US70038A - Improvement in apparatus for casting refractory metals - Google Patents

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MICHAELl SMITH, OF5' PHIIADTELPIIIIA, PENN SYLVANIA.A

Letters PatenfNo. 70,938, dated 0ctoberi22, 1867.

IMPROVEMENT IN APPARATUS PQR GASTLNG REPRAGTORY. METALS.

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- To ALL WHoM 1T MAY eoNeEnn:

Be it known that I, MICHAEL SMITH, of the city and county of Philadelphia, in the'State of Pennsylvania,

have invented a new and useful Improvement in Casting'Refrac-tory Metals.; and I do hereby declare the following .'to be a full, clear, and exact description of the same, reference'hein'g had to the accompanying drawings', which are made part of this specification.

`My invention has for its object the casting of brass and other of the refractory metals, withthe greatest. practical density and freedom from blow-holes, and so`a's to present a perfectly sharp and well-defined fac simile' `-of the original pattern; Vand my invention relates to the class ofdeviees which, for the above objects, einploy mechanical pressure on the molten metal.

Figure is avertical section of an apparatus embodying my invention. Figure 2 is a partiallyseetionalized top yiew thereof. p 1 y Figure 3 is a partially-sectionized perspective view of 'my nest or series of' `moulds detached.

Figures 4 and 5, 6 and 7, show modiiications of my imiention. Similar letters of 'reference indicate corresponding parts of the several figures. i The invention may be applied to one or any number of moulds, but I have selected, for illustration, a series or nest of moulds. A A A (fig. l) area series of moulds formed of baked clay, `in manner hereafter explained,

.adapted to be stacked or piled one above the other, and supported on a slab,B. Oriiiees or cavities C 0,'provided A in said moulds, aEord, in their collective capacity, gates or sprues for the admission of the molten metal from the injecting apparatus to be presently described. Said moulds and slab are confined in a box, D, whose sidesmay beprovided with suitable chinks or orifices for the'cscape of air and gas in the act of casting. An aperture, E, in the top of the box D, in continuation of gate C, servesto admit the metal thereto. V Set-screws F, tapped through the bottom 'ofsaid box, and bearing against the under side ofthe slab, serve to press the series of moulds 4i'nily together and against the top of the box. The box-D is enclosed in an air-tight chest, G,havihg a perforation, H, at the top in line with the" orifices and E. By means of the pipe H and an air-suction pump the air is exhausted from the space between the box D and chest G for the purpose to be explained. The perforation H receives a tube orthimble, I, whose central orilicevforms the channel of` communication for the entering metal. The cylinder J may be easily slipped oil' of the th'imble I u'hentheimetal has become set," andthe employment of said thimble obviates the diieulty of detaching the cylinder from a. superincumbent head of metal,'which diiculty would exist case 'of the formation. of a. shoulder upon said `cylinder at the point of discharge into the lmould. The said thimble I may be divided .longitudinally into two parts, to enable the same to be readily detached frorith'eI metal in the central gate after thecasting is completed. Fitting snugly around andextending upward from the said thimble is a--tubc or cylinder, J, to which is loosely tted a plunger, K, which is linked at L to a lever, M, by means of which the operator is enabled to lift the plunger clear out of the cylinder, or to press thesame downward within the latter. The cylinder J is made of capacity fully exceeding'th'at ofthe moulds, so as to leave a good head of metal within the cylinder after the moulds have beenentirely filled by the pressure exercised on the iluid metal.

The operation is as follows: Take clay, such as used `in the manufacture of' stone-ware, in a dry state,

reduce the same to powder, and sift it through a fine sieve, then meisten the same about as much as sand is moistened for ordinary moulding. The pattern from which the mould is to be taken is then coated with oil, and with .a thin layer of a fine paste of the same Vclay as a facing, and the moistened clay is then applied intmately to every part of it by a strong pressure. This will produce. amould 'more sharp and well defined than can be obtained by the use of gypsum, and much better` calculated to sustain, without giving way, the impact of the rapidly-entering stream of metal injected into the moulds on my plan of operation.

