bm. This straight line Lm is an imaginary line of the side surface 80. Reference numeral Vm represents the intersection of the imaginary line Lm and the reference forming surface FBL. The intersection point Vm is also referred to as the imaginary intersection point.

[0098] In this mold 56, the cross-sectional area of ​​the protrusion 74 is represented by the area of ​​the region surrounded by one side surface 80, the top surface 78, the other side surface 80, the imaginary line Lm of the other side surface 80, the reference forming surface FBL, and the imaginary line Lm of one side surface 80.

[0099] As described above, the curved land surface forming portion 76B is located between the two protrusions 74. The side 80 on the side of the protrusion 74 adjacent to the curved land surface forming portion 76B is also referred to as the reference side 80a. The side 80 on the opposite side of the reference side 80a is also referred to as the dorsal side 80b. The protrusion 74 adjacent to the curved land surface forming portion 76B has the side 80 on the side of the curved land surface forming portion 76B, i.e., the reference side 80a, and the side 80 on the opposite side of the reference side 80a, i.e., the dorsal side 80b.

[0100] exist Figure 4In the attached drawing, reference numeral BB1m represents the boundary between the reference side surface 80a (hereinafter referred to as the first reference side surface) of the first convex strip 74f and the curved land surface forming portion 76B. The boundary BB1m is a reference boundary point (hereinafter referred to as the first reference boundary point). The double-dotted line BL1m is an imaginary line of the first reference side surface 80a. Reference numeral BV1m represents the imaginary intersection point represented by the intersection of the imaginary line BL1m of the first reference side surface 80a and the reference forming surface FBL. The imaginary intersection point BV1m is a reference imaginary intersection point (hereinafter referred to as the first reference imaginary intersection point). The double-arrow Xd1m represents the distance from the first reference imaginary intersection point BV1m to the first reference boundary point BB1m. This distance Xd1m is measured along the imaginary line BL1m of the first reference side surface 80a.

[0101] exist Figure 4 In the attached drawing, reference numeral BB2m represents the boundary between the reference side surface 80a (hereinafter referred to as the second reference side surface) of the second convex strip 74n and the curved land surface forming portion 76B. Boundary BB2m is a reference boundary point (hereinafter referred to as the second reference boundary point). The double-dotted line BL2m is an imaginary line of the second reference side surface 80a. Reference numeral BV2m represents the imaginary intersection point indicated by the intersection of the imaginary line BL2m of the second reference side surface 80a and the reference forming surface FBL. The imaginary intersection point BV2m is a reference imaginary intersection point (hereinafter referred to as the second reference imaginary intersection point). The double-arrow Xd2m represents the distance from the second reference imaginary intersection point BV2m to the second reference boundary point BB2m. This distance Xd2m is measured along the imaginary line BL2m of the second reference side surface 80a.

[0102] In this mold 56, the shape of the land surface forming section 76 controls the flow of unvulcanized rubber generated by pressing the ribs 74 against the green tire 2r. As described above, the circumferential groove 42 is etched into the top 26 of the tread 4. The ribs 74 of the tread forming surface 64 press against this top 26. In this mold 56, the flow of unvulcanized rubber for the top 26 generated by pressing the ribs 74 against the green tire 2r is controlled by the shape of the land surface forming section 76. The shape of this land surface forming section 76 will be described below.

[0103] [Outline of curved land surface forming section 76B]

[0104] The outline of the curved land surface forming portion 76B located between the two protrusions 74 will be described. As described above, the reference forming surface FBL of the tread forming surface 64 is tangent to the first land surface forming portion 76f, the curved land surface forming portion 76B, and the second land surface forming portion 76n included in the tread forming surface 64. Figure 4 In the attached drawing, reference numeral T1m represents the point of tangency between the curved land surface forming section 76B and the reference forming surface FBL. In this mold 56, the tangency point Tm is the reference tangency point.

[0105] In this mold 56, the outline of the curved land surface forming portion 76B is represented by one or more arcs. The aforementioned first reference boundary point BB1m is also the end point on the side of the first protrusion 74f of the curved land surface forming portion 76B. The aforementioned second reference boundary point BB2m is also the end point on the side of the second protrusion 74n of the curved land surface forming portion 76B. For example... Figure 4 As shown, the end BB1m of the first ridge 74f side of the curved land surface forming portion 76B is located radially inside the reference forming surface FBL of the tread forming surface 64. The end BB2m of the second ridge 74n side of the curved land surface forming portion 76B is also located radially inside the reference forming surface FBL.

[0106] During the manufacturing of tire 2, since the top 26 is pressed against the ribs 74, the uncured rubber on the top 26 flows toward the portion between the two ribs 74, namely the curved land surface forming portion 76B. In this mold 56, the contour of the curved land surface forming portion 76B is formed such that the ends BB1m and BB2m of the curved land surface forming portion 76B are located inside the reference forming surface FBL. Since the amount of uncured rubber flowing into the curved land surface forming portion 76B is limited, the flow of uncured rubber pressed against the ribs 74 is prevented from becoming disordered.

[0107] In this mold 56, as described above, the first protrusion 74f has a smaller cross-sectional area, and the second protrusion 74n has a larger groove cross-sectional area. The amount of unvulcanized rubber pressed onto the second protrusion 74n is greater than the amount of unvulcanized rubber pressed onto the first protrusion 74f. There is a concern that the flow of unvulcanized rubber on the first protrusion 74f side may differ from the flow of unvulcanized rubber on the second protrusion 74n side.

[0108] However, in this mold 56, the distance Xd2m from the second reference imaginary intersection point BV2m to the second reference boundary point BB2m on the side of the second protrusion 74n is longer than the distance Xd1m from the first reference imaginary intersection point BV1m to the first reference boundary point BB1m on the side of the first protrusion 74f. In other words, the distance Xd1m from the first reference imaginary intersection point BV1m to the first reference boundary point BB1m on the side of the first protrusion 74f is shorter, while the distance Xd2m from the second reference imaginary intersection point BV2m to the second reference boundary point BB2m on the side of the second protrusion 74n is longer. In this mold 56, the amount of unvulcanized rubber flowing into the curved land surface forming portion 76B is effectively limited on the side of the second protrusion 74n, which has a larger cross-sectional area. The flow of unvulcanized rubber on the side of the first protrusion 74f and the flow of unvulcanized rubber on the side of the second protrusion 74n are controlled evenly, so the flow of unvulcanized rubber is less likely to become disordered. In this mold 56, a curved land surface 46B reflecting the shape of the curved land surface forming portion 76B can be formed. Since the irregularity of the inner surface shape of the tread 4 is also suppressed, the inner surface of the tread 4 is formed with an appropriate shape.

[0109] exist Figure 5 The image shows an example of the contact patch shape of a tire 2 (size = 205 / 55R16) manufactured using this mold 56. Figure 5 In the center, the left-right direction corresponds to the axial direction of tire 2. The up-down direction corresponds to the circumferential direction of tire 2.

[0110] The contact patch shape is obtained by tracing the contours of each land portion 44 in the contact patch obtained by pressing the tire 2 against the road surface under a normal load applied to the tire 2 in its normal state using a tire contact patch shape measuring device (not shown). When obtaining the contact patch, the tire 2 is configured so that its axis is parallel to the road surface, and the aforementioned load is applied to the tire 2 in a direction perpendicular to the road surface. In this measuring device, the road surface is flat. During the contact patch measurement, the tire 2 is pressed against a flat road surface. Figure 9 The ground contact surface shape of the tires shown, which are manufactured using conventional molds, is obtained in the same way.

[0111] like Figure 5 As shown, in the contact surface shape of the tire 2 manufactured using this mold 56, the outer circumferential edge of the intermediate land portion 44m located between the shoulder circumferential groove 42s and the intermediate circumferential groove 42m is not as shown... Figure 9 The tire 2 shown, which is confirmed by tires manufactured using conventional molds to have an inwardly protruding outer edge in the central land area, is instead bulging outwards. The contact patch area is significantly increased, allowing the tire 2 to make more thorough contact with the road surface compared to tires manufactured using conventional molds. Based on this mold 56, the handling stability of the tire 2 can be further improved.

[0112] Figure 6 This shows an example of the ground pressure distribution of a tire 2 (size = 205 / 55R16) manufactured using mold 56. The vertical axis represents the ground pressure, and the horizontal axis represents the position of the ground plane in the ground width direction. Figure 6 In the image, the left side shows the ground pressure distribution of the middle land section at 44m, and the right side shows the ground pressure distribution of the tire shoulder land section at 44s.

[0113] The ground pressure distribution is obtained by pressing a tire 2 against the road surface using a tire ground pressure measuring device (not shown) under a normal load. When obtaining this ground pressure distribution, the tire 2 is configured with its axis parallel to the road surface, and the aforementioned load is applied to the tire 2 in a direction perpendicular to the road surface. In this measuring device, the road surface is flat. In the measurement of this ground pressure distribution, the tire 2 is pressed against a flat road surface. Figure 10 The ground pressure distribution of the tires manufactured using conventional molds, as shown, was obtained in the same manner. Furthermore, in this... Figure 6 In the diagram, the ground pressure distribution, represented by dashed lines, is the ground pressure distribution of a tire manufactured using this conventional mold.

