JP5588257B2 - Pneumatic tire manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a pneumatic tire with improved tire uniformity, particularly RFV and couple balance, by improving the winding position of a belt-like ply constituting a band layer.

  FIG. 8 shows a development view of the internal structure of the tread portion of the pneumatic radial tire. The radial tire includes a carcass a, a belt layer b including two belt plies b1 and b2 disposed on the outer side thereof, and a band layer d disposed on the outer side of the belt layer b. Such a band layer d suppresses lifting or the like of the belt layer b and improves high-speed durability and steering stability.

  Further, as shown in FIG. 8, as the band layer d, a long belt-like ply p is formed at a small angle with respect to the tire circumferential direction from the tire equator C to one side and the other side in the tire axial direction. A jointless ply j formed by being spirally wound has been proposed. Such a jointless ply j is excellent in production efficiency because the left and right jointless plies j1 and j2 can be formed simultaneously.

  However, the start ends m1 and m2 of the conventional jointless plies j1 and j2 are provided on the tire equator C and at substantially the same position in the tire circumferential direction. For this reason, the wound jointless plies j1 and j2 are provided with a substantially triangular gap e where the belt-like ply p is not formed outside the belt layer b. Such a gap e reduces the restraining force on the belt layer b. In particular, in the portion e1 where the length of the gap portion e in the tire axial direction is large, local protrusion is likely to occur during high-speed running, and there is a problem that uniformity, particularly RFV (radial force variation) and couple balance deteriorate. Related technologies include the following.

Japanese Patent Laid-Open No. 08-142226

The present invention has been devised in view of the above-described problems, and the first and second start ends of the belt-like ply forming the jointless ply are wound while being displaced in a predetermined angular range in the tire circumferential direction. Based on this, the main object is to provide a method for manufacturing a pneumatic tire capable of improving the uniformity of the tire by dispersing the gaps in the tire circumferential direction.

The present invention includes a carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, the carcass in the tire radial direction outside and inside the tread portion, and at an angle of 15 to 35 ° with respect to the tire equator. A belt layer comprising a belt ply having an inclined cord and a band layer disposed on the outer side in the tire radial direction of the belt layer , wherein the band layer is a topping rubber having a plurality of band cords arranged in parallel. A jointless ply formed by spirally winding a long belt-like ply covered with the outer periphery of the belt layer at an angle of 5 ° or less with respect to the tire circumferential direction. The jointless ply includes a tire equator. A first belt wound outwardly in the tire axial direction from the upper first starting end to the outer end in the tire axial direction of one of the belt layers; The lie and the first starting end are displaced in the same direction as the first ply from the second starting end on the tire equator shifted by an angle of 150 to 210 ° with respect to the tire circumferential direction and the other end of the belt layer. A method for producing a pneumatic tire comprising a second ply wound outward in the tire axial direction to an outer end in the tire axial direction , comprising the carcass and the belt layer, and the carcass and the belt layer A tire base molding step of molding a plurality of tire bases having substantially the same couple balance by making the relative positions of the seams of the same, and at least the band layer outside the belt layer of the tire base And the position of the first start end of the jointless ply is tied from a reference position determined at an arbitrary position in the tire circumferential direction of the tire base. A raw cover molding step for molding a plurality of types of raw covers that differ in the circumferential direction, a vulcanization molding step for obtaining a plurality of types of vulcanized tires by vulcanizing and molding each of the plurality of types of raw covers, and the plurality of types Measure the couple balance of each of the vulcanized tires, form a raw cover according to a couple balance measurement process for identifying a good tire with the smallest couple unbalance, and a position of the first starting end of the good tire, and vulcanize And a main forming step.

According to a second aspect of the present invention, the winding end of the first ply is substantially at the same position in the tire circumferential direction as the first start end, and the winding end of the second ply is the first end. 2. The method for manufacturing a pneumatic tire according to claim 1, wherein the pneumatic tire is located at substantially the same position in the tire circumferential direction as the starting end of 2.

The invention according to claim 3 is the air according to claim 1 or 2 , wherein the couple balance measurement step measures a couple balance generated by a tire member excluding the jointless ply and a couple balance by the jointless ply. It is a manufacturing method of a entering tire.

