US2985042A

US2985042A - Rolling mill

Info

Publication number: US2985042A
Application number: US810099A
Authority: US
Inventors: Howard H Talbot
Original assignee: United Engineering and Foundry Co
Current assignee: United Engineering and Foundry Co
Priority date: 1959-04-30
Filing date: 1959-04-30
Publication date: 1961-05-23
Anticipated expiration: 1978-05-23
Also published as: GB947591A

Description

H. H. TALBOT ROLLING MILL May 23, 1961 Filed April 30, 1959 NN mm HowARp H. TALBOT Hls ATTORNEY nited States Patent O ROLLING MILL Howard H. Talbot, Pittsburgh, Pa., assignor to United Engineering and Foundry Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 30, 1959, Ser. No. 810,099

1 Claim. (Cl. 80-38) This invention relates to rolling mills employed in the reduction of metallic strip-like material and particularly to a mill adapted to produce a rolled product characterized by having a substantially uniform cross-sectional thickness across the width thereof.

In the use of present-day mills, experience has shown that itis very difficult to produce a strip having a uniform thickness across its width primarily by reason of the inherent deection of the working or metal engaging rolls of the mill. On being subjected to the forces during rolling which tend to separate the rolls, the rolls act somewhat the same as beams supported at their ends and. subjected to a substantially uniform load distributed along most of the length thereof, the distance over which the uniform load acts being of course, dependent upon the width of strip material being processed. As in the case of a structural beam, the rolls are subjected to thel greatest deflection at their centers. Where the same reduction is to be taken, for example, in one mill having small diameter work rolls and in another mill having large diameter work rolls, the small diameter rolls will have imposed upon them a separating force less than that to which large diameter rolls are subjected. However, the small diameter rolls, as will be apparent, also resist bending less than do large diameter rolls.

In order to overcome the diiculties which are to be expected when mills are employed having work rolls of small diameter and without sacrificing the advantages to be gained by using such rolls, modern mills are provided with a large diameter backing-up roll for each work roll, the axes of which are arranged in the same vertical plane as those of the work rolls and the surfaces thereof in frictional contact throughout the roll body length. This type of mill is commonly referred to as a four-high mill. The larger diameter rolls, though they are in supporting engagement with the work rolls along the entire length of the roll body, resist but do not completely nullifyv the bending forces set up in the mill during normal operation thereof. Thus, even with the increased rigidity provided by the large diameter back-up rolls, there will be at times substantial bending or deflection not only of the back-up rolls but, of more importance, the work rolls as well, so that if the rolls are crowned, the crown will be exceeded Vby the deection of the rolls caused by the rolling loads imposed thereon. In mills Where the rolls are of substantial length, the magnitude of the exing or bending is quite pronounced so that the rolled product will be characterized with a definite variation in thickness across the width. Y

In an effort to compensate for the deection of the work rolls and/or the backing rolls, both of the work rolls and/r both of the back-up rolls are crowned or cambered, i.e., ground in such a fashion that the diameter of the roll gradually increases from the ends to the center. It will be appreciated that the extent of the crown formed on the rolls will vary widely by reason of the variable conditions under which mills employing such rolls may be required to operate. The extent of the crown will depend ice upon the type of mill, length of rolls, metallurgical characteristics of the strip material being reduced, the pressures imposed upon the mill, the width of strip, the thermal conditions and the amount of reduction to be taken. Since the crowning of the rolls is determined primarily on the basis of but one combination of these variables, it is apparent that the crown will not be wholly satisfactory for any other combinations of those variables as may be encountered. When conditions of rolling are to be varied from one combination to another, then, in order to provide, a substantially flat pass, the rolls in the mill must be replaced with other rolls having a different crown. v

With the foregoing in mind, it is one of the objects of this invention to provide a rolling mill which is constructed in such a fashion that the rolls of the mill will be so supported and the crown thereof so controlled that a substantially uniform pass between the work or processing rolls will be maintained during a rolling operation thereby to produce a rolled product having a substantially uniform thickness across its width.

It is another object of this invention to provide a mill having small diameter work rolls each supported substantially along the entire length of the roll body by back-up rolls, which in turn are supported in an area adjacent to the central portion thereof by relatively large diameter short bodied rolls, the degree of support offered by such rolls being determined by the degree of the crown for which control is to be provided.

A further object of this invention is to provide a rolling mill having back-up and working rolls in which crowns are formed either on one or both of the working rolls and/ or on one or both of the backing rolls in which there is included a relatively large diameter short-bodied supporting roll for engagingwith each of the back-up rolls thereby to restrict the deection of the back-up rolls and, hence, augment or control the effect of the crown on the rolls so that the crown will be made elective over a relatively wide range of rolling conditions for producing a product of uniform thickness irrespective of the width thereof.

