Tread forming die
The tread forming die addresses the issue of premature bending and cracking in thin blades by incorporating a projection at the blade corners to distribute stress, improving durability and reducing damage during tire molding.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SUMITOMO RUBBER INDUSTRIES LTD
- Filing Date
- 2024-12-26
- Publication Date
- 2026-07-08
AI Technical Summary
Thinned blades in tread vulcanization molds are prone to premature bending and cracking due to stress concentration at their corners during the expansion process, which affects the durability and performance of tires with variable-depth sipes.
A tread forming die with a blade design featuring a thickness of 0.3 mm or less, including a first portion and a second portion with different heights, and a projection at the corner to locally increase thickness, distributing bending stress and reinforcing the blade corners.
The die effectively suppresses bending and cracking at the blade corners, enhancing the durability and reducing the risk of damage during the tire molding process.
Smart Images
Figure 2026114779000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a tread forming die.
Background Art
[0002] In the land portions such as the blocks and ribs of the tread portion of a tire, narrow cuts called sipes are provided. Such sipes enhance the frictional force on wet road surfaces and icy / snowy road surfaces by their edges, improving the running performance. In recent years, sipes having variable depths have also been proposed (see, for example, FIG. 3 of Patent Document 1 below). Such variable-depth sipes include, for example, a main body portion and a shallow bottom portion having a depth smaller than that of the main body portion, and an in-corner-shaped corner portion is formed between them. When the variable-depth sipes contact the road surface, the opening of the sipes in the shallow bottom portion is suppressed compared to the main body portion, and thus, the wear resistance of the land portions and the like are improved.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] The variable-depth sipes as described above are formed by a blade (sometimes called a knife blade, but in this specification, the expression "blade" is used) implanted in a tread vulcanizing die. Such a blade includes, as an inverted shape of the variable-depth sipes, a first portion having a first height in the die radial direction and a second portion having a second height larger than the first height in the die radial direction, and an in-corner-shaped corner portion is provided between them.
[0005] In recent years, attempts have been made to minimize the thickness of the blade in order to suppress the decrease in ground rigidity and the deterioration of rolling resistance. However, such thinned blades have a problem in that when the tread vulcanization mold is moved radially outward from the tire to expand the diameter, stress concentrates at or near the corners of the blade, causing damage such as bending and cracking to occur prematurely.
[0006] This invention was devised in view of the above-described circumstances, and its main objective is to provide a tread molding die that can suppress damage such as bending and cracking at the corners of the blade. [Means for solving the problem]
[0007] The present invention relates to a tread forming die for forming the tread portion of a tire, comprising: a tread forming portion for forming the tread surface of the tread portion; and a blade extending inward from the tread forming portion in the diameter direction of the die for forming sipes, wherein the blade includes a blade body with a thickness of 0.3 mm or less, the blade body includes a first portion having a first height in the diameter direction of the die, and a second portion having a second height greater than the first height in the diameter direction of the die, the first portion includes a first edge extending inward in the blade length direction on the inside in the diameter direction of the die, the second portion includes a second edge extending inward from the first edge in the diameter direction of the die, and a projection is provided near the corner portion where the first edge and the second edge of the blade body intersect, projecting in the blade thickness direction to locally increase the blade thickness. [Effects of the Invention]
[0008] By adopting the above configuration, the tread molding die of the present invention can suppress damage such as bending and cracking at the corners of the blade. [Brief explanation of the drawing]
[0009] [Figure 1] This is a partial cross-sectional view of a tread molding die according to one embodiment of the present invention. [Figure 2] Figure 1 is a perspective view of the segment. [Figure 3] Figure 2 is a front view of the blade. [Figure 4] This is a magnified view of the key part of the corner section of the blade shown in Figure 3. [Figure 5] Figure 4 is a cross-sectional view along the VV line. [Figure 6] This is a cross-sectional view taken along the line VI-VI in Figure 4. [Figure 7] Figure 3 is a front view showing another example of the blade. [Figure 8] Figure 3 is a front view showing another example of the blade. [Figure 9] This is a cross-sectional view taken along line IV-IV in Figure 8. [Figure 10] Figure 1 is a partial perspective view of the tread portion of a tire that has been vulcanized using the mold shown in Figure 1. [Modes for carrying out the invention]
[0010] One embodiment of the present invention will be described below with reference to the drawings. The drawings contain exaggerations and representations that differ from the actual structural dimensional ratios in order to aid in understanding the present invention. Furthermore, where there are multiple embodiments, the same or common elements are denoted by the same reference numerals throughout the specification, and redundant descriptions are omitted. Moreover, the specific configurations shown in the embodiments and drawings are for the purpose of understanding the content of the present invention, and the present invention is not limited to the specific configurations shown in the illustrations.
