Patent Description:
A pneumatic tire is manufactured by vulcanizing an unvulcanized green tire formed by laminating tire components on a molding surface of the outer circumference of a cylindrical forming drum. In the belt layer serving as the tire components, a plurality of reinforcing cords aligned at a predetermined inclination angle with respect to the tire circumferential direction is coated with unvulcanized rubber. The belt layer is formed, for example, by applying a plurality of strip materials with a plurality of aligned reinforcing cords coated with unvulcanized rubber to the molding surface on the outer circumference of the forming drum in the circumferential direction, and bonding strip materials adjacent in the circumferential direction together (see <CIT>).

One method of forming a green tire is a method of sequentially laminating tire components on the outer circumference of a rigid core having an outer circumferential surface shape corresponding to the shape of the tire inner circumferential surface of the finished tire (for example, see <CIT>). Tires typically have a profile in which the circumferential length varies depending on the position in the tire lateral direction. As a result, the outer circumferential surface of the rigid core also has a profile in which the circumferential length varies depending on the position in the width direction. Therefore, when the strip materials forming the belt layer are sequentially and simply extended in the width direction of the rigid core at a predetermined inclination angle with respect to the circumferential direction of the rigid core, and are arranged and bonded in the circumferential direction of the rigid core, depending on the position of the rigid core in the width direction, the overlap between adjacent strip materials in the circumferential direction is excessively large or excessively small, so that a variation occurs in the bonding margin between adjacent strip materials. The variation in the bonding margin adversely affects the quality of the manufactured tire, so there is room for improvement.

<CIT> discloses a tire structure member fabricating method, which fabricates a tire structural member by successively and contiguously attaching stripes to a convex outer surface having an outwardly convex cross section of a forming drum by a strip feed device such that the strips extend obliquely to a center axis of the forming drum. The method comprises the steps of continuously attaching strips to the convex outer surface of the forming drum by successively feeding strips onto the convex surface by the strip feed device, while the strip feed device is being moved parallel to the center axis of the forming drum relative to the forming drum at a fixed speed and while the forming drum is being rotated about the center axis thereof, and controlling the rotation of the forming drum such that the angular velocity of the forming drum varies gradually from a minimum angular velocity at a moment a leading end of the strip is attached to the convex outer surface of the forming drum to a maximum angular velocity at a moment the strip is attached to a middle part of the convex outer surface of the forming drum and from the maximum angular velocity to a minimum angular velocity at a moment a trailing end of the strip is attached to the convex outer surface of the forming drum, the minimum angular velocity at the moment the trailing end is attached being equal to the minimum angular velocity at the moment the leading end is attached.

<CIT> discloses an apparatus for manufacturing reinforcing structures for tires of vehicles comprising a laying unit. The laying unit comprises auxiliary holding elements that hold a strip-like segment, transversely laid in a position substantially cantered relative to an equatorial plane of a toroidal support. A translation of presser elements towards the toroidal support is also brough about, so that the strip-like element is radially approached to the toroidal support and brought in contact and pressed with its central portion against the exterior surface, in proximity to the equatorial plane of the toroidal support itself. With the motion of the support elements away from each other along the guide support, the simultaneous translation is determined of the presser elements along the strip-like segment, away from the equatorial plane, so as to cause the application of the segment itself according to its entire length onto the toroidal support, with a pressing action progressively extending towards the opposite extremities of the strip-like segment itself, starting from the central portion itself. Further, the apparatus comprises a second angular actuation device able to be activated during the application of each strip-like segment to cause a relative angular rotation about an axis of correction.

<CIT> discloses a process for manufacturing a belt structure particularly a crossed belt having at least a first and at least a second radially superimposed reinforcing layers. An apparatus for manufacturing the belt structure comprises a toroidal support having an outer surface on which the belt structure is formed. The toroidal support is mounted rotatably about a rotation axis. The belt structure may be built directly on a carcass structure. The apparatus comprises motion devices represented by two robot arms of an anthropomorphic type, each movable with six degrees of freedom, and the free end of the rotor arm supports a laying element. The laying elements face each other and are opposite to each other with respect to the equatorial plane of the toroidal support. The motion devices can be moved away from each other synchronically and symmetrically with respect to the laying starting point. The motion elements can be moved independently from each other. First, the step of moving the laying element towards the toroidal support is carried out so as to bring a substantially central portion of the rubberized strip-like element into contact with a portion of the outer surface, and according to a predetermined orientation or angle with respect to the equatorial plane of the toroidal support. During the movement of the laying element for each position of the path defined on the outer surface of the toroidal support the orientation of the laying element is changed, so as to substantially match a sequence of positions of the laying surface of the laying element with the sequence of positions of the positioning polygons, which is associated with the laying path.

