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Патент USA US3082728

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March 26, 1963
Filed NOV. 28, 1960
4 Sheets-Sheet 1
female» I!- .S‘umnnaz .Ze
March 26, 1963
Filed Nov. 28, 1960
4 Sheets-Sheet 2 '
I“ a
Eamon: b’. Scmmuaeh
March 26, 1963
Filed NOV. 28, 1960
4 Sheets-Sheet 3
____ _____
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SEW" l“ L
Emmna Ii Sea/mum Ji
United States Patent 0 " 1C6
_ Patented Mar. 26, 1963
In the drawings and the numerals of reference thereon,
a bag sewing machine 10 is driven by an electric motor
Edward H. Scharmer, Jr., Minneapolis, Minn., assignor
11 through a Vebelt 12 drivably mounted on a motor
sheave 13
engage or
and a driven sheave 14. A control lever 15 is
‘by a link 16 to a clutch assembly 17 that will
disengage the drive sheave to drive the sewing
The sewing machine 10 and attached motor 11
are suspended from a support member 18 with a cable
to_ Minneapolis Sewing Machine, Inc., Minneapolis,
Minn, a corporation of Minnesota
Filed Nov. 28, 1960, Ser. No. 72,244
4 Claims. (Cl. 112—11)
20 and a hook 21 that engages a bracket 19.
The present invention relates to thread cutting devices
The sew
for sewing machines and more particularly to an auto 10 ing machine is suspended at a convenient height so the
top section 22 of a bag 23 that is being carried on a
matic device for cutting the chain stitch used to close
conveyor 24 will pass underneath a presser foot 25 of
bags so there is a predetermined amount of thread ex
tending outwardly on both ends of the bag.
Present devices for automatically cutting the chain
the sewing machine 10 and into the stitching needle 26
of the leading and trailing edges of the bag with respect
stitching, such as 28, formed by the sewing machine will
where it will be sewed closed with a chain-stitch. Two
stitch formed when sewing a bag do not operate satis— 15 balls of thread 27, 27 that are utilized in the stitching
are supported on a tray 30 connected to cable 20. A
factorily and leave uneven or excessively long lengths of
spring clip 31 serves to maintain tension on the thread.
stitching on the bag ends. These uneven lengths present
A support shoe 32 is pivotally attached to a pair of
an untidy appearance and cause interference and damage
rods 33, 33 that are slidably mounted in a support block
when the bags are stored and handled. Most of the
devices in use have no support for the stitched thread 20 34 that in turn is mounted to sewing machine 10. Each
I of rods 33, 33‘ has a collar 38 and a spring 35 mounted
on ‘the leading end of the bag and obtaining a prede
thereon and positioned to resiliently urge the shoe 32
termined length of lead stitch is extremely dif?cult.
against a work plate 36 of the sewing machine. Shoe
The present invention discloses a device that uniformly
32 is positioned ahead of the needle and presser foot
severs the chain-type stitching on both the leading and
the trailing edges of the bag responsive to the position 25 and on a plane below the needle so any of the chain
be fed onto and supported by said shoe 32. Rods 33, 33
to the needle. A support for the chain-stitching is pro
vided to insure a uniform length of stitching on the
leading edge of the bag as the stitching will not be
are positioned to allow a ?rst portion of shoe 32 to re
main in contact with work plate 36 when a second por
allowed to sag but will be supported and guided so the ‘ tion of shoe 32 moves to allow a bag to pass through,
as best seen in FIG. 5. As the bag moves past the shoe
knife will leave a predetermined length of stitching every
32 the shoe continues to follow under the stitching formed
time it operates.
in the bag. A portion of the shoe 32 will move into
The cutting device consists of a solenoid that is oper
contacting relationship with work plate 36 as soon as the
ated by a microswitch that controls the ?ow of electricity
to the solenoid. Said microswitch is in turn actuated 35 bag moves clear of the presser foot 25, and thus will
support the trailing chain-‘stitching before it sags or moves
by a cam that is rotated by a bag follower. The solenoid
out of place.
