JP2014073639A - Method for manufacturing pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pneumatic tire that does not cause poor appearance and inferior quality of a product tire by sufficiently suppressing the occurrence of rubber biting, and also can provide a product tire of stable quality by sufficiently suppressing the occurrence of air remaining.SOLUTION: A method for manufacturing a pneumatic tire is configured to vulcanize a raw cover by using a sprit mold having upper and lower side metal molds and multiple segment metal molds, and a bladder. The method for manufacturing a pneumatic tire uses the raw cover provided at a shoulder part with a protrusion of 2-4 mm in height as a raw cover. The width of the protrusion is 30% or more of the width of a shoulder block in the method for manufacturing a pneumatic tire. The protrusion is provided at the position opposed to a projecting section for forming a shoulder lug groove provided at the segment metal molds in the method for manufacturing a pneumatic tire.

Description

  The present invention relates to a method for manufacturing a pneumatic tire capable of providing a product tire of stable quality by sufficiently suppressing the occurrence of rubber biting and remaining air during vulcanization molding.

  In the manufacturing process of pneumatic tires, split molds are generally used as tire vulcanization molds, and the upper and lower side molds are closed and sandwiched by a low cover held by a bladder, then a plurality of segments Vulcanization is performed by closing the mold from the circumferential direction.

  However, in the case of the above method, there is a possibility that rubber biting may occur when the mold is closed. That is, as shown in FIG. 4, when the bladder 28 and the raw cover 23 are arranged at predetermined positions and the side mold 20 is closed, the pressing force of the side mold 20 causes rubber at the corners of the side mold 20. The protruding portion 25 protrudes and is sandwiched between the segment mold 22 and the side mold 20 where the protruding portion 25 of the rubber is closed, thereby generating a rubber bite.

  Vulcanized tires with rubber biting not only cause poor appearance but also have an adverse effect on quality.

  Therefore, as a method for suppressing the occurrence of such a rubber bite, Patent Document 1 proposes that a concave portion is provided in a raw cover at a location corresponding to the vicinity of a corner portion of a side mold. That is, as shown in FIG. 5, the formation of the protruding portion of the rubber is suppressed by providing a recess 26 in advance around the raw cover 23 located in the vicinity of the corner 24 where the side mold 20 and the segment mold 22 contact each other. And prevents the occurrence of rubber chewing.

JP-A-6-23864

  However, in order to prevent the occurrence of rubber biting, the depth / width ratio of the recess 26 needs to be 0.3 or more, and in some cases, an air residue 30 may be generated (see FIG. 6). ).

  Therefore, in view of the above, the present invention does not cause the appearance of rubber tires and poor quality by sufficiently suppressing the occurrence of rubber biting, and also suppresses the occurrence of residual air and has a stable quality. It is an object of the present invention to provide a method for manufacturing a pneumatic tire that can provide a product tire.

The invention described in claim 1
Using a split mold having upper and lower side molds and a plurality of segment molds, and a bladder, a method for producing a pneumatic tire for vulcanizing a raw cover,
As the raw cover, a raw cover having a convex part having a height of 2 to 4 mm provided on a shoulder part is used.

The invention described in claim 2
The method for manufacturing a pneumatic tire according to claim 1, wherein the width of the convex portion is 30% or more of the width of the shoulder block.

The invention according to claim 3
The pneumatic tire according to claim 1, wherein the convex portion is provided at a position facing a convex portion for forming a shoulder lug groove provided in the segment mold. It is a manufacturing method.

The invention according to claim 4
The shoulder lug groove forming convex portion is formed in the segment mold so that the shoulder lug groove depth in the tire after vulcanization is 70% or more of the tread main groove depth. It is a manufacturing method of the pneumatic tire of Claim 3 characterized by the above-mentioned.

The invention described in claim 5
The height of the joint surface between the segment mold and the side mold is 20 to 30% of the section height of the tire, according to any one of claims 1 to 4. It is a manufacturing method of a pneumatic tire.

  According to the present invention, there is provided a product tire having a stable quality that sufficiently suppresses the occurrence of rubber biting and does not cause a defective appearance or poor quality of the product tire, and also sufficiently suppresses the occurrence of residual air. The manufacturing method of the pneumatic tire which can be provided can be provided.

