IMPROVEMENTS IN THE MANUFACTURE OF METAL TUBES
Year: 1884

page_text: I, JAMES ROBERTSON, of Govan, in the County of Lanark, Engineer, do hereby
declare the nature of my said Invention for "IMPROVEMENTS IN THE MANUFACTURE
OF METAL TUBES," to be as follows:-
My Invention relates to new and improved forms and dispositions of dies and
mandrels for rolling drawing shaping and smoothing metal tubes, combined with
improved modes of working the same, consisting mainly of improvements in the
modes and means of rolling, drawing, shaping, and smoothing metal tubes, where
the dies or rolls are made to revolve for operating on the tube externally, and in
the manufacture of metal tubes where the mandrels are made to revolve while
operating on the tube internally, the present invention being mainly a further
development of the improvements in revolving dies and mandrels and modes of
working same for which Letters Patent of the United Kingdom were granted to me
N° 4201 dated the 22nd day of October 1878, entitled "Improvements in frictional
screw gearing and apparatus for drawing, rolling, straightening, shaping and
smoothing wires, rods, bars and tubes."
One improvement consists in forming a revolving mandrel sharp pointed, and
applying or using it for forcing through solid billets of metal and forcing out the
same into tubes without the usual previous operation of being bored, or cast hollow,
the sharp pointed mandrel also having one or more flutes or grooves formed on it
with smoothly rounded edges inclined to the direction in which the mandrel is
revolved to lave aside and displace the metal from the centre of the billet and cause
it to flow in the die in a side direction as well as directly on endwise into a tube
without materially separating, loosening, or wasting part of the metal as is done
by ordinary boring by a sharp drill. By preference in straight, fluted, pointed,
piercing mandrels three or more displacing inclined acting edges are used and the
intervening spaces, grooves or flutings are formed for allowing oil or other lubri
cants to be admitted freely to the acting head or bulb of the mandrel.
Sharp pointed smooth surface revolving mandrels may be used for piercing solid
billets of heated and soft metal but for such metals as copper, tin, zinc and load
operated on in a cold state, the fluted mandrel as described is the best.
The mandrels for this purpose whilst being revolved require great pressure to be
applied or exerted on their ends to produce the forward piercing action on the billets

page_text: .
which may be effected by any mechanical means but is best done by the direct
action of a hydraulic or steam cylinder, ram or piston, as by these the end pressure
can be best reached to the requisite degree, and excess of end pressure which tends
to injure the mandrels is avoided.
For holding and shaping the tube externally for this operation, and also for
drawing out cast or bored hollow billets into tubes, use an improved form of long
die made in halves to produce the necessary retaining hold of the half or semi-
circular die and to withstand the great lateral pressure of the revolving mandrel
exerted through the metal of the tube to the die, and to obtain quick relieving
action or separation of the halves of the long die for getting out the tube when so
formed.
The improved arrangement of long die for this purpose (formed in halves) consists
mainly in forming inclined edges on the sides of the half or semi-circular die
opposite to the opening side of same, a series of short inclined edges or projections
being most suitable where the tube to be formed is of some considerable length, the
two half dies being made to fit into a strong block of metal having corresponding
inclined edges so that the two half dies will wedge themselves in the same and
retain closed the joint of the die thus formed in halves, while the tube is being
formed, the retaining and wedging inclined edges being so disposed as to wedge in
and retain the central joint close by the end pressure of the mandrel and the degree
of angle of the inclined edges 'and wedging hold so as be easily released when
the end pressure of the mandrel or the mandrel is withdrawn for tho reopening of
the die and removal of the tube from it after the tube is formed.
The die with its contained billet and its holder may be either moved forward on
the mandrel or the mandrel moved on end into the die and billet, whilst it is being
revolved.
This die also so formed in halves provides a necessary arrangement of grasping
the billet at the entering end for the mandrel by two small short cod pieces
inserted into the inner surface of the die which fills the billet at this entering end,
the remaining mass of the billet operated upon, and remaining unconverted into a
tube being pushed along the die until all is laid into a tube on the internal surface
of the die. This arrangement of mandrel and die is also an improved means of
converting hollow billets into thin tubes.
Another convenient improved arrangement of long die to be used for similar
mandrels to that just described for forming tubes directly out of solid billets or for
producing from thick tubes or "shells" thin tubes, and affording an effective and
expeditious arrangement for opening and closing the half die, particularly suitable
for forming tubes from billets of hot iron or steel, consists in having the ends of the
half dies formed in about two fifths of a circle, having planed faces, and by tem-
porarily, fastening the half dies thus formed turned for portions of the length of the
die at the two ends to fit strong bush pedestals, the pedestals being fixed on a sole
plate corresponding in length to the die. One of the halves of the die is fixed in
the containing pedestals, the other half being left free to revolve about one fifth
part of the circle or periphery of the die, and thus partially revolved by a lever
cast on it to be actuated by hand or otherwise. The circular channel seat for the
billet to be bored out with its inner edge near to the centre of the die, and corre-
spondingly near and eccentric to the centre of its containing pedestals. In this
way when the actuating lever formed on the half die thus left free to revolve or
oscillate about a fifth part of the circle is depressed, the half die is opened out to a
sufficient degree for the insertion of the billet or shell, and on the lever being raised
the die is again closed and the billet firmly held together by the two containing
pedestals and lever, until the solid "billet" is formed by the mandrel into a tube,
or a thick tube or shell (when such are being operated upon) is converted or drawn
into a thin tube. For making tubes in this way from metal in a heated state, a
very high speed of mandrel is used. For drawing tubes in this way in a cold state
of metal, such as copper and its alloys, a slow rotative motion of mandrel and
careful lubrication of same is necessary.

