JPH0647836A - Method for molding pneumatic tire - Google Patents

Abstract

PURPOSE:To mold a pneumatic tire of high quality highly efficiently and with a device low in cost. CONSTITUTION:A ply band 14 transforms at only its end in the axial direction from a final shape (toroidal shape) by the minimum i.e., its diameter is expanded so as to be a little larger than an outer diameter of a green case 30, so that restoration state of contraction is excellent and quality of a tire will be improved. Besides, the ply band 14 and the green case 30 are attached with pressure in sequence to an inner periphery of a belt tread band 17 by transforming them into the toroidal shape, so that molding process is simplified, efficiency is improved, and a device low in cost can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a pneumatic tire having a down ply, that is, a ply which is not folded around a bead and extends along the tire outer circumference from the tread to the axially outer side of the bead.

[0002]

2. Description of the Related Art The applicant of the present invention describes, as a method for molding a pneumatic tire having a down ply, for example, in Japanese Patent Application No. 3-137093 (filed on May 14, 1991) before the application of the present application. I proposed something like. This is a process in which the diameter of the first drum, to which the cylindrical ply band serving as the down ply is attached, is expanded, and the expanded ply band is held as it is in the holder, and the ply band held in the holder is The step of arranging the bead cores on the drum on the outer peripheral side of the green case with the bead cores pre-wound at both ends, and releasing the ply band from the holder causes the ply band to shrink based on its own shrinkage deformation. A step of attaching to the outer peripheral surface,
It is equipped with. Then these outside belts,
Place the tread and mold the green tire.

Further, in order to prevent the cord pitch from being disturbed and handle easily in such a molding method, the present applicant describes in Japanese Patent Application No. 4-46663 (filed on Mar. 4, 1992). As described above, a molding method is also proposed in which the ply band is expanded in diameter by a plurality of expansion / contraction segments each having two or more rows of rotating members provided on the outer peripheral portion.

[0004]

However, in any of the above-mentioned molding methods, the ply band (down ply) is used.
Irrespective of the final shape (toroidal shape), the diameter is enlarged uniformly, and after that, it is attached to the outer peripheral surface of the green case by its own contraction deformation, so the restored state of contraction varies depending on the location. As a result, there is a problem that the quality of the tire deteriorates. Further, there is a problem that the work for expanding the diameter of the ply band as described above requires a lot of man-hours, and an expensive drum and a complicated mechanism are required.

It is an object of the present invention to provide a pneumatic tire molding method capable of molding a high-quality pneumatic tire with a highly efficient and inexpensive apparatus.

[0006]

The object is to loosely fit a cylindrical belt / tread band on the outside of a cylindrical ply band which is a down ply on the first drum, and the ply band. Swelling from the inside and deforming it into a substantially toroidal shape, by pressing the central part of the ply band in the axial direction to the inner circumference of the belt / tread band to form a band assembly; Removing the band assembly from the first drum while gripping it from the first drum, and expanding at least the axial end of the ply band close to the second drum to a diameter slightly larger than the outer diameter of the green case on the second drum. In this state, the step of loosely fitting the band assembly to the outside of the green case and the expansion of the diameter of the ply band are completed, and the green case is placed inside. Bulged deformed into a toroidal shape,
The step of crimping the green case to the inner circumference of the band assembly can be achieved.

[0007]

