JP5495698B2 - Precured tread, retreaded tire, and retreaded tire manufacturing method - Google Patents

Description

The present invention relates to a retreaded tire, in particular, agricultural machine tire, aircraft tire, Purekyuatore' de suitable for rehabilitation of construction vehicle tire, has been retreaded tire and a manufacturing method thereof relating to rehabilitation using the precured tread.

  When manufacturing tires used for agricultural machinery tires, aircraft tires, construction vehicle tires, etc. as retreaded tires, the tread rubber having a worn tread pattern is removed by cutting and a new tread rubber is pasted. This is done by forming a pasting surface called a buff surface of the tire and molding a tire that is a base of a retread tire called a base tire, and then attaching a vulcanized precured tread to the buff surface of the base tire.

Precure treads have a pair of molds that have molding surfaces facing each other. The tread material made of unvulcanized rubber is placed between the molding surfaces, sandwiched between the molds, and heated for a specified time. By doing so, the tread material is vulcanized and formed into a flat strip having a substantially trapezoidal cross section that is sufficiently longer than the circumferential length of the buff surface of the base tire. This vulcanized precured tread has a molding surface that is attached to the buff surface of the base tire by the molding surface of one mold, and a tread pattern as a tire tread is molded by the molding surface of the other mold. Is done.
On the other hand, the buff surface of the base tire to which the precure tread is affixed is formed by cutting and removing the tread rubber of the used tire with a buff machine, thereby forming a buff surface to which the new tread rubber is affixed. The buff surface is cut so that the diameter set in advance in the radial direction of the tire and the cross section in the width direction have a predetermined shape. This shape is called a buff line, and is set to an optimum shape according to the structure of a used tire that becomes a stand tire, for example.

The precure tread and the base tire are integrated as follows.
First, a cushion rubber made of unvulcanized rubber for bonding the precure tread to the buff surface of the base tire is placed, and the precure tread vulcanized and molded into a flat strip on the cushion rubber is placed around the base tire. The surface of the base tire is cut by winding so that the winding start portion and the winding end portion of the precure tread coincide with each other when the tire is wound in the circumferential direction while applying tension in the direction and becomes the length L1 of one tire circumference. Paste the precure tread.
Then, the tire surface including the precure tread is covered with an envelope made of a rubber material, and the base tire and the precure tread covered with the envelope are put into a pressure vessel called a vulcanization can, and the inside of the vulcanization can is Cushion rubber is vulcanized by pressurization and heating, and a retread tire is manufactured by adhering precure tread to the surface of the base tire.

However, as shown in FIG. 4, from the relationship between the circumferential length difference between the length of the sticking surface and the tread surface side length L2 of the thickness of the precure tread, a flat strip-shaped pre-bump is formed on the buff surface that is three-dimensionally curved and molded. It is necessary to apply a cure tread while applying tension using the elasticity of rubber. A tensile force acts on the tread side of the pre-cured tread, a compressive force acts on the affixing side, a tread side, an affixed surface It will be affixed to a base tire in the state where distortion was inherent in both sides. For this reason, when retreaded tires are used, cracks are likely to occur in the groove portions of the blocks constituting the tread pattern, particularly the tread pattern, due to the influence of strain inherent in the precure tread. This crack is called an ozone crack, and it is caused by the action of ozone contained in the atmosphere against the strain inherent in the groove of the tread pattern. Therefore, in order to eliminate the crack, a precure tread is applied to the base tire. When attaching, it is necessary to prevent distortion in the precure tread as much as possible. In particular, in agricultural machinery tires, aircraft tires, construction vehicle tires, etc., the rubber thickness of the precured tread to be affixed tends to be thick, so the precured tread is pasted along the buff surface of the base tire. When this occurs, a large circumferential length difference is likely to occur between the affixing surface and the tread surface, and there is a high possibility that ozone cracks will occur as a result of large distortion occurring on both the affixing surface and the tread surface.
In addition, by forming the both ends of the precure tread in the width direction to be thin, a method of removing the strain acting in the width direction on the tread surface side and the affixing surface side, or forming the precure tread in an annular shape, The former method is also proposed, in which a base tire is provided on the inner peripheral side of the cure tread and the pre-cured tread and the base tire are attached to remove the strain acting in the circumferential direction on the tread side and the stick side. In the tire circumferential direction, distortion is inherent in the tread surface side and the affixing surface side of the precure tread, and in the latter method, distortion is inherent in the tread surface side and the affixing surface side of the precure tread in the tire width direction. For this reason, it was impossible to obtain a precure tread and a retreaded tire in which distortion in both the width direction and the circumferential direction of the tire does not occur.

