US2160767A - Apparatus for rolling sheet metal - Google Patents

Description

F. o. wADswoRTH 2,160,767

' APPARATUS FOR ROLLING SHEET METAL May 30, 1939.

7 sheets-sheet 1 Filed Sept. 6, 1935 Hll lll/

May 30 1939 l v l F. L.. o. wADswoR-rH 2,160,767

APPARATUS FOR ROLLING SHEELI METAL Filed Sept. 6, 1935 7 Sheets-Sheet 3 May 30, 1939. F. 1 o. wADswoRTH 2,160,767

APPARATUS FOR ROLLING SHEET METAL l Filed Sept. 6, 1955 '7 Sheets-Sheet 4 7 sheets-sheet 5 Filed Sept. 6, 1935 I s l v F. L. o. wADswoRTH APPARATUS FOR ROLLING SHEET METAL May 30, 1939.

May 30, 1939. F. L. o. wA-DswoRTH 2,160,767

FPARATUS FOR ROLLING SHEET METAL l Filed sept. e, 1935'. 7 sheets-sheet 6 Eg vmmf AMay 30, 1939.

F. 1 .l o. wADswoRTH APPARATUS FOR ROLLING SHEET METAL Filed Sept. 6, 14955 Eg. m.

j NVE NTOR Patented May-30, l1939 l PATENTv OFFICE APARATUSFOR ROLLING' SHEET METAL Frank L. 0. Wadsworth, Pittsburgh, Pa.; Mildred I administ M. Wadsworth ratrix oLFrank L. 0.

Application September 6, 19.35, Serial No. 39,437

v14 Claims.

My invention relates to the art of rolling metal, and, broadly stated, the purpose of my improvements is`to concurrently increase the eifectiveness, and reduce the cost, ofth'is operation, par- 5 ticularly'in connection with the production of ,strip and siieet' products.

It is well known to rolling mill engineers that the reactive' pressure onl the rolls, and -the amount of power required to drive-them are both l dependent on `the diameter of the'working surfaces, or,'more accurately stated, on the zonal arc of contact'between them and the material on which they are operating; and that a decrease in4 this arc of vcontact-within the limits l5 imposed byj securing theV necessary pull l 'or" biteis accompanied` by many advantages. But it-has heretofore been found to be impossible to reduce the sizeof the roll elements below a certain value because of the torsional and transverse bendingstresses to which they are subjected and because oi. their resultant angular and lateral distortion. 'I'he last of these two dimculties may be overcome, or avoided, in part, by the use of a proper arrangement of large backing rollsas exemplied in four high and cluster mills-but the first mentioned obstacle toa reduction in roll diameter has not, as far as I am aware, been previously removed.

It is the object of my present invention to elim-J inate, in whole or in large part, both of the diillculties above outlined; and to make it possible to make usel of working rolls, which are, proportionally, of much smaller sizethan have heretofore been employedL in plate (sheet or strip) rolling; and which can be. operated more effectively and eicle'ntly than the larger working elements.V

I accomplish these results by a combination of an improved system of backing rolls-to withstand both vertical and horizontal stresses o n the working rolls-with a new method of driv- 40 ing these elements whereby an equalivzed, or automatically balanced, torque is applied to both endsV of e'ach of the working rolls, and a uniform- 1y distributed driving force is alsol applied to, .and through their entire length of contact with the material; and all tendencies to either bend orftwist the'smali roll members are successfully resisted, or substantially eliminated.

'I'he manner invvwhich I apply power to'the w working rolls of my improved mill diilers from that `of present day practice in two major, and -onejminor respect. I apply a positive gear drive to both ends of eachworking roll, and automatically -balance, or equalize, the dual torque, thus u exerted, by using reversely cut helical gears at the opposite ends of the driven members, which are left free to move axially until the pressures on the oppositely inclined gear teeth'are substantially the same; and I also apply a uniformly distributed friction drive to the entire length 5 ofthe working rolls, which is sufiicient in itself to eil'ect their desired movement during the rolling operation. I obtain this last described characteristic of driving action by applying the main V source of power to the large backing rolls of the 10 mill, and positively connecting 'these driven members to theuworking rolls-through the use of the helical gears above mentioned-so that theseA intergeared elements are revolved at the same peripheral speed, and any circumferential 16 slip between their engaged faces is prevented.A

Under such circumstances the coeillcient of trac-v tion (friction) between the driving and the drivenroll elements is much higher than when such slip is permitted; and is, in eifect, equal to the 20 coeillcient of static friction between metal Isurfaces. For steel-on-steel this coeilicient varies from 0.25 to 0.5 according to the degree of pressure engagement and the condition of the engaged surfaces (wet orv dry etc); and under the 25 average conditions of rolling mill work it may be taken as at least 0.25. The horsepower that may be transmitted to the working roll by its nonslipping frictional engagement with the positively driven backing roll is, under these condi- 30 tions H.P.= M PSA/53W where P is the total pressure of the working roll on` the backing roll (or rolls) and S is the peripheral speed in feet per minute.

In cold rolling of strip and sheet productsthe pressure P varies from 5,000 to 35,000 (or more) lbs. per inch of width. of the material-according to the percentage of reduction at each passand the speed S varies from 300 to 900 (or more) ft. per minute. For a mean pressure of 20,000 lbs. and a mean speed of 600 ft. per minute the horsepower that may be transmitted to the two (upper and lower) working. rolls from the two corresponding backing' rolls (by the non-slipping frictional engagement between them) bey comes Y mission of power, by the non-slipping frietional engagement of the positively driven backing rolls with the working rolls, is, of course, independent of the size of the latter; and thus permits the use of working rolls of very small diameter; and since this driving action is uniformly distributed over the entire operative length of the working rolls any tendency to twist the latter is substantially eliminated.

Another object of this invention is to dispense with all ball or roller bearings for either the working or the backing rolls of four high and cluster mills; and to provide improved forms of plain cylindrical bearings therefor, which will have a very low coefllcient of frictional. resistance, and which will be more precise in their control of the thickness of the rolled product, and more uniformly reliable in continuous operation than any anti-friction (sic) bearings of the types now in use. The attainment of this object is facilitated by the employment of my improved plan of driving the working rolls (supra), and the resultant possibility of making these rolls of much smaller diameters than can be otherwise used; because, `as already stated, the decrease in the arc of contact in the rolling operation reducesin a still greater ratio-both the working pressure and the power required to effect a given percentage reduction in the thickness of the rolled product. v

Still another object of these improvements is to provide an arrangement of working and backing rolls-for four high and cluster mills-which will maintain' all of the revolving elements in continuous pressure engagement with each other-regardless of whether material is, or is not, passing through the mill-and which will also permit of the easy removal and replacement of the working rolls without ldisturbing the mounting, or the adjustments of the backing rolls, or of the driving mechanism therefor. An ancillary purpose of my invention is to provide a freely iloating mounting, or support, for the working rolls which will hold the latter in definite andl precise alignment with each other and with the axes of the backing rolls without the use of any end bearings or housings; and without any attendant heating (slight though it may be) o f the usual neck portions of these rolls.

Other objects and advantages of the present improvements will become apparent to those skilled in this art, by the following description of -.several illustrative embodiments thereof, which are illustrated in the accompanying drawings in which: 1

Figure I is an end (or side) elevation of a four high mill which embodies the main structural and operative features of my invention; Fig. II is a vertical sectional elevation on the plane II-II of Fig. I; Fig. III is an enlarged sectional view on the bent piane III--III of Fig. I; Fig. IV is a composite section, (on a much enlarged scale) on the two planes IV and IVa of Fig. III; Fig. V is another sectional view on the plane III-III of Figs. I and VI; and Fig. VI is a transverse section on the plane VI-VI of Fig. V.

Fig. VII is a composite vertical section through a second form of four-high-semi-cluster mill which also embodies my improvements-the right hand half of this view being taken on the plane VII- VII of Fig. VIII, and the left hand portion thereof being taken on the plane VIIa-VIIa of that iigure; Fig. VIII is a reduced scale view, partly in section, on the plane VIII-VIH of Fig.

VII; Fig. IX is a partial section on the plane ancona? IX-IX of Fig. VII; Fig. X is another reduced scale section` on the plane X-X oi.' this same gure: Fig. XI is a side (end) elevation of the mill shown in Figs. VII to X, inclusive; Fig. XII is a partial front view of this same construction; Fig. XIII is a very greatly enlarged section (about one-half fullsize), through the end portion of one of the working rolls (on the plane XIII-XIII of Fig, XI); Fig. XIV and Fig. XV are diagrams showing the arrangement of certain elements of this second illustrative embodiment of my invention, and also indicating an optional change in this organization; and Fig. XVI is another diagram indicating another permissible addition, or supplement, to the construction shown in Figs. I to VI inclusive. Y

Fig. XVII is a side or end view of a cluster mill, which is provided with two pair of main backing rolls, and which exemplifies lanother utilization of my present invention; Fig. XVIII is a composite illustration of the construction shown in Fig. XV'II and is taken at right angles thereto, the right hand portion thereof being a plan view and the left hand portion being a horizontal section on plane XVIII-XVIII of Figure XVII; Fig. XIX is a greatly enlarged section on the plane XIX-XIX of Fig. XVIII; Fig. XX is a partial section on the plane XX--XX of Fig. XVII; Fig. XXI is another partial section on the plane XXI-XXI of this same figure; and Fig. )QUI is VVa partial end elevation of the opposite side o! the assembly shown in Fig. XVII.

