PRODUCT COOLING FOR BLOW MOLDING

• US 3,837,776 A
• Filed: 07/06/1973
• Issued: 09/24/1974
• Est. Priority Date: 07/06/1973
• Status: Expired due to Term

• Current Assignee: TDT Incorporated 208 Cougar Court
• Original Assignee: John J. Farrell
• Inventors: Farrell, John J.
• Primary Examiner(s): Weidenfeld, Gil
• Application Number:
  US05/377,052
• Time in Patent Office: 445 Days
• Field of Search: 425/DIG.231,DIG.209,DIG.204,DIG.211,DIG.213,DIG.203,242B,387B,324B
• US Class Current: 425/526
• CPC Class Codes: B29C 2049/023 using inherent heat of the preform, i.e. 1 step blow moulding
• CPC Class Codes: B29C 43/12 using bags surrounding the moulding material or using membranes contacting the moulding material
• CPC Class Codes: B29C 49/06 Injection blow-moulding
• CPC Class Codes: B29C 49/44 for applying pressure through the walls of an inflated bag

Abstract

A blow molding machine for making plastic articles has the plastic blown to the desired shape without requiring a blow mold cavity. A plastic coating is applied to a core rod which is covered by an expandible balloon, in deflated condition, hugging the core rod. The extent of expansion of the blown article is regulated by metering the amount of fluid used for blowing; and more accurate control can be obtained by using a liquid for blowing. A stream of air against the outside of the plastic cools the article. By making the wall of the balloon thicker at localized areas the expansion and consequent shape of the article can be controlled. If wide flat bottoms are desired, a baffle can be used for regulating the lengthwise expansion of the balloon and blown article.

Claims

1. Plastics blow molding apparatus comprising a head and at least one core rod extending from the head, a coating station, means at said coating station for applying a coating of plastic material to said core rod, a blowing station, means at said blowing station for blowing the coating on said core rod into an article and means for limiting the size of the article being blown with a substantial portion of the outside surface of the article not being confined by a closed mold, said blowing station further including a chamber in which the coated core rod is located during the blowing operation and means for blowing fluid into said chamber and into direct contact with the outside surface of the plastic material for cooling same before the core rod and blown article are moved from the blowing position.

2. The plastics blow molding apparatus described in claim 1 characterized by a passage through which fluid is blown into the chamber.

3. The plastics blow molding apparatus described in claim 2 characterized by a blower for supplying fluid to the chamber, a timer for controlling the supplying of fluid to the chamber from the blower, and means for operating the timer in accordance with the delivery of a core rod to the chamber.

4. The plastics blow molding apparatus described in claim 3 characterized by the chamber being divided into two compartments, including a first compartment in which the coated core rod is located when at the blowing station, and a second compartment with a perforate partition separating it from the first compartment and having an exhaust outlet for rapid escape of fluid from the second compartment, the blower being in position to supply fluid to the first compartment, and the partition having its perforate area limited in size in proportion to the output of the blower so that the fluid pressure in the first compartment is substantially higher than that in the second compartment.

5. The plastics blow molding apparatus described in claim 4 characterized by the partition being a fine mesh wire screen.

6. The plastics blow molding apparatus described in claim 1 characterized by the means for limiting the size of the blown article being an apparatus that supplies a measured quantity of fluid to the core rod for blowing the coating on the core rod.

7. The plastics blow molding apparatus described in claim 6 characterized by the apparatus that supplies the measured quantity of fluid being a liquid metering device.

8. The plastics blow molding apparatus described in claim 6 characterized by an expandible jacket on the core rod and over which the coating of plastics material is applied, the core rod having openings therein through which the fluid flows into contact with the inside surface of the expandible jacket to blow the coating without having direct contact with the coating.

9. The plastics blow molding apparatus described in claim 1 characterized by a mold that holds the end portion of the coating on the core rod while the rest of the coating is blown, and means for moving a part of the mold with respect to another part to open the mold and release the end portion of the coating for movement of the core rod to another station.

10. The plastics blow molding apparatus described in claim 9 characterized by other structure connected with the mold parts for opening and closing movement therewith, said other structure forming the chamber at the blowing station around the core rod and the coating thereon, said chamber having an inlet opening through which fluid is blown into said chamber and an exit opening through which fluid escapes from the chamber, and means in the chamber for causing the fluid in the chamber to circulate around the outside surface of the blown article on the core rod.

11. The plastics blow molding apparatus described in claim 1 characterized by a cooled surface for confining the length to which the coating on the core rod can be blown, the sides of said coating being unconfined when the coating on the core rod is blown into contact with said cooled surface, and the means for blowing fluid being directed into contact with the unconfined sides of the blown article.

12. The plastics blow molding apparatus described in claim 11 characterized by the cooled surface being a thin metal partition to both sides of which fluid is supplied by said means for blowing fluid.

13. The plastics blow molding apparatus described in claim 1 characterized by the head being an indexing head having faces on different sides thereof to form a polygon, a plurality of core rods extending from each face, stations around the indexing head corresponding to the different sides of the polygon, an indexing control that moves the indexing head successively through angles corresponding to the angular spacing of said stations to shift the core rods progressively to successive stations, an injection mold at one station, the next station around the indexing head constituting the blowing station at which the coating on the core rod is blown and at which the fluid is blown into direct contact with the outside surface of the blown article while the article is still in the position in which it is blown, and means for controlling the cooling of the blown article at said blowing station including a blower and a timer controlling the amount of fluid supplied to the outside of the blown article.

14. The plastic blow molding apparatus described in claim 1 characterized by a plurality of core rods extending from said head.