JP4390187B2 - Pneumatic tire and method for manufacturing pneumatic tire - Google Patents

Description

The present invention relates to a pneumatic tire that exhibits excellent athletic performance and durability performance by increasing the number of ends of a winding portion of a carcass layer more than the number of ends of a main body, and a method for manufacturing the pneumatic tire .

  Conventionally, in order to improve the motion performance of pneumatic tires, the number of carcass plies forming the carcass layer is increased, or the rewinding height of the reversing portion of the carcass layer is increased outward in the tire radial direction to bend the tire side. A pneumatic tire is known in which the front and rear rigidity and the lateral rigidity of the tire are improved by increasing the rigidity of the portion.

  Conventionally, the manufacture of the carcass ply and the molding of the carcass layer have been performed as follows. First, a plurality of cords arranged in a calendar device are covered with rubber, and the obtained continuous cords having a constant width are cut into a predetermined length and joined together in the width direction of the cord to form a sheet-like carcass ply. And Next, the carcass ply is wound around the outer periphery of the drum, cut into a predetermined length, and both ends are joined to form a cylindrical shape. Subsequently, an annular bead wire is extrapolated in the vicinity of the end portion of the cylindrical carcass ply, the end portion is rewound through the bead wire, and the center portion is deformed so as to swell, thereby forming a carcass layer.

  In the carcass layer molded as described above, the number of ends (cord width) of the main body portion of the carcass layer disposed on the inner side in the tire axial direction of the bead portion and the rewinding portion that is wound back and disposed on the outer side of the bead portion. The number of cords per inch in the direction) is the same. Moreover, the height in the tire radial direction of the cord constituting the winding-up portion is constant in the tire circumferential direction, and when the winding-up height of the winding-up portion is increased, the height of the cord is also uniformly increased in the tire circumferential direction.

  Therefore, as described above, when the number of carcass plies is increased for the purpose of improving the motion performance of the pneumatic tire, not only the reversing portion of the carcass layer that effectively improves the front and rear stiffness and the lateral stiffness of the tire, but also the main body portion As the number of ends increases, an increase in tire weight is inevitable. In addition, an increase in the number of ends of the main body increases the longitudinal spring constant of the tire, and thus tends to deteriorate riding comfort. In addition, as described above, when the rewinding height of the rewinding portion is increased for the purpose of improving the motion performance of the pneumatic tire, the height of the cord in the tire radial direction is also uniformly increased in the tire circumferential direction. It became clear that the durability of the tire deteriorated.

  The pneumatic tire disclosed in the following Patent Document 1 disperses stress concentrated on the cord end by changing the height of the cord constituting the carcass layer alternately one by one or by a plurality of units. This is intended to suppress separation. According to the pneumatic tire, since the height of the cord in the tire radial direction can be varied in the tire circumferential direction, the reduction in the bending range of the tire side is suppressed when the rewinding height of the rewinding portion is increased. However, since there is a cord terminal in the winding portion, the durability performance of the tire is not sufficient.

  Moreover, the pneumatic tire disclosed in the following Patent Document 2 prevents bead portion damage such as edge separation by folding back a cord constituting the winding portion of the carcass layer into a U shape. However, in the pneumatic tire, the height of the cord in the tire radial direction cannot be changed in the tire circumferential direction, and when the rewinding height of the rewinding portion is increased, the cord in the tire radial direction is the same as in the past. The height increases uniformly in the circumferential direction, and the durability of the tire deteriorates.

Furthermore, in either of the following Patent Documents 1 and 2, since the number of ends is the same in the main body portion and the rewinding portion of the carcass layer, if the number of carcass plies is increased in order to improve the tire performance, the tire weight and Longitudinal spring constant increases and excellent exercise performance cannot be exhibited.
JP 2000-168309 A JP-A-9-156310

Accordingly, an object of the present invention is to provide a pneumatic tire excellent in exercise performance and durability performance by suppressing an increase in tire weight and an increase in longitudinal spring constant while improving the longitudinal rigidity and lateral rigidity of the tire. In particular, another object is to provide a method for manufacturing the pneumatic tire .