<CIT> discloses a tire manufacturing method comprising a tire bead carcass member manufacturing step including a ply turning-up step, a ply layering step, and a ply turning-down step. In the ply turning-down step, an outer circumferential surface of a ply layered body is supported. While the ply layered body is rotated, a turning-down stitcher turns down axial end portions of a second ply around beads from the radially outer side toward the radially inner side. While the ply layered body is rotated, a layering stitcher operates so as to layer the axial end portions of the second ply having been turned down to an inner side of the ply layered body, over an inner circumferential surface of a first ply, to form the bead carcass member.

An object of the present invention is to provide a method for manufacturing a tire in which when forming a belt layer by sequentially arranging and attaching a large number of strip materials to the outer circumferential surface of a rigid core in a circumferential direction, and bonding strip materials that are adjacent in the circumferential direction, it is possible to suppress bonding disorder between the strip materials due to the circumferential length of the outer circumferential surface of the rigid core that varies depending on the position of the rigid core in the width direction.

In order to achieve the object described above, a method for manufacturing a tire according the present invention is provided, which comprising sequentially bonding a large number of strip materials on a molding surface located on an outer circumferential side of a rigid core having an outer circumferential surface with a profile in which a circumferential length changes at a position in a width direction, in manner of extending the strip materials in a width direction of the rigid core at an inclined direction with respect to a circumferential direction of the rigid core, and arranging and bonding the strip materials in the circumferential direction, so that a belt layer is formed by bonding together the strip materials that are adjacently bonded in the circumferential direction; forming a green tire having the belt layer; and vulcanizing the green tire, wherein, the rigid core is relatively moved along the profile that is preliminarily known so that the molding surface is brought close to the strip material to be bonded to the molding surface, and the strip materials to be bonded are extended in the longitudinal direction and bonded to the molding surface while relatively turning the rigid core in a direction in which a circumferential angle with respect to the longitudinal direction of the strip materials to be bonded changes, so that variation in bonding margin, due to the position in the width of the rigid core, between the strip materials to be bonded adjacent to each other in the circumferential direction is reduced, wherein after bonding the central portion in the longitudinal direction of the strip material to be bonded to the molding surface at a central portion of the rigid core in the width direction, the strip material to be bonded is bonded to the molding surface from the central portion in the longitudinal direction toward one end in the longitudinal direction, then the strip material to be bonded is bonded to the molding surface from the central portion in the longitudinal direction toward the other end in the longitudinal direction.

According to the present invention, along the profile in the width direction of the outer circumferential surface of the rigid core that is preliminarily known, the rigid core is relatively moved so that the molding surface is brought close to the strip material to be bonded to the molding surface, and the strip material is bonded to the molding surface in a manner of extending in the longitudinal direction while relatively rotating the rigid core in a direction in which the circumferential angle of the rigid core with respect to the longitudinal direction of the strip material changes, and thus variation in the bonding margin, due to the position in the width direction of the rigid core, between strip materials that are adjacent in the circumferential direction and bonded to the molding surface is reduced. Therefore, this is advantageous to prevent the strip materials adjacent in the circumferential direction from excessively overlapping with each other, and also prevent gaps generated between adjacent strip materials. Accordingly, it is possible to suppress bonding disorder between the strip materials due to the circumferential length of the outer circumferential surface of the rigid core that varies depending on the position in the width direction. This contributes to improved quality of the manufactured tire.

Hereinafter, a method for manufacturing a tire according to the present invention will be described based on embodiments illustrated in the drawings.

