JP2017109444A - Method for production of pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of air accumulation near a tread rubber end part or bead part when forming a sidewall rubber by winding a ribbon rubber.SOLUTION: A method for production of a pneumatic tire includes: forming a belt lower pad 30 and an inside rubber layer 34 of a sidewall rubber 32 at the outer peripheral side of a cylindrical carcass ply 22; and forming an outside rubber layer 36 by winding a ribbon rubber 48 plural times outside the inside rubber layer 34 after joining the carcass ply 22 in a toroidal shape to a tread ring 44; terminating the inside rubber layer 34 by overlapping the upper end 34A thereof with the belt lower pad 30 so that the lower end 34BE thereof exceeding the tread rubber end 28A positions at intervals from the upper end 20A of a bead filler. The outside rubber layer 36 is formed by overlapping the upper end 36A thereof with the tread rubber end 28A so that the end 28A is held between the outside and inside rubber layers 36 and 34.SELECTED DRAWING: Figure 6

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, Patent Document 1).

  On the other hand, various configurations have conventionally been proposed for the sidewall rubber of pneumatic tires. For example, as shown in Patent Documents 2 and 3, the sidewall rubber is divided into an inner rubber layer and an outer rubber layer in the tire width direction. There are also known two-layer structures.

JP 2007-069409 A Japanese Patent Application Laid-Open No. 2015-089720 JP 2007-196988 A

  By the way, when forming the sidewall rubber by the ribbon winding method, an air pocket may be generated at the step portion between the end portion of the tread rubber and the carcass ply, which may cause a problem in appearance. For example, in the tire shown in FIG. 7, a concave stepped portion due to the thickness of the end portion 102A is provided between the toroidal carcass ply 100 and the end portion 102A of the tread rubber 102 attached to the outer peripheral surface of the crown portion. 104. In order to form the sidewall rubber 106 on the one having such a stepped portion 104, for example, ribbon rubber is started from the vicinity of the shoulder portion of the tread rubber 102 and sequentially wound toward the bead portion 108 on the inner side in the tire radial direction. When it goes, there is a problem that air is easily entrapped in the stepped portion 104.

  In order to suppress the occurrence of such air accumulation, the sidewall rubber is divided into two layers of an inner rubber layer and an outer rubber layer. For example, as shown in FIGS. 8 and 9, the upper end portion 110A of the inner rubber layer 110 is formed. It is conceivable that the level difference can be alleviated by allowing the screw to enter under the end portion 102A of the tread rubber 102. However, when the side wall rubber is simply made into two layers, a new step is generated between the lower end 110B of the inner rubber layer 110 and the carcass ply 100, and the ribbon rubber is wound around to form the outer rubber layer 112. In addition, it has been found that this new step portion can easily entrap air and cause air accumulation in the vicinity of the bead portion 108.

  In view of the above points, an embodiment of the present invention manufactures a pneumatic tire that can suppress the occurrence of air pockets near the end of a tread rubber or a bead when a side wall rubber is formed by winding a ribbon rubber. It aims to provide a method.

The manufacturing method of the pneumatic tire which concerns on embodiment of this invention includes the following processes.
(1) A pad forming step of forming a belt lower pad on the outer peripheral side of the cylindrical carcass ply;
(2) A step of forming the inner rubber layer of the side wall rubber comprising the inner rubber layer and the outer rubber layer on the outer peripheral side of the carcass ply, and in the tire after vulcanization molding, the inner rubber layer is The upper end overlaps the belt lower pad, extends inward in the tire radial direction from the end of the tread rubber, and the lower end is positioned at the outer side in the tire radial direction with respect to the upper end of the bead filler. An inner rubber layer forming step of forming the inner rubber layer,
(3) In a state where a tread ring including a belt and a tread rubber is arranged around the carcass ply, the carcass ply is inflated and deformed in a tire radial direction, and the tread ring is formed on the outer periphery of the crown portion of the toroidal carcass ply. A case main body forming step of forming a case main body by adhering the end of the tread rubber to the inner rubber layer, and
(4) A step of forming the outer rubber layer by winding a plurality of ribbon rubbers around the outer side of the inner rubber layer in the case body, wherein the end portion of the tread rubber is formed by the outer rubber layer and the inner rubber layer. An outer rubber layer forming step in which the outer rubber layer is formed by overlapping the upper end portion of the outer rubber layer with the end portion of the tread rubber so that the outer rubber layer is sandwiched.

