JP4593954B2 - Raw tire forming method and pneumatic tire - Google Patents

Description

  The present invention relates to a green tire forming method and a pneumatic tire that can reduce the meandering of a carcass cord when a tread ring is pressed and stuck to a green tire base.

  In the manufacturing process of a raw tire (a tire before vulcanization) in a radial tire, as shown in FIGS. 7A and 7B, a raw tire in which a cylindrical tread ring A formed in advance is expanded in a toroid shape. It is necessary to press the substrate B and paste it together.

  And as this sticking method, after a part of tread ring A is normally crimped | bonded to the top part of the expanded toroidal raw tire base B, this raw tire base B with a tread ring is rotated. Then, using the rotatable disk-shaped stitching roller e, the whole is pasted by pressing the tread ring A against the green tire base and gradually moving along the tread profile.

  However, in this sticking method using the stitching roller e, the pressing force by the stitching roller e becomes resistance, and a reaction force f in the direction opposite to the rotation direction of the green tire base B is generated. As a result, as shown in FIG. 8 in which the carcass ply b1 of the tire after vulcanization is developed in a plane between the tire maximum width positions, the carcass cord b1a has a radial reference line in the tread ring attachment portion. Arrangement disorder occurs that meanders in the direction of the reaction force f with respect to y.

  This meandering increases the length of the carcass cord between the bead cores, which necessitates the design of the length of the carcass cord in anticipation of the meandering amount δ. It causes the occurrence of uneven wear and the deterioration of uniformity.

  In order to suppress the meandering, Patent Document 1 proposes to increase the rigidity of the raw tire base B during expansion by reducing the volume of the air chamber that inflates the raw tire base B.

Japanese Patent Laid-Open No. 7-60868

  The present invention is based on the fact that 40 to 80% of the total number of rotations of the green tire substrate performed in the stitching process in which the tread ring is attached to the green tire substrate using the stitching roller is performed in the normal rotation and the rest is performed in the reverse rotation. As a raw tire, it is possible to easily suppress the meandering of the carcass cord while using a conventional raw tire forming device, and to suppress waste of material cost due to the meandering and growth of the outer diameter in the initial use of the tire. An object is to provide a forming method and a pneumatic tire.

In order to achieve the above object, the invention of claim 1 of the present application is directed to a belt ply and a tread rubber on an outer peripheral surface of a toroidal green tire base body in which a tire member including a carcass ply is disposed on a former and formed with expansion. Is a raw tire forming method in which an inner peripheral surface of a tread ring including a carcass ply is disposed on a former and a toroidal shape is formed by expansion. None, and the tread ring is formed into a ring shape in advance by a tread constituent member including a belt ply and a tread rubber, and at least a part of the outer peripheral surface of the raw tire base is expanded to the inner peripheral surface of the tread ring. An expansion step for pressure bonding, and the tread ring of a green tire base with a ring to which the tread ring is pressure bonded By pressing the outer peripheral surface of the tire against the raw tire base using a stitching roller, the relative rotation of the green tire base with the ring and the stitching roller and the relative lateral movement along the outer peripheral surface in the meridional section including the tire shaft A stitching step of attaching the tread ring to the green tire base, and the stitching process is performed from the pressing start point of the green tire base with the ring to the start point while the green tire with the ring and the stitching roller rotate relative to each other. A plurality of cycles of pressing until one cycle is performed, and a main cycle area in which the ring-attached tire base body is rotated in the main direction in a cycle of 40% or more and 80% or less of the plurality of cycles remains. characterized by having a sub-cycle zone to rotate the ring with raw tire base body in the opposite direction 20 to 60% of the cycle There.

  According to a second aspect of the invention, the sub cycle area continues after the rotation of the main cycle area.

  According to a third aspect of the present invention, the direction of the relative rotation of the main cycle region and the sub cycle region changes in the forward and reverse directions by one or more cycles.

