JPH0948076A - Manufacture of pneumatic tire with v-shaped directional pattern low tilted groove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To significantly improve the level of uniformity and reduce a noise (hitting sound) by providing a tread pattern by which a V center block is formed with plural directional low tilted grooves extended in a V-shape at a specific angle of inclination in the peripheral direction. SOLUTION: First, a raw grooved tread 4 with a directional low tilted groove 1 and a recessed part 3 formed at a position corresponding to an angle of inclination of 5-30 deg., is manufactured. Next, the raw-grooved tread 4 is attached to a carcass and is formed to obtain a raw grooved tire. After that, the registration of the relative positions for the recessed part 3 of the raw grooved tire and a projecting part provided at a position corresponding to the directional low tilted groove 1 of a vulcanization mold is controlled so that the recessed part 3 coincides with the projecting part, while the raw grooved tire is mounted in the vulcanization mold. Finally, the vulcanization mold is closed and the raw grooved tire is vulcanized under specified temperature and pressure conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a pneumatic tire, and more particularly, 5 to 30 degrees, preferably 1 to the left and right of the pattern center in the circumferential direction.
A large number of directional low-inclination grooves extending in a V shape at a relatively small inclination angle of 0 to 20 degrees are arranged at intervals in the tire circumferential direction, and the directional low-inclination grooves form a V-shaped center block. The present invention relates to a method for manufacturing a pneumatic tire having a tread pattern.

In the present specification, a "directionally inclined groove" is a groove extending obliquely with respect to the circumferential direction, and a portion of the groove extending obliquely near the equatorial plane of the tire is grounded first. , A groove in which a so-called directional tread pattern is formed, in which the direction of rotation (normal rotation) of the tire when it is mounted on a vehicle is specified so that the side farther from the equatorial plane will come into contact with the ground later.

[0003]

2. Description of the Related Art A large number of directional low-inclination grooves extending in a V shape at a relatively small inclination angle with respect to the circumferential direction with a pattern center interposed therebetween are arranged at intervals in the tire circumferential direction. In a region near the pattern center of a pneumatic tire having a tread pattern in which a V-shaped center block is formed by a low-inclination groove, the negative ratio of the tapered tip of the V-shaped center block is large, The negative ratio of the wide part of the V-shaped center block is small. In the conventional ordinary tire manufacturing method, a raw tread having an average cross-sectional area of the final tread after vulcanization is continuously extruded from a tread mouthpiece of an extruder, and the raw tread is pasted and molded on a carcass. Thus, the tire was manufactured. As a result, when the tire as described above is manufactured by the usual method as described above,
The flow of the tread rubber during vulcanization becomes non-uniform, and the thickness of the V-shaped center block increases at the tapered tip.
To make it easier to understand, if you express it a little too much, the inner surface of the tire is wavy in the circumferential direction in the mold at the end of vulcanization, and the inner surface of the tire at the tapered tip of the V-shaped center block is It is convex inward, and in the state before filling the tire with internal pressure, it is almost the same inward convex,
In the state where the tire is assembled on the rim and filled with the internal pressure, the surface of the V-shaped center block is convex toward the outside of the tire near the tapered tip.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
A large number of directional low-inclination grooves extending in a V shape with a relatively small inclination angle with respect to the circumferential direction sandwiching the pattern center are arranged at intervals in the tire circumferential direction. A pneumatic tire with a tread pattern with a V-shaped center block has a large radial runout (dimensional non-uniformity in the radial direction) and a large radial force variation (force in the radial direction). Fluctuation of the tire), the uniformity level of the tire is likely to deteriorate, and the noise (striking sound) generated from the tire during traveling is large.

An object of the present invention is to eliminate the above-mentioned problems of the prior art and to sandwich the pattern center on the left and right sides.
A large number of directional low-inclination grooves extending in a V shape at a relatively small inclination angle with respect to the circumferential direction are arranged at intervals in the tire circumferential direction, and the directional low-inclination grooves form a V-shaped center block. In a pneumatic tire having a known tread pattern, it is to improve the level of uniformity and reduce noise (striking noise).