  According to the present embodiment, the sidewall rubber is divided into two layers, the inner rubber layer is overlapped with the belt lower pad, and the upper end of the bead filler is not applied to the end of the tread rubber. It is extended. Therefore, since the level difference at the end of the tread rubber is alleviated, it is possible to suppress the occurrence of air accumulation at the end of the tread rubber when the outer rubber layer is formed by winding the ribbon rubber. Moreover, since the space | interval is ensured between the lower end of an inner side rubber layer and the upper end of a bead filler, when winding the ribbon rubber of an outer side rubber layer, generation | occurrence | production of the air pocket in this part can also be suppressed.

Half sectional view of a pneumatic tire according to an embodiment Partial enlarged view of FIG. Sectional drawing which shows typically the pad formation process of the tire manufacturing method which concerns on one Embodiment. Sectional drawing which shows the inner side rubber layer formation process of the manufacturing method typically Sectional drawing which shows the case main body formation process of the manufacturing method typically Sectional drawing which shows the outer side rubber layer formation process of the manufacturing method typically Half sectional view of a pneumatic tire according to Comparative Example 1 Half sectional view of a pneumatic tire according to Comparative Example 2 Half sectional view of a pneumatic tire according to Comparative Example 3

  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 bead portion 12, an annular bead core 18 made of a bead wire and a bead filler 20 bonded and integrated on the outer peripheral surface of the bead core 18 are embedded. The bead filler 20 is made of hard rubber and has a narrow cross-sectional triangle shape toward the tip side.

  The pneumatic tire 10 has a toroidal carcass ply 22 embedded between a pair of bead portions 12. The carcass ply 22 extends from the tread portion 16 through the side wall portions 14 on both sides to the bead portion 12, and is wound up and locked around the bead core 18 in the bead portion 12. The carcass ply 22 is formed by covering the carcass cord with rubber and is disposed so that the carcass cord is substantially perpendicular to the tire circumferential direction. In this example, the carcass ply 22 is composed of two sheets of a first ply 22A on the tire inner surface side and a second ply 22B provided on the outer side.

  The carcass ply 22 is wound up from the inside in the tire width direction to the outside so as to wrap the bead core 18 and the bead filler 20, that is, turned up. The winding portion 22T of the carcass ply 22 terminates in the sidewall portion 14 (specifically, in the tire radial direction center) beyond the upper end (that is, the tire radial direction outer end) 20A of the bead filler 20. Specifically, the winding portion 22T includes a winding portion 22BT of the second ply 22B and a winding portion 22AT of the first ply 22A that covers the outside thereof, and the winding portion 22AT of the first ply 22A has a winding position. Highly formed. Therefore, the upper end of the winding portion 22AT of the first ply 22A is the winding end 22TE of the carcass ply 22.

  A belt 24 is disposed on the outer peripheral side of the carcass ply 22 in the tread portion 16. The belt 24 is composed of one or a plurality of belt layers in which a belt cord is inclined at a constant angle with respect to the tire circumferential direction. In this example, the belt 24 is composed of two belt layers. A belt reinforcing layer 26 made of an organic fiber cord extending in the tire circumferential direction is provided on the outer peripheral side of the belt 24. A tread rubber 28 constituting a contact surface is provided on the outer side Ro of the belt 24 and the belt reinforcing layer 26 in the tire radial direction.

  Between the both ends of the belt 24 and the main body 22M of the carcass ply 22, a belt lower pad 30 having a substantially triangular cross section is disposed in order to fill the difference in curvature between the two. In the tire cross-sectional shape shown in FIG. 2, the belt lower pad 30 has a bottom side (tire radial inner surface) arranged along the outer surface of the carcass ply main body portion 22M, and a central portion in the width direction of the outer peripheral surface corresponding to the top portion. The belt 24 is provided so that the end 24E in the width direction of the belt 24 is located.

  A sidewall rubber 32 is provided on the tire outer surface side of the carcass ply 22 in the sidewall portion 14. The sidewall rubber 32 is composed of two layers: an inner rubber layer 34 disposed on the carcass ply 22 side and an outer rubber layer 36 disposed on the outer side and forming the tire outer surface.

  The inner rubber layer 34 has an upper end 34A (that is, an outer end in the tire radial direction) that overlaps the belt lower pad 30 (that is, overlaps with the belt lower pad 30). The lower end (that is, the inner end in the tire radial direction) 34BE is positioned at a distance K from the upper end 20A of the bead filler 20 at a distance K on the outer side in the tire radial direction. It is formed to do.

