US2067192A - Process for tensioned cold rolling in reversible mills - Google Patents

Description

E. B. HUDSON Jan. 12, 1937.

PROCESS FOR TENSIONED COLD ROLLING IN REVERSIBLE MILLS Original Filed May 10, 1954 INVENTOR EIJW/N 5 Hausa/v.

ATTORNEYS.

Patented Jan 12, 1937 PROCESS FOR TENSIONED COLD ROLLING 1N REVERSIBLE MILLS Edwin B. Hudson, Middletown, Ohio, assignor-to I The American Rolling Mill Company, Middletown, Ohio, a corporation of Ohio Original application May 10, 1934, Serial No..

724,931. Divided and this application January 23, 1935, Serial No. 3,129 1 I 5 Claims. (01. 80-60) This is a division of my application Serial No. 724,931 filed May 10, 1934 for Apparatus and process for tensioned cold rolling in reversible mills.

It has hitherto been attempted to roll strip material of sheet width in reversible mills, usually of the four-high type, and also to apply considerable tension to the strip as it is being so rolled. Single stand mills of this general type ordinary plant may represent as much as $50,000 loss per year. a

The general objects of my invention are, to provide rolling apparatus of the reversible mill type capable of rolling thin metal gauge strips in larger quantities than is possible with the type of equipment hitherto in use; to provide a' mill and associated apparatus which is economical in first cost and very economical in operating cost; to providefor the rolling of coils of metal'which greatly exceed the length of "the strip sheets furnished by the hot mill, and usually will be from ten to fifteen times as long,

- whereby thelength of the coils furnished by the hot mill is not determinative of the length of the coils supplied to the cold mill; to provide means to insure the rolling of the greatest amount of strip with the minimum of scrap loss; to provide a way of eliminating unrolled portions of the strip or strip sheet; to provide means for permitting a greater surface speed of rolling; and to provide a system in which the portions of the strip being rolled may be maintained con-- tinuously under a predetermined constant tension so as to insure constant gauge reduction, and

so as to maintain the stress in the strip safely below the breakingstress. My objects also include the provision of processes to the ends hereinabove set forth. 1

In a co-pending application entitled Process 5 and mechanism for rolling endless lengths of metal in reversible mills, Serial No. 741,133, filed August 23,-1934, I have set forth a method of rolling strips of endless lengths involving the have certain disadvantages in operation, howsegregation of a given portion of an endless strip ever. They are limited in the production of tonfor rolling purposes, and the rolling of this strip nage, due primarily to conditions imposed by the backwardly and forwardly through a reversible hot mills upon which the strip sheets are made. mill or series of mills until it is reduced to the These hot mills are able to turn out only relatlvedesired gauge. When this has been accomly short coils, the usual length beingabout three plished the rolled portion of the strip is payed out,

hundred to four hundred feet. These short coils and an additional portion is segregated for rollmake it necessary tooperate at relatively slow ing purposes. In this way. the end scrap loss is speeds, at least on the early passes.' Another eliminated. In my present case I do not keep disadvantage of short coils is that the length of the strip in an endless length during the rolling the strip sheet used up in fastening the strip operation, but segregate a portion of it by 'sever- 20 sheet to the drums on either side of the mill ing that portion from the endless supply. In this amounts to a very considerable length of metal way I do, away with the necessity of apparatus as compared with the length of the coils emfor taking up unsevered lengths of the strip on ployed. This metal cannot be rolled because it either side of the mill, and can thereby reduce cannot be caused to enter the mill; and as a the quantity of apparatus necessary and the 25 consequence, it has to be either discarded or overall space taken up by the apparatus in genmade into some other product; These unrolled eral. But in this case I have also provided means ends, together with strip degraded by cobbles and a method whereby the production of unrolled and breakage, amount usually to around three ends of the strip is eliminated, and scrap loss hundred pounds perton of metal, and in the from this source is avoided. 30

Essentially in the practice of my invention, I take the strip sheets produced on the hot mill and weld successive strip sheets end to end until I have accumulated a large quantity of stock for rolling. This large quantity of stock, usually in the form of a coil of metal say'of 25,000 lbs. in weight or more, is then passed through a reversible mill or series of mills backwardly and .forwardly until it is reduced to gauge. On either side of the mill I p'rovide'means for maintaining in the strip constantly a predetermined tension of constant amount, and I also provide tensioning means and means in the nature of coiling means at either-side of the mill or mills,'to take upthe strip during rolling as it is fed through the mills. In this way I produce at each operation of the mill a length of strip weighing say 25,000

lbs. or more, which has been completely reduced to gauge excepting for a relatively short portion at one end thereof as distinguished from unrolled portions at both ends-of the strip in previous attempts to roll strip sheets on the reversible mill. Moreover, upon the succeeding operation of my mill this unrolled portion at the trailing end of the preceding strip is now ing have advantages other than higher tonnage.

