US2139872A - Sheet metal and procedure for producing the same - Google Patents

Description

13, 1938. w WORTHINGTON 2,139,872

SHEET METAL AND PROCEDURE FOR PRODUCING THE SAME Original Filedkug. '7, 1933 4 Sheets-Sheet 1 IIZZNTOR:

Dec. 13, 1938. 2,139,872

SHEET METAL AND PROCEDURE FOR PRODUCING THE SAME W. WORTHINGTON INVEN TOR Deg.13, 1938. w WORTHINGTON 2,139,872

E FOR PRODUCING THE SAME SHEET METAL AND PROCEDUR 4 Sheets-Sheet 4 Original Filed Aug. 7, 1933 DR/ VEN ROLL Jg'gll.

DR/ VEN ROLL INVENTOR Patented Dec.

UNIT

s. PATsNroFFIcE DUCING 'rnEsAME Warren Worthingtom Pittsbnrgh, Pa.

Application August 7, 1933, Serial No. 684,001 Renewed May 27, 1937 9 claims- (or. 29- 48) This invention relates to procedure for pm ducing sheet-material; and also relates to the production of a new product having new and improved physical characteristics. y

By the term sheet material; I mean metal rolled to athickness comparable to the thickness obtained in p resent sheet or strip" rolling operations, and independent of the'final length or width of the material. 1 v I Y An'object of myinvention is to ll'IlPlOVB the physical characteristics of sheet material.

A further object is to decrease th'e cost of production of sheet material.-

A still "further ob jectis to decrease the cost of the rolling equipment'employed in rolling sheet material.

A fundamental object of m y-invention is'to produce a rolling procedure wherein both the rolling pressure and'the power utilized for caus ing the material to traverse I theroll pass are effectively employed. i i

For many years it has been generally recognized that the rolling of sheet material may be more effectively accomplished with small rolls and for this reason it has long been "thepractice-- to employ'f'o'ur-high and'similar' mills, such as cluster mills, because they provide structures in which-'working rolls of small diameters may be employed without excessive deflectionunder the forces encountered.

I have, however, discovered that in order to most effectively employ the necessary forces; the projected line of contact between the rolls and the material'being'rolled must be reduced even further'than is possible with existing apparatus.

that the projected effectively reduced -I have also discovered lineof contact 'can' be more by-employ pp ir' ing rolls of unequal diameter than with opposed rolls of equal diameter; that is found that the opposed rolls tact the material traversingthe rolling pressure to tact may be obtained.

which directly con-' the pass and apply of the projected line'of con- In all rolling operat ons where small rolls are employed, the rolling torque driving reducing rolls. reducing roll mustbe of r the necessary torsional strength to transmit the the material traversing the propelling force to pass.

tact maybe reduce This necessarily on the projectedline of contact. ever, discovered that: the projected lineof con-v d by not only employing rolls 'That' is-to say; each suchsuficient size to provide has an influencing effect diameter of this to say, I have that material; should be diameters in order that the most limits the size "of the I have;v howroll and a smaller undriven rolLwhich contacts with the material being rolled and is 'infact driven by that material. 'I have also discovered that there is a definite'relationship between the ,5 projected line of contact and the permissible smaller roll; This discovery has led-to the further discovery that in continuous mill operations both reducing rolls and particularly the smaller and undriven reducing rolls of the various stands may be, and preferably should be; progremively decreased in diameter toward the delivery end of the mill. This follows" from the fact that although the percentage of reduction in each of the successive stands of a'c'ontinuous mill may be maintained'the same, the vertical displacement of the-material necessarily decreases from stand to stand, and this in turn results in aprogressive decrease in the projected line of contact from stand to stand. v 20 It has been recognized that in any rolling pro: cedure where but one roll is driven, the resulting re-arrang'ement of themolecules in the material rolled differs, to some'extent, from the molecular re arrangement obtained by employing I two driven reducing rollsjbut I have discovered that an "improved molecular structure and a consequent improvementinthe physical properties of sheet material can be obtained'by employing an undriven reducing roll which is of materially less diameter than has heretofore been considered practical in-anyrolling operation. A further object of my invention is; therefore, to pro duce strip material having a molecular formation diflere'nt from sheet material heretofore produced and having physical characteristics which correspond to its molecular characteristics.

These and other objectsare attained by means ofthe procedure-hereindefined, which is carried forward bymeans of apparatus having the characteristics of the apparatus herein illustrated.

