JP5797510B2 - Tire, tire manufacturing method and tire molding die blade - Google Patents

Description

  The present invention relates to a tire, a tire manufacturing method, and a blade of a tire molding die used in the manufacturing method.

  In a tire such as a pneumatic tire, an unvulcanized tire is accommodated in a tire molding die having a mold surface capable of transferring a tread pattern of a tread portion of the tire, and vulcanized using the tire molding die. Manufactured by molding. When manufacturing a tire having a narrow groove called sipe on the tread portion of the tire tread, a plate-like member having a thickness corresponding to the groove width of the narrow groove corresponds to the depth of the narrow groove. The tire molding die is fixed to the tire molding die so as to protrude from the mold surface of the tread surface portion of the tire molding die. This plate-like member is called a blade.

  A vent hole is formed in the mold surface of the tire molding die so as to provide a flow path for air remaining between the tire molding die and the unvulcanized rubber during vulcanization molding of the tire. Yes. Further, a cross vent as a flow path for escaping air is formed through the blade in the plate thickness direction on the blade attached and fixed to the tire molding die. During vulcanization molding, rubber flows into the cross vent of the blade, and the rubber in contact with both sides of the blade is connected through the cross vent. When the tire is removed from the tire molding die after vulcanization molding, the rubber connected by the blade cross vent is cut by the force to remove the tire. This rubber cutting usually occurs in the cross vent of the blade.

  However, depending on the blade, the rubber that was connected by the cross vent does not cut in the cross vent, but occurs in the part that touches the blade and becomes the wall surface of the sipe of the tire. There was a case. The dropout of the sipe wall surface was a manufacturing defect called tread chipping. The tread chipping not only deteriorates the tire appearance, but also the tread rubber cracks from the portion where the tread chipping occurs, which adversely affects the tire life.

  In order to prevent tread chipping, the position of the cross vent on the blade is formed at a deeper position in the depth direction of the sipe formed by this blade, so that the rigidity of the wall surface by the rubber in contact with the blade near the cross vent There was a measure to improve. There was also a measure to reduce the diameter of the clovent so that it was easily cut in the cross vent. However, all of these measures reduce the function of the cross vent that escapes the air remaining between the unvulcanized tire (raw tire) and the tire molding die. In some cases, air remained between the tire and the tire tread.

  Regarding the cross vent of the blade, there is a tire mold blade in which the cross-sectional shape of the cross vent is changed from a conventional round shape to a sharp shape at the lower end (Patent Document 1). Further, regarding the tire molding die, a convex portion that forms a groove in the tire tread is provided with a through hole, and the opening area of the central portion in the longitudinal direction is smaller than the opening area of the longitudinal end portion of the through hole, and In some cases, the through hole is inclined with respect to the side wall of the convex portion (Patent Document 2). In addition, regarding the tire molding die, a through hole is provided in a convex portion that forms a groove in the tire tread, and the side wall of the other convex portion is larger than the opening area that opens in the side wall of the one convex portion. In some cases, the opening area of the opening is small and the penetration height is inclined with respect to the side wall of the convex portion (Patent Document 3).

  However, since the cross-sectional shape of the blade described in Patent Document 1 is not circular, a through hole cannot be formed by drilling with a drill, and it takes time to process the through hole. Further, the through holes described in Patent Document 2 and Patent Document 3 are through holes formed in a convex portion provided on a mold surface of a tire molding die in order to form a groove wider than a sipe in a tire. It is difficult to apply this through hole to a narrow blade as it is because the processing is difficult.

Japanese Patent Laid-Open No. 10-128755 JP 2010-253694 A JP 2010-280168 A

  The present invention advantageously solves the above-described problems in the prior art, and is improved in the tread surface of the tire tread by improving the through-hole of the blade that is attached to the tire molding die to form the sipe of the tire. Without causing bear defects. An object of the present invention is to provide a tire that prevents tread chipping of a tire that occurs when the tire is removed from a tire molding die, a tire manufacturing method, and a blade used in the tire manufacturing method.

