(For a more com plete description of the Murton mill, see Engineering, October 17, 1S90.) Rolling Fluid Jlctal info Thin Sheets.— In 1846 Sir Henry Bessemer made some experiments on the manufacture of con tinuous sheets of glass, by passing the semi fluid glass from a bath between a pair of rolls. On one occasion a sheet of glass 70 ft. long and 80 in. wide was produced, but the method was never brought into practical use. Ten years later, by somewhat similar means, he produced a sheet of iron. 3 or 4 ft. in length and in. thick, pouring the liquid metal onto a pair of rolls. He then obtained a patent on the process, but no commercial results followed. Experiments have recently been made in the United States on the same process. with such a degree of success that it has already been introduced as a eommercial process. In 1891, forty-five years after his original experiments with glass, Sir Henry Bessemer read a paper before the Iron and Steel Institute of Great Britain, describing his proposed methods of remedying the defects of his first apparatus. From this paper (see Engineenng, October 9, 1E91), we abstract the following : The rolls, L and if, Fig. 9. consist. of two hollow drums through which a tubular steel axis, NN, passes, and conveys a plentiful supply of water for keeping the rolls cool. The brasses which support the roll, 11, are fixed, while those which support the roll, L, are movable in a suitable slide, and are pressed on by a small hydraulic ram. which is in free and uninterrupted communication with an accumulator, so that at any time should the feed of metal be in excess, the roll, L, will move back and prevent any undue strain in the machinery, the only result being a slightly increased thickness at that part of the sheet of metal, a defect which, as it extends parallel across the whole width of the sheet, will be easily corrected in the next rolling operation. The rolls by preference may be made 3 ft. or 4 ft. in diameter, each having a flange on one end only, and thus form a trough with closed ends for containing the fluid metal. In order to obtain u regular and quiet supply of metal, 1 employ a small iron box or reservoir, Fig. 10, lined with plutnbago or along the bot tom of this reservoir some 10 or 20 small holes of about in. in diameter are neatly molded by a row of conical brass _pegs. The reservoir is provided with a long bar or handle at each end. By means of these bars the reservoir is supported on the side frames, the bars falling into suitable notches made in the roll frame for that purpose. A pair of rails. Q, are supported on the roll frames, and serve for the conveyance of the ladle, le, which is mounted on wheels, and brings the natal direct to the roils, or to any number of pairs of rolls that may be placed in line. The ladle is provided with one or more valves or stoppers of the usual kind, by means of which the supply of metal to the reservoir, I', may be easily regulated ; the several small streams from the reservoir will deliver an almost constant quantity of metal, varying only slightly as the operator regulates the head of metal in the reservoir. From the smallness of the head of metal in the reservoir the several streams will fall quietly without splashing. These streams do not fall direct onto the rolls, but into a small pool formed between the thin films solidifying against the cold surface of the rolls, the metal at all times being free from floating slags. The speed of the rolls also affords a means of regulating the quantity of metal retained between them.; and its a pair of 4-ft. rolls would only require to mako about four revolutions per minute. a quick-running engine could easily be provided with differential speed gearing, so as instantly to alter the speed of the rolls to the very small extent ever required during the rolling process.
The thin sheet of metal, as it emerges from the under side of the rolls, is received between the curved guide plates, S and T. to the latter of which a cutting blade. U, is bolted, Beneath the guide plate. S, a similar cutting blade is arranged to denly move forward by a cam and cut the thin sheet in two, the piece so cut afterward passing between the second pair of rolls. I" 1", from which it again descends by gravity, and passes between the third pair of rolls, 11' W, and is delivered onto a horizontal table : or it may be allowed to slide down the inclined end of a cistern of water, and moved slowly forward. By these means it will be possible to cool and stack a ton of plates without any labor or trouble. The thickness of plates capable of being produced will much depend on the size of the mills ; if drums of 10 ft. or 12 ft. in diameter are employed, it is probable that plates of hi. in thickness could be produced, or, perhaps, even thicker. The central space between drums of such large diameter would represent a sort of plate ingot mold with nearly parallel sides for some 8 in. or 10 in. in depth. With reference to speed of produc tion, let us assume the mill to be fitted with a pair of 4 ft. diameter rolls. 18 in. wide. and making four revolutions per minute, and set to produce a sheet having an initial thickness of in., and rolled by the third pair to in. ; we should thus have a surface velocity of the first pair of rolls equal to 50 ft. per minute, and making, when finished, 100 plates 18 in, by 12 in., in. thick, and weighing 060 pounds, or equal to a production of one ton of plates in seven and a half minutes. Hence it becomes a question which is the least costly mode of dealing with a ladleful of fluid steel, forming it into massive ingots in molds, or making it into thin sheets in the manner proposed.
