JP3138404B2 - Method for manufacturing retreaded tires for trucks and buses - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing retread tires for trucks and buses which can provide retreaded tires having improved wear resistance and heat resistance as tires for trucks and buses.

[0002]

2. Description of the Related Art In the case of automobile tires, especially heavy duty tires such as trucks and buses, in order to reduce the cost of tires, tires which have been used due to wear of the tread are replaced with treads. So-called retreaded tires for reuse are increasing.

Conventionally, to retreaded tires, after lamination the Ritore' de member b of new tires and substantially homogeneous wear or damaged preparative tread portion has been removed base tire a 3, the base the tire a and Ritore' de member b vulcanization molding using a vulcanizing mold d, while adhering to each other, molding the tread portion such machining tread grooves e in litho <br/>Re' de member b A rehabilitation method based on a remolding method in which a remolding method is also performed has been used.

[0004]

However, in the molding method, as described above, the unvulcanized retort member b and the vulcanized base tire a are pasted and vulcanized again, so that this vulcanization is performed. There is a problem that the tire shape is easily deformed such as a change in the radius of curvature of the tread at the time of sulfuration or molding, and the reconditioned tire is inferior in wear resistance and heat resistance as compared with a new tire.

[0005] Incidentally, there are also so-called pre-cure method for fabricating the paste retreaded tire this Ritore' de member base tire with previously formed pattern Ritore' de member and subjected to vulcanization but track, the heavy duty tire such as bus With such a precure method, it is difficult to ensure the dimensional accuracy of the retreaded tire, and the abrasion resistance,
There is a problem that heat resistance is poor.

[0006] The inventors of the present invention have focused on a buffing process in which a base tire has been buffed at random and a buffing surface has been formed on the base tire, and a buffing process between the buffing surface and the belt layer has been performed. By making the thickness of the remaining rubber layer different between the central region and the side region, and by regulating the total rubber thickness of the tread between the tread surface and the belt layer after vulcanization molding also in the central region and the side region The present inventors have found that the above problems can be solved even by a manufacturing method using a molding method, and have completed the present invention.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a retread tire for trucks and buses which can improve uneven wear resistance and heat resistance and improve durability in retread tires for trucks and buses.

[0008]

SUMMARY OF THE INVENTION The present invention is a method of manufacturing a retread tire for trucks and buses comprising a carcass of steel cords and a belt layer comprising a plurality of plies of steel cords. Buffing the tread portion of the tire, forming a tread buffing surface to form a buff remaining rubber layer between the belt layer and the base tire, a buffing step, the unvulcanized <br> on the tread buffing surface of the base tire />Ritore' de Ritore' de rubber molding process rubber is impregnated, and the base tire and Ritore' de the rubber in the vulcanization mold vulcanised vulcanization molding step for forming a tread pattern on the tread surface, with including, The buff remaining rubber layer has a center region C having a width of 0.75 times the tread width TW around the tire equator, and side regions S on both sides of the center region C in the tire axial direction. Oite, the thickness tc of the central region C 1.5
3.5 mm and the thickness ts of the side region S is 1.0 to 3.0.
mm and not more than the thickness tc of the central region,
The total thickness of the tread rubber between the tread surface and the belt layer after the vulcanization molding step is such that the total thickness Ts of the side region S is equal to or less than the total thickness Tc of the central region C, and A method for manufacturing a retread tire for a truck or bus, wherein the thickness is equal to or greater than a value obtained by subtracting 0.5 mm from a thickness Tc.

This manufacturing method can be suitably applied to truck and bus tires with tubes.

It is preferable that the difference between the clip width GW and the rim width LW of the mold is 3 mm or less.

[0011]

The thickness tc and ts of the buff-remaining rubber layer are regulated in the central region C and the side region S, respectively, and the total thickness of the tread rubber after vulcanization molding is made relative to the central region C and the side region S. It regulates dimensional differences. As a result, the cross-section in the tire axial direction of the retreaded tire, in particular, the shape of the tread surface can be accurately regulated, and the wear resistance and heat resistance can be improved, and the durability of the retreaded truck and bus tire can be increased.

