Patent ID: 7867415

Claim:
A die clamping method for a die clamping unit, the die clamping unit including (i) a stationary platen configured to hold a stationary die, (ii) a tie bar attached to the stationary platen, (iii) a halfnut positioning servomotor which advances and retreats the tie bar, (iv) a movable platen configured to hold a movable die and capable of advancing toward and receding from the stationary platen, (v) a halfnut which is provided on the movable platen and fixes the movable platen and the tie bar together by engaging the tie bar, (vi) an engaging mechanism which engages the halfnut with the tie bar, and (vii) a hydraulic die clamping cylinder which causes the tie bar to press the movable platen against the stationary platen, thereby performing a pressing operation in which the movable die and the stationary die are clamped, the method comprising: engaging the halfnut and the tie bar with each other by the engaging mechanism; driving the halfnut positioning servomotor to remove a clearance between the halfnut and an engaging groove of the tie bar before the hydraulic die clamping cylinder performs the pressing operation; and starting to control the hydraulic die clamping cylinder to cause the tie bar to press the movable platen against the stationary platen, thereby clamping the stationary die and the movable die after or during removal of the clearance.