US2161064A

US2161064A - Method and apparatus for elongating metal blanks

Info

Publication number: US2161064A
Application number: US126633A
Authority: US
Inventors: Frank R Krause
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-02-19
Filing date: 1937-02-19
Publication date: 1939-06-06
Anticipated expiration: 1956-06-06

Description

June 6, 1939. F, R KRAUSE 2,161,064

METHOD AND APPARATUS FOR ELONGATING METAL BLANKS F15; Reb. 19 1957 e Sheets-Sheet 1 l XL IW/TNEJSEJ J INVENTOR- 4 ATTORNEYS.

June 6, 1939. F R KRAUSE 2,161,064

METHOD AND APPARATUS FOR ELONGATING METAL BLANKS 44 Filed eb. 196 1937 6 Sheets-Sheet 2 'WENTOR.

' w/r/mms I 4/ W a BY i L v ATTORNEYS.

June 6- 939. F, R KRAUSE 2,161,064

AETHOD AND APPARATUS FOR ELONGATING METAL BLANKS Filed Feb. 19, 1957 6 Sheets-Sheet 3 l i a I 0 v: s O 6 FJ L. I .f L '1 2 E I i 4 L..i rI. ...I.! .I. J

INVENTOR.

WIN/E5555 M BY r 3& ATTORNEYS.

June 6, 1939. F. R. KRAUSE 2,151,064

METHOD AND APPARATUS FOR ELIONGATING METAL B LANKS Filed Feb. 19, 1937 6 Sheets-Sheet 4 INVENTOR.

wlrlvfssis ATTORNEYS.

June 6, 1939. R K us 2,161,064

METHOD AND APIARATUS FOR ELONGATING METAL BLANKS 6 Sheets-Sheet 5 Filed Feb. 19, 1957 .l I l a 1 l i I ,I' WITNEJJEJ I INVENTOR.

A4 BY W/W zmw @AMKO/ QMWM June 6; 1939. R us' 2,161,064

METHOD AND APPARATUS FOR ELONGATING METAL BLANKS Filed Feb. 19, 1937 6 Sheets-Sheet 6 INVENTOR.

WITNESSES BY W. d. MM. ATTORNEYS.

Patented June 6, 1939 PATENT OFFICE METHOD APPARATUS FOR ELONGAT ING METAL BLANKS 4 Frank R. Krause, Ellwood City, Pa.

Application February 19, 1937, Serial No. 126,633

r 18 Claims.

This invention relates to a method and apparatus for reducing and elongating metal blanks,

and relates more particularly to the rolling of blanks of solid section, such as plates, sheets, 5 strips, bars and the like.

In metal rolling, as generally practiced today, it generally requires a series of substantially full length passes through a rolling mill to reduce a blank to the desired thickness or gauge, the re- 10 duction in any one pass being only a fraction of the total reduction. The reduction that can be made 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 betaken.

15 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 cente'r of the roll pass due to the friction 3 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 continuous operation from its front end to 3 its rear end in each pass, whereby the rolls constantly roll against the thickest portion of the blank with a uniform draft which requir s a great deal of power. When a single mill s and is used, for each successive reduction the entire '0 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 to provide a method and apparatus for rolling :5 metal blanks in which any desired reduction can be obtained in passing a blank through a single mill stand only once, in'which the character of the metal of the blank is improved, 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 rolls which are caused to periodically roll toward the front or entering end of the blank. 45 During each of these working strokes the rolls also first move toward each other and then in .paths parallel to each. other, whereby the unreduced portion of the blank is connectedby a tapered or wedge-shape portion to a flat reduced 0 portion. ,The movement of the 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 shape of these tracks determines the amount of reduction. During the return strokes of the rolls between In fact, if,

working strokes, unrolled increments of the blank are successively brought into position for reduction by the rolls. It will therefore be understood that in the. practice of my invention a blank is reduced to desired gauge in passing 5 once only through a single mill stand by a stepby-step feed.

a The invention, is illustrated in the accompanying drawings in which Fig. 1 is a plan view, partly in section, of my rolling mill and blankclamping and pushing apparatus; Fig. 2 is a central vertical section thereof, except that the upper roll is shown in elevation; Fig. 3 an enlarged view of the delivery end of the mill, half of it being shown in section; Fig. 4 is a plan view 15 of apparatus for actuating the mill; Fig. 5 is a central vertical section thereof; Fig. 6 is a plan view of apparatus for feeding blanks to the mill; Fig. 7 is a central verticalsection thereof; Fig. 8

is an enlarged fragmentary view of Fig. 2; Fig.

