JP2003025463A - Method for producing pneumatic tire, and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a pneumatic tire which can reduce costs and accomplish the weight reduction of the tire and the pneumatic tire. SOLUTION: A body ply 25 is engaged with a bladder 24, and beads 26 are set at both width end parts of the body ply 25. In this state, while the part between both width end parts of the body ply 25 is narrowed, the bladder 24 is deformed to the side of an outside diameter, so that the intermediate part in the axial direction of the body ply 25 is expanded. By moving a folding member 31 made of a rigid body from the side of the inside diameter to the side of the outside diameter of the body ply 25, both width end parts of the body ply 25 are folded, and the beads 26 are arranged in the folded parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a pneumatic tire, particularly a method of manufacturing a tire bead portion,
And pneumatic tires.

[0002]

2. Description of the Related Art Generally, in a pneumatic tire 51 as shown in FIG. 14, a portion sandwiched between a tire maximum cross-sectional width portion 51a and a mounting portion 51b for a rim 52, that is, an inner diameter side wall portion, is used during running. A large stress such as a compressive force acts on 51c. When the end edges 53b of the bent portions 53a at both width ends of the body ply 53 are arranged on the inner diameter side wall portion 51c, stress concentrates on the end edges 53b of the bent portion 53a. The inner diameter side wall portion 51c cannot withstand the excessive force, and the separation spreads around the edge 53b as a core, which is not preferable.

Therefore, the bent portion 5 of the body ply 53
3a is greatly extended to the tread 51d side beyond the tire maximum width portion 51a, or the end edge 53 of the bent portion 53a.
b is provided, or the bent portion 53a is shortened so that its end edge 53b has a rim mounting portion 51b.
It is necessary to stop in the area of. in this case,
From the viewpoints of material cost reduction and weight reduction, the bent portion 5
A method of stopping the edge 53b of 3a in the area of the mounting portion 51b is preferable, but in the conventional manufacturing method, the requirement could not be satisfied as described below.

That is, FIG. 15 shows a bead core 54a.
A conventional manufacturing method for mounting the bead 54, which includes the bead filler 54b and the bead filler 54b, on the body ply 53 is shown. In this conventional method, first, as shown in FIG. 15A, the body ply 53 is set on the drum 55 with its width end protruding, and the bead 54 is assembled on the protruding portion. Next, as shown in FIG. 15B, air is injected into the flat bladder 56,
When the bladder 56 is expanded, the width end portion of the body ply 53 is erected.

Further, as shown in FIG. 15 (c), the bladder 56 is continuously expanded, and the bladder 56 is pressed toward the drum 55 side by the metal push can 57. By this pressing, the body ply 5
The width end of 3 is folded back, and the bead 54 is wrapped in the bent portion 53 a of the body ply 53. afterwards,
The drum 55 is contracted, the body ply 53 enclosing the bead 54 is removed from the drum 55, and sent to the next step.

[0006]

However, in this conventional manufacturing method, as apparent from FIG. 15 (b), the outer diameter shape of the bladder 56 is small at the initial stage of expansion, and the width end of the body ply 53 is small. The section cannot be fully raised. Therefore, when the length of the bent portion 53a of the body ply 53 is short, the bent portion 53a may hang down due to its own weight, or wrinkles may be formed in the bent portion 53a. Therefore, as described above, it is necessary to extend the bent portion 53a of the body ply 53 to the tread 51d side or to prevent the edge 53b of the bent portion 53a from being covered with a coating layer to form the core of the separation. However, there are problems in terms of material cost reduction and weight reduction.

The present invention has been made by paying attention to the problems existing in such conventional techniques. It is an object of the present invention to provide a pneumatic tire manufacturing method and a pneumatic tire that can achieve cost reduction and tire weight reduction.

[0008]

In order to achieve the above object, the invention relating to the method of manufacturing a pneumatic tire according to claim 1 has a body ply wound around a cylindrical surface and the body ply. With the bead set at both width ends of the body ply, move the bending member made of a rigid body from the inner diameter side of the body ply to the outer diameter side to bend both width ends of the body ply, and the bead at the bent portion. Are arranged.

