JP2003039436A - Method for vulcanizing tire and vulcanization mold used in the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent rubber from being caught between tread segments. SOLUTION: When a green tire is vulcanized by a vulcanization mold having a pair of side molds and a plurality of segments 3a and 3b, in advance of the clamping displacement of the side molds, the contraction displacement of the segments 3a and 3b is done by forming groups of segments and bringing each group into contact with the green tire with timing staggered, and the contraction displacement of the segment 3b of a group contacting the green tire finally is done while an end face 7a in the circumferential direction is contacted slidably with the segment 3a of another group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of vulcanizing a tire by a so-called split mold, in which a tread ring is divided into a plurality of segments that can be respectively expanded and contracted in the radial direction, and a vulcanization mold used for the method. It is about.

[0002]

2. Description of the Related Art When vulcanizing and molding a raw tire with a pair of side molds and a vulcanizing die having a plurality of tread segments each of which expands and contracts, a raw tire placed in the die is vulcanized. On the other hand, under the posture in which the paired side molds are pre-tightened and displaced, the diameters of the tread segments are simultaneously reduced by the cams provided on the outer ring at the same speed, and all the tread segments are produced. It has heretofore been widely and generally made to make contact with the circumferential surface of a tire almost simultaneously.

[0003]

Such near-simultaneous contact of all tread segments with the green tire circumference causes the green tire to be pressed against the molding surface of the vulcanization mold with the bladder contained therein. There is no particular problem in the conventional bladder vulcanization method.

However, this conventional method of simultaneously reducing the diameters of all tread segments at a constant velocity and simultaneously contacting the raw tire is performed on a rigid core having an outer peripheral surface shape corresponding to the inner peripheral surface shape of the product tire. When used for vulcanization molding of a molded raw tire, in particular, that the outer diameter of the raw tire is that of the product tire, in other words, it is almost the same as the inner diameter of the tread molding surface of the vulcanization mold. Due to this, when pushing the tread segments, in particular, the convex portions of those tread segments into the raw tire at the same time during the diameter reduction displacement of the tread segment, the raw gap is generated in the small gap between the adjacent tread segments. The protruding rubber of the tire becomes pinched, which becomes so-called jammed rubber and causes product defects.
There is a problem that the mold is deformed or damaged due to the mold closing in the presence of the rubber.

The similar rubber biting also occurs in a minute gap between the tread segment and the side mold when the tread segment is contractively displaced with respect to the side mold in the tightened posture. was there.

The present invention has been made in view of the above problems, and an object thereof is a green tire molded on a rigid core and having a shape and dimensions very similar to those of the product tire. Occurrence of rubber bite as described above in the vulcanization molding, among them, especially between the tread segment or, between the tread segment and the side mold vulcanization method of the tire which can effectively prevent the occurrence of rubber bite and. It is to provide a vulcanization mold used for it.

[0007]

A method of vulcanizing a tire according to the present invention is to vulcanize a raw tire with a vulcanizing mold having a pair of side molds and a plurality of tread segments each of which expands and contracts. Before, or after the tightening displacement of the side mold, the diameter-reducing displacement of a plurality of tread segments is brought into contact with the raw tire by shifting the timing for each tread segment as a group. In addition to the above, the diameter reduction displacement of the tread segment of the group that comes into final contact with the tire is performed while sliding the circumferential end faces of the tread segments of the other groups.

According to this method, the rubber extruded in the circumferential direction of the tread segments that come into contact with the peripheral surface of the raw tire first comes into contact with the peripheral surface of the raw tire in a group that comes into contact last. Based on the diameter reduction displacement of one tread segment under sliding contact with the adjacent tread segment, it is sufficiently pushed inward and deformed in the radial direction, which effectively prevents rubber from remaining between tread segments. Therefore, it is possible to effectively prevent the protruding rubber from being caught between the segments, improve the appearance quality of the product tire, and also eliminate the risk of damage to the vulcanization mold.

Further, between the side mold and the tread segment, depending on their relative structure, the tightening displacement of the side mold can be changed with respect to each tread segment in the diameter-reduced posture in the radial outer peripheral surface of the side mold. It is preferable to perform the sliding contact with each other or to perform the diameter reduction displacement of the plurality of tread segments while sliding the side surface of the tread segment against the side mold in the tightened posture.

