Pneumatic tire and tire vulcanization mold

Abstract

This invention provides an inflatable tire and a tire vulcanization mold that improve the performance of the tire on muddy and rough roads. The groove wall (72) of the main groove (7) provided on the tread surface (3f) includes a concave-convex region (10) with a plurality of protrusions (40). When viewed from a direction perpendicular to the groove wall (72), the protrusions (40) have a long side direction and a short side direction orthogonal to it, and taper at the front end towards both sides of the long side direction. The long side direction of the protrusions (40) is radial to the tire. The protrusions (40) have: a ridge (44) that extends along the long side direction in a region on one side of the long side direction; a first slope (41) whose protrusion height decreases from the ridge (44) towards the short side direction; a second slope (42) whose protrusion height decreases from the ridge (44) towards the other side of the short side direction; and a third slope (43) that is disposed in a region on the other side of the long side direction and whose protrusion height decreases towards the other side of the long side direction.

Description

Technical Field

[0001] This disclosure relates to pneumatic tires and tire vulcanization molds for vulcanizing pneumatic tires. Background Technology

[0002] Patent documents 1 and 2 respectively describe pneumatic tires with grooves on the tread surface having concave and convex regions on the groove walls. The tire described in Patent Document 1, aimed at improving snow traction, has concave and convex regions formed by multiple recesses with triangular openings on the tread surface and wall surface of the tread blocks. Furthermore, in the tire described in Patent Document 2, although... 2 The shapes of the tiny protrusions, configured with a density of 1 to 5, include frustum conical, cylindrical, and pyramidal shapes, but it is believed that there is room for improvement in their performance on rough roads in muddy conditions.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-161388

[0006] Patent Document 2: Japanese Patent Application Publication No. 2022-128121 Utility Model Content

[0007] The problem to be solved by utility models

[0008] This disclosure was made in view of the above-mentioned actual situation, and its purpose is to provide an inflatable tire and a tire vulcanization mold that can improve the performance of passing through poor roads on muddy ground.

[0009] Methods for solving problems

[0010] The pneumatic tire disclosed herein includes a groove disposed on the tread surface. The groove wall includes a plurality of protruding, uneven regions. When viewed from a direction perpendicular to the groove wall, the protrusions have a long side direction and a short side direction orthogonal to it, tapering towards both sides of the long side direction. The long side direction of the protrusions is radially oriented towards the tire. The protrusions have: a ridge extending along the long side direction in a region on one side of the long side direction; a first inclined surface whose protrusion height decreases from the ridge towards the short side direction; a second inclined surface whose protrusion height decreases from the ridge towards the other side of the short side direction; and a third inclined surface disposed in a region on the other side of the long side direction, whose protrusion height decreases towards the other side of the long side direction.

[0011] The tire vulcanizing mold disclosed herein includes a protrusion for forming grooves disposed on the tread surface of a tire. The sidewall of the protrusion includes a concave-convex region with a plurality of recesses arranged therein. When viewed from a direction perpendicular to the sidewall, the recesses have a shape having a long side direction and a short side direction orthogonal to it, tapering towards both sides in the long side direction. The long side direction of the recesses faces the tire radially. The recesses have: a mold ridge extending along the long side direction in a region on one side; a first mold slope whose depth decreases from the mold ridge towards the short side direction; a second mold slope whose depth decreases from the mold ridge towards the other side in the short side direction; and a third mold slope disposed in a region on the other side in the long side direction, whose depth decreases towards the other side in the long side direction. Attached Figure Description

[0012] Figure 1 This is a radial cross-sectional view of a tire, showing an example of a pneumatic tire.

[0013] Figure 2 This is a planar development diagram showing an example of tire tread pattern.

[0014] Figure 3 This is a planar development diagram showing another example of tire tread pattern.

[0015] Figure 4 This is a cross-sectional view of the tire meridian of the main groove.

[0016] Figure 5 This is a diagram showing the tank wall from the front.

[0017] Figure 6 It is a top view of the protrusion.

[0018] Figure 7 (A) is a side view of the protrusion, (B) is a sectional view along the A-A direction, and (C) is a sectional view along the B-B direction.

[0019] Figure 8 It is a three-dimensional image with protrusions.

[0020] Figure 9 (A) is a side view of the protrusion in the modified example, and (B) is a perspective view.

[0021] Figure 10 This is a radial cross-sectional view of a tire, showing an example of a tire vulcanization mold.

[0022] Figure 11 This is a cross-sectional view of the tire's radial section at the protrusion.

