JP6603566B2 - Pneumatic tire manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire.

  In general, a pneumatic tire is manufactured by molding a green tire on a molding drum and then setting the green tire in a mold and vulcanization molding. As a method for forming such a green tire, a ribbon winding method for forming a rubber member such as a tread rubber or a sidewall rubber by winding a belt-like ribbon rubber spirally along the tire circumferential direction is known (for example, (See Patent Documents 1 and 2).

  When forming the sidewall rubber by such a ribbon winding method, the ribbon rubber is generally wound in one direction in the tire radial direction because of a request for simplifying the control program of the winding device. That is, for example, as shown in FIG. 8, the ribbon rubber 100 starts to wind from the vicinity of the shoulder portion of the tread rubber 102 and ends by winding sequentially toward the bead portion 104 on the inner side in the tire radial direction. On the contrary, the winding is started from the bead portion side, wound sequentially toward the outer side in the tire radial direction, and terminated near the shoulder portion of the tread rubber.

JP 2014-512992 A JP 2004-338626 A

  However, it has been found that such a winding method causes an air reservoir 110 at the stepped portion 108 between the end portion 102A of the tread rubber 102 and the case main body 106 (see FIG. 8), causing an appearance defect. That is, between the case main body 106 including the toroidal carcass ply and the end portion 102A of the tread rubber 102 attached to the outer peripheral surface of the crown portion, a concave stepped portion 108 due to the thickness of the end portion 102A is formed. It is formed. If the ribbon rubber 100 is wound around in one direction in order to form a side wall rubber with respect to the one having such a stepped portion 108, the stepped portion 108 may be entrapped and air may be easily entrapped. is there.

  In the embodiment of the present invention, in view of the above points, when the side wall rubber is formed by wrapping the ribbon rubber, the air that can suppress the occurrence of air accumulation at the step portion between the end portion of the tread rubber and the case main body. It aims at the manufacturing method of a entering tire.

  A method for manufacturing a pneumatic tire according to an embodiment of the present invention uses a tire case including a case main body including a toroidal carcass ply and a tread rubber provided on the outer periphery of the crown portion of the case main body. It includes a sidewall molding process in which at least a part of the sidewall rubber is molded by winding ribbon rubber around the side portion of the tire case. The sidewall molding step is a step of forming a first wound body by winding a ribbon rubber so as to cross over the boundary from the boundary between the end portion of the tread rubber and the step portion of the case body. And a step of forming a second wound body by winding a ribbon rubber around the outside of the first wound body.

  According to the present embodiment, by setting the starting point when winding the ribbon rubber as described above, it is possible to suppress the occurrence of air accumulation at the step portion between the end portion of the tread rubber and the case body.

1 is a half sectional view of a pneumatic tire according to an embodiment. 1 is a half cross-sectional view of a tire case according to a first embodiment. It is sectional drawing in the middle of winding of the ribbon rubber which concerns on 1st Embodiment. It is sectional drawing which shows the winding structure of the ribbon rubber which concerns on 1st Embodiment. It is a semi-sectional view of a tire case according to a second embodiment. It is sectional drawing in the middle of winding of the ribbon rubber which concerns on 2nd Embodiment. It is sectional drawing which shows the winding structure of the ribbon rubber which concerns on 2nd Embodiment. It is sectional drawing which shows the winding structure of the ribbon rubber of a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a half sectional view of a pneumatic tire 10 according to an embodiment. The tire 10 includes a pair of left and right bead portions 12, a pair of left and right sidewall portions 14 that extend outward from the bead portion 12 in the tire radial direction, and a tread portion 16 that connects the outer peripheral ends of the sidewall portions 14. In the present embodiment, since the tire 10 is bilaterally symmetric, only the right half is shown in the figure. In the figure, CL indicates the tire equator plane. In the present specification, the tire width direction is a direction parallel to the tire rotation axis, and is indicated by a symbol W in the drawing. Further, the tire radial direction is a direction perpendicular to the tire rotation axis, and is indicated by a symbol R in the figure. The tire circumferential direction is a circumferential direction around the tire rotation axis.

