Improvements relating to Apparatus for the Manufacture of Metal Tubes.
Year: 1894

page_text: Date of Application, 12th Apr., 1894-Accepted, 25th May, 1894
COMPLETE SPECIFICATION.
Improvements relating to Apparatus for the Manufacture of
Metal Tubes.
I, CARL GUSTAF LARSON, of Sandviken, in the Kingdom of Sweden, Engineer,
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:--
When rolling tubes over a mandril the latter is subjected to a considerable
lateral pressure and the mandril bar to a considerable end pressure. If the tube
is of a small diameter and consequently the mandril and the mandril bar also of
a small diameter it sometimes occurs that the mandril, in which the end pin of the
mandril bar is introduced breaks, and that the mandril bar curves.
This invention relates to arrangements for removing these inconveniences, so
that even tubes of comparatively small diameters may be easily rolled.
In order that the mandril may not break in consequence of the connection with
the mandril bar it is not fixed to the latter, that is to say, it is completely loose
and only rests against the end of the latter when rolling. The mandril is kept in
position between the rollers by means of the tube itself and falls down on the
table in front of the rollers when the tube has passed through the latter. The
said table is provided with grooves corresponding to the grooves in the rollers.
The mandril is brought into position between the rollers by means of the tube
blank. The mandril bars are supported by wheels or parts of wheels, which are
placed partly above and partly below the said mandril bars.
In the accompanying drawings,
Figure 1 shows a rear view of the rolling mill.
Figure 2 is a transverse section across the rollers, the mandrils lying upon the
table in front of the said rollers.
Figure 3 is also a sectional view and shows a tube passing through the rollers.
Figure 4 is a plan view and
Figures 5 and 6 show in section and end view the mandril, drawn to a larger
scale, the diameter of the mandril may however in reality be smaller than shown
in these figures.
As shown in the drawings the mandrils a are made in solid pieces and when not
in use have their place in the grooves in the table 6 in front of the rollers, which
grooves correspond to the grooves in the rollers. On the opposite side of the
rollers are the mandril bars c arranged in the usual manner but they are supported
in such a way that they occupy the same position in the grooves of the rollers as
if they were fixed to the mandrils, that is to say, they do not rest on the lower
roller but are concentric with the round bottom of the groove. The mandrils are
as usual pointed at the fore end and transversely cut off at the rear end in order
that they may steadily rest against the end of the mandril-bar, which is also
transversely cut off.
When the hollow tube blank is to be placed between the rollers its fore end is
pushed forwards in the groove of the table against the mandril so that the
pointed end of the latter will enter into the blank. The blank and the mandril
are then pushed up between the rollers. The mandril thereby stops against the
end of the mandril bar placing itself concentrically with the latter, whereupon
the tube is drawn by the rollers over the mandril on to the mandril bar.
When the tube has passed through the rollers the mandril falls down to its
former place upon the table. The fact of the mandril being loose causes no
inconvenience, because it is very easy to bring the mandril up to its place by

