A control device for an injection molding machine including a cylinder into which a resin is supplied, and a screw that moves forward and rearward and rotates inside the cylinder, includes a suck back control unit that sucks back the screw based on a predetermined suck back speed and a suck back distance or a suck back time period, a pressure acquisition unit that acquires a pressure of the resin, a calculation unit which calculates a compensation amount of the suck back speed, based on a difference between the pressure of the resin at a time when sucking back is completed and a predetermined target pressure, and a speed determination unit that newly determines the suck back speed based on the compensation amount.

An injection molding machine includes: a first driving device rotating a screw provided inside a heating cylinder; a second driving device moving the screw forward and backward; a metering control section configured to, by controlling the first driving device and the second driving device, to meter resin while melting the resin, and thereafter rotate the screw in reverse to thereby reduce the pressure of the resin; a first sensor unit for detecting the pressure; a second sensor unit for detecting one or more kinds of physical quantities that affect the change of the pressure; and a prediction section predicting decompressing rotation information based on the pressure detected by the first sensor unit and the one or more kinds of physical quantities detected by the second sensor unit. The metering control section controls the first driving device based on the decompressing rotation information predicted by the prediction section.

A control device for an injection molding machine including a cylinder into which a resin is supplied and a screw that moves forward and rearward and rotates inside the cylinder, includes a metering control unit that performs metering of the resin inside the cylinder by controlling forward rotation and rearward movement of the screw until the screw has been moved rearward to a predetermined metering position, based on predetermined metering conditions, a rearward movement speed acquisition unit acquiring a rearward movement speed of the screw, a speed determination unit that determines a suck back speed for causing a resin pressure to reach a target pressure, based on the rearward movement speed acquired during metering by the rearward movement speed acquisition unit, and a suck back control unit causing the screw to move further rearward based on the suck back speed, after the screw has reached the predetermined metering position.

A control device for an injection molding machine is equipped with a pressure acquisition unit that acquires a pressure of a resin, a reverse rotation control unit that causes a screw to be rotated in reverse, after the screw has reached a predetermined metering position, a measurement unit that measures an elapsed time or a rotation amount of the screw from when the screw has reached the predetermined metering position, and a rearward movement control unit that initiates sucking back of the screw in an overlapping manner with the reverse rotation of the screw, in the case that a predetermined rearward movement initiation time has elapsed, or in the case that the screw has been rotated by a predetermined rearward movement initiation rotation amount, from when the screw has reached the predetermined metering position.

A control device for an injection molding machine is equipped with a pressure acquisition unit that acquires a pressure of a resin inside a cylinder, a reverse rotation control unit that causes a screw to be rotated in reverse based on a predetermined reverse rotation condition so as to reduce the resin pressure after having moved the screw rearward to a metering position, a compensation amount calculation unit that calculates a compensation amount to be made with respect to the reverse rotation condition, based on the resin pressure inside the cylinder acquired by the pressure acquisition unit when the reverse rotation of the screw is stopped, and a predetermined compensation function, and a compensation processing unit configured to compensate the reverse rotation condition based on the compensation amount calculated by the compensation amount calculation unit.

An injection molding apparatus and method of fabricating a molded part are provided. The apparatus may include a barrel, a nozzle enclosing an end of the barrel and defining an opening in fluid communication with an inside of the barrel, and an extrusion screw positioned at least partially inside the barrel and rotatable relative to the barrel. The extrusion screw may include a screw tip. Relative axial movement between the barrel and the extrusion screw may open or close the opening of the nozzle to permit or prevent, respectively, material flow through the opening of the nozzle. The method may include clamping a mold, opening a nozzle, rotating the extrusion screw to pump a molten material into the mold until the mold is filled, closing the nozzle, and unclamping the mold to release a molded part.

A control device for an injection molding machine including a cylinder into which a resin is supplied, and a screw that moves forward and rearward and rotates inside the cylinder, includes a suck back control unit that sucks back the screw based on a predetermined suck back speed and a suck back distance or a suck back time period, a pressure acquisition unit that acquires a pressure of the resin, a calculation unit which calculates a compensation amount of the suck back speed, based on a difference between the pressure of the resin at a time when sucking back is completed and a predetermined target pressure, and a speed determination unit that newly determines the suck back speed based on the compensation amount.

A method for controlling an injection cycle of an injection molding machine incudes advancing an injection screw axially forward toward an injection nozzle from a shot-size position to an injection position to inject melt from a shot chamber into a hot runner of a mold and from the hot runner to fill cavities of the mold. Then the injection screw is retracted away from the nozzle, from the injection position to a decompression position axially rearward of the shot-size position, to relieve melt pressure in the hot runner. Then the screw is advanced toward the nozzle from the decompression position to an intermediate position axially intermediate the injection position and the shot-size position. The method then includes rotating the screw to re-fill the shot chamber with melt and urge the screw to retract from the intermediate position to the shot-size position.

A control device for an injection molding machine includes a pressure acquisition unit that acquires a resin pressure, a measurement unit that measures an elapsed time period or a rotation amount of the screw from when the screw has reached a predetermined metering position, a reverse rotation control unit that causes the screw to be rotated in reverse from when the screw has reached the predetermined metering position, and a condition determination unit that determines the reverse rotation time period based on a required time period from when the screw has reached the predetermined metering position until when the resin pressure falls to a target pressure, or determines the reverse rotation amount based on a required reverse rotation amount from when the screw has reached the predetermined metering position until when the resin pressure falls to the target pressure.

A control device for an injection molding machine is equipped with a pressure acquisition unit configured to acquire a resin pressure, a pressure reduction control unit configured to, after the screw has reached a predetermined metering position, reduce the resin pressure to a target pressure by performing at least one of reverse rotation and sucking back of the screw, and a standby pressure control unit configured to, after the resin pressure has reached the target pressure, keep the resin pressure within a predetermined range by causing the screw to be rotated in a state in which a position of the screw in an axial direction of the cylinder is maintained.