US5236A - Improvement in casting ordnance - Google Patents

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ing ofthe ball in tiring. J.

UNIT-ED STATES [PATENT ,OFFICEy Trios. J. RODMAN, oFfrI'TTsBURG, PENNSYLVANIA,

IMPRoi/'EMENT INV CASTING ORDNANCE, sbc.

Specification forming part of Letters Patent No. 5,236, dated August 14, 1847..

To" all whom itjitiy ,concern Be it known'that I, THOMAS J.' RD'MAN, of

ing is a full and exact description of the same.

In order more fully to show the object ofthe improvement, Ishall first notice some of the evils which it is'intended to correct, whichare y as follows, viz:

First. It is known that by the ordinary mode of cooling, the exterior of the casting is the first to crystallize, and that crystallization goes. on successively `from the exteriorA toward the center, the interiorpbeing ata temperature con-4 siderably higher than the exterior, from which it results that when the casting is cold itis on a strain,the interior portionsbeing prevented from contractinginto their natural volume by. their attachment to theexterior, and thereby subjected to a force of elongation, while the ex-4 terior portions are subjected` to a force of `compression.

Second. Itis k nownthat the strain produced. on any material (not on astrain at the time o f its application) by aforce acting from the center outward `is inversely as the square of the distance from the center. .-Ihisl prineiple, f acting jointly with the one above, renders the metal very rapidly less ei'ective as' itis farther from the'center; so much so, indeed,that all'over one'calib'erin thickness is ina manner useless, for the interior portions, already un.-

der a force of elongation, are broken befdre the exterior portions are brought into action, the particles being necessarily tornv asunder, in'- stead of being all broken at'the sameilstant.

Third. By the ordinary mode of cooling, .the `interior is the softest portion of the gun, whereas 'i1-.is highly desirable that it should be as, hard as possible,'in order to .resist theballn;`

Fourth. 'When the gun is cooled from the exterior, tlie trunnions are the first partscooled, andas the gun contracts,` in cooli ng,.the part A'below the trunnions becomes suspended byl them, while the metal is still so weak as to be A tion.'

rendered. :porous and permanently;injured' thereby.

- All of the above evils are remediedby cooling from the interior, forby this mode of cool ing the metal is thrown on astrain just the re'- verse. of that produced by the 4old method, which, in combination with the second prin- .ciple above named, will render effective all the metal whichma'y be placed inthe thickness of a gun, which is the main object of this-invenwill ofcourse be the hardest portion of the gun,

the guncnnot ybe' suspended by them while cooling;

particularly to guns of 'large caliber. v

v'To enable others skilled in the art to' use-my invention, I will'p'roceed to describe the'meansand manner of its application. I .make a. hol;

low'ironfcore'barrel elos'ed at the lower endl andopen at the` otherand of sufiicient length' to extend downto within a few inches jofthe bottom of the bore when finished and about'f two feet above the top ofthe flask. v This barrel ismade Water-tight, (when vWater -is used for cooling,).and uted or-grooved longitudi-V na1l-yon theexterior, lfor the purpose ot venting the casting.A .Y The upper end of the barrel' is turned s lightlyconical, s o as to tit snugly into a'socket, of which Figure 3 is a ground view, l ,l

and S, Fig. 1,` a vertical'section.- In that por 'tion of -the' barrel whichnpassesl through and projects above the socket is inserted (watertight) antinduction-pipe; p', Fig. 1. In thel lower end ofi'the 'barrel is a female', screw cut in far enough to Y receive a'jounal, on which .the barrelturn's while being coated withl clay,

but not entirely through the bottom of the bar 'rel.- Having completedthe barrel, I coveriit with a coating of hemp rope (or other suitable material) tightly lapped on fromthe lower end' up as ylrghfas' the metal is. intended to rise.

'The barrel is'then ycovered with a coating of .clayand horse-dung intimately' mixed, then baked and preparedin the same manner as 'the g`un-mo1d.' The barrel thus finished is about an' inch les's, in diameter than the'bore of the gun. Forv casting, the core is held'initsprop-- er position -by having its upper end inserted into the socket above named, where it is firmly secured by keys, as seen at c, Fig. 3, the socket being firmly secured tothe head of the flask by clamps orother suitable means; The sock- The interior, being cooledmost rapidly, Y

The. iinprovementis intended to applymore et is accurately reamed out at the Sametime the portions of its Gains which rest upon the iiask are turned, the head of the ask being also turned. Having secured thecore in po.- sition, (the mold being in the pit,) I insert a pipe, ofwhich 17, Fig. 1, is a longitudinal section, and @Fig-2, a cross-section. This pipe 1sV prevented from sinking below its proper posltion in the barrel by means of a collar or studs attached to it and 'resting on the upper( end of the barrel.

Having secured the Vpipe in position and brought the pit tofthe p roper temperature, (which should never be so high as to impair the strength of the'lask,) I let on the water and fill the core-barrel up until it f begins to ruu' out at the eduction-pipe p', Fig.

1. I then let on the metal and regulate the temperature of the discharged Water by letting on a-grcater or less quantity.A The Water de scends through' the pipe p, Fig. 1, to the boti tom ofthe barrel, and rises up between the pipe and the 'interiorof the core-barrel,A escap'- ing at the pipe p', Fig, `1. l The iiaskI is kept heated by a fire on the grates g, Fig. 1, until the heat is extracted from the casting by the water circulating Within it.

-Now,what I claim as my invention, and desire to secure by Letters' Patent of the United States, isf-` J `fThefcoolinglfr'ol'n the interiorof guns 0'1' other heavy hollow castings intended to resist' a central force by circulating-Within the core a cooling'flnid or gas, in combination with the 'application of artificial heat atthe exterior of the flask to prevent cooling from without.

l THOMAS JQRODMANL Witnesses: y

CHARLES KNAP, Jr., JNO. M; ORELY.

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