Fanuc Corporation

Motohiro Nagaya

Noriaki Neko

Nobuaki Hashimoto

Tatsuya Kawasaki

Masao Kamiguchi

Susumu Ito

Tatsuhiro Uchiyama

Kaoru Hiraga

Shingo Komiya

Fuyuki Sugiura

Shuichi Wakebe

Hisaaki Matsui

An abnormality determination device includes: an oscillating signal sending unit configured to send out an oscillating signal which causes a rotary shaft of a servomotor to rotate and swing in a predetermined pattern, to a motor control unit configured to control the servomotor; a measuring unit configured to measure a physical quantity representing the state of the servomotor when the rotary shaft of the servomotor is swung; a comparing unit configured to compare a measurement signal of the measured physical quantity with a reference signal; and an abnormality determination unit configured to determine occurrence of an abnormality in a drive system which includes the servomotor and the motor control unit and ranges from a driven object to be driven by the servomotor to the motor control unit, based on comparison result from the comparing unit.

Abnormality determination device and abnormality determining method

A nozzle touch mechanism which does not allow an injection unit to move back by the force of inertia at the time of acceleration of injection and prevents leakage of the molten resin. A damper is arranged between the injection unit and a stationary platen secured to a base, so as to generate a strong braking force only at the time of high acceleration of the injection unit. A ball screw is rotated by driving an electric motor to move forward a nut member screwed onto the ball screw, whereby the injection unit is moved via a spring. When the injection unit is stopped by contacting a nozzle to a metal mold, the spring is contracted. When the amount of contraction of the spring reaches a predetermined value, the motor is stopped and locked such that the nozzle touch force corresponding to the amount of contraction of the spring is generated. Even though the injection unit undergoes the force working to move back the unit due to the inertia force at the time of acceleration of the injection, the injection unit is not moved back because the damper substantially prevents the movement back of the unit and the leakage of molten resin.

Nozzle touch mechanism

A system for controlling nozzle touch force, which is capable of maintaining the touch force relying upon a simple constitution. An electric motor moves the injection unit forward via a spring to bring a nozzle into contact with a metal mold. Further, the spring is compressed to impart a preset nozzle touch force. In the injection/pressure-maintaining step, the screw is driven, and a position/speed detector provided on a servo motor for injecting the resin detects the injection speed at regular intervals. A force produced by the force of inertia of the moving portions such as the injection screw and the pusher plate that move due to the injection operation, is found from the acceleration that is found from the injection speed. The amount of compression of the spring is controlled by varying the rotational position of the motor by an amount corresponding to the force that is found to maintain the nozzle touch force constant. Since the nozzle touch force is maintained constant, no resin leaks and an excess of nozzle touch force is not produced, either.

System for controlling nozzle touch force

An electric servo motor is controlled through a pressure control loop wherein a control object is the injection mechanism of an electric injection molding machine. A band elimination filter, which attenuates a frequency component of a band with predetermined width to be determined based on the resonance frequency of the control object, is provided in the pressure control loop.

Electric injection molding machine

Over the whole range of the injection process, standard injection speeds and pressures are set and sections for injection speed control and sections for pressure control are set according to the length of time t, screw position S, or injection pressure P, each after the start of injection, or following the combination of the length of time and the screw position or of the length of time and the injection pressure. The arrival at the point of changeover from one control section to another is followed by a control mode shift. If the shift is made for speed control, injection speed is controlled in a manner such that actual injection speed may agree with one standard injection pressure, while if pressure control is selected by the shift, there is provided feedback control which is put into practice so that actual injection pressure may coincide with one standard injection pressure. During the injection process, injection control is effected by speed control or pressure control, whichever is optimal for each of respective sections, whereby stabilized injection molding may be assured.

Method of injection control for injection molding machine

A reference pressure waveform for injection molding operation is set in advance; pressures corresponding to the pressure waveform are detected with predetermined detection times during the injection molding operation; pressure deviations between pressure stored in the pressure waveform, corresponding to the detection times, and the detected pressures are obtained; and the pressure deviation for each detection time is graphically displayed on a display screen along with the reference pressure waveform.

Growing community of inventors

Yamanashi, Japan

Motohiro Nagaya