IMPROVEMENTS IN APPARATUS FOR FORGING SCREWS ON BOLT BLANKS, AND SUITABLE PATTERNS ON METALLIC RODS EITHER IN A HEATED OR A COLD STATE
Year: 1878

page_text: LETTERS PATENT to Andrew Nicol Porteous, of Edinburgh, Scotland, Engineer,
for the Invention of "IMPROVEMENTS IN APPARATUS FOR FORGING SCREWS
ON BOLT BLANKS, AND SUITABLE PATTERNS ON METALLIC RODS EITHER IN
A HEATED OR A COLD STATE."
1
}
Sealed the 6th May 1879, and dated the 8th November 1878.
PROVISIONAL SPECIFICATION left by the said Andrew Nicol Porteous at
the Office of the Commissioners of Patents on the 8th November 1878.
ANDREW NICOL PORTEOUS, of Edinburgh, Scotland, Engineer.
"IMPROVEMENTS
IN APPARATUS FOR FORGING SCREWS ON BOLT BLANKS, AND SUITABLE PATTERNS
ON METALLIC RODS EITHER IN A HEATED OR A COLD STATE."
My Invention has reference to machines in which are used rings, discs, or rollers,
with screw threads or patterns on their peripheries to form screw threads on bolt
blanks, or patterns, on metallic rods, by rolling and compression.
And my Invention consists in adapting and applying to such machines three or
more rings, discs, or rollers arranged so as nearly, but not quite, to touch one another,
and to be driven by suitable gearing, the threads being cut thereon of the required
pitch, but at an angle greater than the required angle in order to obtain such
obliquity in the setting of the rings, discs, or rollers as will cause the bolt blank to
move forward or backward a sufficient distance to make any required length of
screw.
.
The thread on the rings, dises, or rollers being cut at a greater angle than is
required for that on the bolt blank, this is compensated for as required by placing
their axes at such an inclination to each other as will bring the rings, discs, or
rollers to the proper angle for forming the required thread, and give them the
necessary obliquity for moving forward or backward, as required, the bolt blank or
other piece of metal under operation.
When the bolt to be threaded is sufficiently large (say above half an inch in
diameter) the three rings, discs, or rollers may be of equal diameters; but for bolts

page_text: or screws below that size, one of the rings, discs, or rollers may be made smaller
than the other two, but of the same pitch and angle, and having the same number of
revolutions as the larger ones, in which case the bolt blank is caused to slip or slide
on a smaller roller a distance equal to the difference of the two circumferences.
Or the combination may consist of two smaller rollers and one larger, in which
case the larger roller being of a given diameter and the smaller ones equal to one
half of the larger, then the smaller rollers will be driven at double the speed, placed
at one half the angle for obliquity, and have the threads cut to the same pitch but
to one half of the angle in excess of the true angle.
The said rule and proportion will apply to all unequal diameters of rollers used
in combination. In this case there is no slip, which is more suitable for small
screws.
The relative proportions of the rollers may be varied, provided the revolutions
and angle are adapted to suit the respective variations therein according to the
above rule.
If required, the machine may, be fitted with a reversing motion so that the screw
may be passed twice through the rollers without being released, while for some
kinds of screws the operation during the passage once through is sufficient.
A guide or holder is placed at the back of the rings, discs, or rollers, which keeps
This holder is
the point of the bolt blank steady and straight whilst running in.
kept firm against the point of the bolt blank by means of a weight or spring, and
is made of hardened steel and formed in such a manner as to cut or shape a point
on the bolt blank or screw while the latter is under operation.
In order to make tapered screws, a lateral or vertical motion is communicated to
one or more of the rings, discs, or rollers. This motion is communicated by an
endless screw and wheel or toothed wheels in combination with friction or ordinary
gearing from the main shaft working a cam or screw. For making parallel screws
the said cam is replaced by one of different shape. Provision is also made in the appa-
ratus for relieving any undue pressure by a counterweight or a spring so that if the
pressure is at any time more than the regular working pressure breakage is thereby
avoided. The impressing rings, discs, or rollers are also slightly rounded on the
front in order to make a good finish on the neck of the screw.
