US2685807A - Four-high rolling mill - Google Patents

Description

Aug. 10, 1954 E. B. HUDSON 2,635,307

FOUR-HIGH ROLLING MILL Filed April 14, 1948 5 Sheets-Sheet l Au 10, 1954 v B..HLIJDSON 2,685,807

' FOUR-HIGH ROLLING MILL v Filed April 1.4, 1948 5 Sheets-Sheet 2 Aug. 10, 1954 E. B. HUDSON FOUR-HIGHROLLING MILL.

5 Sheets-Sheet 3 Filed April 14, 1948 -FIC':-4'

Aug. 10, 1954 E. B. HUDSON 2,535,807

FOUR-HIGH ROLLING MILL Filed April 14, 1948 s Sheets-Sheet 4 Aug. 10, 1954 E. B. HUDSON FOUR-HIGH ROLLING MILL 5 Sheets-Sheet 5 Filed April 14, 1948 w ul xi OON "v 9: Om v Mi "LY OON Patented Aug. 10, 1954 UNITED STATES PATENT OFFICE Armco Ohio Steel Corporation,

a corporation of Application April 14, 1948, Serial No. 21,033

'7 Claims. 1

This application is a continuation-in-part of my copending application Serial Number 582,645 filed March 1%, 1945, now abandoned.

My invention relates to four-high cold rolling mills, and it has for one of its principal objects the provision of a mill of that type capable of rolling very thin gauge metal in wide Widths with very substantial reductions per pass. For example, but without limitation, a mill such as that described herein is designed to roll metal to gauges between say .005 inch and .010 inch in widths 5,000 to 10,000 times the gauge.

Another object of the invention is the provision of a four-high rolling mill which can successfully roll wide metal of thin gauge between working rolls which are not only driven, but are small in diameter and are backed by relatively large backing rolls. For example, but again without limitation, I herein describe a four-high mill in which the work rolls are, say, to the diameter of the backing rolls.

The conventional, driven four-high mill has work rolls from about A to about the diameter of the backing rolls. This works out in relatively wide mills to a requirement for work rolls which are large in the absolute sense, as will be clear. Large diameter Work rolls limit the thinness of material that can be rolled with commercial reductions because of the tendency of the rolls to flatten in contact with the work due to the extremely high separating forces, assuming the mill otherwise to be strong and rigid. Thus it is generally true in wide commercial mills that material may be rolled quite well to a gauge of .020 inch with work rolls 19 inches in diameter; but if it be attempted to carry the gauge down to .010 inch, the rate of reduction may become so slow as to be uncommercial.

This indicates the need for the use of work rolls which are small in the absolute sense; but the provision of such small work rolls in a driven mill involves a number of problems. In the conventional four-high driven mill, the limit of work roll size has already been reached, since it is not possible to reduce work roll diameter without at the same time reducing the work roll neck capacity for power input into the mill. The work rolls have to be held in the mill by the bearings on the mill necks, and not only must be stiff enough in themselves to prevent deflection in the r plane of the work piece, but must have a sunlciently larger diameter than their necks to permit the use of adequate neck bearings. Yet the necks must be sufiiciently large to hold the work rolls in place and to withstand the driving torque 2 applied to them. A further reduction of the power transmission capacity of the work roll necks would render the conventional four-high mill ineffective as a rolling machine.

To obviate these difiiculties cluster mills have been suggested. In the simplest form the cluster mill has two back-up rolls for each work roll, Jaking a total of six rolls. In such a mill the work roll necks can usually be made nearly as large in diameter as the work roll barrel, whereas in the conventional four-high mill the work roll neck can have only about 55% to the diameter of the barrel. Hence in the cluster mill the barrel of the work roll can be brought down substantially to the necessary neck diameter while maintaining the same capacity for power transmission. The disadvantages even of the simplest type of cluster mill include the requirement for two additional backing rolls and four additional backing roll bearings, together with a weaker mill housing because of the larger mill window.

More elaborate types of cluster mills have been suggested, and also mills in which the ultimate roll-separating forces are applied against transverse beams through intermediate rolls and caster-like bearing members. In such structures it has been possible to get down to very small working rolls, in some instances so small that the driving torque must be applied to intermediate rolls. But the problems involved are attacked in such mills by elaborating and multiplying the parts, the requirements for careful machining and hence the cost of the structures, whereas it is the object of this invention to solve the problems with adherence to the four-high simplicity of construction, and hence low cost.

