Improvement in Machines for Forming the Threads upon Wood Screws.
Year: 1887

page_text: Date of Application, 20th Sept., 1887
Specification Accepted, 20th July, 1888
COMPLETE SPECIFICATION.
Improvement in Machines for Forming the Threads upon Wood
Screws.
[, Charles DakE ROGERS, of Providence, in the County of Providence, State
of Rhode Island, United States of America, Mechanic, 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 :-
My invention relates to Machines of the class adapted for automatically forming
the threads upon Wood-Screws by rolling the blanks between the working or grooved
faces of suitably mounted and operating dies.
The machine herein described, which embraces my invention consists, essentially, of
the following features:-
The work of forming the threads upon the screw-blanks is performed by a pair of
straight dies one of which is fixed to the frame of the machine while the other is
secured to a reciprocating bar or shaft which carries it back and forth parallel to and
past the stationary die. A mechanism for automatically feeding the blanks to the dies
is connected with the machine so as to introduce a blank at each return of the
reciprocating die to the normal position from which its movement to form a thread
upon a blank commences. In connection with the threading-dies and the feeding
mechanism is a device, which I term a carrier, which receives the blank from the
said feeding mechanism and presents it properly to the dies and insures its proper
relations to them during the whole, or a part, of the threading operation. I consider
this feature a very important element in the manufacture of wood screws.
The machine illustrated in the annexed drawings has two oppositely arranged
complete threading, feeding and carrying mechanisms, each connected with the
reciprocating bar through which the power is applied, but each acting otherwise
independently of the other.
The improved dies for forming the threads, forms the subject of a separate
application for patent filed by me upon even date with this.
In the machine berewith, the thread of the screw is raised from the body of the
blank by compression, and by rolling between dies provided with oblique V-shaped
grooves presenting between them a series of bars or projections narrow at the end

page_text: where they commence to form the thread, and gradually increasing in width to act
laterally upon the metal between them, and force it into the
grooves.
In the accompanying four sheets of drawings, illustrating my improved screw-
threading machine :-
Figure 1, (Sheet 1) represents a plan view thereof as provided with two sets of
thread-forming dies, &c. The several parts being in the normal position. Fig. 2, is
a side elevation; the driving-head or operating mechanism being sectionally
represented.
Fig. 3. (Sheet 2) is a partial cross-sectional view, enlarged, taken on line, of
Fig. 2, showing an end view of the cross-head and carrier as mounted in the frame
of the machine. Fig. 4, is a side view thereof. A portion being broken away to show
the devices for detachably-securing the cross-head and carrier to the reciprocating
bars, which latter extend longitudinally of the machine. Fig. 5, is a plan view, in
partial horizontal section, showing the device for conducting and intermittently placing
the blanks in position, in the holder. Fig. 6, is a side view of the same. Figs.
and 8, are side and end views, respectively, of the adjustably-mounted cam adapted to
reciprocate the said conductor.
Fig. 9. (Sheet 3) is a vertical transverse sectional view of the driving-head taken
on line ww of Fig. 2. Fig. 10, is a front view of the blank holder, detached.
Fig. 11, is a similar view, having the front plate removed. The jaws of the holder
being in an open position, preparatory to receiving a screw-blank. Fig. 12, is an
enlarged vertical sectional view, taken through the center of the blank " pick-up"
driving mechanism. Fig. 13, is a transverse sectional view of the same, taken on
line o―o.
Fig. 14, (Sheet 4) is a vertical transverse sectional view taken through the holder,
carrier, thread-forming dies, &c., showing a blank in the act of being threaded.
Fig. 15, is a front view of the holder, showing the jaws closed. Fig. 16, is an
inverted plan view thereof. Fig. 17, is a detached view of the front plate, showing
its rear face. Fig. 18, is a front view showing the rear plate and the holder jaw pivoted
thereto. The jaws being closed. Fig. 19, is a front view of the rear plate, detached.
Fig. 20, is a vertical transverse sectional view thereof, taken on line s-s. Fig. 21,
is a side view of one of the jaws. Fig. 22, is a front view of an adjustably mounted
stationary stand adapted to engage the front plate of the holder, to close the jaws.
