JP6107343B2 - Manufacturing method of pneumatic bias tire - Google Patents

Description

The present invention relates to a process for the preparation of suitable pneumatic bias tire for the racing kart, more particularly to a method for producing a pneumatic bias tire capable of improving driving performance and cornering performance at the same time.

  The pneumatic bias tire has a bias structure in which a plurality of carcass layers including a plurality of carcass cords inclined with respect to the tire circumferential direction are mounted between a pair of bead portions (for example, Patent Documents 1 to 3). 3).

  When manufacturing a pneumatic bias tire, a plurality of carcass members including a plurality of carcass cords inclined with respect to the tire circumferential direction are wound around a molding drum so that the carcass cords intersect each other, and the carcass members are A cylindrical green tire is formed, and vulcanization is performed in a state where the green tire is expanded in a toroidal shape in a mold. Therefore, in the pneumatic bias tire, the inclination angle of the carcass cord with respect to the tire circumferential direction is usually gradually reduced from the sidewall portion side toward the tread portion side.

  A pneumatic bias tire having such a bias structure is preferably used, for example, as a tire for a racing cart. However, in recent years, with the improvement of the vehicle performance of the racing cart, the pneumatic bias tire attached to the tire is more suitable. A high level of performance is required.

  Here, it is necessary to increase the circumferential rigidity in order to improve the driving performance of the pneumatic bias tire, and in order to improve the cornering performance, it is necessary to ensure lateral rigidity that is not inferior to the grip force in the tire width direction. is there. In addition, it is necessary to appropriately reduce the longitudinal rigidity to ensure followability to the road surface in order to ensure both driving performance and cornering performance. However, the pneumatic bias tire has a carcass line so that the inclination angle of the carcass cord with respect to the tire circumferential direction gradually decreases from the sidewall portion side toward the tread portion side because of its manufacturing method. It is difficult to simultaneously obtain the circumferential rigidity, lateral rigidity, and vertical rigidity, and as a result, it is impossible to improve the driving performance and the cornering performance at the same time.

JP 2009-196521 A JP 2010-994 A JP 2010-996

An object of the present invention is to provide a method of manufacturing a pneumatic bias tire that can simultaneously improve driving performance and cornering performance.

In order to achieve the above object, a method of manufacturing a pneumatic bias tire according to the present invention includes a tread portion extending in the tire circumferential direction to form an annular shape, and a pair of sidewall portions disposed on both sides of the tread portion, A pair of buttress portions positioned between the tread portion and the sidewall portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portion, and a tire circumference between the pair of bead portions. The carcass cord has a structure in which a plurality of carcass layers including a plurality of carcass cords inclined with respect to a direction are mounted, and an inclination angle AB of the carcass cord in the buttress portion with respect to a tire circumferential direction is set to the carcass cord in the tread portion. And an inclination angle AC with respect to the tire circumferential direction of the carcass cord in the buttress portion. And the inclination angle AC of the carcass cord in the tire portion in the tread portion with respect to the tire circumferential direction is 15 ° ≦ AC ≦ 40 °. Is a method of manufacturing a pneumatic bias tire in the range of.

More specifically, the manufacturing method of the pneumatic bias tire of the present invention for achieving the above object is a method of manufacturing the above pneumatic radial tire, and includes a plurality of carcasses inclined with respect to the tire circumferential direction. A center gripping means for gripping the widthwise center of the sheet-like carcass member including the cord, a pair of end gripping means for gripping both widthwise ends of the carcass member, and the center of the carcass member And a pair of heating means for heating an intermediate portion between the two end portions, and the center portion and both end portions of the carcass member are gripped by the center portion gripping means and the end portion gripping means. In this state, the intermediate portion of the carcass member is heated and softened by the heating means, and the end gripping means is aligned with the central gripping means along the longitudinal direction of the carcass member. And increasing the inclination angle of the carcass cord with respect to the tire circumferential direction at the intermediate portion softened by the movement, and thus forming a green tire including a carcass member in which the inclination angle of the carcass cord is adjusted, It is characterized by vulcanizing green tires.

  In the present invention, in the pneumatic bias tire, while the inclination angle AC of the carcass cord in the tread portion with respect to the tire circumferential direction is set in a range of 15 ° ≦ AC ≦ 40 °, the buttress portion differs from the conventional carcass line. The inclination angle of the carcass cord with respect to the tire circumferential direction at the tread portion is larger than the inclination angle of the carcass cord with respect to the tire circumferential direction at the tread portion, and the inclination angle of the carcass cord with respect to the tire circumferential direction at the buttress portion is set to the tire circumference of the carcass cord at the sidewall portion. By making it larger than the inclination angle with respect to the direction, the tire can be easily deformed at the buttress portion while maintaining the lateral rigidity and circumferential rigidity of the tire, and the longitudinal rigidity of the tire can be reduced. As a result, driving performance and cornering performance can be improved at the same time.

