JP2008055860A - Manufacturing method for pneumatic tire and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and inexpensively manufacture a belt layer 23 wherein the meandering of a reinforced cord at both ends in the axial direction is prevented. <P>SOLUTION: Since the central part in the axial direction of the belt layer 23 is bulged outward in the radial direction from the both end parts in the axial direction by a rubber member 42 disposed at the outside of a cylindrical BT drum 40, the clearance is provided between all area of a tread part and an inner surface of a vulcanized mold within the expansion rate of the belt layer 23 in the end of closing of the vulcanized mold, and in the result, the both end parts in the axial direction of the tread is not pushed in the inner side in the radial direction by the vulcanized mold. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to a method for manufacturing a pneumatic tire having a belt layer in which a high elastic modulus reinforcing cord extending substantially parallel to the tire equator is embedded, and a pneumatic tire.

    In recent years, various pneumatic tires have been proposed in the tire industry in order to deal with various problems. For example, in order to easily manufacture test tires for high-performance passenger cars used for wind tunnel experiments, etc., or for motorcycles In order to remarkably improve the traction and grip performance in a tire, a pneumatic tire in which a main belt layer is constituted only by a belt layer in which a high elastic reinforcement cord extending substantially parallel to the tire equator S is embedded is provided. Proposed.

  Here, such a pneumatic tire is manufactured by a method similar to that of a conventional pneumatic tire, that is, a strip of rubber-coated reinforcing cord is spirally formed on the outside of a cylindrical BT (belt tread) drum. After forming a cylindrical belt layer as a main belt layer, a BT (belt tread) band is formed by winding a tread around the outside of the belt layer, and manufactured using such a BT band. If it is going to become a vulcanized tire, meandering will generate | occur | produce in the reinforcement cord in the axial direction both ends of a belt layer. As a result, the circumferential rigidity at both axial ends of the belt layer is lowered, and the diameter growth at the tread edge during rolling of the tire cannot be sufficiently suppressed, and uneven wear and high speed due to abnormal heat generation of the tire are not possible. There was a problem that the durability deteriorated.

  The reason is that the outer peripheral surface (tread surface) of the tread portion of a pneumatic tire is generally curved with a certain radius of curvature (crown radius) so that the central portion in the axial direction bulges radially outward from both axial end portions. On the other hand, the cylindrical belt layer described above is strongly limited (up to about 3%) in the entire range by the reinforcement cord during vulcanization, so the outer diameter of the BT drum is increased. The inner diameter of the belt layer of the vulcanized tire must be substantially the same as the inner diameter of the belt layer.

  However, when trying to vulcanize a green tire having such a cylindrical belt layer, both tread ends of the green tire come into contact with the vulcanization mold and are pushed inward in the radial direction immediately before the vulcanization mold is closed. Then, as the vulcanization progresses, the tread center portion is expanded until it comes into contact with the vulcanization mold, so that the reinforcement cords are left at both axial end portions of the belt layer and meander.

For this reason, conventionally, in order to prevent the meandering of the reinforcing cords at both ends in the axial direction of the belt layer as described above, one of the methods for manufacturing a pneumatic tire described in Patent Document 1 below. A pneumatic tire is manufactured by a manufacturing method in which the part is replaced with a conventional manufacturing method.
JP-A-1-249429

  Here, a part of the manufacturing method described in Patent Document 1 is to enlarge the diameter of a forming drum so that the outer periphery of the forming drum is positioned radially outward from both axial end portions (molding). The outer periphery of the drum is curved so that the axial cross-sectional shape of the belt layer used as the product tire is substantially the same) and the outer side of the forming drum is covered with a high elastic modulus reinforcing cord. And a step of forming a belt layer in which a strip is spirally wound and an axially central portion thereof is located radially outward from both axial end portions.

    However, in the method for manufacturing a pneumatic tire partially using the method described in Patent Document 1 described above, the forming drum that provides a curved outer periphery is made of a metal such as aluminum or steel, and therefore different. When manufacturing different types of pneumatic tires, differently shaped molding drums are required, and the molding drums must be designed and manufactured for each type, resulting in high production costs for pneumatic tires. There was a problem of becoming.

