Improvements in the Manufacture of Jointless Tubes.
Year: 1893

page_text: Date of Application, 10th Aug., 1893
Complete Specification Left, 16th Nov., 1893—Accepted, 16th Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Jointless Tubes.
I, EDOUARD MARTIN of 46 Rue de Dunkerque, Paris, France, Manufacturer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to the manufacture of metal tubes without welded or other
joints. For this purpose a steel mandrel is placed upright in a cylindrical mould
which is surmounted by a cup having through its bottom a number of holes
situated about midway between the exterior of the mandrel and the interior of the
mould. Molten metal, poured into the cup, descends by these holes into the mould,
in streams which do not touch the mandrel, which had been previously coated with
material to prevent adhesion. On the cooling of the cast the mandrel is withdrawn,
having cast on it a short sleeve of the metal which is to form the tube. The whole
is heated sufficiently to soften both sleeve and mandrel, and is reduced in diameter
and extended in length by rolling, this having the effect of making the mandrel
smaller at the middle than at the ends. The tube and mandrel are then cut across
at the middle so as to produce two pieces in each of which there is a somewhat
tapered mandrel. By rolling or mangling, the tube is stretched so as to loosen it
from the mandrel which is withdrawn, after which the tube is drawn through
dies.
Dated this 10th dex of Aucnet 1892
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Jointless Tubes.
I, EDOUARD MARTIN, of 46 Rue de Dunkerque, Paris, 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 ascertained in and by the following
statement:—
This invention relates to the manufacture of metal tubes without welded or other
joints. For this purpose a mandril of steel or other metal harder than that used
for the tube to be formed is placed upright in a cylindrical mould which is
surmounted by a cup having through its bottom a number of holes situated about
midway between the surface of the central mandril and the surrounding interior
surface of the mould. Molten metal, poured into the cup, descends by these holes
into the mould, in streams which do not touch the mandril, which had been
previously coated with material to prevent adhesion. On the cooling of the cast,
the mandril is withdrawn from the mould, having cast on it a short sleeve of the
metal which is to form the tube. The whole is heated sufficiently to soften both
sleeve and mandril, and is reduced in diameter and extended in length by rolling,
this having the effect of making the mandril smaller at the middle than at the
ends. The tube and mandril are then cut across at the middle so as to produce
two pieces in each of which there is a somewhat tapered mandril. By rolling or
mangling, the tube is stretched so as to loosen it from the mandril, which is with-
drawn, after which the tube is drawn through dies.
During these several operations it is essential to take care that the mandril does
not become welded or firmly united to the surrounding tube, although they are in
perfect contact throughout, as the mandril only serves as the temporary means for
forming the tube. For this purpose the mandril is in the first instance provided

