IMPROVEMENTS IN MACHINERY FOR THREADING OR SCREWING BOLT BLANKS AND SCREW BLANKS, SOME OF SAID IMPROVEMENTS BEING APPLICABLE TO OTHER PURPOSES
Year: 1880

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for an
Invention of "IMPROVEMENTS IN MACHINERY FOR THREADING OR SCREWING
BOLT BLANKS AND SCREW BLANKS, SOME OF SAID IMPROVEMENTS BEING
APPLICABLE TO OTHER PURPOSES." A communication from abroad by Samuel
Lord Worsley, of Buffalo, in the State of New York, in the United States of
America.
COMPLETE SPECIFICATION filed by the said Sydney Pitt at the Office of
the Commissioners of Patents on the 5th October 1880.
"IMPROVEMENTS IN
SYDNEY PITT, of Sutton, in the County of Surrey.
MACHINERY FOR THREADING OR SCREWING BOLT BLANKS AND SCREW BLANKS,
SOME OF SAID IMPROVEMENTS BEING APPLICABLE TO OTHER PURPOSES."
A com-
munication from abroad by Samuel Lord Worsley, of Buffalo, in the State of
New York, in the United States of America.
The principal objects of the Invention are to take bolt blanks or screw blanks
automatically one at a time from a holder, to cut screw threads upon their stems,
and to discharge them from the machine. The cutting of the screw threads,
commonly called the screwing or threading of the bolt, is effected by holding the
blank stationary while a screw die is simultaneously revolved and advanced upon
the bolt point, and after the screw thread is cut to the requisite extent the
revolution of the screw die is reversed, so as to back it off the bolt point. Hence
the screw die is caused to revolve in alternately opposite directions, and the
duration of the period of direct movement previous to reversal determines the
extent of the screw thread formed upon the bolt stem. It is however expedient
that the same machine should be capable of being used to cut screw threads of
different extents upon bolts, and to this end the object of some of the improvements,
hereinafter described, is to vary the periods of reversal of the movement of the
revolving shaft or mandril carrying the screw die as required to form screw threads
of different extents, that is, screw threads making different numbers of turns
around the bolt stems.
The said improvements consist of various combinations of devices, of which
devices the following are the principal, viz. :-
:-
Grippers or jaws, by means of which the bolt blank is held stationary during
the threading or cutting of the screw thread upon its stem.
A die holder or chuck, by which the screw die is held and moved.

page_text: A revolving sliding mandrel, by which the die holder and die are turned and
caused to advance against the bolt blank, so as to cut the screw thread thereon.
Revolving gearing, by which the mandrel is caused to revolve in either of two
directions.
Reversing gearing, by means of which the direction in which the mandrel is
caused to revolve is reversed.
A leading cam, or some equivalent or substitute therefor, to. commence the
advance of the screw die upon the bolt blank, or vice versa.
Variable pawl change gearing, by means of which the times at which the
reversing gear reverses the direction of movement of the revolving mandrel can
be varied without necessarily removing parts of the machine and substituting
others in their places, and without dependence upon the longitudinal movement
of either the die holder or the grippers which hold the blank to be threaded.
A bolt holder, in which bolt blanks ready for screwing or threading are held.
A bolt mover, by means of which the bolt blanks are taken, one at a time, from
the bolt holder..
One or more stops, by which the descent of bolt blanks in the bolt holder is
checked when the lowest bolt blank is to be taken by the bolt mover.
Transfer fingers or mechanism, by means of which a bolt blank is transferred
from the bolt mover to the grippers or jaws, by which the bolt blank is held
during screwing or threading.
Sundry minor devices, hereinafter particularly described, are also employed in
making some of the combinations claimed as the Invention.
The said devices are combined by combining mechanism, the construction and
character of which can be varied as circumstances render expedient, or to suit the
views of different constructors.
The accompanying Drawings represent the principal parts of a bolt threading
machine, embodying the said improvements in the best form in which they have
been embodied at this date.
Figure 1 of said Drawings represents a plan of the said machine.
Figure 2 represents a front elevation of the same.
Figure 3 represents an end view of the same.
Figure 4 represents a transverse section of the machine at the line x, x, of
Figure 1.
Figure 5 represents a transverse section of the machine at the line y, y, of
Figure 1.
