Patent ID: 7244379

Claim:
A mold protection method for a mold clamping apparatus, in which a predetermined mold protection zone is set in a mold closing zone, and presence of a foreign object is detected as an anomaly on the basis of a change a physical quantity in the mold protection zone so as to protect a mold, the method comprising the steps of: moving a crosshead in a mold closing direction at a first speed until reaching a crossover point; moving the crosshead at a second speed less than the first speed until a preset threshold is reached, the preset threshold being a threshold for change that has been set in advance in each of the physical quantity, and the closure of the mold being detected on the basis of detection of the change in the physical quantity having reached the preset threshold; outputting an estimated torque (E) based on detection of an anomalous change in acceleration (A) of the crosshead at a time of closure of the mold; previously setting, as a reference position, a closed position of a movable platen at which a target mold clamping force is obtained; setting an end position of the mold protection zone with respect to the reference position; detecting, during a production operation, an actual closed position of the movable platen; and correcting the end position of the mold protection zone on the basis of a deviation between the detected position and the reference position, wherein the physical quantity includes the estimated torque (E) based on the detection of the anomalous change in the acceleration (A) of the crosshead, the anomalous change in the acceleration (A) being detected when the change in the acceleration (A) reaches the preset threshold.