US2145593A

US2145593A - Method and apparatus for making metal strip

Info

Publication number: US2145593A
Application number: US103950A
Authority: US
Inventors: Kirtland C Gardner
Original assignee: United Engineering and Foundry Co
Current assignee: United Engineering and Foundry Co
Priority date: 1936-10-03
Filing date: 1936-10-03
Publication date: 1939-01-31
Anticipated expiration: 1956-01-31

Description

km. 31, 1939. K. c. GARDNER METHOD AND APPARATUS FOR MAKING METAL STRIP Filed 0.0L 3 1936 4 Sheets-Sheet .l

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K. C. GARDNER METHOD AND APPARATUS FOR MAKING METAL STRIP Jan. 31, 1939.

Filed Oct. 3, 1936 4 Sheets-Sheet 2 INVENTOR.

ATTORNEYf- R u l m w I I l l I I l I l I ll w m n! i LT v w n .E T N Jan. 31, 1939. K. c. GARDNER METHOD AND APPARATUS FOR MAKING METAL STRIP Filed 001:. 5, 1936 4 Sheets-Sheet 3 mi). Adi {4.41

WITNESSES Jan. 31,

1939. K, c GARDNER 2,145,593

METHOD AND APPARATUS; FOR MAKING METAL STRIP Filed :11. 3, 1956 4 Sheets-Sheet 4 Mm J2 1 41 5 5 It 58 15 [I i a w I I l 1,, 1 I/ I 5Q. 1 5.69,; 'lll'l 1|] ,M ,mm

In: 1 FIJ'K 11 40-- E tr-40 i l 5 58 mrywim ATTORNEYJ- Patented Jan. 31, 1939 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR MAKING METAL STRIP Application October 3, 1936, Serial No. 103,950

21 Claims.

This invention relates to the making of metal blanks and slabs and, more particularly, is concerned with apparatus and methods for the commercial manufacture of steel strip.

It is inconvenient and metallurgically very difficult to cast ingots wide enough to produce wide sheets and strips without cross rolling. The maximum ingot width which is considered practical is in the neighborhood of 65 inches, and sheets and strip are required to widths approaching 100 inches. Heretofore, these wide sheets-and strip have been produced by rolling an ingot not over 65 inches wide into a slab approximately 60 inches wide, shearing the slab, reheating it, rolling it broadside to the desired width, and then rolling itlongitudinally to the desired thickness. This method of rolling requires that the slabs be broadside rolled after reheating, which means that they cannot be longer than can be handled by a roll of practical length; in other words, they are practically limited to some 8 feet in length, and for broadsiding a very large and expensive mill must be provided, which has no other function except to give perhaps a single pass of very short duration. Another disadvantage of this method is that the time required for broadsiding after reheating could very much better be used in elongating the slab, since the usual requirement is to reduce these slabs to quite thin material and to perform this operation quickly because finishing at a suitable temperature is quite important.

It will be appreciated that these known methods and apparatus for manufacturing metal strip involve tremendous initial and production costs by the very fact that so many different types of mills are required, many of which will be idle during the formation of the strip on the other mills in the operation. In addition, a relatively large number of men are required to control the operation of the various machines, and difficulty is experienced in making the operation of the various mills continuous to improve the efficiency thereof. This is particularly true in the method of making metal strip by first passing the slab through a broadside mill and then through a reversing universal mill in that the broadside mill must remain idle during the entire rough-sheeting operation of the universal mill which, of course, means high investment embodied in the broadside mill which is yielding no continuous return.

The object of my invention is to avoid and overcome the foregoing and other difficulties of prior known methods and apparatus for the manufacture of metal blanks and slabs by the provision of improved means and methods which are adapted to reduce or spread the ingot to the desired width before rolling to the desired blank or slab thickness. Another object of my invention is to provide processes and apparatus for reducing a slab 5 or even an ingot to rough-sheet or strip form entirely in a single mechanism so that there will be no idle apparatus during any part of a strip-forming process. A more specific object of the invention is to provide a single reversing mill which 10 combines the functions of a broadside mill and a rough-sheet mill.

