MANUFACTURING METHOD AND FORMING DEVICE FOR TIRE

Provided are a tire manufacturing method and a tire forming device. One band-like strip material is sequentially supplied through one strip material supply line. By repeating a step of bonding the strip material placed in an arrangement unit by a holding machine to a forming surface on the outer circumferential side of the rigid core using a bonding mechanism, a belt layer in which the strip materials are arranged in the circumferential direction with reinforcing cords inclined at a predetermined inclination angle with respect to the circumferential direction of the rigid core. The strip material held by the holding machine is turned upside down and placed on the arrangement unit to construct a belt multilayer structure in which the inclination directions of the reinforcing cords of vertically adjacent belt layers are opposite to each other, thereby forming a green tire including the belt multilayer structure.

TECHNICAL FIELD

The present technology relates to a tire manufacturing method and a tire forming device and particularly relates to a tire manufacturing method and a tire forming device capable of making equipment more compact when forming a belt layer by sequentially arranging and bonding a large number of strip materials to an outer circumference of a rigid core in a circumferential direction and bonding the strip materials that are adjacent to each other in the circumferential direction.

BACKGROUND ART

A method is known in which, in a tire manufacturing process, a rigid core having an outer circumferential surface shape corresponding to a tire inner circumferential surface shape of a completed tire is used. Tire components are sequentially layered on the outer circumference of the rigid core to form a green tire (see, for example, Japan Unexamined Patent Publication No. 2019-142040 A). In the technology of Japan Unexamined Patent Publication No. 2019-142040 A, in order to form a belt layer, a large number of strip materials are used, the strip materials being formed by coating, with an unvulcanized rubber, a plurality of reinforcing cords arranged in parallel with each other. The strip materials are sequentially arranged in the circumferential direction of the rigid core such that the reinforcing cords extend in the width direction of the rigid core at a predetermined inclination angle with respect to the circumferential direction of the rigid core.

A plurality of layered belt layers are generally layered such that the inclination direction of each reinforcing cord with respect to the circumferential direction of the rigid core is in an opposite direction for each layer. Therefore, when a green tire is formed, it is necessary to prepare two types of strip materials in which the inclination directions of the reinforcing cords with respect to the circumferential direction of the rigid core are opposite to each other. If supply lines for supplying the two types of strip materials to the rigid core are individually provided, there is a problem of equipment becoming large.

SUMMARY

The present technology provides a tire manufacturing method and a tire forming device capable of making equipment more compact when forming a belt layer by bonding strip materials adjacent to each other in a circumferential direction on a forming surface positioned on an outer circumferential side of a rigid core.

A tire manufacturing method according to an embodiment of the present technology includes:sequentially arranging and bonding one band-like strip material including a plurality of reinforcing cords arranged in parallel with each other and coated with an unvulcanized rubber to a forming surface located on an outer circumferential side of a rigid core in a circumferential direction of the rigid core such that the reinforcing cords are extended in an oblique direction at a predetermined inclination angle with respect to the circumferential direction, thereby forming a belt layer in which the strip materials that are bonded adjacent to each other in the circumferential direction are bonded;constructing a belt multilayer structure by layering a plurality of the belt layers in which the reinforcing cords of the belt layers vertically adjacent to each other have opposite inclination directions with respect to the circumferential direction;forming a green tire having the belt multilayer structure; andvulcanizing the green tire,the method comprising:when constructing the belt multilayer structure, forming each of the belt layers by repeatedly performing a step of holding, by a holding machine, the one strip material supplied through one strip material supply line, moving and placing the strip material into an arrangement unit, and bonding the strip material placed in the arrangement unit to the forming surface, in which the strip material held by the holding machine is turned upside down and placed in the arrangement unit so that the inclination directions of the reinforcing cords of the belt layers vertically adjacent to each other are opposite to each other.

