US2745151A

US2745151A - Method and apparatus for continuous casting

Info

Publication number: US2745151A
Application number: US393666A
Authority: US
Inventors: Joseph B Brennan
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-11-23
Filing date: 1953-11-23
Publication date: 1956-05-15
Anticipated expiration: 1973-05-15

Description

May 15, 1956 J. B. BRENNAN 2,745,151

METHOD AND APPARATUS FOR CONTINUOUS CASTING Filed Nov. 25, 1953 3 Sheets-Sheet l mu wlllllllim lllllz 1 IN V EN TOR.

1 III/11114 May 15, 1956 BRENNAN 2,745,151

METHOD AND APPARATUS FOR CONTINUOUS CASTING Filed Nov. 25, 1953 3 Sheets-Sheet 2 2lu l3 h] L .25 (MW INVENTOR.

I60 i i' ll- BY y 5, 1956 J. B. BRENNAN 2,745,151

METHOD AND APPARATUS FOR CONTINUOUS CASTING Filed Nov. 25, 1953 5 Sheets-Sheet 3 INVEN TOR.

United States Patent METHOD AND APPARATUS FOR CONTINUOUS CASTING The present invention relates generally as indicated to amethod and apparatus for castingand more particularly to the continuous casting of metals or other materials which are capable of being rendered molten by application of heat and which solidify or set upon cooling thereof. The present application is a continuation in part of my co-pending U. S. application Serial No. 201,171 filed December 16, 1950, now abandoned.

It is a primary object of this invention to provide a method for continuous casting which involves the steps of downwardly moving a mold, open at its side, through or against a pool of 'moltenfmaterial whereby the cavity in the mold is continuously filled with the molten material without entailing the usual pouring operation; and then the mold is passed through a cooling zone which bridges the mold side opening and which cools the mold and the material therein, whereby,the material is solidified to shape-retaining form. The solidified material thus constitutes a closure for the mold, and the portion of the mold which .is bridged in the cooling zone provides a closure to retain the molten material in the mold cavity while the latter is moving from the casting or filling zone to the cooling zone.

It is another object of this invention to provide apparatuses by which the foregoing method can be practiced.

With the foregoing objects and advantages of the present invention in mind, it .is evident that a striking distinction from prior methods and apparatuses for casting is the absence of the usual pouring operation. The elimination of the pouring operation eliminates oxides in the material and also eliminates the necessity of providing elaborate control equipment. for regulating the relative positions of a pouring crucible and a downwardly traveling mold: as is characteristic of certain prior art appa ratuses and methods. Furthermore, the elimination of the pouring of molten material into a mold cavity permits the molten material in the supply crucibleto become degassed, that is, bubbles of gas can be expelled and therefore are not trapped in the continuous casting, as is the case where'molten material, is poured into a mold cavity.

More specifically, in my method and with my apparatuses, the casting operation is achieved by the molten material in a pool or crucible seeking its own level by flowing into an'open-side, downwardly traveling mold,

thus renuiring neither a.close regulation of the speed of the mold nor of the rate of fl o w of the molten material. Stated in another way, the molten material is notpoured into the downwardly moving mold cavity but, to the contrary, the portion of the cavity which at any instant is within the supplycrucible or passing adjacent thereto and in communication with the molten material therein is, in effect, aunitary part of the crucible. Therefore, regardless of variation of speed of the mold over a 'wide range, the cavity portion thus in communication with the pool'of molten material remains fullup to thelevel of the molten material in said pool or crucible. Therefore,

no pouring isinvolved in the casting operation. The primary reqirement is that an adequate supply of molten "ice material be provided in the crucible preferably in an amount such as to maintain a substantially constant level. I Otherobjects and advantages of the present invention will become apparent as the following description proceeds. p

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully describedand particularly pointed out in the claims, the followingdescription and the annexed drawings settingforth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings: H I

Fig/l is a side elevation view, partly in section, of one form of apparatus for carrying out this invention;

Fig. 2 is a transverse cross-section view through the drive means for ,the open side mold, such cross-section having been taken substantially along the line 22, Fig. l;

Fig. 3 is a side elevation view partly in cross-section of another form of apparatus for carrying out this invention;

Fig. 4 is a cross-section view somewhat similar to Fig. 2, such cross-section having been taken substantially along the line 44, Fig. 3; and

Figs. 5 to 8 are transverse cross-section views of several different types of molds which may be employed.

