JP2015217621A - Vulcanization die for spike tire, vulcanization method and spike tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a crack around the spike pin driving hole of a tire after vulcanization by the projection of the design face of a sector mold while suppressing the increase of production cost.SOLUTION: A sector mold 2 has a pin-shaped projection 8 for forming a spike pin fitting hole to the tread part of a spike tire being provided so as to be projected from a design face 2a. In the projection 8, regarding the projections 8B, 8C provided at the nearest position at the edge in the circumferential direction of the design face 2a, the projecting direction directed from the design face 2a to the tip is tilted from the normal direction of the design face 2a in the base end to the outer direction.

Description

  The present invention relates to a vulcanization mold for a spike tire, a vulcanization method, and a spike tire used for vulcanization in a manufacturing process of a spike tire in which spike pins are driven into a tread portion of a tire.

  As a tire for snow and snow, a spike tire in which a spike pin is embedded in a land portion of a tread portion is known. Spike pins generally have a shape with a tip at the tip of a substantially cylindrical body, a flange with a retaining flange at the base end, the base end side is embedded in the tire, and the tip end side protrudes from the tire to the road surface. It is attached to the tire so that it contacts.

  The spike pin is attached to the tire by forming a spike pin driving hole in advance on the surface of the land portion of the tread portion of the spike tire and driving the spike pin into the spike pin driving hole. The spike pin driving hole of the spike tire is formed with an enlarged portion corresponding to the flange of the spike pin in the vicinity of the bottom thereof, and the flange of the spike pin is accommodated in the enlarged portion.

  The spike pin driving hole is formed by providing pin-shaped protrusions on the design surface of the vulcanization mold, i.e., the surface facing the tread portion of the raw tire in the vulcanization mold. This is because the tread portion comes into contact with the design surface of the vulcanization mold and each protrusion is pushed into the tread portion of the tire. Furthermore, each protrusion may be formed with a bulging portion at the tip in order to form the above-mentioned enlarged diameter portion of the spike pin driving hole.

  Vulcanization molds widely used for vulcanization of tires are such that a mold part having a design surface has an annular shape along the tread portion of the tire and a plurality of annular shapes along the circumference of the circumferential ring. It consists of a so-called sector mold divided into pieces. The design surface of the sector mold has a curved surface that has an arc shape in the circumferential direction in a cross section including the circumference of the annular ring in the circumferential direction. The sector mold can be advanced and retracted in the radial direction of the circumferential ring. During vulcanization, each sector mold is advanced toward the radial center to form an annular mold part, and after vulcanization or after vulcanization, each sector mold is retracted radially outward. The raw tire before vulcanization is attached to the vulcanization mold, and the tire after vulcanization is removed from the vulcanization mold.

  In the spike tire vulcanization mold, the direction in which the protrusion provided on the design surface protrudes from the design surface (hereinafter, also referred to as “projection direction”) is conventionally the normal line of the design surface at the base end of the protrusion. The direction was the same. When the conventional sector mold having such a protruding direction is retracted radially outward of the circumferential ring after vulcanization, the protrusion provided at the position closest to the circumferential end of the design surface among the protrusions However, the stress which causes a crack was produced with respect to the periphery of the spike pin driving hole in the tread portion of the tire.

  The reason is that each sector mold retracts in the normal direction of the center position in the circumferential direction, but retracts in a direction parallel to the normal direction of the center position with respect to all protrusions in the sector mold. This is because the protrusion closer to the edge of the sector mold in the circumferential direction is different from the retracting direction of the sector mold with respect to the normal direction of the protrusion. Further, since the bulging portion may be formed at the tip of the protrusion, a large stress is applied to the tread portion of the tire when the bulging portion is separated from the tread portion of the tire. If this stress is large, cracks may occur around the spike pin driving hole of the tire. This crack can cause the spike pin driven into the spike tire to fall off.

  Regarding the vulcanization mold for spike tires, it is possible to prevent cracks from occurring around the spike pin insertion holes due to protrusions on the design surface of the sector mold when the vulcanized tire is removed from the vulcanization mold. As for the protrusion provided on the side, there is one in which the size of the protruding portion of the protrusion is made smaller than that of the central side in the circumferential direction (Patent Document 1).

