IMPROVEMENTS IN MANUFACTURING METAL TUBES
Year: 1883

page_text: LETTERS PATENT to George Henry Fox a Citizen of the United States
residing in Boston County of Suffolk and State of Massachusetts for an
COMPLETE SPECIFICATION filed by the said George Henry Fox at the
Office of the Commissioners of Patents on the 31st August 1883.
GEORGE HENRY Fox, a citizen of the United States residing in Boston County of
Suffolk and State of Massachusetts, IMPROVEMENTS IN MANUFACTURING METAL
TUBES,"
"
This invention relates to the manufacture of tubes from strips capable of being
joined by the welding process, my invention embracing not only a tube made as
hereinafter described, but the method by which it is made and the machine for
producing it since this machine is adapted especially and solely to carry out the
manufacture of my tube.
Heretofore in the production of welded metal tubes three methods have been
practiced; in the first, the sheet of metal brought into tubular form and the edges
lapped, and then by drawing the tube with the lapped edges under a pair of rolls,
which bear upon a fixed ball, which the tube encloses, this ball in connection with
the rolls affects the union or welding of the lapped edges. In the second method
a narrow strip of metal is employed, which bent until the edges abut, is seized and
forcibly drawn through a die, slightly smaller than the diameter of the metal strip,
when bent into circular form; this squeezing process forcing the edges or buts
together and welding the same, hence called " but welded." In the third method
a narrow strip of metal is employed part of it coiled about a mandril and jumped
or welded together by hammer blows directed longitudinally of the mandril, which
settles the edges together, another portion of the strip is then coiled, heated and
hammered as before, and these operations are intermittently repeated until the
desired length of tube is obtained, which in the case of gun barrels, to which, this
method is principally adapted, is a matter of considerable time and labor.
The essential feature of my invention consists in heating, coiling and welding

page_text: of a strip of metal about a mandril until the entire tube is completed at one
operation, the strip being heated, fed to the mandril, coiled about the latter with
its edges overlapping, and hammered or compressed to effect the welding of the
joint. My invention further relates to means for temporarily isolating the joint
upon the inside of the tube from contact with the mandril until the welding is
accomplished, in order to avoid the chill of the heated strip by contact with the
periphery of the mandril, which would interfere with the welding of the parts,
as it is evident in winding the strip about the mandril, that any outside point on
the strip must remain isolated during one entire revolution before becoming an
inside point, or in other words before being touched by or united with the heated
edge to which it is to be welded; this feature in my invention consisting in
bevelling one corner of the metal strip by which the inner surface of juncture of
the strip upon itself, as the coiling about the mandril proceeds is removed from
immediate contact with the mandril, the welding process being completed before
the comparatively low temperature of the mandril can reach this point of juncture..
Or the mandril itself may be fluted or grooved peripherally or longitudinally to
reduce the area of contact surface between it and the strip to the minimum
degree.
My invention further consists in a machine adapted expressly to support the
mandril, rotate it, to coil the strip, feed it longitudinally to accommodate the
increasing length of the tube, and consolidate or compress the joint to effect the
welding of the seam, all as hereinafter described.
In my first experiment in forming a welded tube by continuously welding a
strip about a mandril, the edges of the strip were simply chamfered in order to
lap over or upon each other, the strip heated and coiled about the mandril and
pressure applied to the seam by a hammer or rolls-the edges of the "weld"
upon the inside of the tube, as a matter of necessity coming directly in contact
with the periphery of the mandril. I found that the low temperature of the
mandril was transmitted to the strip so quickly as to chill the metal and prevent
welding of the joint on its inner edge. then formed a bevel upon the inner
corner of the chamfered edge of the strip, which removed the actual point of
juncture of the lap from contact with the periphery of the mandril and my
success was completed, as the blow or pressure upon the exterior of the lap effected
the welding of the joint before the low temperature of the mandril could be
imparted to the strip sufficiently to interfere with the welding, and at the same
time forcing it clear down upon the mandril. The drawings accompanying this
specification represent in Figure 1 a view of a machine for carrying out my
invention, such view representing the mandril and part of a tube built up upon it,
while Fig. 2. is a side elevation. Figure. 3. a plan and Figure 4 an end view of
the same machine. Figure 5 is a perspective view of the movable guide or trough.
