Year: 1887

page_text: 1, JOHN HARRISON, of Middlesborough-on-Tees, in the County of York, Stone
Cutter, do hereby declare the nature of this invention to be as follows:-
My Invention relates to the composition and manufacture of metallic grit to be
employed for cutting or grinding stone or the like hard substances by being forcibly
rubbed under pressure by means of a saw blade or other instrument in the usual
manner.
The essential features of my invention are, an improvement in the composition of
the material of which the metallic grit is formed, and the process employed in the
manufacture thereof; my object being to produce metallic grains or globules which
shall be sharper and keener in their cut, and shall retain their original sharpness or
keeness for a longer period than the grains or globules hitherto employed for this
purpose.
In the composition of the material from which I produce my improved grains or
globules, I mix Hematite pig iron with the Cleveland brands known as No. 1 and
forge pig iron, to which I add ordinary serap iron, from these ingredients when
mixed by weight in equal proportions I obtain good results, the toughness of the
grains or globules I attribute to the Hematite and No. 1 Cleveland iron, and their
sharpness or keeness to the Cleveland forge and scrap iron, which latter ingredient
also facilitates the production of metallic grit of the required degree of fineness by
making the metal very fluid in the molten state.
The relative proportions of the above named ingredients may be varied without
departing from the nature of my invention, so long as each of them or their well
known equivalents are present in such quantities as to impart to the grains or globules
the combined properties of keeness and sharpness in their cut, with a power of
retaining their keeness or sharpness for a long period.
In the process of casting the metal into the grains or globules, the mixture is first
melted down to a very fluid state, the more fluid the better, and as it flows from the

page_text: cupola or ladle is reduced to a finely divided state by encountering a jet of steam of
sufficient pressure to carry the molten metal a distance of several feet, as for instance
twenty to thirty feet, at which distance the metal falls down into a tank of cold
water in the form of grains or globules which are thereby chilled; salt water, such
as would be obtained from an ordinary tidal river, being better adapted for this
purpose than fresh water.
The material when taken out of the tank is completely saturated and would in
consequence rapidly rust and coagulate into a solid mass, to avoid which I pass it
through a dissicating apparatus of the following construction ;-a long pipe, tube, or
the like passage is enclosed inside a barrel of much larger diameter, the difference in
diameter of the pipe and barrel forming a steam space, so that by passing the
material slowly through the pipe, tube, or the like passage by means of a worm
conveyor fitted up if necessary with suitable paddles for churning up the metallic
grit which is thereby dried by the action of the steam which does not affect its
temper, the metallic grit is also brightened by the attrition of its own particles upon
each other; the grains or globules can then be sorted to various sizes by means of
sieves.

page_text: COMPLETE SPECIFICATION.
.
Improvements in the Composition and Manufacture of Metallic
Grit for Cutting or Grinding Stone or the like Hard
Substances.
I, JOHN HARRISON, of Middlesbrough-on-Tees, in the County of York, Stone
Cutter, 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:-
My Invention relates to the composition and manufacture or preparation of metallic
grit to be employed for cutting, grinding rubbing or polishing stone or the like hard
substances, such as glass, pottery and metal, the metallic grit being applied to the
material to be cut or ground in the condition of loose grains or globules which are
forcibly rubbed under pressure by means of a saw blade or other instrument in the
nsual manner, or the said grains or globules are made to adhere to some article or
material so as to serve the purposes for which emery cloth or emery wheels are
usually employed.
The essential features of my invention are the particular composition of the material
or the mixture of ingredients of which the metallic grit is composed, and the process
employed in producing and preparing the grit in a condition suitable for cutting,
grinding, rubbing or polishing stone or other material without producing grooves or
scratches to be removed by a subsequent operation, my object being to produce the
metallic grit in the form of grains or globules of the required degree of fineness
which are sharper and keener in their cut and retain their original sharpness and
keeness for a longer period than the metallic grit hitherto employed, whereby the
operation of cutting, grinding, rubbing or polishing is rendered less costly and a
better finish obtained.
In the composition of the material from which I produce metallic grit in accordance
with my invention, I mix hematite pig iron with the Cleveland brands known as No. 1
and forge pig iron, to which I add ordinary scrap iron; from these ingredients, when
mixed by weight in equal proportions I obtain good results, the toughness of the
grains or globules I attribute to the hematite and No. 1. Cleveland irons, and their
sharpness or keeness to the Cleveland forge and the scrap iron, which latter ingredient
also facilitates the production of metallic grit of the required degree of fineness by
making the metal very fluid in the molten state.
The relative proportions of the above named ingredients may be varied without
departing from the nature of my invention so long as each of them or their well
known equivalents are present in such quantities as to impart to the grains or
globules the requisite properties of keeness and sharpness in their cut, combined with
a power of retaining their keeness or sharpness for a long period, thus for instance,
pig iron containing 5 per cent. of silicon and from 2 to 3 of per cent. phosphorous,
whether obtained from one or more brands mixed with scrap iron, will produce grains
or globules of the requisite toughness and hardness.
In the process of casting the metal into grains or globules of the requisite
-dimensions or degress of fineness, the mixture is first melted down to a very fluid
state, the more fluid the better, and as it issues from the cupola or ladle encounters a
jet of steam or air of sufficient force to scatter the molten metal into finely divided
particles which drop into a tank of water to a distance extending several feet, as for