According to the former, under the action of the tread segment, the rubber extruded in the width direction of the raw tire can be sufficiently pushed back and deformed to the proper position on the inner side in the width direction by the side mold slidingly contacting the segment. Further, according to the latter, the rubber extruded outward in the radial direction of the raw tire by the action of the side mold can be pushed back and deformed inward in the radial direction by the sliding contact diameter reduction displacement of the tread segment. Also, it is possible to effectively prevent the rubber from being caught between the tread segment and the side mold, to improve the appearance of the product, and to more fully eliminate the risk of damage to the mold.

Another vulcanizing method according to the present invention is to vulcanize a green tire with a vulcanizing mold having a pair of side molds and a plurality of tread segments each of which expands and contracts. Prior to or after tightening displacement, the diameter reduction displacement of multiple tread segments is performed with several tread segments as a group, with different diameter reduction speeds for each group. The segment is made to reach the diameter reduction limit position at the same time.

In this method, although the above-mentioned sliding contact of the circumferential end faces of the tread segments does not occur, the diameter reduction displacement starting positions of the tread segments for each group are made different from each other and the tread segments are different for each group. By differentiating the diameter reduction speed, the relative distance between adjacent segments when they come into contact with the raw tire is advantageously narrowed compared to the case where all tread segments are reduced at a constant speed. As a result, it is also possible to suppress the occurrence of rubber bite.

Further, the vulcanization mold used for carrying out such a method comprises a pair of side molds and a plurality of tread segments each of which expands and contracts, and each tread located radially. A part of the segment is a substantially fan-shaped segment whose circumferential length gradually increases outward in the radial direction, and the remaining tread segments have a constant circumferential length inside and outside in the radial direction,
In addition, each of the plurality of tread segments has an equal length segment whose circumferential end faces are parallel to the expansion / contraction displacement direction and is also parallel to the circumferential end faces of the adjacent tread segments, and each of the plurality of tread segments is configured to move forward / backward. It is connected to.

According to this, in the vulcanization molding of the green tire, each of the substantially fan-shaped segments is first brought into contact with the peripheral surface of the green tire under the action of the advancing / retreating drive mechanism, and thereafter, the isometric length is obtained. By diametrically displacing a segment under sliding contact with an adjacent segment and abutting it on the tire peripheral surface with a delay,
The above method can be carried out easily and reliably. Here, when the substantially fan-shaped segments and the equal-length segments are alternately arranged in the circumferential direction, the uniformity in the circumferential direction can be further improved.

By the way, the advancing / retreating drive mechanism of each segment may be a cylinder or a gear mechanism, and in any of these, each tread segment is subjected to a diameter reduction displacement at a required timing and at a required speed. Therefore, the above method can be carried out smoothly and surely.

Further, when the advancing / retreating drive mechanism is a cam provided on the outer ring common to all the tread segments, in carrying out the other method according to the present invention,
It is possible to reduce the diameter of one group of a plurality of tread segments, for example, an equal length segment, at a high speed, and to reduce the diameter of another group, for example, a fan-shaped segment, at a low speed, thereby providing the above-described effects. And the method can be carried out with less equipment and running costs.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing an embodiment of an apparatus according to the present invention with respect to a half part of a vulcanizing mold. , 3 indicates one of a plurality of tread segments that are respectively expanded and contracted.

Here, the upper side mold 1 is moved up and down together with the holder 4 with respect to the lower side mold 2 to be opened and tightened, and each tread segment 3 is moved.
Is expanded / contracted integrally with the sector 6 holding the segment 3 by the advancing / retreating drive mechanism which is the hydraulic cylinder 5 here.

By the way, as shown in the schematic plan view of FIG. 2, a plurality of tread segments here are arranged such that a part of each of the tread segments located radially is lengthened in the circumferential direction toward the outer side in the radial direction. Is a substantially fan-shaped segment 3a, and the remaining tread segments are arranged such that their circumferential end faces 7a are parallel to the expansion / contraction displacement direction indicated by the arrow A in the figure, and the adjacent tread segment, in the figure The segment 3a is formed into an equal length segment 3b which is parallel to the end face 7b in the circumferential direction of the segment 3a.
b are arranged alternately in the circumferential direction.

