Method of manufacturing pneumatic tire and system for manufacturing pneumatic tire

A system for manufacturing a pneumatic tire provided with a bladder device including a cylindrical vulcanization bladder insertable in a green tire, and a transport device configured to transport the green tire supported by the vulcanization bladder inflated to a predetermined green tire supportable internal pressure together with the bladder device to a vulcanization device, the green tire being vulcanized, in a mold attached to the vulcanization device, by the vulcanization bladder being inflated to a predetermined vulcanization internal pressure to press the green tire against the mold while heating the green tire at a predetermined temperature, the system comprising:

• a positioning device configured to position the green tire in a predetermined position in the bladder device;
• and
• a control device configured to control movement of the positioning device;
• wherein
• shaft central position data and central position in a shaft direction data of the vulcanization bladder of the bladder device placed for holding outside the mold at a holding position are input into the control device beforehand;
• the bladder device is placed at the holding position with the shaft direction of the vulcanization bladder parallel to a vertical direction;
• the positioning device is provided with an arm portion configured to support an upper bead portion of the green tire on its side;
• the positioning device supporting the green tire is moved on the basis of the shaft central position data and the central position in the shaft direction data of the vulcanization bladder;
• the vulcanization bladder is inserted in the green tire with a tire axis central position of the supported green tire and a shaft central position of the vulcanization bladder aligned, and a central position in a tire width direction of the green tire and a central position in the shaft direction of the vulcanization bladder are aligned;
• the system includes a position sensor configured to detect the central position in the tire width direction of the green tire successively from a side direction of the green tire suspended by the positioning device with the vulcanization bladder inserted in the green tire;
• vertical movement of the positioning device is controlled on the basis of the central position in tire width direction data of the green tire detected by the position sensor and the central position in the shaft direction data of the vulcanization bladder input into the control device to align the central position in the tire width direction of the green tire with the central position in the shaft direction of the vulcanization bladder;
• three or more vertical distance sensors are provided on the positioning device;
• a levelness of the green tire is obtained on the basis of vertical distances to the suspended green tire detected by the vertical distance sensors;
• on the basis of an obtained result, the suspended green tire is kept within a preset levelness tolerance range and the central position in the tire width direction of the green tire and the central position in the shaft direction of the vulcanization bladder are aligned;
• in a state positioned as such, the vulcanization bladder is inflated to the predetermined green tire supportable internal pressure and brought into contact with an inner surface of the green tire to support the green tire;
• the green tire together with the bladder device is transported to the vulcanization device by the transport device and set in the mold;
• and
• the vulcanization bladder is inflated to the predetermined vulcanization internal pressure, which is higher than the predetermined green tire supportable internal pressure.