[0006]

In order to achieve the above object, the method of manufacturing a pneumatic tire according to the present invention comprises a pattern center and a left and right sides of the pattern tire in a circumferential direction of about 5 to 30 degrees. A large number of directional low-inclination grooves extending in a V shape at a small inclination angle are arranged at intervals in the tire circumferential direction,
In a method for manufacturing a pneumatic tire having a tread pattern in which a V-shaped center block is formed by the directional low-tilt groove, (1) a recess is provided at a position corresponding to the directional low-tilt groove. A step of producing a grooved green tread, and (2) a grooved green tread having a recess at a position corresponding to the directional low-inclination groove is pasted and molded on a carcass to produce a grooved green tire. And (3) a concave portion provided in the grooved green tire at a position corresponding to the directional low inclination groove, and a convex portion provided in a vulcanization mold at a position corresponding to the directional low inclination groove. While controlling the relative positional relationship between the two parts so that the parts match,
A step of mounting the grooved green tire on a vulcanization mold;
(4) A step of vulcanizing the tire having the directional low inclination groove by closing the vulcanization mold and holding the grooved green tire in the mold for a predetermined time under a predetermined temperature and pressure condition. A method for manufacturing a pneumatic tire, which comprises:

The pneumatic tire to which the present invention is applied has a pattern center between 5 and 30 with respect to the left and right in the circumferential direction.
A large number of directional low-inclination grooves extending in a V shape at a relatively small inclination angle of 10 to 20 degrees are preferably arranged in the tire circumferential direction, and the directional low-inclination grooves form a V-shaped groove.
Since the pneumatic tire has a tread pattern in which a V-shaped center block is formed, an inevitable result of such a tread pattern configuration is a V-shaped center block in the region near the pattern center. It is unavoidable that the negative ratio of the tapered front end is large and the negative ratio of the wide width part of the V-shaped center block is small, so that the negative ratio becomes uneven in the circumferential direction of the tire. When such a tire is manufactured by the conventional ordinary manufacturing method, the flow of the tread / rubber during vulcanization becomes non-uniform, the block thickness increases at the tapered tip, and the tire is assembled on the rim and the internal pressure is increased. Is filled with V
The surface of the block is convex toward the outside of the tire near the tapered tip of the letter-shaped center block. However, in the method for manufacturing a pneumatic tire of the present invention, as described above, provided with a concave portion at a position corresponding to the directional low-inclination groove, by sticking the grooved raw tread to the carcass,
A grooved green tire is manufactured, and a concave portion provided at a position corresponding to the directional low inclination groove of the grooved raw tire, and a convex portion provided at a position corresponding to the directional low inclination groove of the vulcanization mold. The tires are manufactured by mounting the grooved green tire on the vulcanization mold while controlling the relative positional relationship between the two so that As a result, a defect of the conventional technology, that is,
When the thickness of the block becomes large at the tapered tip and the tire is assembled on the rim and the internal pressure is filled, the surface of the block becomes convex outside the tire near the tapered tip of the V-shaped center block. Is eliminated.

In order to achieve the above object, in the method for manufacturing a pneumatic tire of the present invention, the cross-sectional area of the concave portion provided at the position corresponding to the directional low inclination groove of the grooved green tire is It is preferably 50 to 80% of the cross-sectional area of the directional low inclination groove. If this value is less than 50%, the uneven flow of the tread and rubber during vulcanization cannot be effectively corrected,
If it is more than 80%, a manufacturing defect such as a bear is likely to occur at a position corresponding to the directional low inclination groove.

In order to achieve the above object, in the method of manufacturing a pneumatic tire according to the present invention, a pair of movable pins are set adjacent to a tread extrusion base provided at the tip of a tread / rubber extruder to move the tread / rubber extruder. It is preferable to move the pin up and down to control the depth of the recess formed in the grooved raw tread, and to move the movable pin in the tread width direction to control the position of the recess formed in the grooved raw tread. . In this way, by pushing the tread while freely changing the position of the pin in the vertical and horizontal directions, it is possible to manufacture a raw tread with a groove having a desired recess.

In order to achieve the above object, in the method for manufacturing a pneumatic tire according to the present invention, the entire tread of a grooved green tire is scanned to form a grooved green tire before the vulcanization mold is mounted on the grooved green tire. The concave portion of the raw tire, which is provided at a position corresponding to the low-directional directional groove, and the convex portion of the vulcanization mold, which is provided at the position corresponding to the low-directional directional groove, are aligned so that the two From the viewpoint of improving accuracy and productivity, it is preferable to mount the grooved green tire on the vulcanizing mold while controlling the physical positional relationship.