Therefore, according to the invention of claim 1, even when the length of the bent portion of the body ply is short,
By moving the bending member made of a rigid body, the width ends of the body ply can be bent while being surely erected, and the beads can be arranged. Therefore, the cost can be reduced and the weight of the tire can be reduced.

According to a second aspect of the present invention, in the first aspect of the invention, when the width ends of the body ply are bent, the bead set portion of the body ply is moved from the inner diameter side to the outer diameter side by a pressing member. It is characterized by pressing and locking that part.

Therefore, according to the second aspect of the invention, the bead set portion of the body ply can be locked by the pressing member so as not to move, and the bead can be wrapped securely. Further, since the body ply is locked on the inner diameter side of the bead, the length of the bent portion of the body ply should be 1/2 of the axial dimension of the bead core.
With the above, it is possible to form a tire in which the height of the bent portion of the body ply (the tire radial direction dimension) is zero, and it is possible to further reduce the cost and reduce the weight of the tire. Furthermore, when the height of the bent portion of the body ply is set to zero, no bending member is required, and the configuration of the tire molding device can be simplified.

According to the invention of claim 3, claim 1
In bending the both width end portions of the body ply, the bead set portion of the body ply is locked and the intermediate portion in the axial direction is expanded while narrowing the width end portions of the body ply. It is characterized by making it diameter.

Therefore, according to the third aspect of the present invention, the bead set portion of the body ply can be locked, and the space between both width ends of the body ply can be narrowed accordingly, so that the tire molding can be performed. And bead wrapping can be performed simultaneously.

The invention according to a fourth aspect is characterized in that, in the invention according to the second or third aspect, the pressing member is arranged so as to be relatively movable adjacent to the bending member.

Therefore, according to the invention of claim 4, the bending member is moved in a state of being adjacent to the pressing member, and the bending portion of the body ply is set to the bead with respect to the bead inner diameter side surface as a base point. As a result, it can be adhered without wrinkles or gaps.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, a bladder forming the cylindrical surface is used, and the body ply is set on the bladder. Then, the body ply is expanded in diameter by deforming the bladder to the outer diameter side.

Therefore, according to the fifth aspect of the present invention, the body ply is deformed into a toroidal shape by expanding the diameter of the bladder, and tire parts such as sidewalls can be easily mounted on the outer peripheral surface thereof.

The invention according to claim 6 is characterized by being manufactured by the manufacturing method according to any one of claims 1 to 5. Therefore, according to the invention of claim 6, the length of the bent portion of the body ply can be set to be short, and the end edge of the bent portion can be stopped within the area of the mounting portion with respect to the rim. Performance improvement, cost reduction, and weight reduction can be achieved.

According to a seventh aspect of the present invention, in the invention according to the sixth aspect, the position of the end edge of the bent portion of the body ply is outside the center of the bead core width in the tire axial direction,
It is characterized in that it is set within the range of the height of the rim flange.

Therefore, according to the seventh aspect of the invention, the length of the bent portion of the body ply in the tire axial direction can be shortened, and the material cost and the tire weight can be reduced.

The invention according to claim 8 is characterized in that, in the invention according to claim 6 or 7, the position of the end edge of the bent portion of the body ply is set within 1/2 of the rim flange height. It is what

Therefore, according to the invention described in claim 8, the bead can be effectively arranged by the bent portion of the body ply, and the end edge of the bent portion of the body ply is stopped within the area of the mounting portion to the rim. Can do things very effectively.

According to the invention of claim 9, claim 6
The invention according to any one of items 1 to 8 is characterized in that a bead insert ply for reinforcing the bead portion is provided.

Therefore, according to the invention of claim 9,
Even if the bent portion of the body ply is shortened, the bead insert ply can ensure the rigidity of the bead portion, and a tire with excellent steering stability can be realized.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, in the tire building apparatus 21 of this embodiment, a pair of left and right ring-shaped moving bodies 23 are provided relative to the operating shaft 22 along the axis L direction by a driving means (not shown). Are supported so that they can approach and separate,
A bladder mounting portion 23a is provided on the inner peripheral edge thereof.

