US1488262A - Dental oven - Google Patents

Description

March 25 1924.

v M2882@ E. MAGINNIS DENTAL OVEN Filed April 25 1921 2 Sheets-Sheet 2 *Dave/Ziff @L m 7% im Patented Mar. 2,5, 1924,

AUNITED sTA'r-E-s EUGENE MAGINNrs, or EvANsroN, ILLINOIS.

DENTAL o-vEN.

Application iiled'April 25, 1921. Serial No. 464,150.

To all ywhom'vlt may concern.'

Be it known that I, EUGENE MAGINNIS, a citizen of the United States, residing aft Evanston, in the county of Cook and State of Illinois, lhave invented certain new and useful Improvements in Dental Ovens, of which the following is a specification.

My invention pertains to features of novelty and advantage, both structural and functional, in furnaces or ovens particularly, though not. restrictedly, in such appliances of relatively small size designed and adapted for dentists work.

More specifically, the invention relates to heating appliances of this general type and style intended for burning out invested models as in the manufacture of meta-l inlay casting for teeth, provided by first forming a wax or similar model of the filling to be supplied, encasing such wax model in a covering or investment of appropriate more or less porous material, such as plaster of Paris, and heating the -tlask conta-inin such model and its covering to cause thea sorption of the wax in the investment material, thereby forming a matrix or mold the exact shape and size of the tooth cavity to be filled into which the molten metal may be poured to form lthe desired inlay or casting.

The heating of the flask to eiiect the dissipation of the wax must be controlled within iertain temperature limits, otherwise defectiveV and improper results ensue.

Electrically heated furnaces or ovens have heretofore'been provided for this work but they have provento be unsatisfactory because of lack of adequate heat control, a though at first thought it would seem that nofsuch undesired results would necessarily follow. y i

Accordingly my improved oven or furnace is heated by burning gas and no diiiiculty is encountered in automatically controlling the flow thereof to govern and control the temperature developed. i `Such heat also by reason oflts distribution yquired reliable and safe results.

A further object and purpose of the invention is the provision or production of an oven of this character which `is simple in structure, economical to manufacture, and which may be operated satisfactorily by persons more -or less unskilled.

ln order that those acquainted with this art may have a full and complete understanding of the invention and its various benefits and advantages, l `have illustrated a preferred and desirable embodiment of the same in the accompanying drawings forming a part of this specification and throughout the several views of which like reference characters refer to the same parts.

In these drawings:

Figure l is a substantially central longitudinal vertical section through the novel oven;

Figure 2 is a horizontal section on line 2 2 of Figure 1, the thermometer and its lsupport being omitted;

Figure 3 is a horizontal section on line 3-3 of Figure l, the parts being viewed in the direction indicated by the arrows;. y

Figure 4 is a vertical cross-section on line 4-4 of Figure l; and A Figure 5 is an inverted plan view of the heat delector employed over the burner or it may be considered as a horizontal section on line 5-5 of Figure 4, the parts being viewed from below as shown by the arrows.

By reference to these drawings it will be seen that the improved oven or furnace comprises a main, sheet-metal housing or casing characterized as a whole 10, comprising feet or legs 11 on which the structure stands, a bottom wall 12, end walls 13 and 14, a front wall 15, a back or rear wall 16,

and a top wall 17, the margins or borders of the metal sheets being interfolded at 18, 19 and 20 to properly unite the parts together as is customary in sheetmetal work.

-As is indicated, perhaps most clearly in Figure 3, the horizontal bottom or ioor plate 12 has a central hole 21 therethrough and also a smaller hole 22 at or -near each of the four corners of thehousing for the admission and more or less even oruniform distribution of the outer air to carry on the combustion of the gas.

Similarly, the top plate 17-has a central aperture 23 for t-he 'discharge of the products of combustion and a smaller hole 24,]'ust back of the aperture 23 for the accommodation of a. thermometer 25 referred to hereinafter.

A horizontal partition or division sheetmetal wall 26 divides the housing or casing into an upper and a lower chamber 27 and 28, respectively, such plate or wall being of less length than the'inside of the housing leaving spaces between its ends and the adjacent end walls of the housing.

Such partition wall is held in place by being fastened to the front and rear walls of the housing by means of rivets and downt'urned ears 29 and 30 on plate 26, the back edge of the plate being spaced away from the rear wallof the housing as depicted in Figure 4.

A chamber 31 is formed inside of the upper compartment 27 referred to by means of a bent metal plate having a downtinned flange 32 (Figure 4) inside of and fastened to the front wall 15, a horizontal top wall 33 equippedwith two ventilatingholes 34,

34 (Figure 1) and an aperture 35 (Figure VIl() 4) for the thermometer 25, a rear vertical wall v36 spaced forwardly away from t-he back wall of the housing, a horizontal floor wall 37 above and spaced away from the partition wall 26, and a downwardly extended flange 38 disposed and fastened between the flange 29 and the front wall 15 of the housing.

Such compartment or chamber 31 also has sheet-metal end walls 39 and 40 (Figure 1) positioned inwardly somewhat from the cor` responding end walls of the outer housing I or casing.