Lower mill screw pressures may be used, and the strip work hardens at a slower rate, dueto the temperature developed in the strip by cold working at a very rapid rate. The strip has less time to radiate its developed heat between the various passes, or between the pass and the coiling point, so that the strip enters the following pass or passes at a higher temperature. This aids in its reduction. I

These various objects of my invention, and others which will be set forth hereinafter, or will be apparent to one skilled in the art upon reading these specifications, I accomplish by that certain construction and arrangement of parts and in that process of which I shall hereinafter set forth an exemplary embodiment. To facilitate a disclosure of this embodiment, reference is now made to the accompanying drawing, wherein Figure 1 is a'plan view of a single stand reversible mill embodying my invention.

Figure 2 is an elevational view thereof, with parts in section.

I have indicated at l a decoiler in which a strip sheet coil 2 may be supported and unwound, the pinch rolls 3 and knee roll 4 serving to decoil and somewhat straighten the metal. The decoile'r isoperatedby a prime mover :and suitable drive indicated generally at 5. The strip next passes to a shear 6, where the leading end thereof maybe squared to facilitate the formation of a. butt-weld joint to the trailing end of a preceding stripl A welder is indicated generally at l, which may be of any suitable type, preferably, though not necessarily, an electrical butt-welder. ,A flash cutter is indicated at 8, the purpose of which is to remove from the weld any portions of themet'al which extend up above the general plane of the surfaces of the strip sheet. Pinch rolls 3 serve either to hold or to pay out the metal. V

By the juncture of succeeding coils to asupply of strip sheet, rollingmaterial is accumulated ,upon'a reel H), which may be driven by a suitable prime mover ll. Ordinarily in the practice of my invention, 1' accumulate upon the .reel I0 a coil of metal weighing 25,000 lbs. or

more, and consisting of one large coil say of 3500 to 4000 feet in length. This coil I have indicated at l2.

Ihaveshown pinch rolls l3 lying beyond the coiler l0, and beyond this a welding device l4, pinch rolls l5, and a flash cutter Hi. In this groop of apparatus a shear may be included, if

desired. Beyond the flash cutter I 6 I have shown a supporting roll H and a table i8. p I have next shown a type of coiling device which I refer. to as a friction coiler. This comprises a smooth drum IS with means for driving it, which will hereinafter be described, and a flexible outer sheath memberof chain form comprising rollers 20 and interconnecting links 2|. This outer sheath is supported at one end by a pivoted member 22, and is caught at its other end by cables 23 which pass over drums- 24 on a shaft 25. This shaft bears at its end another drum 26, to which a cable 21 is attached. A weight 28 is fastened on the end of the cable.

The operation of this weight is to tighten up on the sheath member which, since its other end is fastened to the pivoted member 22, is able to conform to the surface of coils of varying size upon the drum I9.

I have shown a-deflector or the function of which is to guide the end of a strip into the friction coiler. The strip may be thought of as coming into the coilerfrom the right in Figure 2. When the coiler is empty,

guide member 361" the sheath member comprising elements 20 and 2| encircles the drum l9, and the action of the deflector 36 is to lead into this cradle the end of the sheet, so as to wrap it about the drum I9. Thereafter the sheath functions to keep the strip tightly wrapped about the drum, irrespective of the si'zeof the coiler. The deflector member 36 may be actuated in any way desired, either manually orautomatically, as by means of a fluid pressure cylinder with suitable controls.

The next piece of apparatus is a continuous pulling device comprising pinch rolls 29 and 30, and a series of rolls 3| which are arranged in staggered relationship, and aboutwhich the strip passes sinuously. The purpose of the pinch rolls 29 and 30 is to keep the-strip tightly in contact with the rolls 3!, which are rolled through a suitable gearing indicated generally at 32 and 33 from a prime mover 34. These rolls therefore exert a tension upon the strip as it passes through. them, as will be readily understood, and

this device, which I'shall hereinafter refer to as acontinuous puller, is of a type set forth in my oo-pending application Serial No. 668,100, filed April 26, 1933.

I have shown the shaft I90. of the drum of the friction coiler driven by a belt 35 from a pulley driven by the prime mover 34. This particular drive is, of course, not essential, but I have indicateddt as setting forth a type of slip drive to compensate for changes in surface speed due to the growth or diminishing of a coil of metal in the friction coiler, as will be well understood.

