JP2792202B2 - Sewing machine with automatic thread trimming mechanism - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a sewing machine with an automatic thread trimming mechanism, and more particularly to a sewing machine having an upper thread end holding mechanism for automatically holding an end of an upper thread cut at the end of sewing. The present invention relates to a device in which an operation / non-operation mode can be set alternatively.

(Prior art)

Conventionally, as described in, for example, JP-A-56-139793, at the end of sewing, the movable blade is engaged with the fixed blade via the drive of the lower shaft between the needle plate and the shuttle to drive the upper thread and the lower thread. A sewing machine provided with a thread trimming mechanism for automatically cutting at a predetermined timing is already known.

If the thread amount from the eye of the sewing needle to the thread end of the upper thread is short in this sewing machine with a thread trimming mechanism, the thread end of the upper thread will fall out of the eye at the first needle at the start of sewing. To prevent this, the yarn is cut while leaving a large amount of yarn from the eye hole to the yarn end.

However, when sewing with this sewing machine with a thread trimming mechanism,
Although the upper thread can be prevented from coming off from the eye, the amount of thread from the eye to the end of the thread is long, so the upper thread remains long on the back side of the fabric and is entangled with the lower thread from the second stitch, as shown in FIG. As shown, there is a problem that the upper thread Ns and the lower thread Bs are entangled in a bird's nest on the back side of the fabric W, and the quality of the sewn product is extremely reduced.

Japanese Utility Model Laid-Open Publication No. 61-157487 discloses that the first thread at the start of sewing prevents the thread end of the upper thread from coming out of the eye hole, and the upper thread and the lower thread are nested on the back side of the fabric. In order to prevent entanglement in the shape, after the sewing is completed, the end of the upper thread cut by the thread cutting mechanism is captured by the thread capturing member above the needle plate, and the upper thread end is captured by the thread holding member and the thread capturing member. A sewing machine provided with a thread holding device for holding the sewing needle at a position far away from the sewing needle in cooperation with the sewing machine has been proposed.

However, in the sewing machine equipped with this thread holding device, the upper thread and the lower thread do not become entangled in a bird's nest on the back side of the work cloth at the start of sewing, but as shown in FIG. Since the yarn amount to the yarn end of the yarn Ns is left long and the upper yarn end is held at a position far away from the eye hole, the long upper yarn Ns remains on the front side of the fabric W, and the end of the upper yarn Ns is manually formed. There are problems such as the necessity of a thread picking operation for cutting the portion, and the leftover of the upper thread remaining on the cloth surface even after the thread picking operation.

Accordingly, the applicant of the present application has filed Japanese Patent Application No. 1-285660,
At the end of sewing, the upper thread end portion of the upper thread cut short by the thread cutting mechanism is held by the thread holding member in cooperation with the holding force applying member at the thread holding position near the side of the sewing needle located at the uppermost position. And an upper thread end holding mechanism configured to hold the upper thread end at the thread holding position from the start of sewing until the upper thread of the first stitch is interlaced with the lower thread. A sewing machine with a thread trimming mechanism that remains short without being entangled with the lower thread on the back side of the fabric was proposed.

[Problems to be solved by the invention]

However, in a sewing machine with a thread cutting mechanism proposed by the applicant of the present application, when a special upper thread having a high degree of elasticity such as nylon is used, the upper thread end cut at the end of the sewing is used as the upper thread end holding mechanism. When sewing is started in the state where the upper thread is held, the sewing operation causes a large tension to act on the upper thread particularly from the eye of the sewing needle to the upper thread holding section, and the upper thread portion is extended, and thereafter the upper thread is threaded. When the holding of the end is released, the upper thread expands and contracts to its original length, so that there is a problem that the seam formed at the initial stage of sewing is frayed or the upper thread comes off from the eye hole.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic thread trimming mechanism that can use a special upper thread having a high degree of elasticity in addition to a general upper thread having a low degree of elasticity, and that can sew reliably with clean stitches from the first needle. To provide an attached sewing machine.

