Patent ID: 7168944
Filing Date: 2007-01-30
Classification: B29C

Abstract:
1. An injection molding machine with an improved drive system including a clamp unit, comprising: at least one tie bar configured to be connected to a first stationary platen and to a second stationary platen; a movable platen operatively disposed between the first stationary platen and the second stationary platen, said movable platen being configured to be connected to drive structure; an hydraulic motor configured to be selectably in communication with an accumulator via an hydraulic valve; a rotational drive unit configured to simultaneously (i) power said drive structure to cause translation of said movable platen, and (ii) power said hydraulic motor to cause storage of energy in said accumulator; and an hydraulic piston connected to said movable platen and in selectable communication with said accumulator via said hydraulic valve, wherein pressure from said accumulator acts to maintain the position of said movable platen during the injection process.