An Improved Process of Casting for Reducing the Density of Cast Articles.
Year: 1896

page_text: Date of Application, 31st Dec.. 1996-Accepted, 27th Mar.; 1897
An Improved Process of Casting for Reducing the Density of
Cast Articles.
1, ALPHA FRANCIS COTHIAS of 9, Rae Victor-Hugo Ivry (Seine) in the Republic
of France, Manufacturer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
When any article is cast by the existing processes, either by running the molten
metal or alloy, into moulds of sand or the like by simple ingates or by sending a jet
of inetal under pressure into a metallic mould, the, greatest care is always taken to
avoid mixing any gas, liquid or vapour. with the metal. The escape of air is provided
for 'and this very rational precaution has for its object to avoid the formation of
bubbles, which in the cast article are betrayed by cavities, blow-holes, cracks.or
fissures, rendering the object brittle and absolutely destroying the homogeneous mass
of its constitution..
In some cases it may be requisite to make articles of homogeneous constitution
having given dimensions of a given metal, the said metal being mercly chosen or
preferred for its chemical nature, and not for the greater or lesser cohesion of its
inolecules. This great cohesion may even in certain cases' form a drawback. If
therefore the cohesion of the molecules is great, or in other words if the specific
gravity of the metal in fusion be high, it may be advisable to change uniformly this
cohesion, to diminish it, in order to reduce the density of the cast article, either with
the object of obtaining with the same substance a lighter and consequently cheaper
casting, all things being equal otherwise; or with the object of giving to the cast
article a uniform porosity capable in certain special applications of offering great
advantages. This is the case, more particularly, in making lead seals, which are of
regulation dimensions, and the weight of which is a drawback. It is the same with
the plates of accumulators, which with a given thickness must have given surface, of
which, in a word, the volume is the sole important characteristic, and of which the
considerable weight is rather a drawback, whilst for the anodes of electro-plating.
in which a large surface for attack is alone of importance, the cohesion of the
metallic molecules are on the contrary a drawback; and so forth.
The present invention relates to a process of casting in metal whereby the density
of the moulded article is diminished, which has, among other advantages, that of
reducing the weight of the article and diminishing its cost.
In order to obtain this double result, I inject into the molten metallic mass during
the casting some drops of a suitable liquid (animal, vegetable, or mineral oil, or the
like), which by its evaporation and its fusion in the molten mass imparts a uniform
porosity to the cast article, without changing the chemical composition of the
metal, and which changes uniformly the texture of the metal. The result of this
is to diminish the density of the moulded article, which, nevertheless, preserves a
homogeneous constitution."
As, an example, I will now describe the manufacture by my improved process of
sealing leads, called "Custom's seals" and more specifically designated under the
name of leads for sealing. One of these sealing leads is shown in section in Figure 1
of the accompanying drawings, and in plan view in Figure 2, whilst Figures 3, 4, 5
and 6, show a suitable apparatus for carrying out the process.

page_text: The lead melted in a crucible is delivered by means of a pump by an ingate J into
a suitable mould M (Figures 3, 4, 5 and 6). B is a core penetrating into the mould
at the precise moment when the jet of molten metal enters it, and serving to form the
recess or hollow of the seal P. 1 impregnate the core B with a layer of animal,
vegetablo, or mineral oil, which it receives on its passage into the mould. The liquid
is contained in a reservoir R, whence it flows drop by drop..and penetrates into the
mould by holes t in the cover plate p. The evaporation of the liquid with which the
core is impregnated is produced instantaneously and at the precise moment when
the sealing lead is formed. I thus obtain a sealing lead of homogeneous constitution,
of light uniform porosity, the weight of which is considerably less than that of ordinary
lead seals of the same dimensions.
The process of introducing liquid or gas into substances in fusion, and also
the nature of the liquid, gas or vapour may vary according to requirements or the
result to be obtained.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The improved process of casting hereinbefore described, in which by the
introduction of some drops of a suitable liquid on the arrival of a jet of gas or vapour
into the molten material at the moment of casting, the cohesion of the molecules of
metal is changed, and a uniform porosity communicated to the substances having
for result to diminish the density of the cast article whilst preserving its homogeneous
constitution.
2. The application of the hereinbefore described process of casting, more
particularly to the manufacture of sealing leads, plates of accumulators and anodes of
metal plating apparatuses, substantially as described:
Dated this 30th day of December 1806
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.