JP2005178038A - Manufacturing method of retreaded tire and precured tread body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a retreated tire precisely by reducing the use chance of an unvulcanized rubber member to reduce manufacturing defectiveness. <P>SOLUTION: The manufacturing method of the retreaded tire includes a precured tread body molding process for molding a precured tread body 9 by vulcanizing a tread body obtained by laminating at least one cord ply 10 and a tread rubber 11 and an integration process for integrating the precured tread body 9 with a base tire. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a retread tire useful for accurately manufacturing a retread tire while reducing manufacturing defects, and a precure tread body used for the retread tire.

  In a retreaded tire manufacturing method generally called a precure method, a thin unvulcanized cushion rubber is first applied to a base tire from which worn or defective tread rubber has been removed, and then a new vulcanized precured tread rubber is applied. Paste and vulcanize. Thereby, the base tire and the new tread rubber are integrated via the cushion rubber. Further, when forming a base tire, if damage (for example, damage or separation of a steel belt cord) occurs on the inner belt layer of the tread rubber, one or two outer steel sheets constituting the belt layer are formed. The belt ply is also removed.

  In this case, as schematically shown in FIG. 5, the base tire a is disposed on both outer sides of the unvulcanized first cushion rubber b, the unvulcanized belt ply c, and the belt ply c in the tire axial direction. An unvulcanized cushion rubber d, an unvulcanized second cushion rubber e, a precure tread f, and the like are sequentially attached and then vulcanized. In addition, the following is known as a prior art regarding the precure type retreaded tire.

JP-A-9-295360

  However, in the conventional precure system, it is necessary to perform a large number of unvulcanized rubber members on the base tire a in sequence. Unvulcanized rubber members are likely to be scorched (burned) during storage, which may lead to poor adhesion or insufficient adhesion. In particular, when the steel belt ply is also rehabilitated, the steel belt cord is affected by moisture in the air and tends to cause insufficient adhesion with the topping rubber. Any of these may cause defective manufacture of retreaded tires.

  In addition, since it is necessary to bond a large number of components to the base tire, the larger the number of members, the more likely the position shift or the like is likely to cause dimensional variations. In particular, the retread surface a1 of the base tire a has a curved surface, and it is difficult to bond the members with high accuracy. Further, air is easily trapped between the bonding surfaces, which may cause poor vulcanization. Further, although the precure tread is vulcanized in advance, it may be deformed by heat and pressure during re-vulcanization.

  The present invention has been devised in view of the above problems, and a precure tread body is formed by vulcanizing a tread body bonded with at least one cord ply and tread rubber, Manufacture of retreaded tires that include the process of integrating the precure tread body with a base tire, reducing the chances of using unvulcanized rubber members, reducing manufacturing defects, and manufacturing retreaded tires with high accuracy. It aims to provide a method.

  The invention according to claim 1 of the present invention includes a precure tread body molding step of molding a precure tread body by vulcanizing a tread body in which at least one cord ply and tread rubber are bonded together, An integrated process for integrating a precure tread body with a base tire.

  The invention according to claim 2 is the method for producing a retread tire according to claim 1, wherein the tread body is bonded on a plane.

  The invention according to claim 3 is characterized in that the precure tread body and the base tire are integrated by an adhesive without interposing a sheet-like unvulcanized cushion rubber. It is the manufacturing method of the retreaded tire as described in.

  The invention described in claim 4 is a vulcanized precured tread body used for a retread tire, wherein a tread body in which at least one cord ply and tread rubber are bonded together is integrated by vulcanization. It is characterized by consisting of.

  The invention according to claim 5 further includes packing rubber disposed on both outer sides in the tire axial direction of the cord ply, and cushion rubber disposed on the inner side in the tire radial direction of the cord ply and the packing rubber. The precure tread body according to claim 4, wherein

  In the invention according to claim 1 or 4, since the process of attaching the cord ply and the tread rubber separately on the base tire can be performed at one time as in the conventional general precure method, In addition to improving the productivity and reducing manufacturing defects, it is possible to reduce the number of parts to be used or the number of times of pasting, which in turn can improve the manufacturing accuracy of retreaded tires. In this connection, the amount of storage of unvulcanized rubber members can be reduced by reducing the opportunity for use. Further, since the cord ply and the tread rubber can be bonded at a place other than the tread retreading surface of the base tire, workability is improved and high-precision bonding is possible.

