US Patent 7393481 Method and apparatus for electric clamping

Disclosed is a method for electric clamping, which performs a clamping process in parallel with a core-drawing-in process, avoiding damages of molds and core mechanisms and enabling secure clamping. The method comprises the steps of: setting a check point, for judging safety of the clamping process in advance, in a position that is nearer to the operational start position by a predetermined distance in the mold opening direction than a position of the movable mold when the core-drawing-in process is expected to be completed, wherein the core-drawing-in process and the clamping process proceed in parallel with each other in a straight course for reciprocating a movable mold; activating a core system and a servo-motor to start an operation to draw a core into a cavity in parallel with an operation to move the movable mold in the mold closing direction; detecting whether or not the movable mold reaches the check point; judging whether or not the core reaches the position in which the core is fully drawn into the cavity at a point of time at which the movable mold reaches the check point, and confirming the completion of the core-drawing-in process. Thereafter, the clamping process of the molds is further continued if confirming that the core-drawing-in process is already completed.