JP2000238148A - Manufacture of pneumatic tire and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having improved uniformity. SOLUTION: In a secondary molding step of manufacturing a raw tire, a strip-like rubber member 19 is wound twice on a BT drum 24 to form an annular top tread 20. As a result, the tread 20 has no fear of forming a gap in a circumferential direction, and no necessity of effectively connecting a connecting part of the member 19 by butting it. Thus, a weight of the connecting part can be suppressed to become a locally heavy, and uniformity of the tire can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire manufacturing method and a pneumatic tire having improved weight uniformity.

[0002]

2. Description of the Related Art A method of manufacturing a pneumatic tire includes a process of forming a cylindrical band by attaching an inner liner, a ply, and the like on a drum, and attaching a side rubber and a stiffener to a band folded by a bead. A step of forming a raw case, a step of injecting air into the raw case to expand it, a step of forming a laminated body in which a belt and a top tread are laminated in an annular shape, and attaching the laminated body to the raw case to integrate them. Forming a green tire by allowing
It consists of a step of vulcanizing a green tire.

In a process of laminating a belt and a top tread to form an annular laminated body, a belt and a top tread are supplied from a servicer onto a drum (hereinafter, referred to as a BT drum), and each of the belts and the top tread is wound once (for one round). It is pasted one by one. Thereby, the belt and the top tread stacked on the BT drum are formed into an annular stacked body.

[0004]

In the conventional pneumatic tire manufacturing method, when the top tread is attached to the BT drum, it is wound only one round. Therefore, so that the beginning and end of the top tread made of rubber do not separate,
The joint had to be securely joined with the beginning and end. For this reason, the weight of the joined portion increases, and the uniformity of the weight (hereinafter, referred to as uniformity) of the pneumatic tire after manufacture decreases. As a result, there is a disadvantage that the radial force variation (hereinafter, referred to as RFV) increases.

The present invention has been made to solve the above problems, and has as its object to provide a pneumatic tire manufacturing method and a pneumatic tire with improved uniformity.

[0006]

In order to achieve the above object, a method for manufacturing a pneumatic tire according to claim 1 includes a step of forming an annular top tread by winding a belt-shaped rubber member around two times. Features.

In this manufacturing method, since the belt-shaped rubber member is attached over two circumferences, the belt-shaped rubber member is wound around the entire circumference for at least one circumference.
Therefore, the top tread does not have a gap in the circumferential direction, and there is no need to strictly join the belt-shaped rubber member with the starting end and the end thereof abutting. As a result, one turn (1
(Circumference), it is not necessary to join the joined portions, so that the uniformity of the manufactured pneumatic tire is improved without locally increasing the weight of the joined portions. Moreover, even if the positions of the start end and the end of the belt-shaped rubber member are slightly shifted in the circumferential direction, the effect is reduced as compared with the case where the belt is wound once. This is because the thickness of the shifted portion is な る of the total thickness.

According to a second aspect of the present invention, there is provided a method of manufacturing a pneumatic tire according to the first aspect, wherein in the step, the positions of the start end and the end of the belt-shaped rubber member wound around the circumference are matched in the circumferential direction. It is characterized by the following.

As described above, by aligning the start and end positions of the top tread in the circumferential direction, the belt-like rubber member (top tread) is uniformly wound (two steps) over the entire circumference. The uniformity of the manufactured pneumatic tire can be further improved.

Further, in the method for manufacturing a pneumatic tire according to claim 3, in the manufacturing method according to claim 2, the starting end and the end of the belt-shaped rubber member are tapered in the circumferential direction in the step. It is characterized by.

Therefore, the end of the band-shaped rubber member is brought into contact with the tapered step formed by being laminated on the starting end of the band-shaped rubber member.
The rubber thickness of the molded top tread becomes more uniform over the entire circumference. As a result, the uniformity of the manufactured pneumatic tire is further improved.

Further, the pneumatic tire according to claim 4 is:
It is characterized by being molded by the method for producing a pneumatic tire according to claims 1 to 3.

Therefore, a pneumatic tire with improved uniformity can be provided.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a pneumatic tire according to one embodiment of the present invention will be described in detail. Hereinafter, description will be made with reference to FIGS.

An inner liner is wound around a cylindrical drum (not shown), and a carcass ply or the like is wound thereon to form a cylindrical band on the outer peripheral surface of the cylindrical drum (band forming step).

The band is folded around the driven bead 10 and the side wall 12 (side tread) is attached to the raw case 1 so that
4 (see FIG. 1) (primary molding step).

The raw case 14 is subjected to secondary molding and is mounted on a second former 16 (see FIG. 2) described later. In the second former 16, the distance between the beads 10 is reduced, and the raw case 14 is expanded by filling the raw case 14 with air via a bladder (see FIG. 3).

