Patent Publication Number: US-2022227085-A1

Title: Tire molding die and pneumatic tire

Description:
TECHNICAL FIELD 
     The present technology relates to a tire molding die and a pneumatic tire. 
     BACKGROUND ART 
     Some known pneumatic tires are provided with so-called sipes, which are cuts formed in a tread portion, in order to improve performance on ice and snow, which is running performance on snowy roads and frozen road surfaces, and wet performance, which is running performance on wet road surfaces, and the like. For example, in studless tires, which are required to have running performance on icy and snowy road surfaces, a large number of sipes on the road contact surface of the tread portion are disposed. Additionally, the pneumatic tire is manufactured by vulcanization molding using a tire molding die divided into a plurality of sectors in the tire circumferential direction. However, various defects are likely to occur during vulcanization molding at division positions of sectors, and thus, some known tire molding dies are designed to eliminate such defects. 
     For example, in a tire vulcanization mold described in Japan Unexamined Patent Publication No. 2012-011690, a turning point is provided on sipe blades disposed adjacent to the division positions of sectors. By modifying a portion from the turning point to the other end of the sipe blade further away from the division position than the original shape, separation of and damage to the sipe blade and the like are prevented during vulcanization release. Additionally, in a tire molding die described in Japan Unexamined Patent Publication No. 2009-255734, by making the sipe volume of the sipe forming blade at the end portion position of the sector greater than the sipe volume of the sipe forming blade at the central portion position of the sector, uneven wear of a land portion at or near the division position of sectors is effectively suppressed. 
     In this regard, in a tire molding die in which sipe blades are disposed in each of the sectors separated from one another, the blades are likely to be twisted in a case where the tire is detached from the mold after vulcanization molding of the tire. In particular, because the twist occurring in the blades is significant at or near the division position of sectors, the twist may cause failure such as bending or breakage of the blades. As described above, in the known tire molding dies that include a plurality of the sectors separated from one another in the tire circumferential direction and in which the sipe blades are disposed, there is room for improvement in terms of durability due to the likelihood of failure in the blades disposed at or near the division position of sectors. 
     SUMMARY 
     The present technology provides a tire molding die and a pneumatic tire that can improve durability of sipe blades. 
     A tire molding die according to an embodiment of the present technology includes a plurality of sectors separated from one another in a tire circumferential direction, and a plurality of sipe blades disposed on tread molding surfaces of the sectors, the sipe blades are disposed repeatedly in the tire circumferential direction in a repeating pattern corresponding to a predetermined arrangement pattern, a near sipe blade that is included in a plurality of the sipe blades disposed in one of the sectors and that is closest to a division position between the sectors being more rigid than an original shape blade corresponding to the sipe blade provided in the repeating pattern differing from the repeating pattern including the near sipe blade at a position identical to a position of the near sipe blade in the repeating pattern including the near sipe blade. 
     Additionally, in the tire molding die described above, preferably, a maximum height of the near sipe blade is smaller than a maximum height of the original shape blade. 
     Additionally, in the tire molding die described above, preferably, a ratio of a maximum height H 1  of the near sipe blade to a maximum height H 2  of the original shape blade is in a range 0.3≤(H 1 /H 2 )≤0.8. 
     Additionally, in the tire molding die described above, preferably, the near sipe blade has a relationship between the maximum height H 1  and a sipe volume V corresponding to a product of a length L, a width W, and the maximum height H 1  of the near sipe blade such that V∂H 1 . 
     Additionally, in the tire molding die described above, preferably, the near sipe blade and the original shape blade have a relationship between a number of bend points A 1  of the near sipe blade and a number of bend points A 2  of the original shape blade such that A 2 &lt;A 1 . 
     Additionally, in the tire molding die described above, preferably, the near sipe blade and the original shape blade have a relationship between a material strength S 1  of the near sipe blade and a material strength S 2  of the original shape blade such that S 2 &lt;S 1 . 
     Additionally, in the tire molding die described above, preferably, the near sipe blade and the original shape blade have a relationship between a surface roughness R 1  of the near sipe blade and a surface roughness R 2  of the original shape blade such that R 2 &gt;R 1 . 
     The pneumatic tire according to an embodiment of the present technology is vulcanized using the tire molding die described above. 
     The tire molding die and pneumatic tire according to an embodiment of the present technology have the effect of improving the durability of the sipe blades. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view illustrating a road contact surface of a tread portion of a pneumatic tire according to an embodiment. 
         FIG. 2  is an explanatory diagram of a tire molding die for manufacturing a pneumatic tire according to an embodiment. 
         FIG. 3  is a view taken along A-A in  FIG. 2  and is an explanatory diagram of a state in which sectors are connected together. 
         FIG. 4  is a cross-sectional view taken along B-B in  FIG. 3 , and is an explanatory diagram of the height of a near sipe blade. 
         FIG. 5  is a cross-sectional view taken along C-C in  FIG. 3 , and is an explanatory diagram of the height of an original shape blade. 
