Year: 1888

page_text: I, LEVI LYMAN BURDON, of Broad Street, Providence, Rhode Island, in the
United States of America, Mechanic, do hereby declare the nature of my said inven-
tion, and in what manner the same is to be performed, to be particularly described.
and ascertained in and by the following statement:
My present invention relates to a new and improved process employed in straight-
ening metallic tubes.
In the manufacture of seamless tubes, especially when drawn down to such an
extent that the sides thereof are comparatively thin, it is found that the tendency of
the metal intermediate of the end portions, is to spring inwardly thereby producing
tubes which are somewhat smaller in diameter, or concave, along the centre portions
than at their ends. Tubes thus drawn are, moreover, slightly larger at one end than
at the other, owing to the fact that the plungers which shape them are made
tapering. This is done in order that they may be readily withdrawn from the shells
or tubes.
For certain purposes, as for example in the manufacture of seamless shells for
compound ingots, it is very essential that the tube be quite thin and at the same time
substantially uniform in diameter or cylindrical throughout.
The object of my improvement is to straighten such concave tubes and at the same
time make them uniform in diameter. To accomplish this result I make a standard
arbor or core of proper longth from suitable metal, as,steel, which is perfectly true and
cylindrical; its diameter being substantially the same as that of the large end of the
tube to be operated upon. The arbor has a flexible connection attached to one end
thereof by which it is suspended. I next place the large end of the seamless tube
over the upper end of the vertical arbor, and subject the whole to the action of heat.
[Price 8d.]

page_text: Such heat may be generated in a suitably arranged furnace, or the heat from a series
of burning gas jets may be directed against the arbor and tube, the result being
that the tube expands and by its gravity passes over the arbor and drops therefrom
at its lower end. Upon cooling the tube will be found to be true and uniform in
diameter throughout.
In the accompanying drawings illustrating my improvements,-Figure 1. represents
a longitudinal central sectional view of the seamless tube having one end larger than
the other, corresponding to the size of the plunger or former, and by broken lines
representing the tendency the metal has to assume a concave form. Fig. 2. is a side
view of the plunger. Fig. 3. represents a suspended arbor having the tube (which is
to be straightened) resting thereon, preparatory to being heated, and Fig. 4. is the
same after the heat has been applied; showing the tube straightened by its passage
along the arbor, and being in the act of dropping therefrom.
The following is a more detailed description of my improvement, including the
manner of its operation ;-
B, indicates the last of a series of plungers or formers which give the final shape
to the seamless tube. Said plunger being adapted to be mounted in a suitable press
as common. Such plungers aro generally made slightly tapering or conical, that is
having ono ond a little larger in diameter than the other, so that the work may be
removed therefrom with greater facility. In the drawings the degree or proportion
of the taper is considerably oxaggerated.
a, Fig. 1. designates a seamless tube or shell of metal as made or finished by said
arbor, and open at both ends. a, being the large end, and a², the small end of the
tube. The sides of the tube very frequently spring inwardly, as shown at, c, by the
curved broken lines. To such an extent are the sides bent that it is impossible to
force an arbor longitudinally through the tube without rupturing it.
The tube, a, in this instance we will assume to be made from fine metal, as gold,
and being quite thin and seamless; the curvature of its sides being due to the drawing
process which makes the metal hard. and elastic, and having somewhat of the qualities
of a spring. This characteristic of metals, developed during the drawing or hammering
process, is well known to workers in metal.
C, indicates an arbor of suitable length, and turned off.true and uniform in diameter
throughout. The arbor may be solid and made of steel. The upper end is adapted
to be attached to a chain or flexible connection, e, as clearly shown in Fig. 3.
The operation is as follows:-The tube, a, is first mounted upon the upper end of
the suspended arbor, C, as shown in Fig. 3. and the whole then suitably disposed
within a furnace and subjected to heat which gradually expands the tube. The latter
now slides downwardly along the arbor and finally drops therefrom, thereby straight-
ening the tube and making its interior diameter uniform with the outer diameter of
the arbor, as shown at, A, Fig. 4.
During the foregoing operation the action of the heat is of course to heat both the
arbor and the tube; but the latter, owing to the nature of the material and thinness
of the shell, is more readily acted upon, thereby at the same time in a degroe
annealing 'it, consequently the tube becomes self-straightening in its passage over
the arbor as stated. The tube upon cooling will be found to be practically true;
the heat having removed the "temper" from the metal which had been present by
reason of the "drawing" process in making the tube.
It is obvious that by heating the tube to a proper temperature and holding it
stationary, the arbor itself may be readily drawn endwise through the tube, with
substantially the same effect upon the tubo as though it had been passed over the
arbor.
By means of my improvements the process of straightening metallic tubes is greatly
facilitated, the tubes thus straightened, if made of gold or other fine metal, being
especially adapted to be used in the manufacture of compound ingots, which latter
form the subject of two applications for Patents filed by me upon oven date
herewith.

page_text: 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.:-
1. The method of straightening tubes, which consists, essentially, in passing a
cylindrical arbor longitudinally through and in continuous contact with a heated
tube of substantially the same diameter as the arbor, thereby giving to the tube a
uniform interior diameter corresponding to the diameter of the arbor, substantially as
herein before set forth.
2. The hereinbefore described improved mode of straightening metallic tubes,
the same consisting in inserting, slightly, one end of the shaping arbor within one
end of the tube to be acted upon, and then subjecting the arbor and tube to the
action of heat, which expands the tube and permits it to slide down and from the arbor
by gravity.
Dated this 20th day es
41
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C.,
Agents for the Applicant.