JP2015229465A - Pneumatic tire and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire whose appearance quality is improved by suppressing opening of a joint part when forming a carcass ply, and a manufacturing method for the pneumatic tire that can improve productivity by suppressing occurrence of a defective product caused by occurrence of air leak and deterioration in durability.SOLUTION: The pneumatic tire comprises a carcass ply having a plurality of carcass cords parallely arrayed. The carcass ply has a joint part wound around in a tire circumferential direction whose start end part and terminal end part are connected to each other. The joint part is formed of: a straight section at a central part of 80-120 mm approximately parallel to the carcass cords, and inclined sections that overlap with both sides of the straight line section and has inclination angles larger than 0° and equal to 10° or less.

Description

  The present invention relates to a pneumatic tire with improved appearance quality and a method for manufacturing a pneumatic tire capable of improving productivity.

  In the production of a pneumatic tire, in particular, a pneumatic radial tire, conventionally, in a process of winding a carcass sheet on a carcass drum to form a carcass ply, a plurality of carcass cords provided on the carcass sheet are It is practiced to form a carcass joint part (hereinafter also simply referred to as a “joint part”) by obliquely cutting and joining (joint) at an angle of greater than 0 ° and not more than 10 ° with respect to the cord (for example, Patent Document 1).

  By forming such a joint portion, it is possible to reduce the amount of deformation with respect to the joint dent that causes dents on the surface of the product tire, and to improve the appearance quality of the product tire.

  In the above, the number of overlapping carcass cords in the overlapping portion of the carcass ply is normally preferably 2 or more and 6 or less, but even if it exceeds 6 and 8 or less, the degree of joint dent (joint dent level) ) Is not significantly worsened.

JP 2000-225808 A

  However, in the above-described conventional technique, when the carcass drum is expanded to expand the formed carcass ply to the finished diameter of the tire (tire inner diameter), an opening may occur in the joint portion.

  If such an opening occurs, not only will the appearance quality of product tires be significantly reduced, but air leaks and durability may be reduced. It was causing a decline in sex.

  Therefore, the present invention suppresses the occurrence of opening in the joint portion when forming the carcass ply, and improves the appearance quality, and the occurrence of defective products due to the occurrence of air leaks and reduced durability. It is an object of the present invention to provide a method for manufacturing a pneumatic tire capable of suppressing productivity and improving productivity.

The invention described in claim 1
A carcass ply in which a plurality of carcass cords are arranged in parallel;
The carcass ply is wound in the tire circumferential direction, and has a joint portion in which a start end portion and a terminal end portion are joined,
The joint portion has a linear portion of a central portion of 80 to 120 mm substantially parallel to the carcass cord, and an inclination angle of more than 0 ° and not more than 10 ° with respect to the carcass cord connected to both sides of the linear portion. It is a pneumatic tire characterized by being formed with an inclined portion.

The invention described in claim 2
2. The pneumatic tire according to claim 1, wherein the number of overlaps of the carcass cords in the joint portion is 2 or more and 8 or less.

The invention according to claim 3
The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire is a radial tire.

The invention according to claim 4
Manufacture of a pneumatic tire comprising a carcass ply in which a plurality of carcass cords are arranged in parallel, the carcass ply being wound in the tire circumferential direction, and having a joint portion in which a start end portion and a terminal end portion are joined A method,
The joint portion has a linear portion of a central portion of 80 mm or more and 120 mm or less substantially parallel to the carcass cord, and an inclination angle of more than 0 ° and 10 ° or less with respect to the carcass cord connected to both sides of the linear portion. Cutting the start and end portions of the carcass ply to form an inclined portion having
After joining the start end and the end of the carcass ply on the carcass drum, the transverse portion located at the center of the joint is crimped by a transverse roller disposed above the carcass drum, And a step of forming a joint portion of the carcass ply.

The invention described in claim 5
5. The method for manufacturing a pneumatic tire according to claim 4, wherein the step of cutting the start end portion and the end end portion of the carcass ply is a step of cutting by a guillotine method.