[Means for solving the problem]

A sewing machine with an automatic thread trimming mechanism according to the present invention includes a sewing needle driven by a sewing machine motor, a balance driven up and down in synchronization with the sewing needle, a shuttle for interlacing an upper thread and a lower thread, and responding to a thread trimming command. A thread trimmer mechanism for automatically cutting the upper thread and the lower thread between the needle plate and the shuttle, a thread tension mechanism for applying a resistance to the upper thread between the thread supply source and the balance, and a thread tension mechanism. A tension releasing mechanism for releasing the resistance applied to the upper thread by the mechanism, a thread catching position near the lower part of the sewing needle located at the uppermost position, and a thread holding position and a thread near the side of the sewing needle located at the uppermost position A thread holding member which is located above the holding position and is movable over a standby position where the upper thread end is released, and holds the upper thread end in cooperation with the thread holding member at the thread holding position. An upper thread end holding mechanism having a holding force applying member, and operatively connected to a thread holding member of the upper thread end holding mechanism. An operation mode in which the upper thread end holding mechanism is operated and a non-operation mode in which the upper thread end holding mechanism is not operated, in a sewing machine having an automatic thread trimmer mechanism provided with a thread retaining driving means for selectively switching the thread retaining member to the three positions. And a thread holding member for holding the thread holding member of the upper thread end holding mechanism at the standby position when the inoperative mode is set via the mode setting means. Thread control means for controlling the driving means, and controlling the thread holding drive means in connection with the end of the thread cutting operation of the thread cutting mechanism and the start of the sewing machine motor when the operation mode is set. It is.

[Action]

In the sewing machine with the automatic thread cutting mechanism according to the present invention,
When the operation mode is set by the mode setting means, at the end of sewing, the tension releasing mechanism is operated, and the thread holding control means moves the thread holding member from the standby position when the thread cutting operation by the thread cutting mechanism ends. Since the yarn holding driving means operatively connected to the yarn holding member of the upper yarn end holding mechanism is controlled so as to switch to the yarn holding position via the capture position,
The yarn holding member cooperates with the holding force applying member at the yarn holding position to hold the upper yarn end. When sewing is started by the start of the sewing machine motor, the thread holding control means moves the thread holding member above the thread holding position and releases the upper thread end with the tension release mechanism being operated. The driving means for holding the yarn is controlled so as to switch to the standby position where the upper yarn end is released.

On the other hand, when the non-operation mode is set by the mode setting means, the yarn holding control means controls the yarn holding driving means so as to hold the yarn holding member at the standby position.

〔The invention's effect〕

According to the sewing machine with the automatic thread trimming mechanism according to the present invention, by providing the mode setting means and the thread holding control means,
When using a general upper thread having a low degree of expansion and contraction, the cut end of the upper thread is held by the upper thread end holding mechanism. The quality of the sewn product at the start of sewing can be improved without thread loss.

On the other hand, when using a special upper thread with a high degree of expansion and contraction, the holding mechanism is not operated at the upper thread end, so no tension is applied to the upper thread end, and the upper thread end is slightly longer. By doing so, it is possible to sew with beautiful stitches from the initial stage of sewing without thread coming off from the eye holes.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to a sewing machine having a thread cutting mechanism and a tension release.

First, the thread tension mechanism 1 for applying a resistance to the upper thread Ns fed from a thread spool (not shown) and the tension releasing mechanism 2 for removing the resistance will be described.

Except that a spring rotation restricting mechanism 154 is added to the thread tension mechanism 1, the thread tension mechanism 1 has the same structure as an existing general thread tension mechanism, and thus will be described briefly.

As shown in FIG. 1 to FIG.
A pivot member 10 is fixed to a portion of the machine frame 5 at the front end of the head 8, and a thread tension shaft 15 is attached to the pivot member 10 so as to be movable in the front-rear direction. A tension plate 11, a movable thread tension plate 12, a cap-shaped spring rotation restricting member 155, and a compression spring 13 are externally fitted, and a needle thread Ns is provided at a front end of the pivot support member 10.
An adjusting knob 14 for adjusting the resistance force applied to the spring is screwed. The compression spring 13 is provided over the adjusting knob 14 and the spring rotation restricting member 155. However, the movable thread tension disc 12 and the spring rotation regulating member 155 cannot rotate with respect to the pivot support member 10, and the spring force of the spring 13 is reduced by rotating the adjustment knob 14 clockwise or counterclockwise. A pair of thread tension plates that change
The resistance acting on the upper thread Ns sandwiched between 11 and 12 is adjusted. The fixed thread tension plate 11 is engaged with the step of the pivotal support member 10 from the front, and the portion in front of the step of the pivotal support member 10 is the third portion.
As shown in the figure, the movable thread tension plate 12 is divided into divided slits 10b by divided slits 10b extending in the axial direction.
Is formed, the front end of the thread tension shaft 15 is in contact with the input portion 12a, and the thread tension shaft 15 is moved forward against the spring force of the compression spring 13. The movable thread tension plate 12 is separated from the fixed thread tension plate 11 so that the resistance applied to the upper thread Ns is released.