[0011] [Tread molding die] Figure 1 is a partial cross-sectional view of a tread molding die (hereinafter sometimes simply referred to as "mold") 1 of one embodiment of the present invention, and Figure 2 is a perspective view of a segment 21 constituting the mold 1. As shown in Figures 1 and 2, the mold 1 includes a plurality of arc-shaped segments 21 (Figure 1 shows two adjacent segments 21, 21), and the plurality of segments 21 are arranged in the circumferential direction of the mold to form an annular body. Such a mold 1 can form various patterns on the annular tread portion 2 of a tire T. In this specification, "circumferential direction of the mold" means the direction corresponding to the tire circumferential direction of the tire T molded in the mold 1. Similarly, "radial direction of the mold" and "axial direction of the mold," described later, mean the directions corresponding to the tire radial direction and tire axial direction, respectively, of the tire T molded in the mold 1.
[0012] Each segment 21 is held in a manner that allows it to expand and contract in the diameter direction of the mold, for example, by a well-known actuator ring (not shown). In Figure 1, the mold closed state Y, in which the segments 21 are continuous with each other, is shown by a solid line. Also in Figure 1, the mold open state X, in which the segments 21 are separated from each other, is shown by a dashed line. The mold 1 is configured to be deformable between the mold closed state Y and the mold open state X by moving each segment 21 in the diameter direction along a reference line L that connects the circumferential center P of each segment 21 to the axis j of the mold 1. In the mold closed state Y, the tire T is vulcanized, and in the mold open state X, the tire T can be removed from the mold 1.
[0013] As shown in Figures 1 and 2, the mold 1 (segment 21) includes a tread-forming portion 3 and a blade 4 on its inner circumferential surface in the radial direction of the mold.
[0014] The tread-forming portion 3 is the surface that forms the tread surface S of the tread portion 2, and is formed, for example, as a smooth surface.
[0015] The blade 4 is configured as a thin plate-like body extending radially inward in the die diameter direction from the tread forming portion 3, and forms sipes in the tread portion 2. In this specification, "sipe" means a narrow cut with such a width that at least a part of the opposing wall surfaces come into contact with each other when the tire T contacts the road surface.
[0016] Each blade 4 is, for example, fixed with the root portion on the outer side in the die radial direction of the blade 4 embedded in the tread forming portion 3. Also, the blade 4 of this embodiment extends in the die axial direction and is formed in a plurality in the die circumferential direction so as to form a plurality of sipes extending in the tire axial direction. Further, as shown in FIG. 1, each blade 4 extends along the die radial direction. Therefore, the extension line of the line segment connecting the root and the tip of the blade 4 substantially coincides with the axis j of the die 1. In other embodiments, the blade 4 may be provided inclined with respect to the die radial direction, or may extend in the die circumferential direction so as to form sipes extending in the tire circumferential direction.
[0017] FIG. 3 is an enlarged front view of the blade 4 of this embodiment. The front view of the blade 4 means a view seen from a direction orthogonal to the blade plane. As shown in FIGS. 2 and 3, the blade 4 includes a blade body 5 having a thickness t1 (shown in FIG. 2) of 0.3 mm or less. In this embodiment, the blade body 5 constitutes the main part of the blade 4. More specifically, the blade body 5 of this embodiment constitutes the part of the blade 4 excluding a protruding portion 11 described later, and is formed with a substantially constant thickness.
[0018] The blade body 5 of this embodiment includes a first portion 6 and a second portion 7 having different heights in the die radial direction from the tread forming portion 3.
[0019] The first portion 6 has a first height H1 from the tread forming portion 3 inward in the die radial direction. Also, the second portion 7 has a second height H2 greater than the first height H1 from the tread forming portion 3 in the die radial direction. The blade body 5 of this embodiment includes the first portions 6, 6 on both sides in the blade length direction of the second portion 7.
[0020] In this embodiment, the first height H1 and the second height H2 are substantially constant in the direction of the blade length. In other embodiments, the first height H1 and the second height H2 may vary in the direction of the blade length.