According to the present invention, a tire <NUM> is manufactured by forming a green tire <NUM> using a forming device <NUM> illustrated in <FIG> and <FIG> and vulcanizing the formed green tire <NUM>. Note that the present invention is not limited to a typical pneumatic tire, and may be applied to the manufacturing of various tires <NUM> such as solid tires or the like. The rigid core <NUM> illustrated in <FIG> that is formed from metal or the like is used for forming the green tire <NUM>. The rigid core <NUM> has an outer circumferential surface shape corresponding to the shape of the tire inner circumferential surface of the completed tire <NUM>. Therefore, as illustrated in <FIG>, the outer circumferential surface 2b of the rigid core <NUM> has a profile in which the circumferential length changes depending on the position of the rigid core <NUM> in the width direction. In general, the rigid core <NUM> has a profile in which the central portion of the rigid core <NUM> in the width direction protrudes further toward outer circumferential side than both end portions. The rigid core <NUM> is composed of, for example, a plurality of segments divided in the circumferential direction about a center shaft 2a, and a support rod for supporting the segments from inside.

The width direction W and the circumferential direction L of the rigid core <NUM> correspond to the width direction and the circumferential direction of the green tire <NUM> and the completed tire <NUM>, respectively. The dot-dash line CL in the figures indicates the tire axis (the axis of the center shaft 2a), and the dot-dash line Z indicates the revolution axis passing through the center of the rigid core <NUM> in the width direction W and orthogonal to the dot-dash line CL.

The forming device <NUM> includes a freely moving arm <NUM> for moving the rigid core <NUM> to an arbitrary position, a bonding unit <NUM> for bonding a strip material <NUM>, and a control unit <NUM> for controlling the operations of the freely moving arm <NUM> and the bonding unit <NUM>. Examples of the freely moving arm <NUM> include industrial robots and the like. The center shaft 2a of the rigid core <NUM> is held on the tip end portion of the freely moving arm <NUM>, and the rigid core <NUM> is able to rotate about the center shaft 2a. In addition, the rigid core <NUM> is able to rotate about the revolution axis Z.

In this embodiment, the bonding unit <NUM> (base frame <NUM>) is installed in a fixed state on the floor, and the rigid core <NUM> is movable; however, the rigid core <NUM> may be installed in a fixed state in a predetermined position and the bonding unit <NUM> is movably installed. Alternatively, the bonding unit <NUM> and the rigid core <NUM> may be movably installed. In other words, in the present invention, it is sufficient that the bonding unit <NUM> and the rigid core <NUM> are relatively movable.

The bonding unit <NUM> includes: a base frame <NUM>, a pair of pressing rollers <NUM> attached to the base frame <NUM>, and a movement mechanism <NUM> that horizontally moves the pressing rollers <NUM> in a direction toward or away from each other. The movement mechanism <NUM> includes, for example, a ball screw and a servo motor that rotates the ball screw. Alternatively, a fluid cylinder or the like may be used as the movement mechanism <NUM>. Each of the pressing rollers <NUM> may be configured to independently move horizontally, or may be configured to move horizontally in synchronization with each other.

The bonding unit <NUM> further includes a pressing body <NUM> that moves vertically between the pressing rollers <NUM>, and guides <NUM> disposed in the vicinity of each of the pressing rollers <NUM>. Each guide <NUM> is spaced apart in the axial direction of the rotation shaft, and has an externally fitted guide roller. Each guide <NUM> is disposed on the outer side (side in the direction in which the pressing rollers <NUM> are separated away from each other) of the adjacent pressing roller <NUM>, and is capable of moving horizontally along with the adjacent pressing rollers <NUM>.

Next, a procedure for manufacturing the tire <NUM> according to the present invention will be described.

As illustrated in <FIG>, predetermined tire components (such as an innerliner <NUM>, a carcass layer <NUM>, and the like) are sequentially bonded to the outer circumferential surface 2b of the rigid core <NUM> illustrated in <FIG> and <FIG>. More specifically, the innerliner <NUM> and the carcass layer <NUM> are laminated and bonded sequentially to the outer circumferential surface 2b of the rigid core <NUM> to form a cylindrical shape. On both sides of the rigid core <NUM> in the width direction, a ring-shaped bead member <NUM> is disposed on the carcass layer <NUM>, and the carcass layer <NUM> is folded back around the bead core 13a of each of the bead members <NUM>. In addition, unvulcanized side rubber <NUM> is laminated and bonded to both end portions of the carcass layer <NUM> in the width direction. Other tire components are also bonded as needed. Note that in <FIG>, tire components other than a belt layer <NUM> (strip material <NUM>) are omitted and not illustrated.