         FIG. 6  is a cross-sectional view taken along D-D in  FIG. 4 . 
         FIG. 7  is an explanatory diagram illustrating a tire manufacturing method using the tire molding die illustrated in  FIG. 2 . 
         FIG. 8  is an explanatory diagram illustrating a state before the tire molding die is detached from a pneumatic tire  1  after vulcanization molding. 
         FIG. 9  is an explanatory diagram illustrating a state in which the tire molding die is detached from the pneumatic tire after vulcanization molding. 
         FIG. 10  is a schematic plan view of a near sipe blade in a modified example of the tire molding die according to an embodiment. 
         FIG. 11  is a schematic plan view of an original shape blade in a modified example of the tire molding die according to an embodiment. 
         FIG. 12  is a table showing results of performance evaluation tests of the tire molding die. 
     
    
    
     DETAILED DESCRIPTION 
     A tire molding die and a pneumatic tire according to embodiments of the present technology will be described in detail below with reference to the drawings. However, the present technology is not limited by the embodiment. Constituents of the following embodiments include elements that are essentially identical or that can be substituted or easily conceived of by a person skilled in the art. 
     Embodiments 
     In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not illustrated) of a pneumatic tire  1 , the inner side in the tire radial direction refers to the side facing the rotation axis in the tire radial direction, and the outer side in the tire radial direction refers to the side away from the rotation axis in the tire radial direction. Moreover, the tire circumferential direction refers to the circumferential direction with the rotation axis as the central axis. Additionally, the tire width direction refers to a direction parallel with the rotation axis, the inner side in the tire width direction refers to a side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction refers to a side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire  1  and passes through the center of the tire width of the pneumatic tire  1 , and in the tire equatorial plane CL, the center line in the tire width direction, which is the center position of the pneumatic tire  1  in the tire width direction, coincides with the position in the tire width direction. The tire width is the width in the tire width direction between portions located on the outermost sides in the tire width direction, or in other words, the distance between the portions that are the most distant from the tire equatorial plane CL in the tire width direction. The term “tire equator line” refers to a line in the tire circumferential direction of the pneumatic tire  1  that lies on the tire equatorial plane CL. 
     Pneumatic Tire 
       FIG. 1  is a plan view of a road contact surface  3  of a tread portion  2  of the pneumatic tire  1  according to an embodiment. The pneumatic tire  1  illustrated in  FIG. 1  includes the tread portion  2  disposed at the outermost portion of the pneumatic tire  1  in the tire radial direction. The surface of the tread portion  2 , in other words, a portion that comes into contact with a road surface when a vehicle (not illustrated) equipped with the pneumatic tire  1  travels is formed as the road contact surface  3 . A plurality of grooves  10  are formed in the road contact surface  3 , and a plurality of land portions  15  are defined by a plurality of grooves  10 . The grooves  10  include, for example, a plurality of circumferential grooves  11  extending in the tire circumferential direction and a plurality of lug grooves  12  extending in the tire width direction. In the present embodiment, the lug grooves  12  are inclined in the tire circumferential direction while extending in the tire width direction, and the circumferential grooves  11  are formed between adjacent lug grooves  12  in the tire circumferential direction. The land portions  15  are block-shaped by the circumferential grooves  11  and the lug grooves  12 . 
     Additionally, a plurality of sipes  20  are formed in the road contact surface  3 . The sipes  20  described herein are formed in a narrow groove shape in the ground contact surface  3 . In the sipes  20 , when the pneumatic tire  1  is mounted on a regular rim, inflated to a regular internal pressure, and in an unloaded state, wall surfaces constituting the narrow groove do not contact one another, whereas in a case where the narrow groove is located in a portion of the ground contact surface formed on a flat plate in response to application of a load on the flat plate in the vertical direction or in a case where the land portion  15  provided with the narrow groove flexes, the wall surfaces constituting the narrow groove or at least parts of portions provided on the wall surface contact one another due to deformation of the land portion  15 . Here, “regular rim” refers to a standard rim defined by the Japan Automobile Tyre Manufacturers Association Inc. (JATMA), a “design rim” defined by the Tire and Rim Association, Inc. (TRA), or a “measuring rim” defined by the European Tyre and Rim Technical Organisation (ETRTO). Moreover, a regular internal pressure refers to a “maximum air pressure” defined by JATMA, the maximum value in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. 
     The sipes  20  are formed extending in the tire width direction at a predetermined depth, and are provided in each of the land portions  15  defined by the grooves  10 . Some of the sipes  20  bend in the tire circumferential direction while extending in the tire width direction and the sipes  20  vary in form. Additionally, the sipes  20  are disposed repeatedly in the tire circumferential direction in repeating patterns Pr corresponding to predetermined arrangement patterns. The repeating patterns Pr in this case are each configured by combining a plurality of the sipes  20 , and have an equal shape of the sipes  20  constituting the repeating pattern Pr, an equal number of the sipes  20 , and an equal relative positional relationship among the sipes  20 . In the present embodiment, a plurality of the sipes  20  disposed in a range in which the length of the repeating pattern Pr in the tire circumferential direction is identical to the length of the interval between two lug grooves  12  are formed as one repeating pattern Pr. 
