JP3309128B2 - Automatic booster for low pressure casting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic pressure booster for a low-pressure casting machine for producing a casting by pressurizing a molten metal by the pressure of air supplied from an air supply path and filling the molten metal into a mold.

[0002]

2. Description of the Related Art Conventionally, as an automatic booster of a low-pressure casting machine for manufacturing a casting by pressurizing a molten metal by the pressure of air supplied from an air supply path and filling the molten metal into a mold, a structure as shown in FIG. There is something. As shown in FIG.
A throttle valve 25 is provided at a supply port of an air supply passage 24 for supplying air into a furnace 23 of a low-pressure casting machine for manufacturing a casting by pressurizing the mold 1 and filling the mold 22 with a casting.
A pressure-type electropneumatic proportional valve 26 for controlling the pressure of air is provided between the furnace and the furnace 23. This pressure type electropneumatic proportional valve 26
Is provided with a PID controller 27 for controlling the PID (proportional, integral, derivative).
A pressure sensor 28 is connected to the rack 27. The pressure sensor 28 detects the pressure in the furnace 23 and outputs a pressure detection signal to the PID controller 27.
The D controller 27 controls the furnace 23 based on the pressure detection signal.
Is calculated from the actual applied pressure in the above and the set pressure pattern of FIG. 3 output from the computer 29, and PID calculation is performed to make the deviation zero, and the pressure type electropneumatic proportional valve 26 is operated. Control.

In the case of the conventional technical means in which the pressure-type electropneumatic proportional valve 26 is PID-controlled, the flow rate of air in the air supply passage 24 is set even when the space volume of the furnace 23 is maximized by trial. The pressure is fixedly set by the throttle valve 25 so that the pressure can be secured.

[0004]

In the conventional automatic pressure booster of the conventional low pressure casting machine, the flow rate of air supplied to the furnace 23 is fixedly set by the throttle valve 25. In a certain range of the space volume, it is possible to make the furnace pressure close to the set pressure pattern as shown in FIG. 3, while in other ranges, the furnace pressure is set to the set pressure pattern due to excessive or insufficient air supply flow rate. There is a problem that it is difficult to get close.

Therefore, in the present invention, when air is supplied to the furnace 23, the pressure and flow rate of the air are controlled by PID to make the furnace pressure close to the set pressure pattern in the entire space volume of the furnace 23. Is to be solved.

[0006]

According to the present invention, there is provided a low-pressure casting machine for pressurizing a molten metal by the pressure of air supplied from an air supply path, filling the molten metal in a mold, and producing a casting. In the air supply path, a pressure type electropneumatic proportional valve for controlling the pressure of the air and a flow type electropneumatic proportional valve for controlling the flow rate of the air are provided in series, while the pressure applied to the molten metal is detected. The pressure type electropneumatic proportional valve and the flow type electropneumatic are provided so that the pressure of the molten metal coincides with a predetermined pressure pattern while inputting a pressure detection signal of the pressure sensor. Both proportional valves
Is repeatedly and alternately provided with control means for performing PID control.

[0007]

SUMMARY OF According to the automatic pressurizing device for low-pressure casting machine of the above configuration, the control means, the pressure pressing force of the molten metal is set in advance pattern - of the pressure control valve and flow control valve to match the emission
By alternately performing PID control of both, the pressure and flow rate of air are adjusted to control the furnace pressure to approach the set pressure pattern in the entire range of the space volume of the furnace of the low-pressure casting machine.

[0008]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows that a molten metal 1 is pressurized with air,
FIG. 2 is a control system diagram showing an overall configuration of an automatic pressure boosting device of a low-pressure casting machine (furnace) 3 for filling a molten metal 1 into the inside to produce a casting. As shown in FIG. 1, a pressure type electropneumatic proportional valve 5 for controlling the pressure of air supplied to the furnace 3 and an air flow rate are provided in an air supply path 4 between a pressure air supply source E and the furnace 3. A flow type electropneumatic proportional valve 6 to be controlled is provided. Further, a pressure sensor 7 for detecting the air pressure of the furnace 3 and outputting a pressure detection signal is provided.

In order to control the pressure type electropneumatic proportional valve 5 and the flow type electropneumatic proportional valve 6, a PID controller 8 for pressure is connected to the pressure type electropneumatic proportional valve 5, A flow rate PID controller 9 is connected to the proportional valve 6. Also, a pressure PID controller 8 and a flow rate PID
The pressure sensor 7 is connected to the controller 9, and the pressure type electro-pneumatic proportional valve 5 and the flow rate type electro-pneumatic proportional valve 6 are PID based on a pressure detection signal from the pressure sensor 7.
Controlled. The pressure PID controller 8
A computer 1 for outputting data according to a set pressure pattern as shown in FIG.
0 is connected.

Next, the operation of the automatic booster will be described. The pressure PID controller 8 is based on a deviation between the actual air pressure of the furnace 3 based on the pressure detection signal from the pressure sensor 7 and the data according to the set pressure pattern from the computer 10. The air pressure is adjusted by calculating and outputting a drive signal corresponding to the calculated value to the pressure-type electropneumatic proportional valve 5, so that the actual air pressure of the furnace 3 is controlled to approach the set pressure pattern. . On the other hand, the flow rate PID controller 9 is based on the deviation between the actual air pressure of the furnace 3 based on the pressure detection signal from the pressure sensor 7 and the data according to the set pressure pattern from the computer 10. PID calculation and outputs a drive signal corresponding to the calculated value to the flow type electropneumatic proportional valve 6 to adjust the air flow rate, thereby
The actual air pressure is controlled so as to approach the set pressure pattern. The PID control by the pressure PID controller 8 and the PI control by the flow rate PID controller 9 are performed.
The D control is repeated alternately.

If a pressure tank is used as the supply source E of the pressurized air and the above-described PID control is performed, in the actual machine, good pressure control can be performed only by fine adjustment. In particular, even if there is an air leak in the furnace 3 of the actual machine, the pressure and the flow rate instantaneously make up for the leak amount, and the optimal pressure control can be performed without adjusting the pressure tank.

[0012]

According to the present invention as described above, according to the present invention, the control means, pressure of molten metal preset pressure pattern - by the PID control so as to match the down, the pressure control valve and flow control valve By controlling both alternately and repeatedly , the furnace internal pressure is adjusted to the set pressure pattern in the entire range of the furnace space volume. There is an effect that it can be realized by.

[Brief description of the drawings]

FIG. 1 is a control system diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a control system diagram showing an overall configuration of a conventional automatic pressure booster for a low-pressure casting machine.

FIG. 3 is a set pressure pattern diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molten metal 2 Mold 3 Furnace 4 Air supply path 5 Pressure type electro-pneumatic proportional valve 6 Flow rate type electro-pneumatic proportional valve 7 Pressure sensor 8 PID controller for pressure 9 PID controller for flow rate 10 Computer

Claims (1)

(57) [Claims] 1. A low-pressure casting machine for manufacturing a casting by pressurizing a molten metal by the pressure of air supplied from an air supply path and filling the molten metal into a mold to control a pressure of the air in the air supply path. A type electropneumatic proportional valve and a flow type electropneumatic proportional valve for controlling the flow rate of the air are provided in series, while a pressure sensor for detecting a pressing force on the molten metal is provided, and a pressure detection signal of the pressure sensor is input. Meanwhile , both the pressure type electropneumatic proportional valve and the flow rate type electropneumatic proportional valve are operated so that the pressure of the molten metal coincides with a preset pressure pattern.
An automatic booster for a low-pressure casting machine, comprising a control means for performing PID control alternately and repeatedly .