US1980570A

US1980570A - Rolling mill

Info

Publication number: US1980570A
Application number: US628675A
Authority: US
Inventors: Jr Florence C Biggert
Original assignee: United Engineering and Foundry Co
Current assignee: United Engineering and Foundry Co
Priority date: 1932-08-13
Filing date: 1932-08-13
Publication date: 1934-11-13
Anticipated expiration: 1951-11-13

Description

Nov. 13, 1934. F, c. BIGGERT, JR 1,980,570

ROLLING MILL Filed Aug. 13. 1932 8 Sheets-Sheet l LJQy/ W/T/YEJSLS I I I V Madam- B /W W M A TTORNE YA.

(I ll L lll 8 Sheets-Sheet 2 ROLLING MILL F. C. BIGGERT, JR

Filed Aug. 13. 1932 Nov. 13, 1934.

Nov. 13, 1934. F. c. BIGGERT, JR 1,930,570

aoLLIN MILL I Filed Aug. 15. 1952 8 Sheets-Sheet 3 11v VENTOR. WIT/YEJSES M 6 mad BY mm zw mm d ATTORNEYS.

Nov. 13, 1934. F. c. BIGYGERT, JR

ROLLING MILL Filed Aug. 13. 1952 8 Sheets-Sheet 4 J m gNTOR. lama/44 C r B Y/ 53 A TTORNE Ys 1934. F. c. BIGGERT, JR 1,

ROLLING MILL Filed Aug. 15. 1932 8 Sheets-Sheet 6 NfiNTOR. BY i I i W ATTORNEYP.

W/T/YESSES WW 6 0 Nov. 13, 1934. F c, 5 G JR 1,980,370

ROLLING MILL Filed Aug. is. 1932 Y a Sheets-Sheet 8 I INVENTOR. WM JML Q W ab 1M 6 .m

A TTORNE Yr.

WITNEJU'ES Patented Nov. 13, 1934 PATENTOFFICE Florence C. Biggert, Jr.,

United Engineering ROLLING MILL Grafton, Pa., assignor to & Foundry Company,

Pittsburgh, Pa., a corporation of Pennsylvania Application August 13,

29 Claims.

My invention relates to rolling mills, and particularly to rolling 'mills for producing relatively thin sheets of metal.

\ In the operation of rolling mills for producing relatively thin sheet metal, difliculty has been encountered in securing sheets of uniform thickness and within the limits of tolerance usually permitted. Such difliculties have resulted from a number of causes, including, the elasticity of the materials constituting the rolls, bearing blocks and the roll housing of the mill.

This elasticity or stretch has permitted the 7 rolls and bearing blocks to be bent or compressed when the metal is being rolled and at the same time has permitted portions of the housing to elongate while other portions such as the top and the bottom deflect as beams. The result has been that the adjustment of the rolls prior to the entering of the metal to be rolled is not an accurate measure of the thickness of the finished metal by reason of the changes occurring in the dimensions of the various parts of the mill when the metal enters the rolls. v

Furthermore, breakages have occurred when the metal to be rolled, by reason of its temperature or other conditions causes forces .to be set up within the rigidly adjusted mill that are beyond the strength of the materials for resisting them;

In order to materially diminish the variations in dimensions and other inaccuracies with respect to the sheets of metal produced, I propose to place the housing and the bearing blocks of the mill under initial stress by means of hydraulic cylinders or other fluid-pressure devices, this pressure exceeding that normally encountered in the operation of the mill for rolling metal. I also provide that the parts of the mill within which changes in stresses occur when a piece of, metal enters the rolls occupy relatively short spaces whereby the effect of these changes is correspondingly diminished.

The pressure thus initially applied places the bearing blocks for the backing rolls and the housing under stresses greater than those caused by metal between the rolls and the effectv is much different than if the stresses were caused by the working pressures of the rolls "of I the mill. By reason of the application of these initial stresses the entrance of the metal causes substantially .no additional elongation of the housing and the bearing blocks for the backing rolls are not substantially compressed further. When metal enters the working rolls; the effect is to relieve the bearing blocks and spacingv 1932, Serial No. 628,675

(01. so-se) blocks therebetween of a portion of the stress thereon and to transfer it to the working rolls and the backing rolls therefor.

