JP2020152044A - Method for manufacture of tire for automatic two-wheeled vehicle and profile deck - Google Patents

Abstract

To provide a method for manufacture of a tire for automatic two-wheeled vehicle with improved handling performance.SOLUTION: Disclosed is a method for manufacture of a tire 1 for automatic two-wheeled vehicle, of which a tread part is curved into a circular arc shape which is convex outward in a radial direction of the tire. This method includes a molding process S1 in which a green tire is molded, and a vulcanization process S2 in which the green tire is vulcanized. The green tire has a tread reinforcement layer 7 which is arranged in the tread part 2. The molding process S1 includes a step in which a belt-like ply 10 including plural reinforcement cords, which are juxtaposed, is spirally wound, thereby forming a tread reinforcement layer 7. In the vulcanization process S2, the green tire is inflated and vulcanized so that stretch of the reinforcement cord gradually increases toward a tire axial outer side from a tire equator C.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a tire for a motorcycle and a profile deck.

Patent Document 1 below describes a method for manufacturing a motorcycle tire having a tread portion curved in an arc shape that is convex outward in the radial direction of the tire. This manufacturing method includes a step of forming a raw tire and a step of vulcanizing and molding the raw tire. The step of forming the raw tire includes a tread reinforcing layer forming step for forming a tread reinforcing layer arranged in the tread portion. In the tread reinforcing layer forming step, a strip-shaped ply having a reinforcing cord coated with topping rubber is wound around the profile deck.

JP-A-2016-210305

Generally, in such a motorcycle tire, since the tread portion is curved in an arc shape that is convex outward in the radial direction of the tire, the tire in which the reinforcing cord arranged on the outer side in the tire axial direction in the strip-shaped ply is located. The circumference is larger than the tire circumference where the reinforcing cord arranged inside in the tire axial direction is located. On the other hand, the length (perimeter) of each reinforcing cord in the strip-shaped ply is the same. Therefore, the binding force of the reinforcing cord on the inner side in the tire axial direction in the strip-shaped ply is larger than the binding force on the reinforcing cord on the outer side in the tire axial direction in the strip-shaped ply. As described above, since the binding force of each reinforcing cord in the strip-shaped ply is different, there is a problem that the rigidity of the tread reinforcing layer cannot be increased and excellent handling performance cannot be exhibited.

The present invention has been devised in view of the above problems, and an object of the present invention is to provide a method for manufacturing a tire for a motorcycle with improved handling performance and a profile deck used in this manufacturing method.

The present invention is a method for manufacturing a tire for a motorcycle in which the tread portion is curved in an arc shape convex outward in the radial direction of the tire, the troid-shaped carcass and the tire radial outer side and the tread portion of the carcus. Including a molding step of molding a raw tire having a tread reinforcing layer arranged inside the tire and a vulcanization step of vulcanizing the raw tire, the molding step is topped with a plurality of parallel reinforcing cords. The vulcanization step includes a step of spirally winding a strip-shaped ply coated with rubber to form the tread reinforcing layer, and the vulcanization step is such that the stretch of the reinforcing cord gradually increases from the tire equatorial line to the outside in the tire axial direction. In addition, the raw tire is expanded and vulcanized.

In the method for manufacturing a tire for a motorcycle according to the present invention, the tread reinforcing layer includes a crown region and a pair of shoulder regions on both outer sides thereof, and in the vulcanization step, the tread reinforcing layers are adjacent to each other in the strip-shaped ply. It is desirable that the distance between the reinforcing cords to be formed is smaller than the distance between the reinforcing cords adjacent to each other in the band-shaped ply in the crown region.

In the method for manufacturing a tire for a motorcycle according to the present invention, in the molding step, the strip-shaped ply is wound around the outer peripheral surface of the profile deck, and in the vulcanization step, the tread reinforcing layer is arranged on the outermost side in the tire axial direction. It is desirable that the tire radial distance of the stretch of the reinforcing cord is 0.012 times or less the outermost diameter of the profile deck.

