JP4295759B2 - Manufacturing method of rubber member for tire and pneumatic tire - Google Patents

Description

  The present invention relates to a method for manufacturing a rubber member for a tire, in which a rubber member for a tire such as a tread rubber or a sidewall rubber is formed by winding a rubber strip in a spiral shape, and air vulcanized using the method. Related to tires.

  Since the required characteristics of each part are different in the pneumatic tire, the pneumatic tire is composed of various rubber members having different compositions and cross-sectional shapes such as tread rubber, sidewall rubber, clinch rubber, belt cushion rubber, and inner liner rubber. Conventionally, a wide molded body having a desired cross-sectional shape extruded by a rubber extruder or the like is used for each rubber member, and this molded body is wound once on a molding drum or the like in a raw tire molding process. Each rubber member is formed.

  In contrast, in recent years, as illustrated in FIG. 11A, a rubber strip a is wound around the surface of a cylindrical wound body d such as a forming drum along with the rotation of the wound body d. A so-called strip wind method is proposed in which a strip wound body b close to a desired cross-sectional shape is directly formed on a wound body d as a rubber member c by being displaced in the axial direction of the body and spirally wound. (For example, refer to Patent Documents 1 to 3). In the figure, the case where the rubber member c is a tread rubber is illustrated. This method eliminates the need to store the molded product for rubber members as an intermediate stock, which can improve tire manufacturing efficiency and save space. It has merit.

JP 2000-94542 A JP 2002-160508 A JP 2002-79590 A

  However, when the rubber member c is formed by the strip wind method, as shown in an enlarged view in FIG. 11B, between the wound rubber strips a and a, between the rubber strip a and the wound body d, and the like. Since the gap e is formed in the gap e, air remaining easily occurs in the gap e after the vulcanization molding, and there is a concern that the tire quality may be deteriorated such as uniformity.

  Therefore, the present invention is based on the fact that a plurality of exhaust grooves are arranged in parallel at a predetermined inclination direction and angle on both surfaces of the rubber strip, while ensuring the merit of the strip wind method, the remaining air in the gap is maintained. It aims at providing the manufacturing method of the rubber member for tires which can control generation | occurrence | production effectively and can maintain tire quality high, and a pneumatic tire.

In order to achieve the above object, the invention of claim 1 of the present application provides a rubber strip on the surface of a cylindrical wound body from one side in the axial direction of the wound body along with the rotation of the wound body. A method of manufacturing a tire rubber member for forming a tire rubber member on which the rubber strip is placed by being spirally wound while being displaced on the other side,
The rubber strip has a cross-sectional shape having a thickness T of 0.7 to 4.0 mm, a width W of 10 to 20 times the thickness T, and exhausts air between the rubber strips superimposed on both surfaces. A plurality of exhaust grooves that can be
The exhaust groove extends at an angle θ of 20 to 70 ° with respect to the length direction of the rubber strip, and inclines from the other side in the axial direction toward one side toward the rear side of the winding, and the exhaust groove The maximum groove width of 0.3 to 3.0 mm and the maximum groove depth of 0.1 to 3.0 mm ,
The exhaust groove is formed between a strip base formed by extrusion molding with a final cross-sectional shape, a molding roller having a groove-forming rib for forming an exhaust groove formed on the outer peripheral surface, and a smooth roller having a smooth outer peripheral surface. Including a groove forming step that passes through the groove. The groove forming step includes a rubber indentation deformation caused by the groove forming rib being pushed into the strip base, and a return deformation caused by a part of the indentation deformation being restored after the indentation. Thus, exhaust grooves are formed on both surfaces of the strip base at substantially the same position at the same time.

