AN IMPROVED METHOD OF FINISHING METAL CASTINGS
Year: 1884

page_text: COMPLETE SPECIFICATION.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake & Co, Patent Agents,
Southampton Buildings in the County of Middlesex do hereby déclare the nature
of my invention for "AN IMPROVED METHOD OF FINISHING METAL CASTINGS
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
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My invention relates to a process of manufacturing finished articles from hard
metal like steel or steely iron, whereby the qualities and skin due to casting, are
obtained and preserved; that is to say, my invention relates to a process or method
of manufacturing articles of cast steel or steely iron having a smooth or finished
surface, wherein these metals are compressed, and the surfaces are rendered smooth
and the articles are brought to the desired finished condition without abrading or
destroying the cast skin.
To this end the said invention consists in the process or method of working
metals of the character referred to, by casting the same into shapes approximating
those desired, but having slight irregularities or variations therefrom at the surface,
and then compressing the blanks so obtained between dies.
In the production of cast articles of the character of metals referred to, where it
is necessary to have a smooth or finished surface, as heretofore practiced; the
casting has been completed or finished by chipping, turning, milling, planing or
grinding the exterior surface, and by boring or drilling the interior surface. In
short, the skin or toughest part of the metal has been abraded or cut away to
produce the desired exactness of size and form and finish of surface.
.
In the production of drop forgings wrought iron or steel blocks are first wrought
to approximate form by roughing dies and breaking-down dies, and the surplus
metal is thrown off in the form of fins which must be cut away by trimming dies,
thus making a large per centage of scrap. When holes are required the forging
plugs or mandrills are placed in the dies opposite each other but they cannot come
together. They force the metal outward and leave between them a web to be
afterwards punched out as scrap. In these cases the article must be finished either
by cutting or abrading as with the cast blank, or must be transferred to other
finishing dies to impart the desired finished shape and surface.
Moreover, chambered articles cannot, be produced, by the ordinary processes of
drop forging, but by my process the casting may be cored in well known ways,

page_text: and a blank obtained with any desired form or size of cavity or chamber, and the
exterior surface may be condensed and smoothed in the same manner as a solid
blank. The surface of the edges or openings to the cavities or chambers may also
be compressed to smoothness by my process.
This chambering and coring process also serves another useful office, to wit In
case of imperfections in the moulding, so that surplus stock is attached to any part
of the cast blank, when subjected to the action of the dies, this surplus stock flows
into the chambered part and thus lessens the tendency to throw out a fin, and
allows the dies to come together.
It is found that the surface of cast steel or steely iron will flow, or may be upset,
to a limited extent, and that slight inequalities or projections may be made to flow
inward and fill up corresponding notches or cavities, and thus articles may be
produced from castings having the finished form and surface desired, without
abrading or cutting away the skin, and without crushing or upsetting the entire
body of the metal as in coinage and ordinary drop-forging.
In carrying out my process I cast the metal into a shape approximating in
general contour to that which it is to have when completed, but varying at the
surface somewhat, so as to allow the surface metal to flow under the action of
the compressing dies to such limited extent as to fill up the dies and fill up the
slight depressions in the surface. It should be observed that a practically good
article may be obtained when the surface has been compressed and the sharp
irregularities condensed and forced into the adjacent spaces, notwithstanding said
spaces may not be entirely filled.
A very little experience and practice, however, will enable the casting to be
adapted relatively to the compressing dies so that the desired result may be
. obtained.
By properly proportioning the blank or approximating casting and the com-
pressing dies, the desired surface may be imparted without producing any
perceptible fin on the finished article.
After the blank is cast to approximate shape and size, the same is subjected to
pressure between dies slightly smaller than the extreme projections from the general
contour in a drop power or hydraulic, press. Obviously, cast iron blanks may be
decarbonized by well known processes to convert them into steel or steely iron
and then finished by compression as above described. The cast blank may be
reheated to any desired extent before being subjected to pressure in the finishing
dies.
:
It will be seen that the hard skin of the casting is not ground or cut away by
my process, and while the surface is not brightly polished, it is quite as smooth,
has a harder and better wearing surface, and will resist corrosive action better.
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
The method, substantially as described; of giving to rough castings of hard metal,
such as articles of steel, or steely iron, a smooth or finished surface, which method
consists in taking a casting approximating to the desired dimensions, and subjecting
the same to the action of compressing dies, corresponding in shape and size with
the desired finished article.