JP4589676B2 - Manufacturing method of rubber member for 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 is formed by overlapping and winding a rubber strip in a circumferential direction and spirally.

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

  On the other hand, in recent years, as illustrated in FIG. 5A, a strip wound body b close to a desired cross-sectional shape is formed as a rubber member c by winding the rubber strip a in a circumferential direction and spirally. A so-called strip wind method that directly forms on a drum or the like has been proposed (see, for example, Patent Documents 1 to 3). In the figure, the case where the rubber member c is a tread rubber is illustrated. This system eliminates the need for large rubber extruders and eliminates the need to store molded parts for rubber members as intermediate stock, making it possible to save space. It has a great merit.

Japanese Patent Laid-Open No. 2000-94542 Japanese Patent Laid-Open No. 2002-160508 Japanese Patent Laid-Open No. 2002-79590

  In the strip wind method, since it takes a long time to wind, it is desired to use a thick rubber strip a having a large cross-sectional area and reduce the number of windings in order to improve productivity. However, increasing the thickness of the rubber strip a results in an increase in the level difference k between the rubber strips a and a generated on the surface of the rubber member c, as shown in an enlarged view in FIG. The increase in the level difference k causes air to remain between the rubber member c and another adjacent rubber member c, between the vulcanization mold, and between the bladder, etc. Causes a drop. Moreover, it remains as a scratch on the surface of the tire, causing deterioration of the tire appearance. Further, the increase in the thickness also causes a problem that the formation accuracy of the rubber member and the degree of freedom of the formation shape are impaired, such as making it difficult to obtain a rubber member having a cross-sectional shape according to demand.

  Therefore, the present invention is based on the use of a non-uniform triangular triangle with the base as the strip width as the rubber strip, while increasing the cross-sectional area of the rubber strip to improve the productivity of the rubber member. Provided is a method for manufacturing a rubber member for a tire that can reduce various problems associated with thickening, that is, deterioration of uniformity and tire quality, deterioration of tire appearance, decrease in accuracy of forming a rubber member and freedom of forming shape, and the like. The purpose is that.

In order to achieve the above object, the invention of claim 1 of the present application relates to a tire rubber member that forms a rubber member for a tire on which the rubber strip is placed by winding the rubber strip in a circumferential direction and spirally. A manufacturing method comprising:
The rubber strip has a straight base whose cross-sectional shape forms a strip width, a first oblique side extending linearly from one end of the base to the opposing vertex, the other end of the base and the opposing vertex. It forms an unequal triangular shape consisting of a second hypotenuse that is connected in a straight line and shorter than the first hypotenuse, and further, the base length L0 is 15 to 40 mm, and the thickness T is 0.8 to 3.0 mm. And a length L1 along the bottom side of the first hypotenuse is greater than 0.5 times and less than or equal to 0.8 times the length L0 of the bottom side ,
The tire rubber member is composed of first and second rubber strips having the same cross-sectional shape,
The first rubber strip is wound from the winding start position on one end side of the tire rubber member to the winding end position on the other end side, and the second rubber strip is wound on the other end side of the tire rubber member. From the position to the winding end position on one end side, the first rubber strip is wound so as to be able to traverse,
At each winding start position, the first and second rubber strips are characterized in that the one ends of the bottom sides thereof are arranged outward in the axial direction .

  According to a second aspect of the present invention, the rubber strip is characterized in that each vertex including the opposite vertex of the unequal triangular shape is formed by an arc having a radius of 0.2 to 1.0 mm.

  Since the present invention is configured as described above, while increasing the cross-sectional area of the rubber strip and improving the productivity of the rubber member, various problems associated with conventional thickening, that is, deterioration of uniformity and tire quality, Deterioration of the tire appearance, reduction in the accuracy of forming the rubber member and the degree of freedom of the formed shape can be reduced.

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 that are folded around the bead core 5 on both sides of the ply main body portion 6a that extends 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.

