US3038219A - Method and means for high capacity direct casting of molten metal - Google Patents

Description

June-12, 1962 E. B. HUDSON 3,038,219

METHOD AND MEANS FOR HIGH CAPACITY DIRECT CASTING OF MQLTEN METAL.

.Filed July 2, 1958 3 Sheets-Sheet 1 1y@ wmf- NV-f" BY @4% ATTORNEYS.

June 12, 1962 l E. B. HUDSON 3,038,219

METHOD AND vMEANS FOR HIGH CAPACITY DIRECT CASTING OF' MOLTEN METAL Filed July 2, 1958 3 Sheets-Sheet 2 INVENTOR. fbw/A/ Hansa/v,

AT TORN EYS.

E. B. HUDSON METHOD AND MEANS FOR HIGH CAPACITY June 12, 1962 DIRECT CASTING OF' MOLTEN METAL 5 Sheets-Sheet 5 Filed July 2, 1958 INVENTOR. "W//v .5. Hausa/v, .wfg

ATTORNEYS.

United States Patent O M Ohio Filed July 2, 1953, Ser. No. 746,116 '7 Claims. (Cl. 22-57.5)

My invention relates to the direct casting of molten metal `and more particularly to the direct casting of ferrous metals by procedures and apparatus which permit extremely high tonnage production.

Hitherto many types of direct casting machines have been proposed, all of which are of relatively small capacity and unsuitable for high tonnage production. In Europe `attempts have been made to develop multistrand machines, whereas the American and Canadian practice has been to use single-strand machines, but all of them operate at relatively low speeds. The use of either single or multistrand machines as heretofore known also have the serious disa-dvantage that for each size of slab produced, a die for that size slab is required. In other words,

if the machine is set-up to cast lslabs having a 4 Width, the entire cast must be made through the 40 die since the ysize of the die cannot be changed .during the casting operation. If the mill has need for an entire cast of 40 slabs, no difliculty is encountered, but in many instances the production schedule of the mill is such that a full cast of 40 slabs is not required, in which event the remaining slabs must be cooled and stored for use at a later time. The problem of proper scheduling of work in a mill is an acute one in that the right size slab must be chosen for each job. For this reason mills which roll from conventional ingots will cast as many as twelve different ingot sizes so that the proper slab size may be obtained for a given job. In this connection, it may be observed that the length of the slabs will also vary depending upon the ingot weight.v That is, a large percentage of slabs formed from conventional ingots will be shorter than the maximum length of the lslabs which can be accommodated by the slab furnaces preceding the hot strip mill. Consequently, the heating capacity of the furnaces is seriously reduced in that the furnaces will not be at all times heating slabs having the maximum length which can be accommodated.

With the foregoing in mind, one of the principal objects of the instant invention is to utilize a single die size to cast an entire heat and yet from which any width slab can be cut to suit the requirement of the mill. In accordance with the invention, the width of the cast slab will be equal to the maximum length of slab that can be heated in the slab furnaces preceding the mill. For example, should the slab heating furnaces accommodate a 26-0" long slab, then a slab cast in accordance with my invention Will have a width of 26'-0. Thus for a 300 N. T. heat, a `slab which is 26h-10'l wide and having a thickness of 61/2, will have a length of `approximately 87-0". As this initial slab is formed and the metal solidified suciently to `be self sustaining, it is severed transversely of its length to provide individual slabs of the desired dimensions. Thus, as the continuous slab is formed, it can be severed transversely at intervals of 40., 50" or 60, depending upon the number of 40, 50" or 60" width slabs required. It will be understood that subsequent to the transverse severance of the continuous slab into individual slabs, the individual slabs will be fed into the slab furnaces with the 26-0" width of the original slab becoming the long dimension or length of the severed slab. It should be vapparent from the foregoing that the procedure just described permits the continuous production of slabs varying in ultimate width from the maximum 3,38,2l9 Patented ,lune 12, 1962 to the minimum capable of being handled by a mill and also increases the heating capacity of the slab furnaces in that all slabs Iare of the maximum length capable of being handled by the furnaces.