forces a knife against the thread to sever it at a prede'
A plunger 37 is slidably positioned in support block
termined distance ahead of the bag as the bag moves
34 and extends therethrough. A knife head 40 with a
into the sewing machine and also cuts the stitching an
replaceable blade ‘41 is ?xedly attached to plunger 37 and
equal distance behind the bag after it has been sewn.
is situated at substantially right angles to the chain stitch
The solenoid is energized an exact length of time to put
ing and with the blade positioned substantially parallel
the full force of the solenoid on the knife when it is
to an anvil block 42 that is mounted on a plane parallel
cutting and to immediately release the knife and thereby
with work plate 36. Plunger 37 is positioned to slide in
device severing the chain-stitching from a bag-closing
machine a predetermined distance ahead of and behind
the bag.
In the drawings,
of travel of the bag and chain-stitching. Knife blade 41
is positioned immediately adjacent shoe 32 on the end
insure satisfactory operation.
It is an object of the present invention to present a 45 a direction substantially perpendicular to the direction
FIG. 1 is a rear elevational view of a bag sewing ma
away from the presser foot so that when the knife ‘is
actuated to cut the chain-stitch an exact length of stitch
50 ing will be left between the needle and the knife. Shoe
chine with a bag in place for sewing;
FIG. 2 is a front elevational view of a bag sewing ma
chine showing a device made according to the present
invention installed thereon;
32 supports and guides the chain-stitching and the stitch
ing will be properly positioned when the knife is actu
ated so an accurate cut will always be obtained.
A portion of plunger 37 extends beyond block 34 in
FIG. 3 is a sectional view taken as on line 3-—-3 in 55 a direction away from the knife blade and has a lug 43
attached thereto. A return spring 44 is slidably ?tted
over a guide rod 45 that is fastened to lug 43 and slid
ably ?tted in block 34. Spring 44 resiliently urges the
FIG. 2;
knife and plunger away from the cutting block 42 and
FIG. 5 is a partial top plan view of a thread cutting
device made according to the present invention and show 60 the chain-stitching. A solenoid 46 is mounted on sewing
machine 10 and has a tang 47 that is positioned to en
ing a thread support shoe yieldably moving to allow a bag
gage lug 43 and force knife blade 41 against anvil block
to pass underneath;
42 when the solenoid is energized.
FIG. 6 is a partial top plan view of the device of
A microswitch 50 is actuated by a cam wheel 51 with
FIG. 5 showing a bag that has been sewn and a thread
FIG. 2;
FIG. 4 is a sectional view taken as on line 4--4 in
support shoe in position to support the trailing chain 65 a lobe 57 acting on a roller 52 that is rotatably attached
FIG. 7 is a top plan view of the device of FIG. 5 show
ing a knife in position to cut the chain-stitching trailing
from the rear of a sewed bag; and
FIG. 8 is schematic representation of the electrical cir
cuit for the present invention.
to the microswitch actuator lever 53. Cam 51 is ?xedly
attached to a shaft 54 that is rotatably mounted in sup
port block 34 on an axis substantially parallel to the
upright side of a bag that is being sewed. A cam actua
tor rod 55 is ?xedly attached to shaft 54 adjacent an
opposite side of support block 34 and extends to engage a
bag that is moving through the sewing machine. A spring
48 resiliently urges rod 55 in direction to rotate clock
wise as seen in FIGS. 5, 6 and 7. A stop 56 extends to
engage a portion of block 34 and prevent the actuator rod
from moving too far in clockwise direction.
the bag moves further, the shoe 32 again seats entirely
on wall 36 and supports the chain stitching as before.