[0023] Figure 12 This is a diagram showing the side wall of the protrusion from the front.

[0024] Figure 13This is a top view of the concave area.

[0025] Figure 14 (A) is a side sectional view of the concave part, (B) is a sectional view along the C-C direction, and (C) is a sectional view along the D-D direction.

[0026] Explanation of reference numerals in the attached figures:

[0027] 3f Tread surface, 7 Main groove (an example of a groove), 8 Transverse groove (an example of a groove), 9 Protrusion, 10 Uneven area, 40 Protrusion, 40A Protrusion row, 40t Top, 41 First slope, 42 Second slope, 43 Third slope, 44 Ridge, 71 Groove bottom, 72 Groove wall, 73 Connecting surface, 90 Uneven area, 92 Side wall, 100 Recess, 101 First mold slope, 102 Second mold slope, 103 Third mold slope, 104 Mold ridge, LD Long side direction, LD1 One side of the long side direction, LD2 The other side of the long side direction, SD Short side direction, SD1 One side of the short side direction, SD2 The other side of the short side direction, T Pneumatic tire. Detailed Implementation

[0028] The embodiments of this disclosure will be described with reference to the accompanying drawings.

[0029] Figure 1 This is a radial cross-sectional view of the pneumatic tire T according to this embodiment. The pneumatic tire T is an automobile tire, which includes a pair of bead portions 1, a pair of sidewall portions 2 extending radially outward from the bead portions 1, and a tread portion 3 connected to the radially outward end of each of the sidewall portions 2. An annular bead core 1a is embedded in the bead portion 1. The bead core 1a is formed by covering a bundle of materials such as steel wire with rubber. A bead filler 1b is disposed radially outward from the bead core 1a. The bead filler 1b is formed of rubber with a triangular cross-section extending radially outward from the bead core 1a.

[0030] Here, the tire radial section is the cross-section cut by a plane containing the central axis (axis of rotation) of the tire T. The tire circumferential direction is the direction about the central axis of the tire T. The tire radial direction is the direction along the diameter of the tire T. The side closer to the central axis is the inner radial direction, and the side farther from the central axis is the outer radial direction. The tire axial direction is the direction parallel to the central axis. The side closer to the tire equator TC, located at the center of the tire axial direction of the tire T, is the inner axial direction, and the side farther from the tire equator TC is the outer axial direction.

[0031] Unless otherwise specified, the dimensions and angles of all parts of a tire are determined by its unloaded state when mounted on a standard rim and inflated to the standard internal pressure. A standard rim is a rim defined for each tire within a specification system, including the tire's underlying specification. For example, JATMA is a standard rim, while TRA and ETRTO are "Measuring Rim". Standard internal pressure is the air pressure defined for each tire within a specification system, including the tire's underlying specification. For truck and bus tires, and light truck tires, JATMA represents the maximum air pressure, TRA represents the value corresponding to the Load Index listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and ETRTO represents "INFLATION PRESSURE". For passenger car tires, this is typically 180 kPa, but 220 kPa for tires designated Extra Load or Reinforced.

[0032] The tire T has a carcass 4 extending in a ring shape across a pair of bead portions 1. The carcass 4 is rolled up from the inside to the outside of the tire axial direction by sandwiching the bead core 1a and bead filler 1b. The carcass 4 is formed of a carcass ply formed by rubber-coating the carcass cords. The carcass cords are aligned in a direction that intersects the tire circumference (e.g., at an angle of 75 to 90 degrees relative to the tire circumference). The material of the carcass cords is preferably metal such as steel, polyester, rayon, nylon, aramid, or other organic fibers.

[0033] The tire T has a belt layer 5 stacked on the radially outer side of the tire carcass 4. The belt layer 5 is formed by stacking multiple (two sheets in this embodiment) belt layer plies. Each belt layer ply is formed by rubber-coating the belt layer cords. The belt layer cords are aligned in a direction inclined relative to the tire circumference (e.g., at an angle of 20 to 30 degrees relative to the tire circumference). The belt layer cords are preferably made of a metal such as steel. The multiple belt layer plies are stacked in such a way that the belt layer cords cross each other in opposite directions.

