US1797053A - Method of rolling - Google Patents

Description

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METHOD OF ROLLING Filed Dec. 14, 1927 2 Sheets-Sheet 2 F .2. Mmmlllunummm [y 20 mumnmmmmmm EN'roR AW @MMM jdw.-

Patented Mar. ,17, 1931 'UNITED sTATEs PATENT OFFICE WILLIAM F. DETWILER, OF TARENTUM, PENNSYLVANIA, ASSIGNOR'TO ALLEGHENY STEEL COMPANY, OF BRACKENRIDGE, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA METHOD OF ROLLING Application led December 14, 1927. Serial No.v 239,905.

This invention relates broadly to the manufacture of metal sheets and more particularly to the manufacture of full finished sheets such as low carbon steel sheets commonly referred to as automobile and furniture sheets because of their highly finished surfaces and suitability for, deep stamping operations.

The utility of the present invention is not lo limited, however, with respect to the analysis of the sheets produced nor to the uses to which such sheets are to be put.

The standard or ordinary method of producing sheets comprises a long series of steps in which the material is alternately heated and rolled and in `which the rolling operations are further involved by matching, pairing, doubling, shearing and opening.

Cunningham Patent No. 1,536,663 of May 5, 1925 sets forth a rr ethod of rolling sheets in which the vstandard or ordinary methods are modified by substituting certain cold rolling operations for some of the hot rolling operations. It may be said that this patent contemplates a reduction by hot rolling and a material reduction by cold rolling so carried forward that the sheets when annealed are free from Steads brittleness. Caugherty andflookey Patent No. 1,536,660 of the same date sets forth a modification of the Cunningham method in which a somewhat greater reduction is made during the cold rolling operation with a resultant saving in cost.

la hile l follow to some extent the methcds set forth by the above mentioned patents, in that accomplish material reduction by both hot and cold rolling and produce sheets free from Steads brittleness, my improved t@ method differs from the methods of these pate-nts as well as from the standard or ordinary methods of rolling sheets in that I eliminate difficult and expensive hot rolling operations, which to some extent characterize "-5 `all these methods, and i in fact eliminate all hot rolling operations which specifically characterize heretofore known methods of rolling sheets.

l In the accompanying drawings, l have )o shown more or less diagrammatically for purposes of illustration only, the successive steps utilized in carrying out the method of this invention, it being understood that the drawings do not define the limits of the invention as changes in the construction of the different elements of equipment and in the operation thereof may be made in many instances without departing either from the spirit of the invention or from the scope of my broader claims.

Figure 1 is a diagrammatic view illustrating steps or operations which may` be successively employed in carrying forward my invention. These steps or operations are indicated by diagrammatic views of apparatus for performing them.

Fig. 2 is a diagrammatic view of one form of four-high mill and accessor equipment utilized for the obtaining of certain desirable results in accordance with the present method.

In practicing the present invention, I may start with an lngot 2 heated to the desired temperature and subject this ingot to a rolling operation in one or more suitable mills 3 for producing a billet or strip 4 having the desired with and thickness, with the-length thereof dependent upon the original size of ingot 2 and the amount of reduction to which the ingot is subjected in the rolling operation. This strip or billet i may be subjected to the 'action of shears 5 for the production of slabs Si of the desired dimensions.

IThe slabs are of such dimensions as to be readily handled and are subjected to a heating operaj'en in a suitable furnace 7; the

slabs preferably but not necessariiy, passing therethrough in substantially flat position as indicated. After being raised to the desired temperature in furnace 7, these siabs are snb- 1 jected to an edge rolling operation in an edging roll pass 8 for the purpose of breaking the scale therefrom. vvlfithout reheating, and with the scale effectively removed by the scale breaker, the slabs are subjected to a further rolling operation in either a two-high reversible or three-high continuous mill 9 suitable for transforming the slabs into skelp 10.

rlhe skelp as produced is piled in any desired manner into a pile or stack 11 so that the heat stored in the mass of piled skelp is effective for the self annealing of the material. After the annealing has been completed, the sk'elp may be sheared cold by a shear 12 into lengths 14.-, which for the purposes of this application, I term skelp plates. These skelp platespreferably have a length substantially equal to the`width of the sheets to be produced therefrom. These skelp lates are then preferably subjected to a pic ling operation ina bath 15 to remove all scale therefrom and to provide clean surfaces. These pickled skelp plates may thereafter be 5 arranged in piles 16 or otherwise conveniently arranged for subsequent use.

The asses of the skelp mill 9 are preferably formed so as to rcarf the skelp along bo-th edges in order that either long edge of the skelp plates may be readily entered in -the passes of the cold roll mills. f One or both long edges of the skelp or skelp' plates may be beveled in any manner other than by sca-rfing if desired, but I find that the cheapest Wa of beveling these -edges. is by scar-fing the skelp during its formation.