In one embodiment of the present invention, it is a principal part sectional view showing a state where a side mold is pressing a raw cover. In one embodiment of the present invention, it is a principal part sectional view showing a state immediately before a segment mold presses a raw cover. In one Embodiment of this invention, it is principal part sectional drawing which shows the state which closed the metal mold | die. In the conventional manufacturing method of a pneumatic tire, it is principal part sectional drawing which shows the state which the side metal mold is pressing the raw cover. It is principal part sectional drawing which shows the state in which the side metal mold is pressing the raw cover in the other conventional manufacturing method of a pneumatic tire. It is principal part sectional drawing which shows the state which closed the metal mold | die in the other conventional manufacturing method of a pneumatic tire.

  Hereinafter, based on an embodiment, the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a main part showing a state in which the side mold presses the raw cover in the present embodiment, where 1 is a vulcanization mold, 2 is a side mold, 4 is a segment mold, Is a bladder, and 14 is a raw cover.

  The method of manufacturing a pneumatic tire in the present embodiment uses a vulcanizing mold 1 (split mold) having upper and lower side molds 2 and a plurality of segment molds 4 and a bladder 10 to It is the same as the conventional one in that vulcanization is performed.

  Therefore, unless special measures are taken, as shown in FIG. 1, when the side mold 2 is closed by moving it in the direction of the arrow, as shown in FIG. The rubber protrudes from the sidewall 15 of the raw cover 14 to the corner of the side mold 2. Conventionally, this protrusion of rubber has generated rubber biting.

  However, in the present embodiment, since the convex portion 18 is provided on the tread shoulder portion 17 of the raw cover 14, the occurrence of rubber biting is suppressed.

  That is, the raw cover 14 held by the side mold 2 is then pressed by the segment mold 4 that moves in the direction of the thin arrow in FIG. Contact.

  And since the convex part 18 which contacted the segment metal mold | die 4 is pressed by the segment metal mold | die 4 which moves further, and is pushed inside (the center direction of a raw cover), the rubber | gum which protruded to the corner | angular part of the side metal mold | die 2 is carried out. Including, the raw cover is pushed in the direction of the white arrow.

  As a result, as shown in FIG. 3, when the segment mold 4 is closed, the protrusion of the rubber is eliminated and the occurrence of the rubber biting is suppressed. In addition, since a sufficient amount of rubber is disposed in the vicinity of the corners of the side mold 2, the occurrence of air residue is sufficiently suppressed.

  In addition, in the above, although the case where the convex part 18 was provided in the tread shoulder part 17 of the raw cover 14 was demonstrated, if it is a location which can exhibit the same effect, shoulder parts other than the tread shoulder part 17 May be provided.

  As described above, according to the present embodiment, the occurrence of rubber biting can be sufficiently suppressed, and the occurrence of remaining air can also be sufficiently suppressed. Quality product tires can be provided.

  If the height H of the convex portion 18 is too low, the convex portion 18 is easily crushed by pressing with the segment mold 4, and the raw cover 14 cannot be sufficiently pushed in the direction of the white arrow. On the other hand, if the height is too high, the step on the surface of the raw cover 14 becomes large, and there is a risk that air residue will occur in the vulcanized tire. For this reason, the height H of the convex part 18 is set to 2-4 mm.

  The width W of the convex portion 18 is preferably 30% or more of the width of the shoulder block. If it is less than 30%, it is easily crushed by pressing with the segment mold 4, and the raw cover 14 may not be sufficiently pushed in the direction of the white arrow.

  The segment mold 4 usually has a tread portion 6 for forming a shoulder lug groove and a convex portion 6 for forming a shoulder lug groove in addition to the convex portion 5 for forming a tread main groove. It is preferable that the convex portion 18 is provided at a position facing the convex portion 6 for forming the shoulder lug groove provided in the segment mold 4.

  By providing the convex portion 18 at a position facing the convex portion 6 for forming the shoulder lug groove, when the segment mold 4 is closed, the convex portion 6 first contacts and presses the convex portion 18. It is preferable that the rubber can be pushed inward more reliably.

