Improvements in the Method of Slotting Screw Heads and in Dies therefor.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in the Method of Slotting Screw Heads and in
Dies therefor.
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 the manufacture of wood-screws and drive-screws, but more especially screws
produced by the swaging or rolling process, it is the usual practice to form the
slot for the screw-driver by swaging, simultaneously with the upsetting of the
metal to form the face of the head. An example of swaging dies for forming
finished heads of screws, including the slot, is shown and described in the
Specification to my British Letters Patent No. 12,735 of September 4th 1888.
In that Specification, however, the screw-driver nick or slot does not extend entirely
across the face of the head of the screw.
In all former attempts to produce screws having swaged heads provided with
open swaged slots, that is slots extending entirely across the heads, such attempts
have resulted almost invariably in the production of screws having imperfect heads
sometimes the defect is due to a fin of metal at the ends of the slots; sometimes
there is a lack of metal to fill the die so as to make a complete head, sometimes
there is an excess of metal, in which case the surplus stock spreads out laterally
between the face of the die and the hammer and forins a fin which must subsequently
be removed.
In such former arrangements adapted to swage the slot entirely across the head
of the screw, the die-cavity was made true and smooth; the inclined sides thereof
having an unbroken surface; the face of the finishing hammer being provided
with a tongue having the exact size and shape or counterpart of the slot to be
produced, or in other words the length of the tongue at its intersection with the face
of the hammer was just equal to the diameter of the mouth of the die-cavity, the
ends of the tongue having the same angle or inclination as the sides of the die.
When thus made it is a very difficult matter to so adjust the parts that the tongue
will find the exact center of the die in swaging the slot; and in any event there is
an amount of metal to be disposed of at the ends of the tongue which produces an
excessive strain upon the mechanism in causing the metal to flow in advance of the
moving tongue.
To produce a swaged open slot, that is extending entirely across the head of the
screw-blank or screw, and at the same time one devoid of the objections or defects
before referred to is the object of my present invention; to that end I provide the
face of the die with two or more lateral channels which extend into the die-cavity,
the size and form of each channel where it enters the inclined sides of the die being
substantially the counterpart transversely of the slot to be produced; and the face
of the finishing heading hammer is provided with a tongue adapted to enter the said
channels. The sides of the channels are cut away or enlarged so as to produce in
conjunction with the tongue a shearing action upon the metal filling the die; by.
this method any surplus metal flowing from the die through the channels by the
force of the advancing tongue during the heading operation is cut or sheared off and
falls to waste, the slotted head thus produced being free from fins or other defects
usually present in swaged screw heads having open slots. Another advantage
resulting from my improvement is that the hammer may be easily and quickly
adjusted to the die. This is due to the fact that I preferably make the tongue
considerably longer than the diameter of the die-cavity, therefore the slots can be
as accurately produced in the screw head as though the centers of the hammer and
die were always in actual alignment.

page_text: In carrying out my present invention. I usually employ a series of three hammers,
somewhat in the manner described in my Specification before referred to, that is,
the first hammer to act upon the stock or metal upsets and centralizes it in the
grooved die the next or second hammer has its face provided with a curved
portion so shaped that in operation the hammer disposes the metal alike on-each
side of the line where the slot is to be formed, or as determined by the position
of the grooves in the die; and the last or finishing hammer has a tongue extending
across its face which is impressed into the metal, thereby causing the latter.
to flow laterally and upward to fill the die, any, surplus, metal at, the same time
Howing outward through the die-channels; the. final movement of the tongue
completely severing or shearing such surplus stock from the now finished head
resting in the die.
Another advantage of my invention.lies in the facility. it gives for the production
of screws having the bottom of the slots curved instead of angular transversely; as
usually made. This is done in order to render the heads. stronger, because, other-
wise screws when made of steel, or homogeneous metal as it is called, when the slots
are made by cutting, are very liable to. fracture at the angle of the slot, when being
subjected to the strain or pressure produced by the screw driver. This property or
characteristic of steel, ie. its homogeniety; has been made 'ther subject of careful
investigation and experiment during the past two or three years, and recent
experience has also confirmed the result of such investigation, in proving that a
bar or piece of this metal is "very sensitive to a tearing action, if only a means
of starting the tear exists." A sharp angular groove or cut made in the piece
or a scratch even in some instances being sufficient to form the initial point of
the tear, the further tearing action or complete. fracture being produced by a
sudden strain or pressure, or by the jarring or vibration from hammering, &c.
In such instances the strain or pressure is concentrated at or along the angular
groove or sharp line formed in the piece of stock. Now, in order to prevent such
tearing action at the cut or grooved points just referred to, it is .found that the
metal can be made perfectly reliable by simply forming in the metal in lieu of such
angular cuts, cuts or grooves having a curved form transversely by this latter
method the strain or pressure is distributed because there is no sharp groove or
angle at which the pressure can be concentrated and produce a fracture. I can
easily give this form to the bottom of the slot of a screw head by simply rounding
the end or face of the tongue, which forms the slot.
In the appended two sheets of drawings illustrating my improvement, Fig. 1,
Sheet 1, represents a face or plan view of the die; Figs. 2 and 3 are transverse
sectional views, taken on lines and oo respectively, of Fig. 1; Fig. 4 is a side
elevation of the slotting hammer; Eig. 5 is an end view of it; Fig. 6 is a sectional
view showing the relation of the hammer and die as in use; Fig. 7 represents
sectionally enlarged modified forms of the slot-forming tongue of the haminer;
Fig. 8 shows enlarged a perspective view of the upper portion of a screw-blank
having a swaged open slot; Figs. 9 and 10 are similar views showing forms of
imperfectly slotted heads as commonly produced when swaging hammers are used';
Fig. 11, Sheet 2, shows, enlarged, a transverse section of my improved die having a
piece of wire resting therein preparatory to being acted upon by the first heading-
hammer, Fig. 12 is a similar view showing the hammer, advanced to its limit, its
action being to upset the metal and form a preliminary head centrally on the end of
the wire Fig. 13 is a perspective view of the lower or working face of the second
hammer Fig. 14 is a sectional view showing the initial head transformed by the
second hammer into. a roughly shaped head, the end thereof having a lateral
projection arranged in relation to the slot to be produced; the die-section
orresponding to Fig. 2 Fig. 15 is a similar sectional view of the parts represented
in Fig. 14, the line of cut, however, being taken at right angles therewith, or
corresponding to Fig. 3; Fig. 16 is a perspective view of the blank sectionally
represented the two preceding figures; Fig. 17 is a sectional view, showing the
die and blank resting therein, as in Fig. 15, and also showing the third or slotting

