JP2010194878A - Manufacturing method for tire tread, tire tread, and pneumatic tire equipped with tire tread - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a tire tread, wherein possibility of generating poor molding can remarkably be reduced by adhering appropriately both ends of a belt-like material upon winding a belt-type material around a drum. <P>SOLUTION: A method for manufacturing a cyclic tire tread comprises cutting a belt-like rubber composition and adhering one end surface of the cut rubber composition to the other end surface, wherein an angle between the inner peripheral surface of the rubber composition and one end surface thereof is referred to as one cutting angle, while the angle between the outer peripheral surface of the rubber composition and other end surface thereof is referred to as the other cutting angle, and the other cutting angle is set forth approximately to a peripheral length at an intermittent position in the direction of thickness upon making the rubber composition cyclic. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire manufacturing method, and more particularly to a tire tread manufacturing method and a tire tread that can reduce tire molding defects.

  Conventionally, a product tire has a green tire formed by winding a belt-shaped member such as a tread constituting a product tire around a cylindrical tire molding drum and joining one end and the other end of the belt-shaped member on the drum. It is manufactured by vulcanizing the green tire with a vulcanizer. As described above, since a green tire is formed by winding a plurality of belt-shaped members around a drum, it is required to appropriately bond both ends of the belt-shaped member, and as a method of appropriately bonding both ends. Cut both ends of the belt-like member at a predetermined same angle, and form irregularities on one end and the other end of the belt-like member having a predetermined cutting angle, A method for appropriately joining the end portions by securing an area has been proposed.

JP 2003-103654 A

However, the above method is a method in which both end portions of the band-shaped member are cut on a plane and the cross-sections of both end portions are made to coincide with each other. Since a circumferential length difference that is shorter than the circumferential length of the side surface is generated, the operator needs to join one end of the belt-like member to the other end while correcting the circumferential length difference. The joint surface is likely to vary depending on the skill.
In addition, when the manufacturing object is a large tire, since the gauge (thickness) of the belt-like member is large, the circumferential length difference when wound around the drum becomes more prominent and abutted by pulling both ends. In the vicinity of the joint surface, the outer surface and inner surface are deformed in a wavy shape, or residual stress due to tension is generated on the outer surface, causing air to be mixed during vulcanization, etc., which causes molding defects during vulcanization, The quality of the product tire after vulcanization is reduced.

  Therefore, in order to solve the above-mentioned problem, the present invention can manufacture tire treads that can significantly reduce the possibility of forming defects by appropriately joining both ends of the belt-shaped member when the belt-shaped member is wound around the drum. A method and tire tread are provided.

In order to solve the above problems, as a first embodiment according to the present invention, an annular tire tread is manufactured by cutting a belt-shaped rubber composition and joining one end face and the other end face of the cut rubber composition. The angle between the inner peripheral surface of the rubber composition and one end surface is one cutting angle, and the angle formed between the outer peripheral surface of the rubber composition and the other end surface is the other cutting angle. The cutting angle is set to an angle obtained by approximating the length of the outer peripheral surface of the rubber composition to the peripheral length of the intermediate position in the thickness direction when the rubber composition is annular.
According to this embodiment, the other cutting angle is set in advance to an angle when the length of the outer peripheral surface of the rubber composition is approximated to the peripheral length of the intermediate position in the thickness direction when the rubber composition is annular. Therefore, when the rubber composition is annular, the circumferential length difference between the outer peripheral surface and the inner peripheral surface of the rubber composition can be reduced, and the one end surface and the other end surface of the rubber composition are appropriately joined. Therefore, it is possible to obtain a tire tread that hardly causes molding defects.

In addition, as a second embodiment according to the present invention, one cutting angle is set to be larger than the other cutting angle.
According to this embodiment, since the length of the outer peripheral surface of the rubber composition is longer than the length of the inner peripheral surface, the difference in the peripheral length when the rubber composition is formed into an annular shape can be further reduced. Since the one end surface and the other end surface of the object can be appropriately joined, a tire tread in which molding defects do not occur can be obtained.

Further, as a third embodiment according to the present invention, the other cutting angle is set to 15 ° to 35 °.
According to this embodiment, the other cutting angle can be any angle from 15 ° to 35 °, so that the joining area with the one end at the other end can be appropriately determined, and a molding defect does not occur. A tread can be obtained.

