IMPROVEMENTS IN THE PRODUCTION OF DENSE STEEL CASTINGS, AND IN APPARATUS CONNECTED THEREWITH
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Carl Maria Pielsticker at the Office
of the Commissioners of Patents on the 14th October 1882.
CARL MARIA PIELSTICKER, of N° 5, Sydney Terrace, Kilburn, London, in the
County of Middlesex, " IMPROVEMENTS IN THE PRODUCTION OF DENSE STEEL
CASTINGS, AND IN APPARATUS CONNECTED THEREWITH
"
My invention relates to improvements in the production of dense Steel Castings ;
whereby Cast steel may be used where Forgings of Steel or of Iron, or Cast Iron
have hitherto been used, on account of the difficulty existing in making Steel
Castings free from blow holes or air bubbles, each one of which presents so many
points of weakness in such Castings.
My invention relates also to improved apparatus used for this purpose.
ע
In carrying out my invention I propose to use a Vessel, preferably of cylindrical
form, of sufficient capacity to hold the entire or part of the contents of a " Bessemer
Converter, and the diameter of which propose to make say from one third to one
half that of its height. This vessel may be made of firebrick or of any suitable
refractory material capable of withstanding the elevated temperature of molten
steel, and is to be placed convenient to the Converter, so that the latter may be
emptied directly into the said vessel, or it may be filled by means of a casting
ladle
The vessel may be heated from the outside by being built into a furnace, or by
means of a forced Gas Blast, which latter may be temporarily introduced at the tap
hole near to its bottom, as will be mentioned hereafter.
Inside of the vessel all around its circumference and say about three quarters of
its height I form a projection upon which rests an interchangeable bottom, fitting
closely to the sides of the vessel, which bottom I also propose to make of a highly
refractory material, say of two or more inches in thickness and furnished with
numerous perforations, say of one sixteenth to one eighth of an inch in diameter and
slightly wider at the top than at the bottom.
A second or several similar such perforated bottoms may be placed in a similar
manner underneath the first bottom, having a space of one or more inches between
each of them, but in such a manner that the perforations of the different bottoms
do not form one continuous line.

page_text: Immediately underneath the lowest bottom is placed a vent hole, which may be
closed with a loosely fitting plug of a refractory material, acting as a valve, capable
of opening towards the outside, and permitting the escape of Gases from the inside
of the vessel, while preventing the entrance of atmospheric air.
At the side of the vessel immediately above its actual or permanent bottom, is
placed a tap hole, which may serve for the admission of a forced Gas Blast at the
beginning of an operation and for the outlet of melted steel at the finish of an
operation.
I propose to conduct my operations as follows:-
The temperature of the entire vessel is first of all brought to near that of melted
steel. The tap hole at the bottom of the vessel is then securely closed. The melted
steel is poured in at the top of the vessel and runs down in numerous thin streams
through the perforations of the first bottom.
On its arrival at the second and subsequent perforated bottoms, if any, it changes
the surfaces of these numerous thin streams of the melted Steel, thus presenting
Lew surfaces, permitting the escape of the occluded gases. The melted steel finally
collects at the permanent bottom of the vessel from whence it may be drawn off as
required.
The gases occluded in the melted Steel pass out at the vent hole placed underneath
the lowest perforated bottom.
The action which takes place inside the vessel is as follows:-The molten Steel
being forced by its own gravity through small holes of a certain length in the first
perforated bottom, the Gases occluded in the molten Steel are to a certain degree
compressed and assume a greater elasticity on their passage through these perfora-
tions. As soon as the molten steel arrives as a very thin stream at the open space
underneath the first perforated bottom, the gases by reason of their compression
and consequent greater elasticity have a chance of passing through the thin stream
of molten steel and of escaping. The molten steel on arriving at the second
perforated bottom is obliged to change its surface and passes again through a
number of perforations and what gases may be still occluded have again a chance
of escaping. The friction caused by the passage of the molten steel through the
perforations, at the same assisting the elimination of the Gases.
Finally, the molten Steel arrives in the large space over the permanent bottom
of the vessel thoroughly dessicated and therefore free from any gases, which if not
permitted to escape, cause, on cooling, the objectionable air bubbles or blow holes in
Steel Castings.
If desired, an opening may be made close to the vent hole, for the admission of a
blast of a highly heated non oxydising Gas under pressure, which would meet the
molten steel on its final passage through the lowest perforated bottom and so assist
in the dessication of the molten steel and the escape of the occluded gases.
As the entire operation takes place in a neutral atmosphere no oxidation of the
metal can take place.