Between the bladder mounting portions 23a of both the moving bodies 23, cylindrical bladders 24 are mounted at both ends thereof. On the outer peripheral surface of the bladder 24, a body ply 25 formed into a cylindrical shape in the previous step is fitted. Further, the bead cores 26 are provided on the outer circumferences of both width ends of the body ply 25.
A bead 26 including a and a bead filler 26b is fitted.

The bladder 24 is composed of an inner elastic material 27, an outer elastic material 28, and a core material 29 interposed between the elastic materials 27, 28. The core member 29 includes a plurality of wire members extending in the axial direction of the bladder 24, and the bladder 24.
Is formed of a plurality of wire rods extending in a direction orthogonal to the axis line of, and a material having a high tensile strength and a small permanent set, for example, an aramid fiber is used as the wire rods. Therefore, the bladder 24 has a property of easily bending, but hardly expands or contracts. On the inner peripheral surfaces of both width ends of the inner elastic material 27 of the bladder 24, an annular mounting protrusion 27 is formed.
a is formed, and the annular connecting protrusion 28a is also formed.
Are formed. The mounting convex portion 27a is fitted and fixed to the bladder mounting portion 23a formed on the moving body 23. Further, the connecting convex portion 28a is fitted and fixed to the connecting concave portion 30a formed in the pressing member 30 described later.

As shown in FIGS. 1 to 3, the two moving bodies 2 are
An annular housing recess 23b is formed on the outer peripheral surface of the metal plate 3. In the accommodation recess 23b, a plurality of pressing members 30 made of a rigid body such as a hard synthetic resin are arranged in the circumferential direction of the moving body 23 so as to be radial around the axis L, and are movable in the radial direction. It is housed. The connecting concave portion 30a for fitting the connecting convex portion 28a of the bladder 24 is formed at the outer end portion of each pressing member 30. In addition, an inclined surface 30b is formed on the inner end of each pressing member 30, and an engaging protrusion 30c is formed on the outer surface.

A plurality of bending members 31 made of a rigid body such as hard synthetic resin are centered on the axis L in the accommodating recess 23b of the moving body 23 so as to be arranged adjacent to the outer surface of each pressing member 30. The movable bodies 23 are housed so as to be radially movable while being radially arranged in the circumferential direction. An engaging groove 31a is formed at the outer end of each bending member 31.
Are formed. In addition, an inclined surface 31b is formed on the inner end of each bending member 31, and an engaging concave portion 3 that can be engaged with the engaging convex portion 30c of each pressing member 30 is formed on the outer surface.
1c is formed.

An annular spring 32 centering on the axis L is hooked in the locking groove 31a of each bending member 31. The spring 32 urges each bending member 31 to move in the direction in which the moving body 23 is retracted into the accommodation recess 23b, and causes each pressing member 30 to engage the engaging projection 30c and the engaging recess 31c. It is urged to move in the same direction through the joint.

An annular inner cylinder chamber 33 centering on the axis L is formed in each of the moving bodies 23, and an inner piston 34 having an inclined cam surface 34a on the inner peripheral surface is formed in the inner cylinder chamber 33. Are movably arranged.
Then, as shown in FIG. 4, when the inner piston 34 is moved toward the pressing member 30 side with the supply of the compressed air into the inner cylinder chamber 33, the inclined cam surface 34a and the inclined surface 30b are engaged with each other. As a result, each pressing member 30 is moved to project outward from the accommodation recess 23b of the moving body 23 against the biasing force of the spring 32. By this projecting movement, the bead set portion of the body ply 25 is pressed from the inner diameter side to the outer diameter side, and that portion is locked to the inner diameter surface of the bead core 26a.

