JP5328385B2 - Manufacturing method of tire, rubber sheet piece for tire, and molding cutter - Google Patents

Description

    The present invention relates to a tire in which a carcass layer is formed from a rubber sheet piece obtained by cutting a corded rubber sheet between reinforcing cords, a method for manufacturing the rubber sheet piece, and a molding cutter.

    In the tire industry, tires are sometimes manufactured as follows, for example. That is, first, a thin rubber sheet is wound around a cylindrical molding drum to form an inner liner, and then a corded rubber sheet piece is wound while slightly overlapping the start and end portions, The overlap portion is stitched and joined with a stitching roller to form a carcass layer. Next, a bead core is set outside the both ends of the carcass layer in the axial direction, and the carcass layer outside the bead core is disposed around the bead core. After that, a green case is formed by winding a belt-like rubber around the outside of both ends in the axial direction of the carcass layer to form a side tread.

  Next, air is supplied into the green case to bulge and deform into a substantially toroidal shape. At the time of the bulging and deformation, a cylindrical belt tread band formed by another forming drum is moved radially outward of the green case. The green tire is molded by pressing the green case to the inner periphery of the belt tread band, and then the green tire is vulcanized to produce the tire.

  Here, the cord-containing rubber sheet piece described above is conventionally formed by cutting and cutting a belt-like cord-containing rubber sheet in the width direction with a cutter, as described in, for example, Patent Document 1 below. .

JP 2006-075951 A

  That is, after setting a belt-like cord-containing rubber sheet constituted by coating a plurality of mutually parallel reinforcing cords with coating rubber, the cutter is moved in parallel along the reinforcing cords between adjacent reinforcing cords. Thus, the rubber sheet with cord is cut over the entire width by a cutting blade provided at the front end in the moving direction of the cutter, and the rubber sheet piece is cut out. Here, the cutting blade of the cutter described above is composed of two blades (both blades) composed of two intersecting inclined surfaces inclined so as to go forward in the moving direction from both one side surface and the other side surface of the cutter toward the center in the thickness direction. doing.

  And, when the rubber sheet with cord is cut by such a cutter and the rubber sheet piece is cut out, the cutting blade is a double blade, so the coating rubber from both cut surfaces (start and end surfaces) of the rubber sheet piece to the reinforcing cord The remaining gauge is almost the same gauge at the beginning and end, but normally the coating rubber gauge between the reinforcement cords is about 0.05 to 0.30 mm in the carcass layer of passenger car tires, so each remaining gauge is 0.025 to 0.15 mm It becomes about and becomes quite thin.

    However, when a rubber sheet piece cut out using such a conventional double-edged cutter is wound around a tire molding drum as described above, and a carcass layer in which the start and end portions are slightly overlapped is formed, the carcass layer The inner liner of the portion overlapping the overlap joint was locally stretched due to the stress concentration, resulting in a considerably thin gauge, and in some cases tearing occurred.

  The reason for this is that, as shown in FIG. 12, at the time of the above-mentioned stitching, the end portion 12 of the rubber sheet piece 11 is once pushed in until it comes into close contact with the inner liner 13 radially inward as indicated by a virtual line, At this time, the adhesive force of the rubber sheet piece 11 is stronger than that of the molding drum 14, so that the inner liner 13 near the end portion 12 of the rubber sheet piece 11 is removed from the molding drum 14. It is peeled off 14 and pulled up radially outward while in close contact with the rubber sheet piece 11.

  As a result, the inner liner 13 at the site bridging between the start and end portions 15 and 12 of the rubber sheet piece 11 is locally stretched in the circumferential direction while inclining, but at this time, the start and end of the rubber sheet piece 11 This is because the residual rubber gauge P is quite thin as described above, so that the shape at the time of cutting is substantially maintained, and thereby stress is concentrated on the inner liner 13 at the above-mentioned portion, and is stretched considerably.

  Further, the inner liner 13 at the bridging portion is pushed by the air supplied to the inside of the green case when the green case bulges and deforms into a substantially toroidal shape, and is further stretched. In order to prevent such a situation, the gauge of the inner liner 13 has to be set to a certain value, and as a result, it has become a wall against weight reduction of the tire.

  An object of the present invention is to provide a tire, a method for producing a rubber sheet piece for a tire, and a molding cutter that can be reduced in weight by reducing the gauge of the inner liner.