[0021] The first part 6 includes a first edge 8 that extends in the direction of the blade length along the inside of the mold in the radial direction. The first edge 8 is the so-called tip (free end) of the first part 6.
[0022] The second portion 7 includes a second edge 9 extending radially inward from the first edge 8. The second edge 9 is the lateral edge of the portion of the second portion 7 that protrudes radially inward from the first portion 6.
[0023] The blade body 5 includes a corner portion 10 between the first portion 6 and the second portion 7. Figure 4 is an enlarged view of the main part of one corner portion 10 of the blade 4 in Figure 3. As shown in Figures 3 and 4, the corner portion 10 is the position where the first edge 8 and the second edge 9 intersect. As described above, the vicinity of this corner portion 10 is a region that is susceptible to bending stress and the like during demolding. In this specification, the vicinity of the corner portion 10 includes the region enclosed by a circle r with a radius of 5 mm centered on the corner portion 10. In a preferred embodiment, the corner portion 10 may be provided with an arc-shaped chamfer. When such a chamfer is provided, the corner portion 10 is set at the midpoint of the length of the arc of the chamfer.
[0024] The angle between the first edge 8 and the second edge 9 (hereinafter referred to as the angle θ of the corner portion 10) may be acute or obtuse, but is preferably between 90 and 120 degrees. This allows for the formation of sipes of different depths while effectively suppressing deformation of the second portion 7 relative to the first portion 6. In this embodiment, the angle θ of the corner portion 10 is substantially 90 degrees.
[0025] Figures 5 and 6 are cross-sectional views of line VV and line VI-VI in Figure 4, respectively. As shown in Figures 4 to 6, a protrusion 11 is provided near the corner portion 10 of the blade body 5. The protrusion 11 extends from the blade body 5 in the direction of blade thickness to locally increase the blade thickness. Such a protrusion 11 can reinforce the corner portion 10 of the blade 4 by forming a thicker section with locally increased blade thickness.
[0026] As described above, during demolding, when transitioning from the closed mold state Y to the open mold state X, the blade 4 is susceptible to bending stress as it is pulled out from the tread portion 2 of the tire T. In particular, the bending stress tends to concentrate near the corner portion 10 between the first portion 6 and the second portion 7 of the blade 4. In addition, the blades 4 located on both ends of the mold in the circumferential direction of the segment 21 tend to experience the above bending stress more significantly. On the other hand, as in this embodiment, by providing a protrusion 11 near the corner portion 10 of the blade 4, the bending stress acting on the corner portion 10 is widely distributed to its surroundings, thereby suppressing damage to the corner portion 10 of the blade 4.
[0027] To more effectively obtain the above-mentioned effects, the thickness t2 of the blade 4 at the location where the protrusion 11 is provided is set to, for example, 1.3 times or more, preferably 1.5 times or more, the thickness t1 of the blade body 5. On the other hand, if the thickness t2 of the blade 4 at the location where the protrusion 11 is provided is excessively large, it may increase the weight of the mold and also increase the width of the sipe. From this viewpoint, the thickness t2 is set to, for example, 2.2 times or less, of the thickness t1, preferably 2.0 times or less.
[0028] As shown in Figure 3, the corner portions 10, 10 of this embodiment are formed on both sides of the blade length direction of the second portion 7. Figure 4 shows one corner portion 10, but the other corner portion 10 also has a similar protrusion 11. Therefore, in this embodiment, damage is suppressed at the corner portions 10, 10 on both sides of the blade 4.
[0029] As shown in Figures 5 and 6, the blade body 5 has a first surface 14 and a second surface 15 in the blade thickness direction, but it is preferable that the protrusions 11, 11 are provided on both sides of the first surface 14 and the second surface 15. This configuration reduces the anisotropy of the blade 4 with respect to bending. Therefore, at the corner portion 10, regardless of whether the force is applied from the first surface 14 or the second surface 15, the bending of the blade 4 can be suppressed in a balanced manner.
[0030] As shown in Figure 4, in a preferred embodiment, the projection 11 preferably includes a first rib 12 extending from the first edge 8 to the second edge 9. Since such a first rib 12 extends across the first portion 6 and the second portion 7, it can effectively suppress deformation of the second portion 7 relative to the first portion 6. Thus, the first rib 12 can provide effective reinforcement while reducing the projection thickness, which helps to form a narrower sipe.
[0031] In a preferred embodiment, the first rib 12 extends in an arc shape in the front view of the blade 4. This allows it to resist bending stresses acting on the corner portion 10 in various directions.