The invention described in claim 6
The method for manufacturing a pneumatic tire according to claim 4 or 5, wherein a material of the traverse roller is polyamide resin or hard urethane rubber.

  According to the present invention, when a carcass ply is formed, it is possible to suppress the occurrence of an opening in the joint portion, and to improve the appearance quality, and to generate defective products due to the occurrence of air leaks and a decrease in durability. It is possible to provide a method for manufacturing a pneumatic tire that can suppress productivity and improve productivity.

It is sectional drawing which shows typically the structure of the pneumatic tire which concerns on one embodiment of this invention. It is a typical perspective view explaining formation of the joint part examined prior to this invention. It is a perspective view for demonstrating the carcass of the pneumatic tire shown in FIG. It is a schematic diagram of the overlap part of the carcass ply which shows other embodiment of the pneumatic tire which concerns on this invention.

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

1. FIG. 1 is a cross-sectional view schematically showing the structure of a pneumatic tire according to an embodiment of the present invention, and the basic configuration is the same as that of a conventional pneumatic tire. .

  As shown in FIG. 1, a pneumatic tire 1 includes a tread portion 2, sidewall portions 3 extending inward in the tire radial direction from both ends of the tread portion 2, and tire radial inner ends of the respective sidewall portions 3. And a bead portion 4 that is reinforced by a bead core 5.

  Further, a carcass ply 6 is bridged between the bead portions 4 and 4 in the pneumatic tire 1, and an inner liner layer (not shown) is disposed inside the carcass ply 6. Further, a belt layer (tire breaker) 9 is disposed between the carcass ply 6 and the tread portion 2.

  The carcass ply 6 is formed by arranging carcass cords in parallel at an angle of approximately 90 ° with respect to the circumferential direction of the tire 1. In the cross section of the tire, the carcass ply 6 passes through the sidewall portion 3 from the tread portion 2 and the bead core. At both ends of the toroidal shape up to 5, a bead core 5 is folded back and locked from the inner side to the outer side in the tire axial direction.

  In order to suppress the occurrence of the opening in the joint portion described above, the inventor was formed by first overlapping the start end portion and the end portion of the carcass ply 42 on the carcass drum 40 as shown in FIG. Various experiments and examinations were performed considering that the joint portion 44 is pressure-bonded by a press roller (not shown) disposed above the carcass drum 40.

  However, since the joint portion 44 is formed on the cylindrical carcass drum 40 by overlapping the start end portion and the end end portion of the carcass ply 42 in an inclined state, the joint portion 44 can be joined even if it is crimped by a presser roller. The portion 44 could not be pressed down sufficiently, and the occurrence of opening could not be suppressed sufficiently.

  That is, as shown in FIG. 2A, when the presser roller is advanced along the joint portion 44, the presser roller does not advance parallel to the axial direction of the carcass drum 40, but becomes a base carcass. Since the drum 40 advances while being curved, the joint portion 44 cannot be sufficiently pressed.

  As shown in FIG. 2B, when the presser roller is advanced in parallel with the axial direction of the carcass drum 40, the entire joint portion 44 cannot be pressed.

  In addition, as shown in FIG. 2C, when the plurality of press rollers are used to advance in parallel with the axial direction of the carcass drum 40, the entire joint portion 44 can be sufficiently pressed. Another problem is that it is difficult to secure a space for installing a plurality of press rollers, and there is a problem in equipment strength.

  However, the present inventor has obtained knowledge to be noted in the above experiments and examinations, and has completed the present invention. That is, it was found that the joint portion was opened within a range of 120 mm or less of the central portion of the carcass ply, and the joint portion was not opened at the outer portion.

