JP2003340935A - Method for producing pneumatic tire, pneumatic tire produced by the method, and strip material cooling device used in the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a pneumatic tire which can improve ozone crack resistance, a pneumatic tire produced by the method and a strip material cooling device used in the method. <P>SOLUTION: In the method for producing the pneumatic tire, a tire constituting member is formed by winding the strip material S composed of an unvulcanized rubber immediately after being ejected from an injection machine 21 or an extruder on a tire forming drum X, while having air blown upon the strip material S to cool itself. <P>COPYRIGHT: (C)2004,JPO

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 using a rubber strip material, a pneumatic tire manufactured by the manufacturing method, and a strip material cooling device used in the manufacturing method. The present invention relates to a method for manufacturing a pneumatic tire having improved ozone crack resistance, a pneumatic tire manufactured by the manufacturing method, and a strip material cooling device used in the manufacturing method.

[0002]

2. Description of the Related Art Generally, a green tire is formed by molding each tire constituent member in advance and sequentially laminating each tire constituent member on a tire molding drum at the time of manufacturing.

By the way, in recent years, by using an injection machine or an extruder, an unvulcanized rubber strip material is wound around a tire molding drum to mold each tire constituent member to mold a green tire, thereby producing a wide variety of small quantities. There has been proposed a technique for efficiently performing the above (for example, Japanese Patent Laid-Open No. Hei 11
-48363 gazette and Unexamined-Japanese-Patent No. 2000-202921 etc.).

However, the pneumatic tire using the strip material as described above has a problem of deterioration over time that, after 3 to 5 years, cracks due to ozone are generated along the interface where the strip materials adhere to each other on the surface. was there.

[0005]

The object of the present invention is to use a method for producing a pneumatic tire capable of improving ozone crack resistance, a pneumatic tire produced by the method and a method for producing the same. An object is to provide a strip material cooling device.

[0006]

The method of manufacturing a pneumatic tire of the present invention which achieves the above object comprises a strip material made of unvulcanized rubber immediately after being discharged from an injection machine or an extruder on a tire molding drum. In the method for manufacturing a pneumatic tire, which is formed by winding a tire constituent member,
It is characterized in that the strip material is wound while being cooled by blowing a gas.

In another method for manufacturing a pneumatic tire of the present invention, a strip member made of unvulcanized rubber immediately after being discharged from an injection machine or an extruder is wound around a tire building drum to form a tire constituent member. In the method for manufacturing a pneumatic tire described above, the strip material is wound in an atmosphere of an inert gas.

The pneumatic tire of the present invention is characterized by being manufactured by the method for manufacturing a pneumatic tire described above.

The strip material cooling device of the present invention is a gas blower for blowing gas to a strip material made of unvulcanized rubber immediately after being discharged from the injection machine or the extruder in the vicinity of the discharge port of the injection machine or the extruder. It is characterized in that a gas inlet is arranged and a gas supply source is connected to the gas nozzle.

According to the present invention having the above structure, the strip material is wound while being cooled by being blown to a gas, whereby the surface temperature of the strip material is lowered and the active state of the unvulcanized rubber is relaxed. Therefore, the adhesive strength between the vulcanized strip materials can be increased and the ozone crack resistance at the interface can be improved.

Further, by winding the strip material in an inert gas atmosphere, it is possible to suppress the oxidizing action of the strip material, which is in a state of being easily oxygen-bonded due to the high temperature immediately after the discharge, so that the strip material after vulcanization is suppressed. The mutual adhesion ability is improved, and ozone crack resistance can be improved.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The configuration of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an example of a pneumatic tire manufactured by the manufacturing method of the present invention, in which 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. The carcass layer 4 is mounted between the left and right bead portions 3, and both end portions 4a of the carcass layer 4 are folded back from the tire inside to the outside so that the bead filler 6 is sandwiched around the bead core 5 embedded in the bead portion 3. .

An inner liner 7 is arranged inside the carcass layer 4. A belt layer 8 is provided on the outer peripheral side of the carcass layer 4 of the tread portion 1. On the outer peripheral side of the belt layer 8, an inner peripheral first tread rubber layer 9 and an outer peripheral second tread rubber layer 10 are sequentially laminated. A side rubber layer 11 is arranged outside the carcass layer 4 of the sidewall portion 2, and a cushion rubber layer 12 is provided on the bead portion 3.

