Improvements in Percussion Drills and other Percussion Tools Worked by Electricity.
Year: 1891

page_text: Date of Application, 1st Sept., 1891
Complete Specification Left, 9th May, 1892-Accepted, 11th June, 1892
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Messrs. SIEMENS & HALSKE, of Berlin, in the
German Empire, Electrical Engineers.]
Improvements in Percussion Drills and other Percussion Tools
Worked by Electricity.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate,
Westminster, in the County of Middlesex, Electrical Engineers, do hereby declare
the nature of this invention to be as follows:-
This invention relates more particularly to percussion drills. Such drills require
when working, to perform three different motions. Firstly, the drill must receive
a percussive or hammering motion in the direction of its axis ; secondly, it must at
the same time revolve slowly round such axis; and thirdly, it must be propelled
forward at a greater or slower speed according to the nature of the material
operated upon.
The present invention has for its object, to effect these three simultaneous motions
by means of a single electro-motor.
For this purpose a frame capable of being slid forwards or backwards in a fixed
support by a screw spindle and nut motion worked by hand, carries in suitable
guides a slide in bearings on which is rotatably supported the drill spindle, so that
the slide in travelling to and fro in the frame imparts the requisite percussive
motion to the drill spindle. To the middle of the frame, at right angles to the
motion of the slide and drill spindle, is fixed the frame of an electromotor of any
known construction with rotating shaft, the centre line of such motor shaft being
made to intersect the centre line of the drill spindle. To the end of the motor
shaft is fixed a crank, the pin of which rotates in a plane parallel with the plane of
the slide, just above the drill spindle. The crank pin carries a loose ring having
opposite bosses to which are connected the ends of two helical springs, the other
ends of which are connected respectively to bosses on the before mentioned
bearings at each end of the slide, so that by the rotation of the crank a
reciprocating motion will be imparted to the slide and drill spindle, through the
medium of the two springs, which act as elastic connecting rods, and thus the
requisite percussive motion will be imparted to the drill.
In place of the helical springs might obviously be employed any other device
affording an elastic connection between the crank pin and the slide, such as two
connecting rods each of which is formed in two parts, the one part acting as an
air cylinder, into which fits the other part acting as a plunger, so as to form an air
spring, or the rods may be formed in two telescopic sliding parts between abut-
ments on which are placed caoutchouc washers acting as springs. Or again the
connecting rods may be made rigid, and merely have a suitable elastic connection
with the slide, the essential feature of the construction being the provision of two
opposite elastic connections between the crank pin and the two ends of the
slide.
For effecting the rotation of the drill spindle round its axis during such percussive
motion, various known arrangements may be employed, thus .the frame may carry,
by a bracket at the rear end, the one end of a rod having one or more screw
threads of very quick pitch formed on it. The other end of this rod enters the
hollow rear end of the drill spindle which has a female screw thread fitting
the rod.
The said rod being free to revolve in its bracket in one direction, but prevented
from revolving in the other direction by a pawl and ratchet motion, it will be seen
that, assuming the rod to be prevented from rotating while the drill spindle is

page_text: performing its forward motion, then the drill spindle and its drill will be caused by
the screw thread of the rod to turn through part of a revolution during its forward
stroke, while during the backward stroke, the drill spindle being prevented from
turning by the friction in its bearings, will cause the screw rod to turn backwards
in its support.
Instead of working the screw spindle for advancing the drill during working by
hand such advance may be effected automatically, by providing on the feed spindle
a ratchet wheel, with which gears a pawl carried by one end of a double ended
spring lever, pivotted to the frame and having at its other end a hinge-jointed
piece, which at each backward stroke of the slide carrying the drill spindle is acted
upon by a projection on the slide so as to cause the lever to effect a partial rotation
of the feed spindle by means of the pawl and ratchet gear. At the commencement
of the drilling operation, when the stroke of the drill is only small, the projection
on the slide remains in contact with the feed lever, and consequently this has no
motion imparted to it, and there is no forward feed of the drill.
It will be evident that the above described mechanism for imparting motion to
the drill spindle is equally applicable to other tools, such as hammers operating
with percussive action.
Dated this 1st day of September 1891.
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Percussion Drills and other Percussion Tools
Worked by Electricity.
We, SIEMENS BROTHERS & Co. LIMITED of 12 Queen Anne's Gate,
Westminster, 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 relates more particularly to percussion drills. Such drills require
when working, to perform three different motions. Firstly, the drill must receive a
percussive or hammering motion in the direction of its axis; secondly, it must at
the same time revolve slowly round such axis; and thirdly, it must be propelled
forward at a greater or slower speed according to the nature of the material
operated upon.
The present invention has for its object, to effect these three simultaneous motions
by means of a single electro-motor.
The accompanying drawings shew a construction of percussion drill by means of
which this object is fulfilled.
Fig. 1 shews an end elevation and section on line a b.
Fig. 2 shews a sectional side elevation.
Fig. 3 shews a plan.
Figs. 4, 5 and 6 shew cross sections taken respectively on lines cd, ef, and g h.
The percussion drill A is fixed in any suitable known manner to the drill
spindle B the drill receives any known configuration suitable for the description of
rock on which it is to act and a length suitable for the depth of bore hole which
it is required to make. The carriage C on which are the bearings of the rotatable
spindle B is carried by the moveable guide frame D in such manner, that it can
slide freely to and fro thereon in the direction of the drill axis. To the guide
frame D is rigidly fixed the framing of the electromotor E which may be of any
suitable known construction.
The motor shaft F is arranged to be in the same vertical plane as the axis of
the drill spindle, and carries at its end a crank G. The crank pin G' carries
rotatable ring H having two opposite projections of such a form that the two
helical springs II can be readily attached thereto. These springs I serve to