9 is an end view of the blank-clamping apparatus taken on the line IX-IX of Fig. 2; Fig. 10 is a vertical section of the blank pusher taken on the line X-X of Fig. 2; Fig. 11 is a view showing diagrammatically the relative positions of tracks and rolls at different stages of a working stroke, the tracks being of a modified form; Fig. 12 is a fragmentary plan view of. a modification of my rolling mill; and Fig. 13 is an enlarged central vertical section thereof with the upper roll shown in elevation.

Referring to the drawings, a track housing I, provided with an opening 2 extending from end to end thereof and having parallel horizontal and vertical side walls, is slidably mounted on a bed plate 3, Figs. 1; 2 and 3. Rigidly secured to the -sides-'of the track housing and projecting forwardly therefrom are a pair of rods 4, connected at their front ends by a crosshead 6 slidably mounted on an extension of the bed plate, Figs. '40 4 and 5. Pivotally mounted on the opposite ends of the crosshead are crank arms I which are actuated-by large heavy gears 8 mounted on the opposite ends of a crank shaft l0 journaled in the bed plate. The gears are rotated by pinions 4,5 9 turned by a drive shaft ll likewise journaled in the bed plate and driven by any suitable source of power.

Removably mounted in the top and bottom walls of housing opening 2 is a pair of tempered steel track plates l2 between which a roll car-' riage I3 is slidably disposed formovement longitudinally of the opening. The carriage is guided in a straight line by a forward extension terminating in an inverted channel It slidably mount- 55.

biased apart by coil springs it compressed between the bearing blocks, Fig. 3'.

To permit the size of the roll pass to be varied for reducing blanks of different thicknesses to different gauges, the upper wall of opening? is formed by a cap it slidable vertically in the upper portion of the housing. This cap is biased upwardly by a coil spring 26 compressed between the top of a recess 25 in the center of the cap and the head of a bolt 22 suspended from a cross bar 23 afiixed to the top of the housing. The cap is adjusted downwardly by wedges 26 between the cap and laterally spaced ribs 2% integral with the housing, Fig. 3. The wedges are spaced from the cap by segmental shoes fill which facilitate transverse rocking of the can when only one wedge is adjusted. To permit the wedges to be moved in and out, their rear ends are provided with threaded rods 26 slidable in brackets 29 secured to the back of the housing, the rods being provided with adjusting nuts it El Figs. 1 and 2.

It is a feature of this invention that the track plates are so formed that, as the track housing is moved 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 combinedrolling and sinking operation, they reduce and elongate the blank. During the latter part of the working stroke the rolls travel parallel to the central longitudinal plane of the blank to form flat reduced material, metal strip being shown in the drawings for the purpose of illustration. The rolls move forward at any speed imparted to them by the track plates, generally about half as fast as the latter.

Accordingly, as shown in Figs. 2 and 8, the tracks are provided adjacent their rear ends with parallel areas 33 merging into areas 36 inclined away from each other toward the front of the track housing. Consequently, as the track housing moves forward from a position in which the rolls loosely engage an unreduced increment of the blank a portion of which has already been reduced during preceding working strokes of 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 same time. This reduces the previously unrolled increment to tapered form and further reduces the blanks previously tapered portion, the thinner end of which is thus reducedto thin flat strip by the rolls when the parallel areas of the tracks reach them and move them in parallel paths as shown in Figs. 2 and 8.

The rolls roll 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 continuing 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 rear end of the bed plate with its piston rod 3? 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 frbm a point on the strip in front of the point at which the rolls were re leased from. the strip. Consequently, the die verging areas at. the front of the track'plates' reach the rolls before the latter reach the tapered portion of the strip so that 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 sprockets iii loosely mounted on the ends of the rolls. The opposite or front ends of the chains are connected to the rear of the track housing by coil springs ll that allow the roll carriage to be pushed forward with the track housing by piston rod Bl after the rolls reach the diverging rear ends of the tracks. 0n the return stroke of the housing the chains and sprockets insure the smooth return movement of the rolls, and near the end of the return stroke springs ii expand and thereby restore 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 any well known means (not shown), to hold the roll carriage stationary at the start of the next working stroke until the rolls are brought into firm frictional engagement with the blank and tracks by the latter.

