US2793021A - Crucible for melting metal - Google Patents

Description

. May 21, 1957 I J. w. COURTNEY 2,793,021

CRUCIBLE FOR MELTING METAL Filed Oct. 25, 1953 INV TOR.

CRUCIBLE FOR MELTING METAL John W. Courtney, Dearborn, Mich., assignor to Electro Refractories & Abrasives Corporation, Buffalo, N. Y.

Application October 23, 1953, Serial No. 387,878

6 Claims. (Cl. 263-48) This invention relates to crucibles for metal melting or the holding of molten metal preparatory to pouring it into molds and particularly to a certain shape of crucible and to means for producing a crucible of this shape. The invention is applicable to crucibles made of the socalled clay graphite type of material but is particularly valuable in connection with carbon-bonded crucibles of the type specified in Patents Nos. 1,356,939 and 1,458,726 to John L.Ohman. It relates to crucibles which are removed from the furnace for pouring the metal, rather than to those which remain in place in a tilting furnace during pouring.

Hitherto such crucibles have, in general, been made cylindrical or somewhat barrel-shaped. When metal is ready for pouring, the crucible is removed from the furnace in a set of tongs and taken to the place where the metal is to be cast, after which the molten metal is poured out either through a small notch cut in the top of the edge of the crucible or a relatively small pouring lip formed at the top on one side. In any case it has been very difficult to pour a small stream of metal or to place the poured stream accurately with respect to a mold. Also at the conclusion of the pour, the crucible tends to dribble semi-molten metal which has chilled excessively due to the time required to manipulate the crucible cautiously, thus making some of the metal unfit for casting until it is remelted. The objections to operations using pots of the old shape have been realized for years but no feasible method has been known for obviating these difiiculties until the advent of my invention.

It is, consequently, an object of my invention to provide crucibles with lips of improved construction to control the flow of metal much more accurately both with respect to positioning of the stream and volume of metal poured. If desired, I am able to pour metal rapidly but on small items pouring can be far slower and more accurate than with former practice. I find also that with crucibles of my design it is possible to end the pour with less dribble of metal which is wasted.

It is another object of this invention to provide a crucible with a nozzle which is so constructed that as the metal is poured out of the crucible, the balance of weight of the crucible is approximately maintained.

Other objects and advantages will be apparent from the following description of one embodiment of the invention and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

In the acompanying drawings illustrating by way of example one embodiment of my invention:

Fig. 1 is a side elevation of a crucible embodying this invention.

Fig. 2 is a top plan view thereof.

Fig. 3 is a fragmentary horizontal sectional view thereof, on line 33, Fig. 1.

In carrying out my invention, I spin a barrel-shaped crucible or melting pot in the old way and bake and glaze I ited States Patent 2,793,021 .lce Patented May 21,- 1957 it in the usual manner. I make the lip separately of materials similar to the pot and fire it in the same way. I thereafter cut the pot to receive the lip as will be explained below, after which I join the two together with suitable plastic refractory cement. Thereafter the crucible with the lip attached is dried out and fired to a suitable temperature such as 2400" F. to vitrify the cement and make the crucible and lip into a single integral body.

5 represents a crucible of ordinary or usual shape to which I have applied my improved pouring lip 6.

I have found it desirable that the portion of the lip through which the metal flows be of relatively sharp V-shape, such that the angle A in Fig. 2. is not materially greater than 60 degrees. Preferably the lip is so formed that the angle B from the top of the nozzle to the forward edge thereof, Fig. l, is approximately from 45 to 60 degrees. I have also found that the height of the lip, indicated at h in Fig. 1, should be from at least onethird and up to as much as one-half of the overall height of the crucible. This sharp V-shape of the lip is particularly important at the pouring or discharge end of V the lip and, if desired, the part of the lip which is attached to the crucible may be of some other shape, but for the sake of simplicity in forming the lip and in cutting the notch in the crucible to receive the lip, the V-shape with substantially flat sides is advantageous. It is also desirable that the lip extend outwardly beyond the top edge of the crucible to an extent equal at least to onethird of the outside diameter of the upper end of the crucible. In other words, the ratio of the diameter D, Fig. 2, to the overall lip length L should be not greater than 3 tol.

In applying a lip to a crucible in accordance with my invention, a template is preferably formed having the same form as the part of the lip which is to be secured to the crucible. This template is held against the edge of a crucible and anotch is sawed or otherwise formed in theside thereof at such an angle that the notch at the inner surface of the crucible is of greater width than at the outer surface of the crucible. Very satisfactory results have, for example, been obtained by cutting the notch in the crucible so that the sides of the notch extend approximately in the same direction as the outer side surfaces of the lip. Also clearly shown in Fig. 1, this manner of cutting the notch results in the depth of the notch on the interior of the crucible being greater than the depth of the notch on the outside surface thereof.