JP 2012-96471 A

  However, since the vulcanization mold for spike tires described in Patent Document 1 has different bulge portions for each protrusion, it takes time to process the protrusion. Therefore, there is a risk of increasing the manufacturing cost of the vulcanization mold.

  The present invention advantageously solves the above-described problem, and does not take time and effort to process the protrusions, and thus suppresses an increase in manufacturing cost, and the tire after vulcanization by the protrusions on the design surface of the sector mold. It is an object of the present invention to provide a vulcanization mold for a spike tire, a vulcanization method, and a spike tire that can prevent cracks from occurring around the spike pin driving hole.

The spike tire vulcanization mold according to one aspect of the present invention that solves the above problems includes an annular mold portion provided to face the tread portion of the spike tire to be molded,
The mold part is divided into a plurality of pieces along the circumference of the circumferential ring, and comprises a sector mold that can advance and retreat in the radial direction of the circumferential ring.
Each sector mold is provided with a design surface which is a curved surface in contact with the tread portion of the spike tire and has a circular arc shape in a circumferential direction in a cross section including the circumference of the mold portion, and protrudes from the design surface. A pin-shaped protrusion for forming a spike pin mounting hole in the tread portion of
Among the protrusions, the protrusion provided at a position closest to one of the circumferential ends of the design surface and the other of the protrusions is such that the protrusion direction from the design surface toward the tip is the method of the design surface at the base end of the protrusion Inclined outward from the line direction.

  By having the said structure, the protrusion direction of the processus | protrusion provided in the position nearest to each of the circumferential direction edge of a design surface and each other approximates or becomes the same direction as the advancing / retreating direction of a sector mold. Therefore, when the sector mold is retracted after vulcanization and the tire is removed, the protrusion embedded in the tread portion of the tire can be pulled out in the protrusion direction of the protrusion or a direction similar thereto, so that the spike pin insertion hole of the tire can be removed. It is possible to suppress the occurrence of cracks in the surroundings.

Moreover, the vulcanization mold for spike tires of the present invention has a more specific configuration,
Among the protrusions, the protrusion provided at the position closest to one of the circumferential ends of the design surface and the other of the protrusions is larger than the protrusion provided at the position closest to the center position in the circumferential direction of the design surface. A structure having a large angle between the protruding direction of the projection and the normal direction of the design surface at the base end of the protrusion,
Of the projections, the projections provided at positions closest to one of the circumferential ends of the design surface and the other are projections other than the projections provided at positions closest to one of the circumferential ends and the other, respectively. Compared with the configuration in which the angle formed by the protrusion direction of the protrusion and the normal direction of the design surface at the base end of the protrusion is large,
The protrusion is configured such that the protrusion formed between the protrusion closest to the circumferential center of the design surface and the protrusion close to the circumferential end has a larger angle between the protrusion direction of the protrusion and the normal direction of the design surface at the base end of the protrusion. ,
The projections are divided into four equal parts in the circumferential direction of the design surface, and when one and the other circumferential end side regions are circumferential end portions, and two regions on the circumferential center side are circumferential central portions, the circumferential end The average value of the angle formed by the projection direction of the projection at the projection and the normal direction of the design surface at the base end of the projection is the projection direction of the projection at the central portion in the circumferential direction and the normal of the design surface at the base end of the projection A configuration larger than the average value of the angle with the direction,
The projections are divided into four equal parts in the circumferential direction of the design surface, and when one and the other circumferential end side regions are circumferential end portions, and two regions on the circumferential center side are circumferential central portions, the circumferential end The angle formed by the protrusion direction of the protrusion and the normal direction of the design surface at the base end of the protrusion is inclined outward from the normal direction of the design surface at the base end of the protrusion and only in the circumferential direction. In the end portion, the protrusion provided at the position closest to the circumferential end of the design surface has a protrusion direction of the protrusion and the base end of the protrusion compared to the protrusion provided at a position other than the position closest to the circumferential end. A structure having a large angle with the normal direction of the design surface in the above, or the protrusion is equally divided into four in the circumferential direction of the design surface, and the region on one and the other circumferential end side is a circumferential end, and the central side in the circumferential direction When the two regions are the central part in the circumferential direction, the protrusion direction of the protrusion only at the circumferential end part And the normal direction of the design surface at the base end of the projection is inclined outward from the normal direction of the design surface at the base end of the projection, and the projection at the circumferential end is a design A configuration in which a protrusion closer to the circumferential end from a position closest to the circumferential center of the surface has a larger angle between the protruding direction of the protrusion and the normal direction of the design surface at the base end of the protrusion,
It can be.