The first object is to provide a carcass layer comprising a rubber sheet piece formed by coating a plurality of mutually parallel reinforcing cords with a coating rubber, extending between a pair of bead cores in a substantially toroidal shape, and a carcass layer. An inner liner made of rubber disposed in close contact with the inside of the layer, and a belt layer and a tread composed of at least two belt plies disposed on the radially outer side of the carcass layer, the carcass layer comprising: In a tire configured by winding a rubber sheet piece around a cylindrical forming drum and overlapping and joining a terminal end portion radially outward of the start end portion, the rubber sheet piece is wound when wound around the forming drum. From the end residual rubber gauge L from the end surface to the reinforcement cord, the end residual rubber gauge L from the end surface to the reinforcement cord The tire was large across the entire width of the sheet pieces can be achieved,

  Second, a step of setting a belt-shaped cord-containing rubber sheet formed by coating a plurality of mutually parallel reinforcing cords with a coating rubber, and a molding cutter between adjacent reinforcing cords along the reinforcing cords A rubber sheet piece for a tire comprising a step of cutting the rubber sheet piece from the corded rubber sheet by cutting the corded rubber sheet over the entire width by a cutting blade provided at the front end in the moving direction by parallel movement In the manufacturing method, the cutting blade is composed of a single blade consisting of an inclined surface inclined toward the front in the moving direction from the terminal side plane toward the starting side plane and the starting side plane, and a reinforcing cord is formed from the starting surface of the rubber sheet piece. From the end residual rubber gauge M from the end surface to the reinforcing cord, the starting end residual rubber gauge L is set to the full width of the rubber sheet piece. Method for producing a large and rubber sheet pieces for a tire Te, it is possible to achieve,

  Thirdly, a belt-like cord-containing rubber sheet formed by coating a plurality of mutually parallel reinforcing cords with a coating rubber is moved in parallel along the reinforcing cords between adjacent reinforcing cords. In a tire rubber sheet piece molding cutter that cuts over the entire width by a cutting blade provided at the front end and cuts out the rubber sheet piece, the cutting blade moves forward in the moving direction from the terminal side plane toward the starting side plane. The rubber sheet piece is composed of a single blade consisting of the inclined surface and the starting end side flat surface, and the starting residual rubber gauge L from the starting end surface of the rubber sheet piece to the reinforcing cord is compared to the terminal residual rubber gauge M from the terminal surface to the reinforcing cord. This can be achieved by a molding cutter for a rubber sheet piece for a tire that is large in the entire width.

  In the invention according to claim 1, when the rubber sheet piece to be the carcass layer is wound around the molding drum, the remaining rubber gauge L at the start end from the start end surface of the rubber sheet piece to the reinforcement cord is set to the end residual residue from the end surface to the reinforcement cord. Since the entire width of the rubber sheet piece is larger than the rubber gauge M, as described above, when the start and end portions of the rubber sheet piece are joined together by stitching, for example, with a stitching roller, the remaining rubber at the start end is stitched. It is crushed between the roller and the forming drum and easily flows so as to become a large gauge toward the end portion.

  As a result, the inner liner at the portion bridging between the start and end portions of the rubber sheet piece described above is in close contact with the remaining rubber at the start end, and the amount of stretching is reduced. As a result, it is possible to suppress a significant decrease and breakage of the gauge of the inner liner at the portion, thereby easily reducing the thickness of the inner liner and reducing the weight of the tire.

  And if the manufacturing method of Claim 3 and the shaping | molding cutter of Claim 4 are used, since a cutting blade is a single blade which consists of an inclined surface and a start end side plane, the coating rubber between adjacent reinforcement cords is It is always cut in the vicinity of the reinforcing cord located on the start side flat surface side of the cutter, whereby the rubber sheet piece as described above can be easily and quickly and reliably cut out from the corded rubber sheet.

  Moreover, if comprised as described in Claim 2, it can suppress strongly the fall and tear of the gauge of an inner liner, preventing the situation where a reinforcement cord gets damaged. Furthermore, if it comprises as described in Claim 5, 6, it can cut | disconnect smoothly and rapidly, preventing the situation where a reinforcement cord gets damaged. According to the seventh aspect of the present invention, the rubber sheet with cords can be quickly and reliably cut across the entire width between the reinforcing cords without damaging the reinforcing cords.

