Improvements in Screw Making Machines.
Year: 1897

page_text: Date of Application in the United Kingdom, 29th Mar., 1897
Complete Left, 28th Dec., 1897-Accepted, 5th Mar., 1898
Improvements in Screw Making Machines.
I, THOMAS JAMES SLOAN, of 98, Avenue de St. Mande, Paris, France, Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved machine for threading wood and other
screws, which comprises several sliding headstocks by which the blank to be
threaded is presented to the several tools by which the different phases of the
screw threading operation are successively performed, the proportion of work
done by each being in decreasing progression so that the last tool of the series has
merely to perform the finishing operation. By this means a large production may
be obtained and more especially a superior quality of screw, each tool successively
correcting the work of the preceding one, should such be incomplete or imperfect
owing to the breaking of the tool or through wear or imperfect adjustment. As
the bulk of the work of cutting the thread will be performed by the first tools,
the last one having but light work to perform will always be in perfect condition
for rectifying the screw produced by the preceding tools. This result has never
hitherto been obtained, the same tool being required to perform the twelve cuts
recognised as necessary in threading wood screws.
My improved machine is composed of two entirely distinct parts viz.: (1) the
feed apparatus and (2) the screw threading apparatus. The first of these apparatus
is of the simplest kind and will be described hereinafter, but I will first describe
the screw threading apparatus. The threading of the screws is effected in twelve
cuts and in a rational manner by means of a device whereby the amount of feed
of the tools up to the work is the less as there remains less material to be removed
so that the last three cuts remove very little material and serve to polish the work.
In the accompanying drawings Figure 1 represents a front elevation of the
machine. Figure 2 18 a section on X X looking from the right-hand
end, of the machine. Figure 3 is a plan of the mechanism for the
circulating headstocks or chuck carriers. Figure 3bi is a modification of this
mechanism Figure 4 is a plan of the tool-carrying slide rest. Figure 5 is a face
view and Figure 6 a plan of the feeder. Figure 7 is a detail of said feeder.
The blank to be screw threaded is held between the pair of dogs a, Figure 1,
of the chuck pressed together by a strong spring b, the whole being mounted in an
inner frame c capable of receiving rotary motion and to the upper end of which is
keyed a pinion & whose teeth are inclined at an angle of 45° and to which motion
is imparted by an elongated worm e whose threads are also inclined at 45°. The

page_text: inner frame c is mounted between the top and bottom of a box-like sliding head-
stock (Figures 1 and 2) having grooves y adapted to slide along rails the whole
length of the machine and successively occupy the positions 1, 2, 3, 4, 5, and 6.
The guide rails are interrupted at the ends and completed by movable guide rails
fixed on two slides h h (Figures 1 and 3) movable back and forth by connecting
rods and cranks i to which alternate angular motion is imparted by a rack and
toothed segment (Figure 2).
Supposing the five sliding headstocks to occupy the position shewn, No. 6,
holds in its dogs a finished screw, is supported in the movable guide rails, and has
been moved backwards from the position 6 to position 7. At this moment another
worm J now gears with a rack on each sliding headstock and moves it along to
position 8 where it is again moved forwards to the position 1 whence it is moved
to position 2 by the pusher actuated by cam m moving all the sliding headstocks
along so as to bring them respectively to positions 6, 5, 4, 3, and 2. The feeder
then removes the finished screw and places a blank between the dogs. The same
series of operations are then repeated and the screw is presented successively to
the four tools which first roughly form and then finish it.
The circulating movement of the sliding head-stocks may also be imparted by
means of the arrangement shewn in Figure 3b, which consists of a chain A to
each link of which is fixed a sliding headstock similar to those above described,
the chain passing around two pinions B B¹.
The tools are mounted on a bar A (Figure 4) pivoted at o and occupying the
positions 1, 2, 3, 4, the bar being mounted in a slide rest E sliding up and down
between gibs B B₁ (Figures 1 and 4) which are themselves mounted on a slide C
(Figure 2) capable of receiving forward and backward motion through a con-
necting rod and crank D (Figure 2). The slide rest E is connected by lugs 9
and 10 (Figure 1) to rods t t connected at their lower ends by a centrally apertured
crosshead 11 to receive the end of a shaft having a collar which bears upon said
crosshead 11 and upon which shaft is keyed the leading screw 12. Motion is
imparted to the shaft by a pair of mitre wheels 13, 14. The shaft can slide
through wheel 13 which is in one with a pinion that drives a wheel keyed on the
cam shaft n (Figures 1 and 2). The shaft n has two cams p pl of which the former
engages the nut 15 with the leading screw 12 when the tool-holding slide rest
is to be moved downwards; and when said slide rest is at the lower point of its
stroke the nut suddenly becomes disengaged and the tool-holding apparatus is
raised by a strong spring, but in order to prevent shock by a too sudden return
motion the crosshead 11 has a bracket y carrying a roller r which runs against
the lower cam p¹ keyed on shaft n so as to control the return motion. The nut 15
is constantly pressed against the cam by a spring. The tool-holding slide-
rest carries a steel templet r (Figures 1, 2, and 4) having the exact profile of the
lower part of the screw, and bearing constantly against the cam S which makes a
complete revolution at each cut. The cam is provided with a notch to allow of
the disengagement of the tool after the cut is terminated. The feed of the tool
is produced with the aid of an abutment on bar A bearing constantly against a
cam (Figure 4) which makes one revolution for every four cuts.
