JP2007276268A - Method for producing pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve uniformity by reducing the amount of a meandering band strip when the jointless band ply forming a band strip is wound. <P>SOLUTION: The gap between the bead cores 5 and 5 of a cylindrical main cover 9 including inner liner rubber 8 and carcass ply 6A is swelled by the expansion of a former 21, and the jointless band ply 7A is formed on the outer surface of the main cover 9 in a swelled shape by winding the tapelike band strip c1 spirally in the tire's circumference. In the peripheral surface 21S of the former 21, to align the splice part 12 of the inner liner rubber 8 or the carcass ply 6A, a recess 15 in which the splice part 12 is put is formed. A thickness relaxation layer 16 which is made of a sponge material makes the outer surface of the splice part 12 flat by absorbing the thickness is arranged at least in the recess 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tire manufacturing method in which a jointless band ply is provided in a tread portion, and more specifically, manufacturing a pneumatic tire capable of improving uniformity by suppressing meandering of a band cord when forming the band ply. Regarding the method.

  For example, in a tire for a motorcycle, a tire having a structure in which a jointless band ply in which a band cord is spirally wound in the tire circumferential direction is arranged outside the carcass ply and inside the tread portion is often used. And the thing of patent document 1 is proposed as a manufacturing method of the tire of such a structure.

  In this manufacturing method, as conceptually shown in FIG. 12, a cylindrical body cover a including an inner liner rubber and a carcass ply wound around in the circumferential direction is formed into a former b having a contour shape close to the final tread contour shape. The tape-shaped band strip c1 in which the band cord is rubberized directly on the outer surface of the main body cover a in the tire circumferential direction in a bulging and holding state by the former b. It is spirally wound. Therefore, even for a tire having a very small tread radius, such as a motorcycle tire, the jointless band ply c can be accurately formed without causing the band strip c1 to collapse. There is an advantage that the uniformity of the tire can be improved, for example, occurrence of air accumulation between c and the main body cover a can be prevented.

Japanese Patent Laid-Open No. 2003-118011

  However, as shown in FIG. 13A, in the inner liner rubber a1 and the carcass ply a2 of the main body cover a, the circumferential ends after being wound once are overlapped with each other. Therefore, when the main body cover a is expanded by expanding the former b, the local thickness change occurring in the lap joint j is caused by a belt-like convex portion on the outer surface of the main body cover a. Appears as i. As a result, when the band strip c1 is spirally wound at a high speed on the outer surface of the main body cover a, when the band strip c1 rides on the convex portion i, as exaggeratedly shown in FIG. As a result, there is a tendency to cause partial meandering, and there is room for further improvement, such as reducing the effect of improving uniformity. Since the joint width j1 of the inner liner rubber a1 is wider than the joint j2 of the carcass ply c2, the influence on meandering becomes stronger.

  Therefore, the present invention can flatten the band-shaped protrusions on the basis of forming a concave portion into which the overlap joint portion is formed on the molding surface of the former and disposing a thickness relaxation layer made of a sponge material in the concave portion. An object of the present invention is to provide a method for manufacturing a pneumatic tire capable of suppressing partial meandering when the band strip is wound and achieving further improvement in uniformity.

In order to achieve the above-mentioned object, the invention of claim 1 of the present application is characterized in that an inner liner rubber having a first lap joint portion that is wound around in the circumferential direction and whose circumferential ends are lap-joined to each other, and radially outside thereof. A laminated sheet body including a carcass ply having a second lap joint portion that is wound once and is circumferentially joined, and a cylindrical shape having a pair of bead cores that locks both sides of the main body portion of the lap sheet body. Forming a body cover of
The step of causing the bead cores to approach each other and bulging the main body by expanding the diameter of a former whose diameter can be increased and decreased and whose outer peripheral surface forms a molding surface;
And a tread structure including a jointless band ply by spirally winding a tape-shaped band strip in the tire circumferential direction on the outer surface of the bulging-shaped main body in the bulging holding state by the former While providing the process of arranging the member and forming the tread portion,
The molding surface of the former is aligned with the first or second lap joint, and a recess extending in the width direction of the former and entering the lap joint is formed, and at least in the recess, a sponge material is formed. And a thickness relaxing layer that absorbs the thickness and flattens the outer surface of the lap joint.