[0114] like Figure 6 As shown, in the ground pressure distribution of the tire 2 manufactured using this mold 56, the increase in ground pressure at the edge of the central land portion 44m is greater than that of the tire 2 manufactured using this mold 56. Figure 10 As shown, the increase in ground pressure at the edge of the central land section, confirmed by tires manufactured using conventional molds, is suppressed. Figure 6 In the example shown, the ground pressure difference within the intermediate land section of 44m is suppressed to approximately 55kPa. Localized increases in ground pressure are significantly suppressed, and based on this mold 56, further improvements in the wear resistance of tire 2 can be achieved.

[0115] According to the mold 56 and the manufacturing method of the tire 2 using the mold 56, the shape of the tire 2's contact surface and the distribution of ground pressure can be optimized, thereby improving the handling stability and wear resistance of the tire 2.

[0116] exist Figure 4In the diagram, the double-headed arrow Wcm represents the distance from the first imaginary intersection point BV1m to the second imaginary intersection point BV2m. The distance Wcm is represented by the length of the line segment connecting the first and second imaginary intersection points BV1m and BV2m. The double-headed arrow Xw1m represents the distance from the first imaginary intersection point BV1m to the tangent point Tm. The distance Xw1m is represented by the length of the line segment connecting the first and second imaginary intersection points BV1m and Tm. The double-headed arrow Xw2m represents the distance from the second imaginary intersection point BV2m to the tangent point Tm. The distance Xw2m is represented by the length of the line segment connecting the second imaginary intersection point BV2m and Tm.

[0117] In this mold 56, the position of the tangent point Tm between the curved land surface forming part 76B and the reference forming surface FBL is preferably determined based on the cross-sectional area of ​​the protrusions 74 located on both sides of the curved land surface forming part 76B. Specifically, when the cross-sectional area of ​​the first protrusion 74f is set to Sam and the cross-sectional area of ​​the second protrusion 74n is set to Sbm, the distance Xw1m is preferably set in a manner that satisfies the following formula (1) expressed by the distance Xw1m, the distance Wcm, the cross-sectional area Sam, and the cross-sectional area Sbm.

[0118] Sam / (Sam+Sbm)×100-10≤Xw1m / Wcm×100≤Sam / (Sam+Sbm)×100+10…(1)

[0119] In this mold 56, since the cross-sectional area Sam of the first protrusion 74f is smaller than the cross-sectional area Sbm of the second protrusion 74n, the reference tangent point Tm is set on the side of the first reference boundary point BB1m. In this mold 56, the flow of uncured rubber towards the side of the first protrusion 74f, which has the smaller cross-sectional area, is promoted. In this mold 56, when the cross-sectional area Sam of the first protrusion 74f is larger than the cross-sectional area Sbm of the second protrusion 74n, the reference tangent point Tm is set on the side of the second reference boundary point BB2m. In this case, the flow of uncured rubber towards the side of the second protrusion 74n is promoted.

[0120] In this mold 56, the flow of unvulcanized rubber on the side of the first protrusion 74f and the flow of unvulcanized rubber on the side of the second protrusion 74n are controlled evenly. Since the flow of unvulcanized rubber is less prone to becoming disordered, a curved land surface 46B reflecting the shape of the curved land surface forming portion 76B can be formed. According to this mold 56 and the manufacturing method of the tire 2 using this mold 56, the shape of the tire 2's contact patch and the distribution of contact pressure can be optimized, thereby improving the handling stability and wear resistance of the tire 2.

[0121] In this mold 56, when the cross-sectional area of ​​the protrusion 74 located next to the curved land surface forming part 76B is set to Sm, the ratio of the distance Xdm from the reference imaginary intersection point BVm to the reference boundary point BBm to the cross-sectional area Sm of the protrusion 74 (Xdm / Sm) is preferably 0.0008 or more, and preferably 0.0040 or less.

[0122] By setting the ratio (Xdm / Sm) to 0.0008 or higher, the shape of the curved land surface forming portion 76B effectively helps to restrict the flow of uncured rubber pressed by the protrusions 74. Even if the cross-sectional areas of the protrusions 74 on both sides of the curved land surface forming portion 76B are different, the flow of the uncured rubber is less likely to become disordered. In this mold 56, a curved land surface 46B that reflects the shape of the curved land surface forming portion 76B can be formed. From this viewpoint, it is more preferable that the ratio (Xdm / Sm) is 0.0014 or higher, and even more preferable that it is 0.0020 or higher.

[0123] By setting the ratio (Xdm / Sm) to 0.0040 or less, the flow of the uncurved rubber pressed by the protrusions 74 is appropriately maintained. In this case, even if the cross-sectional areas of the protrusions 74 on both sides of the curved land surface forming portion 76B are different, the flow of the uncurved rubber is less likely to become disordered. In this mold 56, a curved land surface 46B reflecting the shape of the curved land surface forming portion 76B can be formed. From this point of view, the ratio (Xdm / Sm) is more preferably 0.0034 or less, and more preferably 0.0028 or less.

[0124] As described above, in this mold 56, the cross-sectional area Sam of the first ridge 74f is smaller than the cross-sectional area Sbm of the second ridge 74n. From the viewpoint that the flow of uncured rubber on the first protrusion 74f side and the flow of uncured rubber on the second protrusion 74n side can be controlled evenly even when the cross-sectional area Sam of the first protrusion 74f and the cross-sectional area Sbm of the second protrusion 74n are different, and the flow of uncured rubber is effectively suppressed from becoming disordered, on the first protrusion 74f side, the ratio of the distance Xd1m from the first reference imaginary intersection point BV1m to the first reference boundary point BB1m to the cross-sectional area Sam of the first protrusion 74f (Xd1m / Sam) is preferably 0.0008 or more and 0.0040 or less, and on the second protrusion 74n side, the ratio of the distance Xd2m from the second reference imaginary intersection point BV2m to the second reference boundary point BB2m to the cross-sectional area Sbm of the second protrusion 74n (Xd2m / Sbm) is preferably 0.0008 or more and preferably 0.0040 or less. In this case, the ratio (Xd1m / Sam) and the ratio (Xd2m / Sbm) are set with the same value.

[0125] As described above, the outline of the curved land surface forming portion 76B is represented by one or more arcs. Preferably, the outline of the curved land surface forming portion 76B is represented by an arc passing through a reference boundary point BBm and tangent to the reference forming surface FBL at a reference tangency point Tm. Specifically, it is preferably represented by an arc passing through a first reference boundary point BB1m and tangent to the reference forming surface FBL at a reference tangency point Tm, and an arc passing through a second reference boundary point BB2m and tangent to the reference forming surface FBL at a reference tangency point Tm. Thus, the flow of unvulcanized rubber on the side of the first rib 74f and the flow of unvulcanized rubber on the side of the second rib 74n are controlled evenly. Since the flow of unvulcanized rubber is less prone to disorder, a curved land surface 46B reflecting the shape of the curved land surface forming portion 76B can be formed in the mold 56. Based on the mold 56 and the manufacturing method of the tire 2 using the mold 56, the shape of the tire 2's contact patch and the distribution of contact pressure can be optimized, thereby improving the handling stability and wear resistance of the tire 2. Furthermore, when the cross-sectional area of ​​the first ridge 74f is equal to the cross-sectional area of ​​the second ridge 74n, the outline of the curved land surface forming portion 76B is represented by an arc.

[0126] [In the case where the ridge 74 located next to the curved land surface forming section 76B is the tire shoulder ridge 74s]

[0127] Regarding the case where the rib 74 located next to the curved land surface forming section 76B is a shoulder rib 74s, the explanation will take the case where the second rib 74n is the outermost rib 74 in the axial direction as an example. When the second rib 74n is the outermost rib 74 in the axial direction, by... Figure 4 The second land surface forming section 76n forms the shoulder land surface 46s of the tire 2. Hereinafter, this will be used... Figure 4 The outline of the second land surface forming part 76n, i.e. the land surface forming part 76s of the tire shoulder, which forms the land surface 46s of the tire shoulder will be explained.

[0128] In this mold 56, the second protrusion 74n is located between the shoulder land surface forming portion 76s and the curved land surface forming portion 76B. In this second protrusion 74n, the side surface 80 on the side of the curved land surface forming portion 76B is the reference side surface 80a, and the side surface 80 on the side of the shoulder land surface forming portion 76s is the back side surface 80b.

[0129] exist Figure 4 In the attached diagram, the reference numeral Tsm represents the point of tangency between the shoulder land surface forming portion 76s and the reference forming surface FBL. The tangency point Tsm is the shoulder reference tangency point. When the shoulder land surface forming portion 76s and the reference forming surface FBL are tangent by a line rather than a point, the shoulder reference tangency point Tsm is determined by the inner end of the tangent line between the shoulder land surface forming portion 76s and the reference forming surface FBL.

