JPH10264271A - Mold for forming tire and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for forming a tire in which resistance at time of mold release is reduced and also outward appearance of the fire is enhanced by preventing a block from being broken and to provide a pneumatic tire. SOLUTION: The mold for forming a tire is provided with a plurality of main groove forming frames 2 extended in the circumferential direction of the tire and a plurality of transverse groove forming frames 3 extended in the width direction of the tire. Block forming space 4 is divided and formed by these main groove forming frames 2 and transverse groove forming frames 3. A plurality of sipe forming frames 5 are implanted in the block forming space 4 and also at least a piece of cut 7, through which air is passed but unvulcanized rubber is not passed, is provided in the sipe forming frames 5. The cut 7 is extended from the implantation side end part 5a to the midway part unreached to a ridge side end part 5b.

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 having a sipe in a block, and a pneumatic tire molded by using the mold. The present invention relates to a mold for molding a tire and a pneumatic tire which improve the appearance of a tire by preventing chipping of a block.

[0002]

2. Description of the Related Art Conventionally, in a pneumatic tire for running on snow, a block pattern is used such that a block is divided in a tire circumferential direction by a plurality of sipes. In a mold for molding such a pneumatic tire, each block molding space is divided into a plurality of small block spaces by implanting a sipe molding bone in a block molding space on an inner surface of a mold. In addition, each sipe molding bone is provided with a lateral vent hole communicating with the adjacent small block space, and through this lateral vent hole, air that tends to remain in the small block space is released, and the inner surface of the mold is formed. It is designed to be discharged from the vent hole provided in.

[0003] However, the lateral vent holes provided in the sipe molding bone as described above are usually formed near the tire profile surface in order to completely extract the air.
Unvulcanized rubber flows into the lateral vent hole at the time of tire vulcanization molding, and the rubber is connected to small blocks divided into sipes. The rubber pillars connecting the small blocks generate resistance when the mold is released, and because the rubber pillars are near the tire profile surface, they cause chipping of the blocks and cause deterioration of the tire appearance.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a mold for molding a tire, which is designed to reduce the resistance at the time of release from the mold and to improve the appearance of the tire by preventing chipping of the block. It is to provide a pneumatic tire.

[0005]

According to the present invention, there is provided a tire molding mold according to the present invention, wherein a plurality of main groove molding bones extending in a tire circumferential direction and a plurality of main groove molding bones extending in a tire width direction are formed on an inner surface of a mold. A plurality of lateral groove forming bones are provided, a block forming space is divided and formed by the main groove forming bone and the lateral groove forming bone, a plurality of sipe forming bones are implanted in the block forming space, and a side end portion implanted in the sipe forming bone. At least one air extending halfway from the end to the ridgeline side end, but not through the unvulcanized rubber.

[0006] In this way, at least one air passes through the plurality of sipe molding bones which divide the block molding space by the molding inner surface of the mold so as to extend from the implantation side end to the middle not reaching the ridge side end. By providing cuts that do not allow unvulcanized rubber to pass through, rubber columns connecting small blocks to each other are not formed in the sipe of the vulcanized block. This can improve the appearance of the tire.

Further, the pneumatic tire formed from the mold of the present invention has a good appearance because no block is chipped.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. 1 to 3 illustrate a tire molding mold according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a plurality of sectors divided in the circumferential direction of the tire. These sectors 1 are combined in an annular shape to form a tread of the tire.

A plurality of main groove forming bones 2 extending in the tire circumferential direction and a plurality of lateral groove forming bones 3 extending in the tire width direction are provided on the inner surface of the sector 1. A region surrounded by the lateral groove forming bone 3 is a block forming space 4. Accordingly, a plurality of main groove forming bones 2 are provided on a tread of a tire formed from this mold.
Are formed, and a plurality of lateral groove forming bones 3 are formed.
Are formed, and a plurality of blocks corresponding to the block forming space 4 are divided and formed.

Further, on the inner surface of the block forming space 4, a plurality of sipe forming bones 5 in the width direction of the tire are adjacent to each other.
The plurality of sipe-formed bones 5 are implanted so as to straddle the main groove-formed bones 2 of the book, and divide the block forming space 4 into a plurality of small block spaces in the tire circumferential direction. Each block forming space 4 has a sector 1
Vent holes 6 communicating with the outside of the sector 1 are provided at two front and rear positions on the inner surface of the mold, and air remaining in the mold is discharged through these vent holes 6.