On the other hand, the annular belt 18 and the top tread 20 integrated with the raw case 14 are formed as follows. The belt 18 is wound around the BT drum 24 in two steps from the servicer 22, and a belt-shaped rubber member 19 having a half of a predetermined thickness is wound twice thereon to form an annular laminated body 30 ( 2, 4 and 5).

At this time, a taper is formed at the start end 26 of the belt-shaped rubber member 19 along the circumferential direction, and the end 28
Is tapered in the opposite direction along the circumferential direction (see FIG. 5). Therefore, the end portion 28 is inclined to the stepped portion (upward portion of the second round) 34 inclined by the taper of the start end 26.
, The belt-shaped rubber member 19 (top tread 20) has a predetermined thickness over the entire circumference.

The laminate 30 formed on the BT drum 24 in this manner is attached to the BT drum 2 by an O-ring 32.
4 is transported onto the second former 16 (see FIG. 2) and is attached to the expanded raw case 14 to form a green tire 34 by stitching (see FIGS. 6 to 7) (secondary forming step). ).

The pneumatic tire is manufactured by vulcanizing the green tire 34 thus formed.

Manufacturing the pneumatic tire based on the manufacturing method according to this embodiment has the following effects. That is, the belt-shaped rubber member 1 having a half of a predetermined thickness is placed on the belt 18 wound around the BT drum 24.
Since 9 is applied over two turns, one turn surely exists over the entire circumference. Therefore, the formed top tread 20 has no gap in the circumferential direction,
It is not necessary that the start end 26 and the end end 28 of the belt-shaped rubber member 19 be put together and strongly joined. As a result, an increase in weight at the joint portion can be prevented, and the deviation of the weight distribution in the circumferential direction is reduced. Further, even if the position of the start end 26 and the position of the end 28 of the belt-shaped rubber member 19 are slightly shifted, the effect is reduced as compared with the case of a single turn. That is, the thickness of the shifted portion is １ ／ of the rubber thickness of the top tread 20.

Of course, the pneumatic tire (top tread 20) can be formed by matching the circumferential position (on the BT drum 24) of the start end 26 and the end end 28 of the belt-shaped rubber member 19.
Can be further improved.

In particular, since the end 28 of the belt-shaped rubber member 19 is tapered in a direction opposite to the start end 26, the end 28 abuts on the step portion 32 tapered by being laminated on the start end 26. , Top tread 20
Can be made constant over the entire circumference. Therefore, the uniformity of the pneumatic tire can be further improved.

RFV was measured to confirm the operation and effect of the pneumatic tire manufactured by the method for manufacturing a pneumatic tire according to the present invention.

The example tire is a tire in which a belt-like rubber member 19 having a half of a predetermined thickness is wound twice on a BT drum to form a top tread (see FIG. 5). The rubber band member on the BT drum
This is a tire whose circumference is wound to form a top tread (see FIG. 8). The test tire has a size of 205 / 65R
It is 15 and is assembled on a standard rim of 15 × 6JJ, and the filling internal pressure is 2.0 kgf / cm ² .

The test was carried out on a uniformity tester using 20 tires of each of the conventional example and the embodiment.
Were measured and the average value was determined. Table 1 shows the results
Shown in

[0028]

[Table 1]

As described above, in the tire of the embodiment, since the accuracy is not required at the joint portion of the belt-shaped rubber member, the uneven distribution of the weight (RF
V primary component) was small, and the uniformity was improved.

[0030]

As described above, according to the present invention, the uniformity of a pneumatic tire can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a band according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view of a secondary molding device according to one embodiment of the present invention.

FIG. 3 is an explanatory view showing a process of expanding a raw case in a secondary molding step.

FIG. 4 is a diagram illustrating a state in which a belt and a top tread are stacked on a BT drum.

FIG. 5 is a side view illustrating a state in which a belt and a top tread are wound around a BT drum.

FIG. 6 is a diagram illustrating a state in which a top tread and the like are laminated on a raw band.

FIG. 7 is a schematic sectional view showing a raw tire.

FIG. 8 is an explanatory diagram showing a state in which a top tread and the like are laminated on a raw band according to a conventional example.

[Description of Signs] 10 Beads 12 Side tread 14 Raw case 20 Top tread 24 BT drum (drum) 26 Start end 28 End

Claims (4)

[Claims] 1. A method for manufacturing a pneumatic tire, comprising a step of forming an annular top tread by winding a belt-shaped rubber member around two times. 2. The method for manufacturing a pneumatic tire according to claim 1, wherein in the step, the positions of the start end and the end of the belt-shaped rubber member wound around two turns are made coincident in the circumferential direction. 3. The method of manufacturing a pneumatic tire according to claim 2, wherein, in the step, the start and end of the belt-shaped rubber member are tapered in the circumferential direction. 4. A pneumatic tire formed by the method for manufacturing a pneumatic tire according to claim 1.