JP4589684B2 - Manufacturing method of rubber member for tire and pneumatic tire - Google Patents

Description

  The present invention relates to a method for manufacturing a tire rubber member and a pneumatic tire capable of improving productivity and finishing a cross-sectional shape with high accuracy.

  In recent years, various so-called strip winding methods have been proposed in which a ribbon-shaped unvulcanized rubber strip is spirally wound around a member to be wound (for example, a raw carcass or a molding former) to produce an annular tire rubber member. (For example, refer to the following patent document). In such a strip winding method, a rubber member having an arbitrary cross-sectional shape is formed by changing a winding pitch of a rubber strip to be wound. Therefore, unlike the conventional integral extrusion method, there is no preparation or replacement work of a die having a predetermined cross-sectional shape for each tire, and improvement in productivity can be expected.

  10 to 13 show several examples of a cross section of a tread rubber b as a conventional tire rubber member. FIG. 10 shows an integral extrudate b1 extruded integrally by an extruder.

11 to 13 are all made by the strip wind method. The tread rubber b2 in FIG. 11 is formed by winding a continuous rubber strip g around a cylindrical body c to be spirally wound in one direction from one side edge e1 to the other side edge e2. It is formed. The tread rubber b3 in FIG. 12 uses two independent rubber strips g1 and g2, with one rubber strip g1 from one side edge e1 and the other rubber strip g2 from the other side edge e2. In this case, the winding ends f1 and f2 are positioned substantially at the center of the width. In FIG. 11 and FIG. 12, the rubber strip g is schematically drawn with a gap for easy understanding.

  Further, the tread rubber b4 of FIG. 13 uses two independent rubber strips g1 and g2, one rubber strip g1 from the width center position of the tread rubber b4 to one side edge e1, and the other rubber strip g2 having a width. Each of them is wound from the center position toward the other side edge e2.

Japanese Patent No. 3477289 Japanese Patent No. 3352045 Japanese Patent No. 3370282 Japanese Patent No. 3398430

  As shown in FIG. 14, the tread rubber b manufactured by the conventional strip winding method has a winding start end s and / or a winding end f of the rubber strip g at the side edges e1 and e2 of the rubber member (tread rubber b). positioned. For this reason, the discontinuous part k of the side edge having a step shape in plan view is easily formed at the winding start end s and the winding end f of the rubber strip g. Such a discontinuous portion k has a drawback that the cross section of the tread rubber b is made nonuniform in the tire circumferential direction and the uniformity is deteriorated.

  Further, the winding start end s and the winding end f of the rubber strip g are more easily separated than other portions. For this reason, if they are located on the side edge of a tread rubber or the like, there is a drawback that cracks, rubber chipping, etc. are likely to occur from that portion after vulcanization.

  The present invention has been devised in view of the above problems, and is based on limiting the positions of the winding start end and winding end of a rubber strip, and is excellent in productivity, uniformity and durability. It aims at providing the manufacturing method of a member, and a pneumatic tire.

The invention according to claim 1 of the present invention is that a ribbon-like unvulcanized rubber strip is spirally wound around a substantially cylindrical body to be wound from one side edge to the other side edge. A method for manufacturing a tire rubber member for manufacturing an annular rubber member having an axial width, wherein the winding start end of the first rubber strip and the winding start end of the second rubber strip are located above the respective side edges. Fixing to the wound body at an inner position in the width direction, winding the first rubber strip toward one side edge spirally to the one side edge, and attaching the second rubber strip to the other side A first winding step in which a first layer is formed by spirally winding to the other side edge toward the other side edge, and the first rubber strip is folded back at one side edge to the other side edge. When we wrap around spirally In addition, the second rubber strip is folded back at the other side edge and spirally wound toward one side edge to form a second layer continuously outside the first layer. A winding step; and a step of fixing the winding end of the first rubber strip and the winding end of the second rubber strip to a position on the inner side in the width direction from each side edge , and the first rubber strip. The winding start end of the rubber member is provided between the other side edge of the rubber member and the width center of the rubber member, and the winding start end of the second rubber strip is set to one side edge of the rubber member and the width center. In the first winding step, the first rubber strip and the second rubber strip intersect each other at the width center .

  The invention according to claim 2 is the method for producing a tire rubber member according to claim 1, wherein the tire rubber member is a tread rubber or a part thereof.

According to a third aspect of the present invention, the winding end of the first rubber strip and the winding end of the second rubber strip are provided on the center of the width of the rubber member. It is a manufacturing method.