A tire forming device according to an aspect of the present technology includes: an arrangement unit in which one band-like strip material including a plurality of reinforcing cords arranged in parallel with each other and covered with an unvulcanized rubber is placed; anda bonding mechanism that relatively moves at least one of a rigid core and the arrangement unit with respect to the other, the tire forming device being configured such thatthe bonding mechanism relatively moves at least one of the rigid core and the arrangement unit,the one strip material placed in the arrangement unit is sequentially arranged and bonded to a forming surface located on an outer circumferential side of the rigid core in a circumferential direction of the rigid core such that the reinforcing cords are extended in an oblique direction at a predetermined inclination angle with respect to the circumferential direction,the strip materials that are bonded adjacent to each other in the circumferential direction are bonded to form a belt layer, anda belt multilayer structure is constructed by layering a plurality of the belt layers in which the reinforcing cords of the belt layers vertically adjacent to each other have opposite inclination directions with respect to the circumferential direction,the tire forming device comprising:one strip material supply line that sequentially supplies the one strip material; anda holding machine that holds the strip material that is supplied and moves and places the strip material into the arrangement unit,the holding machine comprising a turning mechanism that turns upside down the strip material that is held, and when reversing the inclination directions of the reinforcing cords of the belt layers vertically adjacent to each other, the strip material held by the holding machine being turned upside down and placed in the arrangement unit.

According to the present technology, a strip material can be turned upside down and placed in an arrangement unit by a holding machine that holds a strip material that is sequentially supplied. Therefore, in order to form a belt layer by sequentially arranging and bonding a large number of strip materials to the outer circumference of the rigid core in the circumferential direction and to construct a belt multilayer structure in which the inclination directions of the reinforcing cords of vertically adjacent belt layers are opposite to each other, one strip material supply line for sequentially supplying one strip material may be provided. That is, it is not necessary to separately provide supply lines for supplying two types of strip materials in which the inclination directions of the reinforcing cords are opposite to each other. Accordingly, the equipment for constructing the belt multilayer structure can be made more compact, so that a wide installation space for the equipment is not required, which contributes to a reduction in equipment cost.

DETAILED DESCRIPTION

A tire manufacturing method and a tire forming device according to embodiments of the present technology will be described below with reference to the drawings.

In a tire manufacturing method according to an embodiment of the present technology, a green tire G is formed using a tire forming device1according to an embodiment of the present technology illustrated inFIGS.1to3, and the formed green tire G is vulcanized to manufacture a tire T. Note that the present technology is not limited to general pneumatic tires and can be applied to the manufacturing of various tires T such as solid tires.

For forming the green tire G, a rigid core2formed of metal or the like and illustrated inFIG.4is used. The rigid core2has an outer circumferential surface shape corresponding to a tire inner circumferential surface shape of the completed tire T. Therefore, an outer circumferential surface2bof the rigid core2has a profile in which the circumferential length changes depending on a position in the width direction of the rigid core2. In general, the profile is such that the central portion in the width direction of the rigid core2protrudes more to the outer circumferential side than both end portions. The rigid core2is constituted of, for example, a plurality of segments divided in the circumferential direction about a center shaft2aand a support rod supporting the inner side of the segments.

Note that a width direction W and a circumferential direction L of the rigid core2correspond to the width direction and the circumferential direction of the green tire G and the completed tire T, respectively. A dot-dash line CL in the drawing indicates a tire axis (axial center of the center shaft2a), and a dot-dash line Z indicates a turning axis which is orthogonal to the dot-dash line CL and passes through the center of the rigid core2in the width direction W.

The forming device1includes an arrangement unit5in which one band-like strip material23is placed, a bonding mechanism3that relatively moves at least one of the rigid core2and the arrangement unit5with respect to the other, one strip material supply line10that sequentially supplies one strip material23, a holding machine13that holds each supplied strip material23and moves and places it into the arrangement unit5, and a control unit17. Operations of the bonding mechanism3, the arrangement unit5, the strip material supply line10, and the holding machine13are controlled by the control unit17. A computer is used as the control unit17. The number of control units17is not limited to one, and a plurality of the control units17can be provided.

The strip material23is formed by covering, with an unvulcanized rubber, a plurality of reinforcing cords23aarranged in parallel with each other. The extension direction of the reinforcing cord23ais the longitudinal direction of the strip material23. Both ends of the strip material23in the longitudinal direction are cut at a predetermined inclination angle a with respect to the longitudinal direction and become parallel to each other (the inclination angle a is an acute angle). A width H of one cut strip material23is, for example, 5 mm or more and 50 mm or less, and the length thereof is, for example, 200 mm or more and 800 mm or less. Thus, the strip material23is relatively small and light.

