JP4914508B2 - Manufacturing method of raw tire for motorcycle - Google Patents

Description

  The present invention relates to a method for manufacturing a raw tire for a motorcycle that eliminates wrinkles at both ends of a tread rubber due to stitchdown and improves tire uniformity.

  In motorcycle tires, the tread portion is formed with a convex arc-shaped profile with a small radius of curvature due to the characteristic of turning the vehicle body in a large bank. Therefore, in order to form a tread portion of this type of tire, conventionally, as shown in FIG. 9A, a profile deck b whose outer peripheral surface is approximated to the arc shape of the tread surface is used, and the outer peripheral surface thereof is formed. A band ply c and a tread rubber d are sequentially laminated along the same to form an integral tread ring e for forming a tread portion. At this time, in the band ply c, there is no particular problem because the narrow band-like ply obtained by rubberizing the band cord is spirally wound along the outer peripheral surface of the profile deck b.

  However, in the tread rubber d, a wide belt-like rubber material d1 is wound around to form a cylindrical shape, and then the profile tread b is rotated using a known stitcher f (not shown) while the cylindrical tread is rotated. The rubber body is pressed against the profile deck b from the tire equator side toward the tread end side and is narrowed inward in the radial direction to be brought into close contact with the band ply c. Therefore, as shown in FIG. 9B, wrinkles g are generated at both ends of the tread rubber d by narrowing inward in the radial direction. This wrinkle g causes uneven rubber gauge thickness and waviness (meandering) h at the tread rubber edge, as shown in FIG. 9 (C), and can reduce the appearance quality and cause a decrease in uniformity.

  In addition, in the following Patent Document 1, a rubber material for tread rubber is not extruded from a rubber extruder into a flat plate shape, but is extruded from a rubber extruder with an arc-shaped cross-sectional shape that matches the outer peripheral surface of the profile deck, It has been proposed that this rubber material is wound around the profile deck as it is.

  However, it is difficult to carry out the above-described method because it is difficult to handle, such as transfer, storage, sticking to a profile deck, etc., of a rubber material having a circular arc section extruded from a rubber extruder.

JP 2004-074647 A

  Therefore, in the present invention, instead of narrowing the both end sides of the cylindrical tread rubber body to a small diameter, the center side of the tread rubber body formed in advance in a small diameter is expanded to form a desired profile shape. It is an object of the present invention to provide a method for manufacturing a raw tire for a motorcycle that can suppress wrinkles at both ends of the tread rubber at the time of tread ring formation and suppress deterioration in appearance quality and uniformity.

In order to solve the above-mentioned problems, the invention of claim 1 of the present application includes a carcass extending from a tread portion to a bead core of a bead portion through a sidewall portion, and a band disposed inside the tread portion and radially outward of the carcass. A method for producing a raw tire for a motorcycle, comprising: a layer, and a tread rubber that is disposed on a radially outer side of the band layer and has an outer surface forming a convex arc-shaped tread surface,
Including a tread ring forming step of forming a tread ring in which the band layer and the tread rubber are integrally joined;
The tread ring forming step includes
A tread rubber winding that forms a cylindrical tread rubber body by winding a belt-like tread rubber around the tread forming drum using a cylindrical tread forming drum made of rubber that can be expanded into a drum shape by filling with internal pressure. Step times,
A transfer ring having an inner circumferential surface that is an arc surface that approximates the tread surface is concentrically arranged on the radially outer side of the cylindrical tread rubber body, and then the tread forming drum is expanded by internal pressure filling, and the tread rubber is expanded. A tread rubber bending step for pressing the body against the inner peripheral surface of the transfer ring to bend the tread rubber body from a cylindrical shape into a convex arc shape and hold the transfer ring;
After removing the tread forming drum from the tread rubber body held by the transfer ring, a narrow belt-like ply with a band cord rubberized on the inner peripheral surface of the tread rubber body along the tire circumferential direction. And a band layer forming step of forming a band layer by being attached while being spirally wound.

  According to a second aspect of the present invention, in the band layer forming step, the transfer ring is rotated about its axis, and a belt for laminating the belt-like ply is attached to the inner peripheral surface of the tread rubber body in synchronization with the rotation. The belt-like ply is wound spirally by laterally moving along the axis in the direction of the axis.