  An object of the present invention is to provide a pneumatic tire manufacturing method and a pneumatic tire that can be manufactured easily and inexpensively while preventing meandering of reinforcing cords at both axial ends of the belt layer.

    For this purpose, a carcass layer extending in a toroidal shape, a belt layer disposed outside the carcass layer in the radial direction and embedded with a high elastic modulus reinforcing cord extending substantially parallel to the tire equator S, and a belt A pneumatic tire manufacturing method comprising a tread disposed radially outward of a layer, the step of closely placing a substantially cylindrical rubber member on the outside of a cylindrical forming drum, On the outside, a strip coated with rubber covering the reinforcing cord is spirally wound to form a substantially cylindrical belt layer, and the rubber member causes the central portion in the axial direction of the belt layer to be radially outward from both axial ends. Positioning the belt tread band on the outside of the belt layer, forming the belt tread band, and the belt tread on the radially outer side of the toroidal carcass layer. A step of forming a green tire by arranging the Ddobando, by providing a step of vulcanizing the green tire, can be achieved.

  In the present invention, a substantially cylindrical rubber member is disposed in close contact with the outside of a cylindrical forming drum, and then a strip coated with a high elastic modulus reinforcing cord on the outside of the rubber member is spirally wound to form a substantially cylindrical shape. A belt-shaped belt layer is molded, and the rubber member is arranged so that the axial central portion of the belt layer is positioned radially outward from both axial end portions. A gap within the range of the expansion rate of the belt layer can be provided between the inner surface (molding surface) of the vulcanization mold, and as a result, any part of the tread portion is vulcanized at the end of closing of the vulcanization mold. It is not pushed radially inward by the mold.

  As a result, the meandering of the reinforcing cords at both ends in the axial direction of the belt layer is effectively prevented, and the circumferential rigidity at both ends in the axial direction of the belt layer can be made strong. Moreover, when manufacturing different types of pneumatic tires, it is only necessary to closely contact a rubber member having a thickness and an axial length corresponding to the outside of the forming drum, and it is necessary to design and manufacture the corresponding forming drum. Disappear. As a result, the pneumatic tire can be easily manufactured and the manufacturing cost can be reduced.

  Further, when configured as described in claim 2, since the amount of rubber constituting the rubber member can be reduced, the manufacturing cost can be reduced and the manufacturing can be facilitated. According to the configuration described in Item 3, meandering generated in the reinforcing cords of the belt layer is prevented while preventing air from remaining between the outer surface of the tread portion and the inner surface of the vulcanization mold during vulcanization. It can be surely prevented.

  Further, if configured as described in claim 4, as the rubber member, it is possible to use a band-shaped rubber sheet having a uniform thickness that is easy to manufacture, and as a result, the rubber member can be easily manufactured, Production costs are low. Further, when the belt layer is formed on the outer side of the rubber member, the radius of curvature can be made closer to the radius of curvature of the belt layer of the pneumatic tire that is the product. The present invention is particularly suitable when the reinforcing cord is composed of an aromatic polyamide fiber as described in claim 6.

Embodiment 1 of the present invention will be described below with reference to the drawings.
1 and 2, reference numeral 11 denotes a pneumatic radial tire for a high-performance passenger car used for wind tunnel experiments and the like. Such a tire 11 simulates air resistance and air flow around the tire in the experiment. Used for. The tire 11 includes a pair of bead portions 13 in which bead cores 12 are embedded, a pair of sidewall portions 14 extending from the bead portions 13 substantially outward in the radial direction, and radially outer ends of the sidewall portions 14. And a tread portion 15 having a substantially cylindrical shape.

  The tire 11 has a carcass layer 18 that reinforces the sidewall portion 14 and the tread portion 15 by extending in a toroidal shape from one bead portion 13 to the other bead portion 13, and the carcass layer 18 has a width thereof. Both ends in the direction are folded around the bead core 12 from the inside to the outside. The carcass layer 18 includes at least one carcass ply 19 (here, one carcass ply 19), and extends in the carcass ply 19 in a substantially radial direction (inclined at an angle of 80 to 90 degrees with respect to the tire equator S). A number of organic fibers such as nylon and aromatic polyamide parallel to each other, or a carcass cord made of steel, in this case, a carcass cord 20 composed of organic fibers having a low elastic modulus (1500 to 3600 MPa). Buried.