  Based on this knowledge, the present inventor has come to use a carcass ply 6 as shown in FIG. That is, in FIG. 3, the carcass ply 6 is wound more than one turn in the circumferential direction of the tire 1, so that the start end portion and the end end portion of the winding overlap and the joint portion 20 is formed. In this case, the joint portion 20 has an 80-120 mm central straight portion 20a substantially parallel to the carcass cord 10, and an inclination of more than 0 ° and not more than 10 ° with respect to the carcass cord connected to both sides of the straight portion 20a. The carcass ply 6 is cut in advance so as to be constituted by the inclined portions 20b and 20c having an angle. And after winding this carcass ply 6 on the carcass drum 40, only the range within 120 mm of the linear part 20a of the center part of the carcass ply 6 is traversed using the pressing roller, and the joint part 20 is formed.

  In this way, the press-bonding roller is advanced in parallel to the axial direction of the carcass drum 40 only within the range of 120 mm or less of the central portion of the carcass ply where the joint portion is likely to open, thereby strengthening the pressure bonding of the joint portion. It is possible to suppress the opening of the joint portion.

  And since this part is always located below the tire breaker, even if joint dent is generated by crimping the joint part with the pressing roller, this joint dent is in the center of the carcass ply. It does not appear in the department.

  In this way, by strengthening the crimping of the center part of the carcass ply where the joint part of the carcass cord is likely to open, the amount of deformation of the joint can be reduced without worrying about the opening of the joint part. The appearance quality of the product tire can be improved. In addition, since air leakage can be prevented and durability can be improved, the occurrence of defective products can be reduced and productivity can be improved.

  In the present embodiment, the number of overlaps of the carcass cord 10 of the joint portion 20 is preferably 2 to 8.

  In addition, as shown in FIG. 4A, the inclination angles in the inclined portions 20b and 20c are preferably the same angle on the left and right with respect to the straight portion 20a in terms of tire uniformity, but may be different. .

  Further, as shown in FIG. 4 (A), the inclination directions of the inclined portions 20b and 20c are preferably symmetrical on the left and right with respect to the center of the straight portion 20a from the viewpoint of tire uniformity. The direction may be the same as shown in (B).

  As the carcass cord 10, various cords made of polyamide resin such as nylon (registered trademark), organic fiber such as rayon, polyester, aromatic polyamide, steel, or inorganic fiber, can be used.

2. Method for Manufacturing Pneumatic Tire In the method for manufacturing a pneumatic tire according to the present embodiment, the assembly of the carcass ply to the tire is performed as follows.

  First, the carcass ply is disposed on the upper side of the carcass ply while the carcass ply made of the carcass ply having the carcass cord angle (the angle of the carcass cord with respect to the circumferential direction of the carcass drum) being 90 ° is conveyed by the conveyor. Cut off the start and end parts (including carcass cords).

  At this time, at the start end portion and the end portion of the carcass ply, the straight portion of the central portion of 80 to 120 mm substantially parallel to the carcass cord, and the carcass cord connected to both sides of the straight portion exceed 0 ° and 10 °. It cut | disconnects so that the inclination part which has the following inclination angles may be formed.

  Next, a long carcass ply is wound on the outer periphery of the carcass drum so that the start and end portions of the carcass ply are overlapped. Then, with the presser roller disposed above the carcass drum, only the straight portion a of the overlapping portion of the carcass ply is traversed and pressed to form a joint portion.

  At this time, the press roller is preferably a press roller made of polyamide resin such as MC nylon (registered trademark) or hard urethane rubber.

  Thereafter, another tire rubber material is laminated on the carcass ply to form a green tire, and the green tire is vulcanized to obtain a product tire.

1. Manufacturing Method of Examples and Comparative Examples As a carcass ply, a carcass ply having a carcass cord of polyester cord (1500d / 2) and a carcass cord angle of 90 ° was used, and tire size 175 / 80R14 (expansion allowance: 1.6) ) Pneumatic tires were manufactured.

  At this time, the number of overlapping carcass cords in the joint portion and the length of the straight portion 20a were changed as shown in Table 1. In addition, the conditions of the inclination angles of the inclined portions 20b and 20c were fixed at 10 °. Moreover, the joint part was formed by traversing with the above-mentioned pressing roller and crimping. In Table 1, Comparative Example 1 is a conventional pneumatic tire.