     Additionally, pin holes  30  are formed in the road contact surface  3  of the tread portion  2  and used as holes in which stud pins (not illustrated) are disposed. A plurality of the pin holes  30  are formed in the road contact surface  3  regardless of a tread pattern such as the repeating pattern Pr of the sipes  20 . 
     Tire Molding Die 
     Now, a tire molding die  100  according to the embodiment will be described. Note that in the following description, the tire radial direction of the pneumatic tire  1  will be described as the tire radial direction in the tire molding die  100  and that the tire width direction of the pneumatic tire  1  will be described as the tire width direction of the tire molding die  100  and that the tire circumferential direction of the pneumatic tire  1  will be described as the tire circumferential direction in the tire molding die  100 . 
       FIG. 2  is an explanatory diagram of the tire molding die  100  for manufacturing the pneumatic tire  1  according to an embodiment. As illustrated in  FIG. 2 , the tire molding die  100  is configured as a so-called sector mold corresponding to a divided tire molding die  100 , and has an annular structure in which a plurality of sectors  101  separated from one another in the tire circumferential direction are connected to one another. Note that in  FIG. 2 , the tire molding die  100  is illustrated in the form of an eight-division structure including eight sectors  101 , but the number of divisions of the tire molding die  100  is not limited to eight. 
     One sector  101  includes a plurality of pieces  103  for forming the tread portion  2  of the pneumatic tire  1  corresponding to a product, and a back block  104  in which the pieces  103  are mounted adjacent to one another. One piece  103  corresponds to a portion of the tread pattern divided at a constant pitch or any pitch, and includes a tread molding surface  102  for forming a part of the tread pattern. One sector  101  includes a plurality of pieces  103  in the tire circumferential direction and the tire width direction, respectively (not illustrated), and the plurality of pieces  103  are assembled to constitute the tread molding surface  102  of one sector  101 . In other words, the piece  103  of one sector  101  is divided into a plurality of pieces  103 . 
     In the back block  104 , a plurality of pieces  103  are mounted and held in a predetermined arrangement. One sector  101  is thus configured. 
     The tire molding die  100  is configured by using a plurality of the sectors  101  configured as described above and connecting the plurality of sectors  101  in an annular shape. In the tire molding die  100 , the plurality of sectors  101  are connected together in an annular shape to assemble the tread molding surfaces  102  of the sectors  101 , forming the tread molding surface  102  of the entire tread pattern. 
       FIG. 3  is a view taken along A-A in  FIG. 2 , and is an explanatory diagram of a state in which the sectors  101  are connected together. In the tread molding surface  102  in each sector  101 , a plurality of circumferential groove forming bones  115  are disposed that form the circumferential grooves  11  in the tread portion  2  of the pneumatic tire  1 , a plurality of lug groove forming bones  116  are disposed that form the lug grooves  12 , a plurality of pin hole forming pins  117  are disposed that form the pin holes  30 , and a plurality of sipe blades  120  are disposed that form the sipes  20 . In this regard, the circumferential groove forming bones  115  and the lug groove forming bones  116  are formed in a rib-like shape protruding from the tread molding surface  102 , and the sipe blades  120  are formed as plate-like members formed from a metal material. For example, stainless steel is used as the metal material that forms the sipe blade  120 . 
     Additionally, the sipe blades  120  are disposed on the tread molding surface  102  such that the sipe blades  120  are identical in number to the sipes  20  formed in the tread portion  2 . The sipe blades  120  are disposed at positions in the tread molding surface  102  corresponding to positions in the tread portion  2  where the sipes  20  are disposed. Thus, like the sipes  20  formed in the tread portion  2  of the pneumatic tire  1 , the sipe blades  120  are disposed repeatedly in the tire circumferential direction in the repeating pattern Pr corresponding to a predetermined arrangement pattern. 
     A near sipe blade  121 , corresponding to the sipe blade  120  located closest to a division position  101   a  between the sectors  101  and included in the plurality of sipe blades  120  disposed in one sector  101 , is more rigid than an original shape blade  122 . The division position  101   a  between the sectors  101  in this case is an end portion of the sector  101  in the tire circumferential direction, and corresponds to a position where the sectors  101  adjacent to each other in the tire circumferential direction are connected to each other. Additionally, the near sipe blade  121  is typically disposed at a distance in a range of 10 mm from the division position  101   a.    
     In addition, the original shape blade  122  in this case is the sipe blade  120  located in the repeating pattern Pr differing from the repeating pattern Pr including the near sipe blade  121  at a position identical to the position of the near sipe blade  121  in the repeating pattern Pr including the near sipe blade  121 . In other words, the original shape blade  122  is the sipe blade  120  disposed in the repeating pattern Pr differing from the repeating pattern Pr including the near sipe blade  121  at a position corresponding to the position of the near sipe blade  121  within the repeating pattern Pr including the near sipe blade  121 . 