  The tire of the present invention includes a narrow groove formed by a blade of a tire molding die on the tread surface of the tread portion, and a cross vent mark of the blade is formed on a groove wall that defines the narrow groove and faces each other. The straight line connecting the cross vent trace of the groove wall and the cross vent trace immediately adjacent to the opposing groove wall is the longitudinal direction of the narrow groove with respect to the perpendicular direction of the groove wall surface in plan view of the tread portion. It is characterized by being inclined.

  In the tire of the present invention, the angle formed by the straight line with respect to the direction perpendicular to the groove wall surface is preferably 5 degrees or more and less than 90 degrees.

  The blade of the tire molding die of the present invention is attached to the tread surface portion of the tire molding die, has a plate thickness corresponding to the groove width of the narrow groove of the tire, and the length in the longitudinal direction of the narrow groove. A blade having a cross vent penetrating one surface and the other surface defining the plate thickness, the penetrating direction of the cross vent in plan view of the blade Inclined in the plate length direction with respect to the plate thickness direction.

  In the blade of the mold for molding a tire according to the present invention, it is preferable that the angle formed by the penetrating direction of the cross vent with respect to the thickness direction is not less than 5 degrees and less than 90 degrees.

  The tire manufacturing method of the present invention includes a step of vulcanizing and molding an unvulcanized tire using the tire molding die provided with the tire molding die blade of the present invention.

  According to the present invention, the cross vent formed on the blade attached to the tire molding die is formed so as to be inclined with respect to the plate thickness direction of the blade. When removing from the rubber, the rubber is easily cut at the cross vent. Therefore, it can be prevented that the wall surface of the sipe falls off and the tread chipping occurs.

It is an orthographic view of one embodiment of the blade of the present invention. FIG. 2 is a partial schematic view of a tire molding die to which the blade of FIG. 1 is attached. It is explanatory drawing of the tire shape | molded with the metal mold | die for tire shaping | molding of FIG. It is an orthographic view of the blade of a comparative example.

  Hereinafter, embodiments of a tire, a tire manufacturing method, and a tire molding blade according to the present invention will be described in detail with reference to the drawings.

  In the orthographic view shown in FIG. 1, FIG. 1 (a) is a plan view of a blade 10 of a tire molding die according to an embodiment of the present invention, FIG. 1 (b) is a front view of the blade 10, and FIG. ) Is a right side view of the blade 10. In FIG. 1, the blade 10 is plate-shaped and has substantially rectangular surfaces 11 and 12 parallel to each other. The thickness of the blade 10 is defined by the shortest distance between the surface 11 and the surface 12, and in the illustrated example, the thickness is t. A cross vent 13, which is a hole penetrating between the surface 11 and the surface 12, is formed in the blade 10. The size of the cross vent 13, that is, the size of the opening of the cross vent 13 that opens to the surface 11 and the surface 12, for example, the opening area, is also constant inside the cross vent 13 from the surface 11 to the surface 12. As understood from the plan view of FIG. 1A, the blade 10 of the present embodiment has a crossing direction of the cross vent 13, that is, an opening of the cross vent 13 on the surface 11 and an opening of the cross vent 13 on the surface 12. The connecting direction is inclined with respect to the thickness direction of the blade 10 (indicated by an arrow A in FIG. 1A), and has an inclination angle θ in the illustrated example.

  FIG. 2 shows a schematic cross-sectional view of the vicinity of the blade 10 of the tire molding die 20 to which the blade 10 of FIG. 1 is attached. The tire molding die 20 has a mold surface 21 corresponding to the tread surface portion of the tire molding die 20. A vent hole (not shown) communicates with the mold surface 21. The blade 10 is used by being attached so as to protrude from the mold surface 21 at a predetermined height h. Normally, the blade 10 is fixed by being cast in a tire molding die 20. The cross vent 13 of the blade 10 is provided in the vicinity of the mold surface 21 in a region exposed from the mold surface 21 of the tire molding die 20. The size of the cross vent 13 (for example, the opening area) and the number of cross vents 13 in a single blade are used to allow air to escape from the mold surface 21 when the tire is vulcanized using the tire molding die 20. It is determined as a sufficient amount.