In addition to those set forth above, other objects of this invention include the provision of a four-high mill in which the work rolls, while driven, have no bearing necks, yet are supported throughout their length in a lateral direction between the backing rolls within a tolerance of .003 to .005 inch.

Another object of the invention is to provide a work roll which is driven directly from a motor armature shaft, without spindles or coupling boxes, but with all end-thrust loads carried directly to the work roll motor frame.

Another object of the invention is the application of power to all four rolls of a four-high mill in such a way that none of the power applied to the work roll necks is used to overcome backing roll bearing friction.

Still another object of the invention is to pro- ,in bearings.

3 vide a mill in which there is no limitation upon backing roll bearing capacity.

Still another object of my invention is to provide a driven four-high mill in which there is no limitation upon back-up roll diameter, and wherein back-up rolls can be provided of such strength that the problem of roll shape is minimized or eliminated.

These and other objects of my invention which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these specifications, I accomplish by that certain construction and arrangement of parts of which I shall now describe an exemplary embodiment. Reference is made to the accompanying drawings wherein:

Figure 1 is a partial end elevation of my exemplary mill, at the operating side.

Figure 2 is a partial front elevation of the mill with certain parts shown in section.

Figure 3 is a partial sectional view of the work roll motor mounting showing the arrangement of the thrust bearing and the hollow armature shaft.

Figure 4 is a partial view showing the backing rolls in section, the work rolls, and supporting means for the work rolls, one set of the supporting means being shown in section.

Figure 5 is a partial horizontal sectional view taken across one of the mill housings above the a lower work roll and showing the mounting for a work roll driving motor.

Figure 6 is an end elevation of themill from the operating side with the work roll motor turned back upon its mountings.

Figure '7 is an elevational View, omitting the mill housings but showing the arrangement of the driving motors for the four mill rolls.

Figure 8 is a power distribution diagram.

My exemplary mill has housings I of generally conventional type. The housings are provided with suitable screw-down mechanism, not detailed. I prefer to use a clutchless motorized screw-down such as that shown in my Patent No. 2,343,671. Chocks 2 for the backing rolls are mounted in the windows of the mill frame. The backing rolls are designated at 3 and are provided with suitable bearings in the checks. These bearings are heavy duty bearings preferably with excess capacity to sustain the screw-down loads,

and their size may be made appropriately large because of the relatively very great diameter of the backing roll barrels.

As in all machinery, the provision of antifriction bearings is desirable; but since in my mill power is applied to the backing rolls as well as to the work rolls, power applied to the latter does not have to overcome backing roll bearing friction. The backing rolls 3 are driven by separate motors indicated at e in Figure 7 through gear reduction mechanisms 6 and spindles T, as shown. I prefer to incorporate in the backing roll drives oil transmission couplings indicated at 5 in Figure 7, although if the back-up roll motors have drooping load characteristics, the oil couplings may be eliminated. By the use of either expedient it becomes unnecessary to hold the backing roll diameters to an exact relationship with the work roll diameters.

Work rolls of relatively very small size are indicated at 8. These rolls have no necks engaged Each is directly driven by one of the work roll motors 9, such a motor being located on each side of the mill.

Each work roll motor has a hollow armature shaft 20 provided with thrust bearings 2| in the motor housing 9a. An extension on the work roll 3 extends through the hollow armature shaft to engage a coupling 22. There are no spindles or coupling boxes, as illustrated in Figure 3. The hollow armature shaft 2% is so constructed that not only the extension 80. of the work roll 8, out also the work roll 8 itself may pass through said shaft. In changing the work rolls the work roll is simply inserted into or withdrawn through the hollow armature shaft.

The work roll motors are each mounted upon a gate-like bracket 23 pivoted upon a shaft 24. mounted in ears 25 on the mill housing. The gate-like brackets are provided with means for vertical adjustment to compensate for variations in the positions of the work rolls. One such provision may be a nut or the like 25 threaded upon the shaft 24. Each gate bracket is likewise provided with a lock or fastening means 2i to hold it against the opposite portion of the mill housing. The lock is releasable to permit the motors to be swung outwardly to give access to the backing rolls as indicated in Figure 6. Each lock is also provided with vertical adjustment means 28.

