US 2776586 A
Description (OCR text may contain errors)
Jan. 8, 1957 $ENDZ|M|R 2,776,586
CONSTRUCTION AND CONTROL OF COLD ROLLING MILLS Filed June 10, 1948 3 Sheets-Sheet l 7'0 744 4; (80 71/1. f 18 W I] I AfvM 0/4 -Sl/PPL Y INVENTOR. 7205052 SE/VDZ/M/IT.
ATTORNEYS? Jan; 8, 1957 T. SENDZlMIR r 2,776,536
CONSTRUCTION AND CONTROL OF COLD ROLLING MILLS Filed June 10, 1948 s Sheet-Sheet 2 INVEN TOR. 73aEusz $NDZIMI$Z ATTORNEYS.
Jan. 8, 1957 T. SENDZIMIR I 2,776,586
CONSTRUCTION AND CONTROL OF GOLD ROLLING MILLS Filed June 10, 1948 5 Sheets-Sheet 3 BTW W I i Q 5; 4
Ill/III I I E6. 8. INVENTOR.
United States Patent CONSTRUCTION AND CONTROL OF COLD ROLLING MILLS Tadeusz Sendzimir, Middletown, Ohio, assignor to Armzen Company, Middletown, Ohio, a corporation of Delaware Application June 10, 1948, Serial No. 32,215
3 Claims. (Cl. so-ss My invention relates to cold rolling mills of the general type shown in my United States Letters Patent Nos. 2,169,711 and 2,187,250.
The principal objects of this invention are to provide improvements in the construction of mills of this type such that better control is had of the working operation and better control of the contour of the work piece, both objects being attained by structural changes and arrange ments of parts as will be described herein. These and other objects of the invention which will be set forth or will be apparent to one skilled in the art upon reading these specifications I accomplish by the aforesaid structural changes and modifications of which I shall now describe certain exemplary embodiments. Reference is made to the accompanying drawings wherein:
Figure 1 is a partial cross-sectional view of one type of mill arrangement showing the directions of components of force.
Figure 2 is a partial cross-sectional view of a mill arrangement employing staggered backing elements, and including a diagrammatic showing of a mechanism for mill release.
Figure 3 is a partial cross-sectional view of another mill arrangement employing staggered backing elements and incorporating a release mechanism.
Figure 4 is a partial cross-sectional view of a mill arrangement which is modified over those hereinabove referred to, and which also illustrates certain means for applying lubricant and for wiping the rolls, which means are applicable to all of the forms of mill shown herein.
Figure 5 is a diagrammatic elevational view of a work roll and an intermediate roll with a work piece shown in section, the drawing illustrating a means for preventing over-rolling at the edges of the strip.
Figure 6 is a similar view showing another roll arrangement for the same purpose.
Figure 7 is a diagrammatic view of a pair of work rolls and a pair of intermediate rolls showing another form of contour control means.
Figure 8 is an isometric view of a mill housing so shaped as to control roll deflection.
Figure 9 is an elevational view with parts in section of a driven intermediate roll, coupling means, thrust means, and a roll hold-up mechanism.
Figure 10 is a longitudinal section of a bearing and saddle assembly showing means for controlling the flow of lubricant.
Figure 11 is a longitudinal sectional view of another arrangement of backing bearings and saddles provided with a positive sealing means and means for the separate circulation of lubricant to and through these bearings.
My invention relates to rolling mills of the general type of those set forth in my patents referred to above, in which mills small diameter and relatively slender work rolls are supported by one or more sets of intermediate rolls which in turn are supported by caster elements journaled on shafts having a bearing against beams extending transversely of the mill. Such mills are especial Patented Jars. 8, 195%? 1y useful in making carefully controlled or very heavy reductions in metallic strips, by which is meant here Work pieces of indefinite length irrespective of their specific width.
In such mills the direction of pressure on the final backing casters is at an angle to the roll pressure at the work rolls, which roll pressure is usually in the vertical direction. In a mill through which the strip passes horizontally, only the vertical component of the rolling pressure is useful in the rolling operation, although the horizontal component is of necessity present, because of the angular position of the backing casters.
