JPH09254274A - Production method and device for green tire for retreading - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to form an unvulcanized rubber skin with a homogeneous width so as to obtain a good surface appearance of a side wall of a retreaded tire after vulcanization. SOLUTION: A narrow width unvulcanized rubber strip 3 is stuck to a side surface area of a base tire obtained by removing a rubber skin. An unvulcanized rubber strip part 3b laminated after a second lap is bonded in spiral-form under overlapped with a laminated unvulcanized rubber strip part 3a in an inner side previously. A convergent parts 3c, 3d whose width are progressively reducing toward an each inner end 8 position and outer end 10 position are provided to a part including the outer end 10 of the unvulcanized rubber strip 3 and a part including the inner end 8 thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a green tire for retreading, and specifically, the rubber outer skin of a used tire is buffed and removed, leaving a rim line below a bead portion. In the side area from the rim line of the obtained base tire to the shoulder edge,
The present invention relates to a method and an apparatus for forming an unvulcanized rubber outer cover having a uniform width over the entire circumference. Conventionally, the surface appearance of a retreaded tire after vulcanization was not so favorable as a product, but the present invention can improve the surface appearance.

[0002]

2. Description of the Related Art It is known that tires have different service lives depending on their respective parts, and in general, the outer rubber of the tread and the side wall is worn more than other parts such as beads. It is prone to failure due to damage or damage and has a short service life. For this reason, retreaded tires have been developed which can be reused by removing only these outer rubbers, re-adhering new unvulcanized rubbers, and vulcanizing them. Since this retreaded tire is excellent in terms of cost and environment, it is expected to be applied to truck / bus tires that particularly emphasize appearance.

Conventionally, as a method of forming an unvulcanized outer rubber on a side wall for manufacturing a green tire for rehabilitation, for example, as shown in FIGS. 4 (a) and 4 (b), an unvulcanized rubber outer rubber is formed. The front and rear conceptual diagrams are shown, but a side surface region 23 extending from the rim line 20 of the base tire obtained by buffing leaving the rim line 20 or less of the bead portion to the shoulder edge 21
Then, an unvulcanized rubber strip 22 having a constant width and a narrow width is attached along the rim line 20 from a position directly above the rim line 20, and the unvulcanized rubber strip portion to be attached after the second lap (in FIG. 4 (b), , For convenience of explanation, only the unvulcanized rubber strip portion of the second lap is designated as 22b.) The unvulcanized rubber strip portion is directly attached to the inner side (in FIG. Only the unvulcanized rubber strip portion of the eye is set to 22a.) While being overlapped (overlap portion 24), the unvulcanized rubber skin 25
Is generally used.

[0004]

However, when the unvulcanized rubber skin 25 is formed by this method, the unvulcanized rubber is insufficient in the portion 28 shown by hatching in FIG. 4 (b). It is not possible to form an unvulcanized rubber outer cover of uniform width over the entire circumference of the side surface region 23, and when vulcanized to produce a retreaded tire in the state of the unvulcanized rubber outer cover of this uneven width, the retreaded tire is The surface appearance is deteriorated at the portions corresponding to the side surface regions, particularly at the positions 26 and 27 at both ends of the unvulcanized rubber on the rim line and the shoulder edge.

An object of the present invention is to provide a method and an apparatus for manufacturing a retreading green tire capable of forming an unvulcanized rubber outer cover having a uniform width in order to improve the surface appearance of the sidewall of the retreaded tire after vulcanization. To provide.

[0006]

In order to achieve the above object, the method for producing a green tire for retreading according to the first aspect of the present invention comprises buffing and removing the rubber outer skin of a used tire, leaving a rim line below the bead portion, A narrow unvulcanized rubber strip is attached to the side surface area obtained from the rim line of the base tire from the buffing removal and extending to the shoulder edge from the position immediately above the rim line or along the shoulder edge position along the same, and after the second lap. The unvulcanized rubber strip is formed by overlapping the unvulcanized rubber strip portion with the unvulcanized rubber strip portion that was previously attached to the inside or outside while spirally adhering to the shoulder edge or directly above the rim line. A method of manufacturing a green tire for recycling, comprising: The portion including the portion and an inner end including a tapered width toward the inner end position and an outer end position, respectively is gradually reduced provided, tapering start position of the portion including the outer end,
If a line segment connecting the tire shaft center position and the inner end position is hypothesized, the line segment is on an imaginary line extending from the inner end position, and the gradually decreasing start position of the portion including the inner end is the tire shaft. If a line segment connecting the center position and the outer end position is hypothesized, it is on this line segment.