The cam is
divided into four parts; during the first cut the abutment bears upon the part a b
during the second cut upon the part bc, during the third upon the part c d, and
returns to the initial position during the fourth cut. The bar A being pivoted
at o the feed will be the less the nearer the tool is to the pivot, that is to say the
nearer the screw is to completion. A special arrangement is employed to enable
the tools to be so regulated that the tools 2, 3, 4 shall coincide exactly with the
thread traced by the tool 1. For this purpose the tool is mounted in a clamp fi
(Figures 1 and 2) which may be vertically adjusted by two set screws. Opposite
each screw is a grooved backstay V (Figure 2) to resist the pressure of the tool,
these backstays being mounted on a reciprocating slide C¹ moved back and forth
by a connecting rod and crank D¹ so as to give passage to the screws when the
sliding headstocks are moved along.

page_text: The action of the apparatus is as follows:-When the headstock is moved from
2 to 3 the cam
engages the nut 15 which engages it in the leading screw causing
its shaft and crosshead 11, rods t t', and also the tool-holding slide rest to move
downwards. When the cut is terminated the slide rest E comes forward and moves
the tools out of work at same time that the nut 15 is disengaged and the tool
holder rises, cam u makes one fourth of a turn and the second cut is made and then
the third. During the next or fourth passage of the tools the latter make no cut,
to allow of the shifting along of the headstocks, the feeding and pointing of the
screw which is effected in the ordinary manner when the blank is placed in the
chuck at 2.
The mechanism represented in Figures 5, 6, and 7 removes the finished screw
and replaces it by a screw-blank. This operation is performed with the aid of a
double nipper (Figure 7) the finished screw being received at a whilst the screw-
blank is held at b. The nippers are mounted on the extremity of a lever A turned
about an axis o by means of a toothed sector and rack D. The axis o may receive
to and fro motion in a longitudinal direction by means of a cam B.through the
jointed lever connections a, b, c, d, and the rack D is operated by cam E through
the jointed lever connections e, f, g, h. The nipper takes the screw-blanks from
the lower end t of a feed tube T which has a funnel mouth into which the blanks
are dropped one by one with the aid of the following mechanism:-The blanks
are placed pell-mell in a slowly revolving tray P into which a fork F pivoted at f
dips at intervals and then rises, carrying with it some of the blanks engaged
between its members, this movement being produced by a cam E¹, rods G G, and
lever H, after which fork F receives from cam E' a slight jerking motion by which
the blanks are caused to pass to point k at which is placed a device somewhat
resembling the anchor escapement of a watch, the teeth being replaced by the
screw-blanks. The blanks thus pass one by one and drop through a guide into
the funnel of tube T. The oscillatory motion of escapement K which regulates
the passage of the blanks is transmitted from cam shaft M by means of a cam N
keyed on said shaft and the connecting rods and levers m, n, 1', q. The shaft R is
stationary while the cam shaft M and shaft which carries the table P rotate. The
feeding of the screw-threading apparatus is effected as before mentioned when the
headstock is in position 2 at which moment the feed arm seizes by the spring
nipper b a screw-blank at t whereupon the arm is brought by the rack opposite the
dogs of the chuck and seizes by the second nipper a the finished screw which it
withdraws and inserts the blank in its place, after which it again rotates and
allows the finished screw to drop into a box provided for the purpose, the operation
being then repeated, and so on. Each screw delivered corresponds to one revolu-
tion of shaft M and one oscillation of escapement K, thus every time a blank is
seized at t one will be supplied by K.
It is to be understood that the forms, dimensions, and details of arrangement of
the various parts constituting this improved machine, may be varied without in
any way affecting the nature of the invention.
Doted this 20th day of Masah
1905

page_text: be performed to be particularly described and ascertained in and by the following
statement:
This invention relates to an improved machine for threading wood and other
screws, which comprises several sliding headstocks by which the blank to be
threaded is presented to the several tools by which the different phases of the
screw threading operation are successively performed, the proportion of work
done by each being in decreasing progression so that the last tool of the series has
merely to perform the finishing operation. By this means a large production may
be obtained and more especially a superior quality of screw, each tool successively
correcting the work of the preceding one, should such be incomplete or imperfect
owing to the breaking of the tool or through wear or imperfect adjustment. As
the bulk of the work of cutting the thread will be performed by the first tools,
the last one having but light work to perform will always be in perfect condition
for rectifying the screw produced by the preceding tools. This result has never
hitherto been obtained the same tool being required to perform the twelve cuts
recognised as necessary in threading wood screws.
