Improvements in the Manufacture of Tubes and other Hollow Cylinders.
Year: 1892

page_text: Date of Application, 30th June, 1892
Complete Specification Left, 1st May, 1893-Accepted, 29th July, 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Tubes and other Hollow
Cylinders.
A
I GEORGE HOOKHAM of Nos. 7 & 8 New Bartholomew Street Birmingham
Manufacturer do hereby declare the nature of this invention to be as follows:-
In manufacturing tubes according to my invention, I may commence with a solid
block of metal using the process described & claimed in the Complete Specification
of Letters Patent granted to me & numbered 4039". This block of metal may
be a casting & in the manufacture of cartridge-cases wd. ordinarily be cast from
Muntz metal, but it may be made from any metal that can be worked hot. When,
however, my object is to produce a tube open at both ends the original casting
may itself be a short thick tube, the diameter of whose bore may be about twice
the thickness of the sides. This short tube is placed in a die open at both ends, as
described in my before-mentioned Specification, but in this case the die is tapered
inwards and constricted at its lower opening. The short tube is made hot and
placed in the die, its lower end resting upon the constricted part of the die.
hard steel mandrill longer than the tube is placed in it, its lower end projecting
through the die, & its upper surface being level with the upper surface of the tube.
A hammer or ram closely fitting the bore of the die is introduced from above, and
drives the mandrill & tube together through the constriction of the die thus
elongating the tube till the ram rests upon the constricted part of the die. The
mandrill & tube may now be seized from below & the remaining portion of the
tube drawn clear of the die. The mandrill shd. be slightly taper from top to
bottom. I thus obtain a tube from 2 to 3 times the length of the original tube, &
of about the same internal bore. This tube may be further elongated by the
ordinary process of hot-rolling, but, as one of my principal objects is to avoid the
pickling processes usually employed, I prefer to work the metal cold from this
A hardened steel
point. My next process is accordingly, a swaging process.
mandrill is placed between the swaging tools, the hard mandrill being a little
longer than the operating faces of the swaging tools, & having a stem at least as
long as the tube to be forged. The swaging tools have about the curvature that the
tube is desired to have when swaged down, being eased out at the parts first operating
on the tube, & also at the sides. As the swaging tools reciprocate the tube is
drawn forward between them, being also rotated through a given angle at each
movement forwards. The rotations shd. be all in the same direction: the mandrill
or plug is stationary ; & the movements of the tube take place when the swaging
dies are not pressing. When the length of the tube has again been about doubled by
this means, the tube is annealed, preferably in a reducing furnace, or only made
black-hot, so as produce little scale. The tube is again subjected to suitable
swaging tools & further elongated & reduced in thickness. In fact by properly
shaping the faces of successive dies tubes may be finished by this process. For
the final process, however, I prefer to employ a ball- or roller-tool with lateral
adjustment similar in general construction to the ball-bearing of a bicycle.
Although in some cases, and especially for very thin tubes, balls will give a good
result, yet I find that for all purposes rollers properly shaped are preferable, and that
they have also a much wider application. Roughly speaking steel tubes whose
sides do not exceed in thickness one fifteenth part of the diameter of the tube may
be drawn down to thinner gauges and smaller diameters & left smooth and polished
by rollers, if certain precautions are observed. For example the advancing angle
of the tapered cylindrical roller shd. not much exceed 7°, otherwise a burr is likely
to be thrown up in advance of the tool, wh. when rolled-in produces a bad surface.

page_text: If too many rollers are employed the tube is set tight on the mandrill wh. is with
difficulty removed (though this objection may be overcome by using a fixed mandrill
or plug); if too. few, the metal of the tube "loops" between each pair of balls and
is damaged by the repeated bendings, besides that the tube no longer fits the
mandrill & is not truly cylindrical. The proper number of rollers may generally
be found by the rule that the distance between the points of pressure of any two
adjacent rollers shd. not be more than about 8 times the thickness of the tube, nor
less than about 4 times that thickness. No exact rule can, however, be given only
the general rule that if the tube gets too loose on the mandrill the number of
rollers shd. be increased & vice versa. I prefer rollers generally cylindrical in form
but tapered both ways at the part operating on the tube. The extremities are
truncated cones of, say, 45°. These cones run on hollow cones similar to the cones of
the ball-bearing of a bicycle. The rollers are, preferably, kept in their relative
positions by steel pins passing through their axes, & running in bearings in a
phosphor-bronze cage. It is advantageous to reverse the direction of rotation of
the tool at each successive draw; I may even use a reciprocating instead of a
rotating motion. If flaws occur on the surface, I may grind the surface before the
final or polishing draw. For leaving the surface polished the part of each roller
last operating on the tube shd. be rounded to a very long radius, & the roller itself
highly polished. Instead of the process first described in wh. I start with a block
or a short tube of metal, I may start with a disc; but instead of drawing the disc
through a fixed die in the usual manner, the die consists of a ring of balls or rollers.