According to a second aspect of the present invention, the thickness relaxation layer has a thickness T of 1.0 to 5.0 times the thickness of the inner liner rubber.
According to a third aspect of the present invention, the thickness relaxing layer has a sponge hardness of 50 to 300N.
According to a fourth aspect of the present invention, the concave portion has a belt shape extending at an angle of 0 to 30 ° with respect to the tire axial direction in accordance with the inclination direction of the circumferential edge of the carcass ply or inner liner rubber. It is characterized by.
According to a fifth aspect of the present invention, the thickness relaxing layer is composed of only a buried portion disposed in the concave portion.
According to a sixth aspect of the present invention, the thickness relaxing layer includes an embedded portion disposed in the concave portion and a cover portion that is integrated with the embedded portion and covers the entire circumference of the molding surface of the former. It is characterized by.

  In the present invention, as described above, a concave portion into which the overlapping joint portion is formed is formed on the molding surface of the former, and a thickness relaxing layer made of a sponge material is disposed in the concave portion. Accordingly, when the main body cover is expanded by expanding the former, the thickness change of the lap joint portion of the main body cover is absorbed by the compression of the relaxation layer, and the outer surface of the lap joint portion is flattened. As a result, partial meandering when the band strip is wound can be suppressed, and the uniformity can be further improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a meridional sectional view of a pneumatic tire formed by the manufacturing method of the present invention, and FIG. 2 is a schematic diagram conceptually showing the manufacturing method.

  In FIG. 1, a pneumatic tire T is a motorcycle tire in this example, and includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and the inside of the tread portion 2. A band layer 7 placed on the outer side in the radial direction of the carcass 6.

  The tread portion 2 is curved in a convex arc shape from the tire equator C toward the tread end E, and the tread width Tw that is the distance between the tread ends E and E is configured to be the maximum tire width. ing. At this time, in this example, the tread curvature radius Tr is as small as 0.70 times or less of the tread width Tw, thereby enabling turning at a large bank angle.

  The carcass 6 includes at least one carcass ply 6A in which carcass cords are arranged at an angle of 75 to 90 ° with respect to the tire circumferential direction, in this example, one carcass ply 6A, and both ends thereof are tires around the bead core 5. It is folded and locked from the inner side to the outer side in the axial direction. Inside the carcass ply 6A, an inner liner rubber 8 made of a low air permeability rubber such as butyl rubber and forming a tire lumen surface is disposed. The band layer 7 is composed of one or more, in this example, one jointless band ply 7A in which a band cord is spirally wound at an angle of 5 ° or less with respect to the tire circumferential direction. The band ply 7A is formed by spirally winding a tape-shaped band strip a1 in which band cords are aligned in a topping rubber in the tire circumferential direction. As the carcass cord and the band cord, for example, an organic fiber cord such as nylon, polyester, or rayon is preferably used.

Next, as shown conceptually in FIG.
(1) Step K1 for forming a cylindrical main body cover 9 having an inner liner rubber 8, a carcass ply 6A, and a bead core 5 (referred to as a main body cover forming step K1 for convenience);
(2) A process K2 in which the body cover 9 is expanded between the bead cores 5 and 5 by increasing the diameter of the former 21 capable of expanding and contracting, while bringing the bead cores 5 and 5 closer to each other (referred to as a bulging process K2 for convenience); (3) Step K3 of forming the tread portion 2 by disposing the tread constituent member 10 including the jointless band ply 7A on the outer surface of the bulged main body cover 9 in the bulging holding state by the former 21. (For convenience, it is referred to as a tread forming step K3);
It is comprised including.

