Year: 1897

page_text: I, RALPH CHARLES STIEFEL, of Ellwood City, Lawrence County, in the State
of Pennsylvania, United States of America, Engineer, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be par-
ticularly described and ascertained in and by the following statement:-
My invention relates to enlarging or expanding metallic tubes or tubular
structures.
Its objects are to increase the diameters of such structures and to reduce the
thickness of their walls, by passing them endwise between rolling bodies and over
an expanding mandrel lying in the pass between them, the compressing action of
the rolling bodies and the mandrel on the walls of the tubes being such as to
gradually reduce their thickness and correspondingly increase the diameter of the
tube without materially increasing its length and without twisting or disturbing
the longitudinal arrangement of the fibres of the metal, and also, without there
being any circumferential slip between the surfaces of the tubes and the faces of
the rolling bodies and the mandrel with which they come into contact.
The method by which this is accomplished and the details of the apparatus
for doing it will be readily understood from the following description read in
connection with the accompanying drawings.
These drawings show my invention by diagrammatic figures which are intended
principally to illustrate the piercing mandrel and the shapes of the rolling bodies,
together with the relative positions of the said parts, no attempt being made to
show the frame work or housings by which the parts are carried, or the means for
driving the several moving parts of the mechanism, as such matters are well
understood by those familiar with this class of machinery.
Figure 1 is a plan or top view illustrating the preferred shapes and one form of
the relative arrangement of the several parts of a mechanism employing conical
This figure
rolls, and with which the objects of my invention may be attained.
is made on a larger scale than the other figures of the drawings.
Figure 2 is a side elevation, and
Figure 3 an end view of the same on a reduced scale.
Figure 4 illustrates a slight modification in the relative disposition of the rolls.
Figures 5, 6 and 7 are respectively a plan view, a side elevation, and an end
view of a modification of my invention.
•

page_text: Figures 8 and 9 are diagrammatic views illustrating the effects of different
methods of adjusting the rolls or discs to adapt them, within certain limits, to
varying sizes of work.
Figure 10 is an end view, illustrating four rolls grouped about a common pass,
instead of two as shown in the preceding figures, it being within the scope of my
invention to use either two rolls or as many more than two as may be desirable and
as can conveniently be grouped about a common pass to effect the purposes of my
invention.
At this time I prefer to use two rolls only as illustrated in Figures 1 to 9 of the
drawing, and for convenience I shall confine myself to a detailed description of this
construction before describing the constructions illustrated by the other figures of
the drawings.
In Figures 1, 2 and 3 I show two rolls A, and 3, located on opposite sides of a
pass with their axes lying in the same horizontal plane as the axis of the pass.
These rolls revolve in the directions shown by the arrows and may be driven in
any suitable manner. They are conical throughout their main working portions
terminating at their smaller extremities in ends a, and b, the faces of which are
more inclined to their axes than are those of the main portions of the rolls, and
these faces as they recede from the main portions of the rolls are slightly curved
or rounded in towards the axes of the rolls.
The rolls are so shaped and arranged that their axes and the line of their main
working surfaces all converge towards and intersect the axial line of the pass at a
common point C.
The sides of the pass at its entrance end, between the surfaces of the small
ends a, and b, of the rolls, converge slightly, the pass diminishing in width until
it reaches the line L, which crosses the narrowest part of the pass and intersects
the smaller ends of the main conical portions of the rolls.
From this line the sides of the pass diverge rapidly and its width increases
towards its exit end. Within the pass between the rolls is located the conical
head D, of an expanding mandrel, which is free to rotate.
In Figure it will be observed that the first bite or compression upon the walls
of the tubular billet between the faces of the rolls and mandrel takes place at the
line L, which crosses the pass at its narrowest point, and that the mandrel is so
shaped that its first contact with the interior of the tube takes place on this line.
At the line L, the space between the rolls and the mandrel is equal in width to
the thickness of the walls of the tubular billet to be operated upon, while at the
line M, it is equal in width to the reduced thickness of the walls of the finished
tubular product.