[0130] exist Figure 4 In the attached diagram, reference BBsm represents the boundary between the dorsal side surface 80b of the second convex rib 74n and the shoulder land surface forming portion 76s. Boundary BBsm is the shoulder reference boundary point. The double-dotted line BLsm is an imaginary line of the dorsal side surface 80b. Reference BBsm is the imaginary intersection point represented by the intersection of the imaginary line BLsm of the dorsal side surface 80b and the reference forming surface FBL. The imaginary intersection point BVsm is the shoulder reference imaginary intersection point. The double-headed arrow Xdsm is the distance from the shoulder reference imaginary intersection point BVsm to the shoulder reference boundary point BBsm. This distance Xdsm is measured along the imaginary line BLsm of the dorsal side surface 80b. The double-headed arrow Xwsm is the distance from the shoulder reference imaginary intersection point BVsm to the shoulder reference tangent point Tsm. The distance Xwsm is represented by the length of the line segment connecting the shoulder reference imaginary intersection point BVsm and the shoulder reference tangent point Tsm.

[0131] In this mold 56, the profile of the shoulder land surface forming portion 76s, from the shoulder reference boundary point BBsm to the shoulder reference tangent point Tsm, is configured to be the same as the profile of the curved land surface forming portion 76B, from the second reference boundary point BB2m to the reference tangent point Tm. Specifically, the distance Xdsm from the shoulder reference imaginary intersection point BVsm to the shoulder reference boundary point BBsm is the same as the distance Xd2m from the second reference imaginary intersection point BV2m to the second reference boundary point BB2m. The distance Xwsm from the shoulder reference imaginary intersection point BVsm to the shoulder reference tangent point Tsm is the same as the distance Xw2m from the second reference imaginary intersection point BV2m to the reference tangent point Tm. Furthermore, the profile of the shoulder land surface forming portion 76s, from the shoulder reference boundary point BBsm to the shoulder reference tangent point Tsm, is represented by an arc passing through the shoulder reference boundary point BBsm and tangent to the reference forming surface FBL at the shoulder reference tangent point Tsm, in the same manner as the profile of the curved land surface forming portion 76B, from the second reference boundary point BB2m to the reference tangent point Tm.

[0132] In this mold 56, the shoulder reference boundary point BBsm is also the end of the second ridge 74n side of the shoulder land surface forming portion 76s. For example... Figure 4 As shown, the end BBsm of the second ridge 74n side of the shoulder land surface forming portion 76s is located radially inside the reference forming surface FBL of the tread forming surface 64.

[0133] During the manufacturing of tire 2, since the top 26 is pressed against the rib 74, the uncured rubber of the top 26 flows toward the axially outer portion of the second rib 74n, i.e., the portion forming the shoulder land portion 44s. In this mold 56, the outline of the shoulder land portion 76s is formed such that the end BBsm of the shoulder land portion 76s is located inside the reference plane FBL of the tread forming surface 64. Since the amount of uncured rubber flowing into the portion forming the shoulder land portion 44s is limited, the flow of uncured rubber pressed against the second rib 74n is less prone to becoming disordered. In this mold 56, the shoulder land portion 46s, reflecting the shape of the shoulder land portion 76s, is formed. Since the disorder of the inner surface shape of the tread 4 is also suppressed, the inner surface of the tread 4 is formed with an appropriate shape.

[0134] like Figure 5 As shown, in the contact surface shape of the tire 2 manufactured using this mold 56, the circumferential outer edge of the shoulder land portion 44s is not as... Figure 9 As shown, the tire shoulder land area, as confirmed by tires manufactured using conventional molds, does not have an inwardly protruding shape, but rather a bulging shape. The contact patch area is significantly increased, allowing this tire 2 to make more thorough contact with the road surface compared to tires manufactured using conventional molds. Based on this mold 56, the handling stability of the tire 2 can be further improved.

[0135] like Figure 6 As shown, in the ground pressure distribution of the tire 2 manufactured using this mold 56, the increase in ground pressure at the edge of the land portion 44s of the tire shoulder is greater than that of the tire 2 manufactured using this mold 56. Figure 10 As shown, the increase in ground pressure at the edge of the tire shoulder land portion, confirmed by tires manufactured using conventional molds, is suppressed. Figure 6 In the example shown, the ground pressure difference on the tire shoulder land portion within 44 seconds was suppressed to approximately 70 kPa. Localized increases in ground pressure were significantly suppressed, and based on this mold 56, further improvements in the wear resistance of tire 2 could be achieved.

[0136] Figure 1 The tire 2 shown is manufactured using the mold 56 described above, which has a tread forming surface 64. Next, the outline of the tread surface 22 shaped by the tread forming surface 64 will be described.

[0137] [Outline of curved land surface 46B]

[0138] Regarding the profile of the curved land surface 46B located between the two circumferential trenches 42, based on Figure 2The outline of the intermediate land surface 46m will be used for explanation. As mentioned above, the intermediate land surface 46m is the curved land surface 46B located between the first circumferential groove 42f, which is the intermediate circumferential groove 42m, and the second circumferential groove 42n, which is the shoulder circumferential groove 42s.

[0139] As described above, in this tire 2, the reference plane TBL of the tread surface 22 has a profile represented by at least one circular arc and is tangent to the curved land surface 46B, the first land surface 46f, and the second land surface 46n. Figure 2 In the attached diagram, reference numeral T1t represents the point of tangency between the curved land surface 46B and the reference surface TBL. In this tire 2, this point T1t is the first reference tangency point.

[0140] In this tire 2, the profile of the curved land surface 46B is represented by one or more circular arcs. The aforementioned first reference boundary point BB1t is also the end point on the first circumferential groove 42f side of the curved land surface 46B. The aforementioned second reference boundary point BB2t is also the end point on the second circumferential groove 42n side of the curved land surface 46B. For example... Figure 2 As shown, the end BB1t on the first circumferential groove 42n side of the curved land surface 46B is located radially inside the reference plane TBL of the tread surface 22. The end BB2t on the second circumferential groove 42n side of the curved land surface 46B is also located radially inside the reference plane TBL of the tread surface 22.

[0141] During the manufacturing of tire 2, since the top 26 is pressed against the first rib 74f and the second rib 74n, the uncured rubber on the top 26 flows toward the portion between the first rib 74f and the second rib 74n, i.e., the curved land surface forming portion 76B. In this tire 2, the contour of the curved land surface 46B is formed such that the ends BB1t and BB2t of the curved land surface 46B are located inside the reference plane TBL. Since the amount of uncured rubber flowing into the curved land surface forming portion 76B is limited, the flow of uncured rubber pressed against the first rib 74f and the second rib 74n can be prevented from becoming disordered.

[0142] As described above, in the mold 56 of the tire 2, the amount of unvulcanized rubber pressed against the second ridge 74n is greater than the amount of unvulcanized rubber pressed against the first ridge 74f. There is a concern that the flow of unvulcanized rubber on the first ridge 74f side may differ from the flow of unvulcanized rubber on the second ridge 74n side.

[0143] However, in this tire 2, the distance Xd2t from the second reference imaginary intersection point BV2t to the second reference boundary point BB2t on the second circumferential groove 42n side is longer than the distance Xd1t from the first reference imaginary intersection point BV1t to the first reference boundary point BB1t on the first circumferential groove 42f side. In other words, the distance Xd1t from the first reference imaginary intersection point BV1t to the first reference boundary point BB1t on the first circumferential groove 42f side is shorter, while the distance Xd2t from the second reference imaginary intersection point BV2t to the second reference boundary point BB2t on the second circumferential groove 42n side is longer. During the manufacturing of this tire 2, the amount of uncured rubber flowing into the curved land surface forming portion 76B on the second rib 74n side is effectively limited. The flow of uncured rubber on the side of the first ridge 74f and the flow of uncured rubber on the side of the second ridge 74n are controlled evenly, thus forming a curved land surface 46B that reflects the shape of the curved land surface forming portion 76B. Since the irregularity of the inner surface shape of the tread 4 is also suppressed, the inner surface of the tread 4 is formed with an appropriate shape.

[0144] As mentioned above, in Figure 5 In the contact surface shape of the tire 2 shown, the outer circumferential edge of the intermediate land portion 44m located between the shoulder circumferential groove 42s and the intermediate circumferential groove 42m is not as shown. Figure 9 The tire shown, which is confirmed by manufacturing tires using conventional molds, has a bulging shape instead of an inwardly protruding outer edge of the central land area. This significantly increases the contact area with the road surface, allowing for more complete contact compared to tires manufactured using conventional molds. This tire 2 further improves handling stability.

[0145] As mentioned above, in Figure 6 In the ground pressure distribution of tire 2 shown, the increase in ground pressure at the edge of the middle land portion 44m is greater than that of the tire 2. Figure 10 As shown, the increase in ground pressure at the edge of the central land area, as confirmed by tires manufactured using conventional molds, is suppressed. The localized increase in ground pressure is significantly suppressed, enabling further improvement in wear resistance for this tire 2.

[0146] In this tire 2, a suitable contact patch shape and contact pressure distribution can be obtained. This tire 2 can achieve improved handling stability and wear resistance.

[0147] exist Figure 2 In the diagram, the double arrow Wct represents the distance from the first imaginary intersection point BV1t to the second imaginary intersection point BV2t. The double arrow Xw1t represents the distance from the first imaginary intersection point BV1t to the tangent point Tt. The double arrow Xw2t represents the distance from the second imaginary intersection point BV2t to the tangent point Tt.

