US37497A - Improvement in founding - Google Patents

Description

I www;

www

N.PETERS. FHOTOLITHOGRAFHEH. WASHINGTON, D C.

ffy/miar- `UtuTEn STATES PATENT GEErcE.

A. H. EMERY, OF NEV YORK, N. Y.

IMPROVEMENT IN FOUNDING.

Specitication forming part of Letters Patent No. 37,497, dated January 27, 1363.

"0 all whom i6 may concern.-

Be it known that l', A. H, EMERY, a civil engineer, of No. 17 Vest Vashington Place, in the city, county, and State of New York, have invented a new and Improved Method of Founding; and I do herebydeclare that the following is a full and exact description thereof, reference being .had to the accompanying drawings, and to theletters of'reference marked thereon, and making a part of this specification.

Like letters repuesent like parts.

rIhe nature of my invention consists in providing means to regulate the cooling of the different parts of castings in such a manner and to such an extent that t-he contraction of the metal in cooling shall not destroy the casting, but in very many cases renderitbeneficial.

In making castings generally of metals, either separately or in combination, it often happens that the form and size is such rthat some parts of the casting cool first, leaving the rest to cool afterward, andthe contraction of these parts cooling last brings ou heavy strains, and produces cavities to such an extent as often to destroy the entire piece. 'lo

avoid this evil I incase, either partially or wholly, those parts of the casting which should cool more slowly than they otherwise would, in an envelope of melted metal heated to a very high degree and separated from the casting by a thin mold.

In the founding of cannon the contraction of the metal has always heretofore proved very injurious. My object is not only to counteract the evil effects of the contraction, but to make such contraction beneficial. In casting the cannon solid, the external portion of the metal cools rst and performs alarge share of its contraction while the inner portion of the mass is still in the fiuid state, and as the inner portion cools and contracts, its particles affixing themselves to the surrounding walls, which have been previously formed by the solidication of the external portion, are caused to recede from the center of the mass, and so produce in the interior of the mass cavities to the amount of the contraction in passing from the liquid to the solid state. As soon as the metal has all assumed the solid state, motion of the particles relatively to each other ceases, but contraction goes on untilthe inner portion of the mass is reduced to the same temperature as the exterior, and the surrounding medium and the excess of contraction of the inner portion over that of the outer produces tensile strains in the inner mass and compressive strains in the outer mass. For the purpose of avoiding these evils some persons have endeavored to cool the gun-casting from the interior by circulating water through a hollow core placed in the center of the mold for that purpose; but this only partially counteracts the evils mentioned, for while the casting is cooling from the interior it is also cooling from the exterior, leaving a portion of the metal between the interior and exterior to cool last, with the same results as in the solid cast gun, though in a less degree.

To enable others skilled in the art to make use of my invention, I will proceed to describe the means by which I accomplish the desired results.

I use, in combination with a hollow core by which the piece is cooled from the' interior, an envelope or casing of melted metal heated to a very high degree, which surrounds the whole or any part or portion of the casting that may be desirable, and is separated from it by a thin mold, thus keeping the exterior of the casting hot, while it is cooled entirely from the interior or to any such extent as may be desirable, thereby causing the contraction of the metal either wholly or to such an extent as may be desirable to take place in an inward direction, by which means the whole mass is made solid and free from pores, and the contraction of the external portion of the metal onto the interior portion serves as a reenforce to that portion. In the case of the exterior cooled gun the strains due to contraction act with those ofthe powder to burst the gun, while in the case of a gun which has been cooled from the interior the strains due to contraction are at the interior surface, where rupi the same in the plane indicated by the line y 1/ inFig. l. Fig. 3 is a vertical section of the mold and envelope ol" metal, indicated by the line z z in Fig. et, which latter is a horizontal section in the plane indicated by the line w 1r in Fig. 3.

A represents the flask divided centrally and vertically, and large enough to contain the central mold, B, in which the piece of ordnance is cast, and the surrounding mold-chamber C, which receives and contains the envelope or casing of molten metal by which the external portion ol the casting in the mold B is kept heated. rFhe mold B, which may be Y of any suitable materials, is made as thin as is 'consistent with proper strength, that it may be easily heated by the molten metal in the surrounding chamber C.

a is the gate for filling the mold B, entering it at the center of the bottom, and having a number of passages, I) b, for conveying the metal thereinto at different elevations. The chamber C is furnished internally with a number of thin flat horizontal annular cores, e c, and vertical radial cores d d. The cores c e c are only connected with its outer walls, and annular openings j" j" are left between them and the exterior ofthe mold B. The said cores d d are alternately connected both with the mold B and the walls of 'the chamber C, the inteavening ones being connected only with the outer walls of the chamber C. By this system of cores the interior of the chamber C is subdivided into a series of smaller chainbers, g g, which communicate with each other, and all of which are in communication with an annular chamber, h, provided under the bottom of the mold B, for the reception of the molten metal poured into the gate t'. From the chamber h the molten metal poured in at the gate i is distributed all through the several subdivisions g g of the chamber C. The object of so subdividing 'this chamber is to provide after the cooling of the metal, mold, and iiask for the breaking1 up of the casting which is obtained in the chamber C, such easting being thus formed into a series of blocks of a suitable size to handle and remelt, and connected only by a thin web, which is easily broken by the hammer.