     Note that in a case where the sipe blade  120  located in the repeating pattern Pr differing from the repeating pattern Pr including the near sipe blade  121  at the position identical to the position of the near sipe blade  121  in the repeating pattern Pr including the near sipe blade  121  corresponds to another near sipe blade  121  differing from the near sipe blade  121 , as the original shape blade  122 , the sipe blade  120  located in further another repeating pattern Pr at the position identical to the position of the near sipe blade  121  in the repeating pattern Pr including the near sipe blade  121  is preferably used. 
       FIG. 4  is a cross-sectional view taken along B-B in  FIG. 3 , and is an explanatory diagram of the height of the near sipe blade  121 .  FIG. 5  is a cross-sectional view taken along C-C in  FIG. 3  and is an explanatory diagram of the height of the original shape blade  122 . The maximum height H 1  of the near sipe blade  121  in the tire radial direction from the tread molding surface  102  is smaller than the maximum height H 2  of the original shape blade  122  in the tire radial direction from the tread molding surface  102 . Specifically, the near sipe blade  121  and the original shape blade  122  are configured such that a ratio of the maximum height H 1  of the near sipe blade  121  to the maximum height H 2  of the original shape blade  122  is in the range of 0.3≤(H 1 /H 2 )≤0.8. The maximum height H 1  of the near sipe blade  121  is smaller than the maximum height H 2  of the original shape blade  122  as described above, and thus, the near sipe blade  121  is more rigid than the original shape blade  122 . 
     Note that in the present embodiment, the height of the sipe blade  120  in the tire radial direction from the tread molding surface  102  is in the range of 1 mm or more and 15 mm or less. Thus, both the maximum height H 1  of the near sipe blade  121  and the maximum height H 2  of the original shape blade  122  are in the range of 1 mm or more and 15 mm or less. 
       FIG. 6  is a diagram taken along D-D in  FIG. 4 . The near sipe blade  121  has a relationship between a sipe volume V corresponding to the volume of the near sipe blade  121  and the maximum height H 1  such that V∂H 1 . That is, the near sipe blade  121  has a proportional relationship between the sipe volume V and the maximum height H 1 . The sipe volume V in this case is the product of the length L, the width W, and the maximum height H 1  of the near sipe blade  121 . The length L along the near sipe blade  121  is a direction along the extension direction of the near sipe blade  121  or a length along the shape of the near sipe blade  121 , in a case where the near sipe blade  121  is viewed in the height direction. 
     Note that in the present embodiment, the thickness of the sipe blade  120  is in the range of 0.2 mm or more and 1.0 mm or less. Thus, the near sipe blade  121  and the width W are also in the range of 0.2 mm or more and 1.0 mm or less. 
     Tire Manufacturing Method 
     Now, a manufacturing method for the pneumatic tire  1  using the tire molding die  100  according to an embodiment will be described.  FIG. 7  is an explanatory diagram illustrating a tire manufacturing method using the tire molding die  100  illustrated in  FIG. 2 .  FIG. 7  illustrates an axial cross-sectional view of the mold support device  105  including the tire molding die  100  illustrated in  FIG. 2 . The pneumatic tire  1  according to the present embodiment is manufactured in accordance with manufacturing steps described below. 
     First, various rubber members (not illustrated) that constitute the pneumatic tire  1 , and members such as carcass plies (not illustrated) and belt plies (not illustrated) are applied to a molding machine to form a green tire G. Then, the green tire G is mounted on the mold support device  105  (see  FIG. 7 ). 
     In  FIG. 7 , the mold support device  105  includes a support plate  106 , an outer ring  107 , a segment  109 , a top plate  110  and a base plate  112 , an upper side mold  111  and a lower side mold  113 , and the tire molding die  100 . The support plate  106  has a disc shape and is disposed in a horizontal plane. The outer ring  107  is an annular structure having a tapered surface  108  on an inner side in the radial direction, and is mounted and suspended from a lower portion of an outer peripheral edge of the support plate  106 . The segment  109  is a divisible annular structure corresponding to the sectors  101  of the tire molding die  100  and is inserted into the outer ring  107  and disposed slidably in the axial direction relative to the tapered surface  108  of the outer ring  107 . The top plate  110  is installed movably in the axial direction inside the outer ring  107  and between the segment  109  and the support plate  106 . The base plate  112  is disposed below the support plate  106  and at a position opposite the support plate  106  in the axial direction. 