Fig. 23, is an end view of the same, and Figs. 24, 25 and 26, are detached front, pian
and end views, respectively, of the blank-feeding device.
The following is a detailed description of the screw-threading machine, including
the manner of its operation;-
A, referring again to the drawings, designates the main frame or bed thereof,
constructed to receive the several parts and devices which constitute the
machine.
B, indicates the frame of the main driving head. The latter consisting of a suitably
mounted and driven shaft, as S, and a mounted gear train, ass, s, and s³, the latter
being loosely mounted on the upper end of the main shaft. To the main gear, s³, is
fixed a pin m², the upper portion of which is fitted into a rectangular box m¹. The
latter in turn being fitted to slide in a slotted opening m, formed in a cross-head M.
This cross-head is fitted to slide in longitudinal V's formed in the upper portion of
the frame B. By means of this arrangement a rectilinear reciprocating movement is
imparted to the cross-head through the medium of the revolving gear 83, and the
connected box m¹.
K indicates a rod or bar rigidly secured to the cross-head and fitted to slide in the
main frame A.
t, indicates a tie extending transversely across the top of the frame B, and firmly
secured thereto. See Fig. 9, &c. t¹, is a short shaft mounted to revolve in bearings
formed in the tie t. To the said shaft, intermediate of the bearing, are secured the
two pinions p-p. The latter being just one-half the diameter of the pinion p. A
rack is secured to the upper side of the cross-head M, and arranged to intergear
with the larger pinion p.

page_text: L. designates an upper rod or bar extending lengthwise of the machine, the said bar
being mounted in the same vertical plane as the lower bar K, before referred to. A
short toothed rack, is secured to the underside of the bar L, by means of studs »²,
(Fig. 2). This latter named rack is made to mesh with the teeth of the small
pinion . It is obvious now, that the bars Kand L simultaneously travel in the same
direction as the cross-head M. The rate of speed of the upper bar, L, however, being
just one-half that of the lower bar.
The forming of the threads upon the screw-blanks, is effected by the use of grooved
dies, between the faces of which the blanks are rolled, thereby raising the metal from
the body of the blank into the grooves of the dies which gradually compress the metal
into a screw-thread.
In the machine herewith, each set of grooved dies E, E, for forming the screw-
threads upon the blanks, b, are arranged so that one is stationary, the other being
connected to the bar K, so as to move back and forth with it. At the place where the
stationary die is located the frame A, is made extremely strong to withstand the
lateral thrust, or pressure. This latter die is adjustably secured in position in a die-
The die-block itself,
block, U, by means of a clamp o, and binding screws o.
being adjustably secured to the main frame, by screws o. See Figs. 3, 4, 14, &c.
C, indicates a carriage or cross-head detachably-secured to the lower bar K. The
said carriage is fitted to travel freely back and forth between and upon the vertical
extensions of the frame A, which hold the stationary dies.
Immediately adjacent to the stationary die the carriage is planed out longitudinally
to receive a lie-block U, similar to the one just described; one or more screws o²,
serving to retain it in position. This latter dic-block is in like manner planed out to
receive a die E. A clamp o, and set screws o, adjustably retaining it in position.
The die being similar to the stationary die but having the ends reversed. A means,
as 0, for securing the carriage to the bar K, is represented in Figs. 3 and 4. The
lower face of the carriage being planed out to receive the bar. A strong lever a, is
pivoted at a', to the carriage and adapted to vibrate slightly in an opening formed
therein. See dotted lines. The inner end of the lever bears against an inverted spiral
spring a², mounted in a hole formed in the carriage. See also dotted lines. The
other or outer end of said lever, extends beyond the forward end of the carriage,
(Fig. 4) and is made slightly conical on its under side, at a³, to engage a corre-
A shouldered stud
spondingly shaped shallow cavity formed in the face of the bar.
or pin a, passes loosely through the lever and is screwed into the bar.
wheel as, being firmly secured to and surmounting said stud.
A hand
It is evident that when the parts are connected together, as shown in Fig. 4, the
carriage will travel in unison with the lower bar. But by unscrewing the pin a, there-
from, the bar will then travel back and forth in the carriage, the latter being stationary.
The spring a, serving to keep the forward portion of the lever from coming in contact
with the bar.
