New or Improved Method or Process for Sharpening Rock Drills, and Apparatus employed therein.
Year: 1895

page_text: Date of Application, 3rd Dec., 1895-Accepted, 25th Jan., 1896
New or Improved Method or Process for Sharpening Rock Drills,
and Apparatus employed therein.
I, THOMAS HENRY BRADBURY of Johannesburg in the District of Heidelberg,
in the South African Republic, 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 making and sharpening rock drills by hand, as a blacksmith does with a hand
hammer, a large number of blows or strokes have to be given, and the time occupied
is correspondingly extended. The object of my invention is to replace hand labour
by machinery which secures the result required in shorter time, whilst the quality
of the work done is certainly equal if not superior to that produced by hand
labour.
The drills to which my invention more especially refers are those used by miners
for drilling holes in rock or stone, and of the shape known as "chisel bits"; and
I attain my object by using dies of special and appropriate shapes so that the hot
and plastic metal is reduced, squeezed or compressed to the required shape without
necessity for superior and trained skill in workmanship. If, further, the specially
designed dies are driven with sufficient force on to the plastic metal I secure the
exact shaping with very few blows, and thus attain the end by combining accuracy
of shape with economy of time.
The abovementioned dies may be used in any suitable machine adapted to bring
them in contact with the drill rod with a heavy blow; for example the machine
known in the iron worker's trade as an "Oliver" is very suitable for the purpose,
or a steam hammer may be employed where such is available. As the machines in
which the dies may be used are of ordinary well known construction and do not
form part of my invention I have not deemed it necessary to describe them in detail
or to illustrate them by drawings except as to the particular parts of an Oliver
for example to which the dies are immediately connected.
In the drawings
66
"
Figures 1, 2, 3, 4 and 5 show what I call the shaper and gauger dies,
Figure 1 being a pian of the lower or anvil die, Figure 2 a section of both top and
bottom dies taken on line 2-2 of Figure 1, Figure 3 a section of both top and
bottom dies taken on line 3-3 of Figure 1, and Figures 4 and 5 end elevations of
the bottom die, being projections of Figure 1.
Figures 6, 7 and 8 show what I call the cutter dies, Figure 6 being a plan of the
lower or anvil die, Figure 7 a section of both top and bottom dies taken on line 4-4
of Figure 6, and Figure 8 an elevation of the die shown in Figure 6.
Figures 6 and 6 show shaper and cutter dies combined in one pair of
twin blocks.
Figures 9, 10 and 11 show what I call the finishing dies, Figure 9 being a
plan and Figures 10 and 11 sections on lines 5-5 and 6-6 respectively of
Figure 9.
Figure 12 is a side elevation and Figure 13 a front elevation showing two
hammers G G and the anvil D of an "Oliver" with the shaper and gauger
dies F F 1 fixed in relation to one of the hammers G¹ and the cutter dies E E 1
fixed in relation to the other of the hammers G.
Figures 14 and 15 are respectively an elevation and a plan of a stand or bracket
adapted to receive and hold the finishing dies.

page_text: The hammer heads G G 1 of the "Oliver " may conveniently weigh about
thirty-five pounds each and the blow of the upper die fixed in the hammer head is
delivered on the steel drill rod resting in the lower die fixed on the anvil D by
working the treadle levers of the "Oliver" in the usual way.
The shaper, gauger, and cutter dies may be made as one pair of blocks, upper and
lower, or each twin die may be made in separate pairs of blocks, in which last case
each twin may be fitted to a separate hammer head and anvil, but Figures 1 to 5
show a convenient way of cutting the shaper and gauger dies out of two blocks of
steel, one for the anvil dies and the other for the hammer dies, whilst the cutter
dies are made of two other blocks of steel to be worked with an independent
hammer and anvil, which I find more convenient in practice.
The finishing die shown in Figures 9 to 11 is a single die on which the drill is
finished. This die is single, that is to say does not consist of twin parts, and is not
used in an "Oliver," steam hammer or other like machine for giving blows; but the
drill is jumped on to it as will be hereinafter explained.