The sipe-formed bone 5 has an implanted end 5a.
At least one notch 7 is provided from the front end to the ridge side end 5b. The slit 7 has a slit width that allows air to pass therethrough, but does not allow unvulcanized rubber to pass through. The extended end of the slit 7 stops in the block forming space 4 and extends to the ridge side end 5b. It is formed so as not to reach, so that the sipe molding bone 5 is not divided. The length S of the cut 7 from the inner surface of the mold is
It is preferable that the height of the sipe molding bone 5 be 50% or less of the height D from the inner surface of the mold. By setting the length S of the cut 7 at 50% or less of the height D of the sipe-formed bone 5, a sufficient strength of the sipe-formed bone 5 can be secured.

In the tire molding mold configured as described above, a plurality of sipe molding bones 5 for dividing the block space into a plurality of small block spaces in the circumferential direction of the tire are implanted on the inner surface of the block molding space 4 and the sipe molding bone is implanted. Molded bone 5
At least one notch 7 extending from the implantation side end 5a to the middle of the ridgeline side end 5b is provided, and the adjacent small block spaces are communicated with each other. Only to reduce the total number.

As described above, the slit width of the cut 7 allows air to pass through but does not substantially allow unvulcanized rubber to pass through, so that the rubber pillar connecting small blocks to each other within the sipe of the vulcanized block. Is not formed. Therefore, the resistance at the time of releasing can be reduced, and the chip appearance can be improved by preventing the block from being chipped.
In addition, since the cut 7 is provided from the implantation side end 5a toward the ridge side end 5b and extends to the tire profile surface, immediately before the unvulcanized rubber is completely filled in the mold. It is possible to discharge air up to.

In the present invention, the slit width of the cut 7 is desirably 0.1 mm or less, preferably 0.05 mm or less, and more preferably 0.03 mm or less.
By making the slit width of the cut 7 narrow as described above, it is possible to allow air to pass through but not substantially pass unvulcanized rubber. In addition, the width of the cut 7 may be appropriately set according to the viscosity of the unvulcanized rubber.

As a method of forming the cut 7 in the sipe-formed bone 5 described above, there are press working, wire cut electric discharge machining, and the like. In the present invention, it is preferable to use press working among these processing. When press working, Fig. 4
As shown in FIG.
The planting side end 5a is sandwiched between 0 and 21 so as to be sheared into a strip shape. When the cut 7 is formed by the shearing process, the slit width is set to 0.1 mm.
It is possible to make the following fine, and the strip-shaped sections can be alternately folded in a staggered manner.

The sipe molding bone 5 is implanted at a predetermined position on the inner surface of the sector 1 when the sector 1 is molded. This sector 1
Is formed by die casting or gypsum casting. In any case, the sipe-formed bone 5
And the mold material is poured in a state where a part of the implantation side end 5a is exposed in the mold.

In the sipe-formed bone 5 pressed as described above, since the strip portion of the implanted end portion 5a keeps protruding from the surface even after the processing, the sector 1 is formed by gypsum casting. In case, sipe molding bone 5
The strips deformed in a zigzag pattern are flattened and then inserted into the mold. On the other hand, when the sector 1 is formed by die-casting, the staggered strip portion of the implantation-side end portion 5a is preferably pressed from both sides by pressing and inserted into the mold of the sector 1.
In this case, a spring effect is exerted by the elastic recovery force of the strip portion, so that the implantation accuracy of the sipe-formed bone 5 can be improved.

The sipe-formed bone 5 only needs to have at least one cut 7, and its shape is not particularly limited. For example, as shown in FIGS.
The number of cuts 7 in the sipe-formed bone 5 may be changed, or the ridge-side end 5b may have irregularities in a side view as shown in FIGS. As shown in FIG. 4G, the cuts 7 are formed in a “C” shape or an inverted “C” shape, or as shown in FIG. 4
The cut 7 is inclined in one direction as shown in (i), the sipe-formed bone 5 is arranged on the tire shoulder as shown in FIG. 4 (j), or the sipe-formed bone 5 is placed as shown in FIG. 4 (k). May be used to divide a part of the block. Note that the thickness of the sipe-formed bone 5 may be uniform or may be changed in the depth direction. Further, the shape of the sipe-formed bone 5 as viewed from the ridge line side can be various shapes such as a linear shape and a waveform.

FIGS. 6 and 7 illustrate a tire molding mold according to another embodiment of the present invention. In the figure, a sector (mold) 11 is composed of a molding block 12 arranged on the inner surface of the mold, and a casing 13 for holding the molding block 12 from outside. A plurality of main groove forming bones 2 extending in the tire circumferential direction and a plurality of lateral groove forming bones 3 extending in the tire width direction are provided on the inner surface of the forming block 12 as in the above-described embodiment. An area surrounded by the bone 2 and the lateral groove forming bone 3 is a block forming space 4.

