Improvements in Percussion Drills.
Year: 1894

page_text: Date of Application, 11th Jan., 1894
Complete Specification Left, 11th Oct., 1894-Accepted, 17th Nov., 1894
[Communicated from abroad by Messrs. SIEMENS & HALSKE, of Berlin, in the
German Empire, Electrical Engineers.]
Improvements in Percussion Drills.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate, in the
City of Westminster, Electrical Engineers, do hereby declare the nature of this
invention to be as follows:-
In percussion drills of usual construction for boring comparatively deep holes,
it is necessary, as the boring proceeds, to detach the drill from the drill bar and
replace it by one of increased length, for which purpose it is necessary to remove
the entire machine from its position in front of the working in order to enable the
longer drill to be introduced into the bore hole, and then to fix the machine in its
former position again, whereby, in addition to the labor and loss of time involved,
other inconveniences arise.
These inconveniences may be obviated by making the drill bar tubular and
effecting the fixing and removal of the drills by introducing them from the rear
through the drill bar to the front end thereof and then suitably fixing them thereto.
But with such an arrangement it is necessary, in view of the great number of
drills that may be required, to construct the part thereof which is fixed to the drill
bar in the simplest and least expensive manner.
According to the present invention, this is effected by simply providing an
abutment-piece which is secured in the drill bar behind the end of the drill, after
this has been introduced, so that the rear end of the drill merely abuts against such
abutment piece, being secured in that position by any suitable fastening. By
preference we construct such abutment piece as a key, or flat plate passed through
opposite slots formed in the front end of the drill bar, the plate having external
projections at each end which project backwards beyond the slots when the plate is
placed in position, and thus prevent it from shifting laterally when once the end of
the drill stem is brought close against its front edge. The drill stem is secured in
this position by preference by forming a groove or flat face on one side thereof
against which bears a flat wedge piece introduced through another slot in the drill
bar and secured by a sliding ring driven over its inclined outer face.
For removing the drill, the ring is driven back, the key removed, and the drill
stem drawn slightly forward so as to allow the abutment piece to be first slid
forward in its slots till the projections are clear, after which it is simply drawn out
sideways, so as to allow a free passage for the drill.
For facilitating the introduction and removal of the drill through the tubular
bar, the thickened rear end of the drill stem is made slightly smaller in diameter
than the internal diameter of the bar, and the front end of the latter is made with
a correspondingly smaller internal diameter than the other part and is accurately
bored out to fit the turned rear end of the drill stem.
Dated this 11th day of January 1894.
ABEL & IMRAI,
Agents for the Applicants.

page_text: We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate,
in the City of Westminster,, 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 :-
In percussion drills of usual construction for boring comparatively deep holes,
it is necessary as the boring proceeds, to detach the drill from the drill bar and
replace it by one of increased length, for which purpose it is necessary to remove
the entire machine from its position in front of the working in order to enable the
longer drill to be introduced into the bore hole and then to fix the machine in its
former position again, whereby, in addition to the labor and loss of time involved
other inconveniences arise.
These inconveniences may be obviated by making the drill bar tubular and
effecting the fixing and removal of the drills by introducing them from the rear
through the drill bar to the front end thereof and then suitably fixing them thereto.
But with such an arrangement it is necessary in view of the great number of drills
that may be required, to construct the part thereof which is fixed to the drill bar
in the simplest and least expensive manner.
According to the present invention this is effected by simply providing an
abutment piece which is secured in the drill bar behind the end of the drill after
this bas been introduced, so that the rear end of the drill merely abuts against such
abutment piece, being secured in that position by any suitable fastening. By
preference we construct such abutment piece as a key, or flat plate passed through
opposite slots formed in the front end of the drill bar, the plate having external
projections at each end which project backwards beyond the slots when the plate
is placed in position, and thus prevent it from shifting laterally when once the
end of the drill stem is brought close against its front edge. The drill stem is
secured in this position by preference by forming a groove or flat face on one side
thereof against which bears a flat wedge piece introduced through another slot in
the drill bar and secured by a sliding ring driven over its inclined outer face.
For removing the drill, the ring is driven back, the key removed and the drill
stem drawn slightly forward so as to allow the abutment piece to be first slid
forward in its slots till the projections are clear, after which it is simply drawn
out sideways, so as to allow a free passage for the drill.
For facilitating the introduction and removal of the drill through the tubular
bar, the thickened and accurately turned rear end of the drill stem is made slightly
smaller in diameter than the internal diameter of the bar and the front end of the
latter is made with a correspondingly smaller internal diameter than the other part
and is accurately bored out to fit the turned rear end of the drill stem.
Thus the drill can be readily inserted through the rear end of the bar until its
thickened bead is situated in the front end of the latter, whereupon the abutment
piece is introduced and the drill secured as above described.
The accompanying drawing shews the above described mode of fixing drills in
tubular drill bars, Figs. 1 and 2 being sectional views of the same at right angles
to each other. Of the drilling machine only the drill bar P and its guides E E
are shewn, as the other parts have no reference to the present invention.
P is a tubular drill bar, the cylindrical bore H of the rear part of which is of
sufficiently larger diameter than the thickened head B¹ of the drill stem B to
pass freely through it, while the bore h of the front end is accurately turned of
a smaller diameter to fit the head B', the bores H and being connected by a
coned part c.

page_text: The front part of the bar P has opposite slots through which is passed the
abutment piece Q after the drill B B'has been inserted in position. The piece Q
has two small projections at the rear side, the slots / being of sufficient size to
allow of their passage, so that when Q has been inserted and is moved back
against the rear ends of the slots, the projections prevent it from shifting laterally.
When the abutment Q has thus been placed in position the head B' of the drill stem
is slid slightly back so as to bear with its rear end against the front face of the
piece Q, and the drill is then fixed in this position by any suitable means such as
set screws &c.
The arrangement shown on the drawing consists in forming a flat notch on one
side of the head B¹, with which engages a wedge & inserted through a slot in the
bar P, and secured in that position by driving a ring over it from the rear, so that
the blows of the drill only tend to tighten the ring.
An important advantage afforded by the above described construction, in addition
to that first herein stated, is that with machines having only a small stroke an
increase is thereby afforded in the effective range of feed as compared with known
constructions. Namely with machines in which the drill is inserted from the front,
the front end of the drill bar has to be situated a distance away from the face of
the working at least equal to the total length of the drill and consequently when the
rear end of the latter has been inserted the requisite distance into the socket of
the drill bar, the latter must first be shifted forward together with the drill to the
extent of that distance in order to bring the cutter of the drill against the face of
the working before the effective feed can commence; the extent of such forward
shifting is consequently a loss in the effective feed. This loss is practically
entirely avoided with the above described construction, as the end of the drill
bar P need only be removed from the face of the working a distance equal to the
length of the drill shank projecting beyond it, when in position, plus the small
distance which it is required to shift the drill forward in order to allow the small
projections of the piece Q to pass through the slots of P.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. Constructing percussive drills with tubular drill bars through which the drills
are introduced into position and removed from the rear end, the rear end of the
drill stem, when inserted, being made to bear against an abutment piece which is
afterwards fixed behind it in the drill bar, substantially as described.
2. In percussive drills constructed as set forth in the preceding claim, forming
the tubular drill bar with the rear part of its bore of a sufficient size for the
enlarged head of the drill stem to pass freely through it, while the front part of
the bore is made of a diameter to accurately fit the said enlarged head, the requisite
abutment being afforded to the head by means of an abutment piece or key
inserted laterally through slots in the front part of the drill bar substantially as
described.
Dated this 11th da of October 1901
ABEL & IMRAY,
Agents for Applicants.