According to a second aspect of the present invention, the exhaust groove formed on the other surface of the rubber strip is formed substantially at the same position as the exhaust groove formed on the one surface.
In the invention of claim 3, the groove volume V2 of the exhaust groove formed on the other surface of the rubber strip is 50 to 90% of the groove volume V1 of the exhaust groove formed on the one surface. It is said.
According to a fourth aspect of the present invention, the exhaust grooves are arranged in parallel with a distance P of 40 to 200 mm in the length direction of the rubber strip.
In the invention of claim 5, the rubber strip includes a maximum thickness portion at the center in the width direction where the thickness is maximum, and a taper portion which is continuous with both sides and gradually decreases toward both side edges. 7. The invention according to claim 6, wherein the exhaust groove extends at a maximum groove depth in the maximum thickness portion, and the groove depth is gradually reduced toward the both side edges in the tapered portion. , the protruding height h of the groove forming ribs of the typed roller, be greater than the sum of the groove depth of the exhaust groove on both surfaces, yet in the invention of claim 7, in the invention of air-filled tire And it is characterized by carrying out the vulcanization molding using the rubber member for tires obtained by the manufacturing method in any one of Claims 1-6 .

  Since the present invention is configured as described above, it is possible to effectively suppress the generation of air remaining between rubber strips or between a rubber strip and a molding drum, etc. while ensuring the merit of the strip wind method. It becomes possible to maintain high quality.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a pneumatic tire vulcanized using a tire rubber member manufactured by the manufacturing method of the present invention.
In FIG. 1, a pneumatic tire 1 includes a cord reinforcing layer including a plurality of types of tire rubber members G having different rubber blends, a carcass 6 forming a skeleton of the tire, and a belt 7 disposed on the outer side in the radial direction. To be formed.

  The carcass 6 includes one or more carcass plies 6A in this example, in which carcass cords are arranged at an angle of, for example, 70 to 90 ° with respect to the tire circumferential direction. In this example, the carcass ply 6A includes ply folding portions 6b folded around the bead core 5 on both sides of the ply main body portion 6a extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4. In a series.

  The belt 7 includes two or more belt plies 7A and 7B in which belt cords are arranged at an angle of, for example, 10 to 35 ° with respect to the tire circumferential direction. In this example, the belt cords are alternately arranged between the plies. By intersecting, the belt rigidity is increased and the tread portion 2 is reinforced strongly. A band 9 in which band cords are arranged along the tire circumferential direction can be provided outside the belt 7 mainly for the purpose of improving high-speed running performance.

  Next, as the tire rubber member G, a tread rubber G1 disposed on the tread portion 2 and forming a ground contact surface, a sidewall rubber G2 disposed on the sidewall portion 3 and forming a tire outer surface, and the carcass 6 The inner liner rubber G3 which is disposed inside the tire and forms the inner surface of the tire, the clinch rubber G4 which is disposed in the bead portion 4 and prevents rim displacement, and the both ends of the belt 7 and the carcass 6 are disposed outside the belt. A belt cushion rubber G5 for protecting the end and a bead apex rubber G6 extending radially outward from the bead core 5 may be included.

  Then, at least one of the tire rubber members G1 to G6 is formed by a strip wind method. That is, as shown in FIG. 2, an unadded rubber strip 10 is spirally wound on the surface of a cylindrical wound body 30 while being displaced in the axial direction along with the rotation of the wound body 30. By overlapping, the rubber member G for tires is formed as a wound body of the rubber strip 10.

  In FIG. 2, the rubber strip 10 is wound around the surface of the wound body 30 including the cylindrical forming drum D and the belt 7 and the band 9 sequentially formed on the outer periphery thereof, and the tread rubber G1 is overlapped. What is formed is illustrated. In particular, in the figure, two rubber strips 10A and 10B are used, and with the rotation of the wound body 30, one rubber strip 10A is sequentially displaced from the tire equator C side to the right in the tire axial direction and spirals. Further, the case where the other rubber strip 10B is spirally wound while being displaced sequentially from the tire equator C side to the left side in the tire axial direction is illustrated. That is, in this example, one rubber strip 10A is sequentially displaced from one axial side F1 on the tire equator C side to the other side F2 on the right side in the tire axial direction, and the other rubber strip 10B is aligned with the tire equator. The position is sequentially shifted from one side F1 in the axial direction on the C side to the other side F2 on the left side in the tire axial direction.