1 is a meridian cross-sectional view of a tire showing Embodiment 1 of the present invention. It is a partially broken front view explaining the manufacturing process of a tire. It is a schematic perspective view which shows the cutting device of a corded rubber sheet. It is a front view which shows the cutter for shaping | molding. It is II sectional view taken on the line of FIG. It is II-II arrow sectional drawing of FIG. It is a top view explaining the cutting | disconnection state of the rubber sheet containing a code | cord | chord by the cutter for shaping | molding. It is the III-III arrow sectional drawing of FIG. It is an expanded sectional view explaining the joining process of a rubber sheet piece. It is an expanded sectional view explaining the state after joining of a rubber sheet piece. It is a partially broken front view explaining the manufacturing process of a tire. It is an expanded sectional view explaining the state after joining the conventional rubber sheet piece.

Embodiment 1 of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 21 denotes a pneumatic radial tire mounted on a passenger car or the like. The pneumatic tire 21 has a pair of bead portions 23, and a pair of (here, a pair of) bead cores. 22 are buried. The pneumatic tire 21 includes a sidewall portion 24 that extends from the bead portion 23 toward the outside in the substantially radial direction, and a substantially cylindrical tread portion 25 that connects the radially outer ends of the sidewall portions 24 to each other. Is further provided.

  The pneumatic tire 21 has a carcass layer 28 that extends in a toroidal shape between the bead cores 22 and reinforces the sidewall portions 24 and the tread portions 25. Both ends of the carcass layer 28 in the width direction are the bead cores 22. It is folded around. The carcass layer 28 is composed of at least one, in this case, one carcass ply 29. The carcass ply 29 is substantially organic such as a plurality of nylons and aromatic polyamides extending in the radial direction (meridian direction). A reinforcing cord 30 made of fiber or steel is covered with a coating rubber 31 (see FIG. 9).

  32 is a stiffener extending substantially radially outward from the bead core 22 along the carcass layer 28, 33 is a rubber chafer arranged to wrap the outside of the carcass layer 28 at the bead portion 23, and 34 is both axially outer sides of the carcass layer 28. It is a side tread arranged in. Reference numeral 35 denotes a belt layer disposed radially outside the carcass layer 28. The belt layer 35 is formed by laminating at least two (here, three) belt plies 36, and each belt ply 36 is a tire. The equator tire is formed by covering a reinforcing cord made of organic fiber such as nylon or aromatic polyamide or steel, which is inclined with respect to the equator S and parallel to each other, with a coating rubber. Of these belt plies 36, at least two belt plies 36 have the reinforcing cords inclined in opposite directions.

  39 is a top tread as a tread disposed radially outward of the carcass layer 28 and the belt layer 35. On the outer surface of the top tread 39, for example, a plurality of main grooves 40 extending in the circumferential direction are provided. A lateral groove (not shown) intersecting with the main groove 40 is formed. Reference numeral 41 denotes an inner liner made of rubber closely arranged inside the carcass layer 28 between the bead cores 22. The inner liner 41 is made of rubber having high air permeation resistance.

  The pneumatic tire 21 as described above can be manufactured, for example, as follows. That is, first, while driving and rotating a first forming drum 44 as a cylindrical forming drum capable of expanding and contracting as shown in FIG. 2, a thin rubber is formed at the center in the axial direction around the first forming drum 44. After winding the sheet 45, the start and end of the rubber sheet 45 are joined together to form the cylindrical inner liner 41. Next, a rubber sheet piece 46 wider than the rubber sheet 45 is wound around the first molding drum 44 while driving and rotating the first molding drum 44. The rubber sheet piece 46 used here is shown in FIG. As shown in -8, it is formed by cutting out from the continuous belt-like corded rubber sheet 47 set at the cutting position to approximately the same length as the one circumference of the first forming drum 44 using the cutting device 48. .

  Here, the rubber sheet piece 46 (cord rubber sheet 47) is formed by coating a plurality of mutually parallel reinforcing cords 30 with a coating rubber 31, and the reinforcing cord 30 is formed of the corded rubber sheet 47. It extends linearly in the width direction. On the other hand, the cutting device 48 includes a lift platform (not shown) that can be moved up and down, a pair of movable platforms 49 and 50 that are supported on the lift platform so as to be movable in the width direction of the corded rubber sheet 47, and these movable platforms. 49 and 50 are provided with a moving means (not shown) that applies a moving force to move in the reverse direction.