In some of said Figures certain parts are omitted for perspicuity.
Figures 6 to 16 represent views of detached parts of the machine designated by
the same letters as the same parts are designated by in the other Figures, and
some of said parts being represented upon a larger scale than in the other
Figures.
The working parts of said machine are connected with a strong frame A, and
all the moving parts derive their motion from a driving shaft B which is held in
suitable bearings of that frame, and is fitted with a belt pulley C to which the
driving belt is applied. In practice it is convenient either to apply a movable
tightening pulley to the driving belt, so that the latter can be slacked and the
machine stopped by moving the tightening pulley, or to apply a loose pulley to the
driving shaft, and to employ a belt shipper to transfer the belt to and from the
driving pulley and this loose pulley. The driving shaft B is connected by means
of cog gearing, hereinafter more particularly described, with a counter shaft B',
a clutch shaft B2, and a revolving hub B³, the last being mounted upon a cam
shaft B
The blank to be screwed or threaded is held during threading between a pair
of grippers or jaws D, D, which grasp its shoulder beneath its head and hold
the blank stationary, or so that it cannot revolve. When a square or angular
shouldered bolt blank is to be threaded the adjacent faces of the jaws are constructed
with angular grooves fitting the angular shoulders of the bolt blanks. The screw

page_text: die, by which the screw thread is cut, is held by a die chuck E which is secured to
the mandrel F. This mandrel is connected by cog wheels a, a', with the clutch
shaft B, and is also supported in boxes b, b, which permit it to revolve and to slide
endwise towards and from the jaws D, D. The axis of this mandrel and the axial
line of the opening of the jaws are in the same straight line, so that when the bolt
blank is held in the jaws it is in line with the axis of the screw die carried by the
die chuck E of the revolving mandrel F.
In order that the jaws D, D, may gripe the bolt blank and may release it they
are pivoted in an opening of the jaw standard b' of the main frame, so that they
may open and close like pincers. In the working machine the jaws are closed and
are permitted to open by means of a slide, which is connected by toggle links with
their shanks, and the slide is operated by means of a cam which is secured to the
cam shaft B', and is connected with the slide by means of a lever; a spring also is
employed to move back the slide whenever the gripping jaws are to be opened.
As no claim is made to any novelty in the means for opening and closing the
jaws D, D, and as the means above referred to are in common use for operating
the jaws of other kinds of screw machinery, and as a representation of such means
in the Drawings would increase their complexity, it has been deemed better to omit
the representation of such means from the Drawings.
As before stated, the mandrel F is connected by means of cog gear a, a¹, with
the clutch shaft B2, so that it is caused to revolve by the action of the clutch shaft.
The die mandrel F and clutch shaft must however be caused to revolve in
alternately opposite directions to cause the die to cut the screw thread, and to back
off of the bolt after the screw thread is cut. In order that the said devices inay bec
revolved alternately in opposite directions while the driving shaft B continues to
revolve in the same direction, the clutch shaft is connected with the driving shaft
by means of gearing, as follows:-Two cogwheels a² and a³ are mounted upon the
clutch shaft B, with the capacity to turn freely upon it.
One of these cog-
wheels (2) is connected directly with a cogwheel a' secured to the driving shaft B.
The other cog wheel as of the clutch shaft is connected with an intermediate cog
wheel as secured to the counter shaft B¹, which is caused to revolve in the opposite
direction to the driving shaft by the action of the cog wheel a upon that
intermediate cog wheel a³. Hence, the clutch wheels a³, a³, are caused to revolve
continuously in reverse directions, and the connection of the clutch shaft B² with
one or other of said clutch wheels causes the clutch shaft B2, the mandrel F, and the
die connected therewith, to revolve either forward (as indicated by the arrow in
Figure 1) or backward. The clutch wheels and cog wheels thus described constitute
the revolving mechanism by which the mandrel is caused to revolve in either of
two directions.
In order that the clutch shaft B may be connected with the clutch wheels a², a³,
alternately the clutch G is provided. This clutch is fitted to slide longitudinally
upon the clutch shaft, but is compelled to turn with it by means of a feather and
groove; and its heads are fitted with clutch teeth arranged in suitable positions to
engage with corresponding teeth protruding from the adjacent faces of the clutch
wheels. The clutch is shifted upon the clutch shaft to engage with one or other of
the clutch wheels by means of a double graded cam d which is secured to the
counter-shaft B¹, and operates upon the movable pins c, c', of a shifting carriage d¹.
