JPH0445262B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a pressurized pouring furnace for pouring molten metal or the like using gas pressure.

Prior Art A pressurized pouring furnace, for example, as shown in FIG.
For example, a gas such as air or an inert gas is forced into the hot water storage chamber 2 at a predetermined pressure (hereinafter referred to as base pressure P), and the level of the molten metal in the hot water storage chamber 2 is lowered to lower the hot water level in the pouring chamber 5. The surface level is raised to a predetermined pouring standby level (hereinafter referred to as pre-level).

When pouring hot water into the mold 7, as shown in FIG. 3, an additional pressure (hereinafter referred to as shot pressure ΔP) is applied to the base pressure P from the pressure regulator 3 to the hot water storage chamber 2. At the same time, the level of the molten metal in the pouring chamber 5 is raised to a predetermined pouring level, and a fixed amount of molten metal is poured into the mold 7 from the pouring port 8.

By repeating the above-described operations as shown in FIG. 3, a large number of molds 7 are automatically poured.

However, in the above-mentioned conventional pressurized pouring furnace, the air pressure supplied to the hot water storage chamber 2 is determined by measuring the weight of the hot water pouring furnace 1 with a load cell or the like, and then generating a signal representing the weight of the molten metal in the hot water storage chamber 2. obtained,
The required air pressure was controlled solely by the signal of the weight of the molten metal.

However, this conventional method has problems in that there is a delay in pressurization control and that accurate pressure control is difficult due to malfunctions caused by noise and the like.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and provide a pressurized pouring furnace that can quickly respond and accurately control the required gas pressure.

Composition of the Invention The pressurized pouring furnace of the present invention includes a hot water storage chamber for storing molten metal, a pouring chamber communicating with the hot water storage chamber, and a pressurized metal pouring furnace for supplying pressurized gas to the hot water storage chamber via a pressurization system. After applying a base pressure commensurate with the amount of stored molten metal from the pressurized gas supply means to the storage chamber, a predetermined amount of molten metal is poured from the pouring port of the pouring chamber by increasing shot pressure. In a pressurized pouring furnace that pours out molten metal, a pressure detection means for detecting the pressure in the hot water storage chamber, and a valve opening degree provided in a pressurization system that supplies pressurized gas from the pressurized gas supply means to the hot water storage chamber. an adjustable pressure regulating valve; a pressure reducing regulating valve having an adjustable valve opening in a pressure reducing system that discharges the gas in the hot water storage chamber to the outside of the hot water storage chamber; and a hot water storage weight detection means for detecting the weight of hot water stored in the hot water storage chamber. and a control device that calculates the base pressure and the shot pressure according to the stored hot water weight detected by the hot water storage weight detection means and sends out a control signal as a pressure setting value in the hot water storage chamber; When the deviation between the pressure set value shown and the pressure detection value of the hot water storage chamber supplied from the pressure detection means is zero, the pressurization is performed so that pressurization and depressurization in the hot water storage chamber are in balance. A control signal is generated for the regulating valve and the pressure reducing regulating valve so that the valve opening degrees are correlated to each other, and when the deviation changes from an equilibrium state to a direction in which the pressure in the hot water storage chamber increases, the pressure regulating valve is controlled. A control signal is generated so that the valve opening degree decreases and the valve opening degree of the pressure reduction regulating valve increases, and when the deviation changes from the equilibrium state to a direction in which the pressure in the hot water storage chamber decreases, the pressure reduction regulating valve increases. and pressure regulating means for generating a control signal such that the valve opening increases and the valve opening of the pressure reduction regulating valve decreases.

In the above configuration, when the deviation between the set pressure and the detected pressure is zero, both the pressurization and pressure reduction control valves are approximately 20
% opening, and the inflow gas amount and exhaust gas amount are balanced and the furnace pressure is controlled to be constant.
Now, if the control signal increases and a (-) deviation occurs, the control signal will increase to 0.6-1.0Kg/ ^cm2 . As a result, the pressure control valve opens 20 to 100%, increasing the amount of gas flowing into the furnace and pressurizing it. At the same time, the pressure reducing control valve becomes 20% to 0% open to reduce (stop) the amount of gas discharged from the furnace. In the case of a (+) deviation, perform the opposite operation in the same manner. This control speeds up the gas supply response speed,
Further, even if an error occurs in the signal of the load cell due to noise, accurate control can be performed.

