Vulcanization device for pneumatic tire and method for vulcanizing pneumatic tire
Provided are a vulcanization device for a pneumatic tire and a method for vulcanizing a pneumatic tire. A pressurizing medium having a relatively low pressure is supplied through a pressurizing medium low-pressurization/supply line into a vulcanization bladder having a tube-like shape inserted into a green tire in a vulcanization mold to inflate the vulcanization bladder. Thereafter, a heating medium is supplied through a heating medium supply line into the vulcanization bladder ( 2 ). Then, a pressurizing medium having a relatively high pressure is supplied through a pressurizing medium supply line into the vulcanization bladder to increase internal pressure of the vulcanization bladder while the media in the vulcanization bladder are circulated through a circulation line extending outside the vulcanization bladder, thereby vulcanizing the green tire.
1. A vulcanization device for a pneumatic tire comprising:
a vulcanization bladder having a tube-like shape;
a heating medium supply line and a pressurizing medium supply line communicably connected to an inside of the vulcanization bladder,
a heating medium being supplied into the vulcanization bladder through the heating medium supply line, the heating medium being steam, and
a pressurizing medium being supplied into the vulcanization bladder through the pressurizing medium supply line, the pressurizing medium being inert gas; and
a pressurizing medium low-pressurization/supply line and a circulation line communicably connected to the inside of the vulcanization bladder;
wherein
the pressurizing medium having a low pressure flows and is supplied into the vulcanization bladder through the pressurizing medium low-pressurization/supply line to inflate the vulcanization bladder at a start of vulcanization,
the heating medium is supplied into the vulcanization bladder through the heating medium supply line upon the vulcanization bladder being in an inflated state,
media in the vulcanization bladder circulates through the circulation line upon the heating medium being supplied into the vulcanization bladder, and
the media having a high pressure flows and is supplied into the vulcanization bladder through the pressuring medium supply line upon the media in the vulcanization bladder circulating via the circulation line to increase internal pressure of the vulcanization bladder;
wherein a pressure of the pressurizing medium having a low pressure is from 10% to 40% of a pressure of the pressurizing medium having a high pressure;
after a heating medium is supplied to the interior of the vulcanization bladder for a predetermined time, while the media in the interior of the vulcanization bladder is circulated through the circulation line, the pressurizing medium having a high pressure is supplied into the interior of the vulcanization bladder.
2. The vulcanization device for a pneumatic tire according to claim 1 , wherein the pressurizing medium low-pressurization/supply line comprises a branch line branched off from the pressurizing medium supply line and a pressure reducing valve disposed on the branch line.
3. A method for vulcanizing a pneumatic tire, including supplying a heating medium and a pressurizing medium into a vulcanization bladder having a tube-like shape inserted into a green tire in a vulcanization mold to vulcanize the green tire, the heating medium being steam and the pressurizing medium being inert gas, the method comprising the steps of:
upon a pressurizing medium having a high pressure being used as the pressurizing medium and a pressurizing medium having a low pressure being used as the pressurizing medium,
supplying the pressurizing medium having a low pressure into the vulcanization bladder to inflate the vulcanization bladder; thereafter
supplying the heating medium into the vulcanization bladder; and thereafter
supplying the pressurizing medium having a high pressure into the vulcanization bladder to increase internal pressure of the vulcanization bladder while circulating media in the vulcanization bladder through a circulation line extending outside the vulcanization bladder and vulcanizing the green tire;
wherein a pressure of the pressurizing medium having a low pressure is determined to be from 10% to 40% of a pressure of the pressurizing medium having a high pressure.
4. The method for vulcanizing a pneumatic tire according to claim 3 , wherein upon supplying the pressurizing medium having a low pressure into the vulcanization bladder, the pressurizing medium having a high pressure is supplied to a pressurizing medium low-pressurization/supply line branched off from a pressurizing medium supply line configured to allow the pressurizing medium having a high pressure to be supplied into the vulcanization bladder, and the pressurizing medium having a low pressure reduced by a pressure reducing valve disposed on the pressurizing medium low-pressurization/supply line is supplied through the pressurizing medium low-pressurization/supply line into the vulcanization bladder.