  The tire according to one embodiment of the present invention is manufactured by vulcanizing and molding an unvulcanized tire using the tire molding die 20 shown in FIG. An example of the vicinity of the tread portion of the tire 30 after vulcanization molding is shown in FIG. 3A is a plan view of the tread portion 31 of the tire 30, and FIG. 3B is a schematic cross-sectional view of the tread portion 31 of the tire 30 in FIG. FIG. 3 and FIG. 3C are schematic cross-sectional views of the tread portion 31 of the tire 30 shown in FIG. The tire 30 has a narrow groove 32 on the surface of the tread portion 31, that is, the tread surface 31a. The narrow groove 32 is a groove formed by the transfer of the blade 10 attached to the tire molding die 20 of FIG. 2, and is called a sipe. The groove width W defined by the distance between the opposed and parallel groove wall surface 32a and groove wall surface 32b of the narrow groove 32 corresponds to the thickness t of the blade 10, and the groove depth d of the narrow groove 32. 2 corresponds to the height h at which the blade 10 protrudes from the mold surface 21 of the tire molding die 20 in FIG.

  A cross vent mark 33 of the blade 10 is formed in the narrow groove 32. The cross vent mark 33 is made of rubber that has flowed into the cross vent 13 of the blade 10 during vulcanization molding. Even if rubber that has flowed into the cross vent 13 from each of the surfaces 11 and 12 of the blade 10 during vulcanization molding is connected in the cross vent 13, the tire 30 is removed from the tire molding die 20 after vulcanization. Sometimes it is cut by the force of pulling out the blade 10 to form a cross vent mark 33. That is, the cross vent mark 33 is a rubber mark in the cross vent 13 cut by the blade 10. However, the cross vent mark 33 is not limited to the one protruding from the groove wall surfaces 32a and 32b of the narrow groove 32 as shown in FIG. The position at which the rubber is cut when the blade 10 is pulled out from the narrow groove 32 may be a position in contact with the groove wall surface 32a or 32b. In this case, the cross vent mark 33 is a cut mark of rubber. Refers to that.

  Since the penetrating direction of the cross vent 13 of the blade 10 is inclined with respect to the plate thickness direction of the blade 10 as described above, the cross vent mark 33 formed on one groove wall surface 32a of the narrow groove 32 and The straight line connecting the cross vent mark 33 formed on the opposite groove wall surface 32b closest to the cross vent mark 33 is inclined with respect to the groove wall surface 32a or the perpendicular to the groove wall surface 32b. This means that the rubber in the cross vent 13 of the blade 10 is arranged to be inclined with respect to the groove width direction at the time of vulcanization molding of the tire.

  Since the rubber in the cross vent 13 of the blade 10 is inclined with respect to the groove width direction of the groove wall surface 32 at the time of vulcanization molding of the tire, when the blade 10 is pulled out after vulcanization molding, The rubber in the vent 13 is concentrated at a position where there is no acute angle with respect to the groove wall surface 32a or the groove wall surface 32b. Therefore, only the rubber in the cross vent 13 or the position where the cross vent 13 is in contact with the groove wall can be easily cut, so that the wall surface of the narrow groove 32 can be prevented from falling off, and thus tread chipping can be prevented. .

  Further, in the tire manufacturing method, when the blade is pulled out of the tire after vulcanization molding by vulcanization molding using the blade 10 of the present embodiment in a tire molding die, the inside of the cross vent 13 or the cross Since only the rubber at the position where the vent 13 is in contact with the groove wall is easily cut, the load applied to the blade 10 when being pulled out is reduced. Therefore, the blade 10 is a blade having excellent durability, and the life of the blade is improved and the replacement frequency of the blade can be reduced.

  The angle θ formed by the penetrating direction of the cross vent 13 with respect to the plate thickness direction in the blade 10, and the angle formed by the straight line connecting the cross vent trace with the perpendicular direction of the groove wall surface 32 a or 32 b of the narrow groove 32 in the tire 30 are , Both are preferably 5 degrees or more and less than 90 degrees. If these angles are less than 5 degrees, the concentration of stress when the tire 20 is pulled out from the tire molding die 20 is not sufficient, and the wall surface of the narrow groove may fall off together with the rubber in the cross vent 13. The larger the angle is, the better the cutting performance of the rubber in the cross vent 13 is, but the workability for forming the cross vent 13 on the blade 10 is lowered. For example, when a hole is drilled as a cross vent 13, the tip of the drill slides on the surface 11 or 12 of the blade 10 as the angle increases, so that it is not easy to reliably drill at a predetermined position. A more preferable angle is about 45 °.

