Improvements in Mechanism for Cutting Screw Threads.
Year: 1889

page_text: Date of Application, 12th Apr., 1889
Complete Specification Left, 11th Jan., 1890-Accepted, 8th Mar., 1890
PROVISIONAL SPECIFICATION.
Improvements in Mechanism for Cutting Screw Threads.
I WILLIAM WILSON HULSE.of the Ordsal Works Salford in the County of Lancaster,
Engineer, do hereby declare the nature of this invention to be as follows:-
Both internal and external screw threads may be cut by means of revolving radial
dies moveable towards or away from the axis about which they revolve for the purposes
of adjustment and of setting them up to or withdrawing them from the work as
may be required. For cutting external threads, the dies are held in a die box and
are actaated radially by a cam action such as commonly employed. The cam block
is rotated by means of a worm (which is by preference made solid with its spindle)
and of a worm wheel formed upon the back of the cam block of a smaller diameter
than that of the block, in order that the worm and its spindle may be accommodated
without increasing the diameter of the die box for the purpose. The die box is
formed or secured upon a spindle which is by preference made hollow and
is mounted in bearings in a headstock secured upon a bed. Sometimes the dies may
be arranged in pairs one of each pair cutting when the die box rotates in one direction
and the other when it rotates in the opposite direction. The work is secured in a vice
which is adjustable along the bed and which holds the work by means of gripping.
dies operated similarly to the cutting dies and with a similar arrangement of worm
and worm wheel. While the threads are being cut the work remains stationary
and the cutting die box and spindle have an end wise as well as a rotatory movement,
the end wise movement corresponding to the advance of the cutting dios along the
threads they are forming. Either 3, 4, 6 or 8 dies may be used both for cutting
and gripping according to the diameter of the work. Sometimes when as for smaller
work 3 dies only are employed the cam block by which they are moved towards
or away from the axis about which they revolve, may be actuated by a hand lever
instead of by worm and wheel in the manner previously described. For working the
spindle backwards and forwards end wise by hand the spindle may be provided with
a loose sleeve (between two collars) operated to and fro by rack and pinion the rack
being formed on or secured to the sleeve and sometimes a forked lover taking into
a grooved collar on the spindle may be employed for giving this end wise movement.
In some cases change guide screws (of different pitches of thread) and disengageable
segment nuts are provided for traversing the spindle end wise at a rate corresponding
with the pitch of the threads to be cut. The pitches of the guide screws are the.
same as those of the threads to be produced. The guide screws are formed as.
sleeves and one or other of them is secured fast upon the spindle according.
to the pitch thread required. The segment nuts can be put in or out of gear with
the screws at will. In other cases one permanent guide screw only may be employed:
held between two collars on the spindle and free to rotate upon the spindle. The
screw in this case is rotated at varying speeds in relation to the speed of the spindles'.
rotation (to correspond with the pitch of thread to be cut) by means of change
wheels driven from the spindle. The improvements already described are applicable.
more especially for cutting threads externally on the ends of wrought iron tubes.
For cutting the tubes (when of moderate size) to lengths before cutting the threads
self acting slides holding bar tools may be mounted on the face of the cutting die
box or the ordinary wheel cutters may be employed the tubes being meanwhile held,
stationarily in the vice. Large tubes and other objects may be cut to lengths either
by a rotary saw mounted on the bed of the machine or by bar tools secured in a
transverse slide working in a saddle on the bed; and in these cases the die block of
the vice in which the tubes are secured while being cut has a rotary motion imparted
to it which it communicates to the tubes. A rotary vice block or a stay may he

page_text: employed for giving additional support to the tubes when being rotated. For
cutting threads internally as for example in the sockets used for coupling wrought
iron pipes together, radial screw cutting dies may be held in slot holes in a hollow
round bar which may be placed partly within the hollow spindle of the machine and
be gripped firmly in the cutting die box, which in this case serves as a vice.
