US2353288A - Apparatus for rolling strip metal - Google Patents

Description

R. G. BENNEWITZ APPARATUS ROLLING STRIP METAL Jul 11, 1944.

e Sheets-Sheet 1 Filed Aug. 3, 1940 July 11, 1944. R. G. BENNEWITZ APPARATUS FOR ROLLING STRIP METAL Filed Aug. 3, 1940 6 Sheets-Sheet 2 w w a Q mgmmm 2 w n w 0 M wwflw. w 2, a F F a INVENTOR. lF/(i/fA/FO C. BEAM 5W1 rz.

BY C l -m4 ATTORNEY) y 1944. r' z. G. BENNEIWITZ 7 2,353,238 Y APPARATUS FOR ROLLING STRIP METAL Filed Aug. 5, 1940 e Sheets-Sheet 3 1|]; r |l I ATTORNEY-5 July 11, 1944.

R. G. BENNEWITZ 2,353,288

APPARATUS FOR ROLLING STRIP METAL Filed Aug. 5, 1940 6 Sheets-Sheet 4 y? i 40 m/ 104 1w INVENTOR. Zf cy.9. BY Bag/1R GEENNEW/TZ. "M 0005;

ATTORNEYS July 11, 1944. R. G. BENNEWITZ APPARATUS FOR ROLLING STRIP METAL Filed Aug. 3, 1940 6 Sheets-Sheet 6 INVENTOR. c/Mw ffiz/wvzw/rz.

ATTORNEYS /P/ BY a y nu! reason, that the working rolls must rolls so aligned with the backing Patented July 11, 1944 2,353,288 APPARATUS FOR ROLLING STRIP METAL Richard G.Bennewitz,

to Crucible Steel York, N. Y.,

Jersey City, N. 1., asslgnor Company of America, New a corporation 01' New Jersey I Application August 3, 1940, Serial No. 350,789

' 3 Claims. .(CI. 80-32) This invention relates to improvements in method and apparatus for cold drawing and rolling metal strip, bars and the like.

Apparatus for cold rolling metal strip has heretofore been devised, in which the strip is pulled between a pair of relatively small reducing or working rolls, each backed by an antifrictionally supported backing roll of much larger diameter, the axes of the four rolls all being in a, common plane which is perpendicular to the direction of movement of the strip, this constituting the socalled "4-high construction. This construction, however, is subject to a number of disadvantageous andundesirable features as follows. Owing to the fact that the working rolls are backed only in a direction perpendicular to the direction of rolling, but are unbacked or 'unsupported iu the direction of rolling, they are,

subjected to lateral ilexure or bending in this direction due to the pull exerted by the strip, such as is productive of a strip of non-uniform transverse thickness, and produces riiliing at the edges. To minimize this tendency the working rolls must be made relatively large and the diameter of the backing rolls correspondingly increased to maintain their appropriate dimensions in relation to the working rolls. These large working rolls diminish the maximum reduction or "bite that can be employed during rolling, while the combination of large working and backing rolls greatly increases, the overall dimensions, weight and cost of the mill. Moreover, with the 4-high construction, although ing rolls may be provided with antifriction bearings, such as roller bearings, this cannot be done with the working rolls due, for one reason, to lack of space and also, for the more important be set up tightly in split friction bearings, of babbitt or the like, to hold the working rolls rigidly in line as required with the backing-rolls, andin order to make the requisite adjustments from time to time during rolling, to maintain the working rolls. Antifriction bearings, such as roll or ball bearings,

v could notbe employed for the working rolls in the 4-high construction, inasmuch as the play in the bearings thus introduced would cause misalignment of the working and backing rolls and thus produce riiliing, buckling and non-uniform thickness of the strip. The fact that the working rollsmust be thus tightly set-up in split friction bearings in the 4-high construction entails the further disadvantage that a steady flow of' lubrication is required on the roll necks in order the backto prevent over-heating-of the bearings and roll necks. Owing to this heated oil splashing on the strip, it is impossible to produce a ing a bright lustrous finish.