The angle of divergence of the sides of the pass and of the sides of the conical
mandrel and their relations to each other and the consequent length of the grip of
the rolls and mandrel on the work between them may be varied as found desirable
to adapt them to the work to be performed, the differences in materials to be
operated upon and the amount of expansion of the tube or reduction in thickness of
its walls being important factors in determining the relative angles and length of
the pass and of the conical head.
With soft and ductile metals that would flow easily, the pass might be short and
its angles quite abrupt, while with harder and more brittle metals that would not
yield readily to the operation, the pass would have to be longer and its angles
easier, to avoid the danger of fracturing the material being worked by an assault
on it more rapid and vigorous than it could yield to.
4
5
In the arrangement of the parts shown in Figures 1, 2 and 3 the hollow billet E,
is forced endwise into the pass and over the head of the mandrel by a hydraulic
ram R, or other suitable mechanical appliance, the abutting end of which may
revolve with the billet if desired. The rolls in these figures merely revolve the
billet by contact therewith and compress its walls against the head of the mandrel 5
so that as it advances the thickness of its wall is progressively reduced and its

page_text: diameters progressively increased until the maximum effects are reached at the
largest diameter of the mandrel head.
With this arrangement of the parts, the tubular billet is subjected to two forces;
first, the endwise thrust of the ram R, which forces it into the pass and against
the mandrel D, and second, the lateral compression of the rolls, which reduce the
thickness of its wall and increase its diameter, so that it is caused to flow or
expand around the conical head of the mandrel and passes therefrom in this
tubular form.
It will be observed that owing to the diverging sides of the pass, that portion
of the tubular billet within the grip of the rolls and mandrel is smaller in diameter
at the entrance than it is at the exit end of the pass. Now if the rolls were cylin-
drical or of uniform diameter they would of necessity impart a higher speed of
rotation to the smaller diameter of that portion of the billet within their grip than
to the portion having the larger diameter, which would result in a twisting of the
hollow billet or a tendency to tear it.
With my conical rolls arranged as shown there is absolutely no twist imparted
by the rolls to the billet or tubular structure in process of formation, and no slip
between the contacting surfaces of the rolls and the said tubular structure: for
while the diverging sides of the pass cause a gradual enlargement of the diameter
of the tubular structure it will be observed that the diameters of the rolls increase
progressively in the same ratio as the diameters of the tubular structure increase,
the smaller diameter of the structure being gripped by the small diameters of the
rolls while the larger diameters of the structure are gripped by proportionately
larger diameters of the rolls, so that an absolutely uniform speed of rotation is
imparted by the rolls to every portion of the tubular structure within their grip.
I regard this as a very important feature of my invention and it is the result of
converging the axes of both rolls and the lines of their working surfaces to a
common point on the axial line of the pass.
So far as I am aware this has never been done before and I know of no device
with rolls having a tapering or diverging pass between them, in which there is
not some twist imparted to the tubular billet or some circumferential slip between
the billet and the working faces of the rolls, or both.
While I have in the preceding description of the operation of the mechanism
shown in Figures 1, 2 and 3 stated that the rolls would pass the tubular structure
without slipping upon its surface, I had reference particularly to circumferential.
slip and not to the endwise slip of the tubular billet as it is being pushed through
the pass by the ram R.
In order to overcome this endwise slip of the tubular billet on the contacting
surfaces of the rolls I may slightly incline the axes of my rolls as shown in
Figure 4 so that the rolls themselves will have a slight tendency to feed the tubular
billet forward. This inclination should be just enough to make the forward-feed-
ing tendency of the rolls equal to the speed of the feed imparted to the tubular
billet by the ram.
With this construction there is absolutely no slip of any kind between the rolls
and the tubular billet. In it however the axes of the rolls and the lines of their
working surfaces do not converge to a common point on the axis of the pass, but
the axis and side of one roll converge to a point above the axis of the pass, while
the axis of the other roll and its sides converge to a point below the axis of the
pass, the two points lying in a common vertical line passing through the axis of
the pass.
In connection with my rolls and mandrel any suitable guides may be employed
to hold the work in its proper position in the pass. In some instances I deem it
preferable that the surfaces of these guides against which the work rests should
conform to the longitudinal contour or outline of the sides of the tubular billet
being worked, so that the structure may be supported at every portion of its length
within the grip of the rolls. The guides may be stationary so that the work will

page_text: slip upon them as it revolves, or roller guides may be used that will revolve with
the work, or otherwise, as found desirable.