According to a fourth aspect of the present invention, the tread rubber overlaps the start end surface of the tread rubber band having a start end surface that forms a mating surface that is inclined radially outwardly toward one side in the circumferential direction. It is formed by lap splicing with a terminal portion having a terminal surface,
The stitching process is characterized by starting relative rotation from the one side toward the other side.

Further, in the invention of claim 5, the pressing is performed only in the outward path from the start point to the end point on the tread end side in the one cycle, and the stitching roller is moved from the tread ring on the return path from the end point to the start point. It is characterized by floating and returning to the starting point.

  Since the present invention is configured as described above, it is possible to easily suppress the meandering of the carcass cord while using a conventional green tire forming apparatus.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, in the raw tire forming method of the present invention, a cylindrical raw tire base B1 disposed on the former F is formed into a toroidal shape by expansion, and the outer peripheral surface Sb of the toroidal raw tire base B2 is formed. Further, the inner peripheral surface Sai of the tread ring A is joined using the stitching roller 10.

  Here, in this example, the case where the green tire forming method is employed in a so-called two-stage molding method is illustrated. Therefore, in this example, as shown in FIG. 6A, the cylindrical raw tire base B1 is wound by winding the tire member b including the carcass ply b1 on the well-known cylindrical first former F1. Are separately formed and transferred onto the former F, which is the second former F2. However, it can also be employed in a so-called single stage molding method, in which case the cylindrical green tire base B1 is directly formed on a former F that is a single former. In the figure, reference numeral b2 is an inner liner rubber, b3 is a bead core, b4 is a bead apex rubber, and b5 is a side wall rubber, which are included in the tire member b.

  Further, as shown in FIG. 6B, the tread ring A is separately formed by winding a tread constituent member a including a belt ply a1 and a tread rubber a2 on a known tread ring forming drum D. .

In the raw tire forming method,
(1) As shown in FIG. 1, the raw tire base B1 is expanded in a toroidal shape so that at least a part of the outer peripheral surface Sb, specifically, the central part including the tire equator is disposed on the inner periphery of the tread ring A. An expansion step K1 for pressing and pressing the surface Sai
(2) As shown in FIG. 2, the outer peripheral surface Sao of the tread ring A of the ring-attached green tire base body B <b> 2 </ b> A to which the tread ring A is crimped is applied to the green tire base body B <b> 2 using the stitching roller 10 of the stitcher device 1. The tread ring A is closely attached to the raw tire base B2 by the relative rotation of the green tire base B2A with the ring and the stitching roller 10 and the relative lateral movement along the outer peripheral surface Sao in the meridional section including the tire shaft. And a stitching process K2 to be attached.

  In the expansion step K1, the raw tire base B1 is filled with air of a predetermined internal pressure while moving the bead cores b3 and b3 inward to a predetermined position (or via a bladder), thereby changing from a cylindrical shape to a toroidal shape. Inflate to.

  In the stitching process K2, in this example, the former F is rotated and driven to rotate the green tire base B2A with a ring held by the former F. Further, in this example, the stitcher device includes a pair of rotatable disk-like stitching rollers 10 and 10. Each stitching roller 10 is a tire by a supporting means (not shown) controlled by a CPU or the like, for example. Lateral movement in the axial direction, vertical movement in the tire radial direction, and tilt movement within the meridional section are supported. As a result, each stitching roller 10 is placed on the outer circumferential surface Sao from the pressing start point P1 on the tire equator side to the end point P2 on the tread end side while maintaining a substantially right angle with the outer circumferential surface Sao of the tread ring A. The tread ring A can be tightly attached to the green tire base B2 with a substantially constant pressing force.

  At this time, in the stitching process K2, pressing is performed for a plurality of cycles, for example, 10 to 20 cycles (15 cycles in this example) with “start point P1 → end point P2 → start point P1” as one cycle.