First, the cylindrical belt / tread band is loosely fitted to the outside of the cylindrical ply band on the first drum. Next, the ply band is swollen from the inside and deformed into a substantially toroidal shape, whereby the axial center portion of the ply band is pressed against the inner circumference of the belt / tread band to form a band assembly. Next, the band assembly is taken out of the first drum while gripping the belt / tread band from the outside, and then the band assembly is loosely fitted to the outside of the green case. At this time, at least the axial end portion of the ply band that is close to the second drum is expanded to a diameter slightly larger than the outer diameter of the green case on the second drum, so that the band assembly interferes with the green case. Prevent. Next, the diameter expansion of the ply band is completed, the green case is bulged from the inside and deformed into a toroidal shape, and the green case is pressure-bonded to the inner periphery of the band assembly. During such molding, the ply band is deformed from the final shape (toroidal shape) only in the axial end portion to the required minimum, that is, the ply band is expanded to a diameter slightly larger than the outer diameter of the green case. , The restored state of shrinkage is good, and the tire quality is improved. Moreover, since the ply band and the green tire are deformed into a toroidal shape on the inner circumference of the belt / tread band to be pressure-bonded one after another to mold the green tire, the molding process is simplified and the efficiency is improved. The equipment is also cheaper and better.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 11 is a cylindrical rotatable first drum, and this first drum 11 has slide portions 12 axially movable at both ends in the axial direction. At the outside of the first drum 11, a bladder 13 that is easily bendable is arranged. And the rotating first drum
A ply having a large number of cords embedded in 11 is supplied and attached to form a cylindrical ply band 14. At this time,
As shown in FIG. 2, on the outside of a band forming machine (not shown), a plurality of belt plies 15 having a plurality of cords embedded therein and a tread rubber 16 are attached one after another to form a cylindrical belt / tread band. After molding 17, the belt / tread band 17 is conveyed toward the first drum 11 while being grasped from the outside by the grasping and conveying mechanism 18, and is kept outside the ply band 14 in a coaxial relationship with the ply band 14. Fit loosely. When the belt / tread band 17 is loosely fitted to the outside of the ply band 14 in this manner, the sliding portion 12 of the first drum 11 is moved inward in the axial direction to fill the fluid in the bladder 13, and the bladder 13 Deform toroidal. At this time, since the ply band 14 is arranged on the outer side of the bladder 13, the ply band 14 is bulged from the inner side by the bladder 13 and is deformed into a substantially toroidal shape like the bladder 13. Here, since the axial center portion of the ply band 14 bulges outward most in the radial direction, the axial center portion is formed on the inner circumference of the belt / tread band 17 held by the holding and conveying mechanism 18. Abut and crimp as shown in. As a result, the ply band 14 and the belt / tread band 17 are combined to form the band assembly 19. Then, the fluid in the bladder 13 is discharged while moving the slide portion 12 of the first drum 11 outward in the axial direction, and the bladder 13 is returned to the initial cylindrical shape. Next, the gripping / conveying mechanism 18 holding the band assembly 19 from the outside is moved in the axial direction, and the band assembly 19 is taken out from the first drum 11.

In FIG. 3, reference numeral 25 denotes a rotatable second drum, and the second drum 25 has slide portions 26 axially movable at both axial ends. Then, a substantially cylindrical green case 30 is taken out from the forming drum (not shown) to the second drum 25 by a carrying mechanism (not shown), and is then carried to the second drum 25 and delivered. . Here, the green case 30 is wrapped around a carcass ply 27 in which a cord extending in the radial direction is embedded on the outside of the forming drum when the band assembly 19 is formed, and then the bead 29 with the filler 28 is formed. The carcass ply 27 is molded by being set outside both ends in the axial direction. Thereafter, the carcass ply 27 axially outside the bead 29 is folded back inward in the axial direction by a bladder (not shown) in the second drum 25. At this time, the band assembly 19 taken out from the first drum 11 is expanded from the inside by the holders 31 at both axial ends of the ply band 14 in a state of being gripped from outside by the gripping and conveying mechanism 18. To be done. Here, each holder 31 is composed of, for example, a plurality of holding claws 32 that are spaced apart in the circumferential direction, and a moving mechanism that moves these holding claws 32 in synchronization in the radial direction and the axial direction, After the holding claws 32 are inserted into both axial end portions of the ply band 14, they are radially outwardly synchronized in synchronization with a moving mechanism to expand both axial end portions of the ply band 14. Both ends of the ply band 14 in the axial direction are expanded by the holders 31 to a diameter slightly larger than the outer diameter of the green case 30. After that, the band assembly 19 is gripped and conveyed.
The band assembly 19 is conveyed toward the second drum 25 while being gripped from the outside by 18, and the band assembly 19 is loosely fitted to the outside of the green case 30 while maintaining a coaxial relationship. At this time, since both ends in the axial direction of the ply band 14 which is the smallest diameter in the natural shape are expanded to slightly larger than the outer diameter of the green case 30 by the retainer 31, the ply band 14 and the green are loosely fitted. It does not interfere with the case 30. In this embodiment, both ends of the ply band 14 in the axial direction are expanded by the holder 31, but only the end of the ply band 14 in the axial direction which is close to the second drum 25 is expanded by the holder 31. You may do it.