  The formation of the cross vent 13 when forming the blade 10 is preferable because the above-described drilling is easy because the drilling is easy. However, the drilling is not limited to this drilling. Can do.

  An embodiment of the tire manufacturing method of the present invention includes a step of vulcanizing and molding an unvulcanized tire using the tire molding die 20 to which the blade 10 is attached. About other processes, it can carry out according to a conventional method.

Example 1
As Example 1, a tire of 195/7015 92S SNK2BZ was manufactured by vulcanization molding of an unvulcanized tire using a tire molding die provided with the blade 10 shown in FIG. An angle θ formed by the penetration direction of the cross vent 13 with the plate thickness direction is 45 degrees. Further, as a comparative example, a tire having the same size as that of Example 1 was manufactured by vulcanizing and molding an unvulcanized tire using a tire molding die provided with the blade 100 shown in FIG. The blade 100 of FIG. 4 is a conventional blade in which the penetrating direction of the cross vent 103 is parallel to the plate thickness direction of the blade 100. Except for the penetrating direction of the cross vent, the blade of the first embodiment shown in FIG. 10 and the material, dimensions, the number and size of cross vents are the same.

  The number of cross vents per tire during vulcanization molding is 840. With respect to the above-mentioned cross vent portions of the tire taken out from the tire molding die after vulcanization molding, the number of portions where tread chipping occurred was examined. The smaller the number of occurrences, the better. As a result, in the tires of the examples, there were no tread chip defects. On the other hand, the tire of the comparative example had 45 locations where defects in tread chipping occurred.

(Example 2, Example 3)
As Example 2 and Example 3, it is different from Example 1 except that the angle θ between the penetration direction of the cross vent 13 of the blade 10 and the plate thickness direction is 30 degrees and 60 degrees, respectively. A tire for 195/7015 92S SNK2BZ was produced in the same manner as in Example 1 by vulcanizing and molding an unvulcanized tire using a tire molding die having the same blades as in Example 1.

  About Example 2 and Example 3, about the said cross vent location of the tire taken out from the tire molding die after vulcanization molding, the number of locations where tread chipping per tire occurred and the cross vent were formed on the blade. Table 1 shows the working workability (drilling time per hole) together with Example 1.

  In Example 2, the workability was as good as in Example 1, but slight tread chipping occurred. However, tread chipping in about three places is within a practically acceptable range. Moreover, in Example 3, processing was difficult and processing time was required. However, the tread chipping prevention effect was as good as in Example 1, and the blade obtained by processing had good characteristics.

10 Blades 11 and 12 Surface 13 Cross vent 20 Tire molding die 21 Mold surface 30 Tire 31 Tread portion 32 Fine grooves 32a and 32b Groove wall surface 33 Cross vent mark

Claims (5)

A tire having a narrow groove formed by a blade of a tire molding die on a tread surface and having a cross vent mark of the blade on a groove wall that defines the narrow groove and faces each other. ,
The straight line connecting the cross vent trace on the groove wall and the cross vent trace nearest to the opposite groove wall is inclined in the longitudinal direction of the narrow groove with respect to the perpendicular direction of the groove wall surface in plan view of the tread portion. A characteristic tire.   The tire according to claim 1, wherein an angle formed by the straight line with respect to a direction perpendicular to the groove wall surface is 5 degrees or more and less than 90 degrees. The plate is attached to the tread portion of the mold for molding the tire, has a plate thickness corresponding to the groove width of the narrow groove of the tire , and has a plate length corresponding to the length in the longitudinal direction of the narrow groove, A blade having a cross vent penetrating one surface and the other surface defining the plate thickness,
The blade of the mold for molding a tire is characterized in that a penetrating direction of the cross vent is inclined in the plate length direction with respect to the plate thickness direction in a plan view of the blade.   The tire molding die blade according to claim 3, wherein an angle formed by the cross vent penetrating direction with respect to the plate thickness direction is 5 degrees or more and less than 90 degrees.   A method for producing a tire, comprising a step of vulcanizing and molding an unvulcanized tire using a tire molding die to which the blade according to claim 3 or 4 is attached.

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