US2485492A - Device for sampling molten metal in a ladle or the like - Google Patents

Description

L A T E .LM A E mx@ NTIS ME D H3 Rmz AIRh BLOC BPsm MEM UML H .Dd RAe NmLn .EmF H w v E D Oct. 18, 1949.

Patented Oct. 18, 1949 UNITED STATES PATENT OFFICE DEVICE FOR SAMPLING MOLTEN METAL IN A LADLE OR THE LIKE Howard N. Hubbard and Edward F. Ketterer,

Lorain, Ohio, assignors to National Tube Company, a corporation of New Jersey Application March 23, 1948, Serial No. 16,584

Claims. (Cl. 'i3-425.4)

handled dipper or spoon and pour them into a cast iron chill mold. Samples so taken are satisfactory for chemical analysis but, because they are cooled suddenly, do not reveal the grain characteristics or graphitization to be expected when the metal is cast in a relatively large mass and slowly cooled, i. e., when poured in a large mold such as an ingot mold. In the previous practice, a sample of molten iron, for example, is converted into white chilled cast iron of physical characteristics widely different from those of ordinary gray iron. Micrographic examination of such samples, therefore, gives only limited useful information. Taking samples from the surface also involves an ever-present danger of contamination of the sample by slag floating on the metal.

We have invented a novel device for taking samples whereby the foregoing objections are overcome and a clean, slowly-cooled sample is obl tained from which much significant information may be derived by micrographic analysis. The sample thus shows accurately the properties the metal in the main mass will exhibit when cast in molds. In the case of iron, the sample remains normal gray iron instead of being converted to white chilled cast iron. In a preferred embodiment and practice, we place a refractoryI tube within a shielding sleeve, mount them in one end of a tubular or hollow handle and provide the upper end of the tube with a closure adapted to lthe contents cooled slowly. After freezing, the

sample is removed from the tube.

We are aware that it has been proposed previously to provide a sample dipper with a temporary closure adapted to be destroyed or fused by the molten metal. Our invention utilizes that expedient but is more particularly concerned with a sampling device insuring slow cooling of the sample whereby the condition of the latter as revealed by micrographic analysis will have significance in respect to the characteristics to be expected of the remainder of the metal when cast.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawing, the single gure of which is a central vertical section through our improved sampling device.

Referring in detail to the drawing, an elongated tubular handle I0, which may be a length of pipe of suitable size, has one end bent to form a crook or U-shaped portion Il with a relatively short limb. rIfhe other end is bent to form a hook Il for suspending the sampling device from any suitable support. A bell reducer I2 is threaded onto the upturned lower end of the handle and a sleeve I3 is screwed into the large end thereof. A plate or disc I4 of copper or other metal of high thermal conductivity, having a central orice |48, is seated in the reducer I2 for a purpose which will appear later. A reducer I5 is screwed onto the upper end of sleeve I3.

A refractory tube I6 extends through sleeve I3 and bottoms on disc I4 which forms a closure. Sealing rings I'I of suitable packing material, such as asbestos wick, are applied to the tube I6 and seal the clearance between the tube and the reducers. The tube is preferably inserted in the sleeve and the sealing rings applied before the sleeve is screwed into reducer I2. The tube is composed of heat-resisting glass, quartz, graphite or other suitable material capable of withstanding the temperature of molten iron for a short time at least. It is preferably about 5A," inside diameter and about 9" long, and is provided at its upper end with a temporary closure disc I8 of heat-destructible material, such as pasteboard. The outside diameter of the tube is considerably less than the inside diameter of sleeve I3 whereby an air space I9 is left therebetween.

In using the device described above for sampling, it may rst be coated on the exterior with a refractory slurry which, after drying, serves to protect it from the heat of the metal to be sampled. The user'then seizes the handle I0 and submerges the lower end in the molten metal to be sampled, e. g., a ladle of iron tapped from a blastfurnace, manipulating the device so that the tube I6 is kept substantially vertical. When the handle has been lowered in the metal to a depth suillcient to cover the upper end of the tube, the closure I8 is burned out and metal flows into the upper end of the tube. As metal descends through the tube, it displaces any air initially trapped therein which escapes through orifice or vent I4a in disc I4. The metal which rst strikes the disc is chilled and quickly solidles because 3 of the high thermal conductivity thereof. The disc should be of such mass as to favor this result. A plug of solid metal is thus formed at the bottom of tube I6 which prevents liquid metal from entering the handle I0 through orice |12.