On the rear side of the fixed thread tension tray 11, a coil spring portion at the base end of the thread take-up spring 151 is accommodated in a spring accommodating space in the pivot support member 10, and the end thereof is fixed to the pivot support member 10, and the pivot support member
Thread take-up spring 15 from the circumferential slit opening formed in 10
1 is extended to the outside, and the leading end of the thread take-up spring 151 is projected upward.
Threading portion bent in a substantially U-shape in plan view at a position facing
152 are formed. A locking member 156 fixed to a later-described spring rotation restricting member 155 is provided at a distal end of the thread take-up spring 151.
A contact portion 153 that contacts the locking portion 157 is provided. The thread hook 152 is constantly urged by a spring force so as to be in the operation position indicated by the solid line in FIG. Therefore, when the upper thread Ns is supplied to the yarn catcher 32 by the lowering of the balance 150, the thread hooking section 152 moves to the operating position to absorb the slack of the upper thread Ns, and the upper thread Ns Is a thread catcher 32
When it is picked up from above, the upper thread Ns is elastically deformed to the inoperative position shown by the broken line in FIG.

On the rear side of the thread tension shaft 15, a cam driven shaft 15A is supported by the machine frame 5 so as to be able to move back and forth. The front end of the cam driven wheel 15A abuts the rear end of the thread tension shaft 15, and the rear end is a pin 9 And abuts on a cam portion 17 of a cam plate 16 pivotally attached to the machine frame 5. The cam portion 17 has an operating portion that pushes the cam driven shaft 15A forward, and a step-down portion that drops down from the operating portion. The drive section 18 of the cam plate 16 is connected to a thread loosening solenoid 20 via a connecting rod 19.
Is connected to the plunger 21. The thread loosening solenoid 20 is fixed to the machine frame 5 by a bracket 22, and the plunger 21 is constantly urged to the left in FIG. Therefore, when the thread loosening solenoid 20 is not energized, the cam driven shaft 15A abuts the stepped portion of the cam portion 17 and does not push the thread tension shaft 15 forward, so that the movable thread tension plate
The spring 12 and the spring rotation restricting member 155 are held at a pressing force applying position indicated by a solid line in FIG. 2, and a resistance adjusted by the adjusting knob 14 is applied to the upper thread Ns. However, when the thread loosening solenoid 20 is energized, the connecting rod 19 moves rightward in FIG. 1, the cam plate 16 rotates clockwise, and the cam driven shaft 15A
7 to push the thread tension shaft 15 forward, the movable thread tension plate 12 moves to the tension release position, the spring rotation restricting member 155 moves to the forward position, and the movable thread tension plate 12 The resistance applied to the upper thread Ns at a predetermined distance from the fixed thread tension tray 11 is released.

Next, the rotation restricting mechanism 154 for holding the thread take-up spring 151 at the inoperative position will be described with reference to FIGS.

A thread take-up spring 151 is provided on the outer cylindrical portion of the spring rotation restricting member 155.
The base end of the locking member 156 for regulating the rotation of
It is fixed with. The distal end of the locking member 156 is located near the right side of the contact portion 153 of the thread take-up spring 151 moved to the inoperative position. The abutting portion against which the abutting portion 153 of the thread take-up spring 151 abuts when it is switched to the forward position after being switched to
157 and a notch 158 that allows the contact portion 153 to pass when the spring rotation restricting member 155 moves to the retracted position.

Therefore, when the thread take-up spring 151 rotates to the inoperative position and the spring rotation restricting member 155 moves to the forward position, the contact portion 153 contacts the locking portion 157 to move the thread take-up spring 151 to this inoperative position. On the other hand, when the spring rotation restricting member 155 moves to the retracted position, the contact portion 153 freely passes through the cutout portion 158, and the thread take-up spring 151 can be elastically deformed between the inoperative position and the inoperative position. become.

Next, the thread cutting mechanism 3 for cutting the upper thread Ns and the lower thread Bs will be described. Since this is the same as that described in JP-A-56-139793, it will be briefly described.

