Improvements in Lock-stitch or Double-thread Sewing Machines.
Year: 1897

page_text: Date of Application, 6th July, 1897-Accepted, 14th Aug., 1897
COMPLETE SPECIFICATION.
Improvements in Lock-stitch or Double-thread Sewing Machines.
I, JAMES TRIPP, of No. 973 Amsterdam Avenue, New York City, State of New
York, United States of America, Inventor and Machinist, do hereby declare the
nature of this invention and in what manner the samevis to be performed, to be
particularly described and ascertained in and by the following statement:
My invention relates to that class of lock-stitch or double-thread sewing-machines
in which a rotary hook is employed. for taking the loop from the needle and carrying
it around the hobbin-casing or spool-holder.in such manner as to spread.or bow the
loop and cause it to encompass the under thread in forming the lock-stitch.
It is among the objects of my invention to improve the rotary hook and its
supporting head; to provide an improved form of bobbin-casing or holder aud
improved means for locking said holder against rotation; and to relatively arrange
the several parts and effect their required operation in such manner as to not on y
ensure the spreading of the loop but to provide, as well, a free and unobstructed
passage for the thread in the formation of the stitch, whereby the machine may
be run at high speed without liability of breaking even the finest thread that may
be required for. the work. Other purposes of the invention, in its several, parts,
will hereinafter appear.
The invention consists in features of construction and novel combination of
devices hereinafter described and claimed.
In the annexed drawings
Figure 1 is a front, or end elevation of part of a sewing machine embodying my
invention and showing the rotary hook taking the loop from the needle....
Figure 2 is a similar view showing the needle on its upward movement and
the rotary hook as carrying the bowed loop around the bobbin-casing or holder.
Figure 3 is a similar view showing the loop as cast off from the rotary hook and
as being acted upon by the take-up.
Figure 4 is a vertical longitudinal section through a part of the machine frame,
cloth plate, rotary hook supporting head, and hobbin-casing, with; accompanying
parts.
Figure 5 is a partly sectional plan, illustrating the holding of the bobbin in its
casing and the passages afforded for release of the needle thread loop after it has
been carried around the lower thread.
Figure 6 is an enlarged perspective view of the rotary-hook-carrying head and
connected parts..
Figure 7 is a transverse section of the same with a rear portion broken off.
Figure 8 is a horizontal section of the bobbin-casing with part of the bobbin
spindle broken away.
Figure 9 is a perspective view of the bobbin-casing or spool holder viewed from
the front.
.
Figure 10 is a perspective view of a slotted spring to be attached to the bobbin-
casing or holder to control the tension of the lower thread.
Referring, first; to Figure 1, the numeral 1 designates a portion of the machine
ID 077

page_text: head with the presser-foot bar 2, presser-foot 3, needle-bar 4 and needle 5 arranged
as usual. In the cloth-plate 6 there may be arranged a slide 7, Figures 1, 2, 3
and 4 to give convenient access to the parts supplying the lower thread and the
loop-controlling portions of the double-thread sewing mechanism. The numeral 8
in Figure 4 designates a portion of the table or main bed of the machine, and 9
a pendant forming one of the bearings of the rotary hook-shaft 10, which is driven
from the main shaft, not shown, by means of any suitable connections.
On the forward end of the rotary hook-shaft 10 is carried a hook-supporting
head 11 which is preferably constructed integral with two eccentrics, 12 and 13,
Figures 4, 5 and 6, as well as with a ring 14 on which the hook 15 is immediately
formed. The purpose of the eccentrics 12 and 13 will hereinafter appear. Through
the head 11 and connected eccentrics is formed an opening or bore 16, Figures 6
and 7, to receive and tightly engage the rotary hook shaft.