The last roll 31 of the continuous pulling device, serves also as one of the knee rolls of a static tension applying device. The other knee roll is indicated at 38, and a pull roll 39 is also shown mounted on a bearing member 40 which operates in ways 4| in the framework support ing the aforesaid rolls. In the particular embodiment illustrated, the strip indicated at 42 is shown passing under the knee rolls 3? and 38, and over the pull roll 39, although this particular method of threading is not a limitation upon my invention. The roll 39 is urged upwardly by the action of a hydraulic cylinder indicated at 43, connected by a conduit 44 to a hydraulic accumulator 45. This accumulator can be loaded in such a way as to cause the pull roll 33 to exert a continuous force upon the strip 42. If, due to sporadic changes in rolling conditions, the strip 42 becomes shortened or elongated in that portion of it which extends between the, continucomprising rolls 31, 38, and 39 (which I shall hereinafter refer' to as a static tension take-up device) may be caused to control the speed either of the continuous puller hereinabcve described,

or of the mill hereinafter to be described. The

operation of the static tension take-up device and the general features which go to make up its 'construction, are set forth more in detail in my copending application entitled Rolling under tension, referred to hereinabove.

The strip 62 nextis carried to a mill shown in the drawing and comprising housings 46 and working rolls 41. While this is not a limitation upon my invention, yet, for the purpose of making drastic cold rolling reductions; and more particularly for rolling strip sheets into thin gauge metal, such as tin plate, I prefer to use small working rolls '41. The small working rolls, of course, are backed up by larger rolls 48, and the type of. mill I have shown in my drawing is known as thefour-high mill. The mill will be driven in any suitable manner, and in this type of mechanical organization will be of the reversible type, normally, since in reducingmetal to thin gauges, more than one pass through the rolls is desired. Normally the mill and the rolling operations will-be so adjusted as to reduce the strip sheet to. finished gauge in three or five passes.

The number of passes will preferably be uneven, since it will be desired to deliver the finished pieces on the side opposite to the side of its entry into the mill. I have shown but one rolling mill; but it will be clear that more than one or a train of cold mills, may be employed if desired.

Upon leaving the mill the strip goes through another static tension take-up device comprising appropriate framework,- knee rolls 49, and a pull roll 50, preferably actuated in the same way as heretofore described, by a hydraulic cylinder connected by a conduit 52 to an accumulator 53. I have shown in my drawing. a pump 54 feeding both accumulators. It will be understood that I may use other means than a hydraulic cylinder for actuating the pull rolls of my static tension take-up devices, such as a system of cables and weights, for example.

While, beyond the static tension take-up device just referred to, it would be practicable to place another continuous puller and a reeling device or other take-up means, to which tensioning power does not have to be applied, and while this is within the scope of my invention, yet I have not found it necessary to do this, and prefer for economys sake to employ a type of tight coiler.-

Inasmuch as the operation of my mill is to be as efiicient from point of time as possible, I provide mechanisms indicated respectively at 59 and 60..

a tight coiler device of a type permitting an already formed coil to be unwound and removed while anew coil is being wound up under tension. Consequently, I have shown a base55 upon which I pivot, by means of a shaft 56, a pair of arms 51 and 58 forming a cradle for two tight, coiling This cradle can be swung about by means of a small motor 6|, and through a suitable drive fl, so as to position the driving head 63 of either of the tight coiling mechanisms in alignment with a clutch member 64-. In Figure 1 a tight coiler spindle 59 is shown as connected by the clutch 64 to a shaft 65 which is driven by a motor 66 through suitable gears 61. Ordinarily in the operation of my system, the first static tension take-up device will be caused to control the speed of the mill motor, and the second static'tenslon take-up device will be caused to control the speed of the tight coiler; the speed of the continuous puller shown in Figures 1 and 2 being the fundamental basis for the controlled speeds of the other dynamic instrumentalities in the train. The second static tension take-up device therefore acts to maintain constant tension in spite of sporadic variations in the operation of the final tight coiler. Since the final tight coiler is controlled in speed by the static tension take-up device, the power applied to the tight coiler is caused to vary in accordance with the diameter of the coil of metal formed on the tight coiler spindle. I have shown a coil 68 being wound up on the tight coiler spindle 59 while a coil 69 is being removed from the spindle 60 and coiled upon a spindle mechanism as at 10, to form a package of the metal suitable for shipment or storage. It will be understood, of course, that instead of forming a coil as at 10, the reduced strip may be end to form a'large coil [2. Atthe start of all operations of the metal, an end of this coil is led through the continuous puller and the static tension device, then through the mill, through the next static'tension device, and to the tight coiler to which the end thereof is afilxed. The mechanism is started in. operation and strip rolled to very near its trailing end, leaving always willcient of the metal to be caught by the pinch rolls 29 and 30. The deflector 36 is next dropped and the mill and other associated instrumentalities reversed, whereupon the strip moves in the opposite direction, and as it is fed through the pinch rolls 29 and 30, winds upon the tight coiler l9 to form a. coil which I have indicated at l I. The strip in this way is rolled until near its leading end, leaving a portion, however, long enough to extend from the mill to the final tight coiler. In. this way the piece is rolled backwardly and forwardly a. sufiicient number of times to bring about the desired reductionin gauge. During the rolling operation it is taken up alternately either upon the final tight coiler or'upon the initial friction coiler When the,piece' has been reduced to gauge; it being assumed that the piece is finished by a forward pass inthe mills, its trailing end will extend sufiiciently to be caughtwith the pinch rolls 29 and and the greater portion of the length .of the strip will be wound upon thetight coiler 59 to form the coil 68. The strip will be clamped ahead ofthls coil and cut off, whereupon the cradle formed by the arms 51 and 58 will be rotated to bring the now empty tight coiler spindle 60 into position to be operatively connected with the driving shaft 65 by the clutch other purpose; but end losswill not occur again in the operation of this system for reasons which will hereinafter be described. That is to say, after the rolling of the initial batch of material, no more end scrap loss will be encountered until it is necessary, for some reason or other, to dethread the material or to take the system down for repairs or replacements.

