JPH08267458A - Method and apparatus for producing pneumatic tire - Google Patents

Abstract

PURPOSE: To vulcanize a green tire without generating spew or a slit in the tread part of a vulcanized tire. CONSTITUTION: The mutual joint of a plurality of split molds 22 arranged in peripheral and lateral directions is passed at least one place of the recessed parts each surrounded by protruding parts 26,28 forming grooves in a peripheral direction in a tread pattern and a protruding part 30 forming grooves in a lateral direction. Further, one grooves 50 extending in the peripheral and lateral directions are formed to the joint surfaces of the split molds 22 and predetermined surface roughness processing 52 is applied between the grooves 50 and the surfaces of the split molds forming the tread pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire manufacturing method and apparatus for forming a tread pattern on a raw tire surface in a tire manufacturing process, particularly in a vulcanization process.

[0002]

2. Description of the Related Art In general, a cylindrical raw tire produced in a tire forming step is mounted in a vulcanizer and vulcanized and formed in the next step. Here, the vulcanizer is, for example, annularly arranged so as to be expandable / contractible in the radial direction by a plurality of segments, and a plurality of split molds constituting a tread molding mold are circumferentially and circumferentially on the inner peripheral surface of each segment. They are mounted side by side in the width direction. Each split mold is generally formed so as to divide the tread pattern in the circumferential direction by a straight line orthogonal to the circumferential direction of the tire.

At the time of vulcanization, a cylindrical raw tire is arranged on the inner peripheral side of the expanded segment, and the raw tire is inflated into a donut shape, and then each segment is compressed at a predetermined timing. The tread pattern is formed on the outer circumferential surface of the raw tire by making the diameter.

In the above-mentioned apparatus, it is necessary to efficiently discharge the air accumulated between the outer peripheral surface of the raw tire and the tread molding die during vulcanization to the outside. Therefore, a plurality of pores for venting air called vent holes extending from the inner peripheral surface toward the outer peripheral surface are formed in each of the split molds of the tread molding mold, and the vent holes and the circumferential direction are aligned. Air is exhausted to the outside by utilizing the gap between the divided molds.

Further, recently, as an air venting means replacing the vent holes, air passes through the mold surfaces adjacent to each other of a plurality of split molds constituting the tread molding die but unvulcanized rubber does not pass through. Form a narrow slit,
It has been attempted to exhaust air to the outside of the tread molding die through the slit and the space on the back side thereof (Japanese Patent Laid-Open No. 2-295706.
No. 539. See Japanese Patent Laid-Open No. 6-218733).

[0006]

The above vent hole is
Since it is provided with a thickness of about 1 mm in diameter, unvulcanized rubber flows into the vent hole after the air escapes, and this is vulcanized as it is to form many needle-shaped protrusions, so-called spews, on the tire surface. Therefore, it is necessary to cut off the spew from the root after completion of the vulcanization, which lowers the productivity and leaves a trace of cutting on the tire to deteriorate the appearance. Further, even when air is evacuated from the narrow slits on the mold surface side adjacent to each other of the split mold, the slit width 53 is generally 10 to 50 as shown in FIG. 6- (1).
Since it is formed with a width of μm, similarly, unvulcanized rubber flows into the narrow slits after the air escapes, and this is vulcanized as it is to form slit-shaped protruding rubber, which makes the appearance unsightly. Not only that, but the dirt in the rubber adheres to the inside of the slits to close the narrow slits and prevent the discharge of air from the slits.As a result, air pockets are formed between the tread molding die and the raw tires, resulting in product defects. Had occurred.

The present invention has been made in order to solve the above problems, and does not form a protrusion such as a rubber column in the tread portion of a vulcanized tire and vulcanizes a raw tire with few product defects. It is an object of the present invention to provide a tire manufacturing method and apparatus capable of performing the above.