  At least one of the tire rubber members G1 to G6 is formed by a strip wind method. That is, as exaggeratedly shown in FIG. 2, the tire rubber member G is formed as a wound body of the rubber strip 10 by sequentially winding the unvulcanized rubber strip 10 in a circumferential direction and spirally. Yes. In FIG. 2, the belt 7 and the band 9 are sequentially formed in a circumferential recess Da provided on the outer peripheral surface of the forming drum D, and the outer peripheral surface of the forming drum D and the outer peripheral surface of the band 9 are flattened. Then, the case where the rubber strip 10 is wound around the flattened outer peripheral surface to form the tread rubber G1 is illustrated.

  In the present invention, the cross-sectional area of the rubber strip 10 is increased while reducing the uniformity of the tire and the tire quality, the deterioration of the tire appearance, the formation accuracy of the tire rubber member G and the decrease in the flexibility of the formation shape, and the like. In order to improve the productivity of the tire rubber member G, as shown in FIG. 3 (A), the rubber strip 10 is formed in an unequal triangular section.

Specifically, the cross-sectional shape of the rubber strip 10 includes a straight base 11 having the strip width W and a maximum length, a first oblique side 12 extending straight from one end P1 of the base 11 to the opposite vertex P3, The other end P2 of the base 11 and the opposite vertex P3 are connected in a straight line, and form a left-right asymmetric unequal triangular shape including a second hypotenuse 13 shorter than the first hypotenuse 12. Moreover, the rubber strip 10 has a strip width W that is the length L0 of the base 11 of 15 to 40 mm, and a strip thickness T that is the height of the opposing vertex P3 from the base 11 is 0.8 to 3.0 mm. In addition, the length L1 of the first hypotenuse 12 along the base 11 is set to be greater than 0.5 times and less than 0.8 times the base length L0.

  As shown in FIG. 4, the step k between the adjacent rubber strips 10 and 10 is increased while the cross-sectional area is increased by increasing the thickness T to some extent by making the cross-section unequilateral triangle shape. Can be relaxed as compared with the conventional step k ′ (indicated by a one-dot chain line). Moreover, since the overlapping portion 10a has a sword tip shape, it can be easily deformed along the adjacent rubber strip 10. Accordingly, the rubber member G for a tire having a smooth outer surface shape can be formed while improving productivity by reducing the number of windings, thereby suppressing deterioration of tire uniformity, tire quality, deterioration of tire appearance, and the like. be able to.

  Particularly, by being “unequal sides”, the overlapping portion 10a can be sharpened, and the outer surface shape can be smoothed. Further, the tire rubber member G requires a profile with both ends of the sword shaped, but by being “unequal sides”, the top of the rubber strip 10 on the one end P1 side can be sharpened. A corresponding profile can be created easily and accurately.

  For example, when the tire rubber member G having a symmetrical profile such as the tread rubber G1 is formed, the first and second rubber strips 10A and 10B having the same cross-sectional shape are used as shown in FIG. Use. Specifically, the first rubber strip 10A is wound from the winding start position A1 on the one end Ea side of the tire rubber member G to the winding end position A2 on the other end Eb side. Further, the second rubber strip 10B is wound from the winding start position B1 on the other end Eb side of the tire rubber member G to the winding end position B2 on the one end Ea side so as to be misplaced with the first rubber strip 10A. At this time, at each winding start position A1, B1, the first and second rubber strips 10A, 10B are arranged with the one P1 end of the base 11 facing outward in the axial direction. Thereby, the rubber member G for tires of the left-right symmetrical profile which made the both ends Ea and Eb the shape of a sword can be formed. The “crossing” can be performed by making the circumferential phase of the winding start positions A1 and B1 of the first and second rubber strips 10A and 10B preferably 90 degrees or more, for example, about 180 degrees.