When a plurality of segments are constructed in this way, as shown in FIG. 2 (b), all of the substantially fan-shaped segments 3a are pre-reduced and displaced to the limit position, and then the other segments are formed. When the uniform length segment 3b is radially reduced to the limit position, the circumferential end faces 7a of the equal length segments 3b are brought into sliding contact with the circumferential end faces 7b of the adjacent segments 3a.

Therefore, when the green tire is vulcanized and molded using the vulcanization mold shown in FIG. 1, for example, the rigid core C is used.
As shown in FIG. 3 (a), the raw tire G molded above is positioned on the lower side mold 2 together with the rigid core C of the raw tire G.
To a position at a slight distance from each other, whereupon all of the substantially fan-shaped segments 3a are advanced and displaced to their diameter reduction limit positions by the respective hydraulic cylinders 5 and brought into contact with the peripheral surface of the raw tire G, Then segment 3a
The respective equal-length segments 3b located between them are advanced and displaced by the respective other hydraulic cylinders 5 under sliding contact with the circumferential end faces 7b of the segments 3a to the diameter reduction limit position.

According to this, the substantially fan-shaped segment 3a
The peripheral surface rubber of the raw tire G extruded in the circumferential direction of the segment 3a due to the radial contraction displacement of the tip of the other end of the raw tire G is Since the segments 3a are sufficiently pushed inward in the radial direction based on the sliding contact with the respective circumferential end faces 7b, the segments 3a are not deformed.
The rubber is sufficiently prevented from being caught between a and 3b.

After that, as shown in FIG. 3 (b), the outer peripheral surface of the upper side mold 1 is slidably brought into contact with the inner peripheral surfaces of the respective segments 3a, 3b for tightening displacement. According to this, the rubber extruded to the outer side in the width direction of the tire by the respective segments 3a and 3b in the diameter-reduced posture can be appropriately pushed and deformed to the inner side in the width direction with the upper side mold 1, and It is possible to prevent the rubber from being caught between the segments 3a and 3b and the upper side mold 1.

Here, the relative structure of the segments 3a and 3b and the side molds 1 and 2 is as shown in FIG. 4, for example, when the segments 3a and 3b are reduced in diameter and displaced.
When both side surfaces of each segment 3a, 3b are in sliding contact with mutually facing surfaces of the side molds 1, 2 in the tightened posture, the segments 3a, 3b are displaced after the side molds 1, 2 are tightened and displaced. By diametrically displacing, the rubber extruded outward in the radial direction by the side molds 1 and 2 can be deformed by being pushed inward in the radial direction by the segments 3a and 3b. Can be effectively prevented.

By the way, in the case of using the vulcanizing mold shown in FIG. 1, more preferably, as shown in FIG.
With the upper and lower side molds 1 and 2 both positioned at a predetermined distance from the raw tire G that is positioned, the respective segments 3a and 3b are reduced in diameter and displaced in a required order, and then, as shown in FIG. As shown in (b), the upper and lower side molds 1 and 2 are tightened and displaced. According to this, not only the rubber extruded to the upper side mold side by the diameter reduction displacement of each segment 3a, 3b, but also the rubber extruded to the lower side mold side,
It can be effectively pushed and deformed inward in the tire width direction.

FIG. 6 is a view showing another embodiment of the vulcanization mold, in which the forward / backward drive mechanism of each segment 3a, 3b is a gear mechanism 8 consisting of a rack and pinion. Also by this, each gear mechanism 8 can displace the segments 3a and 3b at a desired timing and at a required speed, so that the same action and effect as in the previous case can be brought about. Even when this apparatus is used, preferably, the raw tire G is positioned and arranged at a slight distance from the lower side mold 2 as shown in FIG.