The result is to initially elongate the housing and to deflect the parts acting as beams to an extent that will not be appreciably alteredduring the operation of the mill, the pressure being maintained constant both before and after the metal enters the rolls. This arrangement has been found to eliminate the major portion of the variations in thickness of the metal after the rolls have been adjusted.

The provision of fluid-pressure devices for placing the bearing blocks under compression has also eliminated breakages of the rolls or of the housing by reason of'the fact that the fluidpressure devices permit the rolls and'the bearing blocks to yield .in case of excessive hardness of the metal being rolled or any other occurrence that might otherwise cause breakage. In such case, the source of fluid pressure maintains a constant pressure upon the mill regardless'of the positions of the bearing blocks and the rolls.

In rolling mills of the prior art, the housing has been placed under stress that is eitherdependent upon or is set up by the rolling pressure or reactions therefrom but only while the mill is rolling metal. Such stress can not be applied to stretch the housing before metal enters "the rolls nor can it exceed, the rolling pressure. There will therefore be material variations in the dimensions of. the mill when metal enters the rolls.

Instead of the usual screw-down mechanisms employed for adjusting the distances between the rolls and the, resultant thickness of material rolledby the rolling mill, I employ wedges, the longitudinal position of which determines the distances between the bearing blocks for the backing rolls of a mill and thereby determines the distance between the working rollsand, accordingly, the thickness 01 the resulting sheet metal. In order to insure that both ends of the rolls are adjusted for the same thickness 01. metal, I have arranged that the wedges for each end of the roll may be adjusted either simultaneously or independently in case of a variation in relative position of the wedges for the respective ends. 1

An important feature of the arrangement of the screw-down mechanism is that it is located variation in relative position of the wedges at the respective ends of the rolls, I provide an indicating mechanism which indicates the relative positions of the wedges at the respective ends of the rolls and which also indicates the thickness of metal for which the rolls are adjusted.

. The details of my invention will be described ,mill of Fig. 1. 20

Fig. 5 is a view similar to Fig. 4 but taken at right angles thereto.

Fig. '6 is an enlarged view in vertical section taken on line VI-VI of Fig. 3.

Fig. -7 is an end elevational view of the wedge operating mechanism of Fig. 3.

Fig. 8 is a front elevational view of a portion of the mill of Fig. 1 with the indicating mechanism in position; and

Fig. 9 is a view in end elevation of the mill of Fig. 1 illustrating a portion of the indicating mechanism, the rolls of the mill being shown diagrammatically, and parts being broken away.

A rolling mill constructed in accordance with my invention comprises a frame 1, which consists of a base structure 2, upon which is mounted two vertical rectangular roll housings or side frames 3. Each housing 3 comprises two vertical posts-4 that are connected by a top 5. The housings 3 are indirectly connected through blocks 12 at both their front and rear portions by horizontally extending brackets 6.

The rolls are arranged for a four-high mill and comprise two relatively large backing rolls 7 and 8 and two relatively small working rolls9 and 10. Within the rectangular space ofeach of the housings 3 are mounted bearing blocks 12 and 13 for the respective ends of the backing rolls '7 and 8. These blocks are held in place between the vertical posts 4 by means of clamping plates 14 having bolts 15 that extend through slotted openings 16 whereby the clamps may be moved into and out of clamping position.

Between the upper and the lower bearing blocks 12 and 13 and at each end of the latter are two

blocks

17 and 18 that have substantially cylindrical adjacent surfaces, as best shown in Figs. 2 and 5, and that have a tongue-and-groove connection at 19 as shown in Fig. 4. The

blocks

17 and 18 are held in position between the bearing blocks 12 and 13 by means of outer flanges 20 projecting vertically from the bearing blocks 12 and 13 and are held in their spaced positions by means of projections 21' on the respective blocks 12 and 13.

In the recesses formed by the spaces between the respective pairs of

blocks

17 and 18 are mounted bearing blocks 22 and 23 for the respective working rolls 3 and 10. The bearing blocks 22 and 23 are held in position axially of the rolls by means of clamps 24 that are provided with bolts 25 and slotted openings 26 similar to those of the clamps 14. Each clamp projects into a groove 27 in the respective blocks.