Further, when each pressing member 30 is projected and moved, each bending member 31 is accommodated in the recess 23b of the moving body 23 through the engagement between the engaging projection 30c and the engaging recess 31c.
It is moved to a position slightly protruding from the inside to the outside. By this movement, the inclined surface 31b of each bending member 31 is arranged so as to be engageable with the inclined cam surface 38a of the outer piston 38 described later.

An air supply passage 36 is formed in the shaft core of the operating shaft 22 so as to communicate with the inner space 35 in the bladder 24 between the two moving bodies 23. And FIG.
As shown in FIG. 3, the compressed air is supplied from the air supply passage 36 to the inner space 35 of the bladder 24 while the widthwise ends of the body ply 25 are narrowed by the approach movement of the movable bodies 23. 24 is deformed toward the outer diameter side. Due to this deformation, the body ply 25 is deformed in a toroidal shape while being expanded in diameter at the intermediate portion in the axial direction.

An annular outer cylinder chamber 37 centered on the axis L is formed in each of the movable bodies 23 concentrically with the inner cylinder chamber 33.
An outer piston 38 having an inclined cam surface 38a on its inner peripheral surface is movably arranged inside. Then, as shown in FIG. 5, when the outer piston 38 is moved toward the bending member 31 side with the supply of the compressed air into the outer cylinder chamber 37, the engagement between the inclined cam surface 38a and the inclined surface 31b is performed. As a result, each bending member 31 is moved to project outward from the accommodation recess 23b of the moving body 23. By this projecting movement, both width ends of the body ply 25 are bent by the bending members 31, and the beads 26 are arranged at the bent portions 25a.

In this embodiment, as shown in FIG. 6, the position of the end edge 25b of the bent portion 25a is not more than the height H of the rim flange 40a of the rim 40, preferably not more than 1 / 2H (the rim flange 40a. Height H 1
/ 2 times or less) is set. Then, with the pneumatic tire 39 molded, the end edge 25b of the bent portion 25a of the body ply 25 can be stopped within the area of the mounting portion 39a with respect to the rim 40.

Next, the operation of the tire building apparatus 21 configured as described above will be described. Now, in this tire forming device 21, as shown in FIG.
In the state in which the bladder 24 is moved to the separated position, the body ply 25 is fitted on the outer periphery of the cylindrical surface of the bladder 24, and the beads 26 are placed on both width ends of the body ply 25. In this state, the inner and outer pistons 34, 38 are arranged at the retracted position, and the plurality of pressing members 30 and the bending members 31 are arranged at the retracted position in the accommodation recess 23b of the moving body 23 by the urging force of the spring 32. There is.

In this state, as shown in FIG. 4, compressed air is supplied into the inner cylinder chamber 33, and the inner piston 34 is moved forward to the pressing member 30 side. Therefore, each pressing member 30 is projected outward from the accommodation recess 23b of the moving body 23 by the engagement between the inclined cam surface 34a and the inclined surface 30b. Due to this protruding movement, the bead set portion of the body ply 25 is pressed from the inner diameter side to the outer diameter side, and that portion is locked immovably.

In this case, the bladder 2 is discharged from the air supply passage 36.
Compressed air is also supplied to the inner space 35 of the bladder 4, the bladder 24 is deformed to the outer diameter side, and the intermediate portion of the body ply 25 is expanded in diameter, as shown in FIG. At the same time, the two moving bodies 23 are moved toward each other, and the gap between the width ends of the body ply 25 is narrowed.

Further, with the protrusion movement of each pressing member 30,
Each bending member 31 is moved to a position slightly protruding outward from the accommodation recess 23b of the moving body 23 through the engagement between the engagement protrusion 30c and the engagement recess 31c. By this movement, the inclined surface 31b of each bending member 31 is disposed so as to be engageable with the inclined cam surface 38a of the outer piston 38.

