Improvements in Machines for Cutting Screws.
Year: 1889

page_text: Date of Application, 3rd Dec., 1889-Accepted, 19th Apr., 189
COMPLETE SPECIFICATION.
Improvements in Machines for Cutting Screws.
I, WILLIAM SAMUEL DORMAN, of No. 210 North Holliday Street, in the City of
Baltimore, in the County of Baltimore, and State of Maryland, United States of
America, Manufacturer, do hereby declare the nature of my 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 has relation to Machines for making Wood Screws, of that
construction wherein the screw blanks are fed through a hollow spindle, engaged by
grippers as they emerge from the spindle and gripped and cut by automatically
griping and cutting mechanism. The object of my invention is to simplify and
improve existing mechanism used to accomplish the manufacture of screws. My
invention therefore, consists in the novel construction of parts, and their combination,
as will be hereinafter specified, and explained, and specially as the same is laid in
the claims.
I have fully and clearly illustrated my invention in the accompanying drawings,
wherein :-
Figure 1 is a side view of the machine,
Figure 2 is a side view of the same, taken on reverse of illustration in figure 1,
Figure 3 is a front view in elevation,
Figure 4 is a plan view showing the gearing,
Figure 5 is a central vertical section of the hollow feed-spindle, the belt-pulley, and
sliding sleeve; also showing the griping-jaws, and the means for automatically holding
and dropping the blanks,
Figure 6 is a central sectional view of the lower part of the hollow-spindle and the
griping-jaws engaging a screw-blank,
Figure 7 is a similar view showing the griping-jaws opened and a finished screw
being discharged from their grasp,
Figure 8 is a bottom view of the hollow spindle, showing the "knock-out" plate
secured thereto,
Figures 9 and 10 are views of the blank-holding pins detached from their positions
on the hollow-spindle,
Figure 11 is a longitudinal section of the machine taken on the line x-x of
figure 1,
Figure 12 is a longitudinal section taken on the line y-y of figure 1,
Figure 13 is a plan view of the leader-cam which gives the pitch to the threads of
the screw,
Figure 14 is a plan view of the cam which operates the cutting-jaw,
Figure 15 is a a plan view of the cam which operates the back-rest jaw,
Figure 16 is a detail view partly in section showing the arrangement of the
cutting and back-rest jaw,
Figure 17 is a side view of the cutting-jaw,
Figure 18 is a side view of the back-rest jaw,
Figure 19 is an enlarged perspective of the cutting-tool,
Figure 20 is an end view of the cutting-tool,
Figure 21 is a detail plan view of the lever which moves the sleeve on the hollow
spindle to open and close the griping-jaws.
Referring to the drawings, wherein the same notations are used to designate like
parts, in the different figures, A, designates the supporting frame of the machine.
This can be made of such shape or parts as to properly take and hold the several
elements making up the machine. I have constructed it to consist of a substantial
bed-piece 1, adapted to be fixed in position to a support by any of the usual fastening
means. In this bed-piece are formed seats for the cam-spindles, and an aperture for

page_text: The
the screw-pitch pin, as hereinafter specified. From the bed-pieces are projected two
substantial standards 2, 3, formed and connected at their upper ends with a top-
piece 4, which is extended back as shown in figures 1 and 2, and provided with
bearings from the cam-spindles. At the front of the vertical part of the frame are
upper and lower projections 5, 6, formed with bearings for the hollow-spindle, and
provided with bearing-caps 7, 8. At the rear of the frame is a vertically arranged
spindle 9, held in bearings 10, 11, in the frame. On the spindle 9 is mounted a
horizontally arranged cam 10x, (see figures 12 and 14) which engages the rear end
of the lever or bar carrying the cutting-tool. This cam is irregularly stepped on its
circumferential face substantially as shown in figure 14 of the drawings.