In rolling brittle or unusually thin material it may be desirable to reduce the strain exerted by the forward movement of the rolls on the portion of the blank in the roll pass. i2 and 13, this can be done, where necessary, by securing a pair of chains 8! to rings 82 disposed at the rear end of the bed plate and training each chain around a sprocket t3 keyed on one end of each roll. The front ends of the chains are connected to the rear of the track housing so that as the tracks roll the rolls forward the chains aid in turning them and thereby relieve the blank of some of that strain. The front ends of the chains are preferably connected to the track housing by coil springs 8t in the same manner as the previously described chains in order to permit the chains to give a little and thus compensate for variations in pitch diameter due to roll wear and redressing. v

Rings 82 are mounted on eccentrics 86 keyed to a shaft 811 journaled in bearings 88 on the bed plate. The shaft is turned through levers it?) by rods 95, the front portions of which are slidably disposed in brackets 92 secured to the sides of the track housing. These rods are shifted longitudinally when stops 93 and 9d mounted thereon are engaged by the brackets.

During the major portion of the working stroke the eccentrics are in the position shown in Fig. 13 with the rear ends of the chains in their rearmost position. As the rolls are released from the blank by the diverging rear ends of the tracks,

v brackets 92 strike front stops 93 and carry rods 98 forward and thereby swing levers 89 forward too. This causes eccentrics 86 to move rings 82 forward, whereby the chains are in efieot lengthened or allowed to move forward. The slack that might otherwise be formed in the chains is immediately taken up by the action of the piston 96 that moves the roll carriage ahead with As shown in Figs. I

the track housing so that the return stroke of the rolls will start from an advanced point, as previously described. The piston may be moved forward in cylinder 9! by any suitable means, such as fluid pressure or a coil spring. No valve is necessary.

During the return stroke of the track housing the rollsare aided .in theirfreturn by the chains. Near the conclusion of the return stroke, housing brackets 92 strike rear stops 94 and move rods 9| and the levers rearwardly. Thiscauses the eccentrics to throw rings 82 back to their original position whereupon the chains pull the roll carriage back to its starting position relative to the track housing ready for the following working.

stroke.

The drawings described thus far show the in-. clined or diverging areas of the tracks flat lengthwise. Thisshape 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 desired short working stroke 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. To be safe, the inclination should probably not exceed 5. With thicker blanks, where the percentage of reduction is likely to be greater than in the case of thin blanks, roll slippage 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 to 2) and its central portion more-steeply inclined to the horil zontal, as shown in Fig. 11. The latter inclination can be considerably greater than 5.

As just indicated, the principal reason for this shape of track is to prevent the rollsfrom slipping on the tracks or blank during the short 1 working strokes that are desirable from the standpoint of rapid operation. The likelihood of roll slippage on the blank is greatest when they first move 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 the parallel areas of the track. with tracks of the shape just referred to, the draft is gradually increased during the beginning and gradually decreased during the ending of the working stroke of the mill so that there will be 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 gradually and materially decreased at the thinner end to prevent tearing the blank apart at its weak section.

With track plates of either shape, each suc-. cessive draft starts at zero atthe surface of an unreduced increment and gradually increases to its maximum amount. This gradual increase of the draft with its accompanying reduction orientatesthe 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 subjected to themaximum draft, but is still further improved because this maximum draft as effected in my mill causes only gradually increasing elongation of the stock and very little spreading thereof. In prior rolling practice in which rolls roll a blank from front to rear and continuously against the portion of a blank having the greatest thickness, the start of therefore be caused to fracture when elongated under heavy drafts. The small amount of spread- 1 the draft at any given point along the stock is sudden instead of gradual and the crystals may 30 to 1 were obtained in a single passage through the mill with a spreading of 25 per cent ofthat obtained with like pieces of steel rolled in a two high mill giving elongation of only 16 to 1. The rolls used in both mills were all of the same diameter. The steel strip rolled in my mill was sound and pliable with smooth edges, but the strip rolled in the two high mill with a 16 to 1 elongation was hard and had rough and torn edges.

The shape 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 different members to one anotherwhen in three different positions, is also illustrated.