  In the pneumatic tire 10, a toroid-like carcass ply 18 is embedded between a pair of bead portions 12. The carcass ply 18 is composed of at least one ply formed by coating a carcass cord with rubber, reaches the bead portion 12 from the tread portion 16 through the side wall portions 14 on both sides, and is wound around the bead core 20 in the bead portion 12. Is locked. A belt 22 is disposed on the outer peripheral side of the carcass ply 18 in the tread portion 16, and a belt reinforcing layer 23 is provided on the outer periphery of the belt 22. A tread rubber 24 constituting a contact surface is provided on the outer side of the belt 22 in the tire radial direction. A sidewall rubber 26 is provided on the tire outer surface side of the sidewall portion 14. Reference numeral 28 denotes a side protector portion provided at a boundary portion between the sidewall portion 14 and the bead portion 12. Reference numeral 30 denotes an inner liner provided on the tire inner surface side of the carcass ply 18.

  The pneumatic tire 10 has a so-called SWOT structure. That is, the pneumatic tire 10 has a structure in which the outer end portion in the tire radial direction of the sidewall rubber 26 is covered on the outer side of the end portion 24A of the tread rubber 24.

  Next, a method for manufacturing the pneumatic tire 10 according to the first embodiment will be described. In the present embodiment, except for the points related to the sidewall rubber 26, the tire can be manufactured in the same manner as the conventional tire manufacturing process. Therefore, the molding process (sidewall molding process) of the sidewall rubber 26 will be mainly described.

  As shown in FIG. 2, in the sidewall molding process, at least a part of the sidewall rubber 26 is wound by winding the ribbon rubber 42 around the side portion of the tire case 40 using the tire case 40 along the tire circumferential direction. Mold. In this embodiment, the entire sidewall rubber 26 is formed by winding the ribbon rubber 42.

  The tire case 40 includes a case main body 44 including a toroidal carcass ply 18 and a tread rubber 24 provided on the outer periphery of the crown portion of the case main body 44. More specifically, the case main body 44 includes a pair of left and right annular bead cores 20, a toroidal carcass ply 18 that is locked by folding both end portions of the pair of bead cores 20, and an inner surface of the case main body 44. And an rim strip rubber 32 provided in the bead portion. A belt 22 and a belt reinforcing layer 23 are provided on the inner peripheral side of the tread rubber 24, and a tread ring 46 including the tread rubber 24 and the belt 22 is bonded and integrated to the outer peripheral surface of the crown portion of the case main body 44. Yes.

  The tire case 40 is held on the outer periphery of the forming drum 80. The forming drum 80 is a shaping drum for forming a green tire (also referred to as a green tire).

  As a method for forming the tire case 40, various known methods can be employed. For example, an inner liner and a carcass ply are formed in a cylindrical shape on the outer peripheral surface of a molding drum, and after inserting bead cores on both sides in the width direction, the ends of the carcass ply are folded back so as to wrap the bead cores. Make the body. On the other hand, a tread ring forming drum is used to wind a belt and a belt reinforcing layer around the outer periphery, and then a tread rubber is formed around the outer periphery to obtain a tread ring. For forming the tread rubber, for example, a ribbon winding method in which a belt-like ribbon rubber is wound a plurality of times spirally along the tire circumferential direction can be used. With the tread ring arranged on the outer peripheral side of the cylindrical case main body, the case main body is inflated and deformed in a toroidal shape in the tire radial direction using, for example, a bladder or the like, and the outer peripheral surface of the tread ring is Adhere to the inner surface. Thereby, a tire case 40 as shown in FIG. 2 is formed.

  The side wall rubber 26 is formed by winding the ribbon rubber 42 which is an unvulcanized belt-like rubber around the side portion of the tire case 40 thus obtained. The dimensions of the ribbon rubber 42 are not particularly limited. For example, the width may be 15 to 35 mm, the thickness (the thickness at the maximum thickness portion) may be 1.0 to 3.0 mm, the width may be 20 to 25 mm, and the thickness may be 2. It may be 0 to 3.0 mm.

  The cross-sectional shape of the ribbon rubber 42 is not particularly limited. However, the ribbon rubber 42 has a flat cross-sectional shape in which the thickness gradually decreases toward both ends in the width direction (for example, by having an apex angle in the center portion 42A in the width direction as shown in FIG. 2). It is preferable to have a triangular shape having a maximum thickness in the central portion 42A. The ribbon rubber 42 having such a cross-sectional shape is deformed and wound so as to conform to the cross-sectional shape of the portion to be wound as shown in FIGS.