In the method for producing a pneumatic tire according to the present invention, a long belt-like ply in which a band layer is formed by covering a plurality of band cords arranged in parallel with a topping rubber is formed on the outer side of the belt layer by 5 ° with respect to the tire circumferential direction. It includes a jointless ply formed by wrapping spirally at the following angles. The jointless ply includes a first ply that is wound outward in the tire axial direction from a first starting end on the tire equator to an outer end in one tire axial direction of the belt layer, and the first starting end is a tire. The outer side in the tire axial direction from the second starting end on the tire equator shifted at an angle of 150 to 210 ° to the circumferential direction, in the same direction as the first ply and to the outer end in the other tire axial direction of the belt layer by the air-filled tires that are configured, and a carcass and a belt layer, and the relative position of each joint of the carcass and the belt layer and the same and a second ply which is wound around the substantially identical A tire base molding process for molding a plurality of tire bases having a couple balance, and forming at least a band layer outside the belt layer of the tire base, A raw cover molding process for molding a plurality of types of raw covers in which the position of the first start end of the jointless ply is changed in the tire circumferential direction from a reference position determined at an arbitrary position in the circumferential direction, and a plurality of types of raw covers Vulcanization molding process to obtain multiple types of vulcanized tires, and couple balance measurement to measure the couple balance of multiple types of vulcanized tires and identify the best tire with the smallest couple unbalance It is manufactured by a manufacturing method including a process and a main molding process in which a green cover is molded and vulcanized according to the position of the first starting end of the good tire. The first and second starting ends located on the tire equator are displaced at an angle of 150 to 210 ° with respect to the tire circumferential direction, thereby forming a substantially triangular shape formed between the first ply and the second ply. the gap portion is dispersed in the tire circumferential direction, and Ru can small a tire axial direction length of each. Further, the raw cover is formed according to the position of the first starting end of the good tire having the smallest couple unbalance. For this reason, the uniformity of the tire is improved, and particularly, the RFV and the couple balance are significantly improved.

It is sectional drawing which shows the pneumatic tire of one Embodiment of this invention. It is a perspective view which shows one Embodiment of a strip | belt-shaped ply. It is an expansion | deployment top view of the band layer of this embodiment. (A) is a figure explaining static imbalance, (b) is a figure explaining dynamic imbalance. It is a figure explaining the manufacturing process of this invention. (A) is a table in which a couple balance vector is calculated from a couple balance and tire circumferential direction angle other than the JLB factor, and (b) is a graph in which the couple balance vector obtained in (a) is plotted on XY coordinates. . (A) is a table in which a couple balance vector is calculated from the couple balance of the JLB factor and the tire circumferential direction adjustment angle, and (b) is a graph in which the couple balance vector obtained in (a) is plotted on XY coordinates. . It is an internal top view of the tread part explaining the conventional band layer.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pneumatic tire 1 of the present embodiment includes a carcass 6 that extends from a tread portion 2 through a sidewall portion 3 to a bead core 5 of the bead portion 4, and the carcass 6 on the outer side in the tire radial direction. The belt layer 7 disposed inside the tread portion 2 and the band layer 8 disposed on the outer side in the tire radial direction of the belt layer 7 are shown in the present embodiment for passenger cars.

  The carcass 6 includes a main body portion 6a straddling a pair of bead cores 5 and 5 in a toroidal manner, and a folded portion 6b which is continuous from both sides of the main body portion 6a and is folded from the inner side to the outer side in the tire axial direction around the bead core 5. And at least one carcass ply 6A (in the present embodiment). In the carcass ply 6A, carcass cords made of, for example, organic fibers are arranged at an angle of, for example, 80 to 90 ° with respect to the tire equator C direction.

  In the present embodiment, the belt layer 7 is composed of two inner and outer belt plies 7A and 7B, and the inner belt ply 7A is formed wider than the outer belt ply 7B. Each of the belt plies 7A and 7B has a highly elastic belt cord such as a steel cord inclined at an angle of 15 to 35 ° with respect to the tire equator C. The belt plies 7A and 7B are overlapped so that the belt cords intersect each other. As a result, the belt layer 7 tightens the carcass 6 over substantially the entire width of the tread portion 2 to increase the rigidity of the tread portion 2.

  As shown in FIG. 2, the band layer 8 is formed by winding a long band-like ply 11 in a spiral shape at an angle α of 5 ° or less with respect to the outer side of the belt layer 7 and the tire circumferential direction. It is composed of one layer of jointless ply 12.

  The belt-like ply 11 is a long ribbon-like long body having a substantially rectangular cross section in which a plurality of band cords 9 arranged in parallel at substantially equal intervals are covered with a topping rubber 10. The band cord 9 is not particularly limited, but an organic fiber cord such as nylon, rayon, aromatic polyamide or PEN is preferably used. Further, a steel cord may be adopted as necessary.