  Reference numeral 23 denotes a belt layer disposed on the outer side in the radial direction of the carcass layer 18, and the belt layer 23 has substantially the same width as the tread width. The belt layer 23 is composed of at least one (here, one) belt ply 24. The belt ply 24 has a high elastic modulus (30000 MPa or more, extending substantially parallel to the tire equator S). A reinforcing cord 25 made of an aromatic polyamide fiber (preferably 40000 to 50000 MPa) is embedded. The reinforcing cord 25 may be made of steel, but the aromatic polyamide as described above is suitable for reasons such as weight reduction.

  If the belt layer 23 having a high but effective effect is provided on the tread portion 15 in this manner, the tread portion 15 is prevented from growing greatly in the radial direction due to centrifugal force during high-speed running. Is held in a predetermined shape even during high-speed rolling. Such a tire 11, that is, a tire 11 in which only the belt layer 23 as described above is disposed as a main belt layer is suitable for wind tunnel experiments and the like because it can withstand high-speed rolling while having a simple structure. is there. Further, the belt layer 23 as described above can also be applied to a tire for a motorcycle. In this case, the belt layer 23 bears most of the circumferential tension, so that the traction performance and the grip performance. Can be improved.

  28 is a pair of narrow reinforcing layers which are provided on the outer side in the radial direction of the belt layer 23 and are usually called layer layers. Here, the narrow reinforcing layers 28 are overlapped with both axial end portions of the belt layer 23 in this case. The layers 23 are arranged so as to straddle both ends in the axial direction. The narrow reinforcing layer 28 is composed of at least one, in this case, one narrow reinforcing ply 29, and inside each reinforcing ply 29 is nylon or aromatic that extends substantially parallel to the tire equator S. Reinforcing elements 30 made of organic fibers such as polyamide, here aromatic polyamide, are embedded therein.

  As a result, the circumferential rigidity of the tread end portion of the tire 11 becomes a higher value, and the diameter growth at the tread end portion of the tire 11 is strongly suppressed. 33 is a tread made of rubber disposed radially outward of the belt layer 23 and the narrow reinforcing layer 28. The outer surface (tread surface) of the tread 33 is continuous in the circumferential direction in order to improve drainage performance. Thus, a plurality of main grooves 34 extending in this case are formed. In addition, a large number of lateral grooves extending in the width direction or oblique direction may be formed on the outer surface of the tread 33. Reference numeral 35 denotes a side tread.

    Next, in order to manufacture such a tire 11, for example, a cylindrical band drum (not shown) that can be enlarged and reduced in diameter and is rotatable is rotated, and a belt-like inner liner, a carcass ply 19 and the like around it are rotated. Are supplied one after another from a supply means (not shown) and wound. Next, the diameter of the central portion of the band drum in the axial direction is increased to increase the diameter of the central portion in the axial direction of the carcass ply 19, and then a pair of bead cores 12 with stiffeners are attached to the outside of the carcass ply 19 by a bead supply means (not shown). It is supplied and set at a position where it contacts the step of the carcass ply 19. In this state, the carcass ply 19 that is axially outer than the bead core 12 is folded back inward in the axial direction using a folding bladder or the like, and a side tread 35 is attached to the outside of the folded portion. Thereby, a cylindrical green case is formed around the band drum.

  On the other hand, in parallel with the forming of the green case, the inner diameter of the green case is increased by a BT (belt tread) drum 40 as a forming drum having a cylindrical shape that can rotate and expand and contract as shown in FIG. A substantially cylindrical BT band 41 (belt tread band) having a larger diameter than the outer diameter is formed. In order to form such a BT band 41, first, the BT drum 40 is rotated, and at the central portion in the axial direction of the BT drum 40, the outer side in the radial direction is set regardless of the position in the width direction (axial position). A rubber sheet having a constant thickness and a substantially rectangular cross section is supplied from a sheet supply means (not shown) to form a wound rubber member. The rubber member 42 is made of rubber such as carcass ply coating rubber.