The disc is carried through the ring of balls or rollers by a rotating punch, in
conjunction preferably with a pressure plate also rotating at the same rate as the
punch, the punch & the pressure plate carrying the disc through with them.
use a ring of balls I may prepare the disc by stamping it at its periphery with a
rim shaped to fit the balls, the pressure-plate being shaped to fit this rim on its
upper surface.
Instead of the swaging tools I may use one or more pairs of rollers
grooved to the curve to wh. it is required to reduce the tube, such grooves being
eased at the sides as in the case of the swaging dies. These rollers roll along the
inner surface of a very strong steel tube, the rollers, except at the grooved parts,
being accurately shaped to fit the inner surface of the said tube. Each pair of
rollers are kept in their relative positions by a cage wh. runs loosely through the
tube. Instead of the tube I may use a pair of rails wh. fit the grooves in the
rollers. The tube or rails are about half as long as the tube to be operated on.
When I desire to produce tubes with thinned or thickened portions or of other than
uniform section, I reduce portions of the tube by swaging, cross-rolling, draw-
rolling or other similar means. As an example of such tubes I may instance
boiler-tubes with thickened ends. When I desire to work the metal to a greater
extent than is provided for in the above-described processes, I may place the tube
upon a mandrill & roll it hot between longitudinal rolls.
Dated this 20th day of June 1902
If I
GEORGE HOOKHAM.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Tubes and other Hollow
Cylinders.
I, GEORGE HOOKHAM, of 7 New Bartholomew Street, in the City of Birmingham,
Manufacturer, 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 the manufacture of tubes and other hollow cylinders and
it is also applicable to tubes such as cartridge cases closed at one end.
"
The object of the invention is to dispense in great measure with the rolling and

page_text: drawing processes at present in use in tube manufacture and to replace these
processes by others which tend to compress and improve the character of the metal
treated as to strength and ductility rather than to extend and weaken the metal as
is the case with existing drawing processes.
One object of my invention is to dispense with rolling and so treat the metal,
cast steel, brass, Muntz metal or other metal that the said metal is sufficiently
worked in one of the tube forming processes to be either drawn down or otherwise
extended after that process.
One part of my invention consists in forcing or squirting heated metal by means
of an enclosing die and punch to work the said metal and transform it from the cast
to the wrought or rolled condition without the operation of working or rolling while
simultaneously performing the first step in the process of manufacturing the metal
into a tube whether closed at one end or not.
Another part of my invention consists in a process of swaging which process
displaces the ordinary process of extending by drawing through dies.
Another part of my invention relates to the mechanical appliances for carrying
the swaging process into effect.
Another part of my invention relates to a combination of roller drawing with the
hereinbefore described processes to finish and further toughen the tube or cylinder
and when desired to produce a polished surface.
Referring to the accompanying sheets of drawings:-
Figure 1 shows in section a steel squirting or forcing die with punch and mandril
ready for action on a hot thick tube contained in it.
Figure 2 shows in section the short thick tube squirted or forced into a longer
and thinner tube.
Figure 3 is a longitudinal section illustrating my swaging process.
Figure 4 is an end elevation and section corresponding to Figure 3.
Figures 4 and 4B are respectively end view and longitudinal section of my
Swaging tools on a larger scale than that of Figures 3 and 4.
Figure 5 shows in end elevation and section a device for roller swaging or
drawing.
Figure 6 is a longitudinal section corresponding to Figure 5.
Figure 7 is a section similar to Figure 6 but showing the rollers and cage in
elevation.
Figure 7 shows in transverse section a modification of the arrangement illustrated
at Figures 5, 6 and 7.
Figure 8 illustrates diagrammatically a process of cup drawing by means of a
ball bearing die.
Figure 9 is similar to Figure 8 but shows the plate or disc to be operated on as
cupped over the balls before the main cupping operation.
Figures 10 and 11 are sections illustrating the squirting or forcing operation as
applied to metal for cartridge cases.
Figure 12 shows a tube thinned at the centre and left thick at the ends.
Figure 10 illustrates the positions before squirting and Figure 11 shows what
occurs by squirting or forcing.
