US1942981A - Electric furnace - Google Patents

Description

Jari. 9, 1934. R. SCHMITZ 1,942,981

ELECTRIC FURNACE R. scHMlTz 1,942,981

ELECTRI C FURNAGE Jan. 9, 1934.

2 Sheets-Sheetv 2 Filed Deo. 14. 1929 Je .e441 '5 f7 e4 l w "M Patented Jan. 9, 1934 PATENT ori-lcs ELECTRIC FURNACE Rudolf Schmitz, Herne, Germany Application December 14, 1929, Serial No. 414,093, and in Germany December 16, 1928 7 Claims.

The present invention is a universal electric resistance furnace 'which is characterized by the fact that it comprises two superposed heating chambers, which can be utilized separately or combined for a series of different processes, such for example: melting out the wax, preliminary heating,` smelting, casting, alloying, soldering, and burning porcelain.

On the accompanying drawings two forms of embodiment have been shown, and on these drawings:

Fig. 1 is a vertical longitudinal section of the universal furnace,

Fig. 2 is similar section through the double furnace in a larger scale but without the standard.

Fig. 3 is a detail section of the flask arranged in inverted position together with the auxiliary tube and stand and the model pin supporting cone as arranged for melting and discharging $0 the wax from the model.

Fig. 4 is a front and Fig. 5 a side view of the universal furnace,

Fig. 6 is a longitudinal section through an auxiliary heating device for the process of soldering and melting out.

The universal furnace for melting, casting and alloying on the one side, and the burning out, preliminary heating, porcelain baking v and soldering, according to Figs. 1-6, comprises a $0 suitable standard on which is fitted the body or part a1 of fire proof material. This part is hereafter referred to as a Silit-furnace. This upper part a1 of rectangular or cylindrical section has the sectional form shown in Figs. 1 and 2 and is provided with a chambera which at the top opens into a larger one a2. A receptacle e1 is detachably fitted in the chamber a2 and is filled with an insertion fitting e of non-conducting material. This insertion fitting'e contains an auxiliary furnace b. The insertion fitting e can be exchanged for other parts (Fig. 6), while the chamber a serves for the reception of suitable asks or models. In order to secure a tight insertion of the element e, its container e1 has a depending annular flange 15 which fits into an annular groove 14 of the body a1. For the melting, casting and alloying the body al is utilized i. e. the chamber a in combination with the electrically heated cover e1, e. The insertion fitting e contains a fire proof tube d, closed at the upper end by a cap l1 having an observation opening l2 and containing a plate of mica Z which is held in close contact with the upper end of the tube d by the cap. Said tube is of inverted truncated conical form, and its lower portion is cylindrical as shown. The lower part forms the melting or auxiliary furnace b and has on its circumference a winding of platinum wire 5 which constitutes the heating device. The second outer tube d1 is intended to center and to fasten the rst mentioned tube d.

At the upper part of the tube d enters the compressed air passage m which surrounds the tub d1 with its windings 2 and which contains the valve 3. The heating of the compressed air is due to an ordinary heating equipment 4 lodged between d1 and the helicoidal windings 2. This heating device produces a temperature of about 800.

The outer face of the bottom of the cover part is provided with an annular projection i (Figs. l, 2) which fits out into a similar groove of the horizontal ange 40 of the flask and which contains a tightening ring of copper and asbestos.

The center part of the cover of the container e1 form a detachable cover 41, so that the heating elements 4 and 5 can be removed. They are connected by wires to the contact pins 16, 17 (Figs. 4 and 5).

'I'he ring h lying onvthe upper side of the chamber a can be attached by bolts y, which traverse the flange 40 of the mule and the bottom of the container e1 with its rigid cover part. (Fig. 5.) These bolts traverse suitable vertical tubes, lodged within the embeddingA of the insertion part e. By screwing on the wing nuts f of the bolts g, the metal ring h, wherein hangs the flask 42, is strongly pressed against the flange of the mufile and the latter against the bottom of `the insertion part e, so that an airtight fltting is guaranteed.