As shown in Figures 6 and 7, the front of the ring 14 is provided in its inner
periphery wth a counter-sunk or reamed out portion 17 on which the hook 15 is
formed. The reamed out ring portion or channel 17 is extended somewhat more
than half the ring circumference, and for the remainder of its periphery the width
of the ring 14 is reduced from front to rear to affect a free passage for the taking up
of the needle thread in advance of the movement of the hook 15, when said
thread is cast off from the hook, as shown in Figure 3. The channel 17 is
terminated at one end by the hook 15, as shown in Figure 6. At the other end of
the channel 17 and at its rear side is a shoulder 18, formed on the front of the
reduced portion of the ring. The ring 14 is reduced in width from the shoulder 18,
to another shoulder 19, Figure 6, and from this point it is still further reduced in
width to a crotch 20 at the junction of the hook 15 with the main body of the
ring. The channel 17 terminates on the hook 15 a portion of which is continuous
with the main body of the ring 14 or rear wall of said channel, as shown in
Figures 4 and 7, but the said rear wall is dressed off or disappears before the point
of the hook is reached.
On the outside of the hook-carrying ring 14, and attached thereto, is a cap or
sheath 21, Figures 4, 5, 6 and 7 which is preferably formed separate from the
said ring and secured thereon by screws 22 or otherwise. The front portion of the
periphery of this cap or sheath 21 has a contour that corresponds with the front
outer edge of the ring 14, except that a portion of the front edge of said sheath is
dressed off to expose the hook 15 and part of its supporting ring, as shown in
Figure 6. On the front of the forward extended portion of the sheath or cap 21
is an inwardly turned lip or flange 23 which, as shown in Figures 6 and 7, nearly
corresponds with the channel 17, in length, and constitutes its front wall.
The channel 17 and flange or lip 23 serve to hold in the ring 14 a bobbin-
casing 24, Figures 4, 8 and 9, in which the spool or bobbin 25 is removably
supported.
There is on the periphery of the bobbin-casing 24 a circumferential flange or
collar 26 to engage in the channel 17 and hold the bobbin-casing from endwise
movement in the hook-carrying ring. The bobbin-casing has a convexed back 27,
Figures 4 and 8; and from the inner or front face of this back there projects a
spindle 28, Figures 8 and 9, on which the spool or bobbin 25 is to be loosely
mounted. The front of the bobbin-casing 24, comprises two segmental ribs 29
and 30, one above and one below the circular opening through which the bobbin 25
is inserted and removed. For permitting suitable descent of the needle 5 to its
lower limit of movement, there is provided in the bobbin-casing 24 a transversely
arranged slot 31 in rear of and parallel with the upper rib 29 which preferably,
constitutes the front wall of said slot. There is formed through the lower portion
of the bobbin-casing 24, in rear of its lower rib 30, a similar slot 32 for nassage of
the lower thread a, supplied by the spool or bobbin. In the lower rib 30 is a
threading slot 33, extended diagonally from front to rear of said rib, for passage
of the lower thread a into the slot 32, when threading or attaching said lower
thread to the bobbin-casing. On the front of the bobbin-casing 24, immediately below

page_text: and partly within the slot 32, is attached a spring 34 provided with a diagonally
arranged slot 35, Figure 10, extending from the lower edge of said spring and
terminating in an eye or guide opening 36 for the lower thread. The spring 34 is,
preferably, somewhat curved as shown in Figure 10; its free portion is set slightly
outward from the flanged body of the bobbin-casing, as shown in Figure 8, to
permit passage of the lower thread behind the spring, and the free end of the
spring is turned slightly forward to facilitate threading. It is preferable to attach
the spring 34 by means of two screws 37 and 38, and whenever required, the
screw 38 may be slightly loosened or tightened to regulate the tension.
When the spool or bobbin 25 is in place, the loose end portion of the thread
thereon is passed through the threading slot 33 into the slot 32 and is then drawn
along the front of the spring 34 to the forward turned end thereof and thence
behind said spring and forward and upward through the slot 35 into the guide
ye 36; and thence outward beneath the lower rib 30 of the bobbin-casing.