The above object can be achieved by the present invention as described below. That is, the pneumatic tire of the present invention includes a pair of annular bead portions, a main body portion of a carcass layer spanned between the pair of bead portions, and the carcass folded back to the outside of the tire via the bead portions. A plurality of first turning points arranged in a region disposed in the tire circumferential direction near at least one end in the tire axial direction of the carcass layer. And a plurality of second folding points arranged in the tire circumferential direction in the vicinity of the ply winding-up portion, and a cord that is sequentially folded back, and the number of ends of the winding-up portion (2.54 cm (1 inch in the cord width direction)) ) Is more than the number of ends of the main body.

  The pneumatic tire of the present invention does not increase the number of carcass plies, but increases the number of ends of the carcass layer only at the rewinding portion, thus increasing the longitudinal rigidity and the lateral rigidity without increasing the tire weight. Thus, the motion performance of the tire can be preferably improved. At that time, since the number of ends of the main body portion of the carcass layer does not increase as in the prior art, an increase in the vertical spring constant of the tire can be suppressed, and riding comfort performance can be ensured. Furthermore, the cords constituting the carcass layer are not used excessively, which can contribute to cost reduction. Since the cord constituting the winding portion is folded at the first folding point, stress is not concentrated on the cord terminal, and edge separation can be suitably prevented. Here, as shown in the tire cross-sectional view of FIG. 9, the ply rewind portion refers to a portion TU that is bent and bent when the end portion of the carcass ply 8 is folded to form the rewind portion 6b. The carcass layer extends in the tire circumferential direction, and the carcass ply before molding the carcass layer extends in the longitudinal direction. The number of ends refers to the number of cords per inch in the cord width direction.

  In the above, it is preferable that at least one side of the carcass layer in the tire axial direction has different heights in the tire radial direction of the first turning point in the tire circumferential direction.

  The height of the first turn-back point in the tire radial direction is varied in the tire circumferential direction to prevent the tire side bending range from being reduced when the turn-up height of the turn-up portion is increased, and the cord The stress concentrated on the folded end can be dispersed. As a result, while improving the durability of the tire, it is possible to increase the longitudinal rigidity and the lateral rigidity of the tire and effectively improve the tire performance. Here, the height of the first turning point is defined as the height H in the tire radial direction from the point B on the outer side in the tire width direction of the upper end of the bead 3a to the first turning point P1, as shown in FIG.

The pneumatic tire manufacturing method according to the present invention includes a step of manufacturing a carcass ply having a predetermined cord arrangement by periodically turning back a cord supply position while continuously moving the cord supply position. In the manufacturing method, the step of supplying the cord, the step of attaching the cord to the attachment surface while reciprocating the supply position of the cord along the width direction of the carcass ply, and the attachment surface of the carcass ply A step of moving along the longitudinal direction; and a step of controlling the amount of movement of the affixing surface with respect to the amount of movement of the supply position, and the step of adhering the cord includes at least one side in the carcass ply width direction, A plurality of first folding points arranged in a region arranged in the longitudinal direction of the carcass ply near the end of the carcass ply; The cord is sequentially folded and pasted at a number of second folding points arranged along the longitudinal direction of the carcass ply in the vicinity of the turning portion, and the number of ends of the ply winding-up portion outside the carcass ply width direction (in the cord width direction) The number of cords per 2.54 cm (1 inch)) is made larger than the number of ends on the inner side in the carcass ply width direction .

According to the method for manufacturing a pneumatic tire of the present invention, regions having different numbers of ends can be formed in the carcass ply, so that a carcass layer having regions having different numbers of ends can be suitably molded. Thereby, for example, a carcass layer in which the number of ends of the winding portion is larger than the number of ends of the main body portion can be manufactured. As a result, a pneumatic tire that exhibits the above effects, that is, it exhibits excellent exercise performance by improving the longitudinal rigidity and lateral rigidity of the tire while suppressing an increase in weight, and excellent pneumatic performance in terms of riding comfort and manufacturing cost. Tires can be provided. Moreover, according to said method, the arrangement | positioning angle of a cord can be changed in the middle of the carcass ply width direction, and a desired bending angle can be easily realized.