  The present invention is formed on the tread forming drum using a rubber cylindrical tread forming drum that can be expanded into a drum shape by filling with an internal pressure, and a transfer ring having an inner circumferential surface approximated to a tread surface. The cylindrical tread rubber body is pressed against the inner peripheral surface of the transfer ring as the tread forming drum is expanded, so that the tread rubber body is deformed from a cylindrical shape into a convex arc shape (drum shape).

  In this way, the tread rubber body is deformed into a convex arc shape by expansion at the center side instead of being narrowed at both ends, so that the tread rubber body is free from wrinkles and suppresses deterioration in appearance quality and uniformity. Can do.

  The band layer is formed by spirally winding the belt-like ply on the inner peripheral surface of the tread rubber body from which the tread forming drum is removed. At this time, since the tread rubber body is held by the transfer ring, there is no deformation or misalignment, and the band layer can be formed densely and accurately on the tread rubber body. Further, after the band layer is formed, the tread rubber body can be transferred as it is to the next process as a tread ring by the transfer ring, so that the process loss can be minimized.

1 is a plan view showing an example of a raw tire production line for carrying out a method for producing a raw tire for a motorcycle according to the present invention. It is a side view which shows the principal part. It is sectional drawing which shows a tread rubber winding step with a tread formation drum. It is a front view which shows an example of a transfer apparatus. It is sectional drawing which shows a tread rubber curve step with a transfer ring. It is sectional drawing which shows a band layer formation step with a strip | belt-shaped ply sticking apparatus. It is a perspective view which shows the principal part of a strip | belt-shaped ply sticking apparatus. 1 is a plan view showing an example of a raw tire production line for carrying out a method for producing a raw tire for a motorcycle according to the present invention. It is sectional drawing which shows an example of the green tire manufactured by the manufacturing method of this invention. (A) is sectional drawing explaining the conventional tread ring formation process, (B), (C) is a partial perspective view of the tread rubber which shows the problem.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 8 is a schematic cross-sectional view of a raw tire 1 before vulcanization manufactured by the method for manufacturing a raw tire for a motorcycle according to the present invention. In FIG. 8, the raw tire 1 extends from a tread portion 2 to a sidewall. A carcass 6 extending through the part 3 to the bead core 5 of the bead part 4, a band layer 7 arranged inside the tread part 2 and radially outside the carcass 6, and arranged radially outside the band layer 7. In addition, the outer surface includes a tread rubber G forming a tread surface 2S having a convex arc shape.

  The carcass 6 is formed from at least one carcass ply 6A having a carcass cord arranged at an angle of, for example, 60 to 90 degrees with respect to the tire circumferential direction, in this example, one carcass ply 6A. As the carcass cord, for example, an organic fiber cord such as nylon, polyester, or rayon is used. The carcass ply 6A has folded portions 6b that are folded from the inner side to the outer side in the tire axial direction around the bead core 5 at both ends of the ply body portion 6a straddling the bead cores 5 and 5, and the ply body portion 6a. A bead apex rubber 8 for bead reinforcement extending in a radially outward direction from the bead core 5 is disposed between the bent portion 6b and the folded portion 6b.

  The band layer 7 is formed of at least one band ply 7A having a band cord spirally wound in the tire circumferential direction, in this example, one band ply 7A. The band ply 7A is formed by spirally winding a long and narrow band ply obtained by rubberizing a band cord. As the band ply 7A, for example, the above-mentioned organic fiber cord is preferably adopted, but for example, a high modulus organic fiber cord such as aromatic polyamide, or a metal cord such as a steel cord can also be adopted.

  If desired, a breaker ply (not shown) in which breaker cords are inclinedly arranged at an angle of, for example, 10 degrees or more with respect to the tire circumferential direction may be interposed between the carcass 6 and the band layer 7. As this breaker ply, the same ply material as the carcass ply 6A can also be used.

  A tread rubber G whose outer surface forms the tread surface 2S is laminated on the outer side in the radial direction of the band layer 7. The tread surface 2S is curved into a convex arc shape having a small curvature radius from the tire equator C to the tread end TE, and the contour shape (raw tread profile) approximates the tread profile of the tire after vulcanization molding. Formed.

  1 and 2 show an example of a raw tire production line 10 for carrying out the production method of the raw tire 1, and the production method will be described together with the raw tire production line 10.