Further, as a first configuration according to the present invention, an annular tire tread formed by joining one end surface and the other end surface of a cut strip-shaped rubber composition, the inner peripheral surface and one end surface of the rubber composition And the other cutting angle formed by the outer peripheral surface and the other end surface of the rubber composition is larger.
According to this configuration, since the peripheral length of the outer peripheral surface of the rubber composition is large and the peripheral length of the inner peripheral surface is small, it is possible to further reduce the peripheral length difference when the rubber composition is annular. The one end surface and the other end surface of the object can be appropriately joined.

Further, as a second configuration according to the present invention, the other cutting angle is in a range of 15 ° to 35 °.
According to this configuration, since the cutting angle of the other end is in the range of 15 ° to 35 °, the bonding area with the one end at the other end can be appropriately determined.
Moreover, it was set as the pneumatic tire provided with the said tire tread as 3rd structure which concerns on this invention. According to the pneumatic tire having this configuration, when the joining surface of the tire tread included in the pneumatic tire is appropriately joined, the generation of separation with the joining surface of the tire tread generated during vehicle traveling as a base point, etc. Defects can be effectively prevented.
In the present specification, “one end surface” and “the other end surface” are, for example, any one of both cut surfaces (splice surfaces) when a rubber composition continuously extruded from an extruder is cut by a cutting means. In the present specification, “one” and “the other” are words used for clarifying and simplifying the explanation, and either “one” or “the other” is used. It is arbitrary.
The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

It is a schematic diagram of a tire molding drum. It is a comparison figure which compares a prior art example and the Example based on this invention. It is a schematic diagram which shows the state which shape | molds a some rubber composition.

  Hereinafter, the present invention will be described in detail through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included in the invention. It is not necessarily essential to the solution, but includes a configuration that is selectively adopted.

FIG. 1 is a schematic view of a tire molding drum 1 for winding a rubber composition that is cut at both ends and molded as a band-shaped member. In the figure, a tire molding drum 1 includes a cylindrical drum body 2.
A plurality of strip-shaped members constituting the green tire 3 before vulcanization are attached to the drum body 2. The green tire 3 is roughly wrapped around a case 4 in which a plurality of belt-like members such as an inner liner, a carcass, and a belt that are wound along the peripheral surface of the drum body 2 are laminated, and along the peripheral surface of the case 4. And a rubber composition 5 having a predetermined gauge (thickness). The rubber composition 5 is a belt-like member that is long along the circumferential direction of the drum body 2, and is a side that contacts the road surface after vulcanization is completed by joining the one end face 8 and the other end face 9 together. An outer peripheral surface 6 and an inner peripheral surface 7 that is the side facing the surface of the case 4 are formed.
The rubber composition 5 is produced by blending natural rubber, synthetic rubber such as synthetic isoprene, styrene butadiene rubber, butadiene rubber, and butyl rubber with a filler such as carbon black and a vulcanization accelerator. A tread of a pneumatic tire is configured by being vulcanized by a vulcanizer.
In addition, in this example, although the example which shape | molds the green tire 3 by the drum main body 2 is disclosed, it is not limited to shaping | molding of a green tire, For example, a base tire and the tread for correction stuck on a base tire, The tire may be a modified tire. In this case, the base tire corresponds to the case 4 and the tread for correction corresponds to the rubber composition 5.

Hereinafter, the circumferential length difference of the rubber composition 5 wound around the drum body 2 will be described.
When the belt-shaped rubber composition 5 is wound on the surface of the case 4, a circumferential length difference is generated between the outer peripheral surface 6 and the inner peripheral surface 7 of the rubber composition 5. Specifically, as shown in FIG. 1, when the drum diameter of the drum body 2 is a, the gauge of the case 4 (thickness in the drum radial direction) is b, and the gauge of the rubber composition 5 is c, the rubber composition 5, the peripheral length A of the outer peripheral surface 6 = (a + 2b + 2c) π, and the peripheral length C of the inner peripheral surface 7 of the rubber composition 5 = (a + 2b) π. Therefore, the circumferential length difference between the outer peripheral surface 6 and the inner peripheral surface 7 is expressed as AC. The larger the circumferential length difference AC, the greater the force required to join the one end face 8 and the other end face 9 while pulling the outer peripheral face 6 side. Since the inner peripheral surface 7 side near the surface is compressed, tension is generated on the outer peripheral surface 6 side, and compressive force is generated on the inner peripheral surface 7 side. That is, a non-uniform stress state is generated on the joint surface between the one end surface 8 and the other end surface 9 or in the vicinity of the joint surface.
As described above, there is a correlation between the circumferential length difference that is the difference between the circumferential length of the outer circumferential surface 6 and the circumferential length of the inner circumferential surface 7 when the rubber composition 5 is annular, and the joining state of the joining surface. Therefore, the rubber composition 5 is cut so that the circumferential length difference between the outer peripheral surface 6 and the inner peripheral surface 7 becomes smaller when the rubber composition 5 is annular, and the outer peripheral surface 6 and the inner peripheral surface 7 are cut. If the length in the circumferential direction is set in advance, the bonding state of the bonding surface when the rubber composition 5 is wound can be set to an appropriate state.

