US3396870A - Mechanical metal pouring control system and components thereof - Google Patents

Description

Aug. 13, 1968 M. J. DIAMOND ETAL MECHANICAL METAL POURING CONTROL SYSTEM AND COMPONENTS THEREOF Filed Jan. 5, 1967 L FREQUENCY .4 PRESET 44. ii VOLTAGE TO' PULSE COUNTER FREQUENCY WITH PRESET I CONVERTER COUNT A'R CONTROLLER w W v INVERTER INTEGRATOR Z K Z /3 COMPRESSED AIR SOURCE Z a x4 2% r? L R &

4 2 j VOLTAGE TO COUNTER CONVERTER 55 AIR AIR SOURCE SOU RC E INVENTORS M17501: ffl/kmormf Roe/z fl /275g WM 444% ATTORNEY United States Patent 3 396,870 MECHANICAL METAL POURING CONTROL SYSTEM AND COMPONENTS THEREOF Milton J. Diamond, Saginaw, Mich., and Robert J. Kinsey,

Danville, Ill., assignors to General Motors Corporation,

Detroit, Mich., a corporation of Delaware Filed Jan. 3, 1967, Ser. No. 606,725 5 Claims. (Cl. 222-14) ABSTRACT OF THE DISCLOSURE Automatic metal pouring control apparatus to measure out desired amounts of metal from a ladle. A gamma source and detector detect metal height in the pouring spout which is a function of pouring rate. Electronic circuitry converts the detector output to a 'value corresponding to the amount of metal poured and the pouring is stopped at a predetermined value.

This invention relates to a mechanical metal pouring system and more particularly to a mechanical metal pouring control apparatus for automatically controlling the amount of metal poured and means for detecting metal height in a ladle pouring spout.

It has been proposed to use pressure ladles for pouring metal such as iron into molds wherein the molten metal within the ladle is forced from the pouring spout thereof by regulated compressed air within the ladle. Prior to this invention it has been found that accurate control of the amount of metal poured was not possible. Previously, the chief manner of pouring a measured amount of metal was to regulate the air pressure within the ladle so that the level of the metal in the pouring spout was at approximately a constant predetermined height so that the rate of metal flow would be at an approximately constant predetermined rate and the pouring was continued for a specified time, thereby pouring roughly the desired amount of metal into the mold. This means is not accurate because in practice, the metal level in the pouring spout will in fact fluctuate so that the amount of metal poured into each mold was not constant. This, of course, resulted in spillage or other waste of metal.

It is a general object of this invention to provide a pouring control means for a metal pouring ladle.

It is another object of this invention to provide means for accurately pouring predetermined amounts of metal from a ladle.

It is a further object of the invention to provide improved means for detecting the rate of flow of metal from the pouring ladle.

An additional object is to provide means for detecting the height of metal in a ladle pouring spout by radioisotope detection means.

It is still another object of the invention to integrate the metal pouring rate from a ladle throughout a pouring period to arrive at a measure of the amount of metal poured.

The invention is carried out by providing means to sense the metal height in a metal pouring spout and means to generate a voltage which is a function of the metal pouring rate and means to integrate the voltage to determine the amount of metal poured. Another feature is the provision of means to stop metal pouring when the integrated voltage achieves a desired value.

The invention is further carried out by providing a radiation source and detector on either side of the metal pouring spout to provide a signal which is a function of the metal height in the spout and correspondingly, a function of the pouring rate.

The invention is further carried out by providing an 3,396,870 Patented Aug. 13, 1968 apparatus for detecting the metal level in the pouring spout and for producing an output voltage which is in direct proportion to the rate of metal flow, and further apparatus for integrating that voltage to indicate the actual amount of metal poured. Further means are included to stop pouring when the desired amount of metal has been poured.

The above and other objects will become more apparent from the following description taken in conjunction with the accompanying drawings wherein like reference numerals refer to like parts and wherein:

FIGURE 1 is a schematic view of a mechanical iron pouring ladle and a block diagram of an electrical control system therefor according to the invention; and

FIGURE 2 is a partial schematic view of a mechanical iron pouring ladle and a block diagram of an electrical control circuit therefor according to another embodiment of the invention.

Referring now to FIGURE 1, apressure ladle 10 includes a receiving spout 12 and a pouring spout 14. Molten iron 16 is contained in the ladle and is forced through the pouring spout 14 in a controlled manner by compressed air from an air source 18 via conduit 20. The pressure of air within the ladle 10 and hence the height of metal in the pouring spout 14 is regulated by control valve 22 in conduit 20. Metal poured from the spout 14 flows through a funnel or pouring box 24 to a mold 26. A source of gamma radiation 28, preferably cesium 137, is located at one side of the pouring spout 14 and a radiation detector 30, preferably a Geiger Mueller tube or a plurality thereof, is located at the opposite side of the pouring spout. This arrangement is best shown in FIGURE 2. The metal within the pouring spout will block out a portion of the gamma radiation proceeding from the source 28 to detector 30 according to the height of the metal. The average pulse output frequency of the detector 30 will be an inverse function of the metal height. Referring again to FIGURE 1 the output pulses are then -fed to a pulse amplifier 32 and integrator 34 such as a capacitor and a voltage inverter 36, which will have an output voltage signal which is a direct function of the metal height in the pouring spout. The output of inverter 36 is fed directly to an air controller 38, which in turn is connected to the control valve 22 thereby providing a feed back means to control the air pressure within the ladle 10 according to the metal height. The output of inverter 36 is also fed to an integrating circuit which comprises a voltage to frequency converter 40 having its output connected to a preset pulse counter 42. The total count registered by the counter 42 is the integral of the output voltage of inverter 36. Since the metal height in pouring spout 14 is a direct function of the metal pouring rate, the integral of the metal height signal is a direct function of the amount of metal poured. By setting the pulse counter to a predetermined number of counts corresponding to the amount of metal desired to be poured, the counter 42 will produce an output when the desired amount of pouring is achieved. This output is fed to the air controller 38, which signals the valve 22 to relieve the air pressure in the ladle to thereby stop the pouring operation.