[0032] The center of curvature of the arc-shaped first rib 12 is preferably located at the corner portion 10. This allows bending stresses acting near the corner portion 10 to be more effectively distributed to the surrounding area, thereby more reliably suppressing damage at the corner portion 10.
[0033] In a preferred embodiment, the projection 11 includes a plurality of second ribs 13 extending radially from the corner portion 10. In this embodiment, each second rib 13 extends radially from the corner portion 10 and is connected to the first rib 12. Such second ribs 13 can also withstand bending stresses acting on the corner portion 10 in various directions. In this embodiment, three second ribs 13 are formed, but the number is not particularly limited and may include two or four or more second ribs 13. Furthermore, the projection 11 may consist only of second ribs 13.
[0034] The second ribs 13 are preferably arranged at equal angular intervals. In this embodiment, three second ribs 13 are arranged so as to divide the 270-degree range of the blade 4 forming the corner portion 10 into four roughly equal parts. That is, the second ribs 13 are arranged at approximately 67.5-degree angular intervals. In other embodiments, two second ribs 13 may be arranged at approximately 135-degree angular intervals, or four or more second ribs 13 may be arranged at equal angular intervals. In a preferred embodiment, the second ribs 13 are arranged at equal angular intervals of less than 90 degrees. Such second ribs 13 distribute bending stress and other forces acting on the corner portion 10 evenly around it.
[0035] While not particularly limited, the rib width W (width perpendicular to the longitudinal direction of the rib) of the first rib 12 and the second rib 13 is preferably formed to be, for example, about 0.2 to 0.6 mm. Furthermore, the cross-sectional shape of the first rib 12 and the second rib 13 is preferably tapered, as shown in Figures 5 and 6, such that the rib width W decreases as it protrudes. Such a cross-sectional shape is preferable because it can suppress stress concentration near the base of the first rib 12 and the second rib 13.
[0036] The mold 1 of this embodiment can be used to vulcanize the tread portion of various tires, particularly pneumatic tires. In particular, the mold 1 of this embodiment can be suitably used for heavy-duty pneumatic tires such as those for trucks and buses, where the rubber volume of the tread portion 2 is large, making it easier for greater bending stress to act on the blade 4. In the case of the mold 1 for vulcanizing such heavy-duty pneumatic tires, the second height H2 of the second portion 7 of the blade 4 is preferably 15 mm or more. Also, the first height H1 is preferably 2 / 2 of the second height H2. This makes it possible to increase the second height H2 while ensuring a sufficient first height H1, thereby effectively suppressing bending of the blade 4.
[0037] The aforementioned protrusion 11 effectively suppresses damage at the corner portion 10 of the blade 4. However, as shown in Figure 3, if the width of the second portion 7 (the dimension of the second portion 7 in the blade length direction) is large, large bending stress may act on the central portion of the blade 4 in the blade length direction. To resist such bending stress, a central protrusion 11a protruding in the blade thickness direction may be provided in the central portion to locally increase the blade thickness. In particular, if the width of the second portion 7 is, for example, 23 mm or more, it is preferable to provide a central protrusion 11a. Furthermore, the thickness of the blade 4 at the location where the central protrusion 11a is provided is, for example, 1.3 times or more, preferably 1.5 times or more, and 2.2 times or less, preferably 2.0 times or less, the thickness t1 of the blade body 5. In this specification, "central portion" refers to the region including the center of the blade 4 in the blade length direction.
[0038] Figure 7 is a front view of the blade 4 in another embodiment. In the embodiment shown in Figure 3, the first portion 6 is provided on both sides of the second portion 7 in the blade length direction. However, as shown in Figure 7, the blade body 5 may have the first portion 6 on only one side of the second portion 7 in the blade length direction. In this embodiment as well, damage to the corner portion 10 can be suppressed by providing a protrusion 11 therein.
[0039] Figure 8 is a front view of the blade 4 showing a modified example of the protrusion 11. Figure 9 is a cross-sectional view taken along line IX-IX in Figure 8. In Figure 4, the protrusion 11 is shown as a rib, but the protrusion 11 may also be composed of a solid mass such that the area near the corner portion 10 is thickened, as shown in the protrusion 11 of Figures 8 and 9. Such a protrusion 11 can also firmly suppress damage to the corner portion 10 of the blade 4.