Still another object of this invention is to provide controlled variable pressure applying means in contact with and by which pressure may be exerted upon each of the back-up rolls of a four-high mill to limit the deflection of the rolls and, hence, control the crown thereof over a wide range of rolling conditions to which the mill may be subjected and thus provide a substantially uniform pass between the work rolls.

These objects, as Well as the various other novel features and advantages of this invention, will be apparent from the following description and accompanying drawings of which:

Fig. l is an end elevation view of a mill in which there are embodied the features of the invention herein disclosed;

Fig. 2 is a side sectional elevation view taken on line Il-II of Fig. l, and

Fig. 3 is a side sectional elevation View similar to fig. 2 in which the invention is embodied in modified orm.

With reference to Figs. 1 and 2, there is illustrated therein a mill which comprises a pair of housings 11, secured together at the top and bottom by separators 12 and13 respectively, and in which there are included a pair of work rolls 14, a back-up roll JIS in engagement with and `for supporting the upper work roll and a back-up roll 16 for supporting the lower work roll. The work rolls are supported at their ends in suitable bearing-chock assemblies 17, one end of each roll being extended and to which a coupling 1S is secured for driving the rolls. The ends of the upper back-up roll 15 are mounted in bearing-chock assemblies 19 which are engaged by suitable screws 21 which are threaded in the upper portions of the housing and'actuated by a worm gear drive 272.within whichfthe upper portions of the screws are'received and slidably engaged in suitable Asplines 23. The lower back-up roll 1'6 Vis supported at 'its ends in suitable bearing-chock assemblies 24 which, in turn, rest on the housing at the bottom of the windows.

At the central body portion or areaof the upper backup roll 15, and in engagement therewith, -there is arelatively large diameter short-bodied supporting roll 25 secured at its ends in bearings 26 within a frame 27 confined andslidably guided for vertical movement between the housings 11 and urged normally Yin an upward direction by a piston cylinder assembly 28 connected tothe 'frame 27 and to the separator 12. The ends of the Vframe 27 are engaged by pistons 29 which extend downward from cylinders 31 mounted within lopenings Vin the upper separator 12. Y

In engagement with the central body portion or area of the lower back-up roll 16, there is a relatively large diameter short-bodied supporting roll 32 which is mounted in suitable bearings 33 within a frame 34. The frame 3 4 is confined and slidably guided for vertical movement between the housings 11 and normally vurged'in an upward direction by a pair of pistons 35 extending upward from cylinders 36 mounted withinV the lower separator 13.

Fluid at a controlled variable pressure is supplied to each of the

piston cylinder assemblies

29, 31 and 3S, 36 through suitable piping V37 connected to a controllable variable pressure pump 38 connected -to a source of fluid, not shown, which is driven by a variable speed motor 39.

Depending upon the crown of either or both of the work rolls 14 and/ or either or both of the back-up rolls and 16, pressure supplied by the pump 38, which is variable over a wide controllable range, will be of sufricient intensity to cause the

pistons

29 and 35 respectively `to exert the proper pressure upon the back-up rolls adjacent thereto thereby to supplement the effect of the vcrown on the roll or rolls so that during a reducing operation a substantially uniform pass will be maintained between ,the work rolls..v Y

As shown in Fig. l, suitable roll balancing piston cylinder assemblies 41 are provided between the bearing-

chock kassemblies

19 and 24 of the back-up rolls and similar assemblies 42 are provided between the bearing-chock assemblies 17 of the work rolls. Y

Fig. 3, which represents amodified embodiment of the invention disclosed herein, includes a mill having a pair of housings 51 secured togetherV by upper and lower separators 52 and 53 respectively, a pair of work rolls 54 and upper and lower back-up

rolls

55 and 56 respectively in contact therewith. The work rolls 54 are supported at their ends in suitable bearing-chockn assemblies 59 and the back-up rolls supported in suitable Vbearingchock assemblies 61 and62 respectively, the bearingchock assemblies being free to move .vertically within the windows formed in the housing.

In lieu of the screwdown mechanism employedk in the preferred embodiment of invention illustrated in Figs. l and 2, the means for applying pressure to the .ends of the upper back-up roll during a rolling operation comprises a pair of piston cylinder assemblies having cylinders 63 which are supported in the separator 52 and piston rods 64 extending downwardly therefrom and engaged with the bearing-chock assemblies 61. Suitable Vroll balancing piston cylinder assemblies, though not shown specically, are provided which are similar to those included in the preferred form of invention as shown in Fig. l. A controllable pressure pump 65, driven by a variable speed motor 66, delivers liuid at the proper pressure to the cylinders 6,3 through piping 67 connected therebetween.