The lip at the portion thereof adjacent to the crucible is grooved, thus forming faces 9 which are inclined to fit the sides 7 of the notch, and a shoulder 10 which will seat against the exterior of the crucible adjacent to the notch cut therein. Consequently, when the lip is in position on the crucible, the portion 9 of the lip will seat against the cut surface 7 of the crucible, and the shouldered portion 10, seating against the outside wall of the crucible in conjunction with the groove 9, will result in a mounting for the lip which is self-supporting when the lip is set in place in the notch of the crucible. The shoulder 10 will prevent the lip from slipping too far into the crucible. By making the inner width of the notch and the lip greater than the width of the notch at the outer surface of the crucible, the lip is held against slipping outwardly with reference to the crucible. Consequently, the lip is self-supporting on the crucible, even before it is cemented in place, and will be held in its correct position on the crucible by gravity when the crucible is in upright position.

When the lip has been fitted to enter into the notch of the crucible, a thin layer of cement is applied to the contact edges of the lip and crucible and the assemblage is then dried and fired as hereinbefore stated. While the composition of the cement is not a part of this invention, a suitable cement for this purpose may be made by mixing together 80 parts by weight of 4-0 and finer mesh SiC; 5 parts of flake graphite; 15 parts of a plastic fireclay; 2 parts of borax and 2 parts of dextrine. This cement should be mixed with water to a plastic condition and then applied to the contacting surfaces of the parts to be joined.

As before stated, a crucible provided with a pouring lip as herein described is easier for a workman to handle than crucibles as heretofore made. This is due to the fact that with my improved crucible as shown, when loaded with molten metal, the center of gravity during the pouring of the metal tends to shift unusually far over toward the lip and also high up in the crucible, as far, for example as the point P, Fig. 1. This makes the crucible easier to manipulate than when the center of gravity goes continually lower down in the crucible as the same becomes empty as with prior crucibles, so that the center of gravity may be at the point Q, Fig. 1. These crucibles during the pouring are held in tongs in such a manner that the center of support by the tongs in all cases remains at a point, such as R, on the center line of the crucible. It will thus be readily seen that a crucible with the center of gravity at P will be much easier to tilt for pouring metal therefrom than a crucible with the center of-gravity at the point Q.

In the manufacture of these crucibles, the lip 6 is generally attached to thecrucible at the factory in which the crucible is made, but if desired, the lips may be applied to the crucible by the customer.

It will be understood that various changes in the details, materials, and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention, as expressed in the appended claims.

I claim as my invention:

1. As an intermediate article of manufacture, a crucible for containing molten metal and a lip for discharge of the molten metal therefrom, said lip having two sides arranged in angular relation to each other, the height of the lip being at least equal to one-third of the height of the crucible, said crucible having a notch cut therein into 1 Which said lip fits, said notch having the edges thereof on the interior of the crucible of greater width than on the exterior thereof, said lip having the edge portion thereof which cooperates with said notch formed with a shoulder formed to abut against the exterior wall of the crucible, for holding said lip in correct relation to said crucible by gravity when said crucible is in upright position.

2. A crucible according to claim 1, in which said lip has the sides thereof adjacent to its discharge end arranged at an angle to each other of not more than 60 degrees.

3. As an intermediate article of manufacture, a crucible for containing molten metal and a lip for discharge of the molten metal therefrom, said lip having two sides arranged in angular relation to each other, the height of the lip being at least equal to one-third of the height of the crucible, said crucible having a notch cut therein into which said lip fits, said notch and the part of said lip which engages said notch being provided with interfitting edges which hold said lip and crucible in correct relation to each other by gravity when said crucible is in upright position.

4. A crucible according to claim 3, in which the angle between the sides of said lip adjacent to the discharge end thereof is not more than 60 degrees and in which the height of said lip is at least one-third of the height of the crucible.

5. A crucible according to claim 3, in which the angle between the sides of said lip adjacent to the discharge end thereof is not more than 60 degrees and in which the height of said lip is at least one-third of the height of the crucible, and in which the lip extends outwardly be yond the edge of the crucible to a distance equal to at least one-third of the external diameter of the top of the crucible.

6. As an intermediate article of manufacture, a crucible for containing molten metal and a V shaped lip for attachment thereto, said crucible having a V shaped notch cut down from the edge thereof to receive said lip, said notch having the edges thereof further apart on the inside than on the outside of the crucible and said lip having an undercut outer edge which provides a shoulder to abut the outer face of the crucible when the lip is positioned within said notch.

References Cited in the file of this patent UNITED STATES PATENTS 259,282 Bavier June 13, 1882 553,055 .Coughlin Jan. 14, 1896 612,134 Levoz Oct. 11, 1898 854,551 Allen May 21, 1907 1,673,115 Hauman June 12, 1928 2,099,043 Wicklein Nov. 16, 1937 2,362,823 Hubbell Nov. 14, 1944 2,650,255 Hogel et a1. Aug. 25, 1953 FOREIGN PATENTS 495,247 France June 21, 1919

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