JP6445926B2 - Rubber strip for tire, rubber strip cutting device, and pneumatic tire manufacturing method using the rubber strip - Google Patents

Description

  The present invention relates to a tire rubber strip that can improve tire uniformity and appearance, a rubber strip cutting device, and a method for manufacturing a pneumatic tire using the rubber strip.

  Conventionally, in order to manufacture a pneumatic tire, a raw tire is formed by spirally winding an unvulcanized rubber strip. The rubber strip usually has an edge cut obliquely in one direction with respect to the width direction (see, for example, Patent Document 1 below). However, the oblique end edges as described above cause mass deviation in the width direction of the rubber strip. For this reason, for example, when the edge of the rubber strip is located on the side surface of the green tire, there is a problem that peeling occurs from the edge of the rubber strip due to a mass deviation with time.

  Patent Document 2 listed below proposes a rubber strip having a corner edge that is substantially V-shaped symmetrical in the width direction in order to prevent the above-described mass deviation.

JP 2012-162046 A JP 2014-233911 A

  By the way, the rubber strips are usually spirally wound with a predetermined winding width. As a result of various studies, the inventors have found that it is effective to suppress the peeling of the rubber strip over time by associating the winding width with the shape of the corner of the edge of the rubber strip.

  The present invention has been devised in view of the above situation, and is useful for suppressing separation at the edge, a rubber strip for a tire, a rubber strip cutting device, and air using this rubber strip. The main purpose is to provide a method for manufacturing a tire.

  A first invention of the present application is a belt-like rubber strip that is spirally wound around a rotation axis of a tire to manufacture a pneumatic tire, and has a first end portion that terminates at the time of winding. The edge of the end portion includes a substantially V-shaped corner in plan view, and the innermost vertex of the corner is located at a distance a in the width direction from one side edge of the rubber strip in the width direction. The distance a is greater than 0% and less than 50% of the width of the rubber strip.

  In the rubber strip for a tire of the present invention, the distance a is preferably 35% to 45% of the rubber strip width.

  In the rubber strip for a tire according to the present invention, it is desirable that an inner angle of the corner is 60 to 80 °.

  In the rubber strip for a tire according to the present invention, the first end portion includes a first taper portion on one side of the entry corner edge and a second taper portion on the other side of the entry corner edge. It is desirable that the tip of the tapered portion and the tip of the second tapered portion are at the same position in the length direction of the strip.

  In the rubber strip for a tire according to the present invention, the first end portion includes a first taper portion on one side of the entry corner edge and a second taper portion on the other side of the entry corner edge. It is desirable that the tip of the taper portion and the tip of the second taper portion are displaced in the length direction of the strip.

  A second invention of the present application is a cutting apparatus for obtaining any of the above rubber strips, wherein the rubber strip is synchronized with the rubber strip around an axis perpendicular to the direction of conveyance of the rubber strip. And a rotary cutting tool that cuts the rubber strip by the rotation. The rotary cutting tool has a cylindrical main body portion and a cutting blade protruding from the main body portion. The cutting blade includes a first portion that is inclined with respect to the axial direction in the main body portion, and a second portion that is continuous with the first portion and is inclined in a direction opposite to the first portion. It is said.

  A third invention of the present application is a method for manufacturing a pneumatic tire, wherein one of the rubber strips is substantially disposed at the distance a on a rigid core that molds the inner surface of the pneumatic tire. It is characterized by including a step of spirally winding with an equal winding width.

  In the method for manufacturing a pneumatic tire according to the present invention, it is preferable that the apex of the entering corner edge of the first end portion is located on the outer side in the tire radial direction than the center position in the width direction of the rubber strip.

  A first invention of the present application is a belt-like rubber strip that is spirally wound around a rotation axis of a tire to manufacture a pneumatic tire, and has a first end portion that terminates at the time of winding. The edge of the end portion includes a substantially V-shaped corner in plan view, and the innermost vertex of the corner is located at a distance a in the width direction from one side edge of the rubber strip in the width direction. The distance a is greater than 0% and less than 50% of the width of the rubber strip. The first end portion having such an entering corner edge can prevent mass deviation in the width direction as compared with a rubber strip having a single inclined edge. Further, the apex distance a can be changed in accordance with, for example, the winding width of the rubber strip, and can be matched, for example. Thereby, for example, the edge of the rubber strip can be deformed starting from the apex, and the edge of the already wound rubber strip can be firmly fixed.