  Thus, the rubber member 42 disposed in close contact with the outer side of the BT drum 40 has a substantially cylindrical shape in which a hollow hole 43 extending in the axial direction is formed in the central portion, and in this case, has a cylindrical shape. Here, as described above, the thickness of the rubber member 42 wound around the BT drum 40 is constant regardless of the position in the axial direction. Therefore, a belt-like rubber sheet having a uniform thickness that is easy to manufacture is used as the rubber member 42. As a result, the rubber member 42 can be easily manufactured and the manufacturing cost is low.

  And, such a rubber sheet may be supplied to the BT drum 40 as it is immediately after forming a long rubber sheet having a constant thickness and a constant width by, for example, a calendar device, or after being molded as described above, It may be wound around a reel in a roll shape and then unwound from the reel and supplied to the BT drum 40 as necessary. Further, the rubber member 42 is formed into a cylindrical shape by another molding drum (not shown), and is then carried and transferred to the BT drum 40 by a conveying means so as to be closely attached to the outside of the BT drum 40. Also good.

  Next, a belt layer 23 covering at least the outer side in the radial direction of the rubber member 42 is supplied at least on the outer side in the radial direction of the rubber member 42 by supplying one or a small number of reinforcing cords 25 and winding it in a spiral shape. Mold. Here, in this embodiment, since the belt layer 23 is wider than the rubber member 42 (the axial length is increased), both end portions in the axial direction (both end portions in the width direction) of the belt layer 23 are rubber members 42. It is located on the axially outer side from both axial ends.

  As a result, the rubber member 42 is disposed only on the radially inner side of the central portion in the axial direction (the central portion in the width direction) of the belt layer 23, whereby the central portion in the axial direction of the belt layer 23 is radially outward. It bulges (projects) and is positioned radially outward from both axial ends. As a result, the belt layer 23 has a substantially cylindrical shape with a hat-shaped cross section. That is, in this embodiment, the outer diameter of the BT drum 40 is substantially the same as the inner diameter of both ends in the axial direction of the belt layer in the vulcanized tire, and is smaller than the outer diameter of the conventional BT drum described above. The rubber member 42 is disposed at the axial central portion of the BT drum 40, and the axial central portion of the wound belt layer 23 bulges outward in the radial direction. The outer diameter of the BT drum is substantially the same as the outer diameter of the BT drum, and is substantially the same as the defined inner diameter of the central portion in the axial direction of the belt layer in the product tire.

  Then, as described above, the belt layer 23 is wider than the rubber member 42, and both axial ends of the belt layer 23 extend outward in the axial direction from the rubber member 42, so that the axial central portion of the belt layer 23 is expanded. For example, by forming a belt layer having the same width as that of the rubber member on the outer side of the rubber member having a convex cross section, the central portion in the axial direction of the belt layer is more radial than the axial end portions. Compared to the case where the rubber member 42 is bulged outward, the amount of rubber constituting the rubber member 42 can be reduced, the manufacturing cost can be reduced, and the manufacturing can be facilitated. Further, when the rubber member 42 is molded by joining the rubber sheet at one place on the circumference, the joining work becomes easy.

  Next, a pair of narrow reinforcing layers 28 are wound in the radial direction of the belt layer 23 by winding a strip of rubber covering one or a small number of the reinforcing elements 30 so as to straddle both ends of the belt layer 23 in the axial direction. Mold outside. Thereafter, a belt-shaped tread 33 is supplied to the outside of the belt layer 23 and the narrow reinforcing layer 28 in the radial direction and is attached in a cylindrical shape. As a result, a substantially cylindrical BT band 41 including the rubber member 42, the belt layer 23, the narrow reinforcing layer 28, and the tread 33 is formed outside the BT drum 40.

  Next, after gripping both the green case and the BT band 41 from the outside in the radial direction by a conveying means (not shown) disposed between the band drum, the BT drum 40 and a shaping drum 47 described later, the band The diameter of the drum and the BT drum 40 is reduced, and the green case and the BT band 41 are transferred from the band drum and the BT drum 41 to the conveying means.

