IMPROVE- MENTS IN THE MANUFACTURE OF COPPER AND OTHER METALLIC TUBES AND IN APPARATUS EMPLOYED IN THE SAID MANUFACTURE”
Year: 1883

page_text: LETTERS PATENT to Thomas Budworth Sharp of French Walls Smethwick
in the County of Stafford Mechanical Engineer for an Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF COPPER AND OTHER METALLIC TUBES AND IN
APPARATUS EMPLOYED IN THE SAID MANUFACTURE”
PROVISIONAL SPECIFICATION left by the said Thomas Budworth Sharp at
the Office of the Commissioners of Patents on the 30th January 1883.
THOMAS BUDWORTH SHARP of French Walls Smethwick in the County of
Stafford Mechanical Engineer "IMPROVEMENTS IN THE MANUFACTURE OF COPPER
AND OTHER METALLIC TUBES AND IN APPARATUS EMPLOYED IN THE SAID
MANUFACTURE"
In the ordinary method of manufacturing copper and other metallic tubes a thick
hollow cylinder is reduced in diameter and elongated by a succession of drawing
through dies or a draw plate having a series of taper or conical holes progressively
decreasing in diameter.
The exterior of the tube is reduced in diameter by the die or draw plate while
the interior of the tube is supported by a cylindrical or nearly cylindrical mandril
which travels with the tube or the interior of the tube is supported at the point
where the drawing takes place by a bulb on the end of a long rod the said bulb
being fixed by means of the said rod in the "eye" of the die or draw plate.
In manufacturing copper and other metallic tubes according to my invention I
dispense with the cylindrical mandril and bulbed rod referred to and I employ in
their place a detached or loose plug preferably of the kind hereinafter described.
The fore part of this plug is of the diameter which it is intended the interior of
the tube shall have after the drawing process while the rear part of the plug is of
Jarger diameter preferably of a diameter not less than that it is intended the
exterior of the tube shall have after the drawing process that is of a diameter not
less than that of the narrowest end of the hole in the die or draw plate.
The fore end of the tube to be drawn down is reduced in the ordinary way so
that it will pass through the drawing hole; the plug is then introduced into the
CD 277

page_text: tube its smaller end foremost. The plug having been pushed up to the draw plate
the tube is drawn in the ordinary way through the drawing hole
The plug stations itself by the motion of the tube at the "eye" of the draw
plate that is at the place where the drawing is effected the metal being drawn
between the hole in the draw plate or die and the said plug. The small diameter
of the drawing hole between which and the rear part of the plug the tube under
operation is situated prevents the advance of the plug; and between the plug thus
self fixed and the drawing hole, the reduction of the external and internal
diameters of the tube as well as the reduction of the thickness of the metal of the
tube takes place.
short cylinder of
The self fixing plug which I prefer to use consists of
hardened steel the fore end of which is of less diameter than the rear part the
junction of the two parts having a convex shoulder upon which shoulder the
drawing mainly takes place. The plug may however be varied in shape within
considerable limits. A spherical or nearly spherical plug or a conical plug may be
used with nearly the same effect as the plug described provided the proper relation
between the size of the acting parts of the sphere or cone and the acting part of
the hole in the draw plate or die be preserved. I prefer to make the holes in the
draw plate or die of a trumpet shape but holes of the ordinary shape may be
employed