[0148] In this tire 2, the position of the reference tangent point Tt between the curved land surface 46B and the reference surface TBL is preferably determined based on the cross-sectional area of ​​the circumferential grooves 42 located on both sides of the curved land surface 46B. Specifically, when the groove cross-sectional area of ​​the first circumferential groove 42f is set as Sat and the groove cross-sectional area of ​​the second circumferential groove 42n is set as Sbt, the distance Xw1t is preferably set in a manner that satisfies the following formula (2) expressed using the distance Xw1t, the distance Wct, the groove cross-sectional area Sat, and the groove cross-sectional area Sbt.

[0149] Sat / (Sat+Sbt)×100-10≤Xw1t / Wct×100≤Sat / (Sat+Sbt)×100+10…(2)

[0150] In this tire mold 56, since the cross-sectional area Sat of the first circumferential groove 42f is smaller than the cross-sectional area Sbt of the second circumferential groove 42n, the reference tangent point Tt is set on the side of the first reference boundary point BB1t. In the manufacturing of this tire 2, the flow of uncured rubber towards the side of the first rib 74f, which has a smaller cross-sectional area, is promoted. In this tire 2, when the cross-sectional area Sat of the first circumferential groove 42f is larger than the cross-sectional area Sbt of the second circumferential groove 42n, the reference tangent point Tm is set on the side of the second reference boundary point BB2t. In this case, the flow of uncured rubber towards the side of the second rib 74n is promoted.

[0151] In the manufacture of this tire 2, since the flow of unvulcanized rubber on the first rib 74f side and the flow of unvulcanized rubber on the second rib 74n side are evenly controlled, a curved land surface 46B reflecting the shape of the curved land surface forming portion 76B can be formed. In this tire 2, an appropriate contact patch shape and contact pressure distribution can be obtained. This tire 2 can achieve improved handling stability and wear resistance.

[0152] In this tire 2, from the viewpoint of optimizing the contact patch shape and contact pressure distribution, the ratio (Xdt / St) of the distance Xdt from the reference hypothetical intersection point BVt to the reference boundary point BBt to the groove cross-sectional area St of the circumferential groove 42 is preferably 0.0008 or more, more preferably 0.0014 or more, and even more preferably 0.0020 or more. This ratio (Xdt / St) is preferably 0.0040 or less, more preferably 0.0034 or less, and even more preferably 0.0028 or less.

[0153] As described above, in this tire 2, the groove cross-sectional area Sat of the first circumferential groove 42f is smaller than the groove cross-sectional area Sbt of the second circumferential groove 42n. From the viewpoint that even when the cross-sectional area Sat of the first circumferential groove 42f and the cross-sectional area Sbt of the second circumferential groove 42n are different, the flow of uncured rubber on the first convex strip 74f side and the flow of uncured rubber on the second convex strip 74n side can be controlled in a balanced manner, and the disorder of the flow of uncured rubber can be effectively suppressed, on the first circumferential groove 42f side, the ratio of the distance Xd1t from the first reference imaginary intersection point BV1t to the first reference boundary point BB1t to the cross-sectional area Sat of the first circumferential groove 42f (Xd1t / Sat) is preferably 0.0008 or more and 0.0040 or less, and on the second circumferential groove 42n side, the ratio of the distance Xd2t from the second reference imaginary intersection point BV2t to the second reference boundary point BB2t to the cross-sectional area Sbt of the second circumferential groove 42n (Xd2t / Sbt) is preferably 0.0008 or more and preferably 0.0040 or less. In this case, the ratio (Xd1t / Sat) and the ratio (Xd2t / Sbt) are set with the same value.

[0154] As described above, the profile of the curved land surface 46B is represented by one or more circular arcs. In this tire 2, from the viewpoint of optimizing the contact surface shape and contact pressure distribution, the profile of the curved land surface 46B is more preferably represented by an arc passing through the first reference boundary point BB1t and tangent to the reference surface TBL at the reference tangency point Tt, and an arc passing through the second reference boundary point BB2t and tangent to the reference surface TBL at the reference tangency point Tt.

[0155] [In the case where the circumferential groove 42 located next to the curved land surface 46B is the shoulder circumferential groove 42s]

[0156] When the second circumferential groove 42n is the outermost shoulder circumferential groove 42s in the axial direction, Figure 2 The second land surface 46n forms the shoulder land surface 46s of tire 2. Hereinafter, using... Figure 2 The outline of the land surface 46s of the tire shoulder is described.

[0157] In this tire 2, the second circumferential groove 42n is located between the shoulder land surface 46s and the curved land surface 46B. In this second circumferential groove 42n, the wall 50 on the curved land surface 46B side is the reference wall 50a, and the wall 50 on the shoulder land surface 46s side is the opposing wall 50b.

[0158] exist Figure 2 In the attached diagram, the reference numeral Tst is the tangent point between the tire shoulder land surface 46s and the reference plane TBL. The tangent point Tst is the reference tangent point of the tire shoulder.

[0159] exist Figure 2In the attached diagram, reference BBst represents the boundary between the opposing wall 50b of the second circumferential groove 42n and the shoulder land surface 46s. Boundary BBst is the shoulder reference boundary point. The double-dotted line BLst is an imaginary line representing the opposing wall 50b. Reference BBst is an imaginary intersection point represented by the intersection of the imaginary line BLst of the opposing wall 50b and the reference plane TBL. The imaginary intersection point BVst is the shoulder reference imaginary intersection point. The double-headed arrow Xdst is the distance from the shoulder reference imaginary intersection point BVst to the shoulder reference boundary point BBst. This distance Xdst is measured along the imaginary line BLst of the opposing wall 50b. The double-headed arrow Xwst is the distance from the shoulder reference imaginary intersection point BVst to the shoulder reference tangent point Tst. The distance Xwst is represented by the length of the line segment connecting the shoulder reference imaginary intersection point BVst and the shoulder reference tangent point Tst.

[0160] In this tire 2, the profile of the shoulder land surface 46s, from the shoulder reference boundary point BBst to the shoulder reference tangent point Tst, is configured to be the same as the profile of the curved land surface 46B, from the second reference boundary point BB2t to the reference tangent point Tt. Specifically, the distance Xdst from the shoulder reference imaginary intersection point BVst to the shoulder reference boundary point BBst is the same as the distance Xd2t from the second reference imaginary intersection point BV2t to the second reference boundary point BB2t. The distance Xwst from the shoulder reference imaginary intersection point BVst to the shoulder reference tangent point Tst is the same as the distance Xw2t from the second reference imaginary intersection point BV2t to the reference tangent point Tt. Furthermore, the profile of the shoulder land surface 46s, from the shoulder reference boundary point BBst to the shoulder reference tangent point Tst, is represented by an arc passing through the shoulder reference boundary point BBst and tangent to the reference surface TBL at the shoulder reference tangent point Tst, in the same manner as the profile of the curved land surface 46B, from the second reference boundary point BB2t to the reference tangent point Tt.

[0161] In tire 2, the shoulder reference boundary point BBst is also the end of the second circumferential groove 42n on the shoulder land surface 46s. For example... Figure 2 As shown, the end BBst of the second circumferential groove 42n on the shoulder land surface 46s is located radially inside the reference plane TBL of the tread surface 22.

[0162] In the manufacturing of tire 2, since the top 26 is pressed against the rib 74, the uncured rubber of the top 26 flows toward the axially outer portion of the second rib 74n, that is, the portion forming the shoulder land portion 44s. In this tire 2, the outline of the shoulder land portion 46s is formed such that the end BBst of the shoulder land portion 46s is located inside the reference plane TBL of the tread surface 22. Since the amount of uncured rubber flowing into the portion forming the shoulder land portion 44s is limited, the flow of uncured rubber pressed against the second rib 74n is less prone to becoming disordered. In this tire 2, the shoulder land portion 46s is formed, reflecting the shape of the shoulder land portion forming portion 76s. Since the disorder of the inner surface shape of the tread 4 is also suppressed, the inner surface of the tread 4 is formed with an appropriate shape.

[0163] As mentioned above, in Figure 5 In the contact patch shape of tire 2 shown, the circumferential outer edge of the shoulder land portion 44s is not as shown. Figure 9 As shown, the tire shoulder land area, as confirmed by tires manufactured using conventional molds, does not have an inwardly protruding shape, but rather a bulging shape. The contact patch area is significantly increased, allowing this tire 2 to make more thorough contact with the road surface compared to tires manufactured using conventional molds. This tire 2 achieves further improvements in handling stability.

[0164] As mentioned above, in Figure 6 In the ground pressure distribution of tire 2 shown, the increase in ground pressure at the edge of the middle land portion 44m is greater than that of the tire 2. Figure 10 As shown, the increase in ground pressure at the edge of the central land area, as confirmed by tires manufactured using conventional molds, is suppressed. The localized increase in ground pressure is significantly suppressed, enabling further improvement in wear resistance for this tire 2.

[0165] [Second Implementation]

[0166] Figure 7 This shows a cross-section of the tread 94 of a tire 92 according to another embodiment of the present invention. Figure 7 The outline of the tread surface 96 is schematically shown in the diagram. Figure 7 In the diagram, the left-right direction is the axial direction of tire 92, and the up-down direction is the radial direction of tire 92. The direction perpendicular to the plane of the paper is the circumferential direction of tire 92.

