Patent ID: 7244378

Claim:
A mold clamping force correction method for a toggle-type mold clamping apparatus including a movable platen and a toggle mechanism for moving the movable platen in which change in mold clamping force is detected during production operation, and the mold clamping force is corrected on the basis of the detected change, the method comprising: 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 at least one physical quantity, and the closure of the mold being detected on the basis of detection of the change in the at least one 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; providing a closure position detection mode for detecting closure of a mold on the basis of a change in at least one physical quantity because of closure of the mold, detecting a position of the crosshead of the toggle mechanism at the time of detection of the closure of the mold, and obtaining, as a closure position, a position of the movable platen at the time of the closure of the mold from the detected position of the crosshead; previously operating the mold clamping apparatus in the closure position detection mode so as to store, as a reference value, a closure position at which a target mold clamping force is obtained; operating, in the production operation, the mold clamping apparatus in the closure position detection mode so as to obtain an actual closure position as a detection value; and correcting the mold clamping force on the basis of a deviation of the detection value from the reference value, wherein the at least one physical value 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.