US1458835A - Dental casting flask - Google Patents

Description

June 12, 1923.

N. O. LYNN DENTAL;- CASTING FLASK Filed Nov. 19.' 1921 .iaten'ted June l2,

NATHAN-dunner TUCSOMARIZONA.

. DENTALCASTING FLASK.

Application aieaivvmier 1e, 1921.l seiiaiio.` 516,442.r

17.70v 4 czZvZ .iolioinf it may `vince/.Yat

.Be it known that 1NA-THAN O. LYNN,

ay citizen of the lUnited States, residing at' gold, aluminum,- and other VKmetallic [alloys iscaccomplishedlbhy the preparing of molds for each .individual case, wherein an investment, vsuch as ,af body offmold forming-finaterial, is placed in the flask in plastic state, andxa pattern having the form of ythe'articleto be produced is embedded lwithin the same, the pattern beingnifade ofa volatile substance, suchas wax or'thelil {`e, which will be .destroyedby ,the alctionof heat applied to the flask .for thev purpose and for the driving from the investment of `allof its moisture content. Whenproperly heated, the investment'will hardeinfand the waa pattern be destroyed, whereb-ya mold space or cavity will ,bel `providedor v,the reception therein: of the desired`v molten metal from whichV thearticle is tovbe produced, and this `molten metal has `tobe forced into the mold i space or cavity, vand is accomplished either' bythe useof a pressure or vacuum' machine. When hardened, the investment is oifa rela# tively great porosity, and, in the use of a pressure machine, the molten metal is forced downwardly of the sprue holeleading into 'the moldspace or ca'v'ity,uiiider the action ofthe pressureof` such machine, while in the use of the .vacuum machine, the action of the.

same drawsA out all of the airfro'in the pores of thefinvestn'ient with the,` result that the molten metalf isv forced 7intothe mold spacefor cavity under atmospheric pressure. Heretofore,; inthe practicef'and in the use of known types of 'dental flasks crniolds, it very often, occurs that, byv freason 'of inaccuracies the positioning oithefwaxeipatf tern within theinvestment, themoldfspace orl cavity v'is formed too near ltheend ,on the latter so ythat the outer wall thereoffi'sf't@ Weak to withstand vthe pressure or .vacuum Vmethods of introducing the inoltenl metal "toy the mold' space" or cavity,` and is; .broken fdown, whereby the lentire operationA vis a failure, with a consequent serious lossin tiin,elabor, andinalterial'in such operationy. as well as in the preparation of a new mold andthe carryingout of the ,additional casting operation.

Thev principal Vlaslroii the class mentionedfandone' wheres of any particularpiece ofdentalfvvorkfis assured. 4 t Y Another' objectof the invention; is'to.prof` vide yfor a .casting flask of the typef-menQ` object of` theI present'infveiition, therefore, is to lprovide for afcafsting lin the. foregoing/defects and. disadvantages inthe structure and operation of such .des ,l

tioned, and one-of anvextreinely simple and inexpensive construction andV arrangement of parts, and wherein the wax `pattern'may bev accurately einbecldedwithin `th'e`-, i'nvesti thepressure'or vacuum methods offorcing v .the molten metal into thef cavity.

v Az further object of the finventioniis to provide fora castingiiaslg ofthe characterset i mold l space :jor

forth, and one' wherein, provision ifs made cross sectional area. of" the porous investl` ment, such as loften( results in the" breakinz down of the weaker wall'portion o f'thfela't-y i' tens, or` in the jfailurejto forceV the molten..

inetal'into 4the mold through lossfofthis pressure or suction, a'meansbeing provided whereby such pressurey is exerted centrallyV ofthe body of the linvestment li'roinoiie end to the other thereof, andfin line with"` the i mold 'space or cavity therein,"` for."su chfipuifpose,` as w'ellv as to assure ,of the. inoltenineta'l -illingthe mold space or 4cavity,'and-fnot y i otherwise being spread to an appreciable extent into the pores of the investment.

