JPH0655659A - Cushion rubber for pneumatic tire and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent molding of inferior quality by making it easier to release the air between a cushion rubber and a ply and also other parts of a tire. CONSTITUTION:A plurality of narrow grooves 20 extending in a width direction are formed in the longitudinal direction of a stiffener 18 spaced apart predetermined intervals on a surface 18A in contact with a body ply of a carcass ply of the unvulcanized stiffener 18 and a surface 18B in contact with a turn-up ply. The opposite ends of each narrow groove 20 are opened to the ends of the stiffener 18 along the longitudinal direction thereof. When a green tire is formed, when surfaces 18A and 18B on which grooves 20 are formed come into contact with the carcass ply, an elongated space is formed. And hence, when the green tire is pressed from the interior against a mold surface by the expansion of a bladder loaded in a vulcanization mold, the air between the stiffener 18 and the body ply 16 is discharged through the space. And the rubber of tire is subjected to the pressure caused by the expansion of the bladder or the air so as to be further vulcanized, while the air is being discharged, so that the rubber is caused to flow and the grooves 20 are eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber contour for a pneumatic tire and a method for manufacturing the rubber contour for a pneumatic tire.

[0002]

2. Description of the Related Art At present, when forming a green tire for a pneumatic tire, so-called rubber contours for cushion rubber, stiffener, side tread, etc. are used. This green tire is formed by winding a carcass ply around a predetermined drum, and arranging cushion rubber, stiffener, side tread rubber contours, beads, and belts at predetermined positions of the carcass ply. It

A green tire assembled with predetermined parts is loaded into a predetermined vulcanization mold and vulcanized.

[0004]

By the way, when assembling a green tire, when attaching each rubber contour for cushion rubber, stiffener, side tread, etc. to the body ply, between these rubber contours and the carcass ply. May remain in the air. For example, as shown in FIG. 11 (A), the end portion 18B of the stiffener 18 on the side opposite to the bead 12 side first comes into contact with the body ply 16C of the carcass ply 16 so that the stiffener 18 and the body ply 16C are separated from each other. Air 10
0 may remain, or as shown in FIG. 11B, the end portion 16A of the carcass ply 16 may come into contact with the stiffener 18 first, and the air 100 may remain between the folded back ply 16B and the stiffener 18. is there.

When the vulcanization is carried out in the state where the air remains inside, the unbonded portion is generated between the stiffener 18 and the carcass ply 16,
The molded pneumatic tire becomes unmoldable and cannot be used.

In view of the above facts, the present invention makes it easier to release air between the rubber contour for a pneumatic tire and the plies and other tire parts when vulcanizing and molding a green tire, thereby causing defective molding. An object of the present invention is to provide a rubber contour for a pneumatic tire and a method for producing the rubber contour for a pneumatic tire.

[0007]

A rubber contour for a pneumatic tire according to a first aspect of the present invention is substantially the radial of the tire on at least a surface of a carcass having a body ply and a folded ply which is in contact with the body ply. It is characterized in that a groove extending in the direction is formed.

According to a second aspect of the present invention, there is provided a method for manufacturing a rubber contour for a pneumatic tire, wherein a plurality of ridges extending substantially in the axial direction are arranged in the circumferential direction on the surface of the rubber contour for the pneumatic tire conveyed by the conveying means. It is characterized in that a groove is formed by making contact with the provided molding roll while rotating it.

[0009]

According to the rubber contour for a pneumatic tire of the invention described in claim 1, the rubber contour for a pneumatic tire includes:
A groove extending substantially in the radial direction of the tire is formed on at least a surface of the carcass having the body ply and the folded ply, which is in contact with the body ply. Therefore, even when air is left between the rubber contour for the pneumatic tire and the body ply or other adjacent tire parts at the time of forming the green tire, a gap is generated.
The air between the rubber contour for the pneumatic tire and the body ply is discharged through the groove when the internal pressure is applied by the expansion of the bladder of the vulcanization mold or the air during the vulcanization molding, and the rubber contour for the pneumatic tire and the body ply are It does not remain between adjacent tire components. It should be noted that, while the air is being discharged, this groove flows and disappears when the surrounding rubber that has been subjected to internal pressure in the vulcanization mold is in an unvulcanized state.

Further, according to the method of manufacturing a rubber contour for a pneumatic tire of claim 2, a plurality of ridges extending substantially in the axial direction are circumferentially provided on the surface of the rubber contour for the pneumatic tire conveyed by the conveying means. Since the arranged molding rolls are brought into contact with each other while rotating, grooves can be efficiently formed continuously on the surface of the rubber contour for a pneumatic tire along the conveying direction.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 2 is a cross section of the pneumatic tire 10 in the vicinity of the bead portion. The pneumatic tire 10 has a general radial structure and has a pair of beads 12 and a toroidal carcass layer 14, and the carcass layer 14 is composed of at least one carcass ply 16.

