JP2005212278A - Method for producing tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a tire excellent in uniformity by preventing the meandering of belt cords. <P>SOLUTION: The tire production method includes at least a process for molding a cylindrical belt ply 12 when a tread member is molded and a process for molding the belt ply 12 into a curved belt ply 20 curved along the peripheral surface 19 of a profile deck 15 by projecting the profile deck 15, which is positioned on the side of the inner surface of the belt ply 12 and has an approximately circular peripheral surface 19 with its cross section protruded outside in the tire radius direction, outside in the radius direction from a clearance 13 with bells 10A and 10B separated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tire manufacturing method suitable for manufacturing a tire in which a belt layer is curved with a relatively large curvature, such as a radial tire for a motorcycle.

  In general, as a raw tire manufacturing process in a radial tire, a method as described in Patent Document 1 below is known. Specifically, as shown in FIG. 7, a cylindrical tread member is formed by winding one or a plurality of belt plies b1 and b2 and a tread rubber c around a flat deck a having a cylindrical surface. d is formed. On the other hand, as shown in FIG. 8A, a cylindrical cover base g including bead cores e and e and carcass plies f locked on both sides thereof is formed, and the bead cores e and e are connected to each other in the axial direction. The cover base g is swelled in a toroid shape while approaching, and the outer peripheral surface thereof is affixed in advance to the inner peripheral surface of the tread member d waiting on the radially outer side.

  Further, as shown in FIG. 8B, at the time of the pasting, both end portions of the cylindrical tread member d are deformed inwardly in the tire radial direction in accordance with the curved shape of the main body cover g (so-called stitch down). ) Since the tread rubber c is in an unvulcanized state, it has plasticity and can be deformed relatively freely. However, belt cords b1 and b2 are arranged with belt cords extending at an angle relatively close to the tire circumferential direction. For this reason, the belt plies b1 to b2 have a problem that both ends are deformed in a wavy shape due to a so-called minus stretch in which the outer diameter is remarkably reduced, and belt cords that are originally uniformly arranged meander. . In particular, this tendency becomes remarkable in a radial tire for a motorcycle in which the belt ply is curved in an arc shape protruding outward in the tire radial direction. Further, the meandering of the belt cord deteriorates the uniformity of the tire, generates unexpected vibrations during driving, and deteriorates the steering stability.

JP 2000-67184 A

  The present invention has been devised in view of the above problems, and when forming a tread member, a belt ply is wound around a pair of bells that can be separated in the width direction from the center in the width direction. A profile deck having a substantially arc-shaped outer peripheral surface located on the inner peripheral surface side of the cylindrical belt ply and having a cross-section projecting outward in the tire radial direction from the gap where the bell is separated Both ends of the curved belt ply, including at least a step of forming the cylindrical belt ply into a curved belt ply curved along the outer peripheral surface of the profile deck by projecting radially outward. Provides a method of manufacturing a tire that can efficiently manufacture a pneumatic tire that can prevent meandering of the belt cord and suppress deterioration of uniformity. It is intended to be.

The invention according to claim 1 of the present invention includes a raw cover forming step of forming a raw cover by attaching an outer peripheral surface of a raw cover base including a carcass ply to an inner peripheral surface of an annular tread member including a belt ply. A method of manufacturing a tire including the step of forming a cylindrical belt ply by winding a belt ply on a pair of bells that can be separated in the width direction from the center in the width direction when forming the tread member; By projecting a profile deck having a substantially arc-shaped outer peripheral surface located on the inner peripheral surface side of the cylindrical belt ply and having a cross-section projecting outward in the tire radial direction from the gap spaced apart by the bell. Forming the cylindrical belt ply into a curved belt ply curved along the outer peripheral surface of the profile deck, and the bay Belt ply is a tire manufacturing method, characterized by satisfying the following formula (1).
(Ds + Dc) / 2> Db (1)
(However, Ds is the minimum inner diameter of the outer edge of the curved belt ply in the tire axial direction, Dc is the maximum inner diameter of the curved belt ply, and Db is the inner diameter of the cylindrical belt ply.)

