Improvements in and relating to Machines for Forming Screw- threads upon Articles of Sheet Metal.
Year: 1889

page_text: Date of Application, 17th Sept., 1889-Accepted, 9th Nov., 1889
COMPLETE SPECIFICATION.
Improvements in and relating to Machines for Forming Screw-
threads upon Articles of Sheet Metal.
I, WILLIAM FREDERIC LEWIS, residing at Watertown, in the County of Litchfield
and State of Connecticut, one of the United States of America, Machinist, 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 certain new and useful improvements in machines for
forming screw-threads upon articles of sheet-metal, such for instance as parts of oil-
cans, gas burners, and the like, and the objects of my invention are:
First, to form the screw-threads in the metal by pressure instead of by knurling or
tapping as heretofore practised, and that, whether the threads are to be on the interior
or exterior of the article, or both.
Second, to provide means for retaining the article to be threaded securely in position
for the performance of the threading operation.
Third, to provide means for the presentation of the article to be operated upon,
to the successive tools adapted to act upon it.
and
Fourth, to provide means for the extraction and ejection of the finished work;
Fifth, to provide a machine embodying the operative parts hereinbefore set forth,
which shall be simple in construction and positive in operation.
With these ends in view my invention consists in the means for impressing the
threads upon the work and for stripping and ejecting the latter, and in the construc-
tion and combination of elements hereinafter set forth and then recited in the claims
liereto annexed.
In order that those skilled in the art to which my invention appertains may fully
understand my invention, and the construction and method of operation thereof, I
will describe the same in detail, reference being had to the accompanying drawings,
which form a part of this specification, and in which
Figure 1, is a front elevation of a press provided with my improvement.
Figure 2, a side elevation thereof.
Figure 3, a detail plan view of the feeding-plate and its operating pawl.
Figure 4, a detail vertical section on the line, x, c, of Figure 2.
Figure 5, a detail section showing a pair of dies adapted for external threading.
Figure 6, a similar view of dies for internal threading.
Figure 7, a detail elevation of a blank before threading.
Figure 9, a similar view of a threaded cup, or shell.
Figure 8, a similar view showing the shell after having been operated upon by a.
single pair only of the dies.
A, represents the bed of an ordinary press, such as is used for stamping sheet-meta!..
B, are the vertical standards mounted upon said bed; and, C, is the reciprocatory
gate which is mounted and moves in ways in the standards. D, is the main
shaft; and, E, is the pitman operated by said shaft and actuating the gate.
Secured by a central pivot upon the bed of the press so that its periphery is
beneath the gate, is a circular turn-table or plate, 1, having upon its edge a series of'
teeth, 2, with which a reciprocating pawl, 3, is adapted to engage and so turn the plate
intermittently, see Figure 3.
4, are hubs, to any suitable number, secured in a circle upon the surface of the
plate, each of these limbs has its upper portion conformed to the shape of the threaded
article to be produced, and forms a lower die. For instance, if a cup-shaped article,

page_text: threaded exteriorly, is to be produced, each of said hubs will, as seen at Figuro 5, be
formed in the shape of the inside of the threaded product, having shoulders, 5, and a
male screw threaded portion, 6.
If, upon the other hand, an interiorly threaded article, as a collar or the like, is to
be made, each of said.hubs will be cup-shaped and provided with an interior female
thread, 7, as seen at Figure 6.
The pawl whereby the circular plate is operated step by step about its center,
receives its motion from a slide, 8, which latter is actuated through a link, 9, by a
lever, 10. Said lever is operated about its pivotal point by a crank disk, 11, on the
end of the main shaft. By this means the plate is moved one step at each revolution
of the main shaft so that the hubs are presented seriatim for the operation of the tools
upon the gate.
The first of these tools consists of a spring cushioned presser block, 12,
carried upon the gate and adapted to seat the unthreaded blank firmly upon the
hub.
Next are secured to the plate two or more threading dies, I have shown three, but
two may be employed, or if desired a greater number than three.
