An Improved Process for Producing Tubes of Varying Internal Diameters, and Tools for same.
Year: 1897

page_text: Date of Application, 30th Nov., 1897
Complete Specification Left, 19th Aug., 1898-Accepted, 5th Nov., 1898
An Improved Process for Producing Tubes of Varying Internal
Diameters, and Tools for same.
I, SAMUEL EARNSHAW HOWELL, Sheffield Tube Works, Wincobank, City of
Sheffield, Manufacturer, do hereby declare the nature of my invention to be as
follows:-
My invention relates to improvements in the method or process of drawing
tubes by which I am enabled to produce metallic tubes with both ends of thicker
material than the centre or intermediate portion, such increase being internal,
also if required any other part of the interior can be increased in thickness while
retaining an equal diameter outside.
The object of the invention which refers more particularly to tubes for cycle
frames is to strengthen certain parts which are subject to strains, or through
which screws and such things have to pass.
In carrying out my invention in the production of steel tubes having both ends
thicker than the intermediate or centre portion, such increase of thickness to be
internal, I proceed as follows:
I prepare a mandrel having its central portion of the desired diameter to produce
the central portion of the tube, and set down at both ends to a diameter corre-
sponding with the desired additional thickness required.
The length of this reduced part at the front end of the mandrel corresponds with
the desired extent of the thickened part of the tube, and the extreme end is further
set down to enable it to be gripped by the drawbench tongs; the back end of the
reduced portion of mandrel is preferably longer than that at the front end.
The length of tube to be operated upon is of such a diameter internally that
the mandrel can be readily inserted and the thickness of metal is sufficient to
produce the extra strong ends.
One end of the tube is set down or closed upon the extreme end of the mandrel
passing freely through the die in the drawbench where it is seized by the tongs.
The die is of such a diameter that as the tube (and the mandrel within it) are
drawn forward the tube is simply closed upon the reduced part of the mandrel
before described, retaining its full thickness but when the full size portion of the
mandrel enters the die the metal of the tube upon that part is reduced in thick-
ness being drawn down to the size required.
When the reduced part of the back end of the mandrel is reached the tube is
closed upon it without being reduced in thickness or below the diameter of the
central part.
I have now to release and withdraw the mandrel from one closed end of the tube;
to accomplish this I subject it to the action of a reeling machine which stretches
and thus slightly enlarges the tube, I now apply force and draw out the mandrel
through the back end of the tube, which necessarily expands the thickened part,
I then pass the tube without the mandrel through a pair of finishing dies which
reduces it to size and leaves it perfectly true.

page_text: By this process and a specially prepared mandrel a thickened portion may
be made in the centre or other part of the tube internally, and the mandrel
released therefrom as herein before described.
Dated the 27th day of November 1897
ROBT. F. DRURY,
Agent for Applicant, Bank Buildings, George Street, Sheffield.
An Improved Process for Producing Tubes of Varying Internal
Diameters, and Tools for same.
I, SAMUEL EARNSILAW HOWELL, Sheffield Tube Works, Wincobank, City of
Sheffield, Manufacturer, do hereby declare the nature of this invention and in what
manner the same has to be performed, to be particularly described and ascertained
in and by the following statement:―
My invention relates to improvements in the method or process of drawing
metallic tubes which vary in the internal diameter, such for example as tubes
having both ends of greater thickness than the central portion, such increased
thickness being internal; or with a thick part in the centre and thick ends, and
other variations of the internal diameter.
The object of the invention which refers more particularly to the production
of tubes for the frames of cycles. is to strengthen certain parts which are subject
to strains, or upon which a serew thread may have to be cut, or the like.
The method of carrying out the invention is illustrated in the annexed sheet
of drawings to which I shall refer, and in which
Fig. 1, represents the thick ends of a tube with portions of the reduced central
part.
Fig. 2, represents the mandrel and die, with a tube ready to be drawn through
the die.
Fig. 3, an enlarged view showing how the process of reducing the central part
is carried out.
In the production of steel tubes for example having both ends thicker than the
central or intermediate portion, and such extra metal being internal as shown
in Fig. 1, I proceed as follows:
I prepare a mandrel M, having its central portion of the desired diameter to
produce the central portion of the tube, and set down or reduced at both ends m,
to a diameter which corresponds with the desired additional thickness of metal.
The length of the reduced part m, on the front end of the mandrel M, corresponds
with the desired extent of the thickened part of the tube, and the extreme end m²
is further reduced to enable it to be gripped by the drawbench tongs; the back
end of the reduced part of mandrel is preferably longer than that at the front end.
The tube T. to be operated upon, is of such a diameter internally that the
mandrel can be readily inserted, and the thickness of the metal is sufficient to
produce the required ends.
One end t, of the tube T. is closed upon the extreme end m³, of the mandrel,
so as to pass freely through the die D, which is held in the headstock H, of the
drawbench, and is seized and gripped by the drawtongs in the usual manner.
The opening through the die is of such a size that as the tube T, and the mandrel
within it are drawn forward, the tube is simply closed upon the part m, without
any alteration in its thickness, but when in continuation of the forward movement,
the full size portion of the mandrel enters the die, the metal of the tube is caused

page_text: to flow back, leaving the desired thickness upon the mandrel as indicated by the
dotted lines L, in Fig. 3, the remainder of the tube is closed upon the reduced
back end of the mandrel without diminishing its thickness, by the action of the die
as before described.
It is now necessary to release the enclosed mandrel and to withdraw it from one
end of the tube, preferably the back end, and to accomplish this I subject the tube
to the action of a reeling machine, and this method of rolling which is well known
to engineers, results in a slight enlargement of the tube's diameter.
I now apply force and draw out the mandrel thereby again slightly expanding
the thicker end of tube, the tube without the mandrel is now passed through a
pair of finishing dies which operation reduces it to the required outer diameter
and leaves it perfectly true.
If a thickened portion is required say in the centre or thereabouts of the tube,
the mandrel is reduced at the corresponding part and the metal of the tube in
place of being drawn thinner by the die will be pressed down into such reduced
part in its full thickness, being afterwards released by the reeling operation before
described.
Having thus 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:-
1. Producing drawn metallic tubes with walls of varying thicknesses, as shown
in Fig. 1, for example, by drawing the tube upon a suitably shaped mandrel:
releasing the enclosed mandrel by the process of reeling" the tube and causing
it to expand, withdrawing the mandrel and passing the tube through one or more
dies to reduce it to the required size, as hereinbefore described and set forth.
2. In the production of metallic tubes with walls of various thicknesses, the
use of a correspondingly shaped mandrel upon which the tube is drawn and locked,
until released by the expanding process of reeling as herein before described.
3. As a new method in the manufacture of metallic tubes with varying internal
diameters, the combination of the several processes herein before described and
set forth.
The 1 154h
1908
ROBT. F. DRURY, C.P.A.,
Agent for Applicant,
Bank Buildings, George Street, Sheffield.