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Budworth Sharp in the Great Seal Patent Office on
the 21st July 1883.
THOMAS BUDWORTH SHARP of French Walls, Smethwick, in the County of
Stafford, Mechanical Engineer "IMPROVEMENTS IN THE MANUFACTURE OF COPPER
AND OTHER METALLIC TUBES AND IN APPARATUS EMPLOYED IN THE SAID
MANUFACTURE"
In the ordinary method of manufacturing copper and other metallic tubes n
thick hollow cylinder is reduced in diameter and elongated by a succession of
drawing through dies or a draw plate having a series of taper or conical holes
progressively decreasing in diameter.
The exterior of the tube is reduced in diameter by the die or draw plate while
the interior of the tube is supported by a cylindrical or nearly cylindrical mandril
which travels with the tube, or the interior of the tube is supported at the point
where the drawing takes place by a bulb on the end of a long rod the said bulb
being fixed by means of the said rod in the "eye" of the die or draw plate.
In manufacturing copper and other metallic tubes according to my invention I
dispense with the cylindrical mandril and bulbed rod referred to and I employ in
their place a detached or loose plug preferably of the kind hereinafter described.
The fore part of this plug is of the diameter which it is intended the interior of the
tube shall have after the drawing process while the rear part of the said plug is of
larger diameter preferably of a diameter not less than that it is intended the
exterior of the tube shall have after the drawing process, that is, of a diameter not
less than that of the narrowest end of the hole in the die or draw plate.
The fore end of the tube to be drawn down is reduced in the ordinary way so
that it will pass through the drawing hole the plug is then introduced into the
tube its smaller end foremost. The plug having been pushed up to the draw plate
the tube is drawn in the ordinary way through the drawing hole.
The plug stations itself by the motion of the tube at the "eye" of the draw
plate, that is, at the place where the drawing is effected, the metal being drawn
between the hole in the draw plate or die and the said plug. The small
diameter of the drawing hole between which and the rear part of the plug the
tube under operation is situated prevents the advance of the plug and between the
plug thus self fixed and the drawing hole the reduction of the external and
internal diameters of the tube as well as the reduction of the thickness of the
metal of the tube takes place.
The self fixing plug which I prefer to use consists of a short cylinder of
hardened steel the fore end of which is of less diameter than the rear part the
junction of the two parts having a convex shoulder upon which shoulder the
drawing mainly takes place. The plug may however be varied in shape within
considerable limits. A spherical or nearly spherical plug, or a conical plug may be
used with nearly the same effect as the plug described provided the proper relation
between the size of the acting parts of the sphere or cone and the acting part of
the hole in the draw plate or die be preserved. I prefer to make the holes in the
draw plate or die of a trumpet shape but holes of the ordinary shape may be
employed.

page_text: I will now proceed to describe with reference to the accompanying Drawings the
manner in which toy invention is to be performed.
Figure 1 represents partly in longitudinal section and partly in elevation the
apparatus I employ in carrying into effect my improvements in the manufacture
of copper and other metallic tubes, the said apparatus being represented in con-
junction with a metallic tube in (course of manufacture; a is die or draw plate
which may be of the ordinary kind. In place of the fixed bulbed rod or cylindrical
mandril ordinarily employed, I use a detached or loose plug b, b². The fore part b²
of the plug b, 62 has the diameter which it is intended the interior of the tube c, c²
shall have after the drawing process. The rear part b of the plug b, b' is of larger
diameter than the fore part 6 the rear part b being preferably of a diameter not
less than that of the exterior of the tube c, c² after drawing, that is, of a diameter
not less than that of the narrowest part of the hole in the die or draw plate a.
The fore end of the tube whose diameter and thickness of metal is to be reduced
is drawn down or contracted in the ordinary way so that it will pass through the
hole in the die or draw plate a. The plug b, b2 is then introduced into the tube
and pushed up to the contracted end of the tube, the smaller part b² of the plug
occupying the said contracted end of the tube and the shoulder at the junction
of the two parts b, 62 of the plug seating itself upon the shoulder formed by the
contraction of the tube. The contracted end of the tube being passed through the
hole in the draw plate a the tube is drawn by the ordinary appliances through
the hole in the draw plate. By the motion of the tube c, c² the plug b, b2 stations
itself at the eye of the die or draw plate a, that is, at the place where the drawing
is effected the diameter of the tube and the thickness of the metal being reduced
between the shoulder at the junction of the parts b, b2 of the plug and the entrance
The plug b, b
to and narrow part of the hole in the said die or draw plate a.
becomes self fixed and retains its position during the drawing of the whole length
of the tube.
In some cases it is desirable to expand the tube being operated upon before
contracting it.
This method of operating is illustrated in longitudinal section in Figure 2 where
a is the die or draw plate and b, b, ba is the self fixing plug. In this case, the
plug is a cylinder b having conical ends 62, 63 and the manner in which the tube
c, c², ca is operated upon by the shoulder of the conical end 63 and the hole in the
die or draw plate a will be understood from the description hereinbefore given
with reference to Figure 1. As the tube Figure 2 is drawn through the die or
draw plate a that part of it in which the cylindrical part b of the plug b, b², b³ is
situated is increased in diameter at c³ Figure 2 before it is reduced to the diameter
and thickness shown at c Figure 2.
In order to introduce the plug b, 63, 63 into the tube to be operated upon the
fore end of the tube is slit or divided longitudinally preferably at three places as
represented at & in cross section in Figure 3 and side elevation in Figure 4. By
this slitting of the tube, the plug b, 62, 63 can be introduced, the three parts into
which the end of the tube has been divided separating as the plug is forced into
the split tube. The plug b, 62, 63 having been introduced into the tube c the split
end of the tube is so far contracted as to permit it to pass through the hole in the
die or draw plate a. The draw bar e is then inserted in that part of the tube
which has been passed through the draw plate and the extreme end c' of the tube
is next contracted by driving the ring or collar f up to the head e² of the draw
bar e.
The drawing of the tube is then conducted in the ordinary way and
progresses in the manner herein before described and represented in Figure 2.
By this method of manufacture different thicknesses of metal inay be given to
different parts of the tube under operation. For example if as illustrated in
Figure 2. a ring or draw plate g be placed upon the tube c having a hole or eye
of larger diameter than the part c of the tube but of less diameter than the part c
of the tube and if the said ring or draw plate g be stationed at the position