  A second invention of the present application is a cutting device for obtaining the above-described rubber strip, and can be rotated in synchronism with the rubber strip around a conveying means for conveying the rubber strip and an axis perpendicular to the conveying direction of the rubber strip. A rotary cutting tool that cuts the rubber strip by rotation, the rotary cutting tool has a cylindrical main body portion and a cutting blade protruding from the main body portion, and the cutting blade is a main body. The portion includes a first portion that is inclined with respect to the axial direction, and a second portion that is continuous with the first portion and is inclined in the direction opposite to the first portion. Such a cutting device can easily obtain the above-mentioned rubber strip by rolling the rotary cutting tool on the rubber strip.

  A third invention of the present application is a method for manufacturing a pneumatic tire, wherein the rubber strip is wound substantially equal to the distance a around a rigid core that forms a lumen surface of the pneumatic tire. The method includes a step of winding spirally with an overlap width. Thereby, for example, the edge of the rubber strip can be deformed starting from the apex, and the edge of the already wound rubber strip can be firmly fixed. Therefore, peeling can be prevented while achieving mass dispersion at the edge of the rubber strip.

It is a perspective view of the rubber strip of one embodiment of the present invention. It is an enlarged plan view of the 1st end part of the rubber strip of FIG. It is sectional drawing of a rigid core when a rubber strip is wound helically. It is the elements on larger scale of the Y section of FIG. FIG. 5 is a sectional view taken along line XX in FIG. 4. It is an enlarged plan view of the 1st end part of the rubber strip of other embodiments of the present invention. It is a perspective view of the cutting device for obtaining the rubber strip of this invention. It is sectional drawing of the rotary cutting tool of the cutting device of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an enlarged perspective view of a rubber strip for tires of the present embodiment (hereinafter simply referred to as “rubber strip”) 1 before being wound. FIG. 2 shows an enlarged plan view of the first end portion 2 that terminates at the time of winding. As shown in FIG. 1, the rubber strip 1 of the present embodiment is long and belt-like, and is spirally wound around the rotation axis of the tire with a predetermined winding width. As a result, various tire rubber members such as tread rubber and inner liner rubber are formed.

  FIG. 3 shows a cross-sectional view of the rigid core 10 when the rubber strip 1 is wound. As shown in FIG. 3, the rubber strip 1 of the present embodiment forms an inner liner rubber in a pneumatic tire manufacturing method using a rigid core 10 that molds the inner surface of the pneumatic tire, for example. It is preferably used in some cases. This manufacturing method will be described later. The rubber strip 1 of the present embodiment is not limited to such a mode, and may be wound spirally as a tread rubber around a raw tire shaped like a toroid, for example.

  As shown in FIG. 2, the edge of the first end portion 2 includes, for example, a first taper portion 6 and a second taper portion 7 in plan view.

  The 1st taper part 6 inclines with respect to the side edges 11 and 12 of the rubber strip 1, for example. The second taper portion 7 is inclined in the opposite direction to the first taper portion 6. As a result, the first end portion 2 is formed with a substantially V-shaped corner edge 3 in plan view. The first end 2 includes a first protruding corner 13 between the side edge 11 on one side of the rubber strip 1 and the first taper portion 6, and a side edge 12 on the other side of the rubber strip 12 and a second taper. A second protruding corner portion 14 between the portion 7 and the second portion 7.

  The innermost apex 4 of the entering corner edge 3 is located at a distance a in the width direction from the side edge 11 on one side in the width direction of the rubber strip 1. The distance a is greater than 0% and less than 50% of the width W1 of the rubber strip 1.

  The first end 2 having such a corner 3 can prevent mass deviation in the width direction as compared with a rubber strip having a single inclined edge.

  FIG. 4 shows a partially enlarged view of a Y portion in FIG. FIG. 4 is an enlarged view of the first end 2 in a state where the rubber strip 1 has been wound. As shown in FIG. 4, the distance a of the vertex 4 can be changed in accordance with, for example, the winding width b of the rubber strip 1, and can be matched, for example. Thereby, as shown in FIG. 5, the edge of the rubber strip 1 can be deformed, for example, starting from the vertex 4, and the edge of the already wound rubber strip 1 can be firmly fixed. Thereby, peeling at the edge of the rubber strip 1 is suppressed, and the uniformity and appearance of the tire can be improved.

  As shown in FIG. 2, when the distance a is small, it approximates to a rubber strip having a single inclined edge, and there is a possibility that the mass deviation in the width direction of the first end portion 2 becomes large. When the distance a is large, it is difficult to match the winding width of the rubber strip 1, and the above-described effect may be reduced. From such a viewpoint, the distance a is preferably 35% or more, more preferably 38% or more, preferably 45% or less, more preferably 42% or less, before the rubber strip width W1.

