AN IMPROVED METHOD OF MANUFACTURING SCREWS
Year: 1851

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
ARCHIBALD BROOMAN, of the Firm of J. C. Robertson & Co., of Fleet Street,
in the City of London, Patent Agents, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Fifteenth day of March,
One thousand eight hundred and fifty-one, in the fourteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Richard Archibald Brooman, my exors, adññors, and assigns, Her
especial licence, full power, sole privilege and authority, that I, the said
Richard Archibald Brooman, my exors, adññiors, and assigns, or such others
as I, the said Richard Archibald Brooman, my exors, adñiors, or assigns,
should at any time agree with, and no others, from time to time and at
all times during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, and in the Islands of Jersey, Guernsey, Alderney,
Sark, and Man, and also in all Her said Majesty's Colonies and Plantations
abroad, the Invention of "AN IMPROVED METHOD OF MANUFACTURING SCREWS,"
communicated to me from abroad; in which said Letters Patent is contained
a proviso that I, the said Richard Archibald Brooman, shall cause a particular
description of the nature of the said Invention, and in what manner the same
is to be performed, by an instrument in writing under my hand and seal,
to be inrolled in Her said Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said in part
recited Letters Patent, as in and by the same, reference being thereunto
had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Richard Archibald Brooman, hereby declare that the nature of the said
Invention, and in what manner the same is to be performed, are fully described
and ascertained in and by the present Specification thereof, reference being had
to the Drawings hereunto annexed, that is to say:-
Firstly, the Invention consists in manufacturing screws of all sizes, and of
more than one thread, from one and the same set of dies, and in producing the
threads, whether square or angular, by rolling compression. The mechanical
combinations and arrangements by which these improvements are effected are
shewn in Sheet I. of the Drawings annexed, and in the following description
thereof :-
Figure 1 is an end elevation of the screw-rolling machine which I employ,
with the dies fixed in their places; and Figure 2, a side elevation of it. A is
a strong rectangular table, supported on standards A, A, and surmounted at
about the middle of its length by a bridge-like piece M, which is securely
bolted by its two sides or cheeks to the sides of the table. The upper surface
of the table is made with two V grooves running in the direction of its length,
in which grooves a bed plate B moves to and fro according as it is actuated by
a crank handle D, which turns a pinion that takes into a rack C affixed
to the under part of the bed plate. To the top of this travelling bed plate one
of the dies K¹ is secured in the manner shewn separately in plan and section in
Figures 3 and 3. F is the die carrier, which fits on to a circular part E
raised on the centre of the bed plate B, yet not so tightly but that the carrier
may turn freely on E as a pivot either to the right or to the left. The die K
is dovetail, jointed into the carrier F, as shewn in Figure 3. The carrier has
a slot at each end, and there are screw bolts G, G, fitting into these slots, by
which the carrier and die can be made fast in any position to the right or left
which it may be proper to assign to them. The other or upper die K is fixed
in the bridge-like picce M. by arrangements precisely similar to those just
described (see Figure 4 and Figure 3), only that the positions are reversed,
that is to say, the die K is dovetailed into the under side of a top carrier F
and that carrier is attached to the under side of a top plate L, which slides up
and down the bridge piece M. The two dies (K¹, K²) are constructed
precisely alike, and consist each of a flat rectangular plate of steel or other
suitable metal, having on one side or face a series of straight parallel grooves
(formed either by hand or machinery) of like width and depth with the threads
of the screws intended to be produced. The grooving is effected when the
plates are in a (comparatively) soft state, and the plates are afterward
hardened sufficiently to enable them to serve as dies. A screw spindle (

page_text: passes right down. through the cross head of the bridge piece M, and into the
boss of the top plate L, by the turning of which the one way or the other the
two. dies can be made to approach to or recede from one another'as required..
N is a wheel, by which the screw spindle O is turned round. P, P, P, are a
series of levers with weights Q, Q, attached, which are connected with the top
plate L by a crank cross head P, and lowered or raised as required by means
of a handle R, so as to bring down the top die with any degree of pressure,
and at any rate of velocity, on any object placed between it, and the under,
die. S represents the plain cylindrical metal rod, on which the screw thread.
is intended to be produced. The principle on which this is to be done
falls now to be explained. If two grooved plates; such as have been
described, were fixed with the grooves of the one fitting exactly on the
ridges of the other, and coinciding with a horizontal line drawn through
the centre of the machine and pressed against a plain metal, rod introduced
between them at right angles to the said horizontal line, the effect, would
simply be to impress the metal rod with a series of straight parallel grooves
and ridges; but if the two dio plates, instead of being set parallel, are
moved horizontally on their centres, one a little to the right, the other.
exactly the same extent to the left, then on the rod being rolled between them
under pressure, and at right angles to the horizontal line drawn through the
centre of the machine as aforesaid, the plates will indent the rod in con-
tinuous spiral lines, corresponding exactly in pitch to the angle at which the
dies have been set. To make sure of uniformity throughout the thread of the
screws it is of course essential that the two dies (at whatever angle they are
set) should be kept with the utmost possible steadiness in that relative position.
The fixing of the die plates at their proper angles of inclination is effected by
means of the screw bolts G, G, as before explained. The angle at which the
dies are set must of course depend upon the diameter of the rod to be screwed,
the pitch of the thread, and the number of threads. A suitable index for this
purpose may be constructed in the manner shewn in the diagram, Figure 3b.
Let a, a, a, represent the parallel ridges upon the die. From as a centre
describe the arc c, d, e, f, g, with a radius equal to the circumference of the
rod or bolt to be screwed, then the angle c, b, d, will be that at which the two
die plates require to be set in regard to each other when a single thread is to
be formed upon the rod. If the screw is to have more than one thread, then
the arc c, d, e, f, is to be divided into equal portions, corresponding to the
pitch of the thread. If a "double-threaded" screw is to be formed, then
the angle c, b, e, formed by the extremities of two such divisions with the
centre b, is that required to be given to the dies;; if a treble thread, then three
such divisions c, d, e, f, are to be taken, and so on for any number of threads

