Electromagnetic re-draw sleeve actuator

Claim 1

In a can forming apparatus in which a cylindrical re-draw sleeve holds a can material preform cup against an ironing die while a ram pushes said cup through an opening in said die to form a can body, an improvement comprising: a linear electromagnet actuator having an actuator core mounted to said apparatus, a coil element moveable between a first position and a second position along an axis of relative movement, a magnetic circuit for defining radially directed flux in both an inward and an outward direction relative to said axis of relative movement, wherein said coil is disposed within the flux path, and means for applying current to said coil so that current can be applied in one direction through the portions of the coil disposed in the inwardly radially directed flux, and applied in the opposite direction through the portions of the coil disposed in the outwardly radially directed flux so that the flux/current products are additive, said re-draw sleeve being mounted to said coil element, and further being in a retracted position to allow placement of said can material preform against said ironing die when said coil element is in said first position and in an extended position to hold said can material preform against said ironing die when said coil element is in said second position; an electromagnet mounted to said apparatus; a ring of magnetic material mounted coaxially to said re-draw sleeve so that said ring is adjacent said electromagnet when said re-draw sleeve is in said extended position; and a timing and control circuit to activate said actuator to place said coil element in said second position when said ram is in a retracted position and to return said coil element to said first position when said ram is in an extended position, and further to activate said electromagnet when said re-draw sleeve has been brought to said extended position so that magnetic force on said ring holds said re-draw sleeve against said can material preform and to deactivate said electromagnet when said re-draw sleeve is to return to said retracted position.