US2370895A - Method and apparatus for rolling strip - Google Patents

Description

March 6, 1945. R. J. WEAN METHOD AND APPARATUS FORROLLING STRIP ,/M NN M Vzw PatentedvMar. 6, I

uNlIEo STATES PATEN'I OFFICE 'METHOD ANn aiignrsusroanomiuo a. Raymond J. Wean, ,Wacrem 0hio, Vassigner Ato -The Wean Engineering Gompany, Inc., Warren, Ollio, a corporation o! Ohio A Application April 28, 1944, Serial No. 533,155

This invention relates to the rolling of metal strip and, in particular, to the cold reduction of strip bypassing it through a plurality of roll stands successively.

Metal strip is commonly reducedto' nal gauge -by cold rolling it progressively in a plurality of 4-high mills or by repeated passes back and forth through a single stand reversing 4-high mill. Tension is usually applied. to the strip as it emerges lfrom the rolls and back tension may also be applied to the strip asl it enters the rolls.. The deformation of the material thus accomplished results from the combined effect of the tension stand of rolls 'and the other side or surface is deformed to an extent greater than the rstmentioned side in passing through a succeeding stand of rolls. I employ a plurality of 3-high roll stands, eaohof which has a middle roll smaller in diameter than the outer rolls. AThe -strip .is

entered between the rollsso that in the first pass, one side of the strip engages the middlel roll and, in the next pass, the other side of the strip engages the middle roll. I also maintain tensionon the strip entering and leavin'g'the mill. By this.method,.I work 'the two sides or surfaces f sclaims. (ci. :so-3s) Journaled therein'.- The rolls of the several stands have their axes substantially in the same vertical-plane. I also provide strip-tensioning means and a coiler on each side of the mill. By this arrangement, the strip may -be passed back and forth through the mill successively until it has been rGeduced to the desired nal gauge.

Further novel features and advantages ofthe invention will becomeapparent during the following complete description and explanation which refer to the accompanying drawing illustrating the apparatus and procedure of a preferred .embodiment and practice. In the drawing,

Figure 1 is a central verticalA section thi-pugna mill and associated apparatus. adapted for carrying out the method of my invention; l

Figure 2 is a sectional view to enlarged scale, through a piece of strip illustrating the reduction produced by passing it through the iirst 3^- high roll stand; and

'Figure 3 is a similar view illustrating the reduction effected o n passing the strip throughthe second stand.

Referring in detail to the drawing, a rolling mill. I0, as illustrated therein, comprises spaced housings II, each having a window I2 adapted to receive bearing .chucks in which are .iournaled the rolls of at least two 3high roll stands. One

S-high stand of rolls includes outer rolls I3 and I4 and a middle roll I5. Another stand includes outer rolls I6 and II and a middle roll I8. The

ofthe strip' alternately and obtain a somewhat angular flow of the metal which results in what I elect to designate angular 11e-orientation. The product of this method, when tested parallel and transverse to the direction lof rolling, ex-

hibits characteristics more nearly equal than the product of conventional rolling methods.

My invention alsohas a specialapplication to the removal of set which is the transverse curvature Vsometimes exhibited 'by cold-rolled withthe concave side 'of the strip in contact Worm wheels disposedv in cases 24 and threaded I on thescrevvs- The chucks of the rolls forming thev upper stand are heldin proper relation by screws 25 actuated bymechanism indicated at 2B, similar to that just described.

The middle 'rolls I5 and Il! of the two B-high stands are quite s al1 compared to the outer .,rolls.' In the illus rated. embodiment,"fr. eicwith the 'smallmiddle v roll whereby that side is deformed more than the otherside, thus-leaving the strip'V in' a nal shape which is more nearly level, I

The apparatus whichl prefer to employ includes a mill comprising a vpair of spaced -housings having a plurlityfof'-hgh roll stands ample.' the -middle rolls have a diameter about one-halfthat of the outer rolls. Whileth'e ratioof the diameters/of the l.middle and outer rolls need not fall within any speciiic limits,v the middle roll should have a diameter which is small conipared [to that of the outer rolls .or,' at least. to',

` l5 theAv diameter vof the outer .roll with which-the the iirst stand. Asclearly shown Y stripiseiected principally strip is in contact. While it is not necessary that the outer rolls of the stands be of the same diameter, this is usuallyconvenient from the operatnaled in spaced housings 32. 'I'he rolls are preferably'arranged to be driven by any suitable means and are also provided with means for applying braking action. The driving and braking may conveniently be combined by providing an electric motor for driving the rolls and utilizing regenerative braking. The coilers 29 and 30 are likewise provided with suitable driving motors and braking means. l

In utilizing the apparatus described above for rolling strip according to the method of my invention, I take-the outer end of a coil of strip 33 disposed, for example, on the mandrel 36 of coiler 29 and pass it around the lower roll 3i ofA tension stand 27, thence between the rolls of said stand and around the upper roll thereof. I then thread the leading end of the strip betweenthe rolls I3 and I5, thence around the roll I3, b E- tween it and the roll I6 and thence around the latter and between it and the roll I8. I then lead the strip around the upper roll of tension stand 28, .between the two rolls thereof and around the bottom roll, and thence to the mandrel of coiler 39.

with the screws 2s and 25 Oadjusted to give the desired drafts on the-strip as it passes between the rolls of the two 3-highstands successively, I drive the coiler 30 and the tension rolls 23. The coiler 33, now serving as an uncoiler, and the rolls of tension stand 27 are retarded to provide the desired tension on the strip entering the irst or lowerstand of reducing rolls.

