US1805650A - Process of protecting sand molds and cores - Google Patents

Description

Patented May 19, 1931,

UNITED STATES rArENr orrlca EUG-ENE A, IBALSLEY, Q1 WHEELING, WES'IVVIRGINIA, LUOIEN I. YEOMANS, OI

CHICAGO, IILINOIS, ASSIGNOBS 'I'O'LUQIEN I. YEDHLNS, INC, 01' CHICAGO, ILLINOIS, 1

a conronarron or more P3001388 OF PROTECTING QMIOLDS Io Drawing. 7

' In the preparation ofsand molds in which molten metal is to be poured,- it iscustomary to reinforce fragile sections in some instances and to protect corners, small bosses, thin ribs and other projecting surfaces where the wash of the metal is liable to break off or cut away a portion of the moldsurface, by using ordinary nails of various sizes which are inserted in the sand body by the molder. in such a 10 manner that the nail heads are flush with the mold. surface and constitute a part thereof.

On certain classes of work the expense involved in thus protecting the mold from wash is an item of consequence, and it is not uncommon for foundries making irregular sections of large steel castings to use as many as twenty pounds of nails, per ton output of the entire foundry, thereby adding a cost of a dollar a ton to the average cost of castings.

This is not the only expense, or even the prln cipal expense item occasioned by their use. The proper placing of the nails requires care and skill and involves a considerable labor cost. The expense of shaking out molds after casting is increased, particularly in the case Application jfled July 5,

of steel castings as the nail heads are melted p by the molten metal and welded to the casting. -The labor entailed in chipping off the nails and cleaning the casting is a further item of expense. I

We have discovered that thesurfaoes of v asandmold'maybestructurall strengthened and protected againstwash o molten metal j by. upon such surfaces a thin layer 0 metals .'.for this purpose,- buthave found aluminum well adapted to the requirements, and

prefer to use metals which have. ama'rked affinity for oxygen or which upon melting tend 4o to .-remove rather than increase the gaseous 'contentof the metalsfrom which the. casting is tobemade'. To-.-apply such-a coating we prefer' to the welllmown Schoopfsp'ray .When -'sprayed :uponlthem'old, the mtlaii 451jmetal penetrates intothe among I I H h I I S p v molten'metal. We may use a variety of;

1929. Serial ll'o. 878,280.

the grains of sand and roduces a protective coating which adheres rmly tothe mold.

Cores, forming part of a mold, may be treated in this way to expedite cleaning processes after the casting is poured, and struc- P tural strength and surface protection against washing may be secured upon dry or green has been left in the casting because of the difliculty' of removing it.

We do not coat the entire surface of the mold or core, but only those surfaces -(and particularly fragile projecting portions) which require reinforcement against the wash of the metal. It would be impracticable and even dangerous to coat the entire surface, as the heat of the metal causes vaporization of volatile substances in the mold or core, as, for example, the binder compounds emblo wprocess the vapors ployed in core making. "If'the entire surface.

damage the 'casting'by the formation of.

escape from the uncoated surfaces of the mold i or core.

The method herein disclosed of protectin sand molds from'wa'sh is cheaper than that o I pause of nails, reduces the cost of cleaning the castings, and in some results. in a smoother product. A

- This application is a continuation in gut of our application Serial No. 275,956, ed *Ma 'maaa ,We. claim as ourinlviention: Theprocess'of structurally strengthening inserting nails in the molds, obviates the ex- 5 the fra 'le projections and the surfaces adjacent t ereto of a sand mold or core to protect such projections from wash which c0n-- sists in spraying with molten metal such projections and adjacent surfaces, the remaining surface area being not coated with metal in order to permit escape of vapors from such uncoated surfaces.

In testimony whereof we have hereunto aflixed our signatures.

EUGENE A. BALSLEY. LUCIEN I. YEOMANS.