This carriage is arranged to slide upon a bar d parallel with the clutch shaft, and
is connected with the clutch G by a fork d³ which fits in a circular groove of the
clutch body. The shifting pins c, c', are fitted to slide up and down in sockets of
the shifting carriage; and whenever either pin is dropped downward in its socket
its point is engaged by the shifting cam d (Figures 1 and 16), and the clutch is
shifted by the action of that cam; the cam grade c² (Figure 16) and pin c operating
to shift the clutch into connection with the clutch wheel as and the cam grade c
(Figure 16), and pin c¹ operating to shift the clutch into connection with the clutch
wheel a. The clutch, the shifting pins, and the shifting cam, thus effect the reversal

page_text: of the movement of the mandrel, and constitute the reversing gearing or mechanism
of the machine.
In order that the shifting pins c, c³, may be raised and dropped automatically,
two cams c, c³, are provided, and each of these pin cams is caused to operate upon
its appropriate pin by means of a lever c and c', and a link cs and co.
The pin
cams c, c³, are secured to the shaft B, which is constructed to revolve in bearings
secured to the main frame; and the revolution of the shaft causes the protuberance
of the cams to raise and to drop the pins as required. When the clutch G is in
gear with either clutch wheel a² or a³, the mandrel F, and the die carried by it, will
continue to revolve in the same direction until the clutch is shifted. The length of
time during which the mandrel and die continue to revolve in the same direction
should, however, be capable of variation to adapt the machine to cutting screw
threads having a different number of turns upon the blank, or extending different
lengths along its shank. In order that the pin cams c³, c³, may be operated
automatically, but may at the same time have their operation varied to change or
vary the times of shifting the clutch, their shaft B5 is not connected with the
driving shaft by means of invariable combining mechanism, but is connected
therewith by means of the following variable pawl change gearing or mechanism :-
A ratchet wheel H is secured to the end of the shaft B5 which carries the pin
cams c, c, and a vibrating pawl is provided to operate upon this ratchet wheel.
The shank of the lever of the vibrating pawl is connected by a link h² with a
crank pin h³, whose shank is secured in a groove which extends radially across
a hub secured to the counter shaft B', so that the crank pin is adjustable towards
and from the axis of the counter shaft which carries it. The continuous rotation
of the counter shaft B₁ turns the crank pin h³ and causes the pawl h to vibrate at
every revolution; but the extent to which the pawl vibrates, and consequently
the amount of movement which it imparts to the ratchet wheel H, to the
change gear shaft B5, and to the pin cams c, c, secured thereto depends upon
the position in which the adjustable crank pin ³ is secured in the groove of
the hub 4. If the adjustable crank pin be close to the centre of the hub
the vibration of the pawl is sufficient to move the ratchet wheel H but one
tooth at a time; hence, under this adjustment of the crank pin the change
gear shaft B and the cams c¹, c³, will be turned slowly; and the clutch shaft,
mandrel, and die, will run for a comparatively long period in one direction
before being reversed. By shifting the position of the adjustable crank pin h³
in the groove of the hub h, the extent of movement of the pawl h is varied, and
it may be made to vibrate to the extent of two, three, or four teeth of the ratchet
wheel; in which cases the latter, the change gear shaft B5, and the pin cams c, c5,
will be turned faster, and the clutch will be shifted at shorter intervals, corresponding
with the cutting of screw threads. making a less number of turns upon the bolt
shank. In order that the adjustable crank pin may be readily shifted or adjusted
in the groove of the hub h', the crank pin is in the present example constructed
with a tubular body or journal traversed by a screwed stem having at its inner end
the shank which fits in the dovetailed groove of the hub, and at its outer end a
screw nut which is slacked to permit the crank pin to be adjusted, and is tightened
to secure the adjustable crank pin in its place. The same result of varying the
extent of movement of the pawl may be accomplished by providing the hub with
a series of holes at different distances from the centre of the counter shaft, and by
shifting the crank pin from one hole to another. In practice, it is generally
sufficient to have a machine capable of four variations or changes of the operation
of the reversing gearing, and consequently the present machine is fitted to vary
the vibration of the pawl h frome one to four ratchet teeth. If a greater number of
vibrations of the same extent are required, the pawl h must be made capable of a
greater extent of vibration; or, if the vibrations are to be made less in extent, the
ratchet teeth must be made shorter or, the pawl and teeth may be replaced by a
vibrating clamp operating upon a wheel rim, like the means employed to operate

page_text: the feed wheels of sewing machines. The variation of the movement of the pawl
or clamp may if preferred be effected by shifting the lever pin h³ of the link h²
radially of the pawl lever h², in place of shifting the crank pin h³ radially of the
counter shaft, but I prefer the latter modification.
