Improved Boring Tools for Boring in Stone and other Hard Friable Material.
Year: 1891

page_text: Date of Application, 30th Oct., 1891
Complete Specification Left, 6th July, 1892-Accepted, 6th Aug., 1892
PROVISIONAL SPECIFICATION.
Communicated from abroad by Messrs. SIEMENS & HALSKE, of 94, Markgrafen-
strasse, Berlin, in the German Empire.]
Improved Boring Tools for Boring in Stone and other Hard
Friable Material.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate, West-
minster, in the County of Middlesex, Electrical Engineers, do hereby declare the
nature of this invention to be as follows:-
This invention has for its object to prevent the. rapid wearing away of boring
tools when boring in hard stone and other similar material, and it consists essentially
in replacing the concussive action of percussion tools or the abrading action of
rotating tools, by the crushing action of hard metal balls which are caused, while
subject to pressure, to roll over the surface of the material to be operated upon.
This rolling action of the boring balls is produced by forming on the lower end of
the boring rod which constitutes the abutment of the balls, an annular groove
of semicircular section, so that on the rotation of the boring rod round its axis,
while subject to end pressure, the balls will roll freely both in the groove of the
rod and on the surfaces of the stone or other more or less friable or brittle material,
and thus in exerting a crushing action successively upon comparatively small
portions of the surface, they will grind the material to powder.
From the above described arrangement it follows that the wear, if any, of the
abutment will take place uniformly all round in the annular groove, resulting merely
in the deepening of the latter and thus preventing any defective action being pro-
duced by such wear.
The arrangement of the balls and boring rod may be variously modified.
Thus according to one arrangement suitable for small borings, a solid cylindrical
boring rod has an annular groove formed in its lower end, into which fit three or
more balls, these being made to project slightly beyond the diameter of the boring
rod, so as to cause the boring produced by the balls to be slightly larger than the
rod.
The latter has a central longitudinal passage, through which water is made to
flow down so as to wash out the pulverised material from the boring. Any small
core of material left between the balls will splinter away as the boring proceeds,
and the pieces falling down, will be crushed by the balls.
In order to prevent the balls from falling away from the boring rod, this, as also
the balls, being made of iron or steel, may be made magnetic by surrounding the
upper part of the rod by a coil through which an electric current is passed, or
the groove of the rod may be made of such a form that the balls cannot fall out
of it.
According to another arrangement, the boring rod is made tubular with a solid
cylindrical lower end which may constitute a permanent magnet; or again the
upper part of the rod may be solid and the lower end tubular, with a separate
central cylindrical core so that the annular groove is formed of two separate con-
centric parts, which are constituted respectively north and south poles by an electric
circuit passed round the central core.
For large borings the entire boring rod and bore head may be made tubular, so
as to form an annular boring, leaving a central core, which is afterwards broken
away.
When used for enlarging a boring, the annular groove is made more or less in the
cylindrical side surface of the boring rod so that the balls act with more or less side
pressure as well as downward pressure against the bore hole.

page_text: When the bore rod and balls are not made of magnetic material the balls may be
held in position by any suitable means such as by the form or position of the groove
as above described, or by projecting claws embracing the balls &c.
Dated this 30th day of October 1891.
ABEL & IMRAY,
Agents for the Applicants.
Improved Boring Tools for Boring in Stone and other Hard
Friable Material.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate, West-
minster, in the County of Middlesex, Electrical Engineers, 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 :—
This invention has for its object to prevent the rapid wearing away of boring
tools when boring in hard stone and other similar material and it consists essentially
in substituting for the concussive action of percussion tools or the abrading action
of rotating tools, the crushing action of hard metal balls which are caused, while
subject to pressure, to roll over the surface of the material to be operated upon.
This rolling action of the boring balls is produced by forming on the lower end of
the boring rod which constitutes the abutment of the balls, an annular groove
of nearly semicircular section so that on the rotation of the boring rod round its
axis while subject to end pressure, the balls will roll freely both in the groove of
the rod and on the surfaces of the stone or other more or less friable or brittle
material, and thus in exerting a crushing action successively upon comparatively
small portions of the surface, they will grind the material to powder.
From the above described arrangement follows that the wear, if any, of the
abutment will take place uniformly all round in the annular groove, resulting merely
in the deepening of the latter and thus preventing any defective action being pro-
duced by such wear.
The arrangement of the balls and boring rod may be variously modified as
illustrated by the accompanying drawings.
According to one arrangement shewn by Figs. 1 and 14 suitable for small
borings, a solid cylindrical boring rod R has an annular groove formed in its lower
end into which fit three or more balls B these being made to project slightly beyond
the diameter of the boring rod, so as to cause the boring produced by the balls to
be slightly larger than the rod.
Through the rod there is a central longitudinal passage, through which water is
made to How down so as to wash out the pulverised material from the boring. The
small core of material that may be left between the balls splinters away as the
boring proceeds, and the pieces falling down are crushed by the balls.
In order to prevent the balls from falling away from the boring rod, this, being
like the balls made of iron or steel, may be made magnetic by surrounding the
upper part of the rod by a coil C through which an electric current is passed,
the balls being thus held in the groove by attraction.
According to another arrangement shewn by Figs. 2 and 2^, the boring rod R is
made tubular with a solid cylindrical lower end S which may constitute a permanent
magnet; or as shewn by Figs. 3 and 3ª the upper part R of the rod may be solid
and the lower end T tubular with a separate central cylindrical core M which is
wound with a coil of insulated wire so that the annular groove is formed of two
separate concentric parts NS which are constituted respectively north and south
poles by an electric circuit passed through the coil of wire round the central
core.
For large borings the entire boring rod R and bore head H may be made tubular

page_text: as shewn by Figs. 4 and 4ª so as to form au annular boring leaving a central core,
which can afterwards be broken away.
When used for enlarging a boring, the annular groove is made, as shewn by
Figs. 5 and 5, more or less in the cylindrical side surface of the boring rod, so that
the balls act with more or less side pressure as well as downward pressure agaiust
the bore hole.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
---
1. For boring in stone or other hard friable material a tool consisting of a boring
rod with balls fitted to run in a groove at the lower end of the rod, arranged and
operating substantially as described.
2. The herein described method of retaining the steel or iron balls in the groove
of a steel or iron boring rod by rendering the rod magnetic by an electric current,
substantially as described.
Dated the Jef T..1.. 1005
ABEL & IMRAY,
Agents for the Applicants.