The present invention is a profile deck used in the method for manufacturing a tire for a motorcycle according to any one of claims 1 to 3, and has an outer peripheral surface on which the strip-shaped ply is spirally wound.

The present invention is a method for manufacturing a motorcycle tire that is curved in an arc shape that is convex outward in the radial direction of the tire. The manufacturing method of the present invention includes a molding step of molding a raw tire having a tread reinforcing layer and a vulcanization step of vulcanizing the raw tire. The molding step includes a step of spirally winding a strip-shaped ply coated with a topping rubber around a plurality of parallel reinforcing cords to form the tread reinforcing layer. In the forming step, a large binding force acts on the reinforcing cord on the inner side in the tire axial direction in the strip-shaped ply as compared with the reinforcing cord on the outer side in the tire axial direction in the strip-shaped ply.

In the vulcanization step, the raw tire is expanded and vulcanized so that the stretch of the reinforcing cord gradually increases from the equator of the tire to the outside in the axial direction of the tire. As a result, in the vulcanization step, the reinforcing cord on the inner side in the tire axial direction in the strip-shaped ply moves to the outer side in the tire axial direction where the tire circumference is small because a larger binding force is generated. Further, in the vulcanization step, a tensile force acts on the reinforcing cord on the outer side in the tire axial direction in the strip-shaped ply due to a large binding force of the reinforcing cord on the inner side in the tire axial direction, and the tire shaft is subjected to the stretch. Moved inward in the direction. As a result, the distance between the adjacent reinforcing cords in the strip-shaped ply becomes small, and the difference in the binding force of each reinforcing cord becomes small, so that the rigidity of the tread reinforcing layer is increased. Therefore, the excellent motorcycle tire manufactured by the method for manufacturing a motorcycle tire of the present invention exhibits excellent handling performance.

It is a tire meridian sectional view of the motorcycle tire manufactured by the manufacturing method of one Embodiment of this invention. It is a perspective view of the reinforcement cord. (A) is an enlarged view of the crown region of FIG. 1, and (b) is an enlarged view of the shoulder region of FIG. It is another embodiment of a motorcycle tire manufactured by the manufacturing method of one embodiment of the present invention. It is a schematic diagram of the apparatus for molding a raw tire. It is a partially enlarged view of the upper part of the apparatus of FIG. It is sectional drawing which shows a part of a vulcanization die. It is a schematic diagram near the tread end of the tire after vulcanization. It is a schematic diagram of the apparatus for molding the raw tire of another embodiment. FIG. 9 is a partial cross-sectional view of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a tire meridian in a normal state of a tire 1 manufactured by a method for manufacturing a motorcycle tire (hereinafter, may be simply referred to as a “tire”) 1 showing an embodiment of the present invention. .. FIG. 1 shows, for example, a tire 1 that is suitably mounted on a motorcycle called a naked bike. The present invention is not limited to such an aspect, and various motorcycle tires 1 can be manufactured.

The "normal state" is a no-load state in which the tire 1 is rim-assembled on a normal rim (not shown) and is filled with a normal internal pressure. Unless otherwise specified in the present specification, the dimensions of each part of the tire 1 are values measured in a normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire 1 is based. For example, "standard rim" for JATMA and "Design Rim" for TRA. , ETRTO is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which Tire 1 is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS" The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

In the tire 1 of the present embodiment, the tread portion 2 is curved outward in the radial direction of the tire in an arc shape. Such a tire 1 can obtain a sufficient ground contact area even when turning with a large camber angle. The tire axial distance between the tread ends 2t and 2t of the tread portion 2 is the tread width TW. In the tire 1 of the present embodiment, the tread width TW is formed as the maximum width in the tire axial direction.