Thus the several walls of the chamber 31 are spaced away from the walls of the housing and division wall except the front wall of the former, which in register with such chamber has a door opening 41 and a hinged door 42 therefor, the lower chamber or cornpartment 28below the partition wall having a front door opening 43 and a hinged door 44.

The lower compartment 28 houses a Bunsen-gas-burner 45 over and raised above t-he opening 2l by the feet of the burner which rest on the bottom wall 12.

A bent pipe 46 extending through a hole 47 in the end wall 14 connects such burner to an automaticfgas controller 48 coupled to the gas supply by a pipe 49.

The flow of gas through the controller from the pipe 49 to pipe 46 is governed or regulated by a valve arm 50 fulcrunied inside the controller at 51 and adapted to open and close'more'or less a port through the member 52 interposed between the two pipes.

The valve arm is under the influence of a coil expansion spring 53 tending to rock the Varm in a direction to open the port or passtem being externally threaded and screwed in a hole in the end wall 14 and held tight in position by a lock nut 56, such stein also extending through a hole in the wall y40. The left hand endl of the tube is closed by a threaded plug 57 to which is fixedly fastenedv an end of a thermostatic rod 58 extended through the tube and stem and through an apertureV in the fulcrumed valve arm 50, being supplied with a nut 59on the threaded end of the rod and having arounded part 60 bearing on the outer face of the arm. Y

Hence as the tube and rod vary relatively as to length due to slight variations or changes in temperature, the position ofthe valve arm will be controlled to maintain a substantially uniform flow of gas and an unvarying temperature in the furnace.

The position of' the nut on the rod may be modified or changed to vary the controlled temperature by turning an external finger 61 on a shaft in the wall of the controller, such shaft having a bent arm im engaging one of several notches or recesses in the nut. Y

A heat deflector or shield 64 spaced below the horizontal division wall and located above the gas-burner, has marginal flanges 65 along its opposite edges and is fastened to the elements 26 and 37 by means of bolts 66 extended through holes in such members and in end lugs 67 of the shield. Y

Thus the intense heat generated directly above the burner is distributed more evenly and prevents the Vupper. chamber from becoming unduly hea-ted locally.VV

Two, or any other desired number of, deck or platform plates V68 are employed in the chamber 3l, each having flanges resting on the Vfloor plate 37, Vwhereby such elements 68 are held above the latter providing air spaces between them.

The thermometer 25 positioned inV the registered holes 24`and 35 rests on an asbestos'blo'ck 69 on one or both of the deck plates, its upper portion extending out of the furnace where the reading of the height of the mercury column may be easily takenl and hence the prevailing tempera-ture in the chamber readily ascertained.

The one or more flasks 7 Ocontaining the invested models are positioned on and 'sup-.b ported by such deck plates and are heated the required period at theproper andvcon# trolled temperature to effect the absorption or dissipation of the wax of the model, all

will be readily understood. y

The air for carrying on the combustion of the gas at the burner enters the lowerchaniber or compartment through Ythe 'several per- A forations orapertures 21, 22 and 47, the hot gases rising from the burner being prevented from directly striking or coming in contact with the division or partition wall immediate-ly above the burner by reason of the presence ofthe shield or deflector 64.

Such hot gaseous products of combustion flow up past the end and rea-r walls of the inner chamber 31 and along its top Wall, being discharged through the central opening 23 in the top Wall of the outer housing or shell.

In this manne-r the contents of such chamber are heatedup to and maintained for the desired period at the required temperature, substantial fluctuations in the lat-ter being prevented by the automatic thermostatic control of the flow of gas to the burner.`

It will be observed that there is more or less of a dead air space between the walls Q6 and 37 and between the latter and the removable deck plates 68, whereby the Flasks will not be unduly heated from below but will be subjected to a practically uniform temperature on all sides.

The holes 34 in conjunction with the aperture Q3 afford convenient and simple means for ventilating and permitting the esca-pe of moisture from the heat chamber containing the flasks.

The invention, as defined by the appended claim, is susceptible of a variety of embodiments and hence more or less radical changes may be made in the structure illustrated and described without departure from the substance and essence of the invention and without the sacrifice of any of its substantial benefits and advantages.

I claim:

An oven of the character described, comprising in combination, a housing having apertured top and bottom walls, legs supporting said housing, the front Wall of said housing having upper and lower doorways and doors therefor, a gas-burner supported on said bottom wall, a horizontal partitionwall in said housing between said doorways leaving a space` between itself and the end and back walls of said housing, a chamber above said partition-wall .having its top, rear, and end walls spaced inwardly from the corresponding walls of said housing and its bottom wall spaced above said partition- "all, the top wall of said chamber being a-pertured for ventilation, the lower door of said housing affording access to the compartment containing the gas-burner, the upper door affording access to said chamber, a heat deflector secured below said partition-Wall above said burner, a. deck plate in said chamber having downturned marginal fianges resting on the bottom wall thereof, a thermostat in said chamber, a gas pipe connection with said burner, and a valve in said connection controlled by said thermostat.

EUGENE MAGINNIS.

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