When the tube I6 has been filled with molten metal which occurs within a few seconds after destruction of closure I8, the device is removed from the bath and may then be hung up by hook Ila until the sample in the tube has solidified after slow cooling. It will be apparent that the sleeve I3 protects the tube I6 in large part, at least, from direct contact with the air, thus preventing rapid cooling or quenching of the sample. The refractory nature of the tube `IIi also delays cooling of the sample. When the sample has ccoled substantially to atmospheric temperature, the tube I6 is removed from the sleeve by unscrewing the reducers, and the sample from the tube. Usually the latter requires destruction of the tube but the cost thereof is small. A fresh tube with a closure I8 therein and packing I1 at the ends is inserted in the sleeve and the reducers are coupled to the latter preparatory to the next sampling operation.

The lower end of the sample which is subjected to chilling and quick cooling by Contact with disc I4 is cut off and may be discarded or used for chemical analysis. The remainder of the sample, having been slowly cooled, when ground,

etched and polished, reveals the grain structure and degree of graphitization to be expected of the main mass of metal if cast in molds for slowcooling, as well as giving a rating as to any nonmetallic inclusions, when examined under the microscope in the known manner. In taking a sample of iron, the sample exhibits the structure characteristic of gray iron and is not converted to white chilled cast iron.

It will be apparent from the foregoing that and the character of the material of whichvthe tube I6 is composed, permits the formation of graphitic carbon and leaves the sample in the form of gray iron except for the initially solidified bottom plug in contact with disc I4. yThe quanti-ty and distribution of excess carbonmay readily observed. .The` physical examinaa slowly-cooledr representative sample should vmake possible improved operationpf the blast furnace and the manufacture'of a superior product.

A sample taken by aid of the invention `fractures easily for visual examination and is of convenient size for polishing and etching preparatory to metallographic analysis. The replaceable tube I6 produces a smooth-surfaced test piece of uniform diameter. Air initially entrapped in the tube is completely vented, thus preventing the formation of an unsound specimen. Our irnproved sampling device is well adapted for taking samples from a deep pool, such as a tapping ladle, and it affords a cooling rate which is substantially uniform from sample to sample, regardless of variations in atmospheric conditions.

Although we have illustrated and described but a preferred embodiment and practice of the invention, it will be recognized that changes in the details and arrangement disclosed may be made without departing from the spirit of the invention or the scope of the appended claims.

1. A device for taking samples of molten metal comprising a refractory tube, a shielding sleeve surrounding said tube, a handle to which one end of said tube and sleeve are secured, said handle having an exit passage for air displaced from said tube, and a disc at said one end of said tube having an air vent therein.

2. In a device for sampling molten metal, an elongated member adapted to have one end immersed in the metal, a refractory tube extending upwardly from said one end of said member, said member having a passage for air displaced from said tube, and a closure at the lower end of the tube having an air vent therein.

3. The apparatus dened by claim 2 characterized by a shielding sleeve surrounding said tube.

4. In a device for sampling molten metal, an elongated handle, a sampling tube xed at one end of said handle and extending upwardly therefrom, said handle having an exit passage for air displaced from said tube, and a disc at the lower end of said tube having an air vent therein.

5. The apparatus defined by claim 4 characterized by a shielding sleeve surrounding said tube.

6. The apparatus defined by claim 4 characterized by said handle being tubular.

7. In a device for sampling molten metal, a. U-tube, one limb of which is shorter than the other, a sampling tube fixed in and extending upwardly from said shorter limb, and an orifice plate at the bottom of said sampling tube permitting the escape of air but restricting flow of metal from the sampling tube to the U-tube.

8. The apparatus defined by claim 7 characterized by a shielding sleeve surrounding said sampling tube.

9. A device for sampling molten metal comprisnga tubular handle, a shielding sleeve secured to one end of said handle and extending upwardly therefrom a sampling tube disposed within said sleeve, and an orifice plate at the bottom of the sampling tube.

10. The apparatus defined by claim 9 characterized by said handle having a crooky at said one end.

HOWARD N. HUBBARD. v EDWARD F. KETTERER.

v'milnmnvclis CITED The following references are of record in the le of this patent:

OTHER REFERENCES American Institute of Mining and Metallurgical Engineers, vol. 122, 1936, p. 197.

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