In manufacturing tubes according to my invention I may commence with a
solid block of metal using the process described and claimed in the Complete
Specification of a Patent granted to me and numbered 4039 of 1891. The block
of metal is marked 1 in Figures 1 and 2 of that Specification. This block of
of metal may be a casting, and in the manufacture of cartridge cases would
ordinarily be cast from Muntz metal, but it may be made from any metal that
can be worked hot. When however, my object is to produce a tube open at
both ends the original casting may itself be a short thick tube.
thick tube as A Figure 1 is heated to the required temperature and is placed
in a die B which die is open at both ends as described in my before mentione.l
Specification, but in this case the die is tapered inwards and constricted at its
lower opening as shown at B' Figures 1 and 2. The tube A is placed in the
This short

page_text: die so that its lower end rests upon the constricted part marked B₁ of the die B.
A hard steel mandril D, longer than the tube is placed in it, its lower end
projecting through the die and preferably guided by passing through a hole in
a cap or guide plate F slipped into a recess in the die. The upper end of the
mandril is preferably expanded to conical form as shown at E and a projection
loosely enters the punch, hammer or ram C. The punch, hammer or ram C
closely fits the bore of the die and is introduced from above and actuated by
hammer, mechanism, or a hydraulic ram. It drives the mandril D and tube A
through the constriction B¹ of the die B thus elongating the tube, till the punch,
hammer or ram C rests upon the said constricted part. The change produced
by the operation of squirting is clearly shown at Figure 2 where A¹ is the
extended tube. The ram C is now raised and the tube and mandril taken out
and the mandril drawn clear of the tube. To facilitate the extraction of the
mandril it may be slightly tapered. The guide plate F is pushed off the die as
the metal advances through the constriction and it serves to keep the mandril
in central position till the metal fills the aperture B₁ when no further guiding is
required. By this process obtain a tube about twice the length of the original
tube more or less according to the proportions of the die and constricted part
as required by the nature of the metal operated on. The tube is about the
same internal bore as the original tube. This tube may be further elongated
by the ordinary process of hot rolling; but as one of my objects is to avoid the
pickling processes usually employed I prefer to work the metal cold from this
point. My next process is accordingly a swaging process forming another part
of my invention.
A hardened steel mandril G (see Figures 3 and 4) having a stem G₁ is placed
between swaging tools H H the hard mandril G being sometimes a little longer
than the operating faces of the swaging tools and having a stem G at least as
long as the tube A¹ to be forged or swaged.
The swaging tools have about the curvature that the tube is desired to have when
swaged down, being eased out at the parts first operating on the tube and also at
the sides. This is shown at Figures 44 and 4 where suitable swaging tools are
drawn to a larger scale in end view and longitudinal section respectively, the
points a a are the points where the tools are eased away.
As the swaging tools reciprocate the tube A' is forced forward between them
and is at the same time rotated through a given angle at each movement forwards.
The rotations should be all in the same direction. The mandril or plug G is held
stationary and the movements of the tube are arranged to take place when the
swaging dies are not pressing.
The forward advance and the partial rotation of the tube may be effected by any
known form of mechanical feed or gripper.
The length of the tube is increased by the action of the reciprocating tools H H
and the tube of thicker walls and larger internal diameter A' is extended and
its walls thinned while the internal diameter is decreased as shown at A. That
is a short thick tube entering the swaging tools passes over the mandril and is
formed into a longer tube of thinner walls and of less internal diameter if desired.
The conical mandril shown at G Figure 3 is adapted for reducing the internal
diameter of the tube as well as thinning its walls. When I desire to retain the
bore of the same diameter as that of the thicker tube A' I arrange the mandril G
as a parallel mandril and thus although I extend the part of the tube A' into the
longer tube AI do so by thinning the walls only. In this case 1 modify my
swaging tools H H to suit a parallel mandril G. In some cases I prefer to dispense
with the taper mandril shown at Figures 3 and 4 even when I desire to reduce the
internal diameter of the tube. The arrangement of mandril G and swaging
tools H H which I prefer for this purpose is shown at Figure 4. The tube A is
larger in internal diameter than the parallel mandril G and the swaging tools are
shaped as indicated to first reduce the internal diameter to that of the mandril and
then to reduce the thickness.

page_text: It is to be understood that the swaging tools are reciprocated in a powerful
machine adapted to supply the required pressure.
When the length of the tube has been about doubled by this means the tube is
annealed, preferably in a reducing furnace or made only black hot, so as tɔ produce
little scale.
The tube is again subjected to suitable swaging tools as hereinbefore described
and further elongated and reduced in thickness. In fact, by properly shaping
the faces of successive dies tubes may be finished by this process.