JP 2006-346930 A JP 2001-180228 A

Therefore, in order to solve the above-described problems, the present invention provides a precured tread and a retread tire that does not cause distortion in the circumferential direction and the radial direction of the precured tread application surface and the tread surface when the precured tread is applied to the base tire. And a method for producing a retread tire .

As a first configuration of the present invention, a pre-cured tread that is formed to a predetermined length shorter than the outer peripheral length of a base tire surface, is placed on the base tire surface and is attached to the base tire surface, The shape of the affixed surface before being affixed to the tire is molded into a shape that curves along the curved shape in the width direction and the radial direction of the surface of the base tire.
According to the present invention, the precured tread application surface is curved and molded along the width direction and the radial direction of the tire surface to which the precured tread of the base tire is attached. When the tread is affixed, distortion is not inherent in the precure tread, and generation of ozone cracks on the tire tread surface of the precure tread can be suppressed. Further, since the circumferential length of the precure tread is shorter than the circumferential length of the surface of the base tire, it can be attached to the surface of the base tire without applying an excessive force when it is attached to the surface of the base tire.

As a second configuration of the present invention, the application surface of the precure tread is made substantially the same as the shape of the base tire surface in the width direction and the radial direction.
According to the present invention, since the precured tread sticking surface is formed in substantially the same shape as the width and radial direction of the tire surface of the base tire, it is only necessary to place the precured tread on the surface of the base tire. Since the precure tread can be pasted and the precure tread is hardly distorted in the width direction and the radial direction, the occurrence of ozone cracks on the tire tread surface of the precure tread is further suppressed.

As a third configuration of the present invention, the tread surface of the precure tread is substantially the same as the shape of the original product tire that becomes the base tire.
According to the present invention, in addition to the effects produced by the first and second configurations, the tread surface of the precure tread is substantially the same as that of the original product tire. Tires can be manufactured.

  In addition, the method for producing a retread tire according to the present invention includes a step of applying a plurality of precure treads according to any one of claims 1 to 3 to the surface of the base tire and affixing it over the circumference of the surface of the base tire. It is characterized by that.

As a fifth configuration of the present invention, a plurality of the precure treads according to any one of claims 1 to 3 are combined on the surface of the base tire and adhered over one turn of the surface of the base tire .
According to the present invention, the retread tire to which the precure tread according to any one of claims 1 to 3 is attached to a base tire does not have any tensile or compression strain inherent in the precure tread. The occurrence of is suppressed more.

As a sixth configuration of the present invention, the retread tire is used for agricultural machinery, aircraft, or construction vehicles.
According to the present invention, the tire for an agricultural machine, aircraft, or construction vehicle has a thick tire tread portion. Therefore, when the precure tread is attached to the buff surface of the base tire, the application surface and the tread surface are provided. The difference in length in the circumferential direction is likely to occur between the two surfaces, and there is a high possibility that ozone cracks will occur as a result of large strains on both the application surface and the tread surface. Since there is no inherent compression strain, it is particularly suitable for rehabilitating tires for agricultural machinery or aircraft or construction vehicles.

