Injection molding machine for foam molding and method for controlling injection molding machine

1 . An injection molding machine comprising:

a heating cylinder having a gas inlet;

a screw drivable in the heating cylinder;

a gas supply configured to supply a gas to the gas inlet;

an injection material pressure detector provided in a vicinity of the gas inlet of the heating cylinder; and

a controller,

wherein an inside of the heating cylinder is divided into a plurality of sections according to a shape of the screw, and includes, from upstream to downstream, a first compression and metering section in which an injection material is melted and compressed, a starvation section in which a pressure of the molten injection material decreases, and a second compression and metering section, and wherein the injection material pressure detector are provided in the starvation section,

wherein the gas supply includes:

a gas supply source configured to supply a gas; and

a pressure adjustment regulator configured to reduce and adjust a primary pressure of a gas from the gas supply source to a secondary pressure,

wherein the gas supply is configured to supply the gas at the secondary pressure to the gas inlet, and

wherein the controller is configured to detect an abnormality based on whether an injection material pressure detected by the injection material pressure detector is within a normal pressure range, the normal pressure range greater than a value that is obtained by subtracting a second threshold from the secondary pressure and being less than a value that is obtained by adding a first threshold to the secondary pressure, the first threshold being larger than 0.1 MPa, and the second threshold being larger than 0.1 MPa.

2 . The injection molding machine according to claim 1 , wherein in a case where the injection material pressure is greater than the normal pressure range and the injection material pressure is less than a value that is obtained by adding a third threshold to the secondary pressure, the third threshold being larger than the first threshold, the controller issues an alarm indicating a risk of a vent-up at the gas inlet.

3 . The injection molding machine according to claim 1 ,

wherein a feeder configured to adjust a supply amount of an injection material is attached to the heating cylinder, and

wherein in a case where the injection material pressure is greater than the normal pressure range and the injection material pressure is less than a value that is obtained by adding a third threshold to the secondary pressure, the controller performs supply amount reduction control including reducing a supply amount of an injection material by controlling the feeder.

4 . The injection molding machine according to claim 3 , wherein in a case where the injection material pressure continuously exceeds the normal pressure range during a first stabilization time from a start of the supply amount reduction control, the controller executes molding cycle stop processing.

5 . The injection molding machine according to claim 1 , wherein in a case where the injection material pressure is equal to or greater than a value that is obtained by adding a third threshold to the secondary pressure, the controller executes molding cycle stop processing.

6 . The injection molding machine according to claim 1 , wherein in a case where the injection material pressure is less than the normal pressure range and the injection material pressure is greater than a value that is obtained by subtracting a fourth threshold from the secondary pressure, the fourth threshold being larger than the second threshold, the controller issues an alarm indicating a risk of a gas leakage or a decrease in a pressure of a supply gas at the gas inlet.

7 . The injection molding machine according to claim 1 ,

wherein a feeder configured to adjust a supply amount of an injection material is attached to the heating cylinder, and

wherein in a case where the injection material pressure is less than the normal pressure range and the injection material pressure is greater than a value that is obtained by subtracting a fourth threshold from the secondary pressure, the fourth threshold being larger than the second threshold, the controller performs supply amount increase control including increasing a supply amount of an injection material by controlling the feeder.

8 . The injection molding machine according to claim 7 , wherein in a case where the injection material pressure continuously temporarily falls below the normal pressure range during a second stabilization time that is a predetermined time from a start of the supply amount increase control, the controller executes molding cycle stop processing.

9 . The injection molding machine according to claim 1 , wherein in a case where the injection material pressure is equal to or less than a value that is obtained by subtracting a fourth threshold from the secondary pressure, the fourth threshold being larger than the second threshold, the controller executes molding cycle stop processing.

10 . The injection molding machine according to claim 1 , wherein the secondary pressure to be compared with the injection material pressure is a secondary pressure set value set in the controller.