  Further, the width W1 of the belt-like ply 11 is desirably 5 to 20 mm, for example. When the width W1 is less than 5 mm, when the jointless ply 12 is formed, the number of windings of the belt-like ply 11 is increased and the productivity tends to deteriorate. Conversely, when it exceeds 20 mm, the winding workability tends to deteriorate. There is. The number of band cords 9 included in one belt-like ply 13 is preferably 2 or more and 10 or less, and the arrangement density is desirably 8 to 12 / cm.

  Moreover, in order to form the jointless ply 12, the belt-like ply 11 can be wound by various methods. For example, in the embodiment of FIG. 3, the side edges F of the belt-like plies 11 adjacent in the tire axial direction are wound so as to overlap each other. Thus, the band layer 8 forms a cord layer over the entire width of the belt layer 7 and serves to improve the uniformity of the tire by exhibiting a substantially uniform restraining force.

  A plan development view of the band layer 8 is shown in FIG. The vertical axis in FIG. 3 indicates the angle in the tire circumferential direction, and the horizontal axis indicates the tire axial direction (the width direction of the belt layer 7). The jointless ply 12 of the embodiment of FIG. 3 includes a first ply 12A that forms the left side of the tire equator C and a second ply 12B that also forms the right side of the tire equator C in the drawing.

  The first ply 12A is continuously wound outward in the tire axial direction from the first starting end S1 on the tire equator C to the outer end G1 of the belt layer 7 in one tire axial direction. In addition, the second ply 12B is connected to the first ply 12A from the second start end S2 on the tire equator C that is displaced from the first start end S1 by an angle θ of 150 to 210 ° with respect to the tire circumferential direction. The belt layer 7 is continuously wound outward in the tire axial direction to the outer end G2 in the other tire axial direction of the belt layer 7. The “first starting end S1 on the tire equator C” and the “second starting end S2 on the tire equator C” mean that the first starting end S1 and the second starting end S2 intersect the tire equator C. However, in consideration of manufacturing variations and the like, there may be a deviation within 3% of the width in the tire axial direction of the inner belt ply 7A.

  In the jointless ply 12 of the present embodiment, since the first start end S1 and the second start end S2 are greatly displaced at the angle θ with respect to the tire circumferential direction, the first ply 12A and the second ply 12B In between, a substantially triangular gap 14 in which the belt layer 7 is exposed is formed dispersed in the tire circumferential direction. The maximum length L1 of the gap portion 14 in the tire axial direction becomes smaller as the positional deviation angle θ in the tire circumferential direction between the first start end S1 and the second start end S2 approaches 180 °. From this point of view, the misalignment angle θ is preferably 160 ° or more, more preferably 175 ° or more, and preferably 200 ° or less, more preferably 185 ° or less. In the present embodiment, there is shown a structure in which two substantially triangular gaps 14 are formed in one circumference of the tire.

  In a particularly preferred aspect, the winding end E1 of the first ply 12A is provided at substantially the same position in the tire circumferential direction as the first start end S1, and the winding end E2 of the second ply 12B is: It is desirable that the second start end S1 is provided at substantially the same position in the tire circumferential direction. As a result, the tire axial length Wa of the first ply and the tire axial length Wb of the second ply are equal at any position in the tire circumferential direction, so that RFV is further improved. The “substantially” at the same position in the tire circumferential direction takes into account variations during tire manufacture. In addition to the case where the tires are completely at the same position, the circumferential deviation is within 5 mm. It may be a range.

  As described above, the jointless ply 12 of the present embodiment suppresses the formation of the gap portion 14 having the large length L1 in the tire axial direction as in the conventional case, and compares the length L1 with the conventional length. Therefore, the restraining force on the central portion of the belt layer 7 can be kept high. Thereby, in the pneumatic tire 1 of the present embodiment, the uniformity of the tire, in particular, RFV and TFV (tangential force variation) are significantly improved.

  Moreover, the performance evaluation of a tire can also be performed using static imbalance or dynamic imbalance. As shown in FIG. 4A, the tire having a large static unbalance has a poor weight balance in the tire circumferential direction, so that the uniformity is lowered. In particular, RFV is lowered, which is not preferable. In addition, as shown in FIG. 4B, a tire having a large dynamic unbalance is not preferable because it causes a “smashing” motion on the rotation axis of the tire, resulting in a decrease in ride comfort and steering stability. This dynamic unbalance can be obtained by vector synthesis of static unbalance and couple (even) unbalance. Therefore, if static imbalance and couple imbalance can be suppressed, it can be understood that dynamic imbalance can also be suppressed.