It is also known to construct cold rolling mills with a pair of working rolls each of which E backed by a pair of spaced backing rolls having-their axes in a plane parallel to the strip and each bearing against the associated working roll, the so-called cluster construction. In mills of this type which have been heretofore devised, however, the working rolls have been directly driven through drive shafts connected thereto through wobblers or the like. Owing to the drive thus applied directly to the working rolls, these rolls must be made relatively heavy to minimize the resulting tendency for lateral deflection thereof, and the backing rolls must be made correspondingly larger and heavier than would otherwise be required in order to preserve the proper relative sizes of the working and backing rolls. Also the working rolls must be made sumciently large so that such driving connections can be made thereto. To further minimize this lateral deflection and displacement of the working rolls, they must again be tightly set up in split friction bearings, requiring'heavy and continuous lubrication during op-' eration to prevent overheating, with the resulting disadvantages above noted for the 4-high construction. Likewise, with this type of mill, it is diflicult to roll strip of uniform cross-sectional thickness with a high degree'of rapidity and with no riiiiing or buckling of the strip, and for the same reasons explained in connection with the 4-high construction.

In accordance with applicant's invention, the cluster arrangement ing rolls is employed, i. e., each of a pair of working rolls is backed by a pair of spaced-backing rolls bearing against the same, but with this .pelled entirely by important distinction over the previous types of cluster mill constructions, that the working rolls are not themselves driven, but are merely cradled between and backed by their associatedbacking rolls. The strip or bar being rolled, is protension applied to the strip or'bar, i. e., the material being rolled is pulled through th mill. Owing to the fact that each working roll is cradled between and backed by a pair of backing rolls, and thus automatically maintained in proper alignment thereby, and owing tothe further fact that no drive is'applied to the working rolls, no bearings, other than loose thrust bearings, are required for the working strip havof the working and backi rolls. The working rolls are thus supported exclusively by the backing rolls in rolling contact therewith. Accordingly, the working rolls are subject to no over-heating or frictional drag, such as is produced in prior constructions due to the friction bearings required. Also since, as stated, each working roll is cradled and automatically aligned between a pair of backing rolls in contrast to the vertical roll arrangement of the 4-high construction, and since the working rolls are not themselves directly driven, as in the case of the prior cluster mill constructions, the working rolls of applicant's construction are not subject to fiexure in the direction of rolling, as is the case with prior constructions. The working rolls and their'associated backing rolls may accordingly be made much smaller thanv in the prior types of 4-high" or cluster" mills, thereby greatly reducing the overall dimensions, weight and'cost of the mill for any given size of stock to be rolled. The smaller working'rolls which can thus be employed permit of reducing the stock to the desired dimensions in fewer passes than previously, due to the increased bite that can be employed effectively. Rolling costs are thus reduced and a superior product obtained.

Further in accordance with applicant's construction, the backing rolls are mountedin antifriction bearings, such as roller bearings. Owing to this fact and the fact that no bearings are required for the working rolls, the bearing losses for the entire mill are reduced to such a point that the strip or bar may be rolled exclusively by tension applied thereto, i. e., by pulling the strip or bar through'the mill and without danger of rupturing the stock. The friction losses are in fact so small that the stock can be rapidly reduced at a relatively high rate of speed, for example as high as 1500 feet per minute.

Applicant's construction has the advantage over the prior 4-high and cluster mills, that it can be employed for drawing and rolling special shapes, such as the conversion of round. bars into square, hexagon, etc., shaped rods, or the reduction in cross-sectional area of round, square, hexagon, etc., shaped bars while maintainin In the drawings:

Fig. 1 is a, plan view; Fig. 2 a view in front elevation and Fig. 3 a view in side elevation of a preferred embodiment of the apparatus of the invention.

Fig. 4 is a view in side elevation illustrating a clutch mechanism for connecting one of the re-' versing reels of the apparatus of Fig. 1, to its associated driving motor.

Fig. 5 is a, transverse sectional elevation through the reducing and backing rolls and appurtenant parts, illustrating the manner in which the reducing rolls -are cradled between and supported by the backing rolls.