page_text: which the diameter of the rod will admit of. In this manner the angle corre-
sponding to any diameter of rod or pitch of thread may be obtained, and a
number of those angles may be marked or tabulated upon an index plate,
which may be attached to the face of the sliding bed plate B, as shewn in
Figure 8, and traversed by a needle pointer projecting from the end of the
under die carrier. The better to ensure perfect accuracy in using such an
index, an endless screw may be affixed to the bed plate at the opposite end of
the under die carrier, as also shewn in Figure 4, and made to work into a series
of teeth formed on that end of the carrier. In operating with the machine
the rod to be screwed is introduced at right angles to a horizontal line drawn
through the centre of the moveable bed plate. It is then gripped fast between
the dies by lowering the upper die (by means of the wheel N) into contact
with the rod, and then causing it to act with pressure by gradually lowering
the weighted levers P, P, P. The under bed plate B, in which the under die
is fixed, is then moved to and fro on the V grooves, as before described, which
carries the rod along with it. The length of rod which can be thus screwed is
necessarily limited by the breadth of the grooved surfaces between which
it is rolled, but that breadth may be encreased to any extent likely to be
required in practice. It will be further obvious that two or more pairs of dies,
cach pair set at a different angle, and producing screws of different patterns,
might be mounted in the single machine and worked simultaneously by one
and the same moving power. And so also the die plates might be made with
two sets of grooves crossing each other at any required angle in opposite direc-
tions, in which case, when they are rolled on a plain rod, as before described,
they will produce at one and the same time both a right and a left hand
thread.
Instead of the dies being flat, as before described, they may be made of the
form of segments of circles, or even of entire circles; and instead also of tho
under die being moved to and fro, it may have a continuous rotary motion
given to it; but the modes of combination and operation embodied in the
method or machine before described are preferred, as being in the whole the
most practically convenient.
The principle of using dies moveable on their centres into different positions
in relation to the rod to be screwed, which forms the distinguishing feature of
the method or machine just described, may also be applied to the improvement
of ordinary stock dies, in the manner represented in Sheet II. of the Drawings
annexed.
Figure 1 is a side elevation of a triple stock constructed on this principle.
Figures 2 and 23, longitudinal and end views of the dies. Figure 3, a section
of one division of Figure 1; and Figure 4, an end view
of the same. The

page_text: dies D, D, D, are made of hardened steel, and perfectly cylindrical, and one or
both extremities are made with sharp parallel cutting edges, which are formed
in the first instance by a tap, the same practice being followed in this respect
as in the ordinary dies. They fit freely into sockets D', D', D', bored out for
them in the circular bosses E, E, E, of the stock A, and so that they may be
readily turned round on their centres so as to vary at pleasure the angular bear-
ing of their cutting edges. When turned into their assigned position they are
then made fast by set screws H, H. Each die has a feather f, which fits into
a slot g in the boss E. B, B, B, are screw handles, by the turning of which the
tool is worked, the screwed parts causing the dies to collapse or recede
as required. The angles at which the dies in this description of stock should
be set may be ascertained by the diagram Fig. 3b before described, and from
this diagram the various angles may be transferred, by means of a "bevil
stock," to the dies. The bevil stock should be applied first to the diagram,
and being set at the proper angle one edge of it should be applied to the face
of the screw stock, while the line of the ridge formed upon the die is made to
correspond with the other leg of the die stock.
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I declare that what I claim is, the
method before described of manufacturing screws of all sizes, and of any
number of threads, either right or left handed, and of every variety of pitch,
from dies acting by rolling compression; as also the partial application of
the said method to ordinary stock dies, in manner before exemplified and
described.
In witness whereof, I, the said Richard Archibald Brooman, have here-
unto set my hand and seal, this Fifteenth day of September, in the
year of our Lord One thousand eight hundred and fifty-one.
R. A. (L.s.) BROOMAN.
AND BE IT REMEMBERED, that on the Fifteenth day of September, in
the year of our Lord 1851, the aforesaid Richard Archibald Brooman came
before our said Lady the Queen in Her Chancery, and acknowledged the