JPH09164606A - Retreading of solid tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce radial run-out(RRO) without damaging productivity and durability. SOLUTION: Filling tread rubber is attached to the tread buff surface of a tire substrate 7 having the tread buff surface formed by buffing an abraded tread surface 5 and the whole is vulcanized and molded in a vulcanizing mold to retread a solid tire. The tread buff surface consists of a central surface 9 extending almost in parallel to the axial direction of the tire at the central part in the axial direction of the tire in the meridian cross section of the tire and the inclined surfaces 10, 10 going toward the side surface of the tire substrate 7 from both edges of the central surface 9 and obliquely extending in a radius direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rehabilitating a solid tire capable of reducing the radial runout (RRO) of a completed solid tire without lowering productivity and suppressing abnormal vibration of a vehicle.

[0002]

2. Description of the Related Art So-called pneumatic type solid solid tires mounted on forklift trucks used for transportation in factories, warehouses, construction sites and the like are used tires whose worn tread surface is Since the disposal method is solid, it is difficult. Therefore, the worn tread surface may be buffed to additionally attach a supplementary tread rubber, and the vulcanization mold may be vulcanized and reused.

Regarding rehabilitation of this solid tire, Japanese Unexamined Patent Publication No. 3-288631 discloses a tread buff surface tb which is flat in a tire meridional section and is substantially parallel to the tire axial direction by buffing a worn tread surface as shown in FIG.
1 shows a method of obtaining a retreaded solid tire by forming a tire base body a1 having No. 1 and further adhering a raw rubber sheet b to the flat tread buff surface tb1 and vulcanizing it.

Further, Japanese Patent Laid-Open Nos. 5-31822 and 6-1994
Japanese Laid-Open Patent Publication No. 79808 proposes to form a tire base body a2 having a substantially circular tread buff surface tb2 curved in an arc shape outward in the radial direction by buffing as shown in FIG.

Such a flat tread buff surface tb
1, or when vulcanizing the raw rubber on the tread buff surface tb2 having a substantially circular shape, the raw rubber is attached in an amount more than necessary in order to obtain a good finished tire having no rubber deficiency or the like. a2 receives a compressive force from the raw rubber portion (complementary tread rubber) during vulcanization.

[0006]

However, in the method of rehabilitating a solid tire from the tire base body a1 having the flat tread buff surface tb1, the center portion of the flat tread buff surface tb1 in the tire axial direction is radially inwardly compressed by the compression force. While it is easily deformed in one direction, it has been found that the outer side portion of the tread buff surface tb1 in the axial direction of the tire is not deformed inward in the radial direction as much as the central portion by contacting the vulcanization mold. As a result, the deformation due to vulcanization of the tread buff surface tb1 becomes larger in the central portion than in the outer portion, and the absolute value of the deformation amount of the central portion tends to increase due to the concentration of the compressive force.

This does not change even when the raw rubber is attached to the sidewall surface of the tire base body a1. Because, the outer portion of the tread buff surface tb1 is suppressed from being deformed inward in the radial direction by the compression force inward in the tire axial direction applied from the vulcanization mold through the raw rubber on the sidewall surface, and thus the tread buff surface tb1 is prevented from being deformed. This is because the deformation does not occur as much as the central portion.

The amount of deformation of the central portion of the tread buff surface tb1 varies in the tire circumferential direction due to the variation of the filled tread rubber to be pasted and the variation of the mounting position of the tire base body a1 on the vulcanization mold, and the completed solid body. In the tire, increase the radial runout (RRO),
This causes abnormal vibrations of the vehicle and reduces ride quality.

