US2400690A - Method of rolling metal bars - Google Patents

Description

G, L. FISK METHOD OF ROLLING METAL BARS May 21, 1946.

4 Sheets-Sheet 2 Filed Aug. 19, 1945 G. L. F ISK METHOD OF ROLLING METAL BARS May 2l, 1946.

Filed Aug. 19. V194:1 4 sheets-sheet M n ,W mf d Rm. um. ,T mm. mm. 5 U. Sm um. www* 5 www. mm. GIM i 1m jv mm. m @NNN y Patented May 2l, 1946 UNITED STATES IPATENT oFFIcE 2,400,690 METHOD OF ROLLING METAL BARS Gustaf L. Fisk, New Fairfield, Conn. Applicatipn August 19, 194s, seal NB. 499,210

(o1. zzo-s6) 1 Claim.

This invention relates to the rolling of metal bars of'various sectional shapes, commonly known as merchant bars and shapes, whereby they may be finished to precise dimensions within close tolerances, and with improved physicalproperties.

such sizes, e. g., in the case of rounds, from 1/2" up, that they cannot be delivered in coils for processing operations requiring. straight stock, without injury to the material. l

In my copending Patent No. 2,369,730, for Method ofV rolling metal bars, I pointed out the diiliculties of rolling metal bars to precise dimensions by the methods and apparatus previously utilized. In said patent, furthermore, I disclosed and claimed a method of rolling bars by passing hot-rolled blanks of cooling-bed 1ength,'the sections of which have major and minor axes,-

through aplurality of stands of cold rolls, while applying tension to the bars between stands sufcient to prevent side-spread o'f the blank. Such method is entirely practical and feasible where suftlcient floor space is available in the vicinity of and immediately beyond Athe hot mill. ordinary circumstances, however, sufficient space is not available and the use of the method of my copending application is thus applicable principally to a new hot mill installation.

I have invented an improvement of the method disclosed in my copending application. whereby the essentials of the latter may be utilized in connection with existing hot mills without requiring extensive iioor space therein or thereabout. The improved method also makes possible the precision rolling and 4cold workingof a limited range of products with only a relatively small investment in equipment.

In a preferred practice of the invention, I take a hot-rolled blank, the section of which has a major axis and a minor axis diiering substantially therefrom, and coil the blank while hot as it emerges from the hot mill, with the major axis of its section parallel to the coil axis. When the coiled blank has cooled substantially to atmospheric temperature, I pickle it and then uncoil it while subjecting it to continuous cold-rolling l inaplurality of passes between parallel rolls, while maintaining tension on the blank sufficient Merchant bars are ordinarily required in Under to cause the product as delivered from the last scription and the accompanying drawings illustrating the practice of my invention as applied to rolling of bars of several diierent shapes, as well as the cold mill and'mill layout which I 4prefer to employ. In the drawings,

Figure 1 is a transverse section through a, blank suited for .cold-rolling in accordance with my invention to produce round bars iinished precisely to the required finished dimensions;

Figures 2 through 5 are partial sections through successive roll stands showing the shape of the passes therebetween, whereby the blank of Figure 1 is progressively reduced to nal shape and size;

Figure 6 isa plan view of a cold mill suited for carrying out the method of my invention;

Figure 7 is a similar View of a modied form of mill; l

Figure 8 is a plan view of a mill layout in which my invention may advantageously be employed;

Figure 9 is a similar View showing a modified Figures 11 through 14 are similar to Figures 2.-

through 5 and show the shapes of the passes between the rolls of the several mill stands whereby the blank of Figure 10 is reduced to final shape and size;

Figure 15 shows the shape of the starting blank, and Figures 16 through 19 the roll passes-adapted for producing bars of rectangular section; and

Figure 20 shows the sectiona1 shape of the starting blank, and Figures 21 through 24 the shape of the several roll passes, which I employ for rolling angles.

Referring now in detail to the drawings and for the present to Figures 1 through 5, in carrying out the method of my invention for the production of round bars, I produce a hot-rolled blank l0 by known rolling methods and apparatus. As shown, the blank I0 has a sectional x shape characterized by major and minor axes which differ substantially in magnitude. As the blank is delivered from the last pass in the hot mill, I coill it in a close helix by any suitable form of coiling mechanism, so that the successive turns of the coil have the major axis of their section parallel to the axis of the coil. In this way I lavoid any pronounced twist in the blank throughout its length during coiling, by permitting it to coil in the manner offering the least resistance to the bending linvolved in the coiling operation. I thus compensate for the normal tendency iof hot-rolled bars and rounds in particular, to twist about their own axis as they emerge from a rolling mill. In a bar of considerable length,v this twist may amount to a half turn or more, vthat is'to say, the trailing end of the bar may be displaced angularly as much as'180" from the leading end. Unless the roller is alert and the rolls and guides properly maintained and adjusted, the twist may, and frequently does, amount to one or more turns in a length of bar. 'I'his twistmakes veryy-diflicult the subsequent rolling of the bar in a cold -mill but I avoid this diiculty entirely by giving thehot-rolled blank a sectional shape characterized by major and minor axes which differ substantially'in magnitude, thus leliminating any substantial twist in the blank as it is coiled. When the coiled blank has cooled suiiiciently, it is subjected to a conventional pickling operation and is then ready for cold-rolling in a continuous mill such 'as that shown in Figure 6.