Fig. 6 is a section at line 6--8 of Fig. 5; Figs. 7 and 8 are sections at line '|I and 3-4 of Fig. 1; Fig. 9 a section at line 9-9 of Fig. 8; and Fig. 10 a section at line Ill-Ill of Fig. 5.

Fig. 11 is. an enlarged fragmentary view in side elevation corresponding to Fig. 2, showing the reducing rolls and associated guides for guiding the strip therebetween, one of the guides being shown in partial section; while Figs. 12 and 13 are sections at lines l2-l2 and l3 l3 respectively of Fig. 11; and Fig. 14 is a section at line I l-l4 of Fig. 1.

Referring now to the assembly views, Figs. 1, 2 and -3, the particular embodiment of the apparatus here shown may comprise generally a rolling mill head through which the strip material as at 2|, which is to be reduced, may be passed either continuously in one direction, or alternately in one direction and then in the other, as it is wound or unwound from reels 22, 23. These reels may be driven by electric motors as at 23, connected through clutches as at 28, 21, and reduction gearing of suitable known type 23, 23 to the shafts 30, 3| carrying the reels 22, 23 respectively.

Suitable brakes 32, for example, hydraulic brakes operating on the Alden dynamometer principle, according to which their contour unchanged. This is accomplished by the use of work rolls having appropriately shaped grooves therein, such as V notches, etc., or more preferably by the use of built-up work rolls consisting of hardened and ground washers of appropriate contour. The self-aligning feature of the work rolls makes it possible to use such built-up rolls since roll necks and bearings are not required. Also with applicants construction,

it is possible to roll special edges on flat strips, by attaching an edge roll table to each end of the roll head. With this edge-rolling operation, it is possible to produce round, square or beveled shapes with a cold rolled finish, both on the flat portion of the strip as well as on the edges. Such .rolling. operations could not be carried out on.

the known types of 4-high and cluster mills.

Various further and more specific objects, features and advantages of the invention will'appear from the detailed description given below, taken in connection with the accompanying drawings forming a partof this specification and illustrating merely by way of example certain embodiments of the invention The invention consists in such novel features, methods, arrangements and combinations of parts as are shown and describe herein.

a braking action is provided by hydrostatic pressure due to the continuous flow of water, oil, etc.,

through a restricted orifice, whereby frictionally produced heat is carried away by the continuous flow of the liquid as the braking pressure is applied, may be connected or mounted upon the shafts 30, 3|. Thus, for exampb, when the motor 24 is connected through clutch 23, the strip will be pulled through the mill head from reel 23 onto reel 22. During this operation, the strip is placed under considerable tension of about one-third to one-half of the elastic limit, as a result of the pull exerted by motor 24 and the back tension applied by brake 33, thereby greatly facilitating the rapid reduction in thickness of the strip without necessity for frequent reannealing. When the strip has been thus completely passed through the mill and wound up on reel 22, the operation is reversed, motor 25 being actuated through clutch 21 to drive the-strip in the opposite direction, while back tension is applied by brake 32. In this way, the thickness of the strip may be rapidly reduced to deslredgauge in successive passes. 4 4

The mill-head 20 includes a main frame or housing 34 (Figs. 2 and 3) mounted upon a pedestal 35. Within main frame 34, the working and backing rolls are assembled and mounted in the manner shown more particularly in Figs. 5 to 10'inc., referred to indetail hereinafter, it being sufllcient at this point to merely indicate the 33 of known construction,

backed by a pair of backing rolls 60, 6! or", 63.-

The backing rolls which are positioned above the strip may be supported in bearing housings 36, 36' (Figs. 2, 7, 8), similar bearing housings 31, 31' being provided for the backing rolls positioned below the strip. The housings 31, 31' may rest upon or be secured to the base of the outer housing 34 and retained against endwise movement therein, as by locking plates 38. The bearing housings 36, 36 may be similarly mounted within the housing frame 34 and retained by plates 39 against endwise displacement. How ever, the bearing housings 36, 36' are so mounted ing roll without requiring the use of any bearings on the latter. In this way the reducing roll is constantly self-aligning and positively supported in a. single predetermined position and prevented from bending despite the powerful and variable pulling forces lengthwise of the strip, and despite severe and variable vertical pressures due to the engagement of the reducing rolls with the strip.

as to be slidably adjustable vertically so as be able to adiust the size of the "pass for-the],

strip between the reducing rolls. adjustment may be accomplished as by the use of two cooperating pairs of Wedge blocks 40,4! and 40', 4|, hereinafter described in further detail.

