Improvements in Tools for Cutting Holes in Metal Plates.
Year: 1893

page_text: Date of Application, 2nd Dec., 1893
Complete Specification Left, 3rd Sept., 1894-Accepted, 13th Oct., 1894
Improvements in Tools for Cutting Holes in Metal Plates.
I, GEORGE FLETCHER, of Masson and Atlas Works, Litchurch, Derby, in the
County of Derby, Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention relates to improvements in tools for cutting holes in meta!
plates.
Tools of this class now generally used require a hole to be drilled in the plate to
guide the spindle of the cutting tool, but tools have been designed with the object
of rendering the drilling of such a hole unnecessary, the cutters in these cases
having been pressed against the plate by means of metallic springs, or cushions
formed by water or the like. In practice however such tools give unsatisfactory
results, partly by reason of the vibration set up causing the point of the spindle to
spring out of its centre.
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According to my invention the rotary cutter is arranged around a driving spindle
having its lower end formed with a cone or centre which, during the cutting
operation, is supported in a pop or depression in the plate to be drilled. The
cylinder carrying the cutters is rotatably connected to a hand wheel supported
upon the spindle by means of screw threads so that the cutter cylinder may be
moved relatively with the spindle to effect the feed, by moving the hand wheel
relatively with the driving spindle.
In practice I find it advantageous to automatically impart a continuous feed to
the cutters by means of spur gearing so arranged that when the driving spindle
is rotated the hand wheel supporting the cutter cylinder will move at a slightly
different speed, this difference in the speed serving to effect the desired longitudinal
movement of the latter relatively with the spindle.
A suitable arrangement of gearing is as follows,-A gear wheel having thirty-
four teeth is connected to the driving spindle by a spline or feather and on the boss
of the hand wheel is fixed a gear wheel having forty seven teeth. These two
wheels gear with a double gear wheel, the two parts of which have thirty four
and forty six teeth respectively.
If now the spindle be driven at 276 revolutions the hand wheel will only make
270 revolutions, this difference of six revolutions between the spindle and hand
wheel giving the desired feed.
It is to be understood that the relative proportions of the gear wheels above
mentioned may be varied as desired.
Dated the 2nd day of December 1803
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Tools for Cutting Holes in Metal Plates.
I, GEORGE FLETCHER, of Masson and Atlas Works, Litchurch, Derby, in the
County of Derby, Engineer, 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 to improvements in tools for cutting holes in metal
plates

page_text: Tools of this class now generally used require a hole to be drilled in the plates
to guide the spindle of the cutting tool, but tools have been designed with the
object of rendering the drilling of such a hole unnecessary, the cutters in these
cases having been pressed against the plate by means of metallic springs, or cushions
formed by water or the like. In practice, however, such tools give unsatisfactory
results, partly by reason of the vibration set up causing the point of the spindle to
spring out of its centre.
<<
According to my invention the rotary cutters are arranged around a driving
spindle having its lower end formed with a cone or centre which, during the cutting
operations, is supported in a
"
pop or depression in the plate to be drilled. The
cylinder carrying the cutters is rotatably connected to a hand-wheel supported upon
the spindle by means of a screw-thread so that the cutter cylinder may be moved
relatively with the spindle to effect the feed by moving the hand-wheel relatively
with the driving spindle.
In practice I find it advantageous to automatically impart a continuous feed to
the cutters by means of spur-gearing so arranged that when the driving spindle is
rotated the hand wheel supporting the cutter cylinder will move at a slightly
different speed, this difference in the speed serving to effect the desired longitudinal
movement of the latter relatively with the spindle.
To enable my invention to be fully understood I will describe how it can be
carried into practice by reference to the accompanying drawings, in which :-
Figure 1 is an elevation of a tool constructed according to my invention for
cutting holes in metal plates:
Figure 2 is a plan of the same; and,
Figure 3 is a vertical section with the driving spindle and the cutters turned a
third of a revolution.
Similar letters in all the figures indicate similar parts.
a is the driving spindle, and b is the cone or centre which I form at its lower end,
which cone or centre during the cutting operation is supported in a "pop" or
depression in the plate to be drilled, the said spindle being adapted to be connected
in the usual manner to the socket on a drill spindle (not shewn).
c, c, c are the cutters, and d is the cylinder carrying the same in grooves, the
cutters being set up or kept to their work by means of screws e, e working in
female screw-threads fin a ring or ferrule g clamped by means of a set-screw h to
a collar i fixed on the cylinder d, the lower ends of the cutters being held firmly in
the grooves in the cylinder by means of set-screws j in a ring or ferrule k.
The spindle a is connected to the cylinder d by a key fixed in the former and
projecting into guide slots m in the latter, so that the cylinder is compelled to
partake of the rotary motion of the spindle but can move vertically in the
same.
n is the hand wheel to which the cylinder d is rotatably connected by means of
a split collar o placed in a groove p in the cylinder and secured to the hand wheel
by screws q
is the left-hand screw-thread on the spindle a on which the hand-wheel n
is supported so that the cutter cylinder & may be moved longitudinally
relatively with the spindle a to effect the feed by moving the hand-wheel
relatively with the spindle.
I will now describe the spur gearing which in practice I find it advantageous to
employ for automatically imparting a continuous feed to the cutters c.
s is a gear-wheel having thirty four teeth and connected to the driving spindle a
by a key working in a keyway in the said spindle; u is a gear-wheel having forty-
seven teeth and fixed on the boss v of the hand-wheel n. These two wheels s and u
gear with a double gear wheel the two parts w and a of which have thirty-four
and forty-six teeth respectively so that when the spindle a is rotated the hand-
wheel n supporting the cutting cylinder d will move at a slightly different speed,
for example, if the spindle a be driven at 276 revolutions in the direction indicated
by the arrow, Figure 3, the hand-wheel n will only make 270 revolutions,. this