' Referring now more particularly to the drawings, and first to Figs. 1 and 2 thereof, the molten material 1 which is' to be continuously cast is contained in a ceramic crucible, said crucible being provided with a valve 3 which is adjustable to regulate the discharge of molten material 1 .from the outlet spout into another crucible 5.

Said crucible 5 is formed with an overflow notch so as to maintain a predetermined level of the molten material therein, the material which overflows above such predetermined level being discharged into an overflow trough 6 or the like for return back into the storage crucible 2.

The crucible 5 is here shown as being of generally funnel sh'apeand is formed around its lower end with a cooling die 7. which is cored as shown for circulation'of co'oling'medium therethrough. The reference numeral 8 denotes a supply pipe for coolingrnedium, which medium for most purposes may be cold water.

In the form of the-apparatus illustrated in Figs. 1

and 2, the mold comprises concentric sections 9 and '10 the arrow. so that a portion thereof passes downwardly through the crucible 5 and through the adjacent cooling die 7. As evident, when said moldis passing through the crucible 5, the molten material continuously flows into servesto bridge the open side of the mold cavity as it passes downwardly through said cooling die. The cooling die 7 is effective to cool the mold and the material cast thereinto so that the latter assumes a shape-retaining 7 form, herein a rectangular cross-section strip of thickness corresponding to the gap between the mold sections 9' and 10 and of a Width corresponding to the width of the opposite spaced apart flat faces of said mold sections.

The casting as it is continuously formed and while yet in rather'highly heated state is designated by'the reference numeral 17 in Fig. 1 and is shown as being continuously withdrawn from the mold cavity 16 and wound around a drum or spool 18 which is journalled in a stand 19 and which is rotated to wind on the strip 17 as by means of the crank 20 of said drum.

in order to maintain the

mold sections

9 and 10 in proper spaced relation, there is disposed between the pairs of

guide rollers

11 and 12, rods 21 on which are mounted for rotation the balls 22, the ends of said rods 21 being anchored in the brackets 23 on which said

rollers

11 and 12 are journalled, the reference numeral 24 being the oppositely extending trunnions of said rollers. The gear 13 previously mentioned is keyed or otherwise nonrotatably mounted on an extension 25 of one of the trunnions 24.

In addition to the cooling effect of the coolingdie 7 as resulting from the circulation of coolant therethrough, cooling sprays 26 may be used to further chill thecasting upon emergence from the die 7, the cooling sprays being located at the point where the strip 17 or other shape emerges from said die.

The storage crucible 2 which has already been referred to has located therebeneath a gas furnace 27 or the like which heats the molten material and maintains the same at the proper fluidity for discharge into the crucible 5 and for flow into the mold cavity.

Ahead of the crucible 5 and die 7 is a container 28 through which the mold passes for coating the mold cavity surfaces with a parting compound or ceramic coating material 29. The mold seections 9 and lll'are coated with a smooth surface of the material 29'as' the sections pass through said container 28. When the thin coating of the material 29 has been applied to the

mold sections

9 and 10, and after such coating has been set'or cured and dried and baked, said

sections

9 and 10 advance through the pool of molten material 4 in the crucible 5 to accomplish the casting operation without pouring. Then, of course, the cast material is solidified to shape-retaining form to provide a plug for the material thereabove. The aforesaid'treatment of the coating maybe elfected by an application of heat, not shown, or as a matter of fact, the coatings may be so treated by the action of the heat from the molten material 4. The

mold sections

9 and 10 may pass successively through several such containers 28 containing suitable material 29 and also through a series of heating zones to build up the desired thickness of such coating.

One of the brackets 23 mounting the pair of

rollers

11 and 12 adjacent said die 7 is equipped with a guide roll 30 over which the strip passes as it is withdrawn from from the mold cavity.

The form of apparatus illustrated in Figs; 3 and 4 is quite similar to that of Figs. 1. and 2, and therefore like reference characters have been used to designate the same or similar parts in the two apparatuses. Accordingly, repetition of the description and operation is believed unnecessary.

