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Injection molding machine having a vector controlled AC drive system

  • US 5,362,222 A
  • Filed: 08/31/1993
  • Issued: 11/08/1994
  • Est. Priority Date: 08/31/1993
  • Status: Expired due to Term
First Claim
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1. An injection molding machine for producing a molded part by injecting a molten material into mold elements forming a mold cavity defining the molded part, the machine comprising:

  • (a) clamp means for supporting and moving the mold elements between open and closed positions;

    (b) injection means for injecting the molten material into the mold cavity, said injection means including a screw member rotatably and translatably carried in a tubular barrel having an end in communication with the mold cavity;

    (c) first drive means mechanically coupled to the clamp means for imparting relative motion to the mold elements;

    (d) second drive means mechanically coupled to the injection means for rotating the screw member;

    (e) third drive means mechanically coupled to the injection means for translating the screw member within the tubular barrel;

    (f) wherein at least one of the first drive means, the second drive means, and the third drive means further includes(1) an AC induction motor having a rotor, a stator comprised of a plurality of sets of three phase windings, and means for detecting angular positions of the rotor, and(2) vector controller means for controlling the AC induction motor in response to a motor command signal, the vector controller means being connected to the AC induction motor and including(i) a CPU for calculating torque and flux producing components of current passing through the stator windings,(ii) current controller means for producing pulse width modulated trigger signals based on the CPU calculations to regulate the current, and(iii) power amplifier means for receiving the pulse width modulated trigger signals and applying a controlled current to the stator windings to produce a commutation effect thereby creating a controlled torque and speed for the AC induction motor; and

    (g) machine control means connected to the vector controller means for producing the motor command signal.

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