US2593460A - Method of producing metal sheets - Google Patents

Description

A ril 22, 1952 w. c. JOHNSON 2,593,460 1 METHOD OF PRODUCING METAL SHEETS OR PLATES Filed Aug. 2, 1946 v 2 SHEETS--SHEET 2 Patented Apr. 22, 1952 METHOD OF PRODUCING METAL SHEETS OR PLATES Wallace 0. Johnson, St. Davids, Pa. Application August 2, 1946, Serial No. 687,904

Claims. (Cl. 2919) This invention relates to metal working, and more particularly to the formation of metal sheets or plates by pack rolling. Whilethe invention is directed particularly to the formation of steel sheets or plates, it is applicable generally to metals or alloys from which ingots may be formed. I

The pack rolling principle, i. e. the simultaneous rolling of a plurality of metal members arranged-in a stack or pack has been used to roll thin steel sheets from rectangular sheet bars generally not over one inch thick. As these bars are spread by hot rolling, they are arranged in packs and as these packs are further reduced in thickness they are folded over to combine four and finally eight sheets. The total reduction in thickness is relatively light and the rolling temperature is kept below 2000 F. so that the individual sheets will not weld together. Sticking together is also prevented by the thin coating of iron oxide which forms on the surface as thehot sheets are individually exposed to the air.

When sheets and light plates are rolled from slabs (generally at least 4" thick) the temperature must be raised because of the increased mass and greater amount of reduction desired. This prevents the rolling of slabs from packs because the individual plates so rolled would weld together. Also because of their greater size and weight, it is not feasible to hot double such large sheets nor is it practical to reheat them to keep the mass at the required higher rolling temperature.

;'However, in the restricted field of clad steel plates and sheets, slabs are assembled into packs termed sandwiches with plates of nickel or stainless steel inserted between the slabs. These packs consisting of steel slabs and nickel or other rust proof plates are rolled together at high'te'mperatures so that the rust proof plates are welded to their respective slabs and yet are prevented from welding to each other by a coating of parting compound as described in my U. S. Patent #l,886,615. The reason for rolling these in packs is to keep the alloy inserts against their respective slabs without warping and also to prevent them from being chilled by contact with the water cooled rolling mill rolls.

Therefore, while it is old to use the pack rolling principle to roll steel sheets from sheet bars, and also to make clad steel plates from slabs, no one to the best of my knowledge has ever successfully rolled plates 'or sheets direct from packs of rough ingots.

Ihave discovered that it is possible to form sheets or plates directly from rough ingots by the pack rolling method, even though this has.

heretofore seemed impossible due to the relatively great thickness, the cast structure, and the very rough surfaces of ingots. To begin with, a pair of superimposed ingots presents a very thick body or mass, since the average thickness of a single ingot is about ten inches. Then, too, an ingot has a dendritic structure due to the fact that it is a raw casting. Therefore the rolling of a pair of ingots requires high initial rolling temperature which is all the more conducive to welding adhesion. Further still, the rough and irregular surfaces of an ingot, as cast, makes it all the .more diilicult to prevent welding adhesion and to provide smooth surfaces on the inner faces of a pair of superposed ingots when rolled into plates or sheets.

Notwithstanding these factors, I have found that plates and sheets can be produced directly from rough ingots by pack rolling, it being thus possible to produce plates and sheets of much greater area than has been possible in the past.

One object of the present invention is the provision of a novel method of forming metal sheets abrasive which exercises a hot grinding and pol ishing effect on the confronting faces of the ingots as they are rolled, thus providing a smooth commercial finish on the saidfaces of the finished plates.

Another object of this invention is to enable a plate mill to roll light plates to greater widths and longer lengths than was previously possible; also to enable a plate mill to produce thin sheets direct from ingots which heretofore has not been possible. For example, an order for 1000 plates x 60" x A thick, that would normally be rolled from 84 single ingots each weighing 4000#, can be rolled from only 28 ingot packs each weighing 12,800# because the mill can roll them to thick in wider multiple widths and longer multiple lengths than is possible at A" thick.