The top face of the carriage is planed out longitudinally to receive the bar L. The
latter also being partially fitted into the carrier D, which is loosely gibbed to the
carriage. This carrier, which is made somewhat shorter than the carriage, is adapted
to be detachably secured to the bar L, substantially as shown sectionally in Fig. 4,
wherein a bushing d*, beveled at its lower end, a stud a*, and a hand-wheel a³, operate
together, in connection with a guide plate d³, to firmly clamp the carrier to the bar.
The carrier may be readily disconnected from the bar by simply unscrewing the stud
therefrom, thereby permitting the carrier to remain stationary and the bar to travel as
usual. The function of the carrier is to longitudinally reciprocate a screw-blank
holder, as H, directly over the space formed by the lateral separation of the two
threading dies, and at one-half the speed of the travelling die.
The holder consists of a back plate, e, a front plate e', and the two jaws J-J,
pivoted on a pin e, attached to the back plate. The sides of the latter are planed to
fit between ways formed in an extension of the carrier. (Figs. 4, 10, &c.). A slotted
opening, is formed in the upper end of the plate e, to receive the reduced end of an
adjusting screw e, of the carrier, by means of which the holder is adapted to be

page_text: vertically adjusted. The lower portion of the said jaws J, is oppositely recessed at u¹, u,
to receive the head and the contiguous portion of the screw-blank b, for the purpose
of holding the blank in position and then to properly enter it between the grooved
faces of the threading-dies. An extension 3, of the rear jaw serves to keep the
blank in a vertical position as it is moved along, nn indicate oppositely inclined
lugs secured to the jaws. The opposed outer sides of the jaws at the bottom, are
beveled at e, to engage the lower portion of the front plate e', hereinafter
described. (See Fig. 18). A lug or lateral extension e, is formed on the lower
end of the rear plate e, the bottom face of which is adapted to bear against
the upper end of the screw-blank, thereby preventing the latter from moving
upwardly.
The front plate or cap el, is fitted to slide vertically in the ways before referred
to; gibs e², secured to the carrier serving to retain the plate laterally. The lower
portion of the front plate is beveled, at e, for the purpose of engaging the corre-
sponding surface e, of the jaws, thereby closing them firinly together. See Figs. 15
and 16.
A lug, having angular sides, is secured to the back face of the plate e¹. By
means of this construction the plate in its upward movement causes the said lug to
simultaneously engage the angular projections n, thereby forcing the jaws apart
(Figs. 10-11) and freely permitting the threaded blank to drop out at the end of
the stroke.
13, indicates a standard, the same being adjustably secured to the top of the frame A,
adjacent to the entering end of the stationary die E. I, is an extension of said
standard the same being adjustably secured thereto by a bolt . The upper part of
the piece, I, is somewhat elongated and is provided with a groove; the forward
portion of which is made quite flaring, as, the groove extending therefrom in a
cam-shape form. (Seo Figs. 22-23). "The object of the said groove being to receive
an extension or pin, 2, of the front plate e¹.
It is evident now, that as the carrier D commences to move ahead in its stroke, the
pin, coming in contact with the enlargement, of the groove, forcibly draws the
plate down to its limit, thereby at the same time firmly closing the jaws, until a blank
is properly entered between the dies by the continued movement of the carrier; as
soon, however, as the blank is fully seized by the dies, (or, later, as may be desired,)
the cam-shaped portion of the groove i, forces the front plate upwardly, (Fig. 10)
which movement also separates the jaws. The latter remaining separated until the
completion of the double stroke.
The blank feeding device R, is as follows:
Motion being imparted to the several parts thereof by a toothed rod T, secured to
the main cross-head M.
"
F, indicates a stationary receptacle or "hopper" into which the screw-blanks are
emptied; a blade or
pick-up", works vertically therein through the medium of a
rack c', (Fig. 12) housed in the casing e, (Fig. 2). A gear-wheel c, loosely mounted
on a stationary stud c, meshing with the rack T serves, in connection with the splined
hub c, and clutch-wheel c, to vertically reciprocate the blade e, from which when at
its elevated position the blanks which it may have brought up, slide into the inclined
track or runway" d. The vertical rack c', and its attachments may be readily
connected to or disconnected from the revolving gear c, by means of the said sliding
clutch-wheel c².