  The moving bases 49, 50 are provided with horizontal support shafts 51, 52 extending in a direction perpendicular to the moving direction of the moving bases 49, 50. The support shafts 51, 52 are provided with sliders 53, 54, respectively. It is supported so that it can move along the support shafts 51 and 52. A thin plate-like first cutter piece 58 extending in the vertical direction is fixed to the slider 53, and the first cutter piece 58 is a piercing blade projecting in a V shape at the tip (lower end) adjacent to the corded rubber sheet 47. 59 is provided, and an arcuate cutting blade 60 is provided at the front end in the movement direction at the time of cutting on the base end side from the piercing blade 59.

  On the other hand, a thin plate-like second cutter piece 61 located on the base end side (upper side) from the stab blade 59 of the first cutter piece 58 and extending in the vertical direction is fixed to the slider 54. The cutter piece 61 moves in the opposite direction to the first cutter piece 58 because the moving platforms 49 and 50 move in the opposite direction as described above. Further, an arcuate cutting blade 62 is provided at the front end in the movement direction (on the side opposite to the cutting blade 60) when cutting the second cutter piece 61, and these cutting blades 60, 62 are located at the same height position. ing.

  A first cutter piece in which a piercing blade 59 protruding in a V shape is provided at the distal end adjacent to the corded rubber sheet 47 and a cutting blade 60 is provided at the proximal end side of the piercing blade 59 in the moving direction front end. 58 and a second cutter piece which is located on the proximal side from the piercing blade 59 of the first cutter piece 58 and is movable in the opposite direction to the first cutter piece 58 and having a cutting blade 62 at the front end in the moving direction. 61 constitutes a molding cutter 63 as a whole. If the cutter 63 is constituted by the first cutter piece 58 and the second cutter piece 61 in this way, the corded rubber sheet 47 is quickly and reliably cut across the entire width between the reinforcing cords 30 without damaging the reinforcing cords 30. be able to.

  And when the said moving bases 49 and 50 are located in the nearest position, these 1st, 2nd cutter pieces 58 and 61 are closely_contact | adhered, and as shown in FIG. ing. When the lifting platform and the first and second cutter pieces 58 and 61 are integrally lowered in this state, the first cutter piece 58 is pierced between the reinforcing cords 30 adjacent to each other in the center in the width direction of the corded rubber sheet 47. The first and second cutter pieces 58 and 61 continue to descend to the position where the cutting blades 60 and 62 and the corded rubber sheet 47 intersect each other. At this time, the piercing position between the reinforcing cords 30 of the first and second cutter pieces 58 and 61 changes every time, and it is difficult to make it constant.

  Thereafter, the moving base 49, the first cutter piece 58 and the moving base 50, and the second cutter piece 61 are moved by the moving means between the adjacent reinforcing cords 30 along the reinforcing cord 30 in the moving direction forward (reverse direction). When the sheet 47 is translated to both ends in the width direction, the corded rubber sheet 47 is cut over the entire width by the cutting blades 60 and 62 provided at the front end in the moving direction, and the rubber sheet piece 46 is separated from the corded rubber sheet 47. Cut out. At this time, even if the reinforcing cord 30 is wavy, the first and second cutter pieces 58 and 61 can be easily bent by the reinforcing cord 30 by moving the sliders 53 and 54 along the support shafts 51 and 52. Can follow.

  In this embodiment, the cutter 63 is composed of the first and second cutter pieces 58 and 61 that move in the reverse direction as described above. However, in this invention, the cutter is provided only at the front end in the moving direction. It is composed of only one piece, for example, the second cutter piece, and by moving the cutter from one end in the width direction to the other end in the width direction of the corded rubber sheet, the corded rubber sheet is cut over the entire width by the cutting blade. You may make it do.

  Alternatively, the cutter may be composed of a single piece provided with a stab blade at the tip, and provided with cutting blades on the front and rear sides of the moving direction. After piercing the cutter in the center in the width direction of the sheet and piercing from the blade side, move the cutter along the reinforcing cord to one end in the width direction of the rubber sheet with cord, and then reverse the movement direction to You may make it cut | disconnect a rubber sheet with a cord over the full width by moving to the other end of the width direction.