page_text: difference of six revolutions between the spindle and hand-wheel serving to effect
the desired longitudinal movement of the latter relatively with the spindle and
consequently giving the desired feed.
It is to be understood that the relative proportions of the gear wheels 8, 1, 10, C
may be varied as desired.
The double gear-wheel wa rotates upon a spindle y between two plates 2,
bolted together as shewn, the said spindle being formed with eccentric ends a¹,
having their bearings in the plates, ¹, the end a receiving a securing nut c' and
the other end & being bifurcated to receive a handle d' whereby the spindle y can
be partially rotated on its eccentric ends a', 6' and the double wheel w, be thereby
moved out of gear with the other two wheels s, u.
This disengaging arrangement is provided for allowing the cutters to be rapidly
lowered to their work or raised therefrom. In the former case it is only necessary
(the spindle a being in motion) to disengage the gear-wheels by moving the
handle d from the position shewn in full lines to that indicated by the dot-and-dash
lines in Figure 2 and then arrest the motion of the hand-wheel when the latter
will work down the screw-thread and quickly bring the cutters into contact with
the plate to be cut. The gear-wheels being then engaged by moving the handle d¹
back to the position shewn in full lines, the cutters c will be gradually and con-
tinuously fed to the work as the cutting of the hole progresses through the medium
of the arrangement of differential gear s, u, w, x, screw and wheel n, for instance,
the proportions of the gear-wheels being those described, if there be six threads
per inch on the said screw and wheel, there will be a feed of one inch for every
276 revolutions of the cutters.
When requiring to raise the cutters from the work it is only necessary to stop
the rotation of the spindle a, disengage the differential gear-wheels and turn the
hand-wheel n by hand in the opposite direction to that of the arrow in Figure 3.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
-:
1. A tool for cutting holes in metal plates comprising a rotary driving spindle
having its lower end formed with a cone or centre which is supported during the
cutting operation in a pop" or depression in the plate to be drilled, a cylinder
carrying the cutters and capable of moving longitudinally on the said spindle and
of rotating therewith, a hand-wheel rotatably connected to the cutter-cylinder and
supported upon the spindle by means of a screw-thread and an arrangement of spur-
gearing for automatically imparting a continuous feed to the cutters, substantially
as hereinbefore described.
2. In combination with a tool of the kind claimed in the first claiming clause for
cutting holes in metal plates, the arrangement of mechanism for throwing the
spur-gearing out of engagement when required substantially as hereinbefore
described.
3. The improved tool for cutting holes in metal plates hereinbefore described
and illustrated in the accompanying drawings.
Dated this 3rd day of September 1894
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.