[0012] The clip width when the following dimensional difference 3mm against the rim width can be more accurately retain the shape of the tread surface.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the manufacturing method of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the retreaded tire 1 for trucks and buses has a tread buffing surface obtained by removing a residual tread portion of a tubed pneumatic tire whose tread surface has been worn out and used by using a buff or the like. a base tire 3 with 2, consisting of litho <br/>Re' de rubber 4 which is adhered to the base tire 3.

The base tire 3 has a sidewall portion 1 extending inward in the tire radial direction from both ends of the tread portion 5.
3, 13 and the bead portion 14 located at the radially inner end of each sidewall portion 13.
A toroidal carcass 6 is suspended between the tread portion 5 and the tread portion 5 from the tread portion 5 through the sidewall portion 13, and both ends of the toroidal carcass 6 are folded back around the bead core 15 of the bead portion 14. And tread part 5
A tough belt layer 7 is wound inward in the circumferential direction to reinforce the tire and provide necessary rigidity.

In the present embodiment, the carcass 6 is composed of a single carcass ply.
It is formed as a radial or semi-radial array juxtaposed at an angle of ９０90 °.

In the present embodiment, the belt layer 7 is composed of three belt plies 7A, 7B and 7C.
In 7B and 7C, belt cords in which steel cords are arranged in parallel with an interval are arranged in a direction crossing each other between the belt plies.

The retret rubber 4 has a rubber composition of substantially the same quality as that of the tread portion 5 of the base tire 3, is attached to the base tire 3 in an unvulcanized state, and is subjected to vulcanization molding together with the base tire 3. A retreaded tire is formed.

Next, the manufacturing method will be described in the order of steps. In this example, (1) buffing step, (2) retread rubber molding step, and (3) vulcanization molding step are performed in this order.

The buffing step is a step of obtaining a base tire 3 having a tread buffing surface 2 formed by buffing a tread portion of a used tire.

The tread buffing surface 2 is provided on the belt layer 7
A rubber layer 9 is formed between the outermost surface of the belt ply 7C and the outermost surface of the belt ply 7C. The tread buffing surface 2 is formed on both sides of the tire equator CO with the same width as the widest belt ply 7B of the belt layer 7 or a width slightly larger than that, and from the end thereof to the buttress surface 13A. Cut-off surface 1 inclined inward in the radial direction toward
7, 17 are formed.

The buff remaining rubber layer 9 has a center region C having a width of 0.75 times the tread width TW centered on the tire equator CO, and two side regions adjacent to both sides of the center region C in the tire axial direction. And have different thicknesses.

The buff remaining rubber layer 9 has a thickness tc of 1.5 to 3.5 mm in the central region C, a thickness ts of 1.0 to 3.0 mm in the side region S, and has a thickness ts of 1.0 to 3.0 mm. The thickness is equal to or less than tc.

As described above, the thickness tc of the buff remaining rubber layer 9 is
By regulating ts, the shape of the tread surface 10 after vulcanization molding can be stabilized.

[0024] Ritore' de rubber 4, the outer peripheral surface 19 forming a tread surface, and a inner peripheral surface 20 facing the buffing surface 2 of the base tire 3, the inner peripheral surface axially opposite sides of 20 Is a band-like body having raised wings 21 fitted with the cut-off surface, and wound along the buffing surface 2 of the base tire 3 in an unvulcanized state and using a rubber-based adhesive. 3 Ritore' de rubber 4 is affixed to the base tire 3 by gluing.

[0025] Such Ritore' de The rubber forming step and the base tire 3 is joined by fart the Ritoreddogomu 4, vulcanization molding process which is vulcanized in a vulcanization mold K 2 Through the process, a retreaded tire is formed.

In the vulcanization molding step, a tread pattern including a groove 18 is formed on the tread surface 10 in addition to the vulcanization treatment.

[0027] vulcanizing mold K is and the base tire 3 and Ritore' de rubber 4 in the mold cavity in the O as shown in FIG. 2 is loaded. The inward surface 23 of the vulcanizing mold K facing the mold cavity O is formed on the basis of the contour of the completed retread tire. The mold size is further regulated.

The difference between the grip width GW of the vulcanizing mold K and the rim width LW of the reference rim J on which the retreaded tire 1 is assembled is 3 mm or less.

[0029] and the difference between the rim width LW of the reference rim J of the retreaded tire 1 a clip width GW of the vulcanization mold K is assembled rim and 3mm or less.