On a conventional four-high mill, where the backing is in the same direction as the roll pressure, for each 1000 tons of roll pressure, the main bearings have to withstand only 1000 tons. As distinguished from this, in a cluster mill where each work roll is backed in a non-vertical direction by two backing rolls, each one of the backing rolls will have to withstand usually from 60 to 70 percent of the total roll pressure. Thus the two backing rolls on either side of the work piece will have to withstand a total pressure which is about to percent of the vertical rolling pressure. It will be clear that more bearing capacity has to be built into such mills.
This makes it clear why in cluster mills it is advantageous so to place the backing elements that their corresponding pressures do not lie at angles too close to the horizontal, and also why, when more than two backing elements are employed for each Work roll it is advantageous to have the bearing pressures distributed as evenly as possible between all of the backing elements to insure that their bearings have a long life.
In mills of my type, however, as set forth in the copending application of myself and John E. Eckert, Serial No. 485,750 and now Patent No. 2,479,974, granted August 23, 1949, filed May 5, 1943 and entitled The Design and Construction of Rolling Mills, after long experimentation with various roll arrangements, an advantage has been found in doing exactly the opposite, i. e. disposing outer ones of the caster elements so that their lines of pressure come as close to the horizontal as possible, taking into account the accessibility of the mill. In such an arrangement the most inclined caster elements will take the biggest share of the load and those caster elements having lines of pressure closer to the vertical will take a smaller part of the load.
In Figure 1, l have illustrated in section a portion of a mill comprising a pair of work rolls 1, a set of first intermediate rolls 2, a second set of intermediate rolls of which the three upper ones, marked 3, 3A and 3B are shown, and a series of upper casters marked 7, 8, 9 and 10. The primary rolling pressure is indicated by an arrow marked P. The backing casters 7 and 10 sus- 'tain the largest components A and D of the roll pressure P whereas the backing casters 8 and 9 sustain the smallest components l3 and C. Components A and D are closer to the horizontal, whereas B and C lie more nearly in the vertical direction and are closer to the direction of the primary rolling pressure P. Those backing casters which sustain the smaller load may be made of lesser diameter as illustrated in Figure 4 of this application, or they may be staggered as illustrated in Figure 2 hereof, in ways commensurate with the loads they have to bear.
It has been found in applying these principles, which appear paradoxical, that they permit a geometrical arrangement of the mill in which a great reduction in the diameter of the Work rolls for a given number and diameter of ultimate backing casters becomes possible. In this Way a more accurate mill is provided, and also one in which the work roll pressure is smaller and therefore the total pressure on the backing caster elements 3 becomes less in spite of their unfavorable angular position.
The relatively high share of the rolling pressure which is sustained by those backing casters most inclined from the vertical means that the intermediate rolls which are in working contact with them also carry a greater share of the load than the ccn er intermediate roll of the same group, or other intermediate rolls of the same group disposed in directions closer to the vertical. But at the same time the outer intermediate rolls in the most inclined positions can be made of very substantially greater diameter than other intermediate rolls; and another advantage of the arrangement is that if the most inclined outer intermediate rolls are employed as driving spindles, they are capable of transmitting heavier torques to the mill.
As set forth in the copending application Serial No. 485,750 now Patent #2,479,974 referred to above, an advantage is obtained by applying the driving torque to intermediate rolls, whether they be the first intermediate rolls 2 in Figure 1 or the outer intermediates 3, 3A and 3B, rather than directly to the Work rolls as was previously done, since the very slender work rolls in these mills have low torque transmitting capacity. Thus, there is a net gain of several times the maximum torque that can conveniently be transmitted, because the number of rolls which carry the torque can be at least doubled, and their diameter will be at least about 2 /2 times larger than the diameter of the work rolls.
