Improvements in Machinery for the Manufacture of Metallic Screws and Screw Bolts and other Metallic Articles having Screw Threads upon them.
Year: 1888

page_text: Date of Application, 1st Mar., 1888
Complete Specification Left, 26th Nov., 1888
Complete Specification Accepted, 5th Feb., 1889
Improvements in Machinery for the Manufacture of Metallic Screws
and Screw Bolts and other Metallic Articles having Screw
Threads upon them.
I JOHN SHELDON of No. 10 St. Augustine's Road Birmingham in the County of
Warwick Mechanical Engineer do hereby declare the nature of this Invention to be
as follows:-
My invention consists of the hereinafter described improvements in or additions to
the screw machinery ordinarily employed for the manufacture of wood screws and
other like articles.
In screw making machinery as ordinarily constructed the screw blank or article on
which a screw thread is to be made is put into rotation and a cutter or cutters is or
are made to advance with a motion parallel to the axis of the rotating blank and
thereby to cut away portions of the blank the uncut away portion of the blank
constituting a screw thread.
According to my invention I dispense with the ordinary cutter or cutters and
substitute either pressing tools or rotary cutters as herein after explained. When I
employ pressing tools I form the said tools of hardened steel circular discs the
peripheries of which have in cross section the figure of one thread of the screw to be
made and the space on each side of the said thread together with one face of the
threads on each side of the said complete thread. These circular pressing discs are
mounted on axes on which they are free to rotate.
A pressing tool of the kind described is situated at opposite sides of the blank
operated upon so that the pressure of one of the said tools is balanced by that of the
other. These pressing tools are pressed forcibly against the rotating blank with a
slow motion in a line parallel to the axis of the rotating blank and by their pressure
displace those portions of the blank on which they operate the undisplaced portions of
the blank constituting a screw thread. The said pressing discs may either have an
independent rotary motion given to them or they may have only the rotary motion
given to them by the rotating blank on which they operate.

page_text: In some cases particularly when metals are to be operated upon which have little
ductility use in place of the pressing discs described rotary cutters. These rotary
cutters have the figure of the spaces between two opposed faces of the screw thread to
be made and their acting parts are made into cutting surfaces. The said rotary
cutters are mounted on axes by which rapid rotary motion is given to them.
In addition to the said rotary motion they have slow motion in a line parallel to the
axis of the blank.
By the motions described combined with the slow rotary motion of the supported
blank the required portions of the blank are cut away leaving the required screw
thread.
W. T. WHITEMAN,
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Machinery for the Manufacture of Metallic Screws
and Screw Bolts and other Metallic Articles having Screw
Threads upon them.
I JOHN SHELDON of No. 10 St. Augustine's Road Birmingham in the County of
Warwick, Mechanical Engineer do hereby declare the nature of my Invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
=
My invention consists of the hereinafter described improvements or changes in or
additions to the screw machinery ordinarily employed for the manufacture of wood
screws screw bolts and other articles having screw threads upon them, such for
example, as augers and gimblets gas tubes and the like.
In screw making machinery as ordinarily constructed the screw blank or article on
which a screw thread is to be made is put into rotation and a cutter or cutters is or
are made to advance with a motion parallel to the axis of the rotating blank and
thereby to cut away portions of the blank, the uncut away portion of the blank
constituting a screw thread.
According to my invention I dispense with the ordinary cutter or cutters and
substitute either pressing tools or rotary cutters as hereinafter explained. When I
employ pressing tools I form the said tools of hardened steel circular discs the
peripheries of which have in cross section the figure of one thread of the screw to be
made and the space on each side of the said thread together with one face of the
threads on each side of the said complete thread. These circular pressing discs are
mounted on axes on which they are secured by keys and screw nuts.
A pressing tool of the kind described is situated at opposite sides of the blank
operated upon so that the pressure of one of the said tools is balanced by that of the
other. These pressing tools are pressed forcibly against the rotating blank with
a slow motion in a line parallel to the axis of the rotating blank and by their pressure
displace those portions of the blank on which they operate the undisplaced portions of
the blank constituting a screw thread. The said pressing discs may either have an
independent rotary motion given to them or they may have only the rotatory motion
given to them by the rotating blank on which they operate.