Fig. XXIII is a side (end) elevation of a full cluster mill (provided with two pair of main backing rolls of equal size) which constitutes still another embodiment of my improvements; Fig. XXV is a partial section on the plane )DUV- XXIV of Fig. XIUII; Fig. XXV is a fragmentary end view of a part of this construction; Fig. XXVI is an enlarged view of a part of the section shown in Fig. XXIV; Fig. XXVII is a composite vertical section, and elevation on the plane XXVII- XXVII of Fig. XXIII; Fig. XXVIII is a plan view, on a reduced scale, of the construction shown in Figs. XXIII to XXVII, inclusive; and Fig. m is a diagram similar in character to those shown in Figs. XIV, XV, and XVI.

Fig. XXX is a vertical elevation of a mill construction, the right hand portion thereof being an end view and the left hand portion being a vertical section through the rolls intermediate their lengths; Fig. XXXI is a side sectional elevation on the plane HXI-XXXI of Fig. m; Fig. XXXII is a partial front view in elevation of the construction of Fig. XXX; and, Fig. XIQIIII is a semi-diagrammatic showing of a general arrangement cf forming and backing rolls, and of a double system of take-up reels.

The organization illustrated in Figs. I to VI, inclusive, comprises two small working rolls l and 2 a pairI of large backing rolls 3 and 4; and two pair of auxiliary supporting rolls 5 6 and 1 -8. Each of the working rolls (l-2) is provided at both ends with helical gear elements, 9 and I0, which are preferably formed on structurally separate sleeves of a suitable alloy steel, and which are rigidly attached to the body of the roll, so as to form an integrally operative part thereof, in any suitable manner. As here shown each gear sleeve or collar is bored to the standard taper of a Morse drill shank, and is secured to the correspondingly coned end of the roll by three symmetrically positioned keyways and splines and by a clamp nut Il (see Figs. III, IV, and V). The backing rolls 3 and 4 are each made up of a heavy body shell, I2, and axially adjustable bearing sleeve I3, and two end rings, I4 and I3, which are provided with helical gear teeth that are adapted to engage with the gears 3 and I0 on the work rolls I and 2. The inner surfaces of the shell and sleeve members I2 and I3 are 'bored to a slight taper, and are rotatably engaged with the reversely coned surfaces of stationary journal members I6 I3 whose ends are adjustably mounted between the adjacent edges of U-shaped housing pillars, 20-20 and 2I-2I, that form a part of the main supporting frame of the assembly. v'Ihe tapered bearing sleeves, I3 I3, are held in adjusted position with respect to the body shells I2 I2 by means of a circumferentially disposed series of bolts, 22, see Fig. II, which are located in slots on the outer surface of the sleeve member I3, I3, and are threaded into the central portion of the shell members I2 I2. 'I'hese bolts are provided with enlarged collars, or heads, 24, which are seated in pockets on the intermediate flanged or shouldered portions of the internally tapered bearingsleeves I3 I 3; and terminate in flattened or squared ends 25 by which they may be turned tomove the sleeves axially in the surrounding shells I2, and thereby adjust the bearing clearances between the members I2 I3 and I6.

The gear rings I5-I5 are clamped in position on the right hand ends of the' backing rolls 3 and 4, by means of nuts 23, which are threaded on the bolts 22 (which pass through three rings); and the gear rings I4 I4 are correspondingly secured to theopposite ends of the backing roll shells I2 I2, by means of the cap screws 21. The rings I4 I5 are provided with helically cut gear teeth of relatively fine pitch (e. g. 5 D. P.)- Whlch, as already stated, are in engagement with the helical pinions on the corresponding ends of the work rolls I and 2 and the rings I4 I4 are also provided with worm teeth of much coarser pitch, which are engaged with double or triple threaded driving Worms 23-28, that are secured to a vertical shaft 30, and are connected to a suitable high speed motor by a pair of mitre gears 3I 3I.

As indicated in Fig. I which illustrates a roll assembly for a non-reversing, or continuous, four high mill-the work rolls I and 2 are positioned behind the vertical plane in which the axes of the backing rolls 3 and 4 are positioned; and there is, therefore, a horizontal component of the holding down pressure on the working rolls which resists their tendency to climb or be drawn forward on the material entering the roll pass.v By properly positioning the axes of the rolls I, 2, and 3, 4, the rst named elements may be held in substantially stable equilibrium under any given fixed conditions as'to draft (viz. percentage of reduction) and otherl factors of resistance to rolling; and provision is made-as hereinafter explained--for adjusting the Vrelative positions of these roll axes. But these conditions may, and do, change duringV the rolling of successive sheets, or even different portions of thesame sheet; and I therefore provide the system, or assemblage of auxiliary supporting rolls 5 6 and 1 3, fortheis mounted as a unit on, or in a heavy U-shaped chock or bearing block 33 (best shown in Figs. V

and VI) which'is adjustably clamped to the reary housing pillars 2I 2I, and is connected to the front housing pillars 20-20 by the tension `bolts ments transmitted by the two pair of helical gearsl is 34. The auxiliary rolls l and 1 are loosely mounted on end pivot bolts 3lv that are carried by the side legs of the blocks 33; and the cooperating rolls l and 3 are rotatably supported in semi-cylindrical bearing pockets 36 in the base of these blocks. The adjacent surfaces of the rolls 5 3 and-1 4 revolve in opposite directions, and the end pivot guides 3B are therefore so positioned that these rolls are never in contact with each other; but the surfaces of the rolls 6 and 3 move in the same direction as the adjacent faces of the main backing rolls 3 and 4; andthe chock blocks 33 ,33 are, therefore, preferably so adjusted as to exert a forward pressure on the working rolls I and 2 through the intermediate idle rolls 5 and 1 and to concurrently establish and maintain a pressure engagement between the rolls 6 3 and 8 4. Under these conditions the Work rolls I and 2 will oat" inthe shallow crotch between the main backing rolls 3 and 4 and the intermediate supporting rolls 5 and 1; but in order to further guard against any possible sidewise displacement of the work rolls from their stabilized oating position the ends of the gear sleeves 9 and III are loosely embraced between the notched extremities of the' U-shaped supporting members 33 and the cap members 31 which are secured thereto by nuts on the tension bolts 34.

The journal supports I6 of the main backing rolls`3 and 4 extend outwardly between the adjacent sides or edges ofthe U-shaped housing pillars 20 and 2l and are provided with oppositely projecting lugs 40 40 which are threaded to engage with two pair of lifting and holding down screws 4| 4I that are suspended in upper bearings on the housing caps 42 42, and are concurrently rotated,'in. opposite`directions, by the worm wheels 43 43 and the intermediate worms 45 45. Each screw is provided with oppositely threaded portions which respectively engage the lugs on the upper and lower journal members I6 I6; so that the rotation of these screws moves the journal members-and the backing rolls 3 and 4 carried thereby-toward or away from each other, and correspondingly varies the vertical opening between the working rolls I and 2. The two worms 45-45, are respectively secured to the coaxial sections 43-46a of a two part shaft, and may be connected to, or disconnected from, each other by an intermediate clutch connection 41, so that all four screws may bemoved simultaneously, or each pair of screws (at one or the other side of the roll stand) may be moved independently, to obtain and maintain exact parallelism of the roll surfaces.

When power is applied to positively rotate the backing rolls 3 and 4 in opposite directions (through the gears 3I '3I, the shaft 30 and the reversely threaded worm and worm wheel elements 28 23)"the movement. of these rolls is communicated to the work rolls, I and 2, in part by the reverselycut helical gears on the rings I4 and I5, 'and the sleeves 9, III-which compel the rolls I 2 3 and 4 to rotatev at the samev peripheral speed-and in part by the non-slipping frictional engagement of the roll surfaces which are ground to the same diameter as the pitch line dimensions of the helical gear ele- The amount of power which can be not in itself sufficient to drive the small working rolls of a largecapacity mill-e. g. one 5 D. P. helical gear of '4" face running at aperlpheral speed of 600 ft. per minute (supra) can safely transmit less than 30 P. (under average conditions of mill operation) and four such gears cannot be depended upon to transmit more than 120 H. P.-but, as already pointed out, the nonslipping frictional pressure engagement of the backing rolls with the 'working rolls is capable of transmitting ample additional power (e. g. in the example already considered upwards of 3600 H. P.) to drive the working rolls under very heavy drafts and at high speeds. The primary function of the helical gear connections is not therefore to supply power to the working rolls, but is to maintain the latter in non-slipping relation to the power driven backing rolls and thereby obtain and maintain a high coeiilcient of friction (i. e. of traction) between the engaged surfaces.