On the other hand, in the method of rehabilitating the solid tire from the tire base body a2 having the substantially circular tread buff surface tb2, the filled tread rubber flows to the outer side portion in the tire axial direction during vulcanization along the tread buff surface tb2 having the arc-shaped cross section. Therefore, the amount of deformation inward in the radial direction due to the compressive force in the central portion of the tread buff surface tb2 becomes small, and the variation in the amount of deformation in the tire circumferential direction can also be reduced and RRO can be reduced, but the tread buff surface tb2 is in the tire meridional section. Since it is a curved surface that is an arc, the buffing process becomes complicated and productivity decreases, and the buffing device becomes large and complicated,
This results in an increase in cost.

According to the present invention, the tread buff surface extends in the center portion in the tire axial direction substantially in parallel to the tire axial direction, and is slanted radially inward from both edges of the center surface toward the side surface of the tire base body. Provided is a solid tire rehabilitation method, which is basically formed from a sloping inclined surface, does not reduce productivity by facilitating a buffing process, and can reduce RRO of a completed solid tire. Has an aim.

[0011]

According to the present invention, an unvulcanized or semi-vulcanized supplementary tread rubber is attached to the tread buff surface of a tire base having a tread buff surface obtained by buffing a worn tread surface, and vulcanization is performed. A method of rehabilitating a solid tire by vulcanization molding in a mold to rehabilitate a solid tire,
In the meridional section of the tire, the tread buff surface extends inward in the radial direction from both edges of the central surface, which extends substantially parallel to the tire axial direction at the central portion in the tire axial direction, toward the side surface of the tire base body. It consists of an inclined surface.

As described above, according to the present invention, the tread buff surface to which the supplementary tread rubber is attached is a central surface extending substantially parallel to the tire axial direction at the central portion in the tire axial direction, and both sides thereof are directed to the side surface of the tire base body. Since it is formed from a sloped surface that extends diagonally inward in the radial direction, the filled tread rubber will flow outward in the tire axial direction along the sloped surface during vulcanization, and radially inward of the central surface. The amount of deformation of the tire can be reduced, the variation in the tire circumferential direction can be reduced, the RRO of the completed solid tire can be reduced, abnormal vibration of the vehicle can be suppressed, and riding comfort performance and the like can be improved.

Further, since the central surface extends substantially parallel to the tire axial direction and has a substantially straight line in the tire meridional section, the buffing process can be facilitated, productivity can be prevented from being reduced, and the buffing device can be downsized. , Can be simplified,
The cost can be reduced.

Further, solid tires generally have the property that heat is likely to be accumulated in the center of the tire and damage is likely to occur as they approach the center of the tire. However, the center plane is a plane substantially parallel to the tire axial direction. Since it is configured, it is possible to easily attach the filling tread rubber to this center surface, avoiding the accumulation of air between the center surface and the filling tread rubber, and as a result of obtaining a good adhesive force, it is possible to generate heat in the tire central portion. It can prevent peeling and improve durability.

According to the invention of claim 2, the supplementary tread rubber is molded into a thick-walled cylindrical shape on the outer periphery of the central surface,
Moreover, before pressing with the vulcanizing mold, a gap is to be formed between the inclined surface and the vulcanizing mold, so that it can be firmly adhered to the outer periphery of the central portion without causing air accumulation or the like. The filled tread rubber can be attached, and the adhesive force can be further enhanced, and at the time of vulcanization, the filled tread rubber can reliably flow outward in the tire axial direction along the inclined surface, and can be radially inward. The compressive force to the
It is possible to prevent the uneven deformation amount of the central surface, reduce the variation in the deformation amount in the tire circumferential direction, and further enhance the RRO reduction effect.

Further, according to the invention of claim 3, the width CW of the central surface in the tire axial direction is set to 1/4 or more and 3/4 or less of the total width TW of the tread buff surface in the tire axial direction. It is possible to reduce RRO while increasing the adhesive force with the tread rubber. If the ratio CW / TW is less than 1/4, the width CW of the center plane that extends substantially parallel to the tire axial direction will be too small, and it will be difficult to obtain a good adhesive force with the filled tread rubber, making it durable. While it can cause a decrease in sex,
When it exceeds 3/4, the width of the inclined surface in the tire axial direction becomes too small, and it becomes difficult to effectively flow the filled tread rubber along the inclined surface outward in the tire axial direction. In some cases, the amount of deformation inward in the direction becomes large and the RRO of the completed solid tire cannot be sufficiently reduced.