  The spike tire vulcanizing method according to another aspect of the present invention is a method for removing a spike tire from the mold part by moving the mold part after vulcanization using the above-mentioned spike tire vulcanization mold. The protrusion has a bulging portion at the tip, and when the bulging portion of the protrusion of the mold portion has moved to a length corresponding to the height of the bulging portion, the movement of the mold is temporarily stopped. It is characterized by that.

  Further, another configuration of the spike tire vulcanizing method of the present invention is that, after vulcanization using the spike tire vulcanization mold, the sector mold is moved to remove the spike tire from the sector mold. The protrusion has a bulging portion at the tip, and the movement speed of the sector mold is changed while the bulging portion of the protrusion of the sector mold moves to a length corresponding to the height of the bulging portion. It is slower than the speed.

Furthermore, a spike tire according to another aspect of the present invention is manufactured using the above-described spike tire vulcanization mold, and includes a tread rubber composed of two or more layers of a cap rubber layer and a base rubber layer. In the spike tire with spike pin driving holes in the land part of
The protrusion has a bulged portion at the tip, and the depth at which the interface between the cap rubber layer and the base rubber layer is located from the surface of the land portion of the tread rubber of the spike tire is determined by the added pressure for the spike tire. When the spike tire is in close contact with the mold, the position of the base of the bulge of the projection of the vulcanization mold for the spike tire is used as a reference position, and the bulge is directed from the reference position toward the design surface. It has a length corresponding to the height of the part and is deep from a shallow position.

  According to the present invention, it is possible to prevent the occurrence of cracks around the spike pin driving hole of the tire after vulcanization while suppressing an increase in manufacturing cost without taking time and effort to process the protruding portion of the protrusion. Can be prevented.

It is a schematic diagram of the vulcanization mold for tires of one embodiment of the present invention. It is sectional drawing of the vulcanization mold for tires of one Embodiment of this invention. It is explanatory drawing of the sector mold of the vulcanization metal mold | die for tires. It is a schematic diagram explaining operation | movement of the sector mold of FIG. It is explanatory drawing of the vulcanization method of one Embodiment of this invention. It is explanatory drawing of the tire of one Embodiment of this invention. It is explanatory drawing of the sector mold of the conventional vulcanization mold for tires. It is a schematic diagram explaining operation | movement of the sector mold of FIG.

  Embodiments of a vulcanization mold for spike tire, a vulcanization method, and a spike tire according to the present invention will be described more specifically with reference to the drawings.

  As shown in the schematic diagram of FIG. 1, the vulcanization mold 1 for spike tire according to the present embodiment is an annular mold provided so as to face a tread portion of a spike tire (not shown) to be vulcanized. The mold part is composed of a plurality of sector molds 2 divided along the circumference of the circumferential ring, in the illustrated example, nine sector molds 2. Further, the spike tire vulcanization mold 1 is provided so as to be connected to the end portion in the width direction of the sector mold 2 as shown in the cross-sectional views of FIGS. Molds 3 and 4 are provided. The outer shape of the spike tire is molded by a sector mold 2 for molding the tread portion of the tire and side molds 3 and 4 for molding the side portion.

  The upper surface of the side mold 3 is fixed to the top plate 5, and the radially outer side of the side mold 4 is fixed to the plate ring 6. A container ring 7 is provided outside the sector mold 2 in the radial direction. The outer surface of the sector mold 2 and the inner surface of the container ring 7 have inclined surfaces that are inclined to each other. The sector mold 2 and the container ring 7 can slide on these inclined surfaces.

