Process of and Apparatus for Manufacturing Metal Tubes from Solid Billets.
Year: 1897

page_text: Date of Application (in the United Kingdom), 23rd Dec., 1897
Compléte Specification Left, 23rd Dec., 1897-Accepted, 19th Mar., 1898
COMPLETE SPECIFICATION.
A Process of and Apparatus for Manufacturing Metal Tubes from
Solid Billets.
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 particularly
described and ascertained in and by the following statement :-
My invention relates to piercing heated metal blanks or billets preparatory to or
in the process of forming such blanks or billets into metallic tubes."
Its objects are to pierce such blanks longitudinally by passing them endwise
between rolling surfaces and over the point of a mandrel lying in the pass between
them, the rolling surfaces compressing and slightly reducing the diameter of the
blanks without twisting or disturbing the longitudinal arrangement of their fibres
and without there being any slip between the rolling surfaces and those portions of
the blanks with which they come into contact.
The method by which this is done 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 views which are intended
principally to illustrate the shapes of the rolls or discs upon which the active working
surfaces are formed and the piercing mandrels, and their relative positions, 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 in which rolls are
preferably employed, and which constitutes a part of my invention, and with which
the objects thereof may be attained.
Figure 2 is a side elevation, and
Figure 3 an end view of the same.
Figure 4 illustrates a slight modification in the disposition of the rolls shown in
Figure 1.
Figures 5, 6 and 7 are respectively a plan view, a side elevation and an end view
of a modification of my invention as it is illustrated in Figures 1, 2 and 3.
Figures 8 and 9 are diagrammatic views illustrating the effects of different
methods of adjusting my 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

page_text: invention to use either two rolls or discs or as many more than two as may be
desired and as can conveniently be grouped about a common pass to effect the
purposes of my invention.
I prefer to use two rolls as illustrated in Figures 1 to 9, inclusive, of the drawings,
and shall proceed to describe this construction in detail.
In Figures 1, 2 and 3 I show two rolls A, and B, located at opposite sides of
a pass with their axes lying in. the same horizontal plane with the axis of the pass.
These rolls revolve in the direction shown by the arrows and may be driven in any
suitable manner. They are conical throughout their main or working portions and
are so arranged that their axes and the lines of their working sides all converge
towards and intersect a common point C, on the axial line of the pass...
The pass between the rolls is wider at its entrance than at. its exit end. so that a
billet introduced between the rolls is gradually compressed and reduced in diameter
as it advances towards the exit end of the pass. This is for the purpose of giving the
rolls a continuing and uniform grip on those portions of the billet lying within the
pass and in contact with their opposing surfaces.
This grip is of sufficient intensity or power to compel the rotation of the billet
against the resistance of the piercing mandrel D, which lies in the pass and which
penetrates and opens the billet as the latter is forced endwise through the pass, the
endwise motion of the billet together with its rotation enabling the mandrel to bore
or pierce into the mass of hot metal advancing against it..
With the rolls disposed as shown in Figures 1, 2 and 3 they impart to the billet
rotary motion only, and the said billet is forced to move endwise by means of a.
hydraulic ram R, or other suitable mechanical appliance, pressing upon the rear end
of the billet. Under this arrangement the heated billet is subjected to two forces;
first, the endwise thrust of the ram R, forcing it into the converging pass between
the adjacent surfaces of the rolls and against the point of the stationary mandrel D,.
located in the pass; and second, the rotary movement imparted to it by the rolls so
that it yields to the boring action of the point of the mandrel, flowing or expanding
around the conical head of the mandrel, and passing therefrom in tubular form.
It will be observed that, owing to the converging sides of the pass, that portion of
the billet within the grip of the rolls is smaller in diameter at its exit than it is at
its entrant end.
Now if the rolls were cylindrical or of uniform diameter they would of necessity
impart a higher speed of rotation to that portion of the billet within their grip which
has the smaller diameter than to the portion having the larger diameter; and this
would result in a twisting of the billet.
With my conical rolls arranged as shown there is absolutely no twist imparted by
the rolls to the billet and no slip between the contacting surfaces of the rolls and the
billet, for while the converging sides of the pass cause a gradual diminishing of the
diameter of the billet it will be observed that the diameters of the rolls diminish
progressively in the same ratio as the diameters of the billet decrease; the larger
diameter of the billet being gripped by large diameters of the rolls while the smaller
diameters of the billet are gripped by proportionately smaller diameters of the rolls
so that an absolutely uniform speed of rotation is imparted to every portion of the
billet within the grip of the rolls.
This I regard as a most important feature of my invention and it is the result of
causing the axes of both rolls and the lines of their working surfaces to converge 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 converging pass between them in which there is not
some twist imparted to the billet, or some slip between the billet and the working
faces of the rolls or both.
As shown in Figure 1, I locate the point or tapering head of my piercing mandrel
within or substantially within the pass and between the convergent adjacent sides of
the rolls so that the largest part of the mandrel head is at or near the narrowest part
of the pass, preferably slightly beyond or outside of a line drawn across the narrowest