In the third aspect, the inclined surface is a straight line inclined at an angle of 5 ° or more and 30 ° or less with respect to the tire axial direction, and further, RRO is reduced, durability is improved, and productivity is improved. Is being secured. When the angle is less than 5 °, it becomes difficult to cause the filled tread rubber to flow along the inclined surface, and RRO cannot be sufficiently reduced. On the contrary, when it exceeds 30 °, the filled tread rubber and the inclined surface are separated from each other. Air accumulation is likely to occur and durability may be reduced. Further, since the inclined surface is linear, it is possible to prevent the buffing process from becoming complicated when the curved surface is formed, which can improve productivity and also contribute to simplification of the buffing device, which contributes to cost reduction.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows a new solid tire 1
FIG. 1 is a meridian cross-sectional view showing an example of A, in which a solid tire 1A has a bead portion 2 located on the innermost side in the radial direction.
Base rubber layer 15 forming a bead bottom surface 2A and a bead side surface 2B, 2B of the bead portion 2 extending radially outward from both edges of the bead bottom surface 2A, located on the outer side in the radial direction and from the bead side surface 2B. The intermediate rubber layer 16 forming the sidewall side surface 3A of the sidewall portion 3 extending outward in the radial direction, and the outer ends of the buttress surfaces 14, 14 located on the outer side in the radial direction and extending from the sidewall side surfaces 3A, 3A. It has a pneumatic tire outer surface having a tread rubber layer 17 that forms a tread surface 4A of the tread portion 4 to be joined.

Both edges of the boundary surface between the intermediate rubber layer 16 and the tread rubber layer 17 parallel to the tire axial direction are provided continuously to the sidewall side surface 3A and the buttress surface 14 and extend in the radial direction. Located on surface 19.

The base rubber layer 15 has enhanced rim slip resistance by using a reinforcing rubber having a high compression elastic modulus reinforced with a short fiber cord or a hard rubber, and the intermediate rubber layer 16 and the tread rubber. Layer 17, J
Using a rubber having an ISA hardness of, for example, 50 to 70 degrees and having excellent wear resistance, crack resistance, and grip properties, for example, a diene rubber such as natural rubber, isoprene rubber, or styrene-butadiene rubber. A so-called tread rubber compound containing a predetermined amount of carbon is used.

In such a solid tire 1A, the tread surface 4A is worn with use and becomes a used solid tire 1B as shown by a chain line in FIG. 2, for example. To obtain a solid tire 1 (shown in FIG. 6).

To this end, first, the rubber of the worn tread surface 5 of the used solid tire 1B is removed by reducing the height of the buttress surface 14 and removed by buffing, whereby a tire base body having a tread buff surface 6 is formed. Form 7.

As shown in FIG. 2, the tread buff surface 6 is symmetrical with respect to the tire equator C, and has a straight cross-section center which extends substantially parallel to the tire axial direction at the central portion in the tire axial direction. The surface 9 and the side surfaces of the tire base body 7 from both edges of the central surface 9, the vertical surfaces 19 and 1 in the present embodiment.
It is composed of inclined surfaces 10 and 10 each having a linear cross section and extending inward in the radial direction toward a height position corresponding to 9.

Thus, the central surface 9 and the inclined surfaces 10 and 1
Since the tread buff surface 6 composed of 0 is formed, the buffing process can be facilitated and productivity can be improved as compared with a tread buff surface having an arc cross section, and in this embodiment, the outer edge of the inclined surface 10 in the tire axial direction is the vertical surface. Since it is located at 19, the height position of the outer edge can be easily set, and the buffing workability can be further improved.