In some cases particularly when metals are to be operated upon which have little
ductility I use in place of the pressing discs described rotary cutters. These rotary
cutters have the figure of the space between two opposed faces of the screw thread to
be made and their acting parts are made into cutting surfaces. The said rotary
cutters are mounted on axes by which rapid rotary motion is given to them.
In addition to the said rotary motion they have slow motion in a line parallel to
the axis of the blank.
By the motions described combined with the slow rotary motion of the supported
blank the required portions of the blank are cut away leaving the required screw
thread.

page_text: 1 will now proceed to describe with reference to the accompanying Drawings the
manner in which my invention is to be performed.
Figure 1 represents in plan; Figure 2 in side elevation and Figures 3 and 4
elevations of the opposite ends of machinery for the manufacture of screws containing
my improvements: Figure 5 is a vertical section of the machinery taken on the
line A A Figure 1; Figure 6 represents in edge view and side elevation one of the
pressing discs hereinafter described and Figure 7 represents in side and end elevation
one of the rotary cutters hereinafter described; Figure 8 represents an end elevation
and Figure 9 a side elevation of a portion of the machinery drawn to a large scale
and Figure 10 represents in side elevation drawn to a large scale that portion of the
mechanism which effects the traversing and compensating motions of the worm by
which the traversing motion of the tools is produced and Figure 11 is an end elevation
of the same partly in section. Figures 12, 13 and 14 represent mechanism
for effecting the compensatory motion of the worm when the blank is operated upon
several times by the pressing tools. As that part of the mechanism of the
machinery represented which effects the feeding of the blanks on which screw threads
are to be formed as well as that part of the mechanism by which the blanks to be
operated upon are gripped and made to rotate differ in no essential respect from
mechanism commonly employed in screw cutting machinery I do not think it necessary
to describe them in detail. I will however describe such modifications of the said
mechanisms as are required in adapting to the machinery the special screw threading
appliances which constitute my invention.
C,
The blank on which a screw thread is to be formed is represented at a in Figures 2
and 8 and the gripping spindle and jaws by which the said blank a is hold and rotated
is marked b in the said Figure 2. The circular tools or pressing discs are marked c
and d. One of the said pressing discs c d is shown separately drawn to a large scale
in Figure 6. Each of the said discs is made of hardened steel and, as will be seen
by referring to the edge view of Figure 6, its periphery has in cross section the figure
of one thread of the screw to be made and the space on each side of the said thread
together with one face of the threads on each side of the said complete thread. The
said pressing discs c, d are carried on spindles or axes supported in the tubes or
sleeves e, fand the said dises as will be seen by referring to the drawings of the
machine press and operate upon opposite sides of the blank a and are inclined in
opposite directions as will also be seen by the drawings. The said discs d may
either turn freely on the spindles carrying them or be fixed thereto. In the former
case the spindles themselves are fixed in the sleeves e, f and the discs c, d have no
rotary motion excepting that communicated to them by the rotating blank a situated
between them and on which they are operating. In the latter case, that is to say,
when the pressing discs have an independent rotary motion communicated to them
they are fixed to the ends of the spindles carrying them and rotate with the said
spindles. The spindles in this case turn freely in the sleeves e, f and have rotary
motion communicated to them by the gearing represented and which I will now
proceed to describe. A rotary motion is communicated to the extra shaft g from the
primary driving shaft by the gearing represented at the right hand end of Figures 1
and 2 and also in the end elevation Figure 3, the gearing for driving the extra shaft g
consisting of the pulley 1 on the shaft 2 carrying the pinion 3 gearing into the wheel 4
which gears with the wheel 5 on the extra shaft g. A toothed on the shaft
y com-
municates motion to the broad toothed wheel i. The toothed wheel k which gears with
the broad toothed wheel i is carried by a sleeve which works freely on the shaft 1.
The said sleeve of the wheel & also carries two bevilled toothed wheels m and n and
the said wheels m and n gear respectively with the bevilled toothed wheels p and
I on
the ends of the shafts carrying the pressing discs c and d. By means of this gearing.
rotatory motion from the extra shaft g is communicated to the shafts or spindles of
the pressing discs c and d in the required directions.