The strip material supply line10includes a conveying mechanism11for moving an elongated body of the strip material23in the longitudinal direction and a cutting portion12for cutting the elongated body to a predetermined length. As the conveying mechanism11, abase table or a conveying conveyor which moves forward and backward by a servo motor, a fluid cylinder, or the like can be used. In this embodiment, a round blade is adopted as the cutting portion12, but various known cutters can be used.

The holding machine13includes a holding arm14, a pair of gripping portions14adisposed at a leading edge portion of the holding arm14, a turning mechanism15for turning the holding arm14about an arm axial center, an advance/withdraw mechanism16afor moving the holding arm14toward and away from the arrangement unit5, and a positioning mechanism16bfor moving the holding arm14in a direction orthogonal to the advance/withdraw direction of the advance/withdraw mechanism16a. By moving the pair of gripping portions14acloser to each other, the strip material23is sandwiched and gripped between the gripping portions14a. By moving the pair of gripping portions14aaway from each other, gripping of the strip material23sandwiched between the gripping portions14ais released.

As the turning mechanism15, a servo motor or the like that turns the holding arm14by an arbitrary angle or by 180° can be used. As the advance/withdraw mechanism16aand the positioning mechanism16b, a servo motor, a fluid cylinder, or the like for moving the holding arm14can be used.

The arrangement unit5includes a base frame5aplaced in a fixed state on the floor, a pair of compression bonding rollers6attached to the base frame5a, and a movement mechanism7for horizontally moving the compression bonding rollers6toward and away from each other. The movement mechanism7is constituted of, for example, a ball screw and a servo motor for rotating the ball screw. Alternatively, a fluid cylinder or the like can be used as the movement mechanism7. Each of the compression bonding rollers6may be horizontally moved independently, or may be horizontally moved in synchronization with each other.

The arrangement unit5further includes a pressing body8which moves up and down between the compression bonding rollers6and guides9which are disposed in the vicinity of the respective compression bonding rollers6. Each of the guides9has guide rollers externally fitted thereto and at a distance in the axial direction of the rotation shaft. Each of the guides9is installed at a position on the outer side (the side in the direction in which the compression bonding rollers6move away from each other) with respect to the adjacent compression bonding roller6, and is horizontally movable together with the adjacent compression bonding roller6. Each of the guides9is preferably movable toward and away from the adjacent compression bonding roller6in the horizontal direction.

The bonding mechanism3bonds one strip material23placed in the arrangement unit5to a forming surface21apositioned on the outer circumferential side of the rigid core2. In this embodiment, a universal arm4for moving the rigid core2to an arbitrary position is used as the bonding mechanism3. An industrial robot or the like can be exemplified as the universal arm4. The center shaft2aof the rigid core2is held at the leading edge portion of the universal arm4, and the rigid core2is rotatable about the center shaft2a. The rigid core2is also rotatable about a turning axis Z.

The bonding mechanism3is not limited to a configuration in which the rigid core2is moved with respect to the arrangement unit5(base frame5a) fixed at a predetermined position as in this embodiment, and may be configured such that the arrangement unit5is moved with respect to the rigid core2fixed at a predetermined position or may be configured such that both the rigid core2and the arrangement unit5are moved.

Next, an example of a procedure for manufacturing the tire T by the tire manufacturing method according to an embodiment of the present technology will be described.

On the outer circumferential surface2bof the rigid core2illustrated inFIG.4, predetermined tire components (an innerliner19, a carcass layer21, and the like) are sequentially bonded by a known method as illustrated inFIG.5. Specifically, the innerliner19and the carcass layer21are sequentially layered and bonded to the outer circumferential surface2bof the rigid core2to form cylindrical shapes, respectively. On both side surfaces of the rigid core2in the width direction, ring-shaped bead members20are disposed on the carcass layer21, and the carcass layer21is folded back around a bead core20aof each bead member20. Further, unvulcanized side rubbers24are layered and bonded to both end portions of the carcass layer21in the width direction. Other tire components are bonded thereto as necessary.