  When the container ring 7 is moved in the direction toward the side mold 3, the inclined surface of the container ring 7 and the inclined surface of the sector mold 2 slide, and each sector mold 2 is in the radial direction of the annular mold portion. Move outward. Conversely, when the container ring 7 is moved to the side mold 4 side, the inclined surface of the container ring 7 and the inclined surface of the sector mold 2 slide, and the sector mold 2 moves toward the center in the radial direction. With such a structure, the sector mold 2 can advance and retreat in the radial direction of the circumferential ring.

  At the time of vulcanization, each sector mold 2 is moved forward toward the center in the radial direction, and an annular mold portion is formed adjacent to each other. After vulcanization, the sector mold 2 is moved back outward in the radial direction, It can be removed.

  The inner surface of the sector mold 2 is a design surface 2a that contacts the tread portion of the spike tire and forms the shape of the tread portion. The design surface 2a is a curved surface having an arc shape in the circumferential direction in a cross section including the circumference of the annular mold portion. On the design surface 2a, a protrusion 8 projects to form a spike pin driving hole for a spike tire. Depending on the size of the sector mold 2, one sector mold is provided with about 100 to 130 protrusions. FIG. 1 representatively shows three protrusions 8, and FIG. 2 representatively shows one protrusion 8.

  FIG. 3A shows a schematic diagram of the protrusion 8A provided at the position closest to the circumferential center position of the design surface 2a of the sector mold 2 and the protrusions 8B and 8C provided at the position closest to the circumferential end. As shown in the enlarged view of the protrusion 8C in FIG. 3B, each of the protrusions 8A, 8B, and 8C has a substantially pin shape, extends from the base end connected to the design surface 2a, and expands a spike pin driving hole at the tip. It has a bulging portion 8a for forming a diameter portion. In addition, each protrusion 8A, 8B, 8C can also be set as the structure which does not have the bulging part 8a.

  The protrusions 8B and 8C provided at positions closest to the circumferential end of the design surface 2a of the sector mold 2 are the directions protruding from the design surface 2a of the sector mold 2, that is, the direction in which the protrusions 8 extend from the base end toward the tip. However, it inclines outward from the normal line direction of the design surface 2a at the base ends of the protrusions 8B and 8C. This is clearly shown in the enlarged view of FIG. 3B, where the protrusion 8C has an angle (hereinafter referred to as “the direction between the protrusion direction of the protrusion 8C and the normal direction of the design surface at the base end of the protrusion 8C”). It is referred to as “inclination angle”.) Θ has a predetermined angle. Similarly, the protrusion 8B has a predetermined inclination angle, but the direction of inclination is opposite to the protrusion 8C. On the other hand, the protrusion 8A provided at the position closest to the center position in the circumferential direction of the design surface 2a of the sector mold 2 is such that the direction protruding from the design surface 2a of the sector mold 2 is the design surface 2a at the base end of the protrusion 8A. It is almost the same as the normal direction. That is, the inclination angle θ is approximately 0 degrees.

  The spike tire vulcanization mold 1 of the present embodiment is provided with the above-described configuration at the protrusion direction of the protrusions 8B and 8C provided at the position closest to the circumferential end of the design surface 2a and the circumferential center position. The protrusion direction of the protrusion 8A provided at the closest position is parallel or approximate to parallel. Therefore, when the sector mold 2 is retracted in the direction of the arrow after vulcanization as shown in FIG. 4 and the spike tire (hereinafter also simply referred to as “tire”) 10 is removed from the sector mold 2, The protrusion directions of the protrusions 8B and 8C can be made close to or the same. Therefore, since the protrusions 8B and 8C can be pulled out of the tire 10 in the same or approximate direction as the protrusion direction, the protrusions 8B and 8C, particularly when the bulging portion 8a is separated from the tire 10, are spike pins of the tire 10. Since the stress applied to the periphery of the driving hole is small and the elastic deformation amount of the rubber is small, the occurrence of cracks can be suppressed.

  Further, since the protrusions 8B and 8C have the bulging portion 8a having the same size as the protrusion 8A, the spike pin holding hole of the tire 10 formed by the protrusions 8B and 8C has a reduced holding force of the spike pin. I don't have to.