[0008]

According to a first aspect of the present invention, an annular tread molding die for forming a tread pattern of a tire comprises a plurality of divided dies for dividing the tread pattern in a circumferential direction and a width direction. , A vulcanizer in which these split molds are annularly arranged so as to be expandable and contractible in the radial direction, after arranging a raw tire on the inner circumferential side of the tread molding die, and expanding the raw tire together with the split mold The diameter of the raw tire is reduced by discharging the air accumulated between the tread molding die and the outer circumferential surface of the raw tire to the outside through the gap between the divided die adjacent in the circumferential direction and the width direction. A tread pattern is formed on the outer peripheral surface.

According to a second aspect of the present invention, a tread forming die for forming a tread pattern comprises a plurality of divided dies for dividing the tread pattern in a circumferential direction and a width direction.
In the vulcanizer in which these split molds are annularly arranged so as to be expandable and contractible in the radial direction, the tread molding mold has a plurality of circumferential projections for forming circumferential grooves on the tire outer peripheral surface. Together with a plurality of width direction convex portions for forming a groove in the width direction, each of the divided mold,
The seams of the divided dies are formed so that at least one of the recesses of the tread molding die is surrounded by the circumferential projections and the widthwise projections and passes through at least one of the recesses.

According to a third aspect of the present invention, a tread forming die for forming a tread pattern comprises a plurality of divided dies for dividing the tread pattern in the circumferential direction and the width direction.
In a vulcanizer in which these split molds are annularly arranged so as to be expandable and contractible in the radial direction, on the side faces along the circumferential direction and the width direction of the split molds, a first extending in the circumferential direction and the width direction of the tread pattern surface, respectively. The first groove and a plurality of second grooves communicating with the surface opposite to the first groove and the tread pattern surface are formed respectively.

According to a fourth aspect of the present invention, a tread forming die for forming a tread pattern comprises a plurality of divided dies for dividing the tread pattern in a circumferential direction and a width direction.
In a vulcanizer in which these split molds are annularly arranged so as to be expandable and contractible in the radial direction, the side surfaces along the circumferential direction and the width direction of the split molds are subjected to predetermined surface roughness processing, and the surface roughness is The air accumulated between the tread molding die and the outer peripheral surface of the raw tire is exhausted to the outside through the gap formed between the divided dies adjacent to each other by the bending process and the first groove and the plurality of second grooves. It was formed as follows.

[0012]

According to the invention described in claim 1, the air accumulated between the tread molding die and the outer peripheral surface of the green tire at the time of vulcanization is discharged from the gaps between the divided dies forming the tread molding die. Since it is discharged to the outside, the vent hole that was conventionally formed in each split mold for venting air is unnecessary, and this allows the rubber column that was formed on the outer peripheral surface of the vulcanized tire to be formed by the vent hole. Disappear. Therefore, the work of picking up the rubber column becomes unnecessary, and the tire production efficiency is improved. Further, since the rubber column is not formed in the vulcanized tire, no traces after picking the rubber column or left unplucked parts of the rubber column are generated, so that the appearance quality of the tire can be improved.

According to the invention described in claim 2.3.4, it is not necessary to provide a vent hole in each split mold.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

As shown in FIGS. 2 and 3, the vulcanizer 10
Is composed of nine segments 12 of the same structure arranged annularly around the shaft 14, a pair of clamp rings 16 arranged on the inner peripheral surface side of these segments 12, and the inner circumference of the segment 12. It is provided with a pair of side molds 18 interposed between the surface and the outer peripheral surface of the clamp ring 16.

The clamp rings 16 are disk-shaped members mounted on the shafts 14, and the clamp rings 16 are mounted at predetermined intervals in the axial direction of the shafts 14. A bladder 20 made of a flexible material that can expand and contract along the outer circumference is attached between the clamp rings 16 to form a cylindrical sealed space surrounded by the clamp rings 16 and the bladder 20. Has been done.

