US1610809A - Electric furnace - Google Patents

Description

D. F. NEWMAN ELECTRIC FURNACE Dgc. 14 1926.

Filed Feb. 15, 1926 Inventor Delbert F. Newman,

His Attorne Ill) Patented Dec. 14, 1926.

UNITED STATES v 1,610,809 PATENT OFFICE.

DELBERT F. NEWMAN, OF SCHENECTADY, NEW YORK, ASSIGNOB TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC FURNACE.

Application filed February 15, 1926. Serial No. 88,171.

The present invention relates to electric furnaces of. the character in which the operations are carried out in the presence of a selected gas such as hydrogen for example.

The primary object of my invention is to improve the construction and mode of operation of such furnaces and more specifically, to provide means whereby a series of relatively small charges or portions of a charge can be inserted and withdrawn from a large furnace while other and generally similar charges are undergoing treatment, and this without permitting atmospheric air to have access thereto. Another object of my invention is to provide meansfor conserving the selected gas when the successive charges or portions of the charge are introduced and removed.

For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

' In the attached drawing, Fig. 1 is a vertical section of a furnace illustrating one embodiment of my invention and Fig. 2 is a plan view of the rotatable charge-supporting base element.

5 indicates a container element. or member whichis closed at all points except the bottom. It comprises an outside metal covering 6 such as boiler plate and an inside lining 7 of heat-resisting material such as fire brick. The container as a whole may be supported in its proper vertical position by a single central means or by means which engage the bottom or both. s shown a rod 8 is attached to the top and this rod in turn is connected to a piston which is located within a suitably support-ed hydraulic or other cylinder 9. The cylinder may be so positioned that when the piston is in its lowest position the container is also in its lowest positi.on. Where the container is large suitable guides other than the piston and rod for directing its movements may beprovided. Such guides may advantageously be in the form of rollers or sets of rollers engaging the cylindrical walls of the container at equi-distant points.

For normal operations it is not intended that the container be raised and lowered. as will appear later. Nevertheless by so arranging it that it can be moved as described I am able to use the furnace for'large work as well as small. Furthermore, the lifting arrangement permits of ready access to the interior when for any reason it is desired.

Returning again to the construction of the container, it is provided at its bottom edge with an annular plate 10 from which depend thin, concentric rings 11 which are interspersed with similar rings 12 carried by a plate 13 on the base element or member 14 to form a labyrinth packing or seal to prevent the free escape of the selected gas from within the furnace. In addition the grooves or spaces between the rings 12 are partially filled with small metal shot such as are used in sand blasting and into which the rings 11 extend. Such a packing permits of the container being raised and lowered and also permits of relative rotary movements of the container and base element for a purpose to be described later. If by accident an explosive mixture should be formed within the container, the latter is free to lift sufiiciently to release the pressure and prevent injury to the apparatus.

Inside the container is mounted a resistor 15 which may be made of any suitable material and supported in any suitable manner. By preference, the resistor covers the side walls and top of the container, there being the usual spaces between turns or parts of the resistor to prevent short-circuiting and to permit of free radiation. The resistor may be divided into one or more sections or parts and connected in any suitable manner with a source of supply through external, flexible conductors and controlling devices;

In order to permit inspection of the charges during the furnace operation, one or more valved sight tubes 16 are provided.

The selected gas is admitted to the container by the inlet pipe 17, some portion of which is made flexible so as not to interfere with the movements of the container. The pres sure of the gas supplied should be slightly in excess of the surrounding atmosphere to prevent the admission of air.

The charge or work supportingmeans will now be described. 14 indicates a base element or member which is centrally supported by a pedestal 18 and may be termed the main charge support. It comprises a metal disk upon which is mounted a heavy covering of heat resisting material. The container and its base elementtform, the walls of what may be termed the heating chamber in which the charge is located.

The axes of the pedestal and container are in the same vertical line so that the packing devices will not be injured as one part is rotated with respect to the other. Either the base or the pedestal has acentral spindle 19 so arrangedthat the base may be rotated on the pedestal, a ball ,or roller thrust bearing being provided to facilitate such movement. The packing rings 12 and 13 permit this rotation to take p ace without permitting the esca e of gas.

T e base element is provided with chargereceiving openings arranged in a circle. As the present furnace is designed for a charge comprising six port-ions that number of openings is shown but the number can be the total charge will be removed-and a fresh I tainer 5 which is of large diameter is raised changed to suit the requirements. It is intended that the furnace shall be continuously operated. The character of the work to be performed in the present furnace is such that thirty minutes is suilicient to complete the cycle of operation but of'course other kinds of operations or different kinds of charges may require a greater or lesser time. Under the conditions herein mentioned a portion of one substituted every five minutes.