  Thereafter, the green case and the BT band 41 are simultaneously conveyed to the shaping drum 47 (see FIG. 4) by the conveying means. Next, the pair of bead supports 48 provided on the shaping drum 47 are enlarged in diameter, and the bead core 12 of the green case is supported from the inside in the radial direction, and then the substantially cylindrical BT band 41 is shaped by the conveying means. Transport to the position surrounding 47.

  Thereafter, by moving the pair of bead supports 48 inward in the axial direction, the pair of bead cores 12 are brought close to each other, and internal pressure is supplied into the green case between the bead cores 12 to deform the green case into a toroidal shape. Let At this time, since the substantially cylindrical BT band 41 is supplied and arranged in advance on the radially outer side of the green case, the green case is deformed into the toroidal shape on the radially outer side of the green case. The BT band 41 is affixed and the green tire 51 is formed. Note that the rubber member 42 closely adhered to the carcass layer 18 of the green tire 51 and the central portion of the belt layer 23 in the axial direction remains as they are.

  Next, after the green tire 51 is gripped from the outside in the radial direction by a conveying means (not shown) and taken out from the shaping drum 47, the upper side mold 54, the lower side mold 55, and the sector mold 56 as shown in FIG. Into the vulcanization mold 57. Thereafter, the vulcanization mold 57 is closed and a vulcanization medium is supplied into the vulcanization bladder 58, and the green tire 51 is vulcanized while being molded to obtain a pneumatic tire 11.

  Here, at the time of such vulcanization, the rubber constituting the rubber member 42 is easily stretched in the longitudinal direction because the carcass cord 20 in the carcass layer 18 receives the internal pressure from the vulcanization medium, and thus the carcass layer 18 Is pushed outward in the radial direction, and flows between the reinforcing cords 25 of the belt layer 23 and flows outward in the radial direction from the belt layer 23. For this reason, when the vulcanization is completed, the rubber member 42 hardly remains between the carcass layer 18 and the belt layer 23, so that the belt layer 23 in the vulcanized pneumatic tire becomes the carcass layer 18. The axial central portion is positioned radially outward from both axial end portions, and is curved in parallel with the carcass layer 18 with a substantially constant radius of curvature.

  Thus, after providing the rubber member 42 on the BT drum 40 having substantially the same diameter as the both axial ends of the belt layer of the vulcanized tire, the belt layer 23 wider than the rubber member 42 is formed outside thereof. Therefore, the central portion in the axial direction of the formed belt layer 23 is located radially outward from both end portions in the axial direction, and has substantially the same shape as the overall shape of the belt layer after vulcanization. As a result, the expansion rate range of the belt layer 23 between the entire tread portion 15 of the green tire 51 and the vulcanization mold 57, here, the inner surface 59 (molding surface) of the sector mold 56 when the vulcanization mold 57 is closed. An inner gap 60 is provided (see FIG. 5), and as a result, any part of the tread portion 15 is not pushed inward in the radial direction by the vulcanization mold 57 when the vulcanization mold 57 is closed.

  As a result, the meandering of the reinforcing cord 25 at both axial ends of the belt layer 23 is effectively prevented, and the circumferential rigidity at both axial ends of the belt layer 23 can be strengthened. Moreover, when manufacturing different types of pneumatic tires, it is only necessary to closely arrange the rubber member 42 having a thickness and an axial length corresponding to the outside of the BT drum 40, and the corresponding BT drum 40 is designed and manufactured. There is no need to do it. As a result, the pneumatic tire 11 can be easily manufactured, and the manufacturing cost can be reduced. Further, if the thickness and the axial length of the rubber member 42 as described above are changed, the expansion rate in the axial direction (width direction) of the belt layer 23 can be arbitrarily set without changing the outer diameter of the BT drum 40. You can also change the shape to control the shape.

  Here, when the axial length of the rubber member 42 is A (mm) and the axial length of the belt layer is B (mm), the length A is within the range of 0.75 to 0.85 times the length B. It is preferable that The reason is that when the length A is less than 0.75 times the length B, only a narrow range of the central portion in the axial direction of the belt layer 23 can bulge outward in the radial direction. This is because air may remain between the outer surface 15 and the inner surface 59 of the vulcanization mold 57 (sector mold 56), while the length A exceeds 0.85 times the length B. Then, both end portions in the axial direction of the belt layer 23 bulge outward in the radial direction within a considerable range, and there is a possibility that meandering may occur in a part of the reinforcing cord 25 in the both end portions in the axial direction of the belt layer 23. Because.

