US2024707A - Crucible furnace - Google Patents

Description

Dec. 17, 1935. F. SOUTH, JR., ET AL CRUCIBLE FURNAGE Filed Ooi. 5l, 193.3 2 Sheets-Sheet l Dec. 17, 1935.

F. SOUTH, JR., ET AL CRUCIBLE FURNACE Filed OC` 3l, 1933 2 Sheets-Sheet 2 pwd IN VEN TORS. 0,@/7/4/1/ $007@ J2.

' ATTORNEY Patented Dec. 17, 19235 UNITED STATES PATENT oFFIcE CRUCIBLE FURNACE Application October 3l, 1933, Serial No. 696,010

7 Claims.

This invention relates to improvements in crucible furnaces, or furnaces of the type wherein metals are melted or otherwise treated in crucibles disposed within the furnace, the crucibles being heated and the heat transmitted to' the contained metal by conduction, convection and/or radiation through the walls of the crucibles.

As a rule, furnaces of this character require almost constant attention and frequent charging; the repeated charging and attention is highly objectionable and the cost of production is considerably more than it should be. Further, the operator is subjected to intense heat, being required to work in close proximity to the flames emitting from the top of the furnace.

The present invention contemplates a construction particularly designed to` overcome the objectionable features above mentioned and to provide for rapid heating, economical fuel consumption, low metal loss, and high metal purity.

Our invention includes, in a crucible furnace, a melting or reduction chamber in which the crucible is positioned and a removable furnace extension or supplemental member or structure associated with the body of the furnace, said supplemental structure being provided with a charging chamber or hopper therein, of such dimensions and configuration as to form a continuation of the crucible within the melting chamber, thus permitting the entire charge to be placed in the furnace before starting the latter, whereby the entire charge may be initially introduced and preheatedbefore actual reduction in the crucible.

A furnace of the character described is shown in Letters Patent of the United States No. 1,930,323, issued to us on October l0, 1932; and the present invention is directed to modified constructions thereof, including' certain elements and functions not present in the embodiment of the said application. For example, a separable hopper or charge-receiving chamber loosely mounted in the removable body extension; the formation of the hopper and the crucible from materials having approximately the same expansibility, for instance, both the hopper and the crucible are preferably formed of graphite; and the construction o-f the body extension and the hopper.

We are aware that some crucible furnaces have heretofore been provided with an extension in which a hopper or a charging chamber has been located. Such structures, however, have not proven a commercial success for a number of (Cl. 26S- 14) reasons. Thus, for example, the hopper has been maintained within the extension by a wedging action; the hopper has not had an expansion independent of the body extension; and, further, the hopper and crucible have been made of diier- 5 ent materials, embodying different properties of expansibility.

In the accompanying drawings, which illustrate applications of our invention:

Fig. 1 is a top plan view of a crucible furnace 10 embodying my invention;

Fig. 2, a vertical sectional view taken on line II-II of Fig. 1;

Fig. 3, a top plan view, partly in section, showing a modified embodiment of our invention; and 15 Fig. 4, a vertical sectional view of the form of Fig. 3, taken on line IV-IV of the latter figure.

Referring to the drawings, and first to the form of Fig. l, the crucible furnace A is of the upright cylindrical tilting type and comprises a 20 body proper 2, formed of suitable refractory material surrounded by an insulating lining 3 and a metal casing 4. 'Ihe inner wall of the cylindrical refractory body 2 forms a melting or reduction chamber 5 for receiving a crucible 6, 25 preferably made from graphite. This crucible is mounted upon a pedestal 1 disposed on the floor 8 of the furnace in such a manner that the upper edge 9 of the crucible lies in substantially the same plane as the upper surface l0 of the 30 body 2.

Positioned adjacent the lower portion of the body 2 and preferably constructed integrally therewith is an elongated combustion chamber l I disposed tangentially with respect to the cylih'- 35 drical melting chamber 5 and in open communication therewith and having a burner I2.

The furnace extension structure, generally designated B, comprises a hollow cylindrical removable body l3 formed of refractory material and 40 having a metallic casing I4. This extension is designed' to be mounted on the upper end I0 of the furnace body.

As illustrated, the extension is formed with a central bore or chamber i5, adapted to receive 45 a separable hopper or charge receiving member l5 thereiman' opening il in the wall thereof 1ocated adjacent the end of the extension designed to rest upon the furnace body when in operative position and to coincide with the pouring open- 50 ing i8 of the said body. The provision of the opening I'l arranged adjacent to the pouring opening provides ready access to the contents of the crucible 5, and enables working'and skimming of the metal, without the necessity of reach- 55 y i type of furnace. 40

ing down through the extension. I9 designates a swinging door covering both the pouring opening I8 and the opening Il.

The interior of the extension is provided with a plurality of spaced-apart longitudinally eX- tending projections 20 primarily designed to form relatively large channels 2| for the passage of heating gases and products of combustion from the melting chamber of the furnace up and around the hopper IS. In practice, the hopper is loosely mounted within the extension out of contact with the projections 20, so that in operation the hopper is permitted to expand and contract independently of the extension. Hopper I6 has its lower edge 22 formed complemental with the upper edge of the Crucible and is supported thereby. The hopper and Crucible are preferably made of graphite.

