US1793314A - Method of and apparatus for producing ingots - Google Patents

Description

Feb. 17, 1931. E. GATHMANN METHOD OF AND APPARATUS FOR PRODUCING INGOTS Filed Aug. 22, 1927 2 Sheets-Sheet 1 Feb. 17, 1931. v E. GATHMANN METHOD OF AND APPARATUS FOR PRODUCING INGOTS 2 Sheets-Sheet 2 Filed Aug. 22, 1927 B & .lrll lJlll w w 0 O O 0, v n Uh M Q m. N 1:: fl .h i

Patented Feb. 17, 1931 PATENT OFFIC EMIL GATHMANN, OF BALTIMORE, MARYLAND METHOD OF AND APPARATUS FOR PRODUCING INGOTS Application filed August 22, 1927. Serial No. 214,584.

This invention relates to the art of casting metallic ingots in the form of slabs suitable for direct rolling or working into commercial shapes of various kinds.

6 In making of slabs heretofore, it has been the usual practice to cast the ingot metal in vertical molds. When solidified the ingots are stripped or removed from the molds by suitable stripping apparatus and placed in 10 reheating or soaking pits. When suitably heated, the ingots are reduced by rolling mill action to the desired size of slab, which is subsequently sheared or divided into unit lengths, which are then again reheated and rolled into desired shapes. These stripping, heating and preliminary rolling operations require elaborate equipment, expensive to install and to.

operate, the reducing of an ingot of say by horizontal cross section and 70" 20 length to a slab of say 30" width, 4 thickness and 30 length entailing a cost of approximately $3.00 to $4.00 per ton of slab.

Furthermore, there are inherent defects in such vertically-cast ingots which necessi- 25 tate a loss of from 10 to 15 percent of ingot metal2 to 3 percent crop usually being necessary from the bottom end of the slab due to fishtailing in rolling, from 6 to 10 percent top crop to eliminate the primary pipe and 2 to 3 percent scale loss in the soaking pitwhen slabs are thus produced.

The primary object of my invention is to reduce the cost of producing slabs, and this I accomplish by providing novel apparatus for and methods of forming slab ingots direct from the molten metal, whereby the preliminary heating and rolling of the ingot is eliminated and the total percentage of discard is reduced to from 4 to 6 percent.

In carrying out'my invention, I provlde means for conveying a plurality, in fact a multiplicity, of molds of suitable shape and dimension to a source of supply of molten metal, where they are filled and then passed under a heat-conserving cover. The ingots, after being sufficiently cooled to assure of the metal being solidified, are delivered to a conveyor which carries them to a reheating furnace forequalizing and, when necessary, increasing their temperature before rolling into plates, sheets or other product, or

to a place of storage or deposit for future use. The molds are of novel shape and construction and have chambers of such contour that the ingots cast therein are suitable, when heated to the proper temperature, for direct rolling into plates, sheets or other desired shapes.

My improvements are illustrated in the accompanying drawings and the preferred details of construction will be hereinafter more fully described:

Figure 1 is a plan view of the slab ingotforming apparatus above referred to.

Figure 2 is a detailed view, somewhat dia- 05 grammatic, showing the source of supply of molten metal and illustrating the manner in which this metal is delivered to the molds.

Figure 3 is a sectional viewshowing a refractory cover arranged above the molds, which is employed for the purpose of conserving the heat of the top portions of the ingots while they are solidifying in the molds.

Figure 4 is a side elevation of the apparatus with some of the parts in section and 76 others broken away.

Figure 5 shows a vertical section on the line 5-5 of Figure 4 and illustrates particularly; how the molten metal is delivered to the molds from a source of supply.

Figure 6 is a transverse section of the preferred form of mold.

. Figure 7 shows a transverse section of a modified form of mold which may be employed.

To cast slab ingots in horizontally-disposed molds seated upon the usual stationary mold stools would be an expensive operation requiring a vast number of molds and cumbersome stripping and handlin equipment. A heat of metal of'say 100 tons burden, with for instance each slab weighing approximately one ton, would require 100 molds. By the use of my apparatus, less thanhalf this number of molds will take care of a heat of this burden, since. each mold can be used several times in the teeming of a single heat.

As previously stated, the cropping and scale loss necessary in vertically-cast and rolledto-shape slabs is excessive. I, therefore, em-

ploy molds of the so-called horizontal type, the ingot chamber of which is of such contour that the waste of metal due to cropping and scaling is minimized.

In my U. S. Patent No. 1,661,039, of February 28, 1928, I have shown, described and claimed horizontal molds having the neces sary characteristics and, though shown herein, they are not herein claimed per se. It is important that the molds should be of such construction that the cooling at all horizontal planes or parts of the ingots formed therein will be primarily from the bottom upwards in a substantially uniform period of time, thus preventing any localized shrinkage cavities or so-called pipe'defects in the solidified metal.

The apparatus, which will ,now be more fully described, fulfills the requirements in the process of casting and solidifying slab ingots of the desired kind.