  Here, both the cutting blades 60 and 62 of the cutter 63 (first and second cutter pieces 58 and 61) are seen from the end side planes 58a and 61a when viewed from the start end side, and the start end when viewed from the end side. It consists of a single-edged blade comprising inclined surfaces 58c and 61c that are inclined to the front in the moving direction toward the side planes 58b and 61b, and the start end side planes 58b and 61b. Here, the above-mentioned start end side means the side of the rubber sheet piece 46 that is first wound around the first molding drum 44, and the end side is the last end of the rubber sheet piece 46 that is wound around the first molding drum 44. Means the side and is irrelevant to the front and rear end sides of the corded rubber sheet 47.

  Then, when the coating rubber 31 between the reinforcing cords 30 is cut by the cutting blades 60 and 62 composed of such single blades, the inclined surfaces 58c and 61c are formed when the first and second cutter pieces 58 and 61 are moved (at the time of cutting). In this case, a resistance force F in a direction perpendicular to the inclined surfaces 58c and 61c acts from the coating rubber 31. Of the resistance force F, the first and second cutter pieces 58 and 61 have the first component in the thickness direction. The second cutter pieces 58 and 61 are pressed toward the starting end side. As a result, as described above, the first and second cutter pieces 58 and 61 are reinforced cords located on the start end side among the adjacent reinforced cords 30 as the cutting progresses regardless of the piercing position. Approach 30.

  Thus, the corded rubber sheet 47 is cut along the reinforcing cord 30 in the vicinity of the reinforcing cord 30 located on the start end side by the cutter 63. As a result, in the cut rubber sheet piece 46, the start end face 46a is cut. The starting end residual rubber gauge L of the starting end residual rubber 46c positioned between the terminal end reinforcing cord 30 and the starting end reinforcing cord 30 is more rubber than the terminal residual rubber gauge M of the terminal residual rubber 46d positioned between the terminal end surface 46b and the terminal reinforcing cord 30. The total width of the sheet piece 46 is large.

  Thus, if the cutting blades 60 and 62 of the cutter 63 are constituted by a single blade comprising the inclined surfaces 58c and 61c and the starting end side surfaces 58b and 61b, the coating rubber 31 between the two adjacent reinforcing cords 30 can be used as the cutter 63. The first and second cutter pieces 58 and 61 can always be cut in the vicinity of the reinforcing cord 30 positioned on the start side flat surfaces 58b and 61b, whereby the rubber sheet piece 46 as described above can be cut into the corded rubber sheet. It can be cut out easily and quickly from 47. In addition, since the variation in the cutting position is less than that of the double-edged blades (double-edged blades), the uniformity and balance of the pneumatic tire 21 can be improved.

  On the other hand, the piercing blade 59 of the first cutter piece 58 (cutter 63) is inclined 2 toward the tip (downward) as it goes from the end side flat surface 58a and the start end side flat surface 58b toward the center in the thickness direction of the first cutter piece 58. It is a two-edged blade (double-edged blade) composed of two inclined surfaces 59a and inclined surfaces 59b, and the cutting edge thereof is sharply pointed. Then, as described above, the rubber sheet piece 46 whose starting end residual rubber gauge L is larger than the terminal residual rubber gauge M is wound around the first molding drum 44 as described above. At this time, as shown in FIG. It winds in the state which made the terminal part overlap slightly on the radial direction outer side of the starting end part.

  Thereafter, the stitching roller 68 is pressed while pressing the start and end portions (overlap portions) of the rubber sheet pieces 46 against the first molding drum 44 by a stitching roller 68 extending in a tangential direction with respect to the first molding drum 44. When the first forming drum 44 is moved in the axial direction, the start and end portions of the rubber sheet piece 46 are stitched by the stitching roller 68 and joined to each other. At the time of this stitching, the starting end remaining rubber 46c is crushed and flowed by the stitching roller 68, and becomes thinner toward the starting end, while the end portion of the rubber sheet piece 46 located in the vicinity of the starting end surface 46a is shown in FIG. 9 is deformed so as to approach the first forming drum 44 as indicated by an imaginary line.

  As a result, the end portion of the rubber sheet piece 46 deformed as described above is in close contact with the inner liner 41. Thereafter, the end portion of the rubber sheet piece 46 returns to an almost initial shape with the end of the stitching operation. . At this time, since the adhesive force between the inner liner 41 and the rubber sheet piece 46 is larger than the adhesive force between the inner liner 41 and the first molding drum 44, the adhesive force between the inner liner 41 and the rubber sheet piece 46 is in close contact with the terminal portion of the rubber sheet piece 46. As shown in FIG. 10, the inner liner 41 is peeled off from the first molding drum 44 by the end portion of the rubber sheet piece 46 and pulled up radially outward.