  Moreover, since the cord ply is integrated with the tread rubber in advance in the precure tread body, the bending rigidity and the like are improved as compared with the case where the cord is made only of rubber. Therefore, the tread rubber can be prevented from being deformed by pressure, heat, etc. when it is integrated with the base tire, which is useful for producing a more accurate retread tire. Furthermore, the relative relationship between the cord ply and the tread rubber can be considered. Therefore, for example, arrange so that the bottom position of the tread groove formed in the tread rubber and the end position of the cord ply in the tire axial direction do not overlap, or adjust the width of the cord ply according to the width of the tread rubber The degree of freedom in combining the cord ply and the tread rubber is improved. This helps to provide a precure tread that can be adapted to various tyres.

  Further, as in the invention described in claim 2, when the tread body is bonded on a plane, the cord ply and the tread rubber can be aligned with higher accuracy. This is particularly effective for improving the uniformity of the retreaded tire.

  According to a third aspect of the present invention, when the precure tread body and the base tire are integrated with an adhesive without interposing a sheet-like unvulcanized cushion rubber, the unvulcanized rubber As a result of manufacturing a retread tire without using a seat, the manufacturing process can be greatly simplified and productivity can be further improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a right half sectional view of a pneumatic tire 1 before rehabilitation. The pneumatic tire 1 includes a tread portion 2 having a tread rubber 2G that comes into contact with a road surface, a pair of sidewall portions 3 extending from both ends of the tread portion 2 to the inside in the tire radial direction, It has a bead portion 4 continuously provided at the inner end, and in this embodiment, a heavy load mounted on a truck, a bus or the like is exemplified.

  The pneumatic tire 1 includes, for example, a carcass 6 that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt layer disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2. 7 and. The carcass 6 is composed of a single carcass ply 6A in which steel cords are arranged at an angle of, for example, 75 ° to 90 ° with respect to the tire equator C, and both ends of the carcass 6 around the bead core 5 from the inner side to the outer side in the tire axial direction. It is folded back and locked. The belt layer 7 is composed of a plurality of belt plies. In this example, the belt layer 7 is formed by sequentially superposing first to fourth belt plies 7A, 7B, 7C and 7D from the inner side to the outer side in the tire radial direction. Illustrated.

  As the pneumatic tire 1 is used, the tread rubber 2G is worn (an example of a worn tread surface is denoted by reference numeral 2L) and is damaged, and the tread rubber 2G has an abnormality due to a manufacturing defect regardless of use. There is a time. In such a situation, when there is no damage to the side wall part 3 and the bead part 4, it can be reused as a retread tire.

  The manufacturing method of the retreaded tire of this embodiment includes a base tire forming step of forming the base tire 1B (shown in FIG. 2) from the pneumatic tire 1, a precure tread body forming step of forming the precure tread body 9, Including the integration step of integrating the precure tread body 9 with the base tire 1B, and will be described in the following order. The order of the previous two steps is not limited.

  In the base tire forming step, as shown in FIG. 2, the base tire 1 </ b> B is formed by removing unnecessary tread rubber 2 </ b> G from the renewed pneumatic tire 1. The base tire 1B of this example is formed by removing the tread rubber 2G and the third to fourth belt plies 7C and 7D from the pneumatic tire 1. Thereby, as for the base tire 1B, the tread renovation surface E in which the precure tread body 9 mentioned later is affixed is formed in the tread area | region. The base tire 1B is formed with at least the carcass 6 left.

  Since the belt plies 7C and 7D are arranged at positions close to the tread rubber 2G, the belt plies 7C and 7D are usually fatigued by a relatively large strain acting during load running and may be damaged. large. In order to enhance the durability of the retreaded tire, it is preferable to remove at least one or two cord plies arranged on the outermost side together with the tread rubber 2G as in this example. Needless to say, if other plies are also injured, they can be removed.

  The removal of the tread rubber 2G and the like can be performed by, for example, cutting, and then it is desirable to finish the tread reclaimed surface E smoothly by buffing. For example, the buffing is preferably performed in a state in which the internal pressure is filled in the base tire 1B and the tire shape is kept constant. Thereby, the finishing accuracy of the tread reclaimed surface E is improved, and it is useful for increasing the adhesive strength with the precure tread body 9. The tread rehabilitation surface E is formed between the second belt ply 7B and the third belt ply 7C. In this embodiment, the buttress has a smooth arc curve along the outer surface of the second belt ply 7B. What extends to the part is shown. However, the tread reclaimed surface E is not limited to such a form, and may include, for example, a part or the whole of a linear portion extending in the tire axial direction.

  In the precure tread body forming step of the present embodiment, as shown in FIG. 3A, one cord ply 10, tread rubber 11, and the cord ply 10 are arranged on both outer sides in the axial direction. A tread body 14 in which the packing rubber 12 and the cushion rubber 13 disposed on the inner side in the tire radial direction of both the cord ply 10 and the packing rubber 12 are bonded together is integrated by vulcanization, and the pre-shown in FIG. A cure tread body 9 is formed.