page_text: Another improved form of long die, also applicable for forming tubes from solid
billets, but, more suitable for drawing shells or thick tubes into thin and finished
tubes, consists of a single half long die and a roll correspondingly semicircularly
grooved, which is used to form the other containing and guiding half of the die.
By preference the long half die is placed under the roll half of the die, and the half
die placed in a sliding channel bed, with an antifriction roll placed at its underside
opposite to the roll half of the die, and all placed in a strong housing.
In the two foregoing improved forms of long dies described, the tube as it
becomes formed adheres to the surface of the die, and the mass of the billet remain-
ing unconverted into a tube, is pushed along the channel of the die until all is
expanded into a tube; but in this modification the long under half of the die
receives the billet and is pushed forward underneath the roll half of the die, and
with the billet between the long die and roll with sufficient grasp to carry the
billet forward over the mandrel and to form it into a tube, the rotundity of the roll
surface relieving the elongating action of the tube sufficiently to allow it to expand
over the mandrel at a greater speed than the speed at which the lower half of the
die and roll is pushed forward. The roll half of the die is preferred to be of
large diameter to produce a long holding grasp of the billet or shell, and to allow
of the roll being driven by the frictional contact only of its under half die. The
ram or piston of an hydraulic cylinder is also the most suitable means for actuating
this form of long die.
An improvement in revolving dies for operating on the external surface of tubes,
consists in forming in them one or more flutes or grooves longitudinally with
inclined and smoothly rounded off edges presented to the metal as the die revolves
to roll the metal down each inclined smoothed-off edge of a flute or groove, making
the metal flow down in a small wave before it and the metal of the shell or thick
tube operated on is laved down into a thick tube sideways as well as on end, as
the shell or thick tube is drawn or forced through the die, which greatly increases
the speed of the drawing action over that obtained by smooth surfaced dies. The
fluting also affords great advantage for more effective lubrication than can be had
with smooth continuous surface revolving dies as heretofore used.
Another improvement in revolving dies to be used for drawing smooth surface
tubes, consists in forming in the acting and drawing down surface of the die one or
more spiral or screw threads and corresponding grooves with rounded inclined
edges, and by drawing or pushing through the shell or tube being drawn down at
a greater or less speed than is due to the pitch of the thread of same, or by
drawing through the tube in the reverse direction to the direction in which the
screw thread would tend to draw through the tube.
In all modes of drawing or pushing through the tube to the speed or direction
of the screw thread, the advantages are obtained that the longitudinal resisting
frictional hold of the die on the tube is greatly reduced and the intervening
grooves between the threads of same provide very greatly improved means of
lubricating the acting surfaces as compared with what is obtained by the use of
continuous surface revolving or stationary dies.
It is preferred, however, as the most effective method of working this form of
revolving die for drawing down tubes, to push or draw the thick tube through the
die at a slower speed than that due to the forward speed of the spiral thread or
threads of the die, the inclined and smoothed-off edges of the die as they revolve
rolling or laving or "spinning" a wave of metal of the tube before it, and causing
it to flow down from a thick tube into one of a thin gauge as may be required,
the action on the tube being drawn down being very similar to the overhauling of
the thread of a screw bolt by its nut. This form of die has also the advantage of
requiring less force to push or draw the tube through it, as the action of the spiral
thread of itself tends to draw through the tube. The die by preference is made conical
and widest at the acting side as required according to the proportion to which the
tube operated upon is being drawn down, and to prevent the spiral inclined edges

page_text: taking too deep a hold, the threads may be made shallow to the requisite degree
suitable to the speed the metal being operated upon can be drawn down.
One or more rounded or inclined edged threads can be formed in the die, two or
four or any number divisible by two, having the advantage of grasping the tube on
directly opposite points on the periphery. Two threads however will be generally
found the best, and the pitch should be large to allow of the requisite speed
endwise without giving a high circumferential speed on the internal surface of
the die.
Spiral dies may be constructed of metal wire or of flat or any other section of
bar twisted forward into a spiral, but round wire or flat bar is the most suitable,
and should be placed in a revolving, housing, with means of drawing out or
compressing in the spiral and thereby within a small limit of diminishing or
increasing the diameter of the die. This form of revolving dies, revolved at a high
speed are very suitable for polishing or burnishing tubes.
One or more spirals may be put in a housing and two will be found for most
purposes the most suitable.
It is intended to work these fluted and spirally formed dies along with smooth
mandrels or any other ordinary form of tube mandrel.
An improved form of revolving tube mandrel consists in giving to its acting or
drawing surface or bulb a spiral form by forming in it one or more spiral threads
with inclined rounded off and smooth surfaces to act on the internal surface of the
tubes similar to that just described in connection with revolving dies.
As accuracy and uniformity of the spiral thread is not important for this
purpose, such mandrels may be for some purposes formed by twisting on flat or
Hluted polygonal square or triangular steel bar according to the number of threads
or shapes of same as may be required. The rolls or acting surfaces of these may
be formed conical or of any other ordinary form, and it is intended to work them
along with ordinary smooth stationary or revolving dies or rolls as also to use them
sharp pointed and along with long dies for drawing out or piercing solid billets
into tubes as hereinbefore described. In working them along with spirally cut
dies it will be an advantage to have the thread of the mandrel formed the reverse
of that of the spiral of the die.
These improved dies and mandrels can be applied and used on most ordinary
forms of tube rolling and drawing benches and as is more particularly described in
my patent specification already referred to for rolling and drawing tubes by or in
connection with revolving dies and mandrels.
An improved arrangement of drawing or rolling bench for working these
consists in a strong revolving head-stock like the main headstock of an ordinary
lathe set at one end for revolving the mandrel for large size tubes with a headstock
in the centre for using the long stationary dies, and short revolving dies and
hydraulic forcing and return stroke cylinders with revolving gear for revolving
the mandrel for small size tubes at the other end of the machine being also
illustrative of a good arrangement of housing and of working these improved
dies and mandrels for drawing rolling and finishing tubes.
D t

