CN-116568476-B - Injection molding machine for foam molding and control method for injection molding machine

Abstract

An injection molding machine (1) is provided with a heating cylinder (17) provided with a gas injection port (26), a screw (18), a gas cylinder (30), a pressure reducing valve for reducing the primary pressure of gas from the gas cylinder (30) to a secondary pressure, a gas supply unit (43) for supplying gas of the secondary pressure to the gas injection port (26), a secondary pressure detection mechanism for detecting the secondary pressure, and a control mechanism. The control means compares a preset pressure in the injection molding machine (1) with the secondary pressure to detect an abnormality.

Inventors

• NAITOU Akihiro
• Oilcloth Tuoye

Assignees

• 株式会社日本制钢所

Dates

Publication Date

20260508

Application Date

20211117

Priority Date

20201210

Claims (20)

1. 1. An injection molding machine, comprising: a heating cylinder provided with a gas injection port; A screw configured to be drivable within the heating cylinder; A gas supply device for supplying gas to the gas injection port, and The control mechanism is used for controlling the control mechanism, The heating cylinder is divided into a plurality of sections based on a change in the shape of the screw flight, and includes at least a 1 st compression/metering section in which molten injection material is compressed, a starvation section in which the pressure of the injection material is reduced, a 2 nd compression/metering section in which the injection material is compressed again, from an upstream side toward a downstream side, the gas injection port being provided in the starvation section, The gas supply device includes: a gas supply source for supplying a gas; A pressure adjustment mechanism that adjusts a primary pressure of the gas from the gas supply source to a secondary pressure; a check valve disposed downstream of the pressure regulating mechanism, and A secondary pressure detecting mechanism that detects the secondary pressure downstream of the check valve, The gas injection port is connected downstream of the check valve, the gas of the secondary pressure is supplied to the gas injection port, The control means includes a set pressure of the gas at the secondary pressure, a1 st threshold value which is a value of 0.1MPa to 1.5MPa, and a2 nd threshold value which is a value of 0.1MPa to 1.5MPa, And a normal pressure range, which is a normal pressure range of the secondary pressure, is larger than a value obtained by subtracting the 2 nd threshold from the set pressure and is smaller than a value obtained by adding the 1 st threshold to the set pressure, and is determined to be abnormal when the secondary pressure is out of the normal pressure range.
2. 2. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The control mechanism is provided with a 3 rd threshold value which is larger than the 1 st threshold value, and when the secondary pressure is larger than the normal pressure range and the secondary pressure is lower than a value obtained by adding the 3 rd threshold value to the set pressure, the control mechanism sends out a dangerous alarm of material discharge at the gas injection port.
3. 3. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The control means has a 3 rd threshold value larger than the 1 st threshold value, and stops the molding cycle after completion of the molding cycle in execution when the secondary pressure is equal to or higher than a value obtained by adding the 3 rd threshold value to the set pressure.
4. 4. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The gas supply device is provided with an opening/closing mechanism at a gas pipe or a gas injection part for supplying the gas of the secondary pressure to the gas injection port, The control means has a 3 rd threshold value larger than the 1 st threshold value, and when the secondary pressure is equal to or higher than a value obtained by adding the 3 rd threshold value to the set pressure, the control means closes the opening/closing means and stops the molding cycle after completion of the molding cycle in execution.
5. 5. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The control means includes pressure control means for controlling the pressure adjustment means, and a3 rd threshold value larger than the 1 st threshold value, and when the secondary pressure is larger than the normal pressure range and the secondary pressure is lower than a value obtained by adding the 3 rd threshold value to the set pressure, the pressure control means performs pressure reduction control so that the secondary pressure becomes the normal pressure range.
6. 6. The injection molding machine of claim 5, wherein the injection molding machine further comprises a plurality of injection molding machines, During the 1 st settling time from the start of the pressure reduction control, in the case where the secondary pressure continues to be higher than the normal pressure range, the control mechanism stops the molding cycle after the completion of the molding cycle in execution.
7. 7. The injection molding machine of claim 5, wherein the injection molding machine further comprises a plurality of injection molding machines, The gas supply device is provided with an opening/closing mechanism at a gas pipe or a gas injection part for supplying the gas of the secondary pressure to the gas injection port, During the 1 st settling time from the start of the pressure reduction control, in the case where the secondary pressure continues to be higher than the normal pressure range, the control mechanism closes the opening and closing mechanism and stops the molding cycle after completion of the molding cycle in execution.
8. 8. The injection molding machine of claim 5, wherein the injection molding machine further comprises a plurality of injection molding machines, The heating cylinder is provided with a feeder for adjusting the feeding amount of the injection material, The control means performs supply amount reduction control of controlling the feeder to reduce the supply amount of the injection material in a case where the secondary pressure continues to be higher than the normal pressure range during the 1 st stabilization time from the start of the pressure reduction control.
