Improvements in Dies for Forging Screw Threads.
Year: 1890

page_text: Date of Application, 3rd Jan., 1890
Complete Specification Left, 13th June, 1890-Accepted, 19th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in Dies for Forging Screw Threads.
I, HENRY PATTERSON BOYD, of 3 Clarence Street, Northam, Southampton,
Engineer, do hereby declare the nature of my invention to be as follows :-.
My invention relates to dies used in machines for forming screw threads by forging,
and has for its object the construction and form of such a die which shall be better
adapted for forming the threads than the ones at present in use, and which can be
prepared at a great reduction in cost.
1 carry out my invention as follows:-
Instead of making the dies (as has previously been done) by placing them together
in pairs and drilling a hole so that each die shall contain half the hole, and tapping
it with a tap of the exact size of the screw to be produced. I insert a liner between
each pair of dies of a suitable thickness according to the diameter of the screw to be
manufactured.
The pair of dies are then bored in the lathe with a hole of rather larger diameter
than the stem of the screw which is desired to be produced by them
The necessary recesses are then cut by the screw cutting attachment of the
lathe and so that when completed the largest diameter of the spiral recesses
or threads are likewise of larger diameter than the outside thread of the bolt to be
produced.
These dies are then taken apart and the liner is removed.
The effect of forming the dies in this particular way is that the difficulty which is
experienced in revolving the bolt in the ordinary semi-circular dies during the
formation of the thread is entirely obviated on account of the curvature of my
improved dies being smaller than that of the screw to be produced, the screw does not
jam in the said dies after every blow as in the case of semi-circular dies having the
same curvature as the screw to be produced.
DL
11
10 T
1000
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Dies for Forging Screw Threads.
1, HENRY PATTERSON BOYD, of 3 Clarence Street, Northam, Southampton, in the
County of Hants, 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 relates to dies used in machines for forming screw threads by forging,
or pressure, and has for its object the construction and form of a die which shall be
better adapted for forming the thread than the ones at present in use, and which can
be prepared very cheaply; and in order that my invention may be the better
understood I now proceed to describe the same, in relation to the drawings hereunto
annexed, reference being had to the letters and figures marked thereon. Like letters
refer to like parts in the various drawings.
Figures 1 and 2 are a side elevation, and transverse section respectively of the dies
with an intermediate liner, as in the course of formation.
Figures 3 & 4 are a side elevation and transverse section respectively of the
dies, after the liner has been removed, and ready for use for forging or pressing a
screw bolt.

page_text: Instead of making the dies (as has previously been done) by placing them together
in pairs, and drilling a hole so that each die shall contain half the hole, and tapping
them with a tap of the exact size of the screw to be produced, I insert a liner A
between each pair of dies B B' of a suitable thickness, according to the diameter of
the screw to be manufactured.
The pair of dies, with the liner between them, are then clamped together, and
bored across the line of junction with a hole C of slightly larger diameter than the
stem of the screw which it is desired should be produced by then, equal portions of
the hole being taken out of each die.
The necessary recesses for the thread D are then cut by an ordinary screw cutting
attachment of the lathe, so that when completed the largest diameter of the spiral
thread D is likewise of slightly larger diameter than the outside thread of the bolt to
be produced.
The dies are then taken apart and the liner is removed, and the dies may be
attached by suitable bolt holes E E to any suitable machine for producing reciprocating
blows or pressure.
The effect of forming the dies in this particular way is that the chief swaging or
forging pressure is applied by the crown of the dies, and the difficulty which is
experienced in forging and revolving a bolt in ordinary semi-circular dies,
during the formation of the thread, is entirely obviated, on account of the curvature
of my improved dies being slightly smaller (i.e. of larger radius) than that of the screw
to be produced.
By the removal with the liner of the side portions of the dies, my improved dies do
not grip the work as would be the case in semi-circular dies, having the same
diameter and curvature as that of the thread to be produced.
Should it be desirable, in carrying out the work, that the dies should come home to
one another to give a regular and definite diameter to the finished bolt, the liner A
may be made of such a thickness, as, when removed, to compensate exactly for the
excess diameter of the internal thread in the dies, as compared with the diameter of
the screw to be cut.
In this case, the dies B B¹ would, upon the removal of the liner, come home to each
other as shown in Figures 3 & 4, or equivalently a thinner liner than the original
liner A may be substituted for the latter, to make any desired amount of compensation
in the approach of the two dies one to another.
In manipulating the blank screw bar in this die we have found it preferable to enter
first only the end of the bar at one side of the die, and by gradual rotation to advance
the bar slowly and steadily into the die until the thread is completed.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is :
1st. The construction or formation of dies for the production of forged or pressed
screw bolts, by drilling, and cutting the formation thread and barrel of slightly larger
diameter than that of the screw to be produced, through the pair of dies and the
interposed removable liner, so that the crowns only of the dies shall produce the
desired swaging or pressing, leaving the bolt ungripped at the sides, for easy revolution
during formation in the dies, substantially as described.
2nd. The specific form of a pair of dies substantially as and for the purposes described
in relation to the figures herewith illustrated.
Dated this 13th day of June 1890.
FELL & WILDING,
1, Queen Victoria Street, E.C., Agents for the Applicant.