Injection molding machine

Claim 2

An injection molding machine including a flow rate control device mounted between one injection screw mounted so that it may be rotated freely in a housing and reciprocated freely by an injection piston·cylinder unit and one injection nozzle mounted in the leading end of the housing so as to inject the molten resin into the mold cavity, said control device serving to control the rate of flow of the molten resin from said injection screw to said injection nozzle.

Claim 3

The injection molding machine as set forth in Claim 1, characterized in that said flow rate control device comprises the following component parts; that is to say, (a) a portion having a first and second slender holes formed in the leading end of said housing and having different lengths, said slender holes connecting an intermediate hole formed in the housing and in which said injection screw is inserted with said nozzle; (b) a portion hav 'ng a transerse hole located in the intermediate part of these slender holes and formed in said housing at right angles to these slender holes; (c) a sleeve fitted in said transerse hole and having a first and a second communcation holes formed therein at positions corresponding to said first and second slender holes; (d) a first and a second proportional action solenoids mounted on both ends of said sleeve, and (e) a first and a second spools fitted in: said sleeve in opposed relationship at respective leading ends thereof, said spools having a small diameter recessed portion formed in their respective intermediate parts thereof and being connected at their base ends with said first and second proportional action solenoids, respectively.

Claim 4

The injection molding machine as set forth in Claim 1, characterized in that said flow rate control device comprises the following component parts; that is to say, (a) a portion having a slender hole formed in the leading end of said housing so as to connect an intermediate hole formed in the housing and in which said injection screw is inserted with said injection nozzle; (b) a nozzle valve located in the intermediate part of said slender hole and mounted rotatably in the housing; (d) an actuator for rotatively driving said nozzle valve so as to control the area of opening of said slender hole to increase and decrease it; and (d) means for connecting the actuator with said nozzle valve.

Claim 5

The injection molding machine as set forth in Claim 3, characterized in that said actuator is a hydraulic oil or pneumatic piston·cylinder unit.

Claim 6

The injection molding machine as set forth in Claim 3, characterized in that said actuator is a proportional action solenoid.

Claim 7

The injection molding machine as set forth in Claim 3, characterized in that the degree of opening of said nozzle valve is controlled by an injection speed control device, said injection speed control device including an injection screw position detector connected with the piston rod of said injection piston.cylinder unit; an injection screw travel speed detector connected likewise with said piston rod; and a controller for controlling the drive of said actuator while comparing the detection signals transmitted by these two detectors, a preset injection screw position signal and a preset injection screw travel speed signal.

Claim 8

The injection molding machine as set forth in Claim 6, characterized in that said controller controls the degree of opening of said nozzle valve, and at the same time, controls the amount of the pressurized fluid to be supplied into said injection piston-cylinder unit.

Claim 9

The injection molding machine as set forth in Claim 3, characterized in that the degree of opening of said nozzle valve is controlled by an injection speed control device, said injection speed control device including an injection screw position detector connected with the piston rod of said injection piston-cylinder unit; a detector for detecting the degree of opening of nozzle valve connected with a movable unit of said actuator; means for setting nozzle valve change-over position; means for commanding change-over of the degree of opening of nozzle valve adapted to transmit a command signal to said actuator; means for setting the degree of opening of nozzle valve arranged to transmit a setting signal to said means for commanding change-over of the degree of opening of nozzle valve; means for commanding change-over of speed of injection screw; and a controller for controlling the drive of said actuator while comparing the detection signal transmitted by said injection screw position detector with the setting signal transmitted by said means for setting nozzle valve change-over position in order to actuate said means for commanding change-over of the degree of opening of nozzle valve, and at the same time, comparing the detection singal transmitted by said detector for detecting the degree of opening of nozzle valve with the setting signal transmitted by said means for setting the degree of opening of nozzle valve in order to actuate the means for commanding change-over of speed of injection screw.

Claim 10

The injection molding machine as set forth in claim 8, characterized in that said controller controls the degree of opening of said nozzle valve, and at the same time, controls the amount of the pressurized fluid to be supplied into said injection piston-cylindre unit.

Claim 11

The injection molding machine as set forth in Claim 3, characterized in that it comprises further a dwell pressure control device arranged to transmit a control signal to said flow rate control device when said injection screw is located at a predetermined position to thereby allow said nozzle valve to have a predetermined degree of opening, and when the predetermined degree of opening is obtained, effect controls to allow the pressure in the expansible pressure chamber of said injection piston-cylinder unit to reach a predetermined dwell pressure.

Claim 12

The injection molding machine as set forth in Claim 10, characterized in that said dwell pressure control device includes an injection screw position detector connected with the piston rod of said injection piston. cylinder unit; a detector for detecting the degree of opening of nozzle valve connected with a movable unit of said actuator; means for setting position of injection screw; means for setting the degree of opening of nozzle valve before dwell pressure application arranged to transmit a setting signal to said actuator; means for setting the degree of opening of nozzle valve during dwell pressure application arranged to transmit a setting signal to said actuator; means for setting dwell pressure application time; means for setting dwell pressure arranged to receive an output signal from the means for setting dwell pressure application time; and a controller for controlling the drive of said actuator while comparing the detection signal transmitted by said injection screw position detector with the setting signal transmitted by said means for setting position of injection screw in order to actuate the means for setting the degree of opening of nozzle valve before dwell pressure application, and at the same time comparing the detection signal transmitted by said detector for detecting the degree of opening of nozzle valve with said setting signal transmitted by the means for setting the degree of opening of nozzle valve before dwell pressure application in order to actuate said means for setting the degree of opening of nozzle valve during dwell pressure application and said means for setting dwell pressure application time.

Claim 13

The injection molding machine as set forth in Claim 11, characterized in that said controller controls the drive of said actuator, and at the same time, controls the amount of the pressurized fluid to be supplied into the expansible pressure chamber of said injection piston·cylinder unit.

Claim 14

The injection molding machine as set forth in Claim 11, characterized in that said controller includes further a means for setting time-lag for opening nozzle valve installed on the input side of said means for setting the degree of opening of nozzle valve during dwell pressure application, and arranged to receive an output signal transmitted by a comparator which serves to compare the detection signal transmitted by said detector for detecting the degree of opening of nozzle valve with the setting signal transmitted by said means for setting the degree of opening of nozzle valve before dwell pressure application.

Claim 15

The injection molding machine as set forth in Claim 13, characterized in that said controller controls the drive of said actuator, and at the same time, controls the amount of the pressurized fluid to be supplied into the expansible pressure chamber of said injection piston-cylinder unit.