  In such a precure tread body 9, since the cord ply 10 and the tread rubber 11 are integrated in advance by vulcanization, the number of parts required for rehabilitation is reduced. In addition, the pre-cured tread body 9 is free from defects such as poor adhesion between the scorch and the cord and the topping rubber unlike the unvulcanized rubber even when stored for a long period of time. Helps improve. Such a precure tread body 9 can be manufactured in large quantities in advance in a well-equipped environment such as a manufacturing factory of a tire manufacturer. This greatly helps to reduce the occurrence of air pockets and the like during the pasting operation of the cord ply 11 and the tread rubber 10 that has been conventionally performed by a rehabilitation manufacturer.

  Moreover, since the precure tread body 9 bonds and vulcanizes the cord ply 10 and the tread rubber 11, the relative relationship between the two can be considered. For example, the tread grooves G1 and G2 formed in the tread rubber 11 are arranged so that the groove bottom positions of the tread grooves G1 and G2 do not overlap with the end positions of the cord ply 10 in the tire axial direction. The step of adjusting the cord ply 10 according to the specification of the tread rubber 11 can be included, such as adjusting the width of the cord ply according to the above. Thereby, the precure tread body 9 which can adapt to various stand tires and customer requirements can be provided.

  Conventionally, it has also been proposed to cut out tread rubber or tread rubber and a belt ply from a used old tire and use it as a precure tread body. However, this is a so-called dismantled product and is not a newly vulcanized molded product as in this embodiment. Therefore, it is considered that productivity is poor and quality is also problematic.

  The cord ply 10 is formed by covering an array of tire cords with unvulcanized topping rubber, and only one piece is used in this embodiment. A steel cord is preferably used as the tire cord, but nylon, rayon, and other organic fiber cords can also be used. The cord ply 10 forms a new belt layer together with the first and second belt plies 7A and 7B remaining on the base tire 1B. The belt ply removed from the pneumatic tire 1 is two, but since there is no problem in strength, only one cord ply 10 is used. The number of code plies 10 used, code rehabilitation, and the like can be variously determined according to the application situation. For example, the number of cord plies 10 is made equal to the number of plies removed, the number of cord plies 10 is reduced to increase the number of steel cords driven, the cord diameter is increased, and the ply width is increased. It is also preferable to reinforce the ply itself.

  The tread rubber 11 is, for example, an unvulcanized one extruded from a rubber extruder or the like, or a vulcanized one obtained by pre-curing the same (including a semi-vulcanized one, and the same applies hereinafter). Either of these can be used. In the case of the unvulcanized tread rubber 11, it is desirable that the tread grooves G1 and G2 are recessed in advance during extrusion. Even when the tread rubber 11 is already vulcanized, since the cord ply 10 is unvulcanized, it can be easily bonded by its adhesiveness and can be easily integrated by vulcanization.

  The packing rubber 12 is made of a small-thick unvulcanized rubber sheet disposed on both outer sides of the cord ply 10 in the tire axial direction. Since the width of the cord ply 10 in the tire axial direction is smaller than the width of the tread rubber 11 in the tire axial direction, the packing rubber 12 is useful for filling the step. Further, since stress concentration tends to occur at the end of the cord ply 10, it is preferable to use a rubber material having excellent adhesiveness with a steel cord or other rubber as the packing rubber 12. Specifically, a rubber material containing cobalt is suitable.

  The cushion rubber 13 is an unvulcanized rubber sheet having a small thickness. The width and thickness of the cushion rubber 13 in the axial direction of the tire are not particularly limited. However, if they are extremely inappropriate, the adhesive strength with the base tire 1B is lowered, and the durability of the retread tire is lowered. Tend. From such a viewpoint, it is desirable that the width of the cushion rubber 13 in the tire axial direction is set to be approximately equal to the width of the tread reclaimed surface E in the tire axial direction. The thickness of the cushion rubber 13 is not particularly limited, but is preferably 1 to 5 mm, more preferably about 1 to 3 mm. In addition, what integrated the cushion rubber 13 and the said packing rubber 12 previously can also be used.

  As shown in FIG. 3 (A), the tread body 14 is formed by bonding the respective members, and is integrated with each other as shown in FIG. 3 (B) by being vulcanized. Preferably, it is desirable to perform these bondings on the plane M. In the conventional precure method, the cord ply 10 and the tread rubber 11 are performed on the tread reclaimed surface E of the base tire 1B. The tread reclaimed surface E extends in a circle and has a circular arc cross section. Since it is a curved surface, there is a limit to accurately performing center alignment. On the other hand, in this embodiment, since both members (all members) can be bonded on the plane M, the tread rubber 11 and the cord ply 10 can be easily centered with high accuracy. This can make the weight balance of the tread portion of the retread tire uniform, and is useful for improving uniformity.