In the pneumatic tire to which the present invention is applied,
The inclination angle of the directional low inclination groove is preferably 5 to 30 degrees, and more preferably 10 to 20 degrees. If this angle is too small, the block formed between the directional low-inclination grooves becomes small, the block rigidity becomes insufficient, and the steering stability on a dry road surface deteriorates. Therefore, in order to increase the size of the block in order to increase the block rigidity, the pitch must be set to a large value, and the number of pitches must be reduced. It stands out. If this angle is too large, the drainage performance on the wet road surface due to the directional low inclination groove is deteriorated, and the function of preventing or suppressing the hydroplaning phenomenon is reduced. Furthermore, when a large number of directional high-inclination grooves extending in a V shape with a relatively large inclination angle of 45 to 90 degrees, preferably 60 to 80 degrees with respect to the circumferential direction are used together, the angle of the directional low inclination groove is Too big,
The intersection angle between the directional low-tilt groove and the directional high-tilt groove becomes small, the block rigidity becomes insufficient, the steering stability on the dry road surface deteriorates, and the uneven wear easily occurs.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a tread pattern of a pneumatic tire for passenger cars according to one embodiment of the present invention. The size is 225 / 60R16.

The tire according to the embodiment of the present invention shown in FIG. 1 has a large number of directional low-inclination grooves 1 extending in a V shape to the left and right with the equatorial line E of the tire, which is the pattern center, sandwiched therebetween in the tire circumferential direction. A tread pattern in which a V-shaped center block is formed by the directional low-inclination groove 1 at a distance P from each other. In addition to the directional low-tilt groove 1, a large number of directional high-tilt grooves 2 are provided.
Has an inclination angle of about 18 degrees, and the directional high inclination groove 2 has an inclination angle of about 65 degrees. The large pitch P, which is the circumferential distance between the low directional grooves 1 and the circumferential direction, is about five times larger than the small pitch p, which is the circumferential distance between the high directional grooves 2. In order to reduce the tire noise (pattern noise) due to the tread pattern, the large pitch P and the small pitch p are each provided with a pitch variation. ) And is not directly related to them, detailed description thereof will be omitted. Like the directional low-tilt groove 1, the directional high-tilt groove 2 also extends in a V shape to the left and right with the equatorial line E of the tire interposed therebetween, and the circumferential interval of the directional high-tilt groove 2 is the directional low-tilt groove 1. The V-shaped center block formed by the directional low-inclination groove 1 is divided into a plurality of small blocks because the distance is smaller than the circumferential interval.

In the tire manufacturing method according to the embodiment of the present invention, first, as shown in FIG. 2, a grooved raw tread 4 having a recess 3 at a position corresponding to the directional low inclination groove 1 is manufactured, and then, A grooved green tire (not shown) is manufactured by pasting and molding a grooved green tread 4 having a concave portion 3 at a position corresponding to the directional low-inclined groove 1 on a carcass, and then a grooved green tire. The concave portion 3 provided at the position corresponding to the low directional groove 1 and the convex portion provided at the position corresponding to the low directional groove 1 of the vulcanization mold (not shown) match each other. In addition, while controlling the relative positional relationship between the two, the raw tire with groove is mounted on the vulcanization mold,
Next, the vulcanization mold is closed, and the tire having the directional low-inclination groove 1 is manufactured through a vulcanization process in which the grooved green tire is held in the mold for a predetermined time under a predetermined temperature and pressure condition. It In the present embodiment, the cross-sectional area of the recessed portion 3 provided at the position corresponding to the directional low-inclination groove 1 of the grooved raw tread 4 is 50% of the cross-sectional area of the directional low-inclination groove 1. As shown in FIG. 2, a grooved raw tread 4 having a recess 3 at a position corresponding to the directional low inclination groove 1 is provided at the tip of a tread / rubber extruder (not shown) as shown in FIG. A pair of movable pins 6 are set adjacent to the tread extrusion die 5 thus formed, and the movable pins 6 are moved in the vertical direction to control the depth of the concave portions 3 formed in the grooved raw tread 4,
It is manufactured by moving the movable pin 6 in the width direction of the raw tread 4 to control the position of the concave portion 3 formed in the grooved raw tread 4. In the tire manufacturing method of the example according to the present invention, prior to the vulcanization mold mounting of the raw tire with groove,
The entire tread of the grooved green tire is scanned with a laser, and the concave portion 3 provided at a position corresponding to the directional low inclination groove 1 of the grooved raw tire and the directional low inclination groove 1 of the vulcanization mold. While controlling the relative positional relationship between the two so that the convex part provided at the position corresponding to
A grooved green tire is mounted on a vulcanization mold.

