US1865443A - Method and apparatus for continuous casting of steel billets - Google Patents

Description

July 5, 1932. J. E. PERRY ET AL 1,365,443

METHOD AND APPARATUS FOR CONTINUOUS CASTING OF STEEL BILLETS Filed Nov. 6, 1928 3 Sheets-Sheet 1 l N i I 1 ENTORS 70/171 1?- erry a d e r-ge Ramwey ATTORNEY July 5, 1932. J. E. PERRY ET AL METHOD AND APPARATUS FOR CONTINUOUS CASTING OF STEEL BILLETS 3 Sheets-Sheet 2 Filed NOV. 6, 1928 wil Z a T8 N .m

y m d Wh Y M July 5, 1932. J. E. PERRY ET AL 1,865,443

METHOD AND APPARATUS FOR CONTINUOUS CASTING OF STEEL BILLETS Filed NOV. 6, 1928 3 Sheets-Sheet 3 llllllll I 6/15 74 1 AIR oak H72}? A INVENTORS Jo/zn E1 Perry and gl orge Ravzwey ATTORNEY Patented July 5, 1932 mart-.51)v STATES JOHN E. PERRY, 0F YOUNGSTOWN, OHIO AND GEORGE PATENT OFFICE N EW YORK Application filed November 6, 1828. Serial No. 317,510.

The present invention relates broadly to metallurgy and more especially to the continuous casting of billets of steel or the like directly from molten metal.

eretofore in the art it has been customary in the manufacture of steel to cast the steel as the ingots in ingot molds; strip the molds from the ingot; place the ingots in a soaking pit for reheating; and then to subject the ingots to the blooming mill to secure blooms Whlch are eventually rolled or worked into the final shape. It is well recognized in the art that for the production of the best ingots, the ingot molds should be poured while hot and at a predetermined temperature. If the ingot molds are too cold, bad crystallization results in the ingot, and if the molds are too hot, the ingot will stick to the mold. Furthermore, it has been recognized in the art that it may be desirable to apply pressure to the steel during the final freezing of the ingot in order to compress the same and obviate flaws in the ingot. This method while producing high grade steel is expen sive and therefore is not generally resorted to for ordinary steel products.

he present invention obviates the difliculties of the known prior art by providing a method and mechanism whereby the molten steel is cast by a continuous operation into the steel billets or blooms properly shaped for direct working by rolling mills which may be either continuous; or the continuous steel billet or bloom from the casting machine may be sheared into desired lengths and rolled as individual units where desired; or the metalshape may be cast into final form,

- 1n which case no reworking is contemplated.

More especially, the present invention relates to a continuous casting machine in which the casting molds are maintained at a predetermined temperature and wherein the rate of operation of the machine may be controlled by the operator as desired and also wherein pressure may be applied in accordance with the desires of the operator to the steel while freezing into the desired shapes. From the foregoing, it will be observed that the present invention obviates the necessity for ingot molds, for the stripping mechanism, for the soaking pit, for the blooming mill and for the operations and loss by cropping commonly practiced in connection with the manufacture of steel by the ingot mold method; and form the rolling also eliminated.

Other and further objects of the present invention will in part be obvious and will in where the shape is in final is or forging operations are part be pointed out hereinafter in the specifico Referring now to the drawings, Fig. 1 illustrates a view of the front portion of a casting machine in accordance with the present invention wherein certain parts of the device 75 are shown in section to more clearly illustrate the same.

Fig. 2 illustrates the rear portion of the same machine partly shown in Fig. 1, together with diagrammatic representations of rolling 80 mills and heating furnaces adapted for operation on the billet as it leaves the machine.

Fig. 3 is a sectional view on line 33 of Fig. 1.

Fig. 4: and Fig. 5 are detail views of the 86 raising and lowering mechanism for applying pressure to the upper mold members to subject the continuous billet or bloom to pressure during the freezing of the steel.