T

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Andrew Nicol Porteous in the Great Seal Patent Office on the 7th
May 1879.
$$
ANDREW NICOL PORTEOUS, of Edinburgh, Scotland, Engineer. IMPROVEMENTS
IN APPARATUS FOR FORGING SCREWS ON BOLT BLANKS, SUITABLE PATTERNS ON
METALLIC RODS EITHER IN A HEATED OR A COLD STATE."
My Invention of "Improvements in Apparatus for Forging Screws on Bolt Blanks,
Suitable Patterns on Metallic Rods either in a Heated or a Cold State" has reference
to machines in which are used rings, discs, or rollers with screw threads or patterns
on their peripheries to form screw threads on bolt blanks or patterns ou metallic
rods by rolling and compression.
And my Invention consists in adapting and applying to such machines three or
more rings, discs, or rollers arranged so as nearly, but not quite, to touch one another
and to be driven by suitable gearing, the threads being cut thereon of the required
pitch, but at an angle greater than the required angle, in order to obtain such
obliquity in the setting of the rings, discs, or rollers as will cause the bolt blank to
move forward or backward a sufficient distance to make any required length of
screw.
The thread on the rings, discs, or rollers being cut at a greater angle than is
required for that on the bolt blank, this is compensated for as required by placing
their axes at such an inclination to each other as will bring the ring, dises, or
rollers to the proper angle for forming the required thread and give them the
necessary obliquity for moving forward or backward, as required, the bolt blank or
other piece of metal under operation.
When the bolt to be threaded is sufficiently large (say about half of an inch in
diameter) the three rings, discs, or rollers may be of equal diameters; but for bolts
or screws below that size one of the rings, discs, or rollers may be made smaller than
the other two, but of the same pitch and angle, having the same number of revolutions
as the larger ones, in which case the bolt blank is caused to slip or slide on the
sinaller roller a distance equal to the difference of the two circumferences. Or the
combination may consist of two smaller rollers and one larger, in which case the
larger roller being of a given diameter, and the smaller ones equal to one half of
the larger, then the sinaller rollers will be driven at double the speed, will be placed
at one half of the angle for obliquity, and have the thread cut to the same pitch
but to one half of the angle in excess of the true angle.
The said rule and proportion will apply to all unequal diameters of rollers used
in combination. In this case there is no slip which is more suitable for small
screws.
The relative proportions of the rollers may be varied, provided the revolutions
and angle are adapted to suit the respective variations therein according to the
above rule.
If required the machine may be fitted with a reversing motion so that the screw
may be passed twice through the rollers without being released, while for some
kinds of screws the operation during the passage once through is sufficient.
A guide or holder is placed at the back of the rings, discs, or rollers which keeps
the point of the bolt blank steady and straight while running in. This holder is
kept firm against the point of the bolt blank by means of a weight or spring and
is made of hardened steel and formed in such a manner as to cut or shape a point
on the bolt blank or screw while the latter is under operation.
In order to make tapered screws a lateral or vertical motion is communicated to
one or more of the rings, discs, or rollers. This motion is communicated by an
endless screw and wheel or toothed wheels in combination with friction or ordinary
gearing from the main shaft working a cam or screw.
the said cam is replaced by one of different shape.
For making parallel screws
Provision is also made in

page_text: the apparatus for relieving any undue pressure by a counter-weight or a spring, so
that if the pressure is at any time more than the regular working pressure breakage is
thereby avoided. The impressing rings, discs, or rollers are also slightly rounded
on the front in order to make a good finish on the neck of the screw.
Having thus stated the nature of the said Invention I will proceed to describe
more particularly in what manner the same is to be performed by the aid of the
accompanying Drawings, in which are represented machines and apparatus of the
kind or kinds hereinbefore referred to.
DESCRIPTION OF THE DRAWINGS.
