IM- PROVEMENTS IN APPARATUS FOR CUTTING SCREW THREADS ON METAL PIPES OR TUBES
Year: 1878

page_text: LETTERS PATENT to Henry Harris Lake, of the Office of Haseltine, Lake, &
Co., Patent Agents, Southampton Buildings, London, for the Invention of "IM-
PROVEMENTS IN APPARATUS FOR CUTTING SCREW THREADS ON METAL PIPES
OR TUBES." A communication from abroad by Frank Armstrong, of Bridge-
port, Connecticut, United States of America.
Sealed the 18th February 1879, in pursuance of an Order of the Lord Chancellor,
and dated the 24th July 1878
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 24th July 1878.
HENRY HARRIS LAKE, of the Office of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN APPARATUS FOR CUTTING
SCREW THREADS ON METAL PIPES OR TUBES." [A communication from abroad
by Frank Armstrong, of Bridgeport, Connecticut, United States of America.]
This Invention relates to improvements in apparatus for cutting screw threads on
metal pipes or tubes, and is designed chiefly for cutting the threads on gas and
steam pipes or tubes.
'
The said Invention comprises two separate or independent dies, which are fitted
in a recess or recesses in a metal plate by being boxed or halved thereto and bolted
fast, so that they can be readily taken out by removing the bolts or the nuts.
Provision is thereby made for more readily removing them for changing and
sharpening than can be done with the ordinary divided dies. The dies have slotted
holes for the passage of bolts by which they are fastened to the plate or holder to
allow them to be adjusted to suit the size of the pipe or tube to be cut.
The said Invention also comprises screws for adjusting the dies, these screws
being fitted in hollow projecting arms (one at each end of the plate) which are also
jointed near the said plate, and the detachable portions have a socket in the end
to receive the projecting shank of the said screws when screwing into the portion
formed on the plate.

page_text: The said plate is recessed for half its thickness to receive the dies, and the dies
are also recessed or halved a little back of the cutting end to fit in the said recess
flush with the surface, and they are bolted fast by bolts, the holes for the bolts
being slotted to allow them to be adjusted to centre with a guide which is formed
together with the plate. This guide projects at right angles from the plate, and is
made to receive detachable bushes, through which the end of the pipe or tube passes
to the dies, being secured therein by a set screw.
The said adjusting screws screw in through the plate from the said arms, which
are made in detachable parts which screw together, and the detachable portions
have each a socket to make room for the projecting shank of the said screws, to
which a wrench is applied for turning them.
These adjusting screws provide means for accurately adjusting the dies to the
dimension of the tube when the latter is placed between them.
The dies are bevelled on the outer corners, so that they may be sharpened by
grinding off the said corners.
These dies may be very simply and cheaply made in the form required for con-
necting them to the plate in this manner by stamping them in dies.
The solid die plate is recessed a little deeper in the middle portion than in the
other part to make room for the thicker portion of the dies.
The apparatus may be attached to any suitable machine for similar purposes, and
may be worked by hand or other power.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Harris Lake in the Great Seal Patent Office on the 18th
February 1879.
HENRY HARRIS LAKE, of the Office of Haseltine, Lake, & Co., Patent Agents, 2
Southampton Buildings, London. "IMPROVEMENTS IN APPARATUS FOR CUTTING
SCREW THREADS ON METAL PIPES OR TUBES." A communication from abroad by
Frank Armstrong, of Bridgeport, Connecticut, United States of America.
This Invention relates to improvements in apparatus for cutting screw threads on
metal pipes or tubes, and is designed chiefly for cutting the threads on gas and 3
steam pipes.
The said Invention comprises two separate or independent dies, which are fitted
in a recess or recesses in a metal plate by being boxed or halved thereto, and bolted
fast so that they can be readily taken out by removing the bolts or their nuts..
Provision is thereby made for more readily removing the said dies for changing and 3
sharpening them than is practicable with ordinary divided dies.
My improved dies have slotted holes for the passage of the bolts by which they
are fastened to the plate or holder to allow them to be adjusted to suit the size of
the pipe or tube to be cut.
The said Invention also comprises screws for adjusting the dies, these screws 4
being fitted in the ends of the plate, as herein-after described.
In the accompanying Drawings,
Figure 1 is a plan of a die plate constructed and fitted with dies according to my
Invention.