[0034] In this embodiment, a belt layer reinforcement 6 is laminated on the radially outer side of the belt layer 5. The belt layer reinforcement 6 is formed of a belt layer reinforcement fabric formed by rubber-coating the belt layer reinforcement cords. The belt layer reinforcement cords are substantially parallel to each other relative to the tire circumference. The belt layer reinforcement fabric is formed, for example, by spirally winding one or more rubber-coated belt layer reinforcement cords along the tire circumference. The material of the belt layer reinforcement cords is preferably the aforementioned organic fibers. The belt layer reinforcement 6 completely covers the belt layer 5, but it can also be partially (e.g., only at both ends) covering the belt layer 5.

[0035] The tread surface 3f, which forms the outer peripheral surface of the tread 3, has a tread pattern corresponding to the required tire performance and operating conditions. Figure 2 This is a plan view showing an example of the tread pattern of a pneumatic tire T. The tread pattern consists of tread blocks with a shape symmetrical about the tire equator TC. However, it is not limited to this; for example, it could be as follows: Figure 3 The pattern shown can also be a tread pattern with an asymmetrical shape relative to the tire equator TC.

[0036] The tire T has a main groove 7 and a transverse groove 8, which are grooves provided on the tread surface 3f. The main groove 7 extends continuously along the tire circumference, and the transverse groove 8 extends in a direction intersecting the main groove 7. The main groove 7 extends in a straight line, but is not limited to this. For example, it may have a shape that includes a portion inclined at an angle of less than 5 degrees relative to the tire circumference, and therefore may also be a groove that extends in a serrated shape along the tire circumference. In the case of a groove that extends in a serrated shape, it is preferable to include a transparent area (an area that can be seen without being obstructed by the groove wall surface 72 of the main groove 7 when viewed in the tire circumference direction).

[0037] Figure 4 This is a sectional view of the tire meridian of the main groove 7. Figure 5 This is a diagram showing the wall surface 72 of the main channel 7 viewed from the front. Figure 6 This is a top view of protrusion 40. It should be noted that, regarding protrusion 40, a top view (or top view) refers to a view (or manner) viewed from a direction perpendicular to the tank wall 72. Figure 7 (A) is a side view of protrusion 40, (B) is a sectional view along line A-A, and (C) is a sectional view along line B-B. Figure 8 This is a perspective view of protrusion 40. The structure of the main groove 7 described below can be applied to any one of the multiple main grooves 7 provided on the tread surface 3f, or it can be applied to all the main grooves 7.

[0038] like Figure 4 As shown, the main groove 7 has a groove bottom surface 71 and a pair of groove wall surfaces 72 extending radially outward from the groove bottom surface 71. The groove wall surfaces 72 are smoothly connected to the groove bottom surface 71 via a connecting surface 73 with an arcuate cross-section. The radius of curvature R of the connecting surface 73 is, for example, 1.5 to 3.5 mm. In this embodiment, the groove wall surface 72 extends in a straight line between the groove edge 74 formed by the tread surface 3f and the groove wall surface 72 and the radially outward end 75 of the connecting surface 73. The groove width W7 of the main groove 7 in the tire axial direction is, for example, 5.0 mm or more, preferably 6.0 mm or more. The groove depth D7 of the main groove 7 in the tire radial direction is, for example, 5.0 mm or more, preferably 6.0 mm or more.

[0039] like Figure 4 and5 As shown, the groove wall surface 72 includes a concave-convex region 10 with a plurality of protrusions 40 arranged thereon. Figure 5 The left and right directions are equivalent to the direction of the groove length (in the case of main groove 7, it is the tire circumference). Figure 5 The vertical direction corresponds to the groove depth direction (tire radial direction). The uneven region 10 is composed of a plurality of protrusions 40 that are repeatedly arranged in the groove length direction and groove depth direction, respectively. The plurality of protrusions 40 protrude from the groove wall surface 72, respectively. The uneven region 10 can be formed on at least one groove wall surface 72, but it is preferable to form it on a pair of groove wall surfaces 72, as in this embodiment.

[0040] Viewed from a direction perpendicular to the groove wall 72, the protrusion 40 has a shape with a long side direction LD and a short side direction SD orthogonal to it, tapering towards its two front ends in the long side direction LD. The long side direction LD of the protrusion 40 faces the radial direction of the tire. The protrusion 40 has a ridge 44, a first inclined surface 41, a second inclined surface 42, and a third inclined surface 43. The ridge 44 extends along the long side direction LD in the region on one side LD1 of the long side direction. The protrusion height of the first inclined surface 41 decreases from the ridge 44 towards the short side direction SD1. The protrusion height of the second inclined surface 42 decreases from the ridge 44 towards the other side SD2 of the short side direction. The third inclined surface 43 is disposed in the region on the other side LD2 of the long side direction, such that the protrusion height decreases towards the other side LD2 of the long side direction.