  According to a fourth aspect of the present invention, the winding start end of the first rubber strip is fixed substantially symmetrically with the winding start end of the second rubber strip with respect to the width center of the rubber member. 4. A method for producing a tire rubber member according to any one of 3 above.

  According to a fifth aspect of the present invention, the winding end of the first rubber strip is fixed at a substantially symmetrical position with respect to the winding end of the second rubber strip with respect to the width center of the rubber member. 4. A method for producing a tire rubber member according to any one of 4 above.

  According to a sixth aspect of the present invention, in the tire rubber according to any one of the first to fifth aspects, the first rubber strip and the second rubber strip have the same rubber composition and the same cross-sectional shape. It is a manufacturing method of a member.

  According to a seventh aspect of the present invention, prior to the first winding step, a rubber strip is spirally wound around the wound body from one side edge toward the other side edge in the tire circumferential direction. The tire rubber member manufacturing method according to any one of claims 1 to 6, further comprising an under layer forming step of forming an under layer inside the first layer.

  In the invention according to claim 8, between the under layer forming step and the first winding step, the rubber strip is spirally wound in the tire circumferential direction from one side edge to the other side edge. The tire rubber member manufacturing method according to claim 7, further comprising a middle layer forming step of forming a middle layer between the under layer and the first layer.

The invention according to claim 9 is a pneumatic tire in which a tread rubber is disposed in a tread portion, wherein at least a part of the tread rubber has a winding start end on the inner side in the width direction than the tread edge. A first layer formed by spirally wrapping the rubber strip and the second rubber strip toward the tread edge in opposite directions, and the first rubber strip and the second rubber strip are arranged on the respective sides. The tread edges of the first rubber strip and the second rubber strip are continuously formed outside the first layer by being folded back at the tread edge and spirally wound toward the tire equator. Ri Do from the strip laminated body and a second layer provided on the inside in the width direction than the first layer, one of the first rubber strip The second layer is formed by spirally winding toward the one tread edge toward the tread edge and spirally winding the second rubber strip toward the other tread edge toward the other tread edge. The first rubber strip is folded back at one tread edge and spirally wound toward the other tread edge, and the second rubber strip is folded at the other tread edge and spiraled toward the one tread edge. It is formed on the outside of the first layer by winding, and the winding start end of the first rubber strip is provided between the other tread edge and the tire equator, and the second rubber strip The winding start end is provided between the one tread edge and the tire equator, whereby the first rubber strip and the second And arm strip is characterized that you have to intersect at the tire equator.

  The method for producing a rubber member according to the present invention fixes the winding start end of the first rubber strip and the winding start end of the second rubber strip to the member to be wound at a position on the inner side in the width direction from each side edge of the rubber member. The process of carrying out is included. Therefore, the winding start end of each rubber strip is not positioned on the side edge of the rubber member.

  Further, the first rubber strip is spirally wound toward one side edge to the one side edge and the second rubber strip is spirally wound toward the other side edge to the other side edge. A first wrapping step for forming a first layer, and the first rubber strip is folded back at one side edge and spirally wound toward the other side edge, and the second rubber strip is wound on the other side. A second winding step of continuously forming a second layer on the outside of the first layer by spirally wrapping at one edge toward one side edge, thereby providing a relatively large thickness. The rubber member can be efficiently formed in a short time.

  Furthermore, in the present invention, the winding end of the first rubber strip and the winding end of the second rubber strip are fixed to the inner side in the width direction from the respective side edges. For this reason, the winding end of each rubber strip is not positioned at the side edge of the rubber member. Therefore, the tire rubber member manufactured according to the present invention can improve the uniformity of the tire, the durability of the rubber member, and the like.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a molding apparatus 1 for producing the tire rubber member of the present invention. The molding apparatus 1 includes a base 2, a cylindrical molding former 3 that is rotatably supported by the base 2, and an applicator 4 that can supply a rubber strip 8 to the molding former 3. Composed.

  The base 2 includes an electric motor and a power transmission device for transmitting torque thereof to the molding former 3. The torque of the electric motor is output to a rotating shaft 7 that is rotatably supported on the side of the base 2.