In cold rolling a twisted bar to accurate dimensions, it must be allowed to turn according to its twist in passing through the rolls. vSince the several sets of rolls are continuous, however, it follows that such a bar heldV correctly in the rst pass is out of its proper position in the succeeding passes by the degree of twist'in the distances from the first to the successive stands.

The pickled coil is placed ina coil holder II and the outer end thereof is entered between the rolls I2a and I2b of a horizontal roll stand I2. The rolls of stand I2 have a plurality of grooves I3 therein only one of which is shown in each roll. The grooves are shaped so that the blank on passing through the stand I2 has its minor axis slightly reduced, the major axis beingaiected little or none. The blank as reduced by the stand I2 is designated I. By reason of the difference between the major and minor axes of the section of a blank as it passes through the rolls of stand I 2, the blank is rigidly held against twisting as it moves forward to enter subsequent roll stands.

For the sake of simplicity, only one ,pass has been shown in each set of rolls although the rolls have room for several passes and each set is adjustable longitudinally to bring any pass into alignment with the straight and xed pass line, along which the bars are made to travel through the rolls of the cold mill.

From the rolls of stand I 2, the blank enters the pass between vertical rolls IIIa and IIb of the second stand I4. 'I'he rolls of this stand have grooves therein effective to reduce the major axis of the blank materially, as shown at IIlb. 'I'he blank next enters the pass between vertical rolls I5a and |517l of a third stand I5 where its major axis is further reduced`to such value that it becomes the minor axis, being less than the original minor axis, as shown at Illc. Finally, the blank enters the pass between horizontal rolls I6a and I 6b' of the fourth stand I6 having grooves therein effective to reduce the vertical height of i the blank precisely to the horizontal sectional dimension, thus converting the blank into a round bar I1 of accurate size and shape.

After passing through the rolls of stand IG, the finished bar may be delivered straight to appropriate means for further processing and handling, yfor example, as shown in Figures 8 and 9. On

theother hand, if desired, the finished product may be coiled by means of a coiler I8 as shown in Figure 7. The mill shown in this figure is otherwise similar to that of Figure 6. The coller is preferably driven by a suitable motor with control devices appropriate to maintain the desired tension on the portionof the bar between the coiler and the stand I6.

During the successive reductions of the blank by thev several stands I2.,` I4, I5 yand I6, I maintain the material betweestands under tension by suitably controlling the speeds of the rolls of the several stands. Each stand is preferably driven by an individual motor. Apparatus is commercally=available forcontrolling the speeds of mill motors in relation one to another so as to effect the desired tension of the material and it is unnecessary, therefore, to include here any specificl disclosure of the means whereby such tensioning is obtained. The tension is preferably maintained suiiiciently high to limit side-spread of .the blank `in the horizontal roll stands and Y vertical spread in the vertical roll stands, as fully stands because of .the diierence between thev major and minor axes of the blank I0 and the fact thaty the blank` is rigid since it is rolled at substantially atmospheric temperatures. 'I'he spacing between the several stands I2, 14, I5 and I6, furthermore, is preferably kept at a minimum in order to minimize the detrimental effect of any slight twist remaining in the coiled blank, as the blank proceeds through the several stands, but principally to reduce to a minimum the length at the rear end of the bar which is rolled without benefit of' tension.

The .exact dimensions of the grooves in the rolls ofthe several stands may be varied slightly in order to produceseveral sizes of finished bars from onel size and shape of starting blank. By virtue of the straight pass line' through the several stands and the tension applied to the blank during rolling, it emerges from the last standv perfectly straight, in addition to being reducedy accurately to the required final size and shape.

It is 'well-known practice to straighten merchant `bars by stretching them after the rolling operation has been completed. Bars of superior straightness are obtained in this manner, by equalizing the internal strains in the bar, which cause it to be out of line.v It is one of the'objects of this invention to roll bars of superior straightness by cold-rolling under tension up to the finishing pass.

Figure 8 shows one mill layout for disposing of bars delivered straight from the stand I6 for further handling and processing. Finished lengths of cold-rolled bars are delivered successively by the last stand I 6 of the cold mill indicated generally at IS in Figure 9 ontoa runin batches and then transferred by shume bars or other suitable mechanism onto shear-approach tables 23. Batches of bars areldelivered by the tablesy 23 to shears 24 which out the bars into commercial lengths after which these lengths are delivered from run-out tables 25 to cradles 26 from which they Amay conveniently be lifted in bundles by an overhead crane.

, shapes of' starting blanks.

