JPH1128915A - Pneumatic tire and its forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire and its forming method which are capable of reducing the weight, improving the uniformity, and increasing clamping force of bead parts in relation to the rim. SOLUTION: A carcass layer 2 is laid over between a pair of right and left bead cores 3, 3 formed of bead wires 7. In this case, the bead wires 7 are continuously wound in the tire-circumferential direction to be laminated from inside to outside in the crosswise direction of the tire to form the bead core 3, and the carcass layer 2 is engagingly locked to the bead core so that its end part across the tire-width is put between the layers of the laminated bead wires 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic tire having a carcass layer mounted between a pair of right and left bead cores and a method of molding the tire, and more particularly, to reducing the weight of the tire and improving uniformity. In addition, the present invention relates to a pneumatic tire and a method for molding the pneumatic tire, which can increase a tightening force of a bead portion on a rim.

[0002]

2. Description of the Related Art Generally, a carcass layer of a pneumatic tire has a structure to be locked between a pair of left and right bead cores.
Both ends in the tire width direction are folded back from the inside of the tire to the outside so as to enclose the bead filler on the outer peripheral side of the bead core. One of the reasons for winding up the end of the carcass layer greatly is
This is because when the internal pressure is applied during the vulcanization molding of the unvulcanized tire to expand the diameter (lift), the lifted portion shifts so that the rolled-up portion is drawn inside the tire, so that a clearance is secured.

However, there is a problem in that securing a long winding portion causes a corresponding increase in tire weight, and a reduction in uniformity due to displacement of a carcass layer during vulcanization molding. Further, when the reinforcing layer is provided along the carcass layer in the bead portion, the reinforcing layer is shifted together with the carcass layer, which has an adverse effect on durability and the like. Furthermore, in this winding structure, since the carcass tension acts to expand the diameter of the bead core, there is a problem that the fastening force of the bead portion to the rim is reduced.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire and a molding method for the same, which are capable of reducing the weight and improving the uniformity and increasing the tightening force of the bead portion to the rim. Is to do.

[0005]

According to the present invention, there is provided a pneumatic tire in which a carcass layer is mounted between a pair of left and right bead cores made of a bead wire. The bead core is formed so as to be continuously wound from the inside in the tire radial direction to the outside in the direction, and the end portion of the carcass layer in the tire width direction is sandwiched between the layers in which the bead wire is being stacked and wound. It is characterized by being locked to.

Further, in the method of forming a pneumatic tire according to the present invention for achieving the above object, an unvulcanized rubber sheet is wound on both left and right sides on the outer periphery of a forming drum, and bead wires are continuously laminated on the outer periphery. It is characterized in that a pair of left and right bead cores are formed by winding, and an end of the carcass layer in the tire width direction is wound in the middle of the lamination.

As described above, since the end portion in the tire width direction of the carcass layer is wound between the layers being continuously wound so that the bead wire is continuously laminated in the tire circumferential direction from the inner side to the outer side in the tire radial direction, a large size is obtained. Since the position of the carcass layer is stabilized by the tightening force, the uniformity can be improved, and the weight can be reduced because the conventional winding portion is not required. Further, since the bead core is formed simultaneously with the winding of the carcass layer in the same molding step of the unvulcanized tire, the productivity can be improved.

Further, in the pneumatic tire of the present invention, when the vehicle is running with the internal pressure applied, the carcass tension is applied only to the outer layer side of the bead core, so that the carcass tension does not impair the fastening force of the bead portion to the rim. Conversely, if a carcass tension is applied to the outer layer side, the bead wire is continuous between the outer layer side and the inner layer side, so that the effect of further increasing the tightening force on the rim on the inner layer side is achieved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention as a determination surface on only one side from the equatorial plane. In FIG. 1, a carcass layer 2 made of a carcass cord is arranged between a pair of left and right bead portions 1 and 1 at a cord angle of about 90 ° with respect to the tire circumferential direction. Both ends in the direction are locked to the bead core 3 respectively. A bead filler 4 made of hard rubber is provided on the outer periphery of the bead core 3. Outside the carcass layer 2 in the tread portion 5, two belt layers 6 made of a steel cord are arranged so that the cords intersect each other between the layers.

The bead core 3 is formed by continuously winding a bead wire 7 made of a steel wire or the like a plurality of times in a layered manner in the tire circumferential direction. The winding of the bead wire 7 may be performed in a single unit, or a plurality of wires may be arranged in parallel to form a band. The bead core 3 is formed so as to be divided into an inner layer 3a and an outer layer 3b in the tire radial direction with the end of the carcass layer 2 interposed therebetween, and the bead wire 7 is continuous from the inner layer 3a to the outer layer 3b. As described above, the end portion in the tire width direction of the carcass layer 2 sandwiched between the inner layer 3a and the outer layer 3b in which the bead wire 7 is continuous between the two layers has a folded portion with its tip end being the end of the outer surface of the bead core 3. Without providing, bead core 3
It is locked to.