     The upper side mold  111  and the lower side mold  113  include molding surfaces with side profiles corresponding to both side surfaces of the pneumatic tire  1  in the tire width direction. Additionally, the upper side mold  111  and the lower side mold  113  are disposed such that the upper side mold  111  is attached to the lower surface side of the top plate  110 , the lower side mold  113  is attached to the upper surface side of the base plate  112 , and the molding surface of the upper side mold  111  faces the molding surface of the lower side mold  113 . As described above, the tire molding die  100  has a divisible annular structure (see  FIG. 2 ) with the tread molding surface  102  enabling a tread profile to be formed. Additionally, the sectors  101  of the tire molding die  100  are attached to the inner circumferential surfaces of the corresponding segments  109 , and the tire molding die  100  is disposed such that the tread molding surface  102  faces the side where the molding surfaces of the upper side mold  111  and the lower side mold  113  are located. 
     Then, the green tire G is mounted between the molding surface of the tire molding die  100  and the molding surfaces of the upper side mold  111  and the lower side mold  113 . At this time, the support plate  106  moves downward in the axial direction to move the outer ring  107  downward in the axial direction along with the support plate  106 , and the tapered surface  108  of the outer ring  107  pushes the segments  109  radially inward. Then, the tire molding die  100  is contracted in diameter to annularly connect the molding surfaces of the sectors  101  of the tire molding die  100 , and the entire molding surface of the tire molding die  100  is connected to the molding surface of the lower side mold  113 . Additionally, the top plate  110  moves downward in the axial direction to lower the upper side mold  111 , reducing the distance between the upper side mold  111  and the lower side mold  113 . Then, the entire molding surface of the tire molding die  100  is connected to the molding surface of the upper side mold  111 . Accordingly, the green tire G is surrounded and held by the molding surface of the tire molding die  100 , the molding surface of the upper side mold  111 , and the molding surface of the lower side mold  113 . 
     Then, the green tire G corresponding to an unvulcanized tire is subjected to vulcanization molding. Specifically, the tire molding die  100  is heated, and the green tire G is expanded radially outward by a pressurizing device (not illustrated) and pressed against the tread molding surface  102  of the tire molding die  100 . Then, the green tire G is heated, and rubber molecules and sulfur molecules in the tread portion  2  are bonded together, leading to vulcanization. Then, the tread molding surface  102  of the tire molding die  100  is transferred to the green tire G, forming the tread pattern in the tread portion  2 . 
     Subsequently, the tire after vulcanization molding is acquired as a product tire corresponding to the pneumatic tire  1  provided as a product. At this time, the support plate  106  and the top plate  110  move upward in the axial direction to space the tire molding die  100 , the upper side mold  111 , and the lower side mold  113  apart from one another, opening the mold support device  105 . In response to opening of the mold support device  105 , the tire molding die  100  detaches from the mold support device  105  with the tire subjected to vulcanization molding. 
       FIG. 8  is an explanatory diagram illustrating a state before the tire molding die  100  is detached from the pneumatic tire  1  after vulcanization molding. During vulcanization molding of the pneumatic tire  1  using the tire molding die  100 , the tread portion  2  is formed by the tire molding die  100 . Thus, immediately after vulcanization molding is performed, the tire molding die  100  is attached to the tread portion  2  of the pneumatic tire  1  (see  FIG. 8 ). Specifically, the plurality of sectors  101  of the tire molding die  100  are connected in an annular shape, and the tire molding die  100  is attached to the tread portion  2  of the pneumatic tire  1  immediately after vulcanization molding is performed. In response to completion of the vulcanization molding of the pneumatic tire  1  and detachment, of the tire molding die  100  from the mold support device  105 , the plurality of sectors  101  connected together in an annular shape and attached to the tread portion  2  of the pneumatic tire  1  are detached from the pneumatic tire  1 . Accordingly, the tire molding die  100  is detached from the pneumatic tire  1 . 
       FIG. 9  is an explanatory diagram illustrating a state in which the tire molding die  100  is detached from the pneumatic tire  1  after vulcanization molding. In a case that the plurality of sectors  101  are detached from the pneumatic tire  1 , the sectors  101  are moved toward the outer side in the tire radial direction and separated from the tread portion  2  of the pneumatic tire  1 . Accordingly, the tire molding die  100  is detached from the pneumatic tire  1 . In this case, during vulcanization molding of the pneumatic tire  1 , the plurality of sipe blades  120  disposed on the tread molding surfaces  102  of the sectors  101  of the tire molding die  100  form a plurality of sipes  20  in the road contact surface  3  of the tread portion  2 . In response to detachment of the sectors  101  of the tire molding die  100  from the pneumatic tire  1  by moving the sectors  101  toward the outer side in the tire radial direction, the plurality of sipe blades  120  disposed on the sectors  101  are extracted from the sipes  20  formed in the tread portion  2  of the pneumatic tire  1 . 
     In this regard, the sipe blades  120  disposed on the tread molding surfaces  102  of the sector  101  extend from the tread molding surfaces  102  generally toward the inner side in the tire radial direction. On the other hand, in a case of detaching the sectors  101  from the pneumatic tire  1 , the sectors  101  are moved toward the outer side in the tire radial direction. Thus, for the sipe blade  120  that is included in the plurality of sipe blades  120  disposed on one sector  101  and that is disposed in a central region of the sector  101  in the tire circumferential direction, the direction in which the sipe blade  120  extends from the tread molding surface  102  is similar to the direction in which the sector  101  is moved. 
