Metal Plates.
Year: 1888

page_text: Date of Application, 29th June, 1888
Specification Accepted, 3rd Aug., 1888
Metal Plates.
I, PETER MITCHELL, of Greatham Terraco, West Hartlepool, in the County of
Durham, Assistant Manager of shipyard and graving docks, 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 :-
My invention relates to improved means for facilitating the formation of man-holos
and other openings in boiler, tank, and other metal plates.
Hitherto such holes have usually been formed either at a single operation by the uso
of a heavy hydraulic or other press, or by punching or drilling a series of small holes
around the margin of the proposed opening. In the former case, however, tho
machinery is very expensive and is practically useless for performing any other operation
than that for which it is specially constructed; and in the latter case a considerablo
time is spent in cutting away the material between the adjacent holos and in trimming
the edges of the plate around the opening.
The object of my present invention is to provide apparatus which is comparativoly
inexpensive, and applicable to any ordinary punching machine, and by means of which
an opening is cut which requires very little if any trimming or finishing, and to these
ends it comprises the improvements hereinafter described.
In the accompanying drawing
Figure 1 is an elevation of my improved apparatus, and
Figure 2 is a vertical section of the same on the line .r, x.
Figures 3, 4, 5, and 6, are views of details.
a is the knife or blade by means of which the opening is formed, and b is a block
which supports the metal plate during the shearing operation.
The knife a is curved in a horizontal plane, for instance, as shown in figure 6 (which
is a plan of the knife detached) and is adapted to pass through a slot or aperture c in
the block b, the said slot at its upper edge being of the same width as the knife, so that
both edges of the latter are enabled to act with a shearing action on the metal. The
slot extends through the block b as indicated in figures 1 and 2 and tapers down-
wardly and outwardly, as shown in figures 2 and 4, so as to afford clearance for and
allow the escape of the piece of metal cut out by the knifo.

page_text: d is a socket in which the knife is carried, the said knife having a head or shank,
preforally shaped as shown in figure 5, with two shoulders e, /. The socket is open
at one end, as shown in figure 3, which is an underside view of the same, and is
constructed with a shoulder and a pin h, so that when the knife is inserted into the
socket with the shoulder e lying upon the shoulder g, the pin will engage beneath
the shoulder and so hold the knife in position. The said socket is also mounted to
rotate in a boaring i formed on a plate which is adapted to be secured to the under-
side of the sliding head of a punching machine by bolis passed through the holes jj.
The socket is retained in the bearing by means of a key which is passed through a
circular head on the said socket and through a pin m projecting through the platej,
ns shown in figures 1 and 2, the said key being insorted through a hole n formed in
the bearing i.
a, o are a series of arms which are formed on the socket d to enable the latter to
be readily turnel by means of a pipe or tubular lover, to cause the curve of the blade
to correspond as nearly as possible with the curve of the hole to be formed, thereby
rondering the manipulation of the metal plate much easier than if the knife were fixed
and the plate lind to be moved to correspond thereto.
In order to cause the block 6 to turn so that in all positions of the knife the slot o
will correspond therewith, ono ond p of the said knife enters the said slot as indicated
in figure 1, the said block being mounted in a bearing on a plate and secured
therein in the same manner as the socket d.
The operation of my improved apparatus is as follows, that is to say, a holo
sufficiently large to allow the introduction of the point is made in the metal plato
within the margin of the hole, the plate is then placed so that the hole therein is over
the end of the part of the slot e occupied by the end of the knife. The said knifa
is then fixed in the socket d in the manner hereinhefore described and the machine is
started, the knife with the block d being gradually moved as hereinbefore described
to cause the blade to correspond as nearly as possible with the outline of the hole.
The material removed by the knife is in the form of a continuous strip.
Having now particularly described and ascertained the nature of my said invon-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. Apparatus for forming openings in metal plates, comprising a knife or punch
and a block or die which are adapted to be rotated to cause the knife or blade to
correspond with the margin of the hole to be cut, tho said knife or blade having a
projecting portion extending into a hole or slot in the block, so that the latter shall
move with the knife or blade for the purpose specified.
2. In apparatus for forming holes in metal plates, the employment of a socket for
carrying the knives, provided with a series of arms, substantially as, and for the
purpose, specified.
3. The improved apparatus constructed and arranged substantially as hereinbofore
described and illustrated in the accompanying drawing.