Method for blow molding

Claim 1

In a method of blow molding plastic articles from heated thermoplastic parisons, the steps of: (1) conveying a plurality of parisons in succession through an enclosure defining a path of travel traversing successive, equally spaced work stations including successive radiant heating stations and a subsequent blow molding station, while rotating each parison except at said blow molding station; (2) temporarily interrupting said conveying along said path of travel at each successive radiant heating station while still continuing rotating such parisons; (3) conveying the parisons serially from the last radiant heating station to said blow molding station; (4) exposing each parison at each radiant heating station to infrared radiation and thus progressively providing each parison with a desired heat profile for blow molding; (5) injecting ambient air into said enclosure intermediate the last radiant heating station and said blow molding station; (6) blowing the injected air past the plurality of heating stations and the parisons in a direction counter to the direction in which the parisons are conveyed, each parison being heated to blow molding temperature by the radiation; (7) ceasing rotation of each parison at the blow molding station and there blow molding each parison in turn after it has been subjected (1) to the infrared radiation at each heating station and (2) to the heating-cooling effect of the countercurrent air to provide a blown plastic article.

Claim 3

The method of blow molding a plastic article from a parison of thermoplastic material, comprising steps of: (1) conveying the parison through a tunnel to and between successive, equally spaced operating stations including a plurality of successive radiant heating stations and a subsequent blow molding station; (2) halting the parison in alignment with each station in turn; (3) exposing the parison to infrared heating radiation at each radiant heating station and imparting a desired axially variable heat profile to such parison by baffling the radiation going to such parison at at least one of said radiant heating stations; (4) blowing air through said tunnel counter-current to the path of travel of said parison through said radiant heating stations to continuously subject the parison to the heating-cooling effect of the air during the performance of steps 1-3, each parison being heated to the blow molding temperature by the infrared heating radiation; and (5) blowing the heated parison at said blow molding station to provide a blown plastic article;

Claim 4

The method of blow molding a plastic article from a parison of thermoplastic material, comprising steps of: (1) conveying the parison through a tunnel to and between successive, equally spaced operating stations including a plurality of successive radiant heating stations and a subsequent blow molding station; (2) halting the parison in alignment with each station in turn; (3) exposing the parison to infrared heating radiation at each radiant heating station and imparting a desired axially variable heat profile to such parison by baffling the radiation going to such parison at at least one of said radiant heating stations; (4) blowing air through said tunnel counter-current to the path of travel of said parison through said radiant heating stations to continuously subject the parison to the heating-cooling effect of the air during the performance of steps 1-3, each parison being heated to the blow molding temperature by the infrared heating radiation; and (5) blowing the heated parison at said blow molding station to provide a blown plastic article;