page_text: I, JAMES ROBERTSON, of Govan, in the County of Lanark, Engineer, do hereby
declare the nature of my said invention for "IMPROVEMENTS IN THE MANUFACTURE
OF METAL TUBES," 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 new and improved forms and dispositions of dies and
mandrels for rolling, drawing shaping and smoothing metal tubes, combined with
improved modes of working the same, consisting mainly of improvements in the
modes and means of rolling, drawing, shaping and smoothing metal tubes where
the dies or rolls are made to revolve for operating on the tube externally, and in
the manufacture of metal tubes where the mandrels are made to revolve while
operating on the tube internally, the present invention being mainly a further
devolopment of the improvements in revolving dies and mandrels and modes of
working same for which Letters Patent of the United Kingdom were granted to
me No 4201, dated the 22d day of October 1878, entitled "Improvements in
frictional screw gearing and apparatus for drawing rolling straightening shaping
and smoothing wires, rods, bars, and tubes."
One improvement consists in forming a revolving. mandrel sharp pointed, and
applying or using it for forcing through solid billets of metal and forcing out the
same into tubes without the usual previous operation of being bored or cast
hollow, the sharp pointed mandrel also having one or more flutes or grooves formed
on it with smoothly rounded edges inclined to the direction in which the mandrel
is revolved to lave aside and displace the metal from the centre of the billet and
cause it to flow in the die in a side direction as well as directly on endwise into a
tube without materially separating, loosening or wasting part of the metal as is
done by ordinary boring by a sharp drill. By preference in straight, fluted,
pointed, piercing mandrels three or more displacing inclined acting edges are used
and the intervening spaces, grooves, or flutings are formed for allowing oil or other
Jubricants to be admitted freely to the acting head or bulb of the mandrel. Sharp
pointed smooth surface revolving mandrels may be used for piercing solid billets of
beated and soft metal but for such metals as copper, tin, zinc, and lead operated on
in a cold state, the fluted mandrel as described is the best.
The mandrels for this purpose whilst being revolved require great pressure to be
applied or exerted on their ends to produce the forward piercing action on the
billets, which may be effected by any mechanical means but is best done by the
direct action of a hydraulic or steam cylinder, ram, or piston, as by these the end
pressure can be best reached to the requisite degree, and excess of end pressure
which tends to injure the mandrels is avoided.
For holding and shaping the tube externally for this operation, and also for
drawing out cast or bored hollow billets into tubes, I use an improved form of
long die made in halves to produce the necessary retaining hold of the half or
semi-circular die and to withstand the great lateral pressure of the revolving
mandrel exerted through the metal of the tube to the die, and to obtain quick
opening action or separation of the halves of the long die for getting out the tube
when so formed,

page_text: The improved arrangement of long die for this purpose (formed in halves)
consists mainly in forming inclined edges on the sides of the half or semi-circular
die opposite to the opening side of same, a series of short inclined edges or
projections being most suitable where the tube to be formed is of some considerable
length, the two half dies being made to fit into a strong block of metal having
corresponding inclined edges so that the two half dies will wedge themselves in the
same and retain close the joint of the die thus formed in halves, while the tube is
being formed, the retaining and wedging inclined edges being so disposed as to
wedge in and retain the central joint close by the end pressure of the mandrel and
the degree of angle of the inclined edges and wedging hold so as to be easily
released when the end pressure of the mandrel is removed or the mandrel is with-
drawn for the reopening of the die and removal of the tube from it after the tube
is formed.
The die with its contained billet and its holder may be either moved forward on
the mandrel or the mandrel moved on end into the die and billet whilst it is being
revolved.
This die also so formed in halves provides a necessary arrangement of grasping
the billet at the entering end for the mandrel by two small short cod pieces inserted
into the inner surface of the die which fills the billet at this entering end, the
remaing mass of the billet operated upon and remaining unconverted into a tube
being pushed along the die until all is laid into a tube on the internal surface of
the die. This arrangement of mandrel and die serves also as an improved means
of converting hollow billets into thin tubes.
Another convenient improved arrangement of long die to be use for similar
mandrels to that just described for forming tubes directly out of solid billets or for
producing from thick tubes or "shells" thin tubes, and affording an effective and
expeditious arrangement for opening and closing the half die, particularly suitable
for forming tubes from billets of hot iron or steel, consists in having the ends of
the half dies formed in about two-fifths of a circle having planed faces, and by
temporarily fastening the half dies thus formed turned for portions of the length
of the die at the two ends to fit strong bush pedestals, the pedestals being fixed on
a sole plate corresponding in length to the die. One of the halves of the die is
fixed in the containing pedestals, the other half being left free to revolve about one
fifth part of the circle or periphery of the die, and thus partially revolved by a
lever cast on it to be actuated by hand or otherwise, the circular channel seat for
the billet to be bored out with its inner edge near to the centre of the die, and
correspondingly near and eccentric to the centre of its containing pedestals. In
this way when the actuating lever formed on the half die thus left free to revolve
or oscillate about a fifth part of the circle is depressed, the half die is opened out to
a sufficient degree for the insertion of the billet or shell, and on the lever being
raised the die is again closed and the billet firmly held together by the two con-
taining pedestals and the lever until the solid "billet" is formed by the mandrel
into a tube, or a thick tube or shell (when such are being operated upon) is
converted or drawn into a thin tube. For making tubes in this way from metal in
a heated state, a very high speed of mandrel is used. For drawing tubes in this
way in a cold state of metal, such as copper and its alloys, a slow rotative motion
of mandrel and careful lubrication of same is necessary.
Another improved form of long die also applicable for forming tubes from solid
billets, but more suitable for drawing shells or thick tubes into thin and finished
.tubes, consists of a single half long die and a roll correspondingly semicircularly
grooved, which is use to form the other containing and guiding half of the die.
By preference the long half die is placed under the roll half of the die, and the
half die placed in a sliding channel bed with an antifriction roll placed at its
underside opposite to the roll half of the die, and all placed in a strong housing.
In the two foregoing improved forms of long dies described, the tube as it
becomes formed adheres to the surface of the die, and the mass of the billet
remaining unconverted into a tube, is pushed along the channel of the die until all