Next, the cylindrical belt layer <NUM> is formed on the outer circumferential surface (molding surface 14a) of the cylindrical carcass layer <NUM> that is bonded to the outer circumferential side of the rigid core <NUM>. As illustrated in <FIG>, the belt layer <NUM> is formed by bonding a plurality of strip materials <NUM>. In the belt layer <NUM>, a plurality of reinforcing cords 16a aligned at a predetermined inclination angle with respect to the tire circumferential direction is coated with unvulcanized rubber. The forming device <NUM> is used to form the belt layer <NUM>.

Each of the strip materials <NUM> is formed by coating, with unvulcanized rubber, the plurality of reinforcing cords 16a that are aligned in parallel. Therefore, first, the strip materials <NUM> are sequentially arranged one by one over the pair of pressing rollers <NUM>. At this time, as illustrated in <FIG>, the pair of pressing rollers <NUM> are at positions close to each other, and the pressing body <NUM> is at a position where it does not project above the respective pressing rollers <NUM>.

Each guide <NUM> is located at a position outside of the adjacent pressing roller <NUM> (on a side in a direction in which the pressing rollers <NUM> are separated from each other). The strip material <NUM> disposed is inserted between the pressing roller <NUM> and the guide <NUM> in such a manner to span over the pair of pressing rollers <NUM>. The central portion M of the strip material <NUM> in longitudinal direction is set above the pressing body <NUM>, and the strip material <NUM> is disposed between guide rollers of each of the guides <NUM>. The separation distance between the guide rollers of the guides <NUM> is set to be slightly greater than the strip width H of the strip material <NUM>; however, both are substantially of the same dimension.

The shape data of the rigid core <NUM> is inputted to the control unit <NUM>, and the data of the profile of the outer circumferential surface 2b having a circumferential length that varies at the width direction position is also inputted to the control unit <NUM>. In addition, various data such as shape data (length, width, thickness) of the tire components used (<NUM>, <NUM>, <NUM>, <NUM>, and the like), specification data of the green tire <NUM> to be molded, and the like are also inputted.

Next, by cooperation of the rigid core <NUM> with the bonding unit <NUM>, the strip material <NUM> is bonded to the outer circumferential surface 14a of the carcass layer <NUM> layered on the outer circumferential side of the rigid core <NUM>. In other words, the outer circumferential surface of the carcass layer <NUM> becomes the molding surface 14a to which the strip material <NUM> is bonded.

In order to form the belt layer <NUM>, a plurality of strip materials <NUM> are sequentially bonded to the molding surface 14a, extending in the width direction of the rigid core <NUM> in a direction oblique (inclination angle a) to the circumferential direction of the rigid core <NUM>. Then, the strip materials <NUM> bonded to the molding surface 14a are bonded to each other in the circumferential direction to form the belt layer <NUM>.

Here, the outer circumferential surface 2b of the rigid core <NUM> has a profile having a circumferential length that varies at the width direction position as described above. The innerliner <NUM> and the carcass layer <NUM> bonded sequentially to the outer circumferential surface 2b are members having a constant thickness, and thus the molding surface 14a to which the strip material <NUM> is bonded has a profile having a circumferential length (length in the circumferential direction) that varies at the width direction position in the same manner as the outer circumferential surface 2b.

Therefore, the belt layer <NUM> is formed by actuating the rigid core <NUM> and the bonding unit <NUM> along the profile of the outer circumferential surface 2b of the rigid core <NUM> that is inputted to the control unit <NUM> and preliminarily known. As illustrated in <FIG>, the pressing body <NUM> is moved upward of the strip material <NUM> which spans over the pair of pressing rollers <NUM>. Accordingly, the central portion M of the strip material <NUM> in the longitudinal direction is pressed against the molding surface 14a and bonded at the central portion of the rigid core <NUM> in the width direction.

