US2878537A - Method and apparatus for casting - Google Patents

Description

March 24, 1959 J, B, BRENNAN 2,878,537

METHOD AND APPARATUS FOR CASTING Filed April 25, 1956 INVENTOR. J05EPH B. BRENNAN ATTORNEYJ.

United States Patent METHOD AND APPARATUS FOR CASTING Io'seph B. Brennan, Cleveland, Ohio; Helen E. Brennan, exectitrix of said Joseph B. Brennan, deceased Application April 23, 1956, Serial No. 579,952

8 Claims. (Cl. 22-57 .2)

v The present invention relates generally as indicated to a method and apparatus for casting, and more particularly to the continuous casting of metallic wires, rods, or the like, the present application being a continuation in part of my copending US. application Serial No. 393,666, filed November 3, 1953, now Pat. No. 2,745,151, granted May 15, 1956.

It is a primary object of this invention to provide a method for continuous casting which involves the steps of downwardly moving a longitudinally grooved mold or core through or against a pool of molten metal, whereby the grooves in the core are continuously filled with molten metal without entailing. the usual pouring operations; and then the core is passed through a cooling zone in the form of a chilling die which bridges the grooves and which cools the metal filling the grooves to shape-retaining form.

The solidified metal thus constitutes a closure for the core, and the portion of the core which is surrounded by the chilling die forms with the latter longitudinally extending cavities of the desired cross-section size and shape of, the wires or rods being cast.

- It is another object of this invention to provide apparatus by which the foregoing method may 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 absence of the pouring operation eliminates oxides in the metal 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 apparatuses and method's.

- Furthermore, the elimination of the pouring of molten metal into a mold cavity permits the molten metal in the supply crucible to become de-gassed, that is, bubbles of gas can be expelled and, therefore, are not trapped in the continuous casting as is the case where molten metal is poured into a mold cavity.

'More specifically, in my method and with my apparatus, the casting operation is achieved by having molten metal in a pool disposed directly against a portion of a longitudinally grooved core, thus requiring neither a close regulation of the downward speed of the core, nor any regulation of the rate of flow of the molten metal.

Stated in another way, the molten metal is not poured into a downwardly moving mold cavity, but, to the contrary, the portion of the cavity which at any instant is within the supply crucible or passing adjacent thereto and in communication with the molten metal therein, is, in effect, a unitary 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 metal remains full up to the level of the molten metal in said pool or crucible". Therefore, no pouring is involved in the casting operation. The primary requirement is that an adequate sup- 2,878,537 Patented Mar. 24,v 1959 ice ply of molten metal be provided in the crucible, preferably in an amount such as to maintain a substantially constant level.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features herein after fully described and particularly pointed out in the claims, the following description and the annexed drawings setting, forth 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: I

Fig. 1 is a fragmentary side elevation view, partly in cross-section, of one form of apparatus for carrying out this invention;

Fig. 2 is a transverse cross-section view, taken substantially along the line 22, Fig. 1;

Fig. 3 is a vertical cross-section view of a modified form of apparatus;

Fig. 4 is a transverse cross-section view, taken substantially along the line 4-4, Fig. 3; and

Fig. 5 is a transverse cross-section view similar to Figs. 2 and 4 except illustrating still another form of apparatus.

Referring now more particularly to the drawings, and first to Figs 1 and 2 thereof, the molten metal 1 which is to be continuously cast in the form of strip, wires, rods, or the like, connected together or not, as desired, is supplied, as needed, into a container 2.

Said container may, if desired, be formed with an overflow notch so as to maintain a predetermined level of the molten metal therein. The container 2 is here shown as being of generally funnel shape and is formed around its lower end with a cooling die 3 which is cored. as shown for circulation of cooling medium, such as cold water, therethrough, the reference numerals 4, 4 denoting the pipes for circulating cooling medium which, as aforesaid, may be cold water.

In the form of the apparatus illustrated in Fig. 1, the mold or core 5 is in the form of an endless ring guided by rollers 6 and 7 and driven by means such as are clearly illustrated and described in my aforesaid copending application. Serial No. 393,666. 7

The core 5 is formed with a series of longitudinally extending grooves 8 which extend endlessly around one side of said core, the grooves 8 as best shown in Fig. 2 herein, being of generally semi-circular cross-section. The core 5 is rotated by the drive means aforesaid in the direction indicated by the arrow so that a portion thereof passes downwardly through the container 2 and through the adjacent cooling die 3. As evident, when said core'5 is passing through the container 2, the grooves 8 are continuously filled with molten metal 1 without entailingv a pouring operation.

In the present case, the cooling die 3 is internally grooved, as at 9, to define with the grooves 8 of core 5 a plurality of circular cross-section die cavities. Inthis case, the cast wires or rods will be connected together by thin webs 10. The cooling die 3 is effective to; cool the metal in the grooves 8 and 9 so that it assumes ashape-retaining form, herein of circular cross-section.