In mills having more than one group of intermediate rolls, an arrangement involving unequal distributor-l of loads to the different rolls, makes it possible to apply the drive to the four outside rolls in the group of six largest intermediate rolls, such as the group 3, 3A and 3B of Figure l. The rolls 3A and 313 have the largest angularity to the rolling pressure P; and it is not necessary to complicate the drive by applying torque to all six or more of the outside intermediate rolls. Since the rolls of greater angularity carry the larger load, they therefore can alone transmit a sufficient torque by friction to the next series of inermediate rolls such as the rolls 2 in Figure 1, and from there the working rolls 1. In such an arrangement marked advantage is secured not only from the fact that the driving spindles may be relatively large, but also from the fact that, because of the large distance between the driven intermediate rolls, a pinion stand may be used which has a relatively low tooth pressure.
in using mills of this type, it has been found in operation that minute deflections tend to occur in the roll assembly and housings, especially when heavy reductions are made and the operating loads are high. These deflections permit Work rolls 1 to deflect more in their central portions than near the edges of the strip. This causes the stretching or elongation of the metal strip being rolled to be uneven unless compensation is made for the deflections. The unevenness of strip elongation usually manifests itself in wavy edges of the strip caused by over rolling when the slender work rolls bend over the edges of the strip.
To overcome this difliculty, the present invention includes means to insure that the elongation of the strip being rolled will be uniform across its width. One aspect of this improvement lies in contouring the intermediate mill rolls, such as the rolls 2 in Figures 5, 6 and 7. This contouring consists of a taper relief which is shown greatly exaggerated at 23 in Figures and 6. This taper relief may be formed on or near the ends of the work rolls or any series of intermediate rolls at the positions of the edges of the strip S which is being rolled. It is preferred to form it on the ends of the first series of intermediate rolls by reason of their flexibility. The taper relief is slight, but suflicient to prevent the work rolls from bending at their ends over the edges of the strip so as to prevent edge over-rolling. Thus the flat portion of the contoured intermediate rolls 2 is usually narrower than the strip being rolled, so that the taper rclief starts slightly inside the strip edge on the rolls as illustrated in Figures 5, 6 and 7. It has also been found beneficial to employ crown on one or more of the rolls, and particularly on the work rolls when used in combination with taper-relieved intermediate rolls. This minimizes the amount of taper necessary. Crown on a work roll is illustrated in an exaggerated form in Figure 6, where the Work roll 1A is shown as having a crown. In actual practice the amount of crown will be restricted to several thousandths of an inch.
It is not necessary to relieve all rolls of any given set. The taper relief, which usually is also no more than several thousandths of an inch, may be ground on one or both ends of one or more rolls, or on opposite ends of different rolls in a set. When one or more rolls are tapered on or near both ends, as in Figures 5 and 6, and remain in fixed positions in the mill, the relieving action at the strip edges will be good only over a small range of strip widths rolled in the mill. If, however, the relieved rolls can be made axially adjustable, they may then be provided with means for axially shifting their positions and a wide range of strip widths can be rolled on them. If means for axially shifting the roll positions is provided, the rolls so shifted may still be tapered on or near both ends if desired, but it becomes necessary only to taper alternate rolls on opposite ends, opposite rolls on opposite ends, or rolls of different sets on opposite ends. The means for axial adjustment may be applied to work rolls or to any set of intermediate rolls having the taper contours described above.
In Figure 7 there is illustrated a roll assembly comprising Work rolls 1, and intermediate rolls 2A and 2B. The roll 2A has a taper relief at or adjacent as at 23A while the intermediate roll 2B has a taper relief at or adjacent its opposite end as at 238. The intermediate roll 2A is shown as provided with a thrust bearing 27' and connected thereby to a non-rotative link 28 which, in turn, is connected to a rack 29. A gear wheel or pinion 30 has teeth meshing with the rack and with a worm 31 on the drive shaft of an electric motor 32 or other prime mover for shifting the axial position of the roll. The intermediate roll 23 will be connected through a thrust bearing 2713 to a similar mechanical arrangement for shifting its axial position, preferably equally and in the opposite direction. By these means the taper reliefs 23A and 23B on or near the opposite ends of thc illustrated intermediate rolls may be made substantially to coincide with the edge portions of a wide range of strips being rolled in the mill. The axial adjustment which has been described can also be accomplished satisfactorily by hydraulic and other means.
The regular deflections under load in the mill housing itself are greatest at a point corresponding to the center of the strip being rolled, since this point is farthest distant from the mill columns. One of the objects of the invention is to counteract this, and provide means which insure that the mill will roll a flat strip irrespective of load. To accomplish this, a special housing structure is provided which includes weakened side portions which will have a greater ability to deflect at areas corresponding to the side edges of the strip, and so introduce an artificial, supplementary deflection which will make the total or resultant deflection at the work rolls uniform over the entire width of the strip.