Referring now more especially to Figs. 1 90 and 2, which in fact should be considered as one large figure, the continuous casting machine comprises a series of open ended molds 1 linked together by suitable connections 2 so arranged as to permit a slight endwise movement between the molds whereby there is no ossibility of the molds being held apart by inding at the joints of 'the connections. These molds form a continuous chain which is slightly inclined to the horizontal with the in the limiting sense.

front end 'of the apparatus being slightly of steel rmits the rater of the machine I higher than the rearend thereof. he upper to regu ate the s of the machine and run of this continuous chain of molds is supported upon supportingtrolls 4 which are ro-.

tated by the drive sha 5 that is connected with the main drive gear 6 through a gear 7 and this drive gear 5 1s operatively connected with the rolls 4 b bevelled gears 8 and 9. At the rear end of the machine, the molds 1 pass around an idler wheel 10 and are 'ded in this passage around the idler wheel y a pair of cams 11 which engage the roller pins 12 (see the slab as would Fig. 3) of the connectors 2 between the molds, in such manner that the molds drop away from the continuous slab A without the corner of the mold bein raised upwardly against the case if the molds were forced to travel tangent to a circular path. After the molds have passed around the idler wheel 10, the molds are again supported by'supporting rolls 14 which likewise are rotated by a lower driving shaft 15 which carries bevelled gears 16 that connect with bevelled gears 17 on the axles of the supporting rolls 14. This lower driving shaft receives the driving power through the stub shaft 18 which carries a gear 19 that meshes with the main drivin gear 6 and also a bevelled gear 20 that mes es with a bevelled gear 21 on the lower driving shaft 15. At the front end of the machine, the continuous mold chain passes around the main driving wheel 22 which is mounted on the main shaft 24 that carries the main drive gear 6 and which main shaft receives its driving power from a variable speed electric motor 25 through the driving shaft- 26 that carries a driving worm gear 27. that engages the main driving ar28 on the shaft 24. The control box 29 or the variable speed motor 25 is located conveniently to an operatin handle 30 for the stop r of a ladle 31 whic brings the molten steefio the casting machine and discharges the same into a spout 32. 1

This spout 32 is in the form of a trough which is illustrated as being deeper at the outlet end than at the other end. This permits the stream of steel from the ladle to enter thetrough or spout and form a pool having a low head of molten steel which permits a gentle stream of steel to fall on the pool or surface B in the machine. It furthermore permits slag which may come from the ladle to rise to the top of the pool in the trough so that this slag may be skimmed ofi if desired by the operator. This pool in the trough preferably shall be .of suflicient size to perm1t the steel to become quiescent so that the stream of steel from the trough is quiescent molten steel as it enters the machine. This trough may be supported by chains or other convenient supports whereby the trough may be cleaned or relined as. desired. This convement location of the control box for the motor and the control handle for the stream the speed of pouring in such manner as to maintain a harmonious action between these two variables. Mold caps 34 are arranged in a continuous chain above a portion of the upper run of the mold chain and pass at one end over a driving-wheel 35 and at the other end over an idler wheel 36. The upper run of the mold caps is supported b driven rolls 37 that are driven from a drive s aft 38 which carries bevelled gears 39 that mesh with bevelled gears 40 mounted on the rolls 37.

This driving shaft. 38 receives its power through a gear 41 that en 42 on the driving wheel s aft 44. This drivin gear42 receives its power from the'main drive gear 6 through a drive shaft 45 which carries a gear 46 on one end that meshes with the main drive gear 6 and another gear 47 at the other end which meshes with the driv. ing gear 42. The lower run of the continuous ca chain asses beneath a'series of pressure to $48 which may or, may not be driven as is desirable and whose main function is to apply pressure to the back of the cap members to force the same downwardly into the molds as the cap chain progresses in its travel over the mold chain. These pressure rolls 48 are mounted in adjustable bearings 49 carried by the main frame 50 and are provided with adjusting devices which may comprise shafts 51 carrying hand wheels 52 and with the shafts 51 carrying gears 54 that mesh with ages adriving gear bevelled gears 55 on the upper ends of presto the mold caps 34. It

beneath the upper run of the continuous mold chain and also the pressure rolls 48 above the mold caps are so constructed that at all times at least two rolls are effective to support a mold or depress a cap, as the case may be, and thereby obviate any irregular movement to these parts. It will also be observed that the direction of application of power to both the molds and the mold caps is endwise from the front end of the machine toward the rear thereby closely pressing together the individual continuous chain members so that thereisno tendency ofthesteel to leak through these respective chains. The operation of the device is that of a continuously moving horizontal mold with a finished cast billet or bloom A, leaving the machine at the rear end .with the molten steed from the ladle 31 pouring into' the machine at the other end. The

the joints between the individual members of.