The carcass ply 16 has a large number of cords covered with rubber, and the cords extend in the tire radial direction (meridian direction).

The carcass ply 16 has an end 16A wound around the bead 12 from the inner side in the tire axial direction to the outer side, and is folded back, and the outer side in the tire axial direction is a folded ply 16B.

Body ply 16C of the carcass ply 16
A stiffener 18 having a substantially triangular cross-section is disposed in a region having a substantially triangular cross-section surrounded by the folded ply 16B.

As shown in FIG. 1 (A), the stiffener 18 of this embodiment has a long belt-like shape in the unvulcanized state before tire assembly and has a surface 18A in contact with the body ply 16C of the carcass ply 16. A plurality of narrow grooves 20 extending substantially in the width direction are formed along the longitudinal direction of the stiffener 18 on the surface 18B (see FIGS. 1A and 2) that is in contact with the folded ply 16B.

These narrow grooves 20 preferably have a width W1 of 3 mm or less and a depth D of 1.5 mm or less. Further, it is preferable that at least one of the narrow grooves 20 in the longitudinal direction is opened at the end portion along the longitudinal direction of the stiffener 18. Further, the pitch dimension P of these narrow grooves 20
Is preferably in the range of 5 mm to 20 mm and at substantially equal intervals. The dimension w2 is in the range of 3 to 20 mm.

The fine grooves 20 are preferably formed so that the longitudinal direction thereof is within ± 20 ° with respect to the radial direction of the tire.

In this embodiment, the unvulcanized stiffener 18 is used.
The narrow groove 20 formed in the linear shape extends linearly in the stiffener width direction (direction of arrow A in FIG. 1) (becomes 0 ° with respect to the radial direction of the tire), and both ends thereof are stiffeners 18.
Is open at the end along the longitudinal direction of the.

Next, the unvulcanized stiffener 18 is provided with the narrow groove 2.
A method of forming 0 will be described. These narrow grooves 20 are formed by a narrow groove forming machine 26 described below.

As shown in FIG. 3, the narrow groove forming machine 26 is disposed downstream of the stiffener outlet of the extruder 28 for extruding and forming the unvulcanized stiffener 18 (direction of arrow B). The groove forming machine 26 is provided with a conveyor 30 that horizontally conveys the stiffener 18 in a direction away from the extruder 28 (direction of arrow B). The extruder 28 has a structure that is generally used in tire manufacturing, and details thereof will be omitted.

Between the conveyor 30 and the extruder 28, a typed roll 32 is arranged below the conveying path of the stiffener 18, and a pressing roll 34 is arranged above the conveying path of the stiffener 18. . The mold roll 32 has a cylindrical shape, and protrusions 36 extending in the axial direction (front and back direction of the paper surface of FIG. 3) are formed on the outer peripheral surface at predetermined intervals in the outer peripheral direction. The die roll 32 is rotatably supported by a base (not shown) and is rotated in the direction of arrow C by a motor (not shown).

On the other hand, the pressing roll 34 has a columnar shape and both ends thereof are rotatably supported by bearings 38. The bearing 38 is attached to a pressure adjusting device 40 composed of an air cylinder or the like.
When 0 is operated, the pressing roll 34 can be urged toward the mold roll 32 side with a predetermined pressure. The pressing roll 34 is also rotated in the direction of arrow D by a motor (not shown), and nips and conveys the unvulcanized stiffener 18 extruded from the extruder 28 together with the die roll 32 to the conveyor 30 side.

By inverting the stiffener 18 at an intermediate portion of the conveyor 30 in the conveying direction, the stiffener 18 is twisted during the conveying to reverse the front and back sides.

On the downstream side of the conveyer 30 in the conveying direction, a typed roll 42 is arranged below the conveying path of the stiffener 18, and a pressing roll 44 is arranged above the conveying path of the stiffener 18. In addition, these typed rolls 4
2 and the press roll 44 have the same structure as the above-mentioned mold roll 32 and press roll 34.

The axial directions of the mold rolls 32 and 42 are parallel to the surface of the unvulcanized stiffener 18 where the narrow groove 20 is formed.

Next, the operation of this embodiment will be described. Extruder 2
The unvulcanized stiffener 18 extruded from No. 8 is extruded to the narrow groove forming machine 26 side, and is nipped and conveyed to the conveyor 30 side by the die roll 32 and the press roll 34 rotated by the motor. At this time, the unvulcanized stiffener 18 is contacted with the mold roll 32 by the lower surface (the surface 1).
8A or the surface 18B), the protrusion 36 is pressed to form the narrow grooves 20 at predetermined intervals.