As the bag advances after the initial severing of the
chain stitching, the actuator rod 55 moves with the lead
ing edge of the bag and rotates the cam 51 to position
A time controlled circuit illustrated in FIG. 8 is used
where the microswitch 50 is in its normal position and
to energize the solenoid 46 for a predetermined time re
the solenoid 46 is not energized. The cam remains in
gardless of the time it takes the lobe 57 to pass by
this position as the bag slides past the rod 55 during
the roller 53. The circuit receives power from a 110
the sewing operation. After the bag has been sewn it
volt, 60 cycle source and includes a relay 60, a con 10 moves clear of the rod and the actuator rod moves under
denser 61, a resistor 62 and a recti?er 63. The recti?er
the action of spring 48 until lobe 57 of the cam again
63 is normally connected across the condenser 61 to
moves the microswitch 50 to energize the solenoid and
keep it charged. When the microswitch is operated
thereby sever the trailing chain stitching as shown in
by lobe 57 of cam 51, the recti?er ‘63 is disconnected
FIG. 7. The rod 55 is thereby automatically positioned
and the relay 60 is activated. This cuts out the micro 15 to contact the next bag that is to be sewed shut and
switch completely, connects the solenoid 46 across the
the process will repeat. The shoe 32 also holds the trail
line, and connects the condenser 61 across the relay coil
ing chain stitching in position so predetermined length
to hold this relay in until and as the condenser dis
of stitching remains on the bag. The length of the
charges. The rate of discharge is determined by the char
chain stitching on the bag may vbe controlled by regulat
acteristics of the relay coil, condenser and of resistor 62; 20 ing the length and position of actuator rod 55 and the
and will be of value to hold the relay closed until the
shape and position of cam 51.
solenoid has had opportunity to force the knife blade
The cutting device presented insures even lengths of
down onto the stitching with full force.
leading and trailing stitching on all bags that are sewn
The relay 60 cannot operate again until the condenser
without any attention from an operator. The thread
61 is recharged. As long as the cam lobe 57 engages 25 support shoe prevents the occurrence of inaccurate lengths
the wheel 53, the recti?er 63 is out of the circuit so that
or misses from thread sag.
this cannot happen. Consequently, regardless of the
What is claimed is:
time interval during which the microswitch is activated,
l. The combination with a bag sewing machine hav
the time which the solenoid is energized is constant. En
ing a substantially horizontally reciprocating needle mov
ergizing the solenoid 46 for 0.012 second has ‘been found 80 ing in relation to a substantially vertical work plate to
to be most satisfactory.
form chain-type stitching used for sewing a bag, passing
between the needle and work plate, closed, of: a cutting
device including a support shoe positioned with respect to
Assuming the sewing machine is constantly running,
said needle on a plane below said needle and adjacent
a bag 23 to be closed is moved toward the sewing ma 35 said needle in the direction of travel of a bag that is
chine by conveyor 24, engages actuator rod 55, is guided
being sewed, a ?rst rod pivotally attached adjacent an end
'under presser foot 25 and the top of the 'bag is sewed.
thereof to said shoe adjacent a ?rst end of said shoe, a
When the bag is advanced to a position as shown in FIG.
second rod pivotally attached adjacent an end thereof
4, lobe 57 on cam 51 actuates microswitch 50 and the
‘to said shoe adjacent a second end of said shoe, a support
solenoid 46 is energized for a predetermined length of
block ?xedly mounted with respect to said sewing ma
time that is controlled by the time controlled circuit.
chine, both of said rods being slidably mounted on their
When the solenoid is energized, the tang 47 imparts an
respective longitudinal axes in said support block and posi
impulse of force to the lug 43 and the knife blade is
tioned to allow said shoe to move transversely to the di
forced down against the anvil with the full force of the
rection of travel of said bag, resilient means urging said
solenoid and severs the leading stitching to a predeter 45 shoe toward said work plate, a plunger with attached
mined length. Ideally the force from the solenoid will
knife blade slidably mounted with respect to said support
be applied until the stitch is cut. As the plunger and
block and movable to position to cut said stitching, a
the tang of the solenoid are not joined, the plunger will
solenoid operably associated with said plunger, resilient
override the tang and complete the cutting stroke even
means urging said knife away ‘from said cutting position,
if the solenoid is not energized for the full stroke 50 and means responsive to the movement of said bag for
length. This insures complete cutting of the stitching
energizing said solenoid.
after the parts have been used and worn.
