US2376240A - Apparatus for cold rolling - Google Patents

Description

May 15, 1945.

J. FERM 2,376,240 APPARATUS FOR COLD ROLLING Fild Feb. 14, 1942 s Sheets-Sheet 1 iilii i- [M INVENTOR. c/OH/V Fi z-RM.

ATTOR EYE May 15, 1945.

J. F. FERM APPARATUS FOR COLD ROLLING 5 Sheets-Sheet 2 v Filed Feb. 14, 1942 5 Y ,1 l Q NM W x m 1 F5 M \m LL B \N\ .Q 1 I AM 1 5 r \m R. Rh mm M May 15, 1945. F FERN. 1,376,240

APPARATUS FOR COLD ROLLING Filed Fe b. 14, 194; 5 shetssfie t s g g j R *5 M9 R We H IHIHIII HHHH llllllll NQQ I I 5 {q fi I Ill W] H H H! II 1 it w 9 m K 'E'A M m? Q A lq Q 1% Q Q I INVENTOR. E v r JoH/vFfE/e/w.

' MAM/ ATTORNEYS May 15, 1945. J. F. FERM APPARATUS FOR COLD ROLLING Filed Feb. 14, 1942 5 Sheets-Sheet 4 08 23 03 cou h 7 23 8w 80 3 h RQO $0 Qv H NOLLO/l 0-78 1N3.) 83d a oNn ATTORNEYJ y 1945- J F. FERM v APPARATUS FOR com) ROLLING Y F iled Feb. 14, 1942 5 Sheets-Sheet s INVENTOR. JoH/v FIZ'RM.

ATTORNEYS tion per pass andat comparable rolling to those of tour-high mills employin the small 66 Poems May 15, 19.45

srrsaa'rus non com some John Elsi-m, manna, Pi, assigi or to Crucible Steel company of America, New York, N. Y., a

corporation of New Jersey I Application Febru ry 14, 1942, Serial No. 430,859 scnims'. '(c1. 80-31.1)

This invention pertains to the art of metal rolling, and niore especially to improved methods and apparatus for the cold rolling reduction of metal into thin-continuous strip form. r

The invention is particularly adapted to the .iurther reduction by cold rolling, of iron or steel strip as it comes from the hot rolling mills.-

,An object 01' the invention is to provide cold rolling reductions on two-high mills comparable to those presently obtainable only on four-high mills. A further object is toimprove the periormance of tour-high mills with respect to'reducworking rolls aforesaid of but a 'few inches in diameter.

I accomplish this novel result by flooding the strip as it enters the working rolls and also the rolls themselves with a suitable oil, such as torch oil, palm oil or the like. To this end. I equip the mill with suitable nozzles supplied fromoil pres-.

sure lines and appropriately mounted to-con-' tinuously spray a coating or the oil onto both the upper and lower surfaces of the strip as it enters the working rolls, other nozzles being provided to concurrentlypspray an oil coating onto the rolls tions per pass, rolling speeds, roll pressures, drivi118 p vger, etc., required.

There is considerableprior art teaching to the eireci; that inorder to prevent-undue hardening.

of metal .strip' in coldrolling and thereby eliminate intermediate annealing, it is necessary to employ relatively small working rolls of preferably about two to three andpnot over about six inches in diameter. Rolls of such dimensions are too small to be directly driven or to withstand the requisite rolling pressures unsup rted. They are accordingly provided with relatively large in the cold reduction of relatively narrow-metal themselves,

