IMPROVEMENTS IN MOLDS FOR CASTINGS
Year: 1884

page_text: I ROBERT WASHINGTON TRAYLOR of Richmond in the County of Henrico and
State of Virginia, one of the United States of America, Gentleman, do hereby
declare the nature of my Invention for "IMPROVEMENTS IN MOLDS FOR CASTINGS"
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
This Invention relates to molds for castings, and has for its object the construc-
tion of a mold of such nature that it will not require to be renewed or remade
cach time a casting is made, and will at the same time produce castings free from
grit and sand and in a neater and smoother condition; thereby effecting a saving
of time, and labor, and the wear of tools now required for finishing.
My Invention consists of a mold, the whole, or a part of whose matrix cavity or
molding surface is composed of mica.
To a full understanding of my Invention, reference should be had to the
accompanying Drawings, wherein I have illustrated, in Fig. 1, the two halves
of my improved mold in perspective, the mold being shown as opened to expose
the molding surface, and in Figure 2, a vertical section of an ingot mold.
Corresponding parts are designated by the same reference letters.
The letter A, refers to a casing or frame of any suitable size or form. This
frame may be the ordinary well known molders flask, or it may be specially
constructed as to form, dimensions and strength.
The frame or frames A, may be filled with sheets or pieces of mica B, compressed
face to face against each other, and preferably placed upright on their edges and at
right angles to the sides of the frames.
The sheets of mica B, should be so tightly compressed as to prevent molten
metal from running between the sheets, and to permit of its body of the mica to
be cut or dressed to the desired configuration to form the matrix cavity, or molding
surface.
Under suitable compression the exposed edges of the sheets or pieces of mica
are capable of receiving a polish that results in rendering the surface of the metal
cast in such a mold so smooth as to require no dressing to prepare it for use, and
at the same time the gases arising from the metal while in a molten state readily
escape through the interstices between the sheets.
LD 431

page_text: A cavity C, of suitable form is cut into the body of the mica in one or both of
the halves of the flask and the edges of the sheets around the cavity are cut or
trimmed down flush with the edges of the flasks or frames to cause the two masses
of mica to make a close joint.
In making castings requiring a matrix cavity in each of the halves of the mold,
I form a half gate hole at the top of each frame or flask, and form a groove c,
extending from the matrix cavities C, to the gate hole to permit of the flowing of
metal into the matrix cavity. But in casting metal ornaments, having a plain
surface upon one side, I contemplate using a half mold of mica to form the exposed
face of the ornament and a half mold of sand or other material for the plane
surface of such ornament. In this instance the gate hole could be formed in the
sand half of the mold.
I wish it understood that I do not confine myself to forming the matrix cavity
after the mica has been compressed in the frames, for when the shape of the castings
desired is not much varied in its lines, angles and curves, the sheets or pieces of
mica may be cut into the needed shapes before they are so compressed.
Nor do I confine myself to pieces or sheets of mica placed at right angles to the
sides of the frame, for they may be arranged parallel with said sides, or as shown
in the Drawing, some of the sheets may be arranged parallel with the sides of the
frame, and others parallel with the ends thereof, or they may be arranged diagonally
with respect to said sides and ends.
Nor do I confine myself to the exact form of mold illustrated in the accompanying
Drawings, as the advantage derived from forming the whole or a part of the
molding surface of mica is specially applicable to ingot molds, and I regard such
molds so constructed as within the scope of my Invention.
I have illustrated in Fig. 1, of the Drawings, a mold shaped to cast the shell of
a globe valve, the mold being made in two halves each having a suitably shaped
cavity; but it is obvious that in some instances one half of the mold will be
required to be made with a cavity and the other half with a projection, as in
casting a concave-convex body.
Although I have throughout this Specification referred to the molds as being
formed of sheets or pieces of mica compressed to form a solid body, it is apparent
that a solid block of mica may be used instead.
I am aware that it has heretofor been proposed to line a mold with macaceous
rock, but this I do not claim.
It will be seen that by my Invention I provide a mold that is, so far as the
operation of casting is concerned, practically indestructible, and that the mold
may be used repeatedly without any renewal or reworking of the surface which
gives configuration to the casting.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is
1. A mold for casting metals, having the whole or part of its matrix cavity or
molding surface composed of mica, substantially as described.
2. A mold for casting metals having its matrix cavity or molding surface
composed, wholly or in part, of compressed sheets or pieces of mica, substantially
as specified.