  In the present invention, the inclination angle AC of the carcass cord in the tread portion with respect to the tire circumferential direction is in a range of 25 ° ≦ AC ≦ 35 °, and the inclination angle AB of the carcass cord in the buttress portion with respect to the tire circumferential direction is 60 ° ≦ AB ≦ 90. It is preferable that the inclination angle AS of the carcass cord in the sidewall portion with respect to the tire circumferential direction is in the range of 35 ° ≦ AS ≦ 60 °, and the relationship of AC ≦ AS <AB is satisfied. Thereby, drive performance and cornering performance can be improved effectively.

  When the carcass layer is wound around the bead core disposed in the bead portion from the inside of the tire to the outside, and the carcass layer winding end is disposed on the tread portion side of the apex of the bead filler disposed on the bead core, the carcass layer is wound up. The terminal is preferably arranged on the bead portion side of the portion where the inclination angle AB of the carcass cord in the buttress portion with respect to the tire circumferential direction is 60 ° ≦ AB ≦ 90 °. As a result, it is possible to ensure a sufficient cornering performance by sufficiently securing the lateral rigidity based on the winding structure of the carcass layer, and to prevent the tire deformation at the buttress portion from being hindered and to achieve a good driving performance. Can be secured.

  The pneumatic radial tire of the present invention is particularly suitable for a racing cart. The pneumatic bias tire for racing carts is a pneumatic bias tire that conforms to the regulations of the International Cart Committee (FIA-CIK), and is a pneumatic bias tire whose rim diameter is in the range of 5 to 6 inches. means.

  Further, according to the method of manufacturing a pneumatic bias tire of the present invention, a pair of gripping means for gripping the center portion in the width direction of the sheet-like carcass member and the both ends in the width direction of the carcass member. By using a carcass processing apparatus provided with an end gripping means and a pair of heating means for heating an intermediate portion between the center portion and both end portions of the carcass member, the tire performance is excellent as described above. The production of a pneumatic radial tire can be realized.

It is a meridian half sectional view showing a pneumatic bias tire for a racing cart according to an embodiment of the present invention. FIG. 2 is a development view illustrating an extracted main part of a carcass layer in the pneumatic bias tire of FIG. 1. It is a top view which shows the carcass processing apparatus used for manufacture of the pneumatic bias tire of this invention. It is a side view which shows the carcass processing apparatus used for manufacture of the pneumatic bias tire of this invention. The carcass processing process in the manufacturing method of the pneumatic bias tire of this invention is shown, (a) is a top view which shows the carcass member before a process, (b) is a top view which shows the carcass member after a process.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic bias tire for a racing cart according to an embodiment of the present invention, and FIG. 2 shows an extracted main portion of the carcass layer. 1 and 2 depict only one side of the tire equatorial plane CL, this pneumatic bias tire has a symmetrical structure on both sides of the tire equatorial plane CL.

  As shown in FIG. 1, the pneumatic bias tire includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, a pair of sidewall portions 3 that are disposed on both sides of the tread portion 1, and a tread portion. 1 and the sidewall portion 3, and a pair of bead portions 4 disposed inside the sidewall portion 3 in the tire radial direction. The buttress portion 2 is a portion that is adjacent to the tread portion 1 and deviated from the ground contact region, and the boundary between the buttress portion 2 and the sidewall portion 3 is an end of the cap tread rubber layer 11 disposed in the tread portion 1 in the tire width direction. It is specified by the part position. The end position in the tire width direction of the cap tread rubber layer 11 generally corresponds to the end position of the tread design.

  Between the pair of bead portions 4, 4, two carcass layers 5 are mounted. These carcass layers 5 include a plurality of carcass cords 5a (see FIG. 2) aligned so as to be inclined with respect to the tire circumferential direction C, and the carcass cords 5a are arranged so as to intersect each other between the layers. Yes. As the carcass cord 5a, for example, an organic fiber cord represented by a nylon fiber cord or a polyester fiber cord can be used. These carcass layers 5 are wound up around the bead core 6 disposed in each bead portion 4 from the tire inner side to the outer side. A bead filler 7 made of a rubber composition is disposed on the outer periphery of the bead core 6, and the bead filler 7 is sandwiched between the main body portion and the rolled-up portion of the carcass layer 5.