My invention is predicated upon my discovery that the features of a broadside mill and a universal reversing type of rough-sheet mill can be combined in a single mill wherein strip can be rolled in a single continuous process from a slab. More broadly I have found that an ingot can be spread by cross rolling to provide an ingot of a width reater than 65 inches which then can be rolled longitudinally to a slab of a width greater than 65 inches and of desired thickness thereby eliminating, if desired, the usual slabbing operations. The advantages of this method are that in producing the slab there is abundant heat, as the total time or" rolling and the final thickness of the slab are such as to leave no anxiety as to the finishing temperature. Another advantage is that, having spread the ingot, the slab is of the desired width when leaving the slabbing mill and can be A cut to any length convenient for reheating or can be passed directly into the finishing mill if the final product is sufficiently thick to permit finish rolling on the initial heat.

The improved apparatus of my invention briefly comprises a combined broadside mill and roughsheet mill upon which both of the operations performed on these mills can readily and continuously be performed. The horizontally journaled rolls of the combination mill are of suficient width to make one or more broadside passes on either (1) an ingot or (2) the slab pieces cut from an ordinary ingot slab, with the pieces being then passed lengthwise through the same horizontal rolls which then function as a rough-sheet mill. Vertically journalled edging rolls are adjustably associated with the horizontal rolls and these are moved to engage with the edges of the slab piece during the rough-sheeting operation but are positioned during the broadside pass beyond the ends of the slab piece.

In the practice of the broad method of my invention I may work directly from a hot ingot by cross rolling it to spread it to a desired width. The ingot is then rolled longitudinally to a slab of the desired thickness which can be handled further in any of the usual ways to produce a desired product, such as metal strip. Second, I may start with a slab produced in standard fashion which is reheated and passed broadside through horizontal rolls which engage the top and bottom of the piece to form it to width. One or more passes may, of course, be taken in a broadside direction to achieve this result. Edging rolls are adiustably positioned beyond the ends of the slabpiece during the broadside pass so that the full Width of the horizontal rolls can be utilized if necessary in the broadside pass. The piece is then turned lengthwise and passed through the horizontal rolls which are periodically reversed, with the requisite number of passes being taken to form the slab to the desired thickness. The vertical edging rolls are moved to contact the edges of the slab piece during the lengthwise rolling of the slab piece and these rolls control the width of the strip produced.

Apparatus which may be used in the practice of my invention, as just explained, is illustrated in the accompanying drawings, of which Fig. 1 is a diagrammatic plan view of the arrangement of one embodiment of my improved combination mill and associated apparatus; Fig. 1a is a diagrammatic plan view of a portion of Fig. 1 and illustrates a modification of the invention; Fig. 2 is an enlarged plan view of the rolling mill illustrated diagrammatically in Fig. 1; Fig. 3 is a longitudinal vertical cross-sectional view taken on line III-III of Fig. 2 and shows details of the mill structure; Fig. 4 is a transverse vertical sectional view taken on line IV--IV of Fig. 2 and indicates structure of the edging rolls; Fig. 5 is a sectional view taken on line VV of Fig. 4 and illustrates the construction of the supporting rollers positioned between the edging rolls; and Fig. 6 is a view similar to Fig. 2 but of a modification of my invention.

General assembly of apparatus The arrangement of the apparatus of my improved strip-rolling equipment is illustrated diagrammatically in Fig. 1, in which the numeral l0 indicates generally a conveyor having rollers reversibly driven by motors I3, which conveyor extends on both sides of the combination mill shown generally at I2. Associated with the conveyor ID are furnaces l4 which are adapted to receive ingots or slabs (hereinafter called metal blanks wherever either ingots, slabs or the like are intended to be included). The furnaces I4 function to reheat the blanks and to deposit them in turn upon the conveyor l0 through the operation of suitable magazine pushers 5 associated with the furnaces M. The conveyor ill feedsthe blanks in turn to the mill l2 and, after the broadside and sheet-roughing passes, the conveyor carries the strip to any equipment adapted to perform the finishing operations thereon. In the embodiment of the invention illustrated, the rough sheet or strip is carried by the conveyor ID to a coiler, indicated generally by the numeral H, which coils the strip in known manner with the strip being then transferred to any apparatus to have the final operations performed thereon. However, as seen in Fig. 1a, the strip-finishing equipment may include a continuous or tandem mill i8 for cold or hot-rolling the strip to final dimensions with or without reheating or annealing. The tandem mills 48 of this modification are placed along the conveyor in in place of the coiler i! as will be understood.

