Provided is an injection device and an injection control method which are capable of preventing a drooping phenomenon from an injection nozzle even during high cycle molding, and capable of appropriately plasticizing and molding a resin having poor thermal stability. An injection device (10) of the disclosure includes: an injection cylinder (30) which accumulates a molding material and has an injection nozzle (33) at the front; an injection plunger (31) which is moved backward in the injection cylinder (30); an injection plunger driving device (50, 150) which moves the injection plunger (31) backward; and an injection controller (60, 160). The injection controller (60, 160) retreats the injection plunger (31) by the injection plunger driving device (50, 150) to perform metering in a plastication metering step of metering the molding material supplied into the injection cylinder (30).

Provided is an injection device and an injection control method which are capable of preventing a drooping phenomenon from an injection nozzle even during high cycle molding, and capable of appropriately plasticizing and molding a resin having poor thermal stability. An injection device (10) of the disclosure includes: an injection cylinder (30) which accumulates a molding material and has an injection nozzle (33) at the front; an injection plunger (31) which is moved backward in the injection cylinder (30); an injection plunger driving device (50, 150) which moves the injection plunger (31) backward; and an injection controller (60, 160). The injection controller (60, 160) retreats the injection plunger (31) by the injection plunger driving device (50, 150) to perform metering in a plastication metering step of metering the molding material supplied into the injection cylinder (30).

Provided are an injection molding machine and an injection molding method. An injection molding machine includes: a plasticizing unit which rotates a screw to plasticize a molding material inside a plastication cylinder, and an injection unit. The injection unit has: a plunger reciprocally moving inside an injection chamber, and an injection driving device reciprocally moving the plunger. By driving the injection driving device to move the plunger backward and forward inside the injection chamber, and driving a rotary driving device to alternately rotate the screw in a normal rotation direction and a reverse rotation direction, the molding material is controlled to reciprocate between the plastication cylinder and the injection chamber.

Provided are an injection molding machine and an injection molding method. An injection molding machine includes: a plasticizing unit which rotates a screw to plasticize a molding material inside a plastication cylinder, and an injection unit. The injection unit has: a plunger reciprocally moving inside an injection chamber, and an injection driving device reciprocally moving the plunger. By driving the injection driving device to move the plunger backward and forward inside the injection chamber, and driving a rotary driving device to alternately rotate the screw in a normal rotation direction and a reverse rotation direction, the molding material is controlled to reciprocate between the plastication cylinder and the injection chamber.

An injection molding machine having vent mechanism includes a plastication device, an injection device, a junction, a vent-up sensor, and a controller. The vent-up sensor detects vent-up. When the vent-up is detected, the controller switches from normal conditions to vent-up suppression conditions. The vent-up suppression conditions have at least one of the followings: increasing a rotational speed of the plastication screw to be higher than that in the normal conditions; using retreat-metering when the retreat-metering is not performed in the normal conditions, wherein in the retreat-metering, in addition to a pressure of the resin material, a force in a retreat direction is applied to the injection plunger to move the injection plunger at a predetermined retreat speed in the metering; and increasing the retreat speed of the injection plunger to be higher than that in the normal conditions when the retreat-metering is performed in the normal conditions.

An injection molding machine having vent mechanism includes a plastication device, an injection device, a junction, a vent-up sensor, and a controller. The vent-up sensor detects vent-up. When the vent-up is detected, the controller switches from normal conditions to vent-up suppression conditions. The vent-up suppression conditions have at least one of the followings: increasing a rotational speed of the plastication screw to be higher than that in the normal conditions; using retreat-metering when the retreat-metering is not performed in the normal conditions, wherein in the retreat-metering, in addition to a pressure of the resin material, a force in a retreat direction is applied to the injection plunger to move the injection plunger at a predetermined retreat speed in the metering; and increasing the retreat speed of the injection plunger to be higher than that in the normal conditions when the retreat-metering is performed in the normal conditions.

A control method for an injection moulding system having an extruder, feeding material continuously to an accumulator, portioning material intermittently to an injection device, wherein the control method is configured to drive the extruder at a high speed or at a low speed respectively, the high speed and the low speed defining an extruder speed interval, the method comprising acquiring a value for an actual positional change for the accumulator (POS.sub.ACT), comparing the value for the actual positional change (POS.sub.ACT) with a predicted value for the positional change (POS.sub.PRED), and adjusting a speed of the extruder based on a result of the comparison.

A plasticizing device that plasticizes a solid material includes a drive motor, a screw rotated by the drive motor along a rotation axis of the drive motor and having a groove forming surface on which a groove is formed, a barrel having a facing surface facing the groove forming surface and provided with a communication hole in a central portion thereof, and a heating unit configured to heat at least one of the screw and the barrel. A first facing region and a second facing region that is closer to the central portion than the first facing region are provided between the groove forming surface and the facing surface. A second gap between the groove forming surface and the facing surface in the second facing region is larger than a first gap between the groove forming surface and the facing surface in the first facing region.

A plasticizing device that plasticizes a solid material includes a drive motor, a screw rotated by the drive motor along a rotation axis of the drive motor and having a groove forming surface on which a groove is formed, a barrel having a facing surface facing the groove forming surface and provided with a communication hole in a central portion thereof, and a heating unit configured to heat at least one of the screw and the barrel. A first facing region and a second facing region that is closer to the central portion than the first facing region are provided between the groove forming surface and the facing surface. A second gap between the groove forming surface and the facing surface in the second facing region is larger than a first gap between the groove forming surface and the facing surface in the first facing region.

A method of determining a solution state of a gas in a plastic melt used in a plastic shaping method includes: (vi) providing the plastic melt together with the gas in a chamber, (vii) alteringin particular reducinga volume of the chamber to alter a pressure of the plastic melt together with the gasin particular increased from a first pressure value to a second pressure value, (viii) introducing the plastic melt into a shaping cavity, (ix) computing at least one compression parameter characteristic of the compression behaviour of the plastic melt, in particular a modulus of compression, from the first pressure value and the second pressure value, and (x) determining from the at least one compression parameter whether the gas is substantially completely dissolved in the plastic melt and/or a solubility limit of the gas in the plastic melt is determined from the at least one compression parameter.