Next, a cylindrical belt multilayer structure22is constructed on the outer circumferential surface (forming surface21a) of the cylindrical carcass layer21bonded to the outer circumferential side of the rigid core2inFIG.5. The belt multilayer structure22is formed by vertically layering cylindrical belt layers22a. Each belt layer22ais formed by bonding a large number of strip materials23. The strip material23is formed by coating a plurality of reinforcing cords23awith an unvulcanized rubber.

As illustrated inFIG.6, in order to form the belt layer22a(belt multilayer structure22), the strip material23is supplied to the holding machine13from a supply source through the strip material supply line10. The elongated body of the strip material23is supplied toward the holding machine13by a preset length of one strip material23. The holding machine13is placed in the middle of the strip material supply line10.

The cutting portion12cuts the supplied elongated body of the strip material23to a preset length of one piece to form one strip material23. Both ends of the strip material23in the longitudinal direction are cut at a predetermined inclination angle a with respect to the longitudinal direction so as to be parallel to each other. The cut one strip material23is disposed in front of the holding machine13. At this time, the gripping portions14aof the holding machine13are at a standby position.

Next, as illustrated inFIG.7, the holding arm14is advanced by the advance/withdraw mechanism16a, and a longitudinal center portion M of the strip material23is vertically sandwiched and gripped by the pair of gripping portions14a. The holding arm14is moved by the positioning mechanism16bto position the longitudinal center portion M of the strip material23at an intermediate position (position of the pressing body8) between the pair of compression bonding rollers6of the arrangement unit5. The cutting portion12is moved to the standby position.

Next, as illustrated inFIG.8, the holding arm14is further advanced by the advance/withdraw mechanism16ato be moved to above the arrangement unit5(the pair of compression bonding rollers6). The moved one strip material23is disposed so as to be bridged on the pair of compression bonding rollers6. At this time, the pair of compression bonding rollers6are positioned close to each other, and the pressing body8is positioned so as not to protrude upward from each compression bonding roller6. Note that, inFIGS.8to14,16, and17described below, tire components other than the belt layer22a(strip material23) are omitted and not illustrated.

Thereafter, the gripping portions14aare moved away from each other to release the gripping of the strip material23, and as illustrated inFIG.9, the holding arm14is retracted to the standby position by the advance/withdraw mechanism16a. The strip material23is inserted between the respective guides9and the adjacent compression bonding rollers6. As a result, one strip material23is set on the pair of compression bonding rollers6in a state where the longitudinal center portion M thereof is positioned above the pressing body8.

The separation distance between the guide rollers of the respective guides9is set slightly larger than a strip width H of the strip material23, The shape data of the rigid core2is input to the control unit17, and profile data of the outer circumferential surface2bwhose circumferential length varies depending on a position in the width direction is also input thereto. Various kinds of data such as shape data (lengths, widths, thicknesses) of the tire components (19,20,21,22aand the like) to be used and specification data of the green tire G to be formed are also inputted.

Next, the rigid core2and the bonding mechanism3are caused to cooperate with each other to bond the strip material23set in the arrangement unit5to the outer circumferential surface of the carcass layer21layered on the outer circumferential side of the rigid core2. That is, the outer circumferential surface of the carcass layer21serves as a forming surface21ato which the strip material23is to be bonded.

In order to form the belt layer22a, a large number of strip materials23(reinforcing cords23a) are sequentially bonded to the forming surface21aso as to be extended in a direction oblique (inclination angle a) to the circumferential direction of the rigid core2and arranged in the circumferential direction. Then, the strip materials23bonded to the forming surface21aadjacent to each other in the circumferential direction are bonded together to form the belt layer22a.

As described above, the outer circumferential surface2bof the rigid core2has a profile in which the circumferential length varies depending on a position in the width direction. Since the innerliner19and the carcass layer21sequentially bonded to the outer circumferential surface2bare members having constant thicknesses, the forming surface21ato which the strip material23is bonded also has a profile in which the circumferential length (length in the circumferential direction) varies depending on a position in the width direction similarly to the outer circumferential surface2b.