I flnd, as emphasized below, that by oil flooding the strip and rolls as aforesaid, the reduction per pass for a given roll pressure is vastly increased as compared to that omitting the oil floodin or, conversely, that a. given amount of reduction is obtained at a much lower roll pressure with than without the oil flooding.- Also that for a given roll pressure, an oil flooded millin accordance with my invention and employing working rolls of a foot or so in diameter, will p'rostrip, 1. e., up to about ten inches or so in width,

they are not adapted to the cold rolling of extremely wide stock, such as is required for automobile bodies and the like. The various (actors responsible for this include the extremely high tension required to propel the-wide strip through the rolls, the tendency of the small working rolls to. twist and distort, etc. Also the. working rolls 1 in all four-high mills irrespective of the width oi strip rolled or the size '01 the rolls, are subject to relatively rapid spelling and surface roughage, because they are subjected to the rolling pressuresat two diametrically opposi e. points, via. in y contact with thestrip and in contact with the There is accordingly p esent a continual tendency to squeeze the working rolls into m emp asise: progre sively along their reploying relatively large working rolls or the. order oi a foot or-soin diameter, about the same reducvide about the same reduction per as a fourinches in diameter operating in conformity with existing practices. The operating speeds, driving power, etc., are also comparable as explained below. I 1

I attribute these improvements to-the reduction in' frictional resistance between the strip and rolls due to the pressure or the interposed oil film. This apparently permits a portion oi the strip as it enters the rolls to stretch resiliently and slip .back past the rolls accumulating in slight bulges on the entry side, as would occur insubiecting a greased rubber band torolling pressure between greased rolls. Itthis theory is correct, as experimental results support, the confined area or the strip which is subjected to theactual cold reduction is considerably less than the total area. of contact between the strip and rolls. The requisite roll pressure for a reduction per pass is thus reduced, as compared to omitting the oil flooding.

In the latter case, the entire contact area is in frictional engagement with the rolls. -The area 01' coldreduction is accordingly coextensive with thecontact area so that a much greaterroll pressure is required not only to elect reduction but 5 also to overcome the frictional drag of the strip against the mils. As againstthis, with'the oil flooding, the area or actual cold reduction, even withthe relatively large rolls of a root or so in iniii emplcyins snrail .rolls as aforesaid.

high mill employing small working rolls of a few diameter. becomes-comparable tothat or a tour- Therefore, the requisite rolling pressures and the reductions per pass become comparable in the two instances, and comparable total reductions may be eifected without intermediate annealing. Likewise the speeds of rolling are comparable.

The invention makes possible rapid cold reduction of the strip in either two-.high or four-high mills employing relatively large working rolls of the order of 12 to 24 inches in diameter or greater, i. e. up to about 30 inches for rolling extreme strip widths of 40 to 60 inches. Such rolls are sufliciently large to be directly driven, so that the strip may be fed wholly or partially by driving power applied to the working rolls. This roll drive may be supplemented or wholly supplanted.

by a tension feed exerted on the strip, as by equipping the mill with a power-driven forward reel. The rolls are preferably mounted in antifriction bearings, such as roller bearings, oil pressure lubricated or Morgoil type bearings, etc., particularly where a tension feed is employed.

Back tension as well as forward may also be roller or equivalent antifriction' bearings, such as Morgoil bearings. The working rolls are power-driven as is also the forward reel, dynamic or hydraulic brakingbeing applied to the unwind reel for exerting back tension on the strip. The mill is suitably equipped with oil spray nozzles for oil flooding the rolls and stripon the entry side, in both directions of strip feed. Another preferred embodiment is a similar construction omitting the roll drive, and hence driven exclusive by tension exerted on the strip by the forward reel. It has been my observation that the use of large working rolls in constructions according to my invention actually facilitates the rapid cold reduction of the metal, since the reduction is more gradual and the tendency of the strip to crack along the edges is reduced as compared to the small work rolls.