2. Evaluation Method of Examples and Comparative Examples For each of the manufactured pneumatic tires, the deformation state of the unevenness on the surface of the sidewall 3 when the normal internal pressure of 180 Kpa was filled with air was measured and evaluated.

  The evaluation was scored using the following sensory evaluation evaluation method. As for the measurement results, 4 points or more are at a level that satisfies users in the market. In addition, the average value of various sample number n = 10 was made into the measurement result.

5 points: Joint dents cannot be found by visual and tactile senses.
4 points: Joint dents cannot be found only by vision.
3 points: The joint dent can be found only by vision, but it is small.
2 points: Joint dents can be found by visual only.
1 point: A joint dent having a practical problem can be found.

3. Evaluation results of examples and comparative examples Table 1 shows the results.

  In Table 1, the column “Evaluation” indicates the overall evaluation result, where “◯” indicates excellent, “Δ” indicates acceptable, and “×” indicates impossibility.

  (1) From Examples 1, 2, 3, and 4, the length of the straight end portion 20a of the carcass ply is 80 mm or more and 120 mm or less, and the number of overlaps of the carcass cord 10 of the joint portion 20 is two. In the case of the above eight or less, it was found that the rate of occurrence of the opening (open joint) of the joint portion 20 was 0%, and a good result with an evaluation result exceeding 4 points was obtained.

  (2) Further, from Example 5, even when the length of the straight end portion 20a of the carcass ply is 120 mm, the number of overlaps of the carcass cord 10 of the joint portion 20 is ten. Although the dent evaluation result was slightly inferior to 3.6 and some joint dents were generated, it was found that the incidence of open joints (open joints) was 0%.

  (3) On the other hand, from Comparative Examples 1 and 2, it was found that when the length of the straight end portion 20a of the carcass ply is less than 80 mm, the joint portion 20 opens. Further, from Comparative Examples 3 and 4, it was found that when the length of the straight portion 20a at the start and end portions of the carcass ply exceeds 120 mm, joint dent occurs.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6, 42 Carcass ply 9 Belt layer (tire breaker)
10 Carcass cord 20, 44 Overlapping part (joint part) of the start and end parts of the carcass ply
20a Straight line part (central part)
20b, 20c inclined part 40 carcass drum

Claims (6)

A carcass ply in which a plurality of carcass cords are arranged in parallel;
The carcass ply is wound in the tire circumferential direction, and has a joint portion in which a start end portion and a terminal end portion are joined,
The joint portion has a linear portion of a central portion of 80 to 120 mm substantially parallel to the carcass cord, and an inclination angle of more than 0 ° and not more than 10 ° with respect to the carcass cord connected to both sides of the linear portion. A pneumatic tire characterized by being formed with an inclined portion.   2. The pneumatic tire according to claim 1, wherein the number of overlaps of the carcass cord in the joint portion is 2 or more and 8 or less.   The pneumatic tire according to claim 1, wherein the pneumatic tire is a radial tire. Manufacture of a pneumatic tire comprising a carcass ply in which a plurality of carcass cords are arranged in parallel, the carcass ply being wound in the tire circumferential direction, and having a joint portion in which a start end portion and a terminal end portion are joined A method,
The joint portion has a linear portion of a central portion of 80 mm or more and 120 mm or less substantially parallel to the carcass cord, and an inclination angle of more than 0 ° and 10 ° or less with respect to the carcass cord connected to both sides of the linear portion. Cutting the start and end portions of the carcass ply to form an inclined portion having
After joining the start end and the end of the carcass ply on the carcass drum, the transverse portion located at the center of the joint is crimped by a transverse roller disposed above the carcass drum, And a step of forming a joint part of the carcass ply.   The method for manufacturing a pneumatic tire according to claim 4, wherein the step of cutting the start end portion and the end end portion of the carcass ply is a step of cutting by a guillotine method.   The method for manufacturing a pneumatic tire according to claim 4 or 5, wherein the material of the transverse roller is polyamide resin or hard urethane rubber.

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