Improvements in Devices for use in Drawing Metal Pipes.
Year: 1893

page_text: Date of Application, 29th Aug., 1893-Accepted, 14th Oct., 1893
COMPLETE SPECIFICATION.
Improvements in Devices for use in Drawing Metal Pipes.
I, CARL GUSTAF LARSON, of Sandviken, in the Kingdom of Sweden, 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 :-
When drawing pipes it is customary, as is well known, to use plyers or grippers
by means of which the pipe is drawn through the drawplate and over the mandrel
introduced into the pipe. In order that this plyer may seize the pipe with certainty
it is however necessary either to hammer the end of the pipe together to a solid
piece or to prevent the pipe, in some other way, from being compressed, the said
plyers being provided with sharp edges in order to firmly grip the pipe.
The hammering together of the end of the pipe and the marks of the plyers
make it necessary to cut off the end of the same which occasions a considerable
amount of waste.
This invention relates therefore to a device which, without damaging the pipe at all
or making it necessary to hammer together the end thereof, securely seizes the same
and enables it to be drawn through the drawplate. This device consists of a
mandrel, an outer clamping socket, and jaws in the shape of two bushes cut into
halves longitudinally, which are arranged one on the inside of the pipe around the
core which is introduced in the latter, and the other on the outside of the pipe in the
clamping socket, which is passed over the same. The said parts are however not
cylindrical but are made conical so that when drawn by the chains they will wedge
themselves fast to the pipe between the socket and the core.
In the accompanying drawing
Figure is a longitudinal section of the device.
Figure 2 is an end-view of the same partly in section.
Figure 3 is a side elevation of the drawing chains and socket.
Figures 4 and 5 show a modified form of the socket for drawing pipes provided
with inner flanges or projections and
Figure 6 shows a modified arrangement of the drawing chains.
Figure 1 represents a section of a pipe A, the end of which has been slit or cut
out at four places as at a, and reduced in diameter in order that it may be passed
through the draw-plate B. C designates the mandrel, D the clamping socket and
E the core.
The said socket is wider at the outer end and adapted to fit the bush F
cut in two and tightly surrounding the pipe. Into the said pipe is introduced the
core E which is wider at the inner end, and around this is fitted the bush H, also
cut in two which fits tightly to the inner side of the pipe.
Owing to the conical shape of the socket and the core, and to the manner in
which the said parts are arranged, it will be understood that when the socket is
drawn outward, the bush F will be pressed in against the outer wall of the pipe
and when the core E is drawn outward the bush H will be forced out against the
inner wall of the pipe. When the socket and the core are drawn outward simul-
taneously a pressure will be exerted against the inner wall of the pipe as well as
against the outer wall thereof and all parts will therefore be locked fast one against
the other with the pipe between them, with a force which increases in proportion
as the pull on the chains is increased.
For the purpose of simultaneously drawing upon the socket and the core, the
said socket is connected by chains II to the eye L of the cross-piece K, and the
said core by means of another chain M to the eye N of the said cross-piece.
The cross-piece is provided with a pivotted drawing-link N', so that the device can
be maintained in equilibrium. If desired only one chain can be used the ends of

page_text: which may be connected to the socket, the said chain passing around a pulley block
fixed to the core and around two other pulley blocks fixed to the cross-piece, as
shown in Figure 6. The bushes F and H may be conveniently provided with
transverse grooves on the sides turned towards the pipe, and their halves with
handles b.
The modification shown in Figure 5 consists only in that the bush H, owing to
the longitudinal projections on the inner side of the pipe, is provided with
corresponding recesses.
Although some small part of the pipe is spoiled by cutting or slitting up the end,
which is necessary in order that the different parts may come freely against each
other, this part is however so short that its loss by cutting off, is of little importance.
If the pipe has very thin walls, the same need not to be cut or slit up.
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 gripping device for use in drawing pipes, consisting of a conical socket
passed over the end of the pipe and having the wider end thereof outward, and a
conical core introduced into the said pipe but having its largest end towards the
pipe and divided bushes adapted to fit between the core and the pipe and also
between the pipe and the socket, with the object, that when drawing simultaneously
upon the socket and the core the said bushes may wedge themselves fast against
the cut or slit end of the pipe, and thus securely hold the latter while being drawn
through the draw-plate.
2. In the device described in the first claim, the arrangement of chains fixed to
the socket and to the core and connected with a cross-piece by means of eyes or
hooks, the said cross-piece being provided with a pivotted draw-link.
3. The modification in the arrangement described in the second claim which
consists in the employment of a single chain fixed to the socket, the said chain
passing around a pulley-block fixed to the core and around two other pulley-blocks
fixed to the cross piece.
Dated this 20th day of Aust 1902
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.