9. 9. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The heating cylinder is provided with a feeder for adjusting the feeding amount of the injection material, The control means includes a 3 rd threshold value that is larger than the 1 st threshold value, and when the secondary pressure is larger than the normal pressure range and the secondary pressure is lower than a value obtained by adding the 3 rd threshold value to the set pressure, the control means performs supply amount reduction control for controlling the feeder so that the supply amount of the injection material is reduced.
10. 10. The injection molding machine of claim 8, wherein the injection molding machine further comprises a plurality of injection molding machines, During the 2 nd settling time from the start of the supply amount reduction control, in the case where the secondary pressure continues to be higher than the normal pressure range, the control mechanism stops the molding cycle after the completion of the molding cycle in execution.
11. 11. The injection molding machine of claim 9, wherein the injection molding machine further comprises a plurality of injection molding machines, During the 2 nd settling time from the start of the supply amount reduction control, in the case where the secondary pressure continues to be higher than the normal pressure range, the control mechanism stops the molding cycle after the completion of the molding cycle in execution.
12. 12. The injection molding machine of claim 8, wherein the injection molding machine further comprises a plurality of injection molding machines, The gas supply device is provided with an opening/closing mechanism at a gas pipe or a gas injection part for supplying the gas of the secondary pressure to the gas injection port, During the 2 nd stabilization time from the start of the supply amount reduction control, in the case where the secondary pressure continues to be higher than the normal pressure range, the control mechanism closes the opening and closing mechanism and stops the molding cycle after the completion of the molding cycle in execution.
13. 13. The injection molding machine of claim 9, wherein the injection molding machine further comprises a plurality of injection molding machines, The gas supply device is provided with an opening/closing mechanism at a gas pipe or a gas injection part for supplying the gas of the secondary pressure to the gas injection port, During the 2 nd stabilization time from the start of the supply amount reduction control, in the case where the secondary pressure continues to be higher than the normal pressure range, the control mechanism closes the opening and closing mechanism and stops the molding cycle after the completion of the molding cycle in execution.
14. 14. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, When the secondary pressure is smaller than the normal pressure range and the rate of decrease of the secondary pressure becomes equal to or higher than a4 th threshold, the control means stops the molding cycle after completion of the molding cycle in execution.
15. 15. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The gas supply device is provided with an opening/closing mechanism at a gas pipe or a gas injection part for supplying the gas of the secondary pressure to the gas injection port, When the secondary pressure is smaller than the normal pressure range and the rate of decrease of the secondary pressure becomes equal to or higher than a 4 th threshold, the control means closes the opening/closing means and stops the molding cycle after completion of the molding cycle in execution.
16. 16. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The heating cylinder is provided with a feeder for adjusting the feeding amount of the injection material, The control means includes a 4 th threshold value and a 5 th threshold value that is greater than the 2 nd threshold value, and when the secondary pressure is greater than a value obtained by subtracting the 5 th threshold value from the set pressure and the rate of decrease of the secondary pressure becomes equal to or greater than the 4 th threshold value, the control means performs supply amount increase control for controlling the feeder so that the supply amount of the injection material is increased.
17. 17. The injection molding machine of claim 16, wherein the injection molding machine further comprises a plurality of injection molding machines, The control means stops the molding cycle after completion of the molding cycle in execution when the rate of decrease in the secondary pressure is temporarily higher than the 4 th threshold during a predetermined cycle from the start of the supply amount increase control or during a 4 th settling time from the start of the supply amount increase control.
18. 18. The injection molding machine of claim 16, wherein the injection molding machine further comprises a plurality of injection molding machines, The gas supply device is provided with an opening/closing mechanism at a gas pipe or a gas injection part for supplying the gas of the secondary pressure to the gas injection port, The control means closes the opening/closing means and stops the molding cycle after completion of the molding cycle in execution when the rate of decrease in the secondary pressure temporarily exceeds the 4 th threshold during a predetermined cycle from the start of the supply amount increase control or during a 4 th steady time from the start of the supply amount increase control.
19. 19. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The control means has a 5 th threshold value larger than the 2 nd threshold value, and stops the molding cycle after completion of the molding cycle in execution when the secondary pressure is equal to or lower than a value obtained by subtracting the 5 th threshold value from the set pressure.
20. 20. The injection molding machine of claim 1, wherein the injection molding machine comprises a plurality of molding machines, The gas supply device is provided with an opening/closing mechanism at a gas pipe or a gas injection part for supplying the gas of the secondary pressure to the gas injection port, The control means is provided with a 5 th threshold value larger than the 2 nd threshold value, and when the secondary pressure is equal to or lower than a value obtained by subtracting the 5 th threshold value from the set pressure, the control means closes the opening/closing means and stops the molding cycle after completion of the molding cycle in execution.