The next step will be to weld the trailing end of the strip extending through the rolls 29 and 30, to the leading end of a new supply of rolling material which, it will be understood, has been accumulated in the meantime upon the reel l2. This welding is done by means of the device I.

' tinuous puller and the tight coiler act on suc-- .ceeding passes respectively as brakes and pullers,

of a supply of rolling material of great length and weight, formed by thewelding together in the end of a plurality of strip sheets from the hot mills; second, the forward and reverse roll- I ing of a preceding supply already so formed; and

third, the recoiling or cutting apart into sheets of an already rolled supply of material.

. During the course of the rolling, the continuous puller upon one side of the mill and the tight coiler upon the other side of the mill, act to. exert tension upon the strip, which tension is of material assistance in rolling. By the use of tension I do not primarily refer to such minor amounts of tension as are useful in feeding the mill or mills and in reducing camber. Rather I prefer to use heavy tensions such as facilitate the reduction of the metal by the cold mill's. The tension produced by the continuous puller and the tight coiler is maintained at a constant value by the static tension take-up devices, which act continuously to make the tension constant in spite of variations in the length of the strip between the several dynamic instrumentalitiesfand to control the speeds of these instrumentalities if variations greater than normal or accumulative variations occur. It will be clear that the conand vice versa.

Modifications may be made in my invention without departing fromthe spirit thereof. 3

Having thus'described my invention, what I claim as new and desireto secure by Letters Patent, is:- e

1. A quasi-continuous process of rolling metal in ,strip' form to eliminate end wastage, which comprises providing a strip of metal of definite as' distingiiished from indefinite length, fixing the ends thereof with respect to take up devices,

rolling substantially said whole strip forwardly and backwardly through a mill until reduced to the desired gauge, severing a useful rolled por tion of said strip forwardly of said mill, uniting to the unrolled portion of said strip behind said mill a succeeding strip of definite length, fixing the ends of the new supply thus formed with respect to the. take up devices, and proceeding with j the. rolling operation as before, all without rethreading said mill.

2. The process of claim 1 in which the rolling is carried on under tension.

3. A quasi-continuous processof rolling metal under tension in strip form to eliminate end wastage, which comprises rolling a strip of metal of definite length forwardly and backwardly in a mill, to the desired gauge, severing a rolled portion thereof forwardly of the mill, and without re-threading the mill, attaching the end of another strip of definite length to the unrolled end of the preceding striprearwardly of the mill so as to form a new supply for rolling, which supply is of definite as distinguished from indefinite length, attaching the end of said supply extending forwardly through said mill to a tensioning device, running the said supply backwardly of said mill through a reversible pulling device, and providing accumulating means for the said supply rearwardly of said mill and pulling device, which accumulating means is not required to exert the rollingtension on the said supply, and proceeding with the rolling operation as before.

4. A quasi-continuous process of rolling metal to eliminate end wastage which comprises pro-" viding a metal strip for rolling, which strip is of definiteas distinguished from indefinite length, passing said strip through a puller, a tension rolling a strip of metal of long, but definite as distinguished from indefinite length forwardly and backwardly in a reversible mill until reduced to gauge and until the rolled portion of said strip forwardly of the mill is accumulated upon a coiler, joining strips of metal together to form another such long strip of definite length, joining the end of said last mentioned long strip to the un-rolled end of said first mentioned long strip rearwardly of the mill, continuing the rolling as aforesaid, and decoiling the rolled portion of said first mentioned long strip, all without re-threading said mill and substantiallyas concurrent operations whereby said rolling. process need be interrupted only for the length of time it takes to join one long strip to the next.

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