     In contrast, for the sipe blade  120  that is included in the plurality of sipe blades  120  disposed on one sector  101  and that is disposed at or near the division position  101   a  between the sectors  101 , the direction in which the sipe blade  120  extends from the tread molding surface  102  is inclined with respect to the direction in which the sector  101  is moved. In other words, in a case where the sectors  101  are detached from the pneumatic tire  1 , one sector  101  is integrally moved, and thus, the direction in which the sector  101  is moved corresponds, even at or near the division position  101   a  between the sectors  101 , to the direction in which a position in a central region of the sector  101  in the tire circumferential direction is moved toward the outer side in the tire radial direction. Thus, the direction of movement of the division position  101   a  between the sectors  101  during detachment of the sectors  101  from the pneumatic tire  1  differs from the tire radial direction, and thus, the direction in which the sipe blade  120  disposed at or near the division position  101   a  between the sectors  101  moves during detachment of the sectors  101  from the pneumatic tire  1  differs from the direction in which the sipe blades  120  extends from the tread molding surface  102 . 
     In a case where the direction of movement of the sipe blades  120  during detachment of the sectors  101  from the pneumatic tire  1  differs from the direction in which the sipe blades  120  extend from the tread molding surface  102 , the direction of movement of the sipe blades  120  differs from the depth direction of the sipes  20  formed by the sipe blades  120 . In this case, because the force acts on the sipe blades  120  in a direction differing from the depth direction of the sipes  20  during movement of the sectors  101 , a strong reaction force from the rubber member forming the sipes  20  acts on the sipe blades  120 . In a case of detachment of the sectors  101  from the pneumatic tire  1 , a reaction force from the rubber member forming the sipes  20  acts on the sipe blade  120  disposed at or near the division position  101   a  between the sectors  101 , and is likely to cause failure such as bending or breakage of the sipe blade  120 . 
     Such failure is likely to occur in the sipe blade  120  disposed at or near the division position  101   a  between the sectors  101  during detachment of the sectors  101 . However, in the tire molding die  100  according to the present embodiment, the near sipe blade  121  disposed at or near the division position  101   a  between the sectors  101  is more rigid than the original shape blade  122 . Thus, even in a case where the force during detachment of the sectors  101  from the pneumatic tire  1  acts in a direction differing from the depth direction of the sipe  20  formed by the near sipe blade  121 , causing the reaction force from the rubber member forming the sipe  20  to act on the near sipe blade  121 , possible failure in the near sipe blade  121  due to the reaction force can be suppressed. As a result, the durability of the sipe blades  120  can be improved. 
     Additionally, because the maximum height H 1  of the near sipe blade  121  is smaller than the maximum height H 2  of the original shape blade  122 , the near sipe blade  121  can be reliably made more rigid than the original shape blade  122 . In addition, because the maximum height H 1  of the near sipe blade  121  is smaller than the maximum height H 2  of the original shape blade  122 , during detachment of the sectors  101  from the pneumatic tire  1 , the near sipe blade  121  can be pulled out of the sipe  20  earlier. This enables a reduction in the time for which the reaction force from the rubber member forming the sipes  20  acts on the near sipe blade  121 . Consequently, failure in the near sipe blade  121  such as bending of the near sipe blade  121  can be reliably suppressed, which failure is caused by the force acting on the near sipe blade  121  during detachment of the sectors  101  from the pneumatic tire  1 . As a result, the durability of the sipe blades  120  can be reliably improved. 
     Additionally, because the ratio of the maximum height H 1  of the near sipe blade  121  to the maximum height H 2  of the original shape blade  122  is in the range of 0.3≤(H 1 /H 2 )≤0.8, the sipes  20  can be formed that can reliably ensure performance on ice and snow and wet performance, and the durability of the sipe blades  120  can be reliably improved. Specifically, in a case where the ratio of the maximum height H 1  of the near sipe blade  121  to the maximum height H 2  of the original shape blade  122  is (H 1 /H 2 )&lt;0.3, the maximum height H 1  of the near sipe blade  121  is excessively small, and this may lead to an excessively small depth of the sipe  20  formed by the near sipe blade  121 . The sipes  20  contribute to ensuring performance on ice and snow and wet performance, but an excessively small depth of the sipe  20  may cause difficulty in ensuring performance on ice and snow and wet performance. Additionally, an excessively small depth of the sipe  20  formed by the near sipe blade  121  causes the sipe  20  to be worn earlier than the other sipes  20 , and this may degrade the appearance. Additionally, in a case where the ratio of the maximum height H 1  of the near sipe blade  121  to the maximum height H 2  of the original shape blade  122  is (H 1 /H 2 )&gt;0.8, the maximum height H 1  of the near sipe blade  121  is excessively large, and this may cause difficulty in making the near sipe blade  121  more rigid than the original shape blade  122 . Additionally, an excessively large maximum height H 1  of the near sipe blade  121  may cause difficulty in pulling the near sipe blade  121  early from the sipe  20  during detachment of the sectors  101  from the pneumatic tire  1 , and this may in turn cause difficulty in shortening the time for which the reaction force from the rubber member forming the sipe  20  acts on the near sipe blade  121 . 