If these dies are adapted for exterior threading, they consist, as seen at Figure 5,
of the threaded rod, 13, for attachment to the gate, a collar, 14, on said rod a hollow
sleeve, 15, having its upper end secured to the lower end of the collar, and internally
tapered at its lower extremity, and the operating die, 16, arranged around the end of
the rod and externally conformed to the interior contour of the sleeve. This die has
a tapered surface corresponding to the tapered internal taper of the sleeve, and is
slotted from its lower end upward for a considerable portion of its length, as seen
at, 17. These slots are for the purpose of imparting spring quality to the die, and
there may be two, three, four, or more of said slots according to the size and thickness
of material of which said die is made. Said die is internally screw-threaded at its
lower extremity as seen at, 18.
Near its upper end said die has two or more guide slots, 19, which are engaged
by pins, 20, projecting inward from the sleeve. These pins serve to hold the die in
the sleeve, and to prevent any axial movement thereof, while at the same time. they
permit a limited movement to said die relative to the sleeve and in the direction of its
length.
Around the rod and bearing respectively, upon the under surface of the collar, 14,
and the top surface of the die is a coiled spring, 21, whose function is to keep the
said die ejected from the sleeve to the limit allowed by the pins, 20, except when
said die is forced upward relative to said sleeve, as will hereinafter be fully set
forth.
If upon the other hand, said dies are to be used for interior threading, they consist,
as seen at Figure 6, of a threaded rod, 22, for attachment to the gate, said rod being
tapered at its lower end, an abutment collar, 23, secured upon said rod, a shouldered
internally tapered die arranged around said rod and externally screw-threaded as
at, 24, a slot and pin attachment between the rod and the die, similar in action to
that heretofore described, and a spiral spring, 25, interposed between the shoulder on
the die and the abutment collar.
The two dies herein before described have each in connection with the shape of the
die upon the hub which is designed to be used therewith, substantially the same mode
of operation.
In the die for exterior threading, the normal position thereof is as shown at
Figure 5, with its interior diameter large enough to admit the lower die with the
blank to be threaded upon it. When said upper die descends over the blank, the
bottom plane face of said die, 26, strikes the shoulder, on the lower dic, and
the slight continued downward movement of the rod and gate and sleeve serves to
drive the die upward within the tapered sleeve and thereby to compress the sections
of said die which are formed by the vertical slots therein, inward upon the lower die
and the sheet metal blank which is arranged thereon. Thereby the impress of the

page_text: threads upon the two dies is imparted to the sheet metal. The upward movement
of the sleeve with the gate allows the die to slide out of the sleeve and to expand so
that it may lift freely with the gate.
In the die for interior threading, the bottom of the hollow lower die arrests the
downward movement of the upper die, and the continued downward movement of
the tapered rod in the tapered and slotted die, expands the screw-threaded lower end
of the latter so as to operate upon the blank to be worked, as in the other die here-
tofore described, but outward instead of inward.
There remains to be described the device whereby the finished work is removed
from the dies upon the feeding plate, and the means whereby it is operated.
27, is a vertical shaft having a bearing in the gate as at, 28. Upon its lower
end is mounted a vertically slotted gripper, 29, which is of such internal diameter
that it may be forced downward over and caused by its spring quality to grasp a
piece of the finished work upon one of the lower dios. Upon the shaft, 27, is an
abutment collar, 30, a spring, 31, is disposed around said shaft between said collar
and the gate, and the upper end of said shaft extends within a short hollow
shaft, 32, to which it is connected by a spline, 33, in such manner that the shaft, 27,
may receive. rotary motion from said hollow shaft, but may at the same time
have a vertical motion independent thereof, the reason for which will be presently
apparent.
The hollow shaft just referred to is journaled in a bracket, 34, on the face of one
of the standards, B, and carries upon its upper end a beveled gear, 35. 36, is a
horizontally disposed shaft journaled in an outward extension from the standard, upon
its inner end it carries a gear, 37, meshing with the gear, 35.
Journaled loosely upon the end of the shaft, 36, is a pulley, 38, interiorly coned
at its inner end, see Figure 4, and continuously driven independently of the main
shaft by a belt. 39, is a slide rod. arranged in the frame immediately above the
shaft, 36, and parallel thereto, and said rod is normally retained at its inward limit
of movement by a spring, 40.