  On the other hand, as shown in the schematic diagram of the main part of the conventional vulcanization mold 101 in FIG. 7A, the projection 108B provided at the position closest to the circumferential end of the design surface 102a of the sector mold 102 in the past. , 108C, like the projection 108A provided at the position closest to the center position in the circumferential direction, the direction protruding from the design surface 102a of the sector mold 102 is the normal direction of the design surface 2a at the base end of the projection 108A Is almost the same. That is, as shown in an enlarged view of the protrusion 108C in FIG. 7B, the inclination angle θ of the protrusion 108C is approximately 0 degrees. The inclination angle of the protrusion 108B is also approximately 0 degrees. Therefore, as shown in FIG. 8, when the sector mold 102 is retracted in the arrow direction after vulcanization and the tire is removed from the sector mold 102, the difference between the retracting direction of the sector mold 102 and the protruding direction of the protrusions 108B and 108C is large. . Therefore, when the bulging portion 108a of the protrusions 108B and 108C is separated from the tire 10, a large stress is applied to the periphery of the spike pin driving hole of the tire 10 and the amount of elastic deformation of the rubber is large, so that a crack may occur. By comparing FIG. 5 with FIG. 3, the configuration and effects of the spike tire vulcanization mold 1 of this embodiment can be easily understood.

  In the spike tire vulcanization mold 1 of the present embodiment, the inclination angle θ of the protrusions 8B and 8C provided at the position closest to the circumferential end of the design surface 2a of the sector mold 2 is the number of divisions of the sector mold 2 or Depending on the size of the spiked tire 10 to be vulcanized, as an example, the design surface 2a of the nine-segment sector mold 2 shown in FIGS. And has an angle that is parallel to the protruding direction of the protrusion 8A provided at the position closest to the center position in the circumferential direction.

  The spike tire vulcanization mold according to the present invention has at least a configuration in which the protruding direction of the protrusion provided at the position closest to the circumferential end of the design surface of the sector mold is inclined outward from the normal direction of the design surface. It has. The embodiment of the vulcanization mold for spike tires having such a configuration can be derived from several derivations as described below.

  As described above, the vulcanization mold for spike tire according to the first embodiment is closest to the protrusions 8B and 8C provided at the position closest to the circumferential end of the design surface 2a and the circumferential center position of the design surface. When the projection 8A provided at the position is compared, the projections 8B and 8C have a larger inclination angle than the projection 8A. In the first embodiment, the plurality of protrusions provided on the design surface 2a of the sector mold 2 are provided at positions closest to the protrusions 8B and 8C provided at positions closest to the circumferential end and the center position in the circumferential direction. It is characterized by paying attention to the protrusion 8A. The inclination angle of the protrusion 8A provided at the position closest to the circumferential center position may be approximately 0 degrees. In the first embodiment, the protrusions other than the protrusions 8B and 8C provided at the position closest to the circumferential end and the protrusion 8A provided at the position closest to the circumferential center position are not particularly limited. The inclination angle can be an intermediate inclination angle between the inclination angles of 8B and 8C and the inclination angle of the protrusion 8A.

  In the vulcanization mold for spike tire according to the second embodiment, the protrusions 8B and 8C located closest to the circumferential end of the design surface 2a are compared to the protrusions provided on the design surface 2a other than the protrusions 8B and 8C. The inclination angle is large. In the second embodiment, with respect to the plurality of protrusions provided on the design surface 2a of the spike tire vulcanizing mold 1, the protrusions 8B and 8C provided at positions closest to the circumferential end and the other protrusions are provided. Characterized by attention. If the inclination angle of the protrusions other than the protrusion provided at the position closest to the circumferential end is 0 degree or more and smaller than the inclination angle of the protrusions 8B and 8C provided at the position closest to the circumferential end, the inclination is inclined. Any angle.

  In the vulcanization mold for spike tire according to the third embodiment, the inclination angle θ of the protrusion is larger from the position closest to the circumferential center position of the design surface 2a to the protrusion closer to the circumferential end. In the third embodiment, the plurality of protrusions provided on the design surface 2a of the spike tire vulcanizing mold 1 are characterized by paying attention to the protrusion from the position closest to the circumferential center position to the circumferential end. . In the third embodiment, the inclination angle θ increases sequentially or stepwise from the position closest to the circumferential center position of the design surface 2a to the circumferential end.