The group of wires or rods interconnected by the webs 10, as continuously formed and while yet in rather highly heated state, is designated by the reference numeral 11, the same being continuously stripped from core 5 by means of a shoe 12, whereupon the casting 11 may passbetween rolls 14, 14 for flattening and for slitting or severing operations to provide separate wires or rods.

In the structure illustrated in Figs. 3 and 4, straight longitudinally grooved cores 20 are successively shoved down through a splined guide 21, through a container 23 for molten metal 1, and through a cooling die 24. In this case, the core 20 and die 24 have complementary grooves 25 and 26 which form hexagonal cross-section wires or rods interconnected by thin webs 27. Such group of wires may readily be removed from core 20 simply. by slitting through one thin web 27 and opening up and flattening the casting and finally slitting or severing at the remaining webs 27.

,While the Figs. 2 and 4 show the cast rods or wires joined together by webs 10 and 27, it is to be understood that, if desired, the rods or wires may be cast separate simply by having the core a close fit in the cooling die. In Fig. 5 is shown a cross-section view like Fig. 2 or Fig. 4 of apparatus for casting metal strip into the open side of a two-part core 303 1, the molten metal flowing into the open side of the groove defined by said core parts 30 and 31, and being solidified by movement of the core downwardly through the cooling die 32. For casting strip metal, the core parts 30 and 31 may be circular as is the core 5.

However, for casting, for instance, copper against steel strip, it is preferred to employ straight core parts 30 and 31 as is the core 20 whereby steel strip 34 may be positioned in the groove leaving a space for flow of copper 35 thereagainst.

The cores 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 as taught in my pending application aforesaid. prior toeach passage thereof through the pool ofmolten metal. As an example of the apparatus and method, the core 5 was of approximately 12" diameter driven at a speed of 1 r.p.m. or, in other words, a lineal speed of about 36" per minute. The grooves 8 and 9 of A" diameter with gaps 10 of .010" thickness and A width. Said core 5 was of graphite and the molten metal in this case was bronze (4% Sn, 4% Pb) heated and maintained in the container 2 at a temperature of about 2350 F., the container 2 heated by induction heating coil 36 (10,000 cycles, 30 kva.). The cooling die 3 was cooled for a lengthof about 3" by circulation of cold water therethrough, the cast metal being at a temperature of about 700 F. at the exit end of said die 3.

Said casting, as it emerges from the die and as aforesaid, is at a temperature of approximately 700 F. so that it may be easily stripped from core 5 by shoe 12 and flattened between rolls 14, 14.

Obviously, the core 5 may be passed through the crucible 2 and die 3 at any speed less than indicated without any change in the results except that the casting 11 will emerge at a somewhat lower temperature if the cooling rate is maintained the same as before. Likewise, the core 5 may be passed through the crucible 2 and die 3 at a speed considerably greater than that indicated, again without seriously affecting the results except that it is conceivable that the casting 11 will emerge in molten condition unless the cooling rate is substantially increased.

Although the longitudinally grooved cores herein are preferably in the form of continuous rings, it is contemplated to employ straight core sections which are successively shoved down through the container 23 and the straight die 24, and upon removal of the casting from the core 20 or 30, 31 which emerges from the bottom of die 24, said core may be re-used by again shoving it down against a successive core.

In this way, the casting operation may continue indefinitely so long as the cores 20 or 30, 31 are shoved down one after the other. As in the case of the ring.

cores, the rods or wires which are cast may be connected together or not, as desired, and if connected together the tubular casting may be slit longitudinally and removed by flattening. Otherwise, if the wires or rods are cast in separated condition, it is then a simple matter to continuously strip the individual wires from the core as the core moves down below the lower end of the chilling die 24.

It is also contemplated by this invention to employ cores 5, 20, or 30-31, which are wholly or partly made up of ceramic fibers as of, for example, mixture of aluminum oxide and silicon dioxide or nitrided silicon carbide. Where the core only partly comprises said ceramic fibers, they would be located to constitute the die surfaces against which the metal is cast. Such ceramic, fibrous material may be continuously accreted and wet as with sodium silicate and hardened with carbon dioxide. A core thus made up wholly or partly of such ceramic fibers has very smooth surfaces which produce smoother castings than can be produced with other known cores.

The cores 5, 20, or 3031 may also be sand cores bonded with a binder such as phenol formaldehyde resin and continuously cured with heat, for instance, by high frequency currents at 400,000 c.p.s. Faster curing with lower frequency may be effected by mixing iron powder, or pulverized iron ore, with the sand.

With reference to the ceramic fiber cores, the fused ceramic may be made into fibers which are aggregated or felted on a screen continuously to half the desired shape and these shapes then mated continuously and metal poured therein continuously. This applies particularly to apparatus using a core 3031 as illustrated in Fig. 5. I

Instead of removing the casting 11 as in Fig. 1, it has been found advantageous to continuously shave the cast;

ing to produce fibers or foil which are useful in metal paper making, in the weaving of metal mats, etc. .Because these fibers or the foil is shaved off continuously, there is no problem of waste as is now encountered in the shaving of metal rods.

