Year: 1886

page_text: I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake & Co, Patent Agents,
Southampton Buildings in the County of Middlesex 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 improvements in percussion rock-drill tools, and applies
to those having at one end a head or shank designed to receive hammer blows, and
at the other end a chisel-like point or cutting-edge, the part between the ends.
being provided with grooves or threads for the purpose of conveying the rock-dust
to the opening of the bore.
The object of my invention is to provide a drill-tool that will clear the bore of,
the powdered rock which gathers in it during the progress of the boring, and thus
avoid jamming or choking which in some cases with a tool as heretofore employed
involves the sacrifice of the tool and the abandonment of the bore.
It is also essential that the tool should possess sufficient lateral strength not to
yield under the numerous and heavy blows of the hammer by which it is forced to
cut the rock.
My improvements consist in giving a certain shape to the threads hereinafter
more particularly described, the said shape being better adapted to the work to be,
performed; this thread being combined with a point or cutting edge adapted to
work under the blows of a hammer or other percussion instrument.
I attain the objects of this invention by forming a drill tool having a chisel or
diamond shaped cutting edge, or two or more cutting edges, the only important
point being that the cutting edge or edges shall be in a plane or planes passing
through the axis of the tool, so that it may receive the blow in a line which
coincides at every point with the said axis; and having a helical thread or threads
of which the upper surface is at right angles or nearly so with the axis of the tool
and the under surface slopes toward the axis to form a strong shoulder, and at the
same time leaves a cylindrical centre to the tool symmetrical at all points with
the axis.

page_text: better tool.
In the accompanying drawing,
Figure 1 is an elevation of a single thread drill-tool constructed in accordance
with my invention as herein described.
Figure 2 is a vertical section of the tool in a plane passing through the central
line of the cutting edge.
Figure 3 is a vertical view of the edge of the cutting point of the tool.
Figure 4 is an elevation of the drill when made with two threads, shewing the
flat side of the point.
Figure 5 is an axial section of the drill on a plane passing through the edge of
the chisel point.
Figure 6 is an elevation of the lower portion of the drill shewing the edge of
the point.
A is the tang of the drill; B is the flat or upper surface of the thread; b is the
cylindrical portion of the thread; O is the sloping under portion of the thread; E is
the cylindrical body of the drill; F is the chisel point of drill; and ffare the bevel
edges of the point or cutting edge.
In Figures 4, 5 and 6 B' is the second thread, b' is the cylindrical portion of the
thread and c is the sloping under portion of the thread.
x, are dotted lines indicating axial lines through which the sections are taken.
The improved tool consists in the simplest form of a cylindrical body having a
Bquare tang, or one of any convenient form, for inserting in the socket of the drill
operating machine and to receive the hammer blows whether applied by hammer
operated directly by hand or by means of suitable mechanism; of a chisel cutting
point which may be either straight or running to a point, the only important
feature being that it shall lie principally in a plane passing through the axis of the
tool; and of one or more spiral threads of peculiar form winding around and
integral with this central cylindrical core, the said thread developing into the cutting
point. The whole tool is so proportioned that it can be drawn out into a cutting
edge at a point of its height without upsetting, and by a simple process of
untwisting, flattening, and shaping.
The thread above described is of a particular form especially adapted to the
performance of its duty of raising and throwing out the dust produced by the
work.
In section it is somewhat like a right angled triangle, one of whose sides is
considerably longer than the other and of which the hypothenuse is curved.
If a long strip of metal having such a section were wound spirally about the
core with the longest side of the triangle next to the core it would form the threaded
portion of the tool; the shorter side forming the top of the thread, and the
hypothenuse forming the shoulder of the thread.
The thread formed in this way retains and lifts the dust, and the under surface
acts as a strong supporting shoulder to the drill. To avoid a sharp edge, a small
portion of the thread is parallel to the axis of the drill or slightly rounded. The
shape of the cross section of the thread may be compared to the shape of a ratchet
tooth.
The drill having a single thread will produce good results but I have found that
the double threaded drill is much to be preferred.
The operation of the tool is as follows that is to say :-the drill tool is slowly
rotated about its own axis, while at the same time it is receiving the blows of a
hammer; its point or cutting edge chips away and disintegrates the rock; as the
dust accumulates it is raised upon the flat upper surface of the thread to the top
of the hole and thrown out by the rebound of the tool under the repeated blows
of the hammer or hammers.
The peculiar shape of the thread prevents the dust from easily slipping back or
packing under the threads, and the thread is so formed as to leave a very strong

page_text: shank or body to the drill, which is very important in a tool that must withstand
the repeated blows of heavy hammers for a long period.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondent, I declare that what I claim is
First. A rock-drill constructed of one solid piece of metal with a point having
its cutting edge or edges in a plane or planes passing through the axial line of the
tool, and having the cylindrical shank or body of the drill surrounded by a single
spiral thread, its upper surface being at right angles to the axial line of the drill,
and uniting itself to the body of the drill by a sloping under surface, all substantially
as described and for the purpose set forth.
Second. A rock-drill constructed of one solid piece of metal with a point having
its cutting edge or edges in a plane or planes passing through the axial line of the
tool, and having the cylindrical shank or body of the drill surrounded by two equal
spiral threads, their upper surfaces both being at right angles to the axial line of
the drill, and both uniting themselves to the body of the drill by sloping under
surfaces, all substantially as described and for the purpose set forth.
Dated this 2nd dex of Fehmeory 1886
HASELTINE, LAKE & Co.,
For the Applicant.