Improvements in the Process of Drawing Tubes.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Process of Drawing Tubes.
I, PIERRE EUGENE SECRETAN, of 16, Rue Drouot, Paris, in the Republic of
France, Manufacturer, do hereby declare the nature of this invention to be as
follows:-
The process of drawing tubes at present employed consists in taking the more
or less long and thick billets, skelps or casts and passing them on chain or
hydraulic benches between draw plates and mandrels.
The same action may be obtained by means of rollers or hammering machines.
These mechanical means have for their object 1st. To considerably elongate
(at a minimum in the proportion of 400 per 100) the billets casts or skelps.
2nd. To reduce the thickness of the same in a considerable manner and at
least in the proportion of 12-15 to 2-3.
This process of drawing yields good results and it is hardly possible to obtain
better ones with it when it is applied to tubes made by the old processes of casting,
boring and the like. This same process may also be applied to tubes obtained
by electrolysis, and the results which are obtained are satisfactory when the tubes
have to be employed cold, in a cold hammered condition, or when it is a question
of tubes for use with steam at low pressures.
It is quite otherwise however in the case of tubes intended to receive steam at
high pressures. In fact when treated by the ordinary known processes of draw-
ing which consist in simultaneously gradually elongating the metal and reducing
its thickness considerably, such tubes have, in the case of high pressures and high
temperatures (1) a diminution of resistance, and (2) a loss, or an
enormous
diminution, in the limit of elasticity, and the result of this is the frequent
accidents which have been recorded in recent times which arise when these tubes
are used for high temperatures.
My invention has for its object an improved process of drawing tubes which
remedies these various drawbacks. It consists, (taking it for granted that it is
desired to obtain a tube of given dimensions) in taking a hollow billet having a
diameter 35 to 100% greater than the final diameter of the tube which is to
be produced according to the kind of tubes which are to be produced, and having
a thickness of metal equal to the required final thickness desired in the completed
tube, and causing the said billet to undergo:-
1st). Instead of a strong re-heating, rising to at least 600 or 700°, a simple
reheating in the fire to a dull or visibly red heat of a temperature of about 400°.
2nd). Strong successive drawings of the metal each yielding a little elongation
and diminishing the original diameter, but maintaining, at each drawing, the
original thickness of the metal or walls of the tube by operating without com-
pression of the metal, this being effected by using a draw plate and mandrel
with diminishing diameters but with the space between them always the same,
and always equal to the original thickness of the metal.

page_text: This combined work of re-heating to a dull red heat strong drawing and con-
stant maintenance of the original thickness of the walls of the billet, has for
result to completely change the molecular condition of the metal and to permit
it in consequence to acquire a superior resistance and a much higher limit of
.elasticity than those obtained by the ordinary drawing processes even in spite
of re-heating it at more than 600° and with samples broken at high temperatures.
In certain cases if it be desired to obtain still greater resistances, and greater
limits of elasticity with good elongations for special purposes, spiral coils, bends
or the like, for instance, I may reduce the original thickness a very little, but
this reduction, whatever may be the original thickness, must not exceed half a
millimetre as a maximum for any number of drawings, diameters and thick-
nesses.
Dated thin 10th
J
100%
Improvements in the Process of Drawing Tubes.
I, PIERRE EUGENE SECRETAN, of 16, Rue Drouot, Paris, in the Republic of
France, Manufacturer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:
The process of drawing tubes at present employed consists in taking the more
or less long and thick billets, skelps, or casts and passing them on chain or
hydraulic benches between draw plates and mandrels.
The same action may be obtained by means of rollers or hammering machines.
These mechanical means have for their object-
1st. To considerably elongate (at a minimum in the proportion of 400 per 100)
the billets casts or skelps.
2nd. To reduce the thickness of the same in a considerable manner and at
least in the proportion of 12-15 to 2-3.
This process of drawing yields good results and it is hardly possible to obtain
better ones with it when it is applied to tubes made by the old processes of casting,
boring and the like. This same process may also be applied to tubes obtained
by electrolysis, and the results which are obtained are satisfactory when the tubes
have to be employed cold, in a cold hammered condition, or when it is a question
of tubes for use with steam at low pressures.
It is quite otherwise however in the case of tubes intended to receive steam at
high pressures. In fact when treated by the ordinary known processes of draw-
ing which consist in simultaneously gradually elongating the metal and reducing
its thickness considerably, such tubes have, in the case of high pressures and high
temperatures (1) a diminution of resistance, and (2) a loss, or an
enormous
diminution, in the limit of elasticity, and the result of this is the frequent
accidents which have been recorded in recent times which arise when these tubes
are used for high temperatures.
My invention has for its object an improved process of drawing tubes which
remedies these various drawbacks. It consists (taking it for granted that it is
desired to obtain a tube of given dimensions) in taking a hollow billet having a
diameter 35 to 100% greater than the final diameter of the tube which is to

page_text: be produced, according to the kind of tubes which are to be produced, and having
a thickness of metal equal to the required final thickness desired in the completed
tube and causing the said billet to undergo:—
1st). Instead of a strong re-heating, rising to at least 600 or 7000, a simple
reheating in the fire to a dull or visibly red heat of a temperature of about 400°.
2nd). Strong successive drawings of the metal each yielding a little elongation
and diminishing the original diameter but maintaining, at each drawing, the
original thickness of the metal or walls of the tube by operating without com-
pression of the metal, this being effected by using a draw plate and mandrel
with diminishing diameters but with the space between them always the same,
and always equal to the original thickness of the metal.
This combined work of re-heating to a dull red heat strong drawing and con-
stant maintenance of the original thickness of the walls of the billet has for
result to completely change the molecular condition of the metal and to permit
it in consequence to acquire a superior resistance and a much higher limit of
elasticity than those obtained by the ordinary drawing processes even in spite
of re-heating it.at more than 6000 and with samples broken at high temperatures.
In certain cases if it be desired to obtain still greater resistances, and greater
limits of elasticity with good elongations for special purposes, such as where
the tubes are to be formed with bends or into coils or the like, I may reduce the
original thickness a very little, but this reduction, whatever may be the original
thickness, must not exceed half a millimetre as a maximum for any number of
drawings, diameters and thicknesses.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, declare that what I
claim is:-
1. An improved process of drawing tubes consisting in simply re-heating the
hollow billet to a dull or visibly red heat instead of highly re-heating it, and in
then passing same repeatedly through a draw plate in order to diminish the
original diameter, and change its molecular condition, but suppressing, during
the passage of the hollow billet through the draw plate, any reduction of the thick-
ness of the metal or walls of the billet and maintaining the original dimensions
of said walls in order to obtain great resistance and a high limit of elasticity at
high temperatures substantially as hereinbefore set forth.
2. In the herein described process of drawing-tubes; reducing the thickness
of the metal during the drawing by half a millimetre as a maximum where the
tubes are to be formed with bends or into coils or the like, substantially as herein-
before set forth.
נד
11.
1001
1
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1000
W. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.