[0167] Figure 7 The outline of the tread surface 96 shown is Figure 2 The diagram shows a modified example of the contour of the tread surface 22. Figure 7 In the outline of the tread surface 96 shown, and Figure 2 The portions of the same outline as the tread surface 22 shown are labeled with the same reference numerals, and their descriptions are omitted.

[0168] Figure 8 Indicates the formation used for Figure 7 The cross-section of the tread ring 100 is a portion of the mold 98 used to manufacture the tire 92 shown. Figure 8 The outline of the tread forming surface 102, which shapes the tread surface 96, is schematically shown. Figure 8 In the diagram, the left-right direction is the axial direction of tire 92, and the up-down direction is the radial direction of tire 92. The direction perpendicular to the plane of the paper is the circumferential direction of tire 92.

[0169] Figure 8 The outline of the tread forming surface 102 shown is Figure 4 The diagram shows a modified example of the profile of the tread forming surface 64. Figure 8 In the outline of the tread forming surface 102 shown, and with Figure 4 The portions of the same outline as the tread forming surface 64 shown are labeled with the same reference numerals, and their descriptions are omitted.

[0170] [Outline of curved land surface forming section 76B]

[0171] First of all, Figure 8 The outline of the curved land surface forming portion 76B included in the tread forming surface 102 will be described. In this tread forming surface 102, the outline of the curved land surface forming portion 76B is also represented by one or more arcs. From the viewpoint of obtaining a more suitable contact surface shape and contact pressure distribution, the outline of the curved land surface forming portion 76B in this tread forming surface 102 can be represented by the four arcs shown below.

[0172] exist Figure 8 In the attached drawing, reference numeral K1m is located on the imaginary line BL1m of the first reference side surface 80a of the first convex rib 74f, and is an arbitrary position between the first reference boundary point BB1m and the first reference imaginary intersection point BV1m. This position K1m is the longitudinal point (hereinafter referred to as the first longitudinal point). The double arrow Xk1m is the distance from the first reference imaginary intersection point BV1m to the first longitudinal point K1m. This distance Xk1m is measured along the imaginary line BL1m of the first reference side surface 80a. In this tread forming surface 102, the arc passing through the first longitudinal point K1m and tangent to the reference forming surface FBL at the reference tangency point Tm is the tangency point side arc (hereinafter referred to as the first tangency point side arc).

[0173] exist Figure 8In the attached drawing, reference numeral J1m is located on the reference forming surface FBL and is any position between the reference tangent point Tm and the first reference imaginary intersection point BV1m. This position J1m is a transverse point (hereinafter referred to as the first transverse point). The double arrow Xj1m is the distance from the first reference imaginary intersection point BV1m to the first transverse point J1m. This distance Xj1m is represented by the length of the line segment connecting the first reference imaginary intersection point BV1m and the first transverse point J1m. Reference numeral M1m is the intersection of the normal line through the reference forming surface FBL at the first transverse point J1m and the first tangent point side arc. This intersection point M1m is an intermediate boundary point (hereinafter referred to as the first intermediate boundary point). In this tread forming surface 102, the arc passing through the first reference boundary point BB1m and tangent to the first tangent point side arc at the first intermediate boundary point M1m is the boundary side arc (hereinafter referred to as the first boundary side arc).

[0174] exist Figure 8 In the attached diagram, reference numeral K2m is located on the imaginary line BL2m of the second reference side surface 80a of the second convex rib 74n, and is an arbitrary position between the second reference boundary point BB2m and the second reference imaginary intersection point BV2m. This position K2m is the longitudinal point (hereinafter referred to as the second longitudinal point). The double arrow Xk2m is the distance from the second reference imaginary intersection point BV2m to the second longitudinal point K2m. This distance Xk2m is measured along the imaginary line BL2m of the second reference side surface 80a. In this tread forming surface 102, the arc passing through the second longitudinal point K2m and tangent to the reference forming surface FBL at the reference tangency point Tm is the tangency point side arc (hereinafter referred to as the second tangency point side arc).

[0175] exist Figure 8 In the attached drawing, reference numeral J2m is located on the reference forming surface FBL and is an arbitrary position between the reference tangent point Tm and the second reference imaginary intersection point BV2m. This position J2m is a transverse point (hereinafter referred to as the second transverse point). The double arrow Xj2m is the distance from the second reference imaginary intersection point BV2m to the second transverse point J2m. This distance Xj2m is represented by the length of the line segment connecting the second reference imaginary intersection point BV2m and the second transverse point J2m. Reference numeral M2m is the intersection of the normal line through the reference forming surface FBL at the second transverse point J2m and the second tangent point side arc. This intersection point M2m is an intermediate boundary point (hereinafter referred to as the second intermediate boundary point). In this tread forming surface 102, the arc passing through the second reference boundary point BB2m and tangent to the second tangent point side arc at the second intermediate boundary point M2m is the boundary side arc (hereinafter referred to as the second boundary side arc).

[0176] In this mold 98, the contour of the curved land surface forming part 76B, from the reference tangent point Tm to the first intermediate boundary point M1m, is represented by a first tangent point side arc. The contour from the first intermediate boundary point M1m to the first reference boundary point BB1m is represented by a first boundary side arc. The contour from the reference tangent point Tm to the second intermediate boundary point M2m is represented by a second tangent point side arc. The contour from the second intermediate boundary point M2m to the second reference boundary point BB2m is represented by a second boundary side arc.

[0177] In this mold 98, the flow of unvulcanized rubber on the side of the first protrusion 74f and the flow of unvulcanized rubber on the side of the second protrusion 74n are also controlled evenly. Since the flow of unvulcanized rubber is less likely to become disordered, a curved land surface 46B that reflects the shape of the curved land surface forming portion 76B is formed in this mold 98.

[0178] Although not illustrated, it can be confirmed from the contact patch shape of the tire 92 manufactured using this mold 98 that the circumferential outer edge of the central land portion 44m is not bulging inward, but rather bulging outward. In terms of ground pressure distribution, it can be confirmed that the ground pressure difference within the central land portion 44m is suppressed to approximately 45 kPa. Based on this mold 98 and the manufacturing method of the tire 92 using this mold 98, the contact patch shape and ground pressure distribution of the tire 92 can be optimized, thereby improving the handling stability and wear resistance of the tire 92.

[0179] In this mold 98, from the viewpoint of optimizing the contact patch shape and contact pressure distribution of the tire 92, the ratio (Xkm / Xdm) of the distance Xkm from the reference hypothetical intersection point BVm to the longitudinal point Km to the distance Xdm from the reference hypothetical intersection point BVm to the reference boundary point BBm is preferably 0.40 or more, more preferably 0.45 or more. This ratio (Xkm / Xdm) is preferably 0.60 or less, more preferably 0.55 or less.

[0180] In this mold 98, from the viewpoint of optimizing the contact patch shape and contact pressure distribution of the tire 92, the ratio (Xjm / Xwm) of the distance Xjm from the reference imaginary intersection point BVm to the lateral point Jm to the distance Xwm from the reference imaginary intersection point BVm to the reference tangent point Tm is preferably 0.40 or more, more preferably 0.45 or more. This ratio (Xjm / Xwm) is preferably 0.60 or less, more preferably 0.55 or less.

[0181] In this mold 98, it is more preferable that the ratio of the distance Xkm from the reference imaginary intersection point BVm to the longitudinal point Km to the distance Xdm from the reference imaginary intersection point BVm to the reference boundary point BBm (Xkm / Xdm) is 0.40 or more and 0.60 or less, and the ratio of the distance Xjm from the reference imaginary intersection point BVm to the transverse point Jm to the distance Xwm from the reference imaginary intersection point BVm to the reference tangent point Tm (Xjm / Xwm) is 0.40 or more and 0.60 or less.

[0182] In this mold 98, the cross-sectional area Sam of the first convex 74f is smaller than the cross-sectional area Sbm of the second convex 74n. From the viewpoint that even when the cross-sectional areas Sam of the first convex 74f and Sbm of the second convex 74n are different, the flow of uncured rubber on the first convex 74f side and the second convex 74n side can be controlled evenly, and the flow of uncured rubber can be effectively suppressed to prevent disorder, thus optimizing the contact patch shape and contact pressure distribution of the tire 92, the distance from the first hypothetical intersection point BV1m to the first longitudinal point K1m is preferably [missing information]. The ratio (Xk1m / Xd1m) of Xk1m to the distance Xd1m from the first datum imaginary intersection point BV1m to the first datum boundary point BB1m is 0.40 or more and 0.60 or less. Similarly, the ratio (Xk2m / Xd2m) of Xk2m from the second datum imaginary intersection point BV2m to the distance Xd2m from the second datum imaginary intersection point BV2m to the second datum boundary point BB2m is 0.40 or more and 0.60 or less. In this case, the ratios (Xk1m / Xd1m) and (Xk2m / Xd2m) are set to the same value.

[0183] From the same perspective, it is preferable that the ratio (Xj1m / Xw1m) of the distance Xj1m from the first imaginary intersection point BV1m to the first horizontal point J1m to the distance Xw1m from the first imaginary intersection point BV1m to the reference tangent point Tm is 0.40 or higher and 0.60 or lower, and the ratio (Xj2m / Xw2m) of the distance Xj2m from the second imaginary intersection point BV2m to the distance Xw2m from the second imaginary intersection point BV2m to the reference tangent point Tm is 0.40 or higher and 0.60 or lower. In this case, the ratio (Xj1m / Xw1m) and the ratio (Xj2m / Xw2m) are set to the same value.

