Vulcanization device for pneumatic tire and method for vulcanizing pneumatic tire

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.