Next, as illustrated in <FIG>, the rigid core <NUM> is moved downward so as to bring the molding surface 14a in proximity with the strip material <NUM> to be bonded to the molding surface 14a, and the strip material <NUM> is bonded to the molding surface 14a in a manner of extending in the longitudinal direction while turning the rigid core <NUM> about the revolution axis Z. More specifically, with the downward movement of the rigid core <NUM>, the rigid core <NUM> is turned in a direction in which the circumferential angle of the rigid core <NUM> with respect to the longitudinal direction of the strip materials <NUM> to be bonded changes, so that the variation in the bonding margin, due to the position in the width direction of the rigid core <NUM> (the bonding length in the circumferential direction of the opposing end surfaces of the strip materials <NUM> adjacent in the circumferential direction), between the strip materials <NUM> that are to be bonded adjacent to each other in the circumferential direction of the molding surface 14a is reduced. Adjacent strip materials <NUM> are brought essentially in contact and bonded, and thus the bonding margin is neither plus nor minus, but is close to zero.

At both end portions in the width direction in the range corresponding to the tread of the rigid core <NUM>, the circumferential length of the molding surface 14a is shorter than that of the central portion in the width direction. Therefore, when bonding the strip material <NUM>, the rigid core <NUM> is turned so that the inclination angle a is greater at both end portions in the width direction than in the central portion in the width direction.

Then, along with the turning of the rigid core <NUM>, the pair of pressing rollers <NUM> are horizontally moved in a direction away from each other. As a result, the strip material <NUM> to be bonded is sandwiched between the molding surface 14a and the pressing rollers <NUM>, and the strip material <NUM> is extended in the longitudinal direction and pressed against and bonded to the molding surface 14a.

For example, when it is set in advance to use N strip materials <NUM> having the same specification (strip width H) to form the belt layer <NUM>, the rigid core <NUM> would be turned as described below. The circumferential length K of the molding surface 14a at the position in the width direction of the rigid core <NUM> illustrated in <FIG> can be predetermined. Then, in a case where the strip material <NUM> is bonded at an inclination angle a with respect to the circumferential direction of the rigid core <NUM>, the length t of the strip material <NUM> in the circumferential direction of the rigid core <NUM> at the position in the width direction is t = H/Sin(a). Then, the circumferential length K = the length t × N, so the following Equation (<NUM>) is introduced.

Thus, when bonding each of the strip materials <NUM> to the molding surface 14a, the rigid core <NUM> is turned so that the inclination angle a of the strip material <NUM> satisfies Equation (<NUM>) above, depending on the position in the width direction of the rigid core <NUM>.

In this embodiment, the profile of the rigid core <NUM> has a symmetrical shape with respect to the center in the width direction, and thus, after bonding the central portion M in the longitudinal direction of the strip material <NUM> to be bonded to the molding surface 14a at the central portion in the width direction of the rigid core <NUM>, the strip material <NUM> is bonded from the central portion M in the longitudinal direction toward both ends in the longitudinal direction. This is advantageous to complete the bonding of the strip materials <NUM> in a shorter time.

In a case where the profile of the rigid core <NUM> is asymmetrical with respect to the center in the width direction, after bonding the central portion M in the longitudinal direction of the strip material <NUM> to be bonded to the molding surface 14a at the central portion in the width direction of the rigid core <NUM>, for example, the strip material <NUM> is bonded to the molding surface 14a from the central portion M in the longitudinal direction toward one end in the longitudinal direction. Then, the strip material <NUM> may be bonded to the molding surface 14a starting from the central portion M in the longitudinal direction toward the other end in the longitudinal direction.

By bonding the plurality of strip materials <NUM> to the molding surface 14a in this manner, the belt layer <NUM> illustrated in <FIG> is formed. In a case of forming a plurality of belt layers <NUM> on the green tire <NUM>, another belt layer <NUM> is formed on the outer circumferential side of the belt layer <NUM> by the same process.

In this embodiment, the movement in the strip width direction of the portion of the strip material <NUM> in close proximity to that bonded to the molding surface 14a is regulated by the guides <NUM>. Therefore, even when the strip material <NUM> is bonded to the molding surface 14a while the rigid core <NUM> is turned, it is advantageous to prevent defects that the strip material <NUM> already bonded to the molding surface 14a is deviated.