The lower chocks 2 are provided with hydraulic balance cylinders 29 shown in Figure 5 to hold up the upper chocks against the mill screws.

As shown in Figure 4, the work rolls are small in relation to the backing rolls. To give the working rolls lateral support, I provide on each side of the mill a pair of housings ID mounted upon heavy shafts I 5. These housings are spaced sufficiently to permit the work piece to enter and leave the mill between them. They are characterized by long tapering noses approaching the work rolls and providing a. construction which is very stiif transversely of the mill. The housings N3 of each pair are rigidly mounted in spaced condition with respect to each other by bolts or the like 38 so disposed as to lie beyond the path of work piece travel.

The bolts 39 have a sliding fit in the members Hi with a tight fit in the upper one of these members, and the bolts prevent any tendency for the members to rotate on the shafts i i.

Each of the housings ii! is perforated at regular intervals for the acceptance of rod members 3! which, at their outer ends, have threaded engagement in the housings and which are provided with lock nuts 32 and squared ends for longitudinal adjustment. The inner ends of the rods have a ball and socket engage 'ient with bearing members 13 shaped to conform to the work rolls. These bearing members may be made of any suitable metallic or other material and their function is to give lateral support to the work rolls. They may be individually adjusted by means already described.

The checks for the upper and lower backing rolls are also provided with hydraulic cylinders 33 (Figure 5). The ends of the shafts N form or are engaged in piston members l2 operating in these cylinders. The cylinders are connected with an hydraulic system and a valving arrangement, which are not shown but will be readily understood, and which operate to cause the pistons IE to reciprocate back and forth horizontally between the mill housings with a stroke length greater than the space between the lateral bearing members i3, and at a suitable rate, say 8 to 10 strokes per minute. Thus the lateral supporting bearings !3 for the Work rolls move along the surfaces of those rolls longitudinally, which greatly minimizes friction between the members l3 and. the work rolls. The mill is of a type designed to have the work rolls and adjacent portions of the work piece flooded with a cooling oil or water. Because of the movement of the lateral supporting members l3 they can be caused to recondition the work rolls 8 if the coolant and lubricant is provided with a mild abrasive, such as rouge, acting to remove pickup and stain from the work rolls, particularly when rolling stainless and chrome steels.

The four mill motors are preferably operated upon the so-called Ward-Leonard control system; but A. C. motors with variable frequency may be employed, if desired. The motors will, of course, be chosen as to size and capacity for the particular duties to be performed by each; and in any given mill under my invention the recise amount of power applied to the work rolls can easily be proportioned to the diameter of the work rolls and their consequent ability to withstand torque. But by employing power also to the backing rolls any power requirement may be made up, the backing rolls frictionally imparting driving power to the work rolls; and the power applied to the backing rolls overcomes any backing roll bearing friction, relieving the power applied to the work rolls from this duty. A typical power distribution chart not intended to be limiting is shown in Figure 8 where, of the total of applied horsepower, 200 horsepower is applied to each of the backing rolls through motors 4, while 50 horsepower is applied to each of the work rolls through motors 9. Of the power applied to each backing roll, 50 horsepower has been indicated to be required to overcome bearing friction, leaving a total of 400 horsepower applied by the mill motors to the job of reducing the metal in the active pass of the mill.

My mill is adapted for use with or without tension on the work piece in either the forward or rear directions or both, the work rolls being supported against lateral deflection in both horizontal directions. My mills may be used as reversin mills, if desired. Also they are adapted for use in tandem trains.

Otherwise than as specifically described, my mills may be the same as conventional four-high mills and may be fitted with the same devices and provided with the same gauges and controls. Modifications may be made in my exemplary structure without departing from the spirit of the invention. By way of a single example, the motors 9 for drivin the work rolls may be mounted, preferably in gate-like brackets of the type described, on the chocks 2, or extensions thereof so that these motors will move with the chocks during extensive screw-down adjustments, or means may be provided to mount the gate-like brackets for the work roll motors 9 upon the side frame of the mill but to cause them to move automatically up and down in accordance with screw-down adjustments.

