페이지 이미지
PDF
ePub

pig-iron of suitable quality into bars of malleable iron : to convert these bars into blistered steel, broken into fragments, in close crucibles, and to pour the fluid steel into iron moulds. “The expense attending these different processes is enormous. If the cost of pig-iron of a quality suitable for good steel be of S a ton, the cost of cast steel, in ingots, made from such pig-iron, by the usual process, will amount to upwards of £30, or four times the cost of the pig iron. I have discovered a process by which the conversion of pig into bar iron, of bar iron into blistered steel, and the use of crucibles for melting the blistered steel, may be dispensed with, and cast steel may be manufactured at a cost far below that of the old process. “This is done by melting together a mixture of pig-iron ar.d malleable iron in such proportions that the fluid mass arising from the mixture shall contain just that amount of carbon which, when combined with iron, forms steel. “The process I now use is described as follows: The pig-iron to be converted into steel may be melted in a cupola, or it may be run direct from a blast furnace used for smelting iron ore ; but the most suitable apparatus I consider to be a common cupola surnace, blown with hot air, in order that the metal, when run from it, may retain its highest possible temperature. The fluid pig-iron shall be run from a cupola or other furnace into a receptacle, made of any material capable of withstanding an intense heat, similar in form to a common refinery, or to the shallow well of a reverberatory furnace for melting pig-iron, and, the quantity of fluid pig-iron used for one operation should occupy about one-third, or thereabouts, of the capacity of the receptacle. The interior of this receptacle and its contents should be kept at the highest temperature that can be produced; and I find a very ready and convenient method of producing this high temperature to be by currents of ignited carbonic oxide gas, conveyed through pipes placed round the top of the receptacle, slightly inclined downwards, so as to bear upon the surface of the fluid metal. A sufficient temperature for this purpose may also be produced by a current of oxyhydrogen gas, produced by directing a stream of atmospheric air into a current of hydrogen gas, formed from the decomposition of water allowed to trickle upon malleable iron brought to a high heat. In order to burn the carbonic oxide, it is necessary to introduce along with it a current of hot atmospheric air; or, if a more intense heat is required, a current of oxygen gas. In either case, however, care must be taken that the proportion of atmospheric air, or of oxygen gas, does not exceed that which is required to convert the carbonic oxide into carbonic acid, as any excess of oxygen in the blast would have a most injurious effect upon the melted metal in the receptacle. “The carbonic oxide may be obtained from the waste gas from the cupola employed to melt the pig-iron, or from a blast furnace, or it may be generated in a separate apparatus by the imperfect combustion of any fuel; and the application of it may be in any of the numerous and well known methods already in use. The proportion of hot atmospheric air, or of oxygen gas necessary to form carbonic acid, may be exactly regulated by means of stop cocks or valves in the pipes by which the hot air or oxy-, gen gas is conveyed into the streams of carbonic oxide. “In order to decarburate the fluid pig-iron in the receptacle to the deGree necessary to form steel, I mix with it a certain portion of malleable

iron, more or less, as I wish to make steel softer or harder; but for cast steel of a medium degree of hardness, such as is used for general purposes, I find that about equal proportions of pig and malleable iron answer best, The proportions in which the pig and malleable iron should be mixed, however, will much depend upon the quality of the former. If gray pig iron is used, it will require more malleable iron to be mixed with it than if white pig-iron is used. This is a point, the exact determination of which can only be arrived at by testing the quality of the mixed fluid metal in the receptacle at intervals. “'The malleable iron to be mixed with the fluid pig-iron in the receptacle may be in scraps, or in any convenient form ; but by far the most economical, convenient, and purest state in which the malleable iron can be used is in the granular form, produced by reducing any perfectly pure oxide of iron to small fragments, and then submitting them to the well known process of cementation in a common converting furnace, such as is used for converting bar iron into blistered steel. The iron ore in small fragments is mixed with just that proportion of carbonaceous matter which is sufficient to combine with its oxygen at a red heat in a close vessel ; and when the process is finished, the malleable iron is obtained in the purest possible state. “Before adding the malleable iron to the fluid pig-iron, the former must be brought to a white heat, and this may be done in a separate furnace; but I find the most convenient method is to place the malleable iron on a bed between the receptacle which holds the fluid pig-iron and the chimney up which the waste heat from the combustion of the gas passes. The malleable iron, when at a white heat, is raked into the receptacle containing the fluid pig-iron, and the whole is kept in fusion and stirred about for a sufficient time to produce intimate mixture and uniformity of composition into the fluid mass ; and when the assays taken from it show that the steel is of the desired quality, the contents of the receptacle are run off into moulds of any form or size required.” Founding.—Three patents have been granted this year for improvements in founding, one of which I will describe. This patent is for improvements in patterns for making moulds. It will be readily understood that when a great number of small articles are to be cast of various shapes, the operation of moulding would be much facilitated by uniting the pat: terns in groups, in such a manner that many may be moulded and cast at the same time. This advantage has already been attained, where the patterns possessed that kind of symmetry which would allow them to be imbedded in wood, plaster, &c., having a general plane surface. But many of these small articles are of such form that but one or two could be thus connected with a plane surface without destroying the mould in drawing the pattern, and such articles are obliged, therefore, to be cast in the old way, by themselves. To obviate this difficulty, and to extend the benefits result. ing from grouping to almost every variety of casting, the patentee resorts to the following process for making his patterns. He fills a flask with soft plaster of Paris, or some similar substance, and imbeds the patterns in it, in such a position that if the plaster were removed from the upper surface of them, and the whole group applied to a flask of sand, the whole would draw. He then allows the plaster to dry, and removes all that lies upon the tops of the patterns, so that each one will draw from the plaster in a direction perpendicular to the bottom of the flask, care being taken to cut