According to the method for manufacturing a pneumatic tire described above, since the cord is sequentially folded and pasted at the first folding point and the second folding point, the number of ends of the carcass ply is changed by changing the cycle of the folding. The ply winding-up portion can be increased outside the inner side of the carcass ply width direction. The inner side of the carcass ply of the carcass ply in the width direction of the carcass ply becomes the main body after the carcass layer is formed, and the outer side of the carcass ply in the width direction becomes the winding portion. Therefore, a carcass layer in which the number of ends of the rewinding portion is larger than the number of ends of the main body portion can be suitably manufactured, and a pneumatic tire having the above effects can be provided.

  In the above, it is preferable that the step of attaching the cord is such that the position of the first folding point in the carcass ply width direction is different in the carcass ply longitudinal direction at least on one side in the carcass ply width direction.

According to the method for manufacturing a pneumatic tire described above, since the position of the first turning point in the carcass ply width direction is different in the carcass ply longitudinal direction, the tire at the first turning point when the carcass layer is molded. The height in the radial direction can be varied in the tire circumferential direction. As a result, when the rewinding height of the rewinding portion is increased, it is possible to suppress a reduction in the bending range of the tire side and to distribute the stress concentrated on the folded end portion of the cord. As a result, a pneumatic tire having excellent durability performance and exercise performance can be provided.

  In the above, it is preferable that in the step of pasting the cord, an unvulcanized rubber sheet is formed on the pasting surface, and the cord is pasted on the unvulcanized rubber sheet.

In the method for manufacturing a pneumatic tire , a cord blank region may be formed on the carcass ply due to the difference in the number of ends between the main body portion and the rewinding portion of the carcass layer. Therefore, an unvulcanized rubber sheet is formed on the affixing surface, and a cord is attached to the unvulcanized rubber sheet, so that rubber is replenished from the rubber sheet to the blank area during vulcanization. Therefore, the carcass ply can be preferably manufactured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a half sectional view showing an example of a pneumatic tire according to the present invention. As shown in FIG. 1, the pneumatic tire of the present invention is arranged so as to be bridged between a pair of annular bead portions 3 and a pair of bead portions 3, and the end portion is wound back to the outer side of the tire. A carcass layer 6. This structure is the same as a general tire, and the present invention can be applied to any tire having the structure. The pneumatic tire includes a sidewall portion 2 that extends outward from the bead portion 3 in the radial direction of the tire, and a tread portion 1 provided between the sidewall portions 2. The bead portion 3 is a convergent body of bead wires. A bead 3a and a bead filler 3b are disposed. On the outer side of the carcass layer 6 in the tire radial direction, a belt layer 5 that reinforces by the effect of warping is disposed.

  The carcass layer 6 is formed by winding the end portion of the carcass ply 8 around the tire so as to sandwich the bead 3a at the ply rewinding portion TU, and the main body portion 6a spanned between the pair of bead portions 3, and the tire outer side. It can be divided into the rewinding portion 6b that has been rewinded. Rubber layers are formed on both sides of the carcass layer 6, and an inner liner layer is formed as the innermost layer in a tubeless tire. The carcass ply 8 forming the carcass layer 6 is constituted by a ply cord 10 (corresponding to the cord) wound around the tire equator line C at a predetermined angle. As the ply cord 10, organic fibers such as steel, polyester, rayon, nylon, and aramid are used. These materials are usually subjected to surface treatment, adhesion treatment or the like in order to improve adhesion to rubber.

  FIG. 2 is a view showing an example of the vicinity of the ply rewinding portion TU of the pneumatic tire according to the present invention. The carcass layer is represented only by the ply cord 10, and the beads 3a and the bead fillers 3b are indicated by dotted lines. The ply cord 10 forms a main body portion 6a across the tire equator line from the other side in the tire axial direction (not shown), and is folded back to the tire outer side so as to sandwich the bead 3a (not shown in FIG. 2) at the ply rewinding portion TU. Thus, the winding part 6b is configured. The folded ply cord 10 has a large number of first turn-back points P1 arranged in the tire circumferential direction A near the end of the turn-up portion 6b and a large number of first turn-up points P1 arranged in the tire circumferential direction A near the ply turn-up portion TU. After being sequentially folded at two folding points P2, it extends toward the other side in the tire axial direction.