  At this time, the depth of the convex portion 6 for forming the shoulder lug groove is formed so that the depth of the shoulder lug groove in the tire after vulcanization becomes 70% or more of the depth of the tread main groove. Furthermore, it is preferable that the rubber can be surely pushed inward.

  As a tire having such a deep shoulder lug groove, a radial tire can be cited. By applying the present embodiment in the production of a radial tire, the effects of the present embodiment can be remarkably exhibited. it can.

  Moreover, if the height of the joint surface between the segment mold 4 and the side mold 2 is too low, it may be out of the range where it is pushed in the direction of the white arrow, and there is a risk of rubber biting. Since the joint surface may interfere with the pattern edge portion and the degree of freedom in pattern design may be reduced, it is preferably 20 to 30% of the tire section height.

1. Production of test tires 100 pneumatic tires (size 195 / 65R15) of Examples 1 to 3 and Comparative Examples 3 and 4 were produced for each using a raw cover formed with convex portions having the height and width shown in Table 1. did.

  Moreover, 100 pneumatic tires (size 195 / 65R15) of Comparative Examples 1 and 2 were each produced using a raw cover in which concave portions having the depth and width shown in Table 1 were formed.

  As a mold, a split mold including a segment mold divided into nine parts was used in each of the examples and comparative examples. The segment mold has a shoulder lug groove forming convex portion so that the depth of the shoulder lug groove is 85% of the depth of the tread main groove, and the segment mold and the side mold. The height of the joint surface with the tire is 23% of the section height of the tire.

2. Evaluation For each tire obtained in each of the examples and comparative examples, the occurrence of rubber biting and the occurrence of remaining air were evaluated.

  Note that the occurrence of rubber biting was evaluated by the rubber thickness (mm) protruding from the joint between the segment mold and the side mold, and the occurrence of remaining air was the occurrence of remaining air in the 100 produced. The number was evaluated. The results are shown in Table 1.

  From Table 1, it can be seen that in the tires (Examples 1 to 3) produced from the raw cover on which the convex portions having appropriate heights were formed, no air residue was generated. Then, it can be seen that the rubber bite is not generated by appropriately controlling the width.

  On the other hand, in tires (Comparative Examples 1 and 2) made from a raw cover having a recess, either rubber biting or air remaining occurs, and depending on the formation of the recess, the quality of the product tire can be stabilized. I understand that I can't.

  In addition, even in a tire (Comparative Examples 3 and 4) made from a low cover whose height of the convex portion is not appropriate, either rubber biting or air remaining is generated, and it can be seen that the quality of the product tire is not stable.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiments within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Vulcanization metal mold | die 2,20 Side metal mold | die 4,22 Segment metal mold | die 5 Convex part for tread main groove formation 6 Convex part for shoulder lug groove formation 10, 28 Bladder 14, 23 Raw cover 15 Side wall part 17 Tread shoulder portion 18 convex portion 24 corner portion 25 rubber protruding portion 26 concave portion 30 air remaining H convex portion height W convex portion width

Claims (5)

Using a split mold having upper and lower side molds and a plurality of segment molds, and a bladder, a method for producing a pneumatic tire for vulcanizing a raw cover,
A method for manufacturing a pneumatic tire, wherein a raw cover having a convex part with a height of 2 to 4 mm provided on a shoulder part is used as the raw cover.   The method for manufacturing a pneumatic tire according to claim 1, wherein the width of the convex portion is 30% or more of the width of the shoulder block.   The pneumatic tire according to claim 1, wherein the convex portion is provided at a position facing a convex portion for forming a shoulder lug groove provided in the segment mold. Production method.   The shoulder lug groove forming convex portion is formed in the segment mold so that the shoulder lug groove depth in the tire after vulcanization is 70% or more of the tread main groove depth. The manufacturing method of the pneumatic tire of Claim 3 characterized by the above-mentioned.   The height of the joint surface between the segment mold and the side mold is 20 to 30% of the section height of the tire, according to any one of claims 1 to 4. A method of manufacturing a pneumatic tire.

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