Elastic tape sewing machine

The elastic tape sewing machine comprises feed teeth feeding a combined body of a fabric and an elastic tape, a sewing needle sewing the elastic tape on the fabric, a presser foot including an elastic tape through-hole and movable to and from said feed teeth to hold the combined body of the fabric and the elastic tape with the feed teeth, a supply device including a retaining means retaining the elastic tape utilizing spring force of an elastic body and feeding the elastic tape through the elastic tape through-hole to one side of the presser foot opposing the feed teeth, a guide device guiding the elastic tape fed from the supply device to a sewing-ready position between the presser foot and the feed teeth, and a cutting device to cut the elastic tape, characterized in that said retaining means includes a regulating apparatus formed by a regulating mechanism having a motor rotating predetermined angle by an electric signal to regulate the spring force of the elastic body and a controller controlling the rotation angle of the motor.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an improvement of a sewing machine to sew 
an elastic tape to a fabric. 
2. Description of the Prior Art 
A generally known elastic tape sewing machine is adapted to place a sewing 
portion of an elongated elastic tape to be sewn on a fabric, to retain the 
combined body of the elastic tape and the fabric between feed teeth and a 
presser foot opposed to the feed teeth, to feed the combined body by the 
feed teeth and to sew the elastic tape by a sewing needle to the fabric. 
In this case, the elastic tape is supplied from a tape winding bobbin 
through a through hole in the presser foot to space between the feed teeth 
and the presser foot. 
Conventionally, in such a sewing machine, the elastic tape to be sewn is 
fed to have suitable tension on the fabric. Thus, in the course of the 
elastic tape from the bobbin to the presser foot, the elastic tape is 
passed between a pair of retaining members pressing the elastic tape. The 
retaining members are adapted to press the elastic tape by urging a 
movable retaining member onto a fixed retaining member by the force of a 
spring. 
However, such retaining members can not adjust the force of the spring 
automatically and precisely. To apply suitable tension to the elastic 
tape, an adjusting screw may be manually turned on the fixed retaining 
member to compress the spring inserted between the movable retaining 
member and the adjusting screw so as to adjust the spring force. That is 
troublesome and time consuming problem. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide an elastic tape sewing 
machine which has a mechanism to regulate the spring force of a spring 
means automatically in order to apply suitable tension to the elastic 
tape. 
To attain the above mentioned object, an elastic tape sewing machine 
includes feed teeth for feeding a combined body of a fabric and an elastic 
tape, a sewing needle sewing the elastic tape onto the fabric, a presser 
foot including an elastic tape through hole and movable to and from said 
feed teeth to hold the combined body of the fabric and the elastic tape 
with the feed teeth, a supply device including a retaining means retaining 
the elastic tape utilizing spring force of an elastic body and feeding the 
elastic tape through the elastic tape through hole to one side of the 
presser foot opposing the feed teeth, a guide device guiding the elastic 
tape fed from the supply device to sewing-ready position between the 
presser foot and the feed teeth, and a cutting device to cut the elastic 
tape, characterized by said retaining means including a regulating 
apparatus formed by a regulating mechanism having a motor rotating 
predetermined angle set by electric signal to regulate the spring force of 
the elastic body and a controller controlling the rotation angle of the 
motor. 
Accordingly, by controlling the rotation angle of the motor by the 
controller, the spring force of the spring body, i.e., elastic tape 
retaining force of the elastic body, can be precisely regulated so that 
conventional troublesome manual adjustment is completely eliminated, and 
suitable tension can be applied to the elastic tape now to be used. 
The motor of the regulating apparatus may preferably be a stepper motor. 
For example, a pulse motor or inclemental motor can be used as the motor 
for regulating apparatus. 
According to other features of the present invention, an elastic tape 
sewing machine having feed teeth feeding a combined body of a fabric and 
an elastic tape, a sewing needle sewing the elastic tape onto the fabric, 
a presser foot including an elastic tape through-hole and movable to and 
from said feed teeth to hold the combined body of the fabric and the 
elastic tape with the feed teeth, a supply device including a retaining 
means retaining the elastic tape utilizing the spring force of an elastic 
body and feeding the elastic tape through the elastic tape through-hole to 
one side of the presser foot opposing the feed teeth, a guide device 
guiding the elastic tape fed from the supply device to a sewing-ready 
position between the presser foot and the feed teeth, and a cutting device 
to cut the elastic tape, characterized by said retaining means including a 
regulating apparatus formed by a regulating mechanism having an 
intermittent motion mechanism intermittently linear or rotational moving 
to regulate the spring force of the elastic body and a controller 
controlling the amount of the linear or rotational movement of the 
intermittent motion mechanism. 
