JP5529599B2 - Lug tire and lug tire manufacturing method - Google Patents

Description

  The present invention relates to a tire with a lug that prevents occurrence of belt end separation and improves durability, and a method for manufacturing the tire with lug.

For vehicles used on rough terrain, such as construction vehicles and agricultural machines, in order to obtain traction on rough terrain, a lug-equipped tire with a lug inclined to the tire circumferential direction is applied to the tread. It is general (see, for example, Patent Document 1).
In such a lug-equipped tire, in order to suppress the occurrence of belt end separation, the outer inclined belt layer including the first cord and the inner inclined belt layer including the second cord are arranged offset in the tire width direction. In the tread shoulder region, only one of the outer inclined belt layer and the inner inclined belt layer is arranged, and the first cord and the second cord in the tread shoulder region extend in a direction crossing the extending direction of the lug. A lug-equipped tire has been proposed (see Patent Document 2).

JP 2004-299459 A JP 2009-286177 A

In the prior art described above, the angle of the cord of each inclined belt layer is restricted by the extending direction of the lug. However, since the cord angle of the inclined belt layer also affects various belt performances, the cord angle for satisfying the various belt performances does not necessarily match the cord angle for suppressing the belt end separation. Both performances could not be fully satisfied.
Accordingly, an object of the present invention is to provide a lug-equipped tire that prevents occurrence of belt end separation and improves durability and satisfies various belt performances, and a method of manufacturing the lug-equipped tire.

The gist of the present invention is as follows.
(1) A belt and a tread composed of at least one belt layer in which a cord extending incline with respect to the tire equatorial plane is covered with rubber on a radially outer side of a crown portion of a carcass straddling a toroidal shape between a pair of bead portions. In manufacturing a tire having a plurality of lugs extending from the tire equatorial plane toward the tread edge at intervals in the tread circumferential direction.
A rubber coating is applied to the end of the belt layer in the tire width direction that is separate from the belt layer and extends at an angle of 85 ° to 95 ° with respect to the extending direction of the concave portion of the mold that molds the lug. A method of manufacturing a tire with a lug, characterized in that it is covered with a protective layer and vulcanized.

(2) A belt and a tread composed of at least one belt layer in which a cord extending incline with respect to the tire equatorial plane is covered with rubber on a radially outer side of a crown portion of a carcass straddling a toroidal shape between a pair of bead portions. In the tire with lugs arranged on the tread with a plurality of lugs extending from the tire equatorial plane toward the tread edge at intervals in the circumferential direction of the tread,
The end of the belt layer in the tire width direction is separated from the belt layer, and is covered with a rubber-coated protective layer that extends at an angle of 85 ° to 95 ° with respect to the extending direction of the lug. A tire with lugs characterized by

  According to the present invention, it is possible to obtain a lug-equipped tire that prevents belt end separation and improves durability and satisfies various belt performances.

(A) is a figure which shows the tread pattern of the tire with a lug of this invention, (b) is a tire with a lug which shows the AA cross section in Fig.1 (a). It is a top view of the belt layer and protective layer of a tire with a lug of the present invention. It is a figure for demonstrating the curve of the code | cord | chord of the belt layer by the flow of an unvulcanized rubber. It is a figure for demonstrating the effect | action of this invention.

Hereinafter, the lug-equipped tire of the present invention will be described in detail with reference to the drawings.
Fig.1 (a) is a figure which shows the tread pattern of the tire with a lug of this invention, FIG.1 (b) is the width direction of the tire with a lug which shows the AA cross section of the tread in Fig.1 (a). It is sectional drawing.
As shown in FIG. 1 (a), the tire tread of the present invention includes lugs 11a, 11b, 11c, and 11d extending from the tire equatorial plane CL toward the tread end TE in an inclined manner with respect to the tire equatorial plane CL. Is formed. The lugs formed on the tread from the tire equatorial plane CL to one tread end TE are parallel to each other at intervals in the circumferential direction of the tread. That is, the lugs 11a and 11b on the left side of the tire equatorial plane CL are parallel to each other, and the lugs 11c and 11d on the right side of the tire equatorial plane CL are parallel to each other.
As shown in FIG. 1B, the tire 10 of the present invention is a pneumatic radial tire for agricultural tractors or agricultural vehicles, and a carcass 2 straddling a toroidal shape between a pair of bead portions in which a bead core 1 is embedded. And a tread 4 comprising a belt layer 3 in this order on the outer side in the tire radial direction of the crown portion of the carcass 2. Further, protective layers 5a and 5b are disposed so as to cover the end of the belt layer 3 in the tire width direction.
The carcass 2 has, for example, a general configuration in which a plurality of organic fiber cords such as polyester are arranged in parallel at regular intervals and covered with rubber, and is not limited to the illustrated example.

