JPH1134060A - Tire molds and pneumatic tires - Google Patents

Abstract

(57) [Problem] To quickly exhaust air to the outside at an early stage of a vulcanization process while reducing the number of vent holes. Kind Code: A1 A tire forming die provided with groove forming protrusions for partitioning a block of a tire on tread forming surfaces.
The main air vent formed at the center of the block forming surfaces 13X and 23X in at least the center region X of the block forming surfaces 13 and 23 for forming the block surfaces partitioned by 2 An auxiliary air vent groove 5 communicating with the groove 3 or communicating with a vent hole 4 formed in the block molding surfaces 11 and 21 extends in the tire width direction and is adjacent to the auxiliary air vent groove 5. The auxiliary protrusions 6 extending side by side are arranged side by side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding a tire and a pneumatic tire, and more particularly to a method for rapidly discharging air to the outside while reducing the number of vent holes from which air is released during vulcanization. TECHNICAL FIELD The present invention relates to a tire molding die capable of performing the above-mentioned operations and a pneumatic tire molded using the same.

[0002]

2. Description of the Related Art For example, a pneumatic tire for a large construction vehicle for traveling on rough terrain has a thick tread portion, and a large block is defined on the tread surface by a circumferential groove and a lateral groove having a large groove depth. Is formed. This thick tread portion is formed by continuously winding a rubber strip in multiple stages during green tire molding. As described above, in the green tire in which the tread portion is formed by the strip wind method, the space between the rubber strips and the uneven portion on the surface thereof is a place for the air pool. If this air is not quickly discharged in the initial stage of the vulcanization process, the tread surface after vulcanization will be in a pseudo-adhesion state, which will cause a tread crack failure.

Conventionally, in a mold for molding such a pneumatic tire for a large construction vehicle, a large number of vent holes for venting air are provided on a block molding surface, so that air is quickly discharged at an early stage of vulcanization. Like that. Especially,
Since air tends to remain in the center region bulging outward from the shoulder region for molding the shoulder portion of the tire, many vent holes are formed on the block molding surface in the center region.

[0004] However, when a large number of vent holes are provided in this manner, rubber flowing out of the vent holes forms a beard-like spew on the tire surface after vulcanization, forming a large number of forests, which makes trimming work in the finishing process complicated. There was a problem that. Further, since rubber flows out from many vent holes, a large amount of rubber is wasted.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a tire molding die and a pneumatic tire capable of rapidly discharging air to the outside at an early stage of a vulcanization process while reducing the number of vent holes. To provide tires.

[0006]

According to the present invention, there is provided a tire molding die having a groove forming projection for partitioning and molding a tire block on a tread molding surface. At the center of the block forming surface in at least the center region of the block forming surface for forming the block surface partitioned by the groove forming protrusions,
An auxiliary air vent groove communicating with a main air vent groove formed on the peripheral edge of the block molding surface or communicating with a vent hole formed in the block molding surface extends in the tire width direction, and the auxiliary air vent groove communicates with the auxiliary air vent groove. An auxiliary protrusion extending adjacent to the air vent groove is provided side by side.

In the pneumatic tire of the present invention, a circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction are provided on the tread surface, and a large number of blocks are defined by the circumferential groove and the lateral groove. The tire includes a concave portion and a convex portion extending adjacent to each other in the tire width direction at a central portion of a block surface in at least a center region of the tread surface.

As described above, according to the present invention, at least the center portion of the block forming surface in the center region extends in the tire width direction and communicates with the main air vent groove on the periphery of the block forming surface, or The auxiliary air vent groove communicating with the vent hole is provided, and the auxiliary convex portion is extended adjacent to the auxiliary air vent groove, so that the rubber of the tread portion flowing in the tire circumferential direction at the initial stage of vulcanization has the auxiliary convex portion. At the same time, the flow is disturbed, whereby the air inside is pushed out and easily escapes to the auxiliary air vent groove. Therefore, air can be quickly discharged to the outside without providing many vent holes on the block molding surface as in the related art.