It may be noted again that the power which is transmitted from the large positively driven backing rolls to the working rolls-by the nonslipping frictional engagement of these elements-is uniformly distributed over the entire width of the material being rolled; and it has therefore no tendency to twist or tortionally strain the working rolls even when they are made of very small diameter. Such additional amounts of power as may be transmitted to the working rolls, by .the helical gear trains, 9-I0- III-IS is equally divided between the two ends of the rolls, because of the opposite and complementary inclination of the helical gear teeth, and because the work rolls are free to move axially until the opposing end thrusts on these teeth are balanced and equalized by such movement. In order to permit each work roll to "hunt" its proper position, without interference from the other, the driving worm shaft 30 is provided with a movable end thrust bearing 48, which is preferablyso adjusted that the teeth of the work roll gears are out of operative contact with each other (see Fig. IV) and cannot, therefore, exercise any controlling effect on the axial equalizing movements of either roll.

It will be observed that the length of the journal bearings for the large backing rolls is substantially greater (e. g. as shown in Fig. I, greater) than the width of the pass be- -tween the work rolls; and that the mean diameter of their bearings is nearly fifteen times that of the rolls I and 2. For a. work roll diameter of 2.6" (13 teeth of 5 P. D.) the projected area of each of these bearings is therefore about 69 sq. in. per inch of width of the roll pass; and if the mean pressure is, as before assumed, 20,- 000 lbs. per inch, the unit pressure, per square inch of projected bearing area, is less than 290 lbs. Now it is well known that under such relatively light unit pressures the coemcient of friction of a well made cylindrical journal bearing, operati-ng at the relatively low surface speed here under consideration (about 450 ft. per minute), is under proper conditions of lubrication, not over 0.0015 to 0.002, which is less than the average coeflicient of a well designed roller bearing operating at its maximum safe load. With a copious supply of heavy lubricant plain journal bearings may be subjected to a load of 1000 lbs. or more per square inch of projected area without rupturing the wedge shaped oil illm whose maintenance is necessary to obtain a low coeillcient of friction; and the form of bearingA illustrated in Figs. I to VI is, therefore, capable of operating continuously and efficiently, Without undue heating, under any load to which it may be subjected in practice.

In order to keep the journal bearing surfaces continuously ushed with oil, one, or both, ends of each journal member I6 is provided with a large reservoir 49, which is kept lled with lubricant under pressure, (e. g. by a pump, or from an overhead tank, not shown), and is also provided with a central passageway 50, which communicates with this reservoir through a valve controlled port 5I, and which is connected to the surface of the bearing bya series of radial ducts 52--52 that lead to points about 90 degrees in advance of the projected planes of thrust on tlie backing roll members 3 and 4. The oil which is carried around by the revolving shells I3 collects in shallow pools at the bottoms of the rolls, until it reaches;l depth indicated by the dotted lines, a-a, (Fig. II), and is then syphoned oif through the passageways 53-53, and discharged into sump cups 54 from which it is drawn through the overowpipes 55 and returned to the main supply pump or tank. The reservoir 49 in the upper journal I6 is also provided with a feed pipe 56 which leads therefrom to the branch pipes 51-58 that communicate respectively with the passageways 60 in the upper and lower chock blocks 33-33. From these passageways a continuous supply of lubricant is delivered to the advance edges of the bearing pockets in the blocks 33. In order to keep the surfaces of the auxiliary rolls 5-6-1 and 8 free from scale and dirt I preferably provide wiping pads BI-BI which are removably supported on the blocks 33 by cross bars 62--62, see Fig. IV. I also provide for a continuous lubrication of the helical gear teeth and of the driving worm teeth on the rings I4 and I5 through a series of small passageways 63-63, see Fig. II, winch lead from the annular channel Abetween the backing rolls members I2-I3 to the outer surfaces of these rings; and the driving worms 28-2-8 are also preferably covered by segmental shields (indicated by dotted lines in Fig. I) which may be charged with hard cup grease.

Under normal conditions of operation the back pressure on the rolls 6 and B is relatively very small (as compared with the vertical pressures on the rolls 3 and 4); and the unit load on the bearing areas for the auxiliary supporting rolls 6 and 3 is, therefore, even less than it is on the main backing roll journals.

It is obvious that the use of ball or roller bearings for the various revolving elements of my improved roll system would present no advantage, because it would not result in any saving of power, or any reduced heating of the bearing parts, while the mill is in operation; and because the increased initial starting friction, which is involved in the use of plain bearings, is a matter of no consequence when the driving powerl is applied directly to the backing rolls, and transmitted from them to the working rolls. On the other hand the use of plain bearings, with an extended area of bearing surface, is of material advantage in the attainment of precision results, (as has been fully demonstrated in the operation of machine tools), and in the avoidance of extreme elastic distortions or deformations, of the bearing elements. And even if the heating of the plain bearings of my improved mill should, at any time, temporarily exceed that of the usual form of neck roller bearings-by reason of insufficient lubrication and a consequent rupture of the oil films-the effect of such increased heating is inconsequential because it is uniformly distributed over the entire working length of the backing rolls and cannot therefore produce any occur when these rolls are supported. in the usual manner, in end neck bearings. The amount ot power required to overcome the frictional resistance to .rotation per se, is, in any case, insignificant as compared with that required to effect the plastic deformation of the material being rolled.

Either one, or both, of the work rolls I and 2 may be readily removed from either side (end) of the roll stand by slightly separating'the backfing rolls, and detaching .the cap plates Il ll.

The intermediate idle rolls! and 'I may then be taken out by withdrawing the end pivot bolts tI-Sg; and this, in turn, permits the auxiliary supporting rolls 6 and I to be removed from their bearing pockets in the chock blocks 33, without disturbing the arrangement of the adjustments of any of the other parts of the assembly. Either one of -the chock block members-together with' all of the rolls supported thereby-may also be withdrawn from the rear side voi' the roll stand by removing the several bolts and cap screws, by which it is clamped to the rear housing pillars 2l-2I, and uncoupling the oil pipe connections 56--51-58, It requires, therefore, very little time to remove any of the small rolls. when they become unduly worn and replace them by others; and in doing this the helical gear sleeves 9 4and I--which are not subject to any severe wear-may be used with a number of successively regrooved or renewed working rolls of substantially the same diameter.

The construction illustrated in Figs. VII to XIV,

' inclusive, is of the same general character as that shown in Figs. I to VI; but differs therefrom in various structural details. In this second illus'- trative embodiment of my invention the work rolls la and 2a are positioned a substantial distance behind the axial plane of the two main backing' rolls 3a and la; andare directly engaged on their rear sides by two secondary backing rolls 65-65 (which are of materially greater diameter than the supporting rolls B `and l of the previously described organization), that are out of contact with the rolls 3a and 4a (see enlarged view of Fig. XIV). Each working roll is, in this case, supported ina relatively deep crotch between the surfaces of a main and a secondary backing roll (laf-65, or ct-85); and does not, for that reason, require any end guides, or other restraining means, to hold it against accidental lateral deplacement when the mill is running idle.

In this respect the construction now under consideration partakes of the nature of a cluster mill, although the rolls laf-Qa and II are of materially different diameters.'

Each of the working rolls la and-2a is of substantially the same construction as that of the rolls I and 2; i. e., it comprises a body' portion, and two end sleeves 9a and Ila which are provided with oppositely inclined helical gear teeth. and which are rigidlyl secured to the body porition in the manner already described (supra). Each main backingv roll (3a or 4a) comprises a massive cylinder I1 of shaped cross section, and two 'forged steel rings Ila and iavof L cross section, which are `rigidly attached to the central enlarged portion of the cylinder 61 by the cap bolts 21a-21a etc. Each set of rings is proj vided with oppositely inclined helical gear teeth which are adapted t'o mesh with the corresponding gears on the associated work rolls sleeves;

scribed.` The end portions of the hacking .roll cylinders l'l--Il are rotatably' supported by mas'- sive chock blocks I0-1I, whichl are each provided with a pair of side luss. that are' embraced by the legsl of the channel shaped housing pillars Ila-Ma, and are threadedto engage the verticallifting andjholding down screws lia-4in.

Each chock block 'Il carries a split tapered bearing sleeve I I, which is seated in a reversely coned socket in the chock block, and is held in an axially adjustable position thereinby the face rings '12, and the cap screws 18. The right hand ends ofthe backing roll bodi 'I-Ol are extended outwardly, beyond the bearing 4sleeve members 1i-12, to receive a pair of large spur gears, (or herringbone gears -1!) which'are driven in unison from any suitable source ofv are each provided with right and'left hand threaded portions,l which respectively engage the lugs on the upper and lower `chock blocks 'III- 10; and are rotatably suspended -in bearings onthe cross heads 'I6-16 that connect the upper ends of the housing columns a-2| a. -If desired the lo er ends of these screws may also be provided end thrust bearings 11 (see Fig. V11) which will assist in supporting the weight of the suspended backing rolls and chock block bearing members. 'I'he upper ends of the screws l Ia4 la etc. are provided with bevel gears 'Il which are cross connected, in pairs, by the bevel pinions and shaft elements 19-19-80; and the shafts, 80-80, at thetwo ends of the roll stand, are coupled together by two sets of bevel gears and pinions 8I-82, and by a third counter cross'shaft 46a. The shaft 46a. is provided, at each end, with a large hand wheel 83; and is made in two sections (like-the shaft 46), that may be con` nected to, or disconnected from,each other by a central clutch member 41a, so as to permit of concurrent or independent operationof the' screws at the opposite ends of the -backing'roll' M are secured in a horizontally xed, but

verticallyadjustable,v position on the rear housing pillars lia- Zia by the cap bolts kIB---II etc.-

In the arrangement of rolls shown in Figs. VII

to m, inclusive, the vradial thrust' on the main vbacking roll bearings is about98% of the vertical l.spreading pressure on. the working rolls lav and 2a. But the bearings ofthe secondary backing mus et arealso subjected to a'r'adial thrust-which necessary area `is obtained by making surfaces of the `iull diameter, and ofthe entire length, of the rolls (which, as shown in Fig.