Figure 9 illustrates a modied form of mill layout providing dierent paths of travel for the finished lengths of ban-'depending on the degree of finish and type of cuts required for the ends thereof. For shearing in the manner described in Figure 8 the bars are delivered to a run-out table 21 and kicked ol therefrom to a transfer 28 on which a plurality of bars are assembled in batches for delivery to a shear-approach table 29. From the latter, the batch of bars is delivered to a shear 30, run-out table 3| and cradle 32, in the manner described with reference to Figure 8. If it is desired that the commercial lengths of finished bars have their ends sawed,

this may readily be accomplished by the arrangement shown in Figure 9 in which the bars are delivered individually from the run-out conveyor 21 to a transfer 33 and thereby placed on a sawapproach table 34. Alternate bars are moved in opposite directions along this table and successively cut into lengths .by lsaws 35, the lengths being then delivered by run-out tables 36 to skidbeds 31 on which the lengths are collected in batches for removal by crane. A further alternative in the disposition and processing of the cold-rolled bars may be aiorded by providing a flying shear 38 at the entry end of the run-out table 21 which is effective to shear the bars immediately to commercial lengths after which the latter pass along Ithe table 21 to a run-out table 39 for delivery to a cradle 40.

The principal advantage of the invention as described above is that one or more continuous cold mills such as shown in Figure 6 can be located at any convenient point, regardless of its relation to the hot mill, since the coiled hotrolled blank may easily be transported, after cooling and pickling, .to the location of the cold mill. The hot mill, furthermore, may be employed as desired for rolling straight bars for delivery to a cooling ,bed and at other times the hot-rolled product may be coiled for nal reduction by cold-rolling, as described herein. It will be understood, of course, that the sections of bars delivered to the cooling bed as hot-rolled will p dier from those of the blanks to be further reduced by cold-rolling. By virtue of this invention, therefore, it is possible for an existing hot mill to deliver part or all of its capacity to 'any cold mill which may be located without particular regard for the location of the hot mill.

v the operation and increases the output of the hotv mill. At the same time, the whole range of products now finished on the hot mill may be produced by cold-rolling, using only a relatively few While the invention is Alimited to sections that can be coiledwhile hot and started 'When cooled into a cold mill, this includes a Substantial portion of ordinary merchant bars.

The invention is of particular value in meeting demands for a great variety of sizes in small lots. Standardized sizes of coiled blanks may be stored in a coil-storage building and drawn upon as and when required. The amount of cold work imparted to the bar largely determines its physical properties and suitable blanks can thusbe selected to fit particular requirements for properties as well as size of product.

In addition to producing round bars as described above, the invention lends itself to the rolling of bars of other shapes such as squares, flats and angles. Figure 10 shows the section of a startihg blank 4l which I employ for rolling squares. Figures 11 through 14 show the shapes of the passes of the several stands of a. cold mill similar to'that shown in Figure 6, for reducing `blank 4| progressively to a finished square bar 42 which is` accurate in Size and shape within small tolerances. Since the several steps involved in producingthe bar 42 from the blank 4I are substantially the same as those required for rolling of rounds as above described, the details need not be repeated.

Figure 15 similarly shows a section of a blank 43 which I use for production of a nat bar 44 by cold-rolling according to the invention. Figures 16 through 19 show the shapes of the several passes required for this reduction. It will be notedthat the first and last passes (Figures 16 and 19) are defined by plain rolls and the remaining passes by grooved rolls.

Figure 20 shows a blank 45 suited for the coldrolling of an angle 46. Figures 21 through 24 show the shapes of the several passes necessary for this product. The first pass (Figure 21) is effective to bend the legs of the blank into rightleg.

angle relation and reduce their thickness, without affecting the length of the legs; The second pass' (Figure 22) eilects a reduction in the length ated that my method of cold-rolling the blank at Figure 20 to produce an angle involves the successive upsetting of the legs of the blank after bending them to the proper angular relation and a nal reduction in the thickness of the legs to finished dimensions.

The advantages of the invention previously pointed out in connection with the rolling of rounds are obviously also obtained in the production of `other shapes such as squares, flats andk angles. In the coiling of the blanks 4I for squares, the hot-rolled blank may twist slightly until one side or the other engages the mandrel of the coiler or previous vturns but, in the case of squares, this degree of twist is not detrimental to the subsequent cold-rolling operation. Angles are coiled as ribbons with their apexes on the outside of the coil. 'Ifhe legs of the blank 45 may spread slightly on coiling but this is fully corrected by the first stand of the cold mill and does not materially hamper entry of the blank therederstood that changes in the apparatus and procedure herein disclosed may be made lwithout. de-

parting from the spirit oi the invention or the scope of the appended claim.

Iclaim: In a, methodl ,of rolling angles, the steps including ceiling a. hot-rolled blank V-shaped in` section while substantially at rolling temperature, and with the' blank disposed substantially in the position of minimum resistance to bending, uncoiling the blank after it has cooled subnished value.

of the legs one at a time in separate Passes and finally reducing the thickness of the legs to its GUsTAF L. FISK. y

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