Roll threading apparatus for threading end blank for metal drum container

A roll threading apparatus for threading a substantially circularly shaped end blank for use on a metal drum container, said end blank having a tubular flange integrally formed therein such that an axis of the tubular flange is disposed at a position displaced from a center of said end blank, comprising:

• a turntable for supporting said end blank, said turntable being rotatable about an axis of the tubular flange such that said circularly shaped end blank is rotated eccentrically on said turntable;
• an annular threading roll die mounted on said turntable and rotatable with said turntable about the axis of said tubular flange, said annular threading roll die receiving therein the flange of the end blank such that a full outer circumferential surface of the tubular flange is held against an inner circumferential surface of the annular threading roll die, said annular threading roll die having a first threading surface on the full inner circumferential surface thereof for threading the tubular flange;
• a threading roll disposed for insertion into the tubular flange of the end blank supported on said turntable in spaced relationship to an inner circumferential surface of the tubular flange, said threading roll being rotatable and movable toward the inner circumferential surface of the tubular flange, said threading roll having a second threading surface on a full outer circumference thereof which is complementary to said first threading surface;
• rotating means for rotating said annular threading roll die through said turntable and said threading roll in synchronism with each other in the same direction;
• and
• pressing means for moving said threading roll toward said annular threading roll die to press said threading roll against the inner circumferential surface of said tubular flange while said annular threading roll die and said threading roll are being rotated by said rotating means;
• the arrangement being such that while said first and second threading surfaces are being rotated, the first and second threading surfaces are pressed against the tubular flange to thread the tubular flange.