  Further, at this time, since the starting end residual rubber 46c that is fluidly deformed in a tapered manner by the stitching is also in close contact with the terminal portion of the rubber sheet piece 46, the starting end reinforcing cord 30 can be easily followed and deformed radially outward with the fixed cord 30 as a fixed point. As a result, the starting end remaining rubber 46c becomes a large gauge toward the terminal portion of the rubber sheet piece 46. As a result, the inner liner 41 at the portion bridging between the start and end portions of the rubber sheet piece 46 is in close contact with the remaining rubber 46c at the start end, and as a result, the stress concentration at the portion is concentrated. Is relaxed and the amount of stretching is reduced. As a result, a significant decrease or breakage of the gauge of the inner liner 41 at the portion is suppressed, whereby the inner liner 41 can be thinned and the pneumatic tire 21 can be easily reduced in weight.

  Here, it is preferable that the crossing angle G between the inclined surfaces 58c and 61c and the start end side surfaces 58b and 61b constituting the single blade is in the range of 40 to 80 degrees. The reason is that if the crossing angle G is less than 40 degrees, the reinforcing cord 30 may be damaged by the cutting blade at the time of cutting. On the other hand, if it exceeds 80 degrees, cutting becomes difficult, but it is within the above-mentioned range. This is because the corded rubber sheet 47 can be cut smoothly and quickly while preventing the reinforcing cord 30 from being damaged.

  Further, it is preferable to round the cutting edge of the single blade described above with an arc of 0.2 mm or more to have a cross-sectional arc shape, because the risk of damaging the reinforcing cord 30 due to the single cutting at the time of cutting can be avoided. However, if the cutting edge is rounded with an arc exceeding 1.0 mm, the cutting operation becomes difficult. Therefore, it is preferable to round the cutting edge of a single blade with an arc of 0.2 to 1.0 mm. The cutting edge of the piercing blade 59 may be rounded with an arc of 0.2 to 1.0 mm as with the cutting blades 60 and 62.

  Furthermore, it is preferable that the starting end residual rubber gauge L at the time of winding around the first molding drum 44 be within a range of 0.70 to 0.95 times the rubber gauge N between two adjacent reinforcing cords 30. The reason is that if the remaining rubber gauge L at the starting end is less than 0.70 times the rubber gauge N, the gauge of the inner liner 41 cannot be sufficiently reduced or broken. On the other hand, if it exceeds 0.95 times, There is a risk that the cord 30 may be scratched by a single blade when it is cut, but if it is within the above range, the reinforcing cord 30 can be prevented from being damaged, and the gauge of the inner liner 41 can be greatly reduced or broken. This is because it can be suppressed.

  When the rubber sheet piece 46 is wound around the first forming drum 44 and the inner liner 41 in this way and the start and end portions thereof are joined together, the carcass layer 28 is formed from the rubber sheet piece 46. The diameter of the central portion of the first molding drum 44 in the axial direction is increased, the diameter of the central portion of the inner liner 41 and the carcass layer 28 is increased, and the bead cores 22 with the stiffeners 32 are provided outside the stepped portions of the carcass layer 28. set. Next, a bladder (not shown) of the first forming drum 44 is expanded, and the carcass layer 28 axially outer than the bead core 22 is folded back inward in the axial direction around the bead core 22. The side tread 34 is wound around both ends, and the green case 70 is formed.

  Next, after gripping the green case 70 from the outside in the radial direction by a conveying device (not shown), the diameter of the first forming drum 44 is reduced, and the green case 70 is transferred from the first forming drum 44 to the conveying device. Thereafter, the green case 70 is transported to the second molding drum 71 as shown in FIG. 11 by the transport device, and is fitted to the outside of the second molding drum 71. Next, a pair of bead supports 72 provided on the second forming drum 71 in the axial direction is moved radially outward to support the bead core 22 of the green case 70 from the radially inner side. Thereafter, low-pressure air is supplied into the green case 70 between the bead cores 22 and the bead support 72 is moved inward in the axial direction so as to approach each other together with the bead cores 22.