  The occurrence of cracks in the spike tire can be caused by a protrusion provided at a position near the circumferential end of the design surface of the sector mold. Therefore, the region of the design surface 2a of the sector mold 2 in FIG. Thus, when the region on the circumferential center side is the circumferential central portion A1 and the circumferential central portion A2, and the region on the circumferential end side is the circumferential end B and the circumferential end C, the circumferential end B and Only the protrusions provided on C can be inclined outward. With this configuration, the trouble of adjusting the angle of each protrusion provided on the design surface 2a can be reduced.

  Implementation of a vulcanization mold for spike tires having a configuration in which only the protrusions provided on the circumferential ends B and C of the design surface 2a are inclined outward from the normal direction of the design surface 2a. The form can be derived in several ways as described below.

  In the vulcanization mold for spike tire according to the fourth embodiment, the average value of the inclination angle of the protrusions at the circumferential ends B and C is larger than the average value of the inclination angle of the protrusions at the circumferential center parts A1 and A2. Is. In the fourth embodiment, assuming that the protrusions 8B and 8C at the circumferential end portions B and C have a predetermined inclination angle, the inclination angle θ of the protrusions 8A at the circumferential central portions A1 and A2 may be approximately 0 degrees. .

  The spike tire vulcanization mold according to the fifth embodiment includes projections 8B and 8C provided at positions closest to the circumferential end among the projections provided at the circumferential ends B and C. The inclination angle is larger than the protrusions of the circumferential end portions B and C other than the protrusions 8B and 8C provided at the position closest to the end. In the fifth embodiment, the plurality of protrusions provided at the circumferential ends B and C are characterized by paying attention to the protrusions 8B and 8C provided at positions closest to the circumferential end and the other protrusions. . Protrusions 8B and 8C provided at positions closest to the circumferential end when the inclination angles of the protrusions other than the protrusions 8B and 8C provided at positions closest to the circumferential ends at the circumferential ends B and C are 0 degrees or more. The inclination angle is not limited as long as it is smaller than the inclination angle. Further, the inclination angle θ of the protrusions 8A of the circumferential center portions A1 and A2 may be approximately 0 degrees.

  In the vulcanization mold for spike tire according to the sixth embodiment, the protrusions provided at the circumferential end portions B and C are closer to the circumferential end from the position closest to the circumferential central portion of the design surface 2a. The inclination angle is large. In the sixth embodiment, the plurality of protrusions provided at the circumferential ends B and C are characterized by paying attention to the protrusion from the position closest to the circumferential center to the circumferential end. In the sixth embodiment, the inclination angle increases sequentially or stepwise from the position closest to the circumferential center of the circumferential ends B and C to the circumferential end. Further, the inclination angle θ of the protrusions 8A of the circumferential center portions A1 and A2 may be approximately 0 degrees.

  In any of the first to sixth embodiments described above, the occurrence of cracks can be effectively prevented.

  An embodiment of a vulcanization method using a vulcanization mold for spike tires according to an embodiment of the present invention will be described below.

  In one embodiment, after the vulcanization, when the sector mold 2 is moved radially outward to remove the spike tire 10 from the sector mold 2, as shown in FIG. 5, the protrusion 8 on the design surface 2 a of the sector mold 2. It is preferable that the movement of the mold is temporarily stopped when the bulging portion 8a has moved to a length h corresponding to the height h of the bulging portion. Around the spike pin mounting hole of the tire 10, the region where the crack c is likely to occur is the height h of the bulging portion 8a than the position of the bulging portion 8a of the projection 8 embedded from the surface of the tire 10 during vulcanization. This is the area closer to the surface by the amount of. Therefore, when the bulging portion 8a of the protrusion 8 serving as the starting point of the crack has moved to a length h corresponding to the height h of the bulging portion 8a, the movement of the sector mold 2 is temporarily stopped, thereby It is possible to further suppress the occurrence of cracks due to the protruding portion being pulled out of the tire.