In the Figs. 3 and 4 apparatus, the mold comprises the sections 9a and ltla which again define therebetween a mold cavity which has open sides, but in this case said mold sections 9a and Lila are of the same diameter and are spaced axially apart to define therebetween a mold cavity of the desired cross-section size and shape.

In Fig. 3, heating gas is supplied through a pipe 31 for the purpose of heating the crucible throughwhich the mold passes. Numeral 32 denotes a guide roller for guiding the strip 17a as it is withdrawn from the mold cavity.

One of the brackets 23 which rotatably support the respective pairs of

rollers

11 and 12 has a bracket extension 33' which mounts the ends of the rod 21a on which the ball bearings 22 are rotatably mounted, said ball bearings serving to accurately maintain the

mold sections

9a and 10a in predetermined spaced apart relation.

In this case, the crucible 34 has an upward extension 35 through which the mold: passes and said extension is formed with a plurality of openings 36 located below the level of the molten material 4 in said crucible, the molten material flowing through such openings 36 to maintain the mold cavity 1-6a'in. filled-condition as the mold passes downwardly through said crucible and the die 7.

As best shown in Fig. 4, positive driving of one ofthe rollers 11 will effect driving of both of. the

mold sections

9a and 10a, whereas in the Fig. 2 construction the inner mold section 10 will be driven through the casting 17 as it is withdrawn from the mold cavity. Of course, this drive assembly of Fig. 2 could. be rotated from the position shown, omittingthe rod 21- and ballbearings 22 sothat the positively driven roller 11. will frictionally engage both moldsections9 and- 10.

In Figs. 5-8 are cross sections of straight or annular molds which. are suitable for making wires or rods of desired cross section. Said molds comprise-the mold sections 37 and 38 (Figs. 5 and7) andmoldrsections 37a and 38a (Figs. 6 and 8), the inner moldsection. in Figs. 5 and 6 beingv hollow as

indicated'at

39 and 39a respectively. The outer. mold section 37 has a series of openings therearound leading into the mold cavities 4142 so that, as said mold passes downwardly through a crucible, rods or wires 43 will be cast and. solidified therein. The individual cavities may be interconnected by gaps 44 so that all of the castings may be removed as a more or less tubular body, and then the fins in between the rods or wires 43 may be severed. In Fig. 6, the above described components are identified by the

reference numerals

40a, 41a, 42a, 43a, respectively, and in this particular em bodiment, the cavities-are separate and not joined by the gaps 44.

In Fig. 7, the openings for the molten material are indicated by reference numeral-46, and in this instance the inner mold section is of solid cross sectionrather than hollow as indicated by numeral 45.

In Fig. 8, the structure resembles that of Fig. 7 insofar as the solid interior mold section 45a is concerned, but otherwise resembles that of'Fig. 5 in the provision of the gaps 44a between the adjacent'cavities 41a-42a.

The mold sections as used in the present invention may be made of any suitable permanent mold ceramic material or they may be'made from a temporary aggregated destructible investment material such as ceramic plaster, graphite, carbon, or resin investment. Where a destructible investment material is used, it is reconstituted completely or at least it is recoated'prior to each passage thereof'through the pool of molten material.

As .an example of the apparatus and method, the mold sections9 and 10 of Fig. 1 were of approximately 12" diameter driven at a speed of 1 R. P. M.; or, in other words, a lineal speed of the mold cavity 16 of 36 per minutes. The mold cavity 16 was A" x A, the

mold sections

9 and 10 being of graphite and the mold cavity surfaces were coated with a thin layer of graphite coating material 29 as said mold sections passed through the container 28. The molten material in this case was bronze (4% Sn, 4% Pb) heated to a temperature of about 2050 F. and kept at such temperature in the crucible 5 as by means of the heating gas supply pipe 31. The cooling die 7 had an opening therethrough of substantially the same size as the

mold sections

9 and 10 and was cooled for a lengthof about 3" by circulation of water at 70 F. and a pressure of about 70 p. .s. i. In addition, the coolant sprays 26'supplied coolant water at the point where the casting 17 emerges from the. die 7. The casting 17 as thus emerging from the lower end of the cooling die has been solidified to shape-retaining form, but is yet highly heated, for example about 700 F.,

so that the casting 17 can be withdrawn as shown and coiled around the drum 18 without danger of rupture.