Another' object of the invention is to provide for a casting flask as characterized, and one wherein the end wall of the investment or mold body, in proximity to which the mold space or cavity is formed, is suitably reinforced in a manner to prevent the breaking down thereof under the effects of pressures used for the forcing of the molten metal into such space or cavity.

lVith the foregoing and other objects in view, the invention resides in the certain novel and useful construction, arrangement and operation of parts, as will be hereinafter more fullv described, set forth in the appended claims, and illustrated in the accompanying drawings, in which l Figure 1 is a vertical section through a preferred embodiment of the casting flask,

and showing the parts thereof in the initial.

or mold preparing position of operation.

Fig.v2 is a view similar to that of Fig. 1, but showing the casting flask in reversed position and ready for the casting operation,

Fig. 3 is a horizontal section taken on the line 3-3 of Fig. 1, y

Fig. 4 is a horizontal section taken on the line 4-4 of Fig. 1, and,

Fig. 5 is a top plan view of the flask as shown in Fg- 2- Referring to the drawing, wherein similar characters of reference designate corresponding parts throughout the several views thereof, the preferred embodiment of the .invention as shown therein comprises a cylindrical flask body or casing formed to provide an upper portion 10, and avlower portion 1,1, said portions having their connected ends interiorly and exteriorly threaded, as at 12, for adjustable engagement one with respect to the other, the lower portion 11 beingof a greater length than the upper portion 10, substantially as shown.

The lower portion 11 is preferably formed to provide an inturned flange portion 13 at its lower end, and has its walls slotted as at 14, for a portion of its circumference, at a point immediately inward of the flange portion 13, for the insertion therethrough V of a perforated removable bottom member or plate 15, the inner portion of the latter being of a width corresponding to the mean diameter of the opening` through the flange portion 13, and of a. length, to have its inner end supported on the inner wall thereof, while the outer end portion* 16 is coextensive with the slot 14 and has its outer edge curved on a line conforming with the curvature of the outer surface of the cylindrical body portion 11` except for a. centrally and outwardly extended linger gripping portion 17, by means of which the insertion and withdrawal of the plate 15 is readily facilitated. The upper portion 10 of the cylindrical body is provided with a concaved wall 18, spaced inwardly of its upper end, and which has a sprue hole 19 at its cent-er for purposes which will be hereinafter more fully explained. r

`In the preparing of the mold, with its upper and lower portions 10 and11 of the ask unthreaded, and with the bottom plate 15 removed from the lower portion 11, the

-upper portion 10 is placed top side down on the topy of a work-bench or other suitable support (not shown), and is centered over a sprue former 20, which is circular in form and has aconvex upper face provided with an opening at its center and preferably filled with a suitable plastic material orwax filling 21 for the engagement therein of a sprue former wire 22, which is now passed downwardly through the central opening 19 formed in the concave wall 18, and has its lower end forced into the wax filling 22 within the opening of the support 2() for the purpose of supporting in proper position, within the flask body, of a pattern 23 fixed onits upper end. The lower portion 11 of the flask is now screwed onto the upper portion 10, as it stands, and

until the wax pattern 23 is at the desired distance below the open or bottom end of the flask. This pattern 23 is in the exact form of the desired dental article or restoration to be cast, and ispreferably formed of a wax capable of being readily v'oliVitli the parts in thevposition as thus` de-` scribed, the flask body is'now filled with a suitable mold forming material or investment 24 in plastic state, which is passed through the central opening 19 and fills the space between the concaved'wall 18 and the convexed face of the sprue former 20, as

well as the body ,ofv the flask proper, when the bottom plate 15 will be inserted inwardly of the slot 14 and in a manner to have its inner end portionseat against the inner wall of the flange 13, in which condition, it is left standingr until the investment material 24 has hardened. The sprue former 2O is then disengaged yfrom the flask end and the sprue wire 22, by aquarter turn, when heat is to b .e applied to the flask for the purpose of evapora-ting all moisture from theyinvestmentfmate'rial andv for the destruction, melting orV vaporizing of the wax pattern 23. By thusV destroying the wax pattern 23, a vmold space or cavity 23", as shown in Fig. 2, will be provided within the hardened body of,ther plastic material or'investment 24, and, upon the lwithdrawal of the sprue former or wire 22, a sprue duct will extend from the moldrspace or cavity 23 to and open through theupper end wall of the mold body or investment 24, and centrallyv with respect to the sprue hole 19 with the concaved wall 18 of the upper portion 10 of the flask. For the forcing of the molten metal into the mold space or cavity 23, the flask is turned end for end from its original position, and the molten metal is forced downward of the sprue duct or passage 22 and into the mold space or cavity 23', the air pressure used for such purpose passing downwardly ofthe sprue hole 19 through the pores of the mold body or investment 24, and out of the perforations formed in the bottom vplate 15 at'the lower end. of the lower portion 11 of the flask. After the mold space or cavity 23 has been filled with the molten metal, the flask is allowed to cool, when the yupper part 10 thereof will be removed from thelower portion 11, preferably'by softening the in- `Ivestment 24 by soaking in water and unscrewing the parts of the flask, .when the investment 24 maybe easily cleaned away from the inside of the flask and the casting removed therefrom. l