page_text: instance, twenty or thirty feet, the greater the distance the smaller the particles which
take the form of grains or globules of an approximately spherical form, and are
rendered intensely hard by being chilled in the water, salt water such as would be
obtained from an ordinary tidal river being better adapted for this purpose than fresh
water.
The material when taken out of the tank is completely saturated and would in
consequence rapidly rust and coagulate into a solid mass, to avoid which and to
retain it in the finely divided state in which it is to be used, I pass it through a
dissicating apparatus of any suitable construction for exposing the metallic grit to a
temperature sufficiently high to remove all moisture without affecting the temper of
the metallic grains or globules, as for instance, an apparatus of the following
construction :-a long pipe, tube, or the like passage placed in a horizontal position is
enclosed within a barrel or other receptacle of much larger diameter or sectional
area so as to form a chamber which envelopes the small central pipe or tube, by
passing the metallic grit slowly through the central pipe or tube by any well known
means, such as a worm conveyor, and adinitting steam, hot air, or the gases from a
furnace to the surrounding chamber at a moderate temperature, the particles of
metallic grit become thoroughly dried in their passage through the apparatus.
When the metallic grit employed is composed of a mixture of various sizes,
grooves or scratches are cut into the surface of the stone or other material by the
operation of sawing which have to be removed by a subsequent operation involving a
waste of material and loss of time, and unless the metallic grains or globules are of
the requisite hardness and toughness to bear the pressure usually applied to them in
the operation of cutting or grinding stone or other material of a similar degree of
hardness, the size of the metallic particles if uniform at first are liable to become
unequal as the operation proceeds. The grains or globules when made of the
ingredients hereinbefore described in accordance with my invention are of the
requisite hardness and toughness to retain their original form and dimensions so that
when sorted to a series of sizes by means of sieves, any size most suitable for the
particular operation in hand may be selected and may be relied on to effect a clean
even cut throughout the operation. The sizes found most useful are such as would be
obtained from a series of sieves, the finest of which has 50 meshes to the inch, and
the coarsest 12 meshes to the inch, the intermediate grades being 40, 30, 20 and 14
meshes to the inch, the mere dust having been first removed by exposing the grit to
the action of a blast.
Having now described the nature of my invention and in what manner the same
may be carried into effect, what I claim is :-
Firstly In the manufacture of metallic grit, the metal composed of the
particular mixture of ingredients or their well known equivalents for imparting to
the grains or globules the requisite degree of hardness and toughness to enable them
to retain their original forms and dimensions when subjected to the pressure usually
applied in the operation of cutting or grinding stone or the like hard material,
substantially as and for the purpose as hereinbefore described.
Secondly-The process of preparing the metallic grit for use in which a dissicating
apparatus is employed for drying the grit as a subsequent operation to atomizing the
metal by a steam jet or its equivalent into grains or globules of the required degree
of fineness which are chilled by dropping into a tank of water, substantially as and
for the purpose as hereinbefore described.
L
ր
3 1000
G. J. CLARKSON,
Agent for the Applicant.