  The molding former 3 includes a plurality of segments 3A arranged in the tire circumferential direction, and an expansion / contraction mechanism (not shown in detail) 6 that is provided on the inside thereof and moves the segments 3A in and out of the tire radial direction. . Each surface of the segment 3A is connected in the tire circumferential direction at a position moved outward in the tire radial direction by the expansion / contraction mechanism 6. Thereby, as shown in FIG. 2, a cylindrical molding surface U around which a rubber strip 8 described later is spirally wound is provided. For example, when it is desired to mold a rubber member having a curvature in advance, the molding surface U can be provided with a curved surface.

  On the other hand, the molding surface U can be reduced in diameter by moving the segments 3A alternately inward in the tire radial direction. This is useful for removing the rubber member wound around the molding surface U from the molding former 3. The expansion / contraction mechanism 6 is fixed to the rotary shaft 7. Therefore, the molding former 3 can be rotated together with the rotating shaft at a predetermined direction and speed. The expansion / contraction diameter of the segment 3A, the rotation speed of the molding former 3, and the like are appropriately adjusted by a controller (not shown).

  The applicator 4 is formed in a conveyor shape, for example, and continuously supplies a ribbon-like and unvulcanized rubber strip 8 on the conveying surface to the molding surface U of the molding former 3. Although not shown, on the upstream side of the applicator 4, there are provided a rubber extruder or calendar machine for continuously extruding the rubber strip 8, and a festoon that can temporarily control the supply speed of the rubber strip. The applicator 4 is provided so as to be appropriately movable with respect to the molding former 3 by being supported by, for example, a three-dimensional movement device (not shown).

  In addition, the molding apparatus 1 of the present embodiment is provided with a first applicator 4A and a second applicator 4B which are arranged with a position shifted in the tire axial direction and the tire circumferential direction with respect to the molding former 3. . The first applicator 4A can continuously supply the first rubber strip 8A to the molding former 3. Further, the second applicator 4B can continuously supply the second rubber strip 8B supplied independently of the first rubber strip 8A to the molding former 3.

  For example, as shown in FIG. 3, the rubber strip 8 is formed in a ribbon shape having a substantially rectangular cross section in this embodiment having a width W larger than the thickness t. The width W and the thickness t of the rubber strip 8 are not particularly limited, but preferably the width is 15 to 35 mm and the thickness t is 0.5 to 1.5 mm. When the width W of the rubber strip 8 is less than 15 mm or when the thickness t is less than 0.5 mm, when the rubber member is formed by spirally wrapping, the number of windings of the rubber strip 8 is remarkably increased and the productivity is lowered. Conversely, when the width W exceeds 35 mm or when the thickness t exceeds 1.5 mm, it tends to be difficult to make a delicate cross-sectional shape. In the present embodiment, the first rubber strip 8A and the second rubber strip 8B have the same rubber composition and the same cross-sectional shape.

  FIG. 4 shows an example of manufacturing a tread rubber R as a tire rubber member. First, the tread rubber R has a target cross-sectional shape designed in advance, as indicated by a virtual line, and has a width from one side edge e1 to the other side edge e2 in the tire axial direction. In the present embodiment, first, the winding start ends 8As and 8Bs of the first rubber strip 8A and the second rubber strip 8B are attached to the body to be wound at the positions inside the respective side edges e1 and e2 in the width direction. A fixing step is performed. The side edges e1 and e2 are specifically determined based on the cross-sectional shape of the rubber member. For example, in the case of a rectangle or a substantially trapezoidal shape as shown in FIG. Further, the width from one side edge e1 to the other side edge e2 indicates the largest width RW between the side edges.

  The wound body is a molding surface U of the molding former 3 in this example. Since the molding surface U is formed of the metal segments 3A, the molding surface U is not deformed when the rubber strip 8 is wound, and serves to form a highly accurate rubber member. In addition, as shown with a virtual line in FIG. 1, the belt ply B etc. can also be previously wound around the molding surface U. FIG. In addition to the molding surface U of the molding former 3, the rubber strip 8 is made of a raw carcass that is unvulcanized and held in a cylindrical shape, a raw carcass around which a belt ply is wound, and the like to be wound. Can be wound. In this case, it is desirable to support the raw carcass so that it cannot be displaced from the inside by using a holding body or the like so that the raw carcass is not deformed by the tension of the rubber strip 8. As for rubber, “unvulcanized” refers to a state where vulcanization is not completely completed. Therefore, what is only pre-vulcanized is included in unvulcanized.

