JP2002361756A - Method for manufacturing pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the uniformity of the shape of a finished product tire, the reduction of a tire manufacturing cost and the curtailment of manufacturing manhour. SOLUTION: A green tire is manufactured by helically winding strips around the surface of a hard core (1) and thereby building a structural formation of an inner liner (2), a radial carcass (3), a belt (4), a belt reinforcing layer (5) and a tread rubber (7) in that order from the innermost side of a radial direction. This green tire is formed by vulcanization together with the hard core (1). In addition, an annular groove which is continuous in the peripheral direction with an accompanied annular constricted part of the radial carcass (3) is formed almost in the center area of the tread part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire having a wide and deep bottom annular groove that is radially depressed with a radial carcass in a substantially central area of a tread tread portion and is continuous in a circumferential direction. The present invention relates to a manufacturing method, and in particular, aims at making the shape of a product tire uniform and realizing both a reduction in tire manufacturing cost and a reduction in the number of manufacturing steps.

[0002]

2. Description of the Related Art In order to form a large annular groove in the central area of a tread, an inner liner, a radial carcass, a belt, a belt reinforcing layer, and a tread rubber are each provided with a constriction located at a substantially central portion in the width direction thereof. Need to be formed. Therefore, conventionally, in forming a green tire, such a constriction is formed by attaching a sheet member or an extruded member having a required shape in advance with an extruder on a first molding drum and a BT drum.

[0003] That is, conventionally, for example, a plurality of sheet-like belt layers are disposed in a substantially flat state on a BT drum having an annular recess at a substantially central portion in the axial direction, and the belt layers are provided. On the top, a sheet-like belt reinforcing layer, in which the cord extends substantially in the circumferential direction, is disposed under the tension control so that the central portion in the axial direction is constricted, and then, on the belt reinforcing layer, an extruded member is provided. While arranging the tread, pressing it against the belt reinforcing layer with a stitcher, preparing an integrated body of the belt layer, the belt reinforcing layer and the tread, combining this integrated body with the green case to form a green tire, and thereafter, The green tire was pressed against a mold, and vulcanization was performed so that required constrictions were formed in each of the belt and the belt reinforcing layer.

[0004] According to this, a constriction is formed in the belt, the belt reinforcing layer, and the like, so that an annular groove having a sufficient depth can be formed. Of the groove bottom was effectively prevented, and even when the tread was completely worn, the groove volume sufficient to provide the required wet drainage performance could be secured due to the presence of the constriction.

[0005]

However, when a green tire is molded in the above-described manner, a 1s having an annular recess is formed when the green case is molded.
Since a sheet-like inner liner and a radial carcass having a considerable width are arranged on a t-type drum, 1s
Wrinkles and the like are formed on the inner liner and the like corresponding to the annular recessed portion of the t-molding drum, which makes it difficult to make the shape of the green case and thus the shape of the product tire uniform in all directions. Since the first forming drum itself must have a complicated structure in order to increase the diameter, there is a problem that the tire manufacturing cost increases.

[0006] As described above, when a belt, a belt reinforcing layer, and the like are provided on a BT drum having an annular recess in molding a green tire, a sheet-like belt provided on the BT drum is used. Since the belt reinforcing layer and the like also have a considerable width, wrinkles and the like also occur in the belt and the like corresponding to the annular recessed portion of the BT drum, so that the shape of the green tire and, consequently, the shape of the product tire must be uniform in all directions. There is also a problem that is difficult.

Furthermore, according to the above aspect, when a green tire is molded, even when the inner surface shape of the green tire is slightly changed in design, all of the first molding drum, the BT drum, and the second molding drum are expected. Since the shape of the bladder must be changed to match the shape of the green tire, and the shape of the bladder used during vulcanization must be changed, the design change of these three types of drums and bladders has been a great deal. There is also a problem that it takes a lot of manufacturing man-hours.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem in the prior art. It is an object of the present invention to make a product tire shape uniform in all directions and to manufacture a tire. It is an object of the present invention to provide a method for manufacturing a pneumatic radial tire, which can reduce the cost and the number of manufacturing steps.