Here, as shown in FIG. 3, the main body cover forming step K1 can be carried out by using a forming drum 50 having a well-known structure and in a method substantially similar to the conventional method. The forming drum 50 is a cylindrical body capable of expanding its diameter, and the main body cover 9 is formed in the following order (a) and (b). That is,
(A) On the molding drum 50, the sheet-like inner liner rubber 8 is wound once in the circumferential direction, and the sheet-like carcass ply 6A is wound once in the circumferential direction on the outer side in the radial direction. At this time, as shown in FIGS. 4A and 4B, the circumferential end 8e of the inner liner rubber 8 is spliced together to form a first spliced portion 12A, and the carcass ply 6A. The circumferential ends 6e are spliced together to form a second spliced portion 12B. Thereby, the cylindrical overlapping sheet body 11 including the inner liner rubber 8 and the carcass ply 6A is formed. The first and second lap joints 12A and 12B may be collectively referred to as a lap joint 12 in some cases.
(B) The annular bead core 5 is inserted from both axial outer sides of the cylindrical overlap sheet body 11, and the bead core 5 is set on the overlap sheet body 11. Then, the protruding portion 11B of the overlapping sheet body 11 protruding from the bead core 5 is folded around the bead core 5 so that the body cover 9 in which both sides of the body portion 11A of the overlapping sheet body 11 are locked by the bead core 5 is provided. It is formed. In addition to the inner liner rubber 8 and the carcass ply 6 </ b> A, the stacked sheet body 11 may include sidewall rubber for forming the sidewall portion 3, clinch rubber for forming the bead portion 4, and the like. Further, the folding of the protruding portion 11B around the bead core can be performed between the bulging step K2 and the tread forming step K3 and after the tread forming step K3 as required.

  And the main body cover 9 formed by the said main body cover formation process K1 is transferred to the tire formation apparatus 1 containing the former 21 after removing from the said forming drum 50 in this example, This former 21 is used. The bulging process K2 and the tread forming process K3 are performed.

  As shown in FIG. 5, the tire forming apparatus 1 includes a clamp ring 20 that clamps the bead cores 5 and 5 of the transferred body cover 9 so as to approach the axial direction, and the body portion 11 </ b> A (body cover 9). A swell forming means 22 having a former 21 swelled between the bead cores 5 and 5 is provided.

  In the present example, as shown in FIG. 6, the clamp ring 20 includes a seat portion 23 </ b> A seated on the bottom surface of the bead core 5 via the stacked sheet body 11, and a small height from the inner end in the axial direction of the seat portion 23 </ b> A. A locking portion 23B that locks and positions the inner side surface in the axial direction of the bead core 5 by standing up, and an inclined portion 23C for guiding the bead core that extends downwardly from the axial outer end of the seating portion 23A in a cone shape. Formed with.

  In this example, one clamp ring 20A (on the right side in FIG. 5) is fixed to, for example, the front end portion of the drum shaft 26 so as to be integrally rotatable with the drum shaft 26 using the first mounting bracket 24. The The clamp ring 20B on the other side (left side in FIG. 5) uses the second mounting bracket 25 and can rotate integrally with the drum shaft 26 via a sleeve tube portion 27 which is externally attached to the drum shaft 26. It is held so as to be slidable in the axial direction. The second mounting bracket 25 includes a slidable slide tube portion 29 that is externally inserted into the sleeve tube portion 27, and a body portion 30 that is continuous with the inner end in the axial direction of the slide tube portion 29. The body portion 30 has a larger diameter than the slide tube portion 29, thereby forming a piston chamber H with the sleeve tube portion 27.

  A case portion 32 is rotatably mounted on the outer end side in the axial direction of the slide cylinder portion 29 via a bearing piece 31 such as a ball bearing. For example, a ball screw mechanism or the like is used for the case portion 32. The slide moving means 33 is linked. Accordingly, the clamp rings 20A and 20B can move relatively close to each other by the parallel movement of the case portion 32 by the slide moving means 33, and the mounting brackets 24 and 25 and the clamp ring 20A, 20 </ b> B can rotate integrally with the drum shaft 23.

  Next, as shown in FIG. 7 (circumferential sectional view perpendicular to the axial direction), the former 21 has a tapered shape in which both side surfaces sa in the circumferential direction gradually approach inward in the radial direction. The first segment 21A and the second segment 21B having opposite side surfaces sb asymptotically outward in the radial direction are alternately combined. The first and second segments 21A and 21B can be moved radially outward by an expanding / contracting diameter means 34, which will be described later. In the expanded diameter state Y1 where the adjacent side surfaces sa and sb are substantially in contact with each other, the outer peripheral surface 21S is substantially the same. It is formed in a perfect circle. Further, when the diameter is reduced, the former 21 can be reduced in diameter by configuring the moving distance in the radially inward direction of the second segment 21B to be larger than the moving distance of the first segment 21A. .

