JPH09183170A - Preparation of regenerated tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of peeling-off and to suppress generation of interfacial peeling-off in the market by ensuring adhesive force in the width direction of a tread. SOLUTION: In the outermost layer belt ply part 5, the first intersecting angle θ1 formed by buff tooth 7, namely buff direction to the direction of the cord 501 of the outermost layer belt ply 50 (the cord angle is r1 ) is formed to be θ1 =90±10 degree, more pref. θ1 =90±5 degree and the second intersecting angle θ2 formed by buff tooth 8 to the direction of the cords 5111 and 5121 of protruded parts 511 and 512 of the second belt ply 51 (the cord angle is r2 ) is formed to be θ2 =90±10 degree, more pref. θ2 =90±5 degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a retreaded tire in which the tread rubber of the tire is replaced to restore its function so that the tire can be reused.

[0002]

2. Description of the Related Art Conventionally, when the tire tread is completely worn, the wear does not reach the carcass, and the carcass is slightly damaged or not damaged at all, the residual tread rubber is removed to obtain a new one. Tread rubber is attached to restore the tire function as a retreaded tire. In a normal retread tire manufacturing method, a special knife-shaped cutting jig (peeling knife) attached to a turret that holds a grinder is used to roughly remove the residual tread rubber of a base tire (tire to be rehabilitated). After cutting (peeling), the tread cutting surface is ground with high accuracy using a buffing jig (rasp) which is a tire grinding tool formed of a thin plate material (see, for example, JP-A-1-164565). By applying buffing), the outer diameter of the cutting surface is accurately formed, and the cutting surface is roughened to improve the adhesiveness (rubber glue etc.) and then the adhesive is applied to the tread cutting surface. Then, the tread rubber is pasted and molded and then vulcanized.

As an example, the peeling process and the buffing process disclosed in JP-A-2-204024 will be described.
In FIG. 5, with respect to the tread b of the base tire a, the peeling knife c is fixed, and the rasp d is rotated while moving along loci e and f traversing the tread b in the width direction.
The base tire a is rotated, and the cutting process with the peeling knife c is performed first, and then the grinding process with the rasp d is performed. When the peeling knife c and the rasp d move along the loci e and f, a template (buffing jig) formed in an accurate shape is used to provide a roller that follows the shape of the template.
And the rasp d are often connected.

An example of peeling and buffing will be described below. Peeling knife Rasp Outer diameter 96mm 228.6mm Jig rotation speed ━━━━━ 3,400rpm Tire rotation speed 94rpm 94rpm Processing surface roughness No unevenness Unevenness 1mm

[0005]

However, in the above-mentioned conventional tread grinding method for retreaded tires, as shown in FIG. 6, the cord direction of the top breaker g located at the outermost layer in the radial direction of the base tire is the tire equator. The inclination angle α = 16 to 24 degrees with respect to the surface, and the processing direction of the buffing indicated by the buff eye h is the inclination angle β = 5 to the tread width direction.
At 10 degrees, the tires are formed substantially symmetrically with respect to the tire equatorial plane r, and the adhesive force in the tread width direction is along the buff eye h, so sufficient adhesive force can be obtained in the tire circumferential direction. However, there is a problem in that it is insufficient in the tread width direction and easily peels off. Further, there is a problem that tires having a relatively small diameter have variations, and that the pressure applied to the bonding surface of the new red rubber is insufficient, the suppression during vulcanization is weak, and interface peeling easily occurs in the market.

An object of the present invention is to provide a method for manufacturing a retreaded tire which can secure the adhesive force in the tread width direction to suppress the occurrence of peeling and suppress the occurrence of interfacial peeling in the market. .

[0007]

