JPH0747617A - Pneumatic tire, and production thereof - Google Patents

Abstract

PURPOSE:To obtain a pneumatic tire not having possibility generating hue difference between the tread side surfaces of the tire and the peeling between rubber sheets. CONSTITUTION:When a green tread 66 is formed by winding a raw rubber sheet 32 around a green tire case, the raw rubber sheet 32 is cut before wound around the green tire case so as to be matched with the lateral dimension of a position where both end parts in the lateral direction thereof are wound. At the time of cutting, the angle with the equator surface tire is varied so that the cut surface is matched with the shape of a green objective tread. Since the shape of the green tread 66 coincides with that of the objective tread, no molding irregularity is generated in a product tire after vulcanization molding and no hue difference or peeling is generated in the tread of the product tire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire manufacturing method and a pneumatic tire, and more particularly, to a pneumatic tire for continuously rolling and stacking a raw rubber sheet on a raw tire case to produce a tire tread. The present invention relates to a manufacturing method and a pneumatic tire.

[0002]

2. Description of the Related Art In large tires such as pneumatic tires for construction vehicles, the tire tread has a large volume, and in order to improve work efficiency and manufacturing quality, the tread is a long raw rubber having a predetermined thickness. Generally, a method of continuously winding and laminating sheets to produce them is used.

[0003]

By the way, in the conventional method, although the inclination angle of the tread end portion differs depending on the tire size, and the tread end portion is formed by two or more straight lines, A certain angle θ with a certain cutting machine
_Since the raw rubber sheet cut at _A was laminated on the raw case to approximate the tread shape, as shown in FIG. 8, the side surface 102 of the tread 100 is entirely stepped, or in FIG. As shown in the figure, some of them have a linear shape, while others have a stepped shape.

In the conventional method, since the side surface shape of the raw tread formed by laminating the raw rubber sheets in the tire width direction has stepwise unevenness, when the tire is vulcanized, the uneven portion of the raw tread is evenly formed on the vulcanization mold. However, the rubber of the convex portion is crushed to fill the concave portion, causing local flow of the rubber, which causes a problem such as a difference in color tone and peeling between the rubber sheets at the time of production.

The cause of peeling is that the adhesive force of the boundary surface formed by the rubber flowing and contacting during vulcanization molding is not sufficient.

Further, the difference in color tone causes deterioration in appearance quality and commercial value. In consideration of the above facts, the present invention is a method for manufacturing a pneumatic tire that does not cause a difference in color tone of a tread side of a product tire or occurrence of peeling between rubber sheets, etc. An object of the present invention is to provide a pneumatic tire that is unlikely to generate.

[0007]

A method of manufacturing a pneumatic tire according to claim 1, wherein a tread of a raw tire is obtained by winding and laminating a long raw rubber sheet having a predetermined thickness on a raw tire case. A method for manufacturing a pneumatic tire, which comprises forming and then vulcanizing and molding the raw tire with a predetermined vulcanization mold to obtain a finished product, wherein the long tire is wound on the raw tire case. While cutting both ends in the width direction of the raw rubber sheet to match the raw target tread shape, the cutting makes an angle with the tire equatorial plane so that the cut surface of the long raw rubber sheet matches the raw target tread shape. It is characterized by changing.

The pneumatic tire according to claim 2 is characterized by being manufactured by the method for manufacturing a pneumatic tire according to claim 1.

[0009]

In the method for manufacturing a pneumatic tire according to the first aspect of the present invention, the tread of a raw tire is formed by winding and laminating a long raw rubber sheet having a predetermined thickness on a raw tire case. Here, the long-sized raw rubber sheet is cut at both ends in the width direction before being wound on the raw tire case in accordance with the raw target tread shape, that is, the width dimension of the wound position, and the long length. The angle formed by the tire equatorial plane is changed so that the cut surface of the raw rubber sheet matches the target raw tread shape.

Therefore, the tread shape formed by the long raw rubber sheet laminated on the green tire matches the target tread shape.

The green tire formed as described above is vulcanized and molded by a predetermined vulcanization mold to obtain a pneumatic tire as a finished product.