  The upper end portion 34A of the inner rubber layer 34 is overlaid on the outer periphery of the belt lower pad 30. Specifically, the inner rubber layer 34 is overlaid on the outer end portion so as to cover the outer peripheral surface of the outer end portion in the tire width direction of the belt lower pad 30. Is provided.

  Further, the inner rubber layer 34 has a tire radial direction more than the end portion 28A of the tread rubber 28 (specifically, the edge 28AE of the tread rubber 28 on the outer side Wo in the tire width direction and the radial inner side Ri). It extends to the inside Ri. In other words, the inner rubber layer 34 has a structure in which the upper end portion 34 </ b> A enters the tire radial direction inner side Ri of the end portion 28 </ b> A of the tread rubber 28. Therefore, the upper end portion 34A of the inner rubber layer 34 is sandwiched between the belt lower pad 30 and the end portion 28A of the tread rubber 28, and is formed in a tapered cross-sectional shape that is thinner toward the tip.

  The inner rubber layer 34 extends inward in the tire radial direction Ri along the outer surface so as to cover the outer surface of the carcass ply 22 and covers the winding end 22TE of the carcass ply 22. Specifically, the lower end portion (that is, the inner end portion in the tire radial direction) 34B of the inner rubber layer 34 covers the winding portion 22AT of the first ply 22A, but extends to the winding portion 22BT of the second ply 22B. Terminate without. Further, the inner rubber layer 34 is terminated so that the lower end portion 34B does not reach the upper end 20A of the bead filler 20, and the tire diameter is between the lower end 34BE of the inner rubber layer 34 and the upper end 20A of the bead filler 20. A predetermined interval K is secured in the direction R. The interval K is preferably 50% or more of the width of a ribbon rubber (preferably, a ribbon rubber 48 forming the outer rubber layer 36) described later.

  The outer rubber layer 36 has an upper end portion 36 </ b> A overlapping the end portion 28 </ b> A of the tread rubber 28, and the outer rubber layer 36 and the inner rubber layer 34 sandwich the end portion 28 </ b> A of the tread rubber 28. The end portion 28A of the tread rubber 28 is formed in a tapered cross-sectional shape in which the thickness gradually decreases toward the edge 28AE, and the side end surface 28AF in the tire width direction W is the outer side Wo in the tire width direction and the inner side in the radial direction. It is formed in an inclined surface shape inclined to Ri. The upper end portion 36A of the outer rubber layer 36 has a tapered cross-sectional shape that is thinner toward the tip and covers the side end face 28AF of the tread rubber 28 and terminates at the tread grounding end.

  The outer rubber layer 36 extends inward in the tire radial direction Ri so as to cover the outer surface of the inner rubber layer 34, and covers the outer surface of the carcass ply 22 beyond the lower end 34 BE of the inner rubber layer 34. Is formed. In this example, the outer rubber layer 36 extends to the bead portion 12 and terminates in contact with a rim strip rubber 38 provided on the bead portion 12. Therefore, the lower end (that is, the inner end in the tire radial direction) 36BE of the outer rubber layer 36 is located on the inner side Ri in the tire radial direction from the upper end 20A of the bead filler 20.

  Reference numeral 40 denotes an inner liner provided on the tire inner surface side of the carcass ply 22.

  Next, a method for manufacturing the pneumatic tire 10 will be described with reference to FIGS. 3 to 6 show only the right half from the center in the width direction corresponding to the tire equator plane as in FIG. 1, the same applies to the left half.

  First, as shown in FIG. 3, in the pad forming process, the belt lower pad 30 is formed on the outer peripheral side of the cylindrical carcass ply 22. The belt lower pad 30 can be formed by winding unvulcanized rubber extruded in a substantially triangular cross section around a position corresponding to the end of the belt 24 on the outer peripheral surface of the carcass ply 22. Instead of using an extrusion-molded product, it may be formed into a substantially triangular cross section by a ribbon winding method in which unvulcanized ribbon rubber is wound a plurality of times along the tire circumferential direction.

  Here, the cylindrical carcass ply 22 is obtained by sequentially winding the unvulcanized inner liner 40 and the carcass ply 22 around the outer peripheral surface of the cylindrical forming drum 50 and forming the cylindrical shape. The bead core 18 and the bead filler 20 are extrapolated at both ends of the carcass ply 22 in the width direction. It is provided along the main body portion 22M. A rim strip rubber 38 is disposed on the winding portion 22T.