     In contrast, in a case where the ratio of the maximum height H 1  of the near sipe blade  121  to the maximum height H 2  of the original shape blade  122  is in the range of 0.3≤(H 1 /H 2 )≤0.8, the depth of the sipe  20  formed by the near sipe blade  121  can be ensured. Thus, performance on ice and snow and wet performance can be reliably ensured, and at the time of wear of the tread portion  2 , degradation of the appearance can be suppressed. Furthermore, the near sipe blade  121  can be reliably made more rigid than the original shape blade  122 , and the time for which the reaction force from the rubber member forming the sipe  20  acts on the near sipe blade  121  can be shortened during the detachment of the sectors  101  from the pneumatic tire  1 , allowing failure in the near sipe blade  121  to be reliably suppressed. As a result, the sipes  20  can be formed that can reliably ensure performance on ice and snow and wet performance, and the durability of the sipe blades  120  can be reliably improved. 
     In addition, because the relationship between the sipe volume V and the maximum height H 1  is V∂H 1  in the near sipe blade  121 , the near sipe blade  121  can be reliably made more rigid. In other words, because the near sipe blade  121  has a proportional relationship between the sipe volume V and the maximum height H 1 , the maximum height H 1  of the near sipe blade  121  decreases consistently with the length L and the width W. Thus, the near sipe blade  121  can be reliably made more rigid than the original shape blade  122 , and bending of the near sipe blade  121  can be reliably suppressed. As a result, the durability of the sipe blades  120  can be reliably improved. 
     Modified Examples 
     Note that in the embodiment described above, the near sipe blade  121  and the original shape blade  122  are formed with identical shapes except for the maximum height, but may differ from each other in shapes other than the maximum height.  FIG. 10  is a modified example of the tire molding die  100  according to an embodiment, and is a schematic plan view of the near sipe blade  121 .  FIG. 11  is a modified example of the tire molding die  100  according to an embodiment, and is a schematic plan view of the original shape blade  122 . The near sipe blade  121  and the original shape blade  122  may be configured such that the number A 1  of bend points  121   a  of the near sipe blade  121  differs from the number A 2  of bend points  122   a  of the original shape blade  122 . In this case, the relationship between the number A 1  of bend points  121   a  of the near sipe blade  121  and the number A 2  of the bend points  122   a  of the original shape blade  122  is preferably A 2 &lt;A 1 . 
     The number A 1  of the bend points  121   a  of the near sipe blade  121  is preferably greater than the number A 2  of the bend points  122   a  of the original shape blade  122 , for example, as illustrated in  FIGS. 10 and 11 , the number A 1  of the bend points  121   a  of the near sipe blade  121  is three, and the number A 2  of the bend points  122   a  of the original shape blade  122  is one, and the like. By making the number A 1  of the bend points  121   a  of the near sipe blade  121  greater than the number A 2  of the bend points  122   a  of the original shape blade  122 , the near sipe blade  121  can be reliably made more rigid than the original shape blade  122 . Accordingly, failure in the near sipe blade  121  such as bending of the near sipe blade  121  can be reliably suppressed. As a result, the durability of the sipe blades  120  can be reliably improved. 
     Note that the number A 1  of the bend points  121   a  of the near sipe blade  121  and the number A 2  of the bend points  122   a  of the original shape blade  122  are preferably each in the range of 1 or more and 10 or less. 
     Additionally, in the embodiment described above, the plurality of sipe blades  120  included in the tire molding die  100  are all made of an identical material, but the material may vary between sipe blades  120  as necessary. The near sipe blade  121  and the original shape blade  122  may differ from each other in material such that, for example, the relationship between the material strength S 1  of the near sipe blade  121  and the material strength S 2  of the original shape blade  122  is S 2 &lt;S 1 . In this case, the material strength S 1  of the near sipe blade  121  and the material strength S 2  of the original shape blade  122  include, for example, the tensile strength and hardness of the material forming the near sipe blade  121  and the original shape blade  122 . Thus, in a case where, for example, tensile strength is used as the material strength compared between the near sipe blade  121  and the original shape blade  122 , the tensile strength of the material forming the near sipe blade  121  is preferably greater than the tensile strength of the material forming the original shape blade  122 . 
     In this way, the relationship between the material strength S 1  of the near sipe blade  121  and the material strength S 2  of the original shape blade  122  is S 2 &lt;S 1 , thus allowing the near sipe blade  121  to be reliably made more rigid than the original shape blade  122 . Accordingly, failure in the near sipe blade  121  such as bending of the near sipe blade  121  can be reliably suppressed. As a result, the durability of the sipe blades  120  can be reliably improved. 