'7 is a tubular supporting device which is employed at the melting, casting and alloylng process and lines the melting furnace b nearly in a complete manner.' It is made from fireproof thin material and has for its object to reinforce and to elongate the edge of the melting or alloying hearth level or block b (Figs. 1, l2, 3 and '7). In order to assure its fastening within the embedding composition 8 its under end has a fiange.

During the embedding of the model 43 to be cast, there is utilized the auxiliary tube 7 and the stand c (Fig. 3) which is provided with a central opening c2 which receives the cone c1 and the inverted tube '7, which must be well centered within the flask in order to occupy the exact position within the melting furnace b. The metallic cone c1 supports the model pins and Serves to form the inner surface of the hearth gases.

level b. The flange c3 determinates the exact position of the mufiie 42.

The filling of the flask with embedding material 8 is made when the ilask occupies the inverted position, shown in Fig. 3 and by introducing it through the opening 44.

For the melting out of the wax, the preliminary heating, burning of porcelain and alloying, the Silit-furnace al, i. e. the furnace a is used in cornbination with the insulating part 45 (Fig. 6).

In the bottom of the furnace a, the walls whereof show heating elements 46, is provided an aperture 11, which continues in a channel 12 and a metallic tube 9 attached by a saddle 13. The condensation of steam escaping from the moist embedding composition of .the flask takes place within the tube 9 surrounded by water jack r. The condensed water and molten wai: drops into the vessel e.

The insulating part 45 Fig. 6 for the melting of wax and the preliminary heating has a conicalchamber 45a closed at both ends by mica plates 10.

All above mentioned parts are situated with in the standard 2O by placing the projecting edge 18 of the body block a1 on the T-ormed frame 19 (Figs. l, 4 and 5). Within the inner side of the standard are placed the electric wires, the resistances, the current converter, the pedal u for driving an air pump (Figs. 4, 5) and its air conducting tube, going to the blast bor: which occupies the bottom part of the element a1. The air tubes m, m' are detachably connected together by the winged union 1.

The switchboard z, shown in Fig. 4 is provided with the usual switches for the different heating devices 4, 5 and 46 and with the necessary apparatus, such as manometers, taps, etc. The connecting cables are placed at the rear side of the standard.

The different processes are conducted in the following manner:

The metallic cone c1 and the short tube 'I are according to Fig. 3 placed into the opening c2 of the stand c, the casting pins 43a for the model 43 are attached by wax as at 43b to the cone c1, the flask 42 is placed in inverted position on the support c andiilled with more or less liquid embedding composition. After the hardening of the embedding mass the flask is lifted off and the pins are withdrawn.

For the melting out of the wax, the member e, e is ilrst removed from the furnace chamber c2 and the flask 42 is arranged in its inverted position, Fig. 3, in the chamber a, into which is now introduced the insulating element 45 (Fig. 6). The heating elements 46 produce the required temperature and the melting of the wax begins. lit drops through the channel 12 and the tube 9 into the collecting vessel s. The moist steam or the embedding composition of the flask is condensed within the tube 9 and the water drops also into the vessel.

The i'la .r is uniformly heated and without danger or" the operator being injured by the wax After the melting process the heating of the `flask is continued in order to raise its temperature to a desired degree.

The flask is then removed and attached in the normal position (Figs. l and 2) to the insulating element, e, e1 by the bolts g and the winged nuts f. After the insertion of the parts e. 42 into the chambers of the body a1 the air conducting tubes m, m' are connected by the nut' 1.

The cast-metal is then put into the hearth b.

. The heating wire 4 is then switched into circuit to effect heating o! the compressed air containing pipe 2 connected to the container x which is filled with compressed air by operating the air pump t. By increasing the temperature of the heating element 5 of thefurnace b, which 8 has also been switched on, the casting metal in the hearth b is melted.