  The expansion / contraction diameter means 34 includes guide means 34A for guiding the segments 21A and 21B inward and outward in the radial direction and movement means 34B for moving the segments 21A and 21B along the guide means 34A. The guide means 34A comprises a plurality of guide shafts 36 extending radially outward from the drum shaft 26, and the guide shafts 36 are fitted with guide holes provided in the segments 21A and 21B. The segments 21A and 21B can be guided inward and outward in the radial direction. Further, as shown in FIG. 5, the moving means 34B includes a cylindrical reciprocating member 39 disposed in the piston chamber H and capable of sliding in the axial direction on the sleeve tube portion 27, and the reciprocating member 39. And a first link body 40 that connects the first segment 21A and a second link body 41 that connects the reciprocating member 39 and the second segment 21A. Here, the link length of the second link body 41 is larger than the link length of the first link body 40, thereby reducing the amount of diameter reduction of the second segment 21B from the expanded diameter state Y1. It can be set smaller than the diameter reduction amount of the first segment 21A. The reciprocating member 39 can be slid in and out in the axial direction by a linear actuator 42 which is an air cylinder fixed to the frame F in this example. The linear actuator 42 is connected to the reciprocating member 39 through a rod member 43 that includes an axial joint shaft 43 </ b> A that penetrates the body 30 and extends to the piston chamber H.

  The former 21 of the present embodiment has a contour shape of the band ply 7A in the vulcanized finished tire T (shown in FIG. 1) in the meridional section including the drum shaft 26, as schematically shown in FIG. It has a shape close to. Strictly speaking, the former 21 has a contour shape obtained by subtracting the thickness of the main body cover 9 from the contour shape of the inner surface in the radial direction of the band ply 7A set in consideration of the stretching in the vulcanization mold. Accordingly, by expanding the diameter of the former 21 having such a contour shape to the expanded diameter state Y1, the main body portion 11A (main body cover 9) bulges between the bead cores 5 and 5 in a shape close to the final shape. be able to. The “final shape” means a shape in a finished vulcanized tire or a shape in a raw tire before vulcanization.

  Here, when the main body 11 </ b> A (main body cover 9) is expanded by expanding the former 21, the inner peripheral surface of the main body 11 </ b> A (main body cover 9) is pressed by the former 21. Therefore, when the molding surface S, which is the outer peripheral surface 21S of the former 21, is hard as in the prior art, the thickness change in the lap joint 12 is a convex portion i (see FIG. 13B) radially outward. As shown).

  Therefore, in the present invention, as shown in FIGS. 8 and 9, the molding surface S of the former 21 extends in the width direction of the former 21 and the first overlapped portion 12A of the inner liner rubber 8 or the carcass ply. A belt-like recess 15 into which the 6A second lap joint 12B enters is formed, and the outer surface of the lap joint 12A or 12B is flattened by absorbing the thickness of at least the recess 15 made of a sponge material. A thickness relaxing layer 16 is provided.

  The recess 15 is formed in alignment with the first lap joint 12A or the second lap joint 12B. That is, the concave portion 15 can be formed by aligning with one of the first and second overlapped portions 12A and 12B, or the concave portion 15 can be formed at both positions. However, the first lap joint 12A generally has a wider joint width and a larger volume at the joint compared to the second lap joint 12B, and therefore has a strong influence on the meandering of the band strip c1. Therefore, it is preferable to form the recess 15 at least at the position of the first lap joint 12A.

  Further, as conceptually shown in FIG. 10, the concave portion 15 is aligned with the inclination direction of the circumferential edge 6e of the carcass ply 6a or the inclination of the edge of the circumferential edge 8e of the inner liner rubber 8, It extends in the width direction of the former 21 with an angle α of 0 to 30 °, preferably 0 to 15 ° with respect to the tire axial direction.

  Further, in this example, as shown in FIG. 8, the thickness reducing layer 16 is composed of only an embedded portion 16A disposed in the concave portion 15, and the outer surface of the embedded portion 16A is substantially the same as the molding surface S. It is formed in one shape. That is, the depth of the concave portion 15 substantially matches the thickness TA of the embedded portion 16A (in this example, the thickness T of the thickness relaxing layer 16).