  In the pneumatic bias tire for a racing cart having the bias structure described above, the inclination angle AB of the carcass cord 5a in the buttress portion 2 with respect to the tire circumferential direction is larger than the inclination angle AC of the carcass cord 5a in the tread portion 1 with respect to the tire circumferential direction. In addition, the inclination angle AB of the carcass cord 5a in the buttress portion 2 with respect to the tire circumferential direction is set to be larger than the inclination angle AS of the carcass cord 5a in the sidewall portion 3 with respect to the tire circumferential direction.

  The inclination angle AC in the tread portion 1 means the inclination angle of the carcass cord 5a measured at the position of the tire equatorial plane CL with respect to the tire circumferential direction, and the inclination angle AB in the buttress portion 2 is the tire width of the cap tread rubber layer 11. It means the inclination angle of the carcass cord 5a measured at the end position in the direction with respect to the tire circumferential direction, and the inclination angle AS in the sidewall portion 3 is the inclination angle of the carcass cord 5a measured at the tire maximum width position with respect to the tire circumferential direction. These inclination angles AC, AB, and AS can be measured at each of the above-mentioned sites in a state where the carcass layer 5 is developed on the same plane.

  In the pneumatic bias tire for a racing cart, unlike the conventional carcass line, the inclination angle AB of the carcass cord 5a in the buttress portion 2 with respect to the tire circumferential direction is the inclination angle AC of the carcass cord 5a in the tread portion 1 with respect to the tire circumferential direction. The inclination angle AB of the carcass cord 5a in the buttress portion 2 with respect to the tire circumferential direction is larger than the inclination angle AS of the carcass cord 5a in the sidewall portion 3 with respect to the tire circumferential direction. The tire can be easily deformed at the buttress portion 2 while maintaining the rigidity, and the longitudinal rigidity of the tire can be reduced. As a result, driving performance and cornering performance can be improved at the same time.

  In the pneumatic bias tire described above, the inclination angle AC of the carcass cord 5a in the tread portion 1 with respect to the tire circumferential direction needs to be in a range of 15 ° ≦ AC ≦ 40 °, and more preferably, the carcass in the tread portion 1 The inclination angle AC of the cord 5a with respect to the tire circumferential direction is in a range of 25 ° ≦ AC ≦ 35 °, and the inclination angle AB of the carcass cord 5a in the buttress portion 2 with respect to the tire circumferential direction is in a range of 60 ° ≦ AB ≦ 90 °. The inclination angle AS of the carcass cord 5a in the sidewall portion 3 with respect to the tire circumferential direction is preferably in the range of 35 ° ≦ AS ≦ 60 ° and satisfies the relationship of AC ≦ AS <AB. Thereby, drive performance and cornering performance can be improved effectively.

  Here, when the inclination angle AC in the tread portion 1 is smaller than 25 °, the lateral rigidity of the tread portion 1 is insufficient with respect to the grip force in the tire width direction, so that cornering performance is deteriorated. Since the circumferential rigidity against the grip force in the circumferential direction of the tread portion 1 is insufficient, the effect of improving the driving performance is lowered. Further, if the inclination angle AB in the buttress portion 2 is smaller than 60 °, the longitudinal rigidity becomes unnecessarily high, so the effect of improving both the cornering performance and the driving performance is lowered, and conversely, it is larger than 90 °. It is difficult to process the carcass member. Further, the inclination angle AS in the sidewall portion 3 has an appropriate value for expressing rigidity. That is, when the angle is smaller than 35 °, the vertical rigidity of the sidewall portion 3 is lowered, and the change in the running posture becomes excessive, resulting in a decrease in cornering performance. On the other hand, when the angle is larger than 60 °, the lateral rigidity of the sidewall portion 3 is lowered, so that the cornering performance improving effect is lowered.

  In the pneumatic bias tire described above, the carcass layer 5 is wound around the bead core 6 disposed on the bead portion 4 from the inside of the tire to the outside, and the winding terminal 5e of the carcass layer 5 is apex of the bead filler 7 disposed on the bead core 6. When the winding terminal 5e of the carcass layer 5 is disposed closer to the tread portion 1 than the bead portion 4 than the portion where the inclination angle AB of the carcass cord 5a in the buttress portion 2 with respect to the tire circumferential direction is 60 ° ≦ AB ≦ 90 °. It should be placed on the side. As a result, the circumferential rigidity and lateral rigidity of the sidewall portion 3 can be sufficiently secured based on the winding structure of the carcass layer 5, so that excellent cornering performance can be exhibited, and adequate tire deformation in the buttress portion 2 is ensured. As a result, good driving performance can be exhibited. That is, by optimizing the winding structure of the carcass layer 5, the flexibility of the buttress portion 2 can be ensured while sufficiently ensuring cornering performance.

