US2223617A

US2223617A - Casting ladle and heating means therefor

Info

Publication number: US2223617A
Application number: US231629A
Authority: US
Inventors: George H Johnston
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-09-26
Filing date: 1938-09-26
Publication date: 1940-12-03
Anticipated expiration: 1957-12-03

Description

Dec. 3, 1940. G. H. JOHNSTON CASTING LADLE AND HEATING MEANS THEREFOR 2 Sheets-Sheet l Filed Sept. 26, 1958 Dec. 3, 1940. G. H. JOHNSTON CASTING LADLE AND HEATING MEANS THEREFOR Filed Sept. 26, 1938 2 Sheets-Sheet 2 ibi Patented Dec. 3, 1940 UNITED STATES PATENT OFFICE CASTING LADLE AND HEATING MEANS THEREFOR 2 Claims.

This invention relates to the type of ladle or container which is employed in transferring molten metal from a furnace to the mold or molds into which it is poured, and the invention is con- 5 cerned With improving the quality of the ingots or castings by controlling the temperature of the metal in the ladle in such a Way as to prevent and avoid the defects and difficulties incident to present methods. One object of the invention is to pro- 0 vide convenient means for pre-heating the ladle to the proper temperature before it is filled With molten metal from the furnace Another object is to provide means for maintaining both the ladle r and its contents at a high temperature as long as the molten metal is contained in the ladle. A further object is to provide for separately regulating the heating effect in different portions of the ladle, as may be required. Other objects will appear as the description proceeds. The inven- -0 tion consists in certain features and elements of construction, as herein shown and described and as indicated by the claims.

In the drawings:

Figure 1 is a sectional view of a ladle embodying this invention, being a transverse vertical section substantially on a diameter, but with a portion of the inner lining removed to reveal the arrangement of the vertical heating element.

Figure 2 is a horizontal section taken substantially as indicated at line 2 2 on Figure l, but omitting the plastic cement iilling and also the inside lining of refractory material.

Figure 3 is, principally, a top plan view of the ladle with a portion broken away to show certain features in section substantially at the plane indicated by the line 3--3 on Figure 1.

Figure 4 is a detail face view of a grooved lining brick for the ladle.

Figure 5 is a similar face View of another type of grooved brick for making a part of the lining.

Figure 6 is a detail section at line 6 6 on Figure 5. v

When molten metal, such as iron or steel, is tapped from a furnace in which it has been melted and treated, it has a certain specified analysis and temperature. In the process of tapping, as the metal flows into the ladle, there is, unavoidably, some turbulence and splashing due to the violent impact of the heavy molten mass. The molten slag and metal tend to attack the refractory lining of the ladle, both chemically, causing corrosion, and by mechanical erosive action. In addition, if the ladle is at ordinary room temperature, much lower than that of the molten metal, the metal tends to solidify suddenly on the inner Wall and on the bottom of the ladle, causing skulls and plates The sudden heat shock may also precipitate some of the ingredients of the metallic mixture, altering the analysis or composition. And when a plate thus forms on the bottom of the ladle, the stopper which controls the pouring is likely to be involved in the solidified metal, so that loosening of the stopper breaks away a part of the refractory lining at the nozzle of the ladle; this destroys control of the pouring, causing what is generally called a running stopper or dribbling which creates undesirable splashing of the metal around the sides of the mold as it escapes from the ladle.

My invention overcomes these difficulties in a manner which will be most readily understood by consideration of the structure shown in the drawings. As illustrated, the ladle includes an outer metallic shell I, which may be of any suitable form and dimensions, and is shown provided with trunnions 2, for mounting in a suitable support. The inner surface of the metallic shell I is lined with a refractory material 3, which may be referred to as a safety lining, in that it forms the final protection for the shell I against the molten metal in the ladle, although, ordinarily, the metal will never come into contact with this final safety lining.

shaped tiles or bricks, molded With channels in their inner faces. The channels are so spaced` that they form continuous grooves on the inner face of the lining 4, adapted to receive metallic electrical conductors 5. such resistance that when supplied with a suitable current, they act as heating elements, and they are disposed in any convenient arrangement for distributing the heating effect, as required, i

having a single groove or channel 4b, While the r transverse portions Gb occupy grooves formed in special tiles 4, each having a vertical groove 4d dimensioned to connect With the grooves 4b of the tiles #Ia and having horizontal grooves 4e which connect with each other, as clearly seen 5 Within the refractory 3 a second refractory lining 4 is formed of suitably These conductors are of in Figure 1. In like mann-er the bottom Wall is made up of grooved tiles 4f to receive the portions of the conductor 6 which are to serve for heating the bottom Wall.