In order to avoid o ening the furnace by separating the base e ement and container, as for example byraising the container, which would result in the wasting of a large amount of valuable gas and also reducing the temperature to some extent, due to the ex- 'posure of the inner surface, I introduce and remove the small charges or port ons successively, the other charges or portions being unaffected in any way. To accomplish this an elevator or loading device is provided which comprises an hydraulic cylinder 25 and a piston or plunger 26 which engages and supports one of the small or auxiliar. charge holders or supports 27, each of whic 1 makes a loose fit in an opening 20. Each of these charge holders is provided with a part of a labyrinth packing of the same character as described in connection with the container 5, but much smaller. lhe other portion of the ackin is carried by the underside of the ase ement. In order to hold the charge holder in place after being elevated hooks 28 or equivalent devices are mounted onthe base element or holder and arranged to engage the "other part in a manner to sustain the weight of the charge holder. After a work holder and its charge are elevated and locked in place and the piston 26 low- ,ered the base element isrotated bya handle 29 or equivalent means to bring another holder into register with the elevator, there being suitable stops for the handle corresponding to its various positions. The plunger 26 is then elevated by admitting water to the cylinder 25 until it supports the weightof the charge holder and the hooks released, after which the charge and holder are lowered.

The charge will of course be hot, and it is then moved sidewise to the platform 30 from which it may be removed either for is opened it is necessary to supply an amount of selected gas over and above the normal requirements to prevent the entrance of air. \Vhen opened the hydrogen in the container combines with the air-t0 form a burning mixture and the burning area corresponds to the diameter of the furnace opening- Furthermore, it is important to keep the burning area substantially in line with the lower edge of the opening for should the air work; up into the container, it would oxidize the resistor and might cause an explosion. If the total charge undergoing treatment is not finished when the furnace is opened, the entrance of air would tosome extent oxidize the unfinished charge or portions thereof.

Now, considering the case where the confrom having access to the other charges, only enough selected gas need be forced into the container to bring the burning area into the openin 20 and slightly below the u per level of the ase element. N o harm wil be done,

however, if said area is substantially below said level so long as the flame does not extend below the under surface of the base element since it would interfere with the removal of the charge from its holder. To state the matter another way, the saving in selected gas is roughly proportional to the difference between the area of the container 5, at its lower end and the area of one opening 20.

Another advantage of this step-by-step method of procedure resides in the fact that only a comparativelysmall amount of cold metal is introduced at a time and hence the 1 ill:

cooling effect. on the furnace as a whole will be reduced to approximately the percentage that the mass of one portion of the charge or portion bears to the total mass. As above intimated, the furnace due to its'novel construction. may be used for large work as well as small and in the customary manner, but when so used'the cost for gas will be. very much increased. However,

this is largely offset by the fact that such use would be rare and the additional facility thereby/afforded would more than offset the additional cost of gas for suchinfrequent use.

Where the furnace is intended for small charges only, the upper side of the base element may be provided with a resistor 31 of the same or different character from that described in connection with the container 5. 'To convey current to and from such a resistor or resistor elements sliding connections will be provided as is usual between relatively movable parts.

Viewed in the broader aspect of the invention, the several individual charges may be regardedas a part of a total charge of which portions are introduced and removed at will As the time required in which to introduce and remove each of the several portions of the charge is short, all of said portions may for some purposes be introduced or removed in quick succcession, so

that for all practical urposes they are treated simultaneously instead of by the stcp-by -step method as previously described.

The furnace herein described is especially intended for uniting metal parts by the fusion of metal, as for example, by the use of copper as a fusing metal, the operation taking place in a hydrogen atmosphere,-but it is to be understood that the furnace is not limited to such use as it is capable of wide application in the industrial arts. As an example, but not as a limitation, the furnace may be used for annealing metal parts of various kinds.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which 1 now consider to represent the best embodiment of my invention, but I'desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States 1. In a furnace of the character described, the combination of a container in which an atmosphere of selected gas is maintained, heating means therefor, means forming a closure for the container and also for supporting the furnace charge within said container, and means for withdrawing a portion of'the charge from the under-side of the closure means and inserting a new portion without exposing the other portion of the charge within the container to the effects of air.

