JPS6378804A - Pneumatic type - Google Patents

Abstract

PURPOSE:To reduce the generation of type noise, by a method wherein trim remaining projected parts of a vent hole burr are formed in a given region of a tread surface. CONSTITUTION:Trim remaining projected parts 4, 4... of vent hole burr are left remaining in a region except a region A nipped by a position (e) 5 mm inner than an earthing end E of a tread surface, determined according to a JIS standard condition and a position (m) 5 mm outer than a central line M of an outermost main groove 2. This constitution enables reduction of the generation of type noise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire that reduces tire noise when new.

[Prior art]

The tread portion of a tire is provided with a complex tread pattern formed by combining a plurality of grooves. In order to vulcanize and mold a tire with such a complex tread pattern, a large number of vent holes (air bleed holes) are provided in the part of the mold corresponding to the tread surface, which allows the mold to connect with the tire rubber. This is to prevent appearance failures (referred to as lights) caused by air pockets between the parts. For this reason, when the tire is released from the mold after vulcanization molding, a burr is formed at the vent hole portion, and this burr is trimmed (cut off) to form the final product. However, even if the above paris are trimmed, it is difficult to completely remove them, and generally about 1 to 21 roots are left behind, forming many convex portions on the tread surface.

However, according to research conducted by the present inventors, it has been found that the trim residue formed in a convex shape on the tread surface has a large effect on noise when the tire is new. These trim residual convex parts cannot be completely erased after driving a new tire for several hundred kilometers, and they still have an impact on noise, and in some cases, even after driving 1,000 to 2,000 km, they still have an adverse effect. I found out that something happened.

As a countermeasure for this, it would be possible to trim the Paris to the extent that it does not affect the noise, but this requires great care and takes a lot of time, so production is slowed down. It is not practical for industrial production because it reduces performance and increases costs. In addition, a vulcanizing device that does not form vent holes has been considered, but such a device has not yet been fully put into practical use.

[Purpose of the invention]

An object of the present invention is to provide a pneumatic tire that can reduce tire noise while leaving a trim residual convex portion of a vent hole burr.

[Structure of the invention]

A pneumatic tire according to the present invention that achieves the above object is provided by J.
Exclude the area sandwiched between a position 5 mm inside from the edge of the tread surface under IS standard conditions and a position 5 mm outside from the center of the outermost main groove among multiple main grooves connected in the circumferential direction. The tread surface is characterized by a vent hole burr trim remaining protrusion.

There are many causes of tire noise, but one of the major causes is when the rubber in various parts of the tread deforms when the tire rotates and is released when it hits the ground (when kicking off). It is thought that this is due to the vibration that occurs (self-excited vibration).

Therefore, the reason why the trim residual convex part of the vent hole burr affects tire noise is that if the trim residual convex part exists in the tread part, when the tread part deforms as mentioned above, the trim residual convex part It is presumed that this is because the ground pressure at the area becomes higher, and the deformation of the rubber around the area becomes larger than at other areas without the protrusion.

Based on the above knowledge, the inventor of the present invention further investigated the cause of tire noise, and found that the part of the tread that generates noise does not contribute equally to the entire area of the tread, but rather varies depending on the part. After discovering that there is a difference, the trim residual convex portion is not placed in the area that contributes most to the noise generation.

After examining the details and conducting experiments, we found that the part that contributes most to noise generation is a part of the shoulder, especially the part that is sandwiched between the tread surface edge and the outermost main groove of the multiple main grooves. It has become a territory. However, even within this region with the highest contribution, 5 m inside from the edge of the tread surface.
It was found that the M region up to m and the region up to 5 mm outside from the center of the main groove had a relatively small degree of contribution. Therefore, in the present invention, based on these results, the area sandwiched between the position 5 mm inside from the edge of the tread surface and the position 5 mm outside from the center of the outermost main groove is removed, and the other areas are removed. The trim remaining convex portion of the vent hole burr is arranged on the tread surface.

Note that the term "tread surface edge" as used herein means that which is defined by the contact surface when the tire is bent under JIS standard conditions commensurate with its size. In addition, the center of the main groove refers to a position halfway between the inner end and the outer end in the width direction of the groove, and when the main groove is formed in a zigzag shape,
The center is set at 1/2 of the width defined by the outermost and innermost ends in the width direction forming the zigzag.

FIG. 1 shows a tread pattern of a tire according to an embodiment of the present invention, in which a plurality of main grooves 2°-, 2 are provided on the tread surface 1 so as to be continuous in the circumferential direction. Groove 2. ... Many minor grooves crossing -92 3. −・
-13 is provided. The surface of the block surrounded by these grooves 2 and 3 has a convex portion 4 remaining after trimming the vent hole burr. ...-94 is formed in large numbers.

In the tread pattern shown in this figure, the tread surface ground width determined by JIs standard conditions is W, and lines E and E at both ends thereof are the ground contact edges. Further, the center line of the left and right main grooves 2.2 located at the outermost side is M from the above definition.

Represented by M.

As mentioned above, the area that contributes most to tire noise is the area surrounded by lines E and M in a part of the shoulder, but the area that contributes the most is the area 5mm inside from line E at the edge of the tread surface. This is a region A sandwiched between position e and position m, which is 5 mm outward from the center line M of the outermost main groove 2. Convex portion of the remaining trim 4. ...-24 is arranged on the tread surface in a portion outside of this region A, thereby reducing tire noise.

On the other hand, in the case of the conventional tire shown in FIG.
is also arranged in the area A. This results in increased tire noise when new.

〔Example〕

Size 175/ has a tread pattern as shown in Fig. 1 and has trim remaining convex portions of vent hole burrs.
A 70SR13 tire (tire of the present invention) was manufactured. On the other hand, for comparison, a tire (conventional tire) of the same size was manufactured, which had a tread pattern as shown in FIG. 2, and was provided with a trim remaining convex portion of a vent hole burr.

Noise measurements were performed on both tires using a rotating steel drum. The measurement conditions were rim 5-
JX13, air pressure 2, Okgf/d1 load 300
kg, and the noise was determined as the average value of the sound pressure level of 100 to 2000 Hz at a speed of 60 to 100 km/h.

As a result, the noise of the tire of the present invention was 89.0 dB, while the noise of the conventional tire was 91.5 dB, and it was found that the tire of the present invention could reduce the noise by 2.5 dB.

〔Effect of the invention〕

As mentioned above, the pneumatic tire of the present invention has a position 5 mm inside from the edge of the trend surface under JIS standard conditions, which is the part that contributes most to noise generation, and a position that is the most of the main grooves connected in the circumferential direction. 5m outside from the center of the outer main groove
By removing the area sandwiched between the tread surface and position m and placing the vent hole burr's remaining trim convex portion on the rest of the tread surface, tire noise due to the trim convex portion is reduced compared to conventional tires. can do.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a tread pattern of a pneumatic tire of the present invention, and FIG. 2 is a plan view of a tread pattern of a conventional tire. 1...Tread surface, 2...Main groove, 3...Minor groove, 4...(trim remaining) convex portion.

Claims (1)

[Claims] A tread with the area sandwiched between a position 5mm inside from the edge of the tread surface under JIS standard conditions and a position 5mm outside from the center of the outermost main groove of multiple main grooves connected in the circumferential direction removed. A pneumatic tire with a vent hole burr trim remaining protrusion on the surface.