Further, if the outer end position of the unvulcanized rubber strip is assumed to be a line segment connecting the inner end position and the tire shaft center position, this line segment is extended from the tire shaft center position. More preferably, it is on the line.

In the apparatus for producing a green tire for retreading according to the second aspect of the present invention, the base tire from which the buffing is removed while leaving the rubber outer skin of the used tire below the rim line of the bead portion can be rotated around its rotation axis. A supporting frame and a rubber extruder located on the side of the base tire supported by the frame and movable in a direction along the side surface and the sectional height of the base tire, the rubber extruder is a base tire. It has a head positioned close to the side surface, and this head is rotatable while maintaining a predetermined distance from the side surface of the base tire, and has a narrow width that is extruded from the head in the side surface region extending from the rim line of the base tire to the shoulder edge. An unvulcanized rubber strip portion to which a vulcanized rubber strip is attached along the rim line immediately above or from the shoulder edge position along the second rim or later. In order to form an unvulcanized rubber outer cover by laminating the unvulcanized rubber strip portion pasted on the inside or the outside in a spiral shape up to just above the shoulder edge or rim line while overlapping with the unvulcanized rubber strip portion, When the unvulcanized rubber strip is attached to the side surface region, the head is changed from 90 ° to 0 ° in terms of the angle between the width direction and the cross-sectional height of the base tire between the inner end position and the half-circumferential position. The head is kept at 0 ° at the angle between the half circumference position and the position before the half circumference of the outer end of the unvulcanized rubber strip, and then the half circumference of the outer end is rotated. From the front position to the outer end position, by gradually rotating the head in the direction in which the angle is gradually increased from 0 ° to 90 °,
An unvulcanized rubber skin having a uniform width can be formed over the entire circumference of the side surface region.

The method and apparatus for manufacturing a rehabilitation green tire of the present invention is characterized by the above-specified matters in forming the unvulcanized rubber outer cover on the side surface region of the base tire. It goes without saying that the full-molding method is applied after the tread rubber is provided on the crown portion of the base tire including the necessary replacement or rearrangement of the belt or breaker in accordance with the conventional recap.

[0010]

1 is a schematic view of a lateral region of a retreading green tire manufactured by the manufacturing method according to the first invention as viewed from the side of the tire.
Is a rim line of a bead portion, 2 is a shoulder edge, 3 is an unvulcanized rubber strip, 3c and 3d are tapered portions, 4 is an overlapping portion between unvulcanized rubber portions, 5 is an unvulcanized rubber outer skin, and 6 is a tip. 3d is the gradual reduction start position, 7 is the tire axial center position, 8 is the inner end of the unvulcanized rubber strip 3, and 9 is the taper 3
The gradual decrease start position of c, 10 is the outer end of the unvulcanized rubber strip 3.

In the method of manufacturing a green tire for rehabilitation according to the first aspect of the present invention, first, the rubber outer skin of a used tire is buffed to remove the rim line 1 and below of the bead portion.

Next, a narrow unvulcanized rubber strip 3 is pasted along the rim line 1 from a position right above the rim line to the side surface region extending from the rim line 1 to the shoulder edge 2 of the base tire obtained by this buffing removal. The unvulcanized rubber strip portion to be bonded after the second lap (in FIG. 1, only the unvulcanized rubber strip portion for the second lap is shown as 3b in FIG. 1) is not bonded to the inner side immediately. Sulfur rubber strip portion (In FIG. 1, for convenience of explanation, only the unvulcanized rubber strip portion of the first round is
It is as a. ) Is overlapped (overlap portion 4), and the unvulcanized rubber outer skin 5 is formed by sticking spirally to the shoulder edge 2. Although the unvulcanized rubber strip is pasted along the rim line 1 from the position immediately above the rim line in the above description, the unvulcanized rubber strip is stuck to the unvulcanized rubber strip. 3 may be bonded from the position of the shoulder edge 2 along the shoulder edge 2, and there is no particular limitation.

