Improvements in Machines for Sharpening Rock Drills, Rock- drilling Machine Bits, and the like.
Year: 1899

page_text: Date of Application, 22nd Feb., 1899-Accepted 25th Mar., 1899
COMPLETE SPECIFICATION.
Improvements in Machines for Sharpening Rock Drills, Rock-
drilling Machine Bits, and the like.
I, WALTER EDWARD KIMBER, of 28, Nugget Street, Johannesburg, in the
South African Republic, Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
-
This invention consists of a machine or apparatus primarily designed for
sharpening that class of rock drilling machine bits known as star" bits, but
it may also be adapted for the purpose of sharpening other classes of rock
drills.
It is designed with the object of providing a machine of small dimensions and
of simple and compact construction which shall be capable of efficiently and
rapidly sharpening the bits without cutting away any unnecessary portion of
the drill steel.
It consists essentially of a machine comprising in its construction a rolling
die, or a roll provided with a die or impression of the cutting face, or one of the
cutting faces of the drill, working in conjunction with a holding device or
stationary plate in which the bit is secured whilst the sharpening thereof is
effected by the die as it is caused to roll backwards and forwards over the sur-
face of said plate.
The invention will now be particularly described by aid of the accompanying
drawings, in which it is illustrated embodied in a machine designed for sharpen-
ing "star" bits.
In the said drawings
Fig. 1 shews a side elevation of the machine.
Fig. 2 a front elevation with one half of the stationary plate H removed.
Fig. 3, a plan.
Fig. 4, a front elevation of the plate H detached.
Fig. 5, a side elevation of the plate H and rolling die E both detached.
Fig. 6 shews several views of one of the adjustable holders and centering
devices detached.
The frame of the machine consists of a base or bed plate A and the two
vertical members or sides a a¹ located at one end thereof. B is a driving shaft
mounted in bearings provided in the upper ends of the vertical sides a, a¹, of
the frame. C, C, are fly wheels secured to the crank shaft B at the outside
of each of the vertical sides. D, D¹, are fast and loose pulleys secured to one
extremity of the crank shaft B through which the machine is driven.
The sides a, a', of the frame are formed with vertical recesses in which blocks
or slides b, b, are arranged in such a way as to be capable of working or sliding
freely up and down therein; 2 are liners fitted within these recesses.
E is a roll fitted with a, preferably, detachable die e, corresponding to the
cutting face or one of the cutting faces of the drill, the said die being secured

page_text: to the roll by means of a screw e¹-see Fig. 5. The reduced ends of the roll
project through the slides b, ¹, to the outside of the parts a, a¹, of the frame.
I is a connecting rod from the driving shaft B. The connecting rod Fis
bifurcated or formed with two depending arms f, f', which, at their lower
extremities, loosely embrace the reduced ends of the roll E, between the
sides a, a, of the frame, or the inside of the slides b, b. By this construction
the roll E can rotate independently as it is raised and lowered by the connecting
rod Fon the rotation of the driving shaft B.
.
G, G¹, are plates secured to the outside of the vertical members a, a¹, of the
frame. The plates G G are formed with open centres, and are constructed on
their front inner vertical edges with racks or teeth g. On the reduced ends of the
roll E, which project beyond the sides a, a', into the open centre of the
plates G G¹, are keyed or otherwise secured pinions h, which gear with the teeth
or stationary racks as aforesaid. By this means the roll E is also rotated as
it is raised or lowered, the direction of rotation of the roll being reversed on the
upward and downward movement.
H is the stationary plate in which the drill is held whilst being sharpened by
the rolling die or roll E as it is rotated over its surface, the plate also acting as
a centering device for the drill while under operation. The plate is arranged
immediately in front of the roll and transversely of the frame, and is secured
to the vertical members a, a'. It is formed with a central circular hole i, and
with four radial slots in which the four holding and centering devices -see
more particularly Figs. 4 and 6-are arranged. The holding devices are each
--formed with an enlargement or shoulder on two opposite sides-see Fig. G
and the outer or front face of-the-plate His countersunk to correspond with
the edges of the radial slots, so as to bring the face of the holders-level with
the surface of the plate H at the back. Jis a dise arranged over the front of the
plate H. This disc is constructed with a central hole corresponding to the
hole in the plate H, and with-four-curved eccentrically disposed slots into which
small projections or pins j, formed on the holders project. As_the_disc J is
rotated in one direction the several holders are simultaneously forced inwards,
and are expanded or opened when the disc is rotated in the opposite direction.
K is a lever for operating the dise to which it is attached, to adjust, the holding
devices or to close them on the drill when it is placed in position between them.
L is a cap or cover secured to the plate H for holding the several parts in position.
The holding and centering devices are formed hollow or concave at their
extremities, to correspond to the convexity of the tips or outer edges of the wings
of the sharpened or finished drill. The holders are each constructed with a
projection or stop k, which projects beyond the surface of the plate H at the back
and enters the die e as it rotates over the plate to prevent the metal of the drill
being rolled beyond the desired point or over the surface of the plate H. This
adjustability of the centering and holding device enables drills of varying sizes
to be sharpened by the one machine.
.
L is a bar arranged to slide in guides 1, 2, formed on the base plate A in front
of the machine. The bar is provided with a number of holes 13, in which fits a
stop formed with a cavity or recess for the shank of the drill M to engage whilst
being sharpened. At the front end the bar L is fitted with a nut m, traversed
by a screw m¹, supported by a bracket m² secured to the base plate A. N is another
bracket fixed to the base plate A and formed with a boss' n in which rotates a
spindle fitted with a bevel wheel n² at one end and an operating handle at the
other. The bevel wheel n¹ gears with a bevel wheel n³ fixed to the extremity of
the screw m beyond the bracket m².
In operation, the drill to be sharpened having first been heated is placed with its
cutting extremity projecting through the plate H and bearing against the die e
in the roll E, the stop being placed in position to support the drill endwise. The
handle is rotated to close the holders on the tips or outer edges of the wings
of the drill, and motion is then imparted to the machine. As the roll E is rapidly