  When the inner angle θ1 of the entrance corner edge 3 is small, the first exit corner portion 13 and the second exit corner portion 14 may be excessively tapered, and the tip thereof may be easily displaced. When the internal angle θ1 of the entrance corner edge 3 is large, the vertex 4 is unlikely to be a starting point of deformation of the rubber strip 1, and the above-described effect may be reduced. From such a point of view, the inner angle θ1 of the entrance corner edge 3 is preferably 60 ° or more, more preferably 65 ° or more, preferably 80 ° or less, more preferably 75 ° or less.

  In the present embodiment, the tip 8 of the first taper portion 6 and the tip 9 of the second taper portion 7 are at the same position in the length direction of the strip. Such a corner 3 is useful for maintaining uniformity.

  FIG. 6 is an enlarged plan view of the first end 2 of the rubber strip 1 according to another embodiment of the present invention. As shown in FIG. 6, in this embodiment, the tip 8 of the first taper portion 6 and the tip 9 of the second taper portion 7 are displaced in the length direction of the strip. Specifically, the tip 9 of the second taper portion 7 protrudes in the length direction of the rubber strip from the tip 8 of the first taper portion 6.

  This embodiment is used, for example, in such a manner that the first protruding corner portion 13 is wound around an already wound rubber strip and the second protruding corner portion 14 is attached to a wound body such as a rigid core. Such a 1st end part 2 can ensure the area of the 2nd protruding corner part 14 large, and can suppress peeling of the 1st end part 2 from the 2nd protruding corner part 14 as the starting point.

  In order to obtain the above-mentioned effect while maintaining uniformity, the distance L1 in the length direction of the strip between the tip 8 of the first taper portion 6 and the tip 9 of the second taper portion 7 is preferably equal to the rubber strip width W1. It is 0.25 times or more, more preferably 0.30 times or more, preferably 0.40 times or less, more preferably 0.35 times or less.

  As shown in FIG. 3, the rubber strip 1 of each of the above-described embodiments is suitably used for a pneumatic tire manufacturing method using a rigid core 10, for example. In this manufacturing method, a rubber member for a tire is attached to the outer surface of a rigid core 10 that molds the inner cavity surface of a pneumatic tire to form a raw tire, and the raw tire is vulcanized together with the rigid core. Thus, a pneumatic tire is formed.

  In this embodiment, the rubber strip 1 described above is attached to the outer surface of the rigid core 10. Thereby, for example, an inner liner rubber is formed on the outer surface of the rigid core 10.

  For example, the rubber strip 1 is spirally formed on the outer surface of the rigid core 10 from the bead portion on one side (left side in FIG. 3) of the tire through the tread portion to the bead portion on the other side (right side in FIG. 3) of the tire. Wrapped around. In the present embodiment, the first end 2 of the rubber strip 1 is positioned on the right side surface of the rigid core 10, for example.

  As shown in FIG. 4, in this embodiment, the winding is finished so that the apex 4 of the corner 3 of the first end portion 2 is located on the outer side in the tire radial direction from the center position 5 of the rubber strip. As a further desirable mode, the rubber strip 1 is wound spirally with a winding width b substantially equal to the distance a. Thereby, the edge of the rubber strip 1 can be deformed, for example, starting from the vertex 4 and the edge of the already wound rubber strip 1 can be firmly fixed. Therefore, it is possible to prevent peeling while achieving mass dispersion at the edge of the rubber strip 1.

  In the method for manufacturing a pneumatic tire of this embodiment, a known technique is suitably used for the steps not described in this specification.

  FIG. 7 shows a perspective view of the cutting device 15 for obtaining the rubber strip described above. As shown in FIG. 7, the cutting device 15 includes a conveying means 16 for conveying the rubber strip 1 and a rotary cutting tool 17.

  For example, the conveying means 16 places the rubber strip 1 supplied from a rubber extruder (not shown) provided on the upstream side on the conveying belt 18 and conveys it to the downstream side.

  The rotary cutting tool 17 is provided, for example, so as to be rotatable in synchronization with the rubber strip 1 around an axis perpendicular to the conveying direction of the rubber strip 1. The rotary cutting tool 17 includes, for example, a cylindrical main body 19 and a cutting blade 20 protruding from the main body 19. The main body 19 is located, for example, on the conveyance surface side of the conveyance belt 18 and is arranged in a direction in which the rotation axis intersects the traveling direction of the conveyance belt 18.