The side mold 18 is a mold for molding the side wall portion of the vulcanized tire, and as shown in FIG. 3, the side mold 18 approaches each other in the width direction and the outer peripheral surface of each of the clamp rings 16 and the side surface of the clamp ring 16. It is configured to be displaced between a state in which it is interposed between the inner peripheral surface of the segment 12 and a state in which they are separated from each other as shown by the dashed line in FIG.

Each of the segments 12 is configured to be expandable / contractible between the position shown by the alternate long and short dash line in FIG. 2 and the position shown by the solid line, and the inner peripheral surface of each segment 12 has a split mold forming a tread molding mold. 22 are arranged side by side (8 in the circumferential direction and 2 in the width direction) (only one segment 12 is shown in FIG. 2). That is, in the embodiment, a total of 144 divided dies constitute a tread forming die, and these divided dies 22 form a tread pattern on the outer peripheral surface of the vulcanized tire.

As shown in FIGS. 1 and 4, the split mold 22 is provided with an uneven portion for forming a tread pattern on its inner peripheral surface. Specifically, the convex portions 26, 26 forming the first main groove in the circumferential direction of the vulcanized tire and the convex portion forming the second main groove parallel to the first main grooves 26, 26. 28, 28 and a convex portion 30 that forms a groove in the width direction called a slot in the vulcanized tire are formed symmetrically or asymmetrically with the equator 24 interposed therebetween.

Here, the end faces in the circumferential direction and the end faces in the width direction of each split mold 22 are generally formed linearly as shown in FIG. More specifically, when forming the split molds 22 so as to divide the tread pattern of the finished tire into 72 in the circumferential direction, the seams 32 of the split molds 22 arranged in the circumferential direction are not Each split mold 22 is formed so as to form a line segment that passes through a part of the concave portion 34, the concave portion 36, and the concave portion 44 formed by being surrounded by the portion 26, the convex portion 28, and the convex portion 30. ing.

The split mold 22 is fixed to the inner peripheral surface of the segment 12 by fixing means such as bolts as shown in FIG. Here, on the inner peripheral surface of each segment 12, as shown in the figure, a plurality of parallel narrow grooves 38 are continuously formed in the circumferential direction and a plurality of parallel narrow grooves extending in the width direction are formed. The thin grooves 40 of the respective segments 12 are formed at predetermined intervals in the circumferential direction.
Lattice-shaped grooves are formed on the inner peripheral surface. Further, each segment 12 is formed with an air hole 42 that communicates the narrow groove 38 with the outside of the upper surface of the segment 12. The air holes 42 are formed at two locations in the width direction of each segment 12 and at a predetermined interval in the circumferential direction. Meanwhile, FIG.
As shown in FIG. 1, on the side surface 54 along the circumferential direction and the width direction of the split mold 22, one groove 50 extending parallel to each of the circumferential direction and the width direction of the tread pattern surface, and the one groove 50 and the tread. A plurality of grooves 51 communicating with the surface opposite to the pattern surface are formed respectively. Further, on the side surface 54 along the circumferential direction and the width direction of each split mold 22, the split mold surface 55 forming a tread pattern and the groove 5 are formed.
Predetermined surface roughness processing 52 is performed between 0 and 0. The surface roughness processing 52 has a center line average roughness (Ra) in the range of 0.1 to 12.5 μmRa based on the JIS standard and is effective in preventing rubber clogging due to rubber intrusion. A range of 1 to 6.3 μmRa is particularly desirable. Further, the surface roughness processing 52 is performed by processing means such as M / C (electrical discharge) processing or corrosion processing.

Next, the operation of the vulcanizer 10 will be described.

