JPH10329140A - Method for vulcanization-molding of pneumatic tire and vulcanization-molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a pneumatic tire of outstanding uniformity without generating a non-uniform angle change in the reinforcing cord of a belt layer. SOLUTION: This vulcanization-molding device keeps the inner peripheral face T1 of a green tire T molded to almost the same outer diameter as the inner diameter of sectors 13 for molding a tread, when fully closed, which are formed by splitting a vulcanizing die in such sectors in the peripheral direction, expanded by expanding the diameter of a freely expandable/shrinkable rigid ring 37. Further, the device fully closes the sectors 13 and injects a heated fluid under pressure to the inside of the green tire T to vulcanization-mold the green tire T.

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 vulcanizing a pneumatic tire, and more particularly, to a method and apparatus for vulcanizing a pneumatic tire capable of producing a pneumatic tire having excellent uniformity. Related to the device.

[0002]

2. Description of the Related Art In general, in vulcanization molding of a pneumatic tire, a green tire molded to a diameter smaller than the inner diameter of a mold (molding surface of a tread pattern) is set in a mold, and a heating fluid is vulcanized at the time of vulcanization. The tread pattern is formed by press-fitting and adding a lift with a bladder to expand the diameter. In the pneumatic tire formed in this way, it is inevitable that the reinforcing cord angle of the belt layer changes due to a change in the outer diameter due to the lift or a biting reaction force of the tread pattern into the tread member. The non-uniformity caused a reduction in uniformity.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reinforcing cord for a belt layer without causing an uneven angle change.
An object of the present invention is to provide a method and an apparatus for vulcanizing and molding a pneumatic tire capable of producing a pneumatic tire having excellent uniformity.

[0004]

According to the present invention, there is provided a method of vulcanizing and molding a pneumatic tire according to the present invention, comprising the steps of: The inner peripheral surface of the green tire molded to substantially the same outer diameter is held in a state where the expandable and contractible rigid ring is expanded, and then the sector is fully closed, and a heating fluid is pressed into the inside of the green tire. It is characterized by being vulcanized.

Further, in the vulcanizing and forming apparatus for a pneumatic tire according to the present invention, a center mechanism having a pair of vertically movable clamp rings is disposed on an inner circumferential side of a tread forming sector divided into a plurality of parts in a circumferential direction. In the pneumatic tire vulcanization molding device, a rigid ring that can be expanded and contracted in the horizontal direction is connected between the pair of upper and lower clamp rings via a link mechanism, and the rigid ring is located at a position where the upper clamp ring is most lowered. It is characterized in that the inner peripheral surface of a green tire molded to an outer diameter substantially equal to the inner diameter of the sector when fully closed is held.

In this manner, the sector is fully closed while the green tire having substantially the same diameter as the inner diameter of the sector when fully closed is held by the rigid ring expanded from the inside, and the heating fluid is press-fitted into the inside of the green tire to apply pressure. Since the vulcanization molding is used, vulcanization molding can be performed without applying a large lift unlike the conventional method, so that there is no uneven angle change on the circumference of the reinforcing cord of the belt layer, and therefore, excellent uniformity is achieved. Pneumatic tires can be manufactured.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an example of a vulcanization molding apparatus used in the vulcanization molding method for a pneumatic tire of the present invention. Reference numeral 1 denotes a sectional mold for tire vulcanization molding, and reference numeral 3 denotes a central mechanism provided with a pair of upper and lower clamp rings 31 and 32 provided on the inner peripheral side of the mold 1.

The mold 1 includes an annular upper mold plate 11 for molding one sidewall of the green tire T and an annular lower mold plate 1 for molding the other sidewall.
2, and a sector 13 for forming a tread pattern on the tread portion. The upper mold plate 11 and the lower mold plate 12 are formed with their side wall forming surfaces 11a,
and a plurality of sectors 13 that are divided along the circumferential direction are arranged on the outer periphery of the tread portion forming surface 13a on the inner periphery.