Next, in order to form the green tire <NUM> illustrated in <FIG>, necessary tire components such as a belt reinforcing layer, unvulcanized tread rubber <NUM>, and the like are sequentially bonded to the outer circumferential surface of the belt layer <NUM>. In this way, a green tire <NUM> having a belt layer <NUM> is formed.

Next, as illustrated in <FIG>, the green tire <NUM> and the rigid core <NUM> are disposed inside a vulcanization mold 11a installed in a vulcanization device <NUM>, and the vulcanization mold 11a is closed. Then, by vulcanizing the green tire <NUM> under predetermined conditions inside the closed vulcanization mold 11a, the tire <NUM> illustrated in <FIG> (the pneumatic tire <NUM> in this embodiment) is completed. After removed from the vulcanization mold 11a, the completed tire <NUM> is separated from the rigid core <NUM>.

In a case of manufacturing a tire <NUM> integrated with the wheel, the wheel may be used as the rigid core <NUM>, for example. When manufacturing a tire <NUM> having such a configuration, it is not necessary to separate the completed tire <NUM> from the rigid core <NUM> (wheel) after vulcanizing the green tire <NUM>.

In the forming device <NUM> described above, the belt layer <NUM> is formed such that the rigid core <NUM> is disposed above the bonding unit <NUM>; however, as in the case of the forming device <NUM> illustrated in <FIG>, the belt layer <NUM> may be formed such that the rigid core <NUM> is disposed below the bonding unit <NUM>. In the forming device <NUM>, the bonding unit <NUM> (base frame <NUM>) is installed in a fixed state of being suspended downward from the support surface, and the rigid core <NUM> is movable by the freely moving arm <NUM>.

The forming device <NUM> has a configuration in which the vertical position relationship of the rigid core <NUM> and the bonding unit <NUM> of the forming device <NUM> illustrated in <FIG> is reversed, and the other configurations are substantially the same. However, the forming device <NUM> has a support roller 9a on the outer side of each guide <NUM>. The strip material <NUM> is inserted between the pressing roller <NUM> and the guide <NUM> so as to span over the pair of pressing rollers <NUM>, and both end portions of the strip material <NUM> in the longitudinal direction are supported by the support rollers 9a.

In addition, in the forming device <NUM>, the pair of pressing rollers <NUM> can be moved vertically. The configuration that allows the pair of pressing rollers <NUM> to move vertically is not essential, and may be adopted as necessary.

In order to form the belt layer <NUM> using the forming device <NUM>, the same method described in the above embodiment may be used. When bonding the strip material <NUM> to the outer circumferential surface 14a of the carcass layer <NUM> bonded to the outer circumferential side of the rigid core <NUM>, the pair of pressing rollers <NUM> are moved downward as necessary. This makes it easier to adhere the strip material <NUM> to the outer circumferential surface 14a.

In another forming device <NUM> illustrated in <FIG> and <FIG>, the rigid core <NUM> is able to rotate about a center shaft 2a fixed to a supporting column 2c erected on the floor. In other words, the rigid core <NUM> is installed on the floor surface in a fixed state (a state in which the rigid core <NUM> is unable to move in a plane). The bonding unit <NUM> is installed in a manner movable to any arbitrary position by the freely moving arm <NUM>. The bonding unit <NUM> is able to turn about a revolution axis Z that extends vertically through the center of the pressing body <NUM> when viewed in a plan view. Note that the rigid core <NUM> is fixed so that it is unable to turn about the revolution axis Z.

In the procedure of manufacturing the tire <NUM> using this forming device <NUM>, similar to the previous embodiment, the belt layer <NUM> is formed by actuating the rigid core <NUM> and the bonding unit <NUM> along the profile of the outer circumferential surface 2b of the rigid core <NUM> that is inputted to the control unit <NUM> and preliminarily known; however, in this embodiment, the bonding unit <NUM> is moved. Thus, as illustrated in <FIG>, the pressing body <NUM> is moved upward of the strip material <NUM> in a state in which the strip material <NUM> spans over the pair of pressing rollers <NUM>. Accordingly, the central portion M of the strip material <NUM> in the longitudinal direction is pressed against the molding surface 14a and bonded at the central portion of the rigid core <NUM> in the width direction.