[0184] [In the case where the ridge 74 located next to the curved land surface forming section 76B is the tire shoulder ridge 74s]

[0185] In the case where the second ridge 74n located next to the curved land surface forming section 76B is the tire shoulder ridge 74s. Figure 8The second land surface forming portion 76n is the shoulder land surface forming portion 76s of the tire shoulder land surface 46s of the tire 92. From the viewpoint of obtaining a more suitable contact surface shape and contact pressure distribution, the outline of the shoulder land surface forming portion 76s in this tread forming surface 102, from the shoulder reference boundary point BBsm to the shoulder reference tangent point Tsm, can be represented by two circular arcs. Hereinafter, using... Figure 8 This section describes the outline of the shoulder land surface forming part 76s from the shoulder reference boundary point BBsm to the shoulder reference tangent point Tsm.

[0186] exist Figure 8 In the attached diagram, reference numeral Ksm is located on the imaginary line BLsm of the dorsal side surface 80b of the second convex rib 74n, and is any position between the shoulder reference boundary point BBsm and the imaginary intersection point BVsm of the shoulder reference. This position Ksm is the longitudinal point of the shoulder. The double arrow Xdkm is the distance from the imaginary intersection point BVsm of the shoulder reference to the longitudinal point Ksm of the shoulder. This distance Xdkm is measured along the imaginary line BLsm of the dorsal side surface 80b. In this tread forming surface 102, the arc passing through the longitudinal point Ksm of the shoulder and tangent to the reference forming surface FBL at the shoulder reference tangency point Tsm is the shoulder tangency point side arc.

[0187] exist Figure 8 In the attached drawing, the reference numeral Jsm is located on the reference forming surface FBL and is any position between the shoulder reference tangent point Tsm and the shoulder reference imaginary intersection point BVsm. This position Jsm is the shoulder lateral point. The double arrow Xjsm is the distance from the shoulder reference imaginary intersection point BVsm to the shoulder lateral point Jsm. This distance Xjsm is represented by the length of the line segment connecting the shoulder reference imaginary intersection point BVsm and the shoulder lateral point Jsm. The reference numeral Msm is the intersection of the normal line through the shoulder lateral point Jsm on the reference forming surface FBL and the shoulder tangent side arc. This intersection point Msm is the shoulder middle boundary point. In this tread forming surface 102, the arc passing through the shoulder reference boundary point BBsm and tangent to the shoulder tangent side arc at the shoulder middle boundary point Msm is the shoulder boundary side arc.

[0188] In this mold 98, in the outline of the shoulder land surface forming portion 76s, the outline from the shoulder reference tangent point Tsm to the shoulder intermediate boundary point Msm is represented by a shoulder tangent point side arc, and the outline from the shoulder intermediate boundary point Msm to the shoulder reference boundary point BBsm is represented by a shoulder boundary side arc. Furthermore, the distance Xdsm from the shoulder reference imaginary intersection point BVsm to the shoulder reference boundary point BBsm in the back side surface 80b of the second convex rib 74n is the same as the distance Xd2m from the second reference imaginary intersection point BV2m to the second reference boundary point BB2m in the reference side surface 80a, i.e., the second reference side surface 80a, and the distance Xwsm from the shoulder reference imaginary intersection point BVsm to the shoulder reference tangent point Tsm is the same as the distance Xw2m from the second reference imaginary intersection point BV2m to the reference tangent point Tm. Furthermore, the distance Xksm from the imaginary intersection point BVsm of the tire shoulder reference to the longitudinal point Ksm of the tire shoulder is the same as the distance Xk2m from the second imaginary intersection point BV2m of the reference to the second longitudinal point K2m, and the distance Xjsm from the imaginary intersection point BVsm of the tire shoulder reference to the transverse point Jsm of the tire shoulder is the same as the distance Xj2m from the second imaginary intersection point BV2m of the reference to the second transverse point J2m.

[0189] In this mold 98, the flow of uncured rubber pressed against the second protrusion 74n is not easily disordered, thus forming a tire shoulder land surface 46s that reflects the shape of the tire shoulder land surface forming part 76s.

[0190] Although not illustrated, it can be confirmed from the contact patch shape of the tire 92 manufactured using this mold 98 that the circumferential outer edge of the tire shoulder land portion 44s is not inwardly protruding, but rather bulging outwards. In terms of ground pressure distribution, it can be confirmed that the ground pressure difference within the tire shoulder land portion 44s is suppressed to approximately 60 kPa. Based on this mold 98 and the manufacturing method of the tire 92 using this mold 98, the contact patch shape and ground pressure distribution of the tire 92 can be optimized, thereby improving the handling stability and wear resistance of the tire 92.

[0191] Figure 7 The tire 92 shown is manufactured using the mold 98 described above, which has a tread forming surface 102. Next, the outline of the tread surface 96 shaped by the tread forming surface 102 will be described.

[0192] [Outline of curved land surface 46B]

[0193] First of all, Figure 7 The outline of the curved land surface 46B included in the tread surface 96 shown will be explained. In this tread surface 96, the outline of the curved land surface 46B is represented by a plurality of arcs. From the viewpoint of obtaining a more appropriate contact surface shape and contact pressure distribution, the outline of the curved land surface 46B in this tread surface 96 can be represented by the following four arcs.

[0194] exist Figure 7 In the attached drawing, reference numeral K1t is located on the imaginary line BL1t of the first reference wall 50a of the first circumferential groove 42f, and is an arbitrary position between the first reference boundary point BB1t and the first reference imaginary intersection point BV1t. This position K1t is the longitudinal point (hereinafter referred to as the first longitudinal point). The double arrow Xk1t is the distance from the first reference imaginary intersection point BV1t to the first longitudinal point K1t. This distance Xk1t is represented by the length of the line segment connecting the first reference imaginary intersection point BV1t and the first longitudinal point K1t. In the tread surface 96, the arc passing through the first longitudinal point K1t and tangent to the reference surface TBL at the reference tangency point Tt is the tangency-side arc (hereinafter referred to as the first tangency-side arc).

[0195] exist Figure 7 In the attached drawing, reference numeral J1t is located on the reference plane TBL at any position between the reference tangent point Tt and the first reference imaginary intersection point BV1t. This position J1t is the lateral point (hereinafter referred to as the first lateral point). The double arrow Xj1t is the distance from the first reference imaginary intersection point BV1t to the first lateral point J1t. This distance Xj1t is represented by the length of the line segment connecting the first reference imaginary intersection point BV1t and the first lateral point J1t. Reference numeral M1t is the intersection of the normal line through the reference plane TBL at the first lateral point J1t and the first tangent-side arc. This intersection point M1t is the intermediate boundary point (hereinafter referred to as the first intermediate boundary point). In the tread surface 96, the arc passing through the first reference boundary point BB1t and tangent to the first tangent-side arc at the first intermediate boundary point M1t is the boundary-side arc (hereinafter referred to as the first boundary-side arc).

[0196] exist Figure 7 In the attached diagram, reference numeral K2t is located on the imaginary line BL2t of the second reference wall 50a of the second circumferential groove 42n, and is an arbitrary position between the second reference boundary point BB2t and the second reference imaginary intersection point BV2t. This position K2t is the longitudinal point (hereinafter referred to as the second longitudinal point). The double arrow Xk2t is the distance from the second reference imaginary intersection point BV2t to the second longitudinal point K2t. This distance Xk2t is represented by the length of the line segment connecting the second reference imaginary intersection point BV2t and the second longitudinal point K2t. In this tread surface 96, the arc passing through the second longitudinal point K2t and tangent to the reference surface TBL at the reference tangency point Tt is the tangency point side arc (hereinafter referred to as the second tangency point side arc).

[0197] exist Figure 7In the attached drawing, reference numeral J2t is located on the reference plane TBL at any position between the reference tangent point Tt and the second reference imaginary intersection point BV2t. This position J2t is a transverse point (hereinafter referred to as the second transverse point). The double arrow Xj2t is the distance from the second reference imaginary intersection point BV2t to the second transverse point J2t. This distance Xj2t is represented by the length of the line segment connecting the second reference imaginary intersection point BV2t and the second transverse point J2t. Reference numeral M2t is the intersection of the normal line through the reference plane TBL at the second transverse point J2t and the second tangent point side arc. This intersection point M2t is an intermediate boundary point (hereinafter referred to as the second intermediate boundary point). In this tread surface 96, the arc passing through the second reference boundary point BB2t and tangent to the second tangent point side arc at the second intermediate boundary point M2t is the boundary side arc (hereinafter referred to as the second boundary side arc).

[0198] In this tire 92, the contour of the curved land surface 46B, from the reference tangent point Tt to the first intermediate boundary point M1m, is represented by a first tangent point side arc. The contour from the first intermediate boundary point M1m to the first reference boundary point BB1t is represented by a first boundary side arc. The contour from the reference tangent point Tt to the second intermediate boundary point M2t is represented by a second tangent point side arc. Furthermore, the contour from the second intermediate boundary point M2t to the second reference boundary point BB2t is represented by a second boundary side arc.