  Next, as shown in FIG. 4, in the inner rubber layer forming step, the inner rubber layer 34 of the sidewall rubber 32 is formed on the outer peripheral side of the cylindrical carcass ply 22. The inner rubber layer 34 may be formed by winding an unvulcanized rubber extruded into a shape corresponding to the cross-sectional shape of the product tire, but is preferably formed by a ribbon winding method. That is, as shown in FIG. 4, by wrapping the ribbon rubber 42, which is an unvulcanized belt-like rubber, on the outer circumferential surface of the carcass ply 22 while being overlapped with the belt lower pad 30, a plurality of circumferential windings are performed along the tire circumferential direction. The inner rubber layer 34 is formed.

  Ribbon rubber 42 can be wound spirally or pitch-turned around each turn while having an overlapping portion for each turn. Here, the spiral winding is performed by continuously changing the winding position of the ribbon rubber in the drum axial direction along with the rotation of the forming drum. Further, the pitch feed winding is performed by shifting the winding position in the drum axis direction by one pitch at a predetermined position on the circumference every time the forming drum is rotated once while the ribbon rubber is wound in parallel.

  The inner rubber layer 34 is formed so as to have the configuration shown in FIG. 2 in the tire after vulcanization molding. Specifically, as shown in FIG. 4, one end portion overlaps the belt lower pad 30, covers the winding end 22 TE of the carcass ply 22, and the other end portion does not cover the upper end 20 A of the bead filler 20. Terminate to In one embodiment, when the inner rubber layer 34 is formed by winding the ribbon rubber 42, the ribbon rubber 42 is overlapped with the belt lower pad 30 and starts to be wound, and is preferably 1 round or more, more preferably 1 round or more and 5 rounds or less. It is wound around the belt so as to have an overlapping portion with the belt lower pad 30. And it winds sequentially toward the width direction outer side, and after winding so that the winding end 22TE of the carcass ply 22 may be covered, winding is complete | finished before reaching the upper end 20A of the bead filler 20. FIG. Thereby, a predetermined interval K can be secured between the lower end 34BE of the inner rubber layer 34 and the upper end 20A of the bead filler 20. The ribbon rubber 42 may be wound from the lower end 34B, that is, from the bead filler 20 side, instead of starting from the upper end 34A, that is, from the belt lower pad 30 side.

  Next, as shown in FIG. 5, in the case main body forming step, the carcass ply 22 is mounted on the tire diameter with the tread ring 44 including the unvulcanized tread rubber 28 and the belt 24 disposed around the carcass ply 22. The tread ring 44 is joined to the outer periphery of the crown portion of the toroidal carcass ply 22 by expanding and deforming in the direction R.

  The tread ring 44 is obtained by winding a belt 24 and a belt reinforcing layer 26 around the outer periphery of a tread ring forming drum (not shown) and then molding the tread rubber 28 around the outer periphery. For forming the tread rubber 28, for example, a ribbon winding method in which a strip-shaped ribbon rubber is wound in a spiral manner along the tire circumferential direction can be used.

  In the case body forming step, the cylindrical molded body shown in FIG. 4 is transferred to the second molding drum 52, the tread ring 44 is disposed on the outer peripheral side of the central portion of the carcass ply 22, and the central portion of the carcass ply 22 is disposed in the tire radial direction. The outer periphery is bulged and deformed, and the outer periphery of the central portion is crimped to the inner peripheral surface of the tread ring 44 and integrated. At that time, for example, the carcass ply 22 can be inflated and deformed in a toroidal shape by supplying air to the inside using a bladder or the like while the left and right bead cores 18 are closely displaced.

  Thereafter, the end portion 28A of the tread rubber 28 is brought into close contact with the inner rubber layer 34 by using a stitcher such as a press roll to form the tire case main body 46 shown in FIG.

  Next, as shown in FIG. 6, in the outer rubber forming step, a plurality of ribbon rubbers 48, which are unvulcanized belt-like rubber, are wound around the tire circumferential direction on the outer side of the inner rubber layer 34 in the case body 46. The outer rubber layer 36 is formed. The ribbon rubber 48 is wound around the end portion 28A of the tread rubber 28 so as to overlap with the outer rubber layer 36 and the inner rubber layer 34 so that the end portion 28A of the tread rubber 28 is sandwiched between them. Yes.