Within the hollow bar is an adjustable sliding solid bar having a conical part with
longitudinal grooves of dovetail or other suitable form into which the inner ends of
the dies are fitted so that when the solid bar is traversed within the hollow one the
dies either approach towards or recede from the axis of the two bars according as the
solid bar is moved in one direction or the other. Sometimes the hollow bar may be
gripped in the vice previously described as for holding the work, and in this case the
work is gripped in and rotated by the cutting die box. Sometimes when a machine
is required for cutting internal threads only the hollow bar may itself form the
spindle of the machine and the die box for cutting external threads may be dispensed
with. The driving gear may be single or compound and the spindle may slide endwise
in the boss of the gear wheel which it carries so as to avoid the use of a sliding wheel.
Sometimes there may be two screw cutting headstocks mounted on one bed (which
may be of the lathe type) for operating simultaneously on both ends of a tube or
other object. One backshaft may operate the driving gear of both spindles or each
spindle may be driven independently. Either one or two vices may be used for
holding the work. For cutting internal threads in holes which only extend part way
through the material in which they occur, solid taps may be employed carried in
holders which may be secured in the die boxes or in suitable rotating spindles. The
construction of the holders is such that when the taps have penetrated to the bottom
of the holes one part of the holders slips upon the other part so as to arrest the cutting
action of the taps and prevent their destruction. The slipping action of the two parts
of the holders is regulated and controlled by two sets of interlocking friction rings
connected with the two parts respectively. The friction rings can be loaded variably
(by adjustable springs or other suitable means) according to the strength of the tap
employed and to the maximum amount of torsional strain to which it may be desired
to expose it.
Dated this 10th day of Anril 1889
HY. C. CARVER,
Agent for Applicant.
COMPLETE SPECIFICATION.
Improvements in Mechanism for Cutting Screw Threads.
I, WILLIAM WILSON HULSE of the Ordsal Works Salford in the County of
Lancaster Engineer 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 the accompanying drawings:-
:-
Both internal and external screw threads may be cut by means of revolving radial
dies moveable towards or away from the axis about which they revolve for the
purposes of adjustment and of setting them up to or withdrawing them from the work
as may be required. For cutting external threads the dies are held in a die box and
are actuated radially by a cam action such as is commonly employed. The cam block
is rotated by means of a worm (which is by preference made solid with its spindle)
and of a worn wheel formed upon the back of the cam block of a smaller diameter
than that of the block, in order that the worm and its spindle may be accommodated
without increasing the diameter of the die box for the purpose. The die box is formed
or secured upon a spindle which is by preference made hollow and is mounted in
bearings in a headstock secured upon a bed. Sometimes the dies may be arranged
in pairs, one of each pair cutting when the die box rotates in one direction and the
other when it rotates in the opposite direction. The work is secured in a vice which
is adjustable along the bed and which holds the work by means of gripping dies

page_text: operated similarly to the cutting dies and with a similar arrangement of worm and
worm wheel. While the threads are being cut the work remains stationary and the
cutting die box and spindle have an end wise as well as a rotatory movement, the end-
wise movement corresponding to the advance of the cutting dies along the threads
they are forming. Either 3, 4, 6 or 8 dies may be used both for cutting and gripping
according to the diameter of the work. Sometimes when as for smaller work 3 dies
only are employed, the cam block by which they are moved towards or away from
the axis about which they revolve, may be actuated by a hand lever instead of by
worm and wheel in the manner previously described. For working the spindle back-
wards and forwards end wise by hand, the spindle may be provided with a loose sleeve
(between two collars) operated to and fro by rack and pinion, the rack being formed
on or secured to the sleeve; and sometimes a forked lever taking into a grooved
collar on the spindle may be employed for giving this end wise movement. In some
cases change guide screws (of different pitches of thread) and disengageable segment
nuts are provided for traversing the spindle endwise at a rate corresponding with the
pitch of the threads to be cut. The pitches of the guide screws are the same as those
of the threads to be produced. The guide screws are formed as sleeves and one or
other of them is secured fast upon the spindle according to the pitch thread required.
The segment nuts can be put in or out of gear with the screws at will. In other
cases one permanent guide screw only may be employed held between two collars on
the spindle and free to rotate upon the spindle. The screw in this case is rotated at
varying speeds in relation to the speed of the spindle's rotation (to correspond with
the pitch of thread to be cut) by means of change wheels driven from the spindle.