The ratchet wheel (or clamp wheel), the variable pawl (or clamp), and the
adjustable crank pin (or its substitute), by which the extent of movement of
the pawl or clamp is varied, constitute the variable pawl change gearing of the
machine.
When the mandrel F, and the screw die carried by it, are turned in the direction
to cut the screw thread, they must be advanced to the bolt blank endwise thereof,
and must be pushed against it sufficiently to start the cutting of the thread; or, in
place of advancing the mandrel, the gripping jaws while holding the bolt blank
from turning, may be arranged to slide, and thus advance the bolt blank to the
screw die.
After the cutting is thus commenced the progressive formation of the
screw thread by the screw die will draw the latter with the mandrel forward as
long as the turning of the mandrel in the advancing or cutting direction is continued,
and will thus cause the screw thread to be cut to the requisite extent. In order
that the cutting of the screw may be started, the mandrel F and the screw-die are
advanced or moved longitudinally towards the grippers or jaws D, D, by means of
a leading cam I (Figures 1 and 9). This leading cam I is secured to the cam
shaft B, and its cam grade i (Figure 9) operates upon the mandrel F through the
intervention of the rocking arm i, the rock shaft (to which that rocking arm is
secured), the second rocking arm i³ (projecting from the rock shaft), the slide 2+
(which is operated by the second rocking arm), the sliding piston rod ³, and the
arm (of the piston rod), which last arm acts upon the end of the mandrel F. The
arm of the piston rod is fitted with an adjusting screw , so that the screw die
carried by the die chuck E of the mandrel may be adjusted to its proper position
relatively to the blanks to be operated upon. The piston 5 is fitted with a
spring to move the piston (5) back to its starting position whenever the
leading cam permits such action. It is also expedient to apply a similar spring
to the mandrel F, to ensure its removal from the point of the bolt after the screw
die has backed off thereof.
The time at which the leading cam operates to do its work depends upon time
at which the mandrel is connected with the advancing clutch wheel as; hence, if
the latter time be varied, the former should vary with it. In order that the leading
cam may act in concert with the variation of the movement of the mandrel due to
the action of the change gearing or mechanism before described, the leading cam I
is operated at intervals, succeeded by intervals of rest. To this end, the cam
shaft B that carries the leading cam is connected with the revolving driving
hub B3 (or with some substitute therefor) by means of a clutch J, which is
engaged with the driving hub B³ when the leading cam is to be driven, and is
disengaged from the driving hub when the leading cam is to remain at rest.
In order, moreover, that the same change mechanism which controls the reversing
clutch G may also control the action of the leading cam I, the clutch J that
connects the cam shaft B with its driving hub B³ is operated by a cam K. secured
to the change gear shaft B³. This clutch cam K operates upon the clutch through
the intervention of the lever k, the rod kl, and the clutch fork 2, which engages in
a ring groove of the clutch J. The clutch arm K in the present case is arranged to
disengage the clutch when the leading cam is to stop acting, and to permit the
clutch to engage with the driving hub J when the leading cam is to commence
acting, a spring being provided to move the clutch into engagement with the
driving hub whenever the clutch cam K permits this operation. If it is preferred
that the gripping jaws should advance the bolt blank to the screw-die, the mandrel
need not be constructed to slide end wise, but the standard which carries the gripping
jaws should be constructed to slide upon the frame, and should be connected with
the leading cam so as to be operated by it, this construction being an equivalent
for that represented in the Drawings.

