Patent ID: 6024911
Filing Date: 2000-02-15
Classification: B29C,B65D

Abstract:
A method of producing an injection molded article in a mold, said molded article being made of a polymeric material and having an integral circumambient rim, said rim having a wall and a closed hollow internal channel, said mold comprising at least one mold cavity defining the shape of said molded article, said mold cavity having a rim forming mold cavity portion, the rim forming mold cavity portion further having at least one reservoir cavity of enlarged cross-section, said mold further having at least one injection gate in communication with said mold cavity, and at least one gas duct, there being one gas duct in communication with each of said reservoir cavities, said method comprising the steps of:injecting said molten polymeric material into said mold cavity via said injection gate;injecting pressurized gas into said molten polymeric material via said at least one gas duct;expanding said rim forming mold cavity portion by way of an expansion means; andwherein said reservoir cavity is sized and shaped to serve as a leveling chamber for the gas during injection of the gas and a material reservoir for the polymeric material, whereby said pressurized gas forces an excess of said molten polymeric material from said reservoir cavity into other portions of said rim forming mold cavity being expanded by said expansion means, said pressurized gas forming said hollow internal channel and said excess molten polymeric material being evenly distributed about the rim thereby forming said wall, the polymeric material remaining in said reservoir cavity forming a bulge integral with said rim of said molded article.