In Fig. 2 the ends of two cooperating reducing rolls may be seen at 42, 43, the detailed construction of which will hereinafter be explained in connection with Fig. 10. Means for guiding the strip to and from the reducing rolls may also be seen at 44, 45, and the novel features thereof will be hereinafter described in connection with Figs. 5, 11, 12 and 13. Thumb nuts for adjusting same appear in Fig. 2 at 46, 41.

As shown in Figs. l-3, the strip 2| in its travel to and from the mill head at each side thereof, may pass over Water-cooled drums 48, 49, suitably journaled at the opposite ends of the pedestal 35 and provided with water inlet and outlet connections 50, Also as indicated in Figs. 1 and 2, the strip may be passed through suitable Wipers as at 52, 53, the same being shown in further detail in Fig. 14. For example, each wiper assembly may comprise a pair of felt pads 54, 55, engaging the upper and lower surfaces of the strip 2|, the lower pad being supported upon a base member 56 and the upper pad upon a bar 51. The pressure of the pads upon the strip/may be adjusted as by a hand wheel 58 acting upon the bar 51 against the pressure of springs 59 in a manner which will be apparent from Fig. 14.

The relative positions of the reducing rolls and backing rolls in respect to the path of travel of the strip 2| will be apparent from Fig. 5. The small reducing roll 42 is here shown as accom Danied by two backing rolls 60, 6| of larger diameter and so placed as to form a cradle-like support for the reducing roll. Upper backing rolls 62, 63 similarly provide a cradle-like backing for 'the small upper reducing roll 43. Thus each reducing roll under the pressure of its ene gagement with the strip'2l has its alignment maintained and determined by the tangential contacts with two backing rolls so positioned an- Such vertical gularly about the reducing roll that the latter point support of each axial section of the reducis maintained against flexing or bending and the ticable heretofore in-the i-high type of mill construction. And with such smaller reducing rolls a deeper bite-may be taken in the strip being rolled, with less pulling power on the strip and consequently with lower operating expense and with no danger of tearing the strip. The action of the smaller roll on the strip is also such that greater reductions of the strip may be accomplished following each annealing of the strip and before it has to be again annealed for further reductions.

In'the 4-highl type of rolling millit is neces: sary to provide the reducing rolls with friction type split bearings to retain the rolls against displacement in the direction of movement of the strip being rolled, since the backing r011 merely contacts with the reducing roll at a position diametrically opposite from the engagement with the strip. The use of such friction bearings involvesa number of seriousdifliculties. For example, such bearings will at least in a large measure determine the alignment of the reducing roll independently of the backing roll, with the result that the contact pressure between the two rolls will vary from point to point and vary at different times depending upon the forces applied from engagement with the strip and the inaccuracies in' bearing aligmnent. Thus, to. avoid prohibitive misalignment, fiexures of the reducing roll, and defects in the rolled strip, all of the rolls as well as the anti-friction bearings for the backing rolls, must be large, heavy and space-consuming. And it is necessary to make frequent adjustments of such split bearings,

sometimes during operation of the machine, to maintain the reducing roll in proper alignment. On the other hand; with the construction of this invention, each of the reducing rolls is cradled by two backing rolls and thus being self-aligned, maybe ieft'free of any bearings (except for small thrust bearings to prevent endwise displacement, as hereinafter described). Thus the difficulties of the friction type split bearings required in 4- high mills are eliminated.