page_text: part of the pass as indicated in the drawing.. This is to insure the continuance of;
the grip of the rolls on the billet throughout the pass until it has been entirely;
pierced through from end to end. The action of the rolls on opposite sides' of
the pass compresses the opening tubular structure closely against the sides of the
mandrel head, making the tube slightly oval so that there is comparative freedom
between the top and bottom surfaces of the mandrel and the inside of the tube. If.
therefore the largest diameter of the mandrel head is located slightly beyond or
outside of the narrowest part of the pass, the action of the last part of the mandrel
head merely serves to take out this oval and form the tube into a true cylinder.
The small ends of the conical rolls may be made to taper more rapidly than the
main portions of the rolls as shown at a, or they may be rounded over as shown at b.
In either case they may impinge only slightly upon the outside of the work as it
passes over and off the mandrel head and by their difference in speed rubbing upon:
and to some extent burnishing the exterior of the tubular product, or they may be so
shaped and arranged relatively to the conical head of the mandrel as not to touch
upon the work after it leaves the head of the mandrel. They are not however
important features and may be entirely dispensed with.
While I have in the description of the operation of the mechanism shown in
Figures 1, 2 and 3 stated that in this disposition. of the parts, the rolls would pass a
billet without slipping upon its surface I had reference particularly to circumferential
slip but not to the endwise slip of the billet along the surface of the rolls as it is
being pushed through the pass by the ram.
:
-:
In order to overcome this endwise slip of the 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 billet forward. This
inclination should be just enough to have the feeding tendency of the rolls equal to
the speed of the feed imparted to the billet by the ram.
'
With this construction there is absolutely no slip of any kind between the rolls
and the 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 sides 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 any suitable guides may be employed to hold the work in
its proper position in the pass.
In Figures 8 and 9 are illustrated the effects of certain adjustments of the rolls
toward or away from each other to permit of variation of the sizes of work they may
produce.
I consider it better to adjust the rolls toward 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 converge
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 which are adjustable
by swinging them towards or away from each other around an axis passing through
the centre of convergency of their respective axes and the lines of their working
surfaces and through the axial lines of the pass.
•
This is an excellent method of adjustment; but I am aware that within certain
limits the rolls might be adjusted laterally as on the line Y (Figure 9), at right angles
to the axis of the pass, and although the converging points c, c, of their axes and
working surfaces would not lie 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 billet without the aid of

page_text: a hydraulic ram or other mechanical appliance to force the billet through the pass
and over the head of the mandrel.
In this construction while the axes and lines of the faces of the rolls do not inter-
sect a common point on the axis of the pass; they do intersect points on a common
line passing through the axis of the pass but above and below said axis respectively
as hereinbefore described with reference to 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 nor resisted this movement;
but in the construction shown in Figures 5, 6 and 7 the inclination of the rolls is such
as to make them active agents of this endwise movement of the billets against the
opposing resistance of the mandrel, enabling me to dispense with other agencies such
as the ram used for this purpose. When the rolls are thus inclined a horizontal line
drawn transversely across the axis of the pass at mid-length of the pass should
intersect also the axes of the two rolls, as shown by the 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 fully described in
connection with Figures 1, 2 and 3.
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 process of manufacturing tubes by piercing heated metal billets or blanks
which consists in subjecting the said billets to lateral rotation and compression
without twisting their fibres and without slip between the metal and the compressing
surfaces, and simultaneously subjecting the metal to forcible longitudinal pressure
against a mandrel thereby causing the metal to yield and expand around said mandrel
substantially as set forth.
2. In the manufacture of tubes from metal blanks or billets 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 and for the purpose set forth.
3. In the manufacture of tubes from metal blanks or billets 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 and for the purposes set forth.
4. The angular method of adjustment substantially as and for the purpose set forth
with reference to Figure 8.
5. The linear method of adjustment substantially as and for the purpose 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 exit end, a piercing mandrel located in said
pass, the axes of the rolls and the lines of their working faces converging towards
and intersecting a common point on the axial line of the past, substantially as
set forth.
7. The combination of conical rolls disposed so as to form a pass between them
with a piercing mandrel located in said pass, the pass gradually diminishing in width
towards its exit end and the diameters of the rolls diminishing progressively in the
same direction and in the same ratio as the width 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 its exit end, a piercing mandrel located in
the axial line of the 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 a
right angle through the axis of the pass, substantially as set forth.

page_text: 9. The combination of conical rolls disposed so as to form a pass between them
the width of which diminishes towards its exit end in the same ratio as the diameters
of the rolls diminish, a piercing mandrel located in the pass and means for forcing
billets or blanks endwise through the pass and against the mandrel substantially
as set forth.