  Here, when the length L0 is less than 15 mm and the thickness T is less than 0.8 mm, the cross-sectional area is too small, and the productivity improvement effect of the tire rubber member G is not sufficiently exhibited. If the length L0 is larger than 40 mm and the thickness T is larger than 3.0 mm, the shape of the rubber member G for tires that can be formed is limited, and the degree of freedom of the formed shape is impaired. As a result, the formation accuracy is reduced. The ratio T / L0 between the length L0 and the thickness T is preferably 0.02 to 0.2.

  If the ratio L1 / L0 between the length L1 and the length L0 is greater than 0.8, the cross-sectional shape of the rubber strip 10 is too irregular, and the degree of freedom in forming the shape tends to be adversely affected. Also disadvantageous. Therefore, the ratio L1 / L0 is more preferably in the range of 0.6 to 0.7.

  Further, in the rubber strip 10, if the vertices P1 to P3 of the cross section are edges, the rubber strip 10 tends to be deformed and tends to be inferior in shape stability, which may reduce the formation accuracy of the tire rubber member G. Therefore, as shown in FIG. 3B, which represents the vertex P1, it is preferable that the vertices P1 to P3 are formed by arcs having a radius r of 0.2 to 1.0 mm.

  In the present invention, although not shown, various tire rubber members G other than the tread rubber G1, such as a sidewall rubber G2, an inner liner rubber G3, a clinch rubber G4, a belt cushion rubber G5, a bead apex rubber G6, etc. It can be formed by winding the rubber strip 10.

  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 on the outer surface of each sample tire and uniformity were compared and evaluated. The specifications are the same except for Table 1.

(1) Defect occurrence status;
Each of the 30 sample tires was visually inspected for conditions such as bear on the outer surface of the tread, and evaluated according to the following A, B, and C criteria.
A: Generation | occurrence | production of a bear etc. is not recognized.
B: A small defect is recognized. (Minor level that does not require modification)
C: A big defect is recognized. (Levels requiring correction)

(2) Uniformity;
Using a force variation (FV) tester, RFV (OA) was measured based on the JASO C607 standard, and the average value of 30 prototype tires was described.

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. (A) is sectional drawing which shows the cross-sectional shape of a rubber strip, (B) is a fragmentary sectional view which expands and shows the vertex. It is a fragmentary sectional view explaining one of the effects of this invention. (A), (B) is a diagram explaining the problem of a prior art.

Explanation of symbols

10, 10A, 10B Rubber strip 11 Base 12 First hypotenuse 13 Second hypotenuse A1, B1 Winding start position A2, B2 Winding end position G Tire rubber member P1 One end P2 Other end P3 Opposite vertex W Strip width

Claims (2)

A method for producing a tire rubber member for forming a rubber member for a tire in which the rubber strip is overlaid by winding the rubber strip in a circumferential and spiral manner,
The rubber strip has a straight base whose cross-sectional shape forms a strip width, a first oblique side extending linearly from one end of the base to the opposing vertex, the other end of the base and the opposing vertex. It forms an unequal triangular shape consisting of a second hypotenuse that is connected in a straight line and shorter than the first hypotenuse, and further, the base length L0 is 15 to 40 mm, and the thickness T is 0.8 to 3.0 mm. And a length L1 along the bottom side of the first hypotenuse is greater than 0.5 times and less than or equal to 0.8 times the length L0 of the bottom side ,
The tire rubber member is composed of first and second rubber strips having the same cross-sectional shape,
The first rubber strip is wound from the winding start position on one end side of the tire rubber member to the winding end position on the other end side, and the second rubber strip is wound on the other end side of the tire rubber member. From the position to the winding end position on one end side, the first rubber strip is wound so as to be able to traverse,
The tire rubber member manufacturing method according to claim 1, wherein at each winding start position, the first and second rubber strips are arranged with the one ends of the bottom sides thereof facing outward in the axial direction .   2. The rubber member for tire according to claim 1, wherein each of the vertexes including the opposing vertices of the unequal triangular shape is formed by an arc having a radius of 0.2 to 1.0 mm. Method.

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