  In the above-described embodiment, the case of the pneumatic bias tire for a racing cart provided with two carcass layers has been described. However, the configuration of the present invention also applies to a pneumatic bias tire for a racing cart provided with three or more carcass layers. Applicable. Of course, the above configuration can also be applied to pneumatic bias tires for uses other than racing carts.

  Next, a method for manufacturing the pneumatic bias tire described above will be described. 3 and 4 show a carcass processing apparatus used for manufacturing the pneumatic bias tire of the present invention, and FIG. 5 shows a carcass processing step in the manufacturing method of the pneumatic bias tire of the present invention.

  As shown in FIGS. 3 to 5, this carcass processing apparatus is arranged such that a center portion 51 in the width direction of a sheet-like carcass member 50 is placed, and can be moved forward and backward toward the upper surface of the base 21 a. A pair of pedestals 22a and 23a on which the pressing member 21b provided and both end portions 52 and 53 in the width direction of the sheet-like carcass member 50 are respectively mounted, and can be moved forward and backward toward the upper surfaces of these pedestals 22a and 23a, respectively. And pressing members 22b and 23b disposed on the surface. The pedestal 21a and the pressing member 21b constitute the center gripping means 21, the pedestal 22a and the pressing member 22b constitute one end gripping means 22, and the pedestal 23a and the pressing member 23b constitute the other end gripping means. 23. The end gripping means 22 and 23 are configured to be movable relative to the central gripping means 21 along the longitudinal direction of the carcass member 50 that coincides with the tire circumferential direction C. In addition, a pair of heating means 24 and 25 for heating intermediate portions 54 and 55 between the central portion 51 and both end portions 52 and 53 of the carcass member 50 are mounted on the base 21a of the central portion gripping means 21. ing.

  When manufacturing the pneumatic bias tire described above, first, as shown in FIG. 5A, a sheet-like carcass member 50 including a plurality of carcass cords 5a inclined with respect to the tire circumferential direction C is prepared. The carcass member 50 constitutes the carcass layer 5 in a pneumatic radial tire. Next, the carcass member 50 is processed using a carcass processing apparatus as shown in FIGS. That is, the intermediate parts 54 and 55 of the carcass member 50 are moved by the heating means 24 and 25 while the central part 51 and both end parts 52 and 52 of the carcass member 50 are gripped by the center gripping means 21 and the end gripping means 22 and 23. Heat to soften. Then, by moving the end gripping means 22 and 23 relative to the central gripping means 21 along the longitudinal direction of the carcass member 50, the tire of the carcass cord 5a in the intermediate portions 54 and 55 in the softened state. The carcass member 50 having a shape as shown in FIG. 5B is obtained by increasing the inclination angle with respect to the circumferential direction. Here, if necessary, the intermediate portions 54 and 55 of the carcass member 50 in which the inclination angle of the carcass cord 5a is adjusted may be cooled to enhance the shape retention.

  Next, a plurality of layers of carcass members 50 in which the inclination angles of the carcass cords 5a are adjusted in this manner are wound around the forming drum so that the carcass cords 5a intersect each other, and a cylindrical green including these carcass members 50 is formed. A tire is molded and vulcanized in a state where the green tire is expanded in a toroidal shape in a mold.

  According to the method for manufacturing a pneumatic bias tire described above, the inclination angle AC of the carcass cord 5a in the tread portion 1 with respect to the tire circumferential direction, the inclination angle AB of the carcass cord 5a in the buttress portion 2 with respect to the tire circumferential direction, and the sidewall portion 3 The inclination angle AS of the carcass cord 5a with respect to the tire circumferential direction can be set to a desired range. As a result, the production of a pneumatic radial tire having excellent tire performance as described above can be realized.

  Racing having a tire size of 7.1 × 11.0-5 and having a bias structure in which two carcass layers including a plurality of carcass cords inclined with respect to the tire circumferential direction are mounted between a pair of bead portions. In the pneumatic bias tire for carts, the inclination angle AC of the carcass cord in the tread portion with respect to the tire circumferential direction, the inclination angle AB of the carcass cord in the buttress portion with respect to the tire circumferential direction, and the inclination angle AS of the carcass cord with respect to the tire circumferential direction in the sidewall portion. Were set as shown in Table 1, and tires of conventional examples, comparative examples 1 and 2 and examples 1 to 7 were manufactured.