Fig. 6 is a sectional elevation of the mandril and strip of metal in process of con-
struction. Fig. 7 a horizontal section of a mandril with non conducting material
thereon. Figs. 8 and 9. detailed views of the manner of adjusting the welding
rollers.
In these drawings the machine is shown, as composed in the present instance, of
a head stock A, carrying a rotary arbor B after the manner of turning lathes, with
the exception that in addition to the ordinary standards or uprights C, D, of the
ordinary head stock I preferably add a third stradard E to support a nut to
receive a peripherally screw threaded shaft to feed the mandril as hereinafter
explained.
The mandril upon which the metal strip is coiled in the building up of a tube is
shown at F, as supported at its front end in bearings 8 in the standard C, while at
its rear end the mandril is stepped in the front end of the arbor B in such manner,
as to be readily removable from the latter, and yet compelled to revolve with the
latter, when stepped to it.
The object in this manner of connecting the mandril removably to the arbor is
to permit of interchange of mandrils of different sizes according to the diameter of
5

page_text: the tube to be formed, and also to allow of the substitution of an empty
mandril for one filled or upon which a tube has just been wound.
Moreover I pivot to the front face of the standard C, above the mandril F, a
disk or roller G, which serves to exert pressure upon the strip of metal, as it is
coiled in a welding state about the mandril. As the space between the periphery
of this roller and that of the mandril should be less than the thickness of the strip
to be welded in order to effect the welding of the metal, and as strips of varying
thickness will be employed in the manufacture of tubes of different varieties, it is
essential that the roller G be capable of being adjusted in height relatively to the
mandril.
A manner of doing this would suggest itself to any good mechanic with the
exercise of ordinary skill; as shown in the accompanying drawings the pivot of the
roller is carried by a block H sliding in ways I in the upper part of the standard C,
this block being adjusted in position by a screw J, screwing into the top of the
standard and swivelled at its upper part to the block H; as shown at H' a
suitable handle or hand wheel being added to the upper end of the screw.
In addition to the roller G, I prefer to employ additional twin rollers K K,
pivoted to the standard C below and bearing against the strip of metal in the
same vertical plane as the roller G, the object of the rolls being to provide a firm
support to the tube or mandril, and relieve the bearings in the standard C of the
strains and thrusts to which it would otherwise be subjected, as well as to smooth
the surface of the tube and more effectually complete the welding.
The rollers G, K, K, especially the roller G should stand at an obtuse angle to
the axis of the mandril, as shown in the drawings in order to travel over the seams
of the tube in a direction parallel, or practically so, to the spiral path followed by
such strip relatively to the axis of the mandril.
It is essential or very desirable that the metal strip be presented to the mandril
in a path parallel to the coils of the tube being built up upon such mandril, in
order to prevent the overiding of the strip on the one hand, or separation of the
coils on the other; on the principle of thread spooling machines, with this difference,
that while in thread spooling machines the thread guide traverses the spool, in my
case the mandril traverses the guide. To effect this I have shown at L in the
drawings a trough or guide, the effective width and depth of which corresponds to
that of the metal strip, this trough being secured adjustably to the front part of
the standard C and moving upon guides, the latter being parallel to the axis of
the mandril, in order that the axial alignment of the trough shall always be in
unison or parallel with the angle of obliquity between the mandril and the strip of
metal being wound. Its delivery end or mouth is so situated as to terminate
immediately in front of the roller G, where it is nearest to the mandril; the angle
of the trough in each instance corresponding practically, if not literally with the
pitch of the feed-screw. My object in securing the trough adjustably to its
support is that its position may be varied to adapt it to changes in the pitch of the
feed screw, and then by means of the parallel guide bars continue so to move
parallel with such pitch hence, the strip will always be run at the same angle for
any given width. In welding two surfaces, it is an essential feature that the
surface of juncture should be entirely free from "scale," and to effect and accomplish
this I have provided the edges or sides of the trough with wire brushes or cards e e,
which as the strip is fed along wipe off the scale upon the edges, as it is only this
portion which is to be brought together and welded, hence producing an entirely
clean surface just prior to the entering of the strip upon that portion of the mandril.
under the roll.