The unvulcanized stiffener 18 having the narrow groove 20 formed on one side thereof is conveyed by the conveyor 30 and is inverted and twisted during the conveyance so that the surface on which the narrow groove 20 is formed is turned upward. It is conveyed to the attaching roll 32 and the pressing roll 34 side.

The stiffener 18 reaching the die roll 32 and the press roll 34 is nipped and conveyed by the die roll 32 and the press roll 34, and the other surface (either the surface 18A or the surface 18B) on which the narrow groove 20 is not formed. Or the other)
The protrusions 36 are pressed to form the narrow grooves 20 at predetermined intervals.

As described above, the unvulcanized stiffener 18 extruded from the extruder 28 is continuously formed with the fine grooves 20 on the surfaces 18A and 18B while being conveyed.

The stiffener 18 having the narrow groove 20 formed therein is arranged at a predetermined position of the carcass ply 16 together with the bead 12 and other components in the green tire assembling process.

As shown in FIG. 4, when the surface 18A (18B) of the stiffener 18 in which the narrow groove 20 is formed contacts the carcass ply 16, the narrow groove 20 is surrounded by the carcass ply 16 and the longitudinal direction of the tire radial. An elongated space portion 48 oriented in the direction is formed (note that 17 is a cord).

The green tire completed through the predetermined steps is loaded into a vulcanization mold (not shown) and pressed from the inside toward the mold surface by the expansion of a bladder or air. At this time, the gap between the stiffener 18 and the carcass ply 16 is pressed and disappears, and the air in the gap is discharged to the side opposite to the bead 12 side through the space 48. The rubber of the tire under pressure due to the expansion of the bladder or the air flows while the air is released, and the narrow groove 20 disappears. The air discharged from between the stiffener 18 and the carcass ply 16 is efficiently discharged when it is discharged to the outside from the degassing portion provided in the vulcanization mold.

Thereafter, the green tire is vulcanized by applying a predetermined pressure and a predetermined temperature.

In the pneumatic tire thus formed, air is not present between the stiffener 18 and the carcass ply 16, that is, the stiffener 18 and the carcass ply 16 are firmly adhered and joined together. Molding failures that could not be avoided can be reduced to zero.

If the longitudinal direction of the narrow groove 20 exceeds 20 ° with respect to the radial direction of the tire, the longitudinal dimension of the narrow groove 20 becomes long and the air discharge property deteriorates, which is not preferable.

When the narrow groove 20 is formed with an inclination,
As shown in FIG. 5 (A), the stiffener 1 is inclined.
8 may be inclined to the right with respect to the width direction of FIG.
As shown in (B), it may be inclined to the left.

Both ends of the narrow groove 20 are stiffeners 1.
It is most preferable to open at the end of No. 8, but if air can escape when pressure is applied by the expansion of the bladder, only one end of the narrow groove 20 is provided for the stiffener 18.
May be opened at the ends of the stiffener 18 (see FIG. 6), or both ends may not be opened at the ends of the stiffener 18 (see FIG. 7). However, when only one end of the narrow groove 20 is opened to the end of the stiffener 18, it is preferable to open the end of the narrow groove 20 on the tire equatorial plane side to the end of the stiffener 18. In terms of

In the above embodiment, the stiffener 18 is used.
Although the example in which the narrow groove 20 is formed is shown in the above, the present invention is not limited to this, and as long as it is a rubber contour for a pneumatic tire constituting a tire, a rubber contour for a pneumatic tire other than the stiffener 18, such as a cushion rubber, a side. The narrow groove 20 may be formed in the tread or the like. FIG. 8 shows a cross section of the pneumatic tire 10 having the cushion rubber 60 as the rubber contour for the pneumatic tire and the side rubber layer 64.

As shown in FIG. 8, cushion rubber 60
Are arranged inside both ends of the tread rubber layer 62, and are in contact with the side rubber layer 64 and the carcass ply 16 to have a triangular cross section.

As shown in FIG. 9, this cushion rubber 6
In No. 0, a thin groove 20 extending in the tire radial direction is formed on a surface 60A that is in contact with the carcass ply 16 in the unvulcanized state before tire assembly, like the unvulcanized stiffener 18 of the above-mentioned embodiment. The narrow groove 2 extending in the tire radial direction also on the surface 60B in contact with the side rubber layer 64.
0 is formed. In addition, unvulcanized cushion rubber 6
The specifications (width dimension W, depth dimension D, pitch P, longitudinal direction, etc.) of the narrow groove 20 formed in No. 0 are the same as those of the narrow groove 20 formed in the unvulcanized stiffener 18 of the above-mentioned embodiment, Further, the formation of the narrow groove 20 in the unvulcanized cushion rubber 60 is also performed by the above-described thin groove 2 in the unvulcanized stiffener 18.
It can be formed by the narrow groove forming machine 26 in the same manner as the formation of 0.