with the bottom of the mold chain adjacent thefront end of the machine and. with the bottom faces of the caps adjacent the front place at the ly illustrated tinuous rolling mills run of the caps. When the machine is first started in operation, it is desirable to prevent the steel from flowing directly through the molds and beneath the caps and therefore, a dam 57 is dropped into the mold chain and is of such height as to substantially seal the mold from side to side and up to and in contact with the mold caps so that the molten steel builds up on one side of this dam and is chilled as it passes through the machine, thereby forming a frozen end on the initial portion of the continuous steel billet which permits the machine to start into operation. After an operation has been begun, the machine may be operated continuously by bringing up one ladle after another of molten steel and this operation may be continued as long as the operator desires. If, however, the operator prefers to separate different heats of furnaces, dams 57 may bedropped in end of each furnace run and thereby divide the continuous billets into sections, each of which represents one furnace run.

As the continuous steel billet A leaves the casting machine, it may be desirable to utilize edging rolls 58 to slightly shape the edges of the billet and surfacing rolls 59 which surface the billet and also bring the continuous run of the billet from the slight incline of the machine to a horizontal. These rolls 58 and 59 also clean the billetor bloom A of scale and surface material that may be present on the cast steel. It is common in the art to sprinkle salt or water on the hot steel to remove this surface scale and this may be done before the hot cast steel reaches these rolls 58 and 59. The scale however, in the present process is in most cases likely to be very slight because the molds are thoroughly cleaned after leaving the casting run of the mold chain, and before coming up for a new casting operation.

A pair of flying shears 60 diagrammaticalin Fig. 2 may be provided where it is desirable to separate the continuous billet into individual lengths for subsequent treatment. Flying shears are well known in the art and are constructed to move with the metal'during the cutting operation so that metal may be out while in motion without interrupting the movement of the metal. Feed rolls 61 may also be provided to support and carry forward the billet to suitable rolling mills. Preferably, though not necessarily, the present machine is adaptable for use with methods of continuous rolling and where desired, continuous heating furnaces 62 and 64 may be arranged adjacent the conand 66. These heating furnaces are illustrated as being electrically heated, but it is obvious that such other furnaces, as are well known in the art for this purpose, may be utilized and may be heated 4 in any manner Well known in the art.

may comprise suitable heat control devices which may be located at convenient places on the machine and preferably comprise a substantially enclosed casing 67 with the top thereof open and located beneath the lower run of the mold chain in such manner as to enclose two sets of temperature control members, one may comprise gas burners 68 and the other may comprise conduits 69 adapted to convey a cooling medium such as air or water. These temperature control devices may be operated where the molds are not maintained sufiiciently hot by the molten steel, the furnace may be utilized to raise the temperature of the molds, and Where there is a tendency for either gas or air may be sprayed over the molds to cool the same. A similar arrangement is preferably provided over the upper the molds to run too hot, then run of the cap chain and may comprise a series of gas burners 70 and aseries of cooling pipes 71, which as previously explained, may carry either water or air or other suitable cooling fluid. By this arrangement, the temperature of the molds may be brought up to and maintained at such a level as is best adapted for the work done,'both when the machine is started and thereof.

Preferably, though not necessarily, .cleaning devices such as brushes or as illustrated, a spray nozzle 72 and a drip trough 74 are provided adjacent the rear of the machine for the purpose of cleaning the mold from scale or any other foreign substances which may tend to collect thereon, and adjacent the front of the machine are also provided another spray nozzle 75 and a drip pan 76 whereby the molds may be treated with any coating material such as tar or other ma terials which may be desirable to facilitate the casting operations. Like cleaning devices such as brushes or spray and coating nozzles may also be provided for the cap chain whenever and wherever such devices are desired.

It is to be understood that the gear-ratios are such that the rate of speed of travel of the mold members shall be exactly the same as the rate of speed of travel of the cap members whereby no torsional forces are exerted on the shape of steel in the machine.