The end of the carcass layer 2 is preferably sandwiched within the width of the bead core 3 as shown in the figure, but may extend outside the bead core 3 if it has a small length. However, as the protruding length, when it is turned outward from the outer surface of the bead core 3 in the tire radial direction,
It is preferable to limit the length to the outer peripheral surface of the bead core 3.

Next, a method of forming the above-described pneumatic tire will be described. First, as shown in FIGS. 3 (a) and 3 (b), an unvulcanized rubber sheet 9 serving as a rim cushion is wound around the outer periphery of both ends of a cylindrical forming drum D, and a plurality of belts are wound around the outside thereof. The inner layer 3a of the bead core 3 laminated in layers is formed by continuously winding the aligned bead wires 7. When the bead core 3 is composed of one bead wire 7, the bead core 3 can be formed in a layer by reciprocating the bead wire 7 in the drum axis direction with the rotation of the forming drum D.

Next, as shown in FIGS. 4A and 4B, the bead wire 7 is continuously wound while the carcass layer 2 is wound around the circumference of the drum 3 substantially by one circumference of the drum. At this time, the width of the carcass layer 2 may be substantially equal to the distance to the outside of both bead cores 3. Further, the forming drum D is rotated, and a bead wire 7 is continuously wound around the outer periphery of the carcass layer 2 to form an outer layer 3b of the bead core 3 as shown in FIGS.

Thereafter, in the same manner as in the conventional pneumatic tire manufacturing method, a primary green tire is formed by attaching a bead filler or the like, and the central portion in the width direction of the primary green tire is expanded, and then the crown portion is formed. A secondary green tire is formed by adhering a belt layer, tread rubber, or the like on the outer periphery of the tire. Then, by inserting the secondary green tire into a mold and performing vulcanization molding, a pneumatic tire as shown in FIG. 1 can be obtained.

According to the present invention, the bead wire 7 is continuously wound in layers in the circumferential direction of the tire to form the bead core inner layer 3a.
The end of the carcass layer 2 is wound around the bead core inner layer 3a together with the bead wire 7 without cutting the bead wire 7, and the bead core outer layer 3b is formed by winding the bead wire 7 alone. In this way, by wrapping both ends of the carcass layer 2 between the inner layer 3a and the outer layer 3b of the bead core 3, the position of the carcass layer 2 can be stabilized. Further, even if a lift tension is applied during vulcanization molding, it is difficult for both ends of the carcass layer 2 to shift, so that the uniformity can be improved.

In addition, the width of the carcass layer 2 is made substantially equal to the width of the pair of left and right bead cores 3 and 3, and since there is no rolled-up portion that is folded back to the outside of the bead core 3 as in the prior art, the weight can be reduced. Further, the bead core 3 is formed simultaneously with the formation of the primary green tire by continuously winding the bead wire 7 together with the carcass layer 2 on the outer periphery of the forming drum D, so that the productivity can be improved.

Furthermore, even if tension is generated in the carcass 2 when the tire is inflated during use of the tire, the carcass tension is applied only to the outer layer 3a of the bead core 3, so that the tightening force of the bead portion 1 on the rim due to the carcass tension. Does not hurt. However, the bead wire 7 is not
From the outer layer 3a to the outer layer 3a, when the outer layer 3a is pulled radially outward by the carcass tension, the inner layer 3b acts to further increase the tightening force on the rim.

FIG. 2 illustrates a pneumatic tire according to another embodiment of the present invention. In FIG. 2, the bead core 3 is configured by continuously winding a bead wire 7 a plurality of times in a layered manner in the tire circumferential direction. The bead core 3 includes an inner layer 3a and an intermediate layer 3 in the tire radial direction.
c and the outer layer 3b, the bead wire 7 is formed from the inner layer 3a through the intermediate layer 3c to the outer layer 3b.
It is continuous until. The end of the carcass layer 2 in the tire width direction is caught between the inner layer 3a and the intermediate layer 3c of the bead core 3.

The cord angle between the mid layer 3c and the outer layer 3b of the bead core 3 with respect to the tire circumferential direction is 10 ° to 30 °.
° reinforcing layer 8 is sandwiched. The reinforcing layer 8 has both ends bent back outward in the tire radial direction along both side surfaces of the bead core 3, and the bead filler 4 is sandwiched between both ends. As a reinforcing cord of the reinforcing layer 8, an organic fiber cord such as a nylon cord or a polyester cord, a steel cord or the like can be used.

When manufacturing the pneumatic tire, both ends of the carcass layer 2 are wound between the inner layer 3a and the intermediate layer 3c of the bead core 3 in the same manner as in the steps of FIGS. Of the carcass layer 2
The reinforcement layer 8 is wound around a position corresponding to the bead portion 1 outside the above. Next, the bead wire 7 is further wound around the outer periphery of the reinforcing layer 8 so that the outer layer 3 of the bead core 3 is formed.
b is formed. Then, a primary green tire can be formed by folding the outer end of the reinforcing layer 8 inside the tire so as to sandwich the bead filler 4 between both ends of the reinforcing layer 8.