page_text: is expanded into a tube; but in this modification the long under half of the die
receives the billet and is pushed forward underneath the roll half of the die, and
with the billet between the long die and roll with sufficient grasp to carry the
..billet forward over the mandrel and to form it into a tube, the rotundity of the roll
surface relieving the elongating action of the tube sufficiently to allow it to expand
over the mandrel at a greater speed than the speed at which the lower half of the
die and roll is pushed forward. The roll half of the die is preferred to be of large
diameter to produce a long holding grasp of the billet or shell and to allow of the
roll being driven by the frictional contact only of its under half die. The ram or
piston of an hydraulic cylinder is also the most suitable means for actuating this
form of long die.
An improvement in revolving dies for operating on the external surfaces of
tubes, consists in forming in them one or more flutes or grooves longitudinally
with inclined and smoothly rounded off edges presented to the metal as the die
revolves to roll the metal down each inclined smoothed off edge of a flute or
groove, making the metal flow down in a small wave before it and the metal of
the shell or thick tube operated on is laved down into a thick tube sideways as
well as on end, as the shell or thick tube is drawn or forced through the die,
which greatly increases the speed of the drawing action over that obtained by
smooth surfaced dies. The fluting also affords great advantage for more effective
lubrication than can be had with smooth continuous surface revolving dies as
hereto before used.
Another (and as regards accessibility for lubrication similar) improvement in
revolving dies to be used for drawing smooth surface tubes, consists in forming in
the acting and drawing down surface of the die one or more spiral or screw
threads and corresponding grooves with rounded inclined edges, and by drawing or
pushing through the shell or tube being drawn down at a greater or less speed
than is due to the pitch of the thread of same, or by drawing through the tube in
the reverse direction to the direction in which the screw thread would tend to
draw through the tube.
In all modes of drawing or pushing through the tube to the speed or direction
of the screw thread the advantages are obtained that the longitudinal resisting
frictional hold of the die on the tube is greatly reduced and the intervening
grooves between the threads of same provide very greatly improved means of
lubricating the acting surfaces as compared with what is obtained by the use of
continuous surface revolving or stationary dies.
It is preferred however as the most effective method of working this form of
revolving die for drawing down tubes, to push or draw the thick tube through the
dic at a slower speed than that due to the forward speed of the spiral thread or
threads of the die, the inclined and smoothed off edges of the die as they revolve
rolling or laving or "spinning" a wave of metal of the tube before it, and causing
it to flow down from a thick tube into one of a thin guage as may be required, the
action on the tube being drawn down being very similar to the overhauling of the
thread of a screw bolt by its nut. This form of die has also the advantage of
requiring less force to push or draw the tube through it, as the action of the spiral
thread of itself tends to draw through the tube. The die by preference is made
conical and widest at the acting side as required according to the proportion to
which the tube operated upon is being drawn down, and to prevent the spiral
inclined edges taking too deep a hold the threads may be made shallow to the
requisite degree suitable to the speed the metal being operated upon can be drawn
down.
One or more rounded or inclined edged threads can be formed in the die, two or
four or any number divisible by two, having the advantage of grasping the tube
on directly opposite points on the periphery. Two threads however will be
generally found the best, and the pitch should be large to allow of the requisite
speed end wise without giving a high circumferential speed on the internal surface
of the die.

page_text: Spiral dies may be constructed of metal wire or of flat or any other section of
bar twisted forward into a spiral, but round wire or flat bar is the most suitable,
and should be placed in a revolving housing, with means of drawing out or
compressing in the spiral and thereby within a small limit of diminishing or
increasing the diameter of the die. This form of revolving dies, revolved at a high
speed are very suitable for polishing or burnishing tubes.
One or more spirals may be put in a housing and two will be found for most
purposes the most suitable.
It is intended to work these fluted and spirally formed dies along with smooth
mandrels or any other ordinary form of tube mandrel.
An improved form of revolving tube mandrel consists in giving to its acting or
drawing surface or bulb a spiral form by forming on it one or more spiral threads
with inclined rounded off and smooth surfaces to act on the internal surface
of the tubes similar to that just described in connection with revolving dies.
As accuracy and uniformity of the spiral thread is not important for this
purpose such mandrels may be for some purposes formed by twisting flat or fluted,
polygonal, square or triangular steel bar according to the number of threads or
shapes of same as may be required. The bulbs or acting surfaces of these may be
formed conical or any, other ordinary form, and it is intended to work them along
with ordinary smooth stationary or revolving dies or rolls as also to use them sharp
pointed and along with long dies for drawing out or piercing solid billets into
tubes as herein before described.
In working them along with spirally cut dies it will be an advantage to
have the thread of the mandrel formed the reverse of that of the spiral of the die.
These improved dies and mandrels can be applied and used on most ordinary
forms of tube rolling and drawing benches and as is more particularly described in
my patent Specification already referred to for rolling and drawing tubes by or in
connection with revolving dies and mandrels.
An improved arrangement of drawing or rolling bench for working these
consists in a strong revolving headstock like the main headstock of an ordinary
lathe set at one end for revolving the mandrel for large size tubes with a headstock
in the centre for using the long stationary dies, and short revolving dies and
hydraulic forcing and return stroke cylinders with revolving gear for revolving the
mandrels or for revolving the dies for small size tubes at the other end of the
machine, being also illustrative of a good arrangement of housing and of
working these improved dies and mandrels for drawing rolling and finishing
tubes.
For the purpose of explaining the manner in which I carry out my invention
I append two sheets of diagrams illustrating these improved forms of revolving
inandrels and dies, and modes of working same. In describing my invention by
the aid of these diagrams I use throughout the following description the same
letters or figures or numerals in referring to like parts in order as far as possible to
avoid needless repetition in describing the various modifications shown.
"
Figure 1 is a side external elevation of a sharp pointed mandrel drawn full size
shown with its round stem A¹ broken off suitable for piercing solid billets of soft
metal and metal such as steel when heated or in a soft state. This size and forin
of mandrel is suitable for piercing billets of steel heated to a soft state into "shells"
or thick tubes suitable for being drawn down to thin guages by after drawing
processes and suitable also for being afterwards formed into gun barrels and like
articles. It is shown partly passed through a solid billet of metal B shown in
section. The form of the mandrel or acting bulb A is shown in cross section at its
largest diameter indicated by the line a, b, in figure 1, and further is shown in
cross section near its sharp point, indicated by the cross line c, d in Figure 1. The
stem or after end of the mandrel A' being shown in end external elevation along
with the billet B being pierced by figure 4.
The bulb or acting part of the mandrel A has three longitudinal grooves or flutes
shown in it and corresponding high. acting edges A2 A3 A² rounded off to displace