Inside the tire 1 of the present embodiment, a toroid-shaped carcass 6 and a tread reinforcing layer 7 arranged on the outer side of the carcass 6 in the tire radial direction are provided. The tire 1 includes, for example, a tread rubber 2G forming the tread surface 2a of the tread portion 2, a sidewall rubber 3G forming the outer surface of the sidewall portion 3, an inner liner rubber 8 forming the inner cavity surface 1n of the tire 1, and the like. I'm out.

The carcass 6 of the present embodiment is composed of one carcass ply 6A. The carcass ply 6A includes, for example, a main body portion 6a extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a folded-back portion 6b connected to the main body portion 6a and folded back by the bead core 5.

The tread reinforcing layer 7 is composed of at least one ply. The tread reinforcing layer 7 of the present embodiment is formed of a belt layer 9 composed of one belt ply 9A. In the tread reinforcing layer 7 of the present embodiment, both outer ends 7e and 7e in the tire axial direction are located in the vicinity of the tread end 2t. The length Tb in the tire axial direction between the outer ends 7e and 7e of the tread reinforcing layer 7 is preferably 70% to 95% of the tread width TW. The tread reinforcing layer 7 may have a belt layer 9 and a band layer (not shown) arranged on the outer side of the belt layer 9 in the tire radial direction.

The tread reinforcing layer 7 has, for example, a crown region Cr, a pair of middle regions Mi and Mi, and a pair of shoulder regions Sh and Sh. The crown region Cr includes, for example, the tire equator C, and is a region that comes into contact with the ground when traveling straight ahead. In the present embodiment, the crown region Cr is a region of 30% of the tread periferi length Lt centered on the tire equator C. In the present embodiment, the shoulder region Sh is an region inside from the outer end 7e in the tire axial direction, and is a region that comes into contact with the ground during turning where the camber angle is maximized. The shoulder region Sh is, for example, a region of 15% of the tread periferi length Lt inward in the tire axial direction from the tread end 2t. In the present embodiment, the middle region Mi is a region formed between the crown region Cr and the shoulder region Sh. The tread periferi length Lt is the length between the tread ends 2t and 2t measured along the shape of the tread surface 2a in the normal tire meridian cross section.

The tread reinforcing layer 7 is formed by spirally winding a strip-shaped ply 10. FIG. 2 is a perspective view of the strip-shaped ply 10. As shown in FIG. 2, the strip-shaped ply 10 is formed by coating a plurality of parallel reinforcing cords 11 with a topping rubber G. As the reinforcing cord 11, for example, an organic fiber cord such as nylon, polyester, rayon, or aromatic polyamide, a metal cord such as a steel cord, or the like is adopted. Although not particularly limited, the width w of the strip-shaped ply 10 is preferably about 2.5 to 6.0 mm, and the thickness t is preferably about 1.0 to 3.0 mm. The number of reinforcing cords 11 arranged on the strip-shaped ply 10 is preferably about 2 to 6, for example.

FIG. 3A is an enlarged view of the crown region Cr of FIG. 1, and FIG. 3B is an enlarged view of the shoulder region Sh of FIG. As shown in FIG. 3, in the present embodiment, the intervals Ws of the reinforcing cords 11 and 11 adjacent to each other in the strip-shaped ply 10 wound around the shoulder region Sh are adjacent to each other in the strip-shaped ply 10 wound around the crown region Cr. It is formed to be smaller than the distance Wc of the reinforcing cords 11 and 11 to be formed. As a result, in the shoulder region Sh, the difference in tire circumference where each reinforcing cord 11 in the strip-shaped ply 10 is located becomes small. Therefore, it is possible to prevent the difference in the binding force of each reinforcing cord 11 in the strip-shaped ply 10 from becoming large, and the shoulder region Sh has high rigidity. Therefore, the tire 1 manufactured by the manufacturing method of the present embodiment exhibits excellent handling performance.