In order to achieve the above object, a method for manufacturing a retreaded tire according to the present invention has two or more layers of belt plies in which a large number of cords are arranged in parallel between a tread rubber and a carcass of a tread portion. In a method for manufacturing a retreaded tire, a tread rubber of a base tire is removed to form a tread rubber-removed surface, the tread rubber-removed surface is buffed to form a buff surface, and the buff surface is vulcanized or unvulcanized. A method for vulcanizing after applying a vulcanized tread rubber, wherein the buffing direction of the buffing, that is, the direction of the buffing is 90 with respect to the cord direction of the outermost layer belt ply portion located on the outermost side in the tire radial direction. By setting it to ± 10 degrees, when peeling occurs in the buff direction, the peeling is divided every time the collision occurs due to the rigidity of the cords arranged substantially orthogonal to the buff direction in parallel,
The peeling in the buff direction, that is, the peeling in the tread width direction can be suppressed, the adhesive force in the buff direction is increased, and the occurrence of the interface peeling in the market is suppressed. Further, since the cord of the belt ply is made of steel, the rigidity of the belt is increased and the effect of suppressing the peeling in the buff direction, that is, the peeling in the tread width direction is improved. Further, when the outermost layer belt ply portion is composed of the outermost layer belt ply and an overhanging portion protruding in the tread width direction from the outermost layer belt ply of the belt ply located inward of the outermost layer belt ply in the tire radial direction, By comparing the area of the outermost layer belt ply and the area of the overhanging portion and determining the direction of the buff stitch based on the cord direction having the larger proportion of the area of the buff surface, the buff processing can be simplified. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described with reference to the drawings.
In FIG. 2, the tread 2 formed on the tire radial direction outer periphery of the base tire 1 includes a tread rubber 4 and a carcass 6 that penetrates the tread 2 and the sidewalls and reaches the beads on both side edges in the tire radial direction. Belt plies of four layers in order from the outside to the inside, that is, the outermost belt ply.
A belt ply 50, a second belt ply 51, a third belt ply 52, and a fourth belt ply 53 are arranged.
The cords 1, 52, 53 are made of steel cord. The tread 2 is cut and removed by a predetermined amount, leaving a rubber layer that covers all of the belt plies 50, 51, 52, 53. If there is damage, repair the damaged part and buff the outer surface of the rubber layer. A buffed surface 3 is formed, an adhesive such as a rubber paste is applied to the buffed surface 3, a vulcanized or unvulcanized new tread rubber 4 is attached, and then vulcanized to be a retreaded tire. And

As in the present embodiment (see FIG. 2), when the second belt ply 51 disposed inside the outermost layer belt ply 50 next to the outermost layer belt ply 50 is larger than the outermost layer belt ply 50, it is the outermost layer belt ply. The portion 5 includes overhang portions 511 and 512 in which the outermost layer belt ply 50 and the second belt ply 51 extend outward from the outermost layer belt ply 50 in the tread width direction. Further, when a part of the belt ply is removed at the time of repair, among the remaining belt plies, the belt ply portion located furthest in the tire radial direction is set as the outermost layer belt ply portion. Further, in this embodiment, the belt ply has four layers, but any tire having two or more layers may be used.

In the buff processing, as shown in FIG.
When forming the buff surface 3, in the outermost layer belt ply portion 5, the first intersecting angle θ ₁ formed by the buff eye 7 or the direction of the buff with respect to the direction of the cord 501 (cord angle γ ₁ ) of the outermost layer belt ply 50. Is formed at θ ₁ = 90 ± 10 degrees, and more preferably at θ ₁ = 90 ± 5 degrees, with respect to the directions of the cords 5111 and 5121 of the overhanging portions 511 and 512 of the second belt ply 51 (cord angle γ ₂ ). The second crossing angle θ ₂ formed by the buff eye 8 is θ
₂ = 90 ± 10 degrees, more preferably θ ₂ = 90 ± 5 degrees.

With this structure, when peeling in the buff direction occurs, the rigidity of the cords of the belt ply arranged substantially perpendicular to the buff direction causes the rigidity difference between the cord of the belt ply and the rubber layer. The peeling is divided every time, and the peeling in the buff direction, that is, the peeling in the tread width direction can be suppressed, the adhesive force in the buff direction is increased, and the occurrence of the interface peeling in the market is suppressed.

Even if it is not the full width of the tread 2, the intersection angle θ with respect to the cord direction of the outermost belt ply portion 5 of the buffs 7, 8 is 80% or more of the full width of the tread 2 around the tire equatorial plane. ₁ and θ ₂ are 90 ± 10
It is also possible to set the degree (more preferably 90 ± 5 degrees). Further, the thickness of the residual rubber layer remaining outside the outermost belt ply portion 5 after the buffing in the tire radial direction is 1.
It should be 0-4.5 mm. If the thickness of the residual rubber layer after buffing is less than 1.0 mm, it is practically impossible to regenerate,
If it exceeds 4.5 mm, the effect of strengthening the adhesive force due to the cord rigidity of the outermost belt ply portion 5 is deteriorated.

In the above embodiment, the cord directions of the outermost belt ply 50 and the overhanging portions 511 and 512 of the second belt ply 51 are different (cord angle γ ₁ ≠ γ ₂ ). The directions are equal (code angle γ ₁ =
In the case of γ ₂ ), the first intersecting angle θ ₁ and the second intersecting angle θ ₂ are equal (θ ₁ = θ ₂ ), the buffs 7 and 8 are the same, that is, the buffing direction is the same in the entire buffing surface 3. Direction.

