Abstract: A method is disclosed for making a three layered parison for blow molding a biaxially oriented hollow article of thermoplastic material. One end portion of an extruded tubular body is heated to welding temperature and closed to a bottom by a forming step. The central layer of the multilayered body is removed from part of the end portion before the forming step takes place to insure that the central barrier layer of the body allows for an intimate welding together of the inner and outer layer. A similar operation is used in making the finish portion of a container at the opposite end of the tubular body.

Abstract: The mold halves of a blow mold device are mounted on a pair of arms encircling the mold halves in a semicircular arc which arms are latched together by latching means which are located at the parting line of the mold halves at both sides thereof. Due to this structure, merely the portion of the arms extending between said latching means is subjected to bending forces by the blowing pressure. For swinging the arms and actuating the latching means a common slide is provided in parallel relationship to the longitudinal axis of the blow mold, which slide includes a number of control cams which are engaged by cam followers cooperating with said arms and said latching means. The invention provides a compact and light-weight construction allowing to actuate a smaller mass in shorter time, thus increasing the production capacity of the blow mold device.

Abstract: The heated end of a parison is brought into a finish mold form to shape a finish profile suitable for setting up a closure. The parison is axially stretched by a stretch pin to pull out the heated plastic material adjacent the profile to a thinner cross section. This allows to obtain a considerable saving of weight of the plastic material.

Abstract: The heated end of a parison is brought into a finish mold form to shape a finish profile suitable for setting up a closure. The parison is axially stretched by a stretch pin to pull out the heated plastic material adjacent the profile to a thinner cross section. This allows to obtain a considerable saving of weight of the plastic material.

Abstract: The number of blow mold stations being associated with a blow wheel of a blow molding machine determines a large pitch of the mandrel receiving positions of the blow wheel. Contrarily the mandrels carrying the parisons are disposed very close to each other on the heating wheel which thus has a substantially smaller pitch. The larger pitch of the blow wheel shall be maintained throughout the complete machine to simplify the transfer of the parison. Accordingly the heating wheel receives the same pitch as the blow wheel including additional mandrel receiving positions which are served in a plurality of subsequent revolutions of the heating wheel.

Abstract: In the art of blow molding thermoplastic articles a pair of blow mold halves is closed around a parison. A blowing medium is applied so that the parison is thus blown to a container configuration. In this blowing step very high closing forces are necessary to maintain the mold halves in closed position. The invention provides for a plurality of biased pistons which are actuated by a pressure medium to support the mold halves on a stationary frame.