The first tread rubber layer 9, the second tread rubber layer 10, the side rubber layer 11, and the cushion rubber layer 12
Are each made of a rubber strip material wound in a spiral shape continuously in the tire circumferential direction.

FIG. 2 shows an essential part of the method for manufacturing a pneumatic tire of the present invention. X is a tire forming drum, and 21 is an injection machine for discharging a strip-shaped strip material S made of unvulcanized rubber. An extruder may be used instead of the injector 21.

Reference numeral 22 denotes a crimping device for automatically crimping the tip of the strip material S onto the tire forming drum X at the start of winding, so that the crimping roller 22A moves forward and backward toward the tire forming drum X by the operation of the cylinder 22B. Has become.

Reference numeral 23 denotes a strip material cooling device for blowing gas onto the strip material S to cool it. The strip material cooling device 23 supplies gas to the strip material S near the discharge port 21a of the die 21A of the injector 21. A pipe 25 in which a gas blowing port 24 for blowing is arranged, and a cooling gas is blown into the pipe 25 through an opening / closing valve 26.
Is connected to a gas supply source 27. The gas supply source 27 is composed of an inert gas supply source.

The term "inert gas" as used herein means that nitrogen gas is included in the inert gas in addition to the inert gases such as argon and neon described in the periodic table.

In the pneumatic tire manufacturing method of the present invention,
Each tire constituent member made of the above-mentioned strip material is molded as follows.

The strip material S made of high temperature unvulcanized rubber immediately after being discharged from the injector 21 is blown with an inert gas from the gas blowing port 24 in the vicinity of the discharge port 21a to cool its surface. The cooled strip material S is sequentially pressed onto the rotating tire forming drum X via the pressure roller 28 while being wound until it has a predetermined shape, thereby forming each tire constituent member.

As the cooling temperature, the surface temperature of the strip material S immediately after being wound around the tire forming drum X is 60 to 1
It is better to cool to 20 ° C. When the temperature is lower than 60 ° C., the adhesiveness between the strip materials S is adversely affected. On the other hand, when it exceeds 120 ° C., it becomes difficult to effectively improve the ozone crack resistance. By the way, the temperature of the strip material S immediately after being discharged from the injector 21 is
It is about 140 ° C.

Since the strip material S thus cooled to lower the surface temperature has its active state relaxed, the adhesiveness between the strip materials after vulcanization is improved as compared with the strip material wound at a high temperature. Therefore, the ozone crack resistance at the interface is improved.

Further, the strip material S immediately after being discharged is in a state of being easily bonded to oxygen due to the high temperature, but by blowing an inert gas, oxygen around the strip material S can be eliminated to suppress the oxidizing action. Therefore, the adhesive strength at the adhesive interface between the strip materials is increased, and the ozone crack resistance is further improved.

Each of the tire constituent members molded as described above is assembled in a conventionally known manufacturing method by the same procedure at the time of molding a green tire, and the molded green tire is vulcanized to obtain the air shown in FIG. It is possible to obtain a filled tire. Since the process of manufacturing a pneumatic tire is the same as the conventional process, detailed description thereof will be omitted.

FIG. 3 shows another example of the method for manufacturing a pneumatic tire according to the present invention, in which a partition wall 31 is installed in place of the strip material cooling device 23 installed in FIG.
The space 32 surrounded by 1 accommodates the tire forming drum X, the injection machine 21, and the pressure bonding device 22. An inert gas is supplied into the space 32 from an inert gas supply source 33 through an on-off valve 34, and the strip material S is wound in the atmosphere of the inert gas. Even in this case, the ozone crack resistance can be improved.

In the present invention, in the above-described embodiment, the strip material S is wound around the tire building drum X to form each tire constituent member, which is assembled during green tire molding. It may be a manufacturing method in which the strip material S is directly wound around the green tire on the tire forming drum during forming to directly form each tire constituent member.

Ozone cracks are caused by the second tread rubber layer 10 and the side rubber layer 11 on the tire surface which are in contact with the atmosphere.
Therefore, only these tire constituent members may be molded as described above.