In the drawings I have illustrated two series of molds placed side by side and secured to conveyors, which carry the molds past a source of supply of liquid steel. Each of the molds A has the characteristics before explained. These molds are attached by suit-- able fastening means preferably to an endless carrier B of the kind shown, having chain conveyors of well-known construction. These conveyors are operated intermittently step by step; while one conveyor is moving, the movement of the other is suspended. One way of obtaining this intermittent movement is illustrated in the drawings, where C indicates a power shaft driven by a motor D of suitable kind and carrying two mutilated pinion gears E, F. The toothed portions of these gears E and F are adapted to operatively engage the pinions G and H on the shafts H of sprocket wheels with which the chain conveyors B engage. Speed-reducing gear of any suitable kind may be located at L, L in order that the mold conveyors may be driven at the desired speed. The movement of the conveyors, which should be relatively slow and smooth. without jarring, may be controlled by devices well known in the art. It will be observed by reference to Figure 1 that the pinion G is in mesh with the toothed portion of the mutilated gear F, so that the conveyor at the left hand side (as viewed from the bottom of the drawing) is being moved. At this time the non-toothed portion of the mutilated gear E is passing the pinion H so that the mold conveyor at the right hand side is at rest. This is one way of giving an intermittent movement to the conveyors, but many other ways could be substituted. It will be understood that when one conveyor is moving. the movement of the other is suspended.

In order to fill the molds successively as they proceed. I preferably employ the feeding devices shown in the drawings. M indicates a ladle of well-known kind carrying a nozzle m and a stopper m at its bottom portion, the said stopper being-controlled by a' handle m in the usual manner. The ladle M has trunnions m,- which may be connected with supports from cranes or other devices adapted to move the. ladle from the melting furnaces and from place to place as required. \Vhen in position for use, the ladle M delivers the molten metal to a secondary or transferring ladle N, which in turn pours the metal into the molds quietly, thereby avoiding the considerable splashing and consequent cutting and scabbing which would occur in teeming the relatively shallow horizontal mold chambers direct from the nozzle m of the primary ladle. This secondary ladle N is shown having a central basin or receptacle n for the molten metal and two relatively large lips or spouts a, one on each side, by which the molten metal may be poured gently but quickly into the mold, thereby preventing the formation of scabs and cold shuts in the relatively long mold chamber, which would occur if the usual stream of metal were employed. The ladle N is pivotally mounted, as indicated'at 0, the pivots being located midway between the ends of the ladle. It will be noted that the ladle N may be intermittently or continuously supplied with metal from the ladle M. The ladle N should be operated so as to supply a mold on one side of the apparatus while a mold of the adjacent series is being moved into teeming position. For this purpose various means may be employed for tilting the ladle N; the devices illustrated are simple and eflicient. As shown, there is a disk P carrying an eccentrically-arranged pin go, which is connected by a rod 17' with the under side of the ladle at p The disk P is carried on a shaft Q, mounted in suitable bearings and connected by a chain R with a sprocket wheel 1- on ashaft 1". This shaft 1 carries another sprocket wheel which is connected by a chain S to a sprocket wheel on the power shaft C. In operation. as the disk P revolves, the ladle N Will be tilted first in one direction and then in the other so as at the proper times to supply the molten metal to the molds.

When the molds, which are firmly and evenly seated upon the, conveyor in order to assure of uniform thickness throughout the horizontal length of the ingot, are filled to the desired depth. they are carried beneath a cover T. which is employed to conserve the heat of the forming ingots in their upper portions in order that the cooling and solidification of the metal may progress from the bottom towards the top substantially uniformly throughout its mass, thus producing slab ingots free from localized shrinkage cavities. Preferably the cover consists of an iron frame t in which are mounted sections of heat-insulating material t, silica brick for instance. This cover should be arranged sufficiently high above the molds to allow them to pass without interference, but should be so located as to conserve the heat of the upper portions of the solidifying ingots for the reasons above specified.

By the time that a mold reaches the end of the mold conveyor, the ingot contained therein is entirely solidified and is sufiiciently cooled to retain its shape, andit may be discharged on to a transfer conveyor U of the desired construction, which is driven by a motor U of suitable type.

Figure 4 shows one of the ingots I dropping on the roll conveyor U, which may be operated so as to carry the ingots in either direction-to a reheating furnace in one direction or to a place of deposit in another direction.

InFigure 1, I have shown diagrammatically a heating furnace V to which the ingots are delivered.

After the molds are emptied, they pass through a tank W supplied with water for cooling the molds and putting them into proper thermal condition for the casting of another ingot. The inlet for the cooling fluid is indicated at w andthe outlet at '20. It will beunderstood, of course, that the molds can be cooled by any other means. The molds should also be slurried to prevent the molten metal of the ingot from fusing and sticking to the mold chamber walls. Some types of slurry, lime for instance, may be mixed in the cooling water, or the chamber walls may be treated by spraying or other methods of application.