Next, the bonding unit <NUM> is moved upward so that the molding surface 14a is in close contact with the strip material <NUM> that is to be bonded to the molding surface 14a, and while turning the bonding unit <NUM> about the revolution axis Z of the rigid core <NUM>, the strip material <NUM> is bonded to the molding surface 14a in a manner of extending in the longitudinal direction. More specifically, with the upward movement of the bonding unit <NUM>, the revolution axis Z of the bonding unit <NUM> is made to coincide with the revolution axis Z of the rigid core <NUM> in a direction in which the angle of the circumferential direction of the rigid core <NUM> with respect to the longitudinal direction of the strip material <NUM> to be bonded changes, and the bonding unit <NUM> is turned about that revolution axis Z, so that the variation in the bonding margin, due to the position in the width direction of the rigid core <NUM> (the bonding length in the circumferential direction of the opposing end surfaces of the strip materials <NUM> adjacent in the circumferential direction), between the strip materials <NUM> that are to be bonded adjacent to each other in the circumferential direction of the molding surface 14a is reduced. Adjacent strip materials <NUM> are brought essentially in contact and bonded, and thus the bonding margin is neither plus nor minus, but is close to zero.

At both end portions in the width direction in the range corresponding to the tread of the rigid core <NUM>, the circumferential length of the molding surface 14a is shorter than that of the central portion in the width direction. Therefore, when bonding the strip material <NUM>, the bonding unit <NUM> is turned such that the inclination angle a is larger at both end portions in the width direction than at the center in the width direction.

Then, as illustrated in <FIG>, with the rotation of the bonding unit <NUM>, the pair of pressing rollers <NUM> are horizontally moved in a direction away from each other. As a result, the strip material <NUM> to be bonded is sandwiched between the molding surface 14a and the pressing rollers <NUM>, and the strip material <NUM> is extended in the longitudinal direction and pressed against the molding surface 14a and bonded.

By bonding a large number of strip materials <NUM> to the molding surface 14a in this manner, the belt layer <NUM> illustrated in <FIG> is formed. The subsequent steps are the same as in the previous embodiment. Note that the arrangement described in the previous embodiment may be similarly applied to this embodiment as well.

Claim 1:
A method for manufacturing a tire (<NUM>), comprising
sequentially bonding a large number of strip materials (<NUM>) on a molding surface (14a) located on an outer circumferential side of a rigid core (<NUM>) having an outer circumferential surface (2b) with a profile in which a circumferential length changes at a position in a width direction in a manner of extending the strip materials (<NUM>) in a width direction of the rigid core (<NUM>) at an inclined direction with respect to a circumferential direction of the rigid core (<NUM>), and
arranging and bonding the strip materials (<NUM>) in the circumferential direction, so that a belt layer (<NUM>) is formed by bonding together the strip materials (<NUM>) that are adjacently bonded in the circumferential direction; forming a green tire (<NUM>) having the belt layer (<NUM>); and vulcanizing the green tire (<NUM>), wherein,
the rigid core (<NUM>) is relatively moved along the profile that is preliminarily known so that the molding surface (14a) is brought close to the strip material (<NUM>) to be bonded to the molding surface (14a), and
the strip materials (<NUM>) to be bonded are extended in the longitudinal direction and bonded to the molding surface (14a) while relatively turning the rigid core (<NUM>) in a direction in which a circumferential angle with respect to the longitudinal direction of the strip materials (<NUM>) to be bonded changes, so that variation in bonding margin, due to the position in the width of the rigid core (<NUM>), between the strip materials (<NUM>) to be bonded adjacent to each other in the circumferential direction is reduced, wherein after bonding the central portion in the longitudinal direction of the strip material (<NUM>) to be bonded to the molding surface (14a) at a central portion of the rigid core (<NUM>) in the width direction, the strip material (<NUM>) to be bonded is bonded to the molding surface (14a) from the central portion in the longitudinal direction toward one end in the longitudinal direction, then the strip material (<NUM>) to be bonded is bonded to the molding surface (14a) from the central portion in the longitudinal direction toward the other end in the longitudinal direction.