Year: 1889

page_text: Date of Application, 5th Feb., 1889
Specification Accepted, 11th May, 1389
I, EDMUND COGGSWELL CONVERSE, residing at Number 104 John Street, in the
City, County and State of New York, one of the United States of America, Gentlempr
do hereby declare th 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 tubing, its special object being to
provide a wrought iron or steel tube, suitable for pneumatic and steam boiler purposes,
as well as for hand-rails, fencing, hose and awning-poles, and other uses where a
polished tube is required.
The pneumatic tubes now in use are generally made of brass or copper, which class
of tubing is found especially applicable for such purposes on account of its smooth
surfaces, lightness and non-corrosive properties. Iron or steel tubing, though less
expensive than the brass or copper tubing could not, however, be employed for the
purpose, because its interior surface was not sufficiently smooth and it was liable to
rust or corrosion. Its weight was also objectionable, as the ordinary tube could not
be welded of plates or sheets sufficiently light for the purpose. Objection has also
been found to iron or steel tubing for steam boilers on account of its liability to rust
or corrode from the action of oxydizing waters and the rapid incrusting thereof with
the lime or other deposits from the water. The objects of my invention are to
improve the ordinary wrought iron or steel tubes so as to overcome these objections
and adapt them for uses to which they have not heretofore been considered
applicable.
To these ends my invention consists, generally stated, in coating the interior and
exterior surfaces of the iron or steel tubing with a molten metal or alloy which will
alloy with the metal of the tube, and then forcing the metal or alloy into the body
of the tube, and elongating the tube, by cold rolling or drawing the tube interiorly
and exteriorly; it being found that in so treating the tube the metal or alloy under
the drawing operation penetrates the body of the tube, filling all the surface pores
and drawing out with the body of the tube, even though a considerable elongation
thereof is obtained, so as to forin a composite or alloy with the molecules of the iron,

page_text: which will prevent corrosion, while at the same time the interior and exterior surfaces
of the tube are rendered smooth and polished, and the holy of the tube is reduced in
thickness and weight, the finished tube having all the requisites for pneumatic
tubes, etc., as above set forth, and its surface finish preventing rusting and incrustation,
so rendering it especially applicable for use in steam boilers or condensors. It also
consists in a drawn iron or soft steel tube having a soft metal or alloy compressed
into and forming a composito alloy with the molecules of the tube on the interior
and exterior surfaces thereof, such a tube being formed by the process above
described.
To enable others skilled in the art to practice my invention, I will describe the same
more fully, referring to the accompanying drawing, in which
Figure 1, is a view of the poi containing the coating metals or alloys.
Figure 2, is a side view of apparatus suitable for drawing the coated tubing.
Figure 8, is a longitudinal "section of the drawing dies and mandrel showing the
drawing operation.
Figure 4, is a like view of another form of drawing apparatus.
Figure 5, is a section of the tube before coating.
Figure 6, is a like view of the coated be, and
Figure 7, is a like view of the finished tubo.
Like letters of reference indicate like parts in each.
In practicing my invention I employ a suitable pot for melting the metals or alloys
employed in coating the pipes or tubing, a tank or pot suitable for the purpose boing
shown in Figure 1. and having a suitable furnace for heating the metal or alloy anil
maintaining it at a proper temperature for coating purposes; and the metal or alloy
being melted within said pot, and the tube to be drawn being first dipped within the
pot in such manner as to cause the molten coating metal or alloy not only to cont the
exterior surface of the tube, but to coat the interior surface thoreof, the tube being
thus conte interiorly and exteriorly with the soft metal or alloy. For the purpose
of drawing or finishing the tube I employ any suitable form of drawing hunch, such
apparatus being shown in the drawing, and having the bed or frame, a, provided at
one end with the die, b, and with suitable gripping apparatus, c, secured to the slide e
operated by the screw, d, so as to draw the tube through the die, b; while in order to
support the mandrel within the tube, the draw-bench is provided with an extension, e,
to which the rear end of the bar., is secured, the bar carrying the mandrel, g, within
the drawing die, 6; and in drawing the tube it is placed over the har, and grasped
by the gripping or drawing apparatus, and drawn through or between the die, b, and
mandrol, y. Instead of employing the die, b, a suitable pair of concave rolls, as
shown in Figure 4, may be employed, these rolls fitting closely to the body of the
tube, and compressing it upon the mandrel so as to act in the same manner as the
drawing die, b
For the purpose of coating the tube I employ a metal which will alloy with the iron
or the steel body of the tnho, at a comparatively low heat, and will also adhere thereto
under the drawing operation, it being necessary therefore to employ a soft metal or
alloy, and one which melts at such a temperature as not to injure the iron or stee!
hody of the tube. I find that load, or tin, or alloy of lead and tin, or lead, tin and
antimony, or lead, tin and bismuth, or tin and bismuth are woll adapted for the
purpose have substantially found that the metals best suited for practicing my
invention are lead and its alloys, the alloys formed with lead generally alloying with
the iron or steel body of the tube and being sufficiently soft to withstand the severe
drawing operation without flaking or peeling off, and to enter into the surface pores
of the iron or steel body, as it is elongated and by forming the composite alloy
therewith protect the metal body thereof.
In practicing my invention and forming the improved tubing, 1 generally
take wrought iron or soft steel tubing, preferring soft steel on account of its
greater capability of elongation, and in making light tube for pneumatic purposes,
1 generally employ for the smaller sizes, such as from two to three inches
in diameter, a tube of about twelve guage, this being the lightest gunge of