In the drawings accompanying'and'forming a part hereoflFlgure 1 15' a sectional view of a mill embodying my invention-and of a mill capable ofcarrying forward the-procedure herein defined as a part of the present invention; the section of Fig.- 1- is taken along the line A-A of Fig.2 is a sectionalview along the line 13-15 ofFighly Fig. 3 is a fragmental side elevation of the mill shown in Figs. Land 2;

Fig. 415a --agmental sectional view along the line C- .C 01 1 Fig. 5 diagrammatically'discloses a roll assemon the horizontal and vertical components of the within the crotch forces illustrated in Fig. 10.

It will be understood that various modifications of the apparatus for carrying out my invention may be employed, and that the several views'of the drawings are merely illustrative of such apparatus. The mill illustrated in the drawings, however, includes the usual baseplate (not shown),

the usual side frames l2, which are provided'with the usual windows for the bearing boxes or housings. As illustrated, the side frames l2 are separately formed and are secured together adjacenttheir upper ends by means of bolts l3. Each side frame is provided with the usual screwdown H, which acts bearing housing ii of a backing roll li. As 11- lustrated,the backing roll l6 engages a working or reducing roll I! of relatively small diameter,

which, like the backing roll, is provided with roll 'necks and is journaled in separate bearings l8,

which are movable with relation to the frame l2.

As shown, the boxes for the bearings l8 fit within recesses in the boxes of the backing roll bearings.

The roll I1 is a driven roll and is shown in Fig. 1

as operatively connected to a driving means, such as a motor l9, by means of a spindle 20 and coupling 20'. This roll is what is ordinarily termed a working roll in that it engages the material to be reduced, 1. e., the sheet material traversing the pass. As shown in Fig. 1, the opposed working roll 2| is of materially less diameter than the roll I! and it is held in place within the crotch formed by two idler rolls 22, which in turn are located formed by two co-operating backing rolls 23. The backing rolls 23 are provided with the usual form of bearing boxes, which are held rigidly in place with relation to the frame "-42. The idler rolls 22 are also provided with roll necks, which are mounted in suitable bearing boxes as shown in Figs. 3 and 4. These hear- "ing boxes may be fitted in recesses formed in the bearing boxes of the backing rolls 23 and, as shown, each of the recesses for receiving these boxes extends radially with relation to one of the backing rolls 23 so that the rolls 22 may move radially, with relation to the rolls 23, for the P pose of taking up wear. 4

In Figs. 6 to 9, I have shown various roll assemblies in section, but it will be understood that in each such assembly, the roll 2| is an undriven working roll and that the roll I1 is a driven working roll, that. the rolls l6 correspond in function to-the backing rolls iii of Fig. 1 even where two such rolls are shown; and that the idler rolls 22' correspond in function to the idler rolls 22 even where but one is illustrated.

It will be apparent that some means must be employed for preventing lateral displacement of the undriven working roll 2! and in each illustrated roll assembly, I have so arranged the cooperating rolls that the undriven working roll is held in place by co-operating backing rolls which in some cases act on the roll 2| through the agency of idler rolls. Other means for preventing lateral displacement of the undriven working areas-72 in the usual manner on the material rolled and roll, may, of course, be employed without departing from either the spirit or scope of my invention.

In the operation of a stand such as illustrated in Fig. l, the vertical deforming force is applied to the material by adjusting the screw-downs so that the space between the working rolls l1 and 2| corresponds to the desired thickness of the material after it has traversed the pass, consequently,-the vertical force exerted by these rolls will depend upon the resistance of the material to the distorting force so applied.

In Figure 10, I have diagrammatically illustrated the positions of the opposed working rolls and their relation to the piece traversing the pass and I have also illustrated by force diagrams the direction of the resultant of these two forces.

The force diagram associated with the roll 2| in Figure 10 may be termed a diagram of the reactive forces, since it discloses the forces which are in eflect transmitted to the roll 2l-through the material acted upon. As there illustrated, r is any radius of the undriven roll and r a radius extending to the so-called neutral point; L' represents the magnitude and the direction of the vertical distorting force occasioned by roll 2l and it is apparent that this force is equal and opposite to the force represented by L. T represents the direction and magnitude of the tangential force transmited by the periphery of the roll 2| to the material 25 at the neutral point within the pass, and S represents the direction and magnitude of the resultant of the two forces T and L. In the drawings, I have so considered the forces acting on the material 25 that the neutral points on the upper and lower surfaces of the material are opposite each other. This, however, may or may not be an absolutely accurate representation of the conditions, but it gives a fair approximation of the action of the opposed forces on the the force diagrams substantially disclose the relative directions and magnitudes of the forces acting on both the material being-rolled and on the undriven working roll.

