US2314839A

US2314839A - Casting metal

Info

Publication number: US2314839A
Application number: US394068A
Authority: US
Inventors: Donald J Campbell
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-05-19
Filing date: 1941-05-19
Publication date: 1943-03-23
Anticipated expiration: 1960-03-23

Description

March 23, 1943. D. J. CAMPBELL CASTING METAL 4 Sheets-Sheet 1 Do /a aal lbul Filed May 19, 1941 lnn cntor Y /hmtulf. Dakz dttorncg March 23, 1943.

D. J. CAMPBELL CASTING METAL Filed May 19. I l-941 4 Shee ts-Sheet 2 Dona lC myfib -l/ 3|wentor (Ittqrneg March 23, 1943- D. .L CAMPBELL CASTING METAL 4 sheat s-Sheet s Filed May 19, 1941 Inventor dttorncgl March 23, 1943- o. J. CAMPBELL CASTING METAL 4 Sheets-Sheet 4 Filed May 19, 1941 3 nnentor DO /a lea 11,111

" M Dd/aa (Ittorneg UNITED STATES PATENT OFFICE i v CASTING METAL Donald J. Campbell, Spring Lake, Mich. Application May 19, 1941, Serial No. 394,068 3 Claims. (Cl. 22-200) My present invention relates to improvements in casting metal, and particularly to the method and apparatus employed in practicing'improved I attain these named objects. and such other objects as appear from a perusal of the following description, by the apparatus disclosed in the several views of the accompanying drawings, in which- Figure 1 is a diagrammatic view of portions of the apparatus employed in practicing my present method of casting metal.

Figure 2 is a top plan view ofthe mold employed in my present method.

Figure 3 is a cross-sectional view of the mold employed and taken on a plane extending downward from line 1-1, of Figure 2, and looking in the direction the arrows crossing the line indicate.

Figure 4 is a transverse sectional view of the said mold taken on line II II, of Figure 3, and looking in the direction the arrows thereon indicate.

Figure 5 is a transverse sectional view of the said mold taken on line V--V, of Figure 3, and looking in the direction the arrows thereon indicate.

Figure. 6 is a transverse sectional view of the said mold taken on line X-X, of Figure 3, and looking in the direction the arrows thereon indicate; and,

Figure 7 is a longitudinal part sectional view of a gun projectile as would be cast by my present method hereinafter described andby the use of the apparatus illustrated in the accompanying drawings,inwhich Similar numerals refer to similar parts or portions throughout the several thereto.

Numeral l refers to the intermediate, or cheek portion of a mold formed within the foundry flask views, and referring portion 5 of the mold is surrounded by flask 10K and has at its axial center, pour sprue hole ll with flaring portion i2 at its top and thereabove,

. pour basin I3 with skim gate l4 therein, and in its lower face, runner gates l5 extending from the i the mold portions I and 6. The draft pipe 8 2, and having mold cavities 3 of such form as would be adapted for casting therein, large caliber gun projectiles, such as shown in Figure '7 of the accompanying drawings; The said cavities 3 are partly closed 'at their top: by core like slabs I having v tt nding therethrough, and into the cope portion 5" of the mold, feeder cavitiesi and from the top thereof extended cavities 1 open to the interior of draft pipe 8 through holes 9. The cope which is surrounded at the sand of the cope portion of'the mold has communication with the cavities I through holes 9 and extends through the side of the flask lo and exterior of the mold where it is detachably connected with hose 2| and thereby to the air pump 22 driven by motor 23 of any suitable design. At the lower extremity of the mold portion I is core like slab 24 surrounding the lower end of the mold'cavities' 3'and portion' 25 of the extended portion of the sprue hole 26. The said core like slab, has encircling the lower ends of the mold cavities 3, runner passages 21 from which extends moldfeeder passages 28 to the portion 25 of the sprue hole 26. Below the core like slab 24 is a-second core lik slab 29 having annular runner passages 30 with radial gates 2| extending therefrom inward and upward to the mold cavities 3. The said core like slab.

'29 has at its central axis, basin :2 and directly below the mold cavities 3, holes through which extends hollowiperforated core arbor 34 having longitudinal neck 34' and built thereon, first, a

rope like fibrous material on which is built the core 35 of suitable granular material, the said cores each have neck portions 36 whereby is formed the hole in the apex of each projectile.

The said core arbors each have a co'nicalfportion 31 socketed intoconical holes 38 of the hollow bottom plate 39 of the mold arbor with their longitudinal holes 40 open to the cavity 4| having a hole 42 closed by plate, which hole is provided for cleaning the interior of the bottom plate which has extending from the cavity 4i thereof, pipe 44" connected in like manner to a similar air pump to the pump 22 shown in Figure-1 91 the drawings.