  As described above, the molding surface S of the former 21 is provided with the concave portion 15 that accommodates the thickness relaxing layer 16 made of the sponge material at a position facing the lap joint portion 12. Accordingly, as shown in FIGS. 9A and 9B, when the main body portion 11A (main body cover 9) is bulged, the thickness change in the lap joint portion 12 is caused by compressive deformation of the thickness relaxation layer 16. The outer surface of the lap joint portion 12, that is, the outer surface of the main body portion 11A (main body cover 9) at the position of the lap joint portion 12 can be flattened. Thereby, meandering of the band strip c1 can be suppressed and uniformity can be further improved.

  Therefore, the thickness relaxation layer 16 having a sponge hardness in the range of 50 to 300 N can be preferably used, and the thickness T of the thickness relaxation layer 16 is set. The inner liner rubber 8 is preferably in the range of 1.0 to 5.0 times the thickness t. If the sponge hardness is larger than 300N, it is too hard to sufficiently absorb the thickness change of the lap joint 12, and conversely if the sponge hardness is smaller than 50N, it becomes too soft. In K3, the tread component member 10 including the band ply 7A and the main body portion 11A (main body cover 9) tend to be insufficiently crimped. Accordingly, the lower limit value of the sponge hardness is preferably 100 N or more, more preferably 150 N or more, and more preferably 200 N or more, and the upper limit value is preferably 250 N or less. The sponge hardness was measured in accordance with Method A (Section 6.3) of the “Hardness” measurement method defined in Section 6 of “Soft urethane foam test method” of JIS K6400. Value.

  On the other hand, if the thickness T of the thickness relaxation layer 16 is smaller than 1.0 times the thickness t, the amount of compression is too small, and the thickness change of the lap joint 12 cannot be absorbed sufficiently. If it is larger than 5.0 times, the amount of compression becomes excessive, which tends to cause insufficient pressure bonding between the tread component 10 and the main body 11A (main body cover 9). Accordingly, the lower limit value of the thickness T is preferably 1.5 times or more, more preferably 2.0 times or more of the thickness t, and the upper limit value is preferably 4.0 times or less of the thickness t. Furthermore, 3.0 times or less is desirable. Even when the concave portion 15 is applied to the second lap joint portion 12B (the lap joint portion 12B of the carcass ply 6A), the thickness T of the thickness relaxing layer 16 can apply the above range.

  In the bulging step K2, as shown in FIG. 2, it is possible to increase the diameter of the former 21 after the predetermined distance between the bead cores 5 and 5 (corresponding to the distance between the bead cores in the raw tire). In order to increase the accuracy (for example, symmetry) of the protruding shape, it is preferable to bulge the main body cover 9 with a low internal pressure of, for example, about 100 kPa until the bead core 5 reaches a predetermined interval.

  In the tread forming step K3, the band ply 7A is formed by spirally winding the band strip c1 directly on the outer peripheral surface of the main body portion 11A (main body cover 9) in the bulging and holding state by the former 21. The tread component 10 includes a tread rubber 2G. As a method for forming the tread rubber 2G, for example, as shown in FIG. 2, a wide belt-like tread rubber member 2Ga is wound once in the circumferential direction, or a narrow thin tape-like rubber strip is spirally formed in the tire circumferential direction. A strip winding method of winding can be suitably employed.

  FIG. 11 shows another embodiment of the thickness relaxing layer 16. In the present embodiment, the thickness reducing layer 16 includes an embedded portion 16A disposed in the recessed portion 15 and a cover portion 16B that is integrated with the embedded portion 16A and covers the entire circumference of the molding surface S of the former 21. Formed from. Even in such a case, it is preferable that the total thickness T of the thickness relaxing layer 16 is in the range of 1.0 to 5.0 times the thickness t. The thickness TB of the cover portion 16B is preferably smaller than the thickness TA of the embedded portion 16A.

  As described above, the particularly preferred embodiment of the present invention has been described in detail. In the manufacturing method of the present invention, a belt cord is, for example, 10 ± 45 ° between the carcass ply 6A and the band ply 7A with respect to the tire circumferential direction. It is also possible to interpose a belt ply inclined at an angle of. Further, the present invention is not limited to motorcycle tires, and the present invention can be implemented in various forms such as being applicable to the manufacture of automobile tires.

  Using 20 former tires (tire sizes 190 / 50R17) for motorcycles using the formers with the specifications shown in Table 1, each of the van strips produced at that time was meandered and compared. The raw tire was vulcanized to form a product tire, and the uniformity of the product tire was measured and compared.