page_text: In order that the blank to be screwed or threaded may be presented to the
gripping jaws D, D, automatically at the proper tines, a magazine or bolt holder L
is provided to contain a supply of bolt blanks, and mechanism is provided to take
one bolt at a time from this bolt holder and present it to the gripping jaws D, D,
which hold the bolt blank from revolving during threading. The bolt holder L
consists mainly of two slabs l, l, connected at their rear ends, with a space between
them a little wider than the thickness of a bolt stem, so that the bolt blanks will
lie horizontally in a column one above the other in said space or cavity, and will
easily slip down the same when the lowest bolt is removed. The heads of the bolt
blanks protrude from the cavity, and are held in place by a head piece l', which
with two check pieces 12, 1, forms the connection of the side slabs of the bolt holder
at its head. The heads of the bolt blanks are thicker than the stems thereof,
consequently the column of superimposed bolts assumes a curved form resembling
the spokes of a wheel, and the head piece and adjacent ends of the side slabs are
curved correspondingly.
In order that the lowest bolt in the bolt holder may be taken therefrom the
bolt mover M is provided. This consists of two arins m, m, connected by a
stock m with a rock shaft m³, which is fitted to rock in bearings connected with
the bolt holder. The upper edges of the arms are curved concentrically with the
rock shaft for the greater part of their length, so that when their curved edges are
beneath the cavity of the bolt holder they act as a stop to prevent the escape of
bolt blanks. The ends of the arms m of the bolt mover are notched sufficiently to
admit the stem of a bolt blank; hence when these notches are brought under the
cavity of the bolt holder they will receive the lowest bolt blank, and when the bolt
mover is subsequently moved by rocking its shaft m² this bolt blank will be moved
laterally from beneath the bolt holder. While the bolt blank is thus moved
laterally it is prevented from turning axially in the bolt mover by the guard ',
which is screwed to the side of the bolt holder with its curved lower edge projecting
over the track in which the angular shoulder of the blank is carried by the bolt
mover. The blank is also prevented from changing its position longitudinally by
ineans of a lateral projection 1 of the head piece l', and by the side of the guard 14,
the said projection being at the outer side of the head of the bolt blank, and the
guard being arranged at its inner side or the shoulder thereof. The bolt mover is
operated at the proper times by means of a cam and a spring acting antagonistically.
The cam N is secured to the cam shaft B and operates upon the bolt mover
through the intervention of the arm n, the rock shaft n', the second rocking arm n²,
the connecting rod n³, the arm n³, and the rock shaft m², which as before stated
is connected with the bolt mover M. The cam in the present case is arranged to
move the bolt mover backward or into the position to receive a bolt, while the
spring is arranged to move the bolt mover forward, or in such manner as to move
the bolt laterally from beneath the bolt holder. The spring used for this purpose
in the machine represented in the Drawings is a helical spring (n³, Figure 7), which
is concealed in a tubular cavity of the rock shaft n¹, and operates by torsion upon
the head of that rock shaft.
In order that the whole column of blanks in the bolt holder may not drop
immediately when the notched ends of the bolt mover are brought beneath the
cavity of the bolt holder movable stops are provided. These stops are by preference
two in number, each consisting of a bar O, which is constructed to slide crosswise
of the cavity of the bolt holder. The case or guide o (Figures 10 and 11) of each
stop is secured to the side of the bolt holder, which also is perforated to permit
the ends of the stops to enter the cavity beneath the lowest blank but one. The
stops 0, 0, are provided with springs o¹, which force them inward. They are
withdrawn from beneath the colum of blanks when the latter are to be permitted
to drop by means of arms o", one for each stop, which operate upon studs pro-
truding from the sides of the stops, and are connected with a rock shaft o³, which
is supported in bearings connected with the bolt holder L. As these stops operate
in concert with the bolt mover advantage is taken of this circumstance to withdraw.

page_text: them by connecting their rock shaft o³ with the rock shaft m² of the bolt mover by
means of connecting arm o*, o*. Hence whenever the rock shaft of the bolt mover
is operated to move the latter to the position for receiving the lowest bolt blank
in the bolt holder the stops 0, 0, are permitted to enter the cavity of the bolt
mover and hold the other bolt blanks from dropping, and whenever the bolt mover
has been moved laterally sufficiently to carry the lowest bolt blank from beneath
the bolt holder the stops 0, 0, are withdrawn to permit the column of blanks to
descend in the bolt holder, so that the lowest bolt blank is in the proper position to
drop into the bolt mover at its next operation.