The width CW of the central surface 9 in the axial direction of the tire
Is 1/4 of the total width TW of the tread buff surface 6 in the tire axial direction.
It is set to 3/4 times, and the inclined surface 10 is inclined at an angle α of 5 to 30 degrees with respect to the tire axial direction.

In the present embodiment, the tire base body 7 is substantially parallel to the tire axial direction by buffing the bead bottom surface 2A, bead side surfaces 2B, 2B, and sidewall side surfaces 3A, 3A of the used solid tire 1B. It has a bead bottom buff surface 20, a bead side buff surface 21, 21, and a sidewall side buff surface 22, 22.

On the tread buff surface 6 of such a tire base 7, an unvulcanized or semi-vulcanized supplemented tread rubber 11 is provided.
In the present embodiment, as shown in FIG. 3, a sheet-shaped raw rubber sheet 24 using a rubber composition containing a tread rubber is attached to the outside of the inclined surfaces 10 and 10 in the axial direction of the tire. By winding around the tread buff surface 6 with 10A and 10A left, a thick cylindrical supplementary tread rubber 11 is formed on the outer periphery of the central surface 9.

Therefore, when the tire base 7 molded with the supplemented tread rubber 11 is loaded into the vulcanizing mold, the unattached portion 10A of the inclined surface 10 and the vulcanizing mold are pressed before the pressing by the vulcanizing mold. A void 12 can be formed between them, and the vulcanization allows the supplementary tread rubber 11 to flow outward in the tire axial direction along the unattached portion 10A of the inclined surface 10, and compression at the central portion in the tire axial direction is possible. It is possible to prevent the center surface 9 from being excessively deformed inward in the radial direction by a force, reduce variations in the amount of deformation in the tire circumferential direction, and reduce RRO.

Further, since the central surface 9 forms a straight line substantially parallel to the axial direction of the tire, the raw rubber sheet 24 can be attached to the outer periphery of the central surface 9 with good quality without leaving air, and the adhesive force is increased to improve durability. Can improve the sex.

As shown in FIG. 4, the raw rubber sheet 24 is not attached to the inclined surface 10 at all, and the supplementary tread rubber 11 is formed only on the outer periphery of the central surface 9 into a thick-walled cylindrical shape.
It is also possible to form a rubber flow gap 12 between 0 and the vulcanization mold.

Further, as shown in FIG. 5, the raw rubber sheet 2 extends over the entire width of the tread buff surface 6 including the inclined surfaces 10 and 10.
4 can be attached. Even in this case, the extra pressure generated by the supplementary tread rubber 11 during vulcanization causes the inclined surface 1
0 and 10 are distributed to both sides in the axial direction of the tire, the amount of deformation of the central surface 9 inward in the radial direction can be reduced, and the variation in the tire circumferential direction is also reduced, thereby reducing the RRO of the completed solid tire 1. it can.

Further, a sheet-shaped raw rubber sheet 26 made of the above-mentioned reinforcing rubber or hard rubber is wound around and attached to the bead bottom buff surface 20 to form a supplementary bead rubber 27, and the bead side buff surface 20. A similar raw rubber sheet 26A is rolled up and adhered to 21, 21 as well.

Therefore, the grounding of the bead portion 2 of the retreaded solid tire 1 (shown in FIG. 6) after vulcanization molding to the rim wheel and the flange can be stabilized, the rim slip resistance can be secured, and the cross section can be ensured. Since the raw rubber sheet 26 is attached to the linear bead bottom buff surface 20, the risk of air accumulation can be reduced and the adhesive strength can be increased.

Also, on the side wall side buff surface 22,
For example, a raw rubber sheet 30 made of a rubber composition having excellent weather resistance and cut resistance is abutted on the upper end of the raw rubber sheet 26A in the radial direction to enhance the side appearance of the solid tire 1, and The height position of the reinforcing rubber or the hard rubber around the base rubber layer 15 is stabilized.