  The vulcanizing method for suppressing the crack c is not limited to the method of temporarily stopping, and as another embodiment, the bulging portion 8a of the protrusion 8 of the sector mold 2 corresponds to the height h of the bulging portion 8a. The movement speed of the sector mold 2 during the movement to the length h to be made is made slower than the subsequent movement speed. Also by this method, generation | occurrence | production of the crack c by the bulging part 8a being pulled out from a tire can be suppressed more.

  Next, a structure of a spike tire suitable for suppressing the generation of crack c around the spike pin mounting hole will be described. As shown in FIG. 6, in the spike tire 10 in which the tread rubber 11 is composed of two or more layers of the cap rubber layer 12 and the base rubber layer 13, the interface I between the cap rubber layer 12 and the base rubber layer 13 is vulcanized. It has a deep structure from a predetermined position in relation to the position of the protrusion at the time. More specifically, the depth d at which the interface I is located from the surface of the land portion of the tread rubber of the spike tire 10 is such that when the spike tire 10 is in close contact with the sector mold 2, the sector mold The position of the base portion of the bulging portion 8a of the projection 8 is defined as a reference position B and is deep from a shallow position with a length h corresponding to the height h of the bulging portion 8a from the reference position B toward the design surface 2a. The structure is in position. If the interface I between the cap rubber layer 12 and the base rubber layer 13 is located in the region where the crack c described with reference to FIG. 5 is likely to occur, cracks are likely to occur from the interface I. Therefore, in order to suppress cracks, the interface I does not exist in a region where cracks are likely to occur. More specifically, the interface I seems to be located deeper from the tire surface than a region where cracks are likely to occur. Use spike tires.

  As mentioned above, although the vulcanization | cure mold for spike tires, the vulcanization method, and the spike tire of this invention were demonstrated based on embodiment, this invention is not limited to the above-mentioned embodiment, and deviates from the meaning of this invention. Many variations are possible within the range that is not.

According to the present invention, a spike tire is vulcanized using a vulcanization mold having a sector mold with a large inclination angle of a protrusion provided at a position closest to a circumferential end of the design surface, and a spike pin driving hole is formed. When the occurrence of surrounding cracks was examined, the ratio of spike pin insertion holes with cracks to all spike pin injection holes was 0%.
On the other hand, the inclination angle of the protrusion provided at the position closest to the circumferential end of the design surface is substantially 0 degree, similar to the inclination angle of the protrusion provided at the position closest to the circumferential center position. Spike tires were vulcanized using a vulcanization mold equipped with a conventional sector mold, and the occurrence of cracks around the spike pin insertion holes was examined. The ratio of pin driving holes was 2 to 10%.

  Thus, according to the present invention, cracks can be generated around the spike pin driving hole by the vulcanization mold for spike tires while suppressing an increase in cost.

DESCRIPTION OF SYMBOLS 1 Vulcanization mold for spike tires, 2 sector molds, 2a design surface, 8 protrusions, 8a bulge part, 10 spike tires 11 tread rubber, 12 cap rubber layer, 13 base rubber layer

Claims (10)

