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Title: Apparatus and method for making blow molded containers with high length to diameter ratio
Claims: What is claimed is: 1. Injection blow molding apparatus for forming a hollow article having a substantially greater length than diameter including a core rod, an injection station having an injection mold in which a parison is injected over the core rod, a blowing station, means to transfer said core rod and parison from said injection station to said blowing station, said blowing station including a mold having a cavity therein and into which the core rod projects for a blowing operation, the cavity being substantially longer than the core rod and parison in the direction in which the core rod extends into the cavity, and means for increasing the length to diameter ratio to which the parison can be blown including a tube that extends into the mold cavity from the end of the cavity opposite to that at which the core rod extends into the cavity, the core rod and tube being in substantial alignment with one another and the tube having a diameter greater than that of the core rod and with clearance for the parison to extend into the tube, means for blowing the parison to expand it lengthwise in the tube, and means for progressively withdrawing the tube from the blow mold cavity during blowing of the parison. 2. The injection blow molding apparatus described in claim 1 characterized by a rod within the tube and of a diameter providing an abutment surface limiting the extent to which the parison can expand lengthwise of the tube. 3. The injection blow molding apparatus described in claim 2 characterized by the rod extending outside of the mold to a location beyond the tube, means for holding the rod in a substantially fixed position with respect to the blowing station mold, the tube being slidable on the rod as a bearing, and positioning means outside of the cavity for stopping movement of the tube when the end of the tube is at substantially the end of the blow mold cavity which is remote from the end through which the core rod extends into the cavity. 4. The injection blow molding apparatus described in claim 3 characterized by a motor, and motion-transmitting means through which the motor moves the tube along the length of the rod during the blowing of the parison in the blow mold. 5. The injection blow molding apparatus described in claim 4 characterized by speed control means for the motor, and means for programming the supply of air to the blowing mold and the supply of working fluid to the tube operating motor in timed relation to withdraw the tube from the blow mold cavity during the blowing operation and in relation with the completion of the blowing of the parison in the blow mold cavity. 6. The injection blow molding apparatus described in claim 2 characterized by a motor for moving the rod lengthwise of the tube with the end of the rod nearest to the cavity operating like a piston in the tube, and an adjustable control for stopping the movement of the rod when it reaches a predetermined location. 7. The injection blow molding apparatus described in claim 2 characterized by means for holding the rod in a fixed position during movement of the tube lengthwise along the rod. 8. The injection blow molding apparatus of claim 1, further comprising means to prevent the parison from contacting the tube during blowing of the parison to expand the parison lengthwise in the tube. 9. Injection blow molding apparatus for forming a hollow article having a substantially greater length than diameter including a core rod, an injection station having an injection mold in which a parison is injected over the core rod, a blowing station, means to transfer said core rod and parison from said injection station to said blowing station, said blowing station including a mold having a cavity therein and into which the core rod projects for a blowing operation, the cavity being substantially longer than the core rod and parison in the direction in which the core rod extends into the cavity, and means for increasing the length to diameter ration to which the parison can be blown including a tube that extends into the mold cavity from the end of the cavity opposite to that at which the core rod extends into the cavity, the core rod and tube being in substantial alignment with one another and the tube having a diameter greater than that of the core rod and with clearance for the parison to extend into the tube, means for blowing the parison to expand it lengthwise in the tube, and means for progressively withdrawing the tube from the blow mold cavity during blowing of the parison characterized by the inside diameter of the tube being greater than the outside diameter of the parison so that there is an air space between the parison and the inside surface of the tube for providing an air cushion that resists expansion of the parison into contact with the inside surface of the tube. 10. The injection blow molding apparatus described in claim 9 characterized by the tube having a double wall that provides an air chamber in the wall of the tube, the inner wall having orifices therein, and means providing air under pressure to said chamber for discharge of air from the air chamber through said orifices and into contact with the parison to control the amount of pressure of the air in said air space and the resulting pressure of the air cushion that resists expansion of the parison into contact with the inside surface of the tube. Other info: Inventors: Farrell, John J. (Green Brook, NJ, US) Application Number: 512294 Filing Date: 1974-10-04 Publication_date: 1976-02-03 Assignee: Farrell Patent Company (Greenbrook, NJ) Primary Class(es): 425/529 425/533, 425/534, 425/535 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Husar, Francis S. Assistant Examiner: Charvat, Robert J. Attorney: Feldman; Marvin |
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