JP2019104111A - Production method of pneumatic tire - Google Patents

Abstract

To discharge efficiently, air interposed between a side wall rubber and a carcass ply while minimizing stitching steps.SOLUTION: A side wall molding step for sticking a sheet-state side wall rubber 26 to a tire case 40 in which a tread rubber 24 is provided on a periphery of a case body on which a carcass ply 18 is folded in the surrounding of a bead part 12, for molding a side wall part 14, comprises a first step for providing a plurality of recess grooves 34 on one surface 32 of a side wall rubber 26, a second step for directing the plurality of recess grooves 34 to a folding part 18A of the carcass ply 18 provided on the tire case 40, and sticking the side wall rubber 26 to the tire case 40 so that an angle of the recess grooves 34 to a ply cord 17 provided on the carcass ply 18 is 10° or smaller.SELECTED DRAWING: Figure 2

Description

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

  In general, a pneumatic tire is an unvulcanized green tire formed by bonding a plurality of tire constituent members such as tread rubber, sidewall rubber, carcass ply, bead, bead filler, belt ply and the like on a forming drum. It is manufactured by vulcanizing and molding in a tire mold. The plurality of tire constituent members constituting the green tire each have a predetermined thickness, and therefore, when the plurality of tire constituent members are pasted together, a step is easily generated at the end of each member, Air stagnation is likely to occur between the tire component members due to the parts.

  Conventionally, in order to eliminate air accumulation between the carcass ply and the sidewall rubber, the air outlet groove is formed in the sidewall rubber and stitching (rollering) is performed to pass air through the air outlet groove. It is carried out that it pushes out from a reservoir to the exterior (for example, refer to patent documents 1).

  However, according to Patent Document 1, in order to discharge the air between the carcass ply and the sidewall rubber to the outside, it is necessary to stitch the entire sidewall rubber, so that the manufacturing cycle time becomes long or the sidewall rubber The thickness distribution is likely to vary from tire to tire.

JP, 2016-93935, A

  The present invention has been made in view of the above-mentioned circumstances, and it is possible to manufacture a pneumatic tire capable of efficiently discharging the air present between the sidewall rubber and the carcass ply while reducing the stitching process as much as possible. Intended to provide a method.

  In the method of manufacturing a pneumatic tire according to the present invention, a sheet-like sidewall is formed on a tire case in which a tread rubber is provided on an outer peripheral surface of a case body in which a carcass ply is folded back around a bead portion having a bead core and a bead filler. In a method of manufacturing a pneumatic tire including a sidewall forming step of attaching a rubber and forming a sidewall portion, the sidewall forming step includes a first step of providing a plurality of recessed grooves on one surface of the sidewall rubber; The side wall is directed to a plurality of the recessed grooves toward the turn-back portion of the carcass ply provided in the tire case, and the angle of the recessed groove with respect to the ply cord provided in the carcass ply is 10 ° or less And d) bonding the rubber to the tire case.

  In a preferred embodiment of the present invention, after the second step, the sidewall rubber may be vulcanized and molded in a tire vulcanizing mold without being pressed against the tire case with a stitching tool.

  In another preferred aspect of the present invention, the sidewall forming step includes, after the second step, a third step of pressing a predetermined region including the radially outer end of the sidewall rubber against the tire case with a stitching tool. You may

  In another preferred aspect of the present invention, the sidewall forming step includes, after the second step, pressing at least a part of the bead filler in the tire width direction outside of the sidewall rubber against the tire case with a stitching tool. It may have four steps.

  In another preferred aspect of the present invention, the depth of the recessed groove may be 1/3 or more and 2/3 or less of the thickness of the sidewall rubber.

  According to the present invention, the air present between the sidewall rubber and the carcass ply can be efficiently discharged while reducing the stitching process as much as possible.