The invention according to claim 2 is the tire manufacturing method according to claim 1, wherein the curved belt ply satisfies the following formula (2).
Ds ≧ Db (2)

The invention according to claim 3 is the tire manufacturing method according to claim 1 or 2, wherein the curved belt ply satisfies the following expression (3).
Ds <1.4 × Db (3)

  The invention according to claim 4 further includes a step of attaching a tread rubber to the outside of the curved belt ply.

  According to the present invention, when forming a tread member, a step of forming a cylindrical belt ply by winding the belt ply on a pair of bells that can be separated in the width direction from the center in the width direction, and the cylindrical belt ply. By projecting a profile deck having a substantially arc-shaped outer peripheral surface that is located on the inner peripheral surface side of the tire and has a substantially arc-shaped outer peripheral surface that protrudes outward in the radial direction of the tire, the cylindrical belt Forming a ply into a curved belt ply that is curved along the outer peripheral surface of the profile deck. Moreover, the curved belt ply is formed such that the average value of the minimum inner diameter and the maximum inner diameter of the outer edge in the tire axial direction is larger than the inner diameter of the cylindrical belt ply. As a result, it is possible to prevent both ends of the curved belt ply in the tire axial direction from becoming excessively negative stretch, and consequently, meandering of the belt cord can be prevented.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of a radial tire for a motorcycle as a pneumatic tire 1 manufactured by the manufacturing method of the present embodiment. The pneumatic tire 1 includes a tread portion 2, a pair of sidewall portions 3 extending inward in the tire radial direction from the tread end Te which is both ends thereof, and a bead portion 4 positioned at an inner end of each sidewall portion 3. Have The tread portion 2 is formed with a smooth arc-shaped cross-sectional contour shape in which the tread surface 2S which is the surface thereof is convex outward in the tire radial direction. The tread portion 2 is formed such that the tread width TW, which is the distance in the tire axial direction between the tread ends Te, Te, is the maximum tire width.

  The pneumatic tire 1 is reinforced with a carcass 6 and a belt layer 7. The carcass 6 is composed of one carcass ply 6A. In the present embodiment, the carcass ply 6A is connected to the main body 6a extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 embedded in the bead portion 4, and is folded back around the bead core 5 while continuing to the main body portion 6a. And the folded portion 6b. A bead apex 8 is disposed between the main body 6a and the folded portion 6b.

  The carcass ply 6A is constituted by a tire cord ply in which a carcass cord is inclined with respect to the tire equator C at an angle of, for example, 75 ° to 90 °, more preferably 80 to 90 °. As the carcass cord, an organic fiber cord such as nylon, polyester, or rayon is suitably employed.

  The belt layer 7 is composed of at least one belt ply 7A and 7B which are overlapped in the tire radial direction in this embodiment. As the belt plies 7A and 7B, tire cord plies arranged by tilting the belt cord with respect to the tire equator C at an angle of, for example, 15 to 30 degrees are used. As the belt cord, an organic fiber cord is suitable, but a steel cord or the like can also be adopted if necessary.

  Moreover, in this embodiment, each belt ply 7A, 7B is piled up in the direction where a belt cord mutually cross | intersects. The belt plies 7A and 7B have different widths. In this example, the belt ply 7B on the outer side in the tire radial direction has a larger width than the belt ply 7A on the inner side. The belt plies 7A and 7B are curved in a circular arc shape that protrudes outward in the tire radial direction substantially along the tread surface 2S. Specifically, in a no-load state in which the pneumatic tire 1 is assembled on a regular rim and filled with a regular internal pressure, each of the belt plies 7A and 7B has a camber ratio (the belt ply width B in the tire axial direction). The value obtained by dividing the bulging amount A of the belt ply in the tire radial direction) is set to about 0.01 to 0.50, more preferably about 0.10 to 0.50.

  Next, an embodiment of a method for manufacturing the pneumatic tire 1 having such a curved belt ply will be described. The manufacturing method of this embodiment includes a raw cover forming step of forming a raw cover. As is well known, the pneumatic tire 1 can be manufactured by vulcanizing a green cover with a tire vulcanization mold.