  Moreover, the winding start ends 8As and 8Bs of the rubber strip are pressed toward the molding surface U by the pressing roller 5 from the outside, for example, as indicated by phantom lines in FIG. Thereby, each winding start end 8As and 8Bs of each rubber strip 8A and 8B is fixed to the molding surface U by its own adhesive force. The pressing roller 5 can move inward and outward in the radial direction with respect to the molding surface U of the molding former 3, for example, and moves to a position where it does not interfere with the applicator 4 after pressing the winding start ends 8As and 8Bs of the rubber strip 8. it can.

  The winding start end 8As of the first rubber strip and the winding start end 8Bs of the second rubber strip are both fixed to the molding surface U at inner positions in the width direction than both side edges e1, e2 of the tread rubber R. In other words, the winding start end 8As of the first rubber strip and the winding start end 8Bs of the second rubber strip are both fixed at positions that do not constitute the side edges e1 and e2 of the tread rubber R. In this example, the winding start end 8As of the first rubber strip is formed between the other side edge e2 of the tread rubber R and the width center CL of the tread rubber R (of course, the other side edge e2 of the tread rubber R is constituted. The position is not included.) Further, the winding start end 8Bs of the second rubber strip is between one side edge e1 of the tread rubber R and the width center CL (of course, the position constituting the one side edge e1 of the tread rubber R is not included). Provided.

  The winding start end 8As of the first rubber strip is fixed to a substantially symmetrical position with the winding start end 8Bs of the second rubber strip with respect to the width center CL of the tread rubber R. In this embodiment, the winding start ends 8As and 8Bs are exemplified as those fixed in proximity to each other so that the facing side edges substantially contact each other.

  As shown in FIG. 2, the winding start end 8As of the first rubber strip and the winding start end 8Bs of the second rubber strip are shifted from each other at an angle α (α ≠ 0 °) in the tire circumferential direction. Provided. The angle α is not particularly defined, but if it is too large, the device space tends to increase due to the layout of the applicators 4A and 4B, and conversely if it is too small, the first rubber strip 8A and the second When the rubber strip 8B is crossed, there is a risk of interference. From such a viewpoint, the angle α is preferably about 10 to 40 °, for example. As shown in FIG. 2, each applicator 4 </ b> A, 4 </ b> B desirably includes a portion that guides the rubber strip 8 so as to extend in the tangential direction of the molding surface U in a side view. This is preferable in that an extra external force acts on the rubber strip 8 as much as possible.

  Next, the first rubber strip 8A is spirally wound toward the one side edge e1 toward the one side edge e1, and the second rubber strip 8B is directed toward the other side edge e2 and the other side edge e1. A first winding step for forming the first layer 10 by spirally winding up to e2 is performed. The rubber strips 8A and 8B are spirally wound around the molding surface U by rotating the molding former 3 in the direction shown in FIG. 2 and moving the applicators 4A and 4B in the direction of the tire rotation axis. It will be done.

  For example, when the molding former 3 is rotated at a constant speed, the spiral pitch around which the rubber strip 8 is wound can be changed by controlling the moving speed of the applicator 4 in the tire rotation axis direction. The helical pitch can be reduced by reducing the moving speed of the applicator 4. This increases the overlapping width of the adjacent rubber strips 8 to increase the thickness of that portion. Conversely, by increasing the moving speed of the applicator 4, the helical pitch can be increased. This makes it possible to reduce the overlapping width of the adjacent rubber strips 8 or to make the thickness of the portion thinner by making the width substantially zero. The spiral pitch, in other words, the moving speed of the applicator is determined in advance in consideration of a pre-designed desired cross-sectional shape of the tread rubber R, a cross-sectional shape of the rubber strip, a rotational speed of the molding former 3, and the like. The information is input to a controller (not shown) for controlling the moving speed of the applicators 4A and 4B (not shown), and the applicator 4 is controlled to move.

  As shown in FIG. 2, the first and second rubber strips 8 </ b> A and 8 </ b> B are sequentially wound around the forming former 3 at the positions of the respective winding start ends 8 </ b> As and 8 </ b> Bs by the rotation of the forming former 3. Since the winding start ends 8As and 8Bs are displaced in the tire circumferential direction, the first rubber strip 8A and the second rubber strip 8B intersect at the width center CL of the tread rubber R in the first winding step. The rubber strips 8A and 8B are continuously wound without interfering with each other.