Horizontal roll stand Referring to Figs. 2 and 3, which illustrate in greater detail the construction of the combination mill H, a housing 20 having four corner columns journals, in bearing structure of standard design and adjustability, a pair of work-engaging rolls 2| of relatively small diameter but of a length suflicient to make a broadside pass on the metal blanks and to receive the widest strip to be rolled. The diameter of the rolls 2| is kept as small as possible to obtain lengthening rather than compressing and widening of the material worked during the rolling operation. The work-engaging rolls 2| are backed by supporting rolls 22 which are likewise journaled, in bearing structure of standard design and adjustability, in the housing frame 20. Suitable means, such as motor 25 and drive mechanism 26, are employed to drive the various working rolls. The motor 25 is adapted to be periodically reversed by known means to form the so-called universal or reversing type of mill.

Slab pushers Associated with the combination mill are suitable pushers for moving the metal blanks broadside into the rolls 2|. These means may take a number of forms but are preferably of such character that they can be moved out of the way during the lengthwise rolling operation and yet can be readily brought into play to positively move the blank broadside into the mill. As best seen in Fig. 3, these means comprise, in the form of the invention illustrated, arms 30 pivotally mounted at 3| upon suitable carriages 32 which are moved toward and from the roll stand by the provision of rack and gear mechanism indicated by the numeral 33 and operable by a prime mover (not shown) Similar pushing mechanism is provided on each side of the roll stand.

Edging rolls Positioned on each side of the horizontal rolls 2| and 22 are vertically journaled edging rolls 40. These edging rolls are mounted so that they can be positioned beyond the ends of the horizontal rolls during the broadside pass, and so that they can be readily brought into engagement with the edges of the rough sheet or the slab piece during the lengthwise rolling thereof to exactly control the width of the strip. This function is achieved, in the particular form of the invention illustrated, by providing a frame 4| at each side of the horizontal rolls with the frame extending transversely of the conveyor l0. Each frame 4| is adapted to slidably carry a pair of boxes 42 each of which journals a stud shaft 43 upon which an edging roll 40 is keyed. A gear 44 is also keyed on the stud shaft 43 and this gear is driven by a gear 45 secured to the shaft 46 and likewise journaled in the housing. The shaft 46 has a bevel gear 41 secured to its lower end. Todrive the bevel gear 41 and thus the edging roll 40, a drive shaft 50 is journaled at its ends in the frame 4| and is formed with a splined length which carries a bevel gear 5| which engages with the bevel gear angle pass.

gear 56 and adjust the housings l2 inwardly or outwardly of the frame II. The worm 51 is driven by any suitable prime mover, such as motor 58, controlled by the mill operator.

In operating strictly on ingots the edging rolls are preferably moved somewhat away from the horizontal rolls so that the turntables (hereinafter described) can be positioned between the edging rolls and the horizontal rolls, all as illustrated in Fig. 6. Since the parts in Fig. 6 are similar to those of Fig. 2, although differently positioned, they have been indicated by like numerals.

Conveyor between edging rolls Rollers for supporting the metal blank between the edging rolls are provided, and these rollers are preferably automatically adjusted so that, regardless of the distance between the edging rolls, the blank is properly supported. In the embodiment of the invention illustrated, the supporting rollers are carried on shafts I driven by motors 15. The shafts 10 are journaled at their ends in the frame 4| and supported near their middle portions by a bearing H carried on a transverse bar,

12 formed on the frame ll. Bearings 14 for the shaft 10 are likewise formed on theends of the housings 42 and these bearings not only receive the shaft 10 but likewise journal a sleeve 16 having flanged ends, one of which comprises a roller I1 and the other a flange 13. Thus while the sleeves I6 can rotate in and move longitudinally of the bearings M the flanged ends prevent the sleeves from moving out of the bearings. The sleeve 16 and associated roller Tl have a sliding fit on and are driven with the shaft 10. To insure a positive drive, the shaft 10 is polygonal in crosssection and is received in a similar bore in the roller 11 and sleeve F3. Rotary bushings are employed in the bearing II to take care of the polygonal shaft 10. A roller 19 is also preferably provided between the spaced shafts I0, and as shown in Fig. 5 this roller is journaled on bar 12.