page_text: or lave aside the metal as it revolves instead of cutting it off as is done by a sharp
drill, these flutes being shallow at the point and made deeper in the larger diameter
of the ball, its formation in this respect being best seen by figures 2 and 3. It is
forced through the billet B by being revolved spirally and the direction of its
rotatory motion as it is forced through the metal being indicated by the arrows
placed on the bulb A and stem A¹ seen in figures 1, 2 and 3. In piercing billets
of such metals as copper, brass and tin in a cold state which for these metals this
invention is preferred to be used working at a slow spiral motion, a spiral motion
of about sixteen circumferential feet per minute generally answers best, and the
intervening flutes between the acting edges are made available for admitting or
forcing from the stem end of the mandrel oil or other lubricants to the acting or
displacing revolving rounded edges A2 A3 A3 on the bulb head A. In piercing out
billets of metal in a hot state such as in piercing billets of steel where lubricants
cannot well be used a spiral speed of about 2500 feet is most suitable in order to
keep the mandrel sufficiently cool in doing its work. Solid bodies immersed in
fluid or semi-fluid matters at a higher temperature or in contact with other solid
bodies at a higher temperature do not absorb heat so quickly when in quick
circumferential motion as when in a quiescent state, a fact or law in the diffusion
of heat so far as I am aware first observed by me quick motion being also
necessary in order to limit the duration of the contact of the mandril with the hot
metal as much as possible. The longitudinal motion of the mandril as it is spirally
revolved in the hot metal should be about a speed of 300 feet per minute.
Figure 5 is a side external elevation of a mandrel A drawn half a suitable
working size suitable for piercing solid billets of such metals as copper and alloys
of copper in a cold state. The bulb A having a small part of its body as shown
nearly parallel near its point. It is an advantage to bore in a centre hole with an
ordinary drill a short distance into the billet B at its entering end to centre in the
mandrel at starting and also at the after end as seen at B¹ in the billet B, shown
in section to keep the mandrel from breaking off portion of the metal in coming
out at the after end, and this form of mandrel bulb effects these purposes
efficiently.
Figure 6 is a cross section of the mandrel at the line α---
--bin figure 5 and
figure 7 a cross section at the line c---d in figure 5. Figure 8 is an end elevation
of the stem showing the square A³ for driving the mandrel in the clutch driver of
the working headstock of the driving machine. The same letters and figures of
reference refer to like parts as used in describing figures 1, 2 3 and 4 and the
arrows indicate the direction of its motion.
Figure 9 is an external elevation of a sharp pointed piercing mandrel A and
stem A¹ shown broken off and for similar purposes to that described in connection
with figures 1, 2, 3 and 4 but having a smooth surface in its bulb A. Figure 10
shows an end elevation of this form of mandrel from its point and figure 11 is an
elevation of the stem and billet of metal being acted upon. With great end
pressure exerted on the mandrel while it revolves this form of mandrel answers for
piercing short billets of soft metal when spirally revolved in either direction.
The same letters of reference refer to like parts as in the foregoing figures.
Figure 12 is a side elevation. Figure 13 a sectional plan and figure 14 an end
external elevation of a long die correspondingly suited mainly for holding the
billets of metal to be operated upon in a cold state by the mandrels described in
connection with the foregoing figures. The long die is formed in halves c and c¹
and bored out to a slightly larger diameter than the billet B to be operated upon,
the form and arrangement of this die being shown length wise and in section by
figure 13, and a billet B being shown placed in this die to be operated upon and a
mandrel A shown partly passed through the billet similar to that described in
connection with figures 5 to 8. Each half of this long die c and c¹ is provided
with a steel grasping dog c³ fitted into their forward ends and opposite each other
as seen in cross section in figure 14 through the line a, b in figure 14 and in
longitudinal section in Figure 13. These dogs are bored out to the same concavity

page_text: as the internal surface of the die and provided with teeth to grasp the billet B,
being made to project inwards a small distance so as to grasp the billet firmly
when the halves of the die c and c¹ are closed upon the billet, these dogs mainly
holding the billet in its position against the end pressure and action of the spirally
revolving mandrel.
Very great containing force is necessary to hold these two semi-circular long
dies c and c¹ together whilst a billet of any metal in a cold state such as a billet of
copper is being forced out into a tube by the action of the mandrel and to effect
this a strong containing channel casting D is provided by preference of steel. The
.strong side containing flanges D1 and D2 of same have a series of inclined
projections C³ projecting inwards as seen in figure 13 on each side which are
smoothly slotted out to the shape shown. The bottom of the containing channel
for the halves of this die is also planed out so as to have a straight and smooth bed
surface for the two halves c and c¹ of the die to lie on. The halves of the die
besides being planed and jointed accurately before they are bored out, are also
planed on their under sides and are provided with a series of inclined surface
projections projecting outwards c³, e corresponding to the inward projecting
inclined surfaces D³ formed on their containing block casting D seen in figure 13.
It is preferred to have these inclined edges D³ formed at an angle to the centre
line of the long die sufficiently acute as to hold the halves c and c¹ of the long die
thus formed together by the end pressure of the mandrel A as it is forced through
the billet of metal B by its frictional contact on the inclined edges D³ of the
containing block D but the halves of the die may also be further secured in their
position in their containing block D after they are closed on the billet B by the
force of the actuating hydraulic ram by inserting the blocks c, c in between the
flange D' formed on the containing block D and the forward ends of the halves of
the long die shown in elevation by the dotted lines in figure 12 and in plan in
figure 14.
In operating this long die and revolving mandrel A the mandrel may be spirally
revolved through the billet B while the billet remains at rest and the mandrel A
may be rotated only as in this example of the mode of working it shown and the
billet B in its containing long die in halves c and c¹ moved forward on the mandrel
as it is revolved to effect the spirally piercing or expanding or drawing action on
the billet. The containing die block D has formed on its base the sliding bed
flanges D, D, which are planed to the shape shown and are made to slide in the
strong bed plate castings E and E¹ having planed recesses in same as shown to
receive the planed bed flanges D' of the containing long die block D. The block D
being shown further secured in its sliding channel planed in the bed castings E
and E by the slide castings E2 and E shown in plan in figure 13 and in sectional
end elevation in figure 14 secured to the base plate castings E and E¹ by bolts, and
forming thereby a secure endwise sliding channel for the die containing block D.
These bed plates E and E¹ are shown broken off short in figure 13. In moving the
long die on end as explained the ram of a hydraulic cylinder is the most suitable
and the hydraulic ram bead F is shown connected to the block D containing the
long die c, c¹ with the billet B contained in it and the mandrel A. as it is revolved,
thus effecting the piercing and drawing action of the metal billet B as described
the motions on the mandrel ram head containing block and long die being as
indicated by the arrows placed on same. In piercing solid billets of metal oil or
other fluid lubricant is fed in over the stem A¹ of the mandrel A to its acting head
through the annular oil holder K and oil tube K¹ placed on the mandrel stem A¹
In drawing out from a shell tallow or other lubricant is filled into the hole
previous to it being placed in the die.
Figure 15 is an external elevation.
Figure 16 an external plan and figure 17 an external elevation of this form of
long die suitable for operating on metal billets in a hot state. It is placed on a
bed plate E shown in side sectional elevation in figure 15 and in sectional elevation
in figure 16. and external plan in figure 18 and shown broken off. The bed plates

