An Improved Method of Forming Tubes for Gun Barrels and the like.
Year: 1888

page_text: Date of Application, 25th June, 1888
Specification Accepted, 17th Aug., 1888
COMPLISTE SPECIFICATION.
An Improved Method of Forming Tubes for Gun Barrels and
the like.
I, LOUIS GATHMANN, of the City of Chicago, County of Cook, and State of
Illinois, United States of America, 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:-
This invention relates to an improved method of forming tubes of considerable
length, such for example as gun barrels, cannon etc., from spirally coiled plates.
I have found in the attempted construction of such tubes of considerable length
from a continuous spiral coil reduced to a proper thinness to secure an effective
distribution of the grain in the curved direction of the coil, that the welding of the
contiguous surfaces of the laminae of the coil at a distance from the end or ends of
the tube is not readily effected by any blow or pressure which it is practicable to apply.
I have therefore devised the improved method of forming such tubes herein set forth.
My said improved method consists in first forming short coils or those containing few
laminae or leaves, and welding each of these separately, thus forming a thick slug as
an intermediate product and thereafter heating and welding two, three or other small
number of theso slugs together to form longer slugs or short tubes and finally adding
other slugs thereto by welding until a tube of the required length is built up. In
this manner the weld is made perfect between all the adjacent laminae or layers of the
coil and between the adjacent slugs so that the entire tube, when completed, no matter
what its length, will have perfect union between all its original elements and will be
of equal strength longitudinally at all points.
In the accompanying drawings I have illustrated the metal strip in its original
condition as a bar; its sectional form after its reduction to a thin and relatively broad,
straight plate; an open or unwelded, short spiral coil formed by curving the straight
plate edgewise; the disk formed by welding the short spiral or coiled strip; a larger
slug formed by the welding of several smaller ones, and, lastly, a tube of considerable
length formed by welding numerous slugs together one after another.
Figure 1 represents, in transverse section, a bar of wrought iron or steel from which
a spiral is to be made.

page_text: Figure 2 is a transverse section of a strip formed by rolling or drawing the original
bar shown in Figure 1 to greater breadth and less thickness.
Figure 3 is a side view of the rolled or drawn strip shown in section in Figure 2.
Figure 4 is a side view of a short coil formed from the strip shown in Figures 2
und 3.
Figure 5 is a top or end view of the short coil shown in Figure 4.
Figure 6 is a side view of a slug formed by welding together the contiguons leaves
or laminae of the short coil of Figure 4.
Figure 7 is a central section of the slug shown in Figuro 5.
Figure 8 is a larger slug or short section of inbing formed by welding together a
plurality of the slugs shown in Figures 5 and 6.
Figure 9 is a longer tube formed by welding together a series of slugs like those
shown in Figures 6 and 7 but of unequal diameters externally, as will be done in the
construction of a cannon by the method herein set forth.
A is the original har of metal; B is the straight, flat and thin strip formed
by rolling or drawing down the har À; C is a relatively short spiral coil formed from
the strip B; D is a slug formed by welding together the laminae of the short coil (';
E is a larger sing or short tube formed by welding together several slugs D, and F is
a tube of considerable length, here shown as of proper length to form a cannon and
also shown as having been formed of slugs of unequal diameter.
The object had in view in making tubes of coiled strips is to secure an arrangement
of the "grain" or fibre of the metal in a transverse diruction around the axis of tho
tube so that the latter is adapted to resist great bursting strain. To produce a reliable
product, however, it is necessary that a perfect welding shall be effected between all tho
contiguous surfaces of the coil throughout the whole length of the tube. I have found
that this result cannot be attained by end blows or pressure in an attempt to unite a great
many laminae or the leaves of a long coil at one time so as to mako a tube of considerable
length, as for example, one long enough to form a gun barrel or cannon. First, in
henting a coil of considerable length and constituted of thin leaves, some portion of the coil
will be too highly heated while another portion or portions may be not hot enough to
properly weld, and secondly an end blow or prossure will not communicato its force to
all points in the tube, and leaves intermediate to the ends of the coil will not be
perfectly welded. I have therefore been led to make the present invention which, as
herein-before stated, consists in first forming short soctions of coil, each preferably
embracing, say, about 10 leaves of about 1-4th inch in thickness or, say, 20 leaves
1-8th inch thick each, heating this short coil to the proper welding condition and
welding its leaves together so as to produce a thorough organic union thereof. This
gives an apertured solid disc or slug, illustrated in Figures 6 and 7. Having in this
manner made such a number of the slugs D as will, when welded together, faco to
face, produce a tube of the required length, as for example, a cannon (which is
illustrated partly made in Figure 9), the slugs are heated and placed one upon another
preferably to the number of two only in the first instance, and theso are weldad
together by proper blows or forco applied in the usual manner of welding pieces of
motal of corresponding dimensions. In placing the slugs together in position to be
welled, caro is taken to bring the holes in the slugs into coincidenco with oach other, 4
which may be done by the preliminary introduction of a short motal bar of suitable
dinmetor. To the two or three slugs thus united another is soparately wolde, or
possibly two or other limited number of slugs may be added to the pile at a single
well, depending upon the thickness of the slugs. In this manner a tubo of any
desired longth is built up and when finished there is perfect organic union between 5
all of its original parts and the tube will have uniform longitudinal strength through-
out its entire length.
In tho construction of cannon or other tubes which require to be of greater diameter
at one point in their length than at another, slugs D of unequal diameter may be first
formed as described and theso welded together to form a tube of the external contour
required, as illustrated in Figure 9.
The purpose of making tubus of coiled strips being to secure the distribution of the

page_text: fibres longthwise of the strips and in a circular course about the axis of the tube, and
the most complete lengthwise arrangement of the fibres being accomplished by
repeated rollings or drawings of the metal forming the strips, it is manifest that the
thinner the strips or leaves of the coils are made from an original bar of given
dimensions the greater will be the resisting power of the finished tube to bursting
strain. But the thinner the leaves the greater the number of joints and the greater
the liability to defective union of the leaves. By the method of first forming slugs of
short coils, and then uniting the slugs, as herein set forth, perfect union can be mado
between the leaves, no matter how thin they may be, and it is therefore practicable by
this method to make coiled tubes of greater strength than have heretofore been
known.
The tube so made, or the spirals or the slugs before being welded, or the strip or
bar before forming the spiral therefrom, may be subjected to any special treatment
desired for the purpose of imparting greater tenacity or other quality to the metal,
without departure from my invention.
For cannon a continuous tube of ordinary construction but of selected quality of
motal will commonly be inserted in the coiled tube described.
A tube made from a spiral coil is not of my invention.
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 :—
1. The method of constructing metal tubes from coiled strips or plates which
consists in soparately welding the leaves of short coils to form slugs and then suc-
cessively welding the slugs together to build up a tube of the required longth.
2. The method of constructing metal tubes of great latoral and longitudinal
strength, which consists in reducing a metal bar to extreme relative thinness by
repeated drawings or rollings; then forming short coils from such thin strips; then
separately welding the leaves of such short coils to form separate discs or slugs, and
finally successively welding the slugs together to form a tubo of the desired length.
Dates
HOME WAS RIGH
LOUIS GATHMANN.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.