Patent ID: 6129870
Filing Date: 2000-10-10
Classification: B29C

Abstract:
A method of controlling the thickness of an unfoamed outer skin of a foamed plastic article formed within an injection molding process, said method comprising:a. providing a mold unit, said mold unit comprising a first mold section and a second mold section, said first mold section and said second mold section forming a mold cavity upon being clamped together;b. providing a plastic injection material;c. providing a central processing unit, said central processing unit in operable communication with said mold unit, said central processing unit capable of controlling the volume of said mold cavity;d. selecting a triggering delay time, said triggering delay time corresponding to a time required to form said unfoamed outer skin to a desired thickness for a selected set of operating conditions;e. providing said triggering delay time to said central processing unit;f. clamping said first mold section and said second mold section together thereby forming said mold cavity;g. injecting said plastic injection material into said mold cavity thereby substantially filling said mold cavity; andh. controlling said thickness of said unfoamed outer skin by maintaining the volume of said mold cavity substantially constant for a period of time equal to said triggering delay time.