The upper plate 11 is held by an annular upper plate holder 14 disposed on the upper side thereof. An upper bead ring B1 for forming one bead portion is fixed to the inner peripheral side of the upper die plate 11. The piston rod 4a of the elevating cylinder 4 extending from above is connected to the inner peripheral end of the upper die plate holder 14 via a rod tip fitting 4b. 11 ascends and descends.

Segment 17 in which sector 13 is incorporated
Is attached by a sliding mechanism that can slide in the vertical direction along the inner peripheral inclined surface 16a of the container ring 16. Each sector 13 is radially divided, and in the final stage of the mold clamping, the side surfaces of the adjacent sectors come into contact with each other to form a perfect circular tread surface without any gap. When the upper mold base plate 15 is raised, the segment 17 is located below the container ring 16,
Each sector 13 is in an open state, and the innermost tread surface of the sector 13 is set to be larger than the outer diameter of the green tire T.

The lower surface of the segment 17 first comes into contact with the sliding surface on the lower mold base plate 18 by the fully closing operation due to the lowering of the upper base plate 15, and the inner peripheral inclined surface 16a of the container 16 and the segment 17 by the further lowering operation. Due to sliding with the outer peripheral inclined surface 17a, the diameter of the segment 17 is reduced toward the center, and the segment 17 is in a fully closed state. The center mechanism 3 includes a bag cylinder 33 erected on the center axis of the lower die plate 12, and the bag cylinder 33 includes a lifting rod 34 that is vertically movable by a drive mechanism (not shown). I have. A lower clamp ring 32 is attached to an upper part of the bag cylinder 33. Bag cylinder 33
An upper clamp ring 31 is fixed to the upper end of the lifting rod 34 projecting upward. The upper and lower ends of a cylindrical bladder 35 made of thin rubber are gripped by the outer peripheral ends of the upper and lower clamp rings 31, 32, respectively.

A rigid ring 37 which can be expanded and contracted in the horizontal direction is connected between the upper and lower clamp rings 31 and 32 via a plurality of link mechanisms 36. This rigid ring 3
Numeral 7 is disposed in the cylindrical bladder 35 and is formed on the left side of FIG. 1 when the upper clamp ring 31 is lowered to the lowest point, and is formed to have an outer diameter substantially equal to the inner diameter when the sector 13 is fully closed. When the upper clamp ring 31 is raised to the uppermost point (see FIG. 2A), the cylindrical bladder 35 expands so as to hold the inner peripheral surface T1 of the green tire T set as above. The diameter is reduced to the inside. In addition,
A green tire molded to have an outer diameter substantially the same as the inner diameter of the sector 13 when it is fully closed is 98 to 100% of the inner diameter of the sector 13 when fully closed (the tread outer diameter of the vulcanized tire).
Is a green tire having an outer diameter of tread.

When a pneumatic tire is vulcanized and formed by the above-described tire vulcanization molding apparatus, as shown in FIG. 2A, a sector 13 is provided around the central mechanism 3 in which the upper die plate 11 is opened. The green tire T molded to have an outer diameter substantially the same as the inner diameter when fully closed is gripped and inserted by the vertical loader X. Subsequently, the lifting rod 34 descends, whereby the rigid ring 37 expands in diameter through the link mechanism 36 as shown in FIG. 2B, and holds the green tire inner peripheral surface T1 from inside through the bladder 35. on the other hand,
The vertical loader X retreats, and the green tire T is set on the lower mold plate 12.

In this state, the cylinder rod 5a is extended by the operation of the lifting / lowering cylinder 5, the upper die plate 15 is lowered, and the lower surface of the segment 17 comes into contact with the sliding surface 19 on the lower die base plate 18, and further lowering operation is performed. Accordingly, the segment 17 is lowered to the fully closed position on the right side in FIG. 1 by sliding between the inner peripheral inclined surface 16a of the container ring 16 and the outer peripheral inclined surface 17a of the segment 17, and the closing operation is completed.