In place of the pressing discs c and d rotary cutters may be employed of the kind
represented in Figure 7. It will be seen by an examination of the said Figure 7 that
both the periphery of the rotary cutter and its inclined sides are cutting surfaces

page_text: having in section the figure of the space between two opposed faces of the screw
threads to be cut. In using the said rotary cutters they are fixed on the shafts in the
sleeves e, in place of the pressing discs c and d and have a rotary motion communi-
cated to them by the following modification of the gearing.
When the pressing tools c, d are employed they have rotation in the same direction
and the arrangement of gearing represented in Figures 1, 2 and 3 is such as is suitable
to give rotation to them in the required direction. When in place of the pressing
tools c d rotary cutters of the kind represented in Figure 7 are employed the gearing
represented requires to be modified. Both the cutters rotate in the same direction but
that direction is the reverse of the direction in which the pressing tools c d rotate,
hence the necessity of modifying the gearing when rotary cutters are employed so as
to reverse the motion of the shafts carrying them. This is effected by the removal of
the broad toothed wheel i from the shaft on which it is represented and fixing the said
broad toothed wheel i on the shaft of the wheel in place of the said wheel 7. The
said broad toothed wheel i will in this case gear directly with the toothed wheel k
and drive the cutters without the reversal of motion which it effects when it is made
to gear the wheels h and together.
In addition to the rotary motion which must be communicated to the rotary cutters
and may be communicated to the pressing discs, these tools require to have a sliding
or traversing motion parallel to the axis of the blank so that besides rotating they are
closed upon one another and travel from near the head of the blank towards the point
end of the blank and on nearing the point end the said tools still further close and
approach one another so as to operate upon the tapering point of the blank. Having
finished the point of a screw the said tools open or separate from one another and
rapidly return in their open condition towards the head of the blank where they again
close and operate a second time on the rotating blank and complete the partially
formed thread. If necessary the thread may be operated upon three or more times by
the tools. The broad toothed wheel i permits of the required traversing motion of
the tools and their appendages, while preserving the gearing of the parts by which
the rotary motion of the pressing tools or rotary cutters is effected.
I will now describe the mechanism whereby the opening and closing or the
approaching and receding motions of the said tools are produced. The wheel 4 has
a sleeve carrying the pinion 6 which gears with the large toothed wheel 7 driving
the shaft S. The end of the shaft 8 carries the cam 9 (see Figures 3 and 8) which
operates on the lever 10 and the lever 10 lifts the rod 11 which operates on the
lever 12 which carries the sleeve 13 (best seen in Figure 8) working on the
excentric 14. On the sleeve 13 is a projection 15 bearing against the roller 16 on
the sleeve e carrying the pressing tool c. The other sleeve carrying the pressing
tool is at the same time made to operate on the blank by being pressed against it
by means of the arm 17 carrying a roller 18 which roller is supported by the
projection 19 on the sleeve 20 working on the excentric 21. The sleeve 20 carries
an arm 22 connected with the arm 23 by means of the rod 24 the said arm 23 being
situated on the sleeve 18 herein before described. By the action of the parts last
described the closing of the tools is effected and while thus closed the tools perform
their traversing motion from near the head of the blank to its point and thereby effect
the first cut or impression on the rotating blank. As the tools in their traversing
motion approach the point of the blank they require to be further closed in order
to produce the thread on the tapering point of the blank. This further closing of the
tools near the end of their traversing motion is effected by additional small projections
on the sleeves 13 and 20. One of these projections is marked 19" on the sleeve 20
Figure 2.
One cut or impression of the thread is effected on the blank and the tools opened
and by a sliding motion returned to their normal or original position during each
rotation of the cam 9.