The conductor elements 6 having been placed in the channeled surfaces of the refractory 4, are then sealed in place by the addition of a plastic cement which lls the additional space in the grooves of the tiles, and also covers their inner surfaces. Then, finally, an inner refractory lining 8 is built around the side walls and over the bottom of the ladle. In Figure 3, and in that portion of Figure 2 in which the conductor elements 6 are visible, it may be understood that the plastic cement is not shown; the parts are represented as they would appear before `addition of the cement.

The outer refractory, or safety lining, is of a composition which tends to retain the heat in the ladle without transmitting it rapidly to the outer shell I. The intermediate refractory 4 may be similar in this respect, and, of course, it must be a good electrical insulator in order to serve as the support for the conductor elements 6. The grooved formation of the lining 4 Will serve to keep the adjacent portions of the conductors out of contact with each other if their temperature should tend to cause expansion and distortion of the elements. The inner r-efractory 8, however, is different in composition from the lining 3, in that it is a good conductor of heat, Iso that the heat generated in the conducting element 6 Will be readily transmitted through the lining 8 to the molten metal in the ladle, thus opposing the tendency of' the metal to radiate its heat through the Walls of the ladle. Around the upper rim of the ladle the cavity in the lining which is provided by the grooved formation for accommodating the conductors 6, is closed by a course of refractory brick 9, and it Will be understood that this material should be similar in quality to that of the outer lining 3, so as to conline the heat rather than radiate it to the air above the ladle.

Various circuit arrangements may be provided for thev heating elements 6. Conceivably, the conductor occupying the bottom of the ladle might be one circuit, and the conductor extending around the 'side Wall might constitute a separate circuit, or these two could be connected in series so as to be energized simultaneously `at `all times. However, it Will usually be found more convenient to have the heating element arranged in several separate circuits, and, preferably, s'o that each circuit corresponds to a definite portion of the ladle or its inner surface in order that the electrical heating effect may be regulated as conditions may require. As shown in the drawings, the heating elements are divided into four circuits, each occupying a quadrant of the ladle. Each circuit includes the portions 6a and 6b, distributed over one-fourth of the side Wall area, together With the portion 6c, Which is arranged in` convolutions distributed over a quadrant of the bottom. Separate terminals l are shown emerging from the side of the ladle for each of the four groups of conductors. Thus, if it should be found that there is some chilling effect in the vicinity of the nozzle opening I I when the pluglnot shown) is withdrawn for pouring the metal, the current flowing through the portion of the heating element 6 in this quadrant, may be increased to prevent any substantial lowering of the temperature from this cause. Similarly, any of the other sections or circuits may be given individual attention, when required. And for protecting the terminals l0 against any -splash or overflow of molten metal or slag, they may be provided with overhanging metallic hoods l2, as indicated in dotted outline in Figure 2, and as seen in Figure 3.

It will be readily seen that with a ladle made in accordance With this invention, the temperature of the ladle may be raised to the proper degree by means of the electrical heating elements before the furnace is tapped, so that When the molten metal is allowed to flow into the ladle, it Will come in contact with surfaces at approximately its own temperature. Then, by controlling and maintaining the temperature of the ladle at the proper point as long as the molten metal is contained in it, the composition of the metal can be kept uniform and in accordance with its original analysis, and its delivery from the ladle can be satisfactorily controlled. As a result, there Will be a better quality of ingots or castings produced, and much less liability of accident in the handling of the molten metal.

While there isfshown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and re-arrangements of the parts may be made without departing from the spirit and scope of the invention, and that the same is not limited to the particularform herein shown and described, except in so far as indicated by the appended claims.

I claim:

1. A portable ladle comprising a metallic shell, a refractory safety lining therein, an insulating refractory lining overlying the inner surface of the safety lining and providing a channeled inner surface, an electrical conductor non-inductively disposed in the channels of said surface to s'erve as a heating element, a sealing of plastic cement enclosing the conductor in the channeled surface, and a refractory lining overlying the sealing layer in the ladle.

2. A portable ladle comprising a metallic shell, an insulating refractory lining therein providing a channeled inner surface, an electrical conductor non-inductively disposed in the channels of said surface to serve as a heating element, a sealing of plastic cement enclosing the conductor in the channeled surface and completely filling the channels thereof, and a refractory lining overlying the sealing layer in the ladle.

GEORGE H. JOHNSTON.