The full'lines indicate the shape of a blank in the process of being reduced, and also the positions of the track plates and rolls during the beginning of a working stroke after the blank has first been advanced a step to subject an unrolled increment A-B to the action of the rolls. As the'tracks continue to advance to the position tindicated by broken lines they roll the rolls forcontinue to advance to the dotted line position in which their parallel areas reach the rolls, also dotted, the blank is reduced to the shape indicated by both broken and dotted lines. The portion 0-D is'reduced materially, but as line D is approached the draft starts to diminish, and by the time the rear ends of the tracks reach the rolls another portion of flat reduced material has been added to the preceding completely reduced portion.

-With this type of mill in which rolls roll successive increments of a blank toward its'front or entering end while the rolls bodily approach" each other, blanks can be reduced" in a single pass 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. This is because the amount of reduction does not depend upon the draft, which is goyerned by the distance the blank is fed forward each time, but upon the shape of the tracks and the length of the mill's working stroke. It will be understood that draft refers to the ,hickness of the metal removed by the rolls each time they roll along the blank, while reduction refers to the difference between the thickness of the unrolled' blank and the finished rolled portion thereof.

The track plates can be so shaped that large reducions can be made with short working strokes, because roll slippage is prevented by the shape of the ends of the inclined areas of the track plates. Also, the rolls that between the track plates and are not turned through their axes but at their peripheries, so that the apex of 'the contact ,7 angle F of each roll is at the point of engagementof the roll with the track. 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 is at the til till

axis of a roll. The smaller the contact angle the less the tension stress on the blank from a force exerted longitudinally thereof toward the rolls, and also the less the likelihood of slippage of the rolls against the blank. The two forces acting-in opposite directions to turn each roll are exerted at the periphery of the roll at its points of contact with the blank and adjoining track, whereby the leverage used in turning the roll is about twice as great as when one of those forces is exerted at the axis of the roll, and the roll offers about half as much resistance to tuming. This factor also contributes to reduction in tension stress on the blank and in the likelihood of slippage of rolls against blank and tracks.

Another factor that differentiates this mill from those known heretofore is that the metal under rolling pressure is distributed on both sides of the vertical center line of the rolls, instead of all on one side of that line. This patricular area of metal is indicated by the character E in Fig. 11. As the metal must therefore be displaced on both sides of this center line it must naturally flow in opposite directions therefrom, as indicated by the arrows, whereby the metal in the pass is under tension as well as compression as it is being displaced and therefore spreads less than in any other rolling practice in use today. As the flow of metal in this case is due to a combination of tension and compression forces, the metal pressure or separating force exerted on the rolls is less than it would be if compression forces alone were relied upon to reduce the blank. An advantage flowing from this is that the blank and the mill are subjected to less strain than heretofore and the capacity and life of the mill are therefore increased. Distribution of metal on both sides of the center line of the rolls also prevents the metal from backing a'way bodily from the center of the pass as there has previously been a tendency to do in mills wherein a single wedge-like body of metal is held in contact with the rolls only by friction force that tends to pull it into the pass only by surface action on the metal.

As indicated before, while the track housing is making its return stroke, 1. e., returning to its starting point 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.

A desirable feeding apparatus for this purpose is illustrated in the drawings wherein a slide $2 is slidable toward and away fromthe mill in a longitudinally extending recess lit in a table l l. As shown in Fig. 10, the opposite side walls of the recess are provided with a pair of inwardly projecting ribs 35 below which extend flanges d6 projecting laterally from the bottom of the slide to hold it in the recess. The rear end of the blank is clamped to the slide by means of a bar ell bolted to the top or the slide. The slide is moved toward the mill by a piston rod d8 connected to a piston Q9 disposed in a cylinder 5! located at the rear of table dd, Figs. 6 and 7. The piston is constantly biased toward the mill by fluid pressure behind it in the cylinder, but its forward movement is obstructed at predetermined intervals by fiuid in the cylinder in front of the piston. That is, a predetermined volume of fluid in front of the piston is released from the cylinder at periodic intervals, the piston being forced ahead by the pressure behind it each time this occurs.

Suitable automatic means for releasing fluid from the front of the cylinder is shown in Fig. 7. A pipe 52 extends from the front end of the cylinder down through a housing 53 to a drain or sump. The pipe is provided within the housing with a shut-off valve M which is actuated by a lever 56 biased forwardly to closed position against a pin stop 51 by a coil spring 58. 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 62 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 6| to engage the valve lever and swing it backwardly to open the valve. As the valve is opened fluid escapes from the front of the cylinder and fluid pressure behind the piston moves it forward to feed the blank ahead a step. As the dog continues to move backwardly 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 blank feed. When the dog is moved forwardly by the advancing track housing it passes over the end of the lever and then is pulled forward against stop 62 by spring 63. The volume of fluid that is permitted to escape from the front of the cylinder each time valve is opened determines the amount of feed of piston and blank, and this volume is controlled by an adustable valve 64 in the pipe above the shut-off valve.

