IMPROVEMENTS IN MACHINES FOR THE MANUFACTURE OF SCREW BOLTS
Year: 1875

page_text: LETTERS PATENT to Charles Fairbairn, of the Railway Iron Works,
Middleton, in the County of Lancaster, Engineer, for the Invention
of "IMPROVEMENTS IN MACHINES FOR THE MANUFACTURE OF SCREW BOLTS.
PROVISIONAL SPECIFICATION left by the said Charles Fairbairn at
the Office of the Commissioners of Patents, with his Petition, on
the 20th November 1875.
I, CHARLES FAIRBAIRN, of the Railway Iron Works, Middleton, in
the County of Lancaster, Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN MACHINES POR THE MANUFACTURE OF
SCREW BOLTS," to be as follows:-
My Invention has for its object the formation of screw threads on
bolts by the process of rolling in such a manner as to obviate defects
hitherto experienced in the use of reciprocating plates and rollers for
the purpose.
And
my
Invention consists in the first place in the employment of a
pair of rollers for reducing the previously heated bolt blanks to the

page_text: required uniformity of size at the parts intended to have screw threads
formed upon them. These rollers are driven by a central wheel, and are
forced into the required contact with the blank to be rolled by means
of a screw with a hand or small fly wheel divided on its circumference
into eighths of an inch, and a stationary pointer being fixed to the frame
the hand wheel can be always brought to the same place, and every
blank made of the same size. On these rollers are cut spirals or
threads in such a manner that a small length of the surface of the bolt
is caused to be operated on at one time. With the said rollers are or
may be combined, either in the same machine or otherwise, a second
pair of rollers for forming the screw threads on the prepared blanks.
When combined in the same machine both pairs of rollers are driven by
one central wheel, and forced into contact with the blanks under opera.
tion by means of the same screw.
In the pair of screwing rollers the one with its rolling surface going
downwards in relation to the bolt blank will be slightly larger than the
one revolving in the opposite direction, and in order to keep the bolt
blank fair and parallel while being pressed between the two rollers, two
friction rollers are fitted in front of the machine which support the shank
of the bolt, and there is also a smaller wheel further back, having its axis
at right angles to the impressing rollers and toothed to the same pitch as
the screw, which merely revolves in the same manner as a worm wheel
with an endless screw, and this holds the hinder part of the bolt blank
parallel with the axis of the rollers. Threads are cut round the rollers
for impressing threads on the bolt blanks as required.
In order to obviate the tendency found in using reciprocating plates
of the central portion of the screwed blank to become of larger diameter
than the end portions, the rollers are made slightly curved longi-
tudinally instead of straight, by which means the prepared blank will
become correspondingly curved, so as to preserve its parallelism when
finished.
And my Invention consists, in the second place, in the use of an outer
and inner ring adapted to operate as required on the bolt blank inserted
between them. The internal surface of the outer ring and the external
surface of the inner ring have threads formed thereon, and a cavity is
formed in the inner ring for the liberation of the finished bolt, and the
insertion of a fresh blank,

page_text: The rings are proposed to be made in halves with threads formed on
their respective surfaces, adapting them for rolling or reducing the blank
to the
proper size by the first halves, and finishing them by the second
halves; the outer ring is mounted so as to be adjustable in its distance
from the inner ring. By means of suitable gearing the parts of the
rings will be brought together so as to liberate the bolts at the top of
the apparatus, and the rings will be caused to rest a sufficient time as
SPECIFICATION filed in pursuance of the conditions of the Letters
Patent, filed by the said Charles Fairbairn in the Great Seal Patent
Office on the 20th May 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
FAIRBAIRN, of the Railway Iron Works, Middleton, in the County of
Lancaster, Engineer, send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twentieth day of November, in the
year of our Lord One thousand eight hundred and seventy-five, in
the thirty-ninth year of Her reign, did, for Herself, Her heirs
and successors, give and grant unto me, the said Charles Fairbairn, Her
special licence, that I, the said Charles Fairbairn, my executors,
administrators, and assigns, or such others as I, the said Charles
Fairbairn, my executors, administrators, and assigns, should at any.
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN MACHINES FOR THE MANUFACTURE OF SCREW
BOLTS," upon the condition (amongst others) that I, the said Charles
Fairbairn, my executors or administrators, by an instrument in writing.
under my, or their, or one of their hands and seals, should particularly