In order that the bolt blank may be transferred from the bolt mover to the
jaws D, D, the transfer fingers P are provided. These fingers are connected with a
vibrating arm P¹, the shank of one finger p (Figures 5 and 8) being connected
rigidly with said arm, while the shank of the other finger p is pivotted to said
arm, and is provided with a spring which tends to press the pivotted finger towards
the rigid finger, the said spring being secured in the head 22 of the arm P¹. In
order that these fingers may seize the bolt blank, the inner faces of their points
have notches formed in them (one of which is V formed), and the points of the
fingers beyond these notches are slightly bevelled or sloped outward, so that when
the fingers are pressed down endwise upon the shoulder of a bolt blank lying in
the bolt mover, these sloping points are caused to separate and admit the shoulder
of the bolt blank into the finger notches, where it is held by the action of the
finger spring. In order that these springs may be moved endwise upon the bolt
blank, may transfer it to the gripping jaws, and inay return from those jaws, the
fingers are moved by vibrating the finger arm P1 by the action of a cam and spring.
The finger cam Q is secured to the cam shaft B*, so as to be revolved by it, and
operates upon the finger arm P¹ through the arm P2 and rock shaft P³. The spring
which operates antagonistically to the cam Q, is in this example the same
torsion spring (m³, Figure 7) which operates upon the bolt mover shaft n¹, one end
of said spring being connected with the end of the rock shaft P³ of the vibrating
finger arın, through the intervention of a hub P. The object of making the
connection through the intervention of this hub is to enable the force of the spring
to be adjusted by winding it up, and for this purpose the face of the hub P* is
formed with ratchet teeth, any one of which will engage with a corresponding
tooth formed upon the adjacent face of the hub of the rocking arm P. Hence, by
turning the spring hub P, the spring may be wound up and held in that condition
by the engagement of one of its ratchet teeth with the tooth of the finger arm.
The periphery of the tinger cam is so formed as to raise the transfer fingers high
enough to permit the bolt mover to move a bolt blank laterally beneath their
points, to let the fingers be depressed upon the bolt blank so as to seize it, to hold
the fingers at rest while the bolt mover is withdrawn from the bolt seized by the
fingers, and to permit the fingers to descend far enough to hold the bolt blank in
line with the axis of the screw die and the gripping jaws.
The action of the finger cam and spring thus far described is to move the bolt
blank to the axial line of the die and gripping jaws D, D. If these jaws are so
made and opened as to admit the head of the bolt when it is moved downwards
by the fingers, the bolt blank, while being moved downward may be introduced
directly between the gripping jaws, but it is preferred to move the bolt blank
between the jaws by moving it endwise, head foremost. In order that this
movement may be effected, the cam R is provided. This cam has upon one of its
sides a grade which operates upon the lower end of a lever R¹ (Figures 1 and 8),
which is pivotted to a standard of the main frame, and operates at its other end
upon the shaft P³ of the finger arm P'. The action of the cam is to hold the finger
shaft from being moved endwise by the end wise pressure of a spring, and the spring
used in this case for such end wise movement is the same spring n which has before
been described, and which being compressed endwise between the head of the
hollow rock shaft n' and the hub P tends to move that hub, the vibrating finger
arm P', with its fingers P and the shaft to which said arm is secured, endwise in the

page_text: proper direction to carry the fingers towards the gripping jaws. The cam R is
secured to the cam shaft B, which also carries the cams Q, N (for controlling the
operation of the transferring fingers P and the bolt mover M), and the grade of the
cam R is so set relatively to the transfer finger cam Q that when the transfer
fingers have, by their downward movement, carried the bolt to the axial line of the
gripping jaws, said fingers are permitted by the cam R to move sidewise towards
the clamping jaws N, so as to introduce the head of the bolt between them, and
hold the blank in this position until the jaws close upon its square shoulder. After
the jaws have closed upon the bolt blank, the cam R moves the fingers sidewise
away from the jaws, to put them in the proper lateral position for a succeeding
operation.