  In the sidewall molding process according to the first embodiment, the ribbon rubber 42 is wound around the boundary 50 starting from the boundary 50 between the end 24A of the tread rubber 24 and the stepped portion 48 of the case body 44. Thus, the first wound body 52 is formed as shown in FIG. 3, and then the ribbon rubber 42 is wound around the outside of the first wound body 52, whereby the second wound body 54 is wound as shown in FIG. Form.

  More specifically, first, the end of the tread rubber 24 is wound by winding the ribbon rubber 42 a plurality of times from the boundary 50 between the end portion 24A of the tread rubber 24 and the case main body 44 toward the outer side Ro in the tire radial direction. The first wound body 52 is formed so as to cover the portion 24A.

  Here, as shown in FIG. 2, the step portion 48 is formed between the case main body 44 and the end portion 24A of the tread rubber 24 attached to the outer peripheral surface of the crown portion, and the thickness of the end portion 24A. It is a concave step portion resulting from the above. In this example, it is formed between the end 24 </ b> A of the tread rubber 24 and the carcass ply 18.

  In the present embodiment, the ribbon rubber 42 starts to be wound so as to straddle the boundary 50 between the tread rubber 24 and the case main body 44 in the stepped portion 48, that is, on both sides of the boundary 50. At the start of winding, as shown in FIG. 2, it is preferable to start winding the ribbon rubber 42 having a flat cross-sectional shape with the center portion 42A in the width direction and the boundary 50 aligned. Moreover, it is preferable to wind the 1st round 42-1 of the winding start in parallel with the boundary 50 (parallel winding). That is, it is preferable that the first round 42-1 is wound around the entire circumference in a state where the center 42A in the width direction of the ribbon rubber 42 is aligned with the boundary 50.

  The ribbon rubber 42 is wound from the boundary 50 toward the tire radial direction outer side Ro to the vicinity of the shoulder portion of the tread rubber 24. At this time, the ribbon rubber 42 is spirally fed or pitch-fed at every turn while having an overlapping portion for each turn. Can be wound. Here, the spiral winding is performed by continuously changing the winding position of the ribbon rubber 42 as the molding drum 80 rotates. Further, the pitch feed winding is performed by shifting the winding position by one pitch at a predetermined position on the circumference every time the forming drum 80 is rotated once while the ribbon rubber 42 is wound in parallel.

  After forming the first wound body 52 as shown in FIG. 3 in this way, the ribbon rubber 42 is folded without being cut, and this time, by winding the ribbon rubber 42 a plurality of times toward the tire radial inner side Ri, As shown in FIG. 4, a second wound body 54 is formed. The second wound body 54 is formed by winding the ribbon rubber 42 so as to overlap the outer side of the first wound body 52, that is, the outer side Wo in the tire width direction. Further, the ribbon rubber 42 is wound until it exceeds at least the boundary 50 after being folded. In this example, the ribbon rubber 42 is wound up to a position (a position corresponding to the side protector portion 28) that crosses the boundary 50 and further joins to the rim strip rubber 32 on the inner side Ri in the tire radial direction, and terminates there.

  Note that the winding pitch of the ribbon rubber 42 can be appropriately set according to the thickness of the sidewall rubber 26 and the like. For example, in the example shown in FIG. 4, the winding pitch is set larger in the portion where the first winding body 52 and the second winding body 54 overlap in the tire radial direction outer side Ro than the boundary 50. The winding pitch is set smaller in the radial inner Ri portion than in the tire radial outer Ro portion.

  Thereby, the sidewall rubber 26 is molded in the tire case 40. Although not shown, the sidewall portion on the opposite side in the tire width direction W is formed in the same manner. The green tire 56 shown in FIG. 4 formed in this way is set in a mold that is a vulcanization mold and vulcanized and molded in accordance with a conventional method to obtain a pneumatic tire.

  In the first embodiment configured as described above, the air at the stepped portion 48 starts by winding the ribbon rubber 42 so as to straddle the boundary 50 between the end portion 24A of the tread rubber 24 and the stepped portion 48 of the case main body 44. Can be prevented and the occurrence of air pockets can be suppressed.