As evident, when shaving metal rods, there is always left a wasted core. In the present case, the shaved casting on core 5 passes through the container 2 and die 3 to build up a new layer of metal which then is shaved continuously. The shaving tools, which for example may take the form of the chisel shaped shoe, may be circumferentially spaced around the core 5 and the shavings may be continuously wound on spools or may be collected in a barrel or pile depending on the use to which said shavings are put. The shavings need not be continuous but can be separate small pieces of metal formed as by alternately shifting the tools into and out of contact with the casting. The metal removing tools likewise may be grinding wheels or the like to form metal dust or powder instead of metal chunks, fibers, or foil.

The high frequency coil 36, for example, may be made of silica or other dielectric ceramic material through The enters the grooves of the core from beneath the surface of the molten metal to prevent oxides which are ordi-' narily on the surface from getting in and contaminating the casting.

With reference to Fig. 5 showing the laminated metal 34 and 35, the base strip will preferably be held by splines against buckling when subjected to heat, such splines extending down short of the zone where solidification occurs.

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 3 the following claims, or the equivalent of such, be emplayed.

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

1. The method of continuously forming metal pieces, filaments, foil, and the like which comprises continuously moving a core downwardly through a pool of molten metal and through an adjoining open-ended chilling die which is efiective progressively to solidify suflicient metal in a smooth continuous layer about the core to provide a layer having a cross-sectional shape conforming to the shape of the space between the die and the core, removing only a portion from the outer smooth surface of said layer without reaching the core to form said pieces and the like remote from the core, and moving the core and remaining solidified metal thereon through said pool and die to replenish the removed portion.

2. Apparatus for continuously casting smooth and fine metal pieces comprising an open-ended downwardly extending chilling die, a downwardly extending core disposed within said die and defining therewith a cavity of desired cross-sectional size and shape, a container for molten metal for supplying said metal into the upper end of said cavity, means for moving the core downwardly through said die to deposit about said core a smooth progressively solidified layer of the metal, and means to remove only an outer portion of said layer remote from the core and without reaching said core to provide a fine and smooth piece of said metal.

3. Apparatus as claimed in claim 2 wherein said core is composed of sand bonded into an integral form.

4. Apparatus as claimed in claim 2 wherein said core is composed of ceramic filters at least along the cavitydefining surfaces.

5. Apparatus for casting a relatively flat metal strip without moving the same through an arcuate path comprising an open-ended downwardly extending chilling die, a downwardly extending linear core disposed within said die and having a groove defining a strip form which extends inwardly from the periphery of said core, a container for molten metal communicating with said die and said slot, and means for moving the linear core in the direction of its length through said die progressively to solidify the molten metal in said slot.

6. Apparatus as claimed in claim 5 further including a plurality of said linear cores for successive and endabutting movement through the chilling die to produce the metal strip continuously.

7. Apparatus for producing a relatively flat bi-metallic strip without bending the same comprising an openended downwardly extending chilling die, a downwardly extending straight core disposed within said die and having a groove defining a bi-metallic strip form which extends inwardly from the periphery of said core, a metal strip defining one of the metals of said bi-metallic strip disposed within and partially occupying said slot, a container for molten metal communicating with said die and said slot, means for moving the linear core in the direction of its length through said die progressively to solidify the molten metal in said slot and in union with said metal strip defining one of the metals of said bimetallic strip, and removing said metallic strip and solidified metal from said straight core slot.

8. The method of continuously forming metal pieces, filaments, foil, and the like which comprises continuously moving a core having a first metal layer thereon downwardly through a pool of molten metal and through an adjoining open-ended chilling die which is effective progressively to solidify metal from such pool about such first layer on the core and provide a smooth continuous deposit comprising such first metal layer and such solidified layer and having a cross-sectional shape conforming to the shape of the space between the die and the core, removing only a portion from the outer smooth surface of such deposit without reaching the core to form said pieces and the like remote from the core, and moving the core and remaining solidified metal thereon through said pool and die to replenish the removed portion.

References Cited in the file of this patent UNITED STATES PATENTS 326,147 Pielsticker et al Sept. 15, 1885 441,643 Close Dec. 2, 1890 443,536 Norman Dec. 30, 1890 910,674 Hancock Jan. 26, 1909 1,249,101 Jacobs Dec. 4, 1917 1,342,127 Mellen June 1, 1920 1,612,737 Lane Dec. 28, 1926 1,651,678 Davis Dec. 6, 1927 2,362,875 Zahn Nov. 14, 1944 2,393,213 Willard Jan. 15, 1946 2,664,605 Beste Jan. 5, 1954 2,714,235 Brennan Aug. 2, 1955 FOREIGN PATENTS 383,313 Italy Oct. 2, 1940

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