  In vulcanizing the tread body 14, a mold may be used to form a pattern, or a vulcanizing can may be used. Particularly preferably, at least the affixing surface i which is the surface on the cord ply 10 side is desirably vulcanized to a substantially flat surface. Thereby, workability | operativity, such as buffing of the bonding surface i, can be improved. In addition, since it is a substantial plane, in addition to a so-called plane, those having a slight curvature (for example, a curvature radius of about 600 mm) are included. Particularly preferably, in the cross section in the tire meridian direction, the contour line of the affixing surface i of the precure tread body 9 is preferably larger than the radius of curvature of the contour line of the tread reclaimed surface E of the base tire 1B. As a result, when the precure tread body 9 is bonded to the tread renewal surface E of the base tire 1B, it is possible to bond the precure tread body 9 with high accuracy while preventing the accumulation of air near the tire equator.

  The integration process of this embodiment shows what integrates the precure tread body 9 and the base tire 1B with an adhesive without interposing a sheet-like unvulcanized cushion rubber. For example, an adhesive containing unvulcanized rubber is suitable for the adhesive. In order to prevent the cushion rubber from intervening, in the method for manufacturing a retread tire according to this embodiment, it is sufficient to attach and adhere the precure tread body 9 to the tread retread surface of the base tire 1B via an adhesive. Thus, it is not necessary to use any unvulcanized rubber sheet, and the manufacturing process can be greatly simplified. As said adhesive agent, what melt | dissolved cushion rubber or packing rubber in the solvent can be used conveniently. In addition, the method of integrating the base tire 1B and the precure tread body 9 is not limited to the adhesive, and, for example, unvulcanized cushion rubber can be used according to the custom.

  After the precure tread body 9 and the base tire 1B are pasted, heat and pressure are applied by a vulcanizing can and firmly integrated. At this time, since the precure tread body 9 is a molded product in which the cord ply 10 is integrated with the tread rubber 11 by vulcanization in advance, the bending rigidity and the like are greatly improved as compared with the case where the precure tread body 9 is made of only the rubber alone. . Accordingly, in the integration step, even if a large pressure or heat is applied, deformation of the tread grooves G1 and G2 of the tread rubber 11 can be suppressed, and a more accurate retread tire can be manufactured.

Twenty retread tires each having a size of 11R22.5 were prototyped by the conventional precure method (FIG. 5) and the method using the precure tread body of the present invention, and the time required for production and uniformity were measured. Uniformity measured the radial force variation (RFV) and the lateral force variation (LFV) of each retreaded tire using a uniformity machine based on the uniformity measurement method of JASO C607. In the evaluation, each average value was used, and in each case, the value was expressed as an index with the numerical value of the conventional precure method as 100. The smaller the numerical value, the higher the uniformity and the better.
The test results are shown in Table 1.

  As a result of the test, it can be confirmed that any of the retreaded tires manufactured by the method of the example is excellent in uniformity. In the conventional method, the cord ply and the tread rubber are bonded on a curved surface such as a base tire. However, in the present invention, the tread rubber and the cord ply can be centered because they can be performed on a flat plate. This is thought to be due to high accuracy.

It is sectional drawing which shows an example of a pneumatic tire. It is a fragmentary sectional view showing a base tire from which tread rubber was removed. (A) is an exploded view of an unvulcanized tread rubber body, and (B) is a cross-sectional view of a precure tread body. It is a fragmentary sectional view which integrated the precure tread body with the base tire. It is a cross-sectional schematic diagram explaining the conventional retreaded retreaded tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 1B Base tire 1C Rehabilitation tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6A Carcass ply 7 Belt layer 7A, 7B, 7C, 7D Belt ply 9 Precure tread body 10 Tread rubber 11 Belt ply (Code ply)
12 Cushion rubber 13 Packing rubber 14 Tread body

Claims (5)

A precure tread body molding step of molding a precure tread body by vulcanizing a tread body bonded with at least one cord ply and tread rubber;
A method for producing a retread tire, comprising an integration step of integrating the precure tread body with a base tire.   The method for manufacturing a retread tire according to claim 1, wherein the tread body is bonded on a plane.   The method for producing a retread tire according to claim 1 or 2, wherein the precure tread body and the base tire are integrated by an adhesive without interposing a sheet-like unvulcanized cushion rubber. .   A vulcanized precured tread body for use in a retread tire, comprising a molded product obtained by integrating a tread body in which at least one cord ply and tread rubber are bonded together by vulcanization Tread body. Packing rubber disposed on both outer sides in the tire axial direction of the cord ply;
The precure tread body according to claim 4, further comprising a cushion rubber disposed on an inner side in a tire radial direction of the cord ply and the packing rubber.

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