Near the outer end of this rod is a projecting roller stud, 41, and at the extremity
said rod carries a downwardly projecting fork, 42, which has roller studs, 43,
engaging a grooved collar, 44. Said collar carries a coned friction disk, 44", and is
arranged around, and connected by a spline, 45, to the shaft, 36. Upon the crank
disk whereby the step by step rotation of the circular feed plate is accomplished
through the lever and pawi, is arranged a sectoral wedge, 46, whose plane of rotation
is just inside the plane of the center of the roller stud, 41, on the slide rod, 39. The
action of this welge is to force the slide rod outward against the action of its spring
and thereby through the fork and collar to engage the coned friction disk with the
constantly rotating pulley, 38.
By this means rotation is imparted to the transverse shaft, and thence through the
beveled gears to the vertical shaft, 27, for such a proportion of each revolution of the
main shaft as the length of the sectoral wedge bears to the entire circumference of
the disk on which said wedge is mounted. By reference to Figure 2, this is seen to
be about one quarter, so that the vertical shaft revolves during one quarter of the
time occupied by the main shaft in making one turn, and is idle during the other
three quarters, by the friction disk being drawn out of engagement with the cone
pulley hy the spring, 40. The wedge is so timed as to throw the disk into engagement
with the coned pulley at the time the gate commences its upward movement, and this
engagement and the rotation of the vertical shaft continues during substantially one
half of the upward stroke of said gate.
It will be observed that the length of stroke of the gripper and of the vertical shaft
is not as great as the stroke of the gate and the tools attached directly thereto and
carried thereby.
When the gate descends it slides on the vertical shaft until it abuts against the
top surface of the gripper designated by, 47. For the balance of its stroke it carries
said gripper with it, the shaft sliding downward within the hollow shaft to which
it is splined. When so carried downward the gripper is forced over and grasps the

page_text: completed article on the die beneath it, and as the gate ascends the gripper is caused
to rotate and thereby the screw-threaded sheet metal article is removed out of engage-
ment with the die. When the gate ascends it raises the shaft on its spline connection,
the spiral spring forming a cushion, and the article of work is disengaged from the
gripper by means of a spring arm, 48, which is displaced by the downward stroke of
the gripper, but which slides across its beveled lower surface on the ascending stroke
and throws out the work.
Having hereinbefore set forth the method of operation of the several parts of my
invention, I will now describe the working of the machine as a whole.
An operator, as the feeding plate revolves, places upon the 'dies upon said plate
seriatim as they come before hier, the blanks to be operated upon.
A blank after having been so placed over the die is first pressed firmly downward
by the presser block carried on the gate. Then as the plate turns the blank is
presented at the next downward stroke of the gate, to the first of the slotted
threading dies which presses into the metal the shape of the screw-threads which it
carries. As the die is slotted to give it resiliency, the blank after the first threading
operation will appear as shown at Figure 8, that is, with blank spaces on its periphery,
corresponding to the slotted portions of the die. Having been turned a third step,
the blank is operated upon by a duplicate of the first threading die, but which is
arranged with its slots out of coincidence with those of the first die so that the
blank spaces left by said first die will receive their appropriate thread.
At the
next step a third die like the two preceding acts upon the blank. This is merely as a
finishing operation and is not essential to the production of good work.
At the next step, the gripper is forced over the now finished blank and the
latter is stripped from the lower die by the combined upward and rotary motion of
the gripper which unscrews the work from the threads, and immediately thereafter by
means of the spring arm, 48, the work is released from the gripper and thrown into
any convenient receptacle.
In this my invention, I do not wish to be confined to the exact details of construction
which I have herein shown and described, since many minor changes, both in the
construction of the operative parts and in their application to the press, which changes
are entirely within the province of mechanical skill, may be made without departing
from the spirit of my invention as is set forth in the clauses of claim now to
follow.
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 machine of the character described, the combination with a lower die,
conformed to the shape of the finished article, of an expansible upper die having an
interrupted operative surface, means for reciprocating said upper die into and out of
engagement with the work, and additional means for imparting to said upper die a
radial expansion and contraction, substantially as set forth.