X extend the full distancel betweenthe inner vsides of the housing pillars 2id-lla). desirable toutilize this relatively heavy pressure engagement between the secondary backing rolls I6, Il, and the work rolls, Iaand 2a, to supplement the frictional transmission of-power to the latter: and,v in the construction now under consideration, I do this by providing means for driving'the secondary rolls from the main backingv But itis also;

rolls 3ay and la. scribed:

As already lstated the helical gear rings Ida-lia are provided with plain cylindrical extensions 98 which are in circumferential registry with the outer ends of the secondary backing rolls 65, and the adjacent plain (untoothed) portions of the gear sleeve elements 9a and i0a. All of these last named sections are ground down to a diameter slightly less than that of the central body portions of the rolls, and are engaged by thinvendless steel bands 89-90 (not shown in Figs. VI to X, but diagrammatically illustrated in Figs. XI to XIV), which are preferably made of some alloy of high tensile strength and high elastic limit (such as that used for band saws), and which are maintained in driving engagement with the said sections by adjustable tension rolls 9i-9|. One pair of these steel bands (B9-99) engage with the outer halves of the projecting anges 6.8 on the lower backing roll 4a; pass up through slots 92 in the block 8l and around the lower secondary rolls 65; then under and around the lower work rolls 2a, then up and around the upper work roll la, then forwardly, along the contiguous surfaces of the upper and lower main rolls 3a and 4a, to the lower tension roll 9i, and thence to the advancing surface of the roll la (as shown by the heavy line in Fig. XIV) 'I'he cooperating pair of driving bands -90 are engaged by the inner halves of the ring anges 68, pass down through slots 93 in the upper chock block 84, and around the upper secondary backing roll 65, then vup and around the upper work roll la, then down and around the lower work roll 2a, then forward, (along the surfaces of the rolls lll-3a) to the upper tension roll 9|, and thence, up and back, to the upper backing roll 3a (as shown by the broken dotted lines of Fig. XV). Each end of each working roll (la and 2a) ls therefore subjected to the driving action of two bands-one of which passes around the roll in a clockwise direction, and the other of which passes around it in the reverse counterclockwise direction-and in order to automatically balance or equalize these reverse pulls, the tension pulleys 9l-9|, are mounted on bell crank frames 94-94, which are journalled on cross shafts 95-95, that extend between the front housing pillars 20a-20a, and which are connected by a common tensioning bolt 96. If desired heavy springs (not here shown) may be interposed beta een the adjustable nuts, at one or both ends, of the tensioning bolts 96, and the outwardly extending arms of the frames 94-94, in order to permit a slight elastic yielding of the tensioning devices; but the elasticity of the bands themselves is usually sufficient to provide for any necessary variations in length that may be produced by temperature variations etc. during the operation of the mill. It will be understood, of course, that a pair of these or other equivalent tensioning devices is provided at each end of the roll assembly; and that these devices may be adjusted concurrently or independently to maintain either the same or different tensions in the two pairs or sets, of bands or belts that engage with the opposite ends of the connected rolls.

If the effective driving tension of each of the four steel belts 99-89 and 90-90 is maintained at a mean value of 2000 lbswhich can be easily sustained by a thin (.04 to .05") alloy steel belt of 3.5 to 4 in width-the total amount of power that may be transmitted to each working roll (Ia-or 2a) at a peripheral (rolling) speed 'Ihese means will now be deof 600 `feet per minute will be approximately 36.4 H. P. for each belt or a total of over H. P. for the four. 'I'he amount oi power transmitted to both rolls is therefore over 290 H. P.

In order to permit these belts 89 and 90 to pass around the secondary backing rolls 65, a narrow portion of the bearing surface on the upper side of the lower roll 65, and on the lower side of the upper rolls 65, must be cut away (as clearly shown in Fig. XIV) but this slight reduction in bearing area is in part compensated by the pull of the bands which tends to relieve the axial back thrust on the rolls and therebyA reduce the resultant unit pressures on the bearing surfaces. This belt tension also reduces the reverse'radial pressures on the axes of the main backing rolls 3a and la; and correspondingly diminishes the unit pressures on the bearing sleeves 'll-H therefor.

All of the bearing surfacesboth those of the main backing rolls, 3a and 4a, and of the secondary backing rolls, 65, BS-are continuously and copi/ously flushed with oil under pressure from a large tank or reservoir 91, which is provided with pipe connections Blo-58a, that lead to longitudinally extending passageways Stia-60a in the chock blocks 94-84'-from which the lubricant is supplied to the entire advance edges of the semicylindrical bearing pockets in these blocks-and which isl also connected, by the vertical conduit 98 with the radial spaces 99-99, between the edges of the split bearing sleeves 'll-1|. The outer ends of these openings are preferably closed by adjustable screw plugs |00, which are carried by the face rings 12, and which are provided with packing washers |0| of soft plastic metal (e. g. lead) that may be forced down over, and partially into the said openings after the sleeves have been axially adjusted to provide the proper bearing clearances between them and the rotating members 61-61. 'I'he lubricant is then introduced to the openings 99-99, and supplied to the advance edges of the sleeve bearings, 'li-1|, through the horizontal nipple connections with the vertical conduit 98. This conduit also supplies oil to the shaft bearings of the tension rolls 9I-9I, through pipes |03 and suitable passageways in the cross shafts 95 and the arms of the bell crank frames ill- 94.

'I'he amount of power transmitted to the secondary backing rolls 65-65, by means of the steel belt drives above described, isI less than half of that communicated to the working rolls Ia` and 2a by this same meansbecause each of these secondary rolls is engaged by only two of the belts, and the arc of engagement is also less than that of the belts with the working rollsbut whatever power is thus transmitted to the revolving elements 65, is in turn transmitted to the elements la and 2a by the pressure engagement between their contacting faces.

In the upper part of the diagrammatic illustration of Fig. XIV, I have indicated an additional means for communicating an added amount of power to the upper secondary backing roll 65 and from it, to the cooperating working roll la. This means comprises a pair of idle helical gears |04, which are positioned in end pockets in the block 94 and are rotatably supported on a cross shaft |05 carried thereby. 'I'hese gears |04-I04 are in alignment with, and are engaged by, the helical gear teeth on the main backing roll rings Maf-wa. The secondary roll 65 is, in this case, somewhat reduced in diameter-(as compared with the construction shown in Figs. VII to XI, and also in the lower part of Fig. XIV)-and is y 2,160,767 also provided with two rows of helical gear teeth,

roll, each of the idle pinions |04, |04 is left free to move axially on its supporting journal |05; and the secondary roll B5 is also permitted to move endwise in its bearings. Under these circumstances the engaged helical gear elements, I III-IIrG-Qa and Illa, will automatically hunt positions in which the power transmitted from the main backing roll ring gears Maf-ld to the .work roll gears Sa--Illa is equally divided or distributed between the two diiIerent zones of tooth engagement; and since these zones are well separated--by an .angular amount greater than the arcs of tooth contact-the total amount of power that may be safely transmitted by the engaged gear elements is double that which can be transmitted when there is only one zone of engagement-as is the case in the organizations shown in Figs. I to XIII inclusive.

In the diagrammatic illustration of Fig. XIV,

I have shown the supplemental gear drive forthe secondary backing rolls, as applied only to the upper one of these members, but it will be understood without further explanation that when this'supplemental drive is used it will, preferably, be applied to both of the lower and the upper roll elements 85 and Sa-IIIa.

Under the conditions last described the total amount of power that may be transmitted from the positively driven main backing rolls to the working rolls is as follows:

(A) Through the helical gear connections (with gears of 4" face and of 5 D. P. at a pitch line (rolling) vspeed of 600 ft. per min.

(a) By direct connection between n 9a-I0a, and Ila-Ilia (supra)- 120 H. P. (b) By supplementary connection through the gears IDI-|06--- 120 H. P.

(B) Through the belt connections 89 and 90 (a) By direct engagement with the working rolls (supra) 290 H. P.

(b) By engagement with the secondary backing rolls 140 H. P.

.l 430 H. P.

It is obvious that the amount of power which can be transmitted from the positively driven econdary backing rolls 65-65 to the working rolls Ia and 2a can be no greater than that which is communicated to the backing rolls themselves; and that in the case last considered this amount isV limited .to the transmitting capacity of the helical gear and belt connections IIM-IIIG and 89.-9II. I will now proceed to describe another more pronounced type of cluster mill, in which each working roll is supported by the large backing rolls of unequal size, and in which all of these backing coils are directly, and independently driven from a common source oi' power.