For oil flooding the rolls and strip, it is preferable to use a relatively light oil of high surface tension, capable of withstanding the rolling pressures encountered and which will not squeeze out between the rolls and strip, but will assure an interposed film of the oil during the cold reduction. Torch oil, which is a very light mineral oil has been found suitable; also palm oil. The thinner the oil the better it functions, provided it has the requisite viscosity and body to withstand the rolling pressure, because this enhances the cbolant properties and facilitates penetrationby the oil of the molecular interstices.

a reversing, pull type of two-high cold rolling mill as equipped with oil-flooding apparatus. and

adapted for carrying out the present invention. Fig. 3 is an enlarged sectional view taken I through the two rolls of the type of mill for example of Figs. 1 and 2, and illustrating in further detail, the oil-flooding arrangements;

Fig. 4 is a vertical sectional view taken substantially along the line 44 of Fig. 1;

Fig. 7 is a perspective view illustrating a com- I bined roll drive and pull type of reversing mill to which features for carrying out the invention have been applied; and

Fig. 8 is a sectional view of the two work rolls of a driven roll type of mill as equipped with oil-flooding apparatus for carrying out the present invention. 1

Referring now to the assembly views, Figs. 1 and 2, the construction shown may be similar to that of the copending application of Richard G. Bennewitz, Ser. No. 350,789, filed August 3, 1940, now Patent No. 2,353,288, issued July 1, 1944, except with modifications providing a "2- high" mill in lieu of the i-high type of mill there disclosed. The construction here shown may comprise generally a rolling mill head 283 through which strip material as at 2|, which is to be reduced by cold rolling, may be passed either continuously in one direction, or alternately in one direction and then in the other, as it is wound or unwound from reels 22, 23. These reels may be driven by electric motors as at 26, 25 connected through clutches as at 2t, 2?, and reduction gearing of suitable known type 28, 29 to the shafts 30, 3|! carrying the reels 22, 23 respectively.

Suitable brakes 32, 33 of known construction,

for example, hydraulic brakes operating on the Alden dynamometer principle, according to which a braking action is provided by hydrostatic pressure due to the continuous flow of water, oil, etc, through a restricted orifice, whereby frictionally produced heat is carried away by the continuous flow of the liquid as the braking pressure is applied, may be connected or mounted upon the shafts 30, 3!. Thus, for example, when the motor 24 is connected through clutch 26, the strip will be pulled through the mill head from reel 23 onto reel 22. During this operation, the strip is preferably placed under a considerable tension of about one-third to one-half of the elastic limit, as a result of the pull exerted by motor 2t and the back tension applied by brake 33, thereby A heavy oil mayalso 'be,used if thinned out sufficiently with greatly facilitating the rapid reduction in thiclo ness of the strip without necessity for frequent reannealing. When the strip has been thus com: pletely passed through the mill and wound up on reel 22, the operation is reversed, motor 25 being actuated through clutch 21 to drive the strip in the opposite direction, while back tension is applied by brake 22. In this way, the thickness of the strip may be rapidly reduced to desired gauge in successive passes.

The mill head 20 includes a main frame or housing 24 mounted upon a pedestal 35. Within the frame 34, the large working rolls 88 and 31 may be mounted with bearing structure including bearing blocks 38, I8 and 38, 39' as shown in Fig. 4, and which are hereinafter described in further detail. i V

The bearing housings I8, 39' are so mounted in the frame 34 as to be slidably adjustable vertically and so as to be able to adjust the size of the pass for the strip between the rolls; Such vertical adjustment may be accomplished by the use of-cooperating pairs of wedge blocks ing 44.

As shown in Figs. 1 and 2, the strip 2| in its travel to and-from the mill head at each side tional features set forth in further detail in the above mentioned Bennewitz application.

The oil as supplied through conduit 65 to the various nozzles and shower sprays, may comprise palm oil for example, and preferably should be a light oil having high viscosity and high surface thereof may pass over water-cooled drums 45, 45.

suitably journaled at opposite ends of the pedestal 35.

As shown in Fig. 4, each end of each of the working rolls 36, 31 may be supported in an antifriction bearing of the self-aligning roller typ as at l'L'including inner bearing races as at 48 embracing the roll necks 49, and outer bearing races 50 secured in outer bearing rings the latter bearing rings being secured within the bearing housings against turning, as by pin 52.