The pickled andl cold skelp plates having' their long edges beveled are now subjected to a cold rolling operation comprising one or more passes in either the same mill or in a series ofsimilar mills.

Before the skelp plates are entered in the first cold roll pass, they are subjected to a cold flattening pass in a mill 16a.

When making loW carbon steel sheets suitable for deep stamping'operations, it is necessary, in order to obtain sheets that are free from Steads brittleness after final annealing, to subject the sheets or rather the mateto astrain which is at least equal tothe strain to which low carbon steel issubjected when itis given about a 10% cold reduction.

The cold rolling of the skelp plates into finished sheets in accordance with this invens tion is preferabl carried out in a series of ,t four-high mills 1 of Whichany desired number may be provided and I have found that the strain above referred to for producing low carbon steel sheets free from Steads brittleness after finalanneal, may, if desired, be given to the skelp plates in the first cold roll pass and I have found that in order to be sure that/the material is subjected to this strain, it is desirable to obtain this strain in the first cold roll pass by effectingabout a 10% reduction.

In practicing this invention,I .have found `that in order to obtain the best results, it is necessary to control the contour of the passes formed by the reducing lor Work rolls 18 of the four-high mills.

Reducing rolls because of heating due to Work and friction during rolling tend to distort or puff as 1t is ordinarily termed, and conrial from which the sheets are being made,

sequently in puffing, change the shape or contour of the pass formed thereby. I have found that I am able to overcome any tendency of the reducing rolls 18 to puE or distort by controlling their temperature, and that therefore I am able to accurately control the contour of the passes through these reducing rolls.

I have found that the contour of the reducingpasses can be maintained constant if the temperature of the reducing rolls' is maintained constant and- I have found that this can be satisfactorilydone by making the reducing rolls hollow and causing sufiicient temperature controlling medium to flow therethrough. Y

I preferably use Water as the temperature controlling medium and control its flow by means of valves as will be readily understood. In some instances Where extremely cold Water is desirable and is not available; or when the Water supply is limited, I find it advantageous to cool the Water by passing it through" a refrimerating device before it is delivered into the hollow reducing rolls.

Th Water may enter one end of the rolls and leave at the other end, or one end of the rolls may be plugged and the Water conveyed by a pipe into the rolls to a point adjacent the plugged end andthen allowed to flow out through the open end around said pipe. 'y

Inasmuch as itis not feasible during rolling to stop the mill or mills and actually measure the temperatureof the reducing rolls,

I preferably provide means for giving a visible and continuous check 'on the temperature of such rolls.l I preferably accomplish Vthis in the manner disclosed in Figure 2 of the drawings, by utilizing a plurality of gauges 19, which are secured toa rigid bar 20, 'sup- 105 ported independently o'f the mill housings 21,

by suitable standards 22. By supporting the bar 20 independently of the mill housings, it

is not subjected to their deflections. A portion 23/of each of the gauges continuously 110 bears against the surface of one ofthe backing rolls, preferably in the plane jWhich includes the roll axes, so as to visibly indicate any deflections in suchbacking roll. It will be apparent to those skilled in the art, that should the temperature of the Work or reducing rolls increase, they will undergo an expansion incident to that temperature increase, which, in turn, is reflected in the deflection of the backing rolls. Thiswill be immediately indicated `by the indicating gauges 19, and may be used by the operator, ras a basis for determining the condition of the roll pass. Gauges 19 visibly indicate when changes in the contour. of the roll passes occur. j N x l a By observing these gauges, the operator is advised when to vary the amount or Atemperature ofthe water or other cooling medium,

circulating through the reducing rolls; in-

tenance of the desired pass contour.

Because of the fact that I prevent puffing ofthe reducing rolls of the cold roll millstby flowing coolin medium through the same, I dress these reducing rolls so as to provide a convexity alon the line of rolling sufficient to compensate or the spring of the rolls durin the rolling operation.

or example, I have found that it is' feasible to allow the reducing rolls to spring during rolling .005 of an inch. I have also found that it is possible by means of backing rolls of my construction to limit this spring to .005 of an inch and I therefore dress the reducing rolls so as to provide la convexity along the line of rolling of .005 of an inch, thus insuring a parallel sided or flat rolling pass.

With indicating means of the type herein diagrammatically disclosed, and made the subject of my co-pending application Serial No. 239,904, filed by me on December 14, 1927, the spring of the backing rolls is visibly and continuously indicated, thus constantly advising the operator as to whether or not the desired contour of the working pass is being maintained.

The initial setting of the rolls may be obtained by screw down mechanism 25 of any desired construction and efectiveagainst the roll neck bearings. These bearings may be of any desired construction, but I preferably use bearings of the tapered roller type.