Therefore, the belt layer22ais formed by operating the rigid core2and the bonding mechanism3based on the profile of the outer circumferential surface2bof the rigid core2which is input to the control unit17and grasped in advance. First, as illustrated inFIG.10, the pressing body8is moved upward with respect to the strip material23bridged between the pair of compression bonding rollers6. As a result, the longitudinal center portion M of the strip material23is pressed against the forming surface21aat the central portion of the rigid core2in the width direction to be bonded.

Next, as illustrated inFIG.11, the rigid core2is moved downward so that the forming surface21ais brought close to the strip material23to be bonded to the forming surface21a, and the strip material23is extended in the longitudinal direction and bonded to the forming surface21awhile the rigid core2is turned about the turning axis Z. More specifically, along with the downward movement of the rigid core2, the rigid core2is turned in a direction in which an angle in the circumferential direction of the rigid core2with respect to the longitudinal direction of the strip material23to be bonded changes so as to reduce variation in a bonding margin between the strip materials23to be bonded adjacent to each other in the circumferential direction of the forming surface21a(bonding length in the circumferential direction between facing end surfaces of the strip materials23adjacent to each other in the circumferential direction) depending on the position of the rigid core2in the width direction. Since the adjacent strip materials23are basically butted and bonded to each other, the bonding margin is not plus or minus but is brought close to 0.

The circumferential length of the forming surface21ais shorter at both end portions in the width direction of a range corresponding to a tread of the rigid core2than at the central portion in the width direction. Therefore, when the strip material23is bonded, the rigid core2is turned so that the inclination angle a becomes larger at both end portions in the width direction than at the central portion in the width direction.

Along with the turning of the rigid core2, the pair of compression bonding rollers6are horizontally moved in directions away from each other. Thus, the strip material23to be bonded is sandwiched between the forming surface21aand the compression bonding rollers6, and the strip material23is extended in the longitudinal direction and is pressed against and bonded to the forming surface21a.

For example, when it is preset that N strip materials23having the same specifications (strip widths H) are used to form the belt layer22a, the rigid core2is turned as follows. A circumferential length K of the forming surface21aat a position of the rigid core2in the width direction illustrated inFIG.12can be determined in advance. When the strip material23is bonded at the inclination angle a with respect to the circumferential direction of the rigid core2, a length T of the strip material23with respect to the circumferential direction of the rigid core2at the position in the width direction is T=H/Sin (a). Since the circumferential length K=the length T×N, the following equation (1) is derived.

Therefore, when each strip material23is bonded to the forming surface21a, the rigid core2is turned so that the inclination angle a of the strip material23satisfies the above equation (1) in accordance with the position of the rigid core2in the width direction.

In this embodiment, since the profile of the rigid core2is symmetrical with respect to the center in the width direction, the longitudinal center portion M of the strip material23to be bonded is bonded to the forming surface21aat the central portion of the rigid core2in the width direction, and then the strip material23is bonded from the longitudinal center portion M toward both ends in the longitudinal direction. Accordingly, it is advantageous for completing bonding of the strip material23in a shorter time.

When the profile of the rigid core2is asymmetric with respect to the center in the width direction, for example, the longitudinal center portion M of the strip material23to be bonded is bonded to the forming surface21aat the central portion of the rigid core2in the width direction, and then the strip material23is bonded to the forming surface21afrom the longitudinal center portion M toward one end in the longitudinal direction. Thereafter, the strip material23may be bonded to the forming surface21afrom the longitudinal center portion M toward the other end in the longitudinal direction.

In this embodiment, a portion of the strip material23immediately before being bonded to the forming surface21ais restricted from moving in the strip width direction by each guide9. Therefore, even when the strip material23is bonded to the forming surface21awhile the rigid core2is turned, it is advantageous to prevent such a problem that the strip material23already bonded to the forming surface21ais shifted and moved by this strip material23.

By repeating the step of sequentially bonding one strip material23to the forming surface21ain this manner, each belt layer22aillustrated inFIG.13is formed. InFIG.13, of the belt layers22aon the inner circumferential side and the outer circumferential side constituting the belt multilayer structure22, the belt layer22aon the inner circumferential side is formed in a cylindrical shape and completed, but the belt layer22aon the outer circumferential side is in an incomplete state.