  In the first embodiment, the ribbon rubber 42 having a flat cross-sectional shape whose thickness decreases toward both ends in the width direction is wound with the center portion 42A in the width direction and the boundary 50 of the stepped portion 48 aligned. By starting and winding the first round 42-1 at the beginning of winding in parallel with the boundary 50, the following operational effects can be obtained. That is, in the first round 42-1 at the start of winding, the boundary 50 can be covered over the entire circumference by the thickest central portion 42A of the ribbon rubber 42, so that the air accumulation generated in the stepped portion 48 can be more effectively suppressed. it can.

  In the first embodiment, after the ribbon rubber 42 is wound from the boundary 50 of the stepped portion 48 toward the tire radial outer side Ro to form the first wound body 52, the ribbon rubber 42 is folded without being cut. Since the second rubber 54 is formed by winding the ribbon rubber 42 a plurality of times toward the inner side Ri in the tire radial direction and at least beyond the boundary 50, the following effects can be obtained. That is, it is possible to suppress air accumulation generated in the stepped portion 48 while ensuring a sufficient thickness of the sidewall rubber 26.

  In the first embodiment, the winding is first performed from the boundary 50 toward the tire radial direction outer side Ro, and then wound toward the tire radial direction inner side Ri after turning back, but may be wound in the opposite direction. . That is, in this embodiment, the ribbon rubber 42 is wound a plurality of times from the boundary 50 toward the outer side Ro or the inner side Ri in the tire radial direction R to form the first wound body 52, and then the ribbon rubber 42 is cut. The second wound body 54 may be formed by folding the ribbon rubber 42 a plurality of times toward the other side in the tire radial direction R without folding.

  5-7 shows the manufacturing process which concerns on 2nd Embodiment, and is the example which wound the ribbon rubber 42 in the reverse direction to 1st Embodiment.

  As shown in FIG. 5, in the tire case 40 </ b> A according to the second embodiment, a part of the sidewall rubber 26 is formed in advance on the side portion of the case main body 44. That is, the case main body 44 is adjacent to the bead core 20, the carcass ply 18, the inner liner 30, the rim strip 32, and the outer side in the tire radial direction Ro of the rim strip 32. And a rubber member 26A constituting the portion. Therefore, in the second embodiment, the outer peripheral side portion of the sidewall rubber 26 is formed by winding the ribbon rubber 42.

  In the sidewall molding process according to the second embodiment, first, the ribbon rubber 42 is wound a plurality of times from the boundary 50 between the end portion 24A of the tread rubber 24 and the case main body 44 toward the inner side Ri in the tire radial direction. Attached body 52A is formed (see FIG. 6). In this example, as described above, the rubber member 26A that forms a part of the side wall rubber 26 is provided in advance on the side portion of the case main body 44. Therefore, the ribbon rubber 42 is wound around the rubber member 26A. A one-roll body 52A is formed.

  Thereafter, the ribbon rubber 42 is folded without being cut, and the ribbon rubber 42 is wound a plurality of times toward the tire radial outer side Ro and at least beyond the boundary 50 to form the second wound body 54A (FIG. 7). reference). The second wound body 54A is formed by winding the ribbon rubber 42 so as to overlap the outer side of the first wound body 52A, that is, the outer side Wo in the tire width direction. In this example, the ribbon rubber 42 covers the end portion 24A of the tread rubber 24 from the boundary 50 toward the tire radial direction outer side Ro, is wound to the vicinity of the shoulder portion, and terminates there.

  As described above, in the second embodiment, the ribbon rubber 42 is wound in the direction opposite to that of the first embodiment. In this case, the sufficient thickness of the sidewall rubber 26 is ensured as in the first embodiment. In addition, air accumulation generated in the stepped portion 48 can be suppressed. About 2nd Embodiment, about another structure and an effect, it is the same as that of 1st Embodiment fundamentally, and description is abbreviate | omitted.