At this time, the inner tread surface 13 of the sector 13
The deformation of the belt layer can be prevented by the rigid ring 37 receiving the reaction force generated when the tread design bone portion a bites into the tread surface of the green tire T. Subsequently, a heated and pressurized fluid is supplied into the bladder 35 through a fluid pipe (not shown) provided inside the central mechanism to apply an internal pressure, and vulcanization molding is performed. Sector 13
The mold 1 is fully closed in a state where the green tire T molded to have the same outer diameter as the inner diameter when fully closed is held by the rigid ring 37 whose diameter is increased from the inside, and the heating fluid is pressed into the mold 1 for vulcanization molding. Therefore, since the vulcanization molding can be performed without causing a non-uniform change in the angle of the reinforcing cord as in a belt layer due to a conventional large lift, a pneumatic tire having excellent uniformity can be obtained. A green tire (98) whose outer diameter is slightly smaller than the inner diameter when the sector 13 is fully closed.
% Or more and less than 100%), a lift is applied when an internal pressure is applied. However, since a small lift of 2% or less is sufficient, there is no accompanying angle change that disturbs the reinforcing cord of the belt layer.

After vulcanization is completed, the mold 1 is operated in the reverse operation to the above.
Is opened, and the vulcanized tire is taken out. In the method of the present invention, it is preferable that after the mold 1 is fully closed, the expanded rigid ring 37 is reduced in diameter, and the rigid ring is separated from the bladder to perform vulcanization molding. Thus, the heated and pressurized fluid is in direct contact with the entire inner surface of the bladder, and the green tire T can be uniformly heated and vulcanized and formed from the inside. This makes it possible to eliminate non-uniformity of heat transfer from the inside of the portion that does not contact the portion that contacts the rigid ring.

As a structure for reducing the diameter of the rigid ring 37 whose diameter has been increased as described above, for example, the clamp rings 31 and 3 are used.
FIG. 3 shows each base end 36a of the link mechanism 36 connected to
As shown in FIG. In this figure, a configuration is shown in which the upper base end portion 36a of the link mechanism 36 is attached to the upper clamp ring 31, but the same applies to the case where the lower base end portion of the link mechanism 36 is attached to the lower clamp ring 32.

In FIG. 3, the hollow portion 4 is provided in the clamp ring 31.
0 is provided, and a piston 41 slidable up and down is disposed in the hollow portion 40. An O-ring 44 is attached to the outer peripheral surface of the piston 41 and abuts against the wall surface of the hollow portion 40. The piston 41 is constantly urged inward by a spring 42 disposed in the outer hollow portion 40a outside the piston 41. Accordingly, the rod 41a connected to the piston 41 is in a state of being exposed to the space 38 between the clamp rings 31 and 32 where the pressurized heating fluid is filled (left in FIG. 3). The space 38 and the inner hollow portion 40 b inside the piston 41 communicate with each other through a communication passage 43. The proximal end 3 of the link mechanism 36 is provided at the distal end of the rod 41.
6a is connected, the sector 13 is fully closed, and the pressurized and heated fluid filled during vulcanization flows from the communication passage 43 to the inner hollow portion 40b.
, The piston 41 returns by that pressure, and the rod 41a is retracted (right in FIG. 3), so that the rigid ring 37 is reduced in diameter and separated.

By this operation, when vulcanizing, the green tire T
A space is created between the inner surface of the bladder 35 that presses and the rigid ring 37, and the pressurized and heated fluid is bladder 35 having a thin rubber film.
, A uniform vulcanized state can be created by contacting the entire inner surface of the green tire T via In FIG. 3, the spring 42 is used as the urging means for bringing the rod 41 a into the extended state. Instead, a pressurized fluid is introduced from the outside into the outer hollow portion 40 a provided with the spring 42, and 41 can also be energized.

Further, in the present invention, in the above-described embodiment, the vulcanization molding has been described using the bladder 35.
The bladder 35 does not necessarily need to be provided if the space inside the space can be sealed and filled with the pressurized and heated fluid.