page_text: for dies of this sort require to be variously shaped according to the description of
gear used to actuate the revolving mandrel; the die formed in halves c and c¹ in
this modification are shown bored out eccentrically for the billets of a nearly
semicircular form c³ and c' at each end on each half to the same length and same
diameter of neck as formed in its counter part. The central part of the half die c
is also shown of a nearly semicircular form. The other half a has formed on it the
lever piece c for being actuated to open and close the die. Both halves of the die
are placed in the strong containing pillar blocks D which are placed on the stool
casting G which is fitted on the bed plate E the half die c being secured in these
pillar blocks by the bolts D. The other half of this die c¹ having its necks c* same
as the necks of its counter part formed about three sevenths of the circumference
of its peripherry allows thereby the half die c¹ to revolve about the seventh part of
a circle as illustrated by figures 17, 18, and 19. The lever piece c³ of this half
die c¹ shown in section at its extreme end has fitted in it the adjustable joint hinge
piece c to which an actuating hand lever H is attached. This hand lever H being
keyed on an axis H' and placed in the bush pillow blocks H2 and filled in the stool
casting c. The axis of the lever H being thus left free to revolve by the lever H'.
In the centre lengthwise of this lever axis H is keyed on the cam lever H³ to
which are shown coupled by hinge pins the links H H and which are also coupled
as shown by figures 15 and 17 to the adjustable hinge piece c6 at the extremity of
the lever c³. The hand lever H; cam lever H3 and link H in the positions
illustrated in figure 17, showing the lever c raised up as high as its range will
allow and the eccentric half die c¹ closed on its counter part and the billet B
grasped by it, the position of the half dies in this state being better shown by
figure 18 in which position the billet is ready for the forward piercing or drawing
action of the revolving mandrel A. When the band lever H is raised up to the
position shown by the dotted line a ---
--b in figure 17 the centre line of the cam H³
assumes the position of the dotted line line c--- -d and top side of the lever c³ falls
down to the position indicated by the dotted line c----
--d causing the oscillating half
die c¹ to open out as shown in end elevation by figure 19 at which stage of the
process the billet has got pierced ready to be removed and a fresh one put in to be
again almost instantly closed and secured ready for the action of the spirally
revolved mandrel. In piercing steel in a hot state particularly billets of small
diameters all the operations of placing the billets in the die and of piercing or
drawing it must be quickly done to avoid the billet getting over cooled.
A guiding bore piece I shown in figures 15 and 16 guides and enters the
mandrel A into the centre of the billet B. The diameter of the mandrels for
piercing will be most effective ranging only from about half an inch to about
one inch in diameter, and made to revolve from about ten thousand to about
twenty thousand revolutions per minute; the means for reaching these high
velocities being herein after described.
Figure 20 is a side elevation figure 21 an end elevation and figure 22 a plan of a
long die of this description. Figure 20 showing the revolving mandrel A in a
billet B in section; placed between the long half die c and roll half die c¹ in the
proper position for action, the half die c being shown as being moved forward by
the hydraulic ram head F. The motions of the hydraulic ram F half die c, half die
roll c, anti-friction roll J, billet B being operated upon and revolving mandrel A
being all as indicated by the arrows placed on these several pieces. An ordinary
roll housing is suitable for this die with under bushes for the necks of the
antifriction roll J¹ and top bushes with ordinary adjusting screws for the necks c³
of the top roll. In these modifications of the long die described the seat of the
billet or shell for making gun barrels or like articles can be of an octagonal or any
other form instead of being all formed cylindrically as shown and tubular articles
thus expanded out by the action of the revolving mandrel to any external
configuration required.
Figure 23 is a side sectional elevation and figure 24 an end elevation of this
improved revolving die o shown in a position for drawing action over a billet B

page_text: One
placed on a plain mandrel A. As indicated by the arrow placed upon the mandrel.
The mandrel A is shown as being revolved in a reverse direction to the arrow on
the die c but this revolving die can also be used with advantage while the mandrel
is held stationary as mandrels are ordinarily in use in draw benches. The die is
shown with six flutes or oil channel ways formed in it c¹, c¹ and correspondingly
rounded acting edges o², c² shown between the oil or other lubricant channels.
oil channel only can be used with advantage with corresponding rounded edges, but
three channels for small diameters of tubes, suit very advantageously and one of
the acting edges may be inserted and rendered easily adjustable to various
diameters. In tubes of large diameters the revolving die is most advantageously
constructed with all the acting tube drawing down edges fitted in separately.
Figure 25 is a side sectional elevation, and figure 26 an external elevation shown
with four acting rounded off edges c², c² fitted into corresponding slots into the
body of the die shown in figure 26. These steel and hardened acting edge pieces
being formed with gab ends to keep them in their seats as seen in figure 25 suit
within certain limits a number of sizes or diameters of tubes may be formed by a
die of this construction by inserting thin lining pieces between these acting
rounded edges, and the body of the die or the acting rounded edges c², c³ can be
easily rendered adjustable by cottars or screws or other mechanical means.
Figure 27 is an end external elevation and figure 28 a sectional side elevation of
a single thread revolving die of this description with a metal billet B to be drawn
down into a thin tube shown placed over a plain surface inandrel A. figure 28
showing the form of the thread most generally suitable. The form of the thread
shown is suitable for metals of about the degree of hardness and toughness of
copper in a cold state. The acting edges of the thread or threads c², c² suits best
to be of such a degree of inclination to the surface of the "shell" or thick tube
operated upon when the thread of the revolving die is moving in the direction
which tends to draw in the "shell." It requires notwithstanding this self drawing
in action a small degree of force to feed forward the "shell" as with acute acting
edges it requires troublesome draw bench appliances to keep the billet B from
going forward with the die too quickly hard metals such as steel requiring the
keenest and most acute grasping and drawing down edges on the threads as shown
at c², cand shaped more obtusely as the metal to be drawn is softer; each
successive thread in the die becomes practically a separate successive series drawing
down dies but for most metals four successive coils or series of threads is about the
limit to obtain the greatest drawing effect whether one or four separate threads are
formed or cut in the die. The larger the diameter of the tube to be acted upon or
drawn the greater the number of separate threads can be used with advantage the
depth of the dies to produce the best drawing effect should be about equal to the
diameter of the tubes to be acted upon and the mandrel may be revolved and by
preference in the reverse direction of the die, as indicated by the arrows but it is
most suitable and advantageous to use this die over a stationary mandrel or over a
mandrel with only longitudinal motion.
Figure 29 is an end elevation and figure 30 a side sectional elevation of a
revolving die with a shell B and mandrel shown placed in it with two threads
instead of one thread as in the one just described. The same letters of reference
refer to like parts.
"
Figure 31 is a side sectional elevation and figure 32 an end elevation of a screw
die C suited for soft metals such as tin, lead, or zinc, or soft brass. The screw die C
is shown fitted on the point of a revolving hollow stem rod or die rain C, and the
billet B is cast hollow and placed over the mandrel A in a containing cylinder D.
The action of the die being a screwing down action on the billet B under great
pressure. Portion of the die at the delivering end being left unscrewed and smooth
forcing out the tube B¹ through the hollow die stem rod C.
Figure 33 is a side elevation and figure 34 an end elevation of a die of this
description formed out of a piece of steel round wire c and hardened and tempered.
In its elongated state as shown by figure 31 in which state it suits the smallest
.