Hereinafter, the setting method of the circumferential direction length of the outer peripheral surface 6 and the inner peripheral surface 7 is demonstrated concretely.
A virtual line L in FIG. 1 indicates a circumferential length (hereinafter referred to as a circumferential length L) at the intermediate position (c / 2) in the thickness direction of the rubber composition 5, and the length of the outer peripheral surface 6 and the length of the inner peripheral surface 7. If the length is approximated to the circumferential length L in advance, the circumferential length difference when the rubber composition 5 is annular can be made as close to zero as possible.
More specifically, the circumferential length of the outer peripheral surface 6 is approximated in advance to the peripheral length L when the rubber composition 5 is annular, and more than the peripheral length C of the inner peripheral surface 7 when annular. By setting the circumference A to be longer, the circumference difference between the outer circumferential surface 6 and the inner circumferential surface 7 can be reduced.

FIG. 2 shows a conventional example in which the lengths of the outer peripheral surface 6 and the inner peripheral surface 7 of the rubber composition 5 are the same, and an example in which the length of the outer peripheral surface 6 is set longer than the length of the inner peripheral surface 7. It is a figure which compares.
FIG. 2 (a) shows that the narrow angle formed by the inner peripheral surface 7 and one end surface 8 of the rubber composition 5 and the narrow angle formed by the outer peripheral surface 6 and the other end surface 9 are both 25 °. An example is shown.
In FIG. 1, for example, the drum diameter a of FIG. 1 is 889 mm, the gauge b of the case 4 is 25.4 mm, the gauge c of the rubber composition 5 is 50.8 mm, and the rubber composition 5 is wound around the drum body 2. In this case, the peripheral length A of the outer peripheral surface 6 of the rubber composition 5 = (889+ (2 × 25.4) + (2 × 50.8)) π = 3271.7 mm, and the inner periphery of the rubber composition 5 Since the circumferential length C of the surface 7 = (889+ (2 × 25.4)) π = 2952.5, the circumferential length difference (A−C) is 319.2 mm.

FIG. 2B shows an embodiment in which the narrow angle formed by the inner peripheral surface 7 and the one end surface 8 of the rubber composition 5 is 45 °, and the narrow angle formed by the outer peripheral surface 6 and the other end surface 9 is 35 °. Show. In this example, hereinafter, an angle formed by the inner peripheral surface 7 of the rubber composition 5 and one end surface 8 forming an acute angle with the inner peripheral surface 7 is defined as one cutting angle, and the outer peripheral surface 6 of the rubber composition 5 is used. And the angle which consists of the said outer peripheral surface 6 and the other end surface 9 which makes an acute angle is made into the other cutting angle.
In the figure, the rubber composition 5 is configured such that the length of the outer peripheral surface 6 is set to be longer by YX than the length of the inner peripheral surface 7 by setting one cutting angle to be larger than the other cutting angle. When the rubber composition 5 is annular, the peripheral length relaxation amount (Y-X) is (1 / tan35 ° -1 / tan45 °) × 50.8 = 21.7 mm. Therefore, the circumferential length difference generated between the outer circumferential surface 6 and the inner circumferential surface 7 can be improved to 297.5 mm as compared with the circumferential length difference 319.2 mm of the conventional example.

FIG. 2 (c) shows that the narrow angle (one cutting angle) formed by the inner peripheral surface 7 and one end surface 8 of the rubber composition 5 is 35 °, and the narrow angle formed by the outer peripheral surface 6 and the other end surface 9 (the other one). An example in which the cutting angle is set to 15 ° is shown.
In the figure, the rubber composition 5 has a circumferential length A of the outer peripheral surface 6 longer by YX than a peripheral length C of the inner peripheral surface 7 by setting one cutting angle to be larger than the other cutting angle. The circumferential length relaxation amount (YX) when the rubber composition 5 is annular is (1 / tan15 ° -1 / tan35 °) × 50.8 = 16.8 mm. Therefore, the circumferential length difference generated between the outer circumferential surface 6 and the inner circumferential surface 7 can be improved to 202.4 mm as compared with the circumferential length difference 319.2 mm of the conventional example.