  As a result, the green case 70 between the bead cores 22 bulges and deforms from a cylindrical shape to a substantially toroidal shape. At the time of the bulging deformation, a cylindrical belt tread band 73 formed by another band forming drum is formed into a green case. Then, the green case 70 is pressed against the inner periphery of the belt tread band 73 to form a green tire. Next, the green tire is vulcanized to produce a pneumatic tire.

Next, the operation of the first embodiment will be described.
When manufacturing the pneumatic tire 21 as described above, first, the rubber sheet 45 is wound around the first forming drum 44, and then the start and end of the rubber sheet 45 are joined together to form the inner liner 41. Mold. Next, a rubber sheet piece 46 is wound around the first forming drum 44 and the inner liner 41. The rubber sheet piece 46 used here is as follows using a cutting device 48 from a continuous belt-like cord-containing rubber sheet 47. And cut out. That is, first, the lifting platform and the first and second cutter pieces 58 and 61 are integrally lowered, and the cutter 63 is interposed between the reinforcing cords 30 adjacent to each other at the center in the width direction of the rubber sheet 47 with cord set at the cutting position. Is inserted to a position where the cutting blades 60 and 62 and the corded rubber sheet 47 intersect.

  Thereafter, when the first and second cutter pieces 58 and 61 are moved in parallel between the reinforcing cords 30 along the reinforcing cords 30 by the moving means to both ends in the width direction of the rubber sheet 47 with cords, The entering rubber sheet 47 is cut over the entire width by the cutting blade 60 and the cutting blade 62 provided at the front end in the moving direction, and the rubber sheet piece 46 is cut out from the corded rubber sheet 47. At this time, since the cutting blades 60 and 62 are composed of single blades composed of inclined surfaces 58c and 61c and the starting end side planes 58b and 61b, the starting end residual rubber gauge L of the starting end residual rubber 46c is the terminal end of the terminal residual rubber 46d. From the remaining rubber gauge M, the total width of the rubber sheet piece 46 becomes larger.

  Then, the rubber sheet piece 46 having the starting end residual rubber gauge L larger than the terminal residual rubber gauge M is wound around the first molding drum 44 in this way, but at this time, the terminal portion is slightly overlapped radially outward of the starting end portion. Then, the rubber sheet piece 46 is started at the start and end portions (overlap portion) by the stitching roller 68, and stitched along the end portions and joined together.

  At this time, the starting end remaining rubber 46c is crushed and flows so as to become a large gauge as it goes to the terminal end, whereby the inner liner 41 at the site bridging between the start and end of the rubber sheet piece 46 is A considerable part or all of the remaining rubber 46c comes into close contact with the remaining rubber 46c, and the amount of stretching is reduced. As a result, a significant decrease or breakage of the gauge of the inner liner 41 at the portion is suppressed.

  When the carcass layer 28 is molded from the rubber sheet piece 46 in this way, the axial center portion of the first molding drum 44 is expanded, and the axial center portions of the inner liner 41 and the carcass layer 28 are expanded. The bead cores 22 with the stiffeners 32 are set on the outside of the stepped portions of the carcass layer 28, respectively. Next, the carcass layer 28 axially outer than the bead core 22 is folded back inward in the axial direction around the bead core 22, and then the side tread 34 is wound around the both axial ends of the carcass layer 28, and the green case 70 is attached. Mold.

  Next, the green case 70 is transported from the first molding drum 44 to the second molding drum 71 by a transport device, and is set on the second molding drum 71. Next, low-pressure air is supplied into the green case 70 between the bead cores 22, and the bead support 72 is moved inward in the axial direction so as to approach each other together with the bead cores 22, so that the green case 70 between the bead cores 22 is substantially toroidal. Bulge and deform. At this time, it is conceivable that the inner liner 41 bridging the start and end portions of the carcass layer 28 is pushed further by the low-pressure air, but the length of the inner liner 41 bridging as described above. Is zero or fairly short, so that it hardly affects the gauge of the inner liner 41.

  Then, as described above, when the green case 70 is bulging and deforming in a substantially toroidal shape, the belt tread band 73 is carried inwardly in the radial direction of the green case 70, and the green case 70 is placed inside the belt tread band 73. A green tire is formed by pressure bonding to the circumference. Thereafter, the green tire is vulcanized by a vulcanizer to form a pneumatic tire 21.

  The present invention can be applied to the industrial field of tires in which a carcass layer is formed from rubber sheet pieces.