From the foregolng, it'will be observed during continuous operation that in the operation of the machines, the molds and caps are first brought up to the desired temperature, then the dam 57 is dro ped into place and the machine started 5 so t at the mold and ca run is toward the rear of the machine as in icated by the arrows in Fig. 2, and the stream of molten steel from the ladle 31 is ermitted to fall into the s ut 32 and bull up a pool of molten steel, which fills the space between the mold members and the caps. The speed of pouring and of travel of the molds and the caps ismaintained in such manner that the surface B of the molten steel remains substantially stationary adjacent the front end of the machine while the steel is being carried away by the molds and caps. As the steel is carried away fromthe surface of the pool, the steel immediately begins to freeze and the length of the mold chain and cap chain is such that the steel is completel frozen before it leaves the machine. This reezing operation initially takes place in the form of frozen steel which gradually encloses a wedge-shaped zone of molten steel that disappears into a solid frozen steel billet before the billet leaves the machine. In order to compress the frozen steel, the pressure rollers on the cap members are so adjusted as to sub- 30 ject the steel, before it is finally frozen and shortly thereafter, to a substantial pressure which squeezes the crystals together without destroying the crystalline structure and permits any occluded gases or other materials which might form cavities, to be squeezed out into the molten steel and escape from the surface B of the pool without leaving any flaws in the solid frozen billet A as it leaves the machine. Furthermore, it will be observed that impurities which tend to segregate in the freezing process are so quickly trapped because the traveling mass of steel is freezing both above and below that these materials which ordinarily tend to segregate in'the ingot mold processes of the prior art do not have an opportunity to segregate and are therefore evenly distributed throughout the steel billet. The billet leaves the casting machine with a high residual heat and may pass through an equalizing furnace 62 before coming to the first rolling mill 65, and after passing this rolling mill 65 the steel may again be reheated if desired by a second heating furnace 65. This method, therefore, conserves the initial heat from the molten steel and at the same time maintains the steel billet in exactly the right temperature condition for subsequent rolling operations.

It is also to be understood that the cross section of the space between the molds and the caps which determines the cross section of the billet A, while being specifically illus- P trated as substantially a rectangular cross sectlon, is to be shaped'in such manner as to thorough interlocking impart a cross section to the continuous billet which cross section is best adapted for rolling the particular finished article which is being made by the rolling mills, and where desired the cross section may be that of the final shape in which case no further working or shaping of the continuous steel shape is necessary.

In the method of making metal shapes as carried out according to our invention, the metal shape while freezing in the machine is subjected to pressure sufiicient to cause a of the columnar crystals whereby there is no tendency of any weak spot being formed anywhere in the metal s ape after the freezingis com leted. The columnar crystals are interloc ed in such manner as to greatly increase the tensile strength of the metal in all directions whereby the shape leaving the machine has substantially uniform tensile strength both longitudinally, transversely, and in fact, all directions.

This method also contemplates the direct production of final metal shapes without the necessity of subjecting these shapes to 1'6; working by rolling or forging, as has heretofore been common in the art with relation to billets made by the ingot mold process.

Furthermore, by this method, pressure is applied to the metal during the freezing thereof in such manner as to resist the normal tendency of metal to expand when freezing, thereby obviating any ruptures to the shape at this time and furthermore permitting the internal forces in the metal to be relieved toward and into the molten metal pool which is continually being fed forward into thechilling or freezing zone. This completely obviates segregation or separation of the various metallurgical contents which go into the final metal shape and consequently so distributes these contents in the final shape as to greatly increase the quality of the final shape from the standpoints of density, lack of internal flaws, and increased characteristics as to tensile strength.

Furthermore, by the present method of controlling the initial temperatures of the mold members and caps the character of the crystallization is controlled and a further element in this control is the factor of being able to adjust and control the speed of the machine, which will lengthen or shorten the conical or crater-like zone of molten metal extending into the freezing envelope or crater-like form at the molten end of the shape. The present method, therefore, contemplates controlling the temperature of the mold members, controlling the effective speed of the mold members with relation to the freezing of the molten metal and applying pressure circumferentially to the shape at critical periods or zones during the freezing of the molten metal into the solid shape.