2. The combination as speci?ed in claim 1 wherein
As the solenoid is no longer energized after the stitch
said means for energizing said solenoid includes an elec
ing is severed, spring 44 is free to return knife blade 41
tric switch in a solenoid energizing circuit, cam means
to position away from the bag and stitching.
65 operably associated with said switch, actuator means
The work plate 36 and the upright wall of shoe 32
operably associated with said cam means to move said
form a guide for the leading stitching so it may be pushed
cam means to position to actuate said switch responsive to
ahead of the bag without bending or moving out of line
the movement of a leading edge of said bag toward said
with the knife. Without this type of support for the lead
needle and to actuate said switch responsive to the move
ing stitching it is dif?cult to get a uniform length of lead 60 ment of a trailing edge of said bag away from said needle.
thread. The shoe keeps the thread from sagging and
3. The combination as speci?ed in claim 2 wherein
guides it to an exact position for cutting by the knife.
said solenoid is energized for a predetermined length of
The bag 23 moves through the machine to a posi
time independent of the length of time that said electric
tion as shown in FIG. 5. The leading edge of the bag
switch is actuated.
top section 22 slides under the rear end portion of shoe 65
4. The combination with a bag sewing machine having
32 against the action of springs 35 and the front end
a substantially horizontally reciprocating needle moving
of shoe 32 continues to support the leading chain stitch.
in relation to a substantially vertical work plate to form
The shoe 32 moves to position as shown in FIG. 3 as the
bag advances. At all times the shoe 32 is below the
chain-type stitching used for sewing a bag, passing be
tween the needle and work plate, closed, of: a cutting
70 device including a support block ?xedly attached to said
When the bag has been completely closed and moves
machine, a ?rst rod slidably mounted in said support
out of the machine, the rear end of the shoe 32 moves
block, a second rod slidably mounted in said support
under the urging of springs 35 against wall 36 and there
and movable substantially parallel to said ?rst rod,
by supports the trailing chain stitch before the stitching
chain-type stitching.
can sag.
This position is best seen in FIG. 6.
a stitch support shoe pivotally attached adjacent a ?rst end
When 75
thereof to said ?rst rod and pivotally attached adjacent
switch movable to a ?rst position for activating an elec
a second end thereof to said second rod, said shoe being
tric circuit for energizing said solenoid, said circuit in
positioned below said needle and adjacent said needle in
the direction of travel of a bag that is being sewed, resil
ient means urging said shoe into contacting relationship
with said work plate, said shoe being of con?guration to
cluding means to control the length of time the solenoid
is energized regardless of the length of time said switch
is in said ?rst position, a cam mounted with respect to
yieldably move to allow each of Said end portions of said
shoe to move to allow a bag to pass between said end
said switch, a bag contacting member operably associated
portion and said work plate with the opposite end portion
switch to said ?rst position responsive to movement of a
with said cam to move said cam to position to move said
leading edge of said bag toward said needle and respon
of said shoe in position against said work plate, an anvil
attached to said machine and substantially aligned wit 10 sive to movement of a trailing edge of said bag away from
said needle.
said work plate, a plunger with attached knife slidably
mounted with respect to said support block and movable
References Cited in the ?le of this patent
to position to cooperate with said anvil to cut said chain
stitching, resilient means for urging said plunger in direc
tion away from said anvil, a solenoid mounted with re
spect to said sewing machine and having a tang positioned
to contact said plunger to force said attached knife to cut
said stitching when said solenoid is energized, an electric
Krasa ________________ __ Dec. 3, 1929
Pierce ______________ __ Mar. 21, 1939
Bates _______________ __ Sept. 25, 1951
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