Accordingly, by controlling the amount of the intermittent movement of the 
intermittent motion mechanism, the spring force of the elastic body, i.e. 
elastic tape retaining force by the elastic body, can be precisely 
regulated, so that the conventional troublesome manual operations are 
completely eliminated, and suitable tension can be applied to the elastic 
tape.

BEST MODE FOR CARRYING-OUT THE INVENTION 
Referring now to FIG. 1, an elastic tape sewing machine, according to the 
present invention, includes feed teeth 1 and a presser foot 2 opposed to 
the feed teeth 1. Between the feed teeth 1 and the presser foot 2, a 
combined body 5 formed by a fabric 3 and an elongated elastic tape 4 to be 
sewn onto the fabric is arranged. The sewing machine according to the 
present invention is shown as an overlock sewing machine to sew the 
elastic tape 4 to tubular end of clothes, e.g., wrist band. However, it is 
not limited to such use and can be applied to sew an elastic tape to a 
flat fabric or to sew a band-like body to fabric. 
The feed teeth 1 perform conventional feed motion through an opening 6a of 
a feed plate 6 to feed the combined body 5 to a direction shown by arrow 
in FIG. 1. The feed plate 6 is secured to a table 7 which is secured to a 
frame 11 of the sewing machine. In the embodiment shown, the presser foot 
2 is pivotably mounted at the rear end by a pin 9 to one end 8a of a link 
8. The link 8 is pivotably mounted to the frame 11 at position 8b to 
contact and release the combined body 5. The presser foot is urged 
clockwise by a biasing spring, not shown, to normally urge the presser 
foot against combined body 5. The other end 8c of the link 8 is engaged to 
a link drive means, e.g., one end of a piston 10a of an air cylinder 10. 
The air cylinder is mounted to the frame 11 of th sewing machine. 
When the piston 10a is extended from the position shown in FIG. 1, the link 
8 rotates counterclockwise to release the presser foot 2 from the combined 
body 5 against the spring. When the piston 10a contracts the presser foot 
urges the combined body 5 by the spring to the feed plate 6 and the feed 
teeth 1 with suitable pressure. The presser foot 2 includes an elastic 
tape through-hole 12 through which the elastic tape passes vertically 
through the front end of presser foot as shown in FIG. 4. 
A supply device 20 feeds the elastic tape 4 to the through-hole 12 of the 
presser foot 2 and includes a body 21. A base 21a of the body 21 is 
pivotably supported by a horizontal shaft 23 on a support body 22 which is 
secured to the table 7. At the free end of the body 21, a retaining means 
24 is provided to retain the elastic tape 4. The retaining means 24 is 
formed at the free end of the body 21 and is formed by a guide groove 25 
receiving smoothly the elastic tape 4, and an urging assembly 26 which 
urges the elastic tape 4 which is received in the groove 25 by suitable 
urging force. The urging assembly 26 is formed by an arm 28 which is 
pivotably supported by pin 27 to the body 21 at one end, and an elastic 
body 30 which is mounted by a screw 29 to the other end of the arm. The 
other end of the elastic body 30 makes contact with the elastic tape which 
is received in the guide groove 25 by suitable pressure to retain the 
elastic tape in the guide groove 25. In this state, when strong force is 
applied axially to the elastic tape, the elastic tape can slide in the 
guide groove. Further, the arm 28 includes a slot 28a to pass the elastic 
tape as shown in FIG. 2. 
The elastic tape 4 is fed from a bobbin, not shown, which winds the elastic 
tape, it then passes through the retaining means 24 and the elastic tape 
through-hole 12 of the presser foot 2, and is fed between the presser foot 
and the feed teeth, i.e., between the lower surface of the presser foot 
and the upper surface of the fabric. 
The elastic tape 4 is sewn by a needle 40 to the fabric. The needle 40 is 
conventional and supports a thread, not shown, and is vertically driven by 
a drive means, not shown. When sewing, the sewing needle passes through a 
hole 41 in the presser foot 2, the elastic tape 4, the fabric and a needle 
hole 42 in the feed plate 6. 