A further object of the invention is the provision of apparatus capable of carrying out the procedure just described, `said apparatus comprising essentially a vertical casting machine which delivers the cast slab to a horizontally disposed conveyor where the slab is delivered to a cutting `station at which gang cutting torches cut the slab to the desired unit widths.

Still a further object of my invention is the provision of a casting machine particularly suited to the carrying out of the foregoing objects of this invention, said machine incorporating improved end dams incorporating refractory areas which control the freezing of the molten metal so as to prevent folding of the metal when passing through the casting rolls.

The foregoing together with other objects of the inven tion which will appear hereinafter or which will be apparent to the skilled worker in the art upon reading these specifications, I accomplish by that construction and arrangement of parts and those procedures of which I shall now describe an exemplary embodiment.

Reference is now made to the accompanying drawings wherein:

FIGURE l is a plan view of a direct casting machine in accordance with my invention. Y

FIGURE 2 4is a side elevational view of the machine taken along the line 2 2 of FIGURE l.

FIGURE 3 is a plan view diagrammatically illustrating the manner in which a cast is severed transversely into slabs of the desired dimensions.

FIGURE 4 is an enlarged vertical sectional view taken through the casting rolls.

FIGURE 5 is an elevational View of an end dam constructed in accordance with the invention.

FIGURE 6 is an end elevational view of the end dam.

FIGURE 7 is a vertical sectional view taken along the line 7-7 of FIGURE 5.

Referring first to FIGURES l and 2'of the drawings, l have therein illustrated a direct casting device comprising a pair of main casting rolls l arranged on parallel horizontal axes and so mounted that the distance between their peripheries defines an opening 2 at their line of nearest approach. The convergent space between the `upper halves of the rolls is formed into a molten metal pool by end dams 3 bearing against the surfaces of the rolls. A supply of molten metal introduced into the pool from an overhead ladle 4 will llow downwardly between the rolls where it will begin to solidify and pass downwardly between spaced guide members 5, the metal moving between the guide members until it has cooled suiciently to form a supporting skin.

As seen in FIGURE l, the rolls l are driven through meshing gears 6 one of which also meshes with a pinion '7 secured to shaft S which, in turn, is driven by spur gear 9 and motor pinion Ill secured to the drive shafts of a motor unit (not shown). `The rolls ll are water cooled, being supplied with water through conduits l1. Discharge water from the rolls is passed through conduits lla at'the opposite ends of the rolls, and the discharge water may be thereafter utilized to spray the cast sheet after it leaves the machine to further cool its skin. As

best seen in FIGURE 4, the rolls l. are provided with with their curved side edges l spaced from the surfaces of the rolls 1 by a uniform distance equal to one-half the thickness of the slab being cast. Contact areas 16 are thus provided; and the molten metal will make direct contact with the copper faces of the end dams 3 in the Contact areas. The refractory inserts f4 prevent freezing of the molten metal in the areas of the inserts, and hence freezing of the molten metal will occur only along the marginal contacting areas 16. This arrangement prevents the freezing of the total side area of the molten metal, which would canse folding of the metal as it passes through the rolls 1. By permitting the molten metal to freeze only in the marginal contact areas 16-each of which is one-half the thickness of the slab being castthe two frozen areas will come together in line contact as the initial slab is formed between the rolls.

It will be understood, of course, that as the slab 17 passes between the cooling rolls l, a frozen skin 12%*18 is formed, and this skin will be supported by the closely spaced guides 5 until the skin 18a-18 is of sufticient strength to prevent ballooning and render the slab selfsustaining.

As best seen in FIGURES 5, 6 and 7, the end dams will be provided with conduits 19 through which water or other coolant will be supplied to internal passageways 20 in the dams, the coolant being discharged from the dams through exit conduits 21. If desired, the discharge water also may be utilized to spray the continuous slab after it leaves the machine. The end dams are also provided with inlets 22 through which a suitable lubricant may be introduced at the interface of the end dams and the rolls 1.