As shown in FIG. 4 and FIG.
A needle plate 27 having a needle hole (not shown) through which is inserted is mounted. A lower shaft 28 is rotatably supported on the machine frame 5 below the needle plate 27, and a left end of the lower shaft 28 Sword point 29, outer pot 30, and inner pot
A bobbin case 33 for accommodating a bobbin (not shown) is provided with a full-rotation type thread ring catcher 32 generally called a shuttle having
The upper thread Ns and the lower thread Bs are entangled with each other in cooperation with the vertical movement of the sewing needle 24 to form a stitch on the work cloth W.

A fixed blade 34 is screwed to the machine frame 5 on the front side of the thread catcher 32 at a substantially front half thereof, and a rear half of the fixed blade 34 is located in the vicinity of the needle hole of the needle plate 27 along the thread catcher 32. It extends in a circular arc shape, and a blade portion 35 is formed at the tip thereof. Reference numeral 36 denotes an inner hook stopper for restraining rotation of the inner hook 31, and reference numeral 37 denotes a fixed blade when the upper thread Ns detached from the blade point 29 during sewing is pulled up.
This is a shielding plate that prevents entanglement with 34.

A movable blade holder 38 is rotatably supported on the machine frame 5 on the rear side of the thread catcher 32 so that the movable blade holder 38 can reciprocate around the same axis as the lower shaft 28. Movable blade on mounting part 39
40 are screwed. A thread separating portion 41, a thread catching groove portion 42, and a blade portion 43 are formed at an arc-shaped left end of the movable blade 40. On the other hand, in order to rotate the movable blade 40, a swing arm 45 is fixed to a swing shaft 44 which is rotated by a cam drive mechanism (not shown), and the swing arm 45 is movable via a connecting lever 46. The connecting portion 47 of the blade holder 38 is connected. Further, in order to drive the cam driving mechanism by rotating the lower shaft 28, the cam driving mechanism is connected to a driving shaft of a thread cutting solenoid 48 (see FIG. 10). Reference numeral 49 denotes a winding spring for urging the swing arm 45 to rotate counterclockwise in FIG. 4 so as to hold the movable blade 40 at the non-cutting position shown in FIG. Accordingly, when the thread trimming solenoid 48 is energized at a predetermined timing at the end of sewing as described later, the rotation of the lower shaft 28 drives the cam drive mechanism and the swing shaft 44 rotates in the direction of the arrow. Moving arm 45
The movable blade holder 38 is rotated clockwise in FIG. 4 via the connecting lever 46, and the movable blade 40 is also rotated clockwise in FIG.
At the timing when the thread ring of the upper thread Ns is disengaged from the blade point 29 of the outer hook 30, the movable blade 40 simultaneously captures the upper thread Ns and the lower thread Bs connected to the work cloth W and engages with the blade portion 35 of the fixed blade 34. And cut it. Here, the length of the cut upper thread Ns from the eye hole 25 of the sewing needle 24 to the thread end (hereinafter, referred to as the upper thread end length) is proportional to the length of the thread catching groove 42. Trench groove
If the length of 42 is reduced, the length of the upper thread end can be reduced.

Next, the upper thread end holding mechanism 51 and the thread holding drive mechanism 52 that hold the upper thread end of the upper thread Ns cut after the sewing is completed will be described.

As shown in FIGS. 6 to 9, a mounting plate 53 is screwed to the rear side of the head 8 of the sewing machine M, and a second solenoid (a bistable latching solenoid) disposed vertically.
54 is fixed to the substantially left half of the mounting plate 53 by a bracket 58, and a first solenoid 59 disposed vertically is fixed to the substantially right half of the mounting plate 53 by a bracket 61. The second solenoid 54 is provided with an upper moving solenoid 55 and a lower moving solenoid 56 (see FIG. 13). When the upper moving solenoid 55 is driven, the plunger 57 moves upward as shown in FIG. (In the direction of arrow U) and is held in the upward movement position,
When the lowering solenoid 56 is driven, the plunger 57 moves down (in the direction of arrow D) and is held at that lowering position. Immediately above the second solenoid 54, a first output link 62 having a substantially U-shape in side view is rotatably supported by a mounting plate 53 with a pin 65 oriented in the front-rear direction. A substantially U-shaped second output link 66 is pivotally supported on the mounting plate 53 by pins 69 oriented in the front-rear direction.