page_text: describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Charles Fairbairn, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawings hereunto.
annexed, and to the letters and figures marked thereon (that is to say) :-
:-
My Invention has for its object the formation of screw threads on:
bolts by the process of rolling, in such a manner as to obviate defects
hitherto experienced in the use of reciprocating plates and rollers for the
purpose.
And my Invention consists in the first place in the employment of a
pair of rollers for reducing the previously heated bolt blanks to the
required uniformity of size at the parts intended to have screw threads
formed upon them. These rollers are driven by a central wheel and are
forced into the required contact with the blank to be rolled by means
of a screw with a hand or small fly wheel divided on its circumference
into eighths of an inch, and a stationary pointer being fixed to the frame
the hand wheel can be always brought to the same place, and every
blank made of the same size. On these rollers are cut spirals or threads
in such a manner that a small length of the surface of the bolt is caused
to be operated upon at one time. With the said rollers are or may be
combined either in the same machine or otherwise, a second pair of 2
rollers for forming the screw threads on the prepared blanks. When
combined in the same machine both pairs of rollers are driven by
one central wheel, and forced into contact with the blanks under
operation by means of the same screw.
In the pair of screwing rollers the one with its rolling surface going a
downwards in relation to the bolt blank will be slightly larger than the
one revolving in the opposite direction, and in order to keep the bolt
blank fair and parallel while being pressed between the two rollers two
friction rollers are fitted in the front of the machine which support the
shank of the bolt; and there is also a smaller wheel further back having a
its axis at right angles to the impressing rollers, and toothed to the same
pitch as the screw which merely revolves in the same manner as a worm

page_text: wheel with an endless screw, and this holds the hinder part of the bolt
blank parallel with the axis of the rollers. Threads are cut round the
rollers for impressing threads on the bolt blanks as required..
•
In order to obviate the tendency found in using reciprocating plates
of the central portion of the screwed blank to become of larger diameter
than the end portions, the rollers are made slightly curved longitudinally
instead of straight, by which means the prepared blank will become
correspondingly curved so as to preserve its parallelism when finished.
And my Invention consists in the second place in the use of an outer
and inner ring adapted to operate as required on the bolt blank inserted
between them. The internal surface of the outer ring and the external
surface of the inner ring have threads formed thereon, and a cavity is
formed in the inner ring for the liberation of the finished bolt and the
insertion of a fresh blank.
The rings are proposed to be made in halves with threads formed on
their respective surfaces adapting them for rolling or reducing the blank
to the proper size by the first halves, and finishing them by the second
halves. The outer ring is mounted so as to be adjustable in its distance
from the inner ring. By means of suitable gearing the parts of the
rings will be brought together, so as to liberate the bolts at the top of
the apparatus, and the rings will be caused to rest a sufficient time as
required.
By placing two of the roller machines in line and connected at the
proper distance, and with one set of the rollers cut for right-hand tho
other set for left-hand screws, coupling or other screws can be made,
both ends being rolled at the same time. Or a double set of rollers may
be arranged in one machine as herein-after described.
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 the
main working parts of the machines above referred to.
DESCRIPTION OF THE DRAWINGS.
1

page_text: convenient position so that the rollers may always be brought to the
same position when rolling the screws.
Sheet II. contains representations of the mode herein-before referred
to of rolling screws by means of an outer and inner ring.
Fig. 7 is a front elevation; Fig. 8 is a side view; Fig. 9, a back
clevation; Fig. 10 is a plan or horizontal view, and Figures 11, 12, and
13 represent detached parts of the machine.
A represents strong standards, on which is placed a strong sole
plate b, carrying bearings for the shaft c, the external disc d, the driving
shaft e (shown in front and back elevation), and the shaft f carrying a
pinion for driving the external disc or ring d. Fastened by screws to
the inside of the external ring or disc is a steel or cast-iron ring d², on
the inside of which is cut a series of spiral threads or grooves, which
are to operate upon one side of the heated blank; the internal disc or
ring carries also on its circumference a steel or cast-iron ring g', on the
outside of which are cut spirals, threads, or straight grooves, corre-
sponding to those on the external ring d¹.
the screws.
The external ring and its bearings are adjustable vertically, having
projections on the bearings through which the shaft f passes, and the
internal ring is capable of moving on that shaft as a centre. A lever h,
on which is a treadle at one end and a heavy weight at the other, is
used for bringing into position as required the two rings for impressing
The position of the bolt to be screwed may be either at the
upper or under side of the machine between the rings, and the lever is
shown in such a way that the bolt is inserted at the top. The weight i
is placed so as to balance the disc d, keeping it open to receive the
blank; by pressing on the treadle at the end of the lever h the disc d
will be brought into position for impressing the screw.
The two spur
wheels give the required speed to the external disc, and the two wheels m
and n answer for the internal disc.
Fig. 11 represents one method of cutting the spirals or threads on the
disc, and they may be cut in the manner shown, leaving alternate blank
spaces, or by having the whole surface covered with threads.
When the machine is in operation the two rings are made to run in
opposite directions, and cause the screw blank to revolve between them.
The two rings may be made to revolve with the same superficial velocity
by means of the wheels k and 7.