Other objects and features of the invention will be apparent from the following detailed desmooth as desired as they are being rolled into plates or sheets.

Following the formation of the ingot pack, as shown in Fig. 1, it is heated to a suitable temperature for hot rolling, e. g. 2300 F., and itis then rolled until the desired individual sheet or plate thickness is attained. Fig. shows the pack at an intermediate stage of the rolling operation. After the rolling is completed, the sheets or plates are separated by shearing normal amounts of end and side scrap which removes all weld metal holding the sheets together.

Figs. 6 and '7 illustrate the character of the opposite faces of a finished sheet formed in accordance with the present invention and employing .a parting compound of the character above mentioned. The illustrations of these figures were taken from an actual sample and are truly representative of the character of the surfaces produced. The surface I5 shown in Fig. 6 is the outer surface of the sheet which was engaged by the rolls during the hot rolling operation, while the surface I6 shown in Fig. 7 is the inner surface which was engaged by the parting compound. While the surface [5 is much smoother than the extremely rough surfaceof the ingot from which the sheet was formed, it is not nearly as smooth as the surface I6 which requires no treatment, such as pickling or sand blasting, by the fabricator. This smooth surface is produced by the hot grinding and polishing action of the combined parting compound as previously mentioned. The sample fromwhich the illustrations of Figs. 6 and 7 were taken is a steel sheet which was produced by ingot pack rolling employing the magnesium oxide parting compound above mentioned.

While magnesium oxide is very satisfactory as a parting compound, it leaves a white chalky color on the inner surfaces of the rolled sheets or plates, and there is therefore a substantial contrast in color between these surfaces and the bluish-black color of the outer surfaces. It has been found that finely divided chrome ore is equally satisfactory when employed as the parting compound, and yet gives a dark brown surface after rolling, thus avoiding any objectionable contrast. Furthermore, it has been found that sheets or plates which are rolled with chrome ore as the parting compound have a thin adhering coating of chrome oxide which is rust-resisting. This is desirable in that it protects the plates or sheetsfrom rusting during transit and during preliminary fabrication before painting. Moreover, it also furnishes a scale-free surface to which paint will more permanently adhere. This adhering coating of chrome oxide to a steel sheet or plate also protects the steel against excessive oxidation such as occurs during heating for flanging, dishing, forging, etc.

Further, in connectionwith the parting compound employed in the practice of the present method, it has been determined that the relative hardness of the compound at the rolling temperature has a great deal to do with the smoothness of the finished plate or sheet surface. Since the invention is primarily concerned with the rolling of steel plates or sheets, and the rolling is preferably done at a temperature starting at 2200-2500 F. and finishing at 1400-1800 F., the relative hardness of the parting compound within the overall temperature range indicated is important. The high starting temperature of 2200-2500 F. is sufficiently high to permit the desired pack rolling and is also sufficiently high to effect the chemical reaction between the parting material and the metallic oxide usually present on the confronting faces of the ingots. Best results are obtained if the parting compound is slightly plastic, and is neither too plastic nor too hard, at the final rolling temperature. If the parting compound is too plastic, it will cause the plates or sheets to stick together, making it difficult or impossible to part them. On the other hand, if the parting compound is too hard, it leaves the surfaces of the plates or sheets undesirably rough. The specific compounds mentioned above have been found to have the desired characteristics for rolling steel plates or sheets in accordance with the invention.

The invention is not limited to the rolling of plates or sheets of uniform thickness but may be applied to the rolling of plates or sheets of varying thickness. Thus, the invention may be applied to the rolling of tapered plates or sheets as illustrated in Figs. 8 to 11. In such case, the rough ingots may be cast in shapes which will give the desired varying thickness of the plates or sheets after rolling. In Fig. 8, there is shown an assembled pack comprising a pair of tapered ingots I! and I8 and a parting sheet l9 therebetween. The ingots are arranged so that the assembled pack is in the form of a parallelopiped. I

Fig. 9 is a cross-sectional view of the assembled pack. The compressible weld dams previously mentioned are shown at 20, and the weld metal is indicated at 2 I.

