Improvements in and relating to Materials and Tools for Grinding, Cutting, and Polishing, and in the Manner of Sharpening the same.
Year: 1895

page_text: Date of Application, 13th Dec., 1895-Accepted, 22nd Feb., 1896
COMPLETE SPECIFICATION.
Improvements in and relating to Materials and Tools for Grinding,
Cutting, and Polishing, and in the Manner of Sharpening the
same.
I, AUGUST WILHELM RINGSTROM, of 34, Storgatan, Örebro, in the Kingdom
of Sweden, Engineer do hereby declare the nature of this invention and in what
manner the same is to be perforined, to be particularly described and ascertained in
and by the following statement :-
The present invention relates to a composition for grinding, cutting or polishing
in which the adhesive or binding element, consisting of a metal or metallic alloy, is❤
so to speak, soldered together with the grinding element, or more properly, with a
metallic covering which surrounds the separate grains and which adheres thereto,
either by ordinary adhesion or as cement.
The object of this invention is to prepare such a grinding and cutting composition
that tools may be made thereof thin enough to be used as saws for cutting glass,
stone and other hard materials. These tools, when for instance in the form of discs,
moreover, do not break so easily as ordinary grinding-discs whose grains are held
together by cement, and they can, without difficulty, be kept sharp by eating away
the adhesive element by means of a corrosive or otherwise."
The manner of preparing the grinding-composition is as follows:-
The grinding-element, diamond-dust, corundum, carborundum emery etc., is given
a metallic covering in some of the following ways.
1. Chemically, by placing the grinding-element in a proper solution of salt
to which a reducing element is added. For instance a solution of oxide of silver in
ammonia, procured by precipitating nitrate of silver with soda and dissolving the
precipitated oxide of silver in ammonia,-mixed with substances which reduce the
silver, such as grape-sugar, tartaric acid, etc.
2. Mechanically, by adding to the grinding-element a cement, for instance,
water-glass cement, which, after hardening, resists a high temperature, and which
is not effected by the acids used in the process of manufacture.
A sufficient quantity of the cement is taken to well cover all the grinding-
particles after which a proper quantity of finely powdered metal or metal-dust is
added, when the whole is shaken in a mixing-drum or in some other way. The
metallic dust will then come to strongly adhere to the grinding-particles and form
a thin metallic covering or coating around each one of them.
The metallic covering formed around the grinding-particles in the manner
described either in paragraph 1 or 2, is extremely thin, but has, however, sufficient
strength and power of resistance to be used at subsequent period in the fabri-
cation, when it comes to soldering together the metal-plated grinding-particles; this
is only possible, however, if the metal used as adhesive element, melts at a low
temperature, and does not easily alloy with the metal which surrounds the grinding-
particles, otherwise the metallic covering on these grains must be strengthened by
galvanic treatment as described below.
3. The grinding-particles may also be provided with metallic covering by
galvanic treatment, which is to be preferred, since the metallic covering can
at once be made much thicker in this way than by the other methods described
above.
In order to give the grinding-particles a covering which is a conductor of
electricity, thereby making the galvanic process possible, they are treated in the

page_text: same manner as described in paragraph 2, but with the exception that pulverized
graphite, peroxide of manganese or similar conductive bodies are used, instead of
the more expensive metallic dust.
The grinding particles thus encased in a conductive covering and also those
provided with metallic covering as described in paragraphs 1 & 2, can be provided
with a thicker metallic covering by galvanic treatment.
This galvanic precipitation is accomplished in the same way as usual in
galvanizing small objects. It might, however, be well to mention some of the
different methods which can be used, namely,
(a) The grinding-particles covered with a conductive coating are immersed in a
suitable metal salt-bath, for instance an alkaline, organic coppersalt bath, where
they are allowed to come into contact with a positive metal, for instance zinc.
(b) For the conductive coating of the grinding-element is used a metal, for
instance, finely powdered iron, which is capable of precipitating on itself the metal
contained in the metal-salt of the bath, and the bath should then consist of a
solution of sulphate of copper in water with an addition of ammonia.
(c) The grinding-particles are allowed to come into contact with the negative
pole of a source of electricity, and, if so desired, the cathode is given the form of a
vessel in which is place the electrolyte at the decomposition of which the metal is
precipitated upon the grinding-particles.
After the grinding-particles have been given a metal coating in some of the
above described ways, they are mixed into a nielted metal or a melted metal alloy,
and thus become soldered together and further covered. In casting the composition,
it can be given proper form, and the grains are held tightly together when it has
cooled. Such a metal alloy may consist of metal and sulphur, phosphorous, carbon,
silicon, or some other metalloid. In respect to form, the metal-bound grinding-
composition can be cast into discs of different sizes and shapes for cutting or
grinding, it can be soldered fast to coarser or finer wire or endless wire-rope for
cutting out blocks or slabs of rocks etc., it can also be cast on to metal cloth
and be used as emery-cloth and on to the edge of thin metal plates to be used as
saw-blades.
In order to sharpen the metal-bound grinding-composition, the metal coating can
be partially removed, while the tool is in use, so that the outer grinding-particles
are partly exposed. This can be done in a mechanical way by grinding away part
of the metal coating, by means of fine, sharp sand and water or oil, or in a chemical
way of corroding away the metal coating by means of a suitable corrosive or in a
galvanic way, when the binding element of the grinding-composition consists of an
electropositive metal, for instance zinc, by surrounding a portion of the circumference
of the disc with a trough of an electro-negative metal, such as copper and filling
the trough with a solution of a salt, for instance common or culinary salt and
connecting one of the journals of the disc with the trough by means of a conducting-
wire.
In order to moderate the grinding-power of the grinding-disc, that is to say, to
make it, while working, bite more or less, a greater or lesser portion of the metallic
binding element can be removed in a galvanic way by applying more or less strong
electric current.
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 manner of preparing a material for grinding, cutting, or polishing in
which the grinding-particles are held together by metal, consisting in covering the
grains of the grinding element with a coating of metal, which is done in a chemical,
galvanic, or mechanical way, for the purpose of permitting the grains to be soldered
together, and in mixing thus prepared grinding-particles into melted metal or
a melted metal alloy, with the view of rendering it possible to cast the grinding
composition into suitable form and to give it necessary compactness, strength and

page_text: flexibility and eventually to make it practical to attach it to discs, wire-ropes,
wires, cloth or plates.
2. Material, and tools manufactured thereof, prepared according to the method
of manufacture described in Claim No. 1.
3. The above described methods of sharpening this kind of tools in a mechanical,
chemical, or galvanic way before or while it is at work.
Dated this 13th day of December 1895.
W. P. THOMPSON & Co.,
31, High Holborn, London, W.C., Patent Agents for the Applicant.