US3599835A

US3599835A - Dispensing apparatus for and methods of casting

Info

Publication number: US3599835A
Application number: US775337A
Authority: US
Inventors: Friedrich Kocks
Original assignee: Individual
Current assignee: Friedrich Kocks GmbH and Co
Priority date: 1968-09-20
Filing date: 1968-11-03
Publication date: 1971-08-17
Anticipated expiration: 1988-08-17

Abstract

A method and apparatus are provided for maintaining a constant casting speed in casting molds by the steps of weighing the molten metal before casting, weighing the molten metal at least at spaced time intervals during casting and adjusting the flow of steel into said casting mold at said spaced time intervals to discharge a substantially identical weight amount in each time interval. An apparatus for maintaining a constant speed in casting provides a pouring ladle, discharge means on the ladle, weighing means supporting said ladle, a voltage transmitter sensitive to weight change connected to the weighing means and transmitting a voltage proportional to a change in weight, a voltage comparator receiving the transmitted voltage, comparing the same with a standard voltage representing a desired casting speed and transmitting a signal indicating a deviation from the standard.

Description

Elited States Patent [72] inventor Friedrich Kocks lFreiligrathstrasse l, 4 Dusseldorf, Germany [2i] Appl. No. 775,337 [22] Filed Nov. 3, 1968 [45] Patented Aug. 17, 1971 [32] Priority Sept. 20, 1968 [33] Germany [31] P15 83658.5

[54] DlSPENSlNG APPARATUS FOR AND METHODS OF CASTING 6 Claims, 1 Drawing Fig.

[52] US. Cl 222/58 [51] int. Cl B65h 1/08 [50] Field 0! Search... ZZZ/58,77

[56] References Cited UNITED STATES PATENTS 2,718,982 9/1955 Long 222/58 3,3 19,828 511991 Maxwell H gag/sax .1,883,017 10/1932 Sholtz 2,040,157 5/1936 Storyetal 222/58 Primary Examiner-Samuel F. Coleman Attorney-Buell, Blenko & Ziesenheim ABSTRACT: A method and apparatus are provided for maintaining a constant casting speed in casting molds by the steps of weighing the molten metal before casting, weighing the molten metal at least at spaced time intervals during casting and adjusting the flow of steel into said casting mold at said spaced time intervals to discharge a substantially identical weight amount in each time interval. An apparatus for maintaining a constant speed in casting provides a pouring ladle, discharge means on the ladle, weighing means supporting said ladle, a voltage transmitter sensitive to weight change connected to the weighing means and transmitting a voltage proportional to a change in weight, a voltage comparator receiving the transmitted voltage, comparing the same with a standard voltage representing a desired casting speed and transmitting a signal indicating a deviation from the standard.

PATENTEDAusmsn 3,599,835

mvsmon Friedrich Kocks DISPENSENG APPARATUS FOR AND METHODS OF CASTING This invention relates to apparatus for and methods of casting and particularly to apparatus for and methods for maintaining a constant casting speed.

The quality of a metal casting is known to be influenced by the casting speed, which has an influence, for example, on the segregation, shrinking, cracking and solidification of the metal. For example, it is necessary to cast rimming soft pipe steel at a slow casting speed in molds with a circular section. Similarly in other operations it is known that better quality of casting is obtained if a certain speed of casting is observed.

Unfortunately casting speeds are very seldom given in practice or at best are given only in general data because an exact value cannot be observed in the past without auxiliary equipment of an expensive and complex nature. As a result the casting speed for mold casting was given very little consideration in the technical literature and virtually no ideas or suggestions can be found concerning the quality control of the casting speed during the casting operation. It was only a very few in stances, such as that of rimmed pipe steel, that even a rough attempt was made at controlling casting speed.

In the case of continuous casting operation, it is common practice today to maintain a constant casting speed. This is accomplished by controlling the withdrawal speed of the cast strand and by controlling the height or level of metal in the mold. Various other means for measurement and control are well known in continuous casting such as the use of tracers and the measurement of their conductivity. The methods used in continuous casting are not, however, adaptable to ingot casting.

The present invention provides a method and apparatus for maintaining a constant casting speed when casting iron or metals in ingots. The major factors which influence the casting speed in casting ingots are the melt height in the pouring ladle, the discharge section and the viscosity of the metal. Since all of these change relatively uncontrollably as the casting time progresses, the measurement of casting speed must take all of these into consideration.

The method of this invention to maintain a constant casting speed is based on the assumption, that the iron or metal melt is poured out of a pouring ladle and into a mold. The quantity flowing out in a certain time can be controlled by removing the stopper rod or by tilting the pouring ladle. The quantity flowing out in a certain time can be controlled by removing the stopper rod or by tilting the pouring ladle. The pouring ladle can also be provided with several stopper rod openings of which only one or a few are opened to allow for the outflow of small quantities in a certain time, and where several or all stopper rods have to be removed to allow the outflow of larger quantities if desired.

The method is thus characterized in that the discharged quantity is computated during the casting operation by weighing the pouring ladle. The computated value can be indicated and/or after conversion into control data be used to control the drive for removal of the stopper rod and for tilting the pouring ladle.

These measures make it possible to utilize the experiences from continuous casting for ingot castings to achieve a high quality of the castings and to avoid faulty castings due to cracks and segregations which are unfavorable for further processing. Besides, all ingots off the same heat will be of more uniform quality.

A different approach of this method is to check the weight of the pouring ladle at the beginning and the end of a given time interval and to indicate the weight difference and/or use this value to regulate or control the drive to lift the stopper rod or to tilt the pouring ladle.

The length of the time interval has to be adjusted to the prevailing circumstances. If, for example, a pouring ladle is used to cast only one big ingot, it will be sufficient to divide the total casting time into about five time intervals. if one pouring ladle is used to cast several ingots, the pouring time for one ingot should be divided in several time intervals.