For the final process however, I prefer to employ a ball or roller tool similar to
that described in my Specification No. 16811 of 1891. Although in some cases and
especially for very thin tubes balls will give a good result yet I find that for all
purposes rollers properly shaped are preferable and that they have also a much wider
application. Roughly speaking, steel tubes whose sides do not exceed in thickness
one fifteenth part of the diameter of the tube may be drawn down to thinner gauges
and smaller diameters and left smooth and polished by rollers if certain precautions
be observed. For example, the advancing angle of the tapered cylindrical roller
should not much exceed 7°, otherwise a burr is liable to be thrown up in advance of
the tool which when rolled in produces a bad surface. If too many rollers are
employed the tube is set tight on the mandril which is with difficulty removed,
though this objection may be overcome by using a fixed mandril or plug. If too
few, the metal of the tube "loops" between each pair of rollers and is damaged by
the repeated bending, besides that the tube no longer fits the mandril and is not
truly cylindrical. The proper number of rollers may generally be found by the
rule that the distance between the points of pressure of any two adjacent rollers
should not be more than about eight times the thickness of the tube or less than
about four times that thickness. No exact rule can, however, be given; only the
general rule that if the tube gets too loose on the mandril the number of rollers
should be increased vice versa. I prefer rollers generally cylindrical in form but
tapered both ways at the part operating on the tube. The extremities are truncated
cones of say 45°; these cones run on hollow cones similar to the cones of the ball
bearings of a bicycle. The rollers are preferably kept in their relative positions by
steel pins on their ends running in bearings in a phosphor bronze cage.
It is
advantageous to reverse the direction of rotation of the tool at each successive
draw,' I may even use a reciprocating instead of a rotating motion. If flaws
occur on the surface I may grind the surface before the final or polishing draw.
For leaving the surface polished the part of each roller last operating on the tube
should be rounded to a very long radius and the roller itself highly polished.
Instead of the process first described in which I start with a block or a short
tube of metal, I may start with a disc and the mechanical arrangements for the
production of this disc forms another part of my invention. Those arrangements
are illustrated at Figures 89 and 10 of the drawings. Instead of drawing the disc
through a fixed die in the usual manner, according to my invention the die consists
of a ring of balls K or rollers. The disc M is carried through the ring of balls
or rollers K by a rotating punch I rotating say in the direction of the arrow and
preferably having in conjunction with it a pressure plate J pressing on the plate M
and rotating at the same rate and in the same direction as the punch. The punch
and the pressure plate thus rotate the disc with them and the plate is forced
through the ring of balls K with a smaller expenditure of work and with the
production of a deeper draw than is possible with ordinary appliances. The ring
of balls or rollers K is held in a convenient die L, the balls being constrained to
move in a suitable groove arranged as in ball bearings.
When use a ring of balls, I may prepare the disc M by stamping it at its
periphery into a rim shaped to fit the balls K. This is shown at M Figure 9 and
When I
the pressure plate J is shaped to fit the curved rim as there indicated.
have produced a sufficiently deep cup or sufficiently long tube with a closed end by
the herein before described ball or roller drawing process, I may continue as before
with the swaging process and complete with the roller finishing process.

page_text: Instead of the swaging tools hereinbefore described and illustrated at Figures 3,
4, 4 and 4 of the drawings, I may use one or more pairs of rollers as N Ni
grooved as at N2 N3 to the curve to which it is required to reduce the tube (see
Figures 5, 6 and 7) (such grooves N N³ being eased at the sides as in the case of
the swaging dies). These rollers N N¹ roll along the inner surface of a very
strong steel tube O; the rollers except at the grooved parts N2 N³ being
accurately shaped to fit the inner surface of the said tube O. Each pair of
rollers N N is kept in position by a cage as P (Figures 5, 6 and 7) which runs
loosely through the tube. In Figures 5 and 6 the cage P is clearly shown the two
halves P P being connected together by bars or bolts P¹ P1 P2 P². The curved
surfaces of the rollers N N are clearly shown as fitting the interior of the strong
steel tube O at Figure 5.
Instead of the tube OI may use a pair of rails O O¹ Figure 7 which fit the
grooves in the rollers N N'. In this case the rollers may be cylindrical as shown
and the cage may be suspended on turned pins.
The tube or rails are about half as long as the tube to be operated on.
In this type of roller swaging as I prefer to call it the tube A is preferably
drawn through the tube O and the rollers N N' and the tube O is held stationary.