  Next, in this strip wind method, a gap e is formed between the wound rubber strips 10 and 10 or between the rubber strip 10 and the wound body 30. Therefore, after vulcanization molding, there are concerns about problems such as air remaining and scratches occurring in the gap e, leading to deterioration of tire quality such as uniformity.

  Therefore, in the present invention, for the purpose of exhausting the air in the gap e, as shown in FIG. 3, the both surfaces Sf and Sr of the rubber strip 10 intersect with the length direction of the rubber strip 10. A plurality of exhaust grooves 11f and 11r (which may be collectively referred to as exhaust grooves 11) are provided side by side.

Here, the to the rubber strip 10, the thickness T is used 0.7～4.0Mm, and what width W of flat oblong a 10-20 times the cross-sectional shape of the thickness T. It has a rectangular cross-sectional shape . However, as shown in FIGS. 8 and 9, the taper portion having the maximum thickness portion 35 having the maximum thickness Tmax at the center in the width direction and gradually decreasing toward both side edges 10E on both sides thereof. A tapered shape on both sides tapered with 36 can be suitably employed from the viewpoint that the gap e itself can be reduced. The tapered shapes on both sides include trapezoidal shapes 10a and 10b (FIGS. 8A and 8B) in which tapered surface portions 36 of inclined surfaces are continuously provided on both sides of the maximum thickness portion 35 having a predetermined width, and the tapered portions. A substantially trapezoidal shape 10c, 10d, 10i (FIGS. 8C, 8D, and 8E) having a convex arc surface or a concave arc surface 36 as a point, and the maximum thickness portion 35 as dots, on both sides thereof And semicircular arcs 10e, 10f (FIGS. 9A, 9B) and arcs 10g, 10h (FIGS. 9C, 9D), etc., in which taper portions 36 of the arc surface are continuously provided. . In the case of such a double-sided tapered shape, the maximum thickness Tmax, that is, the maximum thickness Tmax is in the range of 0.7 to 4.0 mm. In addition, the thing of the rectangular cross-sectional shape can be regarded as the aspect in which the taper part 36 was excluded and the rubber strip 10 was formed only by the maximum thickness part 35.

  The exhaust groove 11 inclines from the other side F2 in the axial direction toward the one side F1 toward the rear side of the winding, and the angle θ of the inclination with respect to the length direction of the rubber strip 10 is 20 to 70 °. The range.

  As conceptually shown in FIG. 4, as the wound body 30 rotates, the rubber strip 10 is spirally wound while being displaced from one axial side F1 to the other side F2. The air in the gap e passes through the exhaust groove 11 and is exhausted from the side edge 10E2 on the other side F2 of the rubber strip 10 toward the side edge 10E1 on the one side F1. At this time, since the rubber strip 10 is sequentially displaced from the one side F1 to the other side F2, the side edge 10E2 of the other side F2 of the rubber strip 10 is deep inward in the radial direction in the wound body. On the other hand, the side edge 10E1 of the one side F1 is positioned on the side exposed on the outer surface of the wound body. Thus, in the present invention, an exhaust passage is formed in which the direction of exhaust is “wound body → wound body surface”, so that the rubber strip 10 is removed while exhausting air inside the wound body to the outside. Winding is possible, and the occurrence of air pockets can be effectively suppressed.

  In addition, since the exhaust groove 11 is inclined at the angle θ, the proportion of the groove area can be increased even with the same groove width, compared with the case where the exhaust groove 11 extends in the width direction (θ = 90 °). It becomes possible to increase it further. Further, since the exhaust grooves 11 are formed on both surfaces Sf and Sr of the rubber strip 10, the number of exhaust grooves 11 formed on the respective surfaces Sf and Sr can be halved while maintaining the exhaust effect. Accordingly, it is possible to reduce the chance that the exhaust groove 11 is exposed on the surface of the wound body, and it is possible to suppress deterioration in appearance quality when the trace of the exhaust groove 11 remains after vulcanization molding. Further, when a groove forming process described later is used, many merits are achieved such that the number of groove processing steps can be halved and the structure and control of the groove forming apparatus can be simplified.