Further, as shown in FIG. 5, compressed air is supplied into the outer cylinder chamber 37 and the outer piston 38
Is moved forward to the bending member 31 side, and the inclined cam surface 3
8b and the inclined surface 31b are engaged with each other to bend each bending member 3
1 is projected and moved outward from the inside of the accommodation recess 23b of the moving body 23. Due to this protruding movement, both width end portions of the body ply 25 are folded back, and the bead 26 is wrapped in the bent portion 25a. Therefore, as shown in FIG. 6, even when the position of the end edge 25b of the bent portion 25a of the body ply 25 is set within a range within the rim flange height H, for example, a short dimension of about 10 mm, By the bending member 31 that is formed, wrinkles and sags do not occur at both width end portions of the body ply 25. Therefore, both width end portions of the body ply 25 are folded up on the bead 26 while being surely erected.

Thereafter, the belt layer and the tread rubber or the like are sequentially laminated to the outer circumference of the toroidal body ply 25, or a belt-tread annular body formed by previously laminating the annular layers is fitted. Then, the sidewall is wound around the side surface of the body ply 25.
In this way, the molding of the green tire before vulcanization is completed. Then, by vulcanizing this green tire, a pneumatic tire 39 as shown in FIG. 13 is obtained.

When the green tire undergoes the vulcanization process, the body ply 25 is slightly displaced due to the diameter expansion during vulcanization. Therefore, the length of the bent portion 25a of the body ply 25 is set in consideration of the displacement. Has been done.

Therefore, according to this embodiment, the following effects can be obtained. (1) In this method for manufacturing a pneumatic tire, the bending member 31 made of a rigid body is moved from the inner diameter side of the body ply 25 to the outer diameter side thereof.
Both width ends of 5 are bent, and the bead 26 is arranged at the bent portion 25a. Therefore, even when the length of the bent portion 25a of the body ply 25 is short, the bead 26 can be arranged by folding the both width end portions of the body ply 25 while surely raising them without wrinkling or sagging. it can. Therefore, the cost can be reduced and the weight of the tire can be reduced.

(2) In this method of manufacturing a pneumatic tire, the bead set portion of the body ply 25 is pressed from the inner diameter side to the outer diameter side by the pressing member 30 when the width ends of the body ply 25 are bent. Then, that part is locked. Therefore, when the width end of the body ply 25 is bent and the bead 26 is wrapped, the bead 26 can be reliably arranged. Further, since the body ply 25 is bent at the end side from the locked portion, the bending does not affect the portion between the bead portions of the body ply 25. By being folded back mechanically uniformly, a uniform tire without wrinkles is formed, and the uniformity of the tire can be improved.

(3) In this pneumatic tire,
The body ply 2 is manufactured by the manufacturing method as described above.
The height position L1 of the end edge 25b of the bent portion 25a of No. 5 is within the height H of the rim flange, preferably 1/2.
It is set within the range within H. That is, the end edge 25b of the bent portion 25a of the body ply 25 can be stopped within the area of the mounting portion 39a with respect to the rim 40, that is, within the flange height of the rim 40. Therefore, the edge 25b, which tends to be a failure nucleus, is housed in the flange with small dynamic strain,
Cost reduction and weight reduction can be achieved while ensuring the strength and durability of the tire. In particular, if the height position L1 of the end edge 25b of the bent portion 25a is set to about 10 mm, preferably within the bead core height, a balance between ensuring tire strength and durability and reducing cost and weight is achieved at a high level. can do.

(Second Embodiment) Next, a second embodiment of the present invention will be described focusing on the points different from the first embodiment.

Now, in the tire forming apparatus 21 of the second embodiment, as shown in FIG. 7, the plurality of bending members 31 of the first embodiment are not provided, and the inside of the accommodation recess 23b of the moving body 23 is not provided. Further, only the plurality of pressing members 30 are housed and arranged so that they can appear and disappear. A locking groove 31d is formed on the outer end of each pressing member 30, and the locking groove 31d is formed.
Each pressing member 30 is urged to move to the retracted position in the accommodation recess 23b by the spring 32 mounted on the. Further, the outer cylinder chamber 37 in the first embodiment.
The outer piston 38 is also removed, and the moving body 23 is provided with only the cylinder chamber 33 and the piston 34 corresponding to the inner cylinder chamber 33 and the inner piston 34.