The improvements already described are applicable more especially for cutting
threads externally on the ends of wrought iron tubes. For cutting the tubes (when
of moderate size) to lengths before cutting the threads self acting slides holding bar
tools may be mounted on the face of the cutting die box, or the ordinary wheel cutters
may be employed the tubes being meanwhile held stationarily in the vice. Large tubes
and other objects may be cut to lengths either by a rotary saw mounted on the bed
of the machine, or by bar tools secured in a transverse slide working in a saddle on
the bed; and in these cases the die block of the vice in which the tubes are secured
while being cut has a rotary motion imparted to it which it communicates to the
tubes. A rotary vice block or a stay may be employed for giving additional support
to the tubes when being rotated. For cutting threads internally as for example in
the sockets used for coupling wrought iron pipes together, radial screw cutting dies
may be held in slot holes in a hollow round bar which may be placed partly within
the hollow spindle of the machine and be gripped firmly in the cutting die box, which
in this case serves as a vice. Within the hollow bar is an adjustable sliding solid bar
having a conical part with longitudinal grooves of dovetail, or other suitable, form,
into which the inner ends of the dies are fitted, so that when the solid bar is traversed
within the hollow oue the dies either approach towards or recede from the axis of the
two bars according as the solid bar is moved in one direction or the other. Sometimes
the hollow bar may be gripped in the vice previously described as for holding the
work, and in this case the work is gripped in and rotated by the cutting die box.
Sometimes when a machine is required for cutting internal threads only, the hollow
bar may itself form the spindle of the machine and the die box for cutting external
threads may be dispensed with. The driving gear may be single or compound and
the spindle may slide end wise in the boss of the gear wheel which it carries, so as to
avoid the use of a sliding wheel. Sometimes there may be two screw cutting head-
stocks mounted on one bed (which may be of the Lathe type) for operating
simultaneously on both ends of a tube or other object. One back shaft may operate
the driving gear of both spindles or each spindle may be driven independently.
Either one or two vices may be used for holding the work. For cutting internal
threads in holes which only extend part way through the material in which they occur,
solid taps may be employed carried in holders which may be secured in the die boxes
or in suitable rotating spindles. The construction of the holders is such that when
the taps have penetrated to the bottom of the holes, one part of the holders slips upon

page_text: the other part so as to arrest the cutting action of the taps and prevent their
destruction. The slipping action of the two parts of the holders is regulated and
controlled by two sets of interlocking friction rings connected with the two parts
respectively. The friction rings can be loaded variably (by adjustable springs or
other suitable means) according to the strength of the tap employed and to the
maximum amount of torsional strain to which it may be desired to expose it.
as may
When
In Sheet 1 of the accompanying drawings Fig. A is an end view and Fig. B a
front view (partly in section) of a machine constructed in accordance with this
invention. I is the bed of the machine, 2 the headstock secured upon the bed, 3 the
spindle having a hollow centre and working in bearings in the headstock and 4 the
die box formed in one piece with the spindle. 5 is the cam block and 6 the screw
cutting dies which are moveable towards or away from the axis of the spindle.
be required by rotating the cam block within the die box; this cam action being one
which is well understood and commonly employed in screwing machines. The cam
block is rotated within the die box by means of a worm 7 and worm wheel 8 the latter
being formed upon the cam block, and being of smaller diameter than the block
so as to allow the worm and its spindle 9 to be accommodated as shown, without
the diameter of the die box being increased for the purpose. 10 is a vice for
holding the work by means of radial gripping dies, operated similarly to the
screw cutting dies, except that in this case the worin wheel is not made of smaller
diameter than the cam block. When desired however the worm wheel for the
vice may be made of a reduced diameter as described above with reference to
the screw cutting die box. The vice is adjustable along the bed 1 and may be
secured in any desired position thereupon by means of the bolt 11.
the machine is in action the work is held stationarily in the vice while the
spindle is rotated, and at the same time traversed endwise in its bearings
in the headstock by the action of a sleeve guide screw 12 secured fast upon the
spindle and gearing into a segmental disengageable nut 13. The pitch of the guide
screw is the same as that of the thread to be cut, and change guide screws and
segmental nuts are provided to suit different pitches of threads. Fig. C. (Sheet 2)
is an enlarged view showing inore fully the segmental nut 13 and the means for
operating it. It is secured to a block 14 by screws as shown, and the block has a
vertical movement in a guide box 15 (for putting the nut in or out of gear with the
guide screw) produced and controlled by a cam 16 which is operated by a handle 17.