[0040] Figure 10 is a partial perspective view of the tread portion 2 of a tire T that has been vulcanized using the mold 1 of this embodiment. This tire T is, for example, a heavy-duty pneumatic tire for trucks and buses, but it may also be a passenger car tire.
[0041] As shown in Figure 10, the tire T has a tread portion 2. The tread portion 2 includes a tread surface S and sipes 4t extending radially inward from the tread surface S. The sipes 4t include a sipe body 5t with a width W1 of 0.3 mm or less. Such a sipe body 5t has an inverted shape of a blade body 5.
[0042] The width W1 of a sipe 4t is measured with a tire in its normal state. Here, "normal state" refers to a tire mounted on a normal rim and filled to the normal internal pressure in an unloaded state. Unless otherwise specified, the dimensions of each part of the tire are values measured in this normal state.
[0043] A "standard rim" is a rim defined for each tire within the standards system on which the tire is based, including the standards on which the tire is based. For example, it is a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO.
[0044] "Regular internal pressure" refers to the air pressure specified for each tire by each standard within the tire standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."
[0045] The sipe body 5t of this embodiment includes a first sipe portion 6t and a second sipe portion 7t, each having a different depth from the tread surface S.
[0046] The first sipe portion 6t has a first depth D1 extending inward from the tread surface S in the tire radial direction. The second sipe portion 7t has a second depth D2 extending radially from the tread surface S that is greater than the first depth D1. The sipe body 5t of this embodiment is provided with the first sipe portions 6t, 6t on both sides of the second sipe portion 7t in the sipe length direction.
[0047] The first sipe portion 6t includes a first bottom portion 8t that extends in the sipe length direction on the inside in the tire radial direction. The first bottom portion 8t is the sipe bottom of the first sipe portion 6t.
[0048] The second sipe portion 7t includes a second side portion 9t extending radially inward from the first bottom portion 8t. The second side portion 9t is the sipe side of the second sipe portion 7t.
[0049] The sipe body, 5t thick, has a corner section 10t thick between the first sipe section 6t thick and the second sipe section 7t thick. The corner section 10t thick is the part where the first bottom section 8t thick and the second side section 9t thick intersect, and is an inward corner.
[0050] A widened portion 11t is provided near the corner portion 10t of the sipe body 5t. The widened portion 11t protrudes from the sipe body 5t in the sipe width direction to locally increase the sipe width. The widened portion 11t of the sipe 4t is formed as an inverted shape of the protruding portion 11 of the blade 4. Such a tire T suppresses the decrease in rigidity of the tread portion 2, improves wear resistance, and reduces rolling resistance.
[0051] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be implemented in various modified forms.
[0052] [Note] The present invention includes the following embodiments.
[0053] [Invention 1] A tread molding die for forming the tread portion of a tire, A tread forming section for forming the tread surface of the tread portion, It includes a blade for forming a sipe, which extends inward in the radial direction of the mold from the tread forming portion, The aforementioned blade includes a blade body with a thickness of 0.3 mm or less. The blade body includes a first portion having a first height in the mold diameter direction and a second portion having a second height greater than the first height in the mold diameter direction. The first portion includes a first edge that extends in the direction of the blade length along the inside of the mold in the radial direction, The second portion includes a second edge extending radially inward from the first edge of the mold, Near the corner where the first edge and the second edge of the blade body intersect, a protrusion is provided that protrudes in the blade thickness direction to locally increase the blade thickness. Tread molding die. [2nd Invention] The tread molding die according to the present invention 1, wherein the thickness of the blade on which the protrusion is provided is 1.3 to 2 times the thickness of the blade body. [Invention 3] The blade body is provided with the first portion on both sides of the second portion in the direction of the blade length, The corner portions are formed on both sides of the second portion in the blade length direction, The tread molding die according to the present invention 1 or 2, wherein the protrusions are provided on each of the corner portions on both sides. [4th Invention] The tread molding die according to any one of inventions 1 to 3, wherein the angle between the first edge and the second edge is 90 to 120 degrees. [5th Invention] The blade body has a first surface and a second surface in the blade thickness direction, The tread molding die according to any one of inventions 1 to 4, wherein the protrusions are provided on both sides of the first surface and the second surface. [Invention 6] The tread molding die according to any one of inventions 1 to 5, wherein the protruding portion includes a first rib extending from the first edge to the second edge. [7th Invention] The tread forming die according to the present invention, wherein the first rib extends in an arc shape in a front view of the blade as seen from a direction perpendicular to the blade plane. [8th Invention] The tread molding