Then, the bladder 24 between the pair of moving bodies 23
The body ply 25 is fitted on the top of the body ply 25, and the beads 26 are set in the vicinity of both end edges 25b of the body ply 25. At this time, both end edges 25b of the body ply 25
Is located outside the center of the width of the bead core 26a in the tire axial direction. In this state, the movement of the inner piston 34 causes each pressing member 30 to move in a protruding manner from the inside of the accommodation recess 23b against the biasing force of the spring 32. By this projecting movement, the bead set portion of the body ply 25 is pressed from the inner diameter side to the outer diameter side, and the bead 2
6 to the bead core 26a.

At this time, similarly to the first embodiment, the two moving bodies 23 are moved toward each other so that the distance between the width ends of the body ply 25 is narrowed, and the space is moved into the inner space 35. By supplying the compressed air, the bladder 24 is deformed to the outer diameter side, and the intermediate portion of the body ply 25 is expanded in diameter. Due to this diameter increase, the body ply 25 is formed in a toroidal shape in a state where it is in close contact with the beads 26 at both width end portions. Therefore, when the pneumatic tire 39 is molded with the body ply 25, as shown in FIGS. 8A and 8B, the edge 2 of the bent portion 25 a of the body ply 25 is
It is possible to obtain a lightweight tire in which the position of 5b is located outside the center position C2 of the bead core width in the tire axial direction and inside the bead core outer end position C1.

Therefore, according to the second embodiment, the following effect can be obtained in addition to the effect described in (2) in the first embodiment. (4) In this pneumatic tire manufacturing method, a tire in which the end edge 25b of the bent portion 25a of the body ply 25 is located outside the bead core center position C2 in the tire axial direction and inside the bead core outer end position C1 is formed. Therefore, further cost reduction and tire weight reduction can be achieved.
Further, the bending member 31 in the first embodiment is unnecessary, and the configuration of the tire molding device can be simplified.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 10, in No. 1 of the third embodiment, the bead filler 2 of the bead 26 is used.
The bead insert ply 41 is arranged on the outer surface of 6b,
The pneumatic tire 39 is molded. The bead insert ply 41 is attached to the bead filler 26b before the bead 26 is placed on both width ends of the body ply 25.
The bead insert ply 41 is a cord made of steel or organic fiber coated with rubber,
The cord is wound so as to be concentric with the bead 26.

The bead insert ply 41 is arranged in the tire outer diameter direction from a position where it is almost in contact with the bead core 26a. Further, the number of cords to be driven in the bead insert ply 41 is set to be 3 to 25 cords / 25 mm.

As shown in FIG. 11, in No. 2 of the third embodiment, the bead filler 2 of the bead 26 is used.
The bead insert ply 41 is arranged on the inner surface of 6b,
The pneumatic tire 39 is molded. In this case, the bead insert ply 41 has the bead core 2 at the inner diameter side end.
It is slightly separated from 6a. The assembly and the material of the bead insert ply 41 are the same as those of the above-mentioned 1.

As shown in FIG. 12, in No. 3 of the third embodiment, a bead insert ply 41 made of the same material as No. 1 and No. 2 is used at the center of the bead filler 26b, and a pneumatic tire 39 is provided. Mold. In this case, the bead filler 26b is divided into two, the bead insert ply 41 is attached to one of the divided pieces, and then both the divided pieces are integrated and combined with the bead core 26a.

By doing so, it becomes possible to secure the rigidity of the bead portion and to obtain a tire having excellent steering stability. (Modification) The present embodiment can be modified and embodied as follows.

In the first and second embodiments,
The pressing member 30 and the bending member 31 are configured to be moved by a mechanical drive device such as a cylinder device or a solenoid operated by pressure oil.

In the first embodiment, as shown in FIG. 9, the height L1 of the bent portion 25a of the body ply 25 is within the range of 5 to 15 mm, for example, about the height of the bead core 26a of the bead 26. Set to short dimensions. This can contribute to cost reduction and tire weight reduction.

