JP2008260219A - Manufacturing method for pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent wrinkles from occurring in manufacturing a green tire. <P>SOLUTION: A strip of unvulcanized composite rubber 21 integrating a strip of side rubber 20a and a strip of first tread rubber 18Aa is wound on the outer surface of a carcass, and then, a strip of second tread rubber member 18B is attached to the outer surface of the central side in the width direction of a carcass case. A belt 16 on the carcass case has a circular shape, but since the diameter difference between both the end parts and a tire equatorial plane part is reduced in the central area in the width direction having a strip of second tread rubber 18Ba to be attached, so called squeezing is reduced compared to the conventional one and the wrinkles are prevented from occurring in the final step of attaching the strip of second tread rubber 18Ba to the outer surface of the belt. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a pneumatic tire, and more particularly to a method for manufacturing a pneumatic tire that does not generate wrinkles that cause product defects when manufacturing a pneumatic tire having a small radius of curvature of a crown portion.

  When forming a green tire, first, a carcass is formed in a shape close to that of a product tire, and a belt, tread rubber or the like is attached to the outer surface thereof. Further, the tread rubber is pasted so as to be pressed against the outer peripheral surface of the belt by a stitcher.

Japanese Patent Laid-Open No. 01-127401 JP 2005-271760 A

  Pneumatic tires with a tread outer diameter that is smaller at the tread end than the tire equatorial plane cause wrinkles when narrowing the tread rubber on the tread end side during green tire molding, resulting in variations in the product gauge. It may cause defects such as air entering and bearing during vulcanization, and it is difficult to take measures only by changing the stitcher conditions during molding.

  In forming raw tires, tread rubber is attached to the carcass that is close to the product tire, but the tread rubber is prepared according to the maximum diameter part (tire equatorial surface) of the belt attached on the carcass. There is no problem on the tire equatorial plane, but there is a dragging when narrowing down the tire on both sides.

  That is, in the region where the tread rubber is pasted, the outer diameter of the portion corresponding to the vicinity of the tread end is smaller than the diameter of the tire equatorial plane, so the tread rubber supplied in a substantially straight section is a belt having an arc section. If you try to affix it to the outer peripheral surface, the tread rubber will be left in the part corresponding to the vicinity of the tread end by the difference in the circumferential length from the tire equator part, and this extra part will be forcibly applied to the outer peripheral surface of the belt. By trying to attach, it will generate a habit that becomes a problem in mass production.

  As a result of examining the occurrence of wrinkles in detail, the occurrence of wrinkles in the tread rubber is related to the ratio of the tread end outer diameter to the maximum diameter (tread end outer diameter / maximum diameter) and the raw gauge of the tread rubber. The present inventor found out. Furthermore, it was also found that when the raw gauge of the tread rubber is less than a certain thickness, no wrinkles are generated regardless of the ratio of the outer diameter / maximum diameter of the tread end.

The inventor has conducted various experimental studies, and as a result, when manufacturing a pneumatic tire having a relatively large ratio of tread end outer diameter / maximum diameter, more specifically, a pneumatic tire for a motorcycle, etc., the tread rubber It has been found that wrinkle generation during raw tire production can be suppressed by devising how to attach the tire.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a pneumatic tire that can suppress generation of wrinkles during manufacturing of a raw tire.

  The manufacturing method of a pneumatic tire according to claim 1 includes a belt-shaped first tread rubber member for forming both side portions in the tire width direction of a tread portion in a product tire and a belt-shaped side rubber member for forming a side portion in the product tire. Are attached along the circumferential direction to the outer surface of the carcass case and the widthwise end side of the belt member disposed on the outer surface of the carcass case. A second step of affixing a belt-like second tread rubber member constituting a tire equatorial plane side of a tread portion in a product tire along a circumferential direction to a tire width direction central outer surface of the belt member; It is characterized by having.

Next, the manufacturing method of the pneumatic tire according to claim 1 will be described.
First, in the first step, the belt-shaped first tread rubber member for forming both side portions in the tire width direction of the tread portion in the product tire and the belt-shaped side rubber member for forming the side portion in the product tire are integrated. The belt-shaped side rubber member faces the outer surface of the carcass case, and the first belt-shaped tread rubber member faces the outer surface of the belt member in the width direction, with respect to the carcass case in which the belt-shaped composite rubber member includes the belt member and the like. To be pasted. This step can be performed with a tire molding drum as in the conventional case.

  In the second step, a belt-like second tread rubber member constituting the tire equatorial plane side of the tread portion of the product tire is attached along the circumferential direction to the outer surface on the center side in the tire width direction of the belt member.

  In the manufacturing method of the pneumatic tire according to claim 1, since the belt-like composite rubber member is attached to the belt outer surface and the carcass case outer surface so that the belt-like first tread rubber member corresponds to the smaller diameter side of the belt outer surface, Because it is different from the conventional method of narrowing down (forcibly reducing the diameter) the tread rubber member supplied according to the tire equatorial plane side with a larger diameter on the smaller side of the belt outer surface. The generation of wrinkles due to the above-mentioned narrowing does not occur in principle during the production of raw tires.

  As described above, according to the method for manufacturing a pneumatic tire of the present invention, there is an effect that generation of wrinkles can be prevented when manufacturing a pneumatic tire with a large tread curvature.

Below, the manufacturing method of the pneumatic tire of this invention is demonstrated.
FIG. 1 is a sectional view of a pneumatic tire 10 for a motorcycle manufactured by the method for manufacturing a pneumatic tire of the present invention.
In FIG. 1, reference numeral 10 denotes a pneumatic pneumatic tire for a motorcycle, reference numeral 12 denotes a bead core, reference numeral 14 denotes a carcass, reference numeral 16 denotes a belt, reference numeral 18A denotes a first tread rubber member, reference numeral 18B denotes a second tread rubber member, reference numeral Reference numeral 20 denotes a side rubber member.

