US2362823A - Base block for crucibles or the like - Google Patents

Description

Nov. 14, 1944.

G. T? HUBBELL Filed Dec. 10, 1942 BASE BLOCK FOR CRUCIBLES OR THE LIKE Patented Nov. .14, 1944 BASEBLOCK Foe CRUCIBLES-OR THE-LIKE f George-T. Hubbell, West Haven, Conn, assignor UNITED sTArE to American Crucible Company, Shelton, Conn a corporation of Delaware i ApplicationD ecember 10; 1942, Serial No; 468,533

w 4 Claims.

This'inventionrelates to base blocks for. crucibles, and more particularly to a supporting device for a crucible to support the latter Within a furnace so that it will be efficiently and evenly willbe permitted toenterthe spaces betweenthe supporting members and attackdirectlythe bott'omof the crucible.

Still another object of the invention is the heated, particularly over the bottom portion 5 provision of afbasev block for crucibles provided thereof, while at the same time the flame of the with a solid base portion and. a pluralityof upburner will not be permitted to contact the botstanding supp r n mem r t r such that tom of the crucible directly. when a crucible is supported on the supporting crucibles employed in foundry work are commembers the furnace flame Will not enter the posed of a material which may be approximately s e between the supporting m r wh fifty percent graphite and the remainder silicon e flame is pp to the furnace in one i carbide and clay. Usually the side walls. of the t o u l tend to Cause the flame to enter crucible are glazed with a flame-resisting mathespaces tw n the ppor i g member wh n terial, but the-bottom i'sl'eft unglazed. For this the base block is inverted and the crucible is reason it is not desirablethat the flame contact Supported u n h as p t nv f t e blockthebottom of the crucible directly, or-the graphite these a other e the invention 00 will b oxidized, i sists in thenovel features and "combinations of It is,however, desirable that thebottom of the parts hereinafter described a d a medcruciblebe evenly heated, andparticularly that i the accompanying drawing: it beheated to the same extent .asthe side walls 1 i nal V e Of a furnace and a so that unequal expansion and cracking ofthe crucible supported 9 base block embodyingcrucible will not result. It has been proposed my'ihvehtien; in the past to place the crucibles on supports 2 i a seetionelview On line of which have a solid top portion, thus preventing- 'Fig-3-is a -P a View f the a e b c the flame from contacting the body of the cru- Fig-4 is a Side ew Of the block; and cible. ,Such a support :or base block, however, a Sectional V On f F does not permit the hot gases from the flame to To illustrate a pre e e embodiment of y contact the bottom for the crucible, but rather invention, a sh wn in a conventional mantends to insulate thisportion of the crucible from e a u a 9 having a linin l l and a botthe heated gases so that it does notreceive-as tom portion l2, which parts H and I2 will normuchheat as theside walls. This not only does mally be e of refractory a eria The Wa l notlaccomplish effective melting of the material Ofihe lining ll maybe provided han openirig in the crucible, .but heats the latter unevenly 7 own in'dotted'lines in Fig. and y be ith d i bl resume observed that this opening is obliquely formed o object of the present invention is the prointhe wall of the crucible so that the flame from vision of a base .block ior crucibles which'will h burner nozzle placed in h penin will' per itth hot. gases of th furnace flame t directed substantially tangentiallyto the space contact directly withthe bottom of the crucible, between the ace lining and the supp but at the same time will prevent the flame itblock, he l e he einafter described. self fromcontacting thisportion of the crucible. 40 Within the u ace is disposed a crucible 14 Another obj ctof th i v nti .1 th proviwhich rests on -a base block I5, there being a sufiision of a base block for crucibles so formed that Ciehli annular Space remaining etween the side the bottom of the crucible will be subjected Wall of the furnace and the crucible and block directly to the hot gases of the flame for efficient 11 which it will be n from g- 2, ti b t 111 t be ubjected t t fl the opening 13 is directed substantiallytangenitself,thus preventing oxidation of the material tielly o t b ock l5 so as'to direct the flame of whichthe cr cibl is de, around the block in the space between the lat- .Astillfurther objectof :theinvention is the ter and the furnace lining. I provisionoi a base block for crucibles comprising The baseblock l5 iS-made 0f ytea low rbase' portion having. thereon a plurality rial so as to Withstand the heat of the flame, and of upstanding spaced supporting members so comprises abaseport ion [6, which, inthe form of formed that when the flame is applied to the my invention shown, is substantially circular in block in one direction, forexarhple, azclockwise shape,.anda..plurality-of upstanding supporting direction it will tendtopassaround the exterior 7 members I1, there being four of these members, of.;.theblock,'whi1e;the. hot.gases..-from theflame, 56 asshown in the -drawing, although the exact number is not material. It will be noted that these members are spaced from each other both at the center of the base block [6 and also between the side walls of the supporting members, as shown at I8, so as to permit the hot gases from the flame to enter the spaces l8 and circulate freely therethrough in direct contact with the bottom of the crucible M.

The members I! are curved from their inner portions outwardly, and particularly at their outer end portions, so that the flame entering the space about the block through the opening I3 will tend to be directed about the periphery of the block and restrained from entering the spaces l8, so that the flame will not come in contact with the bottom or base of the crucible. As shown in Fig. 2 of the drawing, the flame is directed in a clockwise direction, and correspondingly, as shown in Fig. 3, the elements H are so shaped that when the flame tends to pass around the base block in a clockwise direction it will continue in this path and will not be deflected through the spaces Hi. If it is desired to use a similar block with a furnace in which the flame is directed in a counter-clockwise direction, the elements 11 would be reversed with respect to their direction of curvature shown in Fig. 3.

