JPH0645142B2 - Tire vulcanization mold - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vulcanization mold for automobile tires.

(Prior Art) As a mold for vulcanizing an automobile tire, an upper mold and a lower mold arranged above and below to mold a carcass portion of the tire,
It consists of a plurality of circumferential segments arranged in a ring shape between the upper mold and the lower mold for molding the tread portion of the tire, and these circumferential segments project downward on the outer peripheral portion of the upper mold. It is attached to the inner surface of the tapered ring that has a downwardly widening taper so that it can slide up and down, and the lower surface of the circumferential segment contacts the sliding guide surface on the outer circumference of the lower mold and slides inward in the radial direction as the upper mold descends. There is known a split mold which is designed to do so. Then, in this split mold, when the upper die is positioned above, the lower beat portion of the green tire is attached to the center portion of the lower die, and then the upper die is lowered, the center portion of the upper die is By contacting the upper beat part of the green tire, the green tire is compressed in the vertical direction, and as the upper mold descends, the lower surface of the circumferential segment contacts the sliding guide surface on the outer circumference of the lower mold. The circumferential segment slides inward in the radial direction to form a tread groove in the tread portion of the green tire.

(Problems to be Solved by the Invention) However, in the conventional split mold, the lower surface of the circumferential segment slides inward after the lower surface of the circumferential segment comes into contact with the sliding guide surface of the outer circumference of the lower mold, so that the lower mold moves downward. When the green tire is compressed in the up-and-down direction due to the above, that is, when the tread portion of the green tire is descending, the circumferential segment slides horizontally along the slide guide surface on the tread portion. Press against the green tire. In other words, the circumferential segments are pressed against each other in a state where their height is lower than that of the tread of the green tire. Therefore, there is a problem that the smooth lowering of the tread portion is hindered, and therefore, the upper shoulder portion of the tread portion of the product tire is formed thicker than the lower shoulder portion, which causes a problem of uniformity. Then, as the bone of the mold surface of the circumferential segment (protrusion corresponding to the groove bottom of the tread groove) is set higher in order to deepen the tread groove of the tire, there is a problem that the above-mentioned uniformity defect becomes more serious.

The present invention, when the height of the circumferential segment coincides with the height of the tread portion of the green tire while the circumferential segment is descending, the circumferential segment slides in the horizontal direction and comes into pressure contact with the tread of the green tire. With this, it is possible to prevent the occurrence of uniformity defects.

(Means for Solving the Problem) The tire vulcanizing mold of the present invention is for molding the upper and lower molds arranged above and below for molding the carcass part of the tire, and for molding the tread part of the tire. A taper ring having a plurality of circumferential segments arranged in a ring shape between the upper die and the lower die, and the circumferential segments having a downwardly widening taper projecting downward on the outer peripheral portion of the upper die. A tire vulcanizate that is slidably mounted on the inner surface of the lower mold and the lower surface of the circumferential segment contacts the sliding guide surface on the outer circumference of the lower mold and slides radially inward as the upper mold descends. In the mold, a vertical hole corresponding to the circumferential segment is drilled on the sliding guide surface on the outer periphery of the lower mold, and a push-up block is loaded in the vertical hole so that the push-up block can be retracted. Push up The upper end of the elastic block is elastically projected from the sliding guide surface.

(Operation) When a green tire is attached to the lower mold and the upper mold is lowered,
As it descends, the upper mold contacts the green tire as in the conventional case, and then the green tire is compressed. On the other hand, the circumferential segment also starts descending as if it hung from the taper ring on the outer periphery of the upper die as in the conventional case, but if the lower surface of the circumferential segment contacts the upper surface of the lifting block during the descent, the circumferential segment The descent is stopped. In other words, the circumferential segment is pushed upwards with respect to the tapering ring which continues to descend. As a result, the circumferential segment begins to slide radially inward.

When the circumferential segment slides inward in this way, the tread surface of the circumferential segment comes into contact with the tread surface of the green tire, and the bone portion of the mold surface (the portion corresponding to the groove bottom of the tire tread) bites. start. On the other hand, since the tread portion of the green tire is lowered by the lowering of the upper mold, the lowering of the tread portion lowers the circumferential segment meshing with the tread portion against the upward biasing force of the push-up block. That is, the circumferential segment slides inward in the radial direction while descending to form a pattern on the tread portion of the green tire. Then, the inward sliding of the circumferential segment is completed when the lowering of the upper mold is completed, and the mold is completely closed.

The circumferential segment of the present invention starts sliding inward when it is at a high position away from the sliding guide surface of the lower mold, and when this circumferential segment is pressed against the green tire, the circumferential segment together with the tread portion of the green tire The descent starts, and the sliding start timing is determined by the protruding height of the lifting block. Therefore, the protruding height of the lifting block is set so that the lower surface of the circumferential segment starts contact with the lifting block when the height of the tread portion of the green tire matches the height of the mold surface of the circumferential segment. By doing so, the deviation of the mold surface of the circumferential segment with respect to the tread portion of the green tire is eliminated.

