Patent ID: 6412324
Filing Date: 2002-07-02
Classification: B21C

Abstract:
An apparatus for extruding a metal pipe having a uniform inner diameter of a first dimension, said pipe having a first end section, a second end section and a middle section between said first end section and said second end section, said middle section having an outer diameter of a second dimension, said first end section having an outer diameter of a third dimension which is greater than said second dimension, said second end section having an inner portion which has an outer diameter of said third dimension, and an outer portion which has an outer diameter of said second dimension, said apparatus comprising:(a) a machine frame; (b) a container supported on the machine frame, said container having a central longitudinal axis and a longitudinal cylindrical first bore coaxial with said central longitudinal axis for receiving a cylindrical metal billet having a longitudinal cylindrical bore, said container having a rear opening to said first bore for receiving said billet and a front opening to said first bore; (c) a cylindrical die at said at said front opening, said die having a cylindrical second bore coaxial with said first bore and having a diameter which is greater than said second dimension and a third bore between said first bore and said second bore and having a diameter of said second dimension; and (e) a press located rearward of said container and movable along said central longitudinal axis toward and away from said container, said press having a circular forward pressing surface facing the rear opening of said container and a mandrel extending forwardly from said pressing surface toward said rear opening, said pressing surface and said mandrel being coaxial with said first bore, said pressing surface having substantially the same outer diameter as the inner diameter of said first bore with sufficient clearance to enable said pressing surface to move longitudinally within said first bore, said mandrel having a cylindrical forward section having an outer diameter equal to said first dimension and a rearward section having a rearward portion, a forward portion and an intermediate portion between said forward portion and said rearward portion, each of said forward portion and said rearward portion having an outer diameter of said first dimension, said intermediate portion having an outer diameter of a fourth dimension which is smaller than said first dimension, said mandrel having a central section between said rearward section and said forward section, said central section having an outer diameter of said fourth dimension, said mandrel having a frusto conical expanding section extending from said central section where said expanding section has an outer diameter of said fourth dimension to said forward section where said expanding section has an outer diameter of said second dimension.