[0009]

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 a state in which a green tire is set in a tire molding die of the present invention, where M is a die, T is a green tire, and B is a bladder. The mold M is composed of a pair of upper and lower annular upper dies 1 and lower dies 2, and the tread molding surface 1 of the upper dies 1 and the lower dies 2.
Groove forming protrusions 12 and 22 for partitioning and forming the block of the tire are formed on the tires 1 and 21, respectively. Z is an interface between the upper mold 1 and the lower mold 2.

[0010] As shown in FIG.
1 and 21, each block forming surface 1 for forming a block surface defined by the groove forming protrusions 12 and 22.
A main air vent groove 3 is formed in the peripheral edge of each of the first and second air vents 3 and 23.
A plurality of vent holes 4 are formed in each of the block forming surfaces 13 and 23, and the main air vent grooves 3 communicate with the vent holes 4.

Each of the block forming surfaces 13X and 23X located in the center region X is provided with one auxiliary air vent groove 5 extending in the direction of the tire width (vertical direction of the mold). The auxiliary air vent groove 5 has both ends communicating with the main air vent groove 3 across the central part (central part in the circumferential direction) of the block forming surface. One auxiliary convex portion 6 is provided adjacent to the auxiliary air vent groove 5. The auxiliary protrusion 6 extends along the auxiliary air release groove 5 so as to cross the block forming surface.

According to the mold M, a green tire T such as a pneumatic tire for a large construction vehicle for traveling on a rough terrain having a thick tread formed by a strip wind method is set as shown in FIG. When vulcanization is carried out by the usual method using a rubber, the rubber in the tread portion flows so as to meander greatly at the block in the tire circumferential direction, but the flow extends so as to cross the block forming surface in the tire width direction. The projection 6 is disturbed by hitting. For this reason, the air inside the rubber strips and the air accumulated in the uneven portions thereof is pushed out and escapes into the auxiliary air vent groove 5 extending in the tire width direction. The air escaping into the auxiliary air bleed groove 5 flows out into the main air bleed groove 3 on the periphery and is discharged to the outside through the vent hole 4. Therefore, as shown in FIG.
About four vent holes 4 allow air to be quickly discharged to the outside at the initial stage of the vulcanization process, thereby facilitating trimming of the spew and greatly reducing the amount of wasted rubber. Becomes possible.

FIG. 4 shows a pneumatic tire manufactured by using the above-described mold, which is obtained by performing a spew trim operation in finishing. A plurality of circumferential grooves 32 extending in the tire circumferential direction T in a zigzag manner and a lateral groove 33 extending in the tire width direction are provided on the toret surface 31, and a number of blocks 34 are defined by the circumferential grooves and the 32 lateral grooves 33. Is formed. CL is a tire center line.

A center region X between both outer circumferential grooves 32
A convex portion 35 and a concave portion 36 formed by the auxiliary air vent groove 5 and the auxiliary convex portion 6 extending adjacent to each other in the tire width direction are provided side by side on the surface of the block 34X located at 1. The convex portion 35 and the concave portion 36 are provided so as to cross the central portion of the block 34X in the tire circumferential direction in the tire width direction. Also, on the periphery of the surface of the block 34X,
A convex portion 37 formed by the main air vent groove 3 is formed. Thus, the tire molded using the mold M of the present invention has a convex portion 3 extending adjacent to the center of the block surface in the center region X1 of the tread surface 31 in the tire width direction.
5 and the concave portion 36 are arranged side by side.

In the present invention, the width w and the depth d of the auxiliary air vent groove 5 can both be 0.5 to 3 mm. Preferably, it should be 0.7 to 1.5 mm. The cross-sectional shape can be an arc or a polygon. The height h of the auxiliary convex portion 6 can be equal to or greater than the groove depth of the auxiliary air vent groove 5 and equal to or less than 5 mm. The width v of the auxiliary protrusion 6 is preferably 0.5 to 3 mm, which is the same as the width of the auxiliary air vent groove 5.

As shown in FIG. 5, the auxiliary air vent groove 5
It may be provided on both sides of the auxiliary projection 6. In this case, the molded tire has a configuration in which the convex portions 35 are provided on both sides of the concave portion 36, respectively. Further, the auxiliary air vent groove 5 and the auxiliary convex portion 6 are arranged in parallel at each one position on the block forming surface of the center region X. However, if the block becomes larger, it may be provided at more positions. In the present invention, at least one portion may be provided as shown in FIG.