It has been noted that the back 27 of the bobbin-casing 24 is convexed, and,
by reference to Figures 1, 2, 3, 4, 5, 8 and 9, it will be seen that the anterior faces
of the ribs 29 and 30 are somewhat beveled, rounded or tapered, especially at
their ends. Also, the front face of the upper rib 29 is bevelled off in an upward
ection and the front face of the lower rib 30 is bevelled off in a down val direc-
tion, as more clearly indicated in Figures 4 and 9. This construction of the bobbin-
casing back 27 and front ribs 29 and 30 greatly aids in the required spreading or
bowing of the loop in the needle thread b, as said loop is carried around by the
rotary hook 15; and presents no obstruction to the free passage of the loop in forming
a lock stitch.
In the top of the flange 26 on the bobbin-casing 24 is a substantially rectangular
notch 39, Figure 9, to receive the loop of the needle thread on its engagement with
the rotary hook 15 as shown in Figures 1 and 4. This notch 39 also affords a free
passage, as shown in Figure 2, for one side of the needle thread loop in the bowing
or spreading of the loop around the bobbin-casing 24; and, as shown in Figure 3,
it acts with the lip or flange 23 to prevent twisting or kinking of the thread as it is
drawn off by the take-up in the closing of the loop around and onto the lower
thread.
It is necessary to hold the bobbin-casing 24 stationary independent of the rotary
movements of the hook 15 and hobbin 25, and by means that will not obstruct
free passage of the needle thread loop around the bobbin-casing or holder. For
this purpose there may be provided a vibratory locking device arranged to lock
the bobbin-casing 24 alternately at its opposite sides. To this end I have shown
a stud or screw-bolt 40, Figure 4, projecting forward from the lower portion of the
pendant 9 or other support. On the stud 40 is a loose sleeve 41 provided at its
rear end with an upward projecting fork 42 engaging the eccentric 13 on the rotary
hook shaft. The forward end of the sleeve 41 is preferably formed with a laterally
extended are shaped plate 43, indicated by dotted lines in Figures 1, 2 and 3,
to which, by means of screws 44, is secured a two-armed balance lever 45, pre-
ferably segmental in form and arranged with its arms curved upward, as shown.
On the ends of the lever 45 are carried lugs or pallets 46 to engage alternately with
locking recesses 47 between the ends of the ribs 29 and 30 on the front of the
bobbin-casing. The pallets 46 and their supporting and actuating mechanism con-
stitute an effective and positively actuated vibratory locking device for engaging
alternately the recesses 47 of the bobbin-casing 24 in such a manner as to hold said
casing from rotation without obstructing passage of the bowed loop around it.
By reference to Figure 1, it will be seen that both pallets or locking lugs 46 are
nartly engaged with the bobbin-casing for a short season while the loop, is not yet
fully spread. But, as the loop is carried around by the hook 15 the pallet that is
frst in the path of the outermost portion of the loop thread will move outward and
permit the loop to pass, as shown in Figure 2, the bobbin-casing being meanwhile
hel. from rotation by the full locking engagement of the opposite pallet. When,
by action of the take-up, the loop is drawn off from the hook 15, as shown in

page_text: Figure 3, the pallet on this side will have moved outward to permit free passage
of the loop, while the bobbin-casing 24 will now be held by the locking engage-
ment of the pallet on the other side. Thus by the vibratory movements and inter-
mittently locking action of the pallets 46, alternately engaging and disengaging the
bobbin-casing 24, the said casing will be held at all times stationary, by one
pallet or the other or by both together, and will not partake of the rotary movement
of the surrounding hook support or the inclosed bobbin, as might otherwise occur
from frictional contact. At the same time a positively free passage is provided for
the bowed or spread apart loop thread.