Embodiment In FIG. 1, a pressure detector 10 is provided to detect the indoor pressure of a hot water storage chamber 2 of a pouring furnace 1, and a signal using air pressure indicating the pressure inside the furnace detected by the pressure detector 10 is as follows. The pressure is applied to a pneumatic pressure regulator 11 installed at the pouring furnace installation site.

On the other hand, the weight of the pouring furnace 1 is detected by the load cell 12, and the signal is applied to the control device 20. Within this control device 20, it is converted into a digital signal by the A/D converter 21, and the signal is applied to the CPU 22. .
The CPU 22 calculates the weight of the remaining hot water stored in the hot water storage chamber 2 from this weight signal, and calculates the pre-level P and shot pressure ΔP corresponding to the remaining hot water storage amount.
During non-pouring, this pre-level P is the D/A converter 2.
3 into an analog signal, and further converted into an air pressure signal by an electro-pneumatic converter 12, and this air pressure signal is applied to the pressure regulator 11 as a set pressure signal.

The pressure regulator 11 operates a pressure control valve 13 and a pressure reduction control valve 14 based on the difference between the detected pressure signal from the pressure detector 10 and the set pressure signal from the electro-pneumatic converter 12.
outputs a control signal having a pressure corresponding to the degree of opening.

The pressure regulating valve 13 controls the opening degree of the regulating valve 16 in the pressurizing system that sends pressurizing gas to the hot water storage chamber 2, and a control signal of 0.2 to 1.0 kg/cm ² is sent to the split range using a positioner. and 0.5 to 1.0
Kg/cm ² /0 to 100% valve opening operation.

The pressure reduction control valve 14 controls the opening degree of the control valve 17 in the pressure reduction system between the hot water storage chamber 2 and the atmosphere, and the control signal is split in the range from 0.2 to 0.7Kg/cm ² /100 using a positioner. Operate with 0% valve opening.

As shown in Fig. 4, the control method of the controller 11 is such that when the deviation between the detected pressure and the set pressure signal is zero, both the pressure control valve 13 and the pressure reduction control valve 14 are opened approximately 20%, and the hot water storage chamber 2 The amount of gas flowing into the hot water storage chamber 2 and the amount of air discharged from the hot water storage chamber 2 are balanced, and the pressure inside the pouring furnace is controlled to be constant. If the set pressure signal increases and a (-) deviation occurs, the control signal will increase from 0.6 to 1.0 Kg/cm ² and the pressure control valve 13 will change from 20% opening to 100% opening. Then, the amount of gas flowing into the hot water storage chamber 2 is increased to increase the pressurizing force.
At the same time, the pressure reducing control valve 14 changes from 20% opening to 0% opening to reduce or stop the amount of gas discharged from the furnace.

In the case of a (+) deviation, the operation opposite to the above is performed.

In the above-described configuration, each of the control valves 13 and 14 determines the rate of increase in pressure within the furnace relative to the amount of gas inflow based on the internal volume of the furnace, and based on this, a control valve with an appropriate Cv value (flow characteristic value) is selected. Adjust and set the supply gas pressure within the range of 1 to 6 kg/cm ² depending on the situation. And P (proportional band) I (integral band) D (differential band) of the controller
By appropriately adjusting each setting value of the function, responsiveness and followability can be improved.

Further, in the above configuration, when shot pressure is applied, the responsiveness and followability of the pressure increase curve are improved as shown in FIG.

Furnace pressure ∝ inflow air amount ... Also, inflow gas amount = constant x supply gas pressure x time x piping cross-sectional area ... Therefore, if time and piping cross-sectional area are the same, the furnace pressure will increase from the formula. The effect is directly proportional to the supply gas pressure.

In other words, it can be said that the higher the supplied gas pressure within the control range, the higher the pressure increase effect, and the better the responsiveness and followability.

In the conventional method, in order to improve responsiveness, the only option was to increase the cross-sectional area of the piping, but in this invention, in addition to controlling the pressure by the weight of the molten metal,
Since the pressure control valve and the pressure reduction control valve are controlled by detecting the pressure in the hot water storage chamber 2, it is possible to control the supply gas pressure and the cross-sectional area of the piping, which facilitates quick response. You can improve.