The organization last referred to is illustrated in Figs. XIII to XXII inclusive, and comprises two small'working rolls Ib- 2b Aof, substantially the same construction as those previously described; and four large backing rolls b-lb and I IIIA-I I I; which are driven in synchronism (with the rolls 3b and I I0 revolving ina counterclockwise, and the rolls 4b and III revolving in a clockwise direction) by a train of worm and worm wheel gearing, which will be later described.

In order to reduce the horizontal distance between the axes of the rolls 3b-I I0 and lb-I I I,

the surfaces of these revolving elements are provided with an interdigitated, or interdigitating.' series of tongue and groove, or collar and channel, sections, II2--II3 etc., of which only the collar elements engage with the working surfaces of the rolls Ib and 2b. The sections are each of relatively small width, and the staggered lines--or rather narrow bands-of pressure engagement between the working rolls and the grooved backing rolls are so short, and are separated by such small angular intervals, that there is no material tendency to bend, or transversely deform, or circumferentially distort the smaller working rolls. The projected areas of pressure contact between the revolving elements isl in fact substantially the same as that which exists between each of the working rolls and the single large backing roll of a four high mill-such as is shown in Figs. I to VI inclusivealthough it is less than that which is obtained by the use of both `primary and secondary backing rolls, in senil-cluster mills such as were last considered.

' The main backing rolls 3b and 4b are rotatably mounted on stationary journal members IBb, which are provided, at each end, with squared extensions that are embraced and guided by the side flanges of channel-shaped housing pillars h-2lb, and are threaded to engage the lifting and holding down screws 4 Ib-l Ib. These screws are supported and suspended in bearings on the housing caps 2b-42h, and may also be provided,`

If desired, with end thrust step bearings similar to those shown in Fig. VII. They are rotated by means of worm wheels IM-I I4, which are cross connected by a pair of worms I I5 on the two part shaft, I I6, that is provided with a hand wheel at each end and with a clutch coupling,'l`lb, at the center; sothat the two screws may be operated concurrently or independently as desired. "Each of the stationary journal members, IGI), is provided with two reversely tapered split bearing sleeves II1, II'I, which may be axially adjusted on these journal supports by means of a circumferentially disposed row of bolts II8, see Fig. XXII, that are seated in longitudinal slots on ythe periphery of the members I6b, and are adapted to draw together, thus expand, the spit sleeves to compensate for wear. The opening between the edges of each expanded sleeve is substantially closed at one end, (see Fig. XVIII), by the adjacent inwardly projecting shoulder of the outer backing roll shell; and at the other end (see Fig. XXII) it is closed by a plug I00b, similar to that shown in Fig. IX, through which oil is introduced, preferably under pressure, from a suuply conduit 98b;the sleeves beingso positioned that the lubricant so introduced is fed to v the revolving bearing surfaces in planes about y90 degrees in advance of the projected lines of thrust of the journal axes.

The secondary bearing rolls IIII and III are each carried by a massive chock block |20, whose ends are rigidly secured to the L-shaped housing pillars |2|-|2|, and whose central portion is bored out to form a semi-cylindrical grooved bearing surface for both the collar and the channel sections of the associated roll member, and thus afford an ample bearing area to receive the backpressure to which it is subjected in the rolling operations. This grooved bearing surface is constantly and copiously supplied with oil through the longitudinally extending passageways 60h, (see Fig. HX); and the pipe connections 51a and 58a that lead to any suitable tank or reservoir. In order to prevent scale or dirt from being carried into the grooved bearing surface suitable wiper pads 62h may be mounted on the advance edge of each bearing block |20.

The end collar sections of each pair of backing rolls, :ib-H0, and 4b|||, are provided with trains of helical gear teeth |4b|5b and |24| 25, which are of the same (pitch) diameter as the associated collar surfaces, and which are adapted to engage with the elongated helical pinions on the work roll sleeves 9b and |0b. These gear connections compel all of the cooperating rolls to revolve at the same peripheral speed and thus maintain the pressure engaged surfaces thereof in non-slipping relationship to each other, so as to secure the most effective frictional transmission of power from the large positively driven backing rolls to the small working rolls. In order to obtain an equalized driving pressure between the gear teeth on the main backing rolls, 3b'||0, (or 4b-|||), and the teeth on the work roll sleeves 9b-|0b, the latter are left free to huntl the proper axial positions (as before explained); and each set of backing roll elements (3b-I I0, or 4b-ili) is driven in the same direction by a pair of right and left hand worms |26|21 (or |29-|30) one of which engages a worm wheel |3| on the outer end of the backing roll 3b (or 4b), and the other of which engages a worm wheel |32 on the adjacent end of the secondary backing roll ||0 (or'|||). The upper pair of worms H2B-|21) are rigidly secured to a vertical shaft, |33, which is rotatably mounted in bearings on the housing cap 42h and in the lower base plate of the roll stand; and the lower pair of worms M30-|29) are an integral part of a tubular sleeve |34 which is slidably and rotatably mounted on the shaft |33. The shaft |33 and the sleeve |34 are provided with spur pinions |35-I 36, which are rigidly keyed thereto, and are respectively engaged by a pair of spur gears |31 and |38 that are detachably secured to each other and revolve, asl a unit, on a short vertical stud shaft |39. The unit gear assembly (I 31-l38) is in turn connected to any suitable driving motor by the mitre gears |40.

It is apparent that the above described arrangement of worm and spur gear elements permits each pair of worms to move axiallyi. e. tangentially with respect to the associated worm wheelsas they are revolved by the parallel gears |35|36|31 and |38; and that this free axial movement allows each connected pair of worms (H6- |21 or |30-I29) to "hunt a position in which equalized amounts of power will be transmitted from the backing roll gears |4b-I5b- |24|25 to the sleeve gears 9b and |0b at the opposite ends of the working rolls lb and 2b. This automatic balance, or equalization, of the driving forces (tooth pressures), exerted at the separated zones of gear engagement between the positively driven backing rolls 3b| |0 and 4b-|||, and the working rolls Ib and 2b, is obviously of marked advantage in eliminating unequally distributed stresses and strains in the operating elements, and in greatly reducing any tendencies to twisting, or angular distortion, of the small diameter work rolls. v

The lower intermediate spur pinion I31-which is operatively integral with the horizontal mitre gear |40-is provided with an upwardly extended sleeve hub that carries the upper intermediate pinion |38; and the contiguous faces of the two pinions, |31 and |38, are each provided with a ring of teeth that are normally held in interengaged relation by the sleeve nut |4|. When the bracket support |42, which engages the upper end of the stud shaft |39, is removed, the nut |4| may be turned back, and the gear |38 may then be lifted and rotated with respect to the gear |31. This will, in turn, rotate the lower set of worms |29-|30, with respect to the upper set IZB-|21, and will correspondingly alter the angular position of the lower gear driven work-' ing roll 2b with respect to the upper working roll ib. These two rolls may thus be brought to such a relative angular position that the gear teeth on the upper roll sleeves'are out of operative contact with the contiguous gear teeth of the lower roll (as shown in Fig. IV), so as to leave each roll to hunt its proper axial position with respect to its associated backing roll elements.v

In addition to the positive helical gear connections between the rolls, 3b| |0-|b, and

4b| I-Zb, I may also provide a system of steelbelt connections between these revolving members, which are similar to those already described in connection with the organization of Figs. VII to XV inclusive. In the construction now being ,considered the belt engaged end collars of all of the rolls are reduced in diameter by the same proportionate amount-e. g. by approximately 13 %so that the ratios of angular velocity established by the belt connections are the same a's those that are fixed by the positive gear engagements. The twin belt elements b which interconnect the upper backing rolls with the working rolls pass from the upper side of the roll collars ||2a on the backing roll 3b, under a pair of tension rolls |45, to the end collars ||2b on the secondary backing roll ||0; then forward around the reducedouter ends of the upper working roll sleeves 9b|0b; then downward and around the aligned portions of the associated sleeves on the lower work roll 2b; and then forward again to the backing roll collars ||2a. The corresponding belt connections (89h) between the lower backing rolls 4b and and the working rolls IIJ-2b, run from the lower side of the end collars (I |2a) on the roll 4b, over anotherpair of tension rolls |46, to the end collars |2b on the roll then forward and around the lower work roll sleeves (in a counterclockwise direction); then up and around the upper work roll sleeves (in a clockwise direction); and then forward again to the lower backing roll collars |2a. Each work roll is therefore engaged and driven by all four of these belt connections; and each belt is driven by its cir- (at its opposite outer extremity) onl a suitable bracket I carried by the housing caps 2b-42h; and the other two of which MS2-|52) are rattached to the main base plate of the roll stand. Each set of carriage actuating leversat the opposite ends of the roll assemblyis operated by a connecting rod, |53, whose length can be adjusted by a central turnbuckle, |55, so as to concurrently move the associated pair of tension rolls ISI- |52 toward or away from each other, and thus impose any desired tensions on either pair of driving bells 6917-9017.