  If the angle θ is less than 20 °, the length of the exhaust passage leading to the surface of the wound body is excessive, and the exhaust efficiency tends to decrease, and there is a possibility that air remains in the exhaust passage. . Conversely, if the angle θ exceeds 70 °, there is a risk of cutting due to the tension when the rubber strip 10 is wound, and the rate of increase in the groove area is reduced, so that the exhaust efficiency tends to decrease. From such a viewpoint, the lower limit value of the angle θ is more preferably 25 ° or more and the upper limit value is more preferably 65 ° or less.

  Further, since the exhaust grooves 11 are formed on both surfaces Sf and Sr of the rubber strip 10, the distance P in the length direction of the rubber strip 10 between the exhaust grooves 11 and 11 on each surface can be set long. The chance of exposure to the surface of the wound body of the groove 11 can be reduced, and deterioration in appearance quality when the trace of the exhaust groove 11 remains after vulcanization molding can be suppressed. However, if the distance P exceeds 200 mm, an air pool tends to occur. On the other hand, if it is less than 40 mm, the quality is excessive and the strength of the rubber strip 10 tends to be unnecessarily lowered. From such a viewpoint, it is more preferable that the lower limit value of the interval P is 40 mm or more and the upper limit value is 60 mm or less.

  In the exhaust groove 11, as shown in FIG. 5, the maximum width Wg1 (maximum width Wg1) of the groove width Wg is in the range of 0.3 to 3.0 mm and the maximum depth Hg1 (maximum depth Hg1). ) Is set in the range of 0.1 to 3.0 mm.

  Here, when the rubber strip 10 has a rectangular cross-sectional shape, the exhaust groove 11 extends from the side edge 10E1 to the side edge 10E2, and is formed with a constant groove width Wg and groove depth Hg. That is, the constant groove width Wg and groove depth Hg form the maximum width Wg1 and the maximum depth Hg1. When the maximum width Wg1 exceeds 3.0 mm and the maximum depth Hg1 exceeds 3.0 mm, the groove volume becomes excessive, leading to insufficient rubber flow during vulcanization molding, and the trace of the exhaust groove 11 is damaged. The problem of remaining will arise. On the contrary, if the maximum width Wg1 is less than 0.3 mm and the maximum depth Hg1 is less than 0.1 mm, the exhaust effect cannot be exhibited sufficiently.

Then, in the rubber strip 10, the advantage may employ discussed later to groove forming step to form a substantially same position as the forming position of the exhaust groove 11f and exhaust groove 11r.

  Here, in the groove forming step, as shown in FIG. 6, the strip base 20 extruded by the final cross-sectional shape, that is, the contour shape of the rubber strip 10, is formed on the outer peripheral surface of the groove forming rib 21 for forming the exhaust groove. Are provided between the rollers 22U and 22L of the groove forming device 22 including a molding roller 22U having a convex shape and a smoothing roller 22L having a smooth outer peripheral surface. This is a step of forming 11r at a time.

  Specifically, in the groove forming device 22, the gap between the molding roller 22U and the smoothing roller 22L is substantially the same as the thickness T of the rubber strip 10, that is, the thickness T of the strip base 20, and the groove The protruding height h of the molding rib 21 is set to be larger than the groove depth Hg of the one exhaust groove 11f and larger than the sum of the groove depths Hg of both the exhaust grooves 11f and 11r. Then, by passing the strip base 20 between the rollers 22U and 22L, as shown in FIG. 7A, first, the groove forming rib 21 is pushed into the strip base 20 and thereby the rubber is applied to one surface Sf. An indentation deformation K1 occurs. At this time, as shown in FIG. 7B, a stress J is generated in the rubber portion between the groove forming rib 21 and the smooth roller 22L so as to restore the indentation deformation K1. Then, when the groove forming rib 21 passes, a part of the indentation deformation K1 is recovered by the stress J and the other surface Sr and the indentation deformation K1 as shown in FIG. At the same position, a groove-like return deformation K2 occurs. As described above, by adopting the groove forming process using the groove forming apparatus 22, the exhaust grooves 11f and 11r can be simultaneously formed on both surfaces Sf and Sr of the strip base 20 and substantially at the same position. . At this time, it is preferable that the bottom surface of the exhaust groove 11 has an arc shape.