  The raw cover forming step is performed by pasting the outer peripheral surface of the raw cover base including the carcass ply on the inner peripheral surface of the annular tread member including the belt plies 7A and 7B as in the prior art. However, in the present embodiment, the following characteristic steps are included when the tread member is formed.

  First, as shown in FIG. 2, a process of forming the cylindrical belt ply 12 by winding the belt plies 7A and 7B around the pair of bells 10A and 10B is performed. The bells 10 </ b> A and 10 </ b> B are formed in a hollow cylindrical shape having a substantially circular outer peripheral surface 11. Further, in the present embodiment, the pair of bells 10 </ b> A and 10 </ b> B are arranged in advance with the axial centers thereof aligned via the gap 13 having the width Wa. Further, the bells 10A and 10B are provided so as to be movable toward and away from each other in the axial direction. Therefore, the width Wa of the gap 13 between the bells 10A and 10B can be increased by moving the bells 10A and 10B apart (indicated by arrows) in the axial direction.

  The belt plies 7A and 7B are all wound around the bells 10A and 10B with the center BC in the width direction aligned and the center BC substantially aligned with the width center of the gap 13. At this time, the width Wa of the gap 13 is adjusted to a small value so that the winding shape of the belt plies 7A and 7B does not become unstable, and can be zero in any situation. Each of the belt plies 7A and 7B is wound around the bells 10A and 10B and is formed in a cylindrical shape by overlapping both ends with a small length. At this time, it is preferable that the overlap portions of the belt plies 7A and 7B are set at positions opposite to each other by 180 °.

  A profile deck 15 is disposed in the space inside the bells 10A and 10B. FIG. 5 shows a schematic side view of the profile deck 15. The profile deck 15 is configured by combining first segments 16 and second segments 17 alternately arranged in the tire circumferential direction. Each of the segments 16 and 17 can be moved in and out of the tire radial direction by using a driving mechanism (not shown). The first and second segments 16 and 17 can have different amounts of movement. Thereby, the profile deck 15 can expand and contract the outer diameter between the small diameter state S1 indicated by the phantom line in FIG. 5 and the large diameter state S2 indicated by the solid line.

  As shown in FIG. 2, each of the segments 16 and 17 has a substantially arc-shaped outer peripheral surface 19 that is convex outward in the tire radial direction in the cross-sectional shape including the tire rotation axis. The cross-sectional shape of the outer peripheral surface 19 is set to be substantially equal to the camber ratio of the belt ply. The outer peripheral surface 19 is located inside the bells 10A and 10B in the initial state. Therefore, the formation of the cylindrical belt ply 12 is not hindered. In the large-diameter state S1, the profile deck 15 can substantially make the outer peripheral surfaces 19 of the segments 16 to 17 continue in the tire circumferential direction. The profile deck 15 is arranged such that its axial center is aligned with the center BC of the belt plies 7A and 7B.

  In the manufacturing method of the present embodiment, as shown in FIGS. 3A and 3B, the profile deck 15 is protruded radially outward from the gap 13 in which the bells 10A and 10B are separated, thereby forming a cylindrical belt ply. 12 is further formed into a curved belt ply 20 that is curved along the outer peripheral surface 19 of the profile deck 15.

  This step is performed while expanding the outer peripheral surface 19 of the profile deck 15 and correspondingly moving the bells 10A and 10B away from each other. Therefore, the diameter of the profile deck 15 can be smoothly expanded. Although the width Wa of the gap 13 between the initial bells 10A and 10B is set small, the outer peripheral surface 19 of the profile deck 15 protrudes beyond the bells 10A and 10B by separating the bells 10A and 10B in the axial direction. For this reason, a gap 13 is obtained. Further, the outer peripheral surface 11 of the bell moves while causing slippage with respect to the inner peripheral surfaces of the belt plies 7A to 7B. Therefore, it is also preferable to interpose a friction reducing material or the like that can reduce the frictional force in advance.

  Further, the bells 10A and 10B are not separated at a stretch, but hold the belt ply 7A until the outer peripheral surface 19 of the profile deck 15 contacts at least the belt ply 7A as shown in FIG. is required. Preferably, the bells 10A and 10B hold the both ends of the belt ply 7A or 7B as long as possible even while the diameter of the profile deck 15 continues to increase. As a result, the force for extending the belt ply along the diameter of the profile deck 15 to the outer side in the tire radial direction can be gradually applied from the center BC side of the belt plies 7A and 7B to the outer side in the width direction. Helps prevent code out-of-order.