In the -high type of mill the friction type reducing roll bearings must tightly engage the roll necksto prevent play and consequent riffling and buckling of the strip. Anti-friction roller or ball bearings could not be used because of play afforded, particularly in directions lengthwise of the moving strip, and furthermore, because with the adjacent large anti-friction bearings and bearing housings for the backing rolls, there is insufllcient space for anti-friction bearings on the'reducing roll. The use of such friction type bearings not only involves a large power loss, but also necessitates a. continuous flow of oil over the split bearings and the roll necks. Thus a. steady flow of lubricating oil from the rollnecks extends over'the working surfaces of the reducing rolls, with the result that a bright finish cannot be obtainedon the rolled strip. on the other hand, with'the elimithe diameter of the backing roll of the old type i-high mill, even with working rolls of considerably smaller diameter. This may be accounted for by the cradle-like support afforded by the two backing rolls and the avoidance of the relatively long reducing roll necks heretofore necessary for bearing purposes, but having upon flexure against the bearings, such bending forces upon the rolls as to require larger rolls.

The reductions insize of the working and backing rolls as well as the triangular arrangement of each group thereof, makes possible a much more compact machine both as to height and width. I have found in practice that such a machine is capable of accomplishing the same work as a typical ii-high mill of the old type, but at a faster rate with strip speeds up to 1500 feet per minute for the cold reduction of high carbon and alloy shapes and flats. For a 6" strip milul, for example, over half of the weight, and over 80% of the cost may be avoided in the construction of such a mill as compared with a typical mill of the 4-high construction. And due to the accurate self-aligning of the reducing rolls, the use of small rolls and the improved bite-of the reducing rolls, a 6" strip mill such as illustrated in the drawings may be operated for example by 75 H. P. as contrasted with 200 H. P. required. for a corresponding i-high" mill of the old construction.

The details of the arrangement of the reducing rolls and of the bearings for backing roll 6| are shown in Fig. 10. It will be understood that the other backing rolls, 60, 92 and 63 may be similarly mounted. As here shown, each end of the backing roll 6| may be supported in a large anti-friction bearing of the self-aligning roller type, including inner bearing races as at 64 embracing backing roll necks 95, and outer bearing races as at 89 secured in outer bearing rings as at 61. These bearing rings may be secured within the bearing housings ll, 31' against turning, as by pins 88. The roller bearings are shown as at 89 between the inner and outer bearing races. Packing rings formed, for example, of a suitable artificial rubber composition,

ports for the thrust bearings may be retained against turning as by pins 90.

As above indicated, the reducing rolls are left free for self-alignment by contact with the backing rolls and the work, and therefore need merely to 'be provided with small thrust hearings to retain the reducing rolls in proper adjustment endwise. Such thrust bearings are shown in Fig. 10 at 8! mounted in bearing housings as at 82 and provided with sealing rings 83 of artificial rubber or equivalent material. The bearings housings 82 are free to assume positions vertically as determined by contacts of the backing rolls with the reducing roll. The adjustment of these bearing housings in directions endwise of the roll may be effected as by thrust adjusting screws 85, provided with operating knobs 95 and locking knobs 81. The inner ends of the adjusting screws 9! have threadedv engagement with thrust blocks 98, which in turn abut and loosely embrace the sides of bearing housings 82 with sufllcient play to permit the reducing roll alignment to be freely determined 'by the backing rolls (Fig. 6) The outer ends of the adjusting screws 85 may be of reduced diameter as shown to provide shoulders 89 for engaging thrust plates 90. The thrust blocks 88 and plates 90 may be mounted for slida'ble adjustment, for example, in grooves or channels 84 formed in th upper surfaces of bearing housing members 31, 31. The plates 90 may be slid into place along the channels 84 and then held against outward movement by thrust latch members as at 9| (Fig. 10 and middle of Fig. 11). The members 9| may comprise a collar portion for surrounding one of the screw members 85 and also two radially extending arms as appear in Fig. 11. The outer ends of these arms when the 1 latch member is in position, are adapted to enare shown at 10 interposed between the bearing housings and shoulders as at H formed at each end of the backing roll.

