US3620522A

US3620522A - Disposable liner

Info

Publication number: US3620522A
Application number: US27393A
Authority: US
Inventors: John B Bridges
Original assignee: Cameron Iron Works Inc
Current assignee: Cooper Industries LLC
Priority date: 1970-04-10
Filing date: 1970-04-10
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16

Abstract

A disposable liner for accumulating deposits of alloy splashing up from the molten alloy in an induction heating furnace comprises a sleeve which fits closely within the upper portion of the furnace crucible and is supported therein by asbestos-covered chains which loop over studs about the upper end of the crucible.

Description

I United States Patent 3,620,522

[72] Inventor John B. Bridges [56] References Cited 2 UNITED STATES PATENTS 9Y 1 3 1970 663,945 12/1900 Waldburgeret a1. 266/43 p 1,795,935 3/1931 Davis 13/27 [45] Patented Nov. 16, 1971 2 997 512 8/196] Tama 131/27 [73] Assignee Cameron Iron Works, Inc.

Houston, Tex. v FOREIGN PATENTS 2,007,341 l/1970 France 266/1 R Primary Examiner-Gerald A. Dost Attorney-Hyer, Eickenroht, Thompson & Turner [54] DISPOSABLE LINER 10 cmmsa Drawing Figs ABSTRACT: A disposable liner for accumulating deposits of [52] U.S. Cl 266/43, alloy splashing up from the molten alloy in an induction heat- 266/15, 266/39, 13/1, 13/27 ing furnace comprises a sleeve which fits closely within the [51] Int. Cl C2lc 5/02 upper portion of the furnace crucible and is supported therein [50] Field of Search 266/1 R, l by asbestos-covered chains which loop over studs about the upper end of the crucible.

PATENTEmmv 1s IHTI 3. 620.522

/ UUUOU (.WXXXX) UUUUU s John B. Bridges IN VE N TOR BY fM i W ATTORNEYS DISPOSABLE LINER This invention relates to an improvement in induction heating furnaces used in combining at high temperatures metallic elements to produce alloys.

Induction heating requires a furnace having a crucible whose inside wall is made of refractory material in order to withstand the very high temperatures of the molten alloy. induction heating is accomplished by energizing coils carrying high currents which electromagnetically induce secondary currents in the metals thereby producing extremely high temperatures within the crucible. One of the advantages of induction heating is the absence of direct contact between the heating unit, the energizing coils, and the molten alloy, thereby producing alloys of greater purity. The purity is further enhanced by melting the elements in a vacuum which prevents contamination from air and removes gases dissolved in the molten alloy.

However, induction heating furnaces present at least one significant problem which reduces the efficiency of the alloyproducing process and increases its cost. During a heating cycle, commonly called a heat or melt, agitation at the surface of the molten alloy causes splashing onto the crucible wall above the surface of molten alloy. Because of the relative coolness of the upper portion of of the crucible wall above the surface of the molten alloy, the splashed alloy solidifies into large deposits called "skull." The deposits accumulate in such quantities that after only a few heats, the crucible becomes clogged to the extent that the raw materials for additional heats cannot be freely dumped into the crucible. The only portion of crucible wall free of skull is the area between the pouring spout of the crucible and the molten alloy. Pouring of the molten alloy melts and carries away skull which might be deposited in this area.

in the past, these deposits of alloy have had to be removed by mechanical means such as chipping tools or by use of an oxygen torch. During these rather crude removal processes, the refractory material forming the crucible wall has been damaged. Also, of course, these crucibles are quite large, often several feet in diameter, and removal of the alloy deposits causes a significant amount of furnace down" time and manpower. Furthermore, the damage to refractory material which occurs duringthe skull removal shortens the number of operating hours of the furnace, thereby precipitating losses in production time and increased manpower for furnace rebricking.

An object of this invention is to avoid these problems, and, more particularly, to provide a simple and inexpensive means of preventing this accumulation of alloy upon the crucible wall.

This and other objects are accomplished, in accordance with the illustrated embodiment of the invention, by a disposable liner comprising a sleeve which fits closely within the upper portion of the crucible and is supported therein by chains with its lower edge slightly above the surface of the molten alloy. In this position, the sleeve accumulates deposits of skull thereon, and may be replaced from time to time with another liner, thereby obviating the need for removing the skull from the crucible wall.

In the drawings where there is shown, by way of illustration, one embodiment of the invention:

FIG. 1 is a perspective view of the disposable liner;

FIG. 2 is a vertical sectional view of the liner sleeve supported in the furnace crucible and showing skull accumulated upon the sleeve; and

FIG. 3 is a sectional view of the crucible showing a relief in the sleeve adjacent to the pouring spout of the crucible.

With reference now to the above-described drawings, the furnace crucible, indicated at in FIG. I, has a lining of refractory material 11, such as brick, and has heating coils thereabout, including coils 12 in the proximity of the area inside the crucible where the metallic elements are to be melted, and

cooling coils

13 and 14 above and below the heating coils 12. The secondary currents induced in the molten alloy by the heating coils 12 cause turbulence at the surface or melt line 15 of the molten alloy, which turbulence is compounded when the furnace is operated in a vacuum. Due to the turbulence, molten alloy is splashed up above the melt line; and, because the area above this line is cooled below solution temperature by the cooling coils l3, deposits of alloy or skull would accumulate on the refractory wall of the crucible were it not for the liner of the present invention.

A pouring spout 16 located in the upper edge of the furnace crucible is made of refractory material so that the molten alloy may be poured from the spout at the end of a heat. A retaining ring 17, with upstanding studs 18, is fastened to the refractory materials forming the top edge of the crucible.

