Abstract: A multilayered hollow article is formed by first injection molding the outer layer parison on a core rod and then forming a clearance between this first parison and the core rod in a second mold, followed by injection molding the inner layer parison through the inside of the core rod to the outside of the core rod and into intimate contact with the outer layer, and subsequently blow molding the formed two-layered parison in a blow mold to obtain the final configuration. This method and apparatus are particularly suitable to forming multilayered containers wherein the innermost layer is a barrier thermoplastic, such as polyvinylidene chloride, and wherein the dimensional integrity of the innermost layer must be maintained.

Abstract: A plurality of core rods with parisons thereon are mounted to an indexing head with the core rods disposed in a temperature conditioning chamber and wherein the core rods are simultaneously rotated to effect temperature distribution throughout the parisons. Pluralities of core rods are angularly disposed and simultaneously rotated. The apparatus is particularly useful in orientation injection blow molding, wherein the parison is a relatively thick cross section or wherein the parison thermoplastic has a low thermal conductivity.

Abstract: An injection molded parison is positioned in a mold cavity having a high length to diameter ratio and being provided with means along the length of the cavity to selectively and alternatively exert positive pressure as an air cushion, or negative pressure as a vacuum, on portions of the parison as the parison is expanded through the length of the cavity. The thickness of the expanding parison is thus controlled so that in subsequent expansion in the blow mold, the finished hollow article will have the desired wall thickness.

Abstract: An injection molded parison is slightly preblown from the core rod and cooling water is then circulated both externally and internally on the parison so as to effect a rapid temperature decrease in the parison. The internal circulating cooling water initially passes through the core rod and then into contact with the parison. After circulating the water, a drying fluid is then circulated into contact with the parison to remove residual water. The method and apparatus of this invention are useful in controlling the cooling of certain thermoplastic parisons in which rapid cooling is necessary to achieve the desired crystal growth for subsequent biaxial or multiaxial orientation.

Abstract: A core rod for an injection molding machine having an axially disposed blow air conduit connected to a valve at the free end of the core rod, and an annular passageway around the air conduit for flow of a temperature control fluid. The temperature control fluid is preferably channeled in a two-pass or alternatively in a double-spiral flow pattern. This core rod is particularly suited for use in biaxial orientation blow molding wherein rapid and accurate temperature control of the parison is required.