  The summary of the invention does not enumerate all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention. 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. It is not necessarily essential to the solution means of the invention, and includes a configuration or process that is selectively adopted.

The perspective view of the precure tread which concerns on this invention. The front view of the precure tread which concerns on this invention, and the width direction sectional drawing of a base tire. The side view and radial direction sectional drawing of the precure tread which concern on this invention. The table | surface which shows the relationship of the circumference difference of the sticking surface length and tread side length for the thickness of a precure tread.

Embodiment Hereinafter, an embodiment of the present invention will be described.
FIG. 1 is a perspective view in which a plurality of precure treads 1A to 1C are attached and an enlarged perspective view of the precure tread 1A.
As shown in FIGS. 1A and 1B, the precure tread 1 is formed by combining a plurality of precure treads 1A to 1C into an annular shape. Hereinafter, the sticking surface 2 and the tire tread 3 of the precure tread 1 will be described in detail. Each of the precure treads 1A to 1C is molded so as to have the same shape and dimensions as those of a new product of the pasting surface 2 that is curved in advance in the radial direction and the width direction and the base tire 11 to be pasted. The tire tread surface 3 is formed, and is molded with a predetermined length shorter than the outer peripheral length of the base tire 11.

2 shows a front view of the precure tread 1 and an AA ′ sectional view in the width direction A1, and FIG. 3 shows a side view and a BB ′ sectional view of the precure tread 1.
The sticking surface 2 of the precure tread 1 has a shape that curves in a cup shape or a bowl shape in the AA 'cross section in the width direction A1, and is a surface of a base tire that is set when cutting a tread portion of a used tire The buff surface 12 is curved so as to follow the buff line curve B1 and is formed by a radius R1 which is a distance from the tire rotation center C of the base tire 11 to the buff surface 12 in the BB ′ cross section in the radial direction A2. It is curved and molded along the peripheral surface.
That is, as shown in FIGS. 2 and 3, the affixing surface 2 of the precure tread 1 cuts the tread portion of the worn agricultural machine tire and is equal to the radius R1 in the radial direction A2 of the molded buff surface 12. Then, it is three-dimensionally curved in the radial direction A2 and the width direction A1 so as to coincide with the buff line curve B1 in the width direction A1. That is, the affixing surface 2 of the precure tread 1 is molded substantially the same as the radius of curvature of the tire surface in the tire width direction and the tire circumferential direction.

The tire tread 3 is molded so as to have the same dimensions as a new product tire before the base tire 11 is created when the precure tread 1 is attached to the base tire 11 to obtain a retread tire described later. That is, when the precure tread 1 is attached to the base tire 11, the groove depth of the outer diameter R2 of the retread tire formed by the ground contact surfaces 7 of the plurality of tread blocks 6 constituting the tread pattern of the tire tread surface 3. D and tire width W are molded so as to have the same dimensions as the product tire.
As shown in FIG. 1, the front end face 21 of the precure treads 1 </ b> A to 1 </ b> C is formed into a mountain shape that gradually protrudes toward the center in the width direction, and the rear end face 22 is centered in the width direction so as to correspond to the front end face 21. It is molded into a valley shape that gradually squeezes toward Moreover, each precure tread 1A-1C is formed in the circumferential direction length in the length of 1/3 of the circumferential direction length of the top part 13 of the buff surface 12 of FIG. That is, the precure tread 1 for one circumference of the tire is formed by attaching the precure treads 1 </ b> A to 1 </ b> C to the buff surface 12.
The circumferential length of the precure tread 1 is not limited to one third, and may be set as appropriate. When the tread block 6 is characteristic like the tire for agricultural machinery as in this example, the tread block 6 is What is necessary is just to set with the length which does not cut | disconnect. In addition, the front end surface 21 is formed in a mountain shape and the rear end surface 22 is formed in a valley shape so as to correspond to the front end surface 21, but the shape is not limited to this, and the main point is that the rear end surface 22 is formed with respect to the front end surface 21. It suffices if they are formed so as to correspond and match.