Figure 11 shows the magnitude and direction of the vertical and horizontal components of the resultants P and S of Figure 10. In both Figures 10 and 11, the resultant force P is equal in magnitude and acts in the same direction. This is also true of the resultant S. The vertical and horizontal components N and Q of the resultant P, necessarily differ in magnitude from the forces L and M, but they disclose both the direction and magnitude of the deforming and the propelling" sent the direction and magnitude of the vertical force and the retarding force transmitted to the material rolled by, the roll 2|.

From the foregoing it is apparent that the material 25 is subjected to opposed forces during its movement through the-pass and. that these forces,

acting as a couple, not only have a deforming effect on the material itself, but they also have a tend to impart a rotative movement to each of.

the various crystals, with the result that the crystals are not only displaced longitudinally of the piece and with reference to each other, but

each crystal is turned about a point within itself during the deforming operation. I have discovered that this longitudinal translation of the molecules-with relation to each other should bear some relation to the percentage of reduction, or better, to the amount of vertical distortion to which the piece is subjected and that the relationship of the opposed forces acting on the material should be such that the longitudinal dis-' placement of the molecules on the driven roll side of the material with relation to those on the undriven roll side should be atleast 4% of the vertical distortion accomplished in each pass. As a matter of fact, the opposed forces should be so proportioned that this longitudinal translation of molecules should somewhat exceed 4% of the vertical distortion. Under such conditions, the piece 25, after having traversed the desired number of passes, will not only be reduced to the requisite thickness, but the molecules of the piece will also have beensubjected to such rearrangement with relation to each other that each molecule is turned about an internal axis. One of the advantages of this new molecular structure is that the material being rolled does not increase in hardness in proportion to the rolling strains to which it is subjected and consequently, in cold rollirig operations, the material may be subjected to greater reductions per pass and a greater number of passes without the necessity of intermedi= ate annealing.

These beneficial results are the direct result of employing working or reducing rolls of small diameter, one of which is an undriven roll of a diameter substantially less than that of the driven roll. I have discovered that there is a relationship between the diameters of the driven and undriven working rolls and the draft of the pass which must be adhered to in order to obtain the best results. In designing the rolls, it take into consideration the percentage of reduction to be accomplished in the pass, and I necessarily consider the torsional strength of the driven working roll under the conditions of draft encountered. This fixes the minimum diameter of the driven wort: roll. The diameter of the undriven work. roll must then be such that the projected line of contact will at least equal the draft divided by the coefficient of friction between the material rolled and the surface of the driven roll, or in round numbersequal to about ten times the draft, and this relationship of the two reducing rolls should be maintained at least within close limits. From the foregoing it is apparent that I employ small reducing rolls of unequal diameter, and that I drive the roll of larger diameter, while maintaining the undriven roll as small as possible and while maintaining the proper relationship between the rolls and the projected line of contact. It is also apparent that my improved sheet rolling procedure consists in subjecting the material be ing rolled to opposed deforming forces so applied that the forces act on the material as a couple,

and not only decrease the thickness. but produce a new molecular structure by in effect longitudinally displacing one portion of the material with relation to another portion and to such an extent that each molecule or crystal is'rotated about an axis within itself.

My procedure not only contemplates successive applications of such forces to the material rolled in a succession of stands, such as in a continuous mill, or in a tandem arrangement of stands, but I also contemplate a modification of the procedure above outlined wherein the material after traversing one or more such passes is subjected to a cross rolling operation under conditions above defined, so that the molecular structure is further modified by longitudinally advancing the molecules-or crystals on one side of the material with relation to those on the other side, and in causing each such molecule to roll or turn about an internal axis substantially at right angles to the axis of its former rotation. It will also be ap-' parent that the direction of rolling may be varied after each pass or after any desired number of passes so that after one or more cross rolling passes the material may again be rolled in the original direction of rolling or even in a reverse direction and may then again be subjected to one or more cross rolling passes. I, of course, contemplate the necessary cutting of the material in order that it may be rolled in a direction at right angles to its former direction of rolling.

In my improved process, the material rolled is not only reduced in gauge by each pass, but it is also subjected to a longitudinal deformation. This longitudinal deformation not only involves the extrusion normally resulting from subjecting metal to the action of a reducing roll pass, but also consists of a relative offsetting of the molecules or crystals under such conditions that each crystal is rotated through an appreciable arc about an internal axis. As previously pointed out, this molecular displacement and rearrangement produces a new molecular pattern.

in accomplishing this I contemplate a relation between the diameter of the driven work roll and the undriven work roll on the order of more than two to one, that the diameter of the undriven work roll may be 1 /2" or less, in the case of extremely thin material, and that the diameter of the co-operating driven roll may be 16 or more. It'will be understood that this general relationship in size of driven and undriven work rolls is reproduced in all of the mill stands except, as heretofore stated, I contemplate a successive reduction in the diameter of the undriven work roll from stand to stand and toward the delivery end of the mill. In this connection I am referring to a continuous or a tandem mill.