The unvulcanized rubber strip 3 used in the present invention has tapered portions 3c and 3d whose width gradually decreases toward a portion including an inner end and a portion including an outer end thereof toward an inner end position and an outer end position, respectively. Have.

In the present invention, it is necessary to satisfy the following positional relationship as a condition for attaching the unvulcanized rubber strip 3. That is, the gradually decreasing start position 6 of the portion including the outer end of the unvulcanized rubber strip 3 (that is, the tapered portion 3d).
If a line segment connecting the tire axial position 7 and the inner end position 8 is hypothesized, the line segment is on a virtual line extending from the inner end position 8 and a portion including the inner end 8 (that is, If the gradual decrease start position 9 of the tapered portion 3c) is a virtual line segment connecting the tire axial center position 7 and the outer end position 8, the unvulcanized rubber strip 3 is placed on this line segment. Bonding is an essential configuration of the present invention.

More preferably, if the outer end position 10 of the unvulcanized rubber strip 3 is assumed to be a line segment connecting the inner end position 8 and the tire axial center position 7, this line segment is Be on an imaginary line extending from the tire axial position 7, that is,
As shown in FIG. 1, from the left, the unvulcanized rubber strip 3
The outer end position 10, the taper 3c gradually decreasing start position 9, the tire axial position 7, the inner end position 8, the taper 3d gradually decreasing start position 6
Arrange them on the same straight line in the order of.

According to the present invention, with such a structure, the unvulcanized rubber outer skin 5 having a uniform width can be formed over the entire circumference in the side surface region of the base tire.

The unvulcanized rubber strip 3 preferably has a width of 30 to 50 mm and a thickness of 0.5 to 4.0 mm, depending on the tire size, and the overlap portion 4 has a width of 3 to 10 mm. It is preferably about the same.

The formation (recapping) of the tread rubber after forming the unvulcanized rubber outer skin 5 is carried out in accordance with a conventional method, whereby a green tire can be easily obtained, which is subjected to molding and vulcanization by full molding. Carry out and manufacture retreaded tires.

Next, an apparatus for manufacturing a rehabilitation green tire according to the second invention will be described. FIG. 2 is a front view of the tire with the tire set in the manufacturing apparatus according to the second invention. The manufacturing equipment in this figure
A frame 12 that rotatably supports the base tire 11 around its rotation axis, and a direction that is located on the side of the base tire 11 supported by the frame 12 and that extends along the side surface 11a and the cross-sectional height of the base tire 11. It has a movable rubber extruder 14 to 13,
The rubber extruder 14 has a head 15 positioned close to the side surface 11a of the base tire 11, and the head 15 is configured to be rotatable in the direction of arrow 17 while maintaining a predetermined distance from the side surface 11a of the base tire 11. It was done.

The manufacturing apparatus shown in this figure changes the movement of the head 15 in the direction 13 and the rotation in the direction 17 in response to the rotation of the base tire 11 to change the direction of the head 15.
The main feature is that the unvulcanized rubber strip extruded from is directly bonded in a spiral shape to the side surface region 16 of the base tire 11 while appropriately controlling the width thereof.