  About these test tires, the driving performance and cornering performance were evaluated by the following evaluation methods, and the results are also shown in Table 1.

Drive performance:
Each test tire was assembled on a wheel of rim size 210-5, mounted on a KF-2 vehicle with an air pressure of 80 kPa, and a sensory evaluation was performed by a test driver on the driving performance when traveling on a racing cart dedicated circuit. . The evaluation results are shown as an index with the conventional example being 100. A larger index value means better driving performance.

Cornering performance:
Each test tire was assembled to a wheel of rim size 210-5, mounted on a KF-2 vehicle with an air pressure of 80 kPa, and the cornering performance when traveling on a racing cart-dedicated circuit was evaluated by a test driver. . The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the cornering performance.

  As can be seen from Table 1, in the tires of Examples 1 to 5, both driving performance and cornering performance were improved in comparison with the conventional example. On the other hand, the tire of Comparative Example 1 had a reduced cornering performance because the inclination angle AS of the carcass cord in the sidewall portion was increased similarly to the inclination angle AB of the carcass cord in the buttress portion. Further, the tire of Comparative Example 2 had a low driving performance because the inclination angle AC of the carcass cord in the tread portion was too large.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Buttress part 3 Side wall part 4 Bead part 5 Carcass layer 5a Carcass cord 6 Bead core 7 Bead filler 11 Cap tread rubber layer

Claims (4)

A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of buttress portions positioned between the tread portion and the sidewall portions; A plurality of carcass layers including a plurality of carcass cords that are inclined with respect to the tire circumferential direction between the pair of bead portions. has mounted structure, larger than the inclination angle AC inclination angle AB with respect to the tire circumferential direction of the carcass cord with respect to the tire circumferential direction of the carcass cord in the tread portion in the buttress portion, the carcass in the buttress portion The inclination angle AB of the cord with respect to the tire circumferential direction is defined by the direction of the carcass cord in the sidewall portion. It is larger than the inclination angle AS respect ya circumferential direction, and the inclination angle AC with respect to the tire circumferential direction of the carcass cord in the tread portion was a way of producing a pneumatic bias tire in the range of 15 ° ≦ AC ≦ 40 ° And
A center portion gripping means for gripping the center portion in the width direction of the sheet-like carcass member including a plurality of carcass cords inclined with respect to the tire circumferential direction, and a pair of gripping portions in the width direction of the carcass member. Using a carcass processing apparatus comprising an end gripping means and a pair of heating means for heating an intermediate portion between the center portion and both end portions of the carcass member, the center gripping means and the end gripping means In the state where the central portion and both end portions of the carcass member are gripped, the intermediate portion of the carcass member is heated and softened by the heating means, and the end gripping means is moved along the longitudinal direction of the carcass member. Increasing the angle of inclination of the carcass cord with respect to the tire circumferential direction at the intermediate portion softened by moving it relative to the gripping means, and thus the carcass cord Molding a green tire comprising a carcass member angle of inclination is adjusted, pneumatic bias tire manufacturing method, which comprises vulcanizing the green tire. In the pneumatic bias tire, an inclination angle AC of the carcass cord with respect to the tire circumferential direction in the tread portion is in a range of 25 ° ≦ AC ≦ 35 °, and an inclination angle AB of the carcass cord with respect to the tire circumferential direction in the buttress portion Is in the range of 60 ° ≦ AB ≦ 90 °, the inclination angle AS of the carcass cord with respect to the tire circumferential direction in the sidewall portion is in the range of 35 ° ≦ AS ≦ 60 °, and the relationship of AC ≦ AS <AB The pneumatic bias tire manufacturing method according to claim 1, wherein: In the pneumatic bias tire, the carcass layer is wound up around the bead core disposed in the bead portion from the tire inner side to the outer side, and the winding end of the carcass layer is treaded from the apex of the bead filler disposed on the bead core. The carcass layer winding terminal is disposed closer to the bead portion than the portion where the inclination angle AB of the carcass cord in the buttress portion with respect to the tire circumferential direction is 60 ° ≦ AB ≦ 90 °. The manufacturing method of the pneumatic bias tire of Claim 1 or 2. The method for manufacturing a pneumatic bias tire according to any one of claims 1 to 3, wherein the pneumatic bias tire is used for a racing cart.

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