Hereinafter, the manufacturing method of a retreaded tire is demonstrated.
Precured treads 1 </ b> A to 1 </ b> C are formed from one mold that molds the tire tread surface 3 that is the same as the product tire and the other mold that molds the pasting surface 2 that substantially matches the buff surface 12 of the base tire 11. It is molded by a pair of molds. Specifically, after placing a tread material made of unvulcanized rubber with respect to the other mold, one mold is opposed and brought into close proximity to form one mold and the other mold. The pre-cured treads 1A to 1C having a predetermined length that are three-dimensionally curved are formed by housing the tread material in the molding space to be heated and pressurizing it.

As shown in FIG. 3, the base tire 11 has a radial direction A2 as shown in FIG. 2B by cutting the tire surface of the tread portion of the used tire so as to have a predetermined thickness and shape. And it shape | molds in the shape which has a toroidal-shaped tire surface in the width direction A1.
Specifically, the base tire 11 is manufactured as follows.
The worn tread pattern of the used tire with the worn tread pattern is cut by the buff machine so as to have a buff line curve B1 corresponding to the structure of the base tire 11, and the buff surface 12 is molded. The buff surface 12 has a curved shape along the width direction A1 and the radial direction A2 so as to correspond to the pasting surface 2 of the precure tread 1.

  The base tire 11 molded by the above process is generally called a ply cord, and an inner liner 31 made of a rubber layer for holding the tire internal pressure and keeping the tire internal pressure so that air does not leak from the inside of the tire. A carcass 32 formed by adhering a fiber cord or steel cord to a carcass rubber as a skeleton and a steel cord or the like, and maintains a close contact with a wheel rim or a tire and a wheel against torque acting on a rotating tire. A bead cord 33 that fixes the tire to the rim so that no slip occurs between the rim and a bead filler 34 that is formed integrally with the bead cord and reinforces the bead portion of the tire, and further includes a steel cord or the like. , Suppresses changes due to changes in tire internal pressure and rotation, receives input from the road surface, and reduces impact It is a structure comprising a central upper portion of the carcass 32 with a plurality of belts 35 are stacked so as to form a layer.

Next, the manufacturing method of the retreaded tire produced by integrating the precure tread 1A-1C and the base tire 11 is demonstrated.
First, unvulcanized cushion rubber for bonding the base tire 11 and the precure tread 1 is disposed on the buff surface 12 of the base tire 11 along the tire circumferential direction. The first precure tread 1A is stuck on the cushion rubber so as to be placed thereon.
Next, unvulcanized filling rubbers 9a and 9b are arranged on the front end face 21 and the rear end face 22 of the first precured tread 1A, and the first precured tread is inserted through the filling rubber 9b. The rear end surface 22 of 1A and the front end surface 23 of the second pre-cured tread 1B are brought into contact with each other as much as possible, and the second pre-cured tread 1B is attached to the buff surface 12 via a cushion rubber. wear.
Next, an unvulcanized hole filling rubber 9c is arranged on the rear end face 24 of the second precure tread 1B, and the rear end face 24 of the second precure tread 1B is placed through the hole filling rubber 9c. 3 sheets of pre-cured treads 1C are brought into contact with the front end face 25 of the third pre-cured tread 1C as closely as possible, and the third pre-cured tread 1C is affixed to the buff surface 12 via a cushion rubber. The rear end surface 26 of the eye precure tread 1C and the front end surface 21 of the first precure tread 1A are in close contact with each other via the hole filling rubber 9a.
Thereby, the buff surface 12 of the base tire 11 is covered with the three precure treads 1A to 1C, and an unvulcanized retreaded tire is molded. Since this unvulcanized retreaded tire only needs to place the precure treads 1A to 1C on the buff surface 12 of the base tire 11, the pasting operation of the precure tread 1 is facilitated.