The drive arm 63 of the first output link 62 is pivotally connected to a connecting member 70 fixed to the upper end of the plunger 57 of the second solenoid 54, and the swing arm 64 of the first output link 62 is A pin 74 fixed to the first arm 72 of the substantially L-shaped first link 71 is fitted into the long hole 64a and connected to the first link 71. The first link 71 is rotatably supported at its base end by a mounting screw 53 with a stepped screw 76 in the front-rear direction via a spacer 75, and the lower end of the second arm 73 of the first link 71 is The stepped screw 77 is rotatably connected to the right end of the second link 78. The left end of the second link 78 is rotatably connected to the lower end of the third link 80 by a pin 79, and is rotatably connected to the upper end of the fourth link 81. The lower end of the fourth link 81 is a thread. The gripping link member 82 is rotatably connected to the right end of the drive arm 83 by a pin 85.

On the other hand, the drive arm 67 of the second output link 66 has its long hole 67a.
A pin 87 fixed to a connecting member 86 fixed to the lower end of the plunger 57 of the second solenoid 54 is fitted to the connecting member 86, and the right end of the swing arm 68 of the second output link 66 is
At 88, it is rotatably connected to the upper end of the fifth link 89.
The lower end of the link 89 is connected to the first arm 92 of the thread holding link 91 by a pin 90.

A boss 53a in the front-rear direction is fixed to the lower end of the mounting plate 53, and a pivot 94 in the front-rear direction is rotatably supported by passing through the boss 53a and the mounting plate 53. 94
A holder mounting plate 95 is fixed to the front end of the holder, a thread holding holder 96 is screwed to the holder mounting plate 95, and a holding force applying member 97 made of a spring member is screwed to the thread holding holder 96. I have. The distal end portion of the holding force applying member 97 is formed as a downwardly convex curved thread pressing portion 98 (elastic contact portion).

A boss 99 having a step at the rear end of the pivot 94
Is fixedly attached. Therefore, the upward or downward movement of the fifth link 89 causes the yarn holding link to move.
91 rotates counterclockwise or clockwise, and the holding force imparting member 97 is rotated counterclockwise or clockwise in synchronization with the thread holding link 91 via the pivot 94, the holder mounting plate 95, and the thread holding holder 96. Rotate in the direction.

On the other hand, the pivot shaft 94 is inserted through the base end of the drive arm 83 and the base end of the swing arm 84 of the substantially U-shaped thread grasping link member 82 in a plan view, and the thread grasping link member 82 is A thread holding member 100 is screwed to the swing arm 84 so as to be rotatably supported by a pivot 94. Note that reference numeral 102 is a spacer. The front end portion of the thread holding member 100 is formed in an arc shape centered on the pivot 94, and the left end portion of the arc portion captures the upper thread Ns extending downward through the eye hole 25 of the sewing needle 24. A hook portion 101 (yarn catching portion) is formed, and the yarn pressing portion 98 of the holding force applying member 97 elastically abuts a concave portion on the upper surface of the hook portion 101 and cooperates with the hook member 101 to form the upper thread Ns. The end can be held. Accordingly, the yarn gripping link member 82 rotates counterclockwise or clockwise due to the upward or downward movement of the fourth link 81, and the yarn holding member 100 rotates counterclockwise or clockwise. A pivot between the swing arm 84 and the mounting plate 53
One end of a winding spring 103 provided on the 94 is locked to the base end of the thread gripping link member 82, and the other end is locked to a pin 104 fixed to the second arm 93 of the thread holding link 91. The gripping link member 82 is always urged to rotate counterclockwise in FIG. 8 with respect to the thread holding link 91, and the thread holding link 91 is constantly urged clockwise to the thread gripping link member 82. Therefore, the thread presser 98 can reliably contact the hook 101. The drive arm 83 and the sliding arm 84 of the thread gripping link member 82 have an open angle of about 30 degrees.

A pin 105 in the front-rear direction is fixed to the lower end of the plunger 60 of the first solenoid 59, and a third output link 106 substantially U-shaped in side view is fixed to the lower end of the bracket 61 in a front-rear direction. The third output link 106 is rotatably supported at 109 by a helical spring 110 provided on the pin 109 so that the contact portion 107 of the third output link 106 always contacts the pin 105 from below. Is urged to rotate clockwise. The swing arm 108 of the third output link 106 is the third link 80
Is rotatably connected to an upper end portion of the housing by a pin 111. still,
Reference numeral 26 denotes a needle bar, reference numeral 112 denotes a presser bar, and reference numeral 113 denotes a presser foot.

Next, the operation of the upper thread end holding mechanism 51 and the thread holding drive mechanism 52 will be described with reference to FIGS. 8 and 13 to 16.