Clay moulds' thus made being liable to warp in theact of drying, I keep them for about twoidays 'in a close box or case, at a temperature of about 10 Fahrenheit, from which evaporation takes place but slowly, and afterwards burn them in the ordinary mann-er for burning pottery. I then take fine white potters' clay, and

thoroughly blend the same'with an equal quantity of 4pulverized plumbago, and moistcn the mixture suiciently lto convert it into a cement or paste, with which I line the cylinder J, the application being made by means of a brush or otherwise. This lining serves several useful purposes. 1t .serves to pack the space between the piston and cylinder, and preventslthe intrusion of molten metal between the tw'o, which intrusion would be liable to rapidly clog the parts and prevent their action. (It should becxplained that the plunger K is larger in diameter than the internal diameter of the lining, and that at every operation the cylinder must be recoated or relincd with the clay and plumbago paste, as such lining is detached from the cylinder J, and pushed in advance of thc plunger K at every forwardmovement of the latter, the effect of which is to close the jointand prevent the intrusion of the metal between the plunger and the side of the cylinder, as above stated. The importance of this detachable packing or lining can scarcely he over-estimated, since it constitutes the only practical means for preventing the molten metal from chilling and adhering to the sides of the cylinder and plunger, and thereby arresting the motion of the plunger and precluding successful operation.) It also serves as a non-conductor, te

conserve the heat of the molten metal and prevent it getting mushy or chilled, and it also serves, by prevent?l ing the direct contact of ythe molten metal, to prevent the distortion of the cylinder.

I then stop the orifice I with a plug or tamp of clay, N, and having secured thc'm'oulds in their places, as ,already explained, I pour'the desirediquantity of molten metal into the cylinder, and' thcn, pressing down tho plunger upon it, I, by that means, break the yplug N, and croate a passagel for .the same into the moulds with such force as to pack the'metal at once closely into the various cavities prepared for it, andlcontinue thc pressure until .the moulds and sprues are entirely filled and are all equally subjected to the desired pressure.

I have selected, to illustrate my invention, the Apreferred type or form thereof, but do not propose to restrict myself thereto, -so long as the same results are obtained by means substantially equivalent; for example, the pressure 4of condensed airor steam may be employed in place of the piston and lever, or I may, for some purposes, employ such modifications as shown in figs. 4 and 5, 6 and 7, and-in which ycorresponding parts are indicatedby the same letters. l l

In the modifications, figs. 4 and 5, the clay plug may, if desired, be' dispensed with. This construction of apparatus is merely represented as a simplied form, involving few parts in its construction. The object of the tamp or plug N is to prevent the gradual passage of the molten metal from ,the cylinder to the moulds and eiect .the rapid introduction of the metal, upon which depends the attainment of the sharp, well-defined surface' above referred to. i

-In the apparatus, shown by horizontal and vertical sections in tlgs. 6 and 7,'the construction is essentially the same as in figs. 1, 2, and 8 the `only diiierenceheing the-introduction of a sliding-rod, N', for temporarily closing communication between the cylinder J and moulds A. This rod is used as a substitute for-the plug N, its `function being the same, that is' to say, to retard the passage of the 'metal into the mouldsuntil thepressure is applied. When the pressure is applied to the metal in cylinder J, the rod N will be forced backwardby the metal so as to open communication between the cylinder and the moulds. The extent of motion of the ro/d N maybe regulated by means of the adjustable Acollar P, which arrests the rod by coming in contact with an abutment, T. v

By providing a separate vessel or cylinder for the .molten metal' previous to its introduction -into the moulds, and having a pressure to bear upon thesame in the very act of injecting it into thc proper moulds, the elimination of the imprisoned gases commences with the very act of pouring, and continues in full activity until the complete filling of moulds A. l

This mode of operation I find to produce a much more perfect and=well-dened surface on the casting than ,by any process heretofore employed. l

` The relief of atmospheric pressure from tbe-outside of the box D facilitates the escape of the imprisoned gases therefrom.

Having thus described my invention, what I claim as new, unddesire to secure by Letters Patent, isf- 1- The provision, in a mould for casting metals, of a plunger, K, and a-separate injecting-vessel or cylinder, J, havin'ga lining of clay and plumbago or other suitable non-conducting material, to be detached in the manner described,and a temporarily-closable communication with the moulds, substantially as and for the purpose sot forth. i l l I i2. The combination of the'mould-box D, detachable thimble. I, injecting-cylinder J', and plunger K,' all constructed, arranged, and operating in theV manner and for the purposes explained.

3. The arrangement of a series of moulds having consecutiveorices or gates, a slab or follower, B,h'and set-screws F, and box D, as and forthe purpose set forth. Y

' 4. I claim the subject ofthe clause last recited when enclosed within a tight chest, G, having suitable i connection with an air-exhaust, for the purpose stated.

To the ahora specification of my improvement I have signed mly hand this seventh day of, May. 1867. MICHAEL SMITH. Witnesses:

J. J. Cn. Buns, Cass. D. Smm

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