Method of estimating a life of ball screw included in electric injection molding machine and life estimating system

A life estimating apparatus for estimating a life of a ball screw included in an electric injection molding machine comprising an injection unit having a heating barrel and an injection screw placed for rotation in the heating barrel, and an electric motor connected to the injection screw by a ball screw, said life estimating apparatus comprising:

• an encoder connected to the electric motor;
• an arithmetic-and-storage means for multiplying a moving speed of the ball in a unit time measured by the encoder, and an operating current supplied to the electric motor together during this time, and accumulating products, each formed by multiplying the moving speed of the ball screw and the operating current supplied to the electric motor in the unit time, and storing the accumulated products as cumulative data;
• and
• a life deciding means for determining a total energy amount indicating an amount of total energy supplied to the ball screw on the basis of the cumulative data stored in the arithmetic-and-storage means, and comparing the total energy value, and a predetermined life energy value for the ball screw that is associated with force generated by the ball screw and the moving speed of the ball screw to decide whether or not the life of a ball screw has terminated.

A life estimating apparatus for estimating a life of a ball screw included in an electric injection molding machine comprising an injection unit having a heating barrel and an injection screw placed for rotation in the heating barrel, and an electric motor connected to the injection screw by a ball screw, said life estimating apparatus comprising:

• an encoder connected to the electric motor;
• a torque meter interposed between the ball screw and the electric motor;
• an arithmetic-and-storage means for multiplying a moving speed of the ball in a unit time measured by the encoder, and an operating current supplied to the electric motor together during this time measured by the torque meter together, and accumulating products, each formed by multiplying the moving speed of the ball screw and the torque of the ball screw in the in the unit time, and storing the accumulated products as cumulative data;
• and
• a life deciding means for determining a total energy value indicating an amount of total energy supplied to the ball screw on the basis of the cumulative data stored in the arithmetic-and-storage means, and comparing the total energy value, and a predetermined life energy value for the ball screw that is associated with force generated by the ball screw and the moving speed of the ball screw to decide whether or not the life of a ball screw has terminated.