In Sheet I. Fig. 1 represents an elevation of the machine fitted with reversing
gear worked by the foot with tapering motion worked from the holder as hereinafter
described; Fig. 2 is a plan view of the same. Fig. 19 is an elevation of a back
holder for the front of the bolt; Fig. 20, a section of the same. Fig. 21 is a diagram
indicating or serving to explain the mode of determining the angle of the thread on
the discs, and also that of the shafts of the discs; Fig. 22 represents the three dises
in elevation; Fig. 23 represents three discs of unequal size; and Fig. 24 represents
four discs of equal diameters.
In Sheet II. Fig. 3 represents a front elevation of a machine with discs and
holder removed; Fig. 4, a front elevation of the central bracket and method of
slightly altering the angle on shafts if required; Fig. 5, a back elevation; Fig. 6, a
plan of crosshead; Fig. 7, a plan of the front bracket; Fig. 8, a plan of the bush
for front bracket; Fig. 9, a plan of bottom cover for central bracket; Fig. 10, a
plan of the top cover for the same; Fig. 11 is an elevation of the centre piece of the
same; Fig. 12, an end elevation of the same; Fig. 13, a section of the same.
Fig. 14, a plan of bush; and Fig. 15, an end elevation of the same.
In Sheet III. Fig. 17 represents an elevation of the machine fitted with self acting
and reversing motion driven from the main shaft of the machine, and its action
governed by the holder; Fig. 18, an elevation of a single acting machine fitted with
In this machine the
flywheel and treadle motion for opening the top discs or disc.
bolt is run only once through.
On these Drawings A, A, represents the mainshaft which may be fitted with the
reversing motion B produced by three bevilled wheels as shewn; C, C, C, the shafts
carrying the discs D, D, D; E, the holder carrying the head or neck of the bolt to
be operated upon; F, the cam by which the tapering motion is produced; G, G, G,
R, R, Figures 1 and 2, the levers connecting the holders E with the cam F; H, the
treadle by which 'the machine is reversed; I, the back bracket carrying the main-
shaft A, A; K, the centre bracket carrying the end of the mainshaft A, A, and the
angled shafts C, C, C; L, the front bracket carrying the front end of the angled
shafts C, C, C, with the discs D, D, D, fitted thereon; M, the crosshead carrying the
top disc and connected to the cam F for the purpose of producing the tapering
motion; N,.a spring fitted to the crosshead M and also to the top disc for the
purpose of relieving any undue pressure on the discs D, D, D; O, O, brackets on
main shaft for adjusting or setting the discs D, D,'D; P, P, an endless screw and
worm wheel geared to the main shaft A, A, for producing tapering and self acting
reversing motion which may be adopted in place of the levers G, G, G; Q, a friction
clutch by which the tapering and self acting reversing motion P, P; P, is thrown
out of gear when required by means of the levers R, R, connected to the cams S, S,
which can be adjusted to suit the lengths of the bolt or rod to be operated upon.
In diagram Fig. 21 (Sheet I.) suppose the angle A, B, C, shews the true angle of
the thread required to be produced on the bolt to be operated upon, and the angle
on the shafts carrying the discs to be equal to the angle A, B, D, then the angle of
the thread to be cut on the discs will be equal to the angle C, B, D, that is, the
true angle required, plus the angle given to the shafts, because the angle given to
the shafts is less than the true. angle. Suppose the true angle required for the
thread on the bolt to be sixteen degrees, and the angle on the shaft to be four

page_text: degrees, then sixteen degrees and four degress equal twenty degrees, which is the
angle of the thread cut on the discs, because four degrees, "the angle on the shafts,"
taken from twenty degrees, "the angle of the thread" on the "discs" will leave
sixteen degrees, which will be the angle of the thread formed on the bolt, and there-
fore the true angle required.
In discs of unequal size the angles of obliquity will be unequal, but the angle of
the thread cut on the discs will correspond in such a way that a true angle of thread
is formed on the bolt under operation, as shewn by the above.