[0041] This structure improves traction against mud that has intruded into the groove, enhancing performance on rough roads. Since the long side LD of the protrusion 40 faces the tire radially (groove depth direction), the first inclined surface 41 and the second inclined surface 42 are positioned facing the groove length direction, providing traction by shearing the mud. The shape of the protrusion 40, tapering towards both sides of the long side LD, is suitable for using centrifugal force accompanying tire rotation to peel mud from the groove wall 72 and discharge it out of the groove. Furthermore, by arranging a third inclined surface 43 in the region LD2 on the other side of the protrusion 40's long side, the top view becomes simpler, allowing particles (plastic beads, glass beads, dry ice, etc.) during mold cleaning to easily intrude, thus suppressing mold contamination.

[0042] From the viewpoint of effectively improving the traction performance based on the uneven region 10, the angle of the long side direction LD relative to the tire radial direction is preferably less than 45 degrees, more preferably less than 30 degrees. In this embodiment, the long side LD1 of the protrusion 40 faces the bottom of the groove (inner radial direction of the tire). Therefore, the third inclined surface 43 faces the tread side (outer radial direction of the tire), which is suitable for discharging mud out of the groove. It is preferable not to provide the uneven region 10 on the bottom surface 71 of the groove, including the connecting surface 73. This is because the bottom surface 71 contributes less to the performance on rough roads in muddy terrain compared to the groove wall surface 72, and providing the uneven region 10 on the connecting surface 73 would require complex mold processing.

[0043] The protrusion 40 has a length L40 in the long side direction and a width W40 in the short side direction SD. The length L40 is, for example, set to be 2.0 to 5.0 times the width W40. The width W40 is preferably 0.5 mm or more, more preferably 1.0 mm or more. The width W40 is, for example, 3.0 mm or less. In this embodiment, a plurality of protrusions 40 with the same length L40 and width W40 are arranged to form a convex-concave region 10 (see reference). Figure 5 ).

[0044] The ridge 44 has an end 44a on one side LD1 in the long side direction and an end 44b on the other side LD2 in the long side direction. End 44a is substantially located on the groove wall surface 72. End 44b is located away from the groove wall surface 72, and its protrusion height gradually decreases from end 44b toward end 44a. End 44b is located in the region on one side LD1 in the long side direction with reference to the center of the protrusion 40 in the long side direction. In this embodiment, end 44b is positioned to overlap with the top 40t described later when viewed from above. The length L44 of the ridge 44 when viewed from above is, for example, set to be more than 20% and less than 45% of the length L40. Figure 7 The cross-sectional shape of the ridge 44 shown in (B) is sharp and V-shaped, but it can also be a shape that is curved, for example, by an arc with a radius of curvature of less than 0.5 mm.

[0045] The first inclined surface 41 and the second inclined surface 42 can also be formed by planes extending to the groove wall surface 72. In plan view, the first inclined surface 41 is tapered at its front end towards both sides in the long side direction LD. The first inclined surface 41 is triangular in plan view. The second inclined surface 42 is symmetrical to the first inclined surface 41 with respect to the edge line 44. In this embodiment, the opening angle θ between the first inclined surface 41 and the second inclined surface 42 is an obtuse angle (i.e., 90 degrees < θ < 180 degrees). This structure provides the following advantages: reducing snagging when removing the tire from the tire vulcanizing mold, or promoting the intrusion of the aforementioned particles during mold cleaning and suppressing contamination.

[0046] The third inclined surface 43 is disposed on the other side LD2 of the first inclined surface 41 and the second inclined surface 42 in the long side direction. The third inclined surface 43 may also be formed by a plane extending toward the groove wall surface 72. The third inclined surface 43 has a top view shape that tapers at the front end on both sides in the long side direction LD1. The portion of the third inclined surface 43 that tapers at the front end on the long side direction LD1 is disposed between the first inclined surface 41 and the second inclined surface 42 in the short side direction SD. The protrusion 40 has a top 40t in the region on the long side direction LD1, which is the part furthest from the groove wall surface 72, and the third inclined surface 43 extends from the top 40t toward the other side LD2 in the long side direction. With the groove wall surface 72 as a reference, the top 40t is located at a position higher than the end 44b, but their height positions may also be the same.