Hydraulic cylinders 28 and pistons 29 therefor between the blocks 22 and 23 are employed to normally maintain the rolls -9 and 10 against their respective backing rolls 7 and 8 in order that these respective pairs of rolls may be in engagement at all times, regardless ofthe presence of metal between the working rolls.

' As best shown in Figs. 1 and 2, the tops 5 of each of the end frames 3 are each provided with two hydraulic cylinders 31 and pistons 32 therefor for bearing on the tops of the corresponding bearing blocks 12 for the backing roll 7. This hydraulic pressure is normally exerted against the backing roll 7 for retaining the working rolls at the adjusted distance of separation for maintaining the thickness of the metal being rolled. The distance between the working rolls is determined by two pairs of

adjustable wedges

33 and 34.

The upper wedges 33 are located between the backing roll bearing block 12 and the blocks 17 at each end of the block 12. The lower wedges 34 are located between blocks 18 and backing roll bearing block 13 at the opposite ends of the rolls. A link 35, pivotally connected to each of the upper wedges 33, extends through a slot 36 in the blocks 17 at the other ends of the rolls. The lower wedges 34 are pivotally connected to links 49, and the

links

35 and 49 are provided at their outer ends with yokes or

clevises

37 and 38; respectively, by means or which they are connected to mechanisms for longitudinal adjustment.

Wear plates 39 are provided between the wedges 33 and the bearing blocks 12 and similar wear plates 40 are provided between the wedges 34 and the cooperating bearing blocks 13.

The mechanism for actuating the

wedges

33 and 34 longitudinally to control the distance between the working rolls 9 and 10 is shown in position on the driving side of the rolling mill in Figs. 1 and 2, and in enlarged detail in Fig. 3. This mechanism which is supported by suitable brackets 41, comprises two electric motors of the worm gear 46 causes longitudinal mov-' ment of the shaft 47 and through the link mechanisms described above the longitudinal actuation of the

wedges

33 and 34.

Referring particularly to Fig. 3, it will be noted that the upper motor 42 is connected to a train of mechanism in series comprising a coupling 51, a worm gear mechanism 43 for one of the wedges 33, a clutch 52, a worm gear mechanism 43 for the other wedge 33, a second coupling 51, and a bevel gear mechanism 53 com- T pirsing a horizontally projecting shaft 54. The

lower motor 42 is connected to a similar train of mechanisms for operating the lower wedges 34.

The bevel gear mechanisms 53 of the upper and the lower trains of mechanisms are connected by means of a clutch 55. The upper clutch 52 may be operated to adjust any difference between the ,positions of the wedges 33.

of the wedges 34. The, clutch 55 affords a convenient means of adjustingdifierences between the corresponding positions of the pairs of

wedges

33 and 34 in order that the working rolls maybe exactly parallel.

It will be noted that the wedge-actuating mechanism or screw-down is open at its central portion to permit access to the ends of the working rolls 9 and to permit driving connections theretothrough the opening thus provided.

It will be understood that in the operation of the wedge-actuating mechanism the motors 42 are operated simultaneously and when the clutches 52 and the clutch are in engagement all of the worm gear mechanisms 43 operate simultaneously and to the same extent to adjust the positions of the pairs of wedges 33' and 34. In case of unequal wear, however, such inequality may be compensated for by temporarily releasing either of the clutches 52 or.

the clutch 55, as thecase may be, for approcylinders 31 from any convenient source of con-- wedges operate to secure uniform spacing of the working rolls 9 and 10. y

In order that the spacing of the working rolls 9 and 10' may be readily determined, I have provided indicating mechanism for measuring the distance between the rolls and for indicating-also whether or not the working rolls are parallel. The indicating mechanism is best illustrated in Figs. 8 and 9. Attached to the end of of each shaft 54 of the wedge-operating mechanism is a worm-gear mechanism 57, the details of which are not illustrated, for operating shafts 58 and 59, respectively.