Next, the entire unvulcanized retreaded tire is covered with an envelope made of a rubber material, and a stepped annular member called a bead ring is fitted into the inner diameter portion of the envelope and the inner diameter portion of the unvulcanized retreaded tire. The surface of the unvulcanized retreaded tire is sealed with an envelope.
After that, the coated retread tire material is put into a vulcanizing can, and the inside of the vulcanizing can is pressurized and heated to vulcanize the unvulcanized cushion rubber and the hole filling rubber. Thus, a retread tire in which the precure treads 1A to 1C are firmly bonded to 11 is completed.

  The retread tire manufactured in this way is vulcanized and bonded to the tire tread surface 3 and the affixing surface 2 of the precure tread 1 in a state where there is no strain due to tension as in the prior art. That is, since no tensile force is generated between the base portion 6a of the tread block 6 and the groove surface 5 on the tire tread surface 3, distortion due to an internal tension does not occur. Since no compressive force is generated between the two, the pre-cure tread 1 is firmly bonded to the base tire 11 and prevents peeling from the base tire 11 by preventing distortion due to inherent compression. it can.

  According to the pre-cured tread 1 according to this configuration, the pre-cured tread 1 is simply placed on the buff surface 12 of the base tire 11 on which the pasting surface 2 is molded. It is not necessary to stick the cure tread 1 to the buff surface 12 while pulling, and there is no distortion caused by pulling on the tire tread 3 side. Thereby, when using a retreaded tire, it can suppress that the crack which arises in the base 6a of the tread block 6, and the precure tread 1 peel from the base tire 11. FIG.

  In the above description, a method for manufacturing a retread tire for agricultural machinery tires has been described. However, when a retread tire for aircraft tires and construction vehicle tires is manufactured, the precure tread 1 molded to have the above-described configuration is used. May be.

Further, the affixing surface 2 of the precure tread 1 has the same shape as the buff line curve B1 set when cutting the tread portion of the used tire in the cross section in the width direction A1, and the tyre 11 in the radial direction A2. Although it was formed so as to coincide with the radius R1 consisting of the distance from the tire rotation center C to the buff surface 12, not limited to this, only the width direction A1 has the same shape as the buff line curve B1, and from the tire rotation center C The radius of curvature may be set so as to be slightly larger or slightly smaller than the distance to the buff surface 12 and be curved three-dimensionally.
In this way, by performing vulcanization molding, a rehabilitated tire may be manufactured by appropriately attaching a necessary number of tires even when the tire sizes are different.

1; 1A; 1B; 1C Pre-cured tread, 2 affixing surface, 3 tire tread,
5 groove surface, 6 tread block, 7 ground contact surface, 11 tires, 12 buff surface,
A1 width direction, A2 radial direction, B1 buff line curve.

Claims (6)

A pre-cured tread that is formed to a predetermined length shorter than the outer peripheral length of the surface of the base tire, is placed on the surface of the base tire and is attached to the surface of the base tire,
A pre-cured tread having a shape of a pasting surface before being affixed to the surface of the base tire is formed into a shape that is curved along a curved shape in a width direction and a radial direction of the surface of the base tire.   2. The precure tread according to claim 1, wherein a surface to which the precure tread is applied is substantially the same as a shape in a width direction and a radial direction of the surface of the base tire.   The precure tread according to claim 1 or 2, wherein a tread surface of the precure tread is substantially the same as a shape of an original product tire to be a base tire.   A method for producing a retread tire, comprising a step of combining a plurality of the precure treads according to any one of claims 1 to 3 on the surface of the pedestal tire and applying the prepreg tread over the circumference of the surface of the pedestal tire. A retread tire characterized in that a plurality of the precure treads according to any one of claims 1 to 3 are combined on the surface of the base tire and pasted over one turn of the surface of the base tire.   The retread tire according to claim 5, wherein the retread tire is used for agricultural machinery, aircraft, or construction vehicles.

Images