Figure 1 represents the anvil part of the shaper and gauger dies in plan,
Figure 4 a back elevation and Figure 5 a front elevation or the elevation facing
the operator. The hammer part of the dies is not shown in Figures 1, 4 and 5.
Figure 2 is a section of the shaping die through line 2-2 showing both hammer
and anvil parts. Figure 3 is a section of the gauging die through line 3-3 also
showing both hammer and anvil parts.
It will be noted that the sections, Figures 2 and 3, represent the dies in close
contact as they would be at the end of the blow of the hammer on the anvil.
efgh in Figure 1 is a flat or bearing surface on the anvil die which receives or
seats a corresponding flat on the hammer die, which serves the purpose of preventing
the hammer and anvil dies from crushing one another on the edges or weak parts,
and arrests the blow of the hammer when the top and bottom dies come into
contact. The plane of these flats is represented in the sections Figures 2 and 3 by
the line e 1,1.
Figure 6 is a plan of the anvil part of the cutter die of which Figure 8 is an
elevation. Figure 7 represents a section of the anvil and hammer parts of the
cutter dies in contact, and bearing on the flats l m n o, a being the point which
represents, in section, the cutting edge shown at p q in the plan the curve pq is
identical with the curve or camber which it is desired to give to the edge of the
drill, whilst the short bevils of the cutter correspond and coincide with the short
bevils of the drills.
Instead of the cutting edges of the cutter die being made in one with the
parts E and E1 respectively they may be made separate and removable and be
fitted into recesses in the parts E and El as shown by dotted lines in Figures 6,
7 and 8 being secured in such recesses by dovetailed keys E 2 E 3 or by other
suitable means.
Figure 6 is a plan of the anvil part of a shaper die having a cutter die combined
therewith, and Figure 6B a section on line 5-5 of Figure 6 of same together with
the corresponding hammer die. In this arrangement F are shaper dies somewhat
similar to those shown in Figures 1, 2, 4 and 5 but having fitted at their ends a pair
of cutter dies G which are let into recesses in the blocks of the dies F and are held
in place by dovetail keys H. This arrangement may be used for shaping and
cutting the points of new drills; but it is more especially suitable for mending or
sharpening blunt drills in which case the red-hot blunt point is laid with its front
end on the cutting edge of the cutter G in the auvil die and a single blow with the
hammer die suffices to swage or shape the tapered part of the drill by the shaper
dies F and at same time to cut the short bevils at the point thereof by means of the
cutters G.
Figure 9 represents the finishing die in plan. This is a single die which is not
used in the "Oliver" steam hammer or other like machine for giving blows, but is
set up firmly in a position handy to the operator.
In practice it is convenient to have three of these dies set up at different heights

page_text: from the ground so that the operator may use one or the other according to the
length of the drill which he is finishing.
Figures 14 and 15 show a convenient stand or bracket for setting up the finishing
dies Y at different heights from the ground.
Figures 10 and 11 show sections of the finishing die taken through the lines 5-5
and 6-6 respectively. The hollow of this die is identical in shape with the edge
and short bevil of the drill intended to be made; that is to say the curvilinear
bottom of the hollow indicated by rst in Figure 11 is struck with the same radius
as p q in Figure 6, whilst the V-shaped section of Figure 10 has the same angle as
the short bevils meeting at a in Figure 7. The hollow however is longer than the
breadth of the drill so that the corners of the drills shall not touch the die laterally
when the drill is inserted in this hollow. Figures 10 and 11 showing sections of
the die and elevations of the drill A will indicate this clearly.
The drawings show the shanks or squares B by means of which the dies are set
or keyed in the hammer heads G G 1 and in the anvil D of the blow delivering
machine, or in the stand, bracket, or anvil for the finishing die, as the case may be.
Figures 1 to 8 are drawn to a scale of half full size, Figures 9, 10, and 11 full size,
and Figures 12 to 15 to a much smaller scale.
The dies are made of steel and properly tempered to the same degree of
hardness as is usual for iron cutting or drilling tools, that is pale blue or straw
colour.