construction of this cam and its functional effects on the lever of the cutting-tool are
as follows: It is designed to admit the inward movements of the rear-end of the lever
of the cutting-tool when not cutting the thread of the screw, and also to operate the
lever so as to give the requisite number of cutting strokes of the tool during one
revolution. To effectuate these objects a step 11* is formed in the cam from the foot
of which the face forms a true circle 12, for a distance substantially one-fourth of the
distance around the cam, this circular part terminates in a preliminary-step 13,
intended to throw the cutting-tool gradually into operation. The succeeding steps,
designated 14, 15 and 16, respectively, represent the distance travelled during the first,
second, and third cuts of the cutting-tool, and as shown, these steps exceed each other
in height; and have between them the idle-steps 17, 18, which permit the end of
the lever of the cutting-tool to move inwards and free the tool from the screw while
moving vertically as hereinafter specified.
At the termination of each of the step-surfaces 14, 15, and 16, the faces are
abruptly extended, as seen at 19, which construction moves the lever and carries the
cutting-tool deeper at the end of the screw-blank and thus tapers the end and forms
the point of the screw. These projections 19 are only essentials in cutting gimlet-
pointed screws; and can be dispensed with in cutting straight or machine-screws.
Another cam 20, is also mounted on the spindle 9 and serves to operate the back-
rest lever. This cam is a true circle for substantially three-fourths of its circumference,
and is formed with a stop-space 21, which permits the lever to swing inwards and
open to that extent.
22, (see figure 18) designates the lever in which the back-rest is lodged, and 23,
(see figure 17) is the lever which carries the screw-cutting tool. The back-rest lever
is substantially of the shape shown in figures 12 and 18, having its rear portion
extended straight horizontally, and curved laterally, and its forward part or arm
curved upward and inwards and provided with a seat for the back-rest. The seat is
preferably circular and is partially formed in the lever, as at 24, and partially in a
cap 25, secured to the lever end substantially as shown in figure 12. The back-rest 26
consists of a steel plug arranged in the seat provided for it, and is formed with
a number of vertically arranged grooves 27, in which the neck of the screw is
held.
23, is the lever which carries the screw-cutting tool. It consists of a metal bar
substantially straight in its horizontal direction, and curved as shown in figure 12 in
lateral direction. In the forward end of this lever is a bit seat 29, made to take the
cutting-tool, and provided with a bit-clamp 30, by which the bit or tool is held to the
lever. In the rear end of each of the levers 22 and 23 is formed a slot 31, in
which is fixed a bearing-piece 32, made adjustable by means of adjusting screws 33.
These bearing-pieces are preferably of brass or other similar material not liable to
unduly. wear the surface of the cams. The contact of the levers with the cams is
accomplished by means of springs 34, fixed in the frame, and arranged to bear with
their free ends on the levers substantially as shown in figure 12 of the drawings.
The lower lever being that designated as 22, is mounted on a sleeve 35, arranged in
a hole in the bed of the machine and secured therein; and the lever 22, is fixed on
the leading-bar 36, by any suitable fastening-means. I have shown it as secured
by a set-screw 37. The leading-bar 36 bas its lower end arranged in the sleeve 35
in the bed of the frame, and at its upper end is secured a cross-bar 38, to the ends

page_text: of which are attached the lifting-springs 40. 41, having their upper ends connected to
the sides of the upper part of the frame, substantially as seen in figures 1, 2, and 3.
The upper end of the lever-bar is inclined, as seen at 42, to conform to the pitch or
incline of the leader or screw-pitch cam hereinafter described.
In
A vertically arranged shaft 43, is suitably mounted in bearings in the frame of the
machine, and thereon is fixed the leader or screw-pitch cam 44, this cam is a plate
arranged at a spiral incline on its under face in horizontal direction conforming to
the pitch of the screw to be cut and to the length of the threaded part of the screw.
the under face, which is the working face, is a step 45, at the junction of the highest
and lowest points of pressure.
This cam bears with the under face on the spring-
supported leader-bar, and at the start of the cut is in the position shown in figure 1 of
the drawings, and being carried around in the direction of the arrow it pushes the
leader bar downwards, continuing the operation until the step is reached, when by
the action of the lifting springs the leader-bar is lifted vertically into engagement
with the cam.