In carrying out the procedure herein outlined, I am able to decrease the cost of production of sheet material, primarily because the projected line of contact and consequently; the projected contact area is materially reduced. This reduces the roll separation forces, the skin friction encountered and the pressure per bearing, all of which reduces the power required to accomplish the rolling operation and thus results in a reduction in the cost of rolling. The smaller and lighter rolls employed are not only in themselves cheaper, but the bearings, bearing housing and all parts of the stand structure are proportionately reduced in size and in this way the cost of rolling equipment is reduced. One important feature of my invention in connection with cost of equipment and cost of upkeep is that by em- Letters Patent is:-

1; The method of making sheet material, which consists in roll reducing metal to strip or sheet form in a number of roll passes and in at least one pass causing the molecules in one surface of the material to move further in the direction of rolling than those in the opposite surface and each'such molecule to turn through a substantial are about an internal axis, and then in cross rolling the material so as to obtain a transverse relative displacement of the molecules and a partial rotation of each such 'molecule about an internal axis substantially at right angles to the axis of prior rotation.

2. The method of making sheet metal, which consists in roll reducing metal to strip or sheet form in a number of roll passes and in at least one such pass in causing the molecules in one surface of the material to move further in the direction ofrolling than those in the opposite surface, in cutting the strip material thus formed into lengths, in cross roiling such lengths and in at least one such cross rolling pass causing the molecules in one surface of the material to move further in the direction of rolling than those in the opposite surface; such differential movement in each case being equal to at least 4% of the amount the material is reduced in thickness in each pass.

. 3. The method of making metal sheet material, which consists in roll reducing metal to strip or sheet form in a number of roll passes and in each such pass causing the molecules in one surface of the material to move further in the direction of rolling than those in the opposite surface; such differential movement occurring in the same direction in each pass; in cutting the material into lengths and in cross rolling such'material and in causingthe molecules in one surface of the material to move further in the direction of rolling than those in the opposite surface.

'4. The method of making metal sheets, which consists in roll reducing metal to strip or sheet form in a number of roll passes and in each pass in causing the molecules in one portion of the material to move further in the direction of rolling than those in an opposed portion; such differential movement reoccurring in successive Passes and the maximum relative movement between opposed molecules during each pass being equalto at least 4% oLthe amount the material is reduced in thickness in each such pass; in cutting the material and then in cross rolling the cold reducing. operation while subjecting such material to a force couple acting within the material, and then in cold reducing such material, Y

while subjecting it to a force couple acting within the material and across the direction of 'application of the former force couple.

6. The method of rolling sheet material which includes, deforming'a metal piece of material by applying pressure thereto and simultaneously. causing the crystals adjacent one side of the material to advance ahead of the crystals adjacent the other side of the material and in such a mannerexerting a rotative influence upon each of such crystals about an axis, and thence, exerting a rotative influence upon each of such crystals on an axis substantially at right angles to the axis or the first-mentioned rotative influence.

7. As a new article of manufacture, sheet-like material having properties characteristic of those obtained when metal is reduced to sheet-like form in a number of roll passes in at least one of which the molecules in one surface are caused to move further in the; direction of rolling than those in the opposite surface; each such molecule being caused to turn through a substantial are about an internal axis and the material being then cross rolled so as to obtain a transverse relative displacement of the molecules and a partial rotation thereof about internal axes substantially at right angles to those of the prior rotation.

8. As a new article of manufacture, sheet-like material having properties characteristic of those obtained when metal is roll reduced to sheet form in a number of roll passes in each of which the molecules in one surface are caused to move further in the direction of rolling than those in the opposite surface and the material is then cross rolled to cause the molecules in one surface to move further in the direction of rolling than those in the opposite surface.

9. As a new article of manufacture, sheet-like material having properties characteristic of those obtained when metal is roll reduced to sheet form in a number of roll passes in each of which the molecules in one portion of the material are caused to move further in the direction of rolling than those in an opposed portion; such differential movement recurring in successive passes and the maximum relative movement between molecules in each pass being equal to at least 4% of the reduction in such pass; the material being then cross rolled in a number of passes in each of which the molecules in one portion are caused to move further in the direction of rolling than those in an opposed portion.

WARREN woa'rnnva'ron.

Images