My improved machine is composed of two entirely distinct parts viz.: (1) the
feed apparatus and (2) the screw-threading apparatus. The first of these apparatus
is of the simplest kind and will be described hereinafter, but I will first describe
the screw-threading apparatus. The threading of the screws is effected in twelve
cuts and in a rational manner by means of a device whereby the amount of feed
of the tools up to the work is the less as there remains less material to be removed
so that the last three cuts remove very little material and serve to polish the work.
In the drawings accompanying my Provisional Specification Figure 1 represents
a front elevation of the machine. Figure 2 is a section on X X', looking from the
right-hand end, of the machine. Figure 3 is a plan of the mechanism for the
circulating headstocks or chuck carriers. Figure 3b is a modification of this
mechanism Figure 4 is a plan of the tool-carrying slide rest. Figure 5 is a face
view and Figure 6 a plan of the feeder. Figure 7 is a detail of said feeder..
The blank to be screw-threaded is held between the pair of dogs a, Figure 1,
of the chuck pressed together by a strong spring b, the whole being mounted in an
inner frame c capable of receiving rotary motion and to the upper end of which is
keyed a pinion d whose teeth are inclined at an angle of 45° and to which motion
is imparted by an elongated worm e whose threads are also inclined at 45°. The
inner frame c is mounted between the top and bottom of a box-like sliding head-
stock (Figures 1 and 2) having grooves g adapted to slide along rails the whole
length of the machine and successively occupy the positions 1, 2, 3, 4, 5, and 6.
The guide rails are interrupted at the ends and completed by movable guide rails
fixed on two slides h h¹ (Figures 1 and 3) movable back and forth by connecting
rods and cranks i to which alternate angular motion is imparted by a rack and
toothed segment (Figure 2).
Supposing the five sliding headstocks to occupy the position shewn, No. 6
holds in its dogs a finished screw, is supported in the movable guide rails, and has
been moved backwards from the position 6 to position 7. At this moment another
worm J now gears with a rack on each sliding headstock and moves it along to
position 8 where it is again moved forwards to the position 1 whence it is moved
to position 2 by the pusher / actuated by cam m moving all the sliding headstocks
along so as to bring them respectively to positions 6, 5, 4, 3, and 2. The feeder
then removes the finished screw and places a blank between the dogs. The same
series of operations are then repeated and the screw is presented successively to
the four tools which first roughly form and then finish it.
The circulating movement of the sliding head-stocks may also be imparted by
means of the arrangement shewn in Figure 3b, which consists of a chain A to
each link of which is fixed a sliding headstock similar to those above described,
the chain passing around two pinions B B¹.
The tools are mounted on a bar A (Figure 4) pivoted at o and occupy the
positions 1, 2, 3, 4, the bar being mounted in a slide rest Ę sliding up and down

page_text: between gibs B B¹ (Figures 1 and 4) which are themselves mounted on a slide C
(Figure 2) capable of receiving forward and backward motion through a con-
necting rod and crank 1) (Figure 2). The slide rest E is connected by lugs 9
and 10 (Figure 1) to rods t t connected at their lower ends by a centrally apertured
crosshead Il to receive the end of a shaft having a collar which bears upon said
crosshead 11 and upon which shaft is keyed the leading screw 12. Motion is
imparted to the shaft by a pair of mitre wheels 18, 14. The shaft can slide
through wheel 13 which is in one with a pinion that drives a wheel keyed on the
cam shaft n (Figures 1 and 2). The shaft n' has two cams p p of which the former
engages the nut 15 with the leading screw 12 when the tool-holding slide rest
is to be moved downwards; and when said slide rest is at the lower point of its
stroke the nut suddenly becomes disengaged and the tool-holding apparatus is
raised by a strong spring, but in order to prevent shock by a too sudden return
motion the crosshead 11 has a bracket 9 carrying a roller which runs against
the lower cam 21 keyed on shaft a so as to control the return motion. The nut 15
is constantly pressed against the camp by a spring. The tool-holding slide-
rest carries a steel templet r (Figures 1, 2, and 4) having the exact profile of the
lower part of the screw and bearing constantly against the cam S which makes a
complete revolution at each cut The cam is provided with a notch to allow of
the disengagement of the tool after the cut is terminated. The feed of the tool
is produced with the aid of an abutment on bar A bearing constantly against a
cam (Figure 4) which makes one revolution for every four cuts. The cam is
divided into four parts; during the first cut the abutment bears upon the part a b,
during the second cut upon the part c, during the third upon the part c d and
returns to the initial position during the fourth cut. The bar A being pivoted
at o the feed will be the less the nearer the tool is to the pivot, that is to say the
nearer the screw is to completion. A special arrangement is employed to enable
the tools to be so regulated that the tools 2, 3, 4, shall coincide exactly with the
thread traced by the tool 1. For this purpose the tool is mounted in a clamp f¹
(Figures 1 and 2) which may be vertically adjusted by two set screws. Opposite
each screw is a grooved backstay V (Figure 2) to resist the pressure of the tool,
these backstays being mounted on a reciprocating slide C¹ moved back and forth
by a connecting rod and crank D¹ so as to give passage to the screws when the
sliding headstocks are moved along.