The raw tire production line 10
(A) a shaping drum 12 for holding a cylindrical raw tire body 11 including a carcass cylinder 11A having bead cores 5 attached to both ends;
(A) a tread forming drum 13 that forms a cylindrical tread rubber body G2 by winding the belt-shaped tread rubber G1 once;
(C) a transfer device 14 that receives the tread rubber body G2 from the tread forming drum 13 and transfers it to the radially outer side of the raw tire body 11 held by the shaping drum 12 and to the position of the tire equator C;
(D) A structure including a band layer forming device 15 that forms a tread ring 9 by forming the band layer 7 on the inner peripheral surface Gs of the tread rubber body G2 held by the transfer device 14 during the transfer. Is done.

  Reference numeral 16 in the figure denotes a conventional 1st drum having a well-known structure that forms the green tire body 11, and includes a central drum 16a that can be reduced in diameter, and a turn-up bladder (shown in FIG. And a drum 16b on the side having no). In the first drum 16, a sheet-like carcass ply 6A is wound on the central drum 16a, and bead cores 5 are extrapolated on both sides thereof. The carcass ply 6A protruding from the bead core 5 is folded back by a turn-up bladder provided on the drum 16b on the side, thereby forming a carcass cylinder 11A to which the bead core 5 is attached. The carcass cylindrical body 11A is appropriately attached with tire constituent members such as an inner liner rubber and a side wall rubber to form the cylindrical raw tire main body 11.

  Reference numeral 17 is also a conventional transfer device for a raw tire body having a known structure for receiving the raw tire body 11 from the first drum 16, transferring it to the shaping drum 12 and transferring it.

  The shaping drum 12 is also a conventional 2nb drum having a well-known structure, and the bead portions of the raw tire body 11 are held by bead lock rings 12a on both sides in the tire axial direction, and the portion between the bead portions is the bead portion. It bulges in a toroid shape while bringing them closer together. As a result, the bulging portion of the raw tire body 11 is pressed against and integrated with the inner peripheral surface of the tread ring 9 that is on the radial outer side and at the position of the tire equator C, thereby forming the raw tire 1.

  In this example, the shaping drum 12 is disposed on a turntable 18 (shown in FIG. 1) that can rotate around a fulcrum j, and a first position Q1 for receiving the raw tire body 11 from the transfer device 17, The tread ring 9 can be moved in two positions, the second position Q2 where the tread ring 9 is integrated with the green tire body 11.

  Next, as shown in FIG. 3, the tread forming drum 13 includes a rubber cylindrical drum portion 20 that can be expanded into a drum shape by filling with an internal pressure, and both ends of the drum portion 20 are motor-driven. It is fixed to a side plate 22 that is rotatably held by a support shaft 21. The drum portion 20 can maintain a cylindrical shape in a non-internal pressure filling state by being relatively thick. The thickness of the drum portion 20 is preferably about 5 to 10 mm, particularly 7 to 8 mm. In the raw tire manufacturing method, this tread forming drum 13 is used, and a tread rubber winding that forms a cylindrical tread rubber body G2 by winding the belt-like tread rubber G1 once on the outer peripheral surface thereof. Step S1 is performed.

  Next, as shown in FIGS. 2 and 4, the transfer device 14 includes a traveling table 23 that can reciprocate in the X direction between the tread forming drum 13 and the shaping drum 12, and the traveling table in this example. 23, an outer annular frame 24 erected on the outer annular frame 24, an inner annular frame 25 supported concentrically by the outer annular frame 24 and rotatably about its axis, and concentrically with the inner annular frame 25. And a supported transfer ring 26. In this example, the traveling table 23 is placed on a moving table 27 that can move in the Y direction orthogonal to the X direction, and can be moved to the band forming position Q3 arranged by the band layer forming device 15. Yes.

  The transfer ring 26 includes a plurality (eight in this example) of segments 26A divided in the circumferential direction, and each segment 26A is supported so as to be movable inward and outward in the radial direction by an expansion / contraction diameter means 28 which is a cylinder, for example. The Accordingly, the transfer ring 26 has a reduced diameter state in which the segments 26A adjacent in the circumferential direction approach (or contact) each other and accommodate the tread rubber body G2, and an expansion in which the segments 26A are separated from each other and remove the tread rubber body G2. The diameter can be enlarged or reduced between the diameter states. Further, as shown in FIG. 5, a circular arc surface 26S approximate to the tread surface 2S is formed on the inner peripheral surface of the transfer ring 26.