The auxiliary air vent groove 5 and the auxiliary convex portion 6 are
In the above embodiment, the block forming surface 1 of the center region X
Although they are provided only on the 3X and 23X, they may be provided on the block forming surfaces 13Y and 23Y of the shoulder region Y for molding the tire shoulder portions on both sides in the same manner as described above. In that case, the tire formed in the block 34Y of the shoulder region Y1 has the convex portion 35 and the concave portion 3 as well.
6 are arranged side by side.

The auxiliary air vent groove 5 is, as shown in FIG.
When the vent holes 4 are provided above and below the tire width direction, both ends may be directly connected to the vent holes 4. Also, the case where the mold M has a pair of upper and lower halves including an upper mold 1 and a lower mold 2 has been described, but an upper mold for molding one sidewall portion of the tire and another sidewall. Lower mold to mold the part,
And a plurality of sectors for forming a tread portion of a tire.

The mold of the present invention can be preferably used for vulcanizing a pneumatic tire for a large construction vehicle for traveling on rough terrain, in which a tread portion is formed by a strip wind method, but it is a matter of course that the present invention is not limited to this. Not done.

[0020]

As described above, the tire molding die according to the present invention has a main air vent groove extending at least in the center portion of the block molding surface in the center region in the tire width direction and formed on the peripheral edge of the block molding surface. An auxiliary air vent groove communicating with the vent hole formed in the block molding surface is arranged adjacent to the auxiliary convex portion, so that the flow of the tread rubber in the tire circumferential direction during vulcanization is disturbed. Since the internal air can be easily released into the auxiliary air vent groove, the air can be quickly discharged to the outside at the initial stage of the vulcanization process while reducing the number of vent holes.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part showing an example of a tire molding die of the present invention in a state where a green tire and a bladder are set.

FIG. 2 is an arrow view showing a main part of a tread portion forming surface viewed from the direction of arrow A in FIG. 1;

FIG. 3 is an enlarged sectional view taken along the line CC of FIG. 2;

FIG. 4 is a tread developed view showing a main part of a pneumatic tire manufactured by the mold of FIG. 1;

FIG. 5 is an enlarged sectional view corresponding to FIG. 3, showing another example of the tire molding die of the present invention.

FIG. 6 is an explanatory view of a main part showing still another example of a tire molding die according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Upper die 2 Lower die 3 Main air vent groove 4 Vent hole 5 Auxiliary air vent groove 6 Auxiliary convex portion 11, 21 Tread portion forming surface 12, 22 Groove forming protrusion 13, 23 Block forming surface 31 Tread surface 32 Circumferential direction Groove 33 Lateral groove 34 Block M Mold T Tire circumferential direction X, X1 Center area Y, Y1 Shoulder area

Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 21:00 105: 24 B29L 30:00

Claims (4)

[Claims] 1. A tire forming die provided with a groove forming protrusion for partitioning and forming a tire block on a tread forming surface, wherein a block forming surface for forming a block surface partitioned by the groove forming protrusion. At least the center portion of the block forming surface in the center region is communicated with a main air vent groove formed on the periphery of the block forming surface, or an auxiliary air vent communicating with a vent hole formed on the block forming surface. While extending the groove in the tire width direction,
A tire molding die having auxiliary projections extending adjacent to the auxiliary air vent grooves. 2. The tire molding die according to claim 1, wherein the auxiliary air vent groove is provided on both sides of the auxiliary projection. 3. A pneumatic tire in which a circumferential groove extending in a tire circumferential direction and a lateral groove extending in a tire width direction are provided on a tread surface, and a large number of blocks are defined by the circumferential groove and the lateral groove. A pneumatic tire in which a concave portion and a convex portion extending adjacently in the tire width direction are arranged side by side at least in a central portion of a block surface in a center region. 4. The pneumatic tire according to claim 3, wherein the convex portion is provided on both sides of the concave portion.