Improved Means for Forming Screw-threads.
Year: 1899

page_text: [Date of Application, 18th Jan., 1899
Complete Specification Left, 18th Sept., 1899-Accepted, 11th Nov., 1899
PROVIDIUNAL DE DUIVATIONA.
Improved Means for Forming Screw-threads.
I, SALOMON FRANK, of No. 4, Blücherplatz, Frankfort-on-the-Main, in the
German Empire, Engineer, do hereby declare the nature of this invention to be
as follows:
Hitherto screw threads have been cut by means of leading screws and suitable
cutters or tools in lathes or screw-cutting machines. In such articles, for
example, as the caps and necks of preserve-tins, it has been attempted to impress
screw-threads in the metal by means of a pressing tool. The object of this inven-
tion is to provide tubes or other hollow cylindrical articles with either inner
or outer screw-threads, by forcing a matrix or die of corresponding shape into
the tube or the like or forcing the tube or the like into a matrix or die.
For instance in forming an outer screw-thread one extremity of the tube is
first reduced somewhat in width by means of a draw plate, so that it will readily
fit in a matrix having the desired screw-thread formed in its interior. When
a die or mandril is pressed into the part of the tube inserted into the matrix or
die, the thickness of such mandril or die being equal to the clear width or
diameter of the tube, the metal of the tube to be threaded will be thereby caused to
take an impression of the inner screw-thread of the matrix. The tube thus
provided with the necessary screw-thread, is then unscrewed from out of the
matrix.
A tube can be provided with an internal screw-thread by first slightly enlarging
the tube at one end so that an externally threaded mandril or die can be inserted
into it. The core-portion of the said mandril or die is equal, in diameter, to the
interior of the tube. When the enlarged end of the tube, and the mandril or die
are forced through a matrix the size of the outer diameter of the tube, the metal
of the tube will be pressed into the thread of the mandril or die so that the
required screw-thread is formed in the tube end and the die or mandril is then
screwed out of it.
In forming an inner screw-thread in a cap or lid, the lid is first slightly
enlarged at its edge, so as to be capable of accurately accommodating a screw-
threaded mandril or die, and the said cap or lid is then placed upon a matrix of
corresponding shape and forced into it in the same way as has been described with
reference to forming an internal thread in a tube end. The cap or lid, thus
tapped, is then screwed off the die.
100
1
T
1000

page_text: in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
Hitherto screw threads have been cut by means of leading screws, and suitable
cutters or tools, in lathes or screw-cutting machines, and in some articles such,
for example, as the caps and necks of preserve tins, attempts have been made to
impress screw-threads in the metal by means of pressing tools. The object of
this invention is to provide tubes or other hollow cylindrical articles with screw-
threads on the exterior by forcing the tube or the like into a screw-threaded
matrix or die, or in the interior, by forcing a matrix or die of corresponding
shape into the tube or the like.
I will describe my invention with reference to the accompanying drawings of
which Figure 1 illustrates the means according to my invention for forming a
screw thread on the exterior of one end of. a tube or tubular article, Figure 2
shews an arrangement for forming a screw thread in the interior of a tube and
Figure 3 shews an arrangement for forming a screw thread in a metal cap or
cover.
To form a screw thread on the exterior of one end of a tube the end of the tube to be
screw threaded is first reduced somewhat in diameter as shewn in Figure 1 by means
of a draw plate or other suitable means, so that it will readily enter a matrix a
having in its interior a screw thread corresponding to that to be formed on the tube.
The part of the tube to be screw threaded is inserted into the matrix or die a
and into the end of the tube is pressed a mandrel c the diameter of which mandrel
corresponds in diameter to the interior of the tube b, so that the metal of the
portion of the tube. to be screw threaded will be forced into, and caused to take
an impression of, the inner screw thread of the matrix a. The tube is thus
provided with the necessary screw-thread, and is then unscrewed from the matrix.
To form an internal screw-thread in the end of a tube, the end to be screw-
threaded is first slightly enlarged as shewn in Figure 2 so that an externally
screw-threaded portion of a mandrel or die c¹ of greater diameter than the tube
can be inserted into it. The portion of the mandrel c' which is not screw-
threaded, corresponds in diameter to the interior of the tube. When the mandrel
or die is inserted in the enlarged end of the tube & the said enlarged end together
with the mandrel or die is forced through a matrix a¹, the aperture of which is
equal in diameter to the outer diameter of the tube whereby the metal of the
tube will be pressed into the thread of the mandrel or die c and the required
screw-thread is formed in the tube end, the die or mandrel e being then screwed
out of it.
To form an internal screw-thread in a cap or lid, a screw-threaded mandrel or
die, corresponding to the screw-thread on the vessel to which the cap or lid is to
be applied, is inserted in the cap, Figure 3, which is of such internal diameter
to readily admit the said screwed mandrel 2. The cap, together with the mandrel,
is then forced into a matrix a² of corresponding diameter to the exterior of the
finished cap or lid so that the metal of the cap will be pressed into the screw-
thread on the mandrel c and thus form, as described with reference to Figure 2,
a corresponding internal screw-thread in the cap, which is then screwed from
the said mandrel.
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
1. Forming a screw thread on the exterior of the end of a tube or tubular
article by inserting the end on which the screw thread is to be formed, into a
matrix or die having an internal screw thread corresponding to the thread to be
formed on the tube, and then forcing a mandrel into the said end of the tube so
as to press the metal of the tube into the screw thread in the matrix substan-
tially as herein before described.

page_text: -2-Forming a screw thread in the exterior of a tube or tubular article, by-
inserting in the tube or tubular article a mandrel or die having thereon a screw
thread corresponding to the screw thread to be formed in the tube or tubular
article, and then forcing the tube or tubular article together with the mandrel
or die into or through a matrix so as to press the metal of the tube or tubular
article into the screw thread on the mandrel or die substantially as herein before
described.
Dated this 18th day of September 1899.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.