IMPROVEMENTS IN MACHINES FOR CUTTING SCREW THREADS ON PIPES AND COUPLINGS
Year: 1880

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN
MACHINES FOR CUTTING SCREW THREADS ON PIPES AND COUPLINGS." A
communication from abroad by Isaac Smith Schuyler, of Brooklyn, in the
County of Kings, State of New York, Isaac Stout Mettler, of Jersey City, in
the County of Hudson, State of New Jersey, and Barbara Margaret Faucher,
of Newburgh, in the County of Orange, State of New York, both in the
United States of America.
COMPLETE SPECIFICATION filed by the said Alexander Melville Clark at the
Office of the Commissioners of Patents on the 7th July 1880.
"
ALEXANDER MELVILLE Clark, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
IMPROVEMENTS IN MACHINES FOR CUTTING SCREW THREADS ON
PIPES AND COUPLINGS." A communication from abroad by Isaac Smith Schuyler,
of Brooklyn, in the County of Kings, State of New York, Isaac Stout Mettler, of
Jersey City, in the County of Hudson, State of New Jersey, and Barbara Margaret
Faucher, of Newburgh, in the County of Orange, State of New York, both in the
United States of America.
These improvements relate to machines for cutting screw threads upon pipes and
couplings, internally and externally, and have for their object to accomplish such
work more rapidly and perfectly than has heretofore been done. I make use of
rotary cutters formed with serrated edges, the arbors of which cutters are fitted in
a revolving head that has an endwise motion proportioned to the pitch of the
screw, so that while the cutters rapidly revolve with their arbors they also travel
in a spiral path upon the surface being operated upon.
The construction and operation of the machine will be particularly described
hereinafter with reference to the accompanying Drawing, wherein Figure 1 is a
plan view of the machine in a form for cutting an internal screw; Figure 2 is a
vertical longitudinal section on line x, x, of Figure 1; Figure 3 is an end view of
the machine, giving a front view of the cutters with the work bed in section;
Figure 4 is a vertical transverse section on the line y, y, of Figure 1; Figure 5 is a
section of the revolving head, showing the construction whereby the cutter arbors
are held to the proper inclination or pitch; Figures 6 and 7 are detail views

page_text: representing parts of the revolving head; Figure 8 is a sectional view showing the
cutters as arranged for cutting an external thread. Corresponding parts are
indicated by similar letters of reference in all the Figures.
The operative parts of the machine are mounted upon a carriage A that will be
fitted to reciprocate in slides, or on rollers on a suitable bed. As shown, the
carriage A is formed with flanged ribs at its under side, which enter grooves in the
side flanges-of-the-bed-B,-whereby-the-carriage_may_slide_to_and_from the slide
block C, which is fitted at one end of bed B, and carries the work. The slide
block is fitted to move in a suitable slide way lengthwise of bed B, and is
provided at its under side with a rack that gears with a pinion on a cross shaft a',
which shaft is fitted with a crank handle or hand wheel for convenience in moving
the block C. In a cross mortise in the upper side of block C is a block a that
sustains a cage composed of top and bottom discs a², and connecting rods a³. The
lower disc a of this cage sets loosely upon the upper end of a rod u that is fixed
to block a, and extends down through the slide block C, and through a tubular
hub at the under side of block C. The lower end of rod u rests in a step formed
upon the end of a lever v¹ that is hung in a pendant u¹ from the block C. The
opposite end of lever v¹ carries an adjustable weight v², which may be regulated to
balance the block a, the cage, and the work which is placed in the cage. The hub v
is fitted in a dovetail cross mortise at the under side of block C, which block is
slotted for post u to pass, so that the block a and cage are capable of lateral
movement on block C. In the upper disc a² of the cage is tapped a screw a¹ for
use in clamping the work, as shown in Figure 2, and upon block a is hung a stop v³,
which may be turned for engagement with notches in the lower disc a² to hold the
cage from turning while the machine is in operation. By this construction special
care is not required in placing the work, as the tools will keep the work properly
centred. In cutting an internal thread on a quarter bend coupling it will be placed,
as shown in Figure 1, so that when one end is cut a quarter turn of the cage will
bring the other end into position. D is the revolving head. This consists of a
hollow cylinder provided with the fixed caps b, b¹, and fitted in the boxes 62, the
lower one of which is sustained by a post b³ that rises from the carriage A. The
cap b is formed as a gear wheel that receives motion from a secondary shaft, as
hereafter described. The head D carries the arbors c that extend through the
caps b, b', in which they have bearings, and at the rear ends, behind cap b, the
arbors c are fitted with pinions c' that mesh with an internally geared ring or
recessed disc e². The cutters may be placed directly upon the arbors c, which will
then be fitted for radial adjustment. I prefer however to use a second revolving
head D' similar to D, but smaller, and sustained in boxes 64 on a post 65. The
head D¹ is fitted with a fixed cap d³ and adjustable cap d', which sustain the
bearings h, h5, of the arbors c that carry at their outer ends the cutters k. The
arbors c³ are connected to arbors c by toggle bars ct, which are universally jointed
to permit radial movement of arbors c5, as hereafter described. Upon the fixed
cap d³ is fixed a gear wheel c6 corresponding in size with the gear b of head D.
Before describing the manner in which the arbors are fitted for adjustment I will
describe the mechanism for operating the heads and cutters. Through the centre
of the heads D, D¹, passes a rod d that is sustained at the back of the machine in a
box d', which is fixed on the carriage A. The rod d slides in box d, and is
held from turning by a slot and pin, and at its forward end it is fitted with
a loose cone d², upon which rest the collars c³ of arbors c³. Around the rod
is a tube or sleeve d³; upon this is a sleeve e that carries the internally
toothed disc c³, and upon sleeve e is fixed the gear wheel e¹ that meshes with the
pinion e of the driving shaft f which is fitted in boxes h³ on carriage A. Upon
sleeve e is a loose collar e³ that is formed with a large gear wheel g that meshes
with a pinion f¹ on the driving shaft, and collar e³ is also formed with a small gear
wheel g¹ that meshes with a large gear g² on the secondary shaft k'. The shaft k
carries a pinion g³ meshed with toothed cap b to revolve head D, and also carries a
pinion g* meshing with gear c6 to revolve head D'in unison with D.
The cap d'

