Improvements in Screwing Machines and in the Method of Cutting the Dies thereof.
Year: 1889

page_text: Date of Application, 16th Oct., 1889
Complete Specification Left, 16th July, 1890-Accepted, 16th Aug., 1890
PROVISIONAL SPECIFICATION.
Improvements in Screwing Machines and in the Method of Cutting
the Dies thereof.
I SAMUEL DIXON of the firm of Hendall and Gent of the Victoria Works,
Springfield Lane Salford in the County of Lancaster, Machine Tool Makers do
hereby declare the nature of this Invention to be as follows:-
My Invention relates principally to the screwing machines which are employed
in the formation of screw threads upon cylindrical objects of comparatively large
diameter.
In such machines the screw threads are formed by the concerted action of cutter
dies and in the type of machines now mostly used for the purpose the dies are carried
by a revolving die holder which I will term the cutter head and are fitted to move
toward and from the object to be screwed. It is necessary that these dies shall be cut in
their working places and in the cases of ordinary machines such cutting is effected by
means of a master tap as is well understood. In the cases of machines intended to
screw large diameters it is not practicable to produce these master taps. To over-
come this difficulty I form the threads in the dies by means of a revolving cutter or
milling tool which is so mounted as that it can be set up to its work and be traversed
in a direction parallel with the axis of revolution of the cutter head the rate of
traverse being in such concert with the rate of revolution of the cutter head as will
produce upon the dies screw threads of the required pitch. The revolving cutter may
have a single vee" cutting edge or may have two or more vees so that if desired
the cutters may be completed with one revolution of the cutter head.
"
In a machine
which I have devised the cutter spindle having cone bearings revolves in a bracket
which can be secured to one of the sliding jaws which hold the work the said jaws
being mounted to slide in a carriage which is arranged to be slid along the bed of.
the machine by means of a screw shaft. The cutter spindle receives motion from a
connecting shaft which also imparts motion through worm gearing to the shaft which
actuates the revolving cutter head and the said screw shaft. The connection between
the said connecting shaft and the cutter spindle is so effected as to permit of the
sliding movement of the said jaw necessary to effect the setting up of the revolving
cutter. 1 may or may not incline the axis of the cutter spindle with relation to the
axis of revolution of the cutter head. By these means I shall be enabled to cut dies
It is
suitable to form screw threads upon pipes ten inches or more in diameter.
advisable for some purposes to produce a taper screw thread or a screw thread which
tapers at the finish. To enable such a thread to be produced I form the outer end of
each die with a face which is an incline from the right angle and I impart a slow
backward sliding movement to the abutment ring which sets up the dies during the
screwing so that the dies are gradually withdrawn further away from their work such
sliding movement being either continuous during the whole of the screwing action on
coming into operation after a length of screw has been cut. I employ automatic'
apparatus to draw back the dies at the end of the cut.
Dated this 15th day of October 1889.
DUTTON & FULTON,
. 1, St. James Square, Manchester, Agents

page_text: COMPLETE SPECIFICATION.
Improvements in Screwing Machines and in the Method of Cutting
the Dies thereof.
I SAMUEL DIXON of the firm of Hendall and Gent. of the Victoria Works,
Springfield Lane Salford in the County of Lancaster, Machine Tool Makers 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 and accompanying drawings :-
My Invention relates principally to the screwing machines which are employed
in the formation of screw threads upon cylindrical objects of comparatively large
diameter.
In such machines the screw threads are formed by the concerted action of cutter
dies and in the type of machines now mostly used for the purpose the dies are carried
by a revolving die holder which I will term the screwing head and are fitted to move
toward and from the object to be screwed. It is necessary that these dies shall be
cut in their working places and in the cases of ordinary machines such cutting is
effected by means of a master tap as is well understood. In the cases of machines
intended to screw large diameters it is not practicable to produce these master taps.
To overcome this difficulty I form the threads in the dies by means of a revolving
cutter or milling tool which is so mounted as that it can be set up to its work and be
traversed in a direction parallel with the axis of revolution of the screwing head the
rate of traverse being in such concert with the rate of revolution of the screwing
head as will produce upon the dies screw threads of the required pitch.
In order that the manner in which I carry my Invention into effect may by clearly
understood I will describe the invention with reference to the accompanying drawings
which represent a machine adapted to screw pipes up to ten inches in diameter the
machine being provided with means for cutting the screwing dies in accordance with
my invention.
In the said drawings Fig. 1 represents a side elevation. Fig. 2 a plan and Fig. 3
an end elevation of the machine. Fig. 4 represents a vertical section on the line A
in Fig. 1.
In the said Figs. B is the screwing head carried by the hollow spindle b which
revolves in bearings in the headstock and C C are the jaws which hold the pipe
during the screwing operation. These jaws slide to and from each other upon a
carriage D which is mounted to slide upon the bed 62 which in the example is cast in
one piece with the headstock b¹. A worm wheel 63 is fixed upon the end of the
spindle and is actuated by means of a worm which is fixed upon a shaft which is
fitted to revolve in bearings carried by the headstock. Upon the same shaft is fixed
a second worm d which gears with a worm wheel d' which gives motion by means of
gearing d² to a screw shaft d³ which actuates the sliding carriage D. Upon the same
shaft as the two worms is fixed a stepped cone belt pulley d whereby the screwing
head B is actuated. The gearing is so proportioned as that the said screwing head
and the screw shaft d³ revolve at exactly the same speed. The shaft d³ is provided
with a screwed sleeve d³ which works in a nut de which is connected with the
carriage D. The said nut is formed in two parts which are mounted to slide toward
and from each other. By turning a handle & the two parts of the nut are separated
or brought together by means of a cam so as to disengage the carriage D from the
screw or connect the carriage with the screw. The screwed sleeves upon the shaft d³
are changeable the screwing head cutting a thread upon the pipe operated upon of
the same pitch as the said screwed sleeve. When the nut is disengaged from the
screw d³ the carriage D can be slid to and fro by turning a shaft e which is connected
by gearing with a second shaft e' upon which is a rack pinion e² which gears with a
rack which is attached to the side of the bed 62. The sliding jaws are drawn toward
each other so as to centre and hold the work by turning a right and left hand
The parts of the machine as so far described are not claimed as being
screw.