If we assume that the spreading pressure on the working rolls Ib and 2b is exerted in a vertical plane (which is approximately true in all cases except those involving abnormal draft reductions) the radial thrust on the axes vof the backing rolls 3b and 4b will be about '78% of this spreading pressure, and. the accompanying radial thrust on the axes of the associated backing rolls and will be approximately 63.4% The total pressure which is effective in thev nonslipping frictional transmission of power from the larger to the smaller rolls is thereforeunder the same conditions as before assumed-supra:

(H. P.)= 0.5 (0.78 -i- 63.4= l.414) 20,000 X coca/33,000

g257.`per inch of width of roll pass g5l40 H. P. per 20 inches of width In addition to this we have the power transmitted by the helical gear trains which, in the case of the construction now being described (in line speed of 600 ft. per minute- (H. P.) grr-180 H. P.`

The total driving force on the working rolls of the last described mill (operating under the above specified conditions) will therefore be (H. PJM-(H. P. g+ H. Pana-5570 H. P.

Figs. XXIII to XXIX, inclusive, illustrate another application of my invention to which I have hereinbefore referred to as a full cluster" type of mill, in which each working roll |c and'2c is provided with a twin pair of large backing rolls, 3c-3c and 4c--40, of the same diameter; and in which a set of four transmission rolls |60, |60c, |6| and |62, are interposed between each working roll and its associate pair of backing rolls in such manner that eachy assembly of revolving elements, yIc|60|60c|6| and |62, or 2c- |60-|60c-'|6| and |62, is suported, in otant equilibrium, and in true vrolling contact, with the corresponding pair of backing rolls 3c-4c or Ic-4`c. The geometrical relationship between the roll axes, by which these results are attained, is best indicated in the .diagrammatic showing of Fig. XXIX; wherewb-wb are the lines joining the centers ofthe work roll |c and of the backing rolls 3c-3c;` wt-wt are the lines joining the centers of this work roll and of the transmission rolls |60c and |60; and :rb-.rb are the lines joining the centers of the roll |62 and of the backing rolls 3c-3c. As indicated by the arrows all (ISI or |52), two of which (|5||5|) arey It will be apparent that the thereof .j

of theV engaged surfaces of these devolving elements are in true rolling contact with each other. conditions of stable or constrained equilibrium, and of true rolling contact between the assembled rolls will be main-Y tained for any roll diameters which may be selected, provided onlyfthat the lines wt-wt lie inside (e. g. above) the lines 10b-wb, and the lines, :cb-:rb are inclined to each other at an angle of less than 180 degrees.

Each of the main backing rolls 3c-3c and 4c-4c comprisesa heavy cylindrical shell |63, that is revolvably mounted on a stationary journal member I 6c whose reduced end portions are embraced and guided between the side anges of the channel shaped housing pillars c-20c (or 2|c2|c), and whose central portion is reversely coned to receive two correspondingly tapered split bearing sleeves ||1c-||1c. These bearing sleeves are provided at their outer ends with a series of inwardly extending lugs |65,

which are positioned in suitable recesses in the shoulders of the journal members |6c, and which are threaded to engage the extremities of the right and left hand screw bolts ||8c| |8c, etc., that are loosely held in longitudinal slots on the surface of these members. By turning these bolts the split bearing sleeves ||1 c-| 1c may be moved axially ontheir coned journal seats, and thusexpanded (or contracted) to obtain and maintain the desired clearances between the bearing surfaces.

The radial openings surfaces of the sleeves ||1c and the internal surfaces of the outer revolving shells, |63, are, in this case, filled with rows of segmental bearing between the external shoes, |66, 66, etc.-(as here shown seven in number)-each of which is provided with two end trunnions |61|61 that are engaged in short g radial slots in the annular spacing rings |68, |69.

One of these spacing rings (|68) is held in fixed.

endwise relationship to the adjacent extremities of the trunnions |61, by the cap screws |10; but the other ring (|69) may be adjusted axially with respect thereto, and clamped in this adjusted position, by the double lock nuts |1|. Each trunnion element |61 carries a roller |13, which is of oval cross section, and is engaged, on its inner side, by the beveled ange surface of a ring |14 that is clamped against the shouldered end of the stationary journal member |6c, and, on its outer side, by an internally coned end portion |15 of the outer revolving backing roll shell |63, see Fig. XXVI. The outer ends of these shoe rollers, |13, are engaged by the adjacent spacing rings |68 and |69; and by moving these rings toward each other (in the manner already explained) the rounded faces of the rollers may be wedged, more or less tightly, between the reversely coned surfaces of the rings |14 of the shell |69.

When the backing rolls 3c (or 4c) are rotated, the members |13 are revolved on their trunnion- .the more rapidly advancing bearing surface of the backing roll shell |63, and also between their inner faces and the stationary outer surfaces of the bearing sleeves ||1c (see Fig. XXV). This system of individually tiltable shoes with end roller supports, is comparable in effect with the well known Kingsbury end-thrust bearing which has a lower coe'mcient of running friction than any other bearing known; and the use of the auxiliary rollers |13 in combination therewith also substantially reduces the starting friction (as compared with that of a plain cylindrical bearing), and ensures the continuous relative movement between the shoes and the bearing surfaces on which they are floated by the intervening oil films.

Each of the backing roll shells |0| is provided, at one end, with a large spur gear |11 whose pitch diameter is the same as that of the outer surface of the shell, and which is capable of receiving and transmitting at least one-fourth of the maximum power that is employed in operating the roll stand.. 'I'hese gears are driven in unison-to rotate the upper backing rolls 3c-3c in one-direction (e. g. clockwise), and the lower backing rolls 4c4c in the reverse directionby a pair of pinions |18|`|8 which are of the same pitch diameter as the outer intermediate rolls |62|62, and are preferably made integral therewith. The adjacent ends of these rollsare extended outwardly (as' best shown in Fig. XXVII) to receive a pair of involute tooth mill gears |80|80, which are in mesh with each other, and which are driven by any suitable means--such as the wobbler pinion |8| indicated in dotted lines in Fig. XVIII. Each of. the rolls |82 is also provided with two rings |02|82 of oppositely inclined helical gear teeth, of the same pitch diameter, but of ner pitch, than the spur pinions |18; and these gears |82|82 are engaged with similar gears |83|83 on the intermediate rolls |6|-|6|. Each of the gears HB3-|83 is engaged with two gears |84|84c on the rolls |60 and |600; and the latter are in turn in mesh with the working roll sleeve gears 8c-|0c, see Fig. XXVII. The pitch diameters oi all of the gears |83, |84 and |84c are (like the gears ETF-|78- |828c and |0c) the same as the outside diameters of the corresponding roll members; and the engaged surfaces oi these revolving elements are thus maintained in true rolling-on-slipping relationship to each other.

Each pair of backing rolls (3c-3c and 4o4c) are connected to the associated working roll (Ic or 2c) by a pair of steel belts 80c--80c and 890-890, which also pass around the cylindrical outer ends of the rollers |60|80c and thence under (or over) the adjacent extremities of the gear sleeves 8c-|0c. In order to permit the use of these belts, withoutextending the last. mentioned rolls beyond the ends ofthe rolls IGI, the gears |84 and |84c-and the cooperating gears on the work roll sleeves 8c and |0c-are of less width than the gears |82-|83; and the outlet belt engaging sections of the rolls Ic-Sc (or 4c-4c) |60-|60c, and of the gear sleeves 8c|0c are all reduced in diameter, by the same proportionate amount (in this case about 688%). in order to permit the belts to pass over and be-v tween the teeth on the adjacent rolls ll-|62 (see Fig. XXIX). The belts 80e pass from the top of the front backing roll 3c, under a pair of paper tension rolls, |45c|48c to, and around the rear backing roll 3c; then forward around the transmission roll |60c, then downward and around the upper working roll |c;' then up and around the transmission roll |60; and thence forward again to the lower side of the front backing roll 3c. The belts 880-880, follow a similar path (over the lower tension rolls |48c, around the rear backing roll 4c, the lower transmission roll |800, the bottom working roll 2c, the adjacent roll |80, and forward again to the front backing roll 4c); and both sets of belts .8c-88e and 80c-8lc perform the joint functions of transmitting power from the positively driven backing rolls to the working rolls-(and in this case to the intermediate rolls IED-|60() as well and of also maintainingall of these rolls in operative relationship t0 each other when the mill is running idle, and there isI no spreading pressure exerted on the floating roll systems Ic (or 2c) |80|60c-|6| and |02.

Each of the tension rolls |45c|45c is rotatably supported in-a bifurcated frame |88, which is secured to a tubular sleeve |86 that is pivotally mounted on the cross shait4 |81; and is provided, at the outer end of the sleeve |08, with a fork arm lever |88. The lower tension rolls |48c|48c are similarly mounted on a cross shaft |88 that is carried by suitable supports on the base of the roll stand, and are connected to forked arms |80-|80. The ends of each pair of arms IBB-|80 (on theopposite ends of the roll assembly) are connected by the pivoted links |8|-|8|; and

ends are engaged with the said links, and which can be rotated, by any suitable means, to impose any desired, and automatically equalized, ten- I sions on either set of belts, 88-80.