G, indicates the several parts entering into the construction of the separator and
conveyor by means of which device the blanks are individually taken from the
runway and automatically placed in the jaws of the holder preparatory to entering
the dies for the purpose of being threaded. Said device being secured to the frame A,
of the machine slightly in advance of the front end of the stationary die. 'referring
to the device, indicates the supporting frame thereof. (See Fig. 6, &c.). The front
portion of said frame is planed out vertically to a depth substantially equal to the
length of the blank's shank. Into this groove or channel a plate or conveyor b³,
having a thickness of the blank, is fitted to intermittently travel back and forth.

page_text: A lateral opening d¹, formed in the front side of the supporting frame, near its
forward end, coincides with and forms a continuation of the track d, (Fig. 5). A
slotted hollow spindle 62, is mounted in the frame b', (Fig. 25, &c.) its outer end being
jointed to a slotted pivoted lever, which extends downwardly and is provided with
an adjustable stop, adapted to engage a cam or wedge-shaped block w, adjustably
secured to the rack-rod T, (Figs. 7 and 8). The rear end of the plate 3, is made
cylindrical and is fitted into the chamber of the spindle 62, and opposed by the
enclosed cushion-spring d. A pin d', is secured to the rear end of the plate, the
same extending through the slotted opening of the spindle and resting against an end
of a spring A pin 69, is fitted transversely of the frame b¹, just forward of the
vertical slot d'. The inner end of said pin bears against the conveyor plate 6³,
(Fig. 25, &c.) while the latter is placing a blank in the holder. Upon retracting or
withdrawing the plate past the pin and slot d', the pin is forced ahead by means of a
light spring thereby preventing more than one blank at a time from entering the
channel. For the purpose of cutting off the column of blanks and thereby preventing
them from entering the said channel, a pin 68, shown by dotted lines in Fig. 6, is
adapted to be forced across the mouth of the opening d by a hand lever b, pivoted
to the upper portion of the frame &', and jointed to the said pin 68.
It will be observed that the drawings represent a double-acting machine. That is
to say, a set of threading-dies, together with the necessary feeding mechanism, &c.,
are mounted and arranged on each side of the machine, so that as a blank is fed to
and between the dies at one end of the carriage, the latter in its forward movement
causes the blank to be completely threaded and dropped at the end of the stroke.
Upon the return of the carriage on its back stroke the opposite set of dies receive
and thread a blank which in turn is dropped from the dies at the termination of the
stroke, as before. By means of this construction two blanks are threaded during a
double stroke of the carriage.
The operation of the several devices more in detail is as follows:
The main cross-head M, is connected with a pin mounted in the driving-gear s³, so
as to travel back and forth in either direction, a distance exceeding somewhat twice
the length of the stationary grooved die E, mounted in the frame A. The carriage C,
has a similar die E, reversely arranged and secured thereto. The carriage being
reciprocated by means of the bar K, to which it is detacbably secured by the clutch O.
The bar itself being rigidly secured to the main cross-head.
The blank feeding device R, including the stationary hopper F, runway d, &c.,
being arranged substantially as hereinbefore described. A rack T, also secured to the
main cross-lead, serving to move a blade c³, up and down in the hopper to pick up
the blanks.
<
In the system of rolling the threads on screws herewith, the screw travels
ahead at a rate of speed exactly one-half that of the travelling die. Therefore the
blank guide or holder H, and the carrier D, must travel at the same speed as the
screw. I would state here, referring to Fig. 4, that the jaws of the front holder H
of the carrier just before reaching the end of its stroke (but subsequent to passing
the front end of the stationary die) receives a blank in the cavity u, ¹, through the
medium of the conveyor 63, and the connected lever b. The latter being actuated by
the engagement of the stop 6, with the wedge-shaped portion of the block w,
adjustably secured to the travelling rod T.
•
At the instant of passing the forward "dead-center" (See Fig. 4) the blank stands
equi-distant between the forward end of the front stationary die. (shown by dotted
lines) and the corresponding end of the rear or travelling die E. Now, in advancing,
the relative speed of the parts C and D cause both the said dies to receive the blank
between them and also to engage it at the same instant from opposite sides. The
blank being kept vertical by the extension u³. While thus advancing the outer or
free end of the conveyor is gradually guided rearwardly by means of the inclined
surface de, (Figs. 5 and 16) of the rear jaw, and against the tension of the spring d.
Immediately thereafter the continued movement of the rod T carries the block
W,

page_text: away from the stop the spring withdrawing the conveyor to its limit. (See
dotted line position of lever. Fig. 6.) While the blank is axially turning between
the dies the pin, enters the cum-shaped groove i, thereby moving the front plate e¹,
upwardly, which in turn forces the jaws apart. The dies, however, still retain the
blank in position laterally, while the stop e, prevents any upward movement.
As the parts C and D pass the rear dead-center the movable die will then have
travelled past the rear end of the stationary die; the holder in this position being
relatively as far in the rear of the latter and in advance of the former die as at the
commencement of the stroke. At this time the now completely threaded screw drops
from the jaws into a suitable receptacle beneath. In returning upon the back stroke
the jaws, J, are closed by means of the passage of the pin, 7, along the same cam
groove i, the operation being substantially a reversal of the process just described for
opening the jaws. As the jaws close, or just preceding their closing, the inclined
portion of the cam-block w, causes the vertical end of the conveyor to engage a
blank and force it past the pin 69, against the inclined surface do, of the holder (the
latter travelling at the same rate as the cam-block) and finally into the recess u, u',
thereof, thus completing a double stroke of the cross-head, &c. During the operation
of threading a screw as just described, the process is repeated on the opposite side of
the machine, but in a reverse order.
The standards, 1, before described, are adapted to be adjustably secured to the
machine with relation to the stationary dies at any portion of the stroke of the
carrier. The latter also is adapted to be adjusted so as to ensure the proper relation
of the blank to the dies. It is very essential that the feeding device, carrier and
dies, be provided with means for adjustment not only for the purpose stated but also
to accommodate other sizes of blanks.
I contemplate elongating the frame A, on each side (longitudinally) of the driving-
head, and providing the same at suitable intervals with stationary dies E, feeders, &c.
At the same time also the longitudinal upper and lower bars L, K, are to be
proportionately lengthened and provided with a corresponding number of die-
carriages, and carriers C, D, respectively. By means of this arrangement it is
evident that I add greatly to the producing capacity of the machine, and at the same
time lessen the cost of attendance, &c.
By means of combined disconnecting and connecting devices O, P, one or all of
the carriages and carriers may be readily stopped and started at will while the
machine is in operation; the respective bars K, L, at the same time continuously
travelling back and forth.
The jaws J, of the carrier may be opened at any part of the stroke by simply
readjusting the cam-carrying standard.
In the use of the machine herein described it is important that the screw-blank
while being acted upon by the dies shall stand exactly vertical between them, so that
its relation to the ribs or grooves of the opposite dies shall be the same. Otherwise
the dies will not act in harmony and the threads of the screws will not be perfectly
formed. The device which I have called a carrier performs this important duty. It
receives the blanks from the feeding mechanism and presents them vertically to the
dies and holds them in that relation until the rolling has so far progressed that the
ribs of the dies have entered the metal sufficiently to prevent the blank from turning
obliquely across the face of the dies.
This machine may be so modified that the stationary die shall also be made
movable, but in the opposite direction from its companion. In such case, though the
blank will rotate between the dies, it will not change its position in the machine, and
the carrier must be made stationary. It will, however, perform the same duty in
receiving the blanks from the feeding mechanism and presenting them to the dies in
the proper relation and holding them in such relation as long as may be necessary.
Under this construction of the machine the carrier might be more appropriately
called a holder. The cam which operates the jaws of the carrier would also be made
movable.

page_text: 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 blank carrier or holder to receive the blank from a feeding mechanism and
present and hold it to the threading dies in the proper position to be acted upon by
the dies, and provided with movable jaws which are closed to hold the blank vertically,
and which are opened to release the blank to the control of the dies or to allow it to
drop from the machine when the dies have completed their work.
2. The combination of duplicate mechanisins side by side but reversed in their
action and connected with the same actuating-bars or shafts so as to form a screw
during the movement of the shaft in each direction.
Dated this 20th day of Santambor 1887
ALLISON BROS.,
Agents for the Applicant.