Method of forming belted radial tires from a cylindrical tire band

Abstract

Discloses method of forming a belted radial tire from a cylindrical radial green tire band having biased corded belts which are adapted to pantograph and expand circumferentially as the tire band is shaped to be molded into a finished tire without 'S-ing' of the radial cords of the carcass plies under the belts of the finished tire as may be caused by the pantograph action of the belts while the tire band is being expanded into finished shape. Involves lowering a belted radial green tire band of generally cylindrical shape to seat into a conventional tire molding press over the inflatable curing bladder, then applying inflation pressure into the curing bladder to a first pressure level while partially closing the press. The inflation pressure is continued to a second pressure level while continuing to close the press. The belts pantograph and circumferentially expand substantially completely through application of the second pressure until the tire band has reached a generally circular U-shape. The second pressure level is held while the press is in partially open position for a sufficient time interval to retain the belts in expanded position while the carcass cords under the belts stretch to be disposed at substantially 0.degree. with respect to the tire axis. The pressure is then lowered from the second pressure level to about the same as the first pressure level while the press remains partially open to permit ready closure of the press about the tire band. Then the press is fully closed and the higher molding pressure and temperature is applied to cure the tire band into a finished tire as usual.