Improvements relating to the Manufacture of Screws and to Dies therefor.
Year: 1890

page_text: Date of Application, 8th Apr., 1890-Accepted, 7th June, 1890
COMPLETE SPECIFICATION.
[Communicated from abroad by THE RUSSELL AND ERWIN MANUFACTURING COMPANY,
of New Britain, Connecticut, United States of America, Manufacturers.]
Improvements relating to the Manufacture of Screws and to
Dies therefor.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co. Patent Agents,
Southampton Buildings, in the County of Middlesex do hereby declare the nature of
this invention 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 the manufacture of screws by swaging or rolling metal
blanks, and the main object of the said invention is to produce a screw having a
solid thread in contradistinction to a split thread.
Another object of the said invention is to provide for forming a cylindrical screw,
that is to say, a screw in which the threads are of the same outside diameter through-
out, or nearly throughout the length of the screw. The said invention, moreover,
comprises improved dies for use in the manufacture of such screws, which dies may
be made adjustable to adapt them for rolling screws of different sizes.
In the accompanying drawing,
Figure 1 is a face view of one of the improved dies.
Figure 2 is a transverse section of a pair of such dies, the plane of section being
indicated by the line 2, x, Figure 1.
Figure 3 is a like section, whose plane is indicated by the line y, y, Figure 1.
Figure 4 is a like section, whose plane is indicated by the line 2, 2, Figure 1.
Figure 5 is a side elevation of a portion of a partially made screw, showing
the result of subjecting a screw-blank to the action of the first portion of the dies.
Figure 6 is a like view, showing the result at a further stage.
Figure 7 is another like view, showing the result at a still further stage, and
Figure 8 is a side elevation of a complete screw as formed by the said dies.
Figures 5, 6, 7 and 8 are drawn to an enlarged scale.
My said invention is applicable to cylindrical or curved dies, and also to straight
or flat dies. It is illustrated as applied to a straight or flat die. The working surface
of the die consists of oblique grooves of the proper pitch, the beginning of the
working surface of the die or the part thereof which first acts upon the blank consists
of a series of rounded grooves a, that is to say, grooves of semi-circular or other
suitably curved form in transverse section, with narrow ridges between them; the
said rounded grooves, in the die shown, extend from the corresponding end of the
die to the point 6; these grooves are shown in transverse section in Figure 2. The
said rounded grooves a merge into V-shaped grooves in alignment therewith, the
ridges between the V-grooves at the face of the die gradually widening as they extend
on the die to the point c, and the grooves growing proportionally narrower.
wider part of these grooves is V-shaped for convenience of construction, but the
apex or bottom part at the wide end takes no part in the formation of the thread,
the said grooves might therefore be in the form of a truncated V. From the point c
to the rear end of the die, the ridges and grooves are straight and parallel instead of
tapering; these parallel ridges and grooves constitute the finishing portion of the die.
This finishing portion should be of a length equal to one-half or more than one-
half of the circumference of a screw as formed by the said dies.
The
The surfaces of the dies A, B are substantially alike except at the parts d, g, which
form the gimlet-point of the screw. The portion d follows the general profile of
the screw,
but extends beyond the plane in which the axis of the screw lies when the
said screw is within or between the dies. This plane is indicated by the line f in

page_text: Figure 4. The other die B follows the profile of the screw but is truncated at the
corner g in order to allow of the projection d of the die A extending beyond the axial
line fof-the screw.
The feature last above described may be applied to other dies than those having
the rounded grooves and straight and parallel finishing grooves. It permits the dies
to be adjusted to a certain extent for threading screws of different sizes, the degree
of adjustment being in proportion to the extent of the projection d beyond the axial
line of the screw. If the dies are separated or moved further apart, a larger sized
screw may be formed to the extreme point, so long as the projection d lies within a
plane that is coincident with the axis of the screw being threaded, that is to say, as
long as it extends up to, or projects beyond the axis of the screw.
By making the die begin its action with the rounded grooves and ridges, 'I provide
for first forming a rounded screw-thread as shown in Figure 5, which screw-thread
extends at its base to the core of the screw; in other words-the depressions between
!the threads are of the full depth of those in the finished screw, but of less width. As
the blank is further acted upon by the dies, the thread grooves are widened and the
threads projected higher and narrower, but still leaving their edge somewhat
rounded as shown in Figure 6. This action is continued until the edge of the
threads becomes narrow and substantially parallel to the "axis of the screw, the
rounded form being obliterated as shown in Figure 7, and they are finally brought
to a sharp edge. In this manner, I make a screw having a solid or unsplit thread
as shown in Figure 8.
If the grooves and ridges of the die continued their taper to the ends of the die,
the finished screw would not be quite round or cylindrical, but, by leaving a finishing.
portion, as above c, with parallel grooves and ridges, the said portion being of a
length about equal to the circumference or to one-half of the circumference of the
screw, the threads of the screw, after the said screw passes the said portion, will be
all of equal outside diameter. It is evident that this last improvement is applicable
to other dies and also that the aforesaid grooves of semicircular or other suitably
curved form in transverse section, for starting the thread; may be employed in ordinary
dies. That portion of the improved dies which, in Figure 1, is between the points b
and c is of well known construction with the exception that the projection d at the
⚫ portion for forming the gimlet-point is made to extend beyond the axis of the screw
as above described.
•
.
It will be understood that the dies are to be used in any suitable machine, and as
such machines are well known and constitute no part of the present invention, I
consider it unnecessary to make further reference to them.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed as communicated to me by my
foreign correspondents I wish it understood that I claim :-
First. The manufacture of a screw, by first forming on the screw-blank a rounded
screw-thread, and then gradually working the said rounded screw-thread to the
desired V-shape in transverse section, substantially as 'hereinbefore described.
Second. A die for the manufacture of screws by swaging or rolling, having 'its
working surface provided with a series of alternate rounded grooves and narrow
ridges arranged in combination with a corresponding series of alternate tapering
grooves and ridges, substantially as, and for the purpose; above specified.
Third. A die for the manufacture of screws by swaging or rolling, having on its
working surface a series of tapering grooves and ridges and at the end of the said
tapering grooves and ridges a finishing portion consisting of parallel grööves 'and
ridges, substantially as, and for the purposes, above specified.
Fourth. A pair of dies for the manufacture of pointed screws by swaging or
rolling, both of which have the general shape, in transverse section of the profile of
the screw, and in one of which the portion for forming the point of the screw "is
truncated while the corresponding portion on the other die is provided "with" a

page_text: projection d extending towards the companion die to a point beyond a plane coinci-
dent with the axis of the screw while between the said dies, substantially as, and for
the purpose, above specified.
Fifth. A die for the manufacture of screws by swaging or rolling, having its
working surface provided with a series of alternate rounded grooves and narrow
ridges, a corresponding series of alternate tapering grooves and ridges, and a finishing
portion consisting of parallel grooves and ridges, substantially as, and for the
purposes, above specified.
Sixth. The improved die constructed substantially as described with reference to
the accompanying drawing, for the purpose specified.
Seventh. A screw formed by rolling between the improved dies herein before
described.
Dated this 8th day of Anril 1800
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.