In Figures 8 and 9 are illustrated the effects of certain adjustments of the rolls
towards or away from each other to permit, within certain limits, of variations of
the sizes of work they may produce.
I consider it better to adjust the rolls towards or away from each other by moving
them angularly around a common centre or axis C, as shown in Figure 8 where it
will be seen that the axes and the lines of the working faces of the rolls will con-
verge upon this centre or axis C, in every position to which the rolls may be
adjusted.
This method of adjusting the rolls towards or away from each other I regard as
another very important feature of my invention and so far as I am aware this has
never been done before and I know of no device with opposed rolls being adjustable
by swinging them around an axis passing through the centres of convergency of
their respective axes and lines of working surfaces and through the axial line of
the pass.
This is an excellent method of adjustment, but I am aware that within certain
limits the rolls might be adjusted laterally or at a right angle to the axis of the
pass in the direction of the line Y, Figure 9, and although the intersecting
points c, c, of their converging axes and working surfaces would not intersect a
common point C, on the axis of the pass, the rolls might still work with a certain
degree of efficiency.
In Figures 5, 6 and 7 I illustrate a modification of my invention in which the
axes of the rolls are oppositely inclined relatively to the axis of the pass so that the
rolls themselves will cause the endwise movement of the hollow billet without
the aid of a hydraulic ram or other mechanical appliance to force the hollow billet
into the pass and upon the head of the expanding mandrel.
In this construction while the axes and lines of the faces of the rolls do not
intersect a common point on the axis of the pass they do intersect a common line
passing through the axis of the pass but above and below said axis respectively as
hereinbefore set forth in the description of Figure 4.
In the construction shown in Figure 4 however the axes of the rolls were only
inclined enough to render the rolls passive in their effect upon the endwise move-
ment of the billet; that is to say they neither assisted or resisted this movement;
but in the constructions shown in Figures 5, 6 and 7 the inclination of the rolls
is such as to make them active agents in this endwise movement of the billet
against the opposing resistance of the mandrel thereby enabling me to dispense
When the rolls
with other agencies for this purpose, such for example as a ram.
are thus inclined, a horizontal line drawn transversely across the axis of the pass
at mid-length of the pass should intersect the axes of the two rolls as shown by
line Z, Figure 5.
With the exception of the inclination of the axes of the rolls, the general shapes
of the parts and their relative positions are substantially like those described in
connection with Figures 1, 2 and 3.
With the axes of the rolls inclined for the purpose of securing endwise feed of
the hollow billet without the aid of a ram or other suitable means, the small ends a,
and b, of the rolls have a function which though not very important in any of my
constructions may be entirely dispensed with (where the tube is not too large to
enter the pass) where a ram is used to feed the billet.
Where a ram is used and the surfaces or ends a and b exist, the relation of the
outside diameter of the billet to the width of the entrance or narrowest part of the
pass is not a matter of great importance. If the hollow billet is slightly larger
in diameter than the width of the rolls at the line L, the surfaces a and b, of the
rolls will merely rub against and burnish the outside of the hollow billet before it
enters the pass, and by lightly compressing the sides of the billet spring it to a
slight oval form.
While these effects are not injurious they are neither sought nor specially

page_text: avoided with a ram feed, and the outer diameter of the hollow billet may be
exactly equal to or even slightly smaller than the width of the pass at the line L,
and enter the pass without coming in contact with the surfaces a, and b, as shown
at N, Figure 1 without detriment to the efficiency of the apparatus.
When however the ram is dispensed with and the rolls inclined to produce the
forward feed it is preferable that the first end of the hollow billet should be
gripped by the rolls before it encounters the mandrel and that this grip should be
sufficiently powerful to overcome the resistance of the first contact of the hollow
billet with the sloping sides of the mandrel.
