US2223039A - Method for elongating metal blanks - Google Patents

Description

,F. R KRAUSE METHOD FOR EL ONGATING METAL BLANKS Original Filed Feb. 19, 1937 5 Sheets-Sheet 1 INVENTOR.

ATTORNEYS.

WITNESSES a d lid/4A.",

' Nov. 26, 1940. v F, R K AUSE 2,223,039

METHOD FOR ELONGATING METAL BLANKS INVENTOR.

WITNBSfS may BY 4:. ATTORNEYS.

Nov. 26, 1940. F. R. KRAUSE' METHOD FOR ELONGATING METAL BLANKS Original Filed Feb. 19, 1937 5 Sheets-Sheet 3 INVENTOR.

wmvfssfs fig, ATTORNEYS.

F. R. KRAUSE METHOD FOR ELONGATING METAL BLANKS Original Filed Feb. 19, 1937 V 5 Sheets-Sheet 4 Nov. 26, 1940.

INVENTOR.

WITNESJEJ ATTORNEYS.

I l l I I Nov. 26, 1940. F. R. KRAUSE 2,223,039

METHOD FOR ELONGATING METAL BLANKS v Original Filed Feb. 19, 1937 5 Sheets-Sheet 5 A ATTORNEY! Patented Nov. 26, 1940 PATENT OFFICE METHOD roa ELONGATING METAL numxs Frank 1:. Krause, Ellwood City, Pa.

Original application February 19, 1937, Serial No.

128,633. Divided and this application, October 22, 1938, Serial No. 236,457

13 Clai s (o 30-60) This invention relates to a method for reducing and elongating metal blanks.

1 In metal rolling, as generally practiced today,

it generally requires a series of substantially full 6 length passes through a rolling mill to reduce a blank to the'desired-thiclmess'or gauge, the

reduction in any one pass being only a fraction of the total reduction. The reduction that can bemade in any one pass is limited-by the tendency of the rolls to slip against the blank if too great a draft is attempted to be taken. In fact,

if the draft is too great the blank'will not even enter the roll pass. In rolling thin sections such as strip, the amount of draft is also limited by the tendency of the metal to tear transversely at the center of the roll pass due to the friction force between the rolls and blank having a greater velocity in the direction of rolling at the pass center than at the first zone of contact of rolls and blank. Furthermore, the blank is rolled in one a uniform draft which requires a great deal of power. When a single mill stand is used, for each successive reduction the entire blank must pass through the mill which is thus subjected to considerable strain and wear in reducing each blank to the gauge desired.

It is among the objects of this invention toprovide a method for reducing metal blanks in which any desired reduction can be obtained in passing a blank through a single mill stand only once, in

which the draft is not limited to the coeflicient of friction for the blank and reducing means in which the character of the metal of the blank is improved, in which spreading of the blank is reduced to a minimum, and in which the life and capacity of the mill is increased.

In accordance with this invention a metal blank is reduced to any desired gauge or thickness by passing it once only through a mill having reducing means, such as a roll or rolls, which are caused to periodically move toward the front or entering end of the blank. During each of these working strokes the reducing means also first move toward the axis or central plane of the blank and then in paths parallel to that axis, whereby the unreduced portion of the blank is connected by 00 a tapered or wedg-shaped portion to a flat reduced portion. The movement of reducing rolls is brought about by relative reciprocable movement between. the blank and a pair of track surfaces that back up and engage the rolls. The 55 shape of these tracks determines the amount of reduction. The unrolled portion of the blank and the track surfaces are,held against movement in the same direction during the reducing steps so that the rolls have a definite drawing action on the blank as well as a pressing action. ii The rotation of the rolls is controlled principally by their frictional engagementwith the track surfaces and blank,-and the axes of the rolls are therefore free to accommodate themselves to the relative speeds of the tracks and blank. That 10 is, the rolls float by which is meant the rolls are not restricted by mechanical means in their movement along the blank and therefore can follow the elongation of the blank as the metal is displaced. During the return strokes of the '15 rolls between working strokes, unrolled increments of the blank are successively brought into position for reduction'by the rolls. It'will therefore beunderstood that in the practice of my in- I vention ablank is reduced to desiredgauge in 20 passingonce only through a single mill stand by a step-by-step feed. 1 1