First, as shown by the alternate long and short dash line in FIGS. 2 and 3, the diameter of each segment 12 of the vulcanizer 10 is expanded and the side molds 18 are separated from each other. In this state, the raw tire formed into a cylindrical shape in the molding step is mounted on the outer peripheral surface of the clamp ring 16 and vulcanization is started. When vulcanization is started, the side molds 18 are moved to positions close to each other, and high-temperature and high-pressure steam is supplied into the space formed by the clamp ring 16 and the bladder 20 to cause the bladder 2 to move.
0 is expanded toward the outer peripheral direction of the clamp ring 16 as shown by the one-dot chain line in FIG. As a result, the cylindrical green tire mounted on the clamp ring 16 is deformed into a hollow donut shape. When the raw tire is deformed into a donut shape, then the segment 12 is reduced in diameter and each split mold 2 is attached to the inner peripheral surface of each segment 12.
2 is brought into contact with the outer peripheral surface of the raw tire. At this time, the raw tire is divided into two molds 2 by the vapor pressure in the bladder 20.
2, the tread pattern is formed on the outer peripheral surface of the raw tire.

Here, when the green tire is pressed by each split mold 22, between the outer peripheral surface of the raw tire and the inner peripheral surface of the split mold 22, more specifically, the recess 34 of the split mold 22. , Recess 3
6 and the recess 44 will collect air. On this occasion,
The air accumulated in the recesses 34, 36 and 44 is
One groove 5 extending in the circumferential direction and the width direction of the tread pattern surface formed on the side surface 54 in the circumferential direction and the width direction from the seam 32 of each split mold 22 through the surface roughness processing 52 portion.
0 and the plurality of grooves 51 communicating with the groove 50 and the surface on the side opposite to the tread pattern surface and flow out to the thin grooves 40 and 38 of each segment 12, and further through the air holes 42 to each segment. 12 will be discharged to the outside.

As described above, the vulcanizer 1 having the above structure
According to No. 0, air accumulated between each split mold 22 and the outer peripheral surface of the green tire can be discharged from the joint 32 between the split molds 22 in the vulcanization step. There is no need to provide a vent hole for venting the air accumulated in the tread mold unlike the machine. Therefore, since the rubber column which is conventionally formed by the vent hole is not formed on the surface of the vulcanized tire obtained by the above method in which the air is discharged from the joint between the split molds 22,
The work of picking rubber pillars of vulcanized tires becomes unnecessary, which greatly improves the production efficiency of tires. further,
In the vulcanized tire, since the rubber column is not formed, the trace after the rubber column is plucked or the unplucked portion of the rubber column is not left, so that the appearance quality of the tire can be improved. Further, even when the air is removed from the narrow slits on the mold surface side adjacent to each other of the split mold, since the slit is not provided in the present invention, it is not necessary to clean the rubber flowing into the slit. This eliminates the need for frequent cleaning between the split mold slits and significantly improves the split mold operating rate.

In the above embodiment, each of the split molds 22 is divided into 72 pieces in the circumferential direction of the tread pattern.
The number of divisions in the circumferential direction of the split mold 22 is such that the joint 32 between the split molds 22 arranged in the circumferential direction is surrounded by the convex portion 26, the convex portion 28, and the convex portion 30. Recess 34.3
An appropriate number may be formed so that 6.44 may be crossed at at least one place.

In the above embodiment, the split mold 2 is used.
2 is a tread molding die 72 in the circumferential direction and 2 in the width direction.
Although it is formed so as to be divided, this is also an example, and it is of course applicable to a method of dividing by a method other than the example (Applicable Example: Japanese Patent Laid-Open No. 29570/1990).
No. 6. JP-A-6-106539. Japanese Patent Laid-Open No. 6-2187
No. 33).

[0028]