I have found that the amount of roll spring of the backing rolls may be reduced to a comparatively small percentage of that heretofore considered as the minimumfor fourhigh mills, by utilizing fillets 26 connecting the roll bodies and necks, and bearing (with respect to radius of curvature) a definite relation to the diameter of the rolls.

In accordance `with the present invention, this radius of curvature is equal to at least three per cent of the diameter of the rolls, and preferably considerably in excess of that and-up to six per cent. With a 30 inch roll.

diameter a radius of curvature for the fillets of o ne and one-half inch has been found tg decrease the "roll spring under rolling operations from approximately .060 of an inch to .005 of an inch with the same pressure exerted by the screw down mechanism. These fillets, by reducing the roll spring enable me to control the contour of the pass during rolling more accurately than has heretofore been possible.

The cold rolled sheets after leaving the last stand of rolls may be trimmed and squared by trimming shear 27. After this operation the sheets may be annealed in accordance with standard practice, either by a box anneal or an open anneal 28, after which they may be smooth rolled in a suitable mill 29, and then leveled and smoothed in a suitable leveler 30,

Inasmuch as the skelp plates are delivered to the cold roll mills with clean surfaces provided by tlie edging pass and the pickling operation in bath l5, these mills are effective in producing extremely smooth and highly finished sheets, which is not the case with any hot rolling method in the presence of the scale incident to the temperatures employed in such rolling.

I have found that by reversing the material end for end between successive cold roll i -passes to one or more cross rolling operations for the purpose of improving the physical structure of the sheets.

It will be obvious to those skilled in the art that the present invention does away with all surfacemarring incident to hot rolling, and it enables a more rapid production of full or highly finished sheets than has heretofore been possible. It also reduces the cost of such sheets. "M

This invention also provides a method of making individual sheets as distinguished from strip sheets without the necessity of carrying out the difficult steps of pair heating followed by the matching, rolling, reheating, rematching, doubling, and the like incident to standard sheet mill practice.

Other advantages arise7 from the cold rolling of skelp plates having surfaces which are free from scale and otherwise clean and whichl are maintaiiied in clean condition during all ofthe rolling operations from such plates to finished sheets.

Still further advantages of the invention arise from the use of four-high mills in cold rolling; from the control of the spring of the backing rolls of such mills; from the relationship maintained between the backing roll spring and the convexity of the reducing rolls; from the c ontrol and maintenance of the ldesired temperature conditions in the reducing rolls; from the indication of the temperature conditions and roll spring during rolling, and from the control4 of the characteristics of the nished sheets by t-he strain plates are produced whereby said plates, prlor to plckling, have surfaces which are smoother than would be obtainable during rollmg 1f any scale were present; from the 5 scari'ing of the skelp plates and from the flattening of such plates prior to their entrance in the cold roll passes.

This invention provides a method by means of which plates sheared or otherwise formed fromskelp are individually cold rolled into finished sheets. The method is extremely flexible and allows individual treatment of each sheet in its progress through the cold roll passes.

What I claim as new and desire to secure by Letters Patent is 1. rI"he method of rolling sheets, which conslsts in hot rolling slabs, in cutting said slabs into suitable lengths, in edging such lengths to remove the scale, in rolling such scale free lengths into skelp, in cutting the skelp into lengths substantially equal to the width of the sheets to be produced, in picking the scale from such lengths, then in cold rolling such .scale free lengths into finished sheets and then in annealing such sheets.

2. The method of rplling sheets, which consists in hot rolling sla-bs, in cutting said slabs into suitable lengths, in edging such lengths to remove the scale, in rolling such scale free lengths into skelp, in cutting the skelp into .lengths substantially equal to the width of the sheets to be produced, in pickling the scale from such lengths, then in cold rolling such scale free lengths into finished sheets .and 7then in box annealing such sheets. p

3. rlhe method of making sheets, which consists in forming scarfed skelp, in hot rolling said scarfed skelp, in shearing the skelp into skelp plates, in pickling said plates to remove the scale, then in feeding a scarfed edge of such plates to cold rolls and in cold rolling the same into finished sheets and then in annealing such sheets.

4. The method of making sheets, which consists in forming scarfed skelp, in hot rolling said scarfed skelp, in. shearing such skelp into skelp plates, in pickling the scale from such plates then feeding a scarfed edge of such plates to cold rolls and in cold rolling the same into finished sheets and then in annealing such sheets, the drafts during lcold rolling being such that the material is given a strain at least equal to that given low carbon steel when it is subjected to about a 10% cold reduction.

5. The method of making sheets, which consists in forming scarfed skelp, in hot rollv ing said scarfed skelp, in shearing such skelp into skelp plates, in pickling the scale from such plates then in feeding a scarred edge of such plates to c'old rolls and in cold. rolling the same into finished sheets and then iu annealing such sheets, the reduction in the first cold roll pass being equal to about 10%.

finished sheets and then in annealing such sheets.