  In the present invention, a cycle of 40% or more and 80% or less of the total cycle Y (15 cycles in this example) is defined as a main cycle region Y1 in which the green tire base B2A with a ring rotates in the main direction. The remaining 20 to 60% of the cycles are divided into sub-cycle areas Y2 that rotate in the reverse direction. By changing the rotation direction in this way, the influence of the reaction force f caused by the pressing of the stitching roller 10 can be canceled in the main cycle area Y1 and the subcycle area Y2, and the meandering amount δ of the carcass cord b1a is increased. It is possible to reduce the width.

  When the main cycle area Y1 is 40% or less of the total cycle Y, the influence of the sub-cycle area Y2 becomes large. When the main cycle area Y1 is 80% or more, the influence of the main cycle area Y1 becomes large. I can't get it.

  Here, in the stitching step K2, as shown in FIG. 3A, the sub cycle area Y2 is continued after the main cycle area Y1, that is, the main cycle area Y1 is concentrated in the first half of the total cycle Y. In the latter half, it is preferable to concentrate the sub cycle area Y2 from the viewpoint of work efficiency. However, in this case, if the reverse rotation is started at a time point when it has not reached 40% of the total cycle Y, the influence of the sub-cycle area Y2 tends to occur, and the meandering value of the reverse direction of the carcass code b1a increases. Further, even if the reverse rotation is started when the value exceeds 80%, the meandering suppression effect is not exhibited. Therefore, the main cycle area Y1 is preferably set in a range of 50 to 70% of the total cycle Y.

  From the viewpoint of suppressing meandering, as shown in FIG. 3B, it is also preferable to divide the main cycle area Y1 and the sub cycle area Y2 into one or more cycles and perform them alternately. In this case, the number of changes in the rotation direction increases, which is disadvantageous for work efficiency. However, the effect of suppressing meandering is enhanced because the influence of the reaction force f can be canceled early. Also in this case, the meandering suppression effect is more effectively exhibited when the main cycle region Y1 is in the range of 40 to 80% of the total cycle Y, preferably in the range of 50 to 70%.

  It should be noted that in one cycle of “start point P1 → end point P2 → start point P1”, pressing is performed only in the forward path of “start point P1 → end point P2”, and on the return path of “end point P2 → start point P1”. Can also lift the stitching roller 10 from the tread ring A and return it to the starting point P1.

  Further, as shown in FIG. 4, the tread rubber a2 includes a start end portion Ef of a tread rubber band G having a start end surface Jf that forms a mating surface J inclined to one side in the circumferential direction outward in the radial direction, It is formed in a ring shape by overlapping the end portion Er having the end surface Jr overlapping the start end surface Jf. Therefore, in order to keep the joint of the lap joint well, the direction in which the green tire base B2A with ring is rotated with respect to the stitching roller 10 from the one side to the other side is set to the rotation direction of the main cycle region Y1. The stitching process K2 is preferably started from the cycle of the main cycle area Y1.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  A heavy-duty tire having a tire size of 11R22.5 was formed by vulcanization molding a raw tire using a stitching process having the specifications shown in Table 1. Then, the meandering amount of the carcass cord, the outer diameter growth amount, and the uneven wear amount of each sample tire were measured and evaluated mutually. The specifications are substantially the same except for the specifications in Table 1.

(1) Carcass cord meandering amount:
The vulcanized tire was disassembled and, as shown in FIG. 8, a point m at one tire maximum width position of one carcass cord b1a and a point m at the other tire maximum width position were connected. A straight line was used as a reference line y, and the maximum meandering amount δ of the carcass cord b1a from the reference line y was measured. The measurement was performed at four positions 90 ° apart in the circumferential direction for one tire, and the average value was taken as the meandering amount of the tire. Table 1 shows the average value of five tires. + Means meandering in the main direction.

(2) Tire outer diameter growth:
The sample tire was run on the drum at a speed of 80 km / h for 500 km under the conditions of a rim (7.50 × 22.5), internal pressure (850 kPa), and load (26.26 kN). The tire circumference difference was converted into a diameter difference and described. Table 1 shows the average value of five tires.