23 designates a lip or curved projection formed on the hopper at a point to register with the opening I1 and to cooperate with a pouring spout or lip 24 on the crucible 6.

In addition to forming the channels 2| or the passages for the heated gases, the projections 20 function as guides in positioning the hopper in the extension and, as shown and as preferred, each projection has a relatively wide base portion a, curved faces b, and a flat face c of considerable width, thus providing a mass of refractory material of a character and configuration that will not be seriously affected by the hot gases.

The furnace is provided with suitable trunnions 25, as is usual in the tilting type of furnace, and 35 designates a removable cover for the hopper.

In the form of Fig. 3, we have shown an embodiment of our invention in a pit or stationary Referring to this pit type, it will be seen that the furnace proper A is of substantially the same construction, as the furnace A, with the exception that the pouring opening found in the first furnace is omitted; also, that a slightly different form cf crucible 6a is employed. In this form, the extension B is quite similar to the extension of the form of Fig. l, and is designed to rest upon the upper end of the body A'. In this instance, the lower end of extension B is recessed as at e to receive the upper edge of the furnace-when the former is positioned on the latter.

In each embodiment, we contemplate the employment of a separable hopper designed to be positioned within the extension and supported by the upper edge of the Crucible, so that the hopper will be loosely mounted Within the extension.

In the form of Fig. 3, the interior of the extension is formed with a plurality of vertically extending inclined recesses 21 designed to receive Vblocks or members 28 designed to form, when the hopper is inserted, channels or spaces 29 for the passage of gases, etc. up and around the hopper.

Members 28 also function as guides for the hopper, but are of a character that will not bind or wedge the hopper in the said extension.

Suitable means are provided for lifting and swinging the extension B as Well as the cover for the hopper, but as these means form no part of the present invention it is deemed unnecessary to describe them.

In order to insure that the hopper |60, is raised slightly with the extension when the latter is lifted, it is provided with an outwardly flared,

flanged or tapered portion d which contacts with the upper end of the extension or with the guide members 28.

We claim:

1. A Crucible furnace comprising a body proper having a melting chamber therein, a crucible in said melting chamber, a refractory body extension mounted on said body proper, a separable open-ended hopper loosely mounted within the extension, and means on the interior of the extension between and from which the hopper is completely spaced providing passages for heated gases, said Crucible and hopper each formed of material of substantially the same coefficient of expansion and having opposed complemental contacting ends whereby the hopper is solely supported by the Crucible and expansible within, relatively to and independent of the extension.

2. A crucible furnace comprising a body proper having a melting chamber therein, a crucible in said melting chamber, a refractory body extension having a central bore mounted on said body proper, a separable open-ended hopper loosely` mounted within the bore of the extension entirely supported by said Crucible, annularly spaced guide members on the interior of the extension for -spacing the hopper from the wall of the bore and providing passages for heated gases, said guide members at their inner ends terminating in a circle larger than the circumference of the adjacent portion of the hopper whereby said hopper is out of contact with said guide means and is independently expansible relatively to the extension.

3. A crucible furnace comprising a body proper having a melting chamber therein, a crucible in said melting chamber, a refractory body extension mounted on said body proper, a separable open-ended hopper loosely mounted within the extension, and annularly spaced guide means on the interior of the extension between which the hopper is disposed providing passages for heated gases, said guide means at their inner ends terminating in a circle larger than that of the adjacent portion of the hopper, said extension having an opening in the wall thereof to permit access to the crucible, said hopper having a side opening registering with the opening of the extension and being entirely supported by the Crucible so that it is independently expansible relatively to the extension.

4. A crucible furnace comprising a body proper having a melting chamber therein, a Crucible in said melting chamber, a refractory body extension having a central bore mounted on said body proper, a separable open-ended hopper loosely mounted within the bore of the extension and having a flared, hanged, or outwardly tapered portion, guide means on the interior of the extension for spacing the hopper from the wall of the bore and providing passages for heated gases, said guide means at their inner extremities terminating in a smaller circle than the largest circle of said tapered portion and said hopper opposite said guide means being of less diameter than the first mentioned circle, said hopper being supported by the Crucible so that it is independently expansible relative to the extension and said flared portion will be engaged by the guide means when the extension is raised.

5. A crucible furnace according to claim 2 wherein said guide members are widely spaced apart circumferentially and have arcuate side walls so that the members are materially wider at their proximal ends than at their inner ends.

Cil

6. A Crucible furnace comprising a body proper having a melting chamber therein, a Crucible in said melting chamber, a refractory body extension mounted on said body proper, a separable open-ended hopper loosely mounted Within the extension, annularly spaced guide members on the interior of the extension between which the hopper is disposed providing passages for heated gases, said guide members at their inner ends terminating in a, circle larger than that of the adjacent portion of the hopper, the lower edge of said extension and the upper edge of said body proper having communicating openings to permit access to the Crucible, said hopper and Crucible having communicating lips registering with said openings, and said hopper being entirely supported on the Crucible.

'7. A Crucible according to claim 6 wherein the lip of the hopper terminates short of the lip of the Crucible.

FURMAN SOUTH, JR. OSCAR E. NEUHAUSEN.

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