The material forming the refractory 14 does not constitute a limitation on the invention and diverse materials may be employed. It is also within the spirit of the invention.to incorporate heating means within the refractory areas to assure against freezing of the molten metal coming in contact with the refractory areas. If desired, the refractories each may be provided with a nose or wedge shaped projection 23 to counteract the tendency of the molten metal to retreat upwardly out of the pressure zone between the casting rolls.

Referring again to FIGURES l and 2, the cast slab 17, while initially formed in a vertical position, is conveyed in a curved path and delivered to a horizontal conveyor 24 for subsequent severance into the desired slab sizes. To accomplish this, the cast slab is conveyed in a curved path on a conveyor 25 having a radius of at least 25 feet. Coacting with the conveyor 2S are lowering chains 26 which may be conveniently driven by a gear motor 27 mounted on the transverse girder 28. When starting the cast, a bait (not shown) is positioned between the casting rolls 1 and moved downwardly by dogs 26a on the lowering chains, thereby leading the forward edge of the slab in a curved path along the conveyor 19. At the beginning of .a cast, the direction of movement of the chains is reversed to bring the dogs between the guides 5 to support the cold slab used as a bait. After the dogs have controlled the speed of the descending slab, the chain is stopped, with the dogs at approximately the position shown, thereby freeing the cast slab for continued movement on the conveyor. As the forward end of the slab moves into a horizontal plane, it is passed between flattening or bending rolls 29, the lower roll 29a being driven by gear 30 and pinion 31 on drive shaft 32. The upper rolls may be conveniently backed by rolls 33 supported from girder 28 which also mounts the gear motor for the lowering chains 26.

The cast slab 17 is cut into individual slabs of the desired dimensions by means of gang cutting torches 34 which are suspended from overhead girder 35, the girder mounting suitable motor driven mechanism to move the cutting torches in synchronism with the cast slab as the individual slabs are being cut. A stop gage 36, which is adjustable, is provided to establish the desired widths of the individual slabs. Hold-up magnets 37 are arranged to d hold the uncut slab above the slab pile 38; and suitable means will be provided to remove the slabs from pile 38 to a position where the individual slabs may be reached by an overhead crane. In FIGURE 3, I have illustrated a cast slab 17 having lines of cut 39 serving to divide the cast slab into individual slab units 40 which, as should now be apparent, may be of any desired width. The cast slab illustrated is for a 300 N. T. heat and has a thickness of 61/2.

As already mentioned, the discharge water from the casting rolls 2 and the end dams 3 may be utilized to cool the cast slab. As seen in FIGURES 1 and 2, a series of sprays 41 may be provided for these purposes, the sprays illustrated being located between the bending rolls and the cut-off torches.

The apparatus and procedure just described provides a high yield of cast metal, reduces the slab cost, and the flexibility for providing various slab widths is unlimited. A slab cross-section 26-0 x 61/2 has area of slightly above 14 sq. ft., which accounts for the high casting rate of up to 450` N. T. H. or approximately 40 minutes for a 30() N. T. heat. It will be understood, of course, that the iigures given are exemplary only, and do not constitute a limitation upon the invention.

Having thus described the invention in an exemplary embodiment, and with the understanding that modifications may be made in the invention without departing from the spirit of it, what I desire to secure and protect by Letters Patent is:

l. In apparatus for the direct casting of molten metal, a pair of horizontally disposed coacting casting rolls, end dams at opposite ends of said rolls, said end dams and said rolls coacting to define a pool for receiving molten metal, said end dams each having a generally triangular refractory area the apex of which extends between said casting rolls and the adjacent side edges of which -are spaced from the adjoining casting roll by a distance of substantially one-half the distance between the peripheries of said casting rolls at their line of nearest approach, means for cooling the areas of the end dams between the said edges of the refractories and the peripheries of the casting rolls, whereby freezing of the molten metal will occur only along the said areas, guide means positioned immediately beneath the said casting rolls for receiving and supporting a continuous slab as it is formed upon the passage of the molten metal between the casting rolls, conveyor means lying beyond said guide means for moving the slab in a curved path, slab lowering means coacting with said conveyor means to move the slab in said curved path, and means for severing the slab into individual slabs, said last named means being movable relative to said conveyor.