Further, on the inner surface of the molding block 12, a plurality of sipe molding bones 5 are provided adjacent to each other.
The plurality of sipe molding bones 5 divide the block molding space 4 into a plurality of small block spaces in the tire circumferential direction. The sipe-formed bone 5 has a ridge-side end 5a from an implant-side end 5a.
b, at least one notch 7 extending halfway is provided, and this notch 7 is
2 communicates with the back.

On the other hand, the casing 13 is
An exhaust path (exhaust space) 14 communicating with the above-described cut 7 is provided on the surface in contact with the tire so as to extend in the tire circumferential direction. The exhaust path 14 communicates with the outside of the mold at a location (not shown), and exhausts air in the mold. The exhaust path 14 may be provided on the back surface of the molding block 12 as shown in FIG. 8 instead of being provided on the casing 13 side. As shown in FIG. 9, the exhaust hole 1 communicating with the cut 7 is formed on the back of the molding block 12.
5 may be provided so as to be scattered in the tire circumferential direction, and these exhaust holes 15 may be communicated with the exhaust path 14 on the casing 13 side.

In the tire molding mold configured as described above, the cut 7 of the sipe molding bone 5 implanted on the inner surface of the molding block 12 communicates with the exhaust passage 14 or the exhaust hole 15. Since the air pushed into the block molding space 4 during the tire vulcanization molding through the exhaust space can be exhausted to the outside of the mold, there is no need to provide an air vent hole on the inner surface of the molding block 12. Therefore, since no vent spew is formed on the outer peripheral surface of the product tire after vulcanization molding, the step of removing the vent spew is unnecessary, and the tire productivity can be greatly improved. In addition, since unnecessary vent spew is not formed, the rubber material can be saved correspondingly.

Also, in this embodiment, the cut 7 allows air to pass through but hardly passes unvulcanized rubber, so that the resistance at the time of mold release is reduced and the chipping of the block is prevented to improve the appearance of the tire. can do. Especially,
In this embodiment, since no vent spew is formed on the outer peripheral surface of the tire, the step of trimming the vent spew becomes unnecessary, and noise during running of a new product can be reduced.

In each of the above embodiments, a sectional tire mold has been described. However, the present invention is not limited to the case where a sipe molding bone for dividing a block is implanted on the inner surface of a mold. It is also possible to apply the present invention to a split mold for molding a tire.

[0025]

As described above, according to the present invention, a plurality of sipe-forming bones for dividing the block forming space into a plurality of small block spaces are implanted in the block forming space on the inner surface of the mold and the sipe is formed. By providing at least one notch extending through the molded bone from the implanted end to a point not reaching the ridge side end but not passing the unvulcanized rubber, the sipe of the tire block after vulcanization molding is provided. Because rubber pillars connecting small blocks are not formed inside,
The resistance at the time of releasing can be reduced, and the chipping of the block can be prevented to improve the appearance of the tire.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a tire molding mold according to an embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrows AA in FIG. 1;

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a perspective view showing a press die for producing a sipe molding bone in the tire molding mold of the present invention.

FIGS. 5A to 5K are cross-sectional views showing modified examples of a sipe molding bone in the tire molding mold of the present invention.

FIG. 6 is a sectional view showing a tire molding mold according to another embodiment of the present invention.

FIG. 7 is an enlarged perspective sectional view showing the inner surface of FIG. 6;

FIG. 8 is a cross-sectional view showing a modified example of the exhaust space in the tire molding mold of the present invention.

FIG. 9 is a sectional view showing another modified example of the exhaust space in the tire molding mold of the present invention.

[Explanation of symbols]

 Reference Signs List 1 sector (mold) 2 main groove forming bone 3 lateral groove forming bone 4 block forming space 5 sipe forming bone 5a implantation end 5b ridge end 7 cut

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

Claims (4)

[Claims] 1. A plurality of main groove forming bones extending in a tire circumferential direction and a plurality of lateral groove forming bones extending in a tire width direction are provided on a molding inner surface of a mold, and the main groove forming bones and the lateral groove forming bones block. A molding space is divided and formed, a plurality of sipe molding bones are implanted in the block molding space, and at least one air extending from the implantation side end to the ridge line side end to the sipe molding bone does not pass, but is not yet passed. A tire molding mold with cuts that do not allow vulcanized rubber to pass through. 2. The tire molding mold according to claim 1, wherein the cuts facing the implantation side end of the sipe molding bone communicate with an exhaust space provided inside a mold. 3. The slit width of the cut is 0.1 mm.
The tire molding mold according to claim 1, wherein: 4. A pneumatic tire vulcanized and molded in the tire molding mold according to claim 1, 2 or 3.