The contents of the hearthcan be observed through the mica plate 1, and when the metal is melted the blast valve 3 is opened and the 8 molten metal pneumatically forced into the ilask. After the molten metal has nlled the hollow in the embedding composition of the asl; the three heating elements of the Silit-furnace el, the furnace b and the air pipe 2 are then switched 9 oi and the compressed air caused to escape by unscrewing the nut l.

The form of embodiment shown in Fig. 'I represents a tilting furnace, the principles of operation of which are similar to those of the furnace 9 hereinbefore described.

I claim:

l. An electric furnace comprising a body having a lower chamber and an upper chamber of greater width than the lower chamber and into 10 which the latter opens, a flask arranged in the lower chamber and removable therefrom, insert member removably mounted in the upper chamber said flask being mounted on the bottom of said insert member, and a melting furnace in 10 said insert member, and arranged to discharge molten material into the flask.

2. An electric furnace comprising a body hat'- ing a lower chamber and an upper chamber of greater width than the lower chamber and into 11 which the latter opens, a flask arranged in the lower chamber and removable therefrom, an insert member removably mounted in the upper chamber said flask being mounted on the bottom of said insert member, and a melting 11 furnace in said insert member, arranged to discharge molten material into the ilask, said insert member also having a compressed air discharge duct opening into the melting furnace.

3. An electric furnace comprising a body hav- 12 ing a lower chamber and an upper chamber oi greater width than the lower chamber and into which the latter opens, a ask arranged in the lower chamber and removable therefrom, an insert member removably mounted in the up- 12 per chamber said flask being mounted on the bottom of said insert member, a melting furnace in said insert member, arranged tc discharge molten material into the flask, said insert member also having a compressed air discharge duct 13 opening into the melting furnace, said body being further provided with a compressed air container and a duct leading therefrom and detachably connected to the compressed air duct of the insert member.

4. An electric furnace comprising a body having a lower chamber and an upper chamber of greater width than the lower chamber and into which the latter opens, a flask arranged in the lower chamber and removable therefrom, an 14 insert member removably mounted in the upper chamber said ilask being mounted on the bottom of said insert member, a melting furnace in the insert member and arranged to discharge molten material into the flask, a plate covering 14 the lower chamber and having an opening through which the ilask depends and means detachably securing said covering plate, said ilange of the flask and said insert member together.

5. An electric furnace comprising a. body hav- 15 ing a lower chamber and an upper chamber of greater width than the lower chamber and into which the latter opens, a flask arranged in the lower chamber and removable therefmm and an insert member removably mounted in the upper chamber said flask being mounted on the bottom of said insert member, a melting furnace in said insert member, and arranged to discharge molten material into the ilask, said melting furnace having a detachable cap provided with an observation opening.

6. An electric furnace comprising a body having a lower chamber and an upper chamber of greater width than the lower chamber and into which the latter opens, a flask arranged in the lower chamber and removable therefrom and an insert member removably mounted in the upper chamber said flask being mounted on the bottom of said insert member, and a plate covering the lower chamber and having an opening through which the flask depends and means, detachably securing said covering plate, said ange of the ask and said insert member together, the flange of the flask having a groove at its upper side and the lower side of the insert member being provided with a projecting bead to enter said groove and form a tight joint between said insert member and said ilask.

7. An electric furnace comprising a body having a lower chamber and an upper chamber of greater width than the lower chamber and into which the latter opens, a flask arranged in the lower chamber, removable therefrom and having a. ilange. an insert member removably mounted in the upper chamber, and a plate covering the lower chamber and having an opening through which the flask depends and means detachably securing said covering plate. said flange of the ask and said insert member together, the flange of the ilask havingv a groove at its upper side and the lower side of the insert member being provided with a projecting bead to enter said groove and form a tight joint between said insert member and said flask, said insert member also having an additional depending ilange and said body having a groove around the bottom of the upper chamber in which said additional flange is iitted.

RUDOLF lll

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