Fanuc Corporation

Tatsuya Kawasaki

Motohiro Nagaya

Nobuaki Hashimoto

Tatsuhiro Uchiyama

Junpei Maruyama

Satoshi Takatsugi

Wataru Shiraishi

Mitsushi Yoshioka

Hiroshi Watanabe

Toshio Ishikuro

A controller for an injection molding machine capable of reducing an extension of a cycle time in a screw retreat process after the end of measurement, obtaining a more accurate and uniform measured resin amount, and determining measurement conditions in a short period of time. After the measurement is finished, the screw is stopped from rotating and retreated at a first speed V. The screw is reversely rotated at a predetermined speed Rv in a set zone. As this is done, the screw is retreated at a second speed Vlower than the first speed V. After the reverse rotation zone is terminated, the screw is stopped from rotating and retreated at a third speed Vto a set retreat stop position. By doing this, the cycle time can be made shorter than in the case where the retreat and reverse rotation of the screw are performed separately. Since the retreating speed of the screw is low while the screw is being reversely rotated, a sudden pressure change can be suppressed, so that precise measurement can be made. Since conditions for the reverse rotation and retreat of the screw can be regulated independently, they can be adjusted to optimum conditions in a short period of time.

Controller of injection molding machine

An aligning device whereby an injection nozzle can be easily aligned with the sprue of a mold. A stationary platen has a locating hole formed therein and a tapered portion continuous with the locating hole and tapered in a direction such that the tapered portion broadens toward the injection nozzle side. An aligning jig to be fitted into the locating hole and the tapered portion is prepared. The jig has a recess formed in the center of an end face thereof and having a shape matching that of the distal end of the injection nozzle. The jig is fitted into the locating hole, and the injection nozzle is engaged with the recess to align the injection nozzle with the axis of the locating hole. Since the mold is attached to the stationary platen such that the axis of the sprue of the mold is aligned with that of the locating hole, the injection nozzle becomes aligned with the sprue. The injection nozzle can be easily and accurately aligned even while the mold is attached to the stationary platen and also the mold and the injection cylinder are heated to high temperature.

Aligning device for an injection nozzle

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.

Growing community of inventors

Yamanashi, Japan

Tatsuya Kawasaki