11 . The injection molding machine according to claim 1 ,

wherein the gas supply includes a secondary pressure detector configured to detect the secondary pressure, and

wherein the secondary pressure to be compared with the injection material pressure is a secondary pressure measurement value detected by the secondary pressure detector.

12 . The injection molding machine according to claim 1 ,

wherein the gas supply includes a primary pressure detector configured to detect a primary pressure of a gas from the gas supply source, and

wherein the controller is configured to:

detect a pressure decrease of the gas supply source by comparing a difference between the primary pressure and the secondary pressure; and

based on detecting the pressure decrease of the gas supply source, issue an alarm for prompting replacement of the gas supply source.

13 . The injection molding machine according to claim 1 ,

wherein the controller is further configured to:

detect an abnormality of the injection material pressure based on relationship between a normal pressure range and a predetermined condition, the normal pressure range being a normal pressure range of the injection material pressure; and

based on detecting the abnormality of the injection material pressure, perform supply amount reduction control including reducing a supply amount of an injection material by controlling a feeder,

wherein the gas supply includes an on-off valve, and

wherein a molding cycle stop processing is processing of closing the on-off valve, waiting for completion of a molding cycle being executed, and stopping the molding cycle.

14 . The injection molding machine according to claim 1 ,

wherein the controller is further configured to detect the abnormality in a case where the detected injection material pressure falls outside the normal pressure range, including when the detected injection material pressure is less than or equal to the value that is obtained by subtracting the second threshold from the secondary pressure, or when the detected injection material pressure is greater than or equal to the value that is obtained by adding the first threshold to the secondary pressure.

15 . An injection molding machine comprising:

a heating cylinder having a gas inlet;

a screw drivable in the heating cylinder;

a gas supply configured to supply a gas to the gas inlet;

an injection material pressure detector provided in a vicinity of the gas inlet of the heating cylinder; and

a controller,

wherein the gas supply includes:

a gas supply source configured to supply a gas; and

a pressure adjustment regulator configured to adjust a primary pressure of a gas from the gas supply source to a secondary pressure,

wherein the gas supply is configured to supply the gas at the secondary pressure to the gas inlet, and

wherein the controller is configured to detect an abnormality by comparing an injection material pressure detected by the injection material pressure detector with the secondary pressure,

wherein the injection molding machine further comprises an injection material detector configured to confirm a supply of an injection material to the heating cylinder, and

wherein in a case where the injection material is interrupted and an injection material shortage is detected, the controller executes molding cycle stop processing.

16 . The injection molding machine according to claim 15 , wherein the molding cycle stop processing is processing of waiting for completion of a molding cycle being executed and stopping the molding cycle.

17 . The injection molding machine according to claim 15 ,

wherein the gas supply includes an on-off valve, and

wherein the molding cycle stop processing is processing of closing the on-off valve, waiting for completion of a molding cycle being executed, and stopping the molding cycle.

18 . An injection molding machine comprising:

a heating cylinder having a gas inlet;

a screw drivable in the heating cylinder;

a gas supply configured to supply a gas to the gas inlet;

an injection material pressure detector provided in a vicinity of the gas inlet of the heating cylinder; and

a controller,

wherein the gas supply includes:

a gas supply source configured to supply a gas; and

a pressure adjustment regulator configured to adjust a primary pressure of a gas from the gas supply source to a secondary pressure,

wherein the gas supply is configured to supply the gas at the secondary pressure to the gas inlet, and

wherein the controller is configured to:

detect an abnormality by comparing an injection material pressure detected by the injection material pressure detector with the secondary pressure;

detect an abnormality of the injection material pressure based on relationship between a normal pressure range and a predetermined condition, the normal pressure range being a normal pressure range of the injection material pressure; and

based on detecting the abnormality of the injection material pressure, perform supply amount reduction control including reducing a supply amount of an injection material by controlling a feeder, and

wherein a molding cycle stop processing is processing of waiting for completion of a molding cycle being executed and stopping the molding cycle.