While the exact shape of the member I! is not important in all aspects of the invention, I have found that a very eflicient structure results when both of the lateral surfaces of these elements are formed along the arcs of curves. For example, as shown in Fig. 3, the shorter wall ab of one of the members Il may be formed on the arc of a curve having its center at c, which center is midway between the ends of a radius :r--.r of the base block [6. The radiu of the arc a--b which has been chosen is one half that of the radious of the block, so that if the curve a-b were continued it would pass through the center of the block, and also be tangent to the periphery of the block. The longer wall of the member H is formed of a similar curve d--e having its center at the point ,1 on a radius :cy 60 from the radius on which the point is located, this curve having the same radius as the curve w-b. However, from the point e the wall is continued to the point 9/, following the periphery of the base portion Hi from the point e to the point 9. A suitable opening is left between the inner ends of the members at the center at of the base portion l6, and the ends of the members I! are rounded off, the curves of the ends merging into the two curves of the side .walls, as explained above. This forms these supporting members of a substantially tear-drop shape, so that they will tend to cause the flame directed into the space between them and the furnace wall to sweep around their outer peripheries instead of passing into the spaces between them. The face a-b of the next supporting member I! is formed about a center on a radius :r-z, which radius is at an angle 39 to the radius :ry, and this process is continued about the block. Preferably the upstanding supporting members I? are formed integrally with the base portions thereof, although this is not imperative. It is, however, desirable to have them secured to the base portion It so that they will always occupy the proper positions with respect to the block and with respect to' each other to prevent the flame coming in contact with the bottom of the crucible.

In some instances it is desired to have the crucible supported upon a solid base, but to provide for the flame, even if tangentially directed, to enter below this base so that the bottom of the crucible will be evenly heated and the base itself will prevent the flame from coming in contact with the bottom of the crucible. To eflect this result it is merely necessary to turn the base block illustrated upside down with respect to the position shown in the drawing herein. When the base block is thus reversed, the crucible will rest upon the solid portion IE, and the direction of the curvature of the supporting members I! will in effect be reversed. That is, the outer ends of these members will point in a direction opposite to that shown. As will be clearly seen from Fig. 2, a flame entering through the opening 13 when the base block is inverted will tend to enter the spaces l8 between the member H, and thus pass directly below the base portion I6, heating it evenly and likewise heating the bottom of the crucible evenly and efiiciently. Therefore, whether the 'particular operation which is to be carried out is best served by having the flame pass around the base block, or pass through the spaces below the block, either effect may be accomplished by using the device illustrated in upright or inverted position, while in either position the bottom of the crucible is evenly heated and the flame is prevented from coming in direct contact therewith.

The base block will be made of a suitable refractory material to withstand the high temperature of the burner flame, and will usually be made of a silicon carbide clay-bonded refractory material, although its particular composition is not of importance in all aspects of the invention.

While I have shown and described a preferred embodiment of my invention, it is to be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within thespirit of the invention and within the scope of the claims.

What I claim is:

1. A base block for supporting crucibles or the like in the heating chamber of a furnace, comprising a circular base portion having upstanding spaced supporting members on one face thereof, each of said members extending from a point adjacent the center of the base portion to a point adjacent the periphery thereof, and said members being correspondingly curved adjacent their outer ends to direct a flame around the outer ends of said members when said flame is directed around the block in one direction and to cause the flame to enter the spaces between said members when the flame is directed around the block in the opposite direction, said block being adapted to rest freely on the floor of the heating chamber and being reversible in position to rest either on the base portion or on said members.

2. A furnace comprising a heating chamber having, adjacent the base, a tangentially disposed burner inlet opening, a base block adapted to support a receptacle for the material to be heated, and resting freely on the floor of the chamber and reversible top for bottom thereon, the periphery of said block being spaced from the wall of the chamber opposite to said opening, said block comprising a base portion having spaced upstanding receptacle supporting members thereon, and said members extending from a, point adjacent the center of the block to the periphery thereof and having their outer ends ,side wall convexly curved and the opposite side curved in a direction to cause the flame to pass around said members when applied to the block in one direction and to enter the space between said members when applied to the block in the opposite direction.

3. A furnace comprising a heating chamber having, adjacent the base, a tangentially disposed burner inlet opening, a base block adapted to support a receptacle for the material to be heated, and resting freely on the'floor of the chamber and reversibletop for bottom thereon,

the periphery of said block being spaced from the wall of the chamber, opposite to said opening, said block comprising a base portion having spaced upstanding receptacle supporting members thereon, said members extending from a point adjacent the center of the block to' the periphery thereof and having their outer ends curved ina direction to cause the flame to pass around said members when applied to the block 20 in one direction and to enter the space between said members when applied to the block in the opposite direction, and said members having one wall concavely curved.

4. A base block adapted to be inserted in and removed from a circular furnace chamber having a substantially tangentially extending burnv eropening, said base block being adapted to support a receptacle for material to be heated and substantially coaxial therewith, and comprising a circular disc portion and a plurality of flanges on,one face thereof, said flanges being spaced apart at the center of said block and along their lengths, the opposed surfaces of said flanges defining passages with their outer ends facing substantially tangentially of theblock, whereby.

when said block is inserted one side up in said furnace opposite to said burner opening, the flame from said burner opening" will in part enter said passages, and when said block is inserted the other side up, substantially all of the flame will tend to flow past the outer ends of the passages without entering the same.

GEORGE T. HUBBELL.

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