Apparatus suitable for practicing; my invention is illustrated in the accompanying drawings in which Fig. 1 is a plan view, partly in section, 25 of a rolling mill and blank-clamping and pushing apparatus; Fig. 2 is acentral vertical section thereof, except that the upper roll is shown in elevation; Fig. 3 is an enlarged view of the delivery end of the mill, half of it being shown in section; 30 Fig. 4 is a plan view of apparatus for actuating the mill; Fig. 5 isa central vertical section thereof; Fig. 6 is a plan view-of apparatus for feeding blanks to the mill;'Fig.-'l is a central vertical section thereof Fig. 8 is an enlarged fragmentary view of Fig. 2; Fig. 9is an end view of the blankclamping apparatus taken on the line lX-IX of Fig. 2; Fig. 10 is a vertical section of the blank pusher taken on the line XX of Fig. 2; and Fig. '11 is a view showing diagrammatically the 40 relative positions of tracks and rolls at-diflerent. stages of a working stroke, the tracks being of a modified form. I Referring to the drawings, a track housing I, I provided with an opening 2 extendingfrom end to end thereof and having parallel horizontal and vertical side walls, is slidably mounted on a bedplate 3, Figs. 1, 2 and 3. Rigidly secured to the sidesof the track housing and projecting forbar 23 afllxed to thetop of the housing;

opposite ends of a crank shaft" journaled in the bed-plate. The gears are rotated by pinionsi turned by a drive shaft ll likewise journaled in the bed-plate and driven of power.

Removably mounted in the top and bottom walls of housing opening 2 is a pair of tempered steel track plates I2 betweenwhich a roll carriage I3 is slidabiy disposed for movement longitudinally of the opening. The carriage is guided in a straight line by a forward extensionften minating in an inverted channel ll slidably mounted on a rail I5 projecting from-the front of the track housing. Journaled in blocks l6 (Figs. 3 and 8) slidably mounted in ver;

tical recesses in the side walls of the roll carriage is a pair of superimposedreducing rolls II which are biased apart by coil springs ll compressed between the bearing blocks, Fig. 3. h

To permit the size of the rollpass to be varied for reducing blanks of different thicknesses to different gauges, the upper wall of opening 2is formed by a cap I 9 slidable vertically in the upper portion of thehousing. 'I'his cap is biased upwardly by a coil'spring '20 compressed between the top c! a recess 2| in the center of the cap and the head of a bolt 22 suspended from a c iiohss e cap is adjusted downwardly by wedges 24 between the cap and laterally spaced ribs 26 integral with the housing, Fig. 3. Thewedges are spaced from the'cap by segmental shoes 21 which facilitate transverse rocking of the cap when only one wedge is adjusted. To permit thewedges to be moved in and out," their rearends are provided with threaded rods .28, slidable in brackets 22 secured to thebackof the housing, the rods being providedswith adJust-ingnu-ts- 3|, Figs. .1 and 2.

It is afeature of this inventionthat the track plates are so formed that,"'as the track housing is""inoved forward by the cranks during each working stroke, the track plates carried by it roll the rolls forward against the stationary blank 32 toward its front end and simultaneously toward each other .whereby, by a combined rolling, sinking and drawing operation'fthey reduce and elongate the blank. -During .the latter part of the working stroke the rolls travel parallel to the parallel areas merging into areas 34' inclined.

away from each other toward the front of the track housing. Consequently, as the track housing moves forward from a 'positionin which the rolls loosely engage an unreduced increment of the blank a portion of which has already. been reduced during precedingworking strokes vof the mill, the inclined areas of the tracks move into frictional engagement with the rolls and force them tightly against the blank. Continued movement of the tracks causes these rolls to roll forward and inwardly at the sametime. This reduce's the previously unrolled increment to tapered form and further reducesthe blankfs previously tapered portion, the thinner end of which is thus reduced to thin flat strip bythe rolls when theparallel areas of the tracks reach themand by any suitable source move them in parallel paths as shown in Figs. 2 and 8.