Obviously, the mold sections 9 and may be passed through the crucible and die at any speed less than indicated without any change in results except that the casting 17 will emerge at a somewhat lower temperature if the cooling rate is maintained the same as before. Likewise, the

mold sections

9 and 10 may be passed through the crucible and die at a speed considerably greater than that indicated, again without seriously affecting the results except that is conceivable that the speed may be so great that the casting 17 will emerge in molten form unless the cooling rate is substantially increased by circulation of coolant water at a greater pressure and providing a greater number of coolant sprays 26.

It is to be noted that in any case, the casting operation avoids pouring of the molten material into a molding cavity with its disadvantages as aforesaid.

Although in the Figs. 1 and 2 apparatuses, the mold is shown as comprising

separate sections

9 and 10, it is to be understood that in some instances unitary one-piece molds may be employed which are open, for example, on one side only rather than opposite sides as shown in Figs. 1 and 2.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

1. Apparatus for the continuous casting of metal, comprising a mold having an open side which leads to a cavity in said mold, a molten material supply crucible disposed alongside a portion of the open side of said mold for supplying molten material through such open side into such cavity to a level corresponding to that of the material in said crucible, means supporting said mold for continuous movement downwardly with respect to said crucible, cooling means adjacent said crucible and alongside an adjacent portion of said mold arranged to cool the mold and the cast material in the corresponding cavity portion to solidify the material, said cooling means serving to bridge the open side of said mold therealong, and means for continuously withdrawing the cast and solidified material from said mold, said mold comprising spaced apart circular rings defining a cavity therebetween and a peripheral gap constituting the open side of said mold, said rings having portions thereof moved downwardly through said supply crucible and said cooling means.

2. Apparatus for continuous casting of relatively thin strip metal comprising a mold having a relatively narrow open side which corresponds to an edge of the strip metal to be cast and which leads to a strip-shaped cavity in said mold, a molten metal supply crucible, means for maintaining a substantially constant head of molten metal in said crucible, means supporting said mold for continuous movement downwardly through said crucible for flow of molten metal into said mold through the open side of the latter, cooling means downwardly adjacent to said crucible and through which said mold is moved so as to cool the mold and the cast metal in the corresponding cavity portion to solidify the cast metal, said cooling means serving to bridge the open side of said mold therealong, and means for continuously withdrawing the cast and solidified metal from said mold.

3. The method of continuous casting of relatively thin strip metal which comprises continuously moving a mold having opposite narrow open sides corresponding to the edges of the strip to be cast downwardly through a pool of molten metal at a speed such that the molten metal level in the pool and in the mold are approximately the same, and moving the mold downwardly through a chilling zone whereat the narrow open sides of said mold are closed and the metal in the cavity is cooled to shaperetaining form, and thereafter continuously withdrawing the casting from said mold.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

2. APPARATUS FOR CONTINUOUS CASTING OF RELATIVELY THIN STRIP METAL COMPRISING A MOLD HAVING A RELATIVELY NARROW OPEN SIDE WHICH CORRESPONDS TO AN EDGE OF THE STRIP METAL TO BE CAST AND WHICH LEADS TO A STRIP-SHAPED CAVITY IN SAID MOLD, A MOLTEN METAL IN SUPPLY CRUCIBLE, MEANS FOR MAINTAINING A SUBSTANTIALLY CONSTANT HEAD OF MOLTEN METAL IN SAID CRUCIBLE, MEANS SUPPORTING SAID MOLD FOR CONTINUOUS MOVEMENT DOWNWARDLY THROUGH SAID CRUCIBLE FOR FLOW OF MOLTEN METAL INTO SAID MOLD THROUGH THE OPEN SIDE OF THE LATTER, COOLING MEANS DOWNWARDLY ADJACENT TO SAID CRUCIBLE AND THROUGH WHICH SAID MOLD ISMOVED SO AS TO COOL THE MOLD AND THE CST METAL IN THE CORRESPONDINGLY CAVITY PORTION TO SOLIDIFY THE CAST METAL, SAID COOLING MEANS SERVING TO BRIDGE THE OPEN SIDE OF SAID MOLD THEREALONG, AND MEANS FOR CONTINUOUSLY WITHDRAWING THE CAST AND SOLIDIFIED METAL FROM SAID MOLD.