In the movement of the edging rolls 40 towards each other the bearings 14 slide over the sleeves 16 until the bearings strike the rollers Tl. Further movement of therolls 40 towards each other carries the rollers 11 inwardly or towards each other until this movement and the inward movement of the rolls 40 is limited by the rollers ll striking the bearings ll. At this time the rolls 40 and the rollers 11 are in the dotted line positions indicated in Fig. 5. Now when the rolls 40 are moved apart, the bearings 14 slide over the sleeves 16 until the bearings 14 engage with the collars 13 on the ends of the sleeves. Further outward or apart movement of the rolls 40' moves the sleeves 1B and rollers 11 away from the bearings II and into a desired adjusted position, as, for example, that shown in full lines in Figs. 4 and 5.

Turntables surface of the rollers H on the conveyor ID to pick up and turn a metal blank to the desired angle to make the broadside, lengthwise or other The tables are then lowered and leave the blank on the conveyor in its new position. When working with blanks in the form of ingots the turntables 80 are preferably placed as close to the combination mill l2 as possible. In the drawings the assembly has been shown for handling blanks in the nature of slab-s although ingots may also be handled.

Operation and process The operation of the apparatus just described and the method of the invention briefly comprise forming a metal blank, heating the blank and running the blank broadside through, the horizontal rolls to form the blank to the desired Width. Themeans driving thehorizontal rolls as well as the conveyor rolls III are periodically reversed so that any requisite number of passes may be made on the blank toform it to the proper Width for rough-sheet rolling, for example. The broadside pass on the blank increases the width of the piece to substantially the width of the rough sheet or strip to be rolled. During the broadside pass the vertical edging rolls are positioned laterally beyond the ends of the blank and even beyond the ends of the horizontal rolls.

After the broadside pass or passes, the blank is turned lengthwise by means of the turntables 80 associated with each side of the horizontal rolls, and the vertical edging rolls are moved inwardly and against the side edges of the blank so that during the rough-sheeting operation the edges of the blank are kept to the proper dimensions by the edging rolls. The blank is now passed back and forth through the reversing horizontal and edging rolls the requisite number of times to form the piece to rough-sheet form of the desired thickness and width. Of course, the horizontal rolls are periodically moved closer together to effect the desired reduction in the thickness of the blank. Likewise, the vertical edging rolls can be adjusted from time to time to obtain the proper width in rough sheet.

The rough sheet may, of course, be of substantially any thickness and may even be termed a. finished product after the rough-sheeting operation, with or without annealing, shearing and edge-trimming operations. However, in the preferred manner of practicing the invention, the rough sheet is passed to the coiler ll, associated with the conveyor l0, and is coiled in known manner prior to further working operations thereon. For example, the coils can be annealed or reheated with subsequent cold or hot-rolling operations thereon to form the sheet or strip to the exact dimensions and characteristics desired. Instead of passing the rough sheet to the coiler II, the invention contemplates passing it directly to the tandem or continuous mill [8 as seen in Fig. la. for finishing operations.

As will be evident, my improved method contemplates working directly from an ingot which is rolled longitudinally to remove the taper but not sufiicient to elongate the ingot beyond the width of the horizontal rolls, cross rolled in horizontal rolls to width, and then rolled longitudinally as above described. Also I may roll the ingot in accordance with standard prior art practice to form a slab, shear the slab into pieces, reheat the pieces and handle the slab pieces by cross rollingto width and then longitudinally rolling on the same mill.

In working directly from an ingot it may be found advantageous to shear the slab produced from the ingot into smaller pieces with subse-' quent reheating before finishing operations in any desired manner, as for example, on the combination mill I2 or on the continuous mill I8. However, if the slab produced from the ingot is of sufiicient size and retains the requisite amount of heat it may be finished without reheating as will be understood.

' Summary From the foregoing description of the method and apparatus particularly disclosed, it will be recognized that a combined broadside and sheetroughing mill has been provided which will function to form strip or sheet of the desired dimensions and characteristics in a rapid, continuous manner. The combination mill involves much less initial investment than the standard installation of a separate broadside mill and separate sheet-roughing mills of the reversing or continuous type. There is no apparatus or separate mill standing idle for considerable periods during the production of rough sheet or strip, and fioor space requirements as well as production costs are likewise reduced. The combination of completely retractible, vertical edging rolls with horizontal rolls sufficiently long to make a broadside pass, and likewise being adapted to reversing sheetroughing operations wherein the vertical edging rolls are moved into contact with the edges of the sheet, constitutes a distinct improvement in strip and sheet-rolling methods because of investment and production savings.