Preliminary to teeming the molds, the cover T is preferably preheated sufficiently to prevent the cooling, and insofar as possible the oxidizing. of the upper face of the ingot, so that solidification of the ingot will necessarily progress from the bottom upwardly. For this purpose gas, oil or other suitable fuel may be introduced at t or the cover may be heated in any other manner.

Various sizes and contours of horizontal molds may obviously be employed. In Fig ures 6 and 7 are illustrated two cross sections of molds, each mold having a slab ingot forming chamber, the bottom wall of which is much thicker than the side walls and thus more absorptive of the heat of ingot meta-l cast therein. for the purposes explained in my patent before referred to. The side walls of the mold chamber gradually decrease in thickness from bottom to top and are inclined upwardly and outwardly so that the ingots are readily discharged therefrom.

chamber, the upper face of the ingot being the last to solidify. This is accomplished by the method and apparatus as described and illustrated.

In order to insure of homogeneous ingot structure, it is essential that the metal cast in the molds is de-gasified as well as may be at the present state of the art. This is preferably accomplished by adding a. sufiicient quantity of aluminum, ferro-silicon or similar deoxidizer to the bath of molten metal in the primary ladle.

It will be understood that by my method and apparatus for direct casting of slabs numerous economies are effected. Not only is the capacity of the plant employing this invention greatly increased by the lessened operations and rolling passes necessary in the reduction to finished products, but the saving in initial equipment cost is tremendous, since the need for stripping apparatus, soaking pits and break-down or blooming mills is obviated.

I claim as my invention:

1. The'method hereinbefore described of producing a slab ingot from molten well deoxidized steel in a horizontally arranged shallow mold which consists in absorbing heat from the lower middle portion of the molten metal in the mold more rapidly than from the side portions thereof and thus cooling and solidifying the molten metal gradually upwardly and in applying heat in a downward direction upon the upper side only of the molten metal to thus retard the solidification of the metal in its upper side while the body portion of the metal is being cooled and solidified.

2. The method hereinbefore described of producing slab ingots from molten well deoxidized steel in a series of horizontally arranged shallow molds which consists in absorbing heat from the lower middle portions of the molten metal in the molds more rapidly than from the side portions thereof and thus cooling and solidifying the molten metal gradually upwardly and in applying heat in a downward direction upon the upper sides only of the molten metal to thus retard the solidification of the metal on their upper sides while the bottom'portions of the metal are being cooled and solidified.

3. Apparatus for producing a slab ingot from'molten well deoxidized steel com rising a shallow metal mold which is thlcker and thus more heat absorptive through its central middle section than through its vertical side walls, and a heater arranged wholly above the top of the mold and constructed and arranged to transmit heat downwardly upon the upper surface of the molten metal to thus retard the cooling and solidification of the said upper surface while the body por- 13051 of the metal is being cooled and solidi- 4. An apparatus for producing slab ingots from molten well deoxidized steel comprising a series of shallow metal molds each of which is thicker and thus more heat absorptive throughout its central longitudinal section than through its vertical side walls, and a heater arranged wholly above the tops of the molds and constructed and arranged to.

transmit heat downwardly upon the upper surfaces of the molten metal to thus retard the cooling and solidification of the said upper surfaces while the body portions of the metal are being cooled and solidified.

5. Apparatus for producing slab ingots from molten Well deoxidized steel comprising a series of horizontally arranged molds each of which is thicker and more heat absorptive in its middle bottom portion than in its vertical side portions, a heater arranged wholly above the tops of the molds and constructed and arranged to transmit heat downwardly upon the upper surfaces of the molten metal, means for heating said heater before the molds are filled, means for moving the metal filled molds beneath the heater while the metal is being cooled and solidified and for withdrawing the metal filled molds from beneath the heater when the metal has completely solidified.

6. An apparatus for producing slab ingots from molten well deoxidized steel comprising a series of horizontally arranged shallow metal molds each of which is thicker and more heat absorptive in its middle bottom portion than in its vertical side portions, which latter gradually decrease in thickness upwardly, a heater arranged wholly above the tops of the molds and constructed and arranged to i transmit heat downwardly upon the upper surfaces of the molten metal, means for heating said heater before the molds are filled, means for moving the metal filled molds beneath the heater while the metal in the molds is being cooled and solidified and for withdrawing the metal filled molds from beneath the heater when the metal has completely solidified.

7. An apparatus for producing slab ingots from molten steel comprising a series of shallow-chamber metal molds, each of which chambers is of less depth through its central longitudinal section than through its ad acent longitudinal sections, and a heater arranged wholly above the top of the molds and constructed to transmit heat downwardly upon the upper surfaces of the molten metal to thus retard the cooling and solidification of said upper surfaces while the interior portions of the metal are being cooled and solidlfied from the bottom upwardly.

In testimony whereof, I have scribed my name.

EMIL GATHMANN.

hereunto sub-

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