In the present method, pressure is applied 1,sea,44a

in the direction of the growth of the columnar crystals, and in view of the' fact that these crystals grow at t angles to the chilled surfaces into sm er shapes where the maximum thickness or diameter of the shape is less than twice the length of the columnar crystals from any one surface, the present method brings these columnar crystals to ether at their inner ends and interlocks the same so that the sha is of substantially the same crystallization throughout. This action is brought about by several factors, comprising the present method, namely, the controlling of the temperature of the molds and caps which controls crystallization, the application of pressure during the freezing action and the rate of travel of the machine which is under the control of the operator.

It is particularly desirable in accordance with the present invention that the molds and caps shall be of such size and at such temperature as to produce the exact desired chill to form the character of crystals desired and it is to be understood that where the mold side walls are relatively thin to produce this efiect supporting rolls (not shown) may be placed adjacent the sides of the mold at the point where hea internal pressure is exerted on the mol so that these side walls may be thoroughly supported in order to prevent any cracking or reaking of the mold members.

While the present invention has been disclosed more with reference to the steel art, it is to be clearly understood that it is equally adaptable to other metals such as copper, brass, and other alloys or metals.

While the present invention has been specifically referred to in connection with the manufacture of steel billets, it is to be understood that this machine is equally adaptable for use with other metals and may even be utilized for other urposes.

It is to be un erstood clearly that the drawings herewith are for the sole purpose of illustrating the invention and that in practice many of the parts would be larger and heavier than the proportions illustrated in these drawings.

Having described our invention, we claim:

1. A machine for the continuous casting of a metal shape comprising in combination an endless travelling chain of open molds, an endless travelling chain of mold closures adapted to enter into and close the top of said open molds, variable speed driving means for moving said molds and said closures at predetermined rates, and means for controlling the temperature of said molds and said closures.

2. A machine for the continuous casting of metal shapes comprising in combination a .continuous series of molds, capping means for said molds, variable speed devices to move said molds and capping means at a predetermmed rate, coohng means for said molds and said cap ing means, and heating means for said mol s and ca ing means whereby the temperature of em molds and capping means may be controlled.

3. A machine for the continuous casting of metal shapes comprising in combination a continuous series of open molds, a continuous series of capping means entering into and closing the tops of riable speed driving means whereby the rate of travel of said molds and capping means may be controlled relative to the rate of pouring molten metal into said molds.

4. A machine for the continuous casting of metal shapes adapted for reworking comprising in combination an endless series of open molds, an endless series of capping members adapted to enter into and close a portion of said open molds, driving means to drive said series of molds and series of capping members, and adjustable means for applylng pressure under control of the operator to said capping members to force said members into said molds whereby the pressure upon metallic shape may be controlled at the will of the operator.

5. A machine for the continuous casting of metal shapes comprising a continuous series of open molds, a continuous series of cappin members extending into a portion of said open molds and being adapted to close the same, and adjustable pressure means operable upon said capping members to control the depth to which said capping members are adapted to extend into said open mold members' whereby the pressure upon the metallic shape while in the molds may be controlled.

6. A machine for the continuous casting of metal shapes comprising a series of mold members, a series of cappin members for said mold members, means or controlling the heat of said mold members and capping members, and adjustable means to apply pressure to the metal shape in said molds during the time when the molten metal is being frozen in said molds.

7. The method of continuously casting shapes from molten metal comprising forming a stream thereof with a horizontal pool of molten metal at one end of the stream, progressively withdrawing heat from all sides of the stream beyond the pool at such a rate that the foot of the stream is solidified metal while the head of the stream is substantially molten metal and with a wedge shaped molten central portion extending from the pool toward the solidified metal, applying pressure to the stream adjacent to the termlnation of the molten portion, adding molten metal to the head of the stream, and controlling the rate of withdrawal of heat from the stream according to the rate at which molten meal is added to the head of the stream to maintain the said open molds, and vamolten portion of the stream substantially constant.

8. The method of casting shapes from molten steel comprising sup lyin molten steel to chill mold members a apte to withdraw heat circumferentially from the mass of steel, passing said mold members through a temperature control zone to control the temperature of said members, and applying pressure to said mass during freezing thereof at substantially right angles to the chill faces of said mold, whereby pressure is applied in the direction of the growth of columnar crystals in said shape.

JOHN E. PERRY. GEORGE RAMSEY.

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