US 3299706 A
Description (OCR text may contain errors)
Jan. 24, 1967 R. BAILEY ETAL 3,299,705
APPARATUS FOR MEASURING MOLTEN METAL LEVELS IN LADLES Filed April 5, 1964 INVENTORS Gilbert R. Bailey 8 United States Patent 3,299,706 APPARATUS FOR MEASURING MOLTEN METAL LEVELS IN LADLES Gilbert R. Bailey, Ligonier, and Alex Simkovich, Latrobe,
Pa., assignors to Latrobe Steel Company, a corporation of Pennsylvania Filed Apr. 3, 1964, Ser. No. 357,117 1 Claim. (Cl. 73304) This invention relates to methods and apparatus for measuring molten metal levels in ladles and particularly to a method and apparatus for warning the approach of slag toward the nozzle of the ladle so that slag contamination of the last metal poured can be avoided.
A very real and long existing problem in the metal melting art has been the problem of determining when the slag on the metal in the ladle being teemed was approaching the nozzle so that its issuance from the nozzle could be avoided. Up until the present invention the determination of the position of the slag metal interface in the ladle was a matter of pure conjecture and the last metal poured was invariably contaminated with slag, the amount of which was limited purely by the alertness and reflexes of the ladle man operating the ladle stopper.
We have invented a method and apparatus for measuring molten metal levels in ladles and eliminating the contamination of the last metal poured by slag. Preferably we provide a ladle having a nozzle in the bottom thereof, stopper means movable in the ladle for opening and closing said nozzle, means for moving said stopper means into and out of said nozzle, a pair of conductor members extending into the ladle to a predetermined oint above the nozzle, an electrical circuit connecting said pair of conductor members, means for applying an electrical potential to said circuit and signal means indicating a change in the electrical characteristics of said circuit such as for example a change in electrical resistance. The conductor members may be a pair of rods extending through the ladle sidewall, a single rod through the sidewall and the head of the stopper acting as a conductor or any of a variety of other paired conductors within the scope of the claim hereafter set forth.
In the foregoing general statement we have set out certain objects, purposes and advantages of our invention. Other objects, purposes and advantages will be apparent from a consideration of the following description and the accompanying drawings in which,
FIGURE 1 is a schematic drawing of one embodiment of our invention; and
FIGURE 2 is a schematic drawing of a second embodiment of our invention.
Referring to FIGURE 1, we have illustrated a ladle 10, having a refractory lining 11. A nozzle 12 is provided in the bottom of ladle 10. The nozzle is opened and closed by a steel stopper rod 13 having a clay-graphite head 14 and surrounded by refractory sleeve 15. A stopper rod operating handle 16 of conventional form operates the stopper rod. An electrical lead 17 connects with the clay-graphite head 14 through steel stopper rod 13. A second electrical lead 18 connects to a graphite rod 19 situated in an opening 20 in the sidewall of the ladle and exposed to the ladle interior. The leads 17 and 18 are connected to a combination source of potential and a signal device for indicating a change in electrical character of a circuit such as a battery powered voltimeter 21.
Patented Jan. 24, 1967 When the ladle is used for transferring molten metal covered with slag as is conventional in the metal industries the meter 21 will give one reading so long as molten metal forms a part of the circuit between head 14 and rod 19. As soon as the slag reaches a position where it forms the connection between head 14 and rod 19 a much higher resistance will occur providing a signal change on the voltimeter 21. For example, with molten metal forming a part of the circuit a reading of 0.1 to 0.3 ohm is obtained. As soon as the slag takes the place of the molten metal as the circuit member the resistance will jump to to 200 ohms or more depending upon the character of the slag. At this point the stopper rod is lowered shutting the nozzle and preventing slag from flowing from the ladle.
In the embodiment shown in FIGURE 2 we have illustrated a ladle 50, having a refractory lining 51, a nozzle 52 and a stopper rod 53 covered by a refractory sleeve 54 and having a refractory head 55. An electrically powered operator 56 is mounted on the side of the ladle to raise and lower the stopper rod. This powered actuator may be an electromagnet 57 having a moving core 58 or it may be a motor and drive rod, or a solenoid operated air cylinder or any similar device. A pair of zirconium diboride rods 59 and 60 extend through openings in the sidewall of the ladle at a predetermined level above the bottom. Electrical leads 61 and 62 connect rods 59 and 60 to a source of electrical potential 63 and a signal device 64 such as a solenoid switch which actuates the operator 56. When the space between rods 59 and 60 is filled with molten metal the actuator 56 holds the stopper rod 53 in the raised position with the nozzle open. When slag occupies the space between the rods 59 and 60 the increased resistance opens the solenoid 64 to cause actuator 56 to lower the rod into the nozzle cutting oif the flow from the ladle.
While we have illustrated and described certain preferred embodiments of our invention in the foregoing specification, it will be apparent that this invention may be otherwise embodied within the scope of the following claim.
In a vessel for holding and transferring molten metal covered with slag or other material having a different conductivity than metal and having a discharge nozzle and stopper rod for controlling the flow of metal through the nozzle, the improvement comprising a conductor member situated in the ladle wall at a predetermined level adjacent the discharge nozzle, a conductor stopper head on the stopper rod, an electrical circuit connecting said conductive stopper head and said conductor member, means for applying an electrical potential to said circuit, and signal means indicating a change in the electrical characteristics of said circuit.
References Cited by the Examiner UNITED STATES PATENTS 1,982,821 12/1924 Marsclen et al. 252502 2,546,142 3/1951 Watson 252520 X FOREIGN PATENTS 623,555 12/1935 Germany. 645,807 11/1950 Great Britain.
LOUIS R. PRINCE, Primary Examiner.
S. C. SWISHER, Assistant Examiner.