Improvements relating to the Rolling of Metal Tubes.
Year: 1895

page_text: Date of Application, 30th Sept., 1895--Accepted, 2nd Nov., 1895
COMPLETE SPECIFICATION.
Improvements relating to the Rolling 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 :-
This invention relates to the rolling of metal tubes.
The rolling is done over a mandrel, but differs from the method heretofore used,
in that the blank has to pass through wider and wider grooves in rollers, the axes
of which are in the same plane and are parallel with each other, and over wider
and wider mandrels, so that the blank, instead of being contracted to a smaller
and longer tube, is made wider, whether accompanied by a lengthening or not,
depending upon whether the thinning of the tube is exclusively intended to widen
or both to widen and to lengthen.
The blank consists, as is usual in tube-rolling of a hollow piece resembling a
short tube with thick walls. The widening of the aforesaid blank can be done at
once, but it is preferable to roll out the blank into a tube of a smaller external
diameter than that of the blank with comparatively large inner diameter, after
which the tube is widened. The tube is first widened at the end, for instance by
making slits of suitable length and bending the strips apart or by driving in a
mandrel or in any other suitable manner. Thus the rollers, the grooves of which
are wider than the blank are enabled to catch hold of the latter when its widened
end is passed on to the mandrel lying in the groove.
In the accompanying drawing
Figure 1 illustrates the manner in which the widening is accomplished.
Figure 2 is a front elevation of the rollers.
Figure 3 is a sectional elevation of the end of a blank provided with slits, and
Figure 4 a similar view showing the end widened and passed on to the
mandrel.
The rollers a a have one or more grooves a¹, and in connection therewith
mandrels b are provided which are held in place in the groove in any suitable way.
After the blank c has been widened at the end, which can be done, as clearly
shown at c¹ Figures 3 and 4, it is run into the rolling-machine in a groove in the
roller, which groove is wider than the blank. The widening of the blank at the
end allows it to be passed on to the mandrel, and this widening should be sufficient
to enable the rollers to catch hold of the blank when pushed into place upon the
end of the mandrel b, that is to say, the widening and the diameter of the groove
must have such a relation to each other, that the blank, when in place upon the
end of the mandrel, is caught hold of by the rollers and is drawn over the mandrel.
The mandrel will then cause the blank to be widened externally as well as
internally and the rollers roll out the walls of the blank and make them at the
same time more dense.
By repeating the process, passing the blank through wider and wider grooves
and with repeated heatings of the blank when necessary, a tube of great diameter
and with perfectly smooth walls may thus be made. It is evident that the
thickness of the walls may be tolerably accurately controlled.
Instead of making slits in the end of the tube a few projections may extend from
the same and these bent outwards in order to be caught by the rollers. With
regard to the method of rolling the blank in the usual manner to a smaller size,

page_text: and afterwards widening the tube thus obtained, it is, of course, advantageous to
prepare the blank before the widening is commenced, but direct rolling out to a
greater dimension also gives a good result.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :--
In rolling tubes over a mandrel between parallel rollers provided with grooves,
in which the mandrel is placed at right angles with the axes of the rollers, the
method of rolling the tube in a groove of the rollers, which is wider than the blank,
on a mandrel which is so wide that, when the widened end of the blank has been
passed on to the mandrel, the rollers are able to catch hold of the blank and draw
it over the mandrel, in order to obtain a tube, the outer diameter of which is
greater than that of the blank.
Dated this 20th day of Santomban 1905
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.