In order to effectively exert the above-mentioned action, it is desirable that the spacing Ws of the reinforcing cords 11 in the shoulder region Sh is 90% or less of the spacing Wc of the reinforcing cords 11 wound around the crown region Cr. If the spacing Ws of the reinforcing cords 11 in the shoulder region Sh is excessively smaller than the spacing Wc of the reinforcing cords 11 wound around the crown region Cr, damage may occur due to contact between the reinforcing cords 11. Therefore, it is desirable that the spacing Ws of the reinforcing cords 11 in the shoulder region Sh is 60% or more of the spacing Wc of the reinforcing cords 11 wound around the crown region Cr. Although not particularly limited, the spacing Wc of the crown region Cr is preferably 0.8 to 2.0 mm. The spacing Ws of the shoulder region Sh is preferably 0.5 to 1.6 mm. The interval Wm of the middle region Mi is preferably 0.6 to 1.8 mm. Each interval is the shortest separation distance between the adjacent reinforcing cords 11 and 11.

In the motorcycle tire 1, the angle θ (shown in FIG. 1) of the tread surface 2a of the tread portion 2 with respect to the tire axial direction gradually increases from the tire equatorial line C toward the tread end 2t side. Therefore, in general, the angle of each band-shaped ply 10 forming the tread reinforcing layer 7 with respect to the tire axial direction tends to be larger as the band-shaped ply 10 outside the tire axial direction. Therefore, by making the distance Wa between the reinforcing cords 11 and 11 adjacent to each other in the strip-shaped ply 10 as small as the strip-shaped ply 10 arranged on the outer side in the tire axial direction, the difference in the binding force of each reinforcing cord 11 for each strip-shaped ply 10 Is smaller and handling performance is improved.

In the tire 1 of the present embodiment, the shoulder end Es is smaller than the crown end Ec. As a result, the mass of the tire 1 can be reduced while maintaining the rigidity of the shoulder region Sh. The shoulder end Es is the number of reinforcement cords 11 driven per unit periferi length in the shoulder region Sh. Crown Ends Ec is the number of reinforcement cords 11 driven per unit periferi length in the crown region Cr. In the present specification, the "periferi length" is a length measured along the shape of each region Sh and Cr (the inner edge 10e of the strip-shaped ply 10 in the radial direction of the tire) in the normal tire meridian cross section. Is.

FIG. 4 is a cross-sectional view of the tire meridian of another embodiment of the tire 1 manufactured by the manufacturing method of the present embodiment. As shown in FIG. 4, in the tire 1, for example, the shoulder end Es is equal to or higher than the crown end Ec. As a result, the shoulder region Sh has a rigidity equal to or higher than that of the crown region Cr, and thus exhibits high traction during turning. Further, since the rigidity of the crown region Cr is moderately relaxed, the stability of straight running is ensured, and the vehicle body is easily tilted from the upright state. Therefore, the tire 1 of this embodiment also has excellent handling performance.

Next, a manufacturing method for manufacturing such a tire 1 will be described. The tire 1 includes, for example, a molding step S1 for molding the raw tire 1a (shown in FIG. 7) and a vulcanization step S2 for vulcanizing the raw tire 1a. The tire 1 is obtained by vulcanizing the raw tire 1a.

The molding step S1 includes, for example, a first step of forming the raw tire base 1t, a second step of forming the tread reinforcing layer 7 on the outside of the raw tire base 1t, and outside the raw tire base 1t and the tread reinforcing layer 7. It includes a third step of forming the tread rubber 2G.

In the first step of this embodiment, a molding drum having a well-known structure (not shown) is used. In the first step, for example, a cylindrical carcass 6 (shown in FIG. 1) is formed on the molding drum, and bead cores 5 are attached to both ends thereof. Further, in the first step, tire components such as inner liner rubber 8 and sidewall rubber 3G are appropriately attached to the outside of the carcass 6 to form a cylindrical raw tire substrate 1t (shown in FIG. 5). ..

FIG. 5 is a schematic view of the shaping drum 15 used in the second step of the present embodiment. FIG. 6 is an enlarged view of the shaping drum 15. As shown in FIGS. 5 and 6, the raw tire substrate 1t formed in the first step is arranged on the shaping drum 15 of the present embodiment. The raw tire substrate 1t is transferred onto the shaping drum 15 by, for example, a transfer having a well-known structure (not shown).