Each end of the working rolls may also be provided with an anti-friction roller type thrust hearing as at 53 having inner and outer race rings as at 54, 55, with roller bearings as at '56 therebetween. Each of the rings 55 may engage a backing ring as at 51, the latter in turn being received in cup-like casing members 58 adapted to be engaged by adjusting screws 59 mounted in the bearing housing members. Lubrication for ratus for flooding the working rolls and the surfaces of the strip metal as it passes between the rolls, may include a conduit as at ,6! extending from a suitable source of oil as aforesaid for supplying oil under pressure. This conduit as shown may be connected to a group of spray nozzles and shower sprays located at each side of the rolls and including at each side, shower sprays as at 08, 61 directed onto the top and bottom surfaces of the strip 2|; also spray nozzles as at SI, 09 directed respectively downwardly and upwardly toward the upper and lower surfaces of the strip 2! and inwardly toward the pass" between the rolls. These nozzles may be supplemented by nozzles as at 10, H directed respectively downwardly and upwardly; and toward the rolls 81 and 3G for flooding the surface portions of these rolls just prior to engagement with the entering strip. The groupsof shower sprays and spray nozzles respectively at each side of the rolls may be similar in construction and may be connected respectively to the conduit 85 through shut-oi! valves as at l2, 13. Thus when the strip 2! for example is being passed in a direction from reel 22 to reel 23, the valve 12 maybe open andthe valve 13 closed, whereby the strip and roll surfaces are flooded at the areas where these surfaces are coming into contact. Similarly, when the strip is being passed in the reverse direction, the valve I! may be closed and the valve 13 opened. The spray nozzle apertures should be of such dimensions andso directed or distributed as to insure flooding both the upper and lower surfaces of the strip as it enters the pass. as well as the portions of the roll surfaces coming into contact therewith, with continuous coatings of lubricant when the oil supply is subjected to pressures of the above indicated magnitude.

As to features of construction not specifically referred to above, suitable known practice may be followed, or reference may be had to construccavities and spaces in and around the bearings in tension, so as to withstand the high rolling pressures and not readily squeeze out between the roll and the strip, but provide an oil film covering the areas of contact between the rolls and the strip. Ordinary ftorchoilf which is a very light mineral oil, has been found to be satisfaciory for the purpose. Ordinarily the thinner the oil, the more satisfactory also will be the results for cooling purposes, providing the oil 7 has a sufiiciently high viscosity and will withstand the high pressures. The thinner the oil, the more it will tend to penetrate the surfaces and thus act to maintain continuity of the coating thereon. The oil should preferably ,be liquid at' room temperatures. Heavier oils may be used provided considerable thinning material is employed. Owing to the reduction in friction and the consequent smaller amount of heat required to be dissipated, it will not ordinarily be found essential to use a coolant.

With the proper lubricant the rolls may be made of quite large diameter. While there are limits to the size of the rolls of a 2-high mill, since the ratio of the roll diameter to the strip width should ordinarily be in the general proportion of 3:4, it has been found possible by this invention to utilize rolls with diameters up to at lease 32 inches. I

While the reasons-for the strikingly improved. results obtainable with the invention are not known with certainty, it is my theory that the continuous coatings of oil upon the contacting portion Y of the strip. If the area X is well.

confined lubricated, metal in this portion is and can slip resiliently back beyond he rolls. as indicated at z-z, so that only the portion Y receives the vertical component of the rolls; whereas if the strip were dry; the confined portion of the metal would extend back, say, to about the distance indicated by Q and this region'would,

then receive the vertical component of the rolls, producing thereby a greater area of rolling contact, and requiring greater increased rolling pres sure and driving power to effect a given amount of cold reduction.

Fig. .6 strikingly illustrates the results obtainable with the invention in terms of percent reduction, as contrasted with the results according to prior practice, with the same identical 2-high mill in each case, rolling the same identical type of strip metal. 'I 'hus according to the prior practice, without oilcoatings on the sures had only a slight effect on the percentage.

reduction, whereas with the same strip and with the oil coatings applied in the manner above described, the percentage reductions with this same range of pressures, run up to about 24% or more per pass. It is further noted that the percentage of reduction varies substantially directly in accordance with the roll pressures, throughout a wide range."