18 is a grooved collar on the spindle 3 acted upon by a forked lever 19 which is
worked by a handle 20, and by means of this mechanism the spindle can be traversed
end wise by hand when the disengageable nut 13 is out of gear with the guide screw.
21 is a spur wheel mounted on the spindle with a feather key so that the spindle is
free to move end wise within the wheel, the boss of which extends through and rotates
in the adjacent horn of the headstock and has no movement end wise. The boss of
the wheel thus forms a bearing for the spindle. The wheel 21 is driven by double
gear as shown in Fig. A, 48 being a cone belt driving pulley Figs. D. E. F. (Sheet 1)
show different arrangements of cutting dies. In Figs. D and E there are four and
six dies respectively which cut when the spindle is rotated in one direction only;
while in Fig. F there are six dies arranged in three pairs so that one die of each
pair cuts when the spindle is rotated in one direction and the other die of each pair
when the spindle is rotated in the opposite direction. Fig. G (sheet 1) shows an
arrangement in which three dies are employed and in which the cam block is operated
directly by a hand lever 22 instead of by a worm and worm wheel. The number of
dies employed is governed by the size of the machine. In Fig. B wheel cutters and
holders therefor as commonly employed are shown in position on the face of the
die box, for cutting off the ends of tubes. These wheel cutters and holders can
be removed or put in position as required. Figs. H. K (Sheet 1) are respectively an
end and a front view showing a modified machine driven by single gear and having
the spur wheel 21 situated and confined between the two horns of the headstock. In
this case the boss of the wheel does not pass through either of the headstock horns
and the end wise traverse of the spindle when the machine is at work is produced by

page_text: the action of the cutting dies on the object which is being screwed. The spindle is
traversed end wise manually by means of a pinion 23 operated by a handle as shown
and gearing into a rack formed on the underside of a loose non-rotating sleeve 24
mounted on the spindle between two collars as shown. In Fig. K self acting slides 25
are shown in position on the face of the cutting die box, with bar tools for cutting off
the ends of the work; the self action being produced by screws gearing into the
slides and carrying star wheels 26 operated by a fixed stop in a well known manner.
Figs. L. M, (Sheet 2) are respectively an end and a front view of a machine embody-
ing further modifications. In this case two screw cutting heads are mounted upon
one bed of lathe type, and their spindles are operated simultaneously through a back
driving shaft 27. These two heads are similar to that shown in Figs. H, K, except
that the driving gear (as shown in Fig. L) is double instead of single. Sometimes
each spindle may be driven independently of the other. One vice 10 is shown on the
bed for holding the work stationarily, and a second one may be employed for the same
purpose when the size or nature of the work renders this desirable. 28 is a slide rest
in which a bar tool for cutting work to lengths may be fixed. 29 is a rotary saw
driven by a pulley 30, and mounted on a transverse slide on the bed as shown; this
arrangement forming an alternative method of cutting work to lengths. When either
the slide rest or the rotary saw is employed, the work is held by gripping dies placed
in one or both of the screw cutting heads and is rotated; the head or heads being thus
employ d for the time being as rotatory vices. 31 is a rotatory vice block on stay fitted
with gripping dies as already described and rotating in a bracket 32 secured to the
bed. This serves for giving additional support to the work when being rotated.
Figs. N. O (Sheet 2) are respectively an end and a front view of a further modification
in which a permanent guide screw 33 is mounted loose on the spindle between two
collars, and gears with a disengageable nut such as has been already described. The
guide screw carries a spur wheel which is driven from the spindle through spur
wheels 34, 35, and change wheels 36, 37, which last is mounted on a swing frame
as shown. In this case a single guide screw suffices for imparting different rates of
traverse to the spindle corresponding to the different pitches of threads to be cut.