  Such a groove forming device 22 has a simple device structure and has few processing steps to the strip base 20, so that productivity can be improved. In addition, since both the exhaust grooves 11f and 11r can be formed at accurate positions, the control means is simplified if the complicated control between the rollers, which is necessary when forming the groove forming ribs on each roller, is not necessary. It is also possible to do.

  When the groove forming step is employed, the groove volume V2 of the exhaust groove 11r on the other surface Sr on the return deformation K2 side is the groove volume V1 of the exhaust groove 11f on the one surface Sf on the indentation deformation K1 side. However, the groove volume ratio V2 / V1 can be increased to a range of 50 to 90%. If the maximum width Wg1 satisfies 0.3 to 3.0 mm and the maximum depth Hg1 satisfies 0.1 to 3.0 mm in each of the exhaust grooves 11f and 11r, the groove volume ratio V2 / V1 is 50. In the range of ˜90%, exhaust performance can be sufficiently exhibited. It is technically difficult to set the ratio V2 / V1 to 90% or more by the groove forming step. Conversely, if the ratio V2 / V1 is less than 50%, the exhaust effect is adversely affected.

  When the groove forming step is adopted, if the thickness T of the rubber strip 10 is too thick, the return deformation K2 becomes insufficient, and the exhaust groove 11r having the required groove depth Hg cannot be formed. Therefore, the thickness T is preferably 4.0 mm or less as described above. On the other hand, when the thickness T is too thin, the production performance of the rubber member G for tires is lowered, for example, the number of windings is increased. Therefore, the lower limit is preferably 0.7 mm or more. In order to exert the exhaust effect, the rubber strip 10 needs to have a certain degree of rigidity. For this reason, the ratio W / T of the thickness T to the width W is preferably set in the range of 10-20.

Next, the case where the rubber strip 10 has a tapered shape on both sides as shown in FIGS. For example, as a representative example of the trapezoidal shape 10a of FIG. 8A, the rubber strip 10 is tapered on both sides of the maximum thickness portion 35 as shown in FIG. The part 36 is continuously provided. In such a case, the exhaust grooves 11f and 11r extend at the maximum depth Hg1 in the maximum thickness portion 35, respectively. Further, the exhaust grooves 11f and 11r, in the tapered portion 36, gradually decrease the groove depth Hg toward the both side edges 10E, and terminate at the inner side at a distance L0 from the side edges 10E. This is because when the exhaust groove 11 is formed up to the side edge 10E, the cutting strength is remarkably reduced, which may cause weakness and breakage. However, when the distance L0 exceeds 2.0 mm, the air cannot be exhausted from the side edge 10E, which tends to cause an air pocket.
Therefore, the distance L0 is preferably larger than 0 mm and not larger than 2.0 mm. Note that the groove forming step can also be adopted in the case of such a tapered shape on both sides.

  In the present invention, although not shown, various tire rubber members G other than the tread rubber G 1 can be formed by winding the rubber strip 10. In particular, when a tire rubber member G that forms the outer surface or inner cavity surface of the tire, such as a tread rubber G1, a sidewall rubber G2, a clinch rubber G4, and an inner liner rubber G3, is formed by wrapping the rubber strip 10, the outside of the tire The effect of reducing the remaining air between the surface and the vulcanization mold and the remaining air between the inner surface of the tire and the bladder can be exhibited, and an improvement in appearance quality can be expected.

  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.

  A pneumatic tire (tire size 215 / 45ZR17) in which a tread rubber was formed using a rubber strip having the specifications shown in Table 1 was prototyped, and the occurrence of defects caused by the remaining air in each test tire was compared and evaluated. Each exhaust groove is inclined toward the one side F1 from the other side F2 of the positional deviation toward the rear side of the winding. Specifications other than those listed in Table 1 are the same specifications.