The shaft 59 is connected by a bevel gear mechanism 60 to a hollow shaft 61., and 'the latter extends across the front of the mill and is protected by a guard, or shield, 62. The hollow shaft 61 is connected at its right-hand end, as viewed in Fig. 8, to a pointer 63 which operates over the face of a dial 64 that is calibrated in suitable units of distance. The shaft 58 extends through a bearing 66 and the hollow shaft 61, and is connected to'a second pointer 67 which also operates in connection with the dial "64.

From-the foregoing it will be apparent that the pointer 63 indicates the position of the ends of the working rolls controlled by the wedges 34,

' while-the pointer 67 indicates similarly 'the position of the ends of the working rolls controlled by the wedges 33. In actual practice when the relative positions of the wedges are accurately adjusted and the rolls are parallel the pointers 63 and 6'7 will coincide, but they have been shownspaced apart for convenience of illustration. The coincident positions of the pointers also indicate on the dial the distance between the working rolls and accordingly the thickness of the finished sheet metal.

In the operation of the rolling mill of my invention it may be assumed that it is desired to roll sheet metal to-a certain thickness. The motors 42 are operated to adjust the wedges until the

coincident pointers

63 and 67 indicate upon the dial, 64 that the working rolls 9 and 10 have been adjusted to produce metal of that thickness. Fluid pressure is then applied to the stant pressure'(not shown), such, for example, as that of an accumulator which maintains substantially constant pressure regardless of the positions of the pistons 32 in the cylinder 31. 4

This pressure is greater than that normally necessary to maintain the rolls'in the positions to which they have been adjusted, and therefore places the housings of the mill under greater stress than would ordinarily be the case during the rolling of the metal. Accordingly, the housing and other portions of the mill are subjected to stress pri'orto the rolling operation and except as noted below these stresses are not changed by the introduction of the metal between the rolls.

The metal may then be introduced into the rolls and the stress thathas been applied to the series of blocks comprising blocks 12 and 13' and

intermediate blocks

17 and 18 at each blocks 17' and 18 to the working rolls 9 and 10 and backing rolls 7 and 8. Inasmuch as the pressure necessary. to roll the metal is less than that applied to the blocks 12 for the bearing roll 7 by the hydraulic pistons, there will be very slight change in the positions of the working rolls caused by the shift in stresses. It has been determined that the spread of the working rolls due to the pressure imparted to them by the blank being rolled is about one-fourth of the stretch of a roll housing built in the ordinary manner with screws for positioning the upper rolls. The pressure applied to the backing roll, bearing blocks 12 is maintained constant by the fluid pressure cylinders 31 whether or not metal is being rolled in the mill. 9

By referring to Figs; 2 and 4 it will be noted that-the cross-sectional areas of the spacing blocks 17 and 18, which are placed under compression by the hydraulic system including the cylinders 31 and pistons 32, are considerably greater than the cross-sectional areas of the vertical posts 4 of the housings 3. The cross-- sectional areas'of the bearing blocks 12 and 13 are much greater than those of the pairs of spacing blocks 17 and 18 which separate them. In addition, the housings are placed under tension while the bearing blocks and spacing blocks are under compression.

The effect of these differences in cross-sectional areas is to cause the unit stress on the' bearing blocks'and spacing blocks to be considerably less than that on the housings. In addition, the change in dimensions is less under compression than under tension whereby the shifting of a certain amount of stresses from the spacing blocks and portions of the bearing blocks to the working rolls and backing rolls when metal enters the rolls causes relatively small change in the vertical dimensions of the spacing blocks and accordingly very little change in the adjustment of the positions of the rolls.

In case adjustment of I the working rolls is necessary after metal enters the rolls, the screwdown mechanism may be operated at any time farther apart, but no additional strain is placed Y upon the housing or associated parts of the mill because the pressure for resisting this separation does not exceed that of the constant pressure applied to the cylinders-31. Accordingly,-

breakage, such as usually results from conditions of this character, is substantially entirely avoided.

When the rolling operation has been completed and the fluid pressure applied to the cylinders 31 is released, thepistons 32 are returned to their uppermost positions by discs 69 beneath the lower ends of the .pistons, rods 70 and springs 71 that have been placed under compression during the downward movement of the pistons to'bear against the bearing roll '7. The springs 71 are of sufficient strength to compensate for the weight of the pistons 32.