The roller oll parallel to each other until the diverging rear ends of the track plates reach them, whereupon they are permitted to spread apart and become released from the strip. While the track housing is conti'nuing'to move forward a short distance before its movement is reversed,

the roll carriage is pushed forward with it. This is preferably done by a fluid pressure cylinder 36 mounted on the rearend of the bed-plate with its piston rod 31 connected to the carriage, as

shown in Fig. 2 Thus, when the track plates start their return stroke they cause the rolls to start rolling back from a point on the strip in front of the point at which the rolls were released from the strip. Consequently, the diverging areas at the front of the track plates reach the rollsbefore the latter reach the tapered portion of the strip so that the rolls will not roll that tapered portion during their'return stroke.-

The return of the roll carriage is accomplished more smoothly if chains 39 are. secured to the rear end of. the bed-plate and trained around divergingrear ends of the tracks. 7 On the return stroke of the housing the chains and sprockets insure the smooth return movement or the rolls, and near the end of the return stroke springs 4i expand and therebyrestore. the rolls to their original starting position relative to the tracks. At the conclusion of the return stroke the fluid under pressure is reversed to the front end of the cylinder, by-anywelLknown. means (not shown), to hold the roll carriage stationary atthe start of the next working stroke until the rolls-are brought into firm frictional engagement with the blank and tracks by the latter. 1 H

The drawings described thus far show the :inclined or diverging areas of the tracks flat lengthwise. This shape of track is satisfactory when 'thin blanks, such as strip substantially not over inch thick, are being reduced, because the necessary reduction can be made with the desiredshort workingstroke of the mill without increasing the degree of inclination of track'areas 34 to the point at which slippage of the rolls against the blank would occur. Tobe safe, the inclina-'v tion should probably notexceed 5. With thicker blanks, wherethe percentage of reduction is likely to be greater than in the case of thin blanks,

roilslippage is prevented without increasing the length of the working stroke or track by forming each inclined area 34 of a track plate in the shape of a reverse curve with its front end nearly horizontal, (preferably 1 /2 to 2) andits central portion more steeply inclined to the-horizontal, as shown in Fig. 11.. The latter inclination can be considerably greater than-5. I

As Just indicated, the principal reason for this shape of track is to prevent the rolls from slip-'- ping-on the tracks or blank during the short working strokes that are. desirable from :the standpoint of rapid operation. The likelihood of roll slippage on the blank isgreatest when they flrstmove into contact with the blank, and also when they approach the smaller end of the tapered portion of the blank where they come into contact with theparallel areas of the track. 'With 2,229,0 9 v 'ish'. and by the time the rear ends of the tracks tracks of theshape just referred to, the draft rolled cold thereinin which elongations of as.

is gradually increased during the beginning and gradually decreased during the ending of the working stroke of the'mill so, that there wilLbe no roll slippage at those times. "The heaviest draft is taken near the thicker 'end'of the blanks tapered portion which is'strong enough to'withstand it, and the draft is graduallyand materially decreased at the thinner end to prevent. tearing the blank apart at its weak section; 1