  In the raw tire manufacturing method, this transfer device 14 is used, the transfer ring 26 is disposed concentrically on the outer side in the radial direction of the cylindrical tread rubber body G2 and at the position of the tire equator C, and has a reduced diameter. After the state, the tread forming drum 13 is expanded by filling with internal pressure. Thus, by pressing the tread rubber body G2 against the inner peripheral surface (arc surface 26S) of the transfer ring 26, the cylindrical tread rubber body G2 is curved from the cylindrical shape to the convex arc-shaped tread rubber body G2a. Then, a tread rubber bending step S2 that is expanded and held on the arc surface 26S of the transfer ring 26 is performed.

  Further, the tread forming drum 13 can be returned to a cylindrical shape by exhausting the internal pressure of the filling, whereby the tread forming drum 13 can be detached from the convex arc-shaped tread rubber body G2a held by the transfer ring 26. The transfer ring 26 from which the tread forming drum 13 has been removed moves to the band forming position Q3 while holding the tread rubber body G2a, and the band layer forming device 15 causes the inner peripheral surface Gs of the tread rubber body G2a to move. A band layer forming step S3 for forming the band layer 7 is performed.

  As shown in FIGS. 6 and 7, the band layer forming device 15 includes a support arm 30 extending into the inner cavity H of the tread rubber body G2a and a band-like ply sticking tool 31 attached to the tip thereof. The support arm 30 is supported so as to be movable back and forth in the tire axial direction toward the tread rubber body G2a.

  The belt-like ply sticking tool 31 is attached to the front end of the support arm 30 so as to be rotatable about an axis i1 perpendicular to the tire axial direction, and to the rotary frame 32. Guide roller means 33 for guiding the belt-like ply P is provided. The rotating frame 32 is driven to rotate by a motor M attached to the support arm 30, and the rotating frame 32 has an axis i1 which is the center of rotation of the rotating frame 32 in the tread rubber body G2a. It is supported at a position that is the center of the arc of the circumferential surface Gs. When the inner peripheral surface Gs is not a single circular arc, the arc center is defined as a single circular arc center determined by three positions of both end positions of the inner peripheral surface Gs and the center position.

  The guide roller means 33 is pivotally supported concentrically with the shaft center i1, receives a belt-like ply P conveyed from the outside in the tire axial direction, and feeds it outward in the radial direction, and the receiving roller 33a. The rotation axis i2 is orthogonal to each other so that the belt-like ply P from the receiving roller 33a is twisted by 90 ° to change the direction, and can be attached to the inner peripheral surface Gs along the tire circumferential direction. With In this example, a twisting roller 33c that applies the twisting to the belt-like ply P is provided between the receiving roller 33a and the attaching roller 33b.

  Therefore, in the belt-like ply sticking tool 31, the sticking roller 33b is rotated in the axial direction along the inner peripheral surface Gs of the tread rubber body G2a by rotating the rotary frame 32 around the axis i1. Can be moved laterally. Then, the lateral movement of the sticking roller 33b is performed in synchronization with the circumferential rotation of the transfer ring 26, so that the belt-like ply P is spirally wound along the tire circumferential direction while the inner circumferential surface is wound. Can be pasted on Gs. Note that the “synchronization” includes “contact winding” in which the side edge of the belt-like ply P is abutted and spirally wound by moving the same distance as the ply width PW of the belt-like ply P during one rotation of the transfer ring 26. , “Overlapping” in which the side edges of the belt-like ply P are overlapped and spirally wound by laterally moving a distance smaller than the ply width PW, and laterally moved a distance larger than the ply width PW Thus, a case of “gap winding” in which the side edges of the belt-like ply P are separated and spirally wound is included.

  Thus, in the raw tire manufacturing method of the present embodiment, the tread ring forming step S for forming the tread ring 9 includes the tread rubber winding step S1, the tread rubber bending step S2, and the band layer forming step S3. Contrary to the prior art, the tread rubber body G2a is first formed in a convex arc shape, and then the band layer 7 is formed on the inner peripheral surface of the tread rubber body G2a.

  At this time, the convex arc-shaped tread rubber body G2a is curved and deformed into a convex arc shape by expanding the center side instead of narrowing the both end sides of the tread rubber body G2 formed in a cylindrical shape in advance. Therefore, wrinkles are not generated in the tread rubber body G2a, and deterioration in appearance quality and uniformity can be suppressed.

  The band layer 7 is formed by spirally winding the belt-like ply P on the inner circumferential surface Gs of the curved tread rubber body G2a. At this time, the tread rubber body G2a is transferred to the transfer layer G2a. It is held by the ring 26. Therefore, there is no deformation or misalignment, and the band layer 7 can be formed densely and accurately in the tread rubber body G2a. Further, after the band layer is formed, the tread rubber body G2a can be transferred to the shaping drum 12 as it is by the transfer ring 26 as the tread ring 9, so that the process loss can be minimized.