In order to transmit balanced amounts of power from the positively driven transmission roll |62 to the associated Working roll |c (or 2c) the helical gears |84 are mounted to move freelyboth circumferentially and axially-on the ends of the rolls |60, so as to permit them to automatically hunt positions in which the tooth pressures between these gears and the sleeve gears 8c|0c are substantially equal to those between the latter and the gears |840. One of the driving gears |80 is also connected to the roll |82, in such manner (as indicated in Fig. XXVII), that it may be turned slightly thereon, and then rigidly clamped thereto (e. g. by the hub bolts |83) see Fig. XXVII, so as to keep the helical gear teeth elements of the two working rolls, icl-2c, out of contact with each other (as shown in Fig. IV), and thus permit each of these rolls to move axially-independently of the otheruntil the driving pressures on the oppositely inclined helical teeth of these elements are in balance.-

As has already been pointed out each set of.

transmission rolls, |60-|60o-|0| and |62, are automatically in vfixed relative relationship to each other and to the backing rolls 3c-3c (or 4c-4c) both by the reactive rolling pressures on the working rolls |c and 2c, and also by the tension of the belt elements 80c-80c and BSc-88e; and no auxiliary end bearings for these rolls are required to maintain this true rolling relationship between them, either while the mill is running idle or when it is operating.

But in view of the fact that all of the driving,

25 the tension rod |53c, whose reversely threaded 4 in, or carried by, transverse chock blocks |91 which are rigidly bolted to theadjacent sidesv made of slightly larger diameter than the overall sizeof the gears or, as here shown, are provided with free bearing sleeves |99, of this requisite diameter. Any one, or all of the other small rolls (|c-2c-l60-I60c and |6I), can be removed and replaced from the front (left hand) end of the roll stand by merely lifting the upper set of backing rolls 3c--3c by a small amount and by relievingthe tension on the belt connections 09a-90e.

In the constructionnow under consideration the lower set of backing rolls lc-Ic are supported in fixed position by the usual form of leveling (wedge) plates and set screws (200); and only the upper set of backing rolls 3c-0c are moved up and down-to change the height of the roll passby the conjoint action of the four holding down screws, and of the heavy lifting springs 202 that are interposed between the ends of the journal members |6c. The holding down screws 20| are threaded through the ends of the housing caps 42o-I2C, and are leach provided with a bevel gear 204 which is engaged by apinion 200 on the adjacent end of a shaft 200, that is provided, at its center, with a worm wheel 201; and the two worm wheels, 20L-201, at the opposite ends of the'roll assembly, are cross connected by the worm and worm shaftv elements 208-209-200. Allfof these parts, 205-200-201-200-209, are supported by bearing members 2|0-2Ii, which are mounted on, and move up and down with, the shouldered ends of the holding down screws 20|.

.so that all of the gear elements are automatically maintained in engagement for all positions of the upper backing rolls. 'I'he worm shaft 209 is made in two coaxial sections, which may be connected or disconnected at will by a central clutch 01e; and each of the bevel pinions 205 is axially movable on its splined shaft 206,.so as to permit it to be thrown out of engagement with its associated gear 205, by means of a shift lever 2 Il. The two pairs of companion screwsV 20|-20I may therefore be rotated concurrently or independently, or any one screw may be moved independently of all of the others, to adjust the axes of the backing rolls to any desired position.

, In order to assist the action of the springs 202',

the screws 2|0 may be axially bored to receive lifting bolts 2|0, Fig. XXIII, which pass down through. the journal members |00, and are rotatably engaged at their upper ends with the adjacent extremities of the holding down screws.

When the nuts and washers on the upper ends of 'these lifting bolts (2|0) are removed and the connections the chock block members |00 from their housing support 20c-lic,

The vertical movement of the upper backing rolls, to change theheight of the roll pass, will alter the center to center distance of the driving gear |00|00, but the involute form of tooth permits -this to be done withot interfering to any material degree with the efficient transmission 'of powerfrom one to the other. All of the other gear trains remain in fixed center to center relationship, and may therefore be provided with either the 'involute or the epicycloidal form of tooth section. n

The provision of the auxiliary bearing "members |95-l 90, for the ends of the positively driven Vtransmission elements |02--|62,4 not only assists these elements in maintaining a true rolling relationship with the surfaces of the associated rolls 3c, 4c, and 0|, (and in resistingy any side orend thrust of the engaged gear elements |11|10 |00-i02 and |00), but also affords a convenient channel in the bearing block |91, and this channel is connected, by two branch passageways, 22|, with longitudinal passages 222 in the connected journal members |0c, which are, in turn, provided with a series of lateral ducts leading to the openings between the edges of the split bearing sleeves ||1c, at a point about 90, degrees in advance of the planes of radial thrust on the journal axes (see dotted lines of Figs. m and XXIV). The annular channel in the bearing member |91 is also connected-by the extensible pipe conduit 22S- with a like system ofnassageways vancl ducts in the lower bearing block |60 and ir the journal supports for the lower backing rolls lo-lc. This engagement ensures a continuous and copious flow of lubricantunder pressure if desired-to all of the enclosed bearing surfaces ofthe roll assembly; and, as before indicated. the design of the main backing roll bearings is such that the maximum unit pressures thereon are well below the rupture point of the supporting oil films.

In the illustrative construction shown in Figs. XXIII to XXIX the angle between the vertical and the planes w-b, w-b is a little less than 51 degrees, and the axial thrust on each of the backing rolls is therefore approximately '19% of the vertical spreading pressure on the working rolls Ic-2c. on the latter is therefore about 60% greater than that which is exerted by the action of the two backing rolls of a four high mill, such as is shown in Figs. I to VI inclusive; and under the conditionsheretofore assumed will amount to at least 5800 H. P. In addition to this we have, as before, the supplemental driving effects of the helical gear connections between the rolls |62 and |c2c, and of the belt connections between the latter and the rbacking rolls 0c3c0clc; and these may aggregate (as before indicated) from 300 to 400 H. P.

In mills of the cluster type the ratio between the substantially vertical (or normal) spreading pressures on the working rolls, and the resultant radial pressures on the backing roll surfaces in .engagement therewith increases very rapidly as the angular separation of the backing rolls- (i. e. the-angle between the lines w-b, 11i-b)- is increased. In asymmetrical 60 degree ar- The total frictional driving effect rangement-in which the lines Joining the center of a working vroll with the centers oi. the two associated backing rolls make any angle of degrees with -the vertical-the component of radial thrust on each of these backing rolls is substantially equal to the spreading pressure on the working rolls; and the total pressure of surface engagement between the driving and the driven elements-which determines the limit of power transmission through such engagement-is twice that which it is possible to obtain in a straight four high mill assembly, and very substantially in excess of that obtainable with semicluster mills suchas are shown in Figs. VII to XXI inclusive. But in all cases` the amount of power which may be transmitted from th'e positively driven backing rolls to the small working rolls, by a non-slipping pressure engagement between the roll surfaces, is amply suiilcient to operate the mills of my improved construction under the heaviest drafts and at the highest speeds now attainable with much larger working elements.

'I'he various forms ofconstruction which have been heretofore described (as illustratedin Figs. I to XXX, inclusive) are particularly designed for use as continuous-or one way-mills; but it will be apparent-that the roll assemblies shown in Figs. XVII to XXX may be used, if desired, in reversing y'(or two way) mills. The organizations illustrated in Figs. VII to XV can also be used in two way rolling; and the construction first described (Figs. I to VI) may bel easily modifled to operate as a reversing mill. But the arrangement which I prefer to employ in mills of this character' is shown in Figs. XXX to XXXI inclusive where Id, 2d indicate the small working rolls, 3d, 4d the two corresponding backing rolls, and 225-225 are a pair of power receiving land transmitting rolls, which are interposed respectively between the'rolls Ici-3d and 2d-4d. The axes of all of these rolls 4are positioned in the same vertical plane XIVI-XXX, which is perpendicular to the line of movement of the material through the roll pass.

The backing rolls 3d-4d are each mounted on a ring of segmental bearing shoes |6611, which are revolvably engaged with tapered bearing sleeves ||1d, that are axially adjustable on the stationary journal members |6d;-the construction and arrangement of these parts being substantially the same as that previously described (see Figs.

' XXW to XXVI, supr-a). The ends of the journal supports, iSd, project into the window openings betweenV the two pair of housing pillars 20d-2id, at the opposite sides of the roll assembly; and are cut away or rabbeted to receive stirrup shaped chock plates 226 which are bolted rigidly thereto, and which are slidably engaged at their edges with the contiguous faces of the pillars 20d-2 Id. The adjacent portions of these plates are cut out to form open semi-cylindrical guides for the ends of the rolls 225; and the action of these end guides is supplemented by V-shaped cross head members 221-221 etc.; which extend across between the plates 226-226 and are held in position by the through bolts 228-229. These connected .members 226-221 provide continuous side bearing supports which will -prevent any lateral displacement of the power receiving and transmittingrolls 22S-225 under the side thrust of the main driving gears |d-|80d, which are secured thereto, and which are driven in unison in any` suitable manner.