page_text: diameter of tube for which it is suitable for acting upon and shown placed over a
tube B of small diameter. By compressing this spring die c until the coils of wire of
which it is composed are brought together it takes in a larger diameter of tube and
figure 35 is a side elevation and figure 36 an end elevation of the same die c thus
compressed on end and shown placed over a larger diameter of tube B. Figure 37
is a side sectional elevation and figure 38 an end elevation of a die c of this kind
formed out of a piece of flat bar and shown placed over a tube B. Figure 39 is a
side elevation of a die c of this description shown composed of two wires and
thereby having two threads and in a like way to the single threaded die within
certain limits also adjustable to any diameter of dies and round flat or any other
section of wire or bar; with one or more threads can be easily constructed in large
diameters for some purposes six or more wires or threads can be used with
advantage. Figure 40 is a side sectional clevation and figure 41 an end elevation
of a single threaded wire die of this description shown placed in a suitable housing
for adjusting the internal diameter of the die to size required, and shown placed
over a piece of tube B. The wire die itself is shown placed in conical containing
blocks D, D', and D2 composed of three pieces shown in end elevation in figure 41.
The adjusting nut D³ shown in figure 38, being removed. These three conical
separate wire die containing pieces are shown inserted into an outer correspondingly
internal conical containing housing and has a screw chased in it at its outer end
into which the screw nut D³ is fitted which is made hollow for the passage of the
tube. The other end of this housing D' is made correspondingly hollow or tubular
for the passage of the tube.
By tightening up the nut D³ as will be seen the conical blocks D, D' and D³
which do not occupy the full circumference of their seat get forced down into
their internal conical seat in the housing D' thereby compressing in the wire die
externally and reducing its internal diameter, in like manner also enlarging its
internal diameter of the die by screwing the nut D³ outwards.
Figure 42 is a side sectional elevation and figure 43 an external end elevation of
another form of adjustable containing housing for a similar spiral wire die c. In
this example; the internal diameter of the die c is smallest when the nut D³ is
furthest screwed out and largest when this nut is screwed up until the coils of the
wire come together as explained in connection with figures 33, 34, 35, and 36 the
projecting end c which is placed in the slot D', preventing thus the wire die from
running round in its housing. The third form of wire spiral die placed in this form
of housing is only suitable for light drawing floating" or polishing. The same
action will take place when the tubes B are revolved and it is part of my invention
to use this spiral wire adjusting diameter die in a stationary as well as a revolving
state.
Figure 44 is a side elevation and figure 45 an end elevation of a spiral acting
surface revolving mandrel of this kind formed with one spiral thread. A "shell" B
being shown in section over it in order to show how it takes hold of the metal and
rolls or "spins a wave of metal before it causing a thick tube or "shell" to flow
into a thin tube, each successive acting rounded off thread edge A² A* causing
portion of the metal to flow down before it; the motions are as indicated by the
arrows.
"
Figure 46 is a side elevation and figure 47 an end elevation of a similar
mandrel A with two threads A2, A². Figure 48 is a side elevation of a parallel
screw mandrel with six threads shown with a "shell" B in section placed over it
and a slotted revolving die c. as described in connection with figures 23 and 24 on
sheet one of my drawings is shown acting in the "shell" or tube externally.
Figure 50 is a side elevation and figure 51 an end elevation of a revolving screw
threaded mandrel same as described in connection with figures 44 and 45 with a
"shell" B shown in section over it and shown with the external surface of the
"shell" B rolled over the die as indicated by the arrow by the rolls c and c¹,
portion of the flanges of the grooves of the rolls being broken off to show the
mandrel in its position; the motions are as indicated by the arrows; the rolls to

page_text: be contained and driven in an ordinary roll housing. Figure 52 is a side elevation
of a two threaded screw mandrel A placed in a "shell" B shown in section and a
two threaded revolving scew die saine as described in connection with figures 29
and 30 on sheet one of my drawings on the external surface of the "shell" or tube.
The screw threads of the die being cut to the same pitch and in the reverse
direction to those of the mandrel and revolved in the reverse direction of the
mandrel A. In large size screw mandrels it is most convenient as in this example
to have the mandrel A. in a separate steel piece from the stem A¹ and fixed by a
round taper tang A³ and formed with three or more claw clutch projections A* A*
on both mandrel and stem rod to drive it round by its stem rod A¹. Figure 54 is
a side elevation and figure 55 an end elevation of a one threaded sharp pointed
piercing screw mandrel A for piercing from the solid either in connection with long
dies as described in connection with figures 12 to 19 on sheet one of my drawings
or in connection with rolls as described in connection with figures 50 and 51;
a billet partly pierced being shown in section over this form of mandrel the point
of this mandrel as shown is of the same form as the point of the mandrel described
in connection with figures 5 to 7 on sheet one of my drawings.
Figure 56 is a side elevation figure 57 a plan of an improved arrangement of
draw bench illustrating in full a good mode of actuating these improved tube dies
and mandrels.
The mandrel A shown in a position for action is as described in connection with
figures 5 to 8 on sheet one of my drawings and the long die c shown applied is as
described in connection with figures 12 to 14 on sheet one of my drawings and the
same letters of reference are used for same parts.
A strong revolving headstock L is shown applied for drawing the mandrel A
but as this is very similar to an ordinary hollow spindle lathe main headstock it is
unnecessary to describe it, other than is done by sectioning some of the parts as
shown in tigure 57. .
On the bed plate E is placed a strong hydraulic cylinder M for giving longi-
tudinal motion with great pressure to its ram F and the ram head rod F is shown
carried from the ram F to the containing block D of the long die c. The hydraulic
cylinder M is shown provided with tie rod snugs M₁, and into which are secured
the tie rods N and N¹ extending through the headstock casting at L' and L² and
through the headstock back centre bridge L³ to which they are secured as also by
separate screw nuts the headstock M itself.
As shown applied in figures 56 and 57 the headstock spindle L* gives motion to
the mandrel A and the motion of it and of the die c and hydraulic ram F are as
indicated by the arrows placed on same.
A balance weight is used for the backing stroke of the hydraulic cylinder and is
' effected through the bush crosshead M by the two chains M³, M³ which may be
attached to a separate hydraulic cylinder ram or to a balance weight or otherwise
as done for similar purposes to effect the backing motion. An improved arrange-
ment is shown for working revolving mandrels and dies chiefly in connection with
figures 58, 59 and 60 consisting in causing the hydraulic ram F to revolve the
mandrels or dies as it moves out and traverses the mandrel through the billet or
"shell" and applied to traverse the die over a mandrel whether the mandrel is
made to revolve or remains stationary. As shown applied by figures 56 and 57
for working the long die c the hydraulic ram F has only given to it longitudinal
motion but in figure 59 a hollow stem rod O is shown attached to the revolving
hydraulic ram F adapted to contain a revolving die c similar to that described in
connection with figures 23 and 24 on sheet one of my drawings, its die end having
in it a bush neck O¹ and placed in a built pedestal 0% which is fixed to the
traversing sliding die containing block D. This neck O' in the hollow stem rod O
is shown in end elevation partly in section by figure 60. To guide the out end of
⚫ the hydraulic ram F as it traverses outwards there is a neck turned on the ram
close to the driving disc on it F which works in a bush bearing M¹ formed in the
sliding crosshead M which slides in bearings formed in it on the hydraulic cylinder

