Improvements in Metal Tube, and Machinery for Producing the same.
Year: 1896

page_text: Date of Application, 7th Apr., 1896
Complete Specification Left, 30th Dec., 1896-Accepted, 27th Mar., 1897
PROVISIONAL SPECIFICATION.
Improvements in Metal Tube, and Machinery for Producing the
same.
I THOMAS SPENCER JAMES 172 Camden Grove Peckham S.E. Engineer do hereby
declare the nature of this invention to be as follows:-
From a strip or strips of metal, an interlocked lapped spirally seamed tube is
formed; such seam or seams, being raised on the outside, or sunk into the internal
part of the tube, or made flush as desired; the strip or strips of metal, are forced
onto & rolled round a suitably shaped mandrel or mandrels, & various tools & rollers
are brought into use to form the joint; & so from the flat strip or strips, either by
one machine or several machines is produced the locked, lapped, & (as desired) the
compressed, or raised, or flush spiral seam firm & solid, without brazing soldering or
other & similar means; such spirally formed seam or seams imparts great strength
to the tube; the tube may afterwards be formed. into any desired section & I may
sometimes form the ends of the tube with screw threads.
The mandrel, which is supported by two hollow headstocks, one fast, & one
travelling, on a bed or foundation, receives rotary motion & for the compressed locked,
lapped spiral seam has a spiral channel formed around it & into this channel &
around the man Irel the strip or strips of metal which are suitably shaped as to
section are caused & forced. to wind. & during the operation of winding, the seam is
partially formed, being completed & compressed by various rollers & other tools; the
mandrel while rotating is also gradually caused to pass through one headstock & this
completes the operation, bringing the tube to a finished and an equal diameter.
For the raised locked lapped seam a plain mandrel. only is necessary, but for the
flush seam, a combination of the two styles of mandrels are requisite, the operations
are however precisely similar to that described.
Dated this 7th day of April 1896.
COMPLETE. SPECIFICATION.
Improvements in Metal Tube, and Machinery for Producing the
same..
I, THOMAS SPENCER JAMES, of 172 Camden Grove, Peckham, in the County of
Surrey, Engineer, do hereby declare the nature of this invention and in what.
manner the same is to be performed to. he particularly described and ascertained
in and by the following statement :-
My invention relates to an improved manufacture of that description of metal
tubes in which a strip of metal has its two edges bent up into a book-shape and is
then coiled helically round a mandrel so that the hooked edges engage with cach
other, such engaged parts being then subject to pressure so as to be flattened down

page_text: upon each other, producing a folded lap joint such as indicated at Fig. 1 of the
accompanying drawing.
With this joint it will be seen that the only security against the joint becoming
loosened is afforded by the shoulder formed at a on the one edge a, and consequently,
if the tubes are made of comparatively thin metal the joint will easily give way to any
considerable strain to which the tube may be subjected.
According to my present invention 1 effectually prevent any such loosening of
joints of this kind by producing what I term a "locked lapped joint."
For this purpose the one edge of the strip of metal is provided in addition to the
hook a, with a hollow ridge b, as shewn in the cross section of the strip at Fig. 2,
so that when the hook a has been engaged with the hook a¹ on the contiguous edge
of the previous turn of the strip as at Fig. 3, and these are then subjected to pressure
so as to be flattened down, in the manner to be presently described, the ridge b,
which remains standing during the first part of the operation, in being then flattened
down over the joint so formed, as shewn at Fig. 4, and at Figs. 5 and 13, will
effectually lock the joint formed by the parts a and a' and prevent it from loosening
or giving way, and it will at the same time afford considerably greater strength and
stiffness to the tube by reason of the increased depth of the helical rib thus
produced.
This joint may either be formed so as to project on the outside of the tube, as at
Fig. 4, or it may project on the inner surface of the tube as at Figs. 5 and 13, so as
to leave the outer surface smooth, the one arrangement or the other being adopted
according to the purposes to which the tube is to be applied. In the first named
case, the tube is formed on a smooth mandrel, and in the latter it is formed on a
grooved mandrel, as at Figs. 6 and 7.
Or again the joint may be made to project partly on the outer side and partly on
the inner side according to the depth of the mandrel groove in relation to the
thickness of the joint.
When a tubular structure of increased strength is required, a tube having the
helical joint projecting externally may be fitted into a tube having the joint formed
internally, the former being fitted into the latter by a screwing motion.
Instead of forming the tube of a single helically wound strip, it may be made of
two or more helical strips, coiled like a multiple threaded screw. Or again, a tube
may be formed of a strip having the section at Fig. 2, bent round in a circle so that
the hooked edge a engages with the hooked edge a¹ on the other side so as to form a
straight longitudinal locked lapped joint of the kind described, or two or more such
strips may be bent into semicircular or arc form and have their hooked edges
engaged with each other so as to produce a tube with two or more such locked
lapped joints.
I will now describe by way of example one mode of forming a tube according to
my invention by means of a single helically coiled strip, the locked lapped joint
being made to project internally leaving the outer surface smooth as shewn at
Fig. 5.
Fig. 6 shews a side elevation of a machine which may be employed for the
purpose;
Fig. 7 shews an enlarged diagraminatic plan of a series of rollers suitable for
forming the locked lapped joint, and Figs. 8 to 13 shew the several stages of this
during the process of manufacture.
The machine is similar in its general construction to an ordinary lathe, A A are
fixed head stocks with hinged tops, through which passes the mandrel B the rear
end of which fits in a socket on the end of a revolving shaft C carried in the sliding
headstock D and receiving rotary motion from the shaft E through gearing F, the
shaft E being formed with a screw thread working through threaded bushes on the
headstock D, so that at the same time that the mandrel is rotated, it is also advanced.
Between the headstocks A'A is a bracket G, carrying six adjustable pressing rollers
H H³, H3, H, H, H and H' by the consecutive action of which upon the hook-
shaped edges of the strip, the before described locked lapped joint is formed.
For