As shown in FIG. 2, the belt layer 3 has a configuration in which a plurality of cords 13 inclined with respect to the tire circumferential direction (tire equatorial plane CL) are arranged in parallel at regular intervals and covered with rubber. As the cord 13, a steel cord, an organic fiber cord or the like is used. The inclination angle θ1 of the cord 13 with respect to the tire axial direction is, for example, 70 ° ± 10 °, and preferably 60 ° or more.
The protective layer 5a that covers one of the end portions of the belt layer 3 in the tire width direction has a configuration in which a plurality of cords 15a are arranged in parallel at regular intervals and covered with rubber. The cord 15a is inclined at an angle θ3 of 85 ° to 95 ° with respect to the extending direction (longitudinal direction) of the lugs 11a and 11b located on the outer side in the tire radial direction of the protective layer 5a. Similarly, the protective layer 5b covering the other of the end portions in the tire width direction of the belt layer 3 has a configuration in which a plurality of cords 15b are arranged in parallel at regular intervals and covered with rubber. The cord 15b is inclined at an angle θ4 of 85 ° to 95 ° with respect to the extending direction (longitudinal direction) of the lugs 11c and 11d located on the outer side in the tire radial direction of the protective layer 5b. The protective layers 5a and 5b are rolled members including cords 15a and 15b made of textile or steel.

  As virtually indicated by a two-dot chain line in FIG. 2, lugs 11 a and 11 b that are inclined leftward with respect to the tire circumferential direction on the left side of the tire equatorial plane CL are spaced apart in the tire circumferential direction on the tread 4. A plurality of lugs 11c and 11d that are provided on the right side of the tire equator plane CL and are inclined to the right with respect to the tire circumferential direction are formed at intervals in the tire circumferential direction. In the illustrated example, the left lugs 11a and 11b and the right lugs 11c and 11d are arranged with a phase difference in the tire circumferential direction, but may be arranged in the same phase. Note that the inclination angle θ2 of the lugs 11a, 11b, 11c, and 11d with respect to the tire axial direction is 20 ° to 55 °.

Next, the manufacturing method of the tire 10 with a lug of this invention is demonstrated.
The raw tire used for manufacturing the lug-equipped tire 10 of the present invention is a conventional tire manufactured in that the protective layers 5a and 5b are arranged so as to cover the end of the belt layer 3 in the tire width direction. It is different from the raw tires used to do this.
On the other hand, the vulcanization mold for manufacturing the lug-equipped tire 10 has the same configuration as that of the conventional vulcanization mold for manufacturing the lug-equipped tire (the existing one can be used) and is used for forming a tread. A recess is formed on the inner peripheral surface corresponding to the lug indicated by the two-dot chain line in FIG.
In producing the lug-equipped tire 10 according to the present invention, the difference from the prior art is that the structure of the raw tire is different and that the direction when the raw tire is loaded into the vulcanization mold is characteristic.
The method for producing the lug-equipped tire 10 according to the present invention includes the extension direction of the recesses corresponding to the lugs 11a and 11b and the extension of the cord 15a of the protective layer 5a when the raw tire is loaded into the vulcanization mold. The angle θ3 formed by the direction is 85 ° to 95 °, and the angle θ4 formed by the extending direction of the recess corresponding to the lugs 11c and 11d and the extending direction of the cord 15b of the protective layer 5b is 85 ° to 95. The raw tire is loaded into a vulcanization mold and vulcanized and molded so that the temperature becomes 0 °.