The provision of the cylindrical surfaces between the

blocks

17 and 18 enables them to adjust their relative positions to maintain full face contact with the cooperating

wedges

33 or 34, as the case may be. Unless this adjustment were possible edge contact. with the wedges would occur when the rolls were canted which condition is sometimes necessary or desirable. Such relative adjustment may be necessary also because of wear. 5

It will be noted from the foregoing that I have provided a rolling mill that possesses the advantages of initially placing the housings and other portions of the mill under stress greater than that ordinarily encountered in rolling metal, whereby the stretch or elongation of the housings occurs before the metal enters the mill. The entering of the metal causes a change in stresses in a relatively small portion of the mill. The effect is to very materially diminish any change in the distance between the rolls of the mill caused by introduction of the metal and thereby decrease the variations in the dimensions of the finished metal. 5

An important advantage of my rolling mill resides in .the fact that the pass or opening between the working rolls may be varied before metal enters the rolls, and that stress greater than the rolling pressure may oppose the separation of the working rolls without placing the latter or their bearing blocks under stress until metal enters the rolls. v

The location of the entire screw-down mechanism on the driving side of the mill is of importance in that all of the assembled rolls and their associated bearing blocks and spacing blocks may be removed as a body from the mill without obstruction and may be assembled without the mill for return thereto as a body. The

- convenience of this feature will be appreciated by those experienced in the replacement or repair of rolls and associated parts of a rolling mill.

The arrangement for adjusting the distances between the working rolls is simple in construction and effective in operation to secure an accurate adjustment of the working rolls to produce metal of uniform dimensions. The arrangement is such that any variation in the positions of the ends of the working rolls may be readily detected and may be conveniently adjusted for the purpose of providing uniform spacing.

I have provided also a simpleand convenient indicating mechanism whereby the relative positions of the ends of the working rolls may be determined at a glance, and whereby the adjustment of the rolls for a desired thickness of metal may beaccomplished easily and conveniently.

The foregoing and other advantages'will be apparent to those skilled in the art of consimultaneously or independently.

blocks, mechanical means for engaging certain of said blocks for adjusting the spacing of said working rolls, fluid'pressure devices for placing said housing and certain of said bearing blocks under stress prior to the introduction .of metal to the working rolls that is greater thanthat caused by the introduction of metal, means preventing said stress from being communicated to said rolls and'means'for-adjusting said mechanical means regardless of the application .of fluid pressure by said devices.

2. A rolling mill comprising a plurality of backingirolls, housings for the respective ends of said rolls, bearing blocks for said rolls that are separated by spacing blocks at each end thereof, working rolls between said backing rolls and having bearing blocks located between said spacing blocks, means for placing said housing and said backing roll bearing blocks and said spacing blocks under stress prior to introduction of material to be rolled, and means for adjusting the spacing of the bearing blocks forsaid backing rolls whereby when metal is rolled between said working rolls, stress is transferred from said spacing blocks to said working rolls.

3. A rolling mill comprising a plurality of backing and working rolls, bearing blocks there-' for at each end thereof, means comprising wedges co-operating with said bearing blocks at each end of said rolls to determine the thickness of the material rolled thereby, and mechanism comprising two pointers for indicating the relative adjustments of the wedges at the respective ends of said rolls and a dial cooperating with said pointers to indicate the distance between the working rolls corresponding to said adjustments.

4. Arolling mill comprising a plurality of working rolls, a plurality of backing rolls having bearing blocks therefor at each end thereof, means comprising wedges co-operating with the bearing blocks at each end of the rolls for ad justing the distance between said working rolls to regulate the thickness of the metal rolled thereby, means for adjusting said wedges at the respective ends simultaneously or independently, and indicating mechanism comprising two pointers movable respectively with the adjusting means for the wedges for the respective ends of the rolls, anda dial calibrated in units of distance between said working rolls for co-operating with said pointers.

5. A rolling mill comprising a housing, a plurality of. backing rolls, bearing blocks therefor at each end thereof, a plurality of wedges comprising spacing elements disposed between and engaging said bearing blocks at each end of said rolls for regulating the relative positions of said rolls to determine the size of the working pass of the mill, and means for adjusting the positions of the wedges at the respective ends 6. A rolling mill comprising a housing, a plurality of rolls, bearing blocks therefor at each end thereof, a plurality of wedges at each end spacing blocks.

.said working rolls to thereby determine the size ends simultaneously or independently, a said means comprising a shaft connected to the wedges for each end and means for detachably connecting said shafts for rotation together.

7. A rolling mill comprising a'housing, a plurality of rolls, bearing blocks therefor at each end thereof, a plurality of wedges at eachend of .said rolls for cooperating with the corresponding bearing blocks to regulate the relative positions of said rolls, and means for, adjusting the positions of the wedges at the respective ends simultaneously or independently, said means comprising a motor for the wedges at each end of the rolls and a detachable clutch for connecting said motors.

8. A rolling mill comprising a housing, a plurality of rolls, bearing blocks for said rolls at each end thereof, means for regulating the distance betweencertain of said rolls, said means comprising a plurality of wedges for co-operating with the bearing blocks at each end of said rolls, a mechanism for actuating each of said wedges, means for detachably connecting the mechanisms for the wedges'at the same ends of the rolls, means for detachably connecting the mechanisms for the wedges at one end of the rolls to the corresponding wedges at, the otherend of the rolls, -and-driving means for said mechanisms, whereby said mechanisms may be actuated relatively to each other orsimultaneously as desired.

9. A four-high rolling mill comprising two working rolls, two backing rolls therefor, bearing blocks for the respective rolls, a housing for said rolls and said bearing blocks, two wedges disposed between and engaging the bearing blocks for said: backing rolls for regulating the distances between the bearing blocks for the back,- ing rolls at each end thereof to thereby regulate the distance between the working rolls, means,

for actuating the two wedges at each end of the rolls simultaneously or relatively to, each other, and means for actuating the wedges at one end of the rolls simultaneously with or-relatively to the wedges atthe other end.

10'. A rolling mill comprising a plurality, of backing rolls and of working rolls, bearing blocks at the ends of the respective rolls, blocks for spacing the ends. of the backing rolls and having adjacent curved surfaceswhereby the spacing blocks may adjust themselvesangularly relatively to each other, and means engaging said spacing blocks for controlling the spacing of said backing rolls and for controlling the angular position of said spacing blocks,

11. A rolling mill comprising a plurality of backing rolls and bearing blocks therefor at each end thereof, a plurality of blocks for spacing each of the corresponding ends of said bearing blocks, the spacing blocks having adjacent curved surfaces for relative angular move: ment, means for'engaging said'spacing blocks to determine the spacing eifected thereby and for controlling the angular position of said spacing blocks, and a plurality of working rolls and bearing blocks therefor located between said 12. A rolling mill comprising a plurality of working rolls having bearingblocks therefor, a plurality ofv backing rolls having bearing blocks therefor, and adjustable means disposed between the bearing blocks for said backing rolls for positively varying the distance between said back-,

ing rolls prior to the entry of metal between of the roll pass formed by the working rolls.

13. A rolling mill comprising a plurality of rolls having blocks certain of which rolls define a pass or opening for metal to be rolled, means for applying a predetermined pressure in excess of the rolling pressure opposing the separation of the pass-defining -rolls, means disposed'between said bearing blocksfor adjusting the positions of said pass-defining rolls and means operable while said pressure is applied for operating said adjusting means.

14. A rolling mill comprising a plurality of working rolls having bearing blocks therefor, a plurality of backing rolls having bearing blocks therefor, and means applying to the bearing blocks for said backing rolls,' and without placing'said working rolls or their hearing blocks under stress, a pressure opposing the separation of said working rolls which is greater than the pressure required for rolling.

15. A rolling mill comprising a pair of housings, a plurality of backing rolls having bearing blocks, a spacing block between each pair of bearing blocks at the respective ends of the rolls, and means for initially placing said housings, said'bearing blocks and said spacing blocks under stress greater than that caused by the rolling pressure when metal is passing through the mill, and said spacing blocks and said bearing blocks being of greater cross-sectional area than said housings, and thereby causing the unit stress on said bearing blocks and said spacing blocks to be proportionately less than that on said housings.