(Embodiment) In FIG. 1, reference numeral 1 is an upper mold that can be raised and lowered, and is formed in a donut shape. An upper bead receiver 3 is fixed along the lower surface of a center hole 2 thereof, and along an outer peripheral portion on the opposite side. A taper ring 4 is projected downward, and a plurality of circumferential segments 5 arranged at equal intervals are attached to the inner surface of the taper ring 5 so as to be vertically slidable. The circumferential segment 5 has a vertical key 6 on its outer surface, and this key 6 fits into a key groove on the inner surface of the taper ring 4 and slides. The inner side surface 7 of the circumferential segment 5 is formed as a mold surface for forming a tread groove on the tread surface T of the green tire G.

A lower donut-shaped mold 8 is provided below the upper mold 1,
A lower bead receiving member 10 is fixed along the upper surface of the central hole 9, and a sliding guide surface 11 for the circumferential segment 5 is formed on the opposite outer peripheral portion. Then, a vertical hole 12 having a circular cross section is formed in the sliding guide surface 11 so as to correspond to the circumferential segment 5. The upper half of the vertical hole 12 is formed to have a smaller diameter than the lower half thereof, and a cylindrical push-up block 13 is vertically slidably mounted in the upper half of the small diameter.
The push-up block 13 has an upper end closed by a cover plate 14,
A flange 15 is integrally formed on the outer periphery of the lower end, and when the flange 15 is inserted into the vertical hole 12 from below, the flange 15 is formed in a step portion between the upper half portion and the lower half portion of the vertical hole 12. It comes in contact with and stops. Then, the compression coil spring 16 is inserted under the push-up block 13,
A receiving plate 17 in which the lower end of the vertical hole 12 is fixed to the lower surface of the lower mold 8.
And the compression coil spring 16 is compressed and held.

In the above structure, the bead portion of the lower surface of the green tire G is fitted to the bead receiver 10 of the lower mold 8 with the upper mold 1 standing by upward (see FIG. 1), and then the upper mold 1 is replaced. Lower it. At this time, the circumferential segment 5 is the upper die 1
It descends in a state of being suspended from the taper ring 4 on the outer periphery of. As the upper mold 1 descends, as shown in FIG.
The bead receiver 3 of the upper mold 1 is fitted to the bead portion of the upper surface of the green tire G, and the compression of the green tie G starts, whereby the tread portion T of the green tire G descends at a speed half that of the upper mold 1. Start. Then, the circumferential segment 5
When the lower surface of the tire reaches the upper surface of the push-up block 13, the height of the circumferential segment 5 and the height of the tread T of the green tire G become substantially equal to each other by setting, and the circumferential segment 5 is stopped from descending to move radially inward. Starts to slide, and the molding surface 7 of the circumferential segment 5 is pressed against the tread portion T of the green tire G to start molding. The circumferential segment 5 is the compression coil spring 1 of the push-up block 13.
6 descends against the elastic force of 6 and slides inward in the radial direction, and finally, as shown in FIG.
Is sunk into the vertical hole 12 on the outer periphery of the lower die 8, and the upper die 1, the lower die 8 and the circumferential segment 5 are closed, and the molding is completed.

(Effect of the Invention) The present invention has a vertical guide hole corresponding to a circumferential segment formed in a sliding guide surface on the outer periphery of a lower die, and a push-up block is loaded in the vertical hole so that the push-up block can be retracted. Since the upper end of the push-up block is elastically protruded from the sliding guide surface by pushing upward with, the upper die is lowered in the same manner as in the conventional case, so that the circumferential segment The lower surface of the push-up block comes into contact with the upper surface of the push-up block and starts to slide inward in the radial direction, thereby making contact with the tread of the green tire, and then pressing down the tread while descending together with the green tire. ,
Since the start time of the inward sliding of the circumferential segment can be set by the height of the lifting block, when the height of the tread of the green tire matches the height of the mold surface of the circumferential segment, the circumferential direction It is possible to slide the segment inward, so it is possible to bite the mold surface of the circumferential segment into the above tread with the height of the mold surface of the circumferential segment matching the height of the tread of the green tire. It is possible to improve the uniformity of the product tire, and moreover, it is only necessary to open a vertical hole in the sliding guide surface on the outer periphery of the lower mold and load the push-up block into this vertical hole to urge the existing split mold. It is also easy to modify.

[Brief description of drawings]

1 is a sectional view of an embodiment of the present invention, FIG. 2 and FIG.
The drawing is a sectional view for explaining the operation of the apparatus shown in FIG. G: green tire, 1: upper model, 4: taper ring,
5: circumferential segment, 8: lower mold, 11: sliding guide surface,
12: vertical hole, 13: push-up block, 16: compression coil spring.

Claims (1)

[Claims] 1. A ring-shaped arrangement between an upper die and a lower die arranged to form a carcass portion of a tire and an upper die and a lower die arranged to form a tread portion of a tire. A plurality of circumferential segments, which are attached to the inner surface of a taper ring having a downwardly widening taper projecting downward on the outer peripheral portion of the upper die so as to be vertically slidable. In a tire vulcanizing mold formed so that the lower surface of the circumferential segment comes into contact with the sliding guide surface on the outer periphery of the lower mold and slides inward in the radial direction as it descends. A vertical hole corresponding to the circumferential segment is drilled, and a push-up block is freely inserted into and retracted from this vertical hole, and the push-up block is biased upward by a spring to slide and guide the upper end of the push-up block. Elastically protrudes from the surface Tire vulcanizing mold, characterized in that allowed.