In Figure 8 there is illustrated the housing for one of my mills. The strip being rolled enters and leaves the mill through windows W, and these windows together with the central space of the housing in which the work rolls and other operating elements are mounted, divide the housing into columns 40 and beams 40A, as will readily be understood. The compensation described above may be attained by suitably tapering the edge portions of the beams 40A as illustrated at 39 and 39A equidistant from the columns 40. When this is done,
thewassemblies of backing casters 7 andv in Figure 1, when mounted in the mill housing, will deflect most at the center of the strip, whereas the assemblies of backing casters 8 and 9 of Figure 1 will deflect most near the edges of the strip.
: Since one established contour on the rolls themselves in a given mill, such as has-been described in connection with Figures 5, 6 and 7, may begood only for a certain roll pressure and a certain given widthand reduction of the metal, the benefits of a specially shaped housing acting as above described have herein been combined with contour rolls and means for their axial adjustment to permit greater versatility for rolling strips of a wide range of widths and hardnesses and for taking various reductions of any desired percentages. In mills of this type hitherto described, as in the copending application Serial No. 485,750 and now Patent No.1 2,479 ,,974 referred to above, the backing casters have been journaled on shafts with eccentric portions, which in turn are mounted in holding members or saddles lying against the mill housing beams. According to the present invention a more effective construction has been produced by providing plain cylindrical shafts for the casters and employing eccentric discs keyed to. them. In this way the diameter of the eccentric element becomes greater, providing more room for the installation of roller bearings which do away with static friction when rotating the shafts under load in order to set the roll pass screw-down. Another advantage is that the saddles themselves do not need to be split; and the backing caster shafts with their eccentric discs and saddles and the casters themselves, form subassernblies that may be carried as spare parts for exchange in case of breakdowns.
Referring to Figure l, the shafts 5 are provided with roller bearings, such as 11, having rollers engaging between eccentric discs 6 keyedto said shafts 5 by keys 64, and saddle elements 4, which engage in appropriate grooves or recesses in the mill housing beams, 40A.
A further advantage is attained by providing a common locking device for each saddle and caster assembly, which device may be operated from one end of the mill. This may comprise a fixed bar 36 (Figure l) affixed to the mill housing, and a slidable, tapered bar 12 having a toothed end sectionwhichis motivated by a worm 13. Longitudinal movement of, the movable tapered bar 12 will force each saddle against a fixed stop 36A on the housing beam.
It will be clear from the foregoing description that if the discs 6, which are keyed to the shafts 5 and 6 are mounted by means of the roller bearings in the saddles, are eccentric in form, a rotation of the shafts 5 will effect the screw-down of the mill. In such a mill it is possible that while rolling, an unusually high load may accidentally be applied to the mill bearings, and might be beyond their capacity. To eliminate the chance of failure and to protect the casters as well as the rolls, a yieldable feature is provided in the arrangement of backing elements or casters assembly, whichghowever, will hold the backing elements rigidly in position up to a predetermined roll pressure.
This may be accomplished by splitting one or more of the bearing shafts 5 into two parts 5A and 5B as illustrated in Figure 2 along a plane lying substantially normalto the"rolling pressure, leaving within the shaft a flat concavity 21 deep enough to provide for an adequate, safe collapsing distance. Fluid pressure is applied to the cavity 21 urging the two shaft sections 5A and 5B in Figure 2 apart and pressing themagainst the bores of the casters 7 and eccentric rings 6. Elastic seals marked 22 prevent oil leakage, but are of resilient nature so as to collapse when the rolling pressure forces the shaft sections SAand 5B together. Whenever the predetermined pressure setting of an overload valvewhich isincorporated in the system is exceeded, owing to a sudden surge of load on the casters, the overload valve of the pressure system will give way, permitting the two parts of the shaft to approach each other and thus relieve the casters and all pressure bearing elements of the mill.
While a yieldable protection feature has been set forth as embodied in the bearing shaft 5, it may also be employed on any other bearing element or combination of them within the scope of this invention. Even parts of the mill housing can in a similar fashion be made to yield under excess load to protect the loaded mill parts from damage, Within the scope of these disclosures.