8. The method of making sheets, which consists in hot rolling to form skelp, in annealing the skelp, in shearing the annealed skelp into skelp plates, in pickling such plates, in cold rolling such pickled plates into finished sheets and then in annealing such sheets.

9. The method of making sheets, Which consists in reducing an ingot to billet form, yin shearing the billets into slabs, in heating the slabs, in edging the slabs to remove the scale, in'rolling the slabs into skelp, in annealing the skelp, in shearing the skelp into skelp plates of a length substantially equal to the Width of the sheets to be produced, in pickling such plates, in flattening the same, then in cold rolling the flattened plates to the length and gauge of the finished sheets and then in annealing'such sheets.

10. The method of making sheets, which consists in reducing an ingot to billet form, in shearing the billets into slabs, in heating the slabs, in edging the slabs to remove the scale, in rolling the slabs into scarfed skelp, in annealing the skelp, in shearing the skelp into skelp plates of a length substantially equal to the. width of the sheets to be produced, in pickling such plates, in flattening the same, then in entering a scarfed edge of such plates to cold rolls and in cold rolling the flattened plates to the length and gauge of the finished sheets and then in annealing such sheets.

11. rI'he method of making sheets, which consists in reducing an ingot to billet form,

rolling the flattenedplates to the length and gauge of the finished sheets and then in annealing such sheets. A

12. The .method vof making sheets, which consists in rolling to form skelp, in annealing the skelp, in shearing the skelp into skelp 'ai i plates of alength substantially equal to the width of the sheets to be produced, Ain pickling the scale from such plates, then in cold rolling such pickled plates into linishedv sheets through a succession of cold roll passes and Vthen in annealing such sheets, the material between two or `more of such cold roll passes being turned end for end.

13. The methodot making sheets, which consists in rolling to form skelp, in annealing the skelp, in shearing the skelp into skelp plates of a length substantially equal to the width of the sheets to be produced, in pick ling the scales from such plates, then in cold Rolling such pickled plates into finished sheets through a succession of cold roll passes and then in annea ing such sheets, the mate- A rial between two or more of such cold roll perature controlling medium through such' rolls.

15. The method of making sheets, which consists in hot rolling to form skelp, in annealing the skelpz in shearing the same into skelp plates, in plcklin the scale from such plates and then in col rolling such pickled plates to the length and gauge of the inished sheets through a succession of cold roll passes, maintaining said cold roll passes at constant temperature and controlling the .spring of said rolls with the aid of backing rolls.

16. The method of making sheets, which consists in hotrolling to form skelp, in annealing the skelp, in shearing the same into skelp plates, in pickling the scale from such plates, then in coldy rolling such pickled plates to the length and gauge of the fmished sheets through a succession of cold roll passes maintained at constant temperature .and in which the temperature of the reducing rolls is controlled by owng ya temperature controlling medium therethrough, in continl,

uously checln'ng the temperature conditions of such rolls during rolling and in varying the iow of the temperature controlling medium in accordance with such check.

17. lThe method of making full nished low carbon steel sheets free from Steads brittleness, which consists in hot rolling slabs to form skelp, in cutting the same into relatively short lengths, in pickling such lengths then in cold .rolling the pickled lengths through successive roll passes into sheetsd of the length and gauge desired and then in annealin the sheets; the drafts during cold rolling eing so controlled that the material is given a strain at least equal to that given low carbon steel when it is subjected to about a 10% cold reduction in a single pass.

18. The method ofinaking sheets, which consists in roll reducing an ingot to form skelp, in self annealing the skelp, in cold;

shearing the skelp into plates, in pickling the scale from such plates, in cold rolling such plates to the length and gauge desired in the finished sheets, then in annealing the sheets; said cold reduction being accomplished by rolls forming a succession of passes in the first of which a reduction of about 10% is obtained, in reducing the roll spring in such passes by opposing the vertical thrust of the reducing rollsby backing rolls, in visibly indicating changes in temperature in the reducing rollsand in controlling the temperature of the reducing rolls in accordance with said indications'by owing a temperature regulating medium through such rolls.

19. The method of making steel sheets comprising the following steps in substantially the order named: reducing an ingot of steel to form a strip, shearing the strip to form slabs of pre-determined size, heating said slabs by passing them through a furnace of predetermined heat, edge rolling and scarfng said slabs, rollingsaid scarfed slabs to form skelp, self-annealing said skel shearing said scarfed skelp to form ske p plates, pickling said plates, iattening the same, enteringa scarfed edge of 4such plates between cold rolls and plurally cold rolling said plates to pre-determined size, theconditions `of cold rolling being mechanically controlled through temperature control, trimming saidv sheets, annealing them, and finally smoothing and leveling t e same.

In testimony whereof, Iv have hereunto subscribed my name this 10th day of December, 1927.

W. F. DETWILER.

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