With track plates of either shape, each successive draft starts at zeroiat the surface of an unreduced increment and gradually increases to its maximum amount. This gradual increase of the draftwith its accompanying reduction orientates the crystals in the metal before subjecting them to more severe elongations, and thereby improves the character of the metal. This improved portion. of the metal is not affected .adversely during the, next working stroke of the'mill when it is subiectedto the maximum draft, but is still further improved" because this maximum ,draft-as effected inmy mill causes onlysgra'dually increasing elongationof the 'stock and very littl spreading thereof. In prior rolling practice in-which rolls roll a blank from front to rear and continuously against thepportion ofra blank having; the greatest thickness, the start of the draft at any given point alongthe stock is sudden instead. of gradualrand the crystals may therefore be caused to fracture when elongated under heavy drafts; The .small amount of spreading in my mill is shown by samples ofsteel much 'as to 1 were obtained ina single passage -through the mill with-a spreading of 25 per cent of that obtained with like pieces'of steel rolled ina two-high millgiving elongation of only v 16 to 1. The rolls used inboth mills were all-of the same diameter. The steel strip rolled in my mill was sound and pliable with smoothedges. but the strip rolled in the two-high mill with a 16 to 1 elongation was hard and had rough and torn edges. i

, Theshape of the reverse curve tracks and the outline of a blank rolled between them is shown roughly in the diagram of Fig. 11 where the relation of the diil'erent members to one another when in three diflerent positions is alsqdllustrated. ,The full lines indicate the shape of a blankin the process of being reduced/and also the positions of the track, plates and rolls durin the beginning of a working stroke after the I blank has first been, advanced a step to subject an unrolled incrementAe-B tothe action of the rolls. a As the tracks continue to advance'to 'the position indicated by broken .lines they roll the rolls forwardly andinwardlyinto their broken line position wherein increment A.-Band the adjoining portion of the tapered section of the blank are reduced an; amount also shown by broken lines. It will be seen'that. at this stage the increment A-B has been reduced but slightly, the reduction increasing as the front of the :each time, but upon the shapeof 'the tracksand fers, to the difference between vthe thickness 7 of i. reach the rolls another portion of flat reduced material has been added to the preceding com- *pletelyreduced portion. r r With this type of mill in which rollsrolisuc- 5 cessive increments of a blank 'toward itsffront A or entering end while the rolls bodily approach each othenblanks can'be reduced in a single pass 3 through the mill an amount heretofore thought -impossible,because no greater draft is necessary for making a large" reduction than for making a small one. i This isbecause the amount-of reduction'does not dependupon the draftswhich is governed by the'distance the blank is fed forward the length of the "MP8 workingstroke. I 'It' will be understoodthat "draft" refers to the thickness of the metal removed by the rolls each time they-rollalong the blank, while reduction re-' tion thereof.

the unrolled blank and the finished rolled por- The track plates as be so stated that large reductions canbe i made Y with short working strokes, because roll slippage is prevented -bythe shape of the ends "of the inclinedareas of the track plates; Also, the rolls'float' between the 1 track =plates and are not turned throush their axes but at their periph'erieaso that the-apex of the contact angle 1'' of each'roll is at the point I of engagement of the roll "with the'trackg Consequently, the contact angle is smaller for any given draft than for -a like draft in a 'mill in which the apex" of the contact angle iswat the axis of a roll. The smaller the contact anglethe less thetension stress on the blank froniafo'rce exerted longitudinally thereof toward the rolls}. 1

and also theless thelikelihood of slippage of the rolls against the blank. The twoforce's' acting in opposite directions to turn each'roll are exerted at the periphery of the roll atits points.

of contact-with the blank and adjoining track,

whereby the leverage. usedin turning the roll is about twiceas great as when-'one-of thoseforces is exerted at the axis of .the roll,' and-the"roll offers abouthalf as muchresistance to turning. This factor also contributes-to reduction in ten- 'slon' stress on the blank and in the 'likelihoodof slippage of rolls against blank and tracks-'- Another factor that differentiates this mill from those known heretofore is that the m'et'al 'under rolling pressure is distributed" on both sides ofthe vertical center line or the rolls,- instead of all on one side ofth'at 'line. This particular area of metal is indicated by the character Erin Fig; '11.

