US1643425A - Necticut - Google Patents

Description

Sept. 27,1927.

D. L. SUMMEY ART OF' FURNACE LINING Filed Oct. l, 925

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UNITED STATES PA'raN'r'orrlcl-z.

DAVID L. SUMMEY, OF WATERBUBY, CONNECTICUT, ASSIGNOB TO BCOVILL MANU- FACTURING COMPANY, OF WATERBURY, CONNECTICUT, A CORPORATION F CON- NECTICUT.

ABT OF FURNACE LINING.

Application nled October 1, 1826. Serial Ha. 138,858.

This ,invention relates to the art of furnace lining.

.In a known type of induction furnace which may be cited as an 'example, anI ino terior channel or passage/usually roughl V-shaped, communicates at its two en s with the hearth of the furnace. This channel :rfceiv'es a portion of the molten bath which acts as the secondary of the transl0 former'and the molten metal is circulated through the channel, thereby establishing. a circulation of vthe bath for thev eectivc transmission of heat to the charge.. Such a furnace is shown in U. S. patent to James l R. Wyatt, No. 1,201,671.

The channel referred to, because of the hi h temperatures involved, is bounded by refractory material. According to known practice, the channel is formed by'tamping refractory material around a tem let or pattern of the shape of the desired c annel, allowing the refractory material to set, and removing or destroying the templet by means of heat. If expansion of the templet, under 25, the application of heat, is not prevented, the

surface of the refractory lining is liable to jbe cracked or otherwise injured by such expansion.

It is an objectof the present invention to provide a method of and means formanufacturing furnace linings effectively and economically, avoidin injury to the lining by expansion of the orm.

With this general object, and others, in

view, the invention consists in the features,

combinations, details of construction and arrangements of parts which will first be described in connection with the accompanyin drawing and then more particularly w pointed out.

. the furnace.

lustrated as an example comprises a furnace body 11 formed of irebr'ick or other suitable material and enslosedin a metal casing 12. Within the boci.7 is a furnace lining 13 of suitable rfrac v*y material. The furnace has a pouhng aio-ut 14 and a charging door 15 communicating witb'tlc" hearth 16.a Communicatingwith the lower'part of the hearth are the two ends of'a substantially V-shaped channel indicated` at 17. This channel is bounded by the refractory lining 13, the outer defining surfaces mergin into the straight walls of the hearth an the inner surfaces merging into aaounded hearth bottom,.as shown in Fig. 1l

Surrounding the upper ends of the chan- /nel is the core 18 of a transformer with a primary coil suitably wound and connected, the inner leg of the core and the primary coil being encased in a shell 19. When the furnace is in operation the molten metal in the channel acts as the transformer, secondary.

The lower part of the furnace lining, that is, the part which bounds the channel, is formed by tampin refractory material about a tem let an removing the templet after the re raetory material has properly set. While various refractory materials having various consistencies may be used, a dampened granular material having a consistency somewhat like damp sand has been' found suitable.

According to the present invention, there is provided a templet or form having substantially the shape of the channelto be formed, destructible by heat, and capacitated to be rendered collapsible in the initial heating period. This may be accomplishes?, for example, by providing the templet ith a relatively weak or low heat-resisting portion following a given line around the periphery of the templet and, in effect, connecting two halves separated by a plane longitudinal of The templet may conveniently be constructed of wood as such a templet is easy to build and easy to burn out. In such cases, the weak portion may be a relaw tively thin wall so arranged that when the templet is heated up to the point of combilstion, the material of the thin wall is consumed first, i. e., during a preliminary combustion period. This destruction o the dividing wall separates the templet into two ole lll

pants collapsible. one toward the other. thereby to take up or compensate for any tendene-y of the Wood to expand during the main combustion period.

While the templet may vary in construetion, in the embodiment here illustrated as an example, it comprises a V-shaped wooden frame or form 20, the legs of the V being connected at the top by two spaced straps 21 which define a groove at the bottom of the furnace pool. The outer edges ol the V merge into straight lines corresponding to the sides of the hearth. as appears in Fig. 1. The inner edges of tbe V merge into a curve which is continued by the bottom edges of the straps 21, this curve corresponding to the rounded portion of the furnace bottom at the bottom of the hearth.