  3 is a schematic perspective view of the bead portion 3 and the ply cord 10 shown in FIG. As shown in FIG. 3, by repeating the arrangement of the ply cords 10 shown in FIG. 2 along the tire circumferential direction A, the end number Et of the rewinding part 6b may be made larger than the end number Eb of the main body part 6a. In the example of FIG. 3, the end number ratio Et / Eb is 2.0. Thereby, the front-rear rigidity and the lateral rigidity of the tire can be increased, and the motion performance of the tire can be improved. Moreover, since the increase in the number of ends of the main body 6a can be prevented, an increase in tire weight and an increase in the longitudinal spring constant of the tire can be suppressed, and good riding comfort can be ensured. As shown in FIG. 3, the pneumatic tire according to the present invention does not necessarily have a radial tire structure, and may have a bias tire structure or a structure in which the ply cord 10 is partially inclined.

  In the present invention, the end number ratio Et / Eb of the carcass layer is not particularly limited, but is preferably 1.0 <Et / Eb ≦ 3.0, more preferably Et / Eb = 2.0. It is a neighborhood. An end number ratio Et / Eb of 1.0 or less is not preferable because it only has the same kinematic performance as that of a conventional tire, or the longitudinal spring constant of the tire increases and the riding comfort deteriorates. Further, when the end number ratio Et / Eb exceeds 3.0, the rigidity of the main body portion 6a is lowered and tire performance such as durability cannot be exhibited, or an increase in tire weight due to the rewinding portion 6b is preferable. Absent. The end number ratio Et / Eb can be arbitrarily adjusted by setting the first folding point P1 and the second folding point P2. In detail, it demonstrates in the manufacturing method of the carcass ply mentioned later.

  FIG. 4 is a schematic view of the bead portion 3 and the ply cord 10 in a perspective view, and is a view showing a different form from the example shown in FIG. The pneumatic tire according to the present invention only needs to be arranged in a region where the first turn-back point P1 is arranged in the tire circumferential direction near the end of the turn-up portion 6b, and as shown in FIG. The height of P1 may be varied in the tire circumferential direction A. In FIG. 4, the rewinding height of the rewinding portion 6 b is set higher than that of the example of FIG. 3, that is, the maximum height of the first refolding point P <b> 1 is higher than that of FIG. The tires are alternately varied in the tire circumferential direction A. Thereby, the front-rear rigidity and the lateral rigidity of the tire are improved by increasing the rewinding height of the rewinding part 6b, so that the motion performance of the tire can be enhanced. Next, by alternately changing the height of the first turn-back point P1 in the tire circumferential direction A, it is possible to prevent the tire side bending range from being reduced due to the increased turn-up height and to turn the ply cord 10 back. The stress concentrated on the end portion can be dispersed, and the durability performance of the tire can be improved.

  FIG. 4 shows an example in which the heights of the first turning points P1 are alternately different in the tire circumferential direction, but the present invention is not limited to this. For example, the height of the first turning point P1 may be varied for each of the plurality of first turning points P1, or may be gradually changed in the tire circumferential direction A. The difference ΔH between the maximum value and the minimum value of the height of the first folding point P1 is preferably as large as possible within the range of the height at which the winding part 6b is wound, but is preferably at least 5 mm or more. When ΔH is 5 mm or more, the effects of preventing the reduction of the bending range of the tire side and the dispersion of stress concentrated on the folded end portion of the ply cord 10 can be suitably achieved.

  The carcass layer 6 of the pneumatic tire according to the present invention is preferably composed of one carcass ply 8. Thereby, an increase in tire weight and an increase in the longitudinal spring constant can be avoided. Further, even if the carcass layer 6 is composed of one carcass ply 8, the front and rear rigidity and the lateral rigidity of the tire can be sufficiently improved by the ply cord 10 having the arrangement illustrated in FIGS. 3 and 4. can do.

  The carcass ply 8 constituting the carcass layer 6 only needs to be formed of a ply cord 10 as illustrated in FIGS. 3 and 4 on at least one side in the tire axial direction. Further, the end number ratio Et / Eb, the height of the first turn-back point P1, and the mode of change thereof may be different on one side and the other side in the tire axial direction. Thereby, also in the pneumatic tire which has what is called an asymmetric structure, the said effect which this invention has can be provided suitably.