waway the plaster in such a manner that its various points will draw, which ois easily done. The various patterns will then be found, with the remaining portion of the plaster, to present an irregularly curved surface, the whole of which will draw. Another flask, corresponding with the first, is then filled with soft plaster, and placed over the first, which contains the patterns; and when the plaster becomes hard, this flask, with its plaster, is removed, leaving the first flask of patterns as it was. It will be obvious that each of the patterns in the first flask has formed a cavity in the plaster of the second flask; and in each of these cavities a duplicate patterm is firmly placed, and the second group of patterns is completed. Oil, or some other substance, is used to prevent sticking, &c. To obtain the mould for the group, a flask of sand is rammed upon the first flask of patterns, and they are drawn. . Another flask of sand is then similarly applied to the second flask of patterns, and they are drawn. The passages for the admission of the melted metal are made in any convenient way; and placing the two sand flasks together, the group of moulds is complete for casting. The flasks containing plaster and patterns are retained as permanent patterns for any desired number of moulds. The principle is }. of very extensive application, and promises great advantage to the Ollinoler. A particular review of the other two patents for improvements in founding is deemed unnecessary. The art has already attained a high degree of perfection. , Tempering.——One patent has been granted for improvements in treating edged tools for tempering. The edges of these tools being much thinner than the backs and other parts, if they are at once placed in a fire suitable for giving the proper heat without loss of time, the different parts will not be equally heated, and the edge may be injured before other parts have received the proper degree of heat, and other inconveniences may arise very prejudicial to the success of a process so nice. These inconveniences have been felt, and means resorted to to obviate them. The plan adopted by the patentee is to place a rack at some distance above the tempering fire, which will hold a considerable number of the tools to be tempered ; which rack is filled with them, and they are heated slowly by the tempering fire. When they are considerably heated, they are taken one by one from the rack, applied to the tempering fire, and heated to the proper degree for tempering. As each is removed from the rack to the tempering fire, another is substituted in its place, so that a sufficient number is constantly undergoing the preparatory operation. Letters patent have been granted for improvements in machinery for rolling hoop iron, which consists principally in returning the rod to the operative, to undergo further rolling, without the intervention of another workman. - - A patent has also been granted for feeding furnaces by a plunger; for giving form to various parts of ploughs, by dies and gauges; and another for a saw-dressing machine; which it is not necessary to describe. They will be understood by referring to the list of claims. Files.—A patent has been granted this year for an improvement in round or rat-tail files. These, like other files, have heretofore been generally cut by chisels, from which mode of cutting certain irregularities result, which it is the object of the patentee to avoid, and also to facilitate the operation of cutting. The patentee produces his file by cutting upon its surface, from