(3) Uneven wear amount:
The amount of shoulder wear when a sample tire is mounted on the front wheel of a vehicle (2-D / 4 type vehicle) under the conditions of a rim (7.50 × 22.5) and internal pressure (850 kPa) and travels 80000 km. It was measured. Note that the measurement was performed at four positions 90 ° apart in the circumferential direction for one tire, and the average value was defined as the amount of wear of the tire. Table 1 shows the average values of the four tires. As shown in FIG. 5, the shoulder wear amount is determined by taking a single arc closest to the end portions p2 to p9 excluding the tread ends p1 and p10 among the end portions p1 to p10 of the rib (or block) as the reference line y. As a distance γ between the tread ends p1 and p10 from the reference line y.

  As shown in the table, it can be confirmed that the tires of the examples according to the present invention can suppress the meandering of the carcass cord and suppress uneven wear such as the growth of the tire outer diameter and the accompanying shoulder wear.

It is a diagram which shows the expansion | swelling process in the raw tire formation method of this invention. It is a diagram which shows the stitch process. (A), (B) is a diagram explaining the main cycle area and the sub cycle area in a stitch process. It is a diagram explaining the rotation direction of the green tire base with a ring in the main cycle area. It is a diagram explaining the measuring method of the amount of partial wear in Table 1. (A), (B) is sectional drawing which shows a green tire base | substrate and a tread ring. (A), (B) is a diagram explaining background art. It is a diagram explaining the problem. FIG.

Explanation of symbols

10 Stitching roller A Tread ring a Tread component a1 Belt ply a2 Tread rubber B2 Raw tire base B2A Raw tire base with ring b Tire member b1 Carcass ply F Former K1 Expansion process P1 Pressing start point Y Total cycle Y1 Main cycle area Y2 Secondary cycle area

Claims (5)

A tire member including a carcass ply is disposed on a former and an inner peripheral surface of a tread ring including a belt ply and a tread rubber is formed on an outer peripheral surface of a toroidal raw tire base formed with expansion using a stitching roller. A raw tire forming method to be pasted,
The green tire base has a tire member including a carcass ply disposed on a former and is formed into a toroidal shape by expansion, and the tread ring is previously formed into a ring shape by a tread component including a belt ply and tread rubber. ,
An expansion step of pressure-bonding at least part of the outer peripheral surface to the inner peripheral surface of the tread ring by the expansion of the raw tire base;
While rotating the outer peripheral surface of the tread ring of the green tire base with a ring to which the tread ring is pressed against the green tire base using a stitching roller, the relative rotation between the green tire base with the ring and the stitching roller; and Including a stitching step of attaching a tread ring to a raw tire base by relative lateral movement along an outer peripheral surface in a meridional section including a tire shaft,
In the stitching process, the ring-equipped tire and the stitching roller are rotated relative to each other, and a plurality of cycles of pressing are performed with one cycle from the pressing start point of the ring-attached raw tire base to the start point. ,
A main cycle region in which the ring-attached tire base body is rotated in the main direction in a cycle of 40% or more and 80% or less of the plurality of cycles, and the ring-attached tire base body in the reverse direction in the remaining 20 to 60% cycles. A raw tire forming method comprising: a sub-cycle region that is rotated in a straight line.   The raw tire forming method according to claim 1, wherein the sub-cycle region continues after rotation of the main cycle region.   The raw tire forming method according to claim 1, wherein the main cycle region and the sub cycle region change the direction of relative rotation in a forward and reverse direction by one or more cycles. The tread rubber includes a start end portion of a tread rubber band having a start end surface that forms a mating surface inclined to one side in the circumferential direction toward the radially outer side, and a end portion having a end surface overlapping the start end surface. Formed by lap joints,
The raw tire forming method according to claim 1, wherein the stitching step starts relative rotation from the one side in the circumferential direction toward the other side.   In the one cycle, the pressing is performed only in the outward path from the start point to the end point on the tread end side, and the stitching roller is lifted from the tread ring and returned to the start point on the return path from the end point to the start point. The raw tire formation method according to any one of claims 1 to 4.

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