It has not been lost sight of that the material to be operated on is a steel bar or
rod, and the object to be attained is to shape the end of this bar or rod into that
of a rock drill whether the rod may have been previously used as a drill or not.
•
The end of the rod A is heated in a smith's fire or any appropriate furnace in
the same way as a blacksmith or workman would do, to the proper degree of heat
adapted for forging steel. The operator then seizing the rod in his hand transfers
the hot end thereof to the anvil die F of the shaper (see Figures 2, 12 and 13) and
bringing the hammer die F1 down flattens that end of the metal into a wedge
with one blow of the hammer, if the latter is sufficiently heavy or falls with
sufficient energy. Figure 2 shows the rod A, in this process the operator being
supposed to be at the left hand, and facing the open side of the two inclined planes
of the shaping die from which side he has introduced the rod A to the die. He
then removes this wedged end of the rod or bar A the anvil part E of the cutting
die (see Figures 6, 12 and 13) and placing the end of the wedge flatwise in the
cutting edge he brings the corresponding die E¹ down on to it, and clips off
the blunt or rough end of the wedge, as shown in Figure 7. The same blow
forms the short bevils of the drill as well as its curved cutting edge.
This operation of forming the short bevils of the drill by means of cutters is an
important feature of my invention as by its means the point of the drill is
made as dense and as hard by the one cutting operation as it has heretofore been
made by numerous blows of a hammer administered to it in the ordinary process of
sharpening by hand.
The two operations above described have however tended towards spreading the
hot metal so that the gauge of the drill will be wider than the diameter of the rod,
and the drill will also be found, at this stage, to have been left with a burr on its
edge. The operator therefore, as soon as the hammer cutter die E1 rises, removes
the drill to the gauging die Figure 3 and placing the drill A with its edge vertical
in the groove of the anvil part of that die he brings the hammer part of the die
on to it as shown in that figure. It will be noticed here that when the upper and
lower dies of the gauger are in contact, as shown in Figure 3, the diameter of the
opening in the dies facing or towards the hand of the operator is equal, or nearly
so, to that of the drill but the grooves I of the dies deepen in section towards the
other face of the dies whilst their sides remain parallel in plan. The consequence
is that the operator can gauge his drill to any sizes between the depth of the
grooves next to his hand, and the depth of the grooves at the opposite end by
•

page_text: simply holding the drill at any intermediate position between the ends of the
grooves.
Having shaped, cut, and gauged the drill the operator removes the burr from the
edge and finishes the drill by standing it, cutting edge downwards, in the finishing
die as shown in Figure 11, and with a hand hammer deals one or more blows on the
top end of the drill.
The short bevil of the drill fits closely in the hollow of the finishing die
whilst the cutting edge lies in the angle at the bottom of the hollow as at y in
Figure 10. The effect of the blow on the end of the drill is to force the burr back
into the hot metal whilst the edge and short hevils are smoothed, made more
compact and finished.
The drill is now complete and being allowed to cool to the proper tempering
colour is plunged into water or other cooling liquid in the usual manner, and when
cold is ready for use.
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 :-
First. The improved method of making or re-sharpening rock drills which
consists in subjecting them to the action of shaping, cutting, gauging, and
finishing dies of the shapes and kinds described, substantially in the manner
set forth.
"
Second. The shaping dies which consist of top and bottom dies having inclined
surfaces for imparting the "chisel bit or wedge shape to the end of the drill,
substantially as described.
Third. The gauging dies which consist of top and bottom dies having tapering
grooves for the purpose of imparting the desired width to the chisel edge of the
drill, substantially as described.
Fourth. The cutting dies which consist of top and bottom dies having cutting
edges for imparting the proper curvature and short bevils to the chisel edge of the
drill, substantially as described.
Fifth. The finishing die which consists of a block of steel provided with a
hollow the cross section of which corresponds to the V-shape of the short bevils
of the drill, and the longitudinal section of which corresponds at the bottom,
with the camber or curved shape widthwise of the drill, substantially as
. described.
Dated this 2nd day of December 1905.
T. H. BRADBURY,
Per W. H. Beck,
115 Cannon Street, London, E.C., Agent.