IMPROVED APPARATUS FOR CUTTING OVAL HOLES IN METAL PLATES
Year: 1884

page_text: I, JOHN LYALL, of Govan in the county of Lanark, Engineer and Boiler-maker,
do hereby declare the nature of my said Invention for an "IMPROVED APPARATUS
FOR CUTTING OVAL HOLES IN METAL PLATES," to be as follows:-
This Invention relates to improved apparatus for cutting oval holes in metal
plates, such for example as the manhole and mudhole doorways of steam boilers.
The improved apparatus comprises a head or centre block which is bolted or
otherwise secured to the plate in which the oval hole is to be cut.
In the upper
side of this head or block are cut two grooves formed of inverted V or T-shape and
crossing each other centrally at right angles. The grooves may be in the same
plane, but are by preference formed so that the upper surface of the one is in the
plane of the bottom surface of the other, so that the slides with which they are
fitted inay freely cross each other. One slide is fitted within each groove and may
be made in the form of a bolt head corresponding in shape to the section of the
groove, and formed or fitted with a pin or bolt passing out perpendicular to the
groove, through a bush fitted to slide and turn freely on the upper side of the head
the bush being secured to the head by a guide plate and nuts or equivalent
fastenings on the ends of the bolts. This bush is fixed to or formed on an arm
extending out laterally on both sides from the head, and this arm is fitted with a
handle or crank pin by means of which the bush is rotated. By the rotation of the
bush, the slides are traversed back and forth in their grooves, and they constrain
the motion of the bush and arm so that the path traversed by any point in the arm
is that of an ellipso or oval.
If a cutting tool be fixed in the arm perpendicul ir to the plate to which the head
is fixed, it may be made to cut out an oval opening in the plate round the head as
a centre, and the major and minor axes of the oval will depend on the distance
apart of the centres of the slides or bolts. On one enl of the cross arın is formed a
boss which carries a spindle fitted with a radial slotted arm in which a tool holder
is secured. The tool holder is adjustable radially in the slot, so that it may be
moved out from or towards the centre to regnlate the size of hole which is to be cut
Dnll

page_text: by the tool carried in the tool holder. The tool is fed forward in a line per-
pendicular to the plate to be cut by means of a screw which acts on the spindle
carrying the slotted arm and tool holder, and which is turned by a hand wheel or
by a star wheel or similar device acted on at each revolution by a fixed stop. The
tool cuts a groove in the plate, and this groove is deepened as the tool is fed
forward until the plate is cut through.
By providing several sets of bushes bored with the holes to fit over the slide
bolts at different distances apart, the relative lengths of the major and minor axis
of the oval may be varied. The apparatus may be driven by hand or from a
vertical boring machine or a lathe or similar machine arranged to act on the arm
which rotates the bush.

page_text: I, JOHN LYALL, of Govan, in the County of Lanark, Engineer and Boiler Maker,
do hereby declare the nature of my said Invention for "IMPROVED APPARATUS FOR
CUTTING OVAL HOLES IN METAL PLATES; " and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:
My Invention relates to improved apparatus for cutting oval holes in metal
plates, such for example as the manhole and mudhole doorways of steam boilers.
The Invention is illustrated in the accompanying Drawings, in which Figure 1
is an elevation, and Figure 2 is a plan of a modification of my improved apparatus
for cutting oval holes.
The improved apparatus comprises a head or centre block A which is bolted or
otherwise secured to the plate B in which the oval hole is to be cut. In the upper
side of this head or block are cut two grooves c and d formed of inverted V or T
shape, and crossing each other centrally at right angles. The grooves c, d may be
in the same plane, but are by preference formed so that the upper surface of the
one, is in the plane of the bottom surface of the other, so that the slides C and D,
with which they are fitted may freely cross each other. One slide is fitted within
each groove, and may be made in the form of a bolt head C or D, corresponding in
shape to the section of the groove c or d, and formed or fitted with a pin or bolt
cor d' passing out perpendicular to the groove through a bush E fitted to slide
and turn freely on the upper side of the head A, the bush being secured to the head
by nuts e or equivalent fastenings on the ends of the bolts C, D. This bush E is
fixed to or formed on an arm F extending out laterally on both sides from the
head, and this arm is fitted with a handle or crank pin by means of which it is
rotated, or it is operated by a driving arm G on the spindle G¹ of a vertical boring
machine, the plate being secured between the head A and the table B¹ of the
vertical. By the rotation of the bush E, the slides CD are traversed back and
forth in their grooves c, d, and they constrain the motion of the bush and arm, so
that the path traversed by any point in the arm F is that of an ellipse or oval. If
a cutting tool be fixed in the arm F perpendicular to the plate to which the head
is fixed, it may be made to cut out an oval opening in the plate round the head A
as a centre, and the major and minor axes of the oval will depend on the distance
apart of the centres of the slides or bolts C¹, D'. On one end of the cross arm F is
formed a boss H which carries a spindle I fitted with a radial slotted arm J in which a
tool holder K is secured. The tool holder K is adjustable radially in the slot j, so
that it may be moved out from or towards the centre, to regulate the size of hole
which is to be cut by the tool k carried in the tool holder. The tool k is fed
forward in a line perpendicular to the plate B to be cut by means of a screw which
acts on the spindle I carrying the slotted arm J and tool holder K, and which is
turned by a hand wheel, or by a star wheel L or similar device acted on at each
revolution by a fixed stop. The tool k cuts a groove in the plate B, and this
groove is deepened as the tool is fed forward until the plate is cut through.
By providing several sets of interchangeable bushes E bored with the holes to fit
over the slide bolts C¹, D¹ at different distances apart, the relative lengths of the
major and minor axes of the oval may be varied. The apparatus may be driven as
indicated from a vertical boring machine or from a lathe or similar machine
arranged to act on the arm F, which rotates the bush, or it may be operated by

page_text: hand, in which latter case I prefer to secure on the head A a bracket carrying a
train of wheels through which the motion of a hand crank is imparted to the
arın F, the object of the gearing being to increase the power.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
First. The combination of parts constituting the improved apparatus for cutting
oval holes in metal, substantially as herein described and illustrated.
Second. The combination of the tool carrying arm F, bush E, bolts or slides C, D,
and grooved centre block A, substantially as and for the purpose set forth.
Dated this Seventeenth day of January 1885.