die according to the present invention, wherein the first rib extends in an arc shape with its center at the corner portion. [Invention 9] The tread molding die according to any one of inventions 1 to 8, wherein the protruding portion includes a plurality of second ribs extending radially from the corner portion side. [Invention 10] The tread molding die according to the present invention, wherein the second ribs are arranged at equal angular intervals. [Invention 11] The tread molding die according to any one of inventions 1 to 10, wherein the blade is provided with a central projection that protrudes in the blade thickness direction so as to locally increase the blade thickness in the central part in the blade length direction. [Invention 12] A tire having a tread portion, The tread portion includes a tread surface and sipes extending inward from the tread surface in the radial direction of the tire. The aforementioned sipe includes a sipe body with a width of 0.3 mm or less. The sipe body includes a first sipe portion having a first depth in the tire radial direction and a second sipe portion having a second depth greater than the first depth in the tire radial direction. The first sipe portion includes a first bottom portion that extends in the sipe length direction on the inner side in the tire radial direction, The second sipe portion includes a second side portion extending inward in the tire radial direction from the first bottom portion, Near the corner where the first bottom and second side of the sipe body intersect, a widening portion is provided that protrudes in the sipe width direction to locally increase the sipe width. tire. [Explanation of Symbols]
[0054] 1 Tread molding die 2 Tread section 3 Tread forming part 4 Blades 5 Blade body 6 Part 1 7 Part 2 8. First Edge 9. Second Edge 10 Corner Section 11 Protrusion T-tire
Claims
1. A tread molding die for forming the tread portion of a tire, A tread forming section for forming the tread surface of the tread portion, It includes a blade for forming a sipe, which extends inward in the radial direction of the mold from the tread forming portion, The aforementioned blade includes a blade body with a thickness of 0.3 mm or less. The blade body includes a first portion having a first height in the direction of the mold diameter and a second portion having a second height greater than the first height in the direction of the mold diameter. The first portion includes a first edge that extends in the direction of the blade length along the inside of the mold in the radial direction, The second portion includes a second edge extending radially inward from the first edge of the mold, Near the corner where the first edge and the second edge of the blade body intersect, a protrusion is provided that protrudes in the blade thickness direction to locally increase the blade thickness. Tread molding die.
2. The tread molding die according to claim 1, wherein the thickness of the blade on which the protrusion is provided is 1.3 to 2 times the thickness of the blade body.
3. The blade body is provided with the first portion on both sides of the second portion in the direction of the blade length, The corner portions are formed on both sides of the second portion in the blade length direction, The tread molding die according to claim 1, wherein the protrusions are provided on each of the corner portions on both sides.
4. The tread molding die according to claim 1, wherein the angle between the first edge and the second edge is 90 to 120 degrees.
5. The blade body has a first surface and a second surface in the blade thickness direction, The tread molding die according to claim 1, wherein the protrusions are provided on both sides of the first surface and the second surface.
6. The tread molding die according to any one of claims 1 to 5, wherein the protruding portion includes a first rib extending from the first edge to the second edge.
7. The tread forming die according to claim 6, wherein the first rib extends in an arc shape in a front view of the blade as seen from a direction perpendicular to the blade plane.
8. The tread molding die according to claim 7, wherein the first rib extends in an arc shape with its center at the corner portion.
9. The tread molding die according to claim 1, wherein the protruding portion includes a plurality of second ribs extending radially from the corner portion side.
10. The tread molding die according to claim 9, wherein the second ribs are arranged at equal angular intervals.
11. The tread molding die according to claim 1, wherein the blade is provided with a central projection that protrudes in the blade thickness direction so as to locally increase the blade thickness in the central part in the blade length direction.
12. A tire having a tread portion, The tread portion includes a tread surface and sipes extending inward from the tread surface in the radial direction of the tire. The sipe includes a sipe body with a width of 0.3 mm or less. The sipe body includes a first sipe portion having a first depth in the tire radial direction and a second sipe portion having a second depth greater than the first depth in the tire radial direction. The first sipe portion includes a first bottom portion that extends in the direction of the sipe length on the inner side in the radial direction of the tire, The second sipe portion includes a second side portion extending inward in the tire radial direction from the first bottom portion, Near the corner where the first bottom and second side of the sipe body intersect, a widening portion is provided that protrudes in the sipe width direction to locally increase the sipe width. tire.