page_text: hammer advancing to produce the slot, and Fig. 18 shows the same at the end of
the operation, the tongue of the hammer having been forced into the metal of the
head, thereby swaging the slot and at the same time shearing or squeezing off any
surplus metal forced into the die-channels. The headed blank when removed from
the die being substantially as represented in Fig. 8.
My invention involves a new method of forging slots in screw heads with open
ends and the employment of a die and hammer constructed and arranged as
described below. In the drawings indicates a piece of wire resting in the die a
(Fig. 11), a centrally recessed heading hammer 6, the first to operate upon the
wire, being in the act of upsetting the metal to form the preliminary head 2, the
latter being shown by Fig. 12, and at the same time upsetting the metal in the dic
portion to form the taper-shanks. The next heading haminer, 2, to act upon
the metal, that is the preliminary head, has its face provided with a curved
depression (Fig. 13) which acts to dispose the metal across the head substantially
as shown at n in Fig. 16, at the same time the metal is still further compressed
into the die-cavity e, thus forming the approximate head, see Figs. 14 and 15.
The final operation impresses the tongue of the last or third hammer b into and
longitudinally of the slightly raised projection n of the head A.
The face of the die a, see Figs. 1, 2, 3 &c., is provided with a cavity having
inclined sides, the cavity being the counterpart of the screw-head to be produced.
A groove d is formed in opposite sides of the die-cavity, the form and size of the
groove transversely being substantially the same as the slot produced by the action
of the tongue of the hammer b. Immediately to the rear of the slot-opening or
channel where it enters the die-cavity e the channel is enlarged laterally, as at ²,
to form in conjunction with the tongue & cutting or shearing edges d', in fact the
vertical or nearly vertical sides of the grooves at their intersection with the walls
of the die-cavity may be employed for the purpose. The tongue & projecting from
the face of the slotting-hammer may have any suitable form transversely, the
channels of the die obviously having the same form; in any event, however, I
prefer for reasons hereinbefore stated to remove the lower sharp edges of the
tongue so as to produce fillets in the nicks or slots at the intersection of the
bottom and vertical sides. Figs. 4 and 7 represent different forms of the tongue.
Another novel feature of the tongue is that I make it longer than the diameter of
the cavity, or say equal to the diameter of the hammer itself. In Fig. 1, the
dotted circle indicates that the center of the hammer and die are coincident,
the other circle indicates that the said centers are not in alignment, although the
tongue of the hammer is still capable of forming a complete slot. By again
referring to Fig. 17, it will be seen that the die « contains in its cavity e the partly
completed screw-head. Now, upon advancing the hammer the tongue t engages
the raised portion of the head (Fig. 16, &c.,) to form the slot; the continued
movement of the hammer forcing the tongue into the metal to its full depth, being
also the depth of the die channels d, and at the same time forcing out and shearing
or squeezing off at the points d'any surplus metal, as m Fig. 18, and completing
the operation. Upon removing the headed blank from the die the head h will be
found to have a practically perfect slot s therein extending entirely across its face,
substantially as represented by Fig. 8.
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. die for forging slotted screw-heads having in the surface surrounding the
cavity in which the screw-heads are to be formed slots or channels extending from
such cavity in line with the slots to be formed in the screw-heads, to receive the
ends of a slot-forming tongue on the face of a heading hammer and permit the
escape of surplus metal displaced by the tongue in forming the slot.
2. A. die for forming slotted screw heads having in the surface surrounding the
cavity in which screw-heads are to be formed slots or channels extending from

page_text: such cavity in line with the slot to be formed in a screw-head, in combination with
a heading hammer having across its face a tongue to form the slot in the screw-
head and to enter the slots in the die in line therewith to remove from the screw-head
surplus metal displaced in forging the slot.
3. The method herein described for forging slots across the heads of screws and
open at the ends, by forcing into the metal of a screw-head in the cavity of a die
and into slots or channels formed in the surface surrounding such cavity and
extending therefrom in line with the slots to be formed in the screw-heads, a tongue
formed on the face of a heading bammer the counterpart in cross section of the
slot to be produced in the screw head.
Dated the 17th day of December 1890.
CHARLES DAKE ROGERS,
Inventor.