Description

Injection molding machine for foam molding and control method for injection molding machine Technical Field The present invention relates to an injection molding machine for injecting an inert gas into an injection material to mold a foam molded product, and a control method of such an injection molding machine. Background An injection molding machine for obtaining a foam molded product using a physical blowing agent, that is, an inert gas, is generally constructed as follows. That is, the injection molding machine for foam molding is composed of a heating cylinder and a screw. The heating cylinder is divided into a plurality of sections corresponding to the shape of the screw, and includes a1 st compression/measurement section, a starvation section, and a2 nd compression/measurement section from upstream to downstream. The heating cylinder is provided with an injection part of inactive gas in a manner corresponding to the starvation zone. The inert gas is supplied from a gas supply source such as a gas cylinder. The primary pressure of the gas supplied from the gas supply source is reduced to a secondary pressure by the pressure reducing valve. The inert gas of the secondary pressure is connected to the injection portion. The injection material was transported and melted by a screw from upstream to downstream in a heated cylinder, and kneaded in the 1 st compression/metering zone. Next, in the starvation zone, the pressure of the injected material is reduced, and the inert gas of the secondary pressure is injected. The injection material injected with the inert gas was kneaded/compressed and measured in the 2 nd compression/measurement zone, and injected into a mold to obtain a foam molded article. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2014-200937 Disclosure of Invention Problems to be solved by the invention In an injection molding machine for foam molding, an injection material may be pushed up at an injection portion of an inert gas to clog the injection portion, and so-called chipping (bent up) may occur. The injection molding machine for foam molding described in patent document 1 is provided with a material-burst detecting mechanism in an injection portion, and mechanically detects the occurrence of material burst and pushes the injection material back into a heating cylinder. In an injection molding machine for foam molding, various problems occur in addition to the material discharge. Such as reverse flow of inactive gas, poor supply of inactive gas, and the like. The secondary pressure of the inert gas is appropriately controlled by a pressure reducing valve, and the secondary pressure is confirmed to reach a desired pressure by a pressure gauge that can be visually confirmed. In addition, the injection material is also controlled to be properly supplied. However, the above problems cannot be completely prevented, and there is a problem that even if the problems occur, the problems are not noticed and a large number of defective products are generated. Other objects and novel features will become apparent from the description and drawings of this specification. Means for solving the problems The present disclosure relates to an injection molding machine having the following configuration. Namely, the injection molding machine includes a heating cylinder provided with a gas injection port, a screw, a gas cylinder, a pressure adjusting mechanism that adjusts a primary pressure of gas from the gas cylinder to a secondary pressure, a gas injection port that supplies the gas of the secondary pressure to the heating cylinder, a secondary pressure detecting mechanism that detects the secondary pressure, and a control mechanism. The control means compares a preset pressure in the injection molding machine with the secondary pressure to detect an abnormality. Effects of the invention According to the present disclosure, the occurrence of the precursors of the occurrence of the material burst, the gas reverse flow, the gas supply failure, etc. is rapidly captured, and the occurrence of the defective products is prevented. Drawings Fig. 1 is a front view showing an injection molding machine of the present embodiment. Fig. 2 is a front cross-sectional view showing the injection device of the present embodiment. Fig. 3 is a flowchart showing a control method implemented in the injection molding machine of the present embodiment. Fig. 4 is a flowchart showing a control method implemented in the injection molding machine of the present embodiment. Fig. 5 is a flowchart showing a control method implemented in the injection molding machine of the present embodiment. Fig. 6 is a flowchart showing a control method implemented in the injection molding machine of the present embodiment. Fig. 7 is a flowchart showing a control method implemented in the injection molding machine of the present embodiment. Fig. 8 is a diagram showing a control method of the inj