Yet another type of relief mechanism, as heretofore described in application Serial No. 485,750, now Patent #2,479,974, may be employed as shown in Figure 3. Here the work rolls 1 rest upon two intermediate rolls 2 which, in turn, rest upon three sets of staggered casters 41, 42, and 43. These casters or bearings are rotatably mounted on the shafts 5 which in this mill are mounted in supports on a single saddle or cradle 44. The cradle has a cylindrical outer surface which is eccentric to the axis of the work roll 1. It is rotatably journaled in a semi-cylindrical recess in the beam of the mill housing; and it may be given an anti-frictional mounting by means of a series of rollers 46. At one side of the beam there is provided a fixed stop 47, while at the other side a lever or series of levers 48 are pivoted on bearings 49 afi'ixed to the mill beam. One end of the lever or levers engages a slot formed in the cradle 44, while at the other end there is provided some constant force means such as a compression spring 50 engaged between the lever and a socket 51 on the beam of the housing. The effect of the spring 549 is to force the cradle 44 in a clockwise direction against the stop 47; and the force exerted by the springs is adjusted to counteract the expected or desired rolling pressures. Up to a desired predetermined rolling pressure for which the springs 50 are adjusted, the mill will be rigid, because the cradle 44 will be held against the fixed stop 47. But when the working rolls encounter an obstruction and the roll separating force is suddenly increased beyond that predetermined value, the cradle 44 will rock in a counterclockwise direction against the force exerted by the springs. This is due to the eccentricity of the cradle surface relative to the work'rolls, described above.
The same mechanism may be used for screw-down purposes by substituting an adjustable stop in the place of the fixed stop 47 so that the rolling position of the cradle 44 can be changed to vary the operating position of the work rolls. It should be understood that other means than the compression springs 50 may be used for a constant force means, such as fluid pressure cylinders and the like.
A further advantage of the roll arrangement shown in Figures 1 and 2 lies in the simplicity of the provision of the screw-down control. Since the operating positions of the work rolls will be controlled by changing the anguluar position of one or more of the backing shafts 5 and the eccentric discs keyed thereto, and since two symmetrically disposed shafts may be selected for screwdown purposes, and are provided with bearings free of static friction on the saddles, it is possible to provide gear segments 15 in Figures 1 and 2 on the ends of these two shafts, and engage the teeth of these segments with a double' faced rack (14 in these figures). The rack may be attached to an hydraulic piston rod 16 connected to the piston 17 of a cylinder 19. A raising or lowering of the piston will control the angular position of both shafts and hence vary the screw-down of the mill. On wide mills it is advantageous to provide gear segments, racks and pistons at both ends of the shaft, thereby avoiding any inaccuracy which would result from a twisting of the shafts due to torque exerted by a piston at one end thereof.
To operate such a screw-down, use may be made of a known hydraulic control system comprising a follow valve indicated at 18 in Figure 2, connected to the cylinder 19 by tubes 79 and 8d at opposite ends of the cylinder 19. The adjustable element 78 of the follow valve may be operated directly by a remote control systern by the mill operator. The other element of the valve is mechanically connected by a linkage 77 to the piston rod 16 so that it stops the flow of hydraulic fluid as soon as a predetermined screw-down position has been reached. The chief advantage of this system is that when, through leakage or other causes, the position of the piston has changed, the valve 18 will automatically add fluid to restore the position set by the operator, within narrow limits. A pressure relief valve 20 may also be incorporated in this system and, assuming lack of friction in the caster and saddle bearings will provide for relief in the event of a sudden great excess in the rolling pressure. ln mills having a cluster arrangement of the rolls, as herein described, each roll is nested or supported by two backing rolls or bearing assemblies parallel to each other. In this way, there can be no cocking of the rolls, i. e. such a change in position as would throw them out of parallelism. According to this invention, axial freedom of all non-shiftable roll ends is limited by bearing plates 25 in Figure 9, which may be stationary or rotatable, and may be alfixed to the doors 76 of the mill housing. if stationary abutment plates 25 are used, it is preferable to atfix a rotatable bearing 24 of thrust sustaining character to the roll end. This bearing is mounted in a case 37 which is provided with a fiat surface abutting against the thrust plate. In this way doors 76 at the ends of the mill housing will sustain axial thrusts applied to the rolls during operation, while permitting these rolls to adjust their radial positions. Since it is preferred to support all except the work rolls in the upper half of the mill so that they will not gravitate against the bottom work roll when the screw-down is up, springs 26 in Figure 9, air operated piston rods, or other convenient sustaining and lifting means are, according to this invention, attached to the case elements 37 which hold the thrust bearings 24 of these rolls.