In lieu of the stationary brush or card before named, for removing scales from
the strip prior to the action of the rolls upon it, as before explained, a rotary
vibratory or reciprocating brush may be employed. To rotate and to feed, that.
is advance and retract the arbor B, and through the latter the mandril F, I cut
upon the arbor B a peripheral screw thread N, which I screw through the upper
part of the standard E, or a bushing or nut inserted in such standard, while at its

page_text: front part, this screw passes loosely through the hub O of a spur gear P, such hub
being supported in a bearing Q in the upper part of the standard D before named,
and connected with the screw N by an ordinary spline and groove connection R,
in order that the gear may put the screw in rotation, and the screw be permitted
to play longitudinally through such gear.
To put the gear P in rotation, I employ a pinion S which is pivoted to the
standard D below the said gear by a shaft T, and meshes with said gear, the shaft T
of the pinion being provided with a driving pulley U.
The front end of the arbor B is connected removably with the rear end of the
mandril in order to be readily disconnected from the latter. My object in this
being two fold, one being to replace a fresh mandril, for one that has been filled,
either of the same or different diameter, and secondly to enable the arbor to be
readily replaced by another, when a strip of one width is substituted by one of
another width, since any change in the width of the strip necessarily changes
the pitch of the spiral path described by the coils of the tube forming upon the
mandril, it being understood that the pitch of the threads of the screw correspond,
as before stated, to the pitch of the welding joint.
To produce a tube of any desired length I provide a strip of metal a of the
requisite thickness and width, and I chamfer the edges of the strip in parallel
planes, as shown at bc in Fig. 4, and I then bevel the inner corner of one edge of
the strip at an opposite angle as shown at d in Figure 6. The front end of the
heated strip is now secured to one end of the mandril and the latter put in rapid
rotation in a spiral path, the rollers or hammers operating upon the lap of the
chamfered edges of the strip to weld such lap, and the feeding of the strip and
coiling of the same about the mandril being continued until the strip is exhausted,
or a tube of the desired length obtained. The longitudinal feed motion of the
mandril keeps time with the continuous feed of the strips, in order that the lap of
such strip shall always be between the rolls.
The bevel d, as before stated, removes the inner termination of the lap from
direct contact with the mandril for reasons stated until pressure is exerted.
In lieu of the bevel d the inner side or face of the strip a may be grooved to
lessen the area in contact with the mandril, or the periphery of the mandril may
be thus grooved for a like purpose. This however would be attended with certain
disadvantages of expense and otherwise, and I prefer the bevel upon the strip. In
addition to the preliminary pressure upon the seam of the accumulating tube by the
rollers or hammers for the purpose of welding; the tube may be subject to one or
more subsequent pressures should it be found desirable so to do in order to finish
the surface. The first subsequent pressure is upon the exterior of the tube in
order to stretch the metal sufficiently to enable it to be readily removed from the
mandril. But for this pressure the tube in cooling would shrink upon the mandril
to such an extent that its removal would be difficult. In lieu of the rolls, a
hammer or hammers imparting rapid repetitive blows may be employed to compress
the metal of the tube.
Among the purposes to which my invention is especially applicable is the
manufacture of gun barrels. Heretofore these barrels have been produced by
coiling a strip about a mandril with the edges simply abutting and repeatedly
heating and hammering the accumulating coils, as herein before premised.
Another purpose to which my invention is especially applicable is the
manufacture of wrought metal couplings for steam, water and other pipes. A tube
of any desired length may be made by my system very rapidly and perfectly to be
cut up into the desired lengths for use.
In my process of making tubes, it is evident that the position of the fibre of the
material composing the same lies transversely to the axis of the tube, and by this
construction much greater strength is afforded with a given thickness of tube than
in any of the other processes before mentioned in which the fibre lies parallel with
the axis of the tube.
I do not restrict myself to the manner, herein shown, for isolating the inner edge

page_text: of the strip from direct contact with the mandril, as shown in the bevel d or the
grooving of the strip or mandril, as I consider this feature of my invention to
consist in the method of isolating the inner edge, rather than in the exact means
for effecting the result.