  In the present embodiment, the first applicator 4A and the second applicator 4B are synchronously controlled in the first winding step. Specifically, each applicator 4A, 4B is controlled to have substantially the same moving speed at an arbitrary time, although the directions of movement are opposite to each other. Accordingly, in the first winding step, each applicator 4A, 4B (in other words, the first rubber strip 8A and the second rubber strip 8B) is substantially symmetric with respect to the width center CL at any time. When the first rubber strip 8A reaches one side edge e1, the second rubber strip 8B can reach the other side edge e2. Therefore, for example, compared with the case where the rubber strip 8 is continuously spirally wound from one side edge e1 to the other side edge e2 with one applicator, the winding time can be shortened and the productivity can be improved. The first layer 10 formed by the first winding step has a continuous width from the one side edge e1 to the other side edge e2, and has a rubber strip 8 winding structure (interface of the rubber strip). , The width center CL is substantially line symmetric.

  As a particularly preferable aspect, a step of winding the first rubber strip 8A at an arbitrary length along the tire circumferential direction at the one side edge e1 to eliminate the discontinuous portion k as shown in FIG. 14 is included. It is desirable. Similarly, it is desirable to wind the second rubber strip 8B at an arbitrary length along the tire circumferential direction at the other side edge e2. In each side edge e1 or e2, the length for winding the rubber strip 8 along the tire circumferential direction can be appropriately set according to the helical pitch, the width W of the rubber strip 8, or the like. This is useful for making the cross-sectional shape of the tread rubber uniform in the tire circumferential direction.

  Next, in the present embodiment, the first rubber strip 8A is folded at one side edge e1 and spirally wound toward the other side edge e2, and the second rubber strip 8B is folded at the other side edge e2. A second winding step of continuously forming the second layer 11 on the outside of the first layer 10 is performed by spirally winding toward the side edge e1.

  Also in the second step, the first applicator 4A and the second applicator 4B are synchronously controlled. That is, the applicators 4A and 4B are controlled so as to have substantially the same moving speed at an arbitrary time, although the directions of movement are opposite to each other. Therefore, in the second winding step, each applicator 4A, 4B (in other words, the first rubber strip 8A and the second rubber strip 8B) is in a line-symmetrical position with respect to the width center CL of the tread rubber R. . As in the first winding step, this can reduce the winding time and productivity compared to the case where the rubber strip is continuously spirally wound from one side edge e1 to the other side edge e2 with one applicator. To help improve.

  The second layer 11 is formed continuously with the first layer 10. That is, after forming the first layer 10, the rubber strip 8 is continuously wound around the outside without being cut to form the second layer 11. Therefore, since the rubber strip 8 can be continuously wound without being interrupted between the first winding process and the second winding process, productivity can be improved also in this respect.

  In the second winding step, the spiral pitch of the rubber strips 8A and 8B on the outer side in the width direction of the tread rubber R is relatively small, and the spiral pitch on the width center side is relatively large. The thickness is formed so as to gradually and gradually decrease toward the width center side. This approximates the cross-sectional shape of a conventional extruded tread rubber. Therefore, it is useful for continuing to use a conventional mold or the like.

  Next, a step of fixing the winding end 8Af of the first rubber strip and the winding end 8Bf of the second rubber strip to the inner positions in the width direction from the respective side edges e1 and e2 is performed. When the second winding step is completed, the first and second rubber strips 8A and 8B are cut, and the end of the winding is pressed to the predetermined position by the pressing roller 5 to fix the winding end. . The first and second rubber strips 8A and 8B can be automatically cut using a cutting tool (not shown).

  In the present embodiment, the winding end 8Af of the first rubber strip is fixed substantially symmetrically with the winding end 8Bf of the second rubber strip with respect to the width center of the tread rubber R. More specifically, in the present embodiment, the winding ends 8Af and 8Bf are provided on the width center CL of the tread rubber R. Accordingly, the second layer 11 in this example has a continuous width extending from one side edge e1 to the other side edge e2.

  The tread rubber R which is such a tire rubber member has a substantially line-symmetric cross-sectional shape with respect to the width center CL including not only the contour shape but also the winding structure of the first and second rubber strips 8A and 8B. Can be obtained. In addition, the winding start ends 8As and 8Bs of the first and second rubber strips 8A and 8B and the winding end ends 8Af and 8Bf are all provided at positions on the inner side in the width direction from the side edges of the tread rubber R. Such a tread rubber R increases the uniformity of the tire by making the sectional shape uniform in the tire circumferential direction. Further, cracks caused by the winding start end or winding end of the rubber strip 8 located at the side edge can prevent damage such as rubber chipping.