The bolt to be operated upon is placed in the holder E and thrust forward into,
the space formed between the discs D, D, D, on the circumferences of which are cut
threads or patterns of the kind which it is required to impress upon the bolt or rod
under operation. After the bolt or rod has travelled inwards the required distance
the machine is reversed by the treadle H or by the self acting reversing motion
P, P, P, and the bolt or rod is rolled out. The tapering motion is produced by the
.cam F relieving, to the extent required, the top disc. This is accomplished by setting
the cam in motion, the effect of which is to raise the cross head M in a vertical/
direction, thereby opening or enlarging the space formed by the discs D, D, D., In
the single acting machine Sheet III. the discs are opened by means of the treadle H
which is connected with the cam F, and the bolt is only once passed between the
.discs.
When making screws with an uniform taper from point to neck, the cam F gives
an uniform motion to the top disc; but where the screws are tapered at the neck
only, the cam F is replaced by a suitable one for this purpose. Any kind of taper
can be given to the bolt or rod under operation, according to the shape given to the
cam F. For parallel screws the cam F is replaced by a parallel cam.
The general rule for the sizes of the discs or rollers is to make their diameter not
more than six times the diameter of the screw to be made (measured at the bottom
of the thread), they may be less than this, but the above is the limit of size where
discs of equal diameter are used. The greater the diameter of the discs the faster
will the screw in course of formation travel out or in, that is, the obliquity being
equal, but large discs or rollers have not the impressing power of smaller ones, and
if required the smaller discs can be set at a greater angle of obliquity in order to
equalize them.
The
When cutting the threads to a greater angle than the true angle there are more
spaces obtained for forming threads on the discs, consequently more dividing or
wedge shaped points entering or pressing the iron when forging the screws.
points of the threads run towards the iron under operation, that is to say, the thread
on the discs and the iron to be screwed are approaching towards each other, the
screw being formed on the bolt or rod is left solid, because the threads while being
formed run opposite to what they would do if screwed into wood. By using three
or. more rollers the iron under operation is pressed solid to its centre and is not
loosened, as would happen by using less than three rollers, as in that case the process
tends to loosen the iron while being rolled.
Having thus described the nature of the said Invention and in what manner the
same is to be performed, I hereby declare that what I claim as of my Inven-
tion is,
First. A new and improved machine for rolling or forging screws on bolt blanks,
or patterns on metallic rods by means of three or more discs and rollers, on the
circumferences of which are cut grooves, or threads, or patterns of the necessary
pitch but at an angle in excess of the true angle, such greater angle being in practice
reduced as required by setting the axes of the discs or rollers in such a position as
will place the grooves or threads on the discs or rollers at the same true angle, and
at the same time give to the discs or rollers the necessary obliquity in order to com-
municate lateral motion to the metal under operation, as hereinbefore described.
Secondly. The use of discs or rollers of unequal diameters having their circum-
ference travelling at the same superficial velocity with the method of adjusting
and dividing their relative angles and setting the obliquity of the discs as required.
,

page_text: Thirdly. The mode of obtaining tapering or other motion for making screws
with an uniform taper from neck to point, or for making screws with only part of
their screw tapered, the other part remaining parallel by connecting to the holder
for the head of the bolt suitable levers which govern the action of the tapering
motions as the screw is rolled inwards or outwards, as hereinbefore described.
Fourthly. The general arrangement described for increasing or diminishing the
angle or obliquity of the discs with the adjusting screws or worm and worm wheel
at the back and middle supports of the bearings.
And, lastly. The holder, as described, for supporting the points of the bolt under
operation, and for finishing the point of the same while it is travelling in a lateral
direction either inwards or outwards.
In witness whereof, I, the said Andrew Nicol Porteous, have hereunto set my
hand and seal, the Fifth day of May, in the year of our Lord One thousand
eight hundred and seventy nine.
Witness,
JAMES BURNET,
17, Dundas Street,
Edinburgh,
Civil Engineer.
ANDREW NICOL PORTEOUS. (L.S.)