In the present embodiment, the shaping drum 15 has a holding means 16 for holding the raw tire base 1t, a shaping means 17 for expanding the raw tire base 1t in a toroid shape, and a support shaft for supporting the holding means 16 and the shaping means 17. 18 is included.

In the present embodiment, the support shaft 18 is rotatably held by the base M. The support shaft 18 is rotated by, for example, an electric motor having a well-known structure provided on the base M.

The holding means 16 of the present embodiment has a beadlock ring 16a arranged apart from each other in the axial direction. Each of the beadlock rings 16a can be moved in and out of the axial direction and is supported by the support shaft 18. A seating portion 16b for holding the bead core 5 of the raw tire substrate 1t is provided at the radial outer end portion of the beadlock ring 16a.

In the present embodiment, the shaping means 17 includes a profile deck 19 in which the outer peripheral surface 19s approximates the tread surface 2a of the tread portion 2, and a diameter scaling means 20 for scaling the profile deck 19.

The profile deck 19 is composed of, for example, a plurality of segment-shaped members divided in the circumferential direction, and these are pressed by the scaling diameter means 20 and moved in the tire radial direction. The enlarged diameter state of the profile deck 19 is shown in FIG. 6, and the reduced diameter state of the profile deck 19 is shown in FIG.

In the present embodiment, the outer peripheral surface 19s of the profile deck 19 is provided with a first portion 22a in which the crown region Cr of the tread reinforcing layer 7 is arranged, a second portion 22b in which the middle region Mi is arranged, and a shoulder region Sh. Includes a third portion 22c to be made.

The outer peripheral surface 19s is curved in an arc shape that is convex outward in the radial direction, for example. Specifically, it is desirable that the outer peripheral surface 19s has a shape such that the stretch of the reinforcing cord 11 in the vulcanization step S2 gradually increases from the tire equator C to the outside in the tire axial direction. The stretch is the difference between the tire radial height position of the reinforcing cord 11 on the outer peripheral surface 19s in the second step and the tire radial height position of the same reinforcing cord 11 after vulcanization (tire radial distance). Is. The stretch of the reinforcing cord 11 closest to the tire equator C is preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less of the outer diameter of the tire 1 on the tire equator C. desirable. Further, the stretch of the reinforcement cord 11 closest to the outer end 7e of the tread reinforcing layer 7 is preferably 3.0% or less, and more preferably 2.0% or less of the outer diameter on the outer end 7e of the tire 1. , 1.5% or less is more desirable.

More specifically, it is desirable that the outer peripheral surface 19s is formed by a plurality of arcs having a smaller radius of curvature from a position at the tire equator C toward the outside in the tire axial direction. Although not particularly limited, it is desirable that the radius of curvature r1 of the arc of the first portion 22a is 40% to 50% of the tread width TW. Further, in the second portion 22b, it is desirable that the radius of curvature r2 of the arc is 45% to 65% of the tread width TW. Further, in the third portion 22c, it is desirable that the radius of curvature r3 of the arc is 60% to 100% of the tread width TW.

In the present embodiment, the diameter scaling means 20 has a well-known structure including an air bag 20a and a holding portion 20b for holding the air bag 20a. The air bag 20a is formed of a stretchable rubber cylinder, and a pressurized gas is introduced to expand outward in the radial direction of the tire to expand the profile deck 19. The holding portion 20b is, for example, a plate-shaped member fixed to the support shaft 18. The diameter expansion / contraction means 20 is not limited to such an embodiment, and a cylinder mechanism, a link mechanism, or the like may be used.

In the second step, first, the raw tire substrate 1t is expanded in a toroid shape between the bead cores 5 and 5. Specifically, while both bead lock rings 16a holding the bead core 5 are moved close to each other, the air bag 20a is expanded and the profile deck 19 is expanded, so that the raw tire substrate 1t is pushed up. .. As a result, the raw tire substrate 1t is curved in an arc shape that is convex outward in the radial direction of the tire along the outer peripheral surface 19s of the profile deck 19.