Further, the curved belt ply 20 needs to be molded so as to satisfy the following formula (1).
(Ds + Dc) / 2> Db (1)
Here, “Ds” is the minimum inner diameter of the outer edge of the curved belt ply 20 in the tire axial direction, “Dc” is the maximum inner diameter of the curved belt ply 20, and “Db” is the inner diameter of the cylindrical belt ply 12. Note that Dc> Db.

The expression (1) means that the minimum inner diameter of the outer edge 20e in the tire axial direction of the curved belt ply 20 (here, the outer belt ply 7B is taken as an example) as shown in FIG. It means that the average value {(Ds + Dc) / 2} of Ds and the maximum inner diameter Dc is formed larger than the inner diameter Db of the cylindrical belt ply 12. As a result of various experiments by the inventors, when the shape of the curved belt ply 20 is defined as shown in the formula (1), it is possible to give an appropriate stretch to the cylindrical belt ply 12, and the tire of the curved belt ply 20 It has been found that excessive negative stretching can be prevented at both ends including the outer edge 20e in the axial direction, and consequently, the meandering of the belt cord can be prevented. Particularly preferably, it is desirable that the curved belt ply 20 satisfies the following formula (2), that is, the minimum inner diameter Ds of the outer edge of the curved belt ply 20 in the tire axial direction is equal to or larger than the inner diameter Db of the cylindrical belt ply 12. According to this, it is possible to completely prevent the outer edge 20e of the belt ply from becoming a negative stretch.
Ds ≧ Db (2)

Further, even if the minimum inner diameter Ds of the outer edge 20e in the tire axial direction of the curved belt ply 20 is too large, excessive belt cord opening occurs or it becomes difficult to expand the ply. From such a viewpoint, it is desirable that the curved belt ply 20 satisfies the following formula (3), more preferably the following formula (4).
Ds <1.4 × Db (3)
Ds <1.3 × Db (4)

As a more preferable aspect, it is desirable that the curved belt ply 20 satisfies the following formula (5). Thereby, it can prevent that an excessive stretch acts on belt ply 7A, 7B.
Dc <1.5 × Db (5)

  Although it is conceivable to form the curved belt ply by directly winding the belt ply around the outer peripheral surface 19 of the profile deck 15 whose diameter has been completely expanded in advance, in this method, the belt ply 7A, 7B is first uniform in the circumferential direction. It is difficult to give a proper stretch, and since it tends to be a negative stretch at both ends, belt cord meandering cannot be reliably prevented.

  Further, in the present embodiment, as shown in FIG. 4, a step of forming a tread member 23 by affixing a belt-like tread rubber 21 to the outside of the curved belt ply 20 is performed. Since the tread rubber 21 is unvulcanized and has plasticity, it can be easily deformed along the curved shape of the curved belt ply 20 even when it is flat when wound. Thereafter, by reducing the diameter of the profile deck 15, the annular tread member 23 having a curved cross section can be removed from the profile deck 15.

  Then, as shown in FIG. 6A, a cylindrical raw cover base 24 including a carcass ply 6A and a bead core 5 (not shown, but if necessary, at this stage, an inner liner or a sidewall is appropriately used. As shown in FIG. 2B, the raw cover base 24 is expanded in a toroidal shape while the bead cores 5 and 5 are brought close to each other in the axial direction. On the other hand, the annular tread member 23 including the curved belt ply 20 is held in advance on the outer side in the tire radial direction of the raw cover base 24 from the outside in the same manner as in the past, so that the inner surface of the tread member 23 is kept in standby. The raw cover 25 can be formed by pasting the outer peripheral surface of the raw cover base 24. In such a raw cover 25, the belt cord does not meander at both ends of the belt plies 7A and 7B. Therefore, the pneumatic tire obtained by vulcanizing the raw cover 25 exhibits excellent dimensional stability with respect to the belt ply after vulcanization, and thus can prevent deterioration of uniformity due to this. In consideration of the stretch acting on the belt ply, the initial end of the belt ply is appropriately adjusted.