Further, in the above embodiment, the outermost belt ply 50 and the overhanging portions 511 and 512 of the second belt ply 51.
And the cord direction is different (cord angle γ ₁ ≠ γ ₂ ), the outermost belt ply 50 and the second belt ply 51
The bulging portions 511 and 512 of the outermost belt ply 50 and the second belt ply 51 of the outermost belt ply 50 and the second belt ply 51 have different crossing angles (θ ₁ ≠ θ ₂ ). ， 512
In the case where the cord directions are different in and, the area of the outermost belt ply 50 is compared with the areas of the overhang portions 511 and 512,
It is also possible to determine the direction of the buff eye based on the code direction having the larger proportion in the area of the buff surface 3.

Further, in the tire in which the boundary between the buff surface 3 and the tread rubber 4 at the shoulder portion of the tire is likely to be damaged, the overhanging portion 511 of the second belt ply 51,
The direction of the buffs is determined based on the 512 cord direction, and in the tire where the boundary between the buff surface 3 and the tread rubber 4 on the crown portion of the tread 2 is likely to be damaged, the outermost belt ply 50 It is also possible to determine the direction of the buff eye based on the chord direction.

[0016]

〔belt〕

Number of sheets: 4 pieces Material: Steel Each belt ply Angle code composition Width Outermost layer belt ply (50) -20 degrees Two-layer twist 80mm Second belt ply (51) -20 degrees Two-layer twist 170mm Third belt ply (52) +20 2 layer twist 181mm 4th belt ply (53) +55 degree 2 layer twist 165mm The above angle is the angle from the tire equatorial plane, and
Indicates a clockwise direction from the tire equatorial plane, and − represents a counterclockwise direction from the tire equatorial plane. The numbers in parentheses are the reference numerals in FIG.

The tread rubber removing process will be described. Rasp peeling knife Outer diameter 228.6mm 96mm Rotation speed 3400 rpm Not rotated Tire rotation speed 94 rpm 94 rpm Grinding surface condition 1 mm unevenness No unevenness (3-4 mm higher than the buff surface) Next, glue with adhesive The adhesive force of the attached tread rubber shall be 80 N / 25 mm or more (JIS K6329).
Incidentally, in the measurement of the adhesive force, the sample in the circumferential direction is cut into a rectangle extending in the tire equatorial plane including the tire equatorial plane, and the sample in the tread width direction is cut into a rectangle extending perpendicular to the tire equatorial plane. , JIS K630
Perform the test method according to 1 to 7.

Table 1 in FIG. 3 shows the results of experiments conducted on a conventional tire having a conventional structure, an example tire to which the present invention is applied, and a comparative tire having a structure different from the present invention.
In the conventional example, the cord angle γ of the outermost belt portion is γ = −20.
The degree and the buff angle δ are substantially symmetrical about the tire equatorial plane,
Δ = ± 5 degrees with respect to the tread width direction plane including the rotation axis,
That is, the intersection angle γ between the cord of the outermost belt and the buff
However, one side is 65 degrees and the other is 75 degrees, and the tire outer circumference of the buff role is 3185 mm. Here, the buff angle δ is positive in the clockwise direction and negative in the counterclockwise direction with respect to the tread width direction plane including the rotation axis when viewed from the outside in the tire radial direction.

The first embodiment is substantially the same as the second conventional example,
The buff direction is the same for the entire outermost belt (γ ₁ = γ
₂ = δ), the buff angle δ = −20 degrees, the intersection angle is uniform throughout (θ ₁ = θ ₂ = θ), and the intersection angle θ = 90 degrees. The second embodiment is substantially the same as the first embodiment except that the buff angle δ = −15 degrees and the intersection angle θ = 85 degrees. Example 3
Is almost the same as that of the first embodiment, but the buff angle δ = −10 degrees and the intersection angle θ = 80 degrees. Example 4 is the same as Example 1.
However, the buff angle δ = −25 degrees and the intersection angle θ = 85 degrees. The fifth embodiment is substantially the same as the first embodiment except that the buff angle δ = −30 degrees and the intersection angle θ = 80 degrees. Comparative Example 1 is substantially the same as Example 1, but the buff angle δ = −5 degrees and the intersection angle θ = 75 degrees. Comparative Example 2
Is almost the same as that in the first embodiment, but the buff angle δ = −35 degrees and the intersection angle γ = 75 degrees.

From the results shown in Table 1, the adhesive strength in the width direction of the tread is clearly increased in all the examples as compared with the conventional example and the comparative example, and 50% in the example 1 based on the conventional example (260 N / 25 mm). (130 N / 25 mm) increase, Example 2 is 38
% (100 N / 25 mm), Example 3 is 23% (60 N / 25 mm)
25 mm), Example 4 increased 46% (120 N / 25 mm), Example 5 increased 35% (90 N / 25 mm),
In all of the examples, the number of cords causing interfacial peeling is 0. The number of codes that caused interface peeling was m
It is the result of inspecting the presence / absence of interfacial peeling with 10 lines.