page_text: rotated over the surface of the plate H, the cutting face or edges of the drill are
sharpened by being rolled to the desired shape; the screw m¹ being operated by the
handle n² to feed the drill forward during the operation.
66
The only alterations necessary in adapting the machine for the sharpening of
drills or other shapes, such as chisel" bits, or drills of triangular or other section,
will consist of the requisite variations in the formation of the rolling die to cor-
respond to the cutting face or faces of the drill, and in the construction of the
holding device or stationary plate, in conjunction with which the rolling die
works, to correspond to the shape of the cutting extremity.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
1. A machine for sharpening rock drills and rock drilling machine bits con-
structed with a rolling die, or a roll carrying a die or impression of the cutting
face of the drill or bit, working in conjunction with a stationary plate in which
the drill is secured whilst being sharpened, substantially as described.
2. A machine for sharpening rock drills and rock drilling machine bits com-
prising a rolling die or a roll carrying a detachable die or impression of the cutting
face of the drill said rolling die effecting the sharpening of the drill by working
in conjunction with a stationary plate fitted with adjustable holders in which the
drill is held whilst being operated upon substantially as described.
3. In a machine for sharpening rock drills and rock drilling machine bits the
combination of a rolling die or roll carrying a die or impression of the cutting
face of the drill, a stationary plate fitted with adjustable holders for holding and
centering the drill and pinions secured to the ends of the roll for
rotating the roll as it is reciprocated over the surface of the plate,
the pinions gearing stationary racks which reverse the direction of
rotation of the roll on the upward and downward movement, substantially as
described and shewn.
4. In a machine for sharpening rock drills and rock drilling machine bits, in
combination, a roll carrying a die or impression of the cutting face of the drill,
pinions fixed to the extremities of the roll gearing stationary racks for rotating
the roll as it is reciprocated and reversing the direction of rotation of the roll on
its upward and downward motion, a stationary plate arranged in front of said roll
provided with adjustable holding and centering devices for the drill, a bar arranged
to slide in guides longitudinally of the machine frame formed with a number of
holes to receive a stop for the shank of the drill, and a screw working through the
end of the bar operated through gearing to rotate the screw and feed the drill
forward whilst being sharpened, substantially as described and shewn.
5. In a machine for sharpening rock drills and rock drilling machine bits, an
arrangement or device for holding and centering the drill whilst being sharpened
comprising a stationary plate formed with a number of radial slots corresponding
to the wings of the drill in which holders are arranged capable of sliding therein
to and from the centre, a disc constructed with eccentrically disposed slots engaging
projections on the holders to expand or contract the holders on the rotation of the
disc and a cover for holding the parts in position, substantially as described and
shewn.
6. A machine for sharpening rock drills and rock drilling machine bits having
its several parts constructed and arranged in combination substantially as described
and shewn in the accompanying drawings.