The reciprocating movements of the leader-bar correspondingly
carries the cutting-tool lever, in its strokes and engagements with the screw-
blank.
B, denotes the hollow spindle through which the blanks are fed to the cutting-
mechanism. This spindle is held in the projected bearings on the front of the frame.
On the spindle is fixed the driving-pulley 46, which being connected to the power by
a belt (not shown) the spindle is revolved and through the gearing carried by it, in
connection with the other gearing of the machine, motion is communicated to the
several elements of the mechanism: The lower end of the spindle is enlarged in
diameter and formed with upper and lower annular collars 47, 48, between which the
lower bearing box of the spindle is arranged. This construction and arrangement holds
the spindle against vertical displacement in either direction. In the lower and enlarged
part of the spindle are two vertically arranged mortises 49, 50, having their lower
ends open through the end of the spindle, to admit the screw-griping jaws.
C, denote the screw-griping jaws substantially of the shape shown in the
drawings, in figure 5, and pivotally swung in the spindle or bearings 51, near
their lower ends. The griping-jaws are provided with griping-pieces 52, arranged
to meet under the end of the spindle and clamp the blank substantially as seen in
figures 5 and 6. At the upper end of the griping-jaws are adjusting-screws, 53,
which set against the surface of the conical sliding sleeve 54, on the spindle, and by
the adjustment of these screws the bight of the jaws may be regulated to engage
different sized blanks. The inward movement of the upper ends of the griping-jaws
I have
is effected by means of springs, arranged to bear thein in that direction.
shown the springs as arranged on short plugs let through the collar 47 on the spindle
and bearing with their full ends in seats formed in the back of the griping-jaws,
as seen at 55. On the spindle B is the sliding-sleeve 54, having its under face 56
inclined or rounded off rather abruptly; and at the upper portion thereof is an
annular-groove 57, which is engaged by the lugs on the yoke 58 of the lever 59.
This lever 59 is mounted on a fulcrum 60, arranged across and between the side-
pieces of the frame. This lever is provided with an aperture 61, to take the vertical
shaft of the pitch-cam, and prevent the lateral movement of the lever and at its end
has a roller 62, to run on the cam which operates the lever. On the spindle 9 is a
cam 63 having a plain bearing surface for about three-fourths of its circumference,
and formed with a step 64, down which the end of the lever is carried by the
cap 65; from the race thus formed a horizontal part 66 and two steps 67, 68, carry
the lever upwards to the surface of the cam. These steps occupy one-fourth of the
distance around the cam. When the cam moves with the lever on the part 66 the
sliding-sleeve on the bollow-spindle is lifted to its upper limit, and the griping-jaws
are wide open, then as the lever is raised by the step 67 the sleeve is depressed or
lowered partially and the jaws closed far enough to prevent the head of the blank
falling out of their partial grip, and as the lever ascends the step 68, the jaws are
closed and their full grip exerted on the blank, when the lever is carried to the plain
of the cam.

page_text: The feed of the blanks to the action of the cutting-mechanism is ccomplished and
regulated by the following described means:-The blanks are fed into the bore 69 of
the spindle at the top and descend by gravity until the lower one is 'arrested by the
first stop 70, (see figures 10 and 5) which consist of a wire of sufficient size bent into
angular shape substantially as shown, having one arm longer than the other. This is
arranged in holes made transversely through the spindle: in the part between the
griping-jaw-seats and has a limited sliding movement therein; the long arm projects
through the spindle at this part and rests with its end against the inner face of the
griping-jaw, while the short arm of the stop projects partly across the bore of the
spindle. A spring 71 bears with its free end on the bridge of the stop and pushes it
so as to keep the end of the long arm lodged against the griping-jaw, and also
normally holds the stop so that the short arm extends far enough across the bore of
the spindle to admit the blank to continue its descent and be caught by the head as
shown in figure 5. Below the stop 70 is the second stop 72, (see figure 9) consisting
of a straight piece of metal having its end let into a threaded hole in the griping-
jaw and its body arranged in a hole in the spindle. This stop 72 will be perceived bas
a reversed movement across the bore of the spindle to that of the top 70, and hence
catches a blank after the upper stop has released it. The object will be readily per-
ceived: The upper stops receives and holds a blank while the griping-jaws are closed
and in engagement with the neck of the screw being cut, which operation being com-
pleted the jaws are opened to discharge the screw; the same movement which opens
the bight of the jaws also pushes the upper stop so that the short arm releases the
head of the blank which drops down until it is arrested by the lower stop, which has
been moved inwards across the bore by the inward movement of the griping-jaw.