It appears from Sir henry Bessemer's paper, above quoted, that he did nothing to develop the process after his experiments in 1856 for over thirty years, nor until he had learned that success had been reached in America in the same direction. Illeanwhile, Mr. Edwin .Norton,
vice-president of Norton Brothers. incorporated, of Chicago, manufacturers of tin-plate and tinware (see the presidential address of Robert W. Hunt, before the American Society of Me chanical Engineers in November, 1891), had been experimenting for some years on the process, and in conjunction with Mr. J. G. Hodgson, had obtained various American and foreign patents. (Apparatus for making sheet metal, Nos. 882,319 and 382.321, May 8, 1888; No. 406.945. July 16, 1889. Apparatus for manufacturing railroad rails, No. 406.044, same date. Manufacture of metal bars or rails, No. 406.946, same date.) As sheet rolling mills under these patents are now working commercially at Whitestone, Long Island, N. Y.; Chicago, Ill.; and San Francisco, Cal., it appears that to Mr. Norton is due the credit of the successful introduction of the process of rolling sheets, bars, etc., from fluid metal, the first experiments on which were made over forty years before by Mr. Bessemer, just as Mr. Bessemer is entitled to the credit of the successful introduction of the Bessemer process. although William Kelly, an American, had experimented with and obtained patents upon it before Bessemer.
We illustrate herewith the process patented by Messrs. Norton and Hodgson for rolling rails and shapes. The underlying principle is to subject the molten metal to pressure between rolls, the conformation of the first rolls being such as to compress the flowing metal into very nearly the shape of the finished form ; subsequent rolling is continuous, and in a direction to bring to exact size. and to further compress the metal ; also the speed of the rolls is such as to pre. vent damming of the metal ; that is, the speed is such as to provide for a continuous stream of practically a constant cross-section. It will be understood that there is very slight press ure on the initial rolls ; these rolls are kept cool by interior water circulation. In the engravings, Fig. 11 is a plan view of the apparatus devised, and Figs. 12, 13, and 14 are, respectively, a central horizontal section through the axes of the rolls, a vertical sec tion on 3,3. of Fig. 11, and a side elevation partly in section. The first rolls—in this instance four in number—are formed at their peripheries so as to present a space between them similar to the section of an ordinary rail. Directly over these rolls the molten metal passes to the rolls through the spout or channel. The following description is taken from the patent specifications : As indicated in Figs. 11, 12, 13, and 14 of the drawings, the working or meeting faces or peripheries of the rolls, B, are given a shape or configuration to form an ordinary railroad rail. They may, however, be shaped to give the space or passage, b, any desired cross-section, and thus produce a bar of any form required. The rolls, B, have beveled faces, b , which meet or roll against each other, and serve as stops for the several rolls against each other, so that the space or passage, b, for the metal will always be maintained of a uniform size, and thus produce the rail or bar of a uniform cross-section throughout. The rolls, B, are each made hollow, and preferably with a central web, , and the shafts, IP, are also made hollow, so that the water or other cooling fluid or liquid may be made to circulate through each of the rolls for the purpose of keeping them cool or of the desired temperature. The hollow shafts, are each furnished with a packing or stuffing-box. d, at each end, by which they are connected with the inlet and outlet water pipes. D If. The pouring bowl or vessel, C, is supported by-any suitable means above the rolls, B, during the pouring, operation, preferably by standards, a, furnished with adjusting screws, C". The pouring nozzle, C, is preferably furnished with a valve or device, c, for opening and closing the discharge passage. The hollow shafts, IP, of the rolls are all geared together, so Iliat they revolve or roll together at the same surface speed. The gearing employed may preferably be bevel gears, such as indicated at Two of the shafts, IF, are also geared together by spur gears, B'. E is the driving shaft, having a gear, which meshes with a gear, J. on one of the shafts, IP.
The pouring bowl or nozzle, is furnished with a guide or shield, extending down to near the meeting point of the rolls, This is designed to prevent the metal from splattering at the beginning of the pouring operation. A greater or less number of rolls than four may be employed. represents a second series of rolls, arranged preferably directly below the chilling rolls, and between which the bar, .r, passes ns it issues front the chilling rolls, B.
The series of rolls, F, are preferably of the same form construction as the rolls, B, being hollow and having the same connections for passing water through them, so that they may operate as chilling rolls as well as to further roll, compress, and finish the rail or bar pro duced. The rolls, I', may, however, be of any ordinary or known construction. The series of rolls. P, is preferably like the series, B, composed of four rolls revolving together. 0 is a curved guide or conveyer, consisting preferably of a series of rolls or idle pulley wheels, arranged in a curved path to curve and guide the bar as it issues from the rolls, 'PT, to Lhe horizontal conveyer or series of rolls, IL Some of the roils, II, are preferably driven and operated to further roll and straighten the rail or bar, as well as to convey it along or away. The curved guide, 0, also affords some slack in the rail or bar between the chilling rolls and rolls, 11 II, to compensate for difference in speed or slipping.
Rope Driving. : see Belts and Cranes.