page_text: :
Figure 2 is an edge view of the same, provided with a guide socket, as herein-
after described.
Figure 3 is a front view, shewing my improved die plate fitted in a holder which
is designed to be attached to an ordinary screw cutting machine.
Figure 4 is a top or edge view of the same.
Figure 5 is a longitudinal section on the line x, x, Figure 3.
Like letters indicate the same parts throughout the Drawings.
a is the die plate, which is recessed as shown to receive the dies b, which are also
recessed or halved to fit in the recessed part of the plate flush with the surface, and
they are secured by bolts c, the. holes for the bolts being slotted to allow them to
be adjusted centrally with the guide d, which, when the said apparatus is to be
operated by hand, is formed or fixed on the plate a. This guide projects from the
plate a at right angles to its surface, and is fitted with bushes, through which the
end of the pipe or tube passes to the dies b. The said bushes are secured in the guide
by a set screw d¹, and are removable so that they may be changed to suit pipes of
various sizes. e, e, are the adjusting screws for setting up the dies; they pass
through the ends of the plate a, as shewn.
These adjusting screws provide means for accurately adjusting the dies to the
dimension of the tube when the latter is placed between them.
The dies are bevelled on the outer corners b', so that they may be sharpened by
grinding off the said corners.
These dies may be very simply and cheaply made by stamping them in the form
required for connecting them to the said plate in this manner.
The solid die plate is recessed slightly deeper in the middle portion than in the
other part to make room for the thicker portion of the dies.
The lugs or projections a' serve for the reception of the handles a* when the said
apparatus is used for screwing pipes by hand.
My improved die plate holder or box f is preferably formed of cast iron; it has
its rear portion formed to enter the recess formed for its reception in the head of
the machine. By its peculiar formation this holder affords a central opening, as
shewn in Figure 5, for the passage of the pipes to the dies b. Moreover, by this
construction a recess is formed for the securing nuts of the die plate, which are
preferably arranged as above described, and shewn in Figures 1 and 2. A front
recess is also formed for the reception of the die plate a, whose ends a¹ project and
form lugs which, when the die plate is in position, lie adjacent to and in the same
plane with the ends of the said box or receptacle.
These lugs a', it will be seen, extend to a distance not less than the length of the
die-adjusting screws, and the turning of the die plate is prevented by the contact
of the said lugs with the box or holder, while at the same time the said lugs protect
the adjusting screws and prevent any accidental movement of the same.
By this the peculiar formation of the said box or receptacle f, dies and die plates
longer than the head of the standard machines may be used, and as the said die
plate box or holder extends forward a very short piece of pipe may be operated
upon by the dies. And as the thickness of the front of the box in a working
machine is only about one-quarter of an inch the pipe holder may approach to
within that distance of the first thread of the cutting dies.
By reference to Figure 5 of the Drawings it will be seen that the thread of the
dies used in my improved die plate is of a uniform depth and pitch throughout its
whole extent, but is cut taper with two different angles of inclination, that is to
say, the initial or front portion of the die has a greater inclination than the
remaining portion, the advantage of this construction being that the enlarged
diameter of the thread at the entrance of the die permits the free entrance of the
end of the pipe, although it may be burred by the machine which cuts it into
sections, and the thread at this part of the die having the proper acute or angular
form instead of being flattened on the top will at once "bite" or grasp the pipe,
and while reducing or cutting away the excess of metal will also "lead" or start

page_text: the succeeding or following thread or cutter, which is less tapered, and which cuts
it to the required gauge.
In ordinary dies the double taper is obtained by a reduction of the height of the
thread, which produces a flat surface on the top of the thread that shaves off the
excess of metal from the pipe, but does not take hold of or enter the same to lead
it to the succeeding or following threads. Moreover, by the above-described peculiar
form of cutting thread I am enabled to remove the excess of metal at the end of
the pipe with much less power than is ordinarily required, and when it is desirable
to remove the pipe from the dies it is much sooner relieved from strain or pressure
than heretofore.
My Invention also affords the following advantages, namely
:-
The dies can be adjusted to variations in the size of the pipes or tubes, and can
be worked with much less labor and accomplish the desired results in less time
than the ordinary solid dies.
The dies being made in two parts instead of one (as in the solid die) can be more
perfectly constructed, their cutting edges can be reached more directly, and the
work may be performed with greater precision and uniformity than heretofore.
The said dies can be sharpened without drawing their temper, and can be kept
in good condition more easily and with less expense than other dies. An ordinary
mechanic can sharpen these improved dies, and is not obliged to send them to the
manufacturer, as is the case with solid dies when they become blunt.
Moreover, these dies are interchangeable in the stock, and although adjustable dó
not need adjusting to cut the standard size for which the dies are made. There are
corresponding marks on the plate or stock and on the dies, and when these marks
are brought into line the dies will cut the standard size.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I do not confine myself to the exact form or construction of the dies, die plate,
and plate holder, as shewn in the accompanying Drawings, as these may be varied
within certain limits to adapt them to the pipe-cutting machines in which they are
to be used and to the work which they have to perform, and I claim,-
First. In a pipe-cutting machine the employment of the aforesaid die plate fitted
with two separately formed dies with taper threads, and which are secured adjustably
in the said plate, as and for the purposes specified.
Second. The die plate provided with central adjusting screws, and having its
ends extended to form lugs, as and for the purposes set forth.
Third. The box or holder adapted to enter the recess in the head of a pipe-
cutting machine, and extended forward and laterally to form a receptacle for the
dies and die plate, as above set forth.
In witness whereof, I, the said Henry Harris Lake, have hereunto set my hand
.
and seal, this Eighteenth day of February, in the year of our Lord One
thousand eight hundred and seventy-nine.
HENRY H. LAKE. (L.S.)