In practicing my method of casting metal, which in the instant case is the casting,of.large caliber gun projectiles; having provided the apparatus including a mold substantially as described with the air pumps connected to the mold as shown; I start the said air. pumps as by starting the motors having shaft connection therewith by the usual switch that closes an electric-circuit, and in starting the air pumps gas is drawn forations and longitudmalhole 31' or the aroor,

and by the plnnp connected'to the draft pipe 8, drawgas directly from the molten metal through the holes 9 and I at the top at each of the feeder cavities at.the.top of the mold; and by drawing the gas from the cores, I. permit the molten metal to lay up againstthe cores without causing gas pockets or blows, and in drawing gas directly from the molten metal, which is steel in projectiles, all voids within the metal are eliminated and the steel of uniform structure free from dirt,

slag.

While the pumps drawing the gas from the core and metal, are referred to as air pumps, it

' is to be understood such pumps are classed as air pumps which are equally useful for pumping gas as well as air. In the usual method of casting metal, particularly steel, greatloss of good castings are caused I by reason of the gas formed in the metal by melting forming gas cavities or pockets in the casting and in the core formingthe mold cavities also causing gas cavities and blow holes or depressions in the castings.

In castings, the molten metal which in casting projectiles such as shown, is steel, is poured from a foundry ladle into the pour basin [3 from where it flows downward through the skim gate ll into the flaring portion of the sprue hole II and downward through the sprue hole to the basin 32 and radially outward to through passages 28 to the annular ring passage 21 from where it flows feeder cavities to remain in a fluid state after the lowerportion of the molten metal in the mold cavities has solidified and thus: providing molten metal to feed from the feeder c'avities to the mold cavities to compensate for shrinkage of the castings in the mold cavities. It should be understood that. the sprue hole II is less in cross-sectional area than the sprue hole 26 and that the enlarged portion extending through the core like slab 4 is still larger, thereby preventing molten metal entering the top of the mold cavities until the molten metal rises to above the said core like slab.

vThesprue hole by which the molten metal is conducted to the runner gates at the lower portion of the mold, consists of the outwardly flaring funnel like portion that receives the molten metal from the skim gate II, a restricted portion l l of less cross-sectional area than'the skim gate, and therefore less capacity, an enlarged pass portion between the restricted portion II and an elongated portion 26 having a greater cross-sectionaliarea than the said restricted portion H but less than the said enlarged pass portion and the combined area of the runner gates extending to the mold cavities at their lower ends and therefore the small ends of the mold cavities where gun projectiles are being cast. The molten metal delivered to the mold cavities through the runner gates at the lower end of the moldcavities,

therein and in doing so, cools and therefore 5111111 llLlbLl 1b rcauuus but: .ucuvy put uuu ul. ulcprojectile, which because of its greater mass than the side walls of the projectile, remain in a molten state and feeds molten metal to the side wall portions during their period of solidification and shrinkage, and the heavy portion remaining fluid after the said side walls have solidified, draws molten metal from the feeder cavities 6 until the metal in the heavy portion of the projectiles has solidified.

In conducting casting by my method and having provided the mold substantially as described, and the molten metal which in casting projectiles consists of steel; I start the air pump, connected to the pipe 8 having connection with the mold cavities in the cope portion of the mold, the hollow supporting plate at the bottom of the mold, or both, and thereby cause a partial vacuum within the mold cavities, and pour the flows through the sprue and gate passages to v the mold cavities, helped by the partial vacuum within the said mold cavities and by the partial vacuum draws from' the metal gases formed therein and such as are formed in the cores therefrom and therefore produces metal castings free from gas cavities or pockets and internal defects.

Having described my method of casting metal and the apparatus whereby I practice said method; I claim:

1. In casting metal, the method consisting of applying suction simultaneously to a ,core within a mold cavity and a feeder cavity of a mold having a plurality of mold cavities therein, a runner sprue for flowing molten metal to the mold cavities and having a plurality of portions of different cross-sectional areas comprising a choke portion an enlarged portion below the said choke portion and a third portion having a greater cross-sectional area than the choke portion and extending below the said mold cavities with a plurality of runner gates extending to the lower end of said mold cavities and runner gates extending from the said enlarged portion to the upper portion of said mold cavities while the metal in the mold is in a molten state, causing a partial vacuum within the said mold cavities by applying suction to the mold cavities at their top and to the cores in the mold cavities through the core arbors simultaneously.-

2. In casting metal, the method consisting in providing a moldhaving a casting cavity with a feeder cavity above the casting cavity and a hollow core supported in the casting cavity and drawing gas from the top of the feeder cavity while drawing gas from the casting cavity downward through the core substantially as described.

3. In casting metal, the method consisting in providing a mold having a casting cavity with a feeder cavity above the casting cavity and a core .having a hollow core arbor extending upwardly within the mold cavity with a core built onto and around the core arbor, drawing air from-the casting cavity, depositing molten metal in the said casting cavity and against the said core, drawing air and gas from the casting cavity upwardly through the feeder cavity and drawing gas from the said core downward through the core arbor substantially as described.

DONALD J. CAMPBELL.