A Process of Manufacture of Granular Grinding, Cutting, and Sawing Material.
Year: 1899

page_text: Date of Application, 23rd Nov., 1899-Accepted, 27th Jan., 1900
COMPLETE SPECIFICATION.
A Process of Manufacture of Granular Grinding, Cutting, and
Sawing Material.
0
We, CARL LANGENSIEPEN and GEORG BACHMANN, both of 15, Giesser-Strasse,
Leipzig-Plagwitz, Germany, trading as. Backhaus and Langensiepen, Manu-
facturers, 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:-
In the processes of atomization of liquid metal by means of a steam or gas
jet, as for example, in the manufacture of metal molecules or globules" ("iron
grit," "chilled iron sand") the spherical particles of metal obtained vary widely
in size.
Where the minute metal globules are intended for use as grinding, cutting
and sawing material, they must in all cases first undergo a complicated sorting
operation by means of suitable sifting apparatus.
In order to enable the grinding, cutting and sawing medium to be utilized
to the best possible advantage, it should be made to consist of molecules or
globules as nearly as possible equal in size. This well known grinding cutting
and sawing material is therefore classified in the market into a somewhat large
series of grades or numbers" differing from each other in the size of the small
molecules or globules of which they are respectively constituted.
In the manufacture of the grinding, cutting and sawing material in question
two causes of somewhat serious loss of metal are observed. Of the small globules
obtained by the atomization of cast iron, not only all those which happen to
be too small, but all those, also, which exceed a determined size, are unser-
viceable as grinding and sawing material.
The waste constituted by globules or molecules which are too small is quite
unfit for use. But with regard to those globules or molecules which are rejected
as being too large, we have subjected them to a crushing or reducing process
and have then sorted or sifted the material thus divided by the usual method
so as to convert it into serviceable grinding cutting and sawing material; and
this has led to the discovery that the grinding, cutting and sawing material
produced in this manner is far more effective than the known grinding and
sawing material for hard stone, consisting of small spherical bodies or globules.
The effect of this novel grinding, cutting and sawing material is better even
than that of the grinding and sawing material now known produced from glass-
hard steel by crushing and sifting.
This may probably be accounted for by the fact that the small globular par-
ticles are lacking in "operative" sharp edges, while, the hardness of glass-hard
steel is much inferior to that of white cast iron.
In fact the large sized globules obtained by the well known process of manu-
facture of globular grinding, cutting and sawing material consist of white cast
iron.
The knowledge of this circumstance coupled with the experience we have

page_text: gathered has led to the completion of the present invention which the foregoing
remarks would perhaps enable to be readily understood even without further
comment.
The subject of the invention is a novel process of manufacture of granular,
grinding, cutting and sawing material.
Briefly stated, the process is this:
Cast iron melted in a cupola-furnace is first of all converted into white cast
iron by rapid cooling; this is then properly disintegrated, and finally, by the
usual sorting process, brought to the condition of serviceable grinding and
sawing material of the desired sizes or grades.
Simple as this process may at first sight appear, its practical performance is
by no means easy. For it should be borne in mind that large lumps of white
cast iron cannot without considerable difficulty be crushed or pulverized, while
the thin lamina (into which it may be more readily divided) on being pounded
are apt to yield a material of the fineness of flour which like the undersized
globules would prove a "dead" grinding, cutting and sawing medium. In
fact this method of procedure would result in a very large proportion of waste.
Now in order to obtain grinding and sawing material with a minimum of
waste and to render it possible to carry out the crushing operation with a mini-
mum of power, it is absolutely necessary, first and foremost, to obtain the white
cast iron in the condition of small lumps presenting a somewhat wide surface
or area, the fraction of which shows a fibrous texture and which consist of white
cast iron throughout.
The lumps of white cast iron should preferably be of the size of small nuts,
beans, peas or lentils, or at all events should be flat pieces not unduly exceeding
those objects in thickness; for if these bodies should turn out to be too bulky,
it must frequently happen that their inner parts still retain their crystalline
aspect, or in other words, still consist of grey cast iron, which by pounding crush-
ing &c can never yield a serviceable grinding cutting or sawing medium but
which results in a very great amount of waste.
For the purpose of obtaining lumps of white cast iron of the size and shape
of small nuts, beans, peas or lentils, as stated, various methods of casting may
be adopted.
A hot liquid stream of grey cast iron may, for example, be divided into small
particles by means of a water jet used in a manner similar to that in which a
jet of steam or compressed gas is employed according to the well known process.
The size of the pieces of white cast iron will be regulated according to the thick-
ness and speed of the water current, the thickness of the stream of hot liquid
cast iron, the direction of either in relation to the other, and the situation of
the water receiver intercepting the cast iron, in relation to the point of inter-
section of the two currents.
Another method of casting whereby the same object may be attained consists
in the employment of a disc or screen with radial grooves, which is placed in
a water receiver and is given a rotary motion so long as the hot liquid cast iron
continues to flow to the centre of said disc.
The disc but slightly emerges above the surface of the water in the tank.
By varying the speed of rotation of the disc, the size of the pieces of white cast
iron can be regulated.
Besides these two methods, there exist many others which lead to the same
result.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that
what we claim is:-
A process of manufacture of granular cast iron for grinding, cutting and
sawing purposes, the main feature of such process being that fused cast iron
whilst rapidly cooling is divided into small lumps of about the size of small

page_text: nuts, beans, peas, lentils or the like which by a crushing or disintegrating and
sorting operation are converted into the desired grinding, cutting and sawing
material.
Dated this 23rd day of November 1899.
HARRIS & MILLS,
23, Southampton Buildings, London, W.C., Agents.