[0009]

According to the method of manufacturing a pneumatic radial tire of the present invention, an annular groove which is recessed in the radial direction together with the radial carcass and extends continuously in the circumferential direction is provided in the central area of the tread tread portion. In manufacturing a pneumatic radial tire, an inner liner, a radial carcass, and a belt are formed from a radially inner side by spirally winding a strip along a shape of the strip on a hard core having an annular recess at a substantially central portion in an axial direction. And a belt reinforcing layer, respectively, and bead cores are respectively disposed on both inner and outer sides in the radial direction so as to sandwich the radial carcass.Furthermore, a strip-shaped tread rubber is spirally wound radially outward of the belt reinforcing layer. Turn it to make a green tire with a concave groove at almost the center in the width direction. That after the green tire is hardcore by vulcanizing, in a substantially central zone of the tread portion, and forms an annular groove continuous in the circumferential direction with a constricted annular radial carcass. Here, among the tire constituent members such as the inner liner, those having a cord have the strip spiral winding direction set to the cord extending direction.

In this method of manufacturing a pneumatic radial tire, the tire components, that is, the inner liner, the radial carcass, the belt, the belt reinforcing layer, and the tread rubber are arranged on the hard core by spirally forming a strip along the shape of the hard core. By winding the strip, and among those tire constituent members having a cord, by spirally winding the strip along the cord extending direction, the tire corresponding to the annular recess portion of the hard core is formed. Since no wrinkles and the like are generated in the constituent members and vulcanization is performed together with the hard core during vulcanization, the product tire shape can be made uniform in all directions, and it is simpler than the conventional first molding drum. By using a hard core with a simple structure, tire manufacturing costs can be reduced

Further, in this method of manufacturing a pneumatic radial tire, when the inner surface shape of the green tire is slightly changed in design, unlike the conventional case, the three types of molding drums are not changed, It is sufficient to change only the hard core that conforms to the shape, and since bladders are not used during vulcanization, there is no need to consider changing the shape of the bladder, which reduces the number of manufacturing steps when changing the design of the inner surface shape of the green tire Can be achieved.

Therefore, in this method of manufacturing a pneumatic radial tire, the product tire shape is made uniform based on the spiral winding of the strip around the hard core, the tire manufacturing cost is reduced based on the simple structure of the hard core, and the green tire is manufactured. It is possible to reduce the number of man-hours required for changing the design of the inner surface shape.

[0013] In the method for manufacturing a pneumatic radial tire, more preferably, a tread center core is disposed radially outside the radial carcass at a portion corresponding to the annular recess of the hard core. Here, the tread center core refers to a highly rigid ring-shaped member in which a plurality of cords are wound in the circumferential direction. According to this, the desired shape of the tread center portion is securely held, and an annular groove having a sufficient depth can be formed.Moreover, when the internal pressure is filled into the product tire, the annular groove is formed. Protrusion of the groove bottom is effectively prevented, and even when the tread is completely worn, it is possible to secure sufficient groove volume to provide the required wet drainage performance due to the presence of the annular groove.

Preferably, the region where the belt and the belt reinforcing layer are provided is limited to a portion corresponding to both side portions of the annular recess of the hard core. According to such a method for manufacturing a pneumatic radial tire, the area where the belt and the belt reinforcing layer are disposed is limited to a portion corresponding to both side portions of the annular recess of the hard core, thereby further reducing the tire manufacturing cost. Can be. The desired combination of steering stability and ride comfort can be freely selected by subtly changing the arrangement area of the belt and the belt layer in accordance with the required rigidity of the tire tread portion.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view in the tire width direction showing an embodiment of the present invention.
Denotes a hard core, 2 denotes an inner liner, 3 denotes a radial carcass, 4 denotes a belt, 5 denotes a belt reinforcing layer, 6 denotes a bead core, 7 denotes a tread rubber, and 8 denotes a tread center core.

Here, in the central area of the tread tread,
In manufacturing a pneumatic radial tire having a radially recessed and circumferentially extending annular groove, a strip is formed along the shape on a hard core 1 having an annular recess at a substantially central portion in the axial direction. By spirally winding, the inner liner 2, the radial carcass 3, the belt 4 and the belt reinforcing layer 5 are respectively disposed from the radially inner side, and the radial carcass 3
The bead cores 6 are respectively disposed on both the inner and outer sides in the radial direction so as to sandwich the tread rubber, and the tread rubber 7 in a strip shape is spirally wound radially outward of the belt reinforcing layer 5,
A green tire having a concave groove in a substantially central portion in the width direction is formed. Thereafter, the green tire is vulcanized and molded together with the hard core 1, and is formed in a substantially central area of the tread tread portion with an annular constriction of the radial carcass 3 in a circumferential direction. A continuous annular groove is formed. Here, among the tire constituent members such as the inner liner 2, those having a cord, in this case, the radial carcass 3, the belt 4, and the belt reinforcing layer 5, the strip spiral winding direction is the cord extending direction.