I will now describe the arrangement by which after the rotating pressing tools
or discs or rotary cutters have been closed upon the blank the required pressure is
put upon the said tools and maintained during their action on the blank; 25 is a

page_text: toothed wheel driven by the pinion 26 (see Figure 2) from the shaft 27 which receives
motion from the wheel 28 on the shaft 8 (see Figure 1) through the wheel 27ª on the
said shaft 27. On the side of the wheel 25 is a face cam 29 against which the end
of the rod 30 bears. By the rotation of the wheel 25 the cam 29 is made to urge
forward the rod 30 which carries at its end the incline 31. In Figure 1 the rod 30
is represented at the lowest point of the cam 29. The advance of the incline 31
advances the end of the lever 32 the return motion of the said incline being
produced by the spring 37. The advance motion of the lever 32 is transmitted
through the toggle cennecting rod 33 to the lever 34 keyed onto the end of the
excentric 14. The upper end of the said lever 34 is connected by means of an
adjustable connecting rod 35 to the lever 36 keyed to the excentric 21 on the opposite.
side of the machine. The motion described of the lever 34 upon its excentric
together with the motion transmitted from the said lever through the adjustable
connecting rod 35 and arm 36 to the excentric 21 produces the required pressure
upon the rollers 16 and 18 respectively, the roller 16 being pressed upon by the
projection 15 on the sleeve 13 and the roller 18 being pressed upon by the projection 19
on the sleeve 20.
The return motion of the tools is produced by a coiled spring connected with the
arm 17 the arms falling back and the tools separating by the action of their own
weight and the elasticity of the spring connected to the arm 17. A coiled spring
fixed at one end to the peg 38 (see Figures 1 and 3) and the other end to a fixed
portion of the framing pulls down the arm 1 when the said arm is at liberty to move
and restores it to its normal position.
When in place of rotary cutters the circular pressing tools c, d are employed the
mechanism requires to be modified in the manner which I will now proceed to explain.
As the pressing tools do not remove any portion of the metal from the blank on
which they form a thread the said blank suffers a slight elongation by the operation
of the said tools and when the thread is operated upon a second or a third time it is
necessary that in each case the traversing motion shall be made somewhat greater in
order to compensate the increased length of the blank. The pressing discs together
with their sleeves and gearing are carried on the shaft to which the required
traversing motion is communicated by means of the thread or worm s on the said
shaft gearing with the series of teeth or comb t as is well understood, the said series
of teeth or comb constituting a half screw box. The said parts s and t are well
understood and are commonly employed in screw cutting machinery,
In the ordinary mechanism the comb is capable of a slight advancing motion,
that is, a motion in the direction in which the shaft advances. But the comb t in
my improved mechanism requires to have an advancing motion impressed upon it for
the purpose of accomodating the traversing motion of the tools for the slightly
increased length of the partially screwed blank. This motion of the comb t is effected
in the following manner; u is a scroll or volute cam (see Figure 5) on the shaft 27 ;
w is a lever the end of which bears on the cam u. The short arm of this lever
carries a connecting rod w² the upper end of which bears against the underside of
the end of the lever a. The axis of the said lever a carries an adjustable short arm
or lever y which bears through the sliding piece against the comb t. On the lifting
of the lever by the action of the cam u the said short arm or lever y presses forward
the comb t through the sliding piece to the extent required in the direction in which
the axis or shaft is travelling. The construction of the parts I have just described
is best seen in the enlarged views Figures 10 and 11.
=
When the pressing tools are first operating upon the blank no advancing motion
of the comb is requisite, the cam u in this case is inoperative in consequence of its
position on the shaft 27. On the second operation of the said tools on the blank the
inechanism last described for effecting the sliding motion of the comb t is put into
operation by the following means; 39 is a cam on the face of the toothed wheel 25.
A rod 40 sliding in the bracket 41 and having at its inner end a roller 42 bears
against the cam 39. This sliding rod 40 operates a horizontal lever 44 on the top of
the vertical shaft 43 the lower end of which shaft carries the fork 45 which engages

page_text: between collars 46 (indicated in dotted lines in Figure 1) on a sleeve sliding on the
shaft 27. This sliding sleeve carries the cam u. When the roller 42 bears against
that portion of the cam 39 of shortest radius, the cam is in such a position on the
shaft 27 as not to operate the lever w. When however the second action of the
tools on the blank is about to commence that portion of the cam 39 of longest radius
operating on the roller 42 and rod 40 causes the fork 45 to slide the cam u under-
neath the lever w and thereby cause the requisite sliding motion of the cam u during
the second operation of the pressing tools or discs.