The action of the apparatus is as follows:-When the headstock is moved from
2 to 3 the camp engages the nut 15 which engages it in the leading screw causing
its shaft and crosshead 11, rods t t¹, and also the tool-holding slide rest to move
downwards. When the cut is terminated the slide rest C comes forward and moves
the tools out of work at same time that the nut 15 is disengaged and the tool
holder rises, cam u makes one fourth of a turn and the second cut is made and then
the third. During the next or fourth passage of the tools the latter make no cut,
to allow of the shifting along of the headstocks, the feeding and pointing of the
screw which is effected in the ordinary manner when the blank is placed in the
chuck at 2.
The mechanism represented in Figures 5, 6, and 7 removes the finished screw
and replaces it by a screw-blank. This operation is performed with the aid of a
double nipper (Figure 7) the finished screw being received at a whilst the screw-
blank is held at b. The nippers are mounted on the extremity of a lever A turned
about an axis o by means of a toothed sector and rack 1). The axis o may receive
to and fro motion in a longitudinal direction by means of a cam B through the
jointed lever connections a b c d and the rack D is operated by cam E through
the jointed lever connections e f g h. The nipper takes the screw-blanks from
the lower end t of a feed tube T which has a funnel mouth into which the blanks
are dropped one by one with the aid of the following mechanism:-The blanks
are placed pell-mell in a slowly revolving tray P into which a fork F pivoted at f
dips at intervals and then rises, carrying with it some of the blanks engaged
between its members, this movement being produced by a cam E¹, rods G G₁, and
lever H after which fork F receives from cam E¹ a slight jerking motion by which

page_text: the blanks are caused to pass to point k at which is placed a device somewhat
resembling the anchor escapement of a watch, the teeth being replaced by the
screw-blanks. The blanks thus pass one by one and drop through a guide / into
the funnel of tube T. The oscillatory motion of escapement K which regulates
the passage of the blanks is transmitted from cam shaft M by means of a cam N
keyed on said shaft and the connecting rods and levers m n p. q. The shaft R is
stationary while the cam shaft M and shaft which carries the table P rotate. The
feeding of the screw-threading apparatus is effected as before mentioned when the
headstock is in position 2 at which moment the feed arm seizes by the spring
nipper 6 a screw-blank at t whereupon the arm is brought by the rack opposite the
dogs of the chuck and seizes by the second nipper a the finished screw which it
withdraws and inserts the blank in its place, after which it again rotates and
allows the finished screw to drop into a box provided for the purpose, the operation
being then repeated, and so on. Each screw delivered corresponds to one revolu-
tion of shaft M and one oscillation of escapement K, thus every time a blank is
seized at t one will be supplied by K.
It is to be understood that the forms, dimensions, and details of arrangement of
the various parts constituting this improved machine may be varied without in
any way affecting the nature of the invention.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
The herein described machine for threading wood and other screws, disposed
substantially as specified and characterized by the following features:-
(1) The combination of a plurality of headstocks or chuck carriers shifting so
as to present the blanks successively to a plurality of tools, each of which performs
one stage of the threading operation, commencing by roughly shaping and ter-
minating by the finishing operation, the action of one tool being rectified by that
of the other whereby screws entirely free from all defects are produced;
(2) The rectilinear arrangement of the headstocks which permits of driving by
a single worm all the headstocks in work and of successively presenting the blank
to all the tools without interrupting the rotary motion of the machine and so that
the threading is divided into several operations, besides enabling the whole of the
tools to be easily regulated;
(3) The tool-holder slide-rest arranged in the manner described for permitting
of obtaining the progressive advance of the cut of all the tools at one time by
means of a single cam;
(4) The arrangement of the tool holders whereby all the tools may be in work
at one time and be made to follow the profile of the screw by means of a single
cam;
(5) The arrangement for effecting a regular and uninterrupted feed in the
apparatus;
(6) The vertical adjustment of the tool by an adjusting screw or other means
enabling the tool to exactly follow the thread made by the preceding tool which
adjustment can only be effectively obtained by raising and lowering the tool in the
direction of the length of the screw.
100%
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.