  The carcass ply 8 constituting the carcass layer 6 is preferably substantially composed of one ply cord. Thereby, the carcass ply 8 can be suitably manufactured using the manufacturing method of the carcass ply mentioned later. Specifically, it will be described in the following carcass ply manufacturing method.

  FIG. 5 is a view showing an example of an apparatus for manufacturing the carcass ply 8 constituting the carcass layer 6. This manufacturing apparatus 9 is disclosed in Japanese Patent Laid-Open No. 2002-144446, and detailed description of the apparatus itself is omitted. The carcass ply manufacturing apparatus 9 includes an extruder 12, a roller group 13, a buffer roller 14, a guide roller 15, a head driving mechanism 16, a rotary drum 21 to which the ply cord 10 is attached, and a control device 20. I have. Further, the control device 20 includes a drum driving unit 20a that controls the rotation of the rotary drum 21, and a head driving unit 20b that controls the driving of the supply head 19, and the head driving mechanism 16 has a carcass ply width direction X (hereinafter simply referred to as “carcass ply width direction X”). A supply head 19 capable of reciprocating along the width direction X) and a head guide portion 18 are provided.

  According to the manufacturing apparatus 9, the cord material 10a drawn from the bobbin 11 is supplied to the extruder 12, and the ply cord 10 covered with the unvulcanized rubber composition is manufactured. Here, the unvulcanized rubber composition is prepared by kneading a rubber raw material and its compounding material by a conventional method so as to enable heat crosslinking. For example, a rubber material, a vulcanizing agent (sulfur), The components excluding the vulcanization accelerator can be kneaded with a Banbury mixer to prepare a master batch, and after cooling, the vulcanizing agent and the vulcanization accelerator can be mixed using a kneading roll.

  The ply cord 10 is sent to the buffer roller 14 by the roller group 13 and is in a relaxed state for adjusting the processing speed, and is supplied onto the outer peripheral surface 17 (corresponding to the pasting surface) of the rotary drum 21 by the supply head 19. Supplied. The outer peripheral surface 17 of the rotating drum 21 is formed of a material to which the ply cord 10 such as rubber or aluminum can be attached. The supply head 19 and the rotary drum 21 are driven based on a command from the control device 20 to control the amount of rotation of the rotary drum 21 relative to the amount of movement of the supply head 19 (the amount of movement of the outer peripheral surface 17 of the rotary drum 21). it can. Thereby, the turn-back cycle of the ply cord 10 can be changed while continuously moving the supply position of the ply cord 10, and the carcass ply 8 as shown below can be manufactured.

6-8 is a top view which shows an example of the carcass ply 8 affixed on the rotating drum 21. FIG. A position where the bead 3a is disposed at the time of forming the carcass layer is indicated by a dotted line. As shown in FIG. 6, in the pneumatic tire manufacturing method according to the present invention, when the ply cord 10 is attached to the outer peripheral surface 17 of the rotary drum 21, the carcass ply longitudinal direction Y (hereinafter referred to as “carcass ply 8”) is provided. , Simply referred to as the longitudinal direction Y.) The ply cord 10 is sequentially formed by a large number of first folding points P1 arranged along the longitudinal direction Y and a plurality of second folding points P2 arranged in the longitudinal direction Y in the vicinity of the ply winding part TU. Folded and pasted, the ply winding portion TU is formed such that the number of ends Et outside the width direction X, that is, the region 6b ′, is larger than the number of ends Eb inside the width direction X, that is, the region 6a ′. When the carcass layer 6 is molded using the carcass ply 8, the region 6b ′ forms the winding portion 6b of the carcass layer 6, and the region 6a ′ forms the main body portion 6a of the carcass layer 6. It becomes what was shown in 3.

Further, in the carcass ply 8 shown in FIG. 7A, the ply cord 10 is reciprocated three times at the first folding point P1 and the second folding point P2, and the end number ratio Et / Eb becomes 3.0. A carcass layer can be molded. As described above, according to the method for manufacturing a pneumatic tire according to the present invention, the end number ratio Et / Eb of the carcass ply 8 is arbitrarily set by setting the first turning point P1 and the second turning point P2. Can do. As a result, a pneumatic tire that exhibits the above-described effects can be suitably manufactured.