Each end of each of the backing rolls may also be provided with an anti-friction roller type thrust bearing having inner and outer race rings as at I2, I9 with the roller bearings as at 14 therebetween. Each of the rings 13 may engage a backing ring as at IS, the latter in turnbein received in cup-like casing members as at I6 adapted to be engaged by adjusting'screws 11 mounted in the housing members 91, 31' and affording means for giving the backing roll its proper endwise adjustment. Lubrication for the backing roll bearings maybe provided as through oil inlet and outlet pipes ll, I9 communicatinz with cavities and spaces in and around the bearings in a manner apparent in Fig. 10. The sup,-

'gage protruding portions as at 92, 93 formed on 40- the main bearing housing members at either side of the channel 84. But when the thrust assembly is being inserted along the channel, the latch member 9i may 'be turned as indicated by the dot and dash lines in Fig. 11 to a position permitting one of its arms to enter as through a cut-out por- Turntion 94 of the bearing housing'member. ing of the latch member 9| may be limited as by pins 95, 96 mounted'in thrust plate 90. The locking knobs 81 may bear against thrust collars 91 which in turn bear against and form bearings for latch members 9|, whereby the parts between the locking knobs 81 and the shoulders 89 may be brought under pressure by the locking knobs to secure the screw members 85 against turning aiter adjustments are made. It will ments, by turning the screws 95 the thrust bloc 98 may be forced toward the end of the reducing roll through pressure applied to the screw members 95 by the latch members 9! acting through thrust plates 90 on the shoulders 89 of the screw members. 'The above described means for endwise adjustment of the lower reducing roll 92 may be in general substantially duplicated for the'upper reducing roll 43, as will be seen from Fig. 8.

The details of the mechanism for supporting and adjusting vertically the position of the upper bearing housings I8, 36" will now be described members I22 suitable turnbuckle member as at I04 having an eyelet and pin or rod attachment I05 to the wedge block 40 or 40' (Fig. 5). This attachment (Fig. '1) may be made as bya rod I06 having ball shaped ends extending respectively into suitable apertures in the wedge members 40, 40'. The upper end of the spring cylinder I02 may be adjustably secured to the top of the main frame 34' as by a suitably threaded member I01.

As thus far described, it will the bearing housings 36, 36' and wedge blocks 40,40, and consequently also the rolls 62 and 63, are allso supported by the springs I03 as to be pulled upwardly to increase the gap or pass between the reducing rolls 42, 43. On the other hand, the wedge block-s 4|, 4| are so shaped as to limit this upward movement" to an extent depending upon the endwise adjustment of the wedge blocks 4|, 4|. Such adjustment may be effected by lead'screws as at I08 extending horizontally through wedge blocks 4|, 4| in threaded engagement therewith, and mounted at their ends in suitable bearings in the sides'of the main frame or housing 34. The screw rods I08 may be turned by large gear wheels as at I09 (Fig. 9)., which in turn may engage a pinion I I0 (Fig. 2). The pinion IIO may be operated as by a hand wheel I I I, or automatically bya motor 2 connected through reduction gearing II3, pinions H4 and a suitable clutch II5. Thus, either by manual operation of the wheel III or by means of the motor II2, the upper reducing roll and its backing rolls and the supporting structure therefor may be quickly and conveniently adjusted vertically as required, to provide the proper pass for the strip being rolled. Y

Means for guiding the strip to and from the working rolls will now be described. In each guide assembly the upper and lower surfaces of the moving strip may be engaged between a pair of relatively long wooden blocks as at H6, H1 formed of hard wood such as maple and having faces of suitable width and shape to enga e the particular strip being rolled (Figs. 12, 13). The

. lower block may be carried by a supporting plate as at I I8, which in turn may be carried by a plube apparent that.

I of guide rollers rality of supporting pins as at I I 3 extending down through the bearing housing members 31, 31"

(Figs. 11, 5, 7). and adjustable vertically by small cam members I20 mounted upon horizontal rods as at I2I. may be supported 'by and pressed down upon the surface of the strip being rolled as by clamping attached as by screws I23. The vertical positions of the clamping members I22 may be yieldably and adjustably retained by devices as shown in Fig. 5, including bell crank members I24 pivoted on the main frame as-by rods I25, and having-outer arms pivotally connected to pins as at I20, the upper ends of which pins are provided with adjustable thumb nuts as at 46, 41, acting against supporting brackets as at I21. Springs as at I28 may be interposed on the pins I2i between said brackets and the members I24.