page_text: For well-finished screws I make the rings broad enough to cover
the length of the screw to be made, leaving vacant spaces between the
threads, in order to diminish the number of operating threads, the
axes of the two rings being parallel the blank revolves on its own
axis. For screwed spikes or coarse wood screws narrow rings are used,
and the axes of the two rings are placed at the requisite angle, being
widest at the back. By this means the screw while being impressed
on the blank rolls outward, and is thus delivered in a finished state.
Due regard is paid to the angle of the threads to be cut on the rings
when the axes are at different angles, and they may be set at such an
angle that straight grooves will form the necessary angle of the thread
on the bolt. With the rings set in this way the superficial velocity does
not require to be equal in the two rings; and when the velocity of the
rings is unequal a rubbing action is set up on the blank while being
screwed, which cleans the screw from scale. This rubbing action
may be still more utilized by cutting fine slots across the threads in the
direction of the axes of the discs, being deepest at the inside, and gra-
dually running towards the outside or front of the machine, leaving the
two outside threads untouched or complete. The edges of the slots will
remove the skin of the iron, while the outsides of the rings finish or
smooth the surfaces thus cut, as the blank revolves outwards. A guide
is necessary with this arrangement.
Figures 12 and 13 represent the guide in one form. d and g¹ are
sections of the two impressing rings; O is a spindle having two collars,
the inner one plain, and the outer one screwed; the spindle has two
bearings, one inside between the rings, and the other outside. The
bearings are not shown, but they are suspended from the bearings in
which the outer ring revolves. When the blank is revolving between
the rings the outer one presses it against the roller O, the unfinished
portion of the blank bearing against the inner collar or plain ring,
and the screwed portion of the blank bearing against the outer collar
which has threads on it, thereby preventing the newly formed thread
from being injured while rolling outward and delivering itself.
I employ this machine with plain rings for rolling the blanks down
to the proper size, and for making the iron smooth and straight to
receive the screw. I also use the rings for rolling and screwing short
bolt blanks, the two operations being accomplished by means of two
rings. The impressing rings are of the 'breadth of the portion of the

page_text: bolt to be screwed, and their axes are parallel, the superficial velocity
of the impressing surfaces being equal; the inner ring has a hollow
space cut out of it into which the bolt is inserted and withdrawn when
finished. I make the rings in halves with threads formed on their
respective surfaces, adapting them for reducing the blank first, and then
impressing the screw. One half of each ring is plain, and the other
balf has spirals or threads cut on it, and the hollow space, when it
arrives at the proper place, is the starting or delivering point. The
blank is first rolled between the plain portions during the first half
revolution, and the screwed portion of the rings then finish the bolt in
the second half of the revolution.
By means of suitable gearing the two rings make a revolution and
then stop sufficient time to admit of the finished screw being withdrawn
and a new blank being inserted; at this point the two plain surfaces are
about to meet, and the hollow space in the inner ring is in the position
for taking out the screw and inserting a new blank.
With reference to the arrangements for rolling and screwing large
screws, such as coupling bolts for railway carriages with right and left
hand screws, this may be effected either by placing two of the above-
described roller machines in line and suitably connected with one set of
rollers cut for right hand and the other for left hand screws, or by using
double or combined rollers in one machine.
When the latter mode is adopted the rolls have grooves or cavities
in their central parts between the two ends, with their respective right
and left hand screw threads on them, in order to allow the projection
on the middle of a coupling screw to pass while revolving: As the
screw while being pressed between the two reducing rollers lengthens
or expands longitudinally during that operation, it is supported on
two or more worm wheels similar to those represented on Sheet I.,
and described.
The blank may if preferred be held between spring centres. The
bearings of the two centre or inside rollers (of the series of four rollers)
are fixed, those of the two outer rollers being adjustable. The bearings
of these two outer rollers are moved into and out of position, as
required by means of a shaft extending beyond each end of the
machine, and having cranks fixed on it with connecting rods and
links communicating with the said bearings. The said shaft is acted

page_text: upon as required by means of a hand lever, and when spring centres
are employed for holding the blanks these centres are or may be acted
upon as required by means of guides worked by the said lever, and
caused to actuate levers connected to the said movable centres, in order
to release the blanks as required, by compressing the springs, such
blanks being held as required by the reaction of the said springs.
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 Invention is,―
First. The general arrangement of the machine represented in Sheet I.,
and herein-before described with special reference to the apparatus
employed for entering the blank and releasing the finished bolt as
required, and the use of worm wheels for supporting the bolt blank
while being rolled.
Secondly. The rolling of iron rods or bolt blanks and impressing
screw threads thereon by means of two concentric rings, either with
their axes parallel, or placed at an angle, also the guides, as described,
and the partial grooving of the impressing surfaces for removing the
skin of the iron, all as herein-before described with reference to the
Figures on Sheet H.
And, lastly. The general arrangement and combination of two
separate machines, or two sets of rolls in one machine, adapted for
rolling right and left hand screws, as herein-before described.
In witness whereof, I, the said Charles Fairbairn, have hereunto
set my hand and seal, the Fifteenth day of May in the year of
our Lord One thousand eight hundred and seventy-six.
Figures on sheet 11.
And, lastly. The general arrangement and combination of two
separate machines, or two sets of rolls in one machine, adapted for
rolling right and left hand screws, as herein-before described.
In witness whereof, I, the said Charles Fairbairn, have hereunto
set my hand and seal, the Fifteenth day of May in the year of 2
our Lord One thousand eight hundred and seventy-six.
Witness,
JOHN MATTHEW,
Engineer,
Middleton.
CHARLES FAIRBAIRN. (L.S.)