[0021]

As described above, according to the present invention, the inner peripheral surface of a green tire molded to have an outer diameter substantially equal to the inner diameter of a plurality of tread molding sectors divided in the circumferential direction when fully closed can be freely expanded and contracted. By expanding the diameter of the rigid body ring and holding it, then fully closing the sector, press-fitting the heating fluid inside the green tire and vulcanizing it, so that the conventional lift is not added during vulcanization. It is possible to obtain a pneumatic tire having excellent uniformity without causing an uneven change in the angle of the reinforcing cord of the belt layer on the tire circumference.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a pneumatic tire vulcanization molding apparatus according to the present invention in an open state on the left side of a center line CL and in a closed state on the right side.

FIGS. 2 (a) and 2 (b) are cross-sectional views each showing a main part of a vulcanization molding method for a pneumatic tire according to the present invention.

FIG. 3 shows an example of a configuration in which a rigid ring is reduced in diameter and then separated from a green tire after the mold is fully closed. A rod is protruded from the center line CL (the rigid ring contacts the green tire), and a right side. FIG. 4 is a cross-sectional view of a main part illustrating a state where a rod is submerged (a rigid ring is separated from a green tire).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Die 3 Central mechanism 4,5 Elevating cylinder 11 Upper plate 12 Lower plate 13 Sector 14 Upper plate holder 15 Upper base plate 16 Container ring 17 Segment 18 Lower base plate 31 Upper clamp ring 32 Lower clamp ring 33 Bag cylinder 34 lifting rod 35 bladder 36 link mechanism 37 rigid ring 38 space 40 hollow 41 piston 41a rod 42 spring 43 communication passage B1 upper bead ring B2 lower bead ring T green tire T1 inner peripheral surface

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 30:00

Claims (7)

[Claims] 1. A rigid ring capable of expanding and contracting an inner peripheral surface of a green tire molded to have an outer diameter substantially equal to an inner diameter of a tread molding sector of a vulcanization mold divided into a plurality of circumferentially when fully closed. A vulcanization molding method for a pneumatic tire in which the diameter is expanded and held, the sector is fully closed, and a heating fluid is pressed into the inside of the green tire to perform vulcanization molding. 2. The method according to claim 1, wherein a bladder is interposed between the green tire and the rigid ring. 3. The method for vulcanizing and molding a pneumatic tire according to claim 1, wherein after the sector is completely closed, the rigid ring is reduced in diameter and separated from the green tire to perform vulcanization molding. 4. A vulcanizing and molding apparatus for a pneumatic tire in which a central mechanism having a pair of vertically movable clamp rings is disposed on an inner peripheral side of a plurality of tread molding sectors divided in a circumferential direction. A rigid ring that can be expanded and contracted in the horizontal direction is connected between a pair of clamp rings via a link mechanism, and at the position where the upper clamp ring is most lowered, the rigid ring has an outer diameter substantially equal to the sector inner diameter when fully closed. An apparatus for vulcanizing and molding a pneumatic tire that holds an inner peripheral surface of a molded green tire. 5. The apparatus for vulcanizing and molding a pneumatic tire according to claim 4, wherein a bladder is arranged on an outer peripheral side of said rigid ring. 6. The vulcanization and molding apparatus for a pneumatic tire according to claim 4, wherein the rigid ring is reduced in diameter and separated from the green tire after the sector is completely closed. 7. A pair of upper and lower clamp rings are provided with a hollow portion, and a vertically slidable piston is provided in the hollow portion, and the piston is constantly urged inward to be connected to the piston. Into the space filled with the pressurized heating fluid between the pair of upper and lower clamp rings, communicates the space with the hollow portion, and pressurizes and heats the fluid into the hollow portion during vulcanization. The pressure of the fluid causes the rod to be in a sunk state, the base end of the link mechanism is connected to the rod, and the rigid ring is reduced in diameter when the rod is in a sunk state so as to be separated from the green tire. 7. The vulcanization molding apparatus for a pneumatic tire according to 6.