The driven ends of driven rolls such as the roll 3 of Figure 9 are simply engaged by sliding them into the coupling ends of spindles 33. They butt against spherical thrust elements 34 in these spindles; and the spindles transmit the axial thrust to corresponding pinion stand bearings (not shown). Rolls mounted in this manner are free to be removed from the mill upon the opening of the mill doors 76.
The improvements in mill construction and operation herein outlined depend for their precision on the maintenance of an even temperature of the mill elements including all rolls and backing bearings, in spite of the heat generated at the line of contact between the strip and the work rolls, between the individual rolls, between the intermediate rolls and the casters, and within the bearings of the casters. High production mills may consume several thousand horsepower, a part of which goes into sliding and rolling friction, Any local heating will throw the mill out of line and produce a wavy and inaccurate strip almost immediately. Further, once a local heating has occurred, lubrication is upset, and the parts expand locally creating higher local pressures, so that the situation becomes staggeringly worse within a very short time. While a general or uniform change of the mill temperature over the whole width of the strip is of less consequence, it still presents a problem of mill adjustment' Any changes however which occur in temperature across the width of the strip make it impossible to produce good metal strip.
It has been found that the temperature can accurately be controlled by the use in certain ways of controlled coolant which may be and preferably is at the same time a lubricant. Certain features of lubricant control have been disclosed in the copending application of myself and John E. Eckert, Serial No. 477,087, filed February 25, 1943 now Patent No. 2,566,679 and entitled Rolling Mills and Lubrication Methods and Means Therefor. As set forth in that application one feature of successful lubrication is accomplished by causing even quantities of lubricant to escape through control clearances at the sides of the outer races of the caster bearings. As shown in Figure 10, lubricant may be delivered through bores 96 in the shafts 5 and in turn to the bearings through holes 81 in the shafts and corresponding holes 82 in the inner races 65 of caster bearings or the eccentric discs 6 which have hereinabove been described. The lubricant may otherwise be supplied to the bearings, as through passageways in the mill housing means 40A to and through passageways in the saddles, thence to the s. afts and to the caster bearings; but in any event the lubricant will be a coolant and will be supplied undet sufiicicnt pressure to insure copious How to carry away the heat. in Figure 10 clearances 54 are provided between the saddles and the outer bearing races 8, and in case two bearings are mounted between each two saddles, there are also clearances 54A between their outer races. In certain cases it is preferred to provide wider clearances and then fill them with loose rings 38 preferably made of or faced with plastic compounds, because they may be easily changed to a bigger or smaller clearance as desired.
As distinguished from types of mills in which a circulating oil bath was maintained in the hollow mill interior, being introduced at one side and withdrawn at the other, the direct introduction of lubricant to the bearings has an advantage in that the outgoing oil prevents entry of impurities, especially metal chips, into the bearings.
Moreover, as also set forth in the copending application, Serial No. 477,087, new Patent No. 2,566,679, in these improved mills the lubricant enters at or near the caster bearings, and flows therefrom to the hollow interior of the mill, flowing toward the work piece from both sides, and is withdrawn from the mill at a level at or near the level of the work piece or strip being rolled. The entire hollow interior of the mill may be kept filled with a flowing body of the lubricant.
In the present instance, while it is preferred to maintain an oil bath in the lower half of the mill, it is sufficient in the upper half of the mill to let the escaping lubricant cascade over the rolls of the upper half, thus lubricating and cooling them. This simplifies sealing of the mill interior around the drive spindles. By letting the bulk of the lubricant out of the mill at the apertures provided for the strip, i. e. at the windows W in Figure 8, the strip is effectively cooled, and most of the dirt carried by the strip is kept out of the mill. A practical improvement consists in providing bores 62 in Figures 2 and 4 at the lowermost portion of the mill housing, i. e. through the lower beam 48, to let out some of the lubricant, since this prevents dirt from accumulating there. Thus the mill becomes a completely self-cleaning machine, providing the oil is properly filtered. Outside filtering and cooling means for the lubricant are provided but are not shown in the drawings hereof.