In the belt layer22aon the inner circumferential side and the belt layer22aon the outer circumferential side, the inclination directions of the respective reinforcing cords23awith respect to the circumferential direction of the rigid core2are opposite to each other. Therefore, the holding machine13of the forming device1is provided with a turning mechanism15. When the belt layer22aon the outer circumferential side is layered on the belt layer22aon the inner circumferential side for formation, the forming surface21ato which the strip material23is bonded is a surface of the belt layer22aon the inner circumferential side.

When the belt multilayer structure22is constructed, as illustrated inFIGS.14and15, the holding arm14of the holding machine13holding one strip material23is turned about the arm axial center by the turning mechanism15. Accordingly, the strip material23held by the holding machine13is turned upside down about an axis orthogonal to the longitudinal direction of the strip material23.

The holding arm14is further advanced to place the turned strip material23in the arrangement unit5(the pair of compression bonding rollers6). A step before the strip material23is held by the holding machine13and a step after the strip material23is placed in the arrangement unit5are the same as in the case of forming the belt layer22aon the inner circumferential side. However, the orientation of the rigid core2in a plan view is opposite to that inFIG.8(the orientation is symmetrical with respect to the axial center direction of the holding arm14).

In this way, the strip material23set in the arrangement unit5is turned upside down and a series of steps is sequentially repeated to form the belt layer22aon the outer circumferential side and construct the belt multilayer structure22. In order to stably turn the strip material23, it is preferable that the longitudinal center portion M of the strip material23is gripped by the pair of gripping portions14a.

The holding machine13may have any structure as long as it can turn the strip material23upside down, and thus other structures may be employed. In the holding machine13illustrated inFIGS.16and17, a hydraulic cylinder for advancing/withdrawing the holding arm14having the pair of gripping portions14aat the tip thereof is used as the positioning mechanism16b, and a servo motor or the like for moving the holding arm14along a rail extending in a direction orthogonal to the advance/withdraw direction of the holding arm14is used as the advance/withdraw mechanism16a.

As illustrated inFIG.16, in the holding machine13, one strip material23supplied through the strip material supply line10is inserted between the pair of gripping portions14afrom one end portion side in the longitudinal direction and sandwiched and held between the gripping portions14a. The strip material23is preferably held such that the center portion of the strip material23in the width direction coincides with the arm axial center of the holding arm14. Thereafter, the holding arm14is moved toward the arrangement unit5by the advance/withdraw mechanism16a.

Next, as illustrated inFIG.17, at a position between the strip material supply line10and the arrangement unit5, the holding arm14of the holding machine13holding one strip material23is turned about the arm axial center by the turning mechanism15. Accordingly, the strip material23held by the holding machine13is turned upside down about a parallel axis with respect to the longitudinal direction of the strip material23.

Thereafter, the holding arm14is moved above the arrangement unit5(the pair of compression bonding rollers6) by using the advance/withdraw mechanism16aand the positioning mechanism16b, and the turned strip material23is placed in the arrangement unit5. As described above, when the strip material23is turned upside down, the strip material23can be turned about an orthogonal axis with respect to the longitudinal direction of the strip material23or can be turned about a parallel axis with respect to the longitudinal direction of the strip material23. Whether the strip material23is turned about the orthogonal axis or the parallel axis is determined in consideration of a placement space of the equipment or the like but the structures illustrated inFIGS.14and15are advantageous for more accurately placing the strip material23at a predetermined position of the arrangement unit5.

In order to form the green tire G illustrated inFIG.18, after the belt multilayer structure22is constructed by the above-described procedure, necessary tire components such as the belt reinforcing layer and the unvulcanized tread rubber25are sequentially bonded to the outer circumferential surface of the belt multilayer structure22. Thus, the green tire G having the belt multilayer structure22is formed.

Next, as illustrated inFIG.19, the green tire G is disposed together with the rigid core2inside a vulcanization mold18aplaced in a vulcanization device18, and the vulcanization mold18ais closed. Next, the green tire G is vulcanized under predetermined conditions inside the closed vulcanization mold18a, thereby completing the tire T (the pneumatic tire T in this embodiment) illustrated inFIG.20. After being removed from the vulcanization mold18a, the rigid core2is separated from the completed tire T.