With the pneumatic tire configured as described above, substantially the same effects as in the above-described embodiment can be obtained, and
By providing the reinforcing layer 8 having a cord angle of 10 ° to 30 ° with respect to the tire circumferential direction outside the carcass layer 2, it is possible to improve the steering stability. In addition, since the reinforcing layer 8 is wound between the layers of the bead core 3, even if a lift tension is applied at the time of vulcanization molding, the reinforcing layer 8 hardly shifts, so that it is possible to prevent deterioration in durability and the like.

In each of the above embodiments, the carcass layer is formed of one
Although the case in which the layers are provided has been described, in the present invention, the carcass layer can be a plurality of layers of two or more layers. When a plurality of carcass layers are provided, the bead cores 3 may be formed in layers according to the number of carcass layers.

[0023]

EXAMPLE A conventional tire 1 having a tire size of 205 / 55R16 and a different bead structure as described below was used.
2 and the tire of the present invention. Conventionally, both ends in the tire width direction of the tire carcass layer are wound up around the bead core from the inside of the tire to the outside. The height of the winding end of the carcass layer from the inner end of the bead core is 7
It was 5 mm.

Tire of the Invention As shown in FIG. 1, a bead core is formed by continuously laminating and winding a bead wire from the inner side to the outer side in the tire radial direction in the tire circumferential direction. The end of the carcass layer in the tire width direction was sandwiched. For these test tires, by the following test method,
The uniformity and weight were evaluated, and the results are shown in Table 1.

Uniformity : Radial force variation (RFV) was measured for each test tire in accordance with the uniformity test method for automotive tires of JASO C607. The evaluation results are shown by an index with the conventional tire being 100. The smaller the index value, the better the uniformity.

Weight: The weight of the bead portion of each test tire was measured. The evaluation results are shown by an index with the conventional tire being 100. The smaller the index value, the lighter the weight. As is clear from Table 1, the tire of the present invention was superior in uniformity and lighter than the conventional tire.

[0027]

As described above, according to the present invention, a bead core is formed by continuously laminating and winding a bead wire from the inner side to the outer side in the tire radial direction in the tire circumferential direction. By locking the carcass layer so that the end in the tire width direction is sandwiched between the layers in the middle of turning, the position of the carcass layer is stabilized by a large tightening force, so that it is possible to improve the uniformity,
Further, since a conventional winding portion is not required, the weight can be reduced, and the fastening force of the bead portion to the rim can be increased.

[Brief description of the drawings]

FIG. 1 is a meridian sectional view illustrating a pneumatic tire according to an embodiment of the present invention.

FIG. 2 is a meridional sectional view illustrating a pneumatic tire according to another embodiment of the present invention.

3A is a perspective view showing one step of a method for manufacturing the pneumatic tire shown in FIG. 1, and FIG. 3B is a side view thereof.

4A is a perspective view showing one step of the method for manufacturing the pneumatic tire shown in FIG. 1, and FIG. 4B is a side view thereof.

5A is a perspective view showing one step of the method for manufacturing the pneumatic tire shown in FIG. 1, and FIG. 5B is a side view thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead part 2 Carcass layer 3 Bead core 4 Bead filler 7 Bead wire 8 Reinforcement layer 9 Unvulcanized rubber sheet

Claims (5)

[Claims] 1. A pneumatic tire having a carcass layer mounted between a pair of left and right bead cores made of a bead wire, wherein the bead wire is continuously laminated and wound in the tire circumferential direction from inside to outside in the tire radial direction. A pneumatic tire in which the bead core is formed in such a manner that the carcass layer is interposed between layers of the bead wire being stacked and wound so as to sandwich an end in the tire width direction. 2. The pneumatic tire according to claim 1, wherein an end of the carcass layer in a tire width direction is sandwiched within a width of the bead core. 3. A cord angle of 10 ° to 30 ° with respect to the tire circumferential direction at a position radially outside the tire in the tire radial direction from a position where an end of the carcass layer is sandwiched between layers in which the bead wire is being stacked and wound. 3. The pneumatic tire according to claim 1, wherein a reinforcing layer is sandwiched, both ends of the reinforcing layer are respectively turned outward in the tire radial direction along both side surfaces of the bead core, and a bead filler is sandwiched between the both side portions. 4. 4. An unvulcanized rubber sheet is wound around the left and right sides of the outer periphery of a forming drum, and a bead wire is continuously wound around the outer periphery thereof to form a pair of right and left bead cores. And a method of molding a pneumatic tire in which the end portion in the tire width direction of the carcass layer is involved. 5. A reinforcing layer having a cord angle of 10 ° to 30 ° with respect to the tire circumferential direction is wound around the carcass layer in the middle of the laminating winding, following the winding of the carcass layer at the end in the tire width direction. 5. The method for forming a pneumatic tire according to 4.