[0199] In the manufacture of this tire 92, the flow of uncured rubber on the first rib 74f side and the flow of uncured rubber on the second rib 74n side are evenly controlled, thus forming a curved land surface 46B that reflects the shape of the curved land surface forming portion 76B. In this tire 92, an appropriate contact patch shape and contact pressure distribution are obtained. This tire 92 enables improved handling stability and wear resistance.

[0200] In this tire 92, from the viewpoint of optimizing the contact patch shape and contact pressure distribution, the ratio (Xkt / Xdt) of the distance Xkt from the reference imaginary intersection point BVt to the longitudinal point Kt to the distance Xdt from the reference imaginary intersection point BVt to the reference boundary point BBt is preferably 0.40 or more, more preferably 0.45 or more. This ratio (Xkt / Xdt) is preferably 0.60 or less, more preferably 0.55 or less.

[0201] In this tire 92, from the viewpoint of optimizing the contact patch shape and contact pressure distribution, the ratio (Xjt / Xwt) of the distance Xjt from the reference imaginary intersection point BVt to the lateral point Jt to the distance Xwt from the reference imaginary intersection point BVt to the reference tangent point Tt is preferably 0.40 or more, more preferably 0.45 or more. This ratio (Xjt / Xwt) is preferably 0.60 or less, more preferably 0.55 or less.

[0202] In this tire 92, it is more preferable that the ratio of the distance Xkt from the reference imaginary intersection point BVt to the longitudinal point Kt to the distance Xdt from the reference imaginary point BVt to the reference boundary point BBt (Xkt / Xdt) is 0.40 or more and 0.60 or less, and the ratio of the distance Xjt from the reference imaginary intersection point BVt to the transverse point Jt to the distance Xwt from the reference imaginary intersection point BVt to the reference tangent point Tt (Xjt / Xwt) is 0.40 or more and 0.60 or less.

[0203] In this tire 92, the cross-sectional area Sat of the first circumferential groove 42f is smaller than the cross-sectional area Sbt of the second circumferential groove 42n. From the perspective that the flow of uncured rubber on the first rib 74f side and the second rib 74n side can be balanced when the cross-sectional areas Sat of the first circumferential groove 42f and Sbt of the second circumferential groove 42n are different, and that the flow of uncured rubber on both sides can be effectively controlled, and that disorder in the flow of uncured rubber can be effectively suppressed, thereby optimizing the contact patch shape and contact pressure distribution of the tire 92, it is preferable to extend from the first hypothetical intersection point BV1t to the first longitudinal point K1t. The ratio (Xk1t / Xd1t) of the distance Xk1t from the first datum imaginary intersection point BV1t to the first datum boundary point BB1t is 0.40 or more and 0.60 or less. Similarly, the ratio (Xk2t / Xd2t) of the distance Xk2t from the second datum imaginary intersection point BV2t to the second longitudinal point K2t is 0.40 or more and 0.60 or less. In this case, the ratios (Xk1t / Xd1t) and (Xk2t / Xd2t) are set to the same value.

[0204] From the same perspective, it is preferable that the ratio (Xj1t / Xw1t) of the distance Xj1t from the first imaginary intersection point BV1t to the first horizontal point J1t and the distance Xw1t from the first imaginary intersection point BV1t to the reference tangent point Tt is 0.40 or more and 0.60 or less, and the ratio (Xj2t / Xw2t) of the distance Xj2t from the second imaginary intersection point BV2t to the second horizontal point J2t and the distance Xw2t from the second imaginary intersection point BV2t to the reference tangent point Tt is 0.40 or more and 0.60 or less. In this case, the ratio (Xj1t / Xw1t) and the ratio (Xj2t / Xw2t) are set to the same value.

[0205] [In the case where the circumferential groove 42 located next to the curved land surface 46B is the shoulder circumferential groove 42s]

[0206] In the case where the second circumferential groove 42n is located axially at the outermost shoulder circumferential groove 42s, Figure 7The second land surface 46n forms the shoulder land surface 46s of the tire 92. From the viewpoint of obtaining a more suitable contact surface shape and contact pressure distribution, the profile of the shoulder land surface 46s in this tread surface 96 can be represented by two arcs from the shoulder reference boundary point BBst to the shoulder reference tangent point Tst, as shown below. Hereinafter, using... Figure 7 This section describes the profile of the tire shoulder land surface 46s, from the tire shoulder reference boundary point BBst to the tire shoulder reference tangent point Tst.

[0207] exist Figure 7 In the attached diagram, the reference numeral Kst is located on the imaginary line BLst of the opposing wall 50b of the second circumferential groove 42n, and is any position between the shoulder reference boundary point BBst and the imaginary intersection point BVst of the shoulder reference. This position Kst is the longitudinal point of the shoulder. The double arrow Xkst is the distance from the imaginary intersection point BVst of the shoulder reference to the longitudinal point Kst of the shoulder. This distance Xdkt is measured along the imaginary line BLst of the opposing wall 50b. In this tread surface 96, the arc passing through the longitudinal point Kst of the shoulder and tangent to the reference surface TBL at the shoulder reference tangency point Tst is the shoulder tangency point side arc.

[0208] exist Figure 7 In the attached diagram, the reference numeral Jst is located on the reference plane TBL at any position between the shoulder reference tangent point Tst and the imaginary intersection point Vst of the shoulder reference. This position Jst is the shoulder lateral point. The double arrow Xjst is the distance from the imaginary intersection point BVst of the shoulder reference to the shoulder lateral point Jst. This distance Xjst is represented by the length of the line segment connecting the imaginary intersection point BVst and the shoulder lateral point Jst. The reference numeral Mst is the intersection point of the normal to the reference plane TBL passing through the shoulder lateral point Jst and the shoulder tangent side arc. This intersection point Mst is the shoulder middle boundary point. In this tread surface 96, the arc passing through the shoulder reference boundary point BBst and tangent to the shoulder tangent side arc at the shoulder middle boundary point Mst is the shoulder boundary side arc.

[0209] In this tire 92, the profile of the shoulder land surface 46s, from the shoulder reference tangent point Tst to the shoulder intermediate boundary point Mst, is represented by a shoulder tangent point side arc, and the profile from the shoulder intermediate boundary point Mst to the shoulder reference boundary point BBst is represented by a shoulder boundary side arc. Furthermore, the distance Xdst from the shoulder reference imaginary intersection point BVst to the shoulder reference boundary point BBst in the opposing wall 50b of the second circumferential groove 42n is the same as the distance Xd2t from the second reference imaginary intersection point BV2t to the second reference boundary point BB2t in the reference wall 50a, i.e., the second reference wall 50a. The distance Xwst from the shoulder reference imaginary intersection point BVst to the shoulder reference tangent point Tst is the same as the distance Xw2t from the second reference imaginary intersection point BV2t to the reference tangent point Tt. Furthermore, the distance Xkst from the imaginary intersection point BVst of the shoulder reference to the longitudinal point Kst of the shoulder is the same as the distance Xk2t from the second imaginary intersection point BV2t to the second longitudinal point K2t, and the distance Xjst from the imaginary intersection point BVst of the shoulder reference to the transverse point Jst of the shoulder is the same as the distance Xj2t from the second imaginary intersection point BV2t to the second transverse point J2t.

[0210] During the manufacturing of this tire 92, the flow of the uncured rubber pressed against the second rib 74n is less prone to becoming disordered, thus forming a shoulder land surface 46s that reflects the shape of the shoulder land surface forming portion 76s. In this tire 92, an appropriate contact patch shape and contact pressure distribution are obtained. This tire 92 achieves improved handling stability and wear resistance.

[0211] As explained above, the tire mold and tire manufacturing method according to the present invention can optimize the tire's contact patch shape and contact pressure distribution. Furthermore, the tire obtained by this tire mold and tire manufacturing method achieves improved handling stability and wear resistance due to the appropriate contact patch shape and contact pressure distribution. The present invention utilizes a tire with a groove width of 9 mm or more and a tire diameter of 45 mm... 2 When the circumferential grooves with larger cross-sectional areas are engraved on the tire tread, they achieve excellent results.

[0212] As described above, the raised ribs on the tread forming surface are pressed to the top. This invention utilizes grooves with a width of 9mm or more and a diameter of 45mm... 2 The circumferential grooves with larger cross-sectional areas are engraved on the top, which has a significant effect when the Mooney viscosity of the uncured rubber used on the top is 80 or higher. Furthermore, Mooney viscosity means Mooney viscosity ML. 1+4 (100℃), measured according to JISK6300-1.

[0213] Industrial availability

[0214] The techniques described above for optimizing the tire's contact patch shape and ground pressure distribution can also be applied to various tires.