page_text: novel. To these parts I apply my Invention in the manner next to be described.
Upon one of the sliding jaws C I secure a bracket f which is formed with a bearing
for a cutter spindle upon which is fixed a milling cutter G the bearing for this cutter
spindle being preferably coned. This cutter is grooved to correspond with the threads
of the screw which is to be cut but with this difference that the grooves upon the
cutter are at right angles to its axis and do not form a screw thread. Upon the same
spindle is fixed a bevel wheel which gears with a second bevel wheel /¹ which is
fixed upon one end of a cross shaft i. The other end of this shaft passes through a
skew spur wheel which is formed with a long boss or sleeve which is fitted to revolve in
a bearing formed in a bracket k which is secured to the carriage D. As the jaws Care
moved upon the carriage the shift i slides in the boss of the wheel; the shaft being
connected with the wheel by means of a key and slot or otherwise so that the shaft is
always caused to revolve with the said wheel. The wheel is driven by a second skew
spur wheel which is mounted in the bracket k in a similar manner to the wheel j.
A shaft slides in the wheel j' and its boss and rotates the same arrangements being
made for permitting the carriage D to slide upon its bed without interfering with the
driving connection of the shaft with the shaft i as in the case of the shaft and
wheel i. j.
One end of the shaft is mounted to revolve in a bracket m and upon the same
shaft is fixed a bevel wheel n with which gears a second wheel n' which is secured
upon one end of a short shaft which is fitted to revolve in à second bearing formed in
the bracket m. Upon the other end of the said short shaft is fixed a belt pulley o
whereby the shaft is revolved rotatory motion being thereby imparted through the
gearing the shaft i and the gearing h. ' to the milling cutter spindle g.
On one end of the shaft is fixed a worm p which works in a worm wheel p¹ which
is mounted upon one end of the shaft which drives the screwing head spindle b by
means of the worm 64 as aforesaid. The wheel pl is loosely mounted upon its shaft
but can be connected with it when desirable by means of a sliding toothed clutch p².
When this clutch is out of gear the shaft is free to revolve without the worm wheel p¹
revolving. When the clutch is in gear the belt pulley o serves to impart a slow
revolving motion to the screwing head and a quick revolving motion to the milling
cutter G and at the same time the screw shaft d³ is caused to make one revolution for
each revolution of the said screwing head. When the machine is to be used in the
operation of screwing pipes parts of the apparatus employed in the operation of cutting
the dies are not in place. The parts which would be in the way in the screwing
operations are the bracket f with its spindle and cutter and the shaft with the
wheels h. The other parts may remain in position. The machine is then driven by
means of a belt applied upon the pulley d and the machine is used as an ordinary
screwing machine. The pipe to be screwed is held by the jaws C. C with the aid of an
auxiliary clamping screw which acts upon the tops of the jaws and the screwing
head B and the screw shaft d³ revolve in unison as aforesaid the clutch p² being
disengaged from the worm wheel. When the machine is to be used in the opera-
tion of cutting the screwing dies the belt is removed from the pulley d the worm
wheel p is connected with its shaft by means of the clutch and the bracket f is
applied to the jaw C and secured in position by means of bolts or screws.
the said bracket carries the shaft i and the gearing h. the parts can be quickly
applied as it is only necessary to slide the shaft i into the eye in the wheel j and
to adjust and secure the bracket f in position. If considered to be advisable in
any case I may arrange for the bracket to be applied so as to cause the axis of
the cutter to have a slight inclination from the direct axial line of the screwing
head to suit the angular inclination of the thread to be cut upon the dies but I
have not found such inclination of the axis to be necessary when operating upon
dies for screwing large pipes. When the machine is set in motion the pulley o
will actuate the screwing head and the screw shaft through the gearing p.pl and
will also drive the cutter spindle g by means of the gearing j. j and h. h the
result being that the screwing head will be revolved slowly and the cutter G rapidly.
The cutter G may be brought into action by sliding the carriage toward the screwing
As