  In order to suppress the couple imbalance, a couple balance (hereinafter referred to as “a couple balance other than the JLB factor”) generated by the tire members excluding the jointless ply 12 (including at least the bead core 5, the carcass 6 and the belt layer 7). It is conceivable that the couple balance can be improved overall by canceling the joint balance by the couple balance (hereinafter sometimes referred to as “JLB factor couple balance”).

  A method for manufacturing such a pneumatic tire having a generally good couple balance is as follows. First, for example, as shown in FIG. 5A, a tire base 1 </ b> A in which a carcass 6 is wound around the outer surface of a known molding drum 15 and then a belt layer 7 is wound around the outside of the carcass 6. A tire base body forming step for forming a plurality of tires is performed. The tire base 1A is formed so that the relative positions of the seams 6t and 7t of the carcass 6 and the belt layer 7 are the same. Therefore, the tire base body 1A of the present embodiment has substantially the same couple unbalance. In the present embodiment, the carcass 6 and the belt layer 7 are provided with seams 6t and 7t at positions shifted by 180 degrees in the tire circumferential direction.

  Next, as shown in FIG. 5B, a raw cover forming step is performed in which the raw cover 16 for forming at least the band layer 8 is formed outside the belt layer 7 of the tire base 1A. The raw cover 16 includes a plurality of types in which the position of the first start end S1 of the jointless ply 12 is different in the tire circumferential direction from a reference position 17 determined at an arbitrary position in the tire circumferential direction of the tire base 1A. It is formed. Such a raw cover 16 is in a state where the “couple balance of JLB factors” is different. The reference position 17 is not particularly limited. For example, it is preferable that the seam 18 of the carcass 6 or the belt layer 7 is the reference position 17.

  Next, after the raw cover molding step, a vulcanization molding step is performed in which a plurality of types of raw covers are vulcanized to obtain a vulcanized tire.

  Next, a couple balance measurement step is performed in which the couple balance of each of the vulcanized tires is measured and a good tire having the smallest couple unbalance is specified.

  The couple balance measurement process for specifying the good tire will be specifically described. The measurement results of the couple balance and the tire circumferential angle at which the couple balance occurs are shown on the left side of FIGS. 6 (a) and 7 (a). Next, as shown in FIGS. 6A and 6A, a couple balance vector other than the JLB factor is calculated from the measurement result. Here, since the couple balance and the tire circumferential direction angle are expressed by a relationship of circular coordinates, a couple balance vector other than the JLB factor can be easily calculated (X1, Y1 and FIG. 6A). (Shown in FIG. 6B). Next, as shown in FIGS. 7 (a) (1), the angular difference between the attachment position (angle) of the first start end S1 and the reference position is offset from the tire circumferential angle at which a couple balance has occurred. A JLB factor couple balance vector is calculated from the tire circumferential direction adjustment angle and the couple balance. Since the couple balance and the tire circumferential direction adjustment angle are represented by the relationship of the circular coordinates, the couple balance vector of the JLB factor can be easily calculated (X2, Y2 in FIG. 7A and FIG. as shown in b)). In the present embodiment, four types of tire bases are provided in which the first starting end S1 of the tire base 1A is displaced by 90 degrees in the tire circumferential direction, and a total of 16 tire bases are provided for each of the four misplaced portions. An example in which the tire base body 1A is formed is shown.

  Next, the average value of the couple balance vector of the JLB factor and the average value of the couple balance vector other than the JLB factor are calculated, and the tire from the reference position of the average of both the couple balances other than the JLB factor and the JLB factor is calculated from this value. The circumferential position (angle) is obtained (FIG. 6 (a) (2) shows that the average tire circumferential position of the couple balance other than the JLB factor is 98 ° and FIG. 7 (a) (2) shows the JLB The average tire circumferential position of the factor couple balance is shown to be 143 °).

  The position where the two tire balances in the tire circumferential direction are separated by 180 degrees is represented as the position where the two couple balances can be most offset. That is, in this example, the good tire with the smallest couple unbalance can be obtained by shifting the position of 98 + 180-143 = 135 ° from the reference position to be the attachment position of the first starting end S1 of the jointless ply 12. Identified.

  In the measurement of the couple balance, the dynamic balance and the static balance are measured by a conventional balance tester (not shown). Further, if the number of types of tire bases 1A manufactured in the tire base molding process is large, the manufacturing cost increases. Conversely, if the number is small, it is difficult to specify a well-balanced raw cover with high accuracy. From such a viewpoint, the tire base body 1A desirably has about 4 to 8 types.