d

point to shank, right and left hand screws. The threads of each screw are intersected by the groove between the threads of the other in such a manner as to form teeth of equal length, and at proper intervals. Letters patent have also been granted for improvements in machinery for cutting flat files, which is intended to obviate the mischief which results from the unequal hardness of the blank at different points. The blow of the hammer in file-cutting has never been made to vary with the varying hardness of the blank; and it is impossible, perhaps, to give it this variation. The object of the inventor, therefore, is to obviate the evils which result from this and some other disficulties which seem incident to file-cutting by machinery. The following extract from the patent will present the nature of the invention as clearly as can well be done without drawings: - “In driving machinery for cutting files a difficulty hitherto insurmountable has been experienced, which results from the variation in the hardness or density of the metal at different points of the ‘blank” to be wrought upon ; or, to state the difficulty more practically and specifically, when the piece of metal or “blank” is softer in some points than others, the chisel will cut deeper in such points; and as the secding motion is regular, the chisel at its next descent will strike in the groove previously made, and merely widen said groove, without forming another tooth. The serious difficulty has also been met with in accommodating the chisel edge to the “wind' (so termed) of the blank, or the impersection of its surface. “These difficulties are avoided and surmounted by my improvements, my machine being so arranged as to imitate or perform automatically, as it were, the manual process which is now in vogue for cutting files, and which consists in placing the chisel edge in advance of a tooth which has been formed, and on the smooth part of the blank, and drawing it back until the operative feels the said tooth ; when the idow is immediately given with a heavy hammer, which forms the succeeding tooth and its adjacent groove. In my machine this function is effected by so arranging the chisel that for each groove and tooth its cutting edge is made to reach out and slide back, in a manner substantially analogous to the manual process above specified, the movements of the chisel being produced by mechanism which will be explained in the sequel. “I now come to those parts of the machine which embrace my improvements, and I shall proceed to show their distinguishing characteristics—these parts having relation, to the method of sustaining and operating the chisel. In many or most of the file-cutting machines which have hitherto been invented, so far as I am insormed of their construction and operation, the chisel has been held firmly either in the hammer or striker, or in a vibrating arm under the same, and the blank has been drawn along under the edge of the chisel by any proper and regular feed motion, so as to present it at proper points to be cut by the chisel at the successive blows of the hammer. Both of these modes of arrangement, for the reason hereinbefore stated of the varying hardness of the ‘blank,’ have been found inadequate and unsuccessful in forming good or perfect files. - “The chisel is arranged so as to move up and down, and shift its position in the rectangular slot of the chisel frame, being guided and actuated in its movements by the long bent spring in front—the vertical bent spring in its rear; the horizontal bent spring having a button fixed at its end, said button bearing against the rear force of the chisel near its top, and the wedge-shaped stud or projection standing on the front face of the chisel near its top, and also the front face or lip of the chisel frame. The bent spring performs one of the most essential functions, in operating the chisel in a manner similar to the manual process herein above suggested, which function is pulling the chisel out after each.blow of the hammer in front of a tooth previously formed, preparatory to its being drawn or pressed back by the lip, as hereinafter explained, against the same, for the formation of a succeeding groove and tooth. The upper end of this spring is confined to the projection from the top of the chisel frame, while the lower end passes through a slot in the lip or front piece of said frame, and through, a hole in the chisel (where it assumes or has the shape and office of a pivot or pin for the support of said chisel) to the rear side of the same, where it is bent down in such a manner as to tend to hold the chisel against the inner face of the lip, and also to press said chisel down. By this arrangement of the parts above described, it will be seen that when the chisel frame is in the process of rising, (which process will be explained in the sequel,) the chisel will not begin to rise until the top of the lip of the frame reaches the stud; accordingly, the lip moving first, and the feed motion continuing, the front face of the chisel will have a tendency to be separated a little from the lip; but when the chisel does begin to rise, and is raised out of the groove and free of the tooth just formed, the spring will pull the edge of the chisel forward against the lip and in front of such tooth. This will give the chisel a position in which its front face will form an angle more obtuse with the remaining plain face of the blank than before; the wedge-shaped stud assisting in this operation of throwing or moving the chisel-edge forward. But when the said frame descends again, the chisel-edge will first come in contact with the face of the blank; and as the frame continues after this to descend, its lip or front piece will press the chisei-edge back until it comes against the tooth last formed, while at the same time the spring, by pressing its button against the rear of the chisel, will bring the front face of said chisel to a fair bearing against the inner face of the lip ; and then the chisel will be in a proper position for the blow of the hammer, and the formation of another tooth. The back spring is intended to assist in #. and steadying the chisel in its movements; though it might e perhaps entirely dispensed with, without materially affecting the operation of the machine. “The chisel frame is supported in the forked ends of the swivel frame, by means of the journals on the sides of said chisel frame, and the confining nuts on said journals. This swivel frame turns on a proper hinge or pin in the end of the vibrating lever or arm; and by turning this swivel frame round on the pin to various positions, the teeth may be cut on the ‘blank,’ either straight across or in oblique lines. The vibrating lever or chisei-arm, as I shall term it, turns on a proper fulcrum or pin, in the up:ight frame piece, which piece is fitted in an elongated slot, cut through the rocker shaft; being confined in any position in said slot by a binding screw. The rear end of the chisel-arm is connected, by means of an arm, (which turns. freely on a pin fitted in said end,) to an arm or lever arranged in the elongated slot in the shaft, which I denominate the chisel-actuating-shaft; this arrangement of the arms being such as to form an L joint, as it were,

w **

« 이전계속 »