As the metal must; therefore be displaced on both sides; of this-center line it .must naturally flow inopposite directions therefrom, 'as indicated by the arrows, whereby 60 the metalin the pass is under tension aswell as compression as it is being displaced and'th'erefore spreadsless than in any otherrolling'practice in use today. As the flow" of metal in .case is due to a combinationoftension andeompression forces, the metal pressureorseparating force exerted on'the rolls-is'less'than it would-be if. compression forces alone were'relied upon'to reduce :theblank. An advantage flowingfrom this is that the blankand themill'are subjected tov less strain than heretofore andthe capacity and life of the mill are therefore increased. Distribution ofmetal on both: sides of the center line of the rolls also prevents the-metal from backingaway bodily from the center of the pass as there has previously been a tendency todoin'7 ""mill's wherein a ingle" wedge-like body a is held in contact with the. rolls only by friction forcethat tends to pull it into the pass only by surface action on the metal. The metaljust .entering the roll pass and in contact with the rolls does not move noticeably relative to the surface of the rolls in going through the pass, and therefore this no-slip area of metal carries or floats the rolls along with it while they are rotating. This results in considerably less rotation of the rolls fora given amount of linear travelthan in any other. mill of which Iknow. t

As-indicated before, while the track housing is making its return stroke,.i. e.,returning to its startingpoint-during each cycle, and while the rolls are released from the blank, the blank is .fed or advanced. a step to subject the next succeeding unrolled or unreduced increment thereof to the action of the rolls.

; Adesirable feeding apparatus for this. purpose I is illustrated in the drawings wherein a slide 142 .is slidable toward and away fromthe mill in a a longitudinally extending recess 43 in .a table 44.

. As. showninFig. 10,-the opposite, side walls of slide to hold it in the recess. the blank is clamped to the slide by'means of 1 B slide is moved toward the mill bya piston rod the recess are provided with a pair of inwardly" -projecting lribs 45 below whichextend flanges l6 projecting laterally: from the bottom of the The rear end of a {bar 4! bolted to the top of-the slide. The

"connected toa" piston 49 disposed in a cylinder 5] located at the rear of table ,Flgs; 6

and'l. The pistonis constantly biased toward the mill by fluid pressure behind it in the cylinder, but its. forward movement is obstructed .at

predetermined intervals by fluid in the. cylinder infront of the'piston. That is, a predetermined qvolume of fluid in front of the piston is released from the cylinder at periodic intervals, thepiston' .being forced ahead by the pressure behind it .each time this occurs. 1

, I Suitable. automatic means for releasing fluid from the front of the cylinder is shown in Fig. ,7. A pipe 62 extends from the front 1 end of the Qcylinder down through a.housing 53 to a drain ivo .orsump. The pipeis provided within the housing with a -shut-oil valve 54 which is. actuated by a lever biased forwardly to closed'position against a pin stop 51 by a coil spring". Slidably mounted in the housing above'this valve is a rod 59' the front end of which is connected to the bottom of the track housing, as shown in Fig. 2. Within the valve housing a depending dog 6| is pivoted to the rod and biased forwardly against a pin stop 32 by a coil spring 63. when the track housing starts its return stroke-from the position shown in Fig. 2, the rod is slid backwardly through the housing to cause dog ii to engage the valve lever and swing it backwardly to open the valve. As the valve isopened fluid escapes from the front of .the cylinder and fluid ,pressure behindthe piston moves it forward to feed the blank ahead a step. As the dog continues to movebackwardly it slides off the end of the valve lever which is immediately jerked forward to closed. position by coil spring 58.

This closing of the valve stops the piston and blankfeed. When the dog is moved forwardly by the advancing track housing it passes over the 1 end of the lever and then is pulled forward against stop'ilby spring 63. The volume of fluid. that is permitted to escape from the front .of the. cylinder each time valve 54 is opened determines the amount of feedof piston and blank.