FIG. 5 schematically shows another embodiment in which the winding start ends and the winding end ends of the first and second rubber strips 8A and 8B are different. In the aspect (A), the winding start end 8As of the first rubber strip 8A is provided between the width center CL and one side edge e1, and the winding start end 8Bs of the second rubber strip 8B is It is provided between the width center CL and the other side edge e2. The winding end 8Af of the first rubber strip 8A is provided between the width center CL and the other side edge e2, and the winding end 8Bf of the second rubber strip 8B is connected to the width center CL and one of the side edges e2. It is provided between the side edges e1. The winding start ends 8As and 8Bs do not intersect at the width center CL, but the thickness of the central portion of the tread rubber R can be secured by intersecting the winding termination ends 8Af and 8Bf with each other.

  5B is the same as the embodiment of FIG. 5A, but the winding start ends 8As and 8Bs and the winding end ends 8Af and 8Bf are both provided approximately in the middle between the width center CL and the side edge e1 or e2. It has been. Furthermore, the thing of FIG.5 (C) wraps each rubber strip 8A, 8B further by the side edges e1, e2 in the 2nd winding process, and was wound by the width center CL side. Thus, the winding start end and winding end of each rubber strip 8A, 8B can be provided at free positions.

  Moreover, although the said embodiment showed the example which comprises the whole tread rubber R by the 1st and 2nd rubber strips 8A and 8B, this invention is using the rubber member which comprises some tread rubber R, for example. It may be used as a manufacturing method. For example, when the tread rubber R is composed of a plurality of layers having different rubber blends, for example, three layers, at least one layer (that is, a part of the tread rubber) can be produced by the above-described method. 6 and 7 show an example of a method for forming a tread rubber R composed of three layers of rubber.

  First, as shown in FIG. 6A, prior to the first winding step, the third rubber strip 13 is placed on the molding surface U of the molding former 3 from one side edge e1 side to the other side edge e2 side. An under layer forming step for forming the under layer 14 is performed by spirally winding the tire in the tire circumferential direction. In this example, the under layer 14 having a small thickness is formed by slightly overlapping the side edges of the third rubber strip 13.

  Since the under layer 14 is bonded to the belt layer, it is preferable to use, for example, a rubber compound excellent in adhesiveness with the topping rubber of the belt layer. Further, the winding start end 13s and the winding end 13f of the under layer 14 are also provided at positions on the inner side in the width direction from the side edges e1 and e2 on both sides of the tread rubber R. Thereby, also about the under layer 14, the winding start end 13s and winding end 13f of the rubber strip are not located at the side edges e1 and e2 of the tread rubber R. Therefore, it is possible to effectively prevent cracks and rubber peeling in the under layer 14 at the side edge of the tread rubber. Further, since the width of the belt layer is generally smaller than the width RW of the tread rubber, the under layer 14 may be formed with such a small width.

  Next, as shown in FIG. 6B, the fourth rubber strip 15 made of a rubber compound different from the third rubber strip 13 is moved from one side edge e1 side to the other side edge e2 side. Then, a middle layer forming step is performed in which the middle layer 16 is formed outside the under layer by being spirally wound in the tire circumferential direction. The middle layer 16 in this example is wound with the side edges of the fourth rubber strip 15 overlapping each other. Since the middle layer 16 is disposed, for example, inside the tread rubber R, it is desirable to mix the rubber with low heat generation and low energy loss.

  Further, the winding start end 15s and the winding end 15f of the fourth rubber strip 15 forming the middle layer 16 are also provided at positions on the inner side in the width direction from the side edges e1 and e2 on both sides of the tread rubber R. As a result, the winding start end 15s and the winding end 15f of the middle layer 16 are not positioned at the side edges e1 and e2 of the tread rubber R, and therefore cracks and rubber at the middle layer 16 at the side edges e1 and e2 of the tread rubber R Separation can be effectively prevented.

  And in order to form a cap layer on the outer side of these under layer 14 and the middle layer 15, the 1st rubber strip 8A and the 2nd rubber strip 8B are wound in the above-mentioned procedure. FIG. 7 shows a cross-sectional view of such a tread rubber R. The tread rubber R is formed of a plurality of layers (three layers) having different rubber blends. As described above, in the tread rubber R, the winding start ends and winding end of the rubber strips 8A, 8B, 13 and 15 forming all the layers are located on the inner side (width center) of the side edges e1 and e2 of the tread rubber R. ), It is possible to more reliably prevent cracking at the winding start end and winding end of the rubber strip and improve the durability of the rubber member.

