Controller for an ejector mechanism in an injection molding machine

A controller for controlling an ejector mechanism of an injection molding machine having means for moving ejector pins forward to project into a mold, springs for generating an elastic force to return the ejector pins to a retracted position, and brake means for generating a retaining force to retain the ejector pins at a terminal position of the forward motion, said controller comprising:

• position detecting means for detecting a position of the ejector pins;
• elastic force detecting means for detecting an elastic force of the springs during a forward motion of the ejector pins from a retracted position;
• determining means for determining a criterial position of the ejector pins where the detected elastic force of the springs is equivalent to the retaining force of the brake means;
• and
• means for issuing an alarm if a preset terminal position of the forward motion of the ejector pins is remoter from the retracted position than the criterial position of the ejector pins.

A controller for controlling an ejector mechanism of an injection molding machine having means for moving ejector pins forward to project into a mold, springs for generating an elastic force to return the ejector pins to a retracted position, and brake means for generating a retaining force to retain the ejector pins at a terminal position of the forward motion, said controller comprising:

• position detecting means for detecting a position of the ejector pins;
• elastic force detecting means for detecting an elastic force of the springs during a forward motion of the ejector pins;
• determining means for determining a position of the ejector pins immediately before the detected elastic force of the springs exceeds the retaining force of the brake means in the forward motion of the ejector pins;
• and
• means for altering a preset terminal position of the forward motion of the ejector pins to be the determined position, if the preset terminal position of the forward motion the ejector pins is remoter from the retracted position than the determined position.