I also consider my invention to embrace a system of manufacturing tubes by
continuous coiling of a heated strip about a mandril with the edges of the strip
lapping upon one another, by which it is possible to produce a tube of considerable
length, or any reasonable length at one operation and in a short time. I also
consider my invention to consist in a tube composed of a spirally wound strip of
metal with its edges overlapping and welded.
In the operation of the above described machine, the strip is first properly
heated to the welding point and one end of it secured to the front or outer end of
the mandril, the latter having been previously retracted to its extreme position, as
shown in the drawings.
The machine is now put in motion, the mandril being both rotated and fed
forward by the conjoint action of the gear P and feed screw N, the result being
that the metal strip is coiled about the mandril, until the desired length of tube
has been obtained, when the machine is stopped and the tube and mandril removed.
As the edges of the strip overlap, the welding of the joint is effected by the pressure
of the rolls G K K, as before premised.
A useful application of the principle of my invention would be to encase non-
corrosive metal tubes in an envelope of wrought iron or steel. For various uses
in the arts, it is desirable to have a non-corrosive lining to a tube, which shall
possess strength and lightness. A tube may be first placed upon the mandril and
the iron or steel strip coiled and welded about it, as before explained, or the tube
itself may constitute the mandril.
For many uses it may be desirable to form a tube oval or polygonal in cross-
section, in this case a mandril of the form corresponding to the desired shape of
tube will be employed. For reinforcing cast metal ordnance or guns with a welded
steel or iron barrel my method will be practicable and effective. The steel core
after being rifled and turned off on the outside is used as a mandril, and the
wrought iron or steel strip enclosed and welded about it; then another strip is
welded on, and this process may be continued until the desired thickness is attained,
by which an immensely strong tube is built up, at a comparatively small expense
compared with casting a gun of the same size.
In lieu of coiling the metal strip directly about the mandril and isolating the
joint, as herein before described, the mandril may be first covered with a substance,
which is a slow conductor of heat, by which means the welding of the strip can be
effected before the low temperature of the mandril can be communicated to the
tube, see Figure. 7.
Another valuable application of the principle of my invention is seen in the
manufacture of pulley rims. In this case a hub cast with arms having sectional
felloes will be employed, the hub being bored and placed upon the mandril, circular
heads are then slipped upon the mandril constituting together a temporary band
and the heated strip coiled and welded about the periphery of these hubs; the hubs
are now removed and the pulley rim is complete.

page_text: the lap from the effects of the low temperature of the mandril by temporarily
isolating the inner termination of such lap from the periphery of the mandril or by
reducing the area of surface in contact between the two to a minimum point.
5th A method or system of constructing tubes, which consists in heating and
continuously coiling a metal strip about a mandril with the edges of the strip
overlapping to form a welded seain, substantially and for purposes stated.
6th A method or system of constructing tubes, which consists in heating and
continuously coiling a metal strip about a mandril with the edges of the strip
overlapping and imparting pressure to the seam, peripherally of the tube to
consolidate the metal and finish the surface of the tube both inside and out.
7th In machines for forming tubes from strips of metal a suitable frame or head
stock to support a mandril, a mandril upon which the strip is coiled, mechanism to
impart rotary motion to the mandril, and longitudinal feed motion of the said
mandril in consonance with the width of the strip.
8th In machinery for forming tubes from strips of metal a suitable frame or head
stock to support a mandril, a mandril upon which the strip is wound, mechanism
for imparting rotary motion and longitudinal feed motion to such mandril and
mechanism for applying pressure to the exterior of the lap seam, as the winding of
the strip continues substantially as stated.
9th In combination with the mandril, the roll G, and feed motion to feed the
mandril, a stationary or moving brush or card or its equivalent for removing scales
from the heated strip, substantially as and for purposes set forth.
10th In combination with the mandril F and roller G the adjustable trough or
guide A¹ moving upon ways parallel to the axis of the mandril, as and for purposes
herein before described.
11th In combination with the mandril a non conducting material surrounding said
mandril substantially as and for purposes stated.
In witness whereof I the said George Henry Fox have hereunto set my hand
and seal this 3rd day of April 1883.