The openings 62 will be located in such a way that oil may be drained from them without reentering the caster bearings; and the quantity of oil so drained may be controlled so as to maintain any desired oil level in the lower part of the mill, and/or to drain from the lower part of the mill oil introduced into the caster bearings therein, and oil entering the lower half of the mill from the upper half around the edges of the strip at the ends of the rolls.
Where either or both halves of the mill are kept filled with circulating baths of lubricant, a preferable wayof letting the lubricant out of the mill is by providing a flexible strip-metal scraper 55 in Figure 4 contacting the work roll 1 lengthwise close to the pass line. While only one such scraper has been shown, it will be clear a'r/ sss how others could be provided at the opposite side of the lower work roll and at both sides of the upper work roll. This scraper or scrapers are held in holders 56; and these holders are preferably provided with spaced slots or apertures 56A above the scrapers, through which apertures the lubricant may escape from the mill interior, flushing the side of the scraper orscrapers which faces the strip being rolled,
Whether or not scrapers are employed, a further greater advantage may be secured by flushing the rolls and work piece with high pressure lubricant supplied through a separate outside source through jet elements 57 in Figure 4 which are held in holders 66 which may be the same as the holders for the scrapers. If scrapers are employed, these jets of lubricant will flush the outsides of the scrapers also. The use of high pressure lubricant separately introduced in this position provides efiective cooling of the work rolls themselves by fluid jets directed into the bite of the rolls and impinging against that part of the roll surface which is just leaving or coming into contact with the strip. It is known that high heat is generated'in the roll bite, and the work roll picks it up. The use of high pressure lubricant jets makes it possible to evacuate this heat before it has had a chance to penetrate more deeply toward the interior of the roll body. While Figure 4 illustrates jets 57 at but one side of the mill, it will be obvious without illustration that they can be provided at both sides of the mill. The lubricant introduced by means of such jets will for the most part leave the mill through the windows W.
It is preferred to make the jets have a horizontal direction which is not normal but slightly oblique to the roll axis, the jets situated to the left of the center of the mill inclining toward the left, and those situated to the right of the center inclining toward the right, and if necessary increasing the inclination of the jets as they approach the ends of the rolls. This gives to the escaping lubricant a certain acceleration away from the center of the mill, thus taking care of drainage of lubricant from the narrow space and insuring increased turbulence. When sufliciently high oil pressures are used, such as several hundred pounds per square inch, better flushing and cooling results are obtained if the jets are used alone, i. e. without the scrapers 55.
Also in Figure 4 there is illustrated a seal 60 held in a holder 66 for closing the space between the walls and the throat of the housing. This seal is a resilient strip-like member contacting the periphery of an intermediate roll such as the roll 3A. If this seal is located on the side where the strip leaves the mill, it will be appreciated that the direction of motion is such that the seal wipes a dry surface of the roll 3A, which makes its action very eflicient. Such seals may be located at both sides of the mill and in both halves of the mill, for example, contacting all rolls 3A and 38.
Such seals may be caused to perform several functions. In some instances in rolling it is desirable to produce a perfectly dry strip, i. e. to have a dry strip exit fro-m the work rolls without the use of wiping means contacting the strip directly.
Where seals 60 are used against the rolls 3A and 3B, it will be noted that they have the effect of sealing lubricant into the hollow mill interior on the side of the strip at which they are used. If this is done at the lower side of the mill, the lubricant introduced through the caster bearings may be exhausted through the openings 62. If it is done at the upper side of the mill, the lubricant introduced at the caster bearings may be otherwise exhausted as through lateral openings at both sides of the mill, or through longitudinal passageways in the holders 66 themselves, which passageways have lateral branches into the mill distributed in various ways across the mill width.