It has also been found that by the use of this invention, the hardness of the reduced strip on the Rockwell scale is substantially higher throughout a range of roll pressures such as above specified.

In Fig. '7, a combined roll drive and pulltype of two-high mill is shown equipped for carrying out the invention. This mill includes a millhead with rolls as at 16, 11 positively driven by a motor 18 which receives its current from power mains I9 through suitable connections 90 as shown. Motor 18 may be connected to the roll shafts through a suitable gear train 9i-9l as shown. Strip reels 85, 86 may be connected respectively by gears as at 91, 88 to electrical machines 89, 99-, which machines are adapted to operate either as motors or'as generators, de-

pending upon the direction of travel of the metal strip 9|. The machines 99, 90 are shown connected in series with the generator of a motor generator set 92, 93, the motor of which derives its power from mains 19 through suitable connections as at 94. The manner in which one of the machines 89, 90 will operate to apply pulling tension to the metal strip 9| while the other machine operates to apply back tension, and while the rolls are also driven by the motor 18, has long been well understood in the art and need not be here explained in further detail.

As in the case of Fig. 3, the arrangement in Fig. '7 includes spray nozzles for continuously directing sprays of oil under pressure onto both the upper and under surfaces of the strip as it enters the pass, and onto portions of the roll surfaces contacting with the strip, to provide continuous coatings of the oil flooded'over the strip and roll surfaces as same come into contact. For example, a series of nozzles 95 is arranged nozzles 91, 98 may be supplemented respectively by a series of nozzles as at 99, 199 at a point somewhatin advance of the nozzles 91, 98. The nozzles 99, I90 preferably are interspaced in relation to nozzles 91, 98 in directions transverse to the strip. In Fig. 8 the arrangement of nozzles adapted for this or similar types of mills is shown more clearly in an elevational view, the nozzles being indicated respectively at 95'--lilll'. It will be understood that, as in the case of Fig.

1, the sets of nozzles may be substantially duplialong roll 16 and directed downwardly and inwardly, and another series of similar nozzles 96 is arranged along roll 11 and directed upwardly and inwardly. These will serve to supply the oil coating upon the portions of the roll surfaces,

just as the same come into contact with the strip;

adjacent the lower surface of the strip. The

cated at each side of the rolls and that shut-off valves maybe provided to permit application of the oil sprays only to the surfaces on the entering side of the pass.

I claim:

1. In a two-high mill for the cold reduction 0 metal strip: a pair of undriven, anti-frictionally mounted reducing rolls between which the strip is fed, power driven means for pulling the strip between said rolls, means for applying pressure to the rolls for cold reducing the strip, and means for flooding the strip and rolls on the entry side with a lubricant capable of withstanding the rolling pressure, thereby more efiiciently to reduce the strip. v

' 2..In atwo-high mill for the cold reduction of metal strip: a pair'of undriven, anti-frictionally mounted reducing rolls between which the strip is fed, power driven means for pulling the strip between said rolls, means for applying pressure to the rolls for cold reducing the. strip, means for flooding the strip and rolls on the entry side with a lubricant capable of withstanding the rolling pressure, thereby more efliciently ,to reduce the strip, and means for applying back tension to the strip on the entry side for further enhancing said cold reduction.

8. In a two-high mill for the cold reduction of metal strip: a pair of anti-frictionally mounted working rolls between which the'strip is fed, said rolls being of sufllciently large diameter and size to permit of applying driving power thereto, power-driven means for progressively feeding the strip between said rolls, including drive applied to said rolls and tension exerted on the strip emerging from said rolls, means for flooding said strip and rolls on the entry side with a lubricant capable of withstanding the roll pressure,

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