The positioning of the pattern 23 at a proper and necessarily predetermined dis-l tance inwardly of the lower end of the in- -vestment 24, so that a suflicient thickness of the latter will be provided at this side of the mold space or cavity 23.,'is readily accomplished by the lengthening or shortening of the flask body, it being very essential in this particular casting art, that the wax pattern 23 be placed, at the time of its being embedded in the plastic investment, at a definite distance from the lower end or bottom of the flask so that, when the molten metal is forced down through the sprue hole 19, and the sprue duc-t 22 and into the mold space or cavity 23', it will remain within the latter, since the pressure used for the forcing actionwill have been reduced by reason of the escape of the air through the pores of the mold body or investment 24, whereas, should the mold space or cavity 23 be placed too far from the lower end or bottom of the investment 24, the effects of the pressure would be such as to force a goodly portion of the molten metal into the pores of the mold body or investment, since the lessened distance between the mold space or cavity 23 and the sprue hole I19 would not be suflicient to permit of the necessary rapid seepage of air through the pores of the investment for the reducing of such pressure. However, if the mold space or cavity 23 is formed too close to the lower end or bottom wall of the mold body 24, the lower wall portion of the latter will be broken by the pressurewithresult that the metal will lrun out at the "bottom ofthe flask, :causing fail..

ure to the operation as Vhas beenhereinbefore eXPlained.y v

From,y the foregoing,lit=will be readily -ap parent .that'while a. preferredkembodiment of the castin '.mold...orfl`ask has 'beend'e- .i y

Having thus fully described the invention,

what is claimed, is

1. In a casting flask as characterized, al

flask body open at one end and having 'a sprue hole opening cent-rally ofthefclosed end thereof, said flask body beingformedl to provide upper and lower separable secf tions one in threaded engagement with theother, a sprue former adapted vfor insertion into said flask through the vspruehole in the closed endthereof, a, pattern carried at the inserted end of said sprue former and adapte` l ed to be embedded in aplastic material filling said flask body, and a removable perf' forated plate carried at the open end of said flask body for reinforcingthe plastic filling during the casting operation, the separable sections ofl saidl flask body being relatively. adjustable for effecting the proper position!v p I pattern within the plastic filling f v k 2. In a casting flask for the purpose set ing of said therein.

forth, comprising a flaskY body formed to. *Y

provide separable upper and lower sections,

.said upper section' having formedintegral.

with vits inner vface,V at a 4point removed from the upper end thereof a concave wall formed with a centrally disposed opening,`

a removable perforated bottom plate engaging in the lowersection in proximity toits lower end,'a sprue former vadapted for insertion inwardly with respect tosaid wall and` through said opening and adapted to carry a pattern at the inserted end thereof,

and means for adjusting the sections of said flask body for affecting they-proper positioning of the pattern on the sprue former.

3. In a. casting flask for the purpose set forth, a flask body formed of a pair of Sections adjustably connected together, one ofv said-'sections havingv formed integral with its inner face a concave wall lformed with a centrally disposed opening, and the other of said sections provided with a removable perforated bottom plate.

4. In a casting flask for thepurpose set forth, aask body formed of an upper and a lower separablesection, said upper section j having formed integral with its innerigface at a. point removed from the upper terminus thereof a concave wall formed with av center just-ably connecting them together for effecting the proper positioning o'l the pattern therein. f

In testxnonT whereof, I my Signature hereto.

NATHAN o. LYNN.

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