The pneumatic tire manufacturing method according to the present invention may be any method as long as the first turn-back point P1 is arranged in a region arranged in the longitudinal direction Y in the vicinity of the end of the carcass ply 8, and FIGS. ), The position in the width direction X of the first folding point P1 may be different in the longitudinal direction Y, respectively. The positions of the first turning points P1 in the width direction X are set in two ways in FIG. 7B and in three ways in FIG. 7C, and they are alternately arranged in the longitudinal direction Y. The ply cord 10 is sequentially folded at the first folding point P1 and the second folding point P2, and the end number ratio Et / Eb is 2.0. FIG. 7D shows a combination of the arrangement of the ply cord 10 shown in FIG. 7B and a conventional arrangement, and the end number ratio Et / Eb is 1.5. As described above, according to the method for manufacturing a pneumatic tire according to the present invention, the position of the first turning point P1 in the width direction X can be arbitrarily set, which is the first turning point P1 in the carcass layer 6. It means that the height can be arbitrarily set in the tire circumferential direction. As a result, when the rewinding height of the rewinding portion 6b of the carcass layer 6 is increased, the bending range on the tire side can be prevented from being reduced, and the stress concentrated on the folded end portion of the ply cord 10 can be dispersed. The durability performance of the tire can be improved.

According to the method for manufacturing a pneumatic tire according to the present invention, any method may be used as long as it has the above-described arrangement of the ply cords 10 on at least one side in the width direction X. For example, one side in the width direction X may be the above-exemplified arrangement, and the other side may be a conventionally known arrangement as shown in FIG. Moreover, it has the arrangement | sequence illustrated above on both sides of the width direction X, Comprising: You may have a different arrangement | sequence on the one side and the other side of the width direction X, respectively. By these, even in the pneumatic tire having a so-called asymmetric structure, the above-described operational effects exhibited by the present invention can be appropriately provided.

  The carcass ply 8 is preferably substantially composed of a single ply cord 10, and as shown in FIG. 5, the supply position of the single ply cord 10 is periodically folded while continuously moving relative to each other. Thus, it is preferable to manufacture the carcass ply 8 having a predetermined coding sequence. Thereby, control of the supply head 19 which supplies the ply cord 10 becomes easy, and the carcass ply 8 can be manufactured suitably. As shown in FIG. 8A, in the case where the ply cords 10 are discontinuous, a single ply cord 10 that is pasted back and forth in the width direction X is attached near the end of the carcass ply 8. The carcass ply 8 can be substantially manufactured from one ply cord 10 by cutting and re-pasting.

In the method for manufacturing a pneumatic tire according to the present invention, an unvulcanized rubber sheet is formed on the outer peripheral surface 17 of the rotary drum 21 and the ply cord 10 is attached thereon. As shown in FIGS. 7A and 7B, according to the present invention, the blank region 7 of the ply cord 10 is formed in the carcass ply 8 due to the difference in the number of ends between the rewinding portion 6b and the main body portion 6a. There is a case. Therefore, an unvulcanized rubber sheet made of an unvulcanized rubber composition is formed on the outer peripheral surface 17 of the rotary drum 21, and the ply cord 10 is attached to the unvulcanized rubber sheet. In addition, since the rubber can be replenished from the unvulcanized rubber sheet to the blank region 7, the carcass ply 8 can be suitably manufactured. The unvulcanized rubber composition is as described above.

[Other Embodiments]
(1) In the above-described embodiment, the example in which the second turning point P2 is disposed on the inner peripheral side of the bead 3a has been shown. However, the pneumatic tire or the method for manufacturing the pneumatic tire according to the present invention is not limited thereto. It is not something that can be done. In the present invention, it is only necessary that the second folding point P2 is disposed in the vicinity of the ply winding portion TU. For example, the second folding point P2 may be disposed in the region 6a ′ or the region 6b ′ in FIG.

(2) In the above-described embodiment, an example in which the rotating drum 21 is used as the pasting body has been shown. However, the method for manufacturing a pneumatic tire according to the present invention is not limited to this. For example, a flat tray or a conveyor that is long in the longitudinal direction Y may be used as the pasting body. Moreover, the manufacturing apparatus for implementing the manufacturing method of the pneumatic tire which concerns on this invention is not limited to what was shown in FIG.