In the first of the third embodiment,
The bead insert ply 41 is provided outside the bent portion 25a of the body ply 25. In this case, the bead insert ply 41 is attached to the bent portion after the bending of the body ply 25 is completed. Even in this case, the same effect as that of the third embodiment can be obtained.

[0061]

As described above in detail, according to the present invention, it is possible to provide a pneumatic tire capable of achieving cost reduction and tire weight reduction.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a tire building apparatus according to a first embodiment.

FIG. 2 is a partial cross-sectional view showing an enlarged part of the tire building apparatus of FIG.

FIG. 3 is an exploded perspective view showing a folding member and a pressing member in an enlarged manner.

FIG. 4 is a partial cross-sectional view showing an operating state of the tire building apparatus of FIG.

FIG. 5 is a partial cross-sectional view showing a further operating state of the tire building apparatus.

6 is a partial cross-sectional view of a tire manufactured by the tire forming apparatus of FIG.

FIG. 7 is a partial cross-sectional view showing a tire molding device of a second embodiment.

8A is a partial cross-sectional view of a tire manufactured by the tire forming apparatus of FIG. 7 and showing an example in which a bending edge position of a body ply is set to a core center position. FIG. FIG. 3B is a partial cross-sectional view of the tire showing an example in which the bending edge position of the body ply is also set to the core outer end position.

FIG. 9 is a partial cross-sectional view showing a different configuration of the tire.

FIG. 10 is a partial cross-sectional view showing the configuration of the tire according to Part 1 of the third embodiment.

FIG. 11 is a partial cross-sectional view showing the configuration of the tire of the third embodiment, part 2.

FIG. 12 is a partial cross-sectional view showing the configuration of a tire of the third embodiment, part 3.

FIG. 13 is a sectional view of a tire showing an embodiment of the present invention.

FIG. 14 is a cross-sectional view showing the structure of a normal tire.

15 (a), 15 (b) and 15 (c) are explanatory views sequentially showing a manufacturing process of conventional body ply bending.

[Explanation of symbols]

21 ... Tire forming device, 23 ... Moving body, 24 ... Bladder,
25 ... Body ply, 25a ... Bending part, 26 ... Bead, 30 ... Pressing member, 31 ... Bending member, 34 ... Inner piston, 36 ... Air supply passage, 38 ... Outer piston,
51 ... Pneumatic tire, L1 ... Height of bent portion, L2
… The length of the bottom of the bead core.

Claims (9)

[Claims] 1. A body-ply is wound on a cylindrical surface, and a bending member made of a rigid body is moved from an inner diameter side to an outer diameter side of the body ply in a state where beads are set at both width end portions of the body ply. By doing so, both width end portions of the body ply are bent, and the bead is arranged at the bent portion. 2. When bending both width end portions of the body ply, the bead set portion of the body ply is pressed from the inner diameter side to the outer diameter side by a pressing member to lock the portion. 1. The method for manufacturing the pneumatic tire according to 1. 3. When bending both width end portions of the body ply, the bead set portion of the body ply is locked, and the axial middle portion of the body ply is expanded while narrowing the width end portions of the body ply. The method for manufacturing a pneumatic tire according to claim 1, wherein the pneumatic tire is manufactured. 4. The method for manufacturing a pneumatic tire according to claim 2, wherein the pressing member is arranged adjacent to the bending member so as to be relatively movable. 5. A bladder forming the cylindrical surface is used,
The body ply is expanded by deforming the bladder to the outer diameter side in a state in which the body ply is set on the bladder. Manufacturing method for pneumatic tires. 6. A pneumatic tire manufactured by the manufacturing method according to any one of claims 1 to 5. 7. The position of the end edge of the bent portion of the body ply is set outside the center of the bead core width in the tire axial direction and within the height of the rim flange. Pneumatic tire described. 8. The pneumatic tire according to claim 6, wherein the position of the edge of the bent portion of the body ply is within 1/2 of the rim flange height. 9. The pneumatic tire according to claim 6, further comprising a bead insert ply for reinforcing the bead portion.