  The ribbon rubber 48 may start winding from the upper end portion 36A of the outer rubber layer 36, or may start winding from the lower end portion. As one embodiment, when starting to wind from the upper end portion 36A, the ribbon rubber 48 is overlapped with the end portion 28A of the tread rubber 28 and started to be wound, and sequentially wound from the end portion 28A toward the tire radial inner side Ri. After the lower end 34BE of the inner rubber layer 34 and the upper end 20A of the bead filler 20 are further overlapped with the rim strip rubber 38, the winding is finished. Thereby, the outer rubber layer 36 is formed such that its lower end 36BE is positioned on the inner side Ri in the tire radial direction from the upper end 20A of the bead filler 20. As with the inner rubber layer 34, the ribbon rubber 48 can be wound spirally or pitch-turned every turn while having an overlapping portion for each turn.

  Here, the cross-sectional shape of the ribbon rubbers 42 and 48 is not particularly limited, and various shapes having a flat cross-sectional shape such as a trapezoidal shape, a crescent shape, and a triangular shape can be employed. The dimensions of the ribbon rubbers 42 and 48 are not particularly limited. For example, the width may be 15 to 35 mm, the thickness (thickness at the maximum thickness portion) may be 1.0 to 3.0 mm, and the width may be 20 to 30 mm. The thickness may be 1.5 to 2.5 mm. The ribbon rubbers 42 and 48 are wound by being deformed so as to follow the cross-sectional shape of the wound portion by being pressed with a roll or the like at the time of winding. Further, the winding pitch of the ribbon rubbers 42 and 48 can be appropriately set according to the thickness of the inner rubber layer 34 and the outer rubber layer 36.

  From the above, as shown in FIG. 6, a green tire (raw tire) 49 is formed. The obtained green tire 49 is set in a mold that is a vulcanization mold and vulcanized and molded according to a conventional method to obtain a pneumatic tire.

  According to the present embodiment, the sidewall rubber 32 is divided into the inner rubber layer 34 and the outer rubber layer 36, and the inner rubber layer 34 is overlapped with the belt lower pad 30, while the tread rubber 28. By extending the end portion 28A to the bead filler 20 side, the step at the end portion 28A of the tread rubber 28 can be reduced. Therefore, when the ribbon rubber 48 for forming the outer rubber layer 36 is wound, the occurrence of air accumulation at the end 28A of the tread rubber 28 can be suppressed.

  Further, the inner rubber layer 34 is extended in a range that does not reach the upper end 20A of the bead filler 20, and a gap K is secured between the lower end 34BE of the inner rubber layer 34 and the upper end 20A of the bead filler 20. Therefore, when the ribbon rubber 48 of the outer rubber layer 36 is wound, the occurrence of air pockets at this portion can be suppressed.

  This interval K, that is, the interval K in the tire radial direction R between the lower end 34BE of the inner rubber layer 34 and the upper end 20A of the bead filler 20 may be 50% or more of the width of the ribbon rubber 48 forming the outer rubber layer 36. Preferably, this makes it possible to more effectively suppress air entrainment when the ribbon rubber 48 of the outer rubber layer 36 is wound. The upper limit of the interval K is not particularly limited, and may be, for example, not more than twice the width of the ribbon rubber 48 or not more than 1.5 times.

  The interval K is in a normal state with no load in which a pneumatic tire is mounted on a normal rim and filled with a normal internal pressure. The regular rim is a rim determined for each tire in a standard system including a standard on which a tire is based. For example, a “standard rim” in the JATMA standard, a “Design Rim” in the TRA standard, or a “rim in the ETRTO standard” Measuring Rim ”. The normal internal pressure is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. Or “INFLATION PRESSURE” in the ETRTO standard.

  Further, in the present embodiment, the inner rubber layer 34 is overlapped with the belt lower pad 30, and the overlap is overlapped with the belt lower pad 30 in the round of the ribbon rubber 42 more than one turn, more preferably one turn or more and five turns or less. If it has, it will have the following effects. That is, since the level difference at the overlapping portion between the belt lower pad 30 and the inner rubber layer 34 is reduced, air accumulation at this portion can be suppressed.

  Further, when the inner rubber layer 34 is provided so as to cover the winding end 22TE of the carcass ply 22, the following operational effects are exhibited. That is, the inner rubber layer 34 eliminates the step due to the winding end 22TE of the carcass ply 22, and air accumulation caused by the step can be suppressed.