The above described wooden guides and the supports therefor thus provide an eifective means for straightening and properly guiding the strip to be rolled to and from the working rolls in such manner that buckling and bending of the strip are avoided. And the supports for the The upper wooden guide members II1 ers as at I30, preferably having anti-friction bearings, may be mounted along each side oi the strip adjacent the guide blocks H6, H1 (Figs.

6, 12, 13). These rollers may be mounted in supports as at I3I, I32 carried by the supporting plate H0. The position of the supports I3I, I 32 relative to the edges of the strip, may be adjusted in the horizontal direction as by a lead screw I33 having oppositely threaded portions in threaded engagement respectively with the members I3I, I32, 'as appears in Fig. 12. This lead screw I33 also serves to attach or secure the members I3I, I32 in respect to the plate H8. The ends of the screw member I33 respectively may be mounted by suitable bearing means as at I34, I35 respectively, permitting the screw to be turned by a thumb screw I36, but preventing its displacement endwise. A locking thumb screw I31 may also be provided to act in a manner apparent from Fig. 12. Thus, by merely turning the knob I38, the positions of each group I30 at each. side of the strip may be simultaneously adjusted to move the two groups of rollers an equal amount in opposite directions, thusinsuring the maintenance of accurate centering of the strip despite adjustments of the pressure of the rollers against each edge or side of the strip. This afl'ords an important advantage, permitting the guide rollers to be conveniently and properly adjusted from time to time during the operation of the rolling mill, as may be required. Plates H8 and the supporting members I3I, I32 may be formed at their opposed faces with a cooperating tongue and groove construction as shown at I30, for guiding members I3I, I32 during adjustment without jamming. Other tongue and groove constructions for like purposes may also be provided at each side of the screw I33 as shown at I39, I40 in Fig. 11. v

The mill head as above described may if desired be used in conjunction with edge roll tables at both ends of the mill, making it possible to roll strips of round or square cross sections or with beveled edges. Also if desired, the above described rolling head may be attached to a socallai draw bench or draw block when it is desired to roll special shapes. In this event suitable grooves may be ground in the working rolls or the working rolls may be built up from a plurality of suitably shaped collars'mountecl upon a v allow for these adjustments desiredtobeserolling of metal strip, said apparatus including a pair of work engaging rolls of relatively small diameter, each of said rolls being cradled between and in peripheral roiling engagement with a pair of backing rolls of larger diameter, said work engaging rolls being substantially free of radial bearing guidance except as provided by said backing rolls, anti-friction bearings supporting each of said backing rolls, said work-engaging and backing rolls being idle rolls, and devices for applying tension to the strip to pull the same .between said work eng ing rolls and rotate all of said rolls. I

2. Apparatus oi the class described for the cold rolling of metal strip, said apparatus including a pair of work engaging rolls of relatively small diameter, a pair of backing rolls of larger diameter for each of said work rolls, anti-friction bearings supporting the end portions of said backing rolls, said work rolls respectively being cradled between and in peripheral engagement with their respective backing rolls at points between the aforesaid bearings, said work engaging rolls being'substantially free of radial bearing guidance except as provided by said backing rolls, said work engaging and backing rolls being idle rolls,

and devices for applying tension to the strip to pull the same between said work engaging rolls and rotate all oi said rolls.

3. Apparatus of the class described for the cold rolling of metal strip, said apparatus including a pair oi work engaging rolls of relatively small diameter, each of said rolls being cradled between and in peripheral rolling engagement with a pair of backing mils of larger diameter, said work engaging rolls being substantially tree of.

radial bearing guidance except as provided by said backing rolls, anti-iriction bearings supporting each of said backing rolls, said work-engaging and backing rolls being idle rolls, said work engaging rolls having thrust bearings engaging the end portions thereof which are constructed and arranged to suppress emdwise movements thereof, but to afford relative movement of one c! said work engaging rolls toward and from the other, and devices for applying tension to the strip to pull the same between said work engaging rolls and rotate all of the aforesaid rolls G. BENNEWIIZ

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