D is the hollow core-barrel closed at the bottom and open at the top.

E is a smaller pipe arranged within D and extending nearly to the bottom thereof for the purpose of introducing water to expedite the cooling of the casting by its circulation in contact with the interior ofthe core-barrel D. The tubes D and E are usually made of Wrought-iron D, being coated externally with a wash of clay to keep the casting from uniting with it.

F is an overflow-pipe to carry away the water introduced through E after it has been heated by passing in contact with the core barrel D.

In pouring the molten metals in the gates c and @that poured in at the gate fi should be so regulated with that poured in at the gate ay that the metal in the chamber C shall be a few inches higher than that in the mold By so that the heat consumed in heating the mold B shall be'taken from the metal in the chamber C, and not from the casting in the mold B. The height of the metal in the chamber C must not exceed that in the mold B more than a few inches, as the mold Bis very light. The relative height in each can be determined by the use of floats. The metal poured in the chamber O should be made very hot, as it will then require to be of less thickness that if not so much heated; For the same reason the metal in the mold B should not be poured very hot, as the hotter it is the more metal will be required in the chamber C to insure the cooling ofthe casting in the mold B from the interior.

I provide, as in other modes of casting, what is termed a sinking headW-that is to say, make the mold deeper than is required for the length of th`e gun-and thus make the casting extend some distance above the part that is to form the muzzle, the metal in the said extended portion of the casting being intended to supply, while in the fluid state,1netal to the lower part of the casting equal to the contraction in passing from the fluid to the solid state.

That the sinking head may remain lluid as long as possible and thus perform properly itsfunctions I make the upper end of thev corebarrel D with a sleeve, k, made of sand, clay, and plaster-of-paris, either separately or in combination, or of an y other suitable materials, so that it may cool the sinking head as little as possible. This sleeve 7s may be continued down into the chase of the gun to prolong the cooling somewhat of that part and thereby lessen the longitudinal strain, and at the same time assist in longer keeping up the supply of melted metal to the contracting mass below it.

Ido not make the sinking head as deep as is necessary in other processes of casting, .neither do I find 1t necessary to make the casting ior the gun excessively large about the chase o1' the gun as in other processes, where such exv4 cess has to be turned oft1 at great expense, but cast my gun but a little larger than it is when finished; second, in the founding of solid shot and shells either elongated or spherical,when of larger caliber, we find the saine diiiiculties arising from contraction as in the case of guns, and I overcome them'in the same way that ll do in that case. rlhe cavities formed displace the center of gravity ofthe projectile,and thus injure the accuracy of fire, while the cavities and the strains due to contractioinboth weaken the shot and impair its effectiveness in the destruction of fortifications, ships7 armor, &c.

This process of founding projectiles is illustrated in Figs. 5 and 6,which are central sections, at right angles to each other, of a flask containing a mold and casting and the sur rounding envelope of metal. In these figures,

G is the liask; H, the mold, having a very thin Wall, which separates the casting for the projectile from the chamber I, which receives the outer envelope or casing of molten metal, by which the cooling of the shot is retarded. The chamber I is subdivided by numerous thin lat cores,Z Z m m, in the same manner and for the same purpose as Were the cores e c and d r1 in chamber C of the gun-mold. (See Figs. l, 2, 3, and 4.)

m is the gate for the purpose ot' conveying metal into the central mold in which the shot is cast, and n the gate which conveys molten metal to the chamber I.

p is a small hole through the Wall of the mold H, which conveys metal from the chamber I into the mold H as the lmetal in the latter contacts.

K is the hollow core of Wrought-iron, coated externally with clay when used in the shell, but not so coated when used in a casting intended for a solid shot.

L isa tube passing from the core k through the mold H and chamber I and the iiask G, and is coated externally with clay.

M is a tube passing into the core k for the purpose of conveying air, steam, or water into the latter, the pipe L conducting the same away again. Then the shot is cool, the tube L is removed, and the core 7tand the cavity left by the removal of the tube L poured full of molten metal, leaving the project-ile solid. If it is desired to be used as a shell, the core l.: is made larger than otherwise, and may, if desired, be removed, and the cavity is retained.

In all cases of internal cooling the thickness of the exterior casing or envelope will be modified by the rapidity with which We conduct away the heat from the interior, being least when water is circulated through the interior core, and thicker when Water is not so circulated; and in all cases the thickness and heat of the exterior casing of metal should be so regulated in proportion as no't to bring too great strain upon the exterior of the casting of the gun or projectile.

Having thus described my invention,what I claim, and desire to secure by Letters Patent, 1s-

1. The process of retarding the cooling of any part or portion of a casting during the process of founding by means of a casing or envelope of melted metal covering or surround A. H. EMERY.

fitnessesz E. COHEN, M. C. GRIrz-NER.

Images