Provided with an annular mold portion provided to face the tread portion of the spike tire to be molded,
The mold part is divided into a plurality of pieces along the circumference of the circumferential ring, and comprises a sector mold that can advance and retreat in the radial direction of the circumferential ring.
Each sector mold is provided with a design surface which is a curved surface in contact with the tread portion of the spike tire and has a circular arc shape in a circumferential direction in a cross section including the circumference of the mold portion, and protrudes from the design surface. A pin-shaped protrusion for forming a spike pin mounting hole in the tread portion of
Among the protrusions, the protrusion provided at a position closest to one of the circumferential ends of the design surface and the other of the protrusions is such that the protrusion direction from the design surface toward the tip is the method of the design surface at the base end of the protrusion A vulcanization mold for spike tires, which is inclined outward from the linear direction.   Among the protrusions, the protrusion provided at the position closest to one of the circumferential ends of the design surface and the other of the protrusions is larger than the protrusion provided at the position closest to the center position in the circumferential direction of the design surface. The spike tire vulcanization mold according to claim 1, wherein an angle formed between the protrusion direction of the protrusion and a normal direction of the design surface at the base end of the protrusion is large.   Of the projections, the projections provided at positions closest to one of the circumferential ends of the design surface and the other are projections other than the projections provided at positions closest to one of the circumferential ends and the other, respectively. 2. The vulcanization mold for spike tire according to claim 1, wherein an angle formed by a protruding direction of the protrusion and a normal direction of the design surface at the base end of the protrusion is large.   The protrusion has a larger angle between the protrusion direction of the protrusion and the normal direction of the design surface at the base end of the protrusion, as the protrusion is closer to the circumferential end from the position closest to the center position in the circumferential direction of the design surface. Item 1. A vulcanization mold for spike tires according to item 1.   The projections are divided into four equal parts in the circumferential direction of the design surface, and when one and the other circumferential end side regions are circumferential end portions, and two regions on the circumferential center side are circumferential central portions, the circumferential end The average value of the angle formed by the projection direction of the projection at the projection and the normal direction of the design surface at the base end of the projection is the projection direction of the projection at the central portion in the circumferential direction and the normal of the design surface at the base end of the projection The vulcanization mold for spike tires according to claim 1, wherein the vulcanization mold is larger than an average value of angles formed with the direction.   The projections are divided into four equal parts in the circumferential direction of the design surface, and when one and the other circumferential end side regions are circumferential end portions, and two regions on the circumferential center side are circumferential central portions, the circumferential end The angle formed by the protrusion direction of the protrusion and the normal direction of the design surface at the base end of the protrusion is inclined outward from the normal direction of the design surface at the base end of the protrusion and only in the circumferential direction. In the end portion, the protrusion provided at the position closest to the circumferential end of the design surface has a protrusion direction of the protrusion and the base end of the protrusion compared to the protrusion provided at a position other than the position closest to the circumferential end. The vulcanization mold for spike tires according to claim 1, wherein the angle formed with the normal direction of the design surface in is large.   The projections are divided into four equal parts in the circumferential direction of the design surface, and when one and the other circumferential end side regions are circumferential end portions, and two regions on the circumferential center side are circumferential central portions, the circumferential end The angle formed by the protrusion direction of the protrusion and the normal direction of the design surface at the base end of the protrusion is inclined outward from the normal direction of the design surface at the base end of the protrusion and only in the circumferential direction. As for the protrusion at the end, the angle between the protrusion direction of the protrusion and the normal direction of the design surface at the base end of the protrusion increases from the position closest to the center in the circumferential direction of the design surface to the edge in the circumferential direction. The vulcanization mold for spike tires according to claim 1.   After vulcanization using the vulcanization mold for spike tire according to claim 1, when removing the spike tire from the sector mold by moving the sector mold, the protrusion has a bulging portion at the tip, and A spike tire vulcanizing method, wherein the movement of the sector mold is temporarily stopped when the bulging portion of the projection of the sector mold has moved to a length corresponding to the height of the bulging portion.   After vulcanization using the vulcanization mold for spike tire according to claim 1, when removing the spike tire from the sector mold by moving the sector mold, the protrusion has a bulging portion at the tip, and Addition of a spike tire characterized in that the movement speed of the sector mold is made slower than the subsequent movement speed while the bulge of the projection of the sector mold moves to a length corresponding to the height of the bulge. Sulfur method. A tread rubber manufactured using the vulcanization mold for spike tire according to claim 1 and comprising two or more layers of a cap rubber layer and a base rubber layer, and a spike pin driving hole is formed in a land portion of the tread rubber. In the spike tires provided,
The protrusion has a bulged portion at the tip, and the depth at which the interface between the cap rubber layer and the base rubber layer is located from the surface of the land portion of the tread rubber of the spike tire is determined by the added pressure for the spike tire. When the spike tire is in close contact with the mold, the position of the base of the bulge of the projection of the vulcanization mold for the spike tire is used as a reference position, and the bulge is directed from the reference position toward the design surface. Spike tire characterized by being deep from a shallow position with a length corresponding to the height of the part.

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