  The fourth rubber strip 15 forming the middle layer 16 may be wound after the winding of the under layer 14 is completely completed, but in that case, idle time may occur and productivity may be reduced. There is. Preferably, as shown in FIGS. 8A to 8D, the winding of the fourth rubber strip 15 is started between the start of winding of the third rubber strip 13 and the end of winding. desirable. That is, as shown in FIG. 8 (A), when the third rubber strip 13 is wound around the molding former 3 to form a predetermined width, the winding of the third rubber strip 13 is stopped once, The winding start end 15s of the four rubber strips 15 is fixed to the outside (FIG. 8B). Thereafter, it is desirable to wind the third rubber strip 13 and the fourth rubber strip 15 simultaneously toward the other side edge e2. The winding time of the rubber strip 15 can be shortened, and the productivity is further improved.

  FIG. 9 shows a partially enlarged view of a tread portion of a pneumatic tire 1 made using tread rubber as a tire rubber member manufactured according to the above-described embodiment. In this embodiment, a heavy-duty pneumatic tire used for trucks, buses and the like is shown. The pneumatic tire 1 includes a carcass 21 of a steel cord and a belt layer 22 arranged on the outside thereof, and a tread rubber 23 is arranged on the outside of the belt layer 22.

  At least a part of the tread rubber 23 includes a strip laminated body made of a rubber member formed by the above-described method. The strip laminate has winding start ends 8As and 8Bs of the first and second rubber strips on the inner side in the width direction than the tread edge Te. Similarly, the winding ends 8Af and 8Bf of the first and second rubber strips are provided on the inner side in the width direction than the tread edge Te. In such a pneumatic tire, since the winding start and end of each rubber strip are not located at the tread edge Te and the side edge Te1 including the tread edge Te, it helps to improve the tire uniformity and the durability of the tread rubber. . Even after vulcanization, by cutting the tire with a sharp blade, the boundary surface of the rubber strip 8 appears thinly in the cross section. Therefore, the positions of the winding start ends 8As and 8Bs and the winding end ends 8Af and 8Bf can be specified.

  Although the embodiment of the present invention has been described above, the present invention can be used for, for example, a sidewall rubber, an inner liner, a cushion rubber, and the like in addition to the tread rubber as long as it is an annular tire rubber member. The rubber member obtained by the present invention can be used not only for pneumatic tires for heavy loads but also for pneumatic tires of various categories.

Twenty heavy-duty pneumatic tires each having a size of 11R22.5R were produced using a plurality of types of unvulcanized tread rubber having the specifications shown in Table 1. Except for the tread rubber, the tread pattern and the internal structure are the same. And about these, the durability and durability of the tread rubber were evaluated.
The evaluation method is as follows.

<Uniformity>
For each test tires (average value of n = 20) were measured La Jiaruran'nauto (RRO), and the RRO of Comparative Example 1 was indicated by an index to 100. The smaller the value, the better.

<Durability of tread rubber>
Each test tire was mounted on a 7.50 × 22.5 rim, and after running 50,000 km on a drum with a radius of 1.7 m at an air pressure of 700 kPa, a load of 50 kN, and a speed of 100 km / H, the tread rubber was visually observed. In addition, after visual observation, the tread rubber was disassembled and the internal damage was examined.
Table 1 shows the test results.

  From the test results, it was confirmed that the tires of the examples had improved uniformity and durability of the tread rubber compared to the comparative examples.

1 is an overall perspective view of a rubber member molding apparatus showing an embodiment of the present invention. FIG. It is a perspective view of a rubber strip. (A)-(E) are the cross-sectional schematic diagrams explaining the shaping | molding procedure of a tread rubber. (A)-(C) are the schematic which shows the winding aspect of the rubber strip which shows other embodiment. (A), (B) is sectional drawing explaining an under layer and a middle layer. It is sectional drawing of the tread rubber which shows other embodiment. (A)-(D) are sectional drawings explaining the other formation procedure of an under layer and a middle layer. It is an enlarged view of the tread part of a pneumatic tire. It is sectional drawing of the conventional tread rubber. It is sectional drawing of the conventional tread rubber. It is sectional drawing of the conventional tread rubber. It is sectional drawing of the conventional tread rubber. It is a top view of tread rubber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rubber | gum member shaping | molding apparatus 2 Base 3 Molding former 4, 4A, 4B Applicator 8 Rubber strip 8A 1st rubber strip 8As 1st rubber strip winding start end 8Af 1st rubber strip winding end 8B 2nd Rubber strip 8Bs Second rubber strip winding start end 8Bf Second rubber strip winding end point 13 Third rubber strip 15 Fourth rubber strip 20 Pneumatic tire 23 Tread rubber (vulcanized)
R tread rubber (unvulcanized)
e1 One side edge e2 The other side edge

