Improvements in the Process of and Apparatus for Drawing Glass Tubing.
Year: 1897

page_text: Date of Application, 17th Nov., 1897--Accepted, 18th Dec., 1897
COMPLETE SPECIFICATION.
Improvements in the Process of and Apparatus for Drawing Glass
Tubing.
I, ARTHUR HOUGHTON, Manufacturer, of Corning, in the County of Steuben,
and State of New York, one of the United States of America, 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:
In the manufacture of glass tubing as now usually carried on, and especially
in those classes thereof in which accuracy and uniformity are necessary, as in
thermometer tubing, a large proportion of the finished product is defective and
must be rejected. These defects, may be, generally speaking, divided into two
classes. The first of such classes are those which are caused by defects in the
blank from which the tube is drawn and incident to the manner in which the
blank is formed, while the second class arise in the process of drawing out
the blank into the tube. My present invention has for its object to avoid the class
of defects last named.
As is well known in the usual process of drawing glass tubing, a suitable
Blank having been formed and brought to the requisite degree of heat upon the end
of a blow iron in the hands of a workman, another workman presses a pontee iron,
having a small quantity of glass upon its end upon the free end of the blank.
The operators then move away from each other, drawing out the blank into a
tube. As in this process the tube is drawn horizontally it is subjected to gravity
acting at right angles to its axis, causing the tube to sag, whereby the finished
tube is given a curve, and the same force causes an uneven flow and distribution
of glass in the walls of the tube, resulting in inaccuracies and the loss of the
advantages sought to be obtained by perfecting the blank. Other causes of mal-
formation of the finished tube are the uneven, and irregular tension or pull
exerted by the operators in drawing and the twisting of the irons in their hands.
To avoid these deleterious results I have a process of drawing out the blanks
into tubes and a convenient apparatus for carrying out the said process, and these
form the subject matter, of this, my present application.
Referring to the accompanying drawings in which corresponding parts are
designated by corresponding marks of reference:
Figure 1 is an elevation of a device invented by me for carrying out my im-
proved process.
Figure 2 is a plan view on line x-x of Figure 1.
In carrying out my present process after the proper blank has been formed,
instead of drawing it out horizontally, I draw it out vertically, so that the tension
or strain exerted thereon, and the axis of the tube formed thereby, coincide with
the direction of gravity, whereby the injurious effects of gravity in the process
of horizontal drawing, as above stated, are obviated. I will now describe one
form of apparatus I have invented to carry out this process, and in so doing will
describe more specifically the various steps involved in the process, although it
will be obvious that other forms of apparatus may be used in carrying it out.
A frame 1 is mounted between the guides 2, motion being imparted to the frame

page_text: by any suitable actuating mechanism, such as the windlass 3 and rope 3', shown
in the drawings, and it may be stated that to obtain the best results the actuating
mechanism for the frame should be of such a character as to permit a steady and
determinate strain to be placed thereon. A suitable clamp 4 is secured upon the
frame and is adapted to hold the blow-pipe, while a fixed clamp 5 mounted on a
cross-head (which may form, as shown, the base of the guides) is adapted to hold
a pontec iron. Such being the construction, a blow pipe A, having
a heated
blank B on the lower end thereof is clamped to the frame 2, and the frame lowered
until the blank has adhered to the pontee iron Cheld in the clamp 5. The frame
is now raised and the blank drawn out into tubing. The pontee iron is then
detached from the lower end of the tube thus formed, and the tube lowered and
cut into sections of the desired length. It will be observed that there can be in
this process of forming tubes, no twisting, as the irons are firmly secured in place
before they are connected by the blank. It has been further found that the glass
of the blank, when drawn vertically, flows more evenly and retains the form of the
biank better than in the old way of drawing horizontally. This is of the greatest
importance in the manufacture of the so-called "lens-front-tubing", in which
the magnification is dependent on the thickness of the walls of the tube and the
angle formed by the front faces thereof. It is obvious that unless this uniformity
in the flow of the glass can be obtained, any attempt to regulate the shape of the
finished tubing by the shape of the blank will be wholly or in a great measure
unsuccessful. Thus by my invention, while the quality of the output is much
improved, the, cost thereof is lessened.
It is also obvious that many modifications may be made. For instance, the
frame may be lowered, instead of raised, in drawing out the tube; the pontee
iron instead of the blow pipe may be carried by the frame, and the frame may
carry a suitable receptacle, such as is indicated in dotted lines at 7, for air under
pressure, which, if desired, can be permitted to flow into the interior of the
blank while the latter is being drawn. These modifications are immaterial and
are mentioned merely to illustrate the general scope of my invention, but I do
not confine myself thereto or to any of them.
It will be seen however, in any event, irrespective of whether it be the upper
tool that is raised, or the lower tool that is drawn down, that the blank will
rest upon the lower tool, and that as the opposite tools are drawn apart the
blank will be drawn out from the central portion at a rate proportional to the
speed the tools are separated, and as each portion of the blank is reduced to
approximately the desired diameter and thickness it will harden, and this drawing
in a vertical direction at a controllable speed, whereby the liameter of the
finished tubing is regulated is an important element in my improved process, as
were the blanks merely drawn vertically by their weight alone, they would be no
way to control the drawing, and tubing of irregular shape would be produced.
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 hereinbefore described process of drawing glass tubes, which consists
in forming a hollow blank and drawing out the said blank in a vertical direction
at a controllable speed whereby the blank is drawn out into an uniform tube,
substantially as described.
2. The hereinbefore described process of forming glass tubes, which consists
in forming a hollow blank upon the end of a blow-pipe; securing the pipo
against twisting; attaching the free end of the blank to a pontee iron held against
twisting, and separating the pontee and blow pipe vertically, substantially as
described.
3. In a device for drawing glass tubes from hollow blanks, the combination
with vertical guides, of a cross head, a frame moving in the guides, the cross
head and frame being adapted to be secured to the opposite ends of the blank

page_text: and mears for moving the frame away from the cross head substantially as
described.
4. In a device for drawing glass tubes from hollow blanks the combination
with a frame and a cross head to hold the opposite ends of a blank the one
located above the other of means for moving the frame vertically and away from
the cross head substantially as described.
TONGUE & BIRKBECK,
Southampton Buildings. Chancery Lane. London. W.C.
Agents for the Applicant.