When manufacturing a tire T integrated with a wheel, for example, the wheel can be used as the rigid core2. When manufacturing the tire T having such specifications, it is not necessary to separate the completed tire T from the rigid core2(wheel) after the green tire G is vulcanized.

As described above, according to an embodiment of the present technology, the strip material23can be turned upside down and placed in the arrangement unit5by the holding machine13that holds the strip material23that is sequentially supplied. Therefore, in order to construct the belt multilayer structure22in which the inclination directions of the reinforcing cords23aof the vertically adjacent belt layers22aare opposite to each other, the forming device1only needs to include one strip material supply line10that sequentially feeds one strip material23to the holding machine13.

When separate supply lines are provided to supply two types of strip materials23in which the inclination directions of the reinforcing cords23aare opposite to each other in order to construct the belt multilayer structure22, it is necessary to provide the conveying mechanism11, the cutting portion12, the holding machine13, and the like for each of the two types of strip materials23. That is, since it is necessary to provide the same equipment in duplicate, there arises a demerit that a wider space is required for placing the equipment and a demerit that equipment cost is increased. In addition, there is also a demerit that it is disadvantageous to increase the operation rate of the equipment provided in duplicate.

Since only one strip material supply line10is required in the present technology, the equipment for constructing the belt multilayer structure22can be made considerably more compact. Accordingly, the above-described various demerits can be eliminated.

It is more preferable that the cutting angle with respect to the strip material23by the cutting portion12be able to be arbitrarily set. With this configuration, the reinforcing cords23aof the strip material23to be bonded can be set at an arbitrary predetermined inclination angle a with respect to the circumferential direction of the rigid core2. Therefore, the forming device1has high versatility and can form the green tire G with more various specifications.

When the outer circumferential surface2bof the rigid core2has a profile in which the circumferential length varies depending on a position in the width direction, as described above, each strip material23is bonded to the forming surface21ato form the belt layer22aon the basis of the profile data grasped in advance. Therefore, it is advantageous to prevent a problem that the strip materials23bonded to the forming surface21aand adjacent to each other in the circumferential direction excessively overlap each other in the circumferential direction or a problem that a gap in the circumferential direction is generated between the adjacent strip materials23. Therefore, it is possible to suppress a bonding disturbance between the strip materials23caused by the circumferential length of the outer circumferential surface2bof the rigid core2which varies depending on a position in the width direction. This also contributes to improvement in quality of the manufactured tire T.

In the above-described forming device1, the belt layer22ais formed in a state where the rigid core2is disposed above the arrangement unit5. However, as in the forming device1illustrated inFIG.21, the rigid core2may be disposed below the arrangement unit5to form the belt layer22a(belt multilayer structure22). In the forming device1, the arrangement unit5(base frame5a) is suspended downward from a support surface and placed in a fixed state, and the rigid core2can be moved by the universal arm4.

This forming device1has a configuration in which the vertical relationship between the rigid core2and the arrangement unit5of the forming device1illustrated inFIGS.1and2is reversed, and other configurations are substantially the same. However, the forming device1has the support rollers9aoutside the respective guides9. The strip material23is inserted between the compression bonding rollers6and the guides9and bridged between the pair of compression bonding rollers6, and both end portions of the strip material23in the longitudinal direction are supported by the support rollers9a, respectively. In the forming device1, the configuration in which the pair of compression bonding rollers6can be moved up and down is not essential, and may be adopted as necessary. The procedure for forming the green tire G using the forming device1is the same as the procedure described in the previous embodiment.

In another embodiment of the forming device1illustrated inFIGS.22and23, the rigid core2is rotatable about the center shaft2afixed to a supporting column2cerected on the floor. That is, the rigid core2is placed in a fixed state on the floor (in a state where it cannot move in a plane). The arrangement unit5is placed to be movable to an arbitrary position by the universal arm4. The arrangement unit5is turnable about the turning axis Z extending vertically through the center of the pressing body8in a plan view. Note that the rigid core2is fixed so as not to be able to turn about the turning axis Z.

The procedure for forming the green tire C using the forming device1is the same as the procedure described in the previous embodiment. However, in this embodiment, the arrangement unit5is mainly moved.