  Although the embodiment of the present invention has been described above, the pneumatic tire 1 is not limited to a radial tire for a motorcycle, but a radial tire for a passenger car in which the camber ratio of the belt ply is designed to be relatively large in a finished state. Needless to say, it can also be applied. Also, the number of belt plies can be changed as appropriate.

  A radial tire for a motorcycle (Example tire) having a tire size of 190 / 55ZR17 was manufactured according to the method of the present invention, and its uniformity was measured. For comparison, a radial tire for a motorcycle (conventional tire) was manufactured using a tread member formed using the flat deck shown in FIGS. 7 to 8, and the performance was compared. The internal structure of the tire is as shown in FIG. 1, and includes one carcass ply made of nylon cord and two belt plies made of aromatic polyamide cord.

  For uniformity, 20 tires were randomly extracted from each method, and radial force variation (RFV), lateral force variation (LFV), radial runout (RRO), and shoulders on both sides of the crown. Lateral runout at the part ("L" at the end of LROT and LROB is the abbreviation of the top, meaning the LRO of the shoulder part molded on the upper die side of the upper and lower split molds, and "B" is the bottom (Meaning LRO of the shoulder portion molded on the lower mold side of the upper and lower split molds), and the average value was shown. In any case, the smaller the value, the better. The measurement conditions were based on JASO C607, and the rim size was 6.00 × 17, the internal pressure was 250 kPa, and the load was 2.26 kN. The test results are shown in Table 1.

  As a result of the test, it can be confirmed that in the example tire, the magnitude of the force for evaluating the uniformity and the value of the runout amount are significantly reduced as compared with the conventional tire. Therefore, according to the manufacturing method of the present invention, a pneumatic tire excellent in uniformity can be manufactured.

It is sectional drawing of the pneumatic tire manufactured by this invention. It is a cross-sectional schematic diagram which shows the process of shape | molding a cylindrical belt ply. (A), (B) is a cross-sectional schematic diagram which shows the process of the process of shape | molding a curved belt ply. It is a cross-sectional schematic diagram which shows the process of the process of shape | molding a tread member. FIG. 3 is a side view schematically showing a profile deck. (A), (B) is sectional drawing which shows the sticking process of the tread member and cover base | substrate according to this invention. It is sectional drawing explaining the method of shape | molding the conventional tread member. (A), (B) is sectional drawing which shows the pasting process of the conventional tread member and a cover base | substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 7A, 7B Belt ply 12 Cylindrical belt ply 20 Curved belt ply 25 Tread member 24 Raw cover base | substrate 25 Raw cover

Claims (4)

A tire manufacturing method including a raw cover forming step of forming a raw cover by attaching an outer peripheral surface of a raw cover base including a carcass ply to an inner peripheral surface of an annular tread member including a belt ply,
When forming the tread member, a step of winding a belt ply on a pair of bells that can be separated in the width direction from the center in the width direction to form a cylindrical belt ply;
By projecting a profile deck having a substantially arc-shaped outer peripheral surface located on the inner peripheral surface side of the cylindrical belt ply and having a cross-section projecting outward in the tire radial direction from the gap spaced apart by the bell. And forming the cylindrical belt ply into a curved belt ply curved along the outer peripheral surface of the profile deck,
And the manufacturing method of the tire characterized by the said curved belt ply satisfy | filling following formula (1).
(Ds + Dc) / 2> Db (1)
(However, Ds is the minimum inner diameter of the outer edge of the curved belt ply in the tire axial direction, Dc is the maximum inner diameter of the curved belt ply, and Db is the inner diameter of the cylindrical belt ply.) The tire manufacturing method according to claim 1, wherein the curved belt ply satisfies the following formula (2).
Ds ≧ Db (2) The tire manufacturing method according to claim 1, wherein the curved belt ply satisfies the following expression (3).
Ds <1.4 × Db (3)   The tire manufacturing method according to any one of claims 1 to 3, further comprising a step of attaching a tread rubber to the outside of the curved belt ply.

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