The liner is composed of a sleeve 21 made of a relatively inexpensive material such as A.l.S.I. 1010 plain-carbon steel, which will withstand the heat of the melt and to which the skull will adhere. The sleeve is of a size to fit closely within the upper portion of the crucible with the lower end of the liner slightly above the surface of the molten alloy. In the preferred embodiment shown, the crucible is cylindrical in shape and therefore the liner is cylindrical, although it is to be understood that the liner may take other shapes, the important point being that the sleeve of the liner should conform to the shape of the crucible.

The sleeve is moved between positions remote from and supported within the crucible by means of eyes 22 which are welded onto the upper end of the sleeve in such a fashion that they extend above the sleeve so as to receive hooks on a crane or other lifting apparatus. A link of chain 23 is welded on each end to either side of each eye for looping over a stud 18 as the sleeve is lowered into place. Thus, each link is of sufficient length that the lower edge of the sleeve will be slightly above the surface of the molten alloy when the chains are taut. The chains are covered with electrical insulation such as asbestos. Although other means may be used to support the sleeve, these chains are preferred due to their simplicity, sturdiness, and ability to withstand the heats of the molten metal.

The sleeve is discontinuous in order to provide a relief 24 which is adjacent the pouring spout 16 when the sleeve is in place. Thus, as previously noted, although deposits of alloy form during the heat, the deposits in the area of the spout, and thus between the

edges

27 and 28 of the relief, are removed by the passage of the molten alloy over the refractory wall of the crucible to the pouring spout when the crucible is emptied.

Braces

25 and 26 connect the

opposing edges

27 and 28 of both sides of the relief 24 so that the sleeve is provided with greater rigidity as it is lowered into place by the crane or other lifting means. However, when the molten metal is poured from the crucible, the braces melt to allow the sleeve to expand into a closer fit within the crucible. An L-shaped flange 29 is welded around the bottom edge of the sleeve in order to provide further rigidity to the liner.

Before the beginning of the heat, the hooks of the crane or the like are attached to the liner by means of the eyes 22, and the liner is lowered by the crane into the crucible as operators guide it into such a position that the relief 24 will be opposite the pouring spout 16. As the liner continues to be lowered, the operators will loop the chains 22 about the studs 18 nearest to the chains, and after the crane completely sets the liner down to transfer its load to the studs, it may be detached from the liner and used elsewhere.

Deposits of alloy or skull will increase with each heat until they extend from the sleeve, as shown in FIG. 2. When these deposits become so large that the crucible cannot be loaded for the next heat, the liner is lifted from the crucible by at tachment of a crane or other lifting means to the eyes 22 for lifting the sleeve from within the upper portion of the crucible. Another liner may then be lowered into the crucible in a relatively short period of time, so that there is relatively little down time between heats. The removed liner with its accumulation of skull may be melted down to recover the alloy.

In a typical liner the diameter of the sleeve is approximately 84 inches and the height is approximately 40 inches. It is estimated that the weight of the deposits collected on each sleeve averages 5,000 to 6,000 pounds. The liner as well as the deposits of alloy may be recovered simply by melting them down in a later heat, thus making the liner entirely disposable.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A disposable liner for use in accumulating deposits of alloy splashing from the molten alloy within the crucible of a vacuum induction furnace, wherein the crucible has a pouring spout in the upper edge thereof, said liner comprising a sleeve, adapted to fit closely within the upper portion of the crucible, and means on said sleeve for supporting it within said upper portion of the crucible so that the lower end of the liner is slightly above the surface of the molten alloy, said sleeve being relieved to provide an opening adjacent to the pouring spout when said sleeve is so supported, said sleeve also having means thereon to which a lowering and lifting means may be attached for moving the sleeve between positions removed from and supported within the crucible.

2. The liner of claim ll, wherein said support means includes chains attached to the upper part of said sleeve for looping about studs spaced about the top of the crucible.

3. The liner of claim 1, wherein the attaching means includes eyes on the upper end of said sleeve to receive lifting hooks.

4. The liner of claim 1, wherein said support means includes chains attached to the upper part of said sleeve for looping about studs spaced about the top of the crucible, and the attaching means includes eyes on the upper end of said sleeve to receive lifting hooks.

5. The liner of claim 1, wherein the sleeve is discontinuous to provide the relief, and braces are connected between the edges of both sides of the relief in the liner.

6. A vacuum induction furnace for combining at high temperatures molten metals to produce alloys, comprising, in combination, a crucible having a spout in its upper edge for pouring the molten alloy, a liner having a sleeve adapted to fit closely with the upper portion of the crucible, means on said sleeve for supporting it within said upper portion of the crucible so that the lower end of the liner is slightly above the surface of the molten alloy, said sleeve being relieved to provide an opening opposite the pouring spout when said sleeve is so supported, said sleeve also having means thereon to which a lowering and lifting means may be attached for moving the sleeve between positions removed from and supported within the crucible.

7. The furnace of claim 6, wherein said support means includes chains attached to the upper part of said sleeve for looping about studs spaced about the top of the crucible.

8. The furnace of claim 6, wherein the attaching means includes eyes on the upper end of said sleeve to receive lifting hooks.

9. The furnace of claim 6, wherein said support means includes chains attached to the upper part of said sleeve for looping about studs spaced about the top of the crucible, and the attaching means includes eyes on the upper end of said sleeve to receive lifting hooks.

10. The furnace of claim 6, wherein the sleeve is discontinuous to provide the relief, and braces are connected between the eyes of both sides of the relief in the liner.

Claims

2. The liner of claim 1, wherein said support means includes chains attached to the upper part of said sleeve for looping about studs spaced about the top of the crucible.