As described above, according to the present invention, the tread forming die for forming the tread pattern of the tire is composed of a plurality of divided dies for dividing the tread pattern in the circumferential direction and the width direction. A vulcanizer in which the mold is arranged in an annular shape so as to be expandable and contractible in the radial direction, after arranging the raw tire on the inner peripheral side of the tread molding die, and expanding the raw tire and reducing the diameter of the split mold. , At this time, the air accumulated between each of the tread molding dies and the outer peripheral surface of the raw tire is discharged to the outside from the gap between the divided dies adjacent to each other in the circumferential direction and the width direction to the outer peripheral surface of the raw tire. Since the pattern is formed, the vent hole that was formed in the tread molding die for air bleeding is unnecessary, and the rubber that was formed on the outer surface of the vulcanized tire by the vent hole is unnecessary. No longer be formed. Therefore, the work of picking rubber columns of vulcanized tires becomes unnecessary,
This greatly improves the tire production efficiency. Further, in the vulcanized tire, since the rubber column is not formed, there is no trace after the rubber column is plucked or the unplucked portion of the rubber column is not generated, so that the appearance quality of the tire can be improved. Further, even when compared with the conventional case in which air is evacuated from the narrow slits on the mold surface side adjacent to each other of the split mold, since the slit is not provided in the present invention, it is necessary to clean the rubber that has flowed into the slit. There is no. This eliminates the need for frequent cleaning between the split mold slits and significantly improves the split mold operating rate.

[Brief description of drawings]

FIG. 1 is a view on arrow B in FIG.

FIG. 2 is a schematic configuration diagram showing a vulcanizer 10 according to the present invention.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is an enlarged cross-sectional view taken along the line AA in FIG. 2 showing a segment.

FIG. 5 is an enlarged view of a split mold.

FIG. 6 (1) is an enlarged view of a conventional narrow slit,
FIG. 6 (2) is an enlarged view of the surface roughness processing in the present invention.

[Explanation of symbols]

 10 Vulcanizer 12 Segment 22 Split mold 24 Equator 26, 28, 30 Convex portion 32 Seam 34, 36, 44 Recessed portion 50, 51 Groove 52 Surface roughness processing 53 Slit

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Claims (4)

[Claims] 1. An annular tread molding die for forming a tread pattern of a tire comprises a plurality of divided dies for dividing the tread pattern in a circumferential direction and a width direction, and these divided dies can be expanded and contracted in a radial direction. Of the vulcanizer annularly arranged in, after arranging the raw tire on the inner peripheral side of the tread molding die, expand the raw tire and reduce the diameter of the split mold, at this time each of the tread molding dies A tread pattern is formed on the outer peripheral surface of the raw tire by discharging the air accumulated between the mold and the outer peripheral surface of the raw tire from the gap between the split molds adjacent in the circumferential direction and the width direction to the outside. Tire manufacturing method. 2. The annular tread forming die for forming the tread pattern comprises a plurality of divided dies for dividing the tread pattern in the circumferential direction and the width direction, and these divided dies can be expanded and contracted in the radial direction. In the annularly arranged vulcanizer, the tread molding die has a plurality of circumferential projections for forming circumferential grooves on the tire outer peripheral surface, and a plurality for forming widthwise grooves. Of each of the divided molds, the joints between the divided molds are surrounded on all sides by the circumferential convex parts and the widthwise convex parts of the tread molding mold. A tire manufacturing apparatus, characterized in that the recess is formed so as to pass through at least one location. 3. A tread forming die for forming the tread pattern comprises a plurality of divided dies for dividing the tread pattern in a circumferential direction and a width direction, and these divided dies are annularly expandable and contractable in a radial direction. In the arranged vulcanizer, on the side surface along the circumferential direction and the width direction of each of the divided molds,
A first groove extending in the circumferential direction and the width direction of the tread pattern surface, and a second groove communicating with the surface opposite to the first groove and the tread pattern surface are formed, respectively. Tire manufacturing equipment. 4. The tread forming die for forming the tread pattern is composed of a plurality of divided dies for dividing the tread pattern in the circumferential direction and the width direction, and these divided dies are annularly expandable and contractable in the radial direction. In the arranged vulcanizer, on the side surface along the circumferential direction and the width direction of each of the divided molds,
The surface of the tread molding die and the outer surface of the raw tire are subjected to predetermined surface roughness processing, and through the gap formed between the adjacent divided dies by the surface roughness processing and the first groove and the second groove. The tire manufacturing apparatus according to claim 3, wherein air accumulated in the space is discharged to the outside.