page_text: wrought iron or steel tubing which can be conveniently and successfully made.
1 first cleanse the tube to remove therefrom any scale or other impurities and then
wash the tube to remove the acid or like materials used in cleansing the same, the
tube being then in proper condition to receive the soft metal or alloy. I then dip
the cleansed iron tube in a solution of chloride of zinc or chloride of tin, which will
prepare the iron or make a solder for the adhesion or alloying of the soft inetal or
alloy with the surface of the iron body; these steps of the process, however, being
carried out in whatever way is proper for the coating of the tube with the particular
metal or alloy. The tube is then dipped within the inolton metal or alloy with which
it is to be coated, such as an alloy of load, tin and antimony, and in dipping care is
taken that the interior surface of the tuhe, as well as the exterior surface thereof is
properly coated, the soft metal or alloy forming an alloy with the body of the tubo,
and preparing it for the next step of the process. The tube so coated is then taken
to the drawing lench, and it is drawn thereon by any suitable mechanism which acts
to draw both the inner and outer surface of the tube; and the tube is subjected to
this drawing operation until it is considerably elongated, being passed through the
drawing dies or between the drawing rolls, and drawn over the inner mandrel a
sufficient number of times to increase its length from one-fourth to one-half; the dies
or rolls and the mandrel employed being changed as is found necessary in completing
the drawing operation. By this drawing operation, I force the soft metal or alloy
coating the exterior and interior surfaces of the tube into the surface pores thereof,
it being found that by the great pressure and friction applied to the surface of the
soft metal or alloy, as the molecules of the iron are moved under the drawing
operation, a greater affinity of the soft metal or alloy with the moleculos of the iron
is created, and the metal or alloy unites with such molecules, the coating metal being
thus carried into and caused to penetrate the body of the tube forming a composite
alloy therewith, the composite formed becoming neutral to oxydation or corrosion.
The composite surfaces formed on the tube are dense, smooth and highly polished.
At the same time all the imperfections in the body of the tube are filled by the soft
metal or alloy, and therefore a perfect surface finish to both the interior and exterior
surfaces of the tube is obtained. By the elongation of the tube in the drawing
process, I also obtain a tube which is much thinner and lighter in proportion to its
length, the tube being reduced generally, say from twelve guage to between eighteen and
twenty-four guage, and being sufficiently light for all pneumatic purposes. If
desired, where the tube is to be reduced to a very thin guage it can be redipped in
the coating metal, this redipping acting to anneal the body of the tube so as to
prepare it for the further reduction and elongation by the drawing process, and
providing the soft metals or alloys for unting with any other molecules of the iron,
which might be brought to the surface, during such second drawing of the tube,
and which might not have been previously alloyed with the soft metal, as well as to
increase the proportion of the soft metal in the composite alloy formed with the iron.
By my improved process the soft metal or alloy thus acts to incorporate itself with
the iron or steel body of the tube, and impart thereto the non-corrosive quality of
the soft meial or alloy, and where the tube is reduced to a very thin guage, the soft
metal or alloy practically penetrates through the body of the tube. It is found in
practice that by coating and drawing hoth the interior and exterior surfaces of the
tube, 1 am enabled to draw it to a inuch greater extent at each operation without
affecting its strength, as the soft metal by overcoming friction acts to maintain the
fibrous condition of the body of the tube, and also to obtain the drawing of the tube
without injury to the soft metal or alloy, as a more even frictional action is created
where it acts upon both the interior and exterior surfaces at the same time.
By the formation of the composite alloy between the soft metal and the iron body,
I obtain a tube which is not only highly polished on the interior and exterior surfaces
thereof, but substantially non-corrosive, having partaken of the nature of the soft
metal or alloy surface thereof, and which can be formed sufficiently light for use for
pneumatic purposes, and many of the uses for which brass or copper tubing has been
heretofore almost exclusively employed, and which can be produced at considerable

page_text: less cost. The tabo has also great advantages for boilor flues and condensors,
especially where the water contains any acid er alkali, as the metuls so incorporated
with the iron or steel tubo will protect it from the action of the acids on the polished
non-corrosive surface of the tube; will prevent the formation of incrustation on the
tube so that oxydation becomes impossible, and the finished surface prevents the
adhesion of any alkaline deposits.
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-
First: The herein described improvement in the art of forming tubing, consisting
in coating the interior and exterior surfaces of the tube with a molten soft metal or
alloy which will alloy with the metal of the tube, and then forcing the soft metal or
alloy into the body of the tube and elongating it by cold drawing the tube interiorly
and exteriorly, substantially as and for the purposes set forth.
composite alloy
Second: A new article of manufacture, consisting in a drawn iron or soft steel
tube, having a soft metal or alloy compressed into and forming a
with the molecules of the metal of the tube, on the interior and exterior surfaces
thereof, substantially as and for the purposes set forth.
Dadalhin 8th dan of 1024