SU1719155A1 - Method for batching of molten metal - Google Patents

Abstract

The invention relates to foundry, namely, the dispensing of liquid metal by magnetodynamic dispensers. The aim of the invention is to improve the accuracy of dosing. The method involves supplying the metal to the metal pipe under the action of electromagnetic pressure, periodically pouring it through the drain hole under the action of overpressure, and reducing the electromagnetic pressure in the period between pouring until the metal reaches a constant level in the metal pipe. The excess pressure is measured at the level of the drain hole from the moment it reaches its metal, the integral value of this pressure is compared with the preset excess pressure value corresponding to the required dose value, and at the time of matching the compared values, the electromagnetic pressure is reduced by a constant value. 3 il.

Description

The invention relates to foundry, namely, the dispensing of liquid metal by magnetodynamic dispensers.

The aim of the invention is to improve the accuracy of dosing.

FIG. 1 shows a device implementing the method; FIG. 2 illustrates the main parameters of the process; on fig.Z the same. .

In the drawings, the following conventions are taken:

Ro is the initial pressure in the dosing unit before the first dosing cycle;

A PI is the value of the overpressure determining the level of the alloy above the drain hole (flow rate) at the rated voltage of the supply network;

A 2 - the same, while reducing the supply voltage;

ti1ti2ti3 is the time of switching on the first, second, third (conditionally) dosing cycles;

t21, t2, t3 is the time point for the metal to reach the drain hole for the three conditionally selected dosing cycles;

t3, t3.t3 is the time instant of coincidence of the measured integral value of overpressure with a predetermined integral value of overpressure for the selected three dosing cycles;

q -13 - time interval of pressure reduction, constant for all dosing cycles;

S

h

from ate

Si, S2, S3 are the measured integral overpressure values;

Q is the experimentally obtained dependence of the flow rate on the level h of the metal above the drain hole.

The device contains a magnetodynamic pump MDN-6A, consisting of a tank 1, communicating with the W-shaped channel 2, an electromagnet 3, in the gap between the poles of which there is a zone of intersection of the horizontal and central vertical sections of the channel 2, inductors 4, covering the lateral vertical sections channel and drain metal pipe 5 installed above the mouth of the central vertical section of the channel. At the outlet of the metal conduit 5, a pressure measurement sensor 6 is arranged, which is a hollow, hermetically metallic or ceramic tube. The lower slice of the sensor (tube) 6 is installed at the level of the drain hole of the metal conduit 5. And the other is connected by a sealed line 7 to the pressure transducer 8. The electrical output of the converter 8 is connected to an integrator 9, the output of which is connected to the input of the comparator unit 10, at the second input of which a voltage level characterizing the integral value of overpressure for discharge of the required dose is set using the setting device 11. The second input of the integrator 9 is affected by one of the outputs of the control unit 12, which zeroes and prepares for integrating the signal of the converter 8. This output of the block 12 performs shunting and shunting by the command Start of the charge capacity of the integrator 9.

An analogue type I-205 comparator of the Logika-I series is used as block 10. The output of block 1 is applied at the time of coincidence of the measured and specified integral values of overpressure to control unit 12. In accordance with the received signal, the unit 12 acts on the transducer 13 of the voltage of the electromagnet, reducing the voltage of its power supply by a constant value. In this case, the discharge of metal ceases. The alloy is lowered in the metal conduit to a constant level relative to the drain hole. The control unit 12 generates a signal that ensures the reset of the integrator 9 to zero (bypassing the integrator's capacitance). Potentiometer pilot 14 is designed to set the required value of the initial pressure in MDN before the first dosing cycle.

PRI me R. An aluminum alloy of type AL-9 with a temperature of 680 ° C is poured into the crucible of the metering device and the channel connected with it. The inductors are connected to the voltage 56B, which ensures the release of the required power in the channel metal and the crucible to maintain the desired temperature and the current density required to provide the required electromagnetic pressure.

At the mouth of the central section of the channel, a drain metal pipe is installed, in the upper part of which a sealed (metallic or ceramic) tube with an inner diameter of 6-8 mm is connected, connected by a pressure-tight line with a pressure transducer.