[0047] The boundary 45 between the first inclined surface 41 and the third inclined surface 43 extends obliquely from the end 44b toward the opposite side LD2 in the long side direction and toward the opposite side SD1 in the short side direction. The boundary 46 between the second inclined surface 42 and the third inclined surface 43 extends obliquely from the end 44b toward the opposite side LD2 in the long side direction and toward the opposite side SD2 in the short side direction. Boundaries 45 and 46 extend in a straight line when viewed from above, forming a Y-shape together with the edge line 44. Boundaries 45 and 46 may also extend in a curved shape when viewed from above. In this embodiment, boundaries 45 and 46 are formed in a stepped shape, but they may also be structures formed by the edge line.

[0048] Viewed from a direction perpendicular to the groove wall 72, the third inclined surface 43 is larger than both the first inclined surface 41 and the second inclined surface 42. That is, in a top view, the third inclined surface 43 has a larger area than the first inclined surface 41 and a larger area than the second inclined surface 42. This allows for a simpler top view shape for the protrusion 40, making it suitable for suppressing mold contamination. In a top view, the front end of the third inclined surface 43 on the other side of the long side LD2 is sharply V-shaped, but it could also be... Figure 6 A shape with rounded corners, as shown by the dashed line.

[0049] like Figure 6 Thus, the protrusion 40 forms a rhombus shape when viewed from above. In this embodiment, the top-view shape of the protrusion 40 is essentially composed of three surfaces (first to third inclined surfaces 41 to 43). Therefore, the size of each inclined surface is easily ensured. Furthermore, because the protrusion 40 has such a simple shape, compared to cases with more complex shapes, particle intrusion during mold cleaning becomes easier, thus it is suitable for suppressing mold contamination. The surface roughness of the first to third inclined surfaces 41 to 43 can be substantially the same as each other, or it can be different for each surface.

[0050] The protrusion 40 has a protrusion height H40 from the channel wall surface 72 to the top 40t. From the viewpoint of effectively improving the traction effect based on the uneven area 10, the protrusion height H40 is preferably 0.1 mm or more, more preferably 0.3 mm or more. Furthermore, to avoid excessively reducing drainage performance, the protrusion height H40 is preferably 0.5 mm or less. The ratio of width W40 to protrusion height H40 (W40 / H40) is, for example, 1.2 to 10.0. The flat shape of the protrusion 40 is suitable for effectively removing soil that has entered between the protrusions 40 from the channel wall surface 72.

[0051] like Figure 5 As shown, gaps 50 can also be provided between adjacent protrusions 40. That is, multiple protrusions 40 can also be arranged in a manner that corresponds to the gaps 50 and do not contact each other. However, from the viewpoint of adequately ensuring the arrangement density of the protrusions 40, the size of the gaps 50 is preferably 1.0 mm or less. Alternatively, the size of the gaps 50 can be substantially zero, and adjacent protrusions 40 can be arranged in a manner that allows them to contact each other.

[0052] exist Figure 5 In the example shown, multiple rows of protrusions 40A are formed, arranged along the short side direction SD. The phase of each row of protrusions 40A is offset by half a phase relative to the phase of its adjacent rows of protrusions 40A in both the long side direction LD and the short side direction SD. According to this structure, since the paved surface is provided with protrusions 40 that taper towards both sides in the long side direction LD, the traction effect based on the uneven area 10 can be improved, significantly enhancing the performance for traversing rough roads on muddy ground.

[0053] From the viewpoint of improving performance on muddy and rough roads, the length L10 of the uneven region 10 in the groove length direction is preferably 50% or more, more preferably 80% or more, of the length L72 of the groove wall surface 72 in the groove length direction. When the transverse groove 8 is open in the groove wall surface 72 of the main groove 7, the lengths L10 and L72 are measured within the range of the two adjacent transverse grooves 8 along the tire circumference. When the transverse groove 8 is not open in the groove wall surface 72 of the main groove 7, the lengths L10 and L72 are measured within one circumference of the tire. The length L72 is determined from the groove edge 74.

[0054] In this embodiment, the outer radial end 76 of the uneven region 10 is located at the groove edge 74, and the inner radial end 77 of the uneven region 10 is located at the outer radial end 75 of the connecting surface 73. This structure ensures the size of the uneven region 10 in the groove depth direction, thus improving its performance on rough roads, particularly muddy surfaces. The outer end 76 of the uneven region 10 can be located radially inward from the groove edge 74, but is preferably located radially outward from the center of the groove depth. Similarly, the inner end 77 of the uneven region 10 can also be located radially outward from the outer end 75 of the connecting surface 73, but is preferably located radially inward from the center of the groove depth.