Next, as shown in FIG. 4, while moving the slide portion 26 of the second drum 25 inward in the axial direction, the green case 30 is filled with fluid and swelled from the inside, and the green case 30 is opened. Deform toroidal. In the middle of this deformation, the holding claws 32 of each holder 31 are moved inward in the radial direction and then outwardly in the axial direction, thereby ending the diameter expansion of the holder 31 with respect to the ply band 14 and holding them. The tool 31 is retracted from the ply band 14. As a result, the ply band 14 is released from its both ends in the axial direction to be reduced in diameter, and is restored to a substantially toroidal shape. Return to the initial diameter. And the green case 30
When is deformed into a toroidal shape as described above, the green case 30 is pressed and pressure-bonded to the inner circumference of the substantially toroidal ply band 14. At this time, the ply band 14 is a down ply, that is, a ply which is not folded around the bead 29 and extends along the tire outer circumference from the tread rubber 16 to the axially outer side of the bead 29. Here, since the outer diameters of the first drum 11 for molding the ply band 14 and the molding drum for molding the green case 30 described above have the same diameter at the time of molding, the ply band 14 and the carcass ply 27 at the time of molding to the green tire are formed. The expansion rates of the tires can be made almost the same, and the tire quality can be improved. After that, the gripping and conveying mechanism 18 is detached from the band assembly 19 and retracted, and then the side rubber (not shown) is attached to the band assembly.
Affixed to both sides in the axial direction of 19, and mold green tires. During such tire molding, the ply band 14 is deformed from the final shape (toroidal shape) only in its axial end portion by a necessary minimum amount, that is, the ply band 14 is expanded to a diameter slightly larger than the outer diameter of the green case 30. Therefore, the restored state of shrinkage is good, and the tire quality is improved. Moreover, the ply band 14 and the green case are attached to the inner circumference of the belt / tread band 17.
Since the green tires are molded by deforming 30 into a toroidal shape and then crimping them one after another, the molding process is simplified, the efficiency is improved, and the apparatus is inexpensive.

In the above-described embodiment, the ply band 14 is deformed into a toroidal shape by the fluid through the bladder 13 and the fluid in which the green case 30 is directly filled inside. However, in the present invention, Ply band 14
Alternatively, the green case 30 may be deformed into a toroidal shape by the fluid directly filled in the inside or by the fluid through the bladder. Further, in the above-mentioned embodiment, the filler 28 constituting the green case 30 is inclined with respect to the radial direction, but depending on the type of tire, this filler may extend substantially in the radial direction. In addition, the diameter expansion amount of the axial end portion of the ply band 14 must be made larger than that in the above embodiment.

[0012]

As described above, according to the present invention, a high-quality pneumatic tire can be molded with a highly efficient and inexpensive device.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of the vicinity of a first drum showing an embodiment of the present invention.

FIG. 2 is a partially cutaway front view of the vicinity of the first drum for explaining a molded state of the band assembly.

FIG. 3 is a partially cutaway front view of the vicinity of a second drum.

FIG. 4 is a partially cutaway front view of the vicinity of the second drum for explaining a state in which the green case is pressure-bonded to the band assembly.

[Explanation of symbols]

 11 ... 1st drum 14 ... Ply band 17 ... Belt / tread band 19 ... Band assembly 25 ... 2nd drum 30 ... Green case

Claims (1)

[Claims] 1. A step of loosely fitting a cylindrical belt / tread band on the outer side of a cylindrical ply band serving as a down ply on the first drum, and a substantially toroidal shape by bulging the ply band from the inside. By deforming the ply band into the inner circumference of the belt / tread band to form a band assembly, and the band assembly is gripped from the outside while the first The band assembly is taken out of the drum, and the band assembly is expanded with at least the axial end portion of the ply band close to the second drum being slightly larger than the outer diameter of the green case on the second drum. The step of loosely fitting the outer side of the ply band and ending the expansion of the diameter of the ply band, and swelling the green case from the inner side to deform it into a toroidal shape, Method of molding a pneumatic tire characterized by comprising the step of crimping the lean case on the inner circumference of the band assembly, the.