Next, the strip-shaped ply 10 is spirally wound around the raw tire substrate 1t. The strip-shaped ply 10 is continuously supplied on the outer peripheral surface 19s of the profile deck 19 by, for example, an applicator 21 having a well-known structure, and is wound around the raw tire substrate 1t. As a result, the tread reinforcing layer 7 of the raw tire 1a is formed.

In the present embodiment, the tread reinforcing layer 7 is formed by one strip-shaped ply 10. The spacing Wa (shown in FIG. 2) of the reinforcing cords 11 in the strip-shaped ply 10 at this time is formed equally along the longitudinal direction. The tread reinforcing layer 7 may be formed of a plurality of types of strip-shaped plies 10 having different intervals Wa of the reinforcing cords 11. For example, the middle region Mi is wound with a band-shaped ply 10 having a smaller spacing Wa of the reinforcing cord 11 than the crown region Cr, and the shoulder region Sh is wrapped with a strip-shaped ply 10 having a smaller spacing Wa of the reinforcing cord 11 than the middle region Mi. Is also good. In this case, three types of strip-shaped plies 10 having different intervals Wa of the reinforcing cords 11 are used. Further, in the present invention, four or more types of strip-shaped plies 10 having different intervals Wa of the reinforcing cords 11 may be used. The width w of the strip ply 10 is the same. In this state, a larger binding force acts on the reinforcing cord 11 on the inner side in the tire axial direction in the strip-shaped ply 10 than on the reinforcing cord 11 on the outer side in the tire axial direction in the strip-shaped ply 10.

Next, the third step is performed. In the third step of the present embodiment, for example, an extruded wide band-shaped tread rubber member having a trapezoidal cross section (not shown) is attached on the tread reinforcing layer 7, and the tread rubber 2G (shown in FIG. 1) is attached. Is formed. The tread rubber member is wound around the outer peripheral surface of the raw tire base 1t in the circumferential direction to form a tubular shape, and then is curved along the raw tire base 1t by a stitch roller having a well-known structure. In this way, the raw tire 1a is formed.

Next, the vulcanization step S2 is performed. FIG. 7 is a partial cross-sectional view of the vulcanization die 25 used in the vulcanization step S2. As shown in FIG. 7, the vulcanization mold 25 of the present embodiment has, for example, a vulcanization mold main body 26 having a tire molding surface 26a for molding the outer surface of the tire 1, and the tire molding surface 26a. It is equipped with a bladder 27 that pressurizes the raw tire 1a attached to the tire. The raw tire 1a is transferred into the vulcanization die 25 by a transfer device (not shown) having a well-known structure.

The vulcanization mold main body 26 includes, for example, an upper mold 28a that can be divided in the tire axial direction and a lower mold 28b. The vulcanization mold main body 26 has a cavity 26b inside, and the inner surface of the mold defining the cavity 26b constitutes a tire molding surface 26a.

The bladder 27 is formed of a well-known bag-shaped elastic sheet formed by using a rubber composition, a synthetic resin, or the like. The bladder 27 expands when a high temperature, high pressure gas or liquid is injected. As a result, the outer surface of the raw tire 1a is pressed against the tire forming surface 26a.

The tire molding surface 26a includes a tread molding surface portion 29A forming the tread surface 2a of the tread portion 2, a sidewall molding surface portion 29B forming the outer surface of the sidewall portion 3, and a bead molding surface portion 29C forming the outer surface of the bead portion 4. Includes.

