Improvements in Machines for Forming Screw Threads on Bolts or other Blanks.
Year: 1898

page_text: Improvements in Machines for Forming Screw Threads on Bolts or
other Blanks.
A communication to me from abroad by LÉON EDMOND MARIE ERNEST LEVENT, of
Lovignier-Bavay, in the Republic of France, Manufacturer.
I, PHILIP MIDDLETON JUSTICE, of 55 and 56, Chancery Lane, in the County
of London, Fellow of the Chartered Institute of Patent Agents, do hereby
declare the nature of this invention to be as follows:-
In Specification No. 12665 of 1895 is described a machine for threading bolts
or forming screw threads upon blanks.
The present invention relates to improvements in the machine which enables it
to be used for producing taper or conical threaded screws and also for readily
varying the amount of taper or the length of blank to be threaded at a single
operation.
In said prior specification the roller dies are normally held apart by spring
action, and when a blank has been inserted the dies are closed in to grip same
and held in their closed in position during the rolling process by the action of a
disc or wheel operating upon the arm of a ring which surrounds the roller die
bearings and by lever action forces said dies inwards and holds them there or
permits them to open out depending upon whether the bearing between the arm
of the ring and the disc or wheel is resting upon the periphery of the latter or in
a recessed portion thereof.
According to the present invention it is proposed to substitute a cam periphery
for that of the disc or wheel still however retaining the recessed portion of the
face in order that the dies may be rapidly opened and as rapidly closed to grip.
the blank after which the bearing of the arm of the ring will be caused to pass
over a cam surface of uniformly increasing radii until the recess be again reached
and the dies opened. The result of this action will be to gradually force the dies
closer together during the threading operation and thus to produce
conical threaded bolt or screw.
a taper or
The amount of taper in a given length with dies having a given angle of thread
will depend upon the speed at which such dies are driven compared with the
speed of the cam, thus if the dies be driven rapidly and the cam slowly a long
blank having a slight taper will be threaded if the dies are slowly driven and the
cam rapidly then by comparison a short blank with a quick taper will be threaded.
To vary the speed of the cam as compared with that of the dies it is only necessary
to change the intermediate gear.
Dated this 7th day of April 1900

page_text: Improvements in Machines for Forming Screw Threads on Bolts or
other Blanks.
A communication to me from abroad by LÉON EDMOND MARIE ERNEST LEVENT, of
Lovignier-Bavay, in the Republic of France, Manufacturer.
I, PHILIP MIDDLETON JUSTICE, of 55 and 56, Chancery Lane, in the County
of London, Fellow of the Chartered Institute of Patent Agents, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
In Specification No. 12665 of 1895 is described a machine for threading bolts
or forming screw threads upon blanks.
The present invention relates to improvements in the machine which enables it
to be used for producing taper or conical threaded screws and also for readily
varying the amount of taper or the length of blank to be threaded at a single
operation:
In said prior specification the roller dies are normally held apart by spring
action, and when a blank has been inserted the dies are closed in to grip same
and held in their closed in position during the rolling process by the action of a
disc or wheel operating upon the arm of a ring which surrounds the roller die
bearings and by lever action forces said dies inwards and holds them there or
permits them to open out depending upon whether the bearing between the arm
of the ring and the disc or wheel is resting upon the periphery of the latter or in
a recessed portion thereof.
According to the present invention it is proposed to substitute a cam periphery
for that of the disc or wheel still however retaining the recessed portion of the
face in order that the dies may be rapidly opened and as rapidly closed to grip
the blank after which the bearing of the arm of the ring will be caused to pass
over a cam surface of uniformly increasing radii until the recess be again reached
and the dies opened. The result of this action will be to gradually force the dies
closer together during the threading operation and thus to produce a taper or
conical threaded bolt or screw.
The amount of taper in a given length with dies having a given angle of thread
will depend upon the speed at which such dies are driven compared with the
speed of the cam, thus if the dies be driven rapidly and the cam slowly a long
blank having a slight taper will be threaded if the dies are slowly driven and the
cam rapidly then by comparison a short blank with a quick taper will be threaded.
To vary the speed of the cam as compared with that of the dies it is only necessary
to change the intermediate gear.
In the accompanying drawings Fig. 1 shows the parts when the dies are open
ready to receive a blank to be rolled and Fig. 2 shows the position when the dies
are fully closed.
The die rollers a b c are carried by movable shafts a¹ be carried in bear-
ings hhh upon the outer ends of which bear levers or rods f the other ends of
same being carried in a movable ring d provided with an arm e through which
passes an adjustable bar i carrying a roller g constantly kept against the face of
a cam by a spring although a cord and counterweight may be used. The cam j
is driven by a shaft k. The operation of the parts as follows: when the roller
is in the recess 1 in cam j the die rollers a b c are wide apart and ready to have
the blank to be rolled placed between them. If the cam be then rotated in the

page_text: direction of the arrow until the roller g is at the point 2 the arm e will be forced
out and move the ring d and the levers or rods f will force the rollers a b c towards
each other and grip the blank and impress upon it a screw thread in the well
known manner.
As the part 2, 3, 4 of the cam is eccentric the die rollers will be gradually forced
closer together and a taper screw will be the result and by increasing or decreasing
the speed of the cam different degrees of taper may be produced.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to me
by my foreign correspondent I declare that what I claim is:-
In machines for forming screw threads on bolts or other blanks, the combination
with the movable dies or rollers, of movable bearings, a ring surrounding the
bearings, pressure levers or rods between said ring and bearings, an arm of said
ring, a pressure roller carried by said arm, a cam acting upon said pressure roller
to cause the die rollers to gradually close in upon the bolt or blank and produce a
taper on the metal being rolled and a spring or counterweight acting on the arm
of the ring to cause the dies to open so as to release the article rolled, substantially
as set forth.
1
1
801
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n
1000