  In the above-described embodiment, the ribbon rubber 42 of the inner rubber layer 34 and the ribbon rubber 48 of the outer rubber layer 36 are wound only in one direction in the tire meridian direction. May be. The ribbon rubber 42 of the inner rubber layer 34 and the ribbon rubber 48 of the outer rubber layer 36 may be the same in rubber composition and cross-sectional shape, or may be different from each other.

  In order to confirm the effect of this embodiment, the tire of the example according to this embodiment, the tire according to comparative example 1 shown in FIG. 7, the tire according to comparative example 2 shown in FIG. 8, and the tire shown in FIG. A tire according to Comparative Example 3 was prototyped (tire size: LT315 / 75R16), and the presence or absence of air pockets was confirmed.

  The tire structure of the example is as shown in FIG. 1, and both the inner rubber layer 34 and the outer rubber layer 36 were produced by vulcanization molding using a ribbon winding method using the same ribbon rubber. The tire configuration of Comparative Example 1 is as shown in FIG. 7, and the side wall rubber 106 is a single layer structure, and the side wall rubber 106 is produced by a ribbon winding method using the same ribbon rubber as the outer rubber layer of the example. Vulcanization molding was performed in the same manner as in the examples. The tire configuration of Comparative Example 2 is as shown in FIG. 8, and the inner rubber layer 110 is extended inward in the tire radial direction and terminated at the upper end 114A of the bead filler 114 (therefore, the inner rubber layer The lower end 110B and the upper end 114A of the bead filler coincided), and the others were vulcanized in the same manner as in the example. The tire configuration of Comparative Example 3 is as shown in FIG. 9, and the inner rubber layer 110 is extended inward in the tire radial direction so as to overlap with the bead filler 114 (therefore, the lower end of the inner rubber layer). 110B is the inside of the tire radial direction from the upper end 114A of the bead filler), and the others were vulcanized in the same manner as in the example.

  As a result, in the comparative example 1, an air pocket occurred in the stepped portion 104 of the tread rubber end portion 102A. In Comparative Example 2 and Comparative Example 3, no air retention occurred at the tread rubber end portion 102A, but air retention occurred near the bead portion (specifically, near the lower end 110B of the inner rubber layer 110). On the other hand, in the example, no air pocket was generated in the vicinity of the end portion of the tread rubber or in the vicinity of the bead portion.

  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, 20 ... Bead filler, 22 ... Carcass ply,
28 ... tread rubber, 28A ... end, 30 ... belt under pad,
32 ... sidewall rubber, 34 ... inner rubber layer, 36 ... outer rubber layer,
44 ... Tread ring, 46 ... Case body, 48 ... Ribbon rubber,

Claims (4)

A pad forming step of forming a belt lower pad on the outer peripheral side of the cylindrical carcass ply;
A step of forming an inner rubber layer of a side wall rubber composed of an inner rubber layer and an outer rubber layer on an outer peripheral side of the carcass ply, and in the tire after vulcanization molding, the inner rubber layer has an upper end portion thereof. Is overlapped with the belt lower pad, extends inward in the tire radial direction from the end of the tread rubber, and the lower end is positioned at an interval in the tire radial outer side with respect to the upper end of the bead filler. An inner rubber layer forming step for forming an inner rubber layer;
With the tread ring having a belt and tread rubber arranged around the carcass ply, the carcass ply is inflated and deformed in the tire radial direction, and the tread ring is joined to the outer periphery of the crown portion of the toroidal carcass ply. , A case body forming step of forming an end of the case by bringing the end of the tread rubber into close contact with the inner rubber layer;
A step of forming the outer rubber layer by winding a plurality of ribbon rubbers around the inner rubber layer of the case main body, and an end portion of the tread rubber is sandwiched between the outer rubber layer and the inner rubber layer. An outer rubber layer forming step of forming the outer rubber layer by overlapping the upper end of the outer rubber layer with the end of the tread rubber,
The manufacturing method of the pneumatic tire containing this.   The manufacturing method of the pneumatic tire of Claim 1 whose space | interval of the lower end of the said inner side rubber layer and the upper end of the said beat filler is 50% or more of the width | variety of the said ribbon rubber.   The manufacturing method of the pneumatic tire of Claim 1 or 2 which forms the said outer side rubber layer so that the lower end of the said outer side rubber layer may be located inside a tire radial direction rather than the upper end of the said bead filler.   The pneumatic tire according to any one of claims 1 to 3, wherein the inner rubber layer is formed by winding a plurality of circumferences around the outer circumferential surface of the carcass ply while causing a ribbon rubber to overlap the belt lower pad. Manufacturing method.

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