The opposite ends of the rolls 22S-225 are provided with oppositely inclined helical gear elements "2d-Ind which engage with complementary gears 9d on the working rolls |d-2d, and which transmit automatically equallzed quotas of power thereto in the manner previously explained. In order to restrain any transverse movement of the working rolls 4under the pull which they exert on the material passing between them I provide two pair of symmetrically disposed castor rolls .230-230, which are engaged, on their inner sides with the working rolls |d-2d, and on their outer sides, with two other pair or small .backing rolls 23|-23| that are mounted in rolling contact with the driving rolls 22S-225. Each group of `rolls 230--23|, 23d-23|. is supported in position, on opposite sides of the corresponding work roll (Id or 2d) by means of cross heads232-232, which are secured to the chock plates 226-226 by means of through bolts 233-233, and cap screws 234, and which are also clamped to the bearing members 221 by the screws 235. The inner faces of "the cross head supports 232 are machined to form segmental bearing surfaces for the rolls 23o-23|; andr in order to more eiectively resist the lateral spreading pressure on these surfaces, and to also ailord a means for their accurate adjustment, the ends ofthe through bolts 233 are cross connected by toggle bolts 226.

In order to increase the amount of power that may be transmitted from the gear elements |82d on the rolls 225 to the work roll gears 9d, the rolls 23|) and 23| are also provided with coengaging gear elements which are respectively in mesh with the helical gears 9d and |82d; and in order to equitably divide, or equalize, the driving thrust on the teeth in the three lines or zones of engagement with the working roll gears Sd, the castor rolls 230 (like the working rolls idf-2d) are'left free to move axially, and the cooperating gears on the ends of the rolls 23|-like the gears |84 on the rolls |60 (see Fig. XXVII supra)- are formed on separate collars that can each move independently and hunt its position by balanced thrust, or driving action, on the rolls 230. Since the three zones of tooth engagement on the working roll elements 9d are separated by an angular distance greater than the arc 'of tooth) engagement itself, it follows that the amount of power which can be transmitted to these elements, with the arrangement last described, is` three times as great as that which can be transmitted with the construction shown in Figs. I to VI, and is 50% greater than can be imparted vwith the arrangement illustrated in the upper part of Fig. XIV, and in the alternative arrangements of Figs. XVII and XXVIII. Under the conditions above specied 'gears of 5 D. P. and 4" face can therefore be relied upon to safely transmit a total iwf 180 H. P. to each working roll-or 360 P. to the two-at a peripheral speed of 600 feet per minute.

An additional amount of power can be transmitted from the powerj'eceiving and transmitting rolls 225 to the workin'g rolls Id and 2d by means of th l,riferi belts ildiand 89d, which are engaged wit the plain e'nd portions of the rolls 311-23 |-230 |d-230-23i and 225 (or 4d-23I-230-2d-230-23I and 225). As shown in Fig. XXX to XXXI the pair of belts Sd-d pass from its upper backing'roll 3d downward around a takeup or tension pulley |45d; then vunder the left hand supporting roll 23i-(through a triangular slot 231 in the cross head 232)-then over and partly around the 40 asbefore calculated, about 3600I P. for ar 20"A v so meager vadjacent castor roll 230 then under the upper working roll ld; then over the righthand castor .roll 230 and under andjnearlyaround the adjacent supporting roll 23| then' under and around the uppery power transmitting roll 225 and back to the upper backin roll 3d. The belts 33o-#33d follow a correspon ng, path; over,`- underl and` around' a lower tension roll ludl and the successive. rotating elements 23l 230-2d+230. lof" smaller rolls ymoves with it. The spreading pressure to which the working/rollsldh are' 23I'22i54d;` and the two tension rolls Mld and Mid are supported on rocking frames 3Id which are .carried on cross shafts' l31d, and:`

whichcan-be drawn toward each other (toconcurrently subject thebelts Nit-30d ion each end of the roll assemblies to equalized tensions) by 'a turnbuckle connection 1531i. r At aworking tension of 2000 lbs., and linear (peripheral) speed of 600 feet per minute pairg of belts Bild- 881 or slid-Bild, can .trans-y 'l mit about 73 H, P.v to one lofthe working rolls;

or a total of approximately 145 H. P. to thel two. If we add this to the total H.P.' transmitted .by

the three vzone helical gear drives previouslyde'- scribed we 'have-an aggregate of over 500 H. Il.'

II- that may be imparted to the small working-rolls (M -2d) from'the power receiving rolls 22! .iependently of any frictlonal `driving action that is obtained by the non-slipping pressure engagel ment between these rotating elements. thev.construction now 'under consideratlonf-where the axes ofv the'engaged rolls ld v22l- 3d, and 2d-225 4 are all positioned-in the same vertical planethe contact pressure between the driving44 and driven elements is substantially l equal to the pressure of the working rolls on the materiahjand if this is 20,000 lbs. per inch of width (as previously'assumed) the'power transmitted by the non-slipping frictional engagement of the roll elements 22S- ld and 22B-2d is,

stripmill. This lis lless than that obtainedI in somev of the forms` of t "cluster mills previously described; but it is more than sufficient to Ioperate a sixhigh'revrsing .mill of the character t 45 nowfunder consideration. 'l 1 One of the advantages of-` thej construction .shown in Figs. XXX, XXXI afndXXXII is that the helicalfgears which communicate motion to f ythe working rolls-and thus maintain them in non-slipping relationship'to the power receiving rolls 225 are all of relativelyv small slze,'and are therefore less -expensive-toconstruct than the# i large gear elements li-I5, lla-lla, MU-IIb, or Ill-|11 with which` the mainbacking'rolls g5 3 4, 3ft-4a, etc.v must be provided when the latfter 'are in direct pressure engagement with'the lworking rolls; and are used to communicate pow.- er thereto. through the frictional grip of the engaged surfaces, 00 (225) is interposed between eachworking roll (la or zd) and the associated backing roll (3d or I vId), -it is of course unnecessary vtov positively drive 'eitherl of the latter elemente-which in this case perform only the function of receiving -aiyan'dsu'staining the major part of the vertical 75 thereto, are rigidly secured as units to thejournal 23o-23D is therefore supported 'in 'flied axial 'smallfpart ofY that pressureis re'ceivedy by the chock platey and cross headbearing elements .z 28-221;' t he major part oflthis vload bein'g bearings of the main-'backing r umd-4d; The

c In thecase of a reversingmil nal supports ltdlare each provided with ya central lin thesleeves themselveslr'I'he bearing surfaces of the cross heads 221 are 'continuously'suppliedf` When a 'power receiving roll `1:3 members lid; and that each setofy power tranii-y mitting andl supporting' rolls t (22l-23l'239 relationship to the associatedbackingrroll (3d or 4d); yand when either of theal'atter rolls iii;- moved .`'either by the'adiustmentjof the leveling plates f and screws 2nd,' or by the holding down and lifting screws 20|d, 2|6dthe corresponding set subjects@ duringy the rolling of thematerial.- is first coihmunicatedto the power. ieceiving rolls 225;l initv the einterco'nnected bearing supports I6d`-226221f`are so assembled that only a very transmitted to, and sustained/bypthejournal only lood` which must pe carried y the cross head bearing elements 2321?-232 is vthat produced by alateral pressurey `on the castor rolls 2301-230 Y and .on/ the associated supporting rolis freiem;

and a substantial component of the pressure |is sustained bythe rolling co ntact of theelements 23| on-the largerrolls225. i

l--fwhere tle rolls, revolved nrstin one directio/n 'and then in the other. provisionmust be"m`ade lfor introducing lubricant at both sides ofthe roll bearings, IIn the Iconstruction here illustrated thebakingrolliiour-l longitudinal kpassagewayv dJ-which is supplied with oil from an outside reservoir (not shoWnY-- and with a series of radially disposed ducts' 52d 35 that'lead to two of thepocketsoi` grooves,in which the vjournalsleeveloolts Illd are located (see Fig. 1K2!) ,t and from -which the oilpasses to the bearing surfaces through suitable 4perforations with lubricant f rom `the hollow through bolts f v.22S-##229, and suitable ducts leading therefrom to the edges of thebearing b1ocks;'and the revolving elements 23 I ,and 230 are also' ushed with oil from one of the 'tubular bolts 22s ondlongitudn nal passageways 60d inthe cross heads 232. In this ,construction-as in all of those previously 'consideredthe design is such that the unit pressure on any baringsuriace is well within the n limit of rupture pressure of the oil ilim; and when adequate provision is made/for the festablishment and continued maintenance offthis l there-is no advantage t9 be gaineurabut-o the contrary there is a disadvantage to be met by.v a substitution of ball or roller bearings in plaqe of the plain cylindrical journal'bearings herein' described. i It is alsowell lunderstood by those skilled in, the rolling art that thev spreading pressure on the working rolls, and the powerrequired to drive them at any given speed, is not only decreased by reducing the vfsize of these rolls,'but also by applying a .tension to the material passing between them. This tenson may^be eitherra for-U ward (or positive) one--whichftends to-pullthe material through the roll passor 'a backward (or negative) one-which tends to retard the forward movement-or better -still a combination of both positive and negative `tensions. In the 70

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