  The belt-shaped first tread rubber member 18A is formed so that the gauge becomes thinner toward the tire equatorial plane CL side, and the second tread rubber member 18B is formed so as to become thinner toward the tread end 18E, and the first tread rubber is formed. The tapered portion of the member 18A and the tapered portion of the second tread rubber member 18B overlap each other.

  In FIG. 1, for convenience of explanation of the present invention, the boundary SL between the first tread rubber member 18A and the second tread rubber member 18B is indicated by a two-dot chain line, but the first tread rubber member 18A and the second tread rubber member 18A The tread rubber member 18B is the same kind of rubber in the present embodiment, and the boundary line SL is not actually visible.

(Manufacturing process)
Next, the manufacturing process of the pneumatic tire 10 for motorcycles will be described. In addition, the manufacturing process of this pneumatic tire 10 for motorcycles is not different from the conventional one except for the tread portion described below.
Conventionally, on the outer peripheral surface of the carcass formed on the outer peripheral surface of the tire molding drum, a belt-like belt, a belt-like unvulcanized side rubber, and a belt-like unvulcanized tread rubber were attached to obtain a raw tire. In this embodiment, an unvulcanized belt-like composite rubber member 21 in which a belt-like side rubber member 20a having a cross-sectional shape as shown in FIG. 2 and a belt-like first tread rubber member 18Aa are integrated is wound around the outer surface of the carcass.

  Here, the belt-shaped side rubber member 20a is directed to the carcass outer surface portion serving as a sidewall and a bead portion in the product tire, and the belt-shaped first tread rubber member 18Aa is directed from the tread end 18E of the product tire to the tire equatorial plane CL side. Affixed to the part.

  The band-shaped composite rubber member 21 used here may be formed by simultaneously extruding a tread rubber and a side rubber from one base, and a band-shaped side rubber member 20a and a first band-shaped first tread rubber member 18Aa extruded from different bases are attached. You may make it attach.

  Thereafter, with respect to the carcass case in which the band-shaped composite rubber member 21 is bonded to both sides, the taper portion of the band-shaped first tread rubber member 18Aa and the unvulcanized band-shaped second tread rubber having a cross-sectional shape as shown in FIG. The belt-shaped second tread rubber member 18B is attached to the outer surface on the center side in the width direction of the carcass case so that the tapered portion of the member 18Ba overlaps, and the raw tire is completed.

  The belt 16 on the carcass case has an arc shape when viewed in cross section, but in the central region in the width direction where the belt-like second tread rubber member 18Ba is attached, there is little difference in diameter between the both end portions and the tire equatorial plane portion. In other words, so-called narrowing is reduced as compared with the conventional case, and wrinkles are not generated in the final process of attaching the belt-like second tread rubber member 18Ba to the outer surface of the belt.

The green tire is then vulcanized with a mold as before to become a product tire.
Since the annular member loaded in the mold has no wrinkles, there is no occurrence of defects such as bears due to wrinkles.

In the pneumatic tire in which the “outer diameter De of the tread end / the outermost diameter D ₀ of the tread (see FIG. 1)” of the product is 0.95 or less, wrinkles are likely to occur near the tread end. This is particularly effective when manufacturing a pneumatic tire having a “tread end outer diameter / tread outermost diameter” of 0.95 or less. Of course, the present invention may be applied when manufacturing a pneumatic tire having an “outer diameter of the tread end / outermost diameter of the tread” exceeding 0.95.

The present invention is not limited to two-wheeled vehicles, and may be used when manufacturing pneumatic tires for other uses such as three-wheeled vehicles, four-wheeled vehicles, and the like.
Since the cross-sectional shape, width, gauge, and the like of the first tread rubber member 18A and the second tread rubber member 18B vary depending on the type of tire, if they are mass-produced after determining a combination of dimensions that does not cause wrinkles by trial production in advance. good.

  It should be noted that a pneumatic tire for a motorcycle having a tire size of 240 / 50ZR16 (outer diameter 652 mm, tread end outer diameter 538 mm, drop amount 82% (530 ÷ 652 × 100), tread width 290 mm, conventional method and method of the present invention ( As a result of trial manufacture with a width of 250 mm of the second tread rubber member and a width of 20 mm of the first tread rubber member), the conventional method produced wrinkles on the raw tire, but in the present invention, no wrinkles were generated.

1 is a cross-sectional view of a pneumatic tire for a motorcycle. It is sectional drawing of a strip | belt-shaped composite rubber member. It is sectional drawing of a strip | belt-shaped 2nd tread rubber member.

Explanation of symbols

10 Raw Tire 18Aa Band-shaped First Tread Rubber Member 18Ba Band-shaped Second Tread Rubber Member 20 Side Rubber Member
21 Band-shaped composite rubber member

Claims (1)

A belt-like composite rubber member in which a belt-like first tread rubber member for forming both side portions in the tire width direction of a tread portion in a product tire and a belt-like side rubber member for forming a side portion in the product tire are integrated in parallel. A first step of attaching along the circumferential direction to the outer surface of the carcass case and the width direction end portion side of the belt member disposed on the outer surface of the carcass case;
A second step of affixing a belt-like second tread rubber member constituting the tire equatorial plane side of the tread portion of the product tire along the circumferential direction on the outer surface of the belt member on the center side in the tire width direction. A method of manufacturing a pneumatic tire characterized by the above.

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