Improvements in Drawing Metal Tubes.
Year: 1890

page_text: Date of Application, 4th Jan., 1890
Complete Specification Left, 4th Nov., 1890-Accepted, 4th Feb., 1891
[Communicated from abroad by HERMANN MOERCHEN, of Alten, in the
German Empire.]
Improvements in Drawing Metal Tubes.
I, HAROLD IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Fellow of the Institute of Patent Agents, do hereby declare
the nature of this invention to be as follows
--
This invention relates to the drawing of metal tubes in such a manner as either to
reduce the thickness of the shell uniformly over the length of the tube or to produce
a shell of various thickness in various parts of its length.
For this purpose the ends of a tube are closed either, by hammering or pressing
down the metal, or by malleable plugs fixed in the ends, and, before quite closing
both ends, the tube is filled with pulverulent material of a mobile character, such as
sand, lime, powdered plumbago or mixtures of these; or it is preferably filled with
some such substance as will become fluid at the heat to which the tube is subjected.
For this purpose the more fusible metals such as lead, or certain slags or salts can
be employed. The filled tube, heated if necessary to the proper temperature is
subjected to the action of grooved rollers or of tribletts which extends it in length
reducing its diameter, and reducing also the thickness of the shell almost uniformly
throughout. When it is desired to produce a tube with parts of its shell thicker
than other parts, the diameter of the tube is first reduced at the parts which are to
be thick, the tube being filled as above described and closed at its ends, is subjected
to rolling or drawing thus producing a tube having its shell thicker at the parts
which were first reduced in diameter than in the parts which were not so reduced.
By employing suitable rollers the tube may be drawn taper externally with a
nearly uniform bore or with a varied bore throughout its length.
Dated this 4th day of January 1890.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Drawing Metal Tubes.
I, HAROLD IMRAY of No. 28 Southampton Buildings, Chancery Lane in the
County of London, Fellow of the Institute of Patent Agents, 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 the drawing of tubes for the purpose either of uniformly
reducing the thickness thereof along the whole length, or of obtaining varying
thicknesses at different parts of the length of the tube.
For these purposes the interior of the tube is closed either by hammering down,
pressing or rolling the ends thereof or by securing therein malleable plugs, after
baving filled the tube with pulverulent material of a mobile nature, such as sand,
lime, graphite or mixtures thereof.
Instead of these it is in many cases preferable to use for the filling pulverulent
substances which cohere or become plastic under the rolling heat. For this purpose
pulverulent granite, slag or salts having a corresponding melting point may
be used.
The tube so fitted, after being heated to the temperature suitable for rolling, is

page_text: passed through grooved rolls or presses so as to be extended longitudinally, while
the diameter and thickness are also reduced.
If it be desired to produce tubes with greater thickness at certain points, the
tube, before being filled, has its diameter reduced at the said points.
The tube having then been filled as above described, and closed at the ends is
then rolled down or hammered, thus producing a tube the thickness of which is
greater at the points where its diameter was previously reduced, than at the
other parts.
In using suitably formed rolls, the tubes can be made taper externally, or be
formed with grooved or recessed portions &c., the bore being either approximately
cylindrical or tapering.
In Fig. 1 of the accompanying drawings the dotted lines shew a tube of uniform
thickness before the reduction by pressing or forging of certain parts to the form
shewn by the full lines.
Fig. 2 is a section of the tube after it has been rolled down.
Figs. 3 and 4 illustrate the formation of a tube with cylindrical outer surface and
tapering bore.
Figs. 5 and 6 illustrate the manufacture of a tube tapered both internally and
externally.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The herein described process for drawing tubes of reduced thickness by filling
the tube with pulverulent mobile or plastic material, closing the ends of the tube
and then rolling it down to the desired diameter.
2. The herein described process for drawing tubes of varying thickness by first
reducing the external diameter at the parts where the thickness is to be increased,
then filling the tube with pulverulent mobile or plastic material, closing the ends of
the tube and then rolling it down to the desired diameter.
Dated this 4th day of November 1890.
ABEL & IMRAY,
Agents for the Applicant.