  Further, when the thickness of the rubber member 42 is C (mm) and the thickness of the belt layer is D (mm), the thickness C is preferably in the range of 0.9 to 2.0 times the thickness D. . The reason is that if the wall thickness C is less than 0.9 times the wall thickness D, the gap 60 between the axial center of the green tire 51 and the vulcanization mold 57 is within the range of expansion rate of the belt layer 23. In order to achieve this, the outer diameter of the BT drum 40 must be close to the outer diameter of the conventional BT drum. As a result, meandering occurs in the reinforcing cords 25 at both axial ends of the belt layer 23 of the vulcanized tire. On the other hand, when the wall thickness C exceeds 2.0 times the wall thickness D, the outer diameter of the BT drum 40 becomes too small, and the outer surface of both ends in the axial direction of the tread portion 15 at the end of vulcanization. This is because air may remain between the inner surface 59 of the vulcanization mold 57 (sector mold 56).

    FIG. 6 is a diagram showing Embodiment 2 of the present invention. In the second embodiment, the substantially cylindrical rubber member 64 is gradually increased in thickness from the both ends in the axial direction (both ends in the width direction) toward the center in the axial direction (center in the width direction). The cross-sectional shape in the axial direction on the outer periphery of the tire is substantially the same as the cross-sectional shape in the axial direction of the belt layer of the product tire. As a result, the rubber member 64 has a substantially convex lens shape in cross-section. Then, the belt layer 23 is formed by spirally wrapping a rubber-coated strip of the reinforcing cord 25 around the rubber member 64 formed on the BT drum 40 in the radial direction. The belt layer 23 is formed such that the axial center portion (width direction center portion) of the belt layer 23 and the axial center portion (width direction center portion) of the belt layer 23 overlap each other.

  As a result, the thickness of the rubber member 64 disposed on the radially inner side of the central portion in the axial direction of the belt layer 23 is the thickest, and the inner side of the belt layer 23 in the radial direction increases toward the outer sides in the axial direction of the belt layer 23. Since the rubber member 64 disposed on the belt layer gradually becomes thinner, the central portion in the axial direction of the belt layer 23 is located on the outer side in the radial direction from both end portions in the axial direction. As a result, when the belt layer 23 is molded outside the rubber member 64, the radius of curvature of the belt layer 23 can be easily brought close to the radius of curvature of the belt layer of the pneumatic tire that is the product. Other configurations and operations are the same as those of the first embodiment.

    In the above-described embodiment, after forming the green case and the BT band 41 with the band drum and the BT drum 40, they are conveyed to the shaping drum 47, and the green tire 51 is formed on the shaping drum 47. In the present invention, the green tire may be formed by a single forming drum, or after forming the green case, the first forming drum for deforming the green case into a toroidal shape and the BT band are formed. You may make it form a green tire with two forming drums with BT drum.

  In the above-described embodiment, the rubber member 42 is formed by winding the rubber sheet around the BT drum 40 and then joining the start and end. In the present invention, the rubber member is You may shape | mold by winding a narrow and thin rubber strip which consists of unvulcanized rubber on the outer periphery of BT drum spirally many times, shifting gradually in an axial direction. In this way, even when there is a change in the axial sectional shape of the rubber member 42, this can be easily dealt with.

    Next, Test Example 1 will be described. In this test, a strip is spirally wound around a cylindrical BT drum having a rubber member closely arranged on the outside to form a belt layer, and then a tread is attached to the outside to form a BT band. The same tire as the tire manufactured by the method described in the prior art while using the cylindrical BT drum and the tire having the structure as shown in FIG. 1 manufactured by the method described in the first embodiment using the BT band. A conventional tire with a structure was prepared.