page_text: tie rods N and N¹. Behind this bush bearing M¹ on the end of the hydraulic
ram F is keyed the spur cog wheel which gears into a corresponding cog wheel
pinion shown in side elevation and plan in figures 56 and 57 and in end elevation
the periphery lines of these wheels in figure 60. The driving pinion Q which is
keyed on the driving shaft R shown in figure 56 being cast with cogs as broad as
the entire length of the ram F of the hydraulic cylinder, so as to remain in gear
with the spur wheel P at any part of the stroke of the hydraulic ram F to give
rotative motion to it and to the mandrel or to the die cas in this application
shown which is of the form described in connection with figures 22 and 23 on
sheet one of my drawings having a corresponding thick "shell" placed on it to
draw down to a thin tube as there described over the long parallel mandrel A by
the die c being thus rotated in its seat in the hollow stem rod O by the ram of the
hydraulic ram cylinder F driven by the wheel gear as described. The mandrel A
may be held stationary or rotated in a reverse direction to the revolving spindle of
the lathe headstock L but thus applied a revolving headstock is not necessary.
The end form of the hydraulic cylinder and its ram F is shown in end elevation
by figure 58. This improved arrangement for rotating either a mandrel or rotating
die; fixed either directly to the end of the hydraulic ram or as in this example
shown fixed to an intervening stem rod gives greater facilities for using greater
end pressure for these processes than can by other means requiring back centre
steel bearings; the end pressure of the water on the end of the ram in the
hydraulic cylinder being nearly frictionless and any required amount of end
pressure easily obtainable combined with rotative motion in this simple way.
Figure 61 is a side elevation and figure 62 a plan of a long die same as described
and in connection with figures 15 to 19 on sheet one of my drawings shown placed
on a bed plate E along with an improved arrangement of my screw roll or
frictional screwing rolls and housings for same for driving the high speed mandrel.
In piercing billets of steel in a hot state, as already referred to a very high rotative
speed is required and for small bores of about half an inch in diameter a speed of
about from twelve to eighteen thousand revolutions per minute being necessary.
To produce this high number of revolutions per minute spirally with quick means
of starting and stopping these motions of the mandrel, cannot well be managed by
other mechanical means. These rolls S S are keyed on shafts S¹ S¹ shown broken
off and may be driven by any suitable gear; they are set in bush bearings S³, S¹
in a strong housing T as shown in figure 63 containing both these bush bearings.
The bearing S is adjustable by the gear shown for grasping firmly the stem A¹
of the mandrel to give it motion quickly and to release or stop the motion as
quickly by the gear and the hand lever U, shown. The diagrains sufficiently
explain this gear. The long die c shown is the same as that described in con-
nection with figures 15 to 19 in sheet one of my drawings and the same letters of
reference and numerals refer to like parts.
For small diameters of mandrels acting on soft metals the driving frictional
grasp of the screw rolls will give sufficient piercing force but for large sizes a
bydraulic or steam ram F analogous to the helve of a steam hammer applied as
shown to the end of the stem A¹ of the mandrel may be used to increase or assist
the forward motion of the revolving mandrel.
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
The manufacture of metal tubes from solid billets substantially in the manner
herein set forth.
And I further claim as accessories in such manufacture.
First. The arrangements of apparatus herein described for applying end pressure
to revolving mandrels employed in piercing solid billets of metal in the manufacture

page_text: Second. The employment in the manufacture of metal tubes of long dies made
in halves and adapted to open and close quickly and to withstand great internal
pressure substantially as herein described in connection with Figures 12 to 19 on
sheet 1 of the Drawings.
Third. The combination of a roll and half long die for rolling and drawing tubes,
substantially as herein described and illustrated in connection with Figures 20
to 22 of the accompanying Drawings.
Fourth. Forming the acting surface of a revolving or stationary die for use
in drawing metal tubes with flutes or indentations to provide for lubrication,
substantially as herein set forth and illustrated by Figures 23 to 26 of the
accompanying Drawings.
Fifth. Forming the acting surface of a stationary or revolving die for use
in drawing smooth surface tubes with a screw thread or threads substantially
as herein set forth and illustrated by Figures 27 to 43 of the accompanying
Drawings.
Sixth. The improved construction of mandrels for piercing solid billets in the
manufacture of metal tubes substantially as herein described.
Seventh. Forming the acting surfaces of mandrels for use in the manufacture of
metal tubes, with a screw thread or threads, for the purpose herein set forth.
Eighth. The arrangement or combination of parts forming the improved drawing
or rolling bench, for use in the manufacture of metal tubes, in which the forcing
hydraulic ram or rams are at the same time carried to revolve and produce forward
helical motion to dies or to mandrels, substantially as described.
201
3
1007