According to the present invention, since the tread having the target tread shape can be formed on the green tire, uneven molding does not occur in the product tire after vulcanization molding.

Since the pneumatic tire according to claim 2 is manufactured by the method for manufacturing a pneumatic tire according to claim 1, there is no molding unevenness and peeling occurs due to insufficient adhesive strength. Nor.

[0014]

EXAMPLES An example of a pneumatic tire for a construction vehicle manufactured by the method for manufacturing a pneumatic tire of the present invention and the method for manufacturing a pneumatic tire of the present invention will be described with reference to FIGS. 1 to 6.

As shown in FIG. 2, a pneumatic tire 10 for a construction vehicle (tire size 36.00R51 as an example)
Includes a pair of bead cores 12 and these bead cores 1.
The carcass 14 is made up of steel cords that extend in the toroidal shape and are arranged in the radial direction.

A belt layer 16 composed of a plurality of belts intersecting each other is arranged on the outer side in the radial direction of the carcass 14, and a tread 18 is arranged on the outer side in the radial direction of the belt layer.

Next, a manufacturing apparatus 22 for manufacturing a raw tire of the pneumatic tire 10 for a construction vehicle of this embodiment will be described.

As shown in FIG. 3, the manufacturing apparatus 22 is equipped with a sheeting roll 28 consisting of a pair of rolls 24 and 26, and rotates in mutually opposite directions to form a block of raw rubber 3.
0 is set as a raw rubber sheet 32 having a predetermined thickness and discharged in the direction of arrow C.

A direction changing roller 34 is arranged in the direction of arrow C of the sheeting roll 28, and a direction changing roller 36 is provided above the direction changing roller 34 (direction of arrow A).
Is provided. A sheet width cutter 38 is disposed in the direction C of the direction changing roller 36.

As shown in FIG. 4, the sheet width cutter 38
Is provided with a horizontal rail 40, which extends in a direction (arrow B direction and a direction opposite to the arrow B direction) orthogonal to the feeding direction (arrow C direction) of the raw rubber sheet 32, above the transport path.

On the horizontal rail 40, four cutter support bases 42 are movably supported along the longitudinal direction of the horizontal rail 40. The cutter device base 42 can be moved along the longitudinal direction of the horizontal rail 40 by a driving device (not shown), and each movement is controlled by a computer (not shown) connected to the driving device.

Further, the cutter support base 42 has a built-in cylinder device (not shown) controlled by a computer, and is capable of expanding and contracting in the vertical direction.

An actuator 44 including a motor, a gear, a rotary encoder, etc. is attached to the lower side of the side of the cutter device base 42 in the direction of arrow C.

The actuator 44 has a rotary shaft 46 protruding in the direction of arrow C. As shown in FIGS. 4 and 5, the rotary shaft 46 includes a knife fixing portion 4 extending in the radial direction.
8 is provided, and a knife 50 is replaceably attached to the knife fixing portion 48 with a screw or the like. The blade of the knife 50 is directed to the upstream side (direction of arrow C) in the conveying direction of the raw rubber sheet 32, and the inclination angle of the cut surface of the raw rubber sheet 32 can be changed by changing the rotation angle of the rotating shaft 46. . In addition, the actuator 4
The rotation angle of the rotary shaft 46 of 4 is controlled by a computer.

As shown in FIG. 4, a nipping roller 56 consisting of a pair of rollers 52 and 54 is provided in the direction of arrow C of the sheet width cutter 38. The nipping roller 56 is configured such that the motor 52 (not shown) rotates the rollers 52 and 54 in opposite directions so as to pull the raw rubber sheet 32 in the direction of arrow C.

The rotation speeds of the nip roller 56 and the above-mentioned sheeting roll 28 are also controlled by the computer.

A tire building drum 58 that is generally used is disposed diagonally below the nip roller 56 in the direction of arrow C.

Here, the computer is a raw rubber sheet 3
The number of cuts of the raw rubber sheet 32, the cutting width dimension, the cutting angle, the number of layers (conveyance amount), and the shrinkage rate of the raw rubber sheet 32 so that the target tread shape is obtained by winding 2 on the raw tire case 60 of the molding drum 58. Is calculated to control the nip roller 56, the sheeting roll 28, the cutter support base 42, the actuator 44, and the like.