The whole frame is somewhat the shape of' bore is so dimensioned that at the longitudinal lines where the bore most Closely approaches a tangential relation with the faces 23, 24, of the form, there is left a relatively thin double wall Q5, strong enough to hold the templet rigid under tamping pressure but thin enough to burn through easily. This Wall runs around the V, including the straight extensions, in a line, or rather a strip, located .substantially midway of the end edges 26, 9.7 of the form and thus, in effect, connects tuo form halves separated by a longitudinal plane.

ln the embodiment illustrated, the bore 22 serves also as a conduit for a resistor strip or wire 28 which is threaded through the bdr'e. and has its ends extending outwardly aty the top il) for connection in a .snitable circuit.

At opposite sides ot' bore Q2 are other channels or bores 29. 3l), for the passage of an air or oxygen blast to aid combustion.

In use, the templet is suitably positioned and the refractory material is taniped about, the same totorm the furnace lining. During this tamping the. form is rigid and ivithstands tamping pressure so as to constitute a proper pattern for the. channel desired. After a proper setting period. the resistor strip 28 is connected in circuit and the heat set up therein heats the. wooden torm to the oint of combustion. Owing to the fact that the double Wall is relatively thin and Weak and near the source of heat, it burns through during the initial stages of combustion, This. in effect, separates the form into two longitudinal parallel parts collapsible one toward the other. This separation takes place before the form as a whole heats np sutiiciently to exert any substantial expanding pressure on the furnace lining. As a result, the tendency to expand is taken up by the collapse or inward movement of the separated .form parts and injury to the lining is avoided. Bv continued combustion, which, may be aided by an air blast, the form is destroyed and the furnace Channel made ready for use.

that claimed is:

l. A tel'nplet for the purpose described, providing a pattern having substantially the shape of theahannel to be formed and eapacitated to be destroyed by the applica` tion of heat, and having a portion running longitudinally around the templet between tluend edges and eapacitated to be destroyed by heat relatively rapidly with respect to the pattern as a whole, whereby upon application of heat the templet is relatively early divided int-o two parts movable one toward the other.

2. A tem let for the purpose described, composed o wood and providing a pattern having substantially the shape of the channel to be tormed, and having a portion extending around the body of the templet between the edges thereof and arranged, upon Combustion, to burn out relatively rapidly with respect to the combustion of the form al large, thereby to divide the tem let into two parts movable one toward t e other prior to the major combustion.

il. A templet for the purpose described, composed ot' wood and providin a pattern having substantially the shape the chan nel to be formed. and having, substantially midway ot its end edges, relatively thin portions in the inner and outer walls, whereby upon `combustion such thin portions burn out relatively rapidly with respect to the combustion of the attern at large, thereby to divide the temp ct into two parts niet" able one toward the other prior to the ma combustion.

l. A templet for the purpose describri, composed ot' wood and providin a patte"-` having sul'istantially the Shape 01% the chafa nel to he formed, and having substantially' midway ol its end edges a bore running around the body of the templet and forming relatively thin portionsin the inner and outer walls, whereby upon combustion Such thin portions burn out relatively rapidly with respect t0 the combustion of the pat.- tern at large. thereby to divide the tem let into two parts movable one toward the ot er prior to the major Combustion.

5. A teni let for the purpose described, composed o Wood and providing a pattern having substantially the shape. of the chan nel to be formed, and having substantially midway of its end edges a bore running around the body of the templet and forming relatively thin portions in the inner and outer wells, whereby upon combustion such thin portions will burn ont relatively rapid ly with respect to the combustion of the pattern at large'.Y therebyto divide the templet into two parts movable one toward the other, and supplemental bores on either side of said first named bore.

6. The method of making the refractory structure of an electric furnace having an interior channel, which comprises forming 'a pattern having the shape of the channel to be formed, tamping refractory material about said pattern. causing a portion of Said pattern, in a dividing strip-runningr longitudinally around the body thereof, to be destroyed, whereby the pattern is divided into two portions movable one toward the other, and destroying the remainder of the pattern.

7. The method of making the refractory Structure of an electric furnace having an interior channel, which comprises forming a pattern haring the shape of the channel to he formed and having a bore running lon itndinally around the pattern t0 form re atively thin side wall portions substantially midway of the ends. tamping refractory ma.- terial about said pattern, applying lieat to the pattern to burn through said Wall ortions, wherebythe pattern is dividedhnto two portions movable one toward the other, and further Supplying heat t0- burnthe remainder of the pattern.

In testimony whereof, I have hereunto set my hand.

DAVID L. sUMM'EY.

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