     Additionally, the near sipe blade  121  and the original shape blade  122  preferably have a relationship between the surface roughness R 1  of the near sipe blade  121  and the surface roughness R 2  of the original shape blade  122  such that R 2 &gt;R 1 . In this case, as the surface roughness R 1  of the near sipe blade  121  and the surface roughness R 2  of the original shape blade  122 , so-called arithmetic mean roughness Ra is used, for example. Because the surface roughness R 1  of the near sipe blade  121  is smaller than the surface roughness R 2  of the original shape blade  122 , frictional resistance offered in response to pullout of the near sipe blade  121  from the sipe  20  can be made smaller than the frictional resistance offered in response to pullout of the original shape blade  122  from the sipe  20 . Thus, in a case where the sectors  101  of the tire molding die  100  are detached from the pneumatic tire  1  after vulcanization molding, the near sipe blade  121  can be easily pulled out from the sipe  20 , and even in a case where the reaction force from the rubber member forming the sipe  20  acts on the near sipe blade  121 , failure in the near sipe blade  121  such as bending of the near sipe blade  121  can be reliably suppressed. As a result, the durability of the sipe blades  120  can be reliably improved. 
     Additionally, the sipe  20  may be a closed sipe that is at both end portions terminated within the land portion  15  in the length direction of the sipe  20 , or an open sipe that at both end portions opens into the groove  10  in the length direction of the sipe  20 , or a semi-closed sipe that is at one end portion terminated within the land portion  15  and at the other end portion opens into the groove  10  in the length direction of the sipe  20 . Additionally, the pin holes  30  need not be formed in the tread portion  2  of the pneumatic tire  1 , that is, the pin hole forming pins  117  need not be provided on the tire molding die  100 . Additionally, the tread pattern of the pneumatic tire  1  obtained by vulcanization molding using the tire molding die  100  is not limited to the tread pattern illustrated in the embodiment. 
     EXAMPLES 
       FIG. 12  is a table showing results of performance evaluation tests of tire molding dies. In relation to the tire molding die  100  described above, the performance evaluation tests will be described that were conducted on a tire molding die of Conventional Example and the tire molding die  100  according to an embodiment of the present technology. The performance evaluation tests were conducted on the durability of the tire molding die. 
     The performance evaluation tests were conducted by evaluating the durability of the tire molding die when the pneumatic tire  1  having a tire nominal size of 205/55R16 94T, defined by JATMA, was vulcanization molded using the tire molding die. The method for evaluating the durability of the tire molding die includes, after vulcanization molding of the pneumatic tire  1 , checking the near sipe blades  121 , which are likely to be bent, for bending, repairing the near sipe blades  121  bent by 5° or more, and measuring the number of the near sipe blades  121  repaired. Furthermore, after vulcanization molding was performed 5000 times, the total number of the near sipe blades  121  repaired was calculated, and the reciprocals of the totals calculated were expressed as index values with the Conventional Example being assigned the value of 100. Larger values indicate a smaller number of the near sipe blade  121  repaired and superior mold durability. 
     The performance evaluation tests were conducted on nine types of tire molding dies including a Conventional Example as an example of a known tire molding die and Examples 1 to 8 of the tire molding die  100  according to an embodiment of the present technology. Among the tire molding dies, Conventional Example includes the near sipe blade  121  having rigidity comparable to the rigidity of the original shape blade  122 . 
     In contrast, in all of Examples 1 to 8, corresponding to examples of the tire molding die  100  according to the present technology, the near sipe blade  121  is more rigid than the original shape blade  122 . Furthermore, the tire molding dies  100  according to Examples 1 to 8 differ in the maximum height H 1  of the near sipe blade  121 , the ratio (H 1 /H 2 ) of the maximum height H 1  of the near sipe blade  121  to the maximum height H 2  of the original shape blade  122 , whether the sipe volume V and the maximum height H 1  of the near sipe blade  121  are in a proportional relationship, the relative relationship between the number A 1  of bend points  121   a  of the near sipe blade  121  and the number A 2  of bend points  122   a  of the original shape blade  122 , the relative relationship between the material strength S 1  of the near sipe blade  121  and the material strength S 2  of the original shape blade  122 , and the relative relationship between the surface roughness R 1  of the near sipe blade  121  and the surface roughness R 2  of the original shape blade  122 . 
     Note that the relative relationship between the material strength S 1  of the near sipe blade  121  and the material strength S 2  of the original shape blade  122  in the performance evaluation tests corresponds to the relative relationship between the tensile strength of the member forming the near sipe blade  121  and the tensile strength of the member forming the original shape blade  122 . 
     The results of the performance evaluation tests using these tire molding dies  100  indicate that, as shown in  FIG. 12 , the tire molding dies  100  according to Examples 1 to 8 can suppress possible bending of the near sipe blade  121  and improve the durability of the near sipe blade  121  compared to Conventional Example. In other words, the tire molding dies  100  according to Examples 1 to 8 can improve the durability of the sipe blades  120 .