The blank is so held until the movement of the mechanism commences to close the
griping-jaws, and withdraw the stop, when the blank drops down and out of the spindle
lodging with its head on the jaws, which have not been moved at this time so as to
prevent the passage of the stem of the blank between their griping-faces; the grip is
completed after the blank is lodged as stated.
Across the face end of the spindle is secured a knock-out plate 73, having a
central aperture large enough to admit the passage of the head of the blank. This
plate serves to knock out the finished screws from their contact with one or the
other of the jaws. The grip being a strong one the blank sometimes sticks to one or
the other of the jaws and is carried with it in opening, failing to drop, but by means
of this plate, the screw is freed from the jaws when it strikes the edge of the aperture,
as indicated in figure 7 of the drawings.
The various elements of the machine are operated by gearing arranged on the top
of the frame: On the screw spindle is a small-gear wheel 74, meshing with a large
gear-wheel 75 having its shaft in a step bearing in the top of the machine-frame, and
carrying a smaller gear-wheel 76, which meshes with a large gear 77, on the upper
end of the shaft of the screw-pitch cam; on this shaft under the gear 77 is a small
gear 78 which meshes with a larger gear 79 on the rear cam shaft. The gearing is
proportioned so as to turn the screw pitch cam, as geared in the drawings, one
revolution to sixteen of the spindle, and to revolve the rear cams one revolution to
sixty-four of the spindle.
D, designates the cutting-tool. This consists of a steel body formed with a beveled
bit-end 80 and a series of tapping grooves 81 graduated according to the pitch of the
threads of the screw; and at the lower portion is provided with a point-cutting bit 82
curved on its cutting line to form the point of the screw.
The operation is as follows: The machine being put in motion, the blanks may he
supplied to the hollow spindle by any proper or known means, and drop by gravity
down until one of them reaches and is lodged at the first stop in the spindle; the jaws
being closed to effect this object, the blank is so held until the jaws again open, and
the upper stop moved from across the bore of the spindle and the blank released and
dropped down, to be engaged and held by the lower stop; which by the inward
movement of the upper part of the griping-jaws has been moved to project partly
across the bore of the spindle. The blank is thus held by the lower stop until the

page_text: movements of the machine again gradually and partly close the jaws, when the blank
is released and dropped to be engaged by the grip of the closing-jaws. At this condi-
tion of the mechanism, the back-rest is moved into contact with the stem of the
blank, and the cutting tool is brought into action by the instrumentality of the cam
and pitch-bar, and engages the stem of the screw-blank, which is revolved with the
spindle; the pitch-cam carrying the pitch-bar down and with it the cutting tool, thus
completing one cut of the tool; the tool holding lever by this time has reached
the first idle-step in the operating-cam and is thereby freed from the screw and
carried upwards by the spring actuated leader-bar and thrown again into cutting
contact with the screw by the next step of the cam, and this operation repeated at the
next idle step and step-surfaces of the cam, when the circular part of the cam is
reached; when simultaneously therewith the sliding sleeve is moved upwards on the
spindle, the cutting mechanisms are moved apart the griping-jaws opened, and the
finished screw dropped from the machine.
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. In a screw cutting machine, the combination of a vertically arranged revoluble
hollow screw-spindle, provided with griping-jaws to hold the screw blank, a back-
rest lever mounted loosely on a vertically arranged and reciprocating shaft to
reciprocate in a horizontal plane, a cutting-tool lever fixed on the vertically arranged
and reciprocating shaft and arranged to reciprocate horizontally and vertically, cams
to operate the said levers, and mechanism substantially as described for raising and
lowering the cutting-tool shaft, substantially as specified.