[0055] When the area ratio of the concave-convex region 10 to the area between the groove edge 74 and the outer end 75 of the connecting surface 73 (wherein, the opening area of ​​the transverse groove 8 is excluded) is called the configuration range ratio, from the viewpoint of improving the performance of passing through bad roads on muddy ground, the configuration range ratio in at least one main groove 7 is preferably 50% or more, more preferably 80% or more.

[0056] In this embodiment, an example is shown where the groove wall surface 72 of the main groove 7 includes the uneven region 10. However, it is also possible to construct the groove wall surface of the transverse groove 8 to include the uneven region as described above, either alternatively or based on this. In the transverse grooves of winter tires or all-season tires (e.g., mud and snow tires marked "M&S" or "M+S"), when the radially outer end of the uneven region of the tire is located at approximately 50% (e.g., 40-60%) of the groove depth of the transverse groove 8, an edge effect based on the groove edge of the transverse groove 8 is achieved up to the middle of wear. In the subsequent stage where it functions as a summer tire, the uneven region of the groove wall surface can improve the performance on rough roads in muddy conditions.

[0057] exist Figure 9 In the modified example of the protrusion 40 shown, the boundaries 45 and 46 are rounded. Arc-shaped curved surfaces protruding away from the groove wall surface 72 are provided on the boundaries 45 and 46 respectively. A curved surface of the same shape is also provided between the third inclined surface 43 and the groove wall surface 72 in the region LD2 on the other side of the long side of the protrusion 40. According to this structure, the following advantageous effects can be obtained: reduced snagging when removing the tire from the tire vulcanizing mold, and improved particle penetration and reduced contamination during mold cleaning.

[0058] Figure 10 This is a radial sectional view of the tire vulcanizing mold M used in the vulcanization molding of the pneumatic tire T. Figure 10In the diagram, a tire T is represented by a dashed line. The tire T is positioned in the mold M such that its axial direction is upward and downward. The mold M includes a pair of bead rings Mb that fit into the bead portion 1 of the tire T, a pair of sidewall mold portions Ms that abut against the sidewall portion 2 of the tire T, and a tread mold portion Mt that abuts against the tread portion 3 of the tire T.

[0059] The mold M has a tire forming surface Mf that contacts the outer surface of the tire T disposed on the mold M. The tire forming surface Mf includes the inner surfaces of a pair of sidewall mold portions Ms and the inner surface of a tread mold portion Mt. The inner surface of the tread mold portion Mt has concave and convex surfaces for forming the tread pattern. The tread mold portion Mt is composed of multiple fan-shaped molds divided in the circumferential direction of the tire, which are aggregated and connected into a ring. The mold M is a segmented mold of the tread mold portion Mt having this segmented structure, but is not limited thereto; for example, it could also be two molds that are divided into two parts vertically at the center of the tread mold portion.

[0060] The mold M has a protrusion for forming a groove on the tread surface 3f of the tire T. Specifically, the mold M has a protrusion 9 for forming the main groove 7 and a protrusion 89 for forming the transverse groove 8 (see reference). Figure 12 During vulcanization, the tire forming surface Mf, including protrusions 9 and 89, is pressed onto the tread surface of the unvulcanized tire, thereby forming a tread pattern including main grooves 7 and lateral grooves 8.

[0061] Figure 11 This is a cross-sectional view of the tire meridian of protrusion 9. Figure 12 This is a diagram showing the side wall 92 of the protrusion 9 viewed from the front. Figure 11 and 12 Each is equivalent to making Figure 4 and Figure 5 The diagram is reversed. The protrusion 9 has a top surface 91 and a pair of sidewall surfaces 92 extending radially outward from the top surface 91. The sidewall surfaces 92 are smoothly connected to the top surface 91 via a connecting surface 93 with an arcuate cross-section. The sidewall surfaces 92 extend linearly between the inner corner edge 94 corresponding to the groove edge 74 of the main groove 7 and the radially outward end of the connecting surface 93 corresponding to the connecting surface 73 of the main groove 7. The sidewall surfaces 92 include a concave-convex region 90 with a plurality of recesses 100 arranged thereon.