A second pair of rollers may be caused to operate. on the tube A2 after the
operation of the first pair and the axis of said second pair I preferably arrange at
or near right angles to the axis of the first pair so that the grooves operate on that
part of the tube which is not acted on by the first pair.
By passing my tube through a suitable series of such rollers or passing any
required number of times through successive pairs of rollers with diminishing
dimensions of grooves I am enabled to draw down my tube to the determined size.
The said roller drawing or swaging process may be used to finish the tube
produced in the main by my reciprocating swaging tools.
In applying my hot process of metal forcing or squirting to the manufacture of
cartridge cases I place a cast heated block A (see Figures 10 and 11) in a die B
and force into it a plunger or punch C by a blow, hydraulic pressure or other
means. The plunger C I reduce in diameter as shown at C¹ and on applying a
sufficient pressure a cup A¹ (Figure 11) is formed and the cast, disc A passes from
the cast to the wrought condition without the, operation of rolling. The cup A'
is extracted by suitable means and it forms the first stage of the various drawing
processes which are required to produce the finished cartridge case. The die B
is cleared away as shown at Q Q to reduce the friction of the displaced metal as it
moves upwards.
For the formation of cartridge cases by this method any metal or alloy such as
Muntz metal may be used which can be heated to a sufficient extent to be squirted
or forced as described. It is to be understood that when steel is to be treated as
herein before described it is to be heated as highly as it is safe without deteriorating
or burning the metal. The same remark applies to Muntz metal and other copper
alloys.
The punch or plunger C may be made of self hardening steel and the mandril D
Figures 1 and 2 is also preferably made of self hardening steel.
When I desire to produce tubes with thinned or thickened portions or other than
uniform section I reduce portions of the tube by swaging, draw rolling otherwise
termed roller swaging, roller dies, or other similar means. As an example of such
tubes I may instance boiler tubes with thickened ends.
Such a tube is illustrated at Figure 12 of the drawings. The parts A¹ A¹ at
the ends are left of the original thickness and the intermediate length A reduced
in thickness as hereinbefore described by the reciprocating swaging arrangements
by the roller swaging device, or other similar means. For this purpose the tools
are operated within the limits of the intermediate piece A²
When I desire to work the metal to a greater extent than is provided for in
the above described processes, I may place the tube upon a mandril and roll it hot
between longitudinal rolls.

page_text: 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. In the manufacture of tubes and like articles, the process of squirting or
forcing hot metal through a die or round a plunger to form a longer from a shorter
tube or a cup from a disc or shallow cup blank; the said process being arranged
to work the metal sufficiently to transform cast metal so treated to the wrought
metal state without rolling or when a wrought metal blank is used to improve
greatly the wrought quality of the metal so that preliminary rolling or working
may be entirely dispensed with or minimised substantially as hereinbefore
described.
2. In the manufacture of tubes and like articles, an arrangement for squirting or
forcing hot metal comprising--a die open at both ends but having a tapered con-
stricted opening at one end; a mandril passing through the centre of the said dio ;
a plunger punch or ram fitting the die and carrying the mandril before it, the
plunger being operated in the die together with the mandril to force or squirt hot
metal substantially as hereinbefore described.
3. The arrangement of die B, punch or plunger C, mandril D with or without a
conical top E operating on a hot tubular piece A as and for the purposes
herein before described with reference to Figures 1 and 2 of the accompanying
drawings.
4. The arrangement of die B, plunger C C' operating on a hot cylindrical or a
cup blank as A for producing a cup to be used in the manufacture of a cartridge
case or like tubular article as herein before described with reference to Figures 10
and 11 of the accompanying drawings.
5. In the manufacture of tubes and like articles the process of swaging down in
the cold a shorter thick tube to a longer thinner tube either with or without a
mandril or plug substantially as hereinbefore described.
6. In the manufacture of tubes and like articles, an arrangement for swaging
down a tube comprising-swaging tools as H H' acting on a tube having within it
a hard mandril when the thickness of the tube is to be reduced or without a
mandril when the diameter only is to be reduced; together with feeding and
gripping mechanism substantially as hereinbefore described.
7. In the manufacture of tubes and like articles a roller drawing or swaging
device consisting of rollers acting within a strong tube or other guide having a
similar function, the said rollers being suitably grooved substantially as hereinbefore
described reference being had to Figures 5, 6, 7, 7A of the drawings.
8. In the manufacture of tubes with thick portions reducing the thickness of the
metal in the desired parts by cold swaging or other cold process substantially as
hereinbefore described.
Dated this 29th day of April 1893.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicant.