Improvements in Machines for the Manufacture of Screws.
Year: 1885

page_text: Improvements in Machines for the Manufacture of Screws.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co Patent Agents,
Southampton Buildings in the County of Middlesex, do hereby declare the nature
of my invention for "IMPROVEMENTS IN MACHINES FOR THE MANUFACTURE OF
SCREWS" and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
This invention relates to that class of machines for threading screws, in which
the blank is caused to roll between dies presenting corresponding surfaces, the said
surfaces having parallel ridges formed thereon at the proper angle of inclination
with the plane of motion of the dies, the said ridges impressing the surface of
the blank rolled between them, so as to form a corresponding spiral rib on the
blank; and particularly to that class of machines for rolling threads, which are
constructed to continue the rib on the blank from the body down onto a tapered or
conical point, so as to form what are commonly called "Gimlet pointed screws."
Previous to the present invention the dies between which the blanks were rolled
to form the spiral rib or thread thereon, were constructed with their surfaces
parallel to the extent of the cylindrical portion of the body of the screw to be
formed, and at the termination of that portion of the surface the faces of the two
dies converged to substantially a central point between the dies, the ridges on the
dies being continued over the converging portions to form the gimlet point so that
the surfaces of both dies worked alike upon the pointed portion of the screw, each
serving as a rest or resistance for the other.
While good results have been attained in machines constructed as above,
difficulties are at times experienced from the tendency of the blank to work longi-
tudinally between the dies under the action of the gimlet pointing portion, such
movement of the blank tending to strip or destroy the thread on the cylindrical
portion of the body.
The object of the present invention is principally to avoid this difficulty, as well
as to materially simplify the machine; and the invention consists in constructing
one of the dies with its face substantially parallel throughout with the axis of the

page_text: •
blank to be threaded, the companion die having its surface substantially parallel to
the said axis, and to the face of the first mentioned die, to an extent equal to the
length of the cylindrical portion of the blank to be threaded, and thence inclined
toward the said axis and face of the other die; the faces of the two dies being
constructed with parallel ridges at the proper angle of inclination with the plane
of motion of the dies, the ridges on the one die being continued from its parallel
surface onto the inclined portion, whereby as the blank is rolled between the said
two dies its surface will be impressed by the said ridges, and a corresponding
spiral rib raised on the body of the blank, and continued from the body down to
the point by the inclined portion of the one die, as more fully hereinafter
described.
The invention is shown in connection with a machine having one revolving die
(the periphery of which is constructed with inclined ridges,) combined with a
corresponding segment shaped die, fixed with relation to the revolving die, and
having on its adjacent surface corresponding ridges, so that the blank will be rolled
between the two with its axis parallel to the axis of the revolving die, and in such
revolution the surface of the blank will receive the impression of the ridges on the
dies, so as to form a corresponding spiral rib on the body of the said blank.
In the accompanying drawing.
Figure 1 represents a top view of the machine complete.
Figure 2 is a side elevation partly in section.
Figure 3 is an elevation of the feeding mechanism, shown at the upper right
hand in Figure 2.
Figure 4 is a vertical section on the line xx Figure 3.
Figure 5 is a top view drawn to an enlarged scale of the feed mechanism,
showing the blank fed from the upper end of the ways, and standing in front of
the delivery slide.
Figure 6 is a similar view, showing the delivery slide in the act of pushing a
blank toward the rotating die.
Figure 7 is an elevation drawn to an enlarged scale of the parts shown in
Figure 3.
Figure 8 is a vertical section taken on the line y y of Figure 5.
Figure 9 is a transverse section drawn to an enlarged scale through the dies,
showing a screw in place as finished.
A represents the frame of the machine, and B the principal or driving-shaft, to
which power is best applied by means of a pinion C working into a corresponding
gear wheel D on the driving shaft, but it may be otherwise applied.
E is the die stock or head, which is fixed to the shaft, and so as to present a
surface concentric therewith. Upon this stock a ring shaped die F is fixed, the
depth of whch corresponds to the cylindrical portion of the body of the screw to be
threaded; this presents a periphery_substantially parallel with the axis of the
shaft. Immediately below the ring F is a second ring shaped die G, which at its
junction with the ring F is of the same diameter as the ring F, but gradually
increases in diameter therefrom; the thickness of the ring G is substantially that
of the length of the pointed portion of the screw, and its increase in size or its
inclination is equal to substantially one half the diameter of the screw to be rolled.
The peripherical faces of the rings F, G are constructed with parallel ridges at
the proper angle of inclination with the plane of motion of the rings, and the rings
are firmly secured to the head so as to revolve therewith; as here represented the
path of revolution is in a horizontal plane.
"
Adjacent to the faces of the revolving dies one or more segments H are arranged,
the faces of which are substantially parallel with the axis of revolution of the ring
shaped dies F, G. The depth or width of the faces of the segment shaped dies is
immaterial, only that it should be at least equal to the length of the cylindrical
portion of the screw to be threaded. The segments H are constructed with
inclined ridges corresponding to those on the revolving cylindrical die, so that
a blank introduced at the proper point, say at one end of the segment, will be