[0062] Figure 13 This is a top view of the recess 100. Figure 14 (A) is a side sectional view of the recess 100, (B) is a sectional view along the C-C direction, and (C) is a sectional view along the D-D direction. Figure 14 Equivalent to making Figure 7The reversed diagram. When viewed from a direction perpendicular to the sidewall 92, the recess 100 has a shape with a long side direction LD and a short side direction SD orthogonal to it, tapering towards both sides of the long side direction LD. The recess 100 has: a mold ridge 104 extending along the long side direction LD in a region on one side LD1; a first mold slope 101, the recess depth of which decreases from the mold ridge 104 towards the short side direction SD1; a second mold slope 102, the recess depth of which decreases from the mold ridge 104 towards the other side SD2; and a third mold slope 103 disposed in a region on the other side LD2, the recess depth of which decreases towards the other side LD2.

[0063] The sidewall 92 and the recess 100 each have structures corresponding to the groove wall 72 and the protrusion 40, respectively. Furthermore, the mold ridge 104, the first mold inclined surface 101, the second mold inclined surface 102, and the third mold inclined surface 103 of the recess 100 each have structures corresponding to the ridge 44, the first inclined surface 41, the second inclined surface 42, and the third inclined surface 43 of the protrusion 40, respectively. Based on this mold M, an inflatable tire T can be obtained in which the groove wall 72 of the main groove 7 includes a concave-convex region 10 formed by arranging a plurality of protrusions 40. Regarding the structure of this tire T, see [reference needed]. Figures 1-9 As already explained, this improves the performance of the vehicle on rough roads, such as muddy terrain. For details regarding other structures, preferred dimensions, shapes, configurations, and variations related to the recess 100, please refer to the description already given regarding the protrusion 40.

[0064] Those skilled in the art will understand that the above-described embodiments are specific examples of the following schemes. [1]

[0066] The pneumatic tire disclosed herein has a groove provided on the tread surface. The groove wall includes a plurality of protruding, uneven regions. When viewed from a direction perpendicular to the groove wall, the protrusions have a long side direction and a short side direction orthogonal to it, tapering towards both sides of the long side direction. The long side direction of the protrusions faces the radial direction of the tire. The protrusions have: a ridge extending along the long side direction in a region on one side of the long side; a first inclined surface whose protrusion height decreases from the ridge towards the short side; a second inclined surface whose protrusion height decreases from the ridge towards the other side of the short side; and a third inclined surface located in a region on the other side of the long side, whose protrusion height decreases towards the other side of the long side. According to this structure, the performance on rough roads in muddy terrain can be improved. [2]

[0068] Based on the pneumatic tire described above [1], the long side of the protrusion may face the bottom of the groove. Thus, the third inclined surface faces the tread side (radial outer side of the tire), which is suitable for discharging soil out of the groove. [3]

[0070] Based on the pneumatic tire described in [1] or [2] above, the first inclined surface and the second inclined surface may also be formed by planes extending to the groove wall. This ensures the size of the first and second inclined surfaces, thereby improving the traction effect based on the concave and convex areas. [4]

[0072] Based on any of the pneumatic tires described in [1] to [3] above, the opening angle between the first inclined plane and the second inclined plane can also be an obtuse angle. This structure is useful in reducing snagging during tire demolding and suppressing mold contamination. [5]

[0074] Based on any of the pneumatic tires described in [1] to [4] above, the third inclined plane can also be configured such that, when viewed from a direction perpendicular to the first reference plane, the third inclined plane is larger than both the first and second inclined planes. This simplifies the top-view shape of the protrusion, making it suitable for suppressing mold contamination. [6]

[0076] Based on any of the pneumatic tires described in [1] to [5] above, the groove wall surface can also be configured such that it is smoothly connected to the groove bottom surface via a cross-sectional arc-shaped connecting surface, and the groove bottom surface including the connecting surface does not have the uneven area. This is because the groove bottom surface contributes less to the performance of passing through muddy and rough roads compared to the groove wall surface, and setting the uneven area on the connecting surface requires difficult mold processing. [7]

[0078] Based on any of the pneumatic tires described in [1] to [6] above, the protrusion height of the protrusion may be less than 0.5 mm. This structure prevents excessive reduction in drainage performance. [8]

[0080] Based on any of the pneumatic tires in [1] to [7] above, the length of the protrusion in the long side direction can also be 2.0 to 5.0 times the width of the protrusion in the short side direction. [9]

[0082] Based on any of the pneumatic tires described in [1] to [8] above, it is also possible to configure a plurality of columns of protrusions arranged along the short side direction, wherein the phase of each column of protrusions is offset by half a phase relative to the phase of the other adjacent columns of protrusions in both the long and short side directions of the protrusions. Thus, by covering the entire surface with protrusions, traction based on uneven areas can be improved, significantly enhancing performance on rough roads, particularly muddy terrain.