The spreading or bowing of the loop and its free passage around the bobbin-case
or holder 24 will be assisted by the convexity of the back 27 and the ribs 29 and 30;
and, by reference to Figure 8, it will be seen that the convexity of the back 27 is
extended on one side, at 48, nearly to the periphery of the flange 26 so that there
is, at this point, no shoulder on which the thread might be caught. Before the
loop is in position to be drawn off from the hook 15, by action of the take-up,
the hook support or ring 14 will have revolved a sufficient distance, as shown in
Figure 3, to afford free passage for disengagement of the loop, in the space between
the shoulder 18 and hook crotch 20, and before this the needle thread loop will have
encompassed the under thread which may have been previously carried up
through the needle orifice in the cloth plate. With the full action of the take-up
and further rotation of the hook-supporting ring the loop of the needle thread. will
be wholly, released and become combined with the under thread in forming the
stitch,
By reference to Figures 1 and 4, it will be seen that the needle 5 is arranged
to descend immediately in front of the hook 15, notch 39 and that portion of the
flange or collar 26 which is below said notch. This portion of the collar or flange,
below the notch 39, will serve as a guard or guide 50 for the needle point, so that
should the needle be slightly deflected rearward it will be prevented from getting
in the path of the hook 15 that is close to the rear side of the needle when the
loop is taken therefrom.
There may be provided on the lower rib 30 of the bobbin-casing 24, a bevelled
surface 51, adjacent to the spool or bobbin 25, to facilitate insertion of the thumb-
nail to remove an empty spool or bobbin.
:
When a filled spool or bobbin has been mounted on the spindle 28 it may be
held from longitudinal displacement by means of a laterally swinging arm 52
arranged on a pivot 53, Figure 5, supported beneath the cloth plate. The pivotal
end of the arm 52 is squared, as shown in Fig. 5, to have a firm support, in
either of its positions, against a spring bearing 54, Figure 5, provided on a por-
tion 55 of the machine frame. When swung outward or forward the arm 52 will
offer no obstruction to insertion or removal of the bobbin 25, but when said.arm is
turned laterally across the front of the bobbin-casing the bobbin 25 therein will be
prevented from flying out of its holder. The arm 52 does not, however, coin in
contact with the bobbin nor so close to it as to obstruct free passage of the bowed
loop around and off from the bobbin-casing. In order that the arm 52 may not be
swung too far inward there is provided in the frame part 55 an adjustable forward
projecting stud or bolt 56, Figure 5, that can be moved outward to afford a suitable
stop for the arm 52 when swung inward.
The machine may be provided with the usual feed 57 reciprocated by the
ordinary and well known lever mechanism and receiving its vertical movements
through a fork 58 actuated by the eccentric 12 on the rotary hook shaft.
C
The operation of the several parts concerned in sewing the fabric c will be readily
understood from the foregoing description and need not be further explained.
Owing to the smooth running of the hook carrying head or support, the prompt,
casy and efficient action of the alternately engaging locking devices for the bobbin-
casing and the absence of frictional action between the hook-support, bobbin-
casing and bobbin, the operation of the several parts is practically noiseless and

page_text: the machine may be run at very high speed without impairing the accuracy and
neatness of the work:
P
i
Having now particularly described and ascertained the nature of my said
invention. and in what manner the same is to be performed, I declare that what I
claim is:-
1. In a sewing-machine, the combination, with a needle, and a rotary hook
carrying ring, of a circumferentially flanged bobbin-casing having a convexed
back, an open front for insertion and removal of a bobbin, anteriorly convexed
segmental ribs above and below the opening in said front, an upper transverse slot
and a lower transverse slot in rear of said ribs, a tension regulating spring arranged
in said lower slot and provided with a treading slot terminating in an eye, the said
lower rib being provided with a slot for passage of the under thread to said spring
and ineans for holding said bobbin-casing against rotation and longitudinal dis-
placement, within the rotary hook carrying ring, substantially as described.