1 is a half sectional view of a pneumatic tire according to an embodiment of the present invention. The half section view of the pneumatic tire showing the 2nd process of a sidewall formation process. The figure which looked at the carcass ply of the pneumatic tire of FIG. 1, sidewall rubber, and tread rubber from the tire side.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a half cross-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 extending outward from the bead portion 12 in the tire radial direction, and a tread portion 16 connecting outer peripheral ends of the sidewall portions 14. In the present embodiment, since the pneumatic tire 10 is symmetrical, only the right half is shown in the figure. CL shows a tire equatorial plane in the figure. In the present specification, the tire width direction is a direction parallel to the tire rotation axis and is indicated by symbol W in the drawing, and the inside and the outside of the tire width direction are indicated by symbols W1 and W2, respectively. The tire radial direction is a direction perpendicular to the tire rotation axis, and is indicated by reference numeral R in the drawing, and the inner and outer sides of the tire radial direction are indicated by reference numerals R1 and R2, respectively. Moreover, a tire circumferential direction is a direction on the circumference centering on a tire rotation axis.

  In the bead portion 12, an annular bead member 20 in which a bead core 21 obtained by rubber-covering a convergent body such as a steel wire and a hard rubber bead filler 22 having a substantially triangular cross section are embedded. ing.

  Inside the tire, at least one toroidal carcass ply 18 bridged between a pair of bead portions 12 is embedded, and in this example, there is one carcass ply 18.

  The carcass ply 18 includes a plurality of ply cords 17 extending along a radial direction (direction substantially orthogonal to the tire circumferential direction) provided at intervals in the tire circumferential direction, and a topping rubber covering the ply cords 17 (See Figure 3). For the ply cord 17, organic fibers such as polyester, rayon, nylon, or aramid, and metals such as steel are preferably used.

  The carcass ply 18 passes from the tread portion 16 to the bead portion 12 through the sidewall portion 14 and both ends of the carcass ply 18 in the bead portion 12 are folded back around the bead member 20 from the inner side W1 to the outer side W2 in the tire width direction. The folded back portion 18A is formed in FIG. A rubber chafer 19 is provided on the outside of the carcass ply 18 so as to wrap around the bead portion 12.

  A belt 23 is disposed on the outer peripheral side of the carcass ply 18 in the tread portion 16, and a belt reinforcing layer 25 is provided on the outer periphery of the belt 23. A tread rubber 24 constituting a contact surface is provided on the tire radial direction outer side R2 of the belt 23.

  On the tire outer surface side of the sidewall portion 14, a sidewall rubber 26 is provided so as to overlap the folded portion 18 </ b> A of the carcass ply 18. The sidewall rubber 26 extends from the vicinity of the bead core 21 outward in the tire radial direction Y 2 so as to straddle the bead portion 12 to the tread rubber 24, and the tire radial direction outer end 26 A of the sidewall rubber 26 corresponds to the tread rubber 24. Overlap the end 24A of the tire (on the tire outer surface side). That is, the pneumatic tire 10 of the present embodiment has a sidewall on tread (SWOT) structure.

  In addition, the code | symbol 28 shows the side protector part provided in the boundary part of the sidewall part 14 and the bead part 12. As shown in FIG. The code | symbol 30 shows the inner liner provided in the tire inner surface side of the carcass ply 18.

  The sidewall rubber 26 has a plurality of air discharge grooves 34 extending in the radial direction formed in the inner surface 32 in the tire width direction W (that is, the surface facing the folded portion 18A of the carcass ply 18). As shown in FIG. 3, preferably, a plurality of air discharge grooves 34 are provided in the turnback portion 18A such that the angle with respect to the ply cord 17 provided in the turnback portion 18A of the carcass ply 18 is 10 ° or less. Side wall rubbers 26 are superimposed on the folded back portions 18A of the carcass ply 18 so as not to cross the ply cords 17.

  Next, a method of manufacturing the pneumatic tire 10 according to the first embodiment will be described.

  First, the unvulcanized inner liner 30, the rubber chafer 19 and the carcass ply 18 are overlapped on the outer periphery of a forming drum (not shown) and cylindrically wound, and the bead members 20 are arranged at both ends of the carcass ply 18 Both ends of the ply 18 are bent so as to wrap the bead member 20 to form a cylindrical case body. Further, the belt 23 and the tread rubber 24 are sequentially stacked on another molding drum to form a cylindrical belt tread assembly.