Claims (9)

An annular rubber member having an axial width from one side edge to the other side edge is obtained by spirally winding a ribbon-like unvulcanized rubber strip around a substantially cylindrical body to be wound. A method for manufacturing a tire rubber member to be manufactured, comprising:
Fixing the winding start end of the first rubber strip and the winding start end of the second rubber strip to the wound body at a position on the inner side in the width direction from the respective side edges;
Wrapping the first rubber strip spirally toward one side edge to the one side edge and spirally winding the second rubber strip toward the other side edge to the other side edge A first winding step of forming a first layer by:
The first rubber strip is folded at one side edge and spirally wound toward the other side edge, and the second rubber strip is folded at the other side edge and spirally wound toward the one side edge. A second winding step of continuously forming a second layer outside the first layer;
Fixing the winding end of the first rubber strip and the winding end of the second rubber strip to a position on the inner side in the width direction from each side edge , and
A winding start end of the first rubber strip is provided between the other side edge of the rubber member and the width center of the rubber member; and
The winding start end of the second rubber strip is provided between one side edge of the rubber member and the width center,
In the first winding step, the first rubber strip and the second rubber strip intersect each other at the width center .
  The method for manufacturing a tire rubber member according to claim 1, wherein the tire rubber member is tread rubber or a part thereof. The tire rubber member manufacturing method according to claim 1 or 2, wherein the winding end of the first rubber strip and the winding end of the second rubber strip are provided on the center of the width of the rubber member .
  The tire starting point according to any one of claims 1 to 3, wherein the winding start end of the first rubber strip is fixed substantially symmetrically with the winding start end of the second rubber strip with respect to the width center of the rubber member. Manufacturing method of rubber member.   The tire end according to any one of claims 1 to 4, wherein the winding end of the first rubber strip is fixed substantially symmetrically with the winding end of the second rubber strip with respect to the width center of the rubber member. Manufacturing method of rubber member.   The tire rubber member manufacturing method according to any one of claims 1 to 5, wherein the first rubber strip and the second rubber strip have the same rubber composition and the same cross-sectional shape.   Prior to the first winding step, an under layer is formed on the inner side of the first layer by spirally winding a rubber strip around the wound body from one side edge to the other side edge in the tire circumferential direction. The method for producing a tire rubber member according to any one of claims 1 to 6, further comprising an under layer forming step of forming the tire.   Between the under layer forming step and the first winding step, a rubber strip is spirally wound in the tire circumferential direction from one side edge toward the other side edge to thereby form the under layer and the first layer. The method for producing a rubber member for a tire according to claim 7, further comprising a middle layer forming step of forming a middle layer between the two. A pneumatic tire with tread rubber on the tread,
At least a part of the tread rubber is spirally wound around the first rubber strip and the second rubber strip each having a winding start end on the inner side in the width direction than the tread edge in a reverse direction toward the tread edge. A first layer formed;
The first rubber strip and the second rubber strip are folded back at the tread edge on each side and wound spirally toward the tire equator, and are formed continuously outside the first layer. 1 of the rubber strip and winding end of the second rubber strip Ri Do from the strip laminated body and a second layer provided on the inside in the width direction than the tread edges,
The first layer spirally wraps the first rubber strip toward one tread edge to the one tread edge and the second rubber strip faces the other tread edge. Formed by spirally winding to the edge,
The second layer is configured such that the first rubber strip is folded back at one tread edge and spirally wound toward the other tread edge, and the second rubber strip is folded at the other tread edge to form one tread edge. Formed on the outside of the first layer by wrapping in a spiral toward
Moreover, the winding start end of the first rubber strip is provided between the other tread edge and the tire equator, and the winding start end of the second rubber strip is formed between the one tread edge and the tire equator. A pneumatic tire characterized in that the first rubber strip and the second rubber strip intersect each other at the tire equator by being provided in between .

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