Injection stretch blow molding process of performing a cycle of molding

Abstract

An injection stretch blow molding process performs a cycle of molding steps by circulating a plurality of neck mold sets for holding the neck portions of preforms. The first step is conveying a neck mold, by which a preform has been molded in the injection molding stage, disposed at one end of a horizontal path of movement for conveying said neck mold to the stretch blow molding stage disposed at the other end of the horizontal path of movement. The second step is returning a neck mold, from which a blow molded product has been ejected in the ejection stage, offset vertically from the middle of the horizontal path of movement, back to the injection molding stage, which is empty, through a vertical path of movement connecting the horizontal path of movement with the ejection stage and through the horizontal path of movement, after the first step has started. The third step is conveying a neck mold, holding a container blow molded in the stretch blow molding stage, to the ejection stage, which is empty, through the horizontal and vertical paths of movement after the second step has started. The entire system can be reduced in size, with the span between the tie rods being minimized and with the space of installation being reduced, even if a container having an increased bore diameter is to be molded in this system.