ELECTRO-HYDRAULIC MEANS FOR OPENING AND CLOSING INJECTION MOLDS

摘要

The movable platen of an injection-molding machine is rigid with a nonrotatable lead screw engaged by a rotatable drive nut which is splined to a tubular input shaft surrounding the rear end of the lead screw. A cylinder on the machine frame carries an axially movable piston which, upon a stopping of shaft rotation in the mold-closed position, is brought to bear under hydraulic pressure against the nut to clamp the mold between the platens against the tie bars anchored to the frame. The input shaft is powered by a reversible two-speed motor which is switched to low-speed operation in a terminal phase of a lead-screw stroke to absorb excess energy in a nondissipative manner.