Improvements in Dies for Making Rolled Wood Screws.
Year: 1890

page_text: Date of Application, 11th Nov., 1890-Accepted, 13th Dec., 1890
COMPLETE SPECIFICATION.
Improvements in Dies for Making Rolled Wood Screws.
I CHARLES DAKE ROGERS of 21 Stevens Street Providence in the State of Rhode
Island United States of America Works Superintendent 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:-
Dies of the class forming the subject of the improvement hereinafter described
and claimed have been employed before in the manufacture of rolled-thread wood
but the particular type of screw to which my present improved dic relates is
that known as gimlet-pointed wood screws.
screws,
Heretofore it has been the usual practice to provide the working faces of thread-
rolling dies with a series of inclined parallel ribs and grooves, the form or contour
of the die transversely, taken through its face, being substantially alike throughout
the length of the die; or in other words, the ribs are so arranged that they produce
the threads both upon the cylindrical or shank portion and the point portion
simultaneously.
An objection to the use of such former dies, irrespective of the shape of the ribs
cross-sectionally, is that the portion of the dies adjacent to the point portion of the screw-
blank when properly entered between them is beveled at an angle substantially like
that of the blank; such beveled portion extends throughout the length of the die and
is provided with thread-forming ribs and grooves, which are a continuation of the
ribs and grooves formed on the plane portions of the die, substantially as before stated.
Now, when dies thus made are employed, it is evident that the ribs are acting at
once upon the entire portion of the blank's surface which is to be screw-threaded;
such simultaneous action renders it difficult for the blank to maintain itself in a proper
position or relation until the completion of the screw-threads. It is, in fact, due to
this cause alone that a considerable portion of the product is rendered imperfect or
unsaleable. Moreover, as a result of such former construction of dies, it is clearly
apparent that the cone-shaped or point portion of the blank must slip more or
less upon the dies during its passage between them or while being acted upon by
them, even though the cylindrical portion of the blank does not slip at all during the
operation.
The object I have in view in the invention illustrated and described herewith is to
produce a die for rolling the threads of gimlet-pointed wood screws which is free from.
the objections or disadvantages before referred to as incident to the use of dies
heretofore made; to that end, my invention consists, essentially, of a die having its
lower or point-threading portion cut away at the front end so as to not engage the
cone-shaped point portion of the blank until the ribs have commenced to act fairly
upon the cylindrical part of the blank; the lower portion of the die from this point
gradually increases in height in a bevel form above the general surface, and is also
provided with thread-forming ribs and grooves communicating with those of the
main portion of the die, until at or nearly to the back end of the die the raised
bevel-shaped portion has a form transversely the counterpart of that to be given to
the threaded screw point. By means of my improved dies the screw-thread is gradually
produced upon the point portion, the same commencing at the base of the point and
terminating at or near the end of the screw when the dies have nearly completed
their movement. In view of the foregoing, it is evident that the blank is to a great
extent prevented from slipping.
In the accompanying drawings, Figure 1 represents a side or front elevation of a
thread-rolling die embodying my improvement, the same having its working face
provided with inclined ribs and grooves, and having the lower portion cut away, and
also provided with inclined ribs and grooves gradually increasing in length and

page_text: communicating with those of the other portion of the die, the shaded portions
indicating the ribs; Fig. 2 is an elevation of the lower side; Figs. 3, 4 and 5 are
cross-sectional views taken on lines a a, b, and c c of Figs. 1 and 2.
A indicates my improve die as a whole, although the proportions are somewhat
exaggerated. The die as drawn is straight and is arranged and adapted to be used
in a reciprocating manner. My improvement may, however, be advantageously
used on curved dies.
designates the ribs and g the grooves formed between the ribs. I make no
claims herewith to any specific form of ribs and grooves, as they may have any
suitable shape transversely, if adapted to the work required of them. The ribs
should present as little surface or area as possible to the screw-blank, so that they
can be the more readily impressed into the metal; the form of the ribs and grooves
should change so that at the opposite end of the die the grooves are the counterpart
of the screw-threads to be produced.
The major portion of the working face of the die longitudinally is flat or sub-
stantially uniform in height throughout; the dotted line, Fig. 2, indicates the
face of the ribs of such portion and g' the bottom of the grooves. By referring
to said Fig. 2, it will be seen that the die has a wedge-shape portion along its
edge, the same commencing at the right, or as drawn, the entering end, substantially
flush with the ribs or surface ; from this point it extends longitudinally of the
die in an incline « until it reaches a point n near the opposite end, and from thence
it extends, as at a¹, substantially parallel with, but higher than, the line to the
end; the vertical distance (see also Fig. 5) between these lines a' and being
substantially equal to the semi-diameter of the screw at the core or bottom of the
screw-thread.
The inclined flat surface or portion a could be removed up to the line h, Fig. 1,
without materially affecting the manner of the action of the die upon the metal;
such portion is left, however, because it is more convenient, and at the same time the
die is rendered more symmetrical.
It will be seen by referring to Fig. 1 that the inclined or beveled point-threading
portion p of the die extends rearwardly in a gradually increasing manner, as indicated
by the inclined line h; the line ss parallel with the upper edge of the die indicating
the intersection of such portion with the main portion . By reason of this con-
struction the cone-shaped point of the screw-blank is gradually threaded, the several
ribs of a pair of such dies successively acting upon said point until at the end of
the operation the screw drops from them fully threaded.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
A die for forging the threads upon a screw by rolling, having at its entering end
a plane surface only, provided with ribs to form the threads on the cylindrical
portion of the blank, and towards the finishing end a surface inclined to the plane
surface and corresponding to the surface of the point of the screw-blank provided
with ribs which engage in succession with the metal to form the threads on the
point.
Dated the 10th day of October 1890.