The shrinkage rate of the raw rubber sheet 32 is calculated because the raw rubber fed by the sheeting roll 28 has a high temperature and is naturally cooled as the raw rubber sheet 32 is conveyed to the tire molding drum 58 side to shrink the raw rubber sheet 32. Is to cause.

The computer calculates the ratio of shrinkage of the raw rubber sheet 32 from the seat width cutter 38 to the tire molding drum 58 so that the width dimension when the raw rubber sheet 32 is attached to the raw tire case 60 becomes the target width dimension. Also, the cutting width dimension and the carry amount of the raw rubber sheet 32 are controlled so that the winding length becomes appropriate. Since the shrinkage rate has a predetermined value depending on the rubber type, when the rubber type is changed, the value of the shrinkage rate input to the computer is changed accordingly.

Next, the manufacturing process for forming the tread on the raw tire case 60 formed on the tire building drum 58 will be described.

For example, as shown in a cross section along the tire axial direction in FIG. 1A, the widthwise central portion 62 has a constant thickness,
When the tread 66 having the trapezoidal convex portions 64 having linear slopes on both sides thereof is formed on the raw tire case 60, from the start of winding to the winding and stacking to the thickness of the widthwise central portion 62. As shown in FIG. 4, both sides of the raw gome sheet 32 are cut by the knives 50 on both sides and divided into three in the width direction, and the intermediate portion 32A of the divided raw gome sheet 32 is divided.
Is conveyed downward after being discharged from the nip roller 56, and wound around a predetermined position on the outer circumference of the raw tire case 60.
After being ejected from the nip roller 56, it is conveyed upward and collected.
The collected raw rubber of both end portions 32B is collected and reused.

The work of winding the intermediate portion 32A of the raw rubber sheet 32 around the outer circumference of the raw tire case 60 is carried out by a molder as usual, and the raw tire case 60 or the raw rubber sheet 32 previously wrapped is stitched by a stitching roll or the like. It is pressed and sequentially laminated to a predetermined thickness.

Here, as shown in FIG. 1 (B), both ends of the tread 66 are inclined so as to be gradually narrowed, so that the raw rubber sheet 32 wound in the order of the second and third laps. The two knives 5 on each side so that the width of
0 sequentially moves inward (in the present embodiment, a predetermined amount is moved for each rotation of the raw tire case 60). Here, since the inclination angles of both end portions of the tread 66 are constant, the inclination angles of the two knives 50 on both end sides remain unchanged at a predetermined angle.

Thereafter, a plurality of raw rubber sheets 32 are wound and laminated so that the laminated thickness is a central portion 62 of the tread 66 in the width direction.
When the thickness of the convex portion 64 substantially coincides with that of the convex portion 64, the formation of the convex portion 64 is started.

In order to form the convex portion 64, as shown in FIG. 6, the two cutter support bases 42 on the central side extend downward,
The knives 5 provided on the two cutter support bases 42 on the center side
The intermediate portion 32A of the raw rubber sheet 32 is divided into three by 0, and the whole is divided into five.

The raw rubber sheet 32 divided into five parts is conveyed upwardly after the central portion 32C and both end portions 32B of the intermediate portion 32A are discharged from the nip roller 56, and is collected, and the remaining two intermediate portions 32A are laminated first. It is wrapped around the raw rubber sheet 32 and the convex portion 64 is formed.

Here, in order to form the trapezoidal shape of the convex portion 64, the two knives 50 on the center side are inclined according to the angle of the inclined surface of the convex portion 64 on the inner side in the tire width direction, and are sequentially arranged in the width direction. It moves to the outside (in this embodiment, it moves by a predetermined amount for each rotation of the raw tire case 60), and the two knives 50 at both ends move sequentially in the width direction as described above (in this embodiment, The raw tire case 60 is moved a predetermined amount for each rotation).

As described above, since the number of cuts, the cutting width dimension, and the cutting angle of the raw rubber sheet 32 wound around the raw tire case 60 can be variously changed, the tread 66 having a shape corresponding to the target tread cross-sectional shape can be obtained. Can be formed on 60.