In the vulcanization step S2 of the present embodiment, the raw tire 1a is expanded and vulcanized so that the stretch of the reinforcing cord 11 gradually increases from the tire equator C to the outside in the tire axial direction. As a result, a larger binding force is generated on the reinforcing cord 11 inside the strip-shaped ply 10 in the tire axial direction, so that the reinforcing cord 11 moves to the outside in the tire axial direction where the tire circumference is small. Further, the reinforcing cord 11 on the outer side in the tire axial direction in the strip-shaped ply 10 is moved inward in the tire axial direction along with the stretch due to a tensile force acting by the large binding force of the reinforcing cord 11 on the inner side in the tire axial direction. As a result, the distance Wa between the adjacent reinforcing cords 11 in the strip-shaped ply 10 becomes smaller, and the difference in the binding force of each reinforcing cord 11 becomes smaller, so that the rigidity of the tread reinforcing layer 7 is increased. Further, in such a vulcanization step S2, the spacing Ws (shown in FIG. 3) between the reinforcing cords 11 and 11 adjacent to each other in the strip-shaped ply 10 wound around the shoulder region Sh is the strip-shaped ply wound around the crown region Cr. A tread reinforcing layer 7 smaller than the distance Wc between the adjacent reinforcing cords 11 and 11 within 10 is formed.

The tread molded surface portion 29A has substantially the same profile as the profile of the tread surface 2a. Specifically, the tread molded surface portion 29A has a radius of curvature on the tire radial direction line x between the outer ends 7e and 7e of the tread reinforcing layer 7 rather than the arc of the outer peripheral surface 19s of the profile deck 19 (shown in FIG. 6). It is formed by a large arc of R. The rubber thickness of the tread rubber 2G gradually decreases from the crown region Cr toward the shoulder region Sh, and the stretch gradually increases from the crown region Cr toward the shoulder region Sh. Therefore, on the tire radial direction line x, the difference (R-r) between the radius of curvature R of the arc of the tread forming surface portion 29A and the radius of curvature r (shown in FIG. 6) of the arc of the outer peripheral surface 19s of the profile deck 19 is. , It is desirable to gradually decrease from the tire equatorial line C toward the outside in the tire axial direction. The difference (Rr) is preferably about 10 mm or less, for example.

FIG. 8 is a schematic view of the vicinity of the tread end 2t of the tire 1 after vulcanization. As shown in FIG. 8, the tire radial distance a of the stretch of the reinforcing cord 11 arranged on the outermost side in the tire axial direction of the tread reinforcing layer 7 after vulcanization is the outermost diameter D of the profile deck 19 (FIG. 8). It is desirable that it is 0.012 times (shown in 6). The outermost diameter D of the profile deck 19 is the outer diameter on the tire equator C of the profile deck 19 in the warped state in which the strip-shaped ply 10 is wound. As a result, the tire 1 of the above-described aspect can be obtained.

FIG. 9 is a schematic view of an apparatus used in the step of molding the raw tire 1a of another embodiment. As shown in FIG. 9, this embodiment includes a tread ring forming drum 30 and a shaping drum 31. The same components as those of the present embodiment are designated by the same reference numerals, and the description thereof will be omitted. The tread ring forming drum 30 forms, for example, a tread ring Tg (shown in FIG. 10) including the tread reinforcing layer 7 of the raw tire 1a and the tread rubber 2G. The shaping drum 31 of this embodiment expands the raw tire substrate 1t in a toroid shape. In this embodiment, the shaping drum 31 includes a holding means 16, an air bag 20a, a holding portion 20b, and a support shaft 18, and does not include a profile deck 19. For example, the shaping drum 31 holds the raw tire base 1t and bends the raw tire base 1t outward in the radial direction of the tire in an arc shape due to the expansion of the air bag 20a.

The tread ring forming drum 30 includes a profile deck 32 having a cylindrical outer peripheral surface 32s and a diameter-reducable profile deck 32, and a driving device (not shown) for rotationally driving the profile deck 32. The profile deck 32 includes, for example, a plurality of deck segments 32a divided in the circumferential direction. Each deck segment 32a is supported so as to be movable in and out in the radial direction by a diameter scaling means 33 (shown in FIG. 10) having a well-known structure using a link mechanism, a cylinder, or the like. The outer peripheral surface 32s of the profile deck 32 is formed in the same manner as the outer peripheral surface 19s of the profile deck 19 of the present embodiment.

