Mold protection apparatus, mold protection method and mold clamping apparatus

A mold protection method of an opening/closing apparatus that opens/closes a mold by moving a movable platen with use of drive of a motor, the movable platen being formed to be movable in a direction towards or away from a fixed platen having a fixed mold fixed thereto and being fixedly provided with a movable mold to form the mold integral with the fixed mold, the method comprising:

• obtaining an actual operation drive force output from the motor;
• calculating a theoretical operation drive force of the motor;
• and
• comparing a difference between the actual operation drive force and the theoretical operation drive force with a threshold value.

A mold clamping apparatus comprising:

• a fixed platen to which a fixed mold is disposed;
• a movable platen that is arranged to face the fixed platen and to which a movable mold is disposed;
• an opening/closing mechanism that enables moving the movable platen;
• and
• a control apparatus that controls the opening/closing mechanism,
• wherein the opening/closing mechanism has a drive unit that produces a drive force that enables moving the movable platen, and
• the control apparatus comprises:
• a deriving means configured to obtain an actual operation drive force output from the drive unit;
• a calculating means configured to calculate a theoretical operation drive force of the drive unit;
• and a comparing means configured to compare a difference between the actual operation drive force and the theoretical operation drive force calculated by the calculating means with a threshold value.