On the other hand, in the side rubber layer 64 of the pneumatic tire 10, the fine grooves 20 can be similarly formed in the unvulcanized state.

Also in this embodiment, when the green tire receives a pressure due to the expansion of the bladder or the air, the cushion rubber 60 and the carcass ply 16, the cushion rubber 60 and the side rubber layer 64, and the side rubber layer 6 are provided.
Air between the carcass ply 16 and the carcass ply 16 can be discharged to the outside through a space 48 (not shown in FIG. 8) formed by the narrow groove 20.

FIG. 10 shows another embodiment of the fine groove forming machine 26. In the narrow groove forming machine 26 shown in FIG. 10, the mounting position of the mold roll 42 is different from that of the above-described narrow groove forming machine 26, and in this embodiment, the mold roll 42 is used.
Is arranged above the conveyor 30, and the fine groove 20 is formed on the upper surface of the rubber contour for the pneumatic tire such as the stiffener 18 conveyed by the conveyor 30. In this embodiment, no reversing roller is provided.

[0045]

As described above, since the rubber contour for a pneumatic tire according to the first aspect of the present invention has the above-mentioned constitution, the green tire formed by using the rubber contour for a pneumatic tire is vulcanized and molded. At this time, air between the ply in contact with the rubber contour for the pneumatic tire and other tire components can be discharged through the groove, which has an excellent effect of preventing defective molding due to residual air.

Further, in the method for producing a rubber contour for a pneumatic tire according to the second aspect of the present invention, a plurality of protrusions extending substantially in the axial direction are circumferentially provided on the surface of the rubber contour for the pneumatic tire conveyed by the conveying means. Since the arranged molding rolls are brought into contact with each other while rotating, it has an excellent effect that grooves can be continuously and efficiently formed on the surface of the rubber contour for a pneumatic tire.

[Brief description of drawings]

1A is a perspective view of an unvulcanized stiffener according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view perpendicular to a groove of the stiffener shown in FIG. 1A. It is a figure.

FIG. 2 is a cross-sectional view of the vicinity of a bead portion of a pneumatic tire to which a stiffener is applied according to an embodiment of the present invention.

FIG. 3 is a side view of the narrow groove forming machine according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a boundary portion between a carcass ply and a stiffener according to an embodiment of the present invention.

FIG. 5A is a side view of a stiffener showing a narrow groove inclined to the right according to still another embodiment of the present invention, and FIG. 5B is related to still another embodiment of the present invention. It is a side view of the stiffener which shows the narrow groove inclined to the left.

FIG. 6 is a side view of a stiffener according to still another embodiment of the present invention, showing a narrow groove having one end opened at the end of the stiffener.

FIG. 7 is a side view of a stiffener according to still another embodiment of the present invention, showing a narrow groove at both ends of the stiffener, both ends of which are not opened.

FIG. 8 is a cross-sectional view of a pneumatic tire having a cushion rubber and a side rubber layer according to another embodiment of the present invention.

9 is a perspective view showing an unvulcanized state in which the fine grooves of the cushion rubber shown in FIG. 8 are formed.

FIG. 10 is a side view of a narrow groove forming machine according to still another embodiment of the present invention.

FIG. 11A is a cross-sectional view of the vicinity of the stiffener showing the air remaining between the stiffener and the body ply during the molding of the conventional green tire.
[Fig. 6] is a sectional view of the vicinity of the stiffener showing air remaining between the stiffener and the folded ply, similarly showing the conventional green tire during molding.

[Explanation of symbols]

16 Carcass Ply 18 Stiffener (Rubber contour for pneumatic tire) 20 Groove 30 Conveyor (conveying means) 32 Molding roll 36 Ridge 42 Molding roll 60 Cushion rubber (Rubber contour for pneumatic tire) 64 Side rubber layer (Rubber contour for pneumatic tire)

Claims (2)

[Claims] 1. A rubber contour for a pneumatic tire, characterized in that a groove extending substantially in a radial direction of the tire is formed on at least a surface of a carcass having a body ply and a folded back ply in contact with the body ply. 2. A groove is formed by contacting a surface of a rubber contour for a pneumatic tire conveyed by a conveying means with a mold roll having a plurality of protrusions extending substantially in the axial direction in a circumferential direction while rotating the groove. A method for producing a rubber contour for a pneumatic tire, which comprises forming the rubber contour.