A brief description of a method for manufacturing a rehabilitation green tire using the manufacturing apparatus shown in FIG.
(a) and (b) show the changes in orientation due to the rotation of the head 15.
(From the top to the bottom of the figure, move the head 15
And the cross-sectional height direction 19 of the base tire 11 make an angle θ of 90 °
It is the figure which changed from 0 to 0 degree. ) (Fig. 3 (a))
The corresponding change in the width of the unvulcanized rubber strip 3 (Fig. 3 (b)) is shown. The control of the width of the unvulcanized rubber strip 3 in this manufacturing apparatus is specifically performed on the side surface of the base tire 11. During the bonding of the unvulcanized rubber strip 3 to the 11a from the inner end position 8 to a half-circle position (that is, the gradually decreasing start position 9 of the tapered portion 3c), the head 15 is moved to the angle θ.
At 90 ° to 0 °, and then from the half-circle position 9 to the half-circle front position 6 of the outer end 10 of the unvulcanized rubber strip, the head is kept at 0 ° at the angle. The head is held between the half-circumferential position 6 of the outer end 10 and the outer end position 10 and the angle is changed from 0 ° to 90 °.
It is done by rotating in the direction of gradually increasing to °. As a result, an unvulcanized rubber outer cover having a uniform width can be formed over the entire circumference of the side surface region.

The above description merely shows a part of the embodiments of the first and second inventions, and various modifications can be made within the scope of the claims.

[0023]

[Examples] One small extruder on each side of a tire 11 having a tire size of 1000R20 and a tire 11 on which the rubber outer skin of the tread has been buffed removed
Place 14 and width 40 mm, thickness 1.
Attach the base for 0 mm, and attach this base to the side of the base tire.
The head 15 was positioned so that the distance between the head and a was kept within the range of 0.5 to 1.0 mm (see FIG. 2). And the base tire
11 is rotated, and the extruder 14 is moved from the rim line 1 of the base tire to the shoulder edge 2 in accordance with the rotation of the base tire 11.
The head of the extruder 14 while moving in the direction
Corresponding to attaching 15 to the unvulcanized rubber strip 3 from its inner end position to a half-circumferential position, the head is changed from 90 ° to 0 ° in terms of an angle between its width direction and the sectional height of the base tire. The head is kept at 0 ° at the angle corresponding to the bonding from the half circumference position to the half circumference front position of the outer end of the unvulcanized rubber strip, and then the head is held at 0 °. Corresponding to sticking from the front half-circumference position of the outer end to the outer end position, the head is gradually rotated in the direction in which the angle is gradually increased from 0 ° to 90 °, thereby obtaining a uniform width as shown in FIG. (120 mm) unvulcanized rubber skin 5 was formed. Unvulcanized rubber strip 3 at this time
The lamination was carried out by winding the inner end to the outer end in three and a half turns. The taper portions 3c and 3d of the unvulcanized rubber strip are provided at the tapering start positions 9 and 6, respectively.
As shown in FIG. 1 and is separated from the inner end position 8 and the outer end position 10 by a half circumference, and the width of the overlapping portion 4 is set to 5
mm.

For comparison, a retreaded tire was manufactured according to the conventional method, in which unvulcanized rubber sheets of uniform width (40 mm) having no taper on both ends were laminated three times.

As a result, in the comparative example, a portion where the wall thickness is reduced occurs at the position immediately above the rim line or the shoulder edge position, and product failures such as bears frequently occur, and it is necessary to attach a separate rubber layer to this portion, which is costly. However, in the embodiment, the wall thickness at the position directly above the rim line and the shoulder edge position can be made uniform, so that there is no product failure such as bare after vulcanization, and the side The surface appearance of the wall has been greatly improved.

[0026]

According to the method of the first invention, the rubber outer skin of the side wall portion of the used tire is buffed and removed, and the side surface region extending from the rim line to the shoulder edge of the base tire is unvulcanized with a uniform width. A rubber outer coat can be formed, which can improve the surface appearance of the sidewall portion of the retreaded tire after vulcanization. Further, according to the apparatus of the second invention, the step of attaching the narrow unvulcanized rubber strip to the side surface of the base tire can be automated, and efficient operation can be facilitated.

[Brief description of drawings]

FIG. 1 is a typical schematic side view when an unvulcanized rubber outer cover is formed on a sidewall portion of a rehabilitation green tire according to the method according to the first invention.

FIG. 2 is a schematic view showing an example of setting a stand tire on a typical device according to a second aspect of the invention and forming an unvulcanized rubber outer cover on a side surface region thereof.