page_text: indicated in dotted lines at g2 Figure 2 the external diameter of the tube will be:
diminished as the expanded part c. passes through the ring or draw plate at g².
As the final external diameter of the tube is determined by the size of the hole.
or eye in the die or draw plate a the tube after this treatment while having the
same external diameter as it would have had if the ring or draw plate g had not,
been employed, the thickness of the metal in the tube produced is less than it
would have been if drawn without the said ring or draw plate g. Thus, by the
method of manufacture described a tube may be produced having throughout its
whole length the same external diameter but having at any desired parts a greater
or less internal diameter according as the drawing is effected with or without the
draw plate g the internal diameter being greatest when the draw plate g is used
and least when the drawing is effected without the said draw plate g.
Figure 5 represents in longitudinal section a tube of this kind the ends having
a greater thickness of metal or of less internal diameter than the other portion
of the tube. Tubes of this kind are useful for locomotive and other boilers and
for all purposes where greater strength is required in one part of the tube than in
another.
From the description given it will be understood that the additional thickness
of metal or diminished internal diameter may be given to any part of the tube.
Figure 6 represents in longitudinal section a modification of the manufacture
and apparatus represented in Figure 2.
In this modification the plug h, h² has a nearly spherical head the portion h²
being cylindrical.
The action of the modification Figure 6 is essentially the same as that described
with reference to Figures 2 and 4 and may be employed for similar purpose, that is,
for producing tubes having different thicknesses of metal at different parts.
I wish it however to be understood that the method of manufacture described
with reference to Figures 2. 4 and 6 may be employed with advantage to produce
tubes having the same internal and external diameter throughout, the expansion
of the tube before its contraction disclosing any defect in the tube being operated
upon and the issue of defective tubes into commerce is thus avoided.
The plug b, 63, 63 Figure 2, may have a cylindrical termination at the end
entering the draw plate similar to the end 62 of the plug b, 62 Figure 1. In all
cases where the plug has a cylindrical termination the interior of the tube operated
upon is planished or made smooth by the said cylindrical termination excepting in
those cases in which the ring g is employed. In such cases there is no planishing
of the interior of the tube.
Having now described the nature of my invention and the manner in which
the same is to be performed I wish it to be understood that I claim as my
invention of "Improvements in the manufacture of copper and other metallic tubes
"and in apparatus employed in the said manufacture"
First The use in conjunction with a die or draw plate in the manufacture of
copper and other metallic tubes of a detached self fixing plug in place of the
cylindrical mandril or fixed bulbed rod ordinarily employed the said detached
self fixing plug having such size and configuration that it stations itself in the eye
or hole of the die or draw plate and effects the drawing of the tube between itself
and the said eye or hole of the die or draw plate substantially as hereinbefore
described and illustrated in the accompanying Drawings.
Secondly The modification of the said detached self fixing plug herein before
described and illustrated in the accompanying Drawings, whereby the tube under
operation is first expanded before it is drawn down or reduced for the purpose and
substantially as described and illustrated.
Thirdly--The modification of the said detached self fixing plug herein before
described and illustrated in the accompanying Drawings for the purpose explained
in the preceding claim in conjunction with a ring or additional draw plate or die

page_text: whereby a greater or less internal diameter can at pleasure be given to the tube
under operation while the same external diameter is preserved substantially as
hereinbefore described and illustrated in the accompanying Drawings.
In witness whereof I the said Thomas Budworth Sharp have hereunto set
my hand and seal this-Eleventh-day of July in the year of our Lord one
thousand eight hundred and eighty three.
Witness, RICHARD SKERRETT
37 Temple Street
Birmingham.
THOMAS, BUDWORTH. SHARP. (L.S.)