Vln contact with the central body portion or area of the upper back-up roll 55, 'there isV a relatively large diameter short-bodied roll 68 mounted at its ends in suitable lbearings 69 within a frame 71 guided for vertical movement between the housings. The frame 71 is urged normally in an upward direction by a piston cylinder assembly 72 connected to the frame 71 and to the separator 52. The ends of the frame 71 are engaged byr pistons 73 which extend downward from cylinders 74 mounted within suitable openings in the upper separator 52.

Engaged with the lower backup roll 56, there is also a relatively large diameter short-bodied Vroll 75 which is mounted at its ends in suitable bearings 76 supported in a frame 77. The frame 77 is guided for vertical movement between the housings `51 and is normally urged in an upward direction by `a pair of pistons 78 extending upwardly from cylinders 79 mounted in suitable openings in the lower separator 53. Fluid at controlled variable pressure is supplied to the Ycylinders k74 and 79 through'suitable piping 81 connected to a controllable variable pressure pump 82 connected to a VSOlIlce of fluid, not shown, which is driven by a variable speed motor 83.

As mentioned heretofore, depending upon the material to be reduced, the reduction to'be taken, the width of material and the metallurgical characteristics of the material, pressure is supplied to the bach-up rolls by actuating the screws 21 of the preferred embodiment or by applying the desired pressure to the cylinders 63, of the modified embodiment, thereby to press the back-up rolls into engagement with the Work rolls to' establish the pass between the work rolls. During a strip reducing operation, the work rolls and the back-up rolls tend to bend outward at their centers and thus tend to create aA pass wider at the center than at the edges. For a given crown on some or allfo'f the rolls, and Without more, a iiat pass canwbeobtained as the rolls bend outward for one condition of rolling only. However, by means of the relatively large diameter short-

bodied rolls

25, 32, 68 and 75 by which co'ntrolled pressures may be imposed on the back-up rolls, additional resistance tobending of the back-up rolls and, consequently of the worl; rolls Vas well, is provided thereby augmenting or controlling the crown of the rolls so that a uniform pass between the work rolls over a wide range of rolling conditions is established. Merely by controlling the pressure supplied by the pumps to the

cylinders

31, 36, 74 and 79, a given crown on any or all of the rolls of the mill may be made most effective over a wide range of operating conditions whereby a uniform pass between the work rolls may be readily established and maintained irrespective of the reducing operations being carried out. Thus, the necessityV of changing to rolls having a different crown each time a new rolling condition presents itself is avoided.

Though this invention has been described as being embodied in a mill of which one or more of the rolls are crowned, it is to be appreciated that even though noneof the rolls is crowned, the control effected by this invention is of a character to offset the camber normally imposed upon the rolls during a strip reducing Operation.

rln accordance with the provisions o f the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof. However, I desire to have it understood that within the scope of the appended claim, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

A mill within which a fiat rolling pass is maintained fo'r reducing stripl of various widths continuously to form a strip of a substantially uniform thickness across the width thereof comprising a` housing, a pair of relatively small diameter work rolls between which the strip to be reduced is passed, a pair of relatively large diameter back-up rolls fo'r contacting and supporting said Work rolls, a crown related t, a given Width Qt strip t0 be reduced and formed on at least a pair of said aforementioned rolls to provide 5 i 6 a at pass for reducing strip of said given width, a rela- References Cited in the rile of this patent tively large diameter relatively short-body roll in contact with Ithe central zone of each df said back-up rolls, a pis- UNITED STATES PATENTS ton cylinder assembly operably connected to each of said 2,039,959 Iverson May 5, 1936 short-body rolls for applying to said back-up rolls a force 5 2,040,400 Paterson May 12, 1936 in a direction and of a controlled magnitude to supple- 2,267,380 Tyler Dec. 23, 1941 ment the effect of said crown when reducing Strip of 2,776,586 Sendzimir Jan. 8, 1957 said given width when required and when reducing Strip 2,907,235 Murakami Oct. 6, 1959 of width greater than said given width and means connected to and for establishing a controlled variable pres- 10 FOREIGN PATENTS sure adapted to be increased in intensity within said pis- 132,050 Germany July 3, 1902 ton cylinder assembly in connection with an increase in 226 327 Germany CCL 1, 1910 width of strip beyond said given width thereby to resist 111561216 France Dec 9, 1957 outwardly bowing and maintain a at rolling pass under conditions imposed upo'n the rolls by the increased width 15 of strip.