Further, since the side surface of the tread 66 is not stepped, when the tread 66 comes into contact with the vulcanization mold, the surfaces come into contact with each other and local uneven contact does not occur. . That is, by contacting the vulcanization mold as in the conventional case, a new rubber obtained by locally flowing a part of the rubber of the surface portion from the stepped shape to the smooth inclined surface which is the target tread shape is obtained. No joint surface is produced. The joint surface between rubbers newly made in such a vulcanization mold has a weak joint force unlike the portion pressed by a stitching roll, etc., which causes cracking after vulcanization. Example raw tread 6
In No. 6, since there is no unnecessary unevenness and a new boundary surface is not created when it comes into contact with the vulcanization mold, the tread 18 of the pneumatic tire 10 for a construction vehicle that has become a product after vulcanization molding
Does not have such a cause of cracking.

The thickness of the raw rubber sheet 32 when the tread 66 is formed is 1 to 5 mm, preferably 2 to 3 mm in order to prevent air from entering during lamination.

In the raw tread 66 of the above-mentioned embodiment, the inclination angles of both sides are straight, but FIG.
As shown in (A), when the tread 66 has two inclined surfaces with different inclination angles, the cutting angle by the knife 50 is changed in the middle to cut the raw rubber sheet 32 as shown in FIG. 7 (B). Change the angle of the surface.

The roll 2 of the sheeting roll 28
4 and the roll 26 are configured to be variable, and the distance is controlled by a computer so that the raw rubber sheet 32
The thickness may be partially variable.

In this embodiment, the pneumatic tire for construction vehicles was taken as an example to describe the method for manufacturing the pneumatic tire of the present invention. However, a long raw rubber sheet is wound and laminated on a raw tire case. As a matter of course, the present invention may be used when manufacturing a pneumatic tire other than the pneumatic tire for construction vehicles as long as it is a pneumatic tire of a type that forms a tread of a raw tire.

[0045]

As described above, since the method for manufacturing a pneumatic tire according to claim 1 is as described above, it is possible to form a tread having a target tread shape on a green tire and to perform vulcanization. It has an excellent effect that unevenness in molding is not caused in the product tire after molding.

Further, since the pneumatic tire according to claim 2 is manufactured by the method for manufacturing a pneumatic tire according to claim 1, it is excellent in that there is no molding unevenness and peeling due to insufficient adhesive strength does not occur. Have the effect.

[Brief description of drawings]

FIG. 1A is a cross-sectional shape of a tread, and FIG.
[FIG. 2] is an enlarged view of an arrow D portion of the tread shown in FIG.

FIG. 2 is a sectional view taken along the meridian of a pneumatic tire for a construction vehicle according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a manufacturing apparatus.

FIG. 4 is a perspective view of a main part of the manufacturing apparatus showing a state where the raw rubber sheet is divided into three parts.

FIG. 5 is a side view of the vicinity of the knife as seen from the direction opposite to the arrow C direction.

FIG. 6 is a perspective view of a manufacturing apparatus showing a state where a raw rubber sheet is divided into five parts.

7A is a cross-sectional view of a tread according to another embodiment, and FIG. 7B is an enlarged view of the arrow E portion of the tread shown in FIG. 7A.

FIG. 8 is an enlarged cross-sectional view of a side surface of a conventional tread.

FIG. 9 is an enlarged cross-sectional view of a side surface of another conventional tread.

[Explanation of symbols]

 10 Pneumatic tires for construction vehicles 32 Raw rubber sheet 60 Raw tire case 66 Tread

Claims (2)

[Claims] 1. A method of manufacturing a pneumatic tire, comprising forming a tread of a raw tire by winding and laminating a long raw rubber sheet having a predetermined thickness on the raw tire case. Before winding, the widthwise both ends of the long raw rubber sheet are cut in accordance with the raw target tread shape, and the cutting is such that the cut surface of the long raw rubber sheet matches the raw target tread shape. As described above, the method for manufacturing a pneumatic tire is characterized by varying the angle formed by the tire equatorial plane. 2. A pneumatic tire manufactured by the method for manufacturing a pneumatic tire according to claim 1.