When the tools are made to operate a third time on the blank a second com-
pensation for the elongation of the blank must be made by an increased motion of
the comb t. This may be effected by a series of rises side by side on the cam u but
I prefer when more than one compensatory motion of the comb t is required to employ
the mechanism represented in Figures 12, 13 and 14 Figure 12 representing the
mechanism in side elevation Figure 13 a plan of a portion of the same and
Figure 14 an elevation of the cam hereinafter described. In this mechanism the
lever is connected by the link 47 to the lever 48 fixed on the end of the axis 49.
The other end of the axis 49 has an arm or lever 50 parallel to the lever 48 but on
the other side of the cam 54, 51 is a cam on the side of the toothed wheel 25 on the
shaft 8. This cam is represented in elevation in Figure 14 from which Figure it will
be seen that it has two rises 52 and 53 which rises operating at the required times on the
roller on the end of the arm 50 produce the requisite motion in the lever w to effect
the necessary advance motion of the comb t.
The parts of the machinery which I have not described resemble those of ordinary
screw making machinery or differ therefrom only in such unimportant respects as the
adaptation of my improvements render necessary, which changes will be sufficiently
evident to a machinist conversant with screw making machinery.
I have described and represented machinery in which two circular impressing discs
or tools and two rotary cutters are employed the said tools and cutters respectively
being situated at and operating on opposite points of the blank and their pressures
balancing each other. Instead however of employing the said tools and cutters in
duplicate a single tool or a single cutter may be employed. In these cases the
pressure of the single tool or cutter on one side of the blank must be borne by a
support on the other side of the blank as in the ordinary screw cutting machinery.
As the construction and arrangement and operation of the said support differs in no
essential respect from the supports employed in ordinary screw cutting machinery I
do not think it necessary to describe the same I wish it however to be understood that
I prefer to employ pairs of the tools or cutters as hereinbefore described and represented
in the accompanying Drawings.
Although I have only represented and described my invention in its application to
the worming or threading of a screw blank for the manufacture of a screw of the
kind commonly called a wood screw yet my said invention is also applicable to the
worming or threading of screw bolts and other metallic articles requiring screw
threads upon them but as the machinery constituting my invention requires no
essential change to fit it for the worming or screwing of screw bolts and other articles
I do not consider any further description of my said invention necessary.
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 I claim
as my invention of "Improvements in machinery for the manufacture of metallic screws
and screw bolts and other metallic articles having screw threads upon them" :—
First In machinery for worming or threading screws the construction and
arrangement of a rotating pressing disc or discs or tools herein before described and
illustrated in the accompanying Drawings for forming the screw thread by pressure
whether the said rotating pressing disc or discs or tools has or have an independent
rotary motion communicated to it or them from the driving shaft of the machine or
has or have only the rotary motion given to it or them by the rotating blank on
which it or they operate, the planes of the said pressing tools or discs, when two

page_text: are used, being inclined to one another and also being inclined to the axis of the
blank on which they operate substantially as described and illustrated.
a
Secondly-In machinery for worming or threading screws, the construction and
arrangement of a rotary cutter or rotary cutters for forming the screw threads by
cutting action substantially as hereinbefore described and illustrated in the
accompanying Drawings.
Thirdly In machinery for worming or threading screws the arrangement or com-
bination of the parts substantially as hereinbefore described and illustrated in the
accompanying Drawings for driving or giving a rotatory motion to the rotary cutters
and for giving when desired an independent rotary motion to the rotating pressing
discs or tools.
Fourthly In machinery for worming or threading screws the construction and
combination of parts for supporting and for opening and closing or giving the
required approaching and receding motions to the sleeves carrying the rotating pressing
discs or tools or rotary cutters substantially as herein before described and illustrated in
the accompanying Drawings.
Fifthly In machinery for worming or threading screws the construction and
arrangement of parts hereinbefore described and illustrated in the accompanying
Drawings for putting the required pressure or cut on the closed rotating pressing
discs or tools or rotary cutters during the worming of the body and point of the
screw blank.
Lastly In machinery for worming or threading screws, the construction and
arrangements of parts herein before described and illustrated in the accompanying
Drawings for giving the required additional traversing motion to the rotating pressing
discs or tools consequent on the clongation of the blank by the action of the said
discs or tools upon it substantially as described and illustrated.
Dated the Ninateanth day of November 1888