  The cutting edge 20 includes a first portion 21 that is inclined with respect to the axial direction in the main body portion 19 and a second portion 22 that is continuous with the first portion 21 and is inclined in the direction opposite to the first portion 21. Thereby, the cutting blade 20 is formed in V shape.

  The rotary cutting tool 17 is connected to the drive motor 24 via a connecting boss 23, for example. The drive motor 24 rotates the rotary cutting tool 17 in synchronization with the traveling speed of the conveyor belt 18, for example. As shown in FIG. 8, when the rubber strip 1 is not cut, the drive motor 24 places the cutting blade 20 on the upper side of the rotary cutting tool 17 and stops it. The drive motor 24 rotates the rotary cutting tool 17 once when cutting the rubber strip 1. As a result, the rubber strip 1 having the above-described corner is easily obtained.

  As described above, the rubber strip, the rubber strip cutting device, and the method for manufacturing the pneumatic tire using the rubber strip according to the embodiment of the present invention have been described in detail. The present invention is not limited to the form, and can be implemented with various modifications.

  As an example, a pneumatic tire was manufactured using the rubber strip shown in FIG. As a comparative example, a pneumatic tire was manufactured using a rubber strip whose first end edge is slanted in one direction. All are common except for the shape of the first end of the rubber strip. Using each rubber strip, 1000 tires were manufactured, and the appearance rate and uniformity of the appearance defect of the tire due to the shape of the first end portion of the rubber strip were measured. The measuring method is as follows.

<Occurrence rate of tire appearance defects>
The incidence of tire appearance defects due to the shape of the first end of the rubber strip was measured. The result is an index with Comparative Example 1 being 100, and the smaller the numerical value, the smaller the appearance rate of the appearance defect and the better.

<Uniformity>
For the tire manufactured with each rubber strip, the radial force variation RFV, which is a fluctuation component of the force in the tire radial direction during rotation, was measured. The RFV was measured using a tire uniformity testing machine in accordance with JASOC 607: 2000 “Method for testing uniformity of automobile tires”. Moreover, a result is an index | exponent which sets the comparative example 1 to 100, and shows that the uniformity of the manufactured tire is so favorable that a numerical value is small.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the rubber strips of the examples suppressed appearance defects and improved uniformity.

1 Rubber strip 2 First end 3 Corner edge 4 Vertex 5 Center position

Claims (8)

A belt-like rubber strip wound spirally around the axis of rotation of the tire to produce a pneumatic tire,
Having a first end that ends when wound,
The edge of the first end includes a substantially V-shaped corner edge in plan view,
The innermost apex of the entering corner edge is located at a distance a in the width direction from one side edge of the rubber strip in the width direction,
The rubber strip for tires, wherein the distance a is greater than 0% and less than 50% of the width of the rubber strip.   The rubber strip for a tire according to claim 1, wherein the distance a is 35% to 45% of a width of the rubber strip.   The rubber strip for a tire according to claim 1 or 2, wherein an inner angle of the entering corner edge is 60 to 80 °. The first end portion includes a first tapered portion on one side of the entering corner edge, and a second tapered portion on the other side of the entering corner edge,
The rubber strip for a tire according to any one of claims 1 to 3, wherein a tip end of the first taper portion and a tip end of the second taper portion are at the same position in a length direction of the strip. The first end portion includes a first tapered portion on one side of the entering corner edge, and a second tapered portion on the other side of the entering corner edge,
The rubber strip for a tire according to any one of claims 1 to 3, wherein a tip end of the first taper portion and a tip end of the second taper portion are displaced in a length direction of the strip. A cutting device for obtaining the rubber strip according to any one of claims 1 to 5,
Conveying means for conveying the rubber strip, and a rotary cutting tool provided so as to be rotatable in synchronism with the rubber strip around an axis orthogonal to the conveying direction of the rubber strip, and for cutting the rubber strip by the rotation. Have
The rotary cutting tool has a cylindrical main body part and a cutting blade protruding from the main body part,
The cutting blade includes a first portion that is inclined with respect to an axial direction in the main body portion, and a second portion that is continuous with the first portion and is inclined in a direction opposite to the first portion. Rubber strip cutting device. A method for manufacturing a pneumatic tire, comprising:
A step of spirally winding the rubber strip according to any one of claims 1 to 5 with a winding width substantially equal to the distance a on a rigid core that forms a lumen surface of the pneumatic tire. A method for manufacturing a pneumatic tire.   The method for manufacturing a pneumatic tire according to claim 7, wherein the apex of the entering corner edge of the first end portion is located on the outer side in the tire radial direction from the center position in the width direction of the rubber strip.

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