  Here, all the tires described above had a tire size of 162.5 / 45R6.5. Further, the length A in the axial direction of the rubber member in the embodiment tire was 125 mm (0.83 times the length B described later), and the wall thickness C was 2 mm (1.82 times the wall thickness D described later) regardless of the axial position. It was. Further, the axial length B of the belt layer in each tire described above was 150 mm, and the thickness D of the belt layer was 1.1 mm. In the belt layer, 41.7 reinforcing cords having a diameter of 0.87 mm twisted from aromatic polyamide filaments were driven per 50 mm.

  Next, each of such tires was dissected after vulcanization, and the presence or absence of meandering of the reinforcing cord in the belt layer was inspected. As a result, in the conventional tire, meandering occurred in the reinforcing cords at both ends in the axial direction of the belt layer, but no meandering occurred in the implementation tire.

  Next, after mounting each tire on a rim of 6.85J-6.5, it was filled with an internal pressure of 20 kPa and pressed against the drum while applying a 196 N load. The amount of protrusion (diameter growth amount) to the outer side in the radial direction at the axially central portion and both axial end portions of the tread portion of the tire was measured. When the results were expressed in terms of an index, it was 0 at the axial center of the conventional tire and 100 at both axial ends, but 0 at the axial central portion of the tire and 60 at both axial ends. Here, the smaller the numerical value, the smaller the protruding amount.

  The present invention can be applied to the industrial field of pneumatic tires.

1 is a meridian cross-sectional view of a pneumatic tire showing Embodiment 1 of the present invention. It is a partially broken plan view of the tread portion. It is a partially broken front view of the BT drum vicinity. It is a partially broken front view near the shaping drum. It is front sectional drawing of the vulcanization mold vicinity. It is a partially broken front view of the BT drum vicinity which shows Embodiment 2 of this invention.

Explanation of symbols

11 ... Pneumatic tire 18 ... Carcass layer
23 ... Belt layer 25 ... Reinforcement cord
33 ... Tread 40 ... Forming drum
41 ... Belt tread band 42, 64 ... Rubber material
51 ... Green tire A ... Axial length B ... Axial length C ... Thickness D ... Thickness S ... Tire equator

Claims (7)

    A carcass layer extending in a toroidal shape, a belt layer disposed radially outward of the carcass layer, and embedded therein with a high elastic modulus reinforcing cord extending substantially parallel to the tire equator S, and radially outward of the belt layer A method of manufacturing a pneumatic tire including a tread disposed, the step of closely arranging a substantially cylindrical rubber member on the outside of a cylindrical forming drum, and the reinforcing cord on the outside of the rubber member Winding a rubber-coated strip spirally to form a substantially cylindrical belt layer, and positioning the axially central portion of the belt layer radially outward from both axial ends by the rubber member; and A process of forming a belt tread band by attaching a tread to the outside of the belt layer, and arranging the belt tread band on the radially outer side of the toroidal carcass layer Step a pneumatic tire manufacturing method, characterized by comprising the step of vulcanizing the green tire for shaping the green tire Te.     The belt layer is wider than the rubber member, and both axial end portions of the belt layer extend outward in the axial direction from the rubber member, so that the axial central portion of the belt layer is positioned radially outward from both axial end portions. The method for manufacturing a pneumatic tire according to claim 1, wherein the pneumatic tire is manufactured.     The axial length A of the rubber member is in the range of 0.75 to 0.85 times the axial length B of the belt layer, and the thickness C of the rubber member is in the range of 0.9 to 2.0 times the thickness D of the belt layer. The method for producing a pneumatic tire according to claim 2.     The method for manufacturing a pneumatic tire according to claim 2 or 3, wherein the thickness C of the rubber member is constant regardless of the axial position.     The rubber member is gradually thickened from the axial outer ends toward the axial center, and the axial center portion of the rubber member is overlapped with the axial central portion of the belt layer, thereby The method for manufacturing a pneumatic tire according to claim 1, wherein the central portion in the direction is positioned radially outward from both axial end portions.     The manufacturing method of the pneumatic tire in any one of Claims 1-5 which comprised the said reinforcement cord from the aromatic polyamide fiber.     A pneumatic tire manufactured using the method for manufacturing a pneumatic tire according to claim 1.

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