Improvements in Screw-blanks and in Dies for Rolling Wood Screws.
Year: 1890

page_text: Date of Application, 11th Nov., 1890-Accepted. 20th Dec. 1890
COMPLETE SPECIFICATION.
Improvements in Screw-blanks and in Dies for Rolling 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 :-
In another application for Letters Patent filed by me simultaneously with this under
No. 18156 of 1890 I have described and claimed a die for rolling screw-threads
upon gimlet-pointed wood screws. In that die the formation of the thread upon the
cone-shaped point of the screw-blank by means of a gradually increasing beveled
surface provided with ribs and grooves constituted the novel features of the invention.
In my present invention, the die possesses certain features set forth in said companion
application.
In still another application for Letters Patent filed on the 21st day of October 1890
No. 16,765 I have described and claimed a wood screw having a novel point. This
screw has the lower or entering part of its point portion provided with an unthreaded
sharpened spur-like extension, having a cone-shape form; the other part of the point
portion is also cone-shape and provided with one or more screw-threads, the angle or
inclination of the side of the threaded part of the said point portion exceeding that of
the unthreaded part.
In making screw-blanks provided with the novel point portion, just referred to, the
cutting-off dies frequently produce a "fin" of metal on the points; aside from this
defect, the points vary somewhat in form and size, even though the cutting-off dies
remain unchanged, the result being that when the blanks are subjected to the action of
thread-rolling dies, such as usually made, the screws thus produced will be more or
less imperfect or unsalable, such defect being due to the presence of a varying
amount of metal in the point portion of the blank, as stated. Another objection to
the screws thus produced by such former thread-rolling dies is that the blanks are
usually rattled before being threaded; that is, a quantity of blanks are placed
within a suitably mounted revolving vessel or barrel, which operation serves to
brighten the blanks and at the same time to remove any
thein; but incidental to this rattling operation it is found that the sharpened ends of
chips," &c., adhering to
the blanks become very much worn or blunted, so that when the blanks are screw-
threaded and ready for use, the unthreaded end portion no longer possesses a
sufficiently sharpened tip.
The object I seek to attain by my present invention is to overcome the disadvantages
or objections before referred to. This I am enabled to accomplish by means of a
hread-rolling die having the lower or point-threading portion of its working face cut
way at the front end, so as to not engage the cone-shaped point portion of the blank
ntil the ribs of the die have commenced to act fairly upon the cylindrical part of the
lank; the said lower portion of the die gradually increases in height from this point
na bevel form above the general surface longitudinally, and is provided with thread-
orming ribs and grooves communicating with those of the main portion of the die,
uch increase extending until a point is reached where the raised bevel-shaped portion
as a form transversely the counterpart of that to be given to the threade i portion of
he screw-point; from this portion or point in the die the latter extends rearwardly
long its lower side in an ungrooved beveled surface, the angle of which is less than
at of the said grooved beveled portion.
By means of my said improved dies, when suitably mounted and operated, the
rew-thread is gradually produced upon the cone shape point portion of the blank
e dies at the same time rolling the thread upon the cylindrical portion of the blank)