Fig. P (Sheet 1) is a front view shewing the arrangement for cutting internal threads
with radial cutters, and, Fig. 2. in the same sheet is an end view of a part of the same
arrangement. Parts corresponding to those in the arrangements already described
are numbered similarly. 38 is the hollow round bar gripped firmly in the cutting die
box 4 and having slot holes in which are held the internal cutting dies. 40 is the
adjustable sliding solid bar having a conical part as shown with longitudinal grooves
of dovetail section, which receive the inner ends of the dies 39. This solid bar passes
through the hollow bar 38 and can be traversed end wise within it in either direction
by a hand wheel 41 fitted with a nut which works on a screwed part of the bar 40.
The hand wheel 41 is mounted loose on the spindle of the machine but cannot move
end wise thereon. An endwise traverse of 40 within 38 causes the former to slide upon
the dies 39 and make them either recede from or approach towards the axis of the two
bars according to the direction of the traverse. Figs. R. S. (Sheet 2) are respectively
a sectional plan and sectional elevation of the appliance for cutting internal threads,
in holes which only extend part way through the work. 42 is a solid tap for cutting
the threads, fitting into a holder which comprises a cylindrical box 43, friction
rings 44, 44¹, stem 45, sleeve 46 screwed at the top and having a collar at the bottom
and hand wheel 47 working on the sleeve. The stem 45 can rotate independently of
the box +3 but is locked to it by means of a collar and gland as shown so as to
prevent the stem and box from moving apart end wise. The friction rings 44, 44¹
occur alternately one over the other and are a loose fit on the sleeve 46 and inside
the box 43. The sleeve 46 is keyed on the stem 45; the rings 44 are keyed on the
sleeve and the rings 44' in the box 43 and rotation can be communicated from the
stem to the box only by forcing the rings 44, 44¹ together so as to set up frictional
grip between them. The forcing of the friction rings together is effected by screwing
down the hand wheel on the rings so as to grip them between the wheel and the collar
of the sleeve 46. The pressure of the wheel upon the rings is regulated according to

page_text: the amount of power which it is required to transmit through the holder to the
tap 42; and the rings slip upon each other if the resistance opposed to the action of
the tap should exceed the driving power to which the rings are loaded. The stem 45
is shown connected to a drilling machine spindle but it may also be used in a screwing
machine by gripping it in one of the die boxes.
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. In a screwing machine operating with adjustable dies, a cam block 5 (which can
be rotated in a die box 4 for adjusting the dies) formed or provided with a worm
wheel 8 of smaller diameter than the cam block substantially as shown and described
and for the purpose specified.
2. In a screwing machine operating with adjustable dies the arrangement of the
dies so that one half of their number will cut when the spindle is rotated in one
direction and the other half when it is rotated in the opposite direction substantially
as shown in Fig. F. and described.
3. In a screwing machine having a spindle which traverses endwise a non-rotating
sleeve 24 mounted between two collars on the spindle and formed or provided with a
rack into which gears a pinion 23 for traversing the spindle by hand substantially as
shown and described.
4. In a screwing machine having a spindle which traverses end wise the arrange-
ment of change guide screws and disengageable segmental nuts substantially as shown
in Figs. A. B and C. and described and for the purpose specified.
5. In a screwing machine having a spindle which traverses endwise the arrange-
ment of a permanent guide screw driven through change wheels and of a disengageable
segmental nut substantially as shown in Figs. N. and O. and described and for the
purpose specified.
6. In a screwing machine the arrangement of a circular saw for cutting the work
to lengths substantially as shown in Fig. M. and described.
7. The arrangement of tap holder substantially as shown in Figs. R. S, and
described.
8. The general arrangement of a screwing machine substantially as shown in
Figs. A. B, and described.
9. The general arrangement of a screwing machine substantially as shown in
Figs. H. K. and described.
10. The general arrangement of a screwing machine substantially as shown in
Figs. L. M. and described.
11. The general arrangement of a screwing machine substantially as shown in
Figs. N. O. and described.
12. The arrangement of dies for internal screw cutting and the means for
adjusting and operating the same substantially as shown in Figs. P. and Q. and
described.
Dated this 10th day of January 1890.
H. C. CARVER,
Per F. J. B.