The use of seals 60 does not preclude the flushing of No. 477,087, now Patent 2,566,679.
the strip with high pressure sprays where this is desired. For example, the nozzles 57 may be used along with the seals 60, and in this fashion the coolant used against the strip may largely be kept separated from the oil which is employed as a coolant and lubricant in the mill proper. It will be noted also that when scrapers 55 are not used but seals 60 are, and where these seals have a bearing against two of the outermost series of intermediate rolls, the coolant and lubricant introduced through the nozzles 57 can contact not only the strip and surfaces of the work rolls 1 but also surfaces of the first intermediate rolls 2 and the other intermediate rolls such as the series 3, 3A and 3B. Very efiicient cooling can be had in this way by volumes of cooling fluid essentially separate from the fluid used to lubricate the mill parts. In the case of some metals it is vital for the rolling proces that the strip be effectively cooled after each pass, and this is readily accomplished by providing other similar sprays upon the stripboth entering and leaving the mill, preferably within the throats or windows 'of the housing but, if required, also outside of it.
Excepting in the case of the dry strip mentioned above, the strip as it leaves the mill will of course be covered with lubricant, and this in the past has caused some difliculty together with loss of lubricant, until it was found that the lubricant can effectively be wiped from the strip by applying against it a flexible hose 58 in Figure 4 supported by a metal bar extending across the window W so as to insure uniform pressure of the hose against the strip. A synthetic rubber hose with external flanging such as is used in gas welding gives satisfactory results. A metal rod 59 is preferably inserted within the hose to prevent it from collapsing.
In instances where it is desired to employ a lubricant for the caster bearings which is separate from the lubricant or coolant used elsewhere in the mill or upon the strip, the construction shown in Figure 11 may be adopted, as set forth in the said copending application, Serial This consists in using bearings for the caster as at 7, having positive sealing means 63 so that a separate lubricant can be circulated through them continuously for lubricating and cooling purposes. In this instance the lubricant can be introduced to the bearings through a longitudinal passageway in the shaft 50, and withdrawn through another longitudinal passageway 91, these passageways having cross connections to the bearings as shown, the flow of oil being indicated in Figure 11 by arrows. A passageway maybe formed in the mill housing means 40A to supply lubricant around the casters but not to the bearings thereof, this latter lubricant being used to cool the interior of the mill and the other elements contained therein such as the intermediate rolls and the working rolls.
It is also possible to use in these mills suitably sealed bearings with grease packing.
In the ways set forth separate roll lubricant and coolant can be used, which permits the use of a wide range of substances which might not otherwise be desirable for bearing lubrication.
Modifications may be made in my invention without departing from the spirit of it. Having thus described my invention in certain exemplary embodiments, what I claim as new and desire to secure by Letters Patent is:
1. In a cold rolling mill having small diameter work rolls, beams extending parallel to the axis of said rolls, said rolls being backed by intermediate rolls and casters which in turn are backed against said beams so as to give to said Work rolls support throughout their operating length, the combination of a Work roll having a slight crown and a cylindrical intermediate roll having a taper relief, the said taper starting inwardly of the strip edge and extending outwardly beyond said strip edge.
2. The structure claimed in claim 1 in which said inter- 11 mediate roll is so taper relieved at both ends, the nonrelieved central portion of said roll being shorter than the width of the strip being rolled.
3. In a cold rolling mill having small diameter work rolls, end housing members including spaced upright columns, and beams extending across the mill from one housing to the other parallel to the axes of said rolls, end portions of said beams forming portions of said end housing, said Work rolls being backed by intermediate rolls, and said intermediate rolls being supported by casters which, in turn, are backed at spaced intervals against said beams so as to give said work rolls support throughout their operating length, said beams being tapered adjacent their ends so as to permit a greater deflection adjacent said housings without disturbing the tendency toward greater deflection at the center of said mill, whereby to cause said deflections to be self-compensating irrespective of specific loads, an intermediate roll for one of said work rolls having a taper relief at one end, and an intermediate roll for the other of said Work rolls having a taper relief at its opposite end, and means for adjusting the axial position of said taper relieved intermediate rolls at the start of a rolling operation whereby the said taper relieved portions of said intermediate rolls may be brought into coincidence with edge portions of strips being rolled in the said mill, over a substantial range of differing Widths of strips.
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