page_text: the formation of the thread commencing at the base of the point and terminating about
midway of the point portion, or at the intersection of the threaded and unthreaded
parts. The die trom this point throughout to the rear end is substantially uniform
cross-sectionally, but having in addition its lower side or edge provided with a smooth
beveled surface, the angle of which is less than that of the grooved beveled portion.
This peculiarity of the die acts to reduce and elongate the corresponding smooth portion
of the screw to a uniform size and shape, the product being a rolled-thread screw
having its point portion provided with a screw-threaded cone-shape part and a
sharpened unthreaded part, the angle of the latter being less than that of the threaded
part.
In the annexed drawings, Figure 1 represents a side or front elevation of my
improved thread-rolling die, the same having its working face provided with inclined
ribs and grooves, and having the lower portion cut away and provided with inclined
ribs and grooves which gradually increase in length and communicate with those of
the other portion of the die, and further having the rear part of the die along its lower
edge provided with an ungrooved beveled surface, the shaded portions indicating the
ribs; Fig. 2 is an elevation showing the lower side of the die; Figs. 3, 4, 5, 6 and 7
are cross-sectional views, taken respectively on lines a a, b, c c, d d, and ee of
Figs. 1 and 2 Fig. 8 is a side elevation of the lower portion of a screw-blank when
properly shaped; Fig. 9 is a similar view showing a fin of metal on opposite sides, as
produced by the cutting-off dies; Fig. 10 shows the same after "rattling";
Figs. 11, 12, 13 and 14 represent the gradual development of the screw-thread and
point, the several die-sections being taken on lines a a, b b, c c and e e, respectively,
of Figs. 1 and 2; and Fig. 15 shows a blunt point.
Again referring to the drawings, D designates my improved die as a whole, the
proportions as drawn being somewhat exaggerated. The dic represented is straight
and adapted to be used in combination with a similar die in a reciprocating manner.
The improvement may be used on curved dies.
The shaded portions (Fig. 1) indicate the inclined ribs s; the grooves between the
ribs are indicated at t. The form or shape of the ribs and grooves transversely may
be any desired, if adapted to the work required of them. As drawn, however, the
angle of the sides of the ribs is substantially uniform or constant from one end of the
die to the other. In any event the face of the ribs at the front or entering end should
present as little surface or area as possible to the metal of the screw-blank, so that
they can be the more readily impressed into it; the form or area of the ribs at the
opposite end of the die should vary from those at the entering end, so that the grooves
form the counterpart of the screw-threads to be produced.
The greater portion of the working face of the die D longitudinally is flat or
substantially uniform in height throughout; the dotted line s¹, Fig. 2, &c., indicates
the face of the ribs of such portion, and t the bottom of the grooves. In Fig. 1, the
horizontal line a indicates the point of intersection of the surface s¹ of the ribs with
the gradually increasing grooved beveled surface j adapted to produce the screw-
threads on the cone-shaped part pl of the point portion p of the screw-blank. Io
Fig. 2 it will be seen that the die has a wedge-shape portion m along its edge, the
Same commencing at the right or entering end, flush with the surface of the ribs s or
line from this point it extends for about three-fourths of the length of the die in
an incline; from this point rearwardly it extends in a transversely beveled ungrooved
portion n adapted to roll the sharpened conc-shaped part p² of the point portion of the
screw. The inclination or angle of this portion n of the die is somewhat less than that
of the contiguous grooved portion j, the intersection of these parts n and being
indicated at z. By means of the gradually increasing beveled surface ; provided
with the series of thread-forming ribs and grooves which terminate therein, as at w,
the work of forming the threads upon the point portion p' of the blank is greatly
reduced and the proportion of defective screws is reduced to a minimum.
It is to be understood, however, that it is not essential to my invention that the
point of the blank shall have the two conical surfaces of different inclinations to the
axis of the blank, or that the die shall have the provision for threading the point at

page_text: the end of the rolling; the effect of the inclined smooth portion to act upon the
point being the same on a point which is a simple cone or which is to be left smooth
over its whole surface.
In producing wood screws by means of my improved dies D, when suitably mounted
and operated, the "rattled" blank (Fig. 10) is introduced between the dies at the
right or entering end (see also Fig. 11), which immediately commence to form the
threads upon the cylindrical portion o of the blank; the continued movement of the
dies gradually develops the thread and at the same time by means of the grooved
beveled portion gradually forms the thread upon the point portion p'; see
Figs. 12 and 13. Now, when the blank or screw arrives at or near the portion of the
dies indicated at dd, Figs. 1, 2 and 6, the screw will be found to be practically
completed as regards the screw-threads, but the spur-portion p² will be still blunted,
as at 6, and otherwise imperfect, because the dies up to this point have not acted upon
such spur-portion; therefore the further travel of the dies will cause the ungrooved
beveled portion to engage the spur p², and by rolling reduce and elongate it to a
sharpened point ', so that as the dies pass each other at the end of the operation,
the screw produced will be found to have the part pl of the point portion properly
threaded and the part p² reduced to a true form and sharpened point.
In Fig. 15, the angle of the sides of the conical point portion of the blank is less
acute throughout than the spur-portion p², shown in Figs. 8 and 14; consequently
it is obvious that its entering or driving capacity is rendered correspondingly more
difficult.
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 :-
―
1. A screw-blank having a conical point with a section between the base of the
cone and the cylindrical portion of the blank forming the frustrum of a cone less
acute than the cone forming the point.
2. A die for threading screws by rolling provided with smooth beveled surfaces to
act upon the conical portion of the blank, while its cylindrical portion is being
threaded, and bring it to the proper size and shape before a thread is formed thereon
by a grooved portion of the beveled surface at or towards the finishing end of
the die.
Dated the 10th day of October 1890
CHARLES DAKE ROGERS,
Philip M. Justice,
Inventor.
55 & 56, Chancery Lane, London, Agent for the Applicant.