page_text: of head D' is formed with rectangular apertures, as shown in Figures 5 and 6, to
receive the boxes h that carry the arbors c³. The boxes h project in front of
cap d', and are grooved externally to receive an elastic band i which serves to draw
the boxes and arbors c toward the centre and retain the collars c³ upon the cone d²,
so that the diameter of the thread cut by the machine is regulated by the position
of the cone and the band i will collapse the cutters when the cone is withdrawn.
The cap d is attached to head D' by screws passing through slots in the cap
(see Figure 6), so that the cap may be turned to throw the arbors c at an angle
more or less, to the axis of the head D' and the cutters, thereby held during
revolution in the plane or pitch of the screw.. By the above described construction
and arrangement, while the head D¹ is revolved, and carries the arbors c³ with it,
the arbors c have a rapid and independent revolution in the proportion of about
70 revolutions of the arbors to one of the head D¹. I prefer to use four cutter
arbors, as shown, and each arbor may carry two or more cutters, or from 8 to
12 cutters in all, graduated in diameter, so that the rear cutters will finish the
thread partially cut by the forward cutters. The cutters k consist of circular steel
discs formed with bevelled and serrated edges, which are very effective in cutting.
The mechanism for automatically moving the carriage forward and back, and
collapsing and expanding the cutters, is as follows:-Upon the back of carriage A in
the central line of the machine is a box ¹ sustaining one end of a shaft 1, the other
end of which is supported in bearings on the pillow block 2 that rests on the bed B.
Upon the shaft is a roller m held by a pin or feather that 'enters a slot in the
shaft, so that while the roller m turns with the shaft the shaft may move forward
and back with the carriage, which it is caused to do by the hub of a bevel gear m'
and a collar m²; which are fixed on shaft at opposite sides of box U. The
forward end of roller m is formed as a spiral cam upon which bears the friction"
roller n, that is fitted on a stud n' at the ear of carriage A, so that by one revo-
lution of roller m the carriage B will be gradually forced forward the required
distance and also withdrawn. A spring n² or a weight in place thereof serves to
withdraw the carriage, and the cam will be formed so that the withdrawal is made
quickly, sufficient time being allowed for removal of the completed screw and the
substitution of a new piece of work. The roller m is also formed with a peripheral
groove o into which enters a pin o' that projects from an adjustable extension
piece o of the rod d.. The groove o is formed most of its length in a plane at
right angles to the axis of roller m, whereby it retains the rod d and cone d²
projected and the cutters expanded, and for the remainder of its length it is
spiral, the spiral portion terminating abruptly at a point coinciding with that
portion of cam m that completes the forward movement of carriage A, so that
when the pin o' reaches the abrupt end of groove o the spring p that is connected
to the piece o² and pillow block 2 will cause endwise movement of rod d with
cone d and the cutters will be collapsed by the elastic band i, so that they may
withdraw from the work. The further movement of roller m projects the cone and
expands the cutters before the carriage again moves forward. The piece o² is
attached to rod d by screws so that it may be changed to lengthen or shorten the
rod for expanding the cutters more or less. The shaft is revolved by a bevel
gear p¹ on a cross shaft p² that is fitted in boxes on carriage A and fitted with a
pinion q that meshes with a worm q' on the secondary shaft k. The driving shaft f
is provided with a pulley f' for connection by a belt with suitable power.
The operation of the machine is indicated in the above description to such an
extent that further description will not be required. The cone d² being loose will
be revolved by contact of the collars on the arbors, and the friction thereby lessened.
It will be seen that the forward movement of the head with the carriage with the
revolving motion causes the cutters to act in a spiral path. To change the pitch
the cam roller m will be changed. The cone may have a cylinder formed at its
inner end, on which cylinder the collars c³ move while the screw is being cut, or
that portion may be slightly tapering to give a corresponding effect to the screw,