  Finally, a main molding step is performed in which a green cover is molded and vulcanized according to the position of the first starting end of the good tire.

  Since the pneumatic tire 1 manufactured in this way can make the gap portion 14 small, the RFV and TFV of the tire are significantly improved and the overall couple imbalance is improved.

  Further, as another winding method of the belt-like ply 11, the side edges F and F may be separated from each other, or conversely, the side edges F may be wound so as to contact each other. It is preferable that the side edges F are wound so as to overlap each other in terms of exerting a large and uniform restraining force on 7.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.

In order to confirm the effect of the present invention, a pneumatic radial tire of size 215 / 45R17 was prototyped based on the specifications in Table 1. Each tire has the common internal structure shown in FIG. 1 except for the band layer. Moreover, the winding mode of the jointless ply is shown in FIG. In the embodiment, the belt-like plies adjacent to each other in the winding direction are formed from the tire equator to the outer end of the belt layer at equal pitches in the tire circumferential direction.
The main common specifications are as follows.
<Carcass>
Number of carcass plies: 1 Carcass cord material: Polyester Carcass cord angle: 88 degrees <Belt layer>
Number of plies: 2 Belt cord: Steel Belt cord angle: +22 degrees / -22 degrees <band layer>
Number of plies: 1 Band cord material: Nylon Band cord angle α: 90 °
Band-shaped ply width: 1cm
Number of belt ply cords: 10 Band ply overlap width: 0 mm
The test method is as follows.

<FV test of tire>
About a test tire, RFV and TFV were measured on condition of the following based on the uniformity test conditions of JASO C607: 2000 using the force variation testing machine (average value of 20 test pieces). Evaluation was made with an index with Comparative Example 1 as 100. The smaller the value, the better.
Rim: 17 × 7.5J
Internal pressure: 200 kPa
Load: 4.08kN
Speed: 7km / h (low speed)
Speed: 120km / h (high speed)
The test results are shown in Table 1.

  As a result of the test, it can be confirmed that the uniformity of the example is significantly improved as compared with the comparative example.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 8 Band layer 9 Band cord 10 Topping rubber 11 Band-like ply 12 Jointless ply 12A First ply 12B Second ply G1 One tire shaft Direction outer end G2 outer end S1 in the other tire axial direction first start end S2 second start end

Claims (3)

A carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, and a cord disposed on the outer side in the tire radial direction of the carcass and inside the tread portion and inclined at an angle of 15 to 35 ° with respect to the tire equator A belt layer made of a belt ply having a band layer disposed on the outer side in the tire radial direction of the belt layer ,
The band layer is formed by winding a long band ply in which a plurality of band cords arranged in parallel with a topping rubber are spirally wound around the belt layer at an angle of 5 ° or less with respect to the tire circumferential direction. Including a jointless ply formed by
The jointless ply is a first ply that is wound outward in the tire axial direction from a first starting end on the tire equator to an outer end in one tire axial direction of the belt layer;
The first start end is in the same direction as the first ply from the second start end on the tire equator shifted by an angle of 150 to 210 ° with respect to the tire circumferential direction and the other tire axial direction of the belt layer A pneumatic tire manufacturing method comprising a second ply wound around the tire axially outside to the outer end of the tire ,
A tire base including the carcass and the belt layer, and forming a plurality of tire bases having substantially the same couple balance by making the relative positions of the seams of the carcass and the belt layer the same. Molding process;
At least the band layer is formed outside the belt layer of the tire base, and the position of the first starting end of the jointless ply is determined from a reference position determined at an arbitrary position in the tire circumferential direction of the tire base. A raw cover molding process for molding multiple types of raw covers made different in the circumferential direction;
A vulcanization molding step for obtaining a plurality of types of vulcanized tires by vulcanizing and molding each of the plurality of types of raw covers,
A couple balance measurement step of measuring a couple balance of each of the plurality of types of vulcanized tires and identifying a good tire having the smallest couple unbalance;
And a main forming step of forming a raw cover in accordance with the position of the first starting end of the good tire and vulcanizing it. The winding end of the first ply is substantially at the same position in the tire circumferential direction as the first starting end,
The method for manufacturing a pneumatic tire according to claim 1, wherein a winding end of the second ply is substantially at the same position in the tire circumferential direction as the second starting end . The method for manufacturing a pneumatic tire according to claim 1, wherein the couple balance measurement step measures a couple balance generated by a tire member excluding the jointless ply and a couple balance by the jointless ply.

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