The method of manufacturing the pneumatic tire of the conventional example is almost the same as the method of manufacturing the tire of the example except that a raw tread having no recess 3 is used.

Regarding the pneumatic tire manufactured by the method of the embodiment according to the present invention (hereinafter referred to as the tire of the embodiment) and the pneumatic tire manufactured by the method of the above-mentioned conventional example (hereinafter referred to as the tire of the conventional example) , Radial runout (dimensional non-uniformity in the radial direction: RRO),
The radial force variation (radial force fluctuation: RFV), ride comfort and tire noise were compared. The tire noise comparison test was a tire noise evaluation test based on the automobile standard tire noise test method JASO C606, and the tire noise at a speed of 60 km / h, that is, the sound pressure level was measured. Radial Force
In the variation (RFV) comparative test, the tire was pressed against a rotating drum to apply a load, and the uniformity level was measured in a state where the axial distance between the tire and the drum was constant. The comparison test of the riding comfort performance of the tires is a feeling evaluation by a test driver when the tires of the example and the conventional example are attached to a domestic 2000cc class passenger car and the test course is run. Table 1 shows the evaluation results.

[0017]

[Table 1]

[0018]

From the above evaluation test results, the pneumatic tires of the examples according to the present invention have a significantly improved uniformity level as compared with the pneumatic tires of the conventional example, and tire noise is significantly reduced. I understand that.

[Brief description of drawings]

FIG. 1 is a tread pattern diagram of a pneumatic tire targeted by the present invention.

FIG. 2 is a drawing showing a method for manufacturing a pneumatic tire according to the present invention.

FIG. 3 is a drawing showing a method for manufacturing a pneumatic tire according to the present invention.

[Explanation of symbols]

 E Tread equatorial line P Large pitch p Small pitch 1 Directional low inclination groove 2 Directional high inclination groove 3 Recess 4 Raw tread 5 Tread extrusion base 6 Moving pin

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area B29K 105: 24 B29L 30:00

Claims (4)

[Claims] 1. A large number of directional low-inclination grooves extending in a V shape at left and right sides of a pattern center at a relatively small inclination angle of about 5 to 30 degrees with respect to the circumferential direction, spaced apart in the tire circumferential direction. In a pneumatic tire having a tread pattern in which a V-shaped center block is formed by the directional low-inclination groove,
(1) a step of producing a grooved raw tread having a recess at a position corresponding to the directional low-sloping groove; and (2) a grooved raw tread having a recess at a position corresponding to the directional low-sloping groove. A step of manufacturing a grooved green tire by pasting and molding the above into a carcass, and (3) the grooved green tire,
A recess provided at a position corresponding to the directional low-inclination groove,
The grooved green tire was vulcanized into a vulcanization mold while controlling the relative positional relationship between the vulcanization mold and the protrusions provided at the positions corresponding to the directional low-inclination grooves so as to match the relative positions of the two. And (4) closing the vulcanization mold, and maintaining the grooved green tire in the mold for a predetermined time under a predetermined temperature and pressure condition, thereby providing a tire having the low directional groove. A method for manufacturing a pneumatic tire, comprising a step of vulcanizing 2. A cross-sectional area of a recess provided in a position corresponding to the directional low-inclination groove of the grooved green tire is 50 to 80% of a cross-sectional area of the directional low-inclination groove. The method for manufacturing the pneumatic tire according to claim 1, wherein the pneumatic tire is manufactured. 3. A recess formed in the grooved raw tread by setting a pair of movable pins adjacent to a tread extrusion die provided at the tip of a tread / rubber extruder and moving the movable pins in the vertical direction. 3. The method for producing a pneumatic tire according to claim 1, wherein the depth of the groove is controlled, and the movable pin is moved in the tread width direction to control the position of the recess formed in the grooved raw tread. . 4. Prior to mounting the grooved green tire on the vulcanization mold, the entire tread of the grooved green tire is scanned to a position corresponding to the directional low inclination groove of the grooved raw tire. While controlling the relative positional relationship between the concave portion provided and the vulcanization mold, the convex portion provided at a position corresponding to the directional low-inclined groove is controlled,
The method for manufacturing a pneumatic tire according to claim 1, wherein the grooved green tire is mounted on a vulcanization mold.