FIG. 7 is a view showing still another embodiment, in which a common outer ring 9 is provided with a cam surface 9a for the substantially fan-shaped segment 3a and an equal length segment 3b.
And the taper angles θ1 and θ2 of these cam surfaces with respect to the vertical direction of the outer ring 9,
The fan-shaped segment 3a is made smaller, the equal-length segment 3b is made larger, and the diameter reduction start point of the equal-length segment 3b is positioned radially outside of the other segment 3a. According to this, although the cam 9b fitted and connected to the segment 3b causes the segment 3b to be reduced in diameter and deformed at a faster speed than the other segments 3a, both of the segments 3a and 3b are simultaneously brought to the reduced diameter limit position. Will be reached.

Therefore, here, the fan-shaped segment 3a is used.
It is possible to effectively reduce the gap between the raw tire G and the other segment 3b when the raw tire G comes into contact with the raw tire G, as compared with the conventional technique, and effectively prevent the rubber from being caught.

The vulcanizing mold shown in FIGS. 6 and 7 also has a structure in which the segments 3a and 3b are brought into sliding contact with the side molds 1 and 2 which have been pre-squeezed and displaced, as described in FIG. You can also

[0030]

As described above, according to the present invention, even if the raw tire is molded on the rigid core, it is possible to effectively trap the rubber between the tread segments or between the tread segment and the side mold. By so doing, it is possible to improve the appearance quality of the product tire and sufficiently prevent damage to the vulcanization mold.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of an apparatus according to the present invention.

FIG. 2 is a schematic line plan view of a plurality of tread segments.

FIG. 3 is a process drawing of one vulcanizing method.

FIG. 4 is a vertical cross-sectional view showing a modified example of a vulcanizing mold.

FIG. 5 is a process drawing showing another vulcanizing method.

FIG. 6 is a vertical cross-sectional view showing another embodiment of the device.

FIG. 7 is a vertical sectional view showing still another embodiment of the device.

[Explanation of symbols]

1 Upper side mold 2 Lower side mold 3 tread segments 3a Almost fan-shaped segment 3b isometric segment 4 holder 5 hydraulic cylinder 6 sectors 7a, 7b circumferential end faces 8 gear mechanism 9 Outer ring A Expansion / contraction displacement direction C Rigid core G raw tire

Claims (8)

[Claims] 1. When vulcanizing a raw tire with a vulcanization mold comprising a pair of side molds and a plurality of tread segments each of which expands and contracts, the side molds are tightened prior to or during tightening displacement. After displacement, reduce the diameter of multiple tread segments.
Some tread segments as a group, by shifting the timing for each group and making contact with the raw tire, and reducing the diameter reduction displacement of the tread segment of the group that comes into final contact with the raw tire to the tread segments of other groups. A method of vulcanizing a tire that is carried out while sliding the end faces in the circumferential direction. 2. A vulcanization mold comprising a pair of side molds and a plurality of tread segments, each of which expands and contracts, to vulcanize a raw tire. A tire vulcanization method in which the radial outer peripheral surface of the side mold is in sliding contact with each tread segment. 3. A vulcanization mold comprising a pair of side molds and a plurality of tread segments each of which expands and contracts to vulcanize a raw tire. ,
A method of vulcanizing a tire that is carried out while sliding the side surface of the tread segment against the side mold in the tightened position. 4. A vulcanization mold comprising a pair of side molds and a plurality of tread segments each of which expands and contracts. After displacement, reduce the diameter of multiple tread segments.
A method of vulcanizing a tire in which several tread segments are set as a group and the diameter reduction speed is made different for each group, and all the tread segments reach the diameter reduction limit position at the same time. 5. A vulcanization mold comprising a pair of side molds and a plurality of tread segments each of which expands and contracts, wherein a part of each tread segment located radially is radially outwardly. Toward the end of each tread segment is parallel to the expansion and contraction displacement direction, and the remaining tread segment is parallel to the circumferential end face of the adjacent tread segment, etc. A vulcanization mold that is a long segment and that each of a plurality of tread segments is connected to an advancing and retracting drive mechanism that controls expansion and contraction displacement. 6. The vulcanization mold according to claim 5, wherein substantially fan-shaped segments and equal-length segments are alternately arranged in the circumferential direction. 7. The vulcanizing mold according to claim 5, wherein the advancing / retreating drive mechanism is a cylinder or a gear mechanism. 8. The vulcanizing mold according to claim 5, wherein the advancing / retreating drive mechanism is a cam provided on the outer ring.