On the other hand, the adhesive force in the circumferential direction of the tire was slightly reduced. Based on the conventional example (470 N / 25 mm), Example 1 reduced by 4% (20 N / 25 mm) and Example 2 decreased by 2% (10 N / 2).
5 mm), Example 3 is 2% (10 N / 25 mm) reduction, Example 4 is 6% (30 N / 25 mm) reduction, and Example 5 is 6%.
(30 N / 25 mm), but the number of cords causing interfacial peeling is 0 in all the examples, and there is no possibility of causing a substantial problem.

Further, in the conventional example and the first embodiment, after the tread is worn and the wear indicator is used in an actual vehicle until it is grounded, it is disassembled to remove the interfacial peeling of the cord of the grounding portion (sample number n = 20). As a result of inspecting the presence / absence, in the conventional example, two interfaces were peeled off (2/20), whereas in the example, 0 (0/20).

FIG. 4 shows the results of inspecting the change in the adhesive force in the tread width direction due to the change with time after the buffing in the conventional example and the example 1. From the results shown in FIG. 4, it can be seen that the tire of Example 1 always has a higher adhesive force in the tread width direction than that of the conventional example, and that the change over time is small.

[0024]

Since the present invention is configured as described above, the following effects can be obtained. The buffing of the buffing process, that is, the direction of the buffing is set to 90 ± 10 degrees with respect to the cord direction of the outermost layer belt ply portion located on the outermost side in the tire radial direction, so that when buffing peeling occurs, Because of the rigidity of the cords that are arranged substantially orthogonal to each other, the peeling is divided each time the difference in rigidity is collided, and the occurrence of peeling in the buff direction, that is, peeling in the tread width direction can be suppressed,
The adhesive strength in the buff direction is increased and the occurrence of interfacial peeling in the market is suppressed. Further, since the cord of the belt ply is made of steel, the rigidity of the belt is increased and the effect of suppressing the peeling in the buff direction, that is, the peeling in the tread width direction is improved. Also, the outermost belt ply part is
When the outermost belt ply and the overhanging portion of the belt ply located inward of the outermost belt ply in the tire radial direction project from the outermost belt ply in the tread width direction, the area and the overhang of the outermost belt ply are extended. The buff processing can be simplified by comparing the areas of the parts and determining the direction of the buff eye based on the code direction having the larger proportion in the area of the buff surface. Further, the rehabilitation property of the small-diameter tire is improved, and it is possible to prevent the decrease in the adhesive force due to the change with time after the buff treatment.

[Brief description of the drawings]

FIG. 1 is a development view of a tread portion after buffing showing an embodiment of the present invention.

FIG. 2 is a sectional view of a tire to which the present invention is applied.

FIG. 3 is Table 1 showing the results of comparative tests.

FIG. 4 is a graph showing changes with time after buffing.

FIG. 5 is an explanatory diagram of cutting and buffing.

FIG. 6 is a development view of a tread portion after a conventional buffing process.

[Explanation of symbols]

1 tire, 2 tread, 3 buff surface, 4 (sticking) tread rubber 5 outermost belt ply part, 50 outermost belt ply 51 second belt ply 52, third belt ply 53
4th belt ply 511, 512 Overhang part

Claims (3)

[Claims] 1. A method for manufacturing a retreaded tire having two or more layers of belt plies in which a large number of cords are arranged in parallel between a tread rubber of a tread portion and a carcass, and a tread rubber-removed surface is removed by removing the tread rubber of a base tire. Forming a buff surface by buffing the tread rubber-removed surface, adhering a vulcanized or unvulcanized tread rubber to the buff surface, and then vulcanizing the buff surface. A method for producing a retreaded tire, characterized in that the buff pattern, that is, the direction of the buff, is set to 90 ± 10 degrees with respect to the cord direction of the outermost layer belt ply portion. 2. The method for producing a retreaded tire according to claim 1, wherein the cord of the belt ply is made of steel. 3. The outermost layer belt ply portion is composed of the outermost layer belt ply and an overhanging portion of the belt ply located inward of the outermost layer belt ply in the tire radial direction and projecting in the tread width direction from the outermost layer belt ply. In this case, the area of the outermost belt ply is compared with the area of the overhanging portion, and the direction of the buff is determined based on the cord direction having the larger proportion of the area of the buff surface.
Alternatively, the method for producing a retreaded tire according to item 2.