Improved Process of Cold-rolling Metallic Tubes or Pipes.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improved Process of Cold-rolling Metallic Tubes or Pipes.
I, GEORGE HARKER EVERSON, of 95, Fifth Avenue, Pittsburgh, in the County of
Allegheny, and State of Pennsylvania, United States of America, Inventor, 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:
My invention relates to an improved process of cold rolling metallic tubes or
pipes and it consists in placing inside of the pipe a hardened mandrel having a less
diameter than the inside of the tube or pipe which is to be rolled and filling or partially
filling the space between the mandrel and the inside of the pipe with oil and graphite
or other lubricating material and then passing the tube with the mandrel inside of it
through suitable grooves in hard rolls, as will be more fully described hereinafter.
The object of my invention is to cold roll tubes or pipes for the purpose of
reducing them in size and thickness and increasing their elasticity and strength and to
finish and polish their outer surfaces.
Fig. 1 represents a vertical section of a machine for carrying my process into
operation.
Fig. 2 is an end view of the same.
Fig. 3 shows the finishing rolls.
I first take a tube or pipe of the required length, size and thickness and place inside
of it a hardened mandrel of slightly less diameter than the interior of the pipe and of
greater length than the length of the tube or pipe which is to be rolled.
Between the inner surface of the pipe and the outer surface of the mandrel I place
a suitable quantity of graphite and oil or any other suitable lubricant which will
prevent the pipe from adhering to the mandrel after passing through the reducing
rolls and which will permit the pipe as it is elongated to slide or move along the
mandrel without adhering to it. The mandrel must be harder than the pipe or
tube so that the shape of the mandrel will not be changed nor the mandrel lengthened
while the pipe or tube is being rolled.
With the mandrel inside of the tube and the lubricant between the tube and the
mandrel, the section of the pipe or tube is passed through a pair of grooved chilled
rolls, which compress and lengthen out the pipe about two-thirds of its circumference.
After the pipe has been passed through the rolls once, it is turned partially round
and passed through a second time so as to have that portion which was not acted
directly upon by the rolls, rolled in the same manner as the other portion.
The grooves in the reducing rolls being wider or of greater diameter at the sides
where the edges of the rolls meet than at those points where the rolls come in contact
with the pipe for the purpose of reducing it, the opposite sides of the pipe are
made to expand or bulge out as shown in Fig. 2.
The pipe in passing through the rolls besides having its thickness decreased, is
lengthened and has its elasticity and strength increased, and the rolls polish and
finish the outer surface of the pipe better than if it had been passed through a
polishing machine.
Another advantage gained is that the pipe or tube after being thus rolled has its
thickness or diameter made uniform from one end to the other, thus adapting the tubes
for use wherever an elastic tube is required or one which has an even uniform diameter
from end to end or where a finely polished surface is needed.
After the tube and the mandrel have been passed a suitable number of times
through the grooved rolls so as to reduce the pipe to the desired thickness, the
mandrel is removed from the pipe and then the pipe is passed without the mandrel
through rolls having perfectly round grooves in them, as shown in Fig. 3.

page_text: 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
1. The process hereindescribed of cold-rolling metal tubes or pipes, consisting in
placing inside of the tube a mandrel of slightly less diameter than the interior of
the pipe or tube, placing a suitable lubricant between the mandrel and the pipe
and then passing the pipe and the mandrel through a pair of grooved rolls so as
to reduce the diameter of the pipe or tube and elongate it, at the same time that
the surface of the tube is polished and finished, substantially as described.
2. The process hereindescribed of cold-rolling metal tubes or pipes, consisting in
first placing inside of the tube a mandrel of greater length than the tube, placing a
suitable lubricant between the tube and the mandrel, then passing the tube with
the mandrel placed inside of it a suitable number of times through a pair of grooved
reducing rolls, and then finishing the pipe by passing without the mandrel through a
pair of rolls provided with a round groove, substantially as specified.
Dated this 10th day of June 1800
W. P. THOMPSON & BOULT,
Agents for the Applicant.