  In the second embodiment, the case main body 44 is provided with the rubber member 26A that constitutes a part of the sidewall rubber 26 in advance. However, as in the first embodiment, such a rubber member 26A is not provided, The entire wall rubber 26 may be formed by winding the ribbon rubber 42. That is, the first wound body 52A winds the ribbon rubber 42 until it reaches a rubber member (for example, the rim strip rubber 32 or the rubber member 26A described above) that forms a tire outer surface provided in advance on the side portion of the tire case 40. May be formed. Further, in the first embodiment, a rubber member 26A that constitutes a part of the sidewall rubber 26 as in the second embodiment may be provided in advance, and in this case, the second wound body 54 is the rubber member. It may be formed up to 26A. That is, in the first embodiment, the second wound body may be formed by wrapping ribbon rubber until reaching the rubber member that forms the tire outer surface provided in advance on the side portion of the tire case.

  In the above embodiment, the first and second wound bodies are formed by folding the ribbon rubber only once, but the outer side of the second wound body is folded two or more times. A further wound body may be formed.

  In the above embodiment, the first wound body and the second wound body are formed by folding one ribbon rubber without cutting, but the first wound body and the second wound body are formed. You may form using another ribbon rubber. In that case, the ribbon rubber of the first and second wound bodies may be the same or different. Moreover, when winding another ribbon rubber, the second wound body may be formed after forming the first wound body, but for shortening the process time, while forming the first wound body, You may form a 2nd winding body. That is, if the first winding body is formed using the boundary at the stepped portion as the starting point of winding, and the second winding body is formed outside the first winding body, for example, The winding of the second winding body may be started before the winding is completed, and the winding of the first winding body and the winding of the second winding body may be started simultaneously.

  In order to confirm the effect of the present embodiment, the ribbon rubber 100 starts to be wound from the vicinity of the shoulder portion of the tread rubber 102 as shown in FIG. Pneumatic tires were vulcanized with respect to those wound sequentially. As a result, in the comparative example, an air pocket was present at the boundary between the tread rubber and the sidewall rubber of the tire after vulcanization molding, whereas the method of the first embodiment and the second embodiment was used. In the vulcanized tire, there was no air accumulation at the boundary between the tread rubber and the sidewall rubber.

  The above embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

10 ... Pneumatic tire, 18 ... Carcass ply, 24 ... Tread rubber, 24A ... End,
26 ... sidewall rubber, 26A ... rubber member, 40, 40A ... tire case,
42 ... Ribbon rubber, 42A ... Center in the width direction, 42-1 ... First round of winding,
44 ... Case body, 48 ... Step portion, 50 ... Boundary, 52, 52A ... Attached body with first winding,
54, 54A ... 2nd volume

Claims (5)

Using a tire case comprising a case main body including a toroidal carcass ply and a tread rubber provided on the outer periphery of the crown portion of the case main body, by winding ribbon rubber around the side portion of the tire case, Including a sidewall molding step of molding at least a part,
The sidewall molding process includes
Forming a first wound body by wrapping a ribbon rubber so as to straddle the boundary between the end portion of the tread rubber and the step portion of the case body as a starting point;
Forming a second wound body by winding a ribbon rubber around the outside of the first wound body,
A method of manufacturing a pneumatic tire.   The ribbon rubber having a flat cross-sectional shape whose thickness decreases toward both ends in the width direction starts to be wound with the width direction center portion of the ribbon rubber and the boundary aligned with each other, and the first round of winding starts at the boundary. The manufacturing method of Claim 1 wound in parallel.   The ribbon rubber is wound a plurality of times from the boundary toward the outer side or the inner side in the tire radial direction to form the first wound body, and then the ribbon rubber is folded back without being cut to the other side in the tire radial direction. The manufacturing method according to claim 1 or 2, wherein the second rubber body is formed by winding the ribbon rubber a plurality of times toward the surface.   By winding the ribbon rubber a plurality of times from the boundary toward the outer side in the tire radial direction, the first wound body is formed so as to cover the end portion of the tread rubber, and then the ribbon rubber is folded back without cutting. The manufacturing method according to claim 3, wherein the second wound body is formed by winding the ribbon rubber a plurality of times toward a radially inner side and at least exceeding the boundary.   After forming the first wound body up to a rubber member forming a tire outer surface provided in advance on the side portion of the tire case by winding the ribbon rubber a plurality of times from the boundary toward the inside in the tire radial direction The manufacturing method according to claim 3, wherein the ribbon rubber is folded without being cut and wound around the outer side in the tire radial direction and at least beyond the boundary to wind the ribbon rubber a plurality of times to form the second wound body.

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