2. In a furnace of the character described, the combination of a container in which an atmosphere of selected gas is maintained, heating means within the container, a base element over the surface of which the charge is distributed and which is covered by the container, and means for lowering a. portion of the charge through the base element and inserting a new portion without exposing the other portion of the charge within the container to the effects of atmospheric air.

3. In a furnace of the character described, the combination of a container which is closed except at one point and has a heatresisting lining, means for maintaining a supply of select gas within the container, an element which cooperates with the container to close it, a seal between the container and element, heating means for the container, and means for introducing and withdrawing the charge through said element,

4. In a furnace of the character described, the combination of a container element which is closed except at one end and is adapted to contain a selected gas, a second element forming the closure for the first, a support on which one element may be rotated with respect to the other, and an annular packinv means which prevents the free escape of gas from'within the furnace, means for heating the interior of the furmace, and means whereby a portion of the charge undergoing treatment can be removed through one of the elements without moving it or exposing the remainder of the charge to the effects of air.

5. In a furnace of thecharacter described," the combination of a container element which is closed except at one end and is adapted to contain a selected gas, a second element forming the closure for the first, a support on which one of said elements is rotatably supported, removable charge supporting means associated with one of the elements and by means of which a portion of the furnace charge can be inserted and removed without disturbing the other portion, and means for heating the chamber formed by said elements.

6. In a furnace of the character described, the combination of a container element, a base elementf means whereby one e ement can be moved with respect to the other to open the furnace, a support for the other element whereby it can be rotated with respect to the first without opening the fur nace, a number of charge supporting means associated with one of the elements for in troducing a charge into the furnace and removing it therefrom, packing means for pre venting the free-escape of gas from within the furnace. and means for heating the interior of the furnace.

7. In a furnace of the character described, the combination of a container which is closed except at the bottom, means for holding the container at the desired elevation, a base element which closes the lowi er end of the container and also supports the charge, charge-supporting means which are carried by the base element, and a support on which said element is mounted for rotar movement.

8. Ina furnace of the character described, the combination of a container which is closed except at the bottom, a means for holding the container at the desired elevation, a base element which closes the lower end of the container and supports the 9. In a'furnace, the combination of a container which is lined with heat-resisting material and is closed except at one end, a heating device in the container, an element Which closes the open end of the container, the two forming a closed charge containing chamber, said element also supporting the charge, means for maintaining a gaseous medium in the chamber, an elevator means for inserting and withdrawing a por tion of the charge from the chamber without subjecting the other portion to the effects of air, and means for moving the container and element relatively to each other to permit the elevator means to insert and remove successive portions of the charge.

10. In a furnace of the character described, the combination of a container, means for holding it in elevated position, a base element which closes the lower end of the container, a'sealing means between the container and element, a number of individual charge supports which are carried by said element and which are moved into place from theunder-side thereof, devices for securing said supports to the element, a pivotal central support for the base element, an elevator for elevating and lowering the charge supports, and means for imparting relative angular movements to the charge supports'and the elevator.

11. A furnace comprisin two principal members which are slight y spaced apart and are ca )able of relative movement, sealing means toprevent the free escape of gas from within the furnace and between the members, removable charge supports carried by one of the members, and seals to prevent the free escape of gas through the Joints between the charge supports and their supporting member.

12. A furnace comprising two principal members which are slightly spaced apart and are mounted for relative independent movements, one ofsaid members having a chamber, supporting means for the charge carried by one of the members, means for successively inserting-and withdrawing said supporting means through one of the members without separating them, and means for maintaining within the chamber a suificient amount of selected gas to prevent the entrance of air to the heating chamber when a portion of the charge is inserted or withdrawn. I

14. In a furnace, the combination of two principal members which define a heating chamber, an electric heating element for the chamber, means for maintaining Within the chamber a suiiicient amount of selected gas to prevent the entrance of air thereto when a portion of the charge is inserted or withdrawn, a number of charge holders which are independently removable and which are carried by one of the members, and poweractuated means for successively moving the holders to insert and withdraw portions of the charge without separating the members, '15. In a furnace, the combination of walls which define a closed heating chamber, one of said Walls having openings, a heat-resisting lining for the chamber, electric means within the chamber for heating it, a plurality of relatively small charge holders which are located in said openings, means for sealing the joints between the holders and the surrounding wall to prevent the escape of gas, means for maintaining a supply of selected gas within the chamber at a pressure slightly above that of the surrounding atmosphere, and ower-actuated means for re-' moving the hol ers and their heated charges from the chamber and inserting cold charges.

In witness whereof, I have hereunto set my hand this 13th day of February, 1926.

DELBERT F. NEWMAN.

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