page_text: connect the crank pin G' with two similar pins J J which are formed in one with
or fixed to the carriage C and which, like the crank pin carry rotatable rings K K
serving for the attachment of the springs I. Thus on the rotation of the motor
shaft the springs I act as connecting rods causing the carriage together with the
drill spindle to slide to and fro in the guide frame D, whereby the drill is made to
act percussively upon the rock or other material opposed to it.
This very simple means for converting the rotary motion of the motor shaft into
a percussive motion of the drill spindle constitutes the essential feature of the
present invention. The elastic connecting rods may either be formed as helical
springs as described and shewn at Figs. 2 and 3, or they may be otherwise
constituted, such as by a pneumatic spring L as at Fig. 8, or as a caoutchouc
buffer spring M as at Fig. 7.
The essential feature of the invention could also be carried out by making the
connecting rods rigid in themselves, and connecting them by springs or other
elastic media with the carriage C, the essential feature of the invention consisting
in the uninterrupted elastic connection of the motor crank with the carriage C
carrying the drill spindle.
The second and third of the above mentioned descriptions of motion are obtained
by known means from the reciprocating motion imparted to the drill spindle in the
manner described.
In the rear end of the tubular drill spindle B are formed several screw threads
of quick pitch into which take corresponding threads formed on the screw
spindle N, which is rotatably carried in the hollow head piece O formed in one
with the guide frame D. The screw spindle N has fixed on it a ratchet wheel o
which is prevented from revolving in one direction by the two pawls P P
(Figure 5).
This arrangement acts as follows: At each backward motion of the carriage C
the ratchet wheel o together with the screw spindle N will be turned in one
direction through an angle depending on the pitch of the screw threads and the
length of the stroke. On the forward motion of the carriage however, the pawls
hold the ratchet wheel and spindle preventing them from rotating in the contrary
direction, and consequently the drill spindle B is caused by the screw threads of Ń
to revolve through a corresponding angle during its forward motion.
Lastly the advance of the guide frame D which carries the entire drilling
apparatus, is effected by the rotation of the screw spindle, which can be rotated by
hand by the crank handle Q. The advance of the frame can however be effected
automatically, if desired, by providing, in the manner usual with percussive drills,
a ratchet wheel R the boss of which fits with a coned bore on to a coned part of
the boss of the crank handle Q, so as to be frictionally coupled to the advancing
spindle N.
The carriage C has a projection T and on the frame D is pivotted a lever U the
one end of which carries a spring pawl V (Fig. 4.) which acts upon the ratchet
wheel R. The other end of the lever U is acted upon by the projecting rail T
so as to cause the pawl V to turn the ratchet wheel and advancing spindle N at
each backward stroke of the carriage.
To prevent a sharp blow when the rear end of the rail T comes in contact with
the lever U the end of this is formed with a hinge-jointed piece U which is held
in a straight position by a spring U', but which is turned into the angular position
shewn at Fig. 3 when the end of the rail T comes in contact with the small roller
at its end. When, in working, the stroke of the carriage and drill is of so limited
an extent that the rail-projection T only slides backwards and forwards against the
end of the lever U without coming out of contact therewith the lever U is not
moved and there is no advance of the frame. When however owing to the
deepening of the bore hole the stroke increases to such an extent that in the
forward motion of the carriage the end of the rail T passes beyond the end of
the lever U, then the spring U³ of this lever will force the pawl end outwards and
the end U¹ inwards, so that on the following backward motion of the carriage the

page_text: rail T in pushing the end U¹ outward will cause the pawl end to move inward,
whereby the pawl V will be made to turn the ratchet wheel R and screw spindle N
through a certain distance, thus advancing the frame D to a corresponding
extent.
In the above, the invention has been described in its special application as a
percussive drill; it will however be evident that the above described main feature
of the invention, namely the elastic connection of the crank of an electro-motor
to the two points of a percussive tool is equally applicable to other tools, such as
hammers, stamps, and the like, operating with a percussive action, where the crank,
by its double elastic connection with the tool or its spindle firstly causes such tool
to strike the object with a more or less elastic blow the concussion of which is not
transmitted injuriously to the motor shaft, and secondly effects the withdrawal of
the tool for the next blow by an elastic pull which also prevents the transmission
of sudden shocks to the motor shaft.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we
claim is :-
1. An electrically driven percussive drill or other tool wherein the rotary motion
of the motor crank is converted into a reciprocating motion of the percussive tool
by connecting the crank pin of the motor by means of two elastic connecting rods
or equivalent elastic connections with two opposite points of the tool or tool spindle,
so as to effect the forward or operative motion of the tool by means of the one
clastic connection, while the backward motion thereof is effected by the other elastic
connection, substantially as described.
2. In an electrically driven percussive drill, the combination of the guide frame D
with a sliding carriage C carrying the drill and drill spindle, and an electro motor E
the crank & G¹, of whose shaft F is connected by elastic connecting rods or
equivalent appliances I, L M, to two opposite points JJ on the carriage C, so
as to impart the requisite to and fro motion to the carriage and tool by means
of such elastic connections, substantially as described, with reference to the
drawings.
Dated this 9th day of May 1892.
ABEL & IMRAY,
Agents for the Applicants.