2. In a screw cutting machine the combination of a vertically arranged revolving
hollow screw spindle, formed with upper and lower annular collars 47, 48, and
oppositely arranged mortises at its lower end, griping-jaws supported on fulcrums in
the mortises with their lower ends to close over the end of the screw-spindle, a
supporting bearing box 8, about the spindle between the annular collars, a sliding
sleeve on the hollow spindle having a tapering lower end to engage between the
upper ends of the griping-jaws a lever to raise and lower the sliding sleeve and
means substantially as described to tilt the lever, as specified.
3. In a screw cutting machine, the combination of the revolving hollow spindle, the
griping-jaws hung thereon, and a blank stop arranged in a hole traversely across the
bore of the spindle and adapted to be engaged by one of the griping-jaws, and be
moved by the movement of the griping-jaws, substantially as described.
4. In a screw cutting machine, the combination of the revolving hollow-spindle,
the griping-jaws hung thereon, and upper and lower blank stops arranged across the
bore of the spindle substantially as described and for the purpose specified.
5. In a screw cutting machine, the combination of the revolving hollow spindle,
the griping-jaws hung thereto, an upper screw-blank stop arranged across the bore of
the spindle and consisting of an angular shaped metal rod, and a lower screw blank
stop consisting of a straight metal rod arranged across the bore of the spindle, all sub-
stantially as specified.
6. The combination with the screw blank delivering and griping mechanism, of the
tool holding back-rest levers, the reciprocable leader-bar carrying the said tool
holding lever, the pitch-cam to depress the leader-bar, and springs to lift it
vertically, whereby the lever of the cutting tool is raised and lowered, substantially
as described.
7. The combination with the screw blank delivering and griping mechanism, of the
tool holding and back-rest levers, the leader-bar projected loosely through the back-
rest lever, and having the cutting tool lever secured thereto, and formed with an
inclined upper-end, the spirally formed pitch cam to depress the leader-bar, and a
lifting means for the leader-bar consisting of a cross bar secured to the upper end
thereof and springs secured to the outer ends of the cross-bar and to the frame of the
machine, substantially as described.

page_text: 8. In a screw cutting machine, the combination with the back-rest lever and the
cutting-tool lever, of a cam to operate the back-rest lever, and a rotating cam to
operate the cutting tool lever, said latter cam having its face formed with steps
increasing successively in height and intermediate idle-steps, to throw the tool
free from engagement and into corresponding cuts on the blank, substantially as
described.
9. In a screw cutting machine, the combination with the revolving-hollow spindle,
and the griping jaws, of a sliding sleeve on the hollow spindle, a lever to reciprocate
the sliding-sleeve, and a horizontally arranged cam to operate the lever, said cam
having a horizontal surface of determined distance around its circumference, a race to
draw the end of the lever down, and steps leading from the race to lift the lever,
substantially as described and for the purpose specified.
10. In an organized mechanism for cutting screws, the combination of the
vertically arranged revolving hollow-spindle having a knock-off plate having an
aperture arranged over its delivery end, and forined with oppositely arranged
mortises at its lower portion, griping-jaws fulcrumed in the mortises of the spindle
to close with their griping-ends across the lower end and bore of the spindle, and
means for opening and closing the jaws, substantially as described.
11. In a screw-cutting machine, the combination with the vertically arranged shaft 9,
carrying the cams 10, 20, the back-rest lever, the cutting tool lever, the leader-bar 36,
having said levers pivotally arranged thereon, the shaft 43, carrying the pitch-cam 44,
and the lifting-springs on the leader-bar, substantially as described and for the purpose
specified.
12. In a screw-cutting machine, the combination with the back-rest lever and the
tool holding lever, formed with slots in their rear inner ends, of adjustable bearing
pieces arranged in the slots, whereby the cut of the machine can be regulated to
different sized blanks, substantially as described.
Dated this 3rd day of December 1980
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.