page_text: this purpose the metal strip, which has been previously brought by suitable rolls to
the form shewn in cross section at Fig. 2, has its front end attached in any
suitable manner to the mandrel B such as by bending down the end thereof and
inserting it into a slot in the mandrel, whereupon on the rotation of the mandrel in
the direction of the arrow, the strip will first be led under the roller H¹ H³, the
groove H of which will fit the edge having the hook a and ridge b, while the
groove H will fit the edge a¹.
This roller will consequently press the strip down on the mandrel: as the strip
travels round with the latter, the edge ab will be brought under roller H2 which
simply has the effect of straightening up the hook a so as to bring it into the form
shewn at Fig. 8.
On the strip. continuing its travel, its edge a meets the edge a' of the
following turn of the strip, as it passes under the groove H³ of the first roller,
which consequently presses the two edges together to a certain extent, as shown at
Fig. 9. The edges thus engaged then pass on to roller H, the sloping side face of
which has the effect of partly pressing down the hooks a a' as shewn at Fig. 10; on
the joint then passing under roller H³, this more or less completely flattens down the
hooks a a' as at Fig. 11, still leaving the ridge b standing; the joint is now brought
under the roller H the sloping face of which partly presses down the ridge over
the hooks, which are thereby also completely flattened down, as at Fig. 12, and
finally the joint is brought under the roller H', which completely flattens down the
ridge b on to the hooks, and compresses the completed joint in the groove of the
mandrel, as at Fig. 13, the outer surface of the tube then presenting a smooth surface
as at Figure 5. When the mandrel B has been advanced to the extent of its full
stroke, the front end of the formed length of tube is disconnected from it, and the
rotation of the mandrel and travel of the headstocks D are reversed whereby the
mandrel will be screwed backward out of the formed length of the tube, after which
the above described operation may be continued for producing a tube of any desired
length.
If desired the above described locked lapped joint can be still further strengthened
by the introduction of a wire either into hooked edge a or into the ridge b, as
iudicated at c c Fig. 3.
It is to be understood that I do not limit myself to the above described mode of
producing the locked lapped joint, as this only serves as an example of the way in
which the invention may be carried out. The arrangement of the rollers H¹ to H
shewn at Fig. 7 is only diagrammatic, as they would of course be arranged in oblique
positions corresponding to the helical position of the strip.
It will be evident that instead of first producing the metal strip of the section
described with reference to Fig. 2, by a separate machine, the machine for producing
the described locked lapped joint, may be combined with suitable rolls for forming a
flat strip into the desired section, as it is fed forward to the jointing rollers.
Having now particularly described and ascertained the nature of this 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 from a helically coiled strip of metal, the method
of producing a locked lapped joint by first engaging with each other the contiguous
hook shaped edges of two coils of the strip and then pressing down a projecting
ridge, formed on the one edge, so as to lap over the engaged hook shaped parts and
thus to lock them firmly together substantially as described.
2. The use for the manufacture of tubes from metal strips with helical locked lapped
joints such as are referred to in the preceding claim, of a metal strip having at the one
side a book shaped edge such as a, and a ridge such as b, and on the other side a hook
shaped edge such as a', adapted to hook into the edge a substantially as described
with reference to Fig. 2 of the drawings.
3. A locked lapped tube joint, consisting of the combination of two hook-shaped
edges a a' engaged with and folded down upon each other, and a ridge b formed

page_text: behind the edge a and folded down over the edge a¹ so that this is locked between the
said ridge and the edge a, substantially as described with reference to Figs. 4, 5
and 13 of the drawings.
4. The production of the locked lapped joint such as is referred to in the preceding
claims, by means of a revolving mandrel and pressing rollers, so formed and combined
as first to flatten down the engaged hook shaped edges of a spirally coiled strip and
then to fold down the projecting ridge over the folded joint so formed substantially
as described.
Dated this 30th day of December 1896
ABEL & IMRAY,
Agents for the Applicant.