3 (a) and 3 (b) are diagrams respectively showing a change in orientation due to rotation of a head 15 of the apparatus of FIG. 2 and a change in width of the unvulcanized rubber strip 3 corresponding thereto.

4A and 4B are schematic side views before and after forming an unvulcanized rubber outer cover on a sidewall portion of a rehabilitation green tire according to a conventional method.

[Explanation of symbols]

 1 Rim line 2 Shoulder edge 3 Unvulcanized rubber strip 3c, 3d Tip 4 Overlap portion 5 Unvulcanized rubber skin 6 Tapered 3d taper start position 7 Tire axial center 8 Inner end of unvulcanized rubber strip 3 Tapered 3c taper start position 10 Outer end of unvulcanized rubber strip 3 11 Tires 12 Frames 13 Direction along section height of tire 11 14 Rubber extruder 15 Head of rubber extruder 14 16 Side area of tire 17 Arrow direction 18 Head 15 width direction 19 Unit Tire 11 cross-section height direction 20 Rim line 21 Shoulder edge 22 Unvulcanized rubber strip 23 Side area 24 Overlap portion 25 Unvulcanized rubber outer skin 26 Unvulcanized rubber strip Inner edge 27 Outer edge of unvulcanized rubber strip 28 Diagonal area

Claims (3)

[Claims] 1. A rubber uncovered from a used tire is removed by buffing, leaving a portion below the rim line of a bead portion, and a narrow unvulcanized area is obtained in a side surface region extending from the rim line of the base tire to the shoulder edge obtained by this buffing removal. The rubber strip is pasted along the rim line from the position directly above the rim line or along the shoulder edge position, and the unvulcanized rubber strip part to be pasted after the second lap is the unvulcanized rubber strip part pasted to the inside or outside first. In a method for producing a green tire for reproduction in which a non-vulcanized rubber outer cover is formed by pasting in a spiral shape up to just above a shoulder edge or a rim line while overlapping, a portion including an outer end of the unvulcanized rubber strip and an inner portion In the part including the end, the width gradually decreases toward the inner end position and the outer end position, respectively. If a taper is provided and the gradual decrease start position of the portion including the outer end is a virtual line segment connecting the tire axial center position and the inner end position, this line segment is on a virtual line extending from the inner end position. The gradual decrease start position of the portion including the inner end is on a line segment connecting the tire axial center position and the outer end position, and is on this line segment. Manufacturing method. 2. If the outer end position of the unvulcanized rubber strip is assumed to be a line segment connecting the inner end position and the tire axial center position, then this virtual line segment is extended from the tire axial center position. The method for manufacturing a green tire for rehabilitation according to claim 1, which is on a line. 3. A frame for rotatably supporting a base tire from which a rubber outer cover of a used tire has been removed by buffing except a rim line of a bead portion, and a base tire supported on the frame. And a rubber extruder that is located on the side of the base tire and is movable in the direction along the cross-sectional height of the base tire. The rubber extruder has a head positioned close to the side surface of the base tire. However, a narrow unvulcanized rubber strip extruded from the head is placed in the side area of the base tire extending from the rim line to the shoulder edge. The unvulcanized rubber strips that are to be bonded from the edge position along them and that are to be bonded after the second round are first bonded to the inside or outside. When forming the unvulcanized rubber outer cover by overlapping the shoulder strip or just above the rim line in a spiral shape while overlapping with the rubber strip portion, attach the unvulcanized rubber strip to the side surface area of the base tire. From the inner end position to the half-circle position, the head is rotated in a direction in which the angle between the width direction and the cross-sectional height of the base tire is gradually reduced from 90 ° to 0 °, and then from the half-circle position. The head is held at 0 ° at the angle until the outer circumference of the unvulcanized rubber strip reaches a position before the half circumference, and the head is held between the half circumference before the outer edge and the outer end of the unvulcanized rubber strip. Further, by gradually rotating the angle in a direction of gradually increasing from 0 ° to 90 °, an unvulcanized rubber outer cover having a uniform width is formed over the entire circumference of the side surface region. Equipment for manufacturing green tires.