A metering electromagnet controlled by a thyristor voltage converter is supplied with a voltage of 25 V (maximum voltage of an electromagnet of 220 V), which provides the required value of Ro before the first dosing cycle. At these voltages, the supply of inducers from the electromagnet Ro ensures mixing of the alloy without breaking the oxide film of the metal mirror in the crucible and maintaining the level of the metal in the drain metal conductor 30 mm lower than the level of the metal in the crucible, which prevents the metal from freezing on the walls of the metal conductor.

At time ti1, a command is received to start the dosing cycle. In this case, the voltage on the electromagnet is increased at a speed of 30 V / s. Electromagnetic pressure increases the metal level in the metal pipe. At the time point, the metal reaches the drain hole, which corresponds to a voltage of 70 V at the maximum level of the metal in the crucible of the metering device. At t21, the control system of the thyristor converter of the electromagnet increases (smoothly or abruptly) the voltage of the electromagnet, providing the given D Pi value of which conditions for obtaining the required flow rate at the dose discharge.

For discharge, for example, within 3 seconds a dose of 2 kg according to the calibration dependence of FIG. 3 for a flow rate of about 700 g / s, it is determined that the level of the metal above the drain hole should be between 31-32 mm, which corresponds to an increase in voltage electromagnet of 15.5–16 V. Thus, the maximum voltage of the electromagnet for the first dosing cycle is 86 V. At time t2, the metal, blocking the opening of the pressure sensor, seals the line connecting the sensor and the pressure transducer.

As a result, the change in air pressure in the hermetic line corresponds to the amount of overpressure above the drain hole. Air pressure oscillations occur in the pipeline volume, continuously recorded and changed by the pressure transducer. The magnitude of each such oscillation corresponds to the oscillation acting on the metal overpressure above the level of the drain hole during the dose draining process. An electrical signal on the magnitude of the overpressure enters the integrator and after it in the comparison unit, where the signal characterizing the integral value of the overpressure is compared to drain the required dose in the form of a voltage level signal. The preset voltage level of the comparator unit is set based on the magnitude of the output signal of the pressure transducer (usually up to 5 mA) and the integrator circuit parameters.

When the coincidence (time point ta) of the measured and specified integral values of overpressures, which indicates that the volume of metal melted in a given cycle corresponds with the required dose volume, a signal about the end of the dosing cycle is generated in the comparator unit. In accordance with this signal, the supply voltage to the electromagnet is reduced during a period of time (14-13).

The duration of the voltage reduction phase of the electromagnet is constant for all dosing cycles, which ensures that the metal in the metal conduit is lowered to a constant level located 60–70 mm below the drain hole. It should be noted that possible deviations of the metal level in the drain metal pipeline within 10 mm lead to an insignificant change in the duration (tenths of a second) of the metal lifting to the drain hole and the dosing process is not affected. Subsequent dosing cycles (see Fig. 2) are performed as described above.

It should be noted that when pouring each dose of metal, the integral value of the overpressure characterizing the dose value is constant (). This ensures that the received dose corresponds to the required volume, which significantly improves the accuracy of dosing.

Continuous measurement of the overpressure value makes it possible to correct the effective value of the integral value of this pressure with an arbitrary change in the hydraulic resistance of the metallo tract of the dispenser, fluctuations in supply voltage, etc. and thereby eliminate the negative impact of the above factors on the dosing process.

The technical advantage of the method is its simplicity, the absence of complicated and expensive controls, the possibility of realization in an automatic mode.

The application of the method allows to increase the accuracy of dosing by 1.5-2 times, which will provide an increase in the yield of suitable by 1-1.5%.

Claims (1)

Invention Formula A method of dosing a liquid metal, which includes feeding the metal into the metal pipe under the action of electromagnetic pressure, periodically pouring it through the drain hole under the action of overpressure, and reducing the electromagnetic pressure during the period between pouring until the metal reaches a constant level in the metal pipe, increase the accuracy of dosing, additionally measure the amount of overpressure in the metal pipeline at the level of the drain hole from the moment it reaches the metal, comparing T is the integral value of this pressure with a predetermined by the technology integral value of overpressure.-corresponding to the required dose value, and at the moment of coincidence of the compared values, the electromagnetic pressure is reduced by a constant value.