When the upward moving solenoid 55 is driven, the plunger 57 moves upward and moves to the upward moving position shown in FIG. 13, and the first output link 62, the first link 71, the second link via the connecting member 70. 7
8, fourth link 81, thread gripping link member 82, thread holding member 100
Respectively move to the solid line positions. The yarn holding member 100 at this time
Is the standby position. On the other hand, as the plunger 57 moves to the upward movement position, the fifth link 89, the thread holding link 91, the holder mounting plate 95, the thread holding holder 96, and the holding force applying member 97 are respectively connected via the connecting member 86. Move to the solid line position.
The position of the holding force applying member 97 at this time is set as a standby position (see FIG. 14). At the standby position, the thread holding member 100 is largely rotated in the counterclockwise direction, and the hook portion 101 is located at a position far above the needle plate 27.

Next, when the lowering solenoid 56 is driven, the plunger 57 moves down and moves to the lowering position shown in FIG. 13, and the first output link 62, the first link 71, The second link 78, the fourth link 81, the thread gripping link member 82, and the thread holding member 100 move to the dashed line positions, respectively. The position of the yarn holding member 100 at this time is defined as a yarn holding position. At this thread holding position, the hook portion 101 of the thread holding member 100 is located near the right side of the sewing needle 24 at the uppermost position. On the other hand, with the downward movement of the plunger 57, the second output link 66 via the connecting member 86,
The fifth link 89, the thread holding link 91, the holder mounting plate 95, the thread holding holder 96, and the holding force applying member 97 are each moved to the dashed line position in FIG. 13 (see FIG. 16). At this time, the thread presser 98 of the holding force applying member 97 can engage with the recess of the hook 101 to hold the upper thread Ns.

In this state, when the first solenoid 59 is driven, the plunger 60 moves down, and the third output link 1
06, third link 80, fourth link 81, thread gripping link member 8
2. The thread holding members 100 move to the two-dot chain line positions in FIG. 13, respectively. At this time, the hook portion 101 of the thread holding member 100 is located near the lowermost position of the sewing needle 24 at the uppermost position, and catches the end of the upper thread Ns extending downward from the eye hole 25 of the sewing needle 24. The position of the yarn holding member 100 at this time is defined as a yarn catching position. When the driving of the first solenoid 59 is stopped, the third output link 106, the third link 80, and the fourth link 8 are driven by the spring force of the winding spring 110.
1.Since the thread gripping link members 82 return to the dashed line positions in FIG. 13 respectively, the thread holding member 100 returns to the thread holding position with the hook 101 capturing the upper thread end, and the holding force. The upper thread end is held in cooperation with the thread presser 98 of the applying member 97 (see FIG. 16).

Further, when the upward moving solenoid 55 is driven, the thread holding member
100 and the holding force imparting member 97 move to the standby positions, respectively, but the second link 78, the third link 80, and the fourth link 81
Immediately after the start of the movement to the standby position, the moving speed of the yarn holding member 100 becomes slower than the moving speed of the holding force applying member 97, and the holding force is applied as shown in FIG. The thread presser 98 of the member 97 comes off the hook 101, and the upper thread end is released. The thread holding member 10 at this time
The position of 0 is the release position.

Next, the overall configuration of the control system of the sewing machine M will be described with reference to the block diagram of FIG.

The thread trimming solenoid 48, the thread loosening solenoid 20, the upper moving solenoid 55, the lower moving solenoid 56, the first solenoid 59, and the sewing machine motor 115 are connected to the drive circuits 116 to 121, respectively, and the respective drive circuits 116 to 121 are controlled. Each is connected to the input / output interface 130 of the device C.

The operation panel 122 is used to set a loosening time setting key for setting the loosening time (t2) of the upper thread Ns by the tension release 2 immediately after the start of sewing or from releasing the needle end of the upper thread Ns from the needle lower position immediately after the start of sewing. A release time setting key for setting the release time (t3) of the thread and a setting switch 126 for selectively setting an operation mode for operating the upper thread end holding mechanism 51 and a non-operation mode for not operating the key are provided. And outputs setting data and switch signals set by operating the switches to the input / output interface 130. The setting switch 126 outputs an “L” level switch signal SS when switched to set the operation mode, and outputs an “H” level switch signal SS when switched to set the non-operation mode. Output.

The foot pedal 123 has three positions: a front depressed position, a horizontal neutral position, and a rear depressed position, and outputs a sewing machine start command signal (“H” level) as a depressed signal when the operator depresses the front depressed position. , The sewing machine stop command signal (“L” level) is output to the input / output interface 130 when the