A cutting device 50 cuts the elastic tape after a predetermined length of 
the elastic tape is sewn to the fabric. The cutting device 50 is arranged 
in the elastic tape through hole 12 of the presser foot 2. As shown in 
FIG. 4, the cutting device 50 is formed from a circular movable blade 51 
and a fixed blade 52. The movable blade 51 is rotatably received in a hole 
53 which is formed midway in the through-hole 12. The movable blade 51 
forms a through-hole 54 which can be aligned with the through hole 12. 
Thus, as shown in FIG. 4a, at first, the elastic tape passes from the 
upper surface of the presser foot 2 into the through-hole 12 and through 
the through-hole 54 and again through the through hole 12 to the lower 
surface of the presser foot 2. The fixed blade 52 is fixed to the presser 
foot 2 generally tangentially to the movable blade 51. As shown in FIG. 
4a, the fixed blade 52 has a knife edge portion 52a which opposes the 
elastic tape 4 exiting from the through holes 54 and 12. As shown in FIG. 
1, the movable blade 51 has a projection 51a projected from the hole 53 to 
connect to a drive means. The drive means is formed by an air cylinder 55 
in the illustrated embodiment. A cylinder portion 55a of the air cylinder 
55 is mounted on the link 8, and an outer end of a piston rod 55b is 
connected to the projection 51a through a connecting lever 56. When the 
piston rod 55a extends from the position shown in FIGS. 1 and 4a, the 
movable blade 51 rotates clockwise shown in FIG. 4a to a position shown in 
FIG. 4b. By the rotation, the elastic tape is cut by the fixed blade 52. 
When the piston rod 55b contracts, the movable blade 51 rotates 
counterclockwise in FIG. 4b to return to the position shown in FIG. 4a. 
Thus, the elastic tape is cut in the presser foot so that the elastic tape 
can be cut near the needle. To cut the elastic tape as near to the needle 
as possible, the fixed blade is positioned near the lower surface of the 
presser foot. 
After the elastic tape is cut in the presser foot 2, in order to sew the 
end of the elastic tape connected with the supply device 20 again to the 
fabric, the end of the elastic tape should be fed to a position which is 
projected and extended from the lower surface of the presser foot 2. This 
is done by rotating and urging the body 21 toward the presser foot 2. A 
drive mechanism 60 rotates the body 21 toward and from the presser foot 2 
as shown in FIG. 1. In the illustrated embodiment, the drive mechanism 60 
includes a spring 61 which urges the body 21 toward the presser foot 2, 
and an air cylinder 62 which rotates the body 21 from the presser foot 2 
against the spring force. A cylinder portion 62a of the air cylinder 62 is 
mounted on a frame 63 which is secured to the support body 22. A free end 
of a piston rod 62b of the air cylinder 62 is positioned to be engageable 
with the body 21. One end of the spring 61 is fixed to the body 21 and the 
other end is fixed to the frame 63. Thus, when the piston rod 62b 
contracts from the position shown in FIG. 1, the body 21 rotates clockwise 
as shown by arrow in FIG. 1 by the force of the spring 61 so that the free 
end of the body 21 moves toward the presser foot 2 and the cut end portion 
of the elastic tape 4 which is supported by the retaining means 24 
projects from the lower surface of the presser foot 2. When the piston rod 
62b extends, the body 21 moves from the presser foot 2. 
Further, when the free end of the body 21 moves toward the presser foot 2 
to project the end of the elastic tape 4 from the lower surface of the 
presser foot 2, a free end 30a of the elastic body 30 fits in a groove 2a 
of the presser foot 2. Thus, the free end 30a of the elastic body 30 
guides the elastic tape to insert the elastic tape easily into the elastic 
tape through-hole 12. A stopper 64 shown in FIG. 1 is mounted on the frame 
and limits the clockwise rotation of the body 21. 
After the cut end of the elastic tape is projected from the lower surface 
of the presser foot, a guide device 70 shown in FIG. 1 guides the 
projected end between the presser foot and the feed teeth, i.e., sewing 
ready position. The guide device 70 is formed by an air nozzle 71 and an 
air supply source, not shown, to feed pressurised air to the air nozzle 
71. Air outlets 71b of the nozzle 71 inject air toward the outlet of the 
elastic tape through-hole 12. The air nozzle acts to let the cut end of 
the elastic tape move along the feed direction of the fabric. When the 
presser foot is in an upward position, the air nozzle injects pressurised 
air. 