[0029]

EXAMPLE An unvulcanized rubber strip material having a width of about 20 mm discharged from an injection machine was blown with nitrogen gas, and a circumference of 12 mm was obtained.
A tire forming member forming a side rubber layer was formed by winding around a 00 mm tire forming drum 25 times, and a pneumatic tire having a tire size of 205 / 65R15 was manufactured using the tire forming member (method of the present invention).

A tire constituent member constituting the side rubber layer was molded in the same manner as above without blowing nitrogen gas, and the same pneumatic tire as described above was manufactured using the tire constituent member (conventional method). .

In the method of the present invention and the conventional method, the temperature of the rubber strip material immediately after being discharged from the injection machine is about 140.degree. In the method of the present invention, the temperature of the rubber strip material immediately after winding the tire forming drum is about 100 ° C,
It was cooled to about 40 ° C.

A rim size of 15 × 6 was applied to each of these test tires.
When mounted on a 1/2 JJ rim and subjected to an ozone crack resistance evaluation test under the following measurement conditions, the results shown in Table 1 were obtained. Ozone crack resistance Each test tire was set to 120 kPa in air pressure and mounted on an indoor drum tester to load 74% (74% of the maximum load capacity described in JATMA for 205 / 65R15 size).
Under the conditions described above, after traveling 4800 km while blowing ozone at a concentration of 100 pphm to the sidewall portion, the ozone crack generated in the sidewall portion of each test tire was visually evaluated by a judge who was familiar with the ozone crack test. The results were evaluated in 4 levels.

Reference numeral 4 means that no ozone cracks occur, 3 means that small ozone cracks are not noticeable, 2 means that ozone cracks are conspicuous, 1 means that ozone cracks that are very conspicuous are large.

[0034]

[Table 1] It can be seen from Table 1 that the present invention can improve ozone crack resistance.

[0035]

As described above, the present invention improves the ozone crack resistance by winding the strip material while cooling it by blowing a gas, or by winding the strip material in an atmosphere of an inert gas. can do.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a tire meridian showing an example of a pneumatic tire manufactured by a method for manufacturing a pneumatic tire of the present invention.

FIG. 2 is an explanatory view of a main part showing an example of a method for manufacturing a pneumatic tire of the present invention.

FIG. 3 is an explanatory view of a main part showing another example of the method for manufacturing a pneumatic tire of the present invention.

[Explanation of symbols]

1 Tread Part 2 Sidewall Part 3 Bead Part 4 Carcass Layer 8 Belt Layer 9 First Tread Rubber Layer 10 Second Tread Rubber Layer 11 Side Rubber Layer 12 Cushion Rubber Layer 21 Injector 21a Discharge Port 23 Strip Material Cooling Device 24 Gas Spraying Port 25 Piping 26 Open / close valve 27 Gas supply source 31 Partition wall 32 Space S Strip material X Tire forming drum

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuya Takaoka             2-1, Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd.             Ceremony Company Hiratsuka Factory F-term (reference) 4F212 AH20 AK02 VA02 VK02 VK34                       VL09 VL11 VL19 VL28 VL31                       VL32

Claims (6)

[Claims] 1. A method for manufacturing a pneumatic tire, wherein a strip material made of unvulcanized rubber immediately after being discharged from an injection machine or an extruder is wound around a tire molding drum to mold a tire constituent member. A method for manufacturing a pneumatic tire, which is wound while being cooled by blowing gas onto a strip material. 2. The method for manufacturing a pneumatic tire according to claim 1, wherein the gas is an inert gas. 3. A method for manufacturing a pneumatic tire, wherein a strip member made of unvulcanized rubber immediately after being discharged from an injection machine or an extruder is wound around a tire molding drum to mold a tire constituent member. A method for producing a pneumatic tire, in which a strip material is wound in an atmosphere of an inert gas. 4. A pneumatic tire manufactured by the method for manufacturing a pneumatic tire according to any one of claims 1 to 3. 5. A gas blowing port for blowing a gas to a strip material made of unvulcanized rubber immediately after being discharged from the injection machine or the extruder is arranged in the vicinity of the discharge port of the injection machine or the extruder. A strip material cooling device with a gas supply source connected to the gas blowing port. 6. The strip material cooling device according to claim 5, wherein the gas supply source is an inert gas supply source.