Although the invention has been described as particularly applied to the making of sheet and strip the principles of the invention are broadly applicable to the manufacture of other metal bodies as will be recognized.

While, in accordance with the patent statutes, one embodiment of the apparatus and several Ways of practicing the invention have been illustrated and described in detail, it should be understood that the invention is not limited thereto or thereby but is defined in the appended claims.

I claim:

1. That method of forming strip which comprises rolling an ingot to form a slab, cutting the slab to form a piece adapted to be rolled to strip of the desired width, reheating the slab piece, running the piece broadside through the horizontal rolls of a broadside mill to form the piece to width, turning the rolled piece ninety degrees, adjusting vertical rolls associated with the mill so they engage the sides of the slab piece and the.

horizontal rolls so they engage the top and bottom of the piece, and rolling the piece to strip form of the desired width and thickness by a. reversing operation of the horizontal rolls with periodic reductions in the pass clearance of the horizontal rolls.

2. The method of forming metallic sheet which includes rolling an ingot to form a slab, shearing a piece from the slab, reheating the sheared piece, rolling the sheared piece broadside in a mill to increase the Width of the piece to the desired dimensions, turning the piece and rolling it lengthwise through the same mill, periodically reversing the rolling operation while concurrently reducing the pass in a direction to form a sheet of the desired thickness, and confining and rolling the edges of the piece during the lastnamed rolling operation to obtain a. sheet of the desired width.

3. The method of forming metallic sheet which includes rolling an ingot to form a slab, shearing a piece from the slab, rolling the sheared piece broadside in a mill to increase the width of the piece to the desired dimensions, turning the piece and rolling it lengthwise through the same mill, and confining and rolling the edges of the piece during the last-named rolling operation to obtain a sheet of the desired width.

4. The process of manufacturing steel strip which comprises rolling a steel blank broadside in a broadside mill to increase the width of the blank to more than about inches and then rolling the blank longitudinally in the same mill to provide strip of the desired thickness, maintaining the width of the blank substantially constant during the last-named rolling operation, and passing the strip thus formed directly to a tandem finishing mill.

5. That method of making metal strip which comprises forming a slab by a rolling operation, shearing a piece from the slab, passing the slab piece broadside through a reversing horizontal roll mill having associated vertical edging rolls but with the edging rolls being moved back so as to not interfere with the broadside pass, repeating this pass until the width of the slab piece is of the desired dimension, turning the slab lengthwise and passing the slab piece through the rolls in reversing passes to obtain a strip of the desired thickness, and adjusting the edge rolls to engage the edges of the piece during the strip rolling,

6. That method of making metal strip which comprises forming a slab, shearing a piece from the slab, passing the slab piece broadside through a reversing horizontal roll mill having associated vertical edging rolls but with the edging rolls being moved back so as to not interfere with the broadside pass, repeating this pass until the width of the slab piece is of the desired dimension, turning the slab lengthwise and passing the slab piece through the rolls in reversing passes to obtain a strip of the desired thickness, and

adjusting the edge rolls to engage the edges of the piece during at least part of the strip rolling.

'7. The combination in a single mill of a broadside mill and a rough-sheet mill which includes horizontally journalled rolls of a length suflicient to roll the widest sheet and to receive the broadside pass, vertically journaled rolls for rolling the edges of the sheet during the sheet roughing, means for reversibly driving the rolls, and means adiustably mounting the edging rolls whereby they can be positioned beyond the ends of the horizontal rolls to leave the full width of the rolls accessible for a broadside pass or so they can be positioned within the ends of the horizontal rolls to engage the edges of the sheet during the sheet roughing.

8. The combination in a single mill of horizontal rolls of sufficient length to comprise a broadside mill and adapted to give a broadside pass to a slab, edging rolls for rolling the edges of the slab in the lengthwise pass of the slab to rough form strip, means adjustably mounting the edging rolls whereby they can be moved to the out side of the ends of the horizontal rolls during the broadside pass, and means for reversibly driving the rolls. I

9. That method of forming strip which comprises heating a steel blank, running the blank broadside through the horizontal rolls of a broadside mill to form the blank to width, turning the rolled blank ninety degrees, adjusting vertical rolls so they engage the sides of the blank and the horizontal rolls so they engage the" top and bottom of the blank, and rolling the blank to strip form of the desired width and thickness by a reversing operation of the horizontal rolls with periodic reductions inthe pass clearance of the horizontal rolls.