When the raw tire is loaded into the vulcanization mold in this way and vulcanized, the raw tire also expands as the bladder expands in the mold, and the unvulcanized rubber on the outer surface of the tire flows and the inner surface of the mold Close contact with. A phenomenon in which the cord 13 of the belt layer 3 is bent by the flow of the unvulcanized rubber will be described with reference to FIG.
The unvulcanized rubber (not shown) around the lug 11a is, as indicated by the arrow B in FIG. 3A, from both sides in the width direction of the concave portion of the mold for molding the lug 11a toward the central portion of the concave portion. Flows in. As shown in FIG. 3 (a), when the cord 13 of the belt layer 3 is substantially parallel to the longitudinal direction of the lug 11a, the unvulcanized rubber flows in the direction of the arrow B, and as shown in FIG. In addition, the end of the cord 13 is curved. Then, the density of the cord 13a at the end of the belt layer 3 varies, and the end of the belt layer 3 meanders in a wave shape.
In addition, this phenomenon will be described with reference to FIGS. 3C and 3D in a cross-sectional view in the width direction of the lug 11a. When the green tire shown in FIG. 3C is vulcanized, the unvulcanized rubber in the lug 11a flows toward the tread surface side of the lug 11a as indicated by an arrow C in FIG. Then, the end of the belt layer 3 is curved outward in the tire radial direction by the flow of the unvulcanized rubber.
As described above, in the tire with lugs, when the raw tire is loaded into the vulcanization mold and vulcanized, the cord 13 of the belt layer 3 on the outermost radial direction is turned into the mold corresponding to the lug. Due to the rubber flow, the arrangement density is disturbed, so that the cords 13 of the belt layer 3 aligned at a constant interval before vulcanization become turbulent after vulcanization. As a result, belt end separation occurs, leading to a decrease in durability.

  Therefore, as shown in FIG. 4A, according to the present invention, the protective layer 5a in which the cord 15a extending at an angle of 85 ° to 95 ° with respect to the longitudinal direction of the lug 11a is embedded When the vulcanized rubber is disposed so as to cover the portion, the flow direction (arrow B) of the unvulcanized rubber is substantially the same as the longitudinal direction of the cord 15a, so the cord 15a of the protective layer 5a bends the cord 15a. It does not receive the force from unvulcanized rubber. Further, as shown in the cross-sectional view of the lug 11a in the width direction in FIG. 4B, the end of the belt layer 3 is covered with the protective layer 5a, so that the unvulcanized rubber in the lug 11a is the lug 11a. Even if it flows toward the tread surface side, the end of the belt layer 3 is not curved outward in the tire radial direction.

  Thus, by arranging the protective layers 5a and 5b, the cord 13 of the belt layer 3 can be extended at an arbitrary angle without being restricted by the extending direction of the lug 11a. The degree of freedom in design can be improved.

In the above embodiment, tires for agricultural tractors or agricultural vehicles have been exemplified. However, the present invention is not limited to agricultural vehicle tires, and construction vehicle tires and the like as long as they have a belt and lugs. It can also be applied to other types of tires.
The belt structure of the above embodiment is an example, and the belt may have two or more inclined belt layers in which the cords intersect each other, and may further have a circumferential belt layer.
For example, when two inclined belt layers are arranged in an overlapping manner, a protective layer may be arranged so as to cover the tire width direction end of the outer inclined belt layer, and the two inclined belt layers are arranged in the tire width direction. In the case where they are disposed offset, a protective layer is disposed so as to cover the ends of the tread shoulder region where only one layer is disposed on the outer inclined belt layer and the inner inclined belt layer in the tire width direction.

1 bead core 2 carcass 3 belt layer 4 tread 5 protective layer 10 tire 11 lug 13 cord 15 cord

Claims (2)

In the radial direction outside of the crown portion of the carcass straddling a toroidal shape between a pair of bead portions, a belt and a tread composed of at least one layer of a belt layer in which a cord extending obliquely with respect to the tire equatorial plane is rubber-coated, When manufacturing a tire in which a plurality of lugs extending from the tire equatorial plane toward the tread end are arranged in the tread at intervals in the circumferential direction of the tread,
A rubber coating is applied to the end of the belt layer in the tire width direction that is separate from the belt layer and extends at an angle of 85 ° to 95 ° with respect to the extending direction of the concave portion of the mold that molds the lug. A method of manufacturing a tire with a lug, characterized in that it is covered with a protective layer and vulcanized. In the radial direction outside of the crown portion of the carcass straddling a toroidal shape between a pair of bead portions, a belt and a tread composed of at least one layer of a belt layer in which a cord extending obliquely with respect to the tire equatorial plane is rubber-coated, In the tire with a lug in which a plurality of lugs extending from the tire equatorial plane toward the tread end are arranged in the tread at intervals in the circumferential direction of the tread.
The end of the belt layer in the tire width direction is separated from the belt layer, and is covered with a rubber-coated protective layer that extends at an angle of 85 ° to 95 ° with respect to the extending direction of the lug. A tire with lugs characterized by

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