At periodic intervals, 1. e., for the duration of each working stroke of the mill, the blank is held in fixed position by an automatic clamp shown most clearly in Fig. 9. This clamp includes a support 66 provided at one side with a bracket 6'! in which is pivotally mounted one end of an arm 58 that extends across the top of the support with its opposite end connected by a depending link te to a piston ll disposed in an hydraulic cylinder it. Mounted on support 66 is a table 13 that supports the blank above which is a clamping head Ed connected to arm t8 by which it is forced down to clamp the blank against table l3 when the arm is drawn down by piston l I. To permit the clamping head to accommodate itself to blanks of different thicknesses, it is preferably made self-aligning by providing its upper surface with a concave recess in which is seated a convex bearing 76 projecting from the bottom of the arm. The clamping head is held against this bearing by a bolt ll extending up through an oversized opening in the head and-biased upwardly by a coil spring it encircling it in a recess in the top of the arm. Fluid pressure is automatically supplied to the hydraulic cylinder and released therefrom by any well-known automatic control which may be actuated by the reciprocating track housing if desired.

To summarize the operation of the mill described herein, a blank 32 is held at its rear end in pusher slideflZ which at that time is at the rear end of table M. With the blank clamped in fixed position by clamping head 14 with its front end in the roll pass, drive shaft I l is rotated which, by means of cranks I and rods 4, moves track housing I forward whereby rolls fl'l taper the end of the blank before running off 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 .Iclaim:

is pushed forwardby 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

5 the rolls start forward again and taper an unreduced increment of the blank and further reduce thepreviously tapered end thereof. This tapering alone continues until a suflicient length of the blank extends far enough through the roll pass to be engaged by the rolls throughout their working stroke, whereupon the foremost portion of the blank is engaged by the rolls while they are moving parallel to each other between track areas 33 and a fiat 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 previously tapered portion isflattened and added 0 to the next preceding finished portion of the the grain structure of the blank and substantially unlimited reduction in one pass through the mill, relate to cold working. Nevertheless it will be 0 understood that the invention can likewise be practiced to advantage in the hot rolling of metal blanks.

' Although the invention has been described as contemplating holding the blank stationary while 5 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 mill. In either case, a blank can be reduced to desired gauge more quickly with my mill than u with an ordinary single stand mill.

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.

l. A rolling mill comprising a housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away I from each other toward the exit end of the housing, a pair of rolls rotatably mounted between said track surfaces in frictional engagement therewith, said rolls forming a pass for receiving a metal blank, means for efiecting relative longi- D tudinal reciprocable movement between said housing and blank to cause said rolls to periodically roll simultaneously on the blanktoward the entering end of the blank and toward each other to reduce and elongate a portion of the blank, the 5 rotation of the rolls being controlled principally by their frictional engagement with the tracks and blank, means for holding said housing and the unrolled portion of the blank against movement in the same direction during the blankreducing steps,- and means for periodically sub Jecting successive unrolled increments of said blank to the action of said rolls whereby to periodically roll successive portions of the blank.

- 2. A cold rolling mill comprising a track hous- 5 ing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the exit end of the housing, a carriage disposed in said track housing between said tracks, a pair'of rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming a pass for receiving a metal blank, means for effecting relative longitudinal reciprocable movement between said track housing and blank to cause said rolls to periodically roll simultaneously on the blank toward the entering end. of the blank and toward each other to elongate a portion of the blank, the forward movement of the rolls relative H tially parallel areas merging into areas inclined away from each other toward the front of the housing, .a carriage disposed in said track housing between said tracks, a' pair of rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming a pass for receiving a metal blank, means for reciprocating said track housing longitudinally of said blank to cause said rolls to periodically roll simultaneously toward the front end of the blank and to-, ward each other to reduce and elongate an in-. crement of the blank, the motivating force for moving said rolls forward being supplied solely by said tracks through their frictional engagement with the peripheries of the rolls, means for holding the unrolled portion of the blank in fixed position during each blank-reducing step, and means for periodically advancing successive unrolled increments of said blank into the roll pass. between reducing strokes of said rolls.