10. The method of forming metallic sheet which includes heating a metal ingot having a width of less than 65 inches and a length of over 65 inches, rolling the ingot broadside in a mill to increase the width of the ingot to over 65 inches, turning the ingot and rolling it lengthwise through the same mill, periodically reversing the rolling operation while concurrently reducing the pass in a direction to form a sheet of the desired thickness, and confining and rolling the edges of the ingot during the last-named rolling operation to obtain a sheet of the desired width.

11. The method of forming steel sheet which includes rolling a metal blank broadside in a broadside mill to increase the width of the blank to the desired dimensions, turning the blank and rolling it lengthwise through the same mill, and confining and rolling the edges of the blank during the last-named rolling operation to obtain a sheet of the desired width.

12. The method of forming steel members which includes reheating a full-sized steel ingot, rolling the ingot broadside in a broadside mill to increase the width of the ingot to the desired dimensions, turning the ingot and rolling it lengthwise through the same mill, periodically reversing the rolling operation while concurrently reducing the pass in a direction to form a member of the desired thickness, and confining and rolling the edges of the member during the lastnamed rolling operation.

13. The process of manufacturing metal strip which comprises rolling a metal blank broadside in a reversing mill to increase the width of the blank to over about 65 inches, rolling the blank in the same mill to provide strip of the desired thickness, and maintaining the width of the strip substantially constant during the last-named rolling operation.

14. That method of making metal strip which comprises reheating 'an ingot, longitud nally rolling the ingot to remove its taper but not sufiicient to elongate the ingot beyond the width of the horizontal rolls of a reversing broadside mill, passing the ingot broadside through a reversing broadside mill having associated vertical edging rolls but with the edging rolls being moved back so as to not interfere with the broadside pass, repeating this pass until the width of the ingot is of the desired dimension, turning the ingot lengthwise and passing it through the rolls in reversing passes to obtain a strip of the desired thickness, and adjustingthe edge rolls to engage the edges of the strip during the strip rolling.

plane and about a vertical axis, rolling the ingot broadside in the same mill to increase its width to a desired width, turning the ingot through ninety degrees in a horizontal plane and about a vertical axis, rolling the ingot longitudinally in the same mill to produce a blank of the desired thickness, and maintaining the width of the blank as desired during the last-named rolling operation.

1'7, Apparatus for directly rolling a metal ingot into a blank comprising a combined broadside and roughing mill having working rolls on horizontal axes of a length greater than the length of an ingot to be worked whereby the entire ingot can be passed broadside through the mill to increase the width of the ingot to substantially that of the blank to be rough formed, edging rolls on vertical axes positioned adjacent the horizontal rolls for maintaining the width of the blank as desired, and a turntable positioned between the edging rolls and the horizontal rolls for turning the ingot to provide a broadside or a longitudinal rolling operation.

18. Apparatus for directly rolling steel ingots to blanks of desired dimensions comprising a roll stand of a roll length capable of receiving an ingot broadside, a conveyor extending to and from the mill and substantially of the width of the stand, a pusher associated with the stand for moving an ingot into the stand, a turntable on the conveyor in front of the stand and capable of turning the ingot either broadside or longitudinal to the stand, and edging means positioned on both sides of the conveyor and adjustable to and from each other, said edging means being positioned closely adjacent the turntable but not interfering with the operation thereof.

19, In combination, means for rolling a full sized steel ingot either broadside or longitudinally, means for edging the ingot during longitudinal rolling, and means positioned between the edging means and the rolling means for turning the ingot to present itjeither broadside or longitudinally to the rolling means.

20. That method of making a metal blank directly from a full-sized hot steel ingot which includes the steps of longitudinally rolling the in-.

got to remove its taper but without noticeably increasing its length, rolling the complete ingot broadside to increase it to a desired width, and rolling the ingot lengthwise to desired thickness.

21. Apparatus for directly rolling a metal ingot into a blank comprising a combined broadside and roughing mill having working rolls on horizontal axes of a length greater than the length of an ingot to be worked whereby the entire in-