A regulating device 80 regulates the elastic tape retaining force of the 
retaining means 24. The regulating device 80 includes a shaft 81 which 
engages with the arm 28 at one end, a lever 82 pivotably connected with 
the body 21 at one end and is pivotably connected by the other end of the 
arm at intermediate portion, a stepping motor 83 connected with the other 
end of the lever 82, and a controller 84 to control the stepping motor 83. 
The shaft 81 passes through the body 21 and the arm 28, and forms at one 
end a head 81a which engages with the arm 28. Between the arm 28 and the 
body 21, a coil spring 85 encircles the shaft 81. The coil spring acts to 
rotate the arm 28 counterclockwise, as shown in FIG. 1. An output shaft 
83a of the stepping motor 83 has a pulley 86 which is wound by one end of 
a wire 87 the other end thereof which is connected through a spring 88 
with the other end of the lever 82. 
The controller 84 controls the rotation angle of the stepping motor 83, and 
includes well-known micro-computer, not shown, which performs memory, 
operation and input and output function. The controller is operated 
through switches 89 on the sewing machine table and switches 91 on a 
keyboard 90. 
By rotation of the stepping motor 83, the lever 82 rocks through the wire 
87 and the spring 88, to move the arm 28 toward and from the body 21. 
Thus, the elastic tape retaining force of the elastic body 30 can be 
precisely regulated. 
The controller 84 is constructed as follows: The controller can set and 
store a plurality of position information or data to control the rotation 
angle of the stepping motor previously as desired. Then, afterward, the 
position information can be indexed and read out by operator one by one. 
Or if a plurality of such position information and order is to be read 
out, the position information or data is first stored as reference 
information, and then the read-out information is changed and controlled 
by the operations of the switch 89. That is, ten position informations 
corresponding to ten keys 91 of 0-9 on the keyboard 90 are stored in the 
first memory portion in the micro-computer previously so that when a 
switch 92 is set as input mode and when first No. 2 key of the keys 91 is 
pushed and then secondly the switch 89 is pushed, position information of 
program No. 2 is read out from the first memory portion and is written in 
a second memory portion. Similarly, when first No. 8 key of the keys 91 
and then secondly the switch 89 are pushed, position information of 
program No. 9 is written in the second memory portion next to the 
aforementioned position information of No. 8. Following this, the switch 
92 changes to the practice mode, so that the writing operation is 
prohibited and now the first piece of position information written in the 
program No. 2 can be read out from the second memory portion and the 
stepping motor 83 operates in response to this position information. 
Following this operation, when the switch 89 is pushed, the position 
information of program No. 9 which has been written as the second piece of 
information on the second memory portion is read out from the second 
memory portion and the stepping motor 83 rotates and stops at a 
predetermined position in response to that position information. After 
that, the order of position information read out from the second memory 
portion is controlled by the order of input order by every operation of 
the switch 89. 
When the switch 92 is input mode, and the key 89 is pushed while No. 1 and 
6 keys 91 are pushed simultaneously, information or data written in the 
second memory portion is erased. Thus, new position information or data 
can be read out from the first memory portion and can be written in the 
second memory portion. 
In the above mentioned construction, the elastic tape 4 is guided through 
the slot 28a of the arm 28, the guide groove 25 of the body 21, and the 
cutting device 50 in the presser foot 2, to the lower surface of the 
presser foot 2 to be sewn to the fabric by the needle 40 holding upper 
thread. 
In this case, the elastic tape 4 has frictional resistance applied to it by 
the free end of the body 21 and the elastic body 30. Thus, the elastic 
tape 4 is elongated corresponding to the frictional resistance and is sewn 
to the fabric. The frictional resistance applied to the elastic tape 4 is 
changeable by the rotation angle of the stepping motor 83. The rotation 
angle can be switched to a plurality of steps by the controller 84, and 
the position and order thereof can be previously programmed as desired, 
and further, the switching of the rotation angle by the operator operating 
the switch 89 can be performed even while sewing is in process. For 
example, although the order of the three positions of the rotation and 
stop position have been previously selected and set, by every operation of 
the switch 89 these three stop position of the stepping motor can be 
changed. 
