| 摘要 |
PURPOSE:To prevent the breakage caused by an uneven wall thickness and make the distribution of the wall thickness uniform by a method wherein an optional member is made to contact with the part of a parison which is liable to be formed thinly in thickness and the blow forming is performed while the swelling of the parison is controlled partially up to the surface of a cavity. CONSTITUTION:The boardlike member 5 for controlling the swelling of the parison is faced with the lateral surface thereof remotest from the surface 2a of the cavity and is made to contact therewith by blowing-in of air, and it is made to retreat with somewhat resistance thereto being given as the parison 4 swells. As the result, the swelling of the contact part is controlled and thereby the transfer to the partial swelling is delayed, and thus the part which reaches the surface 2a of the cavity finally can not be stretched one-sidely, whereby the thin formation of the wall thickness is prevented and the distribution of the thickness of the wall of a hollow molded article A is made uniform. More excellent result can be obtained by a method wherein the wall thickness of the part with which the member 5 is made to contact is formed to be thick and uneven beforehand and further the heat capacity of the part is made higher than that of the other part. |