2. For use in apparatus for the direct casting of molten metal wherein the metal is passed between a pair of casting rolls, end dams adapted to coact with the casting rolls to provide a pool for receiving molten metal, said end dams being of generally triangular configuration and having edge surfaces following the contour of the casting rolls and in substantial contact therewith, the inner surfaces of said end dams having generally triangular refractory inserts the apices of which project between the casting rolls with the adjacent side edges of the inserts spaced from the roll contacting surfaces of -the dams by a distance of substantially one-half the distance be- -tween the peripheries of the casting rolls at their line of nearest approach, whereby to provide marginal contact areas between `the refractory inserts and the roll con- -tacting edges of the dams, said inserts being effective tovprevent freezing of the molten metal in the areas of the inserts, with freezing occurring only along the said marginal contact areas.

3. The structure claimed in claim 2 wherein said end dams are formed of copper, and have internal cooling passageways elfective to cool said marginal contact areas.

4. In a direct casting apparatus, a pair of casting rolls positioned to form a sizing pass, and reservoir means located on and in contact with said casting rolls -above said pass, Isaid reservoir means comprising metallic end dams of generally triangular configuration, with adjacent edges shaped to follow the contour of said casting uolls, the inner surfaces of said end dams being provided with refractory inserts two side edges .of which are `spaced uniformly from the peripheries of the casting rolls to deiine marginal contact areas therebetween, whereby to prevent freezing of the molten met-al in the area of the refractory inserts but not in the marginal contact areas.

5. The device claimed in claim 4 wherein said marginal contact areas are each of a width which is substantially one-half the width of the pass.

6. In apparatus for the continuous direct casting of an entire heat of molten ferrous metal, a pair of horizontally disposed co-acting casting rolls defining a pass therebetween, end `dams -at the opposite ends of said rolls positioned above yand entering between said rolls, the facing surf-aces of said end dams each having a generally triangular refractory insert the apex of which extends between said casting rolls Iand the adjacent side edges of which are spaced from the adjoining casting roll by a distance .of substantially one-half the distance between the peripheries of said casting rolls at their line of nearest approach, the facing surfaces of said end dams and said casting rolls co-acting to define a pool overlying the pass of ysaid rrolls for receiving molten metal, means for cooling said casting rolls, means for cooling the areas of said end dams between the edges of the refractory inserts and the peripheries of said casting rolls, and means positioned immediately beneath the said casting rolls for 6 receiving and advancing a continuous slab of ferrous metal as it is formed upon passage of the molten metal between said casting rolls.

7. A method for the `direct casting of molten meta-l into slabs, which comprises casting a heat of molten metal by introducing it into a die -the front and rear walls of which converge downwardly toward a pass and the end walls of which define the opposite Iside edges of the slab being cast, whereby molten metal in contact with the end walls of the die must converge as it approaches said pass, controlling the freezing of the molten metal in contact with the end walls of the die so 4as to permit freezing to occur 4only along marginal a'reas of said end walls adjacent the front and rear walls of lthe die, said marginal tareas having a combined width equal to the thickness of the slab being cast, and bringing the two frozen marginal areas together in substantially line contact as the slab is formed.

References Cited in the file of this patent UNITED STATES PATENTS 1,841,715 Cone Jan. 19, 1932 2,127,515 Hazelett Aug. 23, 1938 2,640,235 Hazelett June 2, 1953 2,698,467 Tarquinee et al .l an. 4, 11955 2,790,216 Hunter Apr. 30, 1957 2,799,065 Whitaker July 16, 1957 FOREIGN PATENTS 441,118 Great Britain Oct. 20, 1934 1,090,019 France Oct. l13, 1954

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