- 4. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage disposed in said track housing between said tracks, a pair of rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming a pass for receiving a metal blank, means for recipro cating said track housing to cause said rolls to periodically roll simultaneously toward the front end of the blank and toward each other to elongate a portion of the blank, means for returning said rolls to their starting position after each working stroke, means for delaying said return stantiallyparallel areas merging into areas inclined away from each other toward the front of the housing, a carriage disposed in said track tatably mounted in said carriage in frictional engagement with said tracks and forming a metal blank-receiving pass, means for reciprocating said tra'ck housing longitudinally of the blank to cause said track plates to periodically roll said rolls simultaneously toward its front end and toward each other to elongate an increment of the blank, means associated with said track housing for engaging said carriage to return it to starting position after each working stroke, fluid pressure means for delaying the return of said carriage during the return stroke of said track housing,

and means for periodically advancing successive unrolled increments of said blank into the roll pass.

6. A rolling mill comprising a housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, said inclined areas diverging slightly adjacent said parallel areas and then diverging more sharply followed by less divergence, a pair of rolls rotatably mounted between said track surfaces in frictional engagement therewith and forming a blank-receiving pass, means for effecting relative longitudinal reciprocable movement between said housing and blank to cause said track surfaces to periodically roll said rolls simultaneously toward the front end of the blank and inwardly toward each other to reduce a portion of the blank, said inward movement of the rolls being gradual at first and then more sudden followed by gradual inward movement, and means for periodically subjecting successive unrolled increments of said blank to the action of said rolls.

7. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage disposed in said track housing between said tracks, a pair of, rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming a pass for receiving an elongate metal blank, means for reciprocating said track housing longitudinally to cause said rolls to periodically roll simultaneously toward the front end of the blank and toward each other to elongate a portion ofthe blank, the motivating force for moving said rolls forward being supplied solely by said tracks through their frictional engagement with the peripheries of the rolls, forwardly biased means for moving said blank forward, and means periodically stopping said forwardly biased means.

8. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage slidably disposed in said track housing between said tracks, a pair of rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming .a pass for receiving an elongate metal blank, means for reciprocating said track housing longitudinally to cause said rolls to periodically roll simultaneously toward the front end of the blank and toward eachother to elongate a portion of the blank, the motivating force for moving said rolls forward being supplied solely by said tracks through their frictional engagement with the peripheries of the rolls, forwardly biased means for moving said blank forward, means for stopping said forwardly biased means prior to each working stroke of said rolls, and means for clamping said blank in fixed position when its forward movement is thus arrested.

9. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage disposed in said track housing between said tracks, a pair of rolls carried in said carriage in frictional engagement with said tracks and forming a pass for receiving a metal blank, means for reciprocating said track housing longitudinally of said blank to cause said track surfaces to periodically roll the rolls simultaneously toward the front end of the blank and toward each other to reduce and elongate an increment of the blank, sprockets mounted on the ends of said rolls, means anchored at one end and meshing with said sprockets, means'for holding the unrolled portion of the blank in fixed position during each blank-reducing step, and means for periodically advancing successive unrolled increments of said blank into the roll pass.

10. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage disposed in said track housing between said tracks, a pair of rolls carried in said carriage in frictional engagement with said tracks and forming a pass forreceiving a metal blank, means for reciprocating said track housing longitudinally of said blank to cause said track surfaces to periodically roll the rolls simultaneously toward the front end of the blank and toward each other to reduce and elongate an increment of the blank, sprockets mounted on the with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage disposed in said track housing between said tracks, a pair of rolls carried in said carriage in frictional engagement with said tracks and forming a pass for receiving a metal blank, means for reciprocating said track housing longitudinally of said blank to cause said track surfaces to periodically roll the rolls simultaneously toward the front end of the blank and toward each other to reduce and elongate an increment of the blank, sprockets mounted on the ends of said rolls, chains anchored at one end behind said track housing, and meshing with said sprockets, resilient means for connecting the opposite ends of the chains to said track housing, and means for periodically advancing successive unrolled increments of said blank into the roll pass.

12. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage slidably disposed in said track housing between said tracks, a'pair of rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming a pass for receiving an elongate metal blank, means for reciprocating said track housing longitudinally to cause said rolls to periodically roll simultaneously toward the front end of the blank and toward each other to elongate a portion of the blank, a cylinder disposed behind said blank,

, a piston disposed in the cylinder and connected to the rear end of the blank, fluid under pressure in said cylinder behind the piston for biasing it forward, fluid in the cylinder in front of the piston for limiting forward movement of the piston, and means for periodically releasing a predetermined amount of said last-mentioned fluid from the cylinder to permit the piston to move forward.

13. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage slidably disposed in said track housing between said tracks, a pair of rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming a pass for receiving an elongate metal blank, means for reciprocating said track housing longitudinally tocause said rolls to periodically roll simultaneouslytoward the front end of the blank and toward each other to elongate a portion of the blank, 2. cylinder disposed behind said blank, a piston disposed in the cylinder and connected to the rear end of the blank, fluid under pressure in said cylinder behind the piston for biasing it forward, fluid in the cylinder in front of the piston for limiting forward movement of the piston, a shut-off valve connected to the front end of the cylinder, and means actuated by "said track housing for periodically opening said valve to release fluid from in front of said piston.

14. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage slidably disposed in said track housing between said tracks, a pair of rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming a pass for receiving an elongate metal blank, means for reciprocating said track housing longitudinally tocause said rolls to periodically roll simultaneously toward the front end of the blankand toward eachpther to elongate a portion of the blank, a cylinder disposed behind said blank, a piston disposed in the cylinder and connected to the rear end of the blank, fluid under pressure in said cylinder behind the piston for biasing it forward, fluid in the cylinder in front of the piston for limiting forward movement of the piston, a shut-off valve connected to the front end of the cylinder, means actuated by said track housing for periodically opening said valve to release fluid from in front of said piston, and an adjustable valve for controlling the volume of fluid released by said shut-off valve each time it is opened.

15. A rolling mill comprising a track housing open from end to end and provided interiorly with a pair of spaced track surfaceshaving substantially parallel areas merging into areas inclined away from each other toward the front of the housing, a carriage slidably disposed in said track housing between said tracks, a pair of rolls rotatably mounted in said carriage in frictional engagement with said tracks and forming a pass for receiving an elongate metal blank, me ms for reciprocating said track housing longitudinally to cause said rolls to periodically roll simultaneously toward the front end of the blank and toward each other to elongate a portion of the blank, forwardly biased means for moving said blank forward, means for stopping said forwardly biased means prior to each working stroke of said rolls, a support over which said blank passes, and fluid pressure actuated means for periodically clamping the blank to said support.

16. A rolling mill comprising a track member, a floating roll disposed with its periphery in frictional engagement therewith, means adjacent the opposite side of said roll for forming with the roll a pass for receiving a metal blank, means for effecting relative longitudinal reciprocable move- -ment between said track and blank to cause said roll to periodically roll simultaneously on the blank toward its entering end and toward said adjacent means to reduce and elongate a portion of the blank, the rotation of the roll being controlled principally by its frictional engagement with the track and blank, means for holding said track and the unrolled portion of the blank against movement in the same direction during the blank-reducing steps, and means for periodically subjecting successive unrolled increments of said blank to the action of said roll whereby to periodically roll successive portions of the blank.

1'7. A rolling mill comprising a track member, a floating roll disposed with its periphery in frictional engagement therewith, means adjacent the opposite side of said roll for forming with the roll a pass for receiving a metal blank, means for reciprocating said track longitudinally of the blank to cause said roll to periodically roll simultaneously toward the entering end of the blank and toward said adjacent means to reduce and elongate an increment of the blank, the motivating force for moving said roll toward the entering end of the blank being supplied solely by said track through its frictional engagement with the periphery of the roll, and. means for periodically advancing successive unrolled increments of said blank into the roll pass between reducing strokes of said roll.

18. A rolling mill comprising a housing open from end to end and provided interiorly with a pair of spaced track surfaces having substantially parallel areas merging into areas inclined away from each other toward the exit end of the housing, a pair of rolls rotatably mounted between said track surfaces in frictional engagement therewith, said rolls forming a pass for receiving a metal blank, means for effecting relative longitudinal reciprocable movement between said housing and blank to cause said rolls to periodically roll simultaneously on the blank toward its entering end and toward each other to reduce and elongate a portion of the blank, the axes of the rolls being'free to accommodate themselves to the relative speeds of the tracks and blank, and means for periodically subjecting successive unrolled increments of said blank to. the action of said rolls whereby to periodically roll successive portions of the blank.

FRANK R. KRAUSE.