(3) In the above-mentioned embodiment, although the example which affixes the ply cord 10 along the width direction X was shown in FIGS. 5-8, the manufacturing method of the pneumatic tire which concerns on this invention is the supply head 19's. The arrangement angle of the ply cord 10 may be changed in the middle of the width direction X by controlling the rotation amount of the rotary drum 21 with respect to the movement amount.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. The test tire used for the evaluation of the following items is a radial tire having a tire size of 205 / 65R15 94H, and a carcass layer made of a polyester 1670 dtex / 2 ply cord and a belt layer made of 1 + 2 × 0.27 steel cord. It was supposed to be prepared. The belt layer was laminated in two layers so that the cord was inclined by 22 ° with respect to the tread center line. The test vehicle was a domestic car (4-door sedan car, 2000cc) equipped with the test tire. Each evaluation item was measured as follows.

(1) Motor performance Two people got on the test vehicle and performed sensory evaluation on motor performance such as maneuverability on a dry road surface. The maximum score is 10 points. The higher the point, the better the exercise performance.

(2) Tire weight The weight of the test tire was measured and index evaluation was performed with the tire weight of Conventional Example 1 being 100. The higher the value, the greater the tire weight.

(3) Durability Performance The durability performance test of the test tire was performed by the method specified in JIS D 4230. In the case where cracks or the like were not confirmed even after completion of the test stage 3, the speed and load were continuously applied to the tire, and the test time until the malfunction was confirmed was measured. The index is evaluated with Conventional Example 1 being 100, and the higher the value, the longer the test time, that is, the better the durability performance.

(4) Riding comfort performance Two people got on the test vehicle, and sensory evaluation was performed on a good road and a bad road. The maximum score is 10 points, and the higher the point, the better the riding comfort.

Conventional Example 1
The above items were evaluated using a test tire having a carcass layer having a carcass ply consisting of one layer of carcass plies and having a first turn-up point height of 50 mm. The number of ends is the same number (end number ratio is 1.0) in the main body portion and the rewinding portion, and the ply cord arrangement is as shown in FIG.

Conventional example 2
It was the same as Conventional Example 1 except that two carcass plies in Conventional Example 1 were laminated to form a carcass layer.

Example 1
The above items were evaluated using a test tire having a carcass layer in which the end number ratio was 2.0 by changing the number of ends of the main body and the turn-up portion, and the height of the first turn-back point was 50 mm. Note that the height of the first turning point is constant in the tire circumferential direction (carcass ply longitudinal direction) as in the carcass ply shown in FIG.

Example 2
The height of the first turning point is the same as that of the conventional example 1 except that the height is changed from 50 to 20 to 60 mm and repeated in the tire circumferential direction as in the carcass ply shown in FIG. .

Example 3
In the carcass layer of the test tire, the end number ratio on the outer side of the vehicle body when mounted on an actual vehicle is set to 2.0, and the height of the first turn-back point is as shown in the carcass ply shown in FIG. In addition, it was configured to repeat in the tire circumferential direction by changing from 20 to 60 mm. On the other hand, the end number ratio on the inner side of the vehicle body was 1.0, and the height of the ply cord was fixed to 50 mm in the tire circumferential direction as in the carcass ply shown in FIG.

  Table 1 shows the evaluation results of the above items in the conventional example and the example.

表１に示すように、従来例２ではカーカスプライの枚数を増やすことでタイヤの前後剛性および横剛性が向上し、従来例１に比べて高い運動性能と耐久性能が得られている。しかし、タイヤ重量の増加を引き起こすとともに、タイヤの縦バネ定数の上昇により乗心地性が悪化している。それに対して実施例１は、巻き返し部のエンド数を増加することで、従来例１よりも優れた運動性能を発揮しつつ、本体部のエンド数を増加させないことで、タイヤ重量の増加を防止するとともに優れた乗心地性能を発揮している。

As shown in Table 1, in Conventional Example 2, the front and rear rigidity and lateral rigidity of the tire are improved by increasing the number of carcass plies, and higher kinematic performance and durability performance are obtained compared to Conventional Example 1. However, while increasing the tire weight, the ride comfort is deteriorated due to an increase in the longitudinal spring constant of the tire. On the other hand, Example 1 prevents the increase in tire weight by increasing the number of ends of the rewinding part, while demonstrating the exercise performance superior to that of Conventional Example 1 and not increasing the number of ends of the main body part. In addition, it exhibits excellent riding comfort.