In this embodiment, an emergency shutoff valve 18 is provided between the control valve 16 and the hot water storage chamber 2, and in an emergency, the emergency shutoff valve 18 is closed by a signal from the control device 30 to stop hot water storage. The gas supply to chamber 2 is cut off.

On the other hand, an emergency discharge valve 19 is provided in parallel with the control valve 17, and in an emergency, this emergency discharge valve 19 is closed by a signal from the control device 30.
The gas in the hot water storage chamber 2 is discharged.

In addition, the emergency signal from the control device 30 is
It is also applied to the CPU 22.

The emergency stop signal from the control device 30 is sent to the CPU 22.
By entering, the control output is made zero. When the control signal becomes zero, the external setting value of the pressure regulator 11 becomes zero, the pressurization regulating valve 13 is fully closed, and the pressure reducing regulating valve 1 is closed completely.
Outputs a control signal of 0.2Kg/cm ² with 4 fully open.

The positioner output signals of the pressure control valve 13 and the pressure reduction control valve 14 are cut by a signal cut-off solenoid valve,
Forcibly closes the pressure control valve 13 fully and reduces the pressure control valve 14.
fully open. The emergency shutoff valve 18 provided in the pressurized gas piping line is fully closed by an emergency stop signal from the control panel, and the inflow gas circuit is cut off. The large-diameter emergency discharge solenoid valve 19 on the exhaust line is fully opened in response to an emergency stop signal from the control panel, and the pressure inside the furnace is rapidly reduced.

Effects of the Invention As described above, according to the present invention, in a pressurized pouring furnace, a pressure control valve and a pressure reduction control valve are provided to adjust the pressure according to the difference between the detected gas pressure and the set gas pressure in the furnace. Since the pressurizing force of the pouring furnace is controlled by controlling the pressure regulating valve and the pressure reducing regulating valve, it is possible to control the pressure in the hot water storage chamber faster and more accurately than with conventional devices. Pressure control becomes possible.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an embodiment of the present invention, Figs. 2 and 3 are sectional views showing the operating principle of a pressurized pouring furnace, and Figs. 4 and 5 are diagrams of the apparatus shown in Fig. 1. This is a characteristic curve showing the operation. 1... Pressurized pouring furnace, 2... Hot water storage room, 10...
Pressure detector, 11...pressure regulator, 13...pressure control valve, 14...pressure reduction control valve.

Claims (1)

[Scope of Claims] 1. A hot water storage chamber 2 for storing molten metal, a pouring chamber 5 communicating with the hot water storage chamber, and pressurized gas supply means for supplying pressurized gas to the hot water storage chamber via a pressurization system. After applying a base pressure corresponding to the amount of molten metal stored in the molten metal from the pressurized gas supply means to the molten metal storage chamber, a predetermined amount of molten metal is poured from the pouring port 8 of the molten metal pouring chamber by increasing shot pressure. Pressure detection means 1 for detecting the pressure inside the hot water storage chamber in the pressurized pouring furnace
0, pressurization adjustment valves 13 and 16 that are provided in a pressurization system that supplies pressurized gas from the pressurized gas supply means to the hot water storage chamber, and whose opening degree can be adjusted; Pressure reduction regulating valve 1 with adjustable valve opening included in the pressure reduction system that releases to
4, 17; stored hot water weight detection means 12 for detecting the weight of hot water stored in the hot water storage chamber; when the deviation between the pressure setting value indicated by the control signal and the pressure detection value of the hot water storage chamber supplied from the pressure detection means is zero; , so that the pressurization and depressurization in the hot water storage chamber are balanced, a control signal is generated for the pressurization adjustment valve and the pressure reduction adjustment valve so that the valve opening degrees are correlated, and the deviation is in an equilibrium state. When the pressure in the hot water storage chamber changes in the direction of increasing from pressure regulating means 11 that generates a control signal so that when the pressure in the hot water storage chamber changes in a direction in which the pressure in the hot water storage chamber decreases, the opening degree of the pressure regulating valve increases and the opening degree of the pressure reducing regulating valve decreases; A pressurized hot water storage furnace characterized by being equipped with.