page_text: head by turning the shaft e and the nut de would then be caused to engage with
the screw d by turning the handle d' as aforesaid. The cutter will then be
advanced toward the screwing head at a proportionate rate of speed determined by
the pitch of the screw thread upon the screwed sleevo do. The cutter is set up to
its work by turning the shaft e³ so as to slide the jaws C to which the bracket f' is
applied in the required direction across the carriage D. The cutter will then act to
groove the screwing dies and as the cutter is traversed in the direction of the axis
of the screwing head by the action of the screw d³ which revolves once for each
revolution of the screwing head it follows that a screw thread will be cut upon the
screwing dies supposing the cutter G to have been suitably grooved. The cutter
may be set up to finish the screw thread at one cut or by repeated cuts as con-
sidered to be most advantageous. In practice I should employ apparatus for
automatically withdrawing the dies at the end of the cut.
For this purpose
prefer to use the apparatus for which Letters Patent Number 6051 of the year 1882
have been granted to me, but as the method of application of such apparatus will
be readily understood it has not been considered necessary to include it in the
drawings. It is advisable for some purposes to produce a taper screw thread or a screw
thread which tapers at the finish. To enable such a thread to be produced I form the
outer end of each die with a face which is an incline from the right angle and I impart
a slow backward sliding movement to the abutment ring which sets up the dies during
the screwing so that the dies are gradually withdrawn further away from their work
such sliding movement being either continuous during the whole of the screwing
action or coming into operation after a length of screw has been cut. The means
whereby I effect the withdrawal of the dies are indicated in Fig. 2. A lever ris
mounted to turn upon a fulcrum at s and is provided with an antifriction bowl which is
situated a short distance from such fulcrum as indicated by the dotted lines. This
bowl is adapted to act upon the cam ring to slide it back at the required times. The
end of the arm of this lever is jointed to a rod t which slides in a bracket or part
upon the carriage D and is provided with an adjustable stop t¹. When the carriage
or a part fixed thereto comes into contact with the said stop the lever is slowly pushed
over in the indicated direction whereby the cam ring is slid back and the screwing
dios are gradually withdrawn. This withdrawal of the dies may take place during the
whole or during part only of the operation. I can use this part of the apparatus
both for the cutting of the dies and the screwing of the pipes or bodies. It will be
seen that by means of my Invention I can cut screwing dies or cutters adapted for
operating upon pipes of any size which can be operated upon by a machine of such
a character. I do not confine myself to any of the details of the machine as used in
the screwing operation as such details may be greatly varied without affecting the
operation of the parts which constitute my Invention. I may also vary the arrange-
ments for transmitting motion to the cutter G and for applying and carrying the
cutter spindle. In place of the cutter G being grooved it may have only one vee
cutting edge as indicated in Fig. 5.
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 milling cutter G applied to a screwing machine in such a manner as that
such cutter can be rapidly revolved and be set up to operate upon the dies in the
screwing head of the machine and at the same time be regularly traversed in a
direction parallel with the axis of such screwing head to an extent in a complete
revolution of the screwing head equal to the pitch of the screw thread which is to be
formed upon the said dies.
2. As applied to a screwing machine the milling cutter G fixed upon a cutter
spindle which is driven by a side shaft which is connected by gearing with the
screwing bead spindle and the screw shaft which actuates the carriage upon which the
said cutter spindle and its bearing or bearings is or are mounted substantially as and
for the purpose set forth and indicated.

page_text: F 3. The milling cutter G with its spindle connected by means of a cross shaft and
gearing with a side shaft the worm p and worm wheel pl which latter can be con-
nected with the shaft which gives motion to the screwing head B and the screw
shaft d³ which gives motion to the sliding carriage D substantially as and for the
purpose set forth and indicated.
4. The apparatus for cutting the dies of a screwing machine in situ consisting of
the bracket adapted to be secured to one of the holding jaws C and carrying a cutter
spindle g which can be provided with a suitable cutter the shaft and gearing i. h. h³
and the shaft with provision for the movements of the said cutter spindle in a
direction parallel to the axis of the screwing head and at right angles to such axis
the worm and worm wheel p. p¹ the clutch p² and the driving gear n. n'o in combina-
tion with the cross traversable jaws C the sliding carriage 1) the screw shaft d³ and the
screwing head B of a screwing machine substantially as and for the purpose set forth
and indicated.
5. The combination of parts constituting the machine for screwing pipes tubes
or cylinders and for cutting the screwing dies of such machine in situ arranged and
adapted to act substantially as set forth and indicated.
6. The combination of the parts constituting a screwing machine substantially as set
forth and indicated with the apparatus for opening and closing the dies by power as
set forth in the specification of my former hereinbefore referred to invention.
7. Arranging for the carriage of a screwing machine to act through intermediate
parts upon the cam ring so as to gradually withdraw the dies substantially as and for
the purpose set forth and indicated.
Dated this 15th day of Tul„ 1800