page_text: rolled along the surface of the segment between that surface and the surface of the
revolving die, and the surface of the body of the blank will be impressed by the
ridges so as to form a spiral rib on the body of the blank, as indicated in Figure 9,
where the blank is shown as having the thread completely formed.
The formation of the thread by the revolving dies is progressive, from its com-
mencement at one end of the segment until it is discharged fully formed at the
opposite end.
In illustrating the invention, feeding devices are shown which are designed to
successively deliver blanks between the dies at the proper time, so that the blanks
shall be successively taken by the revolving die, and rolled along between the
revolving and stationary dies, and delivered from the machine. The illustration
of the feeding device does not require description as it constitutes no part of the
present invention. Any of the feeding devices heretofore employed for similar
machines may be used.
The blanks, preparatory to being rolled, are pointed, as indicated in Figure 8,
and being properly delivered to the feeding, device are delivered successively to the
dies, as seen in Figures 5, 6, and 8.
As the blank passes between the revolving and stationary dies the ridges on the
face of the two dies firmly grasp and support the blank while being rolled, at
the same time the single ridges on the inclined portion of one die operate upon
the pointed portion of the blank, so as to continue the rib on the blank from the
cylindrical portion down on to the point, as seen in Figure 9.
As the pointed portion is not grasped between opposing surfaces, the tendency
to raise the blank under the action or formation of the rib on the point, is
avoided.
The parallel portion of the die firmly supports the blank against the action of
the single inclined portion, so that the point, whatever its inclination, will be
concentric throughout.
A great advantage of this improvement arises from the fact that one die, having
its surface parallel with the axis throughout, may be made of a depth sufficient for
the longest screw to be threaded, and thereby serve for all lengths of screws having
one particular pitch of thread.
In all screws having the same pitch of thread the point is the same, hence the
same ring shaped die G will serve for all lengths of screws, it only being necessary
then to supply the cylindrical ring shaped die F for the depths corresponding to
the varying lengths of screws, so that by simply changing the ring F and adjusting
the pointing ring G, the same stationary segment die and the same ring will serve
for all lengths of screws of the same pitch. The two rings F, G however may be
made as one if preferred, and the segment may be made of a depth only corre-
sponding to the length of the cylindrical portion of the blank to be threaded, but
by constructing the rings in two parts, and the segment of maximum depth, a very
considerable saving in expense in the construction of dies is made.
In thus far describing the invention the threading has been shown to be per-
formed by one revolving die, in conjunction with its segment, but the process of
threading may be performed by the use of several such revolving dies with their
corresponding segments, the invention is therefore not to be understood as limited
to the formation of the thread in a single pair of dies.
The fixed or segment shaped die is represented as having its surface parallel
throughout with the axis of the blank to be rolled, and the revolving or moving
die as having its surface parallel with the axis of the blank to be formed, to the
extent of the length of the cylindrical portion of the blank to be threaded, and the
remainder of its face inclined corresponding to the point to be formed, but this
arrangement may be reversed, and the revolving die be cylindrically ridged, and
the segment have the pointing portion of its face inclined toward the moving die.
While it is preferred to perform the rolling operation by means of a cylindrical
die combined with a segment shaped die, the face of one of which is substantially
parallel throughout with the axis of the blank to be rolled, and the other parallel

page_text: with the said axis to a depth equal to the length of the cylindrical portion of the
body of the blank to be rolled, thence gradually inclined toward the opposite die
to the depth of the pointed portion of the blank, the said inclination being
substantially equal to one half the diameter of the point, the dies may be straight,
one or both receiving a reciprocating motion as in well known machines for
rolling screws.
•
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
First. In a machine for rolling threads on screws, the dies between which the
blank is rolled baving parallel ridges formed thereou at the proper angle of
inclination with the plane of motion of the dies, the face of one of the dies being
parallel throughout with the axis of the blank to be rolled, and the face of the
corresponding die also substantially parallel with the said axis to an extent equal
to the cylindrical portion of the blank to be threaded, and thence inclined toward
the opposite die, the depth of the said inclination being substantially equal to the
length of the pointed portion of the blank, and the inclination substantially equal
to one half the diameter of the blank, substantially as described.
Second. In a machine for rolling threads or screws, a rotating die and a stationary
curved die in which the working faces for impressing the threads upon the body
of the blank present parallel ridges at the proper angle of inclination with the
plane of motion of the rotating die, the face of one die being substantially parallel
throughout with the axis of rotation, and the face of the other die parallel with
the axis of rotation, to a depth substantially equal to the threaded portion of the
screw to be produced, and thence gradually inclined toward the opposite die, the
depth of the inclined portion being substantially equal to the pointed portion of
the screw to be produced, and the inclination substantially equal to one half the
diameter of the blank, substantially as described.
Dated this 10th day of October 1885
HASELTINE, LAKE & Co.,
For the Applicant.