After sewing, the sewing machine drive pedal is operated to operate the air 
cylinders 55, 10 and 62 sequentially. Thus, by operation of the air 
cylinder 55, the elastic tape 4 is cut, as shown in FIG. 4b. Then, by 
operation of the air cylinder 10, the presser foot 2 moves upward to 
release urging force to the elastic tape and the fabric. Then, by 
operation of the air cylinder 62, the body 21 rotates clockwise from the 
position shown in FIG. 1, until the body 21 engages with the stopper 64 so 
that the elastic tape retained between the free end of the body 21 and the 
elastic body 30 is fed into the through-hole 12. 
As the elastic tape 4 is fed, the cut end thereof projects from the lower 
surface of the presser foot. When the presser foot 2 is raised, air is 
injected from the air nozzle 71 so that portion of the elastic tape 4 
projected from lower surface of the presser foot 2 is bent by the air 
pressure along the lower surface of the presser foot, as shown in FIG. 4a. 
When the presser foot 2 is lowered, the elastic tape 4 is urged between 
the feed teeth and the lower surface to enable the next sewing action. 
FIG. 5 shows another regulating device 80' which regulates the spring 
action of the elastic body 30, i.e., the retaining force of the elastic 
tape 4 by the elastic body 30. The regulating device 80' includes an 
intermittent motion mechanism including an operation shaft 94 having saw 
teeth 94a, a stepping spring 95 urging the operation shaft 94 in the 
direction of arrow shown in FIG. 5, and a stepping solenoid 96 having a 
finger 96a engageable with the saw teeth 94a, and a controller 98. 
One end of the operation shaft 94 has a slit 94b which extends normally to 
the axis of the operation shaft. One end of a link element 99 is movably 
connected with the slit, and the other end thereof is pivotably connected 
with the other end of a lever 82 through a pin 100 to rock the lever 82 by 
the operation shaft 94. 
When operational, the stepping solenoid 96 draws the finger 96a to release 
the saw teeth 94a against the force of the return spring 96b. When the 
stepping solenoid is deenergized by the spring force of the return spring 
96b, the finger 96a engages with the saw teeth 94a. 
The controller 98 applies a pulse signal to the stepping solenoid 96 to 
operate the stepping solenoid at intervals, and includes a micro-computor 
to set operation numbers of the stepping solenoid 96 as desired. 
The other end of the operation shaft 94 has a return solenoid 101 which is 
operated by the controller 98 to return the operation shaft 94 against the 
spring force of the stepping spring 95 to its original position in a 
revers direction to that of the arrow shown in FIG. 5. 
When the controller 98 operates the stepping solenoid 96, the finger 96a 
repeatedly moves back and forth to move the operation shaft 94 by the 
stepping spring 95 and so that each one tooth of the saw teeth 94a rotates 
the lever 82 counterclockwise shown in FIG. 5 through the link element 99. 
When the controller 98 selects a high number of operations for the stepping 
solenoid 96, the movement of the operation shaft 94 in the direction of 
arrow shown in FIG. 5, i.e., counterclockwise rotation of the lever 82 in 
FIG. 5. becomes large, so that the arm 28 moves nearer to the body 21 to 
increase the spring force of the elastic body 30 such that the elastic 
tape retaining force by the elastic body 30 is increased. When the number 
of operations of the stepping solenoid is set less, the shaft 81 moves the 
arm 28 slightly to towards the body 21 so that the spring force of the 
elastic body is less and the elastic tape is retained by the elastic body 
30 by a smaller force. Consequently, the elastic tape retaining force 
exerted by the elastic body 30 can be precisely regulated. 
Further, though not shown in the drawing, an intermittent motion mechanism, 
a feed pawl operated by a solenoid may rotate a ratchet wheel at 
intervals. In this case, a controller controlling the solenoid has ratchet 
wheel rotation angle information which is previously set and stored. A 
drum concentric with the ratchet wheel winds the wire 87 shown in FIG. 1. 
In this case, when the controller operates the solenoid, the ratchet wheel 
rotates at intervals by the feed pawl to pull the wire 87 to rock the 
lever 82 so that the elastic tape retaining force exerted by the elastic 
body 30 can also be precisely regulated.