  In Example 2, excellent exercise performance and riding comfort performance are obtained in the same manner as in Example 1, but the height of the first folding point is 60 mm, which is 10 mm higher than that of Conventional Example 1 and the like. The rewinding height of the tire is high, and further excellent exercise performance is obtained by effectively increasing the longitudinal rigidity and lateral rigidity of the tire. Furthermore, since the height of the first turning point is not constant at 60 mm and is different in the tire circumferential direction, the stress concentrated on the turning end portion of the ply cord is dispersed and excellent durability performance is obtained. In Example 3, the end number ratio and the height of the first turn-back point are appropriately set only on one side of the carcass layer, and the effects according to the present invention are favorably achieved in a so-called asymmetric structure pneumatic tire.

Half sectional view showing an example of a pneumatic tire according to the present invention The figure which showed the ply rewind part vicinity of the pneumatic tire which concerns on this invention The schematic diagram which looked at the bead part and ply cord of the pneumatic tire which concerns on this invention The schematic diagram which looked at the bead part and ply cord of the pneumatic tire which concerns on this invention The figure which shows the structure of a carcass ply manufacturing apparatus The top view of the carcass ply manufactured by the manufacturing method concerning the present invention The top view of the carcass ply manufactured by the manufacturing method concerning the present invention Plan view of carcass ply manufactured by a conventional manufacturing method The figure explaining the height of a ply rewind part and a 1st folding | turning point

Explanation of symbols

3 bead portion 3a bead 3b bead filler 6 carcass layer 8 carcass ply 6a main body portion 6b rewinding portion 10 ply cord 17 outer peripheral surface of rotating drum 19 supply head 21 rotating drum A tire circumferential direction P1 first turning point P2 second turning point TU Ply rewind part

Claims (5)

A pneumatic tire comprising a pair of annular bead portions, a main body portion of a carcass layer spanned between the pair of bead portions, and a rewinding portion of the carcass layer folded back to the tire outer side through the bead portion. Because
At least one side in the tire axial direction of the carcass layer has a plurality of first turning points arranged in a region arranged in the tire circumferential direction near the end of the winding-up portion and a plurality of pieces arranged in the tire circumferential direction near the ply winding-up portion. And the number of ends of the winding portion (the number of cords per 2.54 cm (1 inch) in the cord width direction) is based on the number of ends of the main body portion. Pneumatic tires characterized by a large number.   2. The pneumatic tire according to claim 1, wherein at least one side of the carcass layer in the tire axial direction has different heights in the tire radial direction of the first turning points in the tire circumferential direction. A pneumatic tire manufacturing method including a step of manufacturing a carcass ply having a predetermined code arrangement by periodically turning back a cord supply position continuously relative to each other,
A step of supplying the cord; a step of attaching the cord to the attaching surface while reciprocating the supply position of the cord along the carcass ply width direction; and the attaching surface along the longitudinal direction of the carcass ply. And a step of controlling the amount of movement of the pasting surface with respect to the amount of movement of the supply position,
The step of affixing the cord includes a plurality of first folding points arranged in a region arranged in the longitudinal direction of the carcass ply near the end portion of the carcass ply and at the vicinity of the ply winding portion at least on one side in the carcass ply width direction. The cord is sequentially folded and pasted at a number of second folding points arranged along the longitudinal direction of the carcass ply, and the number of ends of the ply winding-up portion outside the width of the carcass ply (2.54 cm (1 in the cord width direction)) A method for manufacturing a pneumatic tire, characterized in that the number of cords per inch) is greater than the number of ends on the inner side in the carcass ply width direction . The method for manufacturing a pneumatic tire according to claim 3 , wherein the step of attaching the cord is such that at least one side in the carcass ply width direction has different positions in the carcass ply width direction of the first folding point in the carcass ply longitudinal direction. . The method for manufacturing a pneumatic tire according to claim 3 or 4 , wherein, in the step of attaching the cord, an unvulcanized rubber sheet is formed on the attachment surface, and the cord is attached to the unvulcanized rubber sheet.

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