[10]

[0084] The tire vulcanizing mold disclosed herein includes a protrusion for forming grooves disposed on the tread surface of a tire. The sidewall of the protrusion includes an uneven region with a plurality of recesses arranged therein. When viewed from a direction perpendicular to the sidewall, the recesses have a shape having a long side direction and a short side direction orthogonal to it, tapering towards both sides in the long side direction. The long side direction of the recesses faces the tire radially. The recesses have: a mold ridge extending along the long side direction in a region on one side; a first mold slope whose depth decreases from the mold ridge towards the short side direction; a second mold slope whose depth decreases from the mold ridge towards the other side in the short side direction; and a third mold slope disposed in a region on the other side in the long side direction, whose depth decreases towards the other side in the long side direction. According to this structure, since the groove wall of the groove disposed on the tread surface of the vulcanized tire includes the uneven region described above, it is possible to improve the performance on rough roads, such as muddy surfaces.

[0085] The pneumatic tire disclosed herein, except for the grooves forming the tread surface as described above, can be constructed in the same manner as a conventional pneumatic tire, and conventionally known materials, shapes, structures, and manufacturing methods can all be used.

[0086] The tire vulcanizing mold disclosed herein, except for the protrusions that form grooves for shaping the tread surface as described above, can be constructed in the same manner as a conventional tire vulcanizing mold, and conventionally known materials, shapes, structures, mechanisms, etc., can be used.

[0087] This disclosure is not limited to the embodiments described above, and various modifications and improvements can be made without departing from its spirit. Furthermore, the structures used in the above embodiments can be arbitrarily combined and employed.

Claims

1. A pneumatic tire, characterized in that, The pneumatic tire has grooves provided on the tread surface. The groove wall includes a plurality of protruding, uneven areas. When viewed from a direction perpendicular to the groove wall, the protrusion has a long side and a short side perpendicular to it, tapering towards both sides of the long side. The long side of the protrusion faces the radial direction of the tire. The protrusion has: An edge line, which extends along the long side in the region on one side of the long side; The first inclined surface has a protrusion height that decreases from the edge towards the shorter side. The second inclined plane has a protrusion height that decreases from the edge towards the other side in the direction of the shorter side; as well as The third slope, located in the area on the other side of the long side, has a protrusion height that decreases towards the other side of the long side.

2. The pneumatic tire according to claim 1, characterized in that, The long side of the protrusion faces the bottom of the groove.

3. The pneumatic tire according to claim 1, characterized in that, The first inclined surface and the second inclined surface are respectively formed by planes extending to the wall surface of the groove.

4. The pneumatic tire according to claim 1, characterized in that, The opening angle between the first inclined plane and the second inclined plane is an obtuse angle.

5. The pneumatic tire according to claim 1, characterized in that, When viewed from a direction perpendicular to the groove wall, the third inclined plane is larger than the first and second inclined planes.

6. The pneumatic tire according to claim 1, characterized in that, The wall surface of the trough is smoothly connected to the bottom surface of the trough via a connecting surface with a circular arc cross section. The uneven area is not provided on the bottom surface of the groove containing the connecting surface.

7. The pneumatic tire according to claim 1, characterized in that, The protrusion height is less than 0.5 mm.

8. The pneumatic tire according to claim 1, characterized in that, The length of the protrusion along its long side is 2.0 to 5.0 times the width of the protrusion along its short side.

9. The pneumatic tire according to any one of claims 1 to 8, characterized in that, The protrusions are arranged in multiple rows along the short side direction. The phase of the protrusion column is offset by half a phase relative to the phase of the other adjacent protrusion columns in both the long and short side directions of the protrusion.

10. A tire vulcanizing mold, characterized in that, The tire vulcanizing mold has protrusions for forming grooves provided on the tread surface of the tire. The sidewall of the protrusion includes a concave-convex region with a plurality of recesses arranged thereon. When viewed from a direction perpendicular to the sidewall, the concave portion has a long side direction and a short side direction orthogonal to it, tapering towards both sides in the long side direction and towards the front end. The long side of the recess faces the radial direction of the tire. The recess has: The mold edge line extends along the long side in the region on one side of the long side. The first mold slope has a recess depth that decreases from the mold edge towards the shorter side. The second mold bevel, the depth of which decreases from the mold ridge towards the other side in the direction of the shorter side; and The third mold slope is located in the area on the other side of the long side, and the depth of the recess decreases towards the other side of the long side.

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