2. In a machine of the character described, the combination with a plurality of
lower dies each conformed to the shape of the finished article to be produced, and
means as described for moving said dies seriatim into the field of operation of the
upper dies, of a plurality of expansible and contractible upper dies having operative
faces conformed to the shape of the finished article, means as described for recipro-
cating the said upper dies, and further means for inducing in said dies a radial expan-
sive and contractile movement, while in engagement with the lower dies, substantially
as specified.
3. In a machine of the character described, the combination with a plurality of
lower dies, each conformed to the shape of the finished article to be produced and
means as a rotating plate, whereby said lower dies are presented serialim to the upper
dies, of a plurality of radially expansible and contractible upper dios, the gate for
vertically reciprocating said dies, wedges for imparting the radial expansion and
contraction thereunto, and a gripper properly timed relative to said, upper dies, and

page_text: adapted to remove the titsted, work from the lower ales, substantiany as any for the
purpose set forth.
4. In a machine of the character described, the combination with the lower dies,
of the plurality of radially expansible and contractible upper dies and means for
operating their jaws toward and from the work a cushioned pressure block operating
one or more steps in advance of the said upper dies, and a gripper operating subsequent
to the said upper dies and adapted to remove the finished work from the lower dies,
substantially as set forth.
5. The combination in a machine of the character described, with the lower dies
and means whereby they are successively presented to the tools, of the plurality of
upper threading dies, the same being radially expansible and contractible and the
gate, whereon they are mounted, the pressure block upon the gate whereby the blanks
are seated in advance of their presentation to the threading dies, and the vertically
reciprocated and intermittently rotated gripper operating subsequent to the threading
dies, and whereby the work is removed from off the lower dies, substantially as set
forth.
6. In a machine of the character described, the combination with the intermittently
operated feeding plate, and the lower dies arranged in a circle upon said plate, each
of said dies conformed to the shape of the article to be produced, of the reciprocating
gate, the plurality of expansible and contractible threading dies mounted upon and
reciprocating with said gate, the gripper vertically operated by said gate, and means
independent of said gate whereby an intermittent rotation is imparted to said
gripper in addition to its vertical movement, substantially as and for the purpose
specified.
A
7. The combination in a machine of the character described, with the lower dies
and the rotary plate whereon they are mounted, of the gate and a plurality of
threading dies arranged thereon, each of said dies being slotted vertically as to its
operative surface, whereby a radial expansibility is imparted thereto, said dies having
an inclined surface, and an inclined surface secured upon the gate adjacent to said
inclined surface on the dies, and a spring for retaining the parts in their normal relative
positions except when operated by the descent of the gate, substantially as and for the
purpose set forth.
8. In a machine of the character described the combination with the lower dies and
the means for operating them, of the dies upon the reciprocating gate, each die, having
a series of slots theroin whereby an expansive and contractile action is imparted
thereto, a wedge for effecting the radial action of the die jaws, and a gripper
for the removal of the work subsequent to the action of the dies, substantially as
specified.
9. In a machine of the character described, the combination with the reciprocating
gate, the tools secured thereon and the lower dies mounted beneath said grate, of
the gripper and a vertical shaft upon which it is secured, a transverse shaft
geared to said vertical shaft, a constantly rotating band wheel, and means, as a
clutch for connecting said transverse shaft with said band wheel, substantially as set
forth.
10. In a machine of the character described, the combination with the reciprocating
gate, the dies carried thereby and the lower dies arranged beneath the gate, of the
vertical shaft and the gripper arranged thereon, a short hollow shaft splined to said
vertical shaft, a transverse shaft geared to said hollow shaft, a constantly rotating
band wheel, a clutch splined to said transverse shaft, and a wedge operated
independent of the band wheel and in proper time with the gate, whereby inter-
mittent engagement is effected between said band wheel and the transverse shaft, as
set forth.