FIG. 10 is a partial cross-sectional view of the profile deck 32. As shown in FIG. 10, the tread reinforcing layer 7 and the tread rubber 2G are formed on the outer peripheral surface 32s. Since the tread reinforcing layer 7 and the tread rubber 2G are formed in the same manner as in the present embodiment, the description thereof will be omitted. Then, the tread ring Tg is transferred to the shaping drum 31 by a transfer means having a well-known structure (not shown) and adhered to the outside of the raw tire substrate 1t to form the raw tire 1a (not shown).

Although the embodiments of the present invention have been described in detail above, it is needless to say that the present invention is not limited to the exemplary embodiments and can be modified into various embodiments.

A tire for a motorcycle was prototyped using the manufacturing method of the present invention and based on the specifications in Table 1, and the handling performance of the test tire was tested. The basic structure of the test tire is shown in FIG. The main common specifications and test methods for each test tire are as follows.
Reinforcement cord spacing before vulcanization Wa: 1.4 mm
“Stretching in the vulcanization process” in Table 1 represents an increase or decrease in the stretch of the reinforcing cord from the tire equator to the outer end of the tread reinforcing layer.

<Handling performance>
The following test vehicles equipped with each test tire were run on a test course on a dry asphalt road surface by a test rider. The handling performance due to the feeling of rigidity during straight running and turning at this time was evaluated by the sensuality of the test rider. The results are shown with a score of 100 for Comparative Example 1. The larger the number, the better.
Tires (front wheels, rear wheels): 120 / 70ZR17, 190 / 50ZR17
Rim (front wheels, rear wheels): MT3.50, MT6.00
Tire internal pressure (front wheels, rear wheels): 250kPa, 290kPa
Test vehicle: Motorcycle with a displacement of 1000cc

As a result of the test, the handling performance of the tire of the example is improved as compared with the tire of the comparative example.

1 Motorcycle tire 1a Raw tire 2 Tread part 7 Tread reinforcement layer 10 Band-shaped ply 11 Reinforcement cord C Tire equatorial line S1 Molding process S2 Vulcanization process

Claims (4)

A method for manufacturing a motorcycle tire in which the tread portion is curved in an arc shape that is convex outward in the radial direction of the tire.
A molding process for molding a raw tire having a toroid-shaped carcass and a tread reinforcing layer arranged on the outer side of the carcass in the radial direction of the tire and inside the tread portion.
Including a vulcanization step of vulcanizing the raw tire
The molding step includes a step of spirally winding a strip-shaped ply coated with a topping rubber on a plurality of parallel reinforcing cords to form the tread reinforcing layer.
In the vulcanization step, the raw tire is expanded and vulcanized so that the stretch of the reinforcing cord gradually increases from the equator of the tire to the outside in the axial direction of the tire.
How to manufacture tires for motorcycles. The tread reinforcement layer includes a crown region and a pair of shoulder regions on both outer sides thereof.
The first aspect of the vulcanization step, wherein the distance between the reinforcing cords adjacent to each other in the strip-shaped ply in each shoulder region is smaller than the distance between the reinforcing cords adjacent to each other in the strip-shaped ply in the crown region. How to manufacture tires for motorcycles. In the molding step, the strip-shaped ply is wound around the outer peripheral surface of the profile deck.
The claim that in the vulcanization step, the tire radial distance of the stretch of the reinforcing cord arranged on the outermost side in the tire axial direction of the tread reinforcing layer is 0.012 times or less the outermost diameter of the profile deck. The method for manufacturing a tire for a motorcycle according to 1 or 2. A profile deck used in the method for manufacturing a tire for a motorcycle according to any one of claims 1 to 3.
The strip-shaped ply has an outer peripheral surface around which it is spirally wound.
Profile deck.

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