16. A rolling mill comprising a housing, a plurality of rolls therein, means for spacing certain of'said rolls, and means operable prior to the entry of metal into the mill for placing said housing and said spacing means under. stress that is greater than that caused by the rolling of the metal, said spacing means to which stress.

is applied having a cross-sectional area that is greater than the .cross-sectional area of said housing.

17. A rolling mill comprising a pair of housings, a plurality of backing rolls having bearing blocks, a spacing block between each pair spacing blocks to be 'at least approximately no greater than that on said housings.

18. In a rolling mill a pluralityof backing rolls and working rolls, bearing blocks at the ends of said rolls, and spacing blocks disposed between the bearing blocks for said backing rolls provided with curved adjacent surfaces adapted to permit them to adjust themselves angularly relative to eachother.

-' 19. In a rolling mill provided with roll housings, a plurality of backing rolls having bearing blocks, a pluralityof working rolls, means operable prior to rolling -placing said housing and said bearing blocks under stress greater than that caused by the rolling pressure when metal is passing through the mill, and spacing blocks disposed between said bearing blocks for resisting the movement toward each other of said backing rolls and preventing said initial stress being communicated ,to said rolls.

20. A 'rolling mill comprising a plurality of rolls having bearing blocks therefor, a housing for each end of said rolls having a window therein for the reception of said bearing blocks, means subjecting said bearing blocks and housing to an initial pressure in excess of the roll-- ing pressure, means preventing said initial pressure being communicated to said rolls and means preventing the rolling pressure from increasing the stress in the housings.

21. A rolling mill comprising a plurality of backing and working rolls having bearing blocks at the ends thereof, a housing for each end of said rolls having a window therein for the reception of said bearing blocks, means for exerting a pressure on said bearing blocks and a tension in said housings in excess of the corresponding stresses produced by rolling, means for prevent-,

ing the pressure set up by said last-mentioned means being communicated to said rolls, means for preventing the rolling pressure being communicated to said housings, and means for maintaining said working rolls in contactwith sa'id backing rolls. f

22. A rolling mill comprising a plurality of rolls having bearing blocks therefor, a housing for each end of said rolls having a window therein for the reception of said bearing blocks, a

pluralityof means at one end of each of said housings for exerting a pressure on the adjacent bearing blocks at opposite sides of the axis of the roll journalled'therein, said means being adapted to exert a pressure on said blocks and a tension in'said housing in excess of the corresponding rolling stresses, means preventing the pressure exerted by this means being communicated to said rolls, and means preventing the stant pressure of a suflicient value to exert a pressure on said bearing block and a tension in said housing in excess of the corresponding stresses produced by rolling, and means to prevent the pressure exerted by said pistons on said bearing blocks being communicated to said rolls. f

24. In a rolling mill comprising a plurality of rolls, a housing having a window therein for supporting the ends of said rolls, means for setting up a pressure prior to rolling between the ends of said window which isadapted to stress said housing and resist the separation of said rolls without placing the rolls underhpressure and which is so disposed as to permit the rolls to assume said pressure when metal is entered between the rolls, and means for maintaining the pressure substantially constant befor and .after insertion of the metal 25. A rolling mill according to claim 24 including means operable between the ends of the rolls for determining the size of the roll pass.

26. A rolling mill comprising a plurality of working rolls, a plurality of backing rolls having bearing blocks therefor, means located at the opposite ends of said backing. rolls for regulating the distance therebetween and determining the thickness of the material being rolled,

means for communicating .to a common point the movement of the-regulating means at both ends of the rolls, and common means cooperating with said last-mentioned means for indicating the position of adjustment of both of said regulating means. v

27. A rolling mill comprising a plurality of backing and working rolls having bearing blocks therefor and adapted to be driven at one -end thereof, a housing for said rolls and said bearing blocks, means disposed between and engaging Y 28. In a rolling mill, a plurality of backing' rolls and working rolls, bearing blocksat the when material is being rolled which consists in placing the supporting housing for said rolls under tension prior to rolling withoutlsubjecting the rolls to pressure and preventing the rolling stress appreciably increasing the tension in-said housing.

FLORENCE C. BIGGER'I', JR.