  For each tire, the inner liner rubber has a rubber thickness t of 1.8 mm, the seam width Wj of the lap joint is 8.0 mm, and the carcass ply has a ply thickness of 0.9 mm and its lap joint. The joint width Wj of the part is 3 mm, which is the same. In the former, a recess having a thickness relaxing layer is formed at the position of the lap joint of the inner liner rubber.

(1) Maximum meander amount:
The maximum value of the meandering amount in the tire axial direction generated when the band strip is spirally wound is measured for each tire, and is shown as an average value of 20 prototype tires.

(2) Uniformity:
Using a uniformity testing machine, lateral runout (LRO) was measured for each tire, and the average value of 20 prototype tires was shown. Measurement conditions were a rim (MT 6.00 × 17), an internal pressure (200 kPa), and a load (2.26 kPa).

  As shown in the table, it can be confirmed that the manufacturing method using the former according to the present invention can greatly reduce the amount of meandering of the band strip and can improve uniformity, such as reducing LRO.

It is sectional drawing which shows one Example of the pneumatic tire formed by the manufacturing method of this invention. It is a diagram which shows notionally one example of the manufacturing method of the present invention. It is a diagram explaining a main body cover formation process. (A), (B) is sectional drawing which expands and shows the 1st, 2nd lap joint part. It is sectional drawing which shows an example of a tire formation apparatus. It is sectional drawing which expands and shows a clamp ring. It is sectional drawing orthogonal to the axial direction explaining the diameter-expanded state and diameter-reduced state of a former. It is a fragmentary perspective view which shows a part of former | foamer with a recessed part and a thickness relaxation layer. (A), (B) is sectional drawing explaining the effect by a recessed part and a thickness relaxation layer. It is a conceptual diagram explaining the formation direction of a recessed part. It is a fragmentary sectional view showing other examples of a thickness relaxation layer. It is drawing explaining background art. (A), (B) is drawing explaining the problem.

Explanation of symbols

2 Tread portion 5 Bead core 6A Carcass ply 7A Band ply 8 Inner liner rubber 9 Main body cover 10 Tread component 11 Overlapping sheet body 11A Main body portion 12A First lap joint portion 12B Second lap joint portion 15 Recess 16 Thickness relaxation layer 16A Buried part 16B Cover part 21 Former c1 Band strip S Molding surface

Claims (6)

An inner liner rubber having a first lap joint portion that is wound around in the circumferential direction and whose circumferential ends are overlapped with each other, and a second lap that is wound around the outer side in the radial direction and is overlapped at the circumferential end. A step of forming a cylindrical body cover having a stacked sheet body including a carcass ply having a joint portion and a pair of bead cores for locking both sides of the main body portion of the stacked sheet body;
The step of causing the bead cores to approach each other and bulging the main body by expanding the diameter of a former whose diameter can be increased and decreased and whose outer peripheral surface forms a molding surface;
And a tread structure including a jointless band ply by spirally winding a tape-shaped band strip in the tire circumferential direction on the outer surface of the bulging-shaped main body in the bulging holding state by the former While providing the process of arranging the member and forming the tread portion,
The molding surface of the former is aligned with the first or second lap joint, and a recess extending in the width direction of the former and entering the lap joint is formed, and at least in the recess, a sponge material is formed. A method of manufacturing a green tire, comprising a thickness relaxing layer that absorbs the thickness and flattens the outer surface of the lap joint.   The method of manufacturing a pneumatic tire according to claim 1, wherein the thickness relaxation layer has a thickness T of 1.0 to 5.0 times the thickness of the inner liner rubber.   The method of manufacturing a pneumatic tire according to claim 1 or 2, wherein the thickness relaxation layer has a sponge hardness of 50 to 300N.   The said recessed part makes the strip | belt shape extended at an angle of 0-30 degrees with respect to a tire axial direction according to the inclination direction of the edge of the circumferential end of the said carcass ply or inner liner rubber. 4. The method for producing a pneumatic tire according to any one of 3 above.   The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, wherein the thickness relaxation layer is composed of only a buried portion disposed in the recess.   The thickness reducing layer includes an embedded portion disposed in the concave portion and a cover portion that is integrated with the embedded portion and covers the entire circumference of the molding surface of the former. 5. The method for producing a pneumatic tire according to any one of 4 above.

Images