  Next, the inner peripheral surface of the cylindrical belt tread assembly is bonded and integrated to the outer peripheral surface of the case main body expanded in a toroidal shape by the shaping drum to form a tire case 40. Then, a sidewall molding process is performed in which sidewall rubber 26 is provided to the obtained tire case 40.

In the side wall forming step, as a first step, the sheet-like side wall rubber 26 is formed, and a plurality of air discharge grooves 34 extending in parallel to one another are provided on one surface of the side wall rubber 26. Such an air discharge concave groove 34 can be formed by pressing one surface of the sidewall rubber 26 molded into a sheet shape against a groove roller in which the concave and convex grooves are formed.
The depth of the air discharge groove 34 provided in the sidewall rubber 26 in the first step is preferably 1/3 or more and 2/3 or less of the thickness of the sidewall rubber 26. As an example of the dimensions of the sidewall rubber 26 and the air discharge groove 34, the thickness of the sidewall rubber 26 is 3 to 6 mm, the depth of the air discharge groove 34 is 2 to 3 mm, and the distance between the air discharge grooves 34 The distance between the center positions of the bottoms of the adjacent air discharge grooves 34 can be 4 to 6 mm.

  Then, one surface of the sidewall rubber 26 provided with the plurality of air discharge recessed grooves 34 is directed to the turn-back portion 18A of the carcass ply 18 provided in the tire case, and air for the ply cord 17 provided in the turn-back portion 18A. A second step of bonding the sidewall rubber 26 to the tire case 40 is performed so that the angle of the discharge groove 34 is 10 ° or less (see FIG. 2). Thus, an unvulcanized green tire (green tire) is formed.

  The unvulcanized green tire thus obtained is set in a mold which is a vulcanized mold in accordance with a conventional method, and a pneumatic tire can be obtained by vulcanization molding.

  In the present embodiment, an air discharge concave groove 34 extending substantially parallel to the ply cord 17 provided on the carcass ply 18 is formed on the inner side surface 32 of the sidewall rubber 26 opposed to the turnback portion 18A of the carcass ply 18. A flow path for leading the air present between the carcass ply 18 and the sidewall rubber 26 to the outside is secured.

  Therefore, after the second step, the air present between the carcass ply 18 and the sidewall rubber 26 can be discharged into the air by setting it in a mold and performing vulcanization molding without performing stitching on the sidewall rubber 26. It can be discharged from the groove 34 to the outside. That is, even if the green tire is pressurized in the initial stage of vulcanization molding, the air discharge concave groove 34 is less likely to be crushed by the ply cord 17 provided substantially parallel to the air discharge concave groove 34, and the carcass ply 18 and the sidewall Air present between the rubber and the rubber can be discharged to the outside. Therefore, in the present embodiment, the air present between the sidewall rubber 26 and the carcass ply 18 can be efficiently discharged while reducing the stitching process as much as possible.

  Moreover, since the side wall rubber 26 is not stitched after the second step, the side wall rubber 26 can be provided to the tire case 40 while maintaining a desired thickness distribution.

  Further, in the present embodiment, by setting the depth of the air discharge concave groove 34 to 1/3 or more of the thickness of the sidewall rubber 26, a flow path having a sufficient opening area with the carcass ply 18 is formed. Thus, the air present between the carcass ply 18 and the sidewall rubber 26 can be discharged to the outside. Further, by setting the depth of the air discharge concave groove 34 to 2/3 or less of the thickness of the sidewall rubber 26, it is possible to prevent the sidewall rubber 26 from becoming thin locally.

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

(Modification example)
In the embodiment described above, the first step and the second step are performed as the sidewall forming step of providing the sidewall rubber 26 to the tire case 40, and thereafter, the sidewall rubber 26 is vulcanized with a mold without stitching. Although the case where it shape | molds was demonstrated, after the 2nd process, you may perform any one of the 3rd process and 4th process mentioned later, and may perform both the 3rd process and the 4th process.