The cams N, Q, R, which thus control the movement of the bolt blank to the
clamping jaws D, D, are all secured to the cam shaft B* which carries the leading
cam I, so that the bolt mover, the stops, and the transfer fingers act in concert with
each other, and with the advance of the die holder E. Moreover, as the operation
of this cam is controlled by the variable pawl change gearing or mechanism, as
above described, the lengths of the intervals between the successive operations of
feeding bolt blanks can be changed to permit the threads to be cut a greater or less
number of turns upon them. When the machine is employed to cut the screw
threads of bolts which have angular shoulders, either square or polygonal, it is
important that the bolt should be presented to the jaws with the corners of its
angular shoulders in the proper positions to be grasped without bruising in
corresponding angular notches of the said jaws. In order to insure this result the
guard (at the side of the bolt holder) has its lower edge curved, and set above the
lower sides of the notches of the bolt mover a distance slightly greater than the
thickness of the angular shoulder of the bolt between its opposite sides. Hence, the
edge of this shoulder guard cooperates with the bolt mover to form a species
of channel, and to hold the bolt with the corners of its angular shoulder in the
proper axial positions which they should have to be so presented by the transfer
fingers to the gripping jaws that the angles of the bolt shoulder may correspond
with the angles of the notches of the jaws. This shoulder guard is also used in the
machine, as before stated, to prevent the bolt from excessive longitudinal movement
in the bolt mover; but a separate guard may be used for that purpose. In order
that the bolt blank may be moved by the transfer fingers to its exact position
axially of the spring jaws and die, the spring n³ is employed to cause the descent
of the transfer fingers, and a stop S employed to limit their descending
movement; an adjustable bumper s (Figure 8) also is fitted to the finger arm P¹ to
strike the stop S, and the precise position at which the bolt is presented by the
transfer fingers can be determined by adjusting this bumper, or if preferred by
using a fixed bumper and making the stop adjustable.
The
The die by which the threading or screwing is effected is by preference a solid
die, and as before stated is carried by the die chuck or holder E, which is secured
to the head of the revolving mandril F. The solid die if made according to the
last part of my Invention, is a block of steel of conoidal form (as represented at T,
Figures 12, 13, and 14), having upon its periphery several projections or teeth t
which fit into corresponding notches formed in the cavity of the die chuck E.
butt of this die is flat, so that it may set truly against the head f of the die
mandril F, and the die is held there by the action of the die chuck, which is
composed of the screwed sleeve e (Figure 12) and the screwed gland e¹, the first of
which bears against the inner side of the mandrel head and holds the gland e¹ and
the die within firmly in place. Dies of this construction are readily forged to the
exact shape required by means of suitable forging dies used in a drop press, the
cavity of the die conforming in form and size with the cavity of the die chuck in
which the die is to be used. The die is then drilled and cut while held in a die
chuck corresponding with that of the threading machine, so that the die will fit
the chuck of the threading machine without any dressing up. Hence, the cost of
making dies for the screw threading machine is reduced to a minimum. On the

page_text: other hand the die is free from any groove which requires a milling operation or a
planing operation to form it, and which by nicking the body of the die renders it
liable to crack in the hardening operation to which the die is necessarily subjected.
When the threading machine is to be put to work, the variable pawl mechanism
is adjusted according to the number of turns of screw thread to be cut upon the
bolts. The bolt blanks are put into the bolt holder L by a child; and by the
automatic operation of the machine the bolt blanks are taken from the bolt holder
one at a time by the bolt mover, the downward movement of the column of the
bolt blanks in the bolt holder is temporarily checked by the stops, the bolt blank is
presented for the action of the transfer fingers and is seized by them, the bolt mover
is withdrawn from beneath the bolt blank, which is then transferred to the gripping
jaws; these jaws seize the blank; the die advances upon it and cuts the thread to
the required extent; the die backs off of the bolt, by reason of the reversal of the
movement of the mandrel, and the jaws are opened to permit the threaded bolt to
drop. If the bolt hangs in the jaws it is knocked downwards from them by the
downward movement of the next succeeding bolt blank carried by the transfer
fingers. The adjustment of the machine to the cutting of threads having a
different number of turns is effected by changing the position of the adjustablo
crank pin h³, as before described. It is expedient that the time at which the
feeding of the bolt commences relatively to the time of reversal of movement of
the screw die should be capable of being changed, and this capacity is given in the
machine above described by constructing the cam grade of the clutch cam K. of two
parts, one of which is movable concentrically of the other, so that the grade as a
whole may be lengthened or shortened in the direction of the periphery of the cam.