'aaaaosa metal and this volume is controlled by an adjustable valve 34 in the pipe above the shut oif valve.

At periodic intervals, i. e., for the duration of each working-stroke of the mill. the blank is held in flxed position by an automatic clamp shown most clearly in Fig. 9. .Due to'the fact that the 'unrolledportion' of the blank is thus held in fixed position during rolling, the rolls exert a drawing action on the blank. Thecl'amp includes a support'lii'provided at one side with a bracket 61 in which is pivotally mounted one end ofan' arm 68 that extends across the top of. the support with its opposite end connected by a depending link 69 to a-piston ll disposed in 1 a hydraulic cylinder'12..--Mounted on support 66 is'a'table 13 that supports the blank-above which is a clamping head I4 connected to arm 63 by which it is forced downto clamp the blank against table l3'when-the arm is drawn down I by piston .H. To permit the clamping head to accommodate itselfto blanks of different thicknesses, it is preferably made self-aligningby providing its upper'suri'ace with a concave recessin which is seatedva convex bearing I6 projecting from the bottom of the .arm. The clamping head is held against this hearing by a bolt 11* extending up through an oversized opening in the head and biased upwardly by a 'coilspring .13 encircling it in a recess in the top of the arm.

Fluid pressure is automatically supplied to the any well-known automatic control which may be actuated by the reciprocating track housing if desired. f 1

To summarize the operation of themill described herein, a blank '32 is held at itsrear end in pusher slide 42 which at that time is'atthe 3 hydraulic cylinder and released therefrom by rear-end -of table. With the blank clamped in fixed position by clamping head "with its front end in the roll pass, drive shaft "II is rotated which, by means of cranks 1 and rods,

moves track housing I forward whereby rolls'l'l taper the end of the blank before running ofi the end of it. During the'return or backward stroke of the mill the clamp releases the blank which is then fed forward an increment by the slide which is pushed forward by piston 49 in the .manner described above; As soon as movement of the piston is arrested by the closing of valve 54, the blank is again clamped in place by head 14, and the rolls start forward again'and taper an unreduced'increment of the blank and further'reduce the previously'tapered end thereof.

This tapering alone continues until a suflioient length of the blank extends far enough through the-roll. pass to be engaged by the rolls throughout their working stroke, whereupon the foremostportion of the blank is engaged by the rolls while they are moving parallel to each other between track areas 33 and a flat reduced portion of the blank of uniform gauge is produced. The blank continues to be fed ahead step'by step, and after each feeding step a new increment of the blank is tapered by the mill rolls and the front end of the previouslytaperedportion is flattened and added to the next preceding finished portion of the blank. In the case of I will be understood that the invention can likewise be practiced to advantage inthe hot reducing of metal blanks. M

Although the invention has beendescribed-as contemplating holding theblank stationary while the mill is reciprocated to reduce it, it will be understood that the mill can be stationary and-the blank reciprocated in"it;as it is fed through-the According to the provisions of the Patent Statutes, I have explained the principle and mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

This application is a division of my copending application Serial No. 126,633, filed February 19, 1937, now Patent No. 2,161,064.

I claim:

1. The step-by-step method of rolling a metal blank toward its front end periodically by successive increments, in which rotation of a roll is effected and controlledonly by opposing forces acting on opposite sides of the roll at its periphery.

2."I'he method of reducing a metal blank step by step in successive increments by periodically rolling a roll toward the front end of the blank by means of a track member frictionally engaging the periphery of the roll, comprising leaving the roll free to accommodate itself to the relative speeds of said track member and blank.

3. The method of reducing a blank between a pair of backed-up rolls, comprising effecting relative reciprocable movement between said rolls and blank longitudinally of the blank to cause the rolls to periodically roll toward the front end of the blank, the axes of the rolls being free to accommodate themselves to the relative speeds of the blank and roll backing-up means, moving the rolls first toward each other and then substantially parallel .to each other as they approach the front of the blank to reduce and elongate a portion thereof, and periodically subjecting successive unrolled increments of the blank to the action of said rolls.