page_text: For cutting an external thread the parts may be arranged as shown in Figure 8.
In this case the collars c³ of the cutter arbors rest on an elastic wheel s that is on a
fixed shaft on rod s¹, and the cutters are forced inward to the work by a tapering
sleeve t that bears on the collars, which sleeve will be fitted to revolve and
provided with an offset to permit.expansion of the cutters by the elasticity of
rollers s.
The machine as above described is more especially adapted for threading what
are known as "fittings." For wide couplings requiring a longer screw the forward
movement of the carriage may be given by a screw and the backward movement
by a reverse movement at higher speed.
I do not limit myself in these particulars, nor to the details generally, exactly
as described, as they may be varied without departing from this Invention.
In this machine the use of oil is dispensed with, and the threads cut dry, thereby
saving expense of oil, and rendering the chips or cuttings more valuable, as they
will be free from oil and dirt. This method of cutting produces a more perfect
fitting screw than can be made with taps and dies in the usual manner for the
reason that a tap or die to ensure its entering must be bevelled at the end, thereby
leaving the large end of the pipe or small end of the fitting with the first few
threads flattened, or only about half depth, while this machine will cut a perfect
thread from beginning to end. Further, the tap must be passed entirely through
the coupling, thereby making the screw straight, so that a perfect joint cannot be
made with a pipe having the thread cut on the taper, while with this machine the
screw of the coupling may be tapered as required and uniformly.
When fittings are clamped for cutting by taps or dies in the usual manner the
pressure stretches the iron, so that the thread cut with the tap having a given
number of threads to the inch will not match a thread of the same number cut
by a lathe. By this method of cutting the fitting is held solidly, and the thread
cut will be accurate to the gauge.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as new, and desire to secure by Letters
Patent is,-
1st. In screw cutting machines, the combination with a head having a revolving
and forward movement, of revolving arbors carrying circular cutters and fitted for
radial movement, a slide rod at the centre fitted with a device for expanding the
arbors, and a cam roller fitted for moving the slide rod and cone lengthwise,
substantially as shown and described.
2nd. In screw cutting machines, the revolving head D₁ provided with caps d³, d³,
and carrying cutter arbors c in boxes fitted for radial movement combined with
the revolving head D, revolving arbors c, and toggle bars c¹, for operation as
specified.
3rd. In screw cutting machines, the revolving cutter arbors c³, combined with a
revolving head having caps sustaining the arbors, one of which is capable of
partial revolution for varying the angle of the arbors, substantially as and for the
purposes set forth.
4th. In screw cutting machines, the revolving head D, the arbors c carrying the
cutters or connected to the cutter arbors, the pinions c³, and revolving internal
gear c², combined for operation as and for the purposes set forth.
5th. In screw cutting machines, the head D fitted with gear b, arbors c, carrying
pinions c¹, revolving sleeve e, carrying internal gear c², loose collar es, carrying
gears g, g', that are respectively connected to the driving shaft and to a secondary
shaft that is geared to head D, substantially as shown and described.
6th. In screw cutting machines, the head D', carrying cutter arbors co, and
provided with gear 6 combined with the revolving head D, toggles c³, and

page_text: secondary shaft giving motion to head D, whereby the head D¹ with its arbors is
operated sychronously with head D and its arbors, as set forth.
7th. In screw cutting machines, the revolving roller m formed with a spiral cam
and peripheral cam groove in combination with the slide rod d, revolving heads
D, Di, arbors c; c, sliding carriage A fitted with roller n, and spring n³, and fixed
bed B, substantially as and for the purposes set forth.
8th. The revolving shaft 7 and cam roller m combined with the fixed bed B and
sliding carriage A, substantially as and for the purposes set forth.
9th. The shaft, sustained in the bearings 1, 12, and fitted with bevel gear m'
and the cross shaft p², gearing with wheel m³, and driven from the secondary
shaft by a worm and pinion, as shown and described.
10th. In screw cutting machines, the serrated circular cutters k attached upon
revolving arbors in a head that is fitted for movement forward spirally, substantially
as described and shown.
11th. In screw cutting machines, the sliding. rod d, acting by its movement to
cause the expansion or contraction of the cutters, and fitted with the adjustable
extension o² that connects with the operating cam m, substantially, as and for the
purposes specified.
12th. In screw cutting machines, the slide C fitted for movement endwise of
bed B, and provided with the slide block a that sustains the revolving cage a², a³,
substantially as and for the purposes set forth.
13th. The block a, rod u, cage a², a³, hub v, lever v¹, and adjustable weight v²
combined together, and with slide block C, substantially as and for the purposes
specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Sixth day of July, in the year of our Lord One
thousand eight hundred and eighty.
A. M. CLARK. (L.S.)