FIG. 2D shows a narrow angle (one cutting angle) formed by the inner peripheral surface 7 and the one end surface 8 of the rubber composition 5 is 40 °, and a narrow angle formed by the outer peripheral surface 6 and the other end surface 9 (the other side). An example in which the cutting angle is 10 ° is shown. In the same figure, when the rubber composition 5 is annular, the circumferential relaxation amount (Y-X) is (1 / tan 10 ° -1 / tan 40 °) × 50.8 = 228.6 mm. Therefore, the circumferential length difference generated between the outer circumferential surface 6 and the inner circumferential surface 7 can be improved to 90.6 mm as compared with the circumferential length difference 319.2 mm of the conventional example.
As described above, as apparent from FIG. 2, the rubber composition is set by setting one cutting angle larger than the other cutting angle in advance and setting the length of the outer peripheral surface 6 longer than the length of the inner peripheral surface 7. The circumference difference when 5 is annular can be reduced. Therefore, when the one end surface 8 and the other end surface 9 are joined, it is possible to prevent an excessive tension or compressive force from being generated on the joining surface, and both ends can be joined appropriately.
The one and the other cutting angle may be any angle as long as the length of the outer peripheral surface 6 can be made longer than the length of the inner peripheral surface 7, but the other cutting angle is set to an angle smaller than 15 °. When set, the bonding area increases, but the tip becomes too thin, and molding defects are likely to occur. Conversely, when the angle is set larger than 35 °, the bonding area decreases and the bonding force decreases. In view of the joining force when joining the one end face 8 and the other end face 9, it is desirable that the other cutting angle be in the range of 15 ° to 35 °.

FIG. 3 is a schematic view showing a state in which a plurality of rubber compositions 5 are molded by cutting a rubber composition continuously extruded by an extruder.
In the same figure, if the rubber composition 5 is extruded in the direction indicated by the arrow, one cutting angle α of the subsequent rubber composition 5 ′ following the rubber composition 5 that is previously cut by the cutting tool 10 is The other cutting angle (15 °) of the rubber composition 5 is the same angle. Therefore, when the subsequent rubber composition 5 ′ is molded, as shown by the phantom line, it is cut again so that one cutting angle α becomes 35 °, and the other cutting angle β becomes 15 °. Just cut it.
In addition, the rubber composition 5 in which the cutting angle of the extruded rubber composition is always cut alternately by α (15 °) and β (35 °), and one of the cutting angles becomes 35 ° is reversed upside down. You may make it wind on the main body 2. FIG. In addition, in the same figure, as shown in FIG. 2 (c), the rubber composition 5 is illustrated in which one cutting angle is 35 ° and the other cutting angle is 15 °. The same applies to.

  As described above, according to the tire tread manufacturing method of the present invention as described above, by arbitrarily changing the cutting angle of both end faces of the rubber composition 5 constituting the tire tread based on the circumferential length difference calculated in advance. Since the difference in circumferential length that occurs when the length of the outer peripheral surface 6 and the inner peripheral surface 7 of the rubber composition 5 is set to make the rubber composition 5 annular, a tire tread that is less prone to molding defects And a pneumatic tire provided with the said tire tread can be obtained.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the said embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made to the above-described embodiment, and it is obvious that such changes and modifications can be included in the technical scope of the present invention. It is clear from the description.

1 tire molding drum, 2 drum body, 3 green tire, 4 case,
5 rubber composition, 6 outer peripheral surface, 7 inner peripheral surface, 10 cutting tool.

Claims (6)

A method for producing an annular tire tread by cutting a belt-shaped rubber composition and joining one end face and the other end face of the cut rubber composition,
When the angle formed between the inner peripheral surface of the rubber composition and the one end surface is one cutting angle, and the angle formed between the outer peripheral surface of the rubber composition and the other end surface is the other cutting angle,
The other cutting angle is set to an angle when the length of the outer peripheral surface of the rubber composition is approximated to the peripheral length of the intermediate position in the thickness direction when the rubber composition is annular. A method for manufacturing a tire tread.   The tire tread manufacturing method according to claim 1, wherein the one cutting angle is set larger than the other cutting angle.   The tire tread manufacturing method according to claim 1, wherein the other cutting angle is set to 15 ° to 35 °. An annular tire tread formed by joining one end surface and the other end surface of a cut belt-shaped rubber composition,
A tire tread characterized in that one cutting angle formed by the inner peripheral surface of the rubber composition and the one end surface is larger than the other cutting angle formed by the outer peripheral surface of the rubber composition and the other end surface.   The tire tread according to claim 4, wherein the other cutting angle is in a range of 15 ° to 35 °.   A pneumatic tire comprising the tire tread according to claim 4 or 5.

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