Having described my invention in an exemplary embodiment, what I claim as new and desire to secure by Letters Patent is:

1. In a four-high driven mill, housings, a pair of backing rolls journaled in bearings in said housings, a pair of work rolls having diameters substantially between A and the diameter of the backing rolls, means supported from said housings and engaging lateral operating faces of said work rolls to hold them between said backing rolls, and means for individually and simultaneously applying power to all four rolls, the means for applying power to said work rolls comprising individual electric motors to which said work rolls are directly coupled, said motors having thrust bearings acting to sustain the axial thrusts of said work rolls in both directions.

2. In a four-high driven mill, mill housings, a pair of work rolls, a backing roll for each work roll mounted in hearings in said housings, means for applying power to said backing rolls, means for applying power to said work rolls, said last mentioned means comprising electric motors having hollow armature shafts, said work rolls being directly coupled to said hollow armature shafts, the bores of said armature shaft being larger than the outside diameter of the work rolls, whereby said rolls may pass completely through said hollow armature shafts, said hollow armature shafts being equipped with thrust bearings acting to sustain the axial thrust of said work rolls in both directions.

3. In a four-high driven mill, housings, a pair of backing rolls journaled in bearings in said housings, a pair of work rolls having diameters substantially between and the diameter of the backing rolls, means supported from said housings and engaging lateral operating faces of said work rolls to hold them between said backing rolls, and means for individually and simultaneously applying power to all four rolls, said means for engaging the lateral faces of the work rolls comprising frames and bearing members adjustable in said frames, the bearings for said backing rolls being mounted in chocks slidable in said housings, said chocks having fluid cylinders and pistons therein, said frames being mounted by and connected with said pistons whereby said frames can be caused to oscillate in a direction longitudinally of said work rolls.

4. In a four-high rolling mill having two large backing rolls having necks journaled in bearings in the housing of said mill and two small work rolls, individual electric motors connected to each of said four rolls, reciprocating lateral supporting means engaging the operating faces of said work rolls to maintain said work rolls between said backing rolls, the connection between said backing roll motors and said backing rolls being of the fluid transmission type, and said work rolls being connected to said work roll motors by direct coupling to hollow armature shafts provided in said work roll motors, said shafts having internal bores larger than the outside diameters of said work rolls, said shafts also having thrust bearings acting to withstand the axial thrust of said work rolls in both directions.

5. In a four-high driven mill having mill housings, a pair of work rolls having very small diameters in proportion to their length, said diameters being so small as to render the rolls unable to maintain their position in the mill against the stresses of rolling, means engaging the operating faces of said work rolls to maintain said rolls in position, a backing roll for each of said work rolls, bearings forsaid backing rolls only, separate power-applying means for each of said work rolls, and separate power-applying means for each of said backing rolls, the relation between said power-applying means being such that power is applied directly to said Work rolls within their ability to withstand torque and to said backing rolls in quantity at least suificient to overcome backing roll bearing friction, the greater power input being applied to said backing rolls so that said work rolls are frictionally driven by said backing rolls, said separate power-applying means for said work rolls comprising individual electric motors directly coupled to each of said work rolls, each of said motors having thrust bearings associated therewith to take up the endwise thrust on said work rolls.

6. In a rolling mill having work rolls and backing rolls, a shaft mounted in said mill, a hydraulic cylinder in said mill, said shaft being operatively associated with said cylinder for reciprocation thereby, a housing mounted on said shaft, said housing having a long tapering nose approaching a said work roll, a plurality of rod members adjustably fixed in said housing and extending through said nose, and a plurality of bearing members shaped to conform to a said work roll, the inner ends of said rod members engaging said bearing members respectively.

'7. In a rolling mill having a pair of work rolls and backing rolls; a pair of shafts mounted in said mill; a pair of hydraulic cylinders in said mill, said shaft being respectively operatively associated with said cylinders for reciprocation thereby; a pair of housings, one mounted on each of said shafts in rigidly spaced relation, each of said housings having a long tapering nose approaching the respective work rolls; a plurality of rod members adjustably mounted in each of said housings and extending through said noses; a plurality of bearing members for each of said Work rolls, each bearing member being shaped to conform to a said work roll; and a connection between each of said bearing members and the inner ends of a respective rod member.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,772,248 Gibbons Aug. 5, 1930 1,779,195 Steckel Oct. 21, 1930 1,813,129 White July 7, 1931 1,892,933 Coryell Jan. 3, 1933 2,165,266 Hudson et a]. July 11, 1939 2,434,979 Bergh Jan. 27, 1948

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