21 ... Tire 22 ... Bead core
28 ... Carcass layer 30 ... Reinforcement cord
31 ... Coating rubber 35 ... Belt layer
39 ... Tread 41 ... Inner liner
44 ... Molding drum 46 ... Rubber sheet
46a ... Start end face 46b ... End face
47 ... Rubber sheet with cord 58 ... First cutter piece
58a, 61a ... Termination side plane 58b, 61b ... Start end side plane
58c, 61c ... inclined surface 59 ... piercing blade
60, 62 ... Cutting blade 61 ... Second cutter piece
63 ... Cutter for molding

Claims (7)

A carcass layer composed of a rubber sheet piece formed by coating a plurality of mutually parallel reinforcing cords with a coating rubber extending between the pair of bead cores in a substantially toroidal shape, and a rubber closely arranged inside the carcass layer An inner liner, and a belt layer and a tread composed of at least two belt plies disposed on the outer side in the radial direction of the carcass layer, and the carcass layer has rubber around a cylindrical forming drum. In a tire configured by winding a sheet piece and overlapping and joining the end portion radially outward of the starting end portion, when the winding is performed on the molding drum, the remaining starting end from the starting end surface of the rubber sheet piece to the reinforcing cord is retained. The rubber gauge L is larger in the entire width of the rubber sheet piece than the residual rubber gauge M at the end from the end surface to the reinforcing cord. Tire, characterized in that it was.     2. The tire according to claim 1, wherein the starting end residual rubber gauge L at the time of winding on the molding drum is within a range of 0.70 to 0.95 times the rubber gauge N between adjacent reinforcing cords.     A step of setting a belt-shaped cord-containing rubber sheet constituted by coating a plurality of mutually parallel reinforcing cords with a coating rubber, and a parallel movement of the molding cutter between the adjacent reinforcing cords along the reinforcing cords In the method for manufacturing a rubber sheet piece for a tire, including a step of cutting the rubber sheet piece from the corded rubber sheet by cutting the corded rubber sheet over the entire width by a cutting blade provided at the front end in the moving direction, The cutting blade is composed of a single blade consisting of an inclined surface inclined to the front in the moving direction from the terminal end plane to the starting end plane and the starting end plane, and the starting end remaining from the starting end surface of the rubber sheet piece to the reinforcing cord The rubber gauge L is larger in the entire width of the rubber sheet piece than the remaining rubber gauge M at the end from the end surface to the reinforcing cord. Method for producing a rubber sheet strip for a tire, characterized in that the.     A belt-shaped cord-containing rubber sheet formed by coating a plurality of mutually parallel reinforcing cords with a coating rubber is provided at the front end in the moving direction by moving in parallel along the reinforcing cords between adjacent reinforcing cords. In a tire rubber sheet piece molding cutter that cuts the entire width by a cutting blade and cuts out the rubber sheet piece, the inclination of the cutting blade is inclined so as to move forward in the moving direction from the terminal end plane to the starting end plane. And a starting edge residual rubber gauge L from the starting end surface of the rubber sheet piece to the reinforcing cord is larger than the terminal residual rubber gauge M from the terminal surface to the reinforcing cord over the entire width of the rubber sheet piece. A tire cutter for molding rubber sheet pieces.     The rubber sheet piece molding cutter according to claim 4, wherein an intersection angle G between the inclined surface constituting the single blade and the starting end side plane is in the range of 40 to 80 degrees.     The rubber sheet piece molding cutter according to claim 4 or 5, wherein the blade edge of the single blade is rounded with an arc of 0.2 to 1.0 mm.     A first cutter piece provided with a piercing blade projecting in a V shape at the distal end near the corded rubber sheet and a cutting blade at the front end in the moving direction on the proximal side of the piercing blade. And a second cutter piece which is located on the proximal end side from the piercing blade of the first cutter piece and is movable in the opposite direction to the first cutter piece, and a cutting blade is provided at the front end in the moving direction, From the piercing blade side to the position where the cutting blade of the first and second cutter pieces and the corded rubber sheet intersect with each other between the adjacent reinforcing cords of the corded rubber sheet with the first and second cutter pieces in close contact with each other 7. The rubber sheet with cords is cut by piercing the first and second cutter pieces in parallel in the reverse direction along the reinforcing cords. Molding cutter rubber sheet strip for a tire.

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