'Ihe rolls of the two 3high stands are preferablydriven by any suitable means, conveniently by -separate motor drives with speed-controlmeans so that the rolls of the second stand may be driven at a peripheral speedsuilciently greatv er than that of the rolls of the rst stand so as, to

maintain tension on the strip between'the two and anvil, the small roll performing the function of the hammer and the large roll that of the anvil.

eiected. The alternate deformation of the two sides or surfaces of the strip causes angular plastic iiow of the metal resulting in. angular re-y orientation of the grains. This tends t0 prevent thel occurrence of preferred orientation to a marked extent, leaving thematerial with more nearly uniform apparatus. The method of ,my invention apparently results in an angularv displacement oi lsuccessive layers of the original material caused by working each of the two surfaces successively to a greater extent than the opposite surface.v

Thedirection of relative slippage between the several planes is reversed in passing through the two stands successively.

After substantially the full length of the strip in the coil has beenv passed through the two 40 tension on thestrip between` the stands. y strip is again reduced by successive deformations f stands, despite the elongation resulting from the reduction in the rst stand. The tension stand 28 and the coiler 30 maintain lforward tension on the strip emerging from the second stand.

It will he noted that, under th conditions de` scribed, the bottom side or surface of the strip designated S will be engaged by the small or- `middle roll 'of the first stand, while the upper. .side or surface'of the strip will be engaged by the "middle roll of the second stand. This causes the Y two'sidesor surfaces of the strip tobe deformed alternately or,v at least, causes one surface to be deformed much more lthan the other, in `each of the two passes. l diameters of the rolls engaging the strip in each of the twopasses.

Figure 2 illustrates reduction of the strip effected on passing through niFigure 2,

This results from the relative stands, the mill is reversed, as' Well as the func-- tions of the tension stands and the coilers.' The A strip is then 'subjected to a second pass through the two stands successively under tension as described before. It will be evident that the rolls of the lower stand must be driven, on the reverse pass, at a speed higher than that vof the rolls of the upper stand, in order to maintain the desired eiectedfprincipally inthe two sides thereof .as previously described. Rolling ofthe strip in opposite directions is continued until it has been reduced to the desired iinal gauge.

My invention also contemplates subjecting cold-rolled strip tovone or more passes through a single stand of rolls to remove set,therei`rom.v

This set is a transverse curvature which sometimes characterizesold-rolled material. To remove it, "I pass the strip between the lupper'roll I3 and the middle roll I5 of the Alower stand, as indicated by a chain line 35, or between the lower roll I6 and the middle roll I8F ofthe upper stand, as indicated by chain line 36, depending on the direction of the set.. The strip should be started through the mill so that the concave surface will be engaged by the small roll and thereby subieoted'to greater'deformation than the other surface, in accordance with the explanationgiven above. A This tends to remove the curvature and e deliver the rstrip ina-shape more nearly approachonan enlarged scale theA the reductionA in the original thickness of Izhef I I in the portion o1 the strip `thickness 'belowrthe median plane between -the upper and lower surfaces. In other words,

the twosides of the 'strip are deformed along the curvature ofthe rolls I3 and I5, the deformationcurves being designateda andV lia. The of the rolls, because of their dierent diameters; to be analogous to the actionof a hammerP ing a ilat or level condition. f Usually a. relatively 1 lightreductio in a single pass will sufce to re- Ise .,l

' It wlllbe apparent from the foregoing explana- Y tion that my invention is characterized -bye nu" merous advantages. The .most important has already been mentioned, vizwthe ,production of material having more o1; lessvvunifo'rm characters istics `parallel'and transverse to-the 4rolling direction. The preferred embodiment ofthe apparatus, includingtwo 3-high roll stands in the vsaine housings, -is obviously capable of producing a much greater reduction; `than a single 4-high Figure 3' illustrates the reductioneiected inl characteristics parallel andv transverse to the direction of rolling than in the v case of strip rolled by conventional methods and The.

roll stand. Two mills, suchv as that shown in Figure l, for example, will eiect areduction equivastrip, it mayA also `bes'utiliz'ed wfor temper rolling material such as tinplate stock while still in strip form. .v

A furtheradvantage of` the invention is that the strip is wrapped around one of the larger outer rolls of each stanji throughV an angle of more than 180?, which results in a frictional grip on the material whereby it may be subjected to' substantial tensions without slippage. j

^ Although vI have illustrated and described but:- a preferred embodiment and practice of the in` vention, it willoe recognized that changes in the construction and procedure disclosed may be made y' middle roll of one stand and the outer roll therey 2. In a method of flattening cold-rolled strip having a "set" or transverse curvature, the steps including cold-rolling the strip and deforming the concave surface thereof more deeply than theJ i convex surface.

3. In a method ofrolling strip, the steps including cold-reducing it progressively in a plurality of 3-high roll stands disposed one above the otherQeach having a middle roll smaller than the outer rolls. and passing the strip between the of adjacent the -other standthen between the middle roll of the other stand and the outer roll without departing from the spirit of the invention I or the scope of the appended claims.-

I claim:- I 1. In a method of flattening cold-rolled strip having a. set or transverse curvature, the 'steps including cold-reducing the strip by passing` it 'through a 3-high rolling mill having a middle roll smaller than the outer rolls, and starting the strip through the mill so that the concave surface f thereof is engaged by the middle roll.

thereof nearer the first-mentioned stand.

. 4. The method dened by` claim 3 characterized by maintaining the strip in contact with^thex outer rolls engaged thereby throughout about of'their circumference. i

5. A mill for reducing strip comprising a pair of spaced housings having windows therein, two stands of three rolls' each having their necks posed in'said windows with their axes substatitially in vertical alinement, chucks slidable in said windws adapted .to receive said nedks, and spacers between the chucks inwhich the necks of 0the tcm roll of the lower stand and the bottom roll of the upper stand are journaled, said speceri being movable relative to said housings with sai Alast-mentioned chucks.

a J' J. WEAN.

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