When this construction is used therefore, it is preferable that the outside
diameter of the hollow billet should slightly exceed the width of the pass at the
line L, so that it is fairly gripped as indicated at O, Figure 1, by the surfaces a, b,
which rotate and give the hollow billet its forward impulse before it encounters
the mandrel. This may cause the hollow billet to be sprung into a slight oval
form by pressure between the two rolls before it encounters the mandrel but I
do not regard this as injurious or objectionable.
It is in fact an effect that is being produced throughout the entire length of the
tubular billet that is within the field of operation of the rolls and mandrel, the
rolls pressing the side of the structure against the mandrel expand it and cause it
to assume a slight oval form, so that while the tube is pressed at its sides by the
rolls against the mandrel its oval form insures absolute freedom from contact of
the inside of the tube with the top and bottom sides of the mandrel. As a result
of this there is no sliding friction of the inside of the tube upon the head of the
mandrel except at the immediate sides where it is in the pinch between the rolls
and the mandrel, and as this point is constantly changing with the revolution of
the mandrel and hollow billet to bring new portions of the latter into operation,
the sliding contact of the hollow billet upon the mandrel is a helical rather than
an endwise slip.
The two sides a, b, are not however absolutely essential and may be dispensed
with and the first contact between the rolls and hollow billet can be produced in
the following manner. Before entering the hollow billet, the rolls may be slightly
separated or drawn away from the mandrel upon which the end of the hollow billet
is thrust, the rolls being then closed into their normal working positions where
they firmly grip the billet and begin the process of expanding it upon the mandrel
which process is carried on as hereinbefore described.
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:-
1. The process of expanding metallic tubes which consists in subjecting them
to lateral rolling compression upon a conical mandrel without twisting their fibres
and without slip between their sides and the compressing rolling surfaces, and
simultaneously subjecting them to forcible endwise movement against the mandrel
thereby causing the metal to yield and expand around said mandrel, substantially
as set forth.
2. For the purpose of expanding tubes over a mandrel the employment of rolls
whose axes and the lines of whose working faces converge to a common point on
the axial line of the pass substantially as set forth.
3. For the purpose of expanding tubes over a mandrel the employment of rolls
whose axes and the lines of whose working faces converge on two points on a
line intersecting the axis of the pass, that is to say, the axis and the line of the
working face of one roll converging on a point on one side of the axis of the pass
and the axis and the line of the working face of the other roll converging on a
point on the other side of the axis of the pass, a line joining said points intersecting
the axial line of the pass substantially as set forth.
4. For the purpose of expanding tubes the angular method of adjustment sub-
stantially as set forth with reference to Figure 8.

page_text: 5. For the purpose of expanding metal tubes the linear method of adjustment
substantially as set forth with reference to Figure 9.
6. The combination of conical rolls disposed so as to form a pass between them
the sides of which converge towards its entrant end, a mandrel located in said
pass, the diameters of the rolls diminishing progressively in the some direction and
in the same ratio as the width of the pass, substantially as set forth.
7. The combination of conical rolls disposed so as to form a pass between them
the sides of which converge towards the entrant end, a conical mandrel located in
said pass, the axes of the opposed rolls and the lines of their working faces sub-
stantially converging towards and intersecting a common point on the axial line
of the pass substantially as set forth.
8. The combination of conical rolls disposed so as to form a pass between them
the sides of which converge towards the entrant end of the pass, a conical mandrel
located in said pass, the axes of the opposed rolls and the lines of their working
faces converging towards and passing through points on a common line drawn
at right angles through the axis of the pass substantially as set forth.
9. The combination of conical rolls disposed so as to form a pass between them
the sides of which converge towards its entrant end, a conical mandrel located in
said pass, the diameters of the rolls diminishing in the same ratio as the width of
the pass diminishes, with means for forcing hollow billets or blanks endwise into
the pass and against the mandrel substantially as set forth.
Dated this 23rd day of December 1897.
licant,
JAMES G. LORRAIN, M.I.E.E., M.I.Mech. E.,
Norfolk House, Victoria Embankment, London, W.C.,
Chartered Patent Agent.
For the Applicant,
JAMES G. LORRAIN, M.L.E.E., M.I.Mech. E.,
Norfolk House, Victoria Embankment, London, W.C.,
Chartered Patent Agent.