<Defect occurrence>
(1) With respect to each of 100 sample tires, the deformation due to the air remaining inside the tread was visually inspected and evaluated by the number of tires in which the deformation was confirmed.
(2) With respect to each of 100 sample tires, the occurrence of scratches due to air remaining on the tread surface and exhaust grooves was visually inspected, and the number of tires in which scratches were confirmed was evaluated.

It is sectional drawing which shows one Example of the pneumatic tire using the rubber member for tires manufactured by the manufacturing method of this invention. It is sectional drawing in case the rubber member for tires is a tread rubber. It is the top view and sectional drawing which show a rubber strip with an exhaust groove. It is a perspective view explaining the effect of an exhaust groove. It is sectional drawing which makes the cross-sectional shape of an exhaust groove. It is a side view explaining a groove forming process. (A)-(C) are sectional drawings explaining formation of an exhaust groove by a groove formation process. (A)-(E) are sectional drawings explaining the other cross-sectional shape of a rubber strip. (A)-(D) are sectional drawings explaining other cross-sectional shape of a rubber strip. It is sectional drawing explaining an exhaust groove in case a rubber strip is a taper shape on both sides. (A), (B) is sectional drawing explaining the problem of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 10 Rubber strip 10e Side edge 11f, 11r Exhaust groove 20 Strip base body 22U Molding roller 22L Smoothing roller 24 Groove forming rib 30 Wound body 35 Maximum thickness part 36 Tapered part F1 One side F2 The other side G For tires Rubber member K1 Indentation deformation K2 Return deformation Sf, Sr Surface

Claims (7)

The rubber strip is spirally wound on the surface of the cylindrical body to be wound while being displaced from one side in the axial direction of the body to be wound together with the rotation of the body to be wound. A method for producing a rubber member for a tire for forming a rubber member for a tire on which a rubber strip is placed,
The rubber strip has a cross-sectional shape having a thickness T of 0.7 to 4.0 mm, a width W of 10 to 20 times the thickness T, and exhausts air between the rubber strips superimposed on both surfaces. A plurality of exhaust grooves that can be
The exhaust groove extends at an angle θ of 20 to 70 ° with respect to the length direction of the rubber strip, and inclines from the other side in the axial direction toward one side toward the rear side of the winding, and the exhaust groove The maximum groove width of 0.3 to 3.0 mm and the maximum groove depth of 0.1 to 3.0 mm,
The exhaust groove is formed between a strip base formed by extrusion molding with a final cross-sectional shape, a molding roller having a groove-forming rib for forming an exhaust groove formed on the outer peripheral surface, and a smooth roller having a smooth outer peripheral surface. Including a groove forming step that passes through the groove. The groove forming step includes a rubber indentation deformation caused by the groove forming rib being pushed into the strip base, and a return deformation caused by a part of the indentation deformation being restored after the indentation. The exhaust groove is formed at substantially the same position on both surfaces of the strip base at the same time .   2. The tire rubber member according to claim 1, wherein the exhaust groove formed on the other surface of the rubber strip is formed at substantially the same position as the exhaust groove formed on the one surface. Method.   3. The groove volume V2 of the exhaust groove formed on the other surface of the rubber strip is 50 to 90% of the groove volume V1 of the exhaust groove formed on the one surface. Manufacturing method for rubber member for tire.   The method for manufacturing a rubber member for a tire according to any one of claims 1 to 3, wherein the exhaust grooves are arranged in parallel in the length direction of the rubber strip at an interval P of 40 to 200 mm.   The rubber strip includes a maximum thickness portion on the center side in the width direction where the thickness is maximum, and a tapered portion which is continuous with both sides and gradually decreases toward both side edges, and the exhaust groove has the maximum thickness. 5. The tire rubber member according to claim 1, wherein the tire rubber member extends at a maximum groove depth in the portion and gradually decreases the groove depth toward the both side edges in the tapered portion. Manufacturing method. The tire rubber member according to any one of claims 1 to 5, wherein the protrusion height h of the groove forming rib of the molding roller is set to be larger than the sum of the groove depths of the exhaust grooves on both surfaces. Manufacturing method. A pneumatic tire which is vulcanized with the tire rubber member obtained by the production method according to any one of claims 1-6.

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