Claims

1. A tire mold for manufacturing a tire, the tire having a tread surface having contact with the road surface, wherein at least two circumferential grooves are etched into the tread to form at least three land portions, the tread surface comprising: The at least two circumferential trenches and the outer surfaces of the at least three land sections, i.e., at least three land surfaces, are characterized in that... The tire mold has a tread forming surface for shaping the tread surface. The tread forming surface includes: a rib forming the circumferential groove and a land surface forming portion forming the land surface. A surface having a profile represented by at least one circular arc and tangent to the three land surface forming portions arranged axially with the convex strips spaced apart is the reference forming surface of the tread forming surface. Of the three land surface forming sections, the one located between the two convex ridges is a curved land surface forming section. The convex strip includes: a side surface on the land surface forming portion side, i.e., a reference side surface, and a side surface located on the back side of the reference side surface, i.e., a back side surface. The point of tangency between the curved land surface forming portion and the reference forming surface is the reference tangency point. The boundary between the reference side and the curved land surface forming part is the reference boundary point. The intersection of the imaginary line extending from the reference boundary point toward the reference forming surface and the reference forming surface is the reference imaginary intersection point. The outline of the curved land surface forming part is represented by one or more circular arcs. The reference boundary point is located inside the reference forming surface. When one side of the convex strip has a small cross-sectional area and the other side of the convex strip has a large cross-sectional area, The distance from the imaginary intersection point to the reference boundary point is shorter on one side of the convex strip, and longer on the other side of the convex strip. When the distance from the reference imaginary intersection point on one side of the convex rib to the reference tangent point is set to Xw1m, the distance from the reference imaginary intersection point on one side of the convex rib to the reference imaginary intersection point on the other side of the convex rib is set to Wcm, the cross-sectional area of ​​the convex rib on one side is set to Sam, and the cross-sectional area of ​​the convex rib on the other side is set to Sbm, the distance Xw1m from the reference imaginary intersection point on one side of the convex rib to the reference tangent point is set in a manner that satisfies the following formula (1). Sam / (Sam+Sbm)×100-10≤Xw1m / Wcm×100≤Sam / (Sam+Sbm)×100+10…(1).

2. The tire mold according to claim 1, characterized in that, The ratio of the distance from the reference imaginary intersection point to the reference boundary point to the cross-sectional area of ​​the convex strip is greater than 0.0008 and less than 0.0040.

3. The tire mold according to claim 1 or 2, characterized in that, The contour of the curved land surface forming part, from the reference tangent point to the reference boundary point, is represented by a circular arc that passes through the reference boundary point and is tangent to the reference forming surface at the reference tangent point.

4. The tire mold according to claim 3, characterized in that, The land surface forming portion included in the tread forming surface, located axially on the outer side, is the shoulder land surface forming portion. The land surface forming part located next to the curved land surface forming part among the three land surface forming parts is the tire shoulder land surface forming part. The side of the ridge located between the shoulder land surface forming portion and the curved land surface forming portion, on the side of the curved land surface forming portion, is the reference side, and the side of the ridge on the side of the shoulder land surface forming portion is the dorsal side. The point of tangency between the shoulder land surface forming portion and the reference forming surface is the shoulder reference tangency point. The boundary between the dorsal side and the shoulder land surface forming part is the shoulder reference boundary point. The intersection of the imaginary line extending from the shoulder reference boundary point toward the reference forming surface and the reference forming surface is the imaginary intersection point of the shoulder reference. The distance from the imaginary intersection point of the tire shoulder reference on the dorsal side to the tire shoulder reference boundary point is the same as the distance from the imaginary intersection point of the reference side to the reference boundary point on the reference side. The distance from the imaginary intersection point of the tire shoulder reference to the imaginary tangent point of the tire shoulder reference is the same as the distance from the imaginary intersection point of the reference to the imaginary tangent point of the reference. The outline of the shoulder land surface forming portion, from the shoulder reference tangent point to the shoulder reference boundary point, is represented by an arc that passes through the shoulder reference boundary point and is tangent to the reference forming surface at the shoulder reference tangent point.

5. The tire mold according to claim 1 or 2, characterized in that, Any position on the imaginary line of the reference side, between the reference boundary point and the imaginary intersection point of the reference, is a vertical point. The arc that passes through the longitudinal point and is tangent to the reference forming surface at the reference tangent point is the tangent-side arc. Any position on the reference forming surface between the reference tangent point and the reference imaginary intersection point is a transverse point. The intersection of the normal to the reference surface formed by the horizontal point and the tangent side arc is the intermediate boundary point. The arc passing through the reference boundary point and tangent to the tangent-side arc at the intermediate boundary point is the boundary-side arc. The contour of the curved land surface forming part, from the reference tangent point to the intermediate boundary point, is represented by the tangent point side arc, and the contour from the intermediate boundary point to the reference boundary point is represented by the boundary side arc.

6. The tire mold according to claim 5, characterized in that, The ratio of the distance from the reference imaginary intersection point to the longitudinal point to the distance from the reference imaginary intersection point to the reference boundary point is greater than 0.40 and less than 0.

60. The ratio of the distance from the reference imaginary intersection point to the horizontal point to the distance from the reference imaginary intersection point to the reference tangent point is greater than 0.40 and less than 0.

60.

7. The tire mold according to claim 5, characterized in that, The land surface forming portion included in the tread forming surface, located axially on the outer side, is the shoulder land surface forming portion. The land surface forming part located next to the curved land surface forming part among the three land surface forming parts is the tire shoulder land surface forming part. The side of the ridge located between the shoulder land surface forming portion and the curved land surface forming portion, on the side of the curved land surface forming portion, is the reference side, and the side of the ridge on the side of the shoulder land surface forming portion is the dorsal side. The point of tangency between the land surface forming portion of the tire shoulder and the reference forming surface is the tire shoulder reference tangency point. The boundary between the dorsal side and the shoulder land surface forming part is the shoulder reference boundary point. The intersection of the imaginary line extending from the shoulder reference boundary point toward the reference forming surface and the reference forming surface is the imaginary intersection point of the shoulder reference. The distance from the imaginary intersection point of the tire shoulder reference to the tire shoulder reference boundary point on the dorsal side is the same as the distance from the imaginary intersection point of the reference side to the reference boundary point on the reference side. The distance from the imaginary intersection point of the tire shoulder reference to the imaginary tangent point of the tire shoulder reference is the same as the distance from the imaginary intersection point of the reference to the imaginary tangent point of the reference. The shoulder longitudinal point is any position on the imaginary line on the dorsal side, between the shoulder reference boundary point and the imaginary intersection point of the shoulder reference. The arc that passes through the longitudinal point of the tire shoulder and is tangent to the reference surface at the reference tangent point of the tire shoulder is the side arc of the tire shoulder tangent point. Any position on the reference forming surface between the shoulder reference tangent point and the imaginary intersection point of the shoulder reference is the shoulder lateral point. The intersection of the normal to the reference forming surface at the shoulder transverse point and the arc on the side of the shoulder tangent point is the middle boundary point of the shoulder. The arc that passes through the tire shoulder reference boundary point and is tangent to the tire shoulder boundary side arc at the middle boundary point of the tire shoulder is the tire shoulder boundary side arc. The outline of the shoulder land surface forming portion, from the shoulder reference tangent point to the shoulder intermediate boundary point, is represented by the shoulder tangent point side arc, and the outline from the shoulder intermediate boundary point to the shoulder reference boundary point is represented by the shoulder boundary side arc. The distance from the imaginary intersection point of the tire shoulder reference to the longitudinal point of the tire shoulder is the same as the distance from the imaginary intersection point to the longitudinal point. The distance from the imaginary intersection point of the tire shoulder to the lateral point of the tire shoulder is the same as the distance from the imaginary intersection point to the lateral point.

8. The tire mold according to claim 1 or 2, characterized in that, The tread has a top that includes the tread surface. The Mooney viscosity of the uncured rubber used for the top is above 80.

9. A method for manufacturing a tire, characterized in that, This includes the process of pressurizing and heating a green tire using a tire mold as described in any one of claims 1 to 8.

10. A tire comprising a tread having a tread surface in contact with the road surface, wherein at least two circumferential grooves are etched into the tread to form at least three land portions, the tread surface including the at least two circumferential grooves and the outer surface of the at least three land portions, i.e., at least three land surfaces, characterized in that, A surface having a profile represented by at least one circular arc and tangent to the three land surfaces arranged axially across the circumferential grooves is a reference surface for the tread surface. Of the three land surfaces, the one located between the two circumferential trenches is a curved land surface. The circumferential trench has a wall on the curved land surface side, i.e., a reference wall, and a wall opposite to the reference wall, i.e., an opposing wall. The point of tangency between the curved land surface and the reference surface is the reference tangency point. The boundary between the reference wall and the curved land surface is the reference boundary point. The intersection of the imaginary line extending from the reference boundary point toward the reference surface and the reference surface is the imaginary intersection point. The contour of the curved land surface is represented by one or more circular arcs. The reference boundary point is located inside the reference surface. When one side's circumferential ditch has a small cross-sectional area and the other side's circumferential ditch has a large cross-sectional area, The distance from the imaginary intersection point to the reference boundary point is shorter on one side of the circumferential groove, while the distance from the imaginary intersection point to the reference boundary point is longer on the other side of the circumferential groove. When the distance from the imaginary intersection point of one side to the imaginary tangent point is set as Xw1t, the distance from the imaginary intersection point of one side to the imaginary intersection point of the other side is set as Wct, the cross-sectional area of ​​the circumferential groove of one side is set as Sat, and the cross-sectional area of ​​the circumferential groove of the other side is set as Sbt, the distance Xw1t from the imaginary intersection point of one side to the imaginary tangent point is set in a manner that satisfies the following formula (2). Sat / (Sat+Sbt)×100-10≤Xw1t / Wct×100≤Sat / (Sat+Sbt)×100+10…(2).

Images