page_text: with a coating of steatite or other material that will prevent the penetration of
the molecules of the sleeve among those of the mandril. Furthermore, it is
essential to prevent that, at the time of casting, the jets of liquid metal shall
impinge upon the surface of the mandril. For this purpose I employ the arrange-
ment of casting mould shewn at Figure 1 of the accompanying drawing. It
consists in adapting to the upper end of the ingot mould L a cup shaped top C,
having an annular recess c, into which is run the molten metal.
This descends into the mould round the central mandril A through a number of
holes tt formed obliquely in the bottom of the annular recess, so that the jets of
metal are directed away from the mandril and against the sides of the mould.
The cup C has a central hole through which and through a hole in the bottom of
the mould the mandril passes, so as to be held centrally thereby, the metal of the
cup being raised round the central hole so as to keep the molten metal therein out
of contact with the mandril.
The mould is shorter than the mandril so that, after casting, the combined
mandril A and sleeve B will appear as at Figure 2, namely with the ends of the
mandril projecting beyond the sleeve, and this serves to afford a ready hold for the
tongs in the subsequent operations of rolling and separating the mandril from
the tube.
After the sleeve has been cast on the mandril and these have sufficiently cooled,
the sleeve should be tapped with a hammer in order to ascertain by the nature of
the sound given that the two parts are not welded or firmly united together.
The combined mandril and sleeve are then heated in a furnace to a temperature
sufficient to soften the metal of both parts, after which they are subjected to a
rolling process. The rolling mill employed for this purpose is of ordinary con-
struction. The pressure produced by the rolls on passing the object repeatedly
through them has a double effect; on the one hand it has a drawing effect upon
the sleeve and thus extends it in length, as also the mandril; on the other hand,
as the pressure is exerted with greater force at the middle part of the sleeve than
at the ends, there is produced a gradual thinning of the mandril from the two ends
of the sleeve towards, the middle. The result hereof is, that by the time the
metal of the sleeve has, by its elongation, covered nearly the whole of the mandril,
the combined bodies will have an appearance shewn by the longitudinal section at
Figure 3, the mandril having the form of two conical frustra, united tegether at
their smaller ends.
The rolling is continued so as to still farther reduce the two bodies in thickness,
but the external thickness of the sleeve will be thereby rendered more approxi-
mately uniform, while the mandril will retain its above described double conical
form, as shewn at Fig. 4.
The first part of the process being thus completed, it is necessary to separate
the mandril from the sleeve.
For effecting this, the combined body is cut through at the middle, as shewn at
Figure 5, thus producing two conical mandrils a a¹ covered respectively with the
sleeves bb. In order to detach the latter from the former, it suffices to increase
the inner diameter of the sleeves. This may be effected by various means.
According to one arrangement a slight hammering after reheating may suffice to
destroy the adhesion of the two bodies, enabling them to be readily separated; or,
according to another arrangement, as shewn at Fig. 6, the combined bodies may be
passed through rolls L having oval or other shaped grooves d that will only exert
pressure upon two or more points of its circumference so as to aid the separation
of the sleeve from the mandril.
Figure 7 shews another arrangement for accomplishing this end, which consists
in passing the combined bodies between two rolls L, having no grooves, whereby
the two parts will become detached from each other at the first passage through,
and the tube will become enlarged at the second passage, whereupon the tapering
mandril can be readily withdrawn.
Figure 8 shews an arrangement for drawing the combined parts a, b, through a

page_text: die having a square hole, whereby they will be subject to pressure at four opposite
points; the tube will thus be separated from the mandril at the parts situated
between those points.
Lastly, Figure 9 shews a mode of separating the parts by rolling them between
two plates P, made to travel in opposite directions which will effect the enlarge-
ment of the tube without deformation.
According to another modification of the above described process, the sleeve
may be cast on or towards the one end of the mandril as shewn at Figure 10. On
subjecting this to the rolling operation in the direction from the end of the
mandril A on which the sleeve B is situated towards the other end, the sleeve will
be extended along the mandril, the outer surface remaining of uniform diameter
while the inner surface as also the mandril will be formed tapering from the one end
to the other.
For converting the extended sleeve from the tapering to the cylindrical internal
form, it is only necessary to draw the same in a draw bench.
By the above described method of rolling tubes on a mandril a great economy
of manual labour will be effected, as several drawing operations are obviated
thereby, and the advantage is gained of being able to manufacture tubes of
greater length and of a more homogeneous nature, and consequently of greater
strength.
The process can be applied to the manufacture of tubes of all kinds of metal,
even iron or steel.
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 herein described improved manufacture of seamless tubes wherein a sleeve
is first cast upon a mandril, the combined parts being then heated and rolled so as
to extend the sleeve upon the mandril, whereby the interior of the sleeve and the
if
mandril are made to assume a tapering form, after which the two parts are,
necessary cut through the middle and are subjected to a rolling or other process
for separating the sleeve from the mandril.
2. In the manufacture of seamless tubes referred to in the first claim, the herein
described method of casting the sleeve upon the mandril in such manner as not to
become welded or firmly united thereto.
3. In the manufacture of seamless tubes referred to in the first claim, the herein
described method of casting the sleeve on the middle part of the mandril, and then
rolling the combined parts when heated so as to produce a tubular sleeve of uniform
external diameter while the internal diameter of the sleeve and the diameter of the
mandril are smaller at the middle than at the two ends, the combined parts being
then cut through at the middle in order to enable the mandril to be removed.
4. In the manufacture of seamless tubes referred to in the first claim, the
herein described method of separating the formed tube from its tapering mandril
by increasing the internal diameter of the tube either by hammering, or by rolling
between rolls having no grooves, or having grooves so formed as to press upon the
tube only at two or more points of its circumference, or by drawing the tube
through a die having a square orifice, or by rolling the tube in a
transverse
direction between two plates moving in opposite directions or by any other suitable
known means.
Dated this 16th day of November 1893.
ABEL & IMKAY,
Agents for the Applicant.