[0035]

EXAMPLE A width CW in the tire axial direction of the central surface of the tread buff surface and a total width TW in the tire axial direction of the tread buff surface
And the value of the ratio CW / TW and the angle α of the inclined surface with respect to the tire axial direction are set to the values shown in Table 1, and a retreaded solid tire having a tire size of 7.00-12 is manufactured as a prototype (Example 1
6) and tested each performance. Incidentally, a solid tire rehabilitated from a tire substrate having a flat tread buff surface having no inclined surface (conventional example), and a solid tire rehabilitated from a tire substrate having a tread buff surface having a substantially V-shaped cross section without a central surface ( (Comparative example) was also prototyped,
The performance was compared. The test method is as follows.

(1) RRO (Radial Runout) Performance The test tire was mounted on a rim of 5.00 S to measure the RRO, and the results are shown in Table 1 by an index with the conventional example being 100. The larger the index, the smaller the RRO and the better the performance.

(2) Durability Performance Eight test tires were trial-produced, mounted on a forklift truck with a rim assembled, disassembled after traveling 5000 km, and examined for damage on the adhesive surface of the tread buff surface. Table 1 shows the results. Note that in Table 1, * 1 indicates that peeling occurred in the inclined surface of the adhesive surface in one of the eight,
In addition, * 2 indicates that peeling occurred in the center of the adhesive surface in 5 out of 8 pieces.

[0038]

[Table 1]

As a result of the test, it was confirmed that the example has an improved RRO performance as compared with the conventional example, and the durability is generally increased as compared with the comparative example.

[0040]

INDUSTRIAL APPLICABILITY As described above, the solid tire rehabilitation method according to the present invention can be applied to RR without lowering durability and productivity.
O can be reduced, and abnormal vibrations can be eliminated to improve riding comfort performance and the like.

[Brief description of the drawings]

FIG. 1 is a tire meridian cross-sectional view illustrating a new solid tire.

FIG. 2 is a tire meridian cross-sectional view showing an example of a tire base having a tread buff surface.

FIG. 3 is a meridian sectional view of the tire showing a state in which a supplementary tread rubber is attached to the tread buff surface of the tire base.

FIG. 4 is a cross-sectional view showing another embodiment.

FIG. 5 is a cross-sectional view showing still another embodiment.

FIG. 6 is a meridian sectional view showing a refurbished solid tire.

FIG. 7 is a cross-sectional view for explaining a conventional technique.

FIG. 8 is a cross-sectional view for explaining a conventional technique.

[Explanation of symbols]

 5 Worn tread surface 6 Tread buff surface 7 Tire base body 9 Center surface 10 Inclined surface 11 Complementary tread rubber 12 Void

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29K 105: 24 B29L 30:00

Claims (3)

[Claims] 1. A tread buff surface of a tire base having a tread buff surface obtained by buffing a worn tread surface,
An unvulcanized or semi-vulcanized supplemented tread rubber is affixed, which is a method for retreading a solid tire by vulcanization molding in a vulcanizing mold to rehabilitate a solid tire, wherein the tread buff surface is a tire meridional section, A solid comprising a central surface extending substantially parallel to the tire axial direction at an axial center portion and an inclined surface extending radially inward from both edges of the central surface toward the side surface of the tire base body. Tire rehabilitation method. 2. The supplementary tread rubber is molded into a thick-walled cylindrical shape on the outer periphery of the center surface, and before being pressed by a vulcanizing mold,
The method of rehabilitating a solid tire according to claim 1, wherein a gap is formed between the inclined surface and the vulcanization mold. 3. The width CW in the tire axial direction of the central surface is
1/4 to 3 of the total width TW of the tread buff surface in the tire axial direction
The solid tire rehabilitation method according to claim 1, wherein the inclined surface is a straight line that is inclined at an angle of 5 to 30 ° with respect to the tire axial direction.