1.1. The combination in a machine of the character described with the reciprocating.
gate and dies, and the lower dies arranged beneath the gate, of the vertically and
axially movable gripper shaft, and the gripper carried thereby, an independently
operated band wheel, a clutch whereby the motion of the said band wheel may be
imparted to the gripper shaft and means operated in time with the gate and independent

page_text: of the gripper shaft whereby the latter is intermittently engaged with the band wheel
so as to be operated thereby, substantially as specified.
12. The combination in a machine of the character described with the main shaft,
of the gate connected thereto and driven thereby, the dies upon the gate and means
whereby radial movement is imparted to said dies, and the lower dies arranged
beneath said gate, of the circular ratchet plate whereon said lower dies are mounted,
a reciprocating pawl adapted to engage and turn said plate step by step, and a
pivoted lever driven by the main shaft and adapted to actuate said pawl, substantially
as specified.
13. In a machine of the character described, the combination with the gripper and
its shaft and means, as the gate, for imparting thereto a properly timed vertical
movement, of a hollow shaft splined to the gripper shaft, a transverse shaft geared to
the hollow shaft, an independently rotated band wheel, a clutch splined to said trans-
verse shaft and carrying a friction disk, and a sectoral wedge operated from the main
shaft and whereby the clutch is moved into engagement with the band wheel, sub-
stantially as set forth.
14. The combination in a machine of the character described, with the rotating
feed plate and the lower dies mounted thereon, and means, as a ratchet and pawl
mechanism for imparting properly timed step by step rotation to the plate, of the
reciprocating press gate, a plurality of vertically slotted dies arranged upon said gate,
and wedges arranged in said dies, whereby a radial movement may be imparted to
their operative faces, in connection with the downward stroke of the gate, substantially
as set forth.
15. The combination in a machine of the character described, with the centrally
pivoted feeding plate and its dies and the ratchet and pawl mechanisin whereby a
step by step movement is imparted thereto, of the reciprocating press gate, a plurality
of vertically slotted dies arranged and carried thereon, and means as wedges for
imparting to the sections of said dies a radial movement, a spring cushioned
presser block also carried by said gate, a gripper adapted to be operated by said
gate and means disconnected from said gate whereby in addition to its vertical
movement, an intermittent axial rotation is imparted thereto, substantially as set
forth.
16. In a machine of the character described, the combination with a stationary
lower die having thereon the figure to be impressed upon the work, of the upper die,
whose operative surface is interrupted and conformed to the lower die, a gate whereby
said upper die is carried, and wedges moving with the upper die and engaging the
sections theroof, whereby a radial movement is imparted to said sections, substantially
as set forth.
17. In a machine of the character described, the combination with a lower die,
the same being conformed to the shape of the finished article to be produced, of
the upper die having its operative sections conformed to the lower die and radially
spring actuated in one direction, and a wedge element imoving with said die,
whereby the sections are operated radially against their spring action, substantially as
specified.
18. In a machine for forming screw threads upon articles of sheet metal, the
combination with two or more lower dies each conformed to the shape of the
finished article, of a plurality of expansible upper dies and means for operating
the same, each having an interrupted operative surface, the interruptions of said
surfaces being out of coincidence, whereby the second die imparts its conforma-
tion to the blank surfaces left on the work by the first die, substantially as set
forth.
19. In a machine of the character described, the combination with a plurality of
lower dies each having a surface conformed to the shape of the finished articlo and
means for moving said dies step by step for presentation to the upper dies, of a recipro-
cating gate and a series of expansible and contractible dies mounted thereon, said dies
being arranged with the interruptions between their operative surfaces out of coinci-
dence, substantially as and for the purpose specified.

page_text: 20. In a machine of the character described, the combination with a plurality of
lower dies each having an operative surface conformed to the shape of the article to
be produced, of a gate and means for reciprocating it relative to the said lower dies,
an upper die having an interrupted operative surface and means for imparting to said
die an expansive and contractile movement, and a second upper die also having radial
movement, both said upper dies being carried on the gate and the interruptions between
the operative surfaces of the last named upper die being out of coincidence with
the interruptions between the surfaces of the first mentioned upper die whereby
work having a continuous finished surface may be produced, substantially as specified.
Dated thie 28th day of Auous 1889
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.