This system is not necessarily linear, even so it has been found in practice that the results are accurately repeatable by calibrating the counter to issue a stoppouring signal for a given amount of metal poured. Then constant results are obtained during each pouring operation. The relationship between the metal height and the rate of pouring is not linear, but rather the pouring rate is an exponential function of the metal height. In addition, the output of detector 30 is not a linear function of metal height. When, however, it is desired to have a linear relationship between the output of inverter 36 and the metal pouring rate, it is necessary only to include in the electronic circuitry one or more nonlinear elements which are chosen to compensate for the nonlinearity of the detector output. As an example, a nonlinear amplifier may be placed in series with the inverter 36 to provide this corrective function.

The circuit arrangement shown in FIGURE 2 is intended to achieve the same function as that of FIGURE 1 by slightly dilferent means. There, the pulsed output of the detector 30 is fed to a recorder rate meter 44 which mechanically drives potentiometer 46. The potentiometer 46 is preferably nonlinear. For example, it may be an exponential potentiometer so that it will compensate for the nonlinearities in the detection system and will have an output which is in direct proportion of metal flow rate. A power source 48 supplies voltage to the potentiometer and the potentiometer output is connected to the air controller 38 and the integrating circuit 40 and 42 as described with respect to FIGURE 1. Where the potentiometer output is proportional to flow rate, then of course, the output of counter 42 will be proportional to the amount of metal poured.

In practice, this invention has proven capability of controlling iron pouring at great speeds and with amazing accuracy. For example, one mechanical pouring system equipped with apparatus according to this invention is capable of pouring 450 pound aliquots of iron in 3 /2 seconds in rapid succession and having an error of no more than one pound. A pouring ladle of this type has a capability of 50 tons per hour and accordingly requires a precision automatic control like that of this invention. Such accuracy has not been provided by any other type of control. Another advantage of the proposed system is that the radioisotope detection system replaces the brick float in the pouring spout which is used in conjunction with conventional controls. However, a brick will occassionally break off or erode and in addition, slag sticks to the brick. These problems are eliminated by using the gamma source. The gamma radiation is essentially insensitive to the slag as compared to the metal and would require only some electronic adjustment as the pouring spout lining gradually erodes.

It will thus be seen that this invention provides a greatly improved control means for mechanical metal pouring by accurately measuring out the amount of metal poured and automatically stopping pouring when the desired amount has been poured.

The embodiment of the invention described herein is for purposes of illustration and the scope of the invention is intended to be limited only by the following claims.

What is claimed is:

1. In an apparatus for controlling a mechanical metal pouring ladle, means for measuring the amount of metal being poured comprising in combination; means for producing a voltage which is a function of the height of metal in the ladle pouring spout and of the metal pouring rate, and means for integrating the voltage and generating an output signal upon achieving a predetermined integrated voltage comprising a voltage-to-frequency converter having an output pulse rate proportional to the voltage and to the metal height and a pulse counter connected to the converter output, the number of pulses counted being a function of the amount of metal poured.

2. In an apparatus for controlling a mechanical metal pouring ladle as described in claim 1 wherein the counter is preset to a count corresponding to the total amount of metal desired to be poured, so that the counter produces an output signal when the preset count is achieved, and means responsive to the output signal for stopping the pouring of metal.

3. In an apparatus for controlling a mechanical metal pouring ladle, means for measuring the amount of metal being poured and for controlling the pouring rate comprising in combination; means for producing a voltage which is a function of the height of metal in the ladle pouring spout and of the metal pouring rate, means responsive to the voltage for controlling the height of metal in the ladle pouring spout, a voltage-to-frequency converter having an output pulse rate proportional to the voltage and to the metal height, and a pulse counter connected to the converter output, the number of pulses counted being a function of the amount of metal poured.

4. In an apparatus for controlling a mechanical metal pouring ladle, means for measuring the amount of metal being poured comprising in combination; metal height monitoring means for producing a pulsed output signal having an average frequency which is an inverse function of metal height, means connected to the output of the monitoring means for converting said output signal to a voltage having a direct correspondence to metal height, means for integrating the voltage comprising a voltage-to-frequency converter having an output pulse rate proportional to the voltage and to the metal height and a pulse counter connected to the converter output, the number of pulses counted being a function of the amount of metal poured.

5. In an apparatus for controlling a mechanical metal pouring ladle, means for measuring the amount of metal being poured comprising in combination; means for producing a voltage which is a function of the height of metal in the ladle pouring spout including a source of radiation at one side of the spout and a radiation detector at the other side of the spout whereby the amount of radiation reaching the detector from the source is dependent upon the metal height and the detector output signal is an inverse function of the metal height and further including means for inverting said detector output signal thereby producing said voltage, and means for integrating the voltage comprising a voltage-to-frequency converter having an output pulse rate proportional to the @ltage and to the metal height, and a pulse counter connected to the converter output, the number of pulses counted being a function of the amount of metal poured.

References Cited UNITED STATES PATENTS 3,042,258 7/1962 Mayes 222--76 X 3,186,596 6/1965 Badgett 222-14 3,248,061 4/1966 Franz 250-435 ROBERT B. REEVES, Primary Examiner.

HADD S. LANE, Assistant Examiner.

Images