4. The method of reducing a metal blank between a pair of rolls, comprising simultaneously rolling the rolls toward the front end first of said blank and toward and then substantially parallel to each other to reduce and elongate a portion of the blank, the rotation of the-rolls being controlled principally by their frictional engagement with the blank and force-applying means engaging the periphery of the rolls, advancing the blank a step, and repeating said rolling starting with an unreduced increment of the blank.

5. The method of reducing a metal blank between a pair of rolls, comprising rolling a portion thereof simultaneously toward the entering end of the blank and the central plane thereof to taper said portion while holding the unrolled portion of the blank against movement in the direction of rolling, continuing the rolling parallel to said plane to produce a flat reduced portion, and periodically repeating the entire rolling operation starting with a succeeding unrolled increment of the blank each time.

6. The method of reducing a metal blank between a pair of rolls, comprising simultaneously rolling the rolls toward the front end of said blank and toward each other to reduce and elongate a portion ofIthe blank, continuing the rolling with the rolls moving in substantially parallel paths, said rolling movementof 'therolls being caused solely by opposing forces acting only at the periphery of said rolls, and periodically advancing ,successiveunro'lled increments of said blank for reduction by said rolls. 7

7. They method of reducing am H a1 blank between-a pair-10f back-up rolls, comprising simultaneously rolling the rolls toward the front end of said blank and toward each other to reduce and elongate a portion of the blank, continuing the rolling with the rolls moving in substantially parallel paths, the rolls being free to accommodate themselves to the relative speeds of the blank and roll backing-up means, releasing the rolls from said blank and moving them toward the rear end of the blank, advancing the blank an increment, repeating said rolling startingwith an unreduced increment of the blank, and hold-- ing the unrolled portion of the blank in substantially fixed position during each blank-reducing step.

8. The method of reducing a metal blank, comprising simultaneously rolling a pair of rolls toward the front end of said blank and gradually toward each other, continuing the rolling with the rolls approaching each other more rapidly followed by a more gradual approach, advancing the blank a step, and repeating said rolling starting with an unreduced increment of the blank.

9. The method of reducing a metal blank between a pair of rolls, comprising rolling a portion thereof simultaneously toward the entering end of the blank and the central plane thereof to taper said portion, continuing the rolling parallel to said plane to produce a fiat reduced strip,

returning the rolls to their original position, ad-

vancing the blank a step, repeating the entire rolling operation starting with an unrolled increment of the blank, holding the unrolled portion of the blank in substantially fixed position during each blank-reducing step, said increment being tapered and said previously tapered portion being further reduced with its thinner end reduced to flat form during said second rolling operation, and repeating the entire cycle .of operation until substantially the entire blank is rolled down to fiat reduced form.

10. The step-by-step method of reducing a metal blank in successive increments, comprising effecting relative reciprocable movement between said blank and blank-reducing means longitudinally of the blank to cause said means to periodically move toward the front end of the blank, moving said means first 'toward and then substantially parallel to the axis of the blank as it approaches the front of the blank to reduce and elongate a portion thereof, and leaving said means free to accommodate itself to the elongaapproaches the front of the blank to reduce and I elongate a portion thereof, leaving said means free to accommodate itself to the elongation of the blank, and holding the unrolled portion of 10 comprising simultaneously rolling a pairoi rolls toward the front end of said blank and toward each other in planes intersecting the axis of the blank at an angle of approximately 2,continuing the rolling withthe rolls approaching each other in planes intersecting said axis at'an angle substantially greater than 5 followed by a more gradual approach, advancing the blank astep,

and repeating said rolling starting with an unreduced increment of the blank.

FRANK R. KRAUSEQ

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