page_text: means of the tube blank.
When rolling tubes of small diameters it has ou the
contrary proved to be very advantageous to have the mandril loose and solid
because no rupture can take place between the mandril and the mandril bar and
because the mandril is capable of resisting a greater lateral pressure as it is not
weakened by any connection with the mandril bar. A further advantage consists
therein that the mandril may be easily brought from one groove to another
without moving the mandril bar and also therein that more mandrils than mandril
bars may be used as one of the latter may be used for mandrils of different sizes
provided the mandril has a somewhat greater diameter than the mandril bar.
It is consequently possible to exchange the mandrils without moving the
mandril bars out of their positions. The upper supports for the mandril bars
consist of wheels h h h which are arranged along the mandril bar and are capable
of being moved along the shafts which are journalled above and across the
mandril bars. In order that the wheels may always be in a straight line and may
be simultaneously moved from one mandril bar to another there is a side-piece b¹
placed on each side of the same, the said side-pieces being passed upon the
intermediate shaft and connected with each other. by means of bolts a', and
chains a passing over pulleys a², which have their bearings at the sides of the
rolling mill, are connected with the side-pieces b¹.
The pulleys are rotated by means of the handwheel a', which is connected
with the shaft a' by gearing, which shaft is common to two of the said pulleys a²
on the same side of the rolling mill. The arms a which are passed upon the
shaft and and connected with the side pieces &', serve as a further guide for
the latter. The wheels h h h are at a point on their circumference provided with
a transverse cam or upward projecting rim d and at another point on the
circumference with a shoulder or projection ď³. When the wheel rests with the
latter against a fixed point for instance the bolt a¹ its cam d is just above
the mandril bar and rests against this.
Each shaft d' is below provided with as many supports c' as there are mandril
bars. In Figure 4 only a part is shown. The said lower supports c¹ are like
wheel sectors which have a groove in the periphery for receiving the mandril
bar, a cam at the one radial side, which cam projects over the groove and
also is provided with a groove for receiving the mandril bar, and a counter-
weight which keeps the sector in such a position that the cam 6 will be
vertically above the shaft of the sector and just opposite the cam d. The mandril
bar is consequently supported from above, from the sides and from below and
these supports are placed at three points along its length. It may evidently also
be supported in the described manner at a greater number of points depending
upon its length. For this purpose only the number of supports along the mandril
bar is to be increased.
When the tube is passing over the mandril bar it strikes the cams d and b³.
The wheels are thereby rotated one after the other in the direction of the
arrow, Figure 3, and the lower supports are turned into the position shown in
Figure 3. The tube and the mandril bar are however still supported by the
wheels from above and from the sides and from below by the sectors, in the
grooves of which they remain as shown in Figure 3. When the tube has passed
through the rollers the handwheel a' is rotated, so that the wheels are moved a
step to the side just above the next mandril bar. As soon as they are released
they rotate themselves in the opposite direction to that of the arrow, Figure 3,
so that the cam d moves against the mandril bar and supports the same as above
described.
The last rolled tube located upon the mandril bar may afterwards without
hindrance of the wheels h² be removed from the bar after which the lower
supports return to their vertical positions. The angle irons y serve as a stop for
the lower supports. The form of these latter differ certainly somewhat from that
of the upper ones but it is evident that the lower supports may, like the upper
ones, have the shape of complete wheels. The upper wheels or at least the one
1

page_text: or the ones which are furthest away from the rollers, may likewise be incomplete
wheels, that is to say, have the shape of a sector or a segment.
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 improvement in the mandril of tube rolling mills consisting therein
that the mandril is not fixed to the mandril bar but only resting against the end
of the same when rolling, substantially as shown and described.
2. In a tube rolling mills with the mandrils arranged as indicated in Claim 1
the arrangement in which the mandrils are placed in grooves which are made in
the table in front of the rollers opposite the grooves of the latter with the view
that the tube blank may be easily passed upon the mandril and the latter then be
brought between the rollers against the mandril bar by means of the tube blank,
substantially as shown and described.
3. In tube rolling mills the arrangement for supporting the mandril bars
consisting of several wheels h--h' arranged one behind the other and placed above
the mandril bars which may be moved along their shafts (i) across the mandril
bars, so that they are brought just above the mandril bar which is to be
supported by them, and of rocking pieces (c') which are placed below the mandril
bars on cross-shafts and provided with counter-weights and at the upper rounded
end having a groove or recess for receiving the mandril bar.
4. In the arrangement indicated in Claim 3, the provision of two side
pieces (b) connected with each other between which the wheels (h-h²) above the
mandril bars are placed, chaine, which are connected with the said side pieces and
pass over pulleys (a) at the sides of the rolling mill, these pulleys being in
connection with a suitable gearing with the view that the wheels (h-h³) may be
easily moved across the mandril bars from one mandril bar to the other, sub-
stantially as shown and described.
5. In the arrangement indicated in Claim 3, the provision of a transverse
cam (d) on the edge of the wheel and a shoulder by means of which the wheel
rests against some fixed point whereby it is kept in such a position that it rests
against the mandril bar with the cam but can be rotated when the tube passing
on the mandril bar engages with the cam, substantially as shown and described.
6. In the lower supports for the mandril bars indicated in Claim 3, the arrange-
ment of an upwardly directed cam projecting from the support (c¹) which
receives the mandril bar and corresponds to the cam of the upper wheel (Claim 5)
and is held against the mandril bar so that the support by its own weight is
therefore forced to take a suitable position while the tube is not prevented from
passing on to the mandril bar, substantially as shown and described.
7. The modification of the lower supports (c') (Claim 3) in which they consist
of complete grooved wheels which have a counterweight and a cam, the latter
provided with a recess for receiving the mandril bar.
Dated this 12th day of April 1894
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.