The groove bottom diameter KD of the vulcanizing mold K is in the range of -2 to +4 mm with respect to the groove bottom diameter GD of the old tire, and 0.48 to 0 with respect to the groove bottom diameter of the old tire. The maximum width BK of the vulcanization mold is ±
In the range of 2 mm, and 0.1 mm from the groove bottom diameter of old tires.
In the buttress 13 located at the position of 76 to 0.86 times, the vulcanizing mold K is set within 3 mm from that of the old tire.

Further, the radius of curvature KR in the meridional section of the tread surface of the vulcanizing mold K is smaller than the radius of curvature GR of the groove bottom radius line in the meridional section of the old tire by 40 mm or less.

[0032] By vulcanizing the base tire 3 and Ritore' de rubber 4 with thus dimensioned regulated vulcanization mold K, the tread surface 10 and the belt layer 7 after the vulcanization molding process The total thickness of the tread rubber in between is such that the total thickness Ts in the side region S is equal to or less than the total thickness Tc of the central region C,
Moreover, the retreaded tire 1 having a value equal to or greater than a value obtained by subtracting 0.5 mm from the total thickness Tc of the central region C is formed.

[0033]

[Specific Example] A tube-containing tire having a tire size of 225/90 R17.5 was tested for its performance together with an example of trial production according to the specifications shown in Table 1. A test was also conducted on a tire having a conventional retread (comparative example) to compare the performance. Table 1 shows the test results.

[0034]

[Table 1]

As a result of the test, it was confirmed that the example had better abrasion resistance and heat resistance than the comparative example.

[0036]

As described above, the method of manufacturing a retreaded tire for trucks and buses according to the present invention, as described above, uses the thickness of the rubber layer remaining after buffing at the center region and the side region of the tread portion and after the molding and vulcanization steps. Because the gist is to regulate the total thickness of each tread rubber, the retreaded tire manufactured despite the molding method is improved in uneven wear resistance, heat resistance and durability. By
It can be suitably used as a retreaded tire for trucks and buses.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a retread tire manufactured according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a vulcanizing mold used for the manufacturing method.

FIG. 3 is a sectional view schematically showing a conventional vulcanizing mold.

[Explanation of symbols]

1 retread tire 2 buffing surface three tire 4 Ritore' de rubber 5 tread portion 6 a carcass 7 belt layer 10 tread surface C central region CO tire equator GW grip width K vulcanizing mold LW rim width S side region TW tread width

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-136907 (JP, A) JP-A-2-258329 (JP, A) JP-A-58-1546 (JP, A) JP-A-61-1986 85205 (JP, A) JP-A-4-230403 (JP, A) JP-A-3-62821 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29D 30 / 00-30 / 72

Claims (3)

(57) [Claims] 1. A method for manufacturing a retread tire for trucks and buses having a carcass of a steel cord and a belt layer composed of a plurality of plies of a steel cord, wherein a tread portion of a used tire is buffed, A buffing step of forming a buff remaining rubber layer on the base tire by forming a tread buffing surface on the base tire, and an unvulcanized retret on the tread buffing surface of the base tire.
Ritore' de rubber forming step for impregnating the de rubber, and the base tire and Ritore' de vulcanization molding process and rubber to form a vulcanized tread pattern on the tread surface in the vulcanizing mold, with including, the buff remaining The rubber layer has a center region C having a width of 0.75 times the tread width TW about the tire equator, and side regions S on both sides of the center region C in the tire axial direction.
The thickness tc of the central region C is 1.5 to 3.5 mm, the thickness ts of the side region S is 1.0 to 3.0 mm and not more than the thickness tc of the central region. The total thickness of the tread rubber between the subsequent tread surface and the belt layer is such that the total thickness Ts of the side region S is equal to or less than the total thickness Tc of the central region C, and the total thickness Tc of the central region C is 0%. A method for manufacturing a retread tire for trucks and buses, wherein the value is not less than 0.5 mm. Wherein said vulcanization mold is claim 1, characterized in that the clip width GW is the difference between the rim width LW and 3mm or less
A method for producing a retreaded tire for trucks and buses as described above. 3. The method according to claim 1, wherein the retreaded tire is a tire with a tube.