If the computated weight difference is used to control the drive for lifting the stopper rod or tilting the ladle, it is advisable to compare the weight difference with a nominal value and to use the difference of latter to control the pouring. This can be done by using analogues or digital values.

An installation to use this method is thus characterized in that a pouring ladle with stopper rod or tilting drive is suspended in a weighing system. The weighing system is connected to a potentiometer or another voltage transmitter of which the voltage expressed as actual value is propositional to the ladle weight, and is compared with the voltage constituting the nominal value. The nominal value voltage is changed during the casting operation according to the casting speed desired. The result of the comparison of nominal to actual value is used to control the drive on the pouring ladle.

The practice of the present invention and an apparatus for carrying out the invention will perhaps be best understood by referring to the accompanying drawing showing a schematic arrangement of an analogue control system according to the present invention.

Referring to the drawing I have illustrated a typical ingot mold l and a typical casting ladle 3 as used in casting steel. The ingot mold l for the metal is erected in the casting pit 2 and is filled from the casting ladle 3. The casting ladle 3 has an opening 4 which is opened for pouring by a stopper rod 5 moving up and down. The pouring ladle 3 is suspended in the crane rig 6 which also incorporates the scale 7. The recording of scale 7 is transmitted over a pinion and pinion rack 8 to slide 12 of potentiometer 9. A similar potentiometer 10 is used as actual value sender, and its slide 13 is moved according to the desired pouring speed by the DC motor 14 over gear drive 15 and threaded spindle 16. To preadjust the nominal value of the casting speed the voltage of potentiometer 17 which is fed by the source of current 18 is adjusted and this in turn controls the speed of DC motor 14. Both terminals (12 and 13) of potentiometers (9 and 10) are connected electrically with a minivoltmeter 20 which indicates any deviations from the desired casting speed. The voltage difference of both terminals (12 and 13) can also be used to regulate a drive motor 5a for stopper rod 5 through

lines

12a and 13a. Switch 19 is for reversing or switching off of DC motor 14.

The installation is operated in the following way:

Casting ladle 3 filled with liquid metal is moved into pouring position. Scale 7 indicates the weight. Slide 13 is brought by motor 14 into such a position that minivoltmeter 20 does not indicate any voltage difference. The desired casting speed is adjusted at potentiometer 17. By lifting stopper rod 5 motor 14 is started by switch 19. Any weight loss of ladle 3 is controlled during casting by opening or closing stopper rod 5 in such a way that minivoltmeter 20 shows a very small, or no voltage indication at all. After ingot 1 is filled, the stopper rod closes the opening, and motor 14 is stopped by switch 19.

While I have illustrated and described a present preferred practice of my invention in the foregoing specification, it will be understood that this invention may be otherwise embodied within the scope of the following claims.

I claim:

1. A method for maintaining a constant casting speed in casting into casting molds which comprises the steps of:

a. weighing the molten metal before casting;

b. weighing the molten metal at spaced equal time intervals during casting;

c. transmitting a voltage proportional to each change in weight;

d. comparing said transmitted voltage with a standard changing voltage representing a desired casting speed;

c. transmitting a signal indicating the deviation of the transmitted voltage from the standard and from the transmitted signal so as to discharge a substantially identical weight amount in each time interval; and

f. adjusting the flow of steel into the casting mold at said spaced equal time intervals.

2. A method as claimed in claim 1 wherein the flow of steel is adjusted automatically by comparing the weight change as represented by the transmitted voltage in any time period with a preselected standard weight change for a like time period as represented by the standard voltage and adjusting the flow to equal the difference in voltage represented by said weight change.

3. An apparatus for maintaining a constant casting speed in casting into molds comprising a pouring ladle, discharge means on said ladle, weighing means supporting said pouring ladle, a voltage transmitter sensitive to weight change connected to said weighing means and transmitting an electrical voltage proportional to a change in weight, a voltage comparator receiving said transmitted voltage and comparing the same with a standard changing voltage representing a desired casting speed and transmitting a signal indicating a deviation from the standard.

4. An apparatus as claimed in claim 3 wherein the signal indicating a deviation is delivered to a drive means controlling the ladle discharge means to vary the rate of flow whereby to neutralize the signal.

5. An apparatus as claimed in claim 3 wherein the weighing means is a stram gage.

6. An apparatus as claimed in claim 3 wherein the voltage transmitter is a potentiometer operated by the weighing means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 .599. 835 Dated August 17, 1971 Invent (s) Friedrich Kocks It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet under item [22] "Nov. 3, 1968'. should be Nov. 13, 1968 item [32] "Sept. 20, 1968" should be Nov. 17, 1967 Column 1, line 46, delete "The quantity flowing out in a certain time can be controlled by removing the stopper rod or by tilting the pouring ladle."

Signed and sealed this 24th day of October 1972.

(SEAL) Attest:

EDWARD M.FLE'ICHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents )RM Po-1o50 [10-691 USCOMM-DC moan-P09 9 U S GOVERNHENY PRINTING OFFICE 196D OSSG-SS

Claims

1. A method for maintaining a constant casting speed in casting into casting molds which comprises the steps of: a. weighing the molten metal before casting; b. weighing the molten metal at spaced equal time intervals during casting; c. transmitting a voltage proportional to each change in weight; d. comparing said transmitted voltage with a standard changing voltage representing a desired casting speed; e. transmitting a signal indicating the deviation of the transmitted voltage from the standard and from the transmitted signal so as to discharge a substantially identical weight amount in each time interval; and f. adjusting the flow of steel into the casting mold at said spaced equal time intervals.

5. An apparatus as claimed in claim 3 wherein the weighing means is a strain gage.