The movable part of the cam grade is secured by a clamp screw.
The speed at
which the screw die is advanced or pushed against the point of the bolt stem
should correspond with the pitch of the screw thread to be formed. In order that
the same leading cam I may be employed to advance the screw dies for screw
threads of different pitches, the rocking arm is slotted so that the pin 6 through
which that arm operates upon the slide can be set at a greater or less distance
from the rock shaft, thus causing the slide and the mandrel and screw die which
are connected with the slide to be moved with greater or less speed by the same
movement of the leading cam I. In order that the bolt holder and the parts con-
nected with it may be set to the proper positions to suit the blanks to be threaded,
the standard U which supports the bolt holder is constructed with a foot u, which
can be moved along the rest V which supports it, and can be secured in any desired
position by a screw bolt. For purposes of adjustment some of the rocking arms of
the machine are constructed with split hubs, and are secured to their shafts by
clamping the split hubs by clamp screws; the ends of some of the arms also are
slotted so that the pins by which the arms are connected with other parts may
have their positions changed.
The combination of the variable pawl change gearing with reversing gearing, as
above described by me, may be used with advantage in machines for other
purposes than threading bolts.
I claim as the Invention to be secured by Letters Patent,-
First. The combination, substantially as set forth, of the change gearing shaft and
its cams, the ratchet wheel, variable vibrating pawl, and adjustable crank pin.
Second. The combination, substantially as before set forth, of the clutch, shifting
pins, shifting cam, pin cams, cam shaft of the change gearing, ratchet wheel,
vibrating pawl, and adjustable crank pin.
Third. The combination, substantially as before set forth, of the jaws for holding
the bolt blank stationary, the revolving sliding mandril, the bolt holder, the bolt
mover, the transfer fingers, and the variable pawl change gearing.
Fourth. The combination, substantially as before set forth, of the transfer fingers,
finger cam, finger cam shaft, driving hub and clutch, with the variable pawl change
gearing.
Fifth. The combination, substantially as before set forth, of the bolt mover, bolt

page_text: mover cam, cam shaft, driving' hub and clutch, with the variable pawl change
gearing.
Sixth. The combination, substantially as before set forth, of the bolt holder, the
bolt mover, the stops for checking the descent of the blanks in the bolt holder, and
the transfer fingers which take the bolt from the bolt mover.
Seventh. The combination, substantially as before set forth, of the gripping jaws
for holding the blanks stationary, the bolt holder, the bolt mover, the transfer
fingers arranged to move both endwise and sidewise towards and from the gripping
jaws, and the variable pawl change gearing.
Eighth. The combination, substantially as before set forth, of the bolt holder, the
bolt mover, and the shoulder guard, whose lower edge operates on the shoulder of
the blank while in the bolt mover.
Ninth. The combination, substantially as before set forth, of the bolt mover, the
shoulder guard, and the transfer fingers.
Tenth. The combination, substantially as before set forth, of the bolt holder and
bolt mover, with a shoulder guard whose edge operates on the shoulder of the
blank while in the bolt mover, and whose side is arranged in the proper position to
operate on the inner side of the head of the blank and prevent excessive longi-
tudinal movement of the blank.
Eleventh. The combination, substantially as before set forth, of the bolt mover,
the shoulder guard, the transfer fingers, and the gripping jaws to which the blank
is presented by the transfer fingers.
Twelfth. The combination, substantially as before set forth, of the die holder, the
revolving sliding mandrel, the leading cam, the slotted rocking arm which enables
the speed with which the die is advanced to be varied, and the variable pawl
change gearing.
Thirteenth. The combination, substantially as before set forth, of the conoidal
screw die, with a die chuck, consisting of the screwed sleeve and screwed gland
operating in connection with the mandrel head.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand
and seal, this Twenty sixth day of August, in the year of our Lord One
thousand eight hundred and eighty.
SYDNEY PITT. (L.S.)