2. In a sewing-machine, the combination, with a needle, and a rotary hook
shaft; of an eccentric and a hook-carrying ring or head formed integrally and
mounted in one body on the forward end of said hook shaft, a bobbin-casing
held from longitudinal displacement without the hook carrying ring, a bobbin, and
a positively actuated locking device adapted to engage the bobbin-casing at two
points alternately for locking said casing at all times against rotation and to provide
free passage for the loop at each locking point as required, said eccentric being
arranged for actuating the said locking device, substantially as described.
3. In a sewing-machine, the combination, with a needle, a rotary hook-carrying
ring having a portion of its periphery provided with a passage for the loop, and
a bobbin-casing held from longitudinal displacement within said ring and pro-
vided with locking recesses at two points in the path of the needle thread loop that
is to be bowed or spread around said casing to encompass the under thread, of a
positively actuated vibratory locking device provided with lugs or pallets adapted
an arranged to engage both locking recesses of the bobbin-casing for a time
while the loop is not yet fully spread and to alternately disengage from and become
fully engaged with the respective recesses of the bobbin-casing, whereby the said
casing is at all times locked against rotation and a free passage afforded for the
loop at each locking point as required, substantially as described.
4. In a sewing machine, the combination, with a needle, a rotary hook carrying
ring provided with a passage for the needle thread loop and mounted on a shaft
provided with an eccentric, and a bobbin-casing held from longitudinal displace-
ment in the said hook-carrying ring, around which casing the loop of the needle
thread is to be bowed or spread, of a vibratory two armed locking device provided
with lugs or pallets adapted and arranged to simultaneously have a partial engage-
ment with the bobbin-casing for a time while the loop is not yet fully spread
and to alternately become disengaged from and fully engage with the bobbin-
casing as the loop is carried fully around the same, whereby the said casing is at
all times locked against rotation and a free passage afforded for the loop at each
locking point as required, and means for vibrating said two-armed locking device
from the eccentric on the hook-shaft, substantially as described.
5. In a sewing-machine, the combination, with a needle, and a rotary hook-
carrying ring adapted to afford passage for the loop of the needle thread around and
in advance of the hook, of a bobbin-casing held against longitudinal movement
in said hook-carrying ring and provided with a convexed back and an open front
having anteriorly convexed ribs one above and one below the bobbin receiving
opening and with recesses between the end of said ribs, and upper and lower trans-
verse slots in rear of the ribs, and a positively actuated vibratory locking device
provided with lugs or pallets to engage in both of said recesses for a time and to
alternately disengage from and fully engage with the respective recesses, whereby
the hobbin-casing is at all times locked against rotation and a free passage afforded
for the needle thread loop at each locking point, substantially as described.

page_text: 6. In a sewing-machine, the combination, with a needle, and a rotary hook-
carrying ring having a portion of periphery reduced in width to afford passage for
the loop of the needle thread, of a bobbin-casing closed at the back and open in front
for insertion and removal of a bobbin, the said bobbin-casing being provided with
convexed surfaces for free passage of the bowed or spread loop around it and
having transverse slots above and below the front of the bobbin receiving opening
and locking recesses at the sides, a tensión regulating spring arranged in one of the
slots of the bobbin-casing and provided with a threading slot and eye in said
spring, and vibratory locking device to alternately engage with and disengage from
the said recesses in the sides of the bobbin-casing for holding it against rotary
displacement within the hook-carrying ring and to permit free passage of the loop
at each locking point, substantially as described.
7. In a sewing-machine, the combination, with a needle, a rotary hook-carrying
ring, and a bobbin-casing having an open front and provided with locking recesses
on opposite sides, of positively actuated vibratory locking devices adapted to simul-
taneously engage for a time in both said recesses of the bobbin-casing and to
alternately disengage from and fully engage with said recesses as the loop is carried
around the casing, to lock the latter and permit free passage for the loop at both
locking points in succession, and an arm to retain the bobbin in its casing, sub-
stantially as described.
Cl
T
1007
D. YOUNG & Co.,
1 & 12 Southampton Buildings, London, W.C.,
Agents for the Applicants.