Fig. 10 shows the pack after it has been subjected to some rolling, while Fig. 11 shows one of the finished tapered plates or sheets.

While it is preferred to use a composite parting sheet as hereinbefore described, the general method contemplated by the present invention may be performed in some instances by applying the parting compound as a thick paint to the rough surfaces of one or both of the ingots which are to be brought into confronting relationship. Therefore, the general method of the invention is not limited to the use of a composite parting sheet. The invention contemplates broadly-the pack rolling of rough ingots, employing a parting compound which is not only effective to prevent welding adhesion of the ingots but also exercises a hot grinding and polishing action on the confronting faces of the ingots during the hot rolling operation. The invention further contemplates the use of a parting compound which imparts the desired dark brown or black color to the inner faces of the pack-rolled plates or sheets.

I claim:

1. The method of producing metal plates or sheets from relatively rough and thick members such as ingots, which comprises: assembling a plurality of said members in a pack for rolling in which the confronting faces of the members are separated by a parting compound which will prevent welding adhesion of said confronting faces and which will chemically react at high rolling temperatures with the metallic oxide usually present on said confronting faces to form an abrasive; heating the pack to a high temperature sufficient to permit hot rolling of the pack and'to effect the chemical reaction between the parting compound and the metallic oxide to form the abrasive; rolling the highly heated pack to reduce the members to the desired plate or sheet thickness, the abrasive between the confronting faces of said members being moved relative to saidfeonfrontingifaces during 'such mnmg to er-K fect a grindingand polishingaction thereon; and separating the formed plates or sheets from'the wh w V- y 2. The" method according "to claim 1, wherein said parting'compound is magnesium oxide. N

,3, The method according to claim 1, wherein saidfparting compound isfchrorne ore.

The method of producing metal plates or sheets? which comprises assembling a pair of roughingots inan edge welded pack with a part-' ing material therebetween'consisting of a base; sheet fhavingfsuflicient flexibility to conform it self to 'thejrough confronting faces'ofthe ingots and a partin'g 'm;ateria1 carried on saidbase sheet, saidjiparting material preventing welding adhe'sion of said'confronting faces and chemically reacting at rolling temperatures of the order of 22 0( 25 00 F, with the metallic oxide usually prs'entfon fsa'id confronting faces to form an abrasive; heating the pack'at a temperat'ure'of the order of 2200-2500 F. to permit hot rolling of the pack and to effect the chemical reaction between theparting compound and the metallic oxide 'to'form the'abrasive; rolling the heated packftdreduce the'ingots to the desired plateor sheet thickness, the abrasive between the' confronting faces of said ingots being moved relative to said confronting faces during such rolling to'fefiectagrindingand polishing action thereon; and shearing the edges of the pack to separ'ate the formed plates or sheets.

5, The method of producing tapered mean plates or sheets which comprises: forming relatively 'roughand thick tapered memberasuch as ingots, capable of assembly in a parallelopiped the metallic oxide to form the'abrasivej rolling" the highly"heated pack to reduce the members to "the desired plate or'sheet thickness, the abrasive between the confronting faces of said members being moved 'relativeto said confronting faces during such rolling to'effect a grinding and polishing action thereonyand separating the formedpl'ates or sheets'from the pack.

WALLACE C. JOHNSON.

I REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 321,693 Craig July 7, 1885 440,866? Meyer NOV. 18, 1890 632,879 Norton Sept; 12, 1899 1,886,615 Johnson Nov. 8,. 1932 1,926,320 Trembour Sept.12,;1933 1,950,871 Trembour Mar. 13, 1934 1,955,547 Ingersoll Apr. 17, 1934 2,008,880 Stoops July 23,1935 2,159,043" Orr May 23; 1939 April 22, 1952 F. B. JONES 2,593,461

ARTIFICIAL CASTING LURE Filed Sept. 15, 1947 2 SHEETS-SHEET l INVENTOR. Frank B. Jones HRNEYS

Images