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

  Based on the manufacturing method of the present invention, motorcycle tires having tire sizes of 190 / 50ZR17 and 160 / 60ZR17 were prototyped according to the specifications shown in Table 1, the uniformity of each sample tire, and the waviness at the tread rubber edge of the raw tire (meandering) ) And compared the occurrence rate of defective products.

Each tire is different only in the formation method of the tread ring, and the conventional examples A1 and B1 are raw tires as shown in FIG. 9A while narrowing both sides of the cylindrical tread ring using a stitcher. It is pasted on the main body. In the tire of the tire size (190 / 50ZR17), the carcass and the band layer have the following specifications.
-Number of carcass plies: 1 carcass cord: Nylon: 1400dtex / 2
Number of cords: 35 / 5cm
Cord angle: 90 ° (angle with respect to the circumferential direction)
・ Band layer Number of plies: 1 Band code: Steel: 3x3 / 0.17

In the tire of the tire size (160 / 60ZR17), the carcass and the band layer have the following specifications.
-Number of carcass plies: 2 Carcass cord: Nylon cord: 1400dtex / 2
Number of cords: 35 / 5cm
Cord angle: 72 ° (angle with respect to the circumferential direction)
・ Band layer Number of plies: 1 Band code: Steel cord: 3x3 / 0.17

(1) Waves at the tread rubber edge (meander):
As shown in FIG. 9C, after the tread ring was attached to the green tire body, the amplitude of the wavy h generated at the edge portion of the tread rubber was measured, and the maximum value was described. The smaller the value, the better the appearance quality.

(2) Defective product incidence:
Due to the wrinkles of the tread rubber, a recess was formed on the outer surface of the tire, and the defective product occurrence rate at which the tire became defective was measured for 200 tires produced.

(3) Uniformity Using an uniformity tester, LFV, RFV, and lateral blur were measured for 200 tires in accordance with JASO C607 (automotive tire uniformity test method), and the average value and standard The deviation (σ) was compared. In the measurement, standard rims of various sizes were used, and the internal pressure was 200 kPa.

  As shown in the table, it can be confirmed that the embodiment can improve the undulation of the edge caused by the tread rubber, the defective product occurrence rate, and the uniformity as compared with the conventional example.

DESCRIPTION OF SYMBOLS 1 Raw tire for motorcycles 2 Tread part 2S Tread surface 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Band layer 9 Tread ring 13 Tread forming drum 26 Transfer ring 26S Arc surface 33b Pasting roller G Tread rubber G1 Tread rubber G2, G2a Tread rubber body P Strip ply S Tread ring forming step S1 Tread rubber winding step S2 Tread rubber bending step S3 Band layer forming step

Claims (2)

A carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, a band layer disposed inside the tread portion and radially outward of the carcass, and an outer surface disposed radially outside the band layer Is a method for producing a raw tire for a motorcycle comprising a tread rubber having a convex arc-shaped tread surface,
Including a tread ring forming step of forming a tread ring in which the band layer and the tread rubber are integrally joined;
The tread ring forming step includes
A tread rubber winding that forms a cylindrical tread rubber body by winding a belt-like tread rubber around the tread forming drum using a cylindrical tread forming drum made of rubber that can be expanded into a drum shape by filling with internal pressure. Step times,
A transfer ring having an inner circumferential surface that is an arc surface that approximates the tread surface is concentrically arranged on the radially outer side of the cylindrical tread rubber body, and then the tread forming drum is expanded by internal pressure filling, and the tread rubber is expanded. A tread rubber bending step for pressing the body against the inner peripheral surface of the transfer ring to bend the tread rubber body from a cylindrical shape into a convex arc shape and hold the transfer ring;
After removing the tread forming drum from the tread rubber body held by the transfer ring, a narrow belt-like ply with a band cord rubberized on the inner peripheral surface of the tread rubber body is spiraled along the tire circumferential direction. A method for manufacturing a raw tire for a motorcycle, comprising: a band layer forming step of forming a band layer by being attached while being wound in a shape.   In the band layer forming step, the transfer ring is rotated about its axis, and a belt for adhering the belt-like ply is moved in the axial direction along the inner peripheral surface of the tread rubber body in synchronization with the rotation. The method for manufacturing a raw tire for a motorcycle according to claim 1, wherein the belt-like ply is wound spirally by being moved.

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