Here, a tread center core 8 is disposed radially outside of the radial carcass 3 in a portion corresponding to the annular recess of the hard core 1, and further, a belt 4 and a belt reinforcing layer 5 are disposed in a region where the tread center core 8 is disposed. The hard core 1 is limited to a portion corresponding to both side portions of the annular recess.

According to the method for manufacturing a pneumatic radial tire as described above, the product tire shape is made uniform based on the spiral winding of the strip around the hard core 1, and the tire manufacturing cost is reduced based on the simple structure of the hard core 1. In addition, it is possible to reduce the number of manufacturing steps when the design of the inner surface shape of the green tire is changed. In the example shown in FIG. 1, the desired shape of the tread center portion is maintained based on the arrangement of the tread center core 8, and the tire manufacturing cost is reduced based on the limitation of the arrangement region of the belt 4 and the belt reinforcing layer 5. Further reduction can be realized respectively.

2 to 4 are cross-sectional views in the tire width direction showing other embodiments of the present invention. In the example shown in FIG. 2, the belt 4 and the belt 4 are not provided with a tread center core. The arrangement region of the reinforcing layer 5 is not limited to a portion corresponding to both side portions of the annular recess of the hard core 1,
In the example shown in FIG. 3, the tread center core is not provided, and the region where the belt 4 and the belt reinforcing layer 5 are provided is limited to portions corresponding to both side portions of the annular recess of the hard core 1. In the example shown in FIG. 4, the tread center core 8 is provided, and the region where the belt 4 and the belt reinforcing layer 5 are provided is not limited to the portions corresponding to both side portions of the annular recess of the hard core 1.

In any of the examples shown in FIGS. 2 to 4, the product tire shape is made uniform based on the spiral winding of the strip around the hard core 1, and the tire manufacturing cost is reduced based on the simple structure of the hard core 1. In addition, it is possible to reduce the number of manufacturing steps when changing the design of the inner surface shape of the green tire.

As shown in FIG. 4, when the tread center core 8 is provided and the region where the belt 4 and the belt reinforcing layer 5 are provided is not limited to a portion corresponding to both side portions of the annular recess of the hard core 1. Are located between the radial carcass 3 and the belt 4, between the belt 4 and the belt reinforcing layer 5, and between the radial carcass 3 and the belt reinforcing layer 5.
And any position between the tread rubber 7 and the tread rubber 7.

[0022]

As described above, according to the present invention, it is possible to make the shape of the product tire uniform and to realize both a reduction in tire manufacturing cost and a reduction in the number of manufacturing steps.

[Brief description of the drawings]

FIG. 1 is a sectional view in the tire width direction showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view in a tire width direction showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view in a tire width direction showing another embodiment of the present invention.

FIG. 4 is a sectional view in the tire width direction showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hardcore 2 Inner liner 3 Radial carcass 4 Belt 5 Belt reinforcement layer 6 Bead core 7 Tread rubber 8 Tread center core

Claims (3)

[Claims] In manufacturing a pneumatic radial tire having an annular groove which is radially recessed with a radial carcass in a central area of a tread tread portion and continuously extends in a circumferential direction, an annular ring is formed in a substantially central portion in an axial direction. On a hard core having a depression, by spirally winding a strip along the shape thereof, an inner liner, a radial carcass, a belt, a belt reinforcing layer, and a tread rubber are arranged from the radially inner side to form a green tire. Thereafter, the green tire is vulcanized and molded together with the hard core, and a circumferentially continuous annular groove is formed in a substantially central area of the tread tread with an annular constriction of the radial carcass, thereby producing a pneumatic radial tire. Method. 2. The method for manufacturing a pneumatic radial tire according to claim 1, wherein a tread center core is disposed radially outside of the radial carcass at a portion corresponding to the annular recess of the hard core. 3. The pneumatic radial tire according to claim 1, wherein an area where the belt and the belt reinforcing layer are provided is limited to a portion corresponding to both side portions of the annular recess of the hard core. Method.