  In the third step, a region including the tire radial direction outer end 26A of the sidewall rubber 26, that is, a region extending with a substantially constant width in the tire radial direction from the tire radial direction outer end 26A (for example, the tire radial direction outer end 26A This is a step of pressing the tire case 40 with the stitching tool) by using a stitching tool as a center).

  In the fourth step, at least a portion of the portion of the sidewall rubber 26 located on the tire width direction outer side W2 of the bead filler 22 (for example, the side protector portion 28 provided at the boundary portion between the sidewall portion 14 and the bead portion 12) (A region including the above) is pressed onto the tire case 40 with a stitching tool.

  By performing the third step after the second step, although the predetermined region including the tire radial direction outer end 26A of the sidewall rubber 26 is stitched, the sidewall rubber 26 is not stitched overall, but the sidewall rubber It is possible to discharge the air present between the side wall 26 and the carcass ply 18 and efficiently discharge the air present between the sidewall rubber 26 and the carcass ply 18 while reducing the stitching process as much as possible. it can.

  Also, a mold release agent may be applied to the inner surface of the mold for molding the tire, but by performing the third step after the second step, the tire radial direction outer end 26A of the sidewall rubber 26 and the end of the tread rubber 24 It is possible to suppress molding defects due to the mold release agent entering between 24A.

  By performing the fourth step after the second step, although the portion of the bead filler 22 located on the tire width direction outer side W2 is stitched, the sidewall rubber 26 and the sidewall rubber 26 are not stitched together. The air present between the sidewall ply 18 and the carcass ply 18 can be discharged, and the air present between the sidewall rubber 26 and the carcass ply 18 can be efficiently discharged while reducing the stitching process as much as possible.

  When the side protector portion 28 is formed at the boundary between the sidewall portion 14 and the bead portion 12, the sidewall rubber 26 may become thick near the side protector portion 28 and air may not be easily discharged. By performing the fourth step after the two steps, air present between the sidewall rubber 26 and the carcass ply 18 in the vicinity of the side protector portion 28 can be reliably discharged to the outside.

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

DESCRIPTION OF SYMBOLS 10 ... Pneumatic tire, 12 ... bead part, 14 ... sidewall part, 16 ... tread part, 17 ... ply cord, 18 ... carcass ply, 18A ... return part, 20 ... bead member, 23 ... belt, 24 ... tread rubber , 25: belt reinforcement layer, 26: sidewall rubber, 28: side protector portion, 34: air discharge groove, 40: tire case

Claims (5)

A sheet-like sidewall rubber is attached to a tire case in which a tread rubber is provided on an outer peripheral surface of a case main body in which a carcass ply is folded back around a bead portion having a bead core and a bead filler to form a sidewall portion In a method of manufacturing a pneumatic tire including a sidewall forming process,
The sidewall forming step is a first step of providing a plurality of recessed grooves on one surface of the sidewall rubber, and a plurality of the recessed grooves directed to a turn-back portion of the carcass ply provided on the tire case. And a second step of applying the sidewall rubber to the tire case such that the angle of the recessed groove with respect to the ply cord provided in the ply is 10 ° or less.   The method for manufacturing a pneumatic tire according to claim 1, wherein after the second step, the sidewall rubber is vulcanized and molded in a tire vulcanizing mold without pressing the sidewall rubber against the tire case with a stitching tool.   The pneumatic tire according to claim 1, wherein the sidewall forming step has a third step of pressing a predetermined region including the radially outer end of the sidewall rubber against the tire case with the stitching tool after the second step. Manufacturing method.   The sidewall forming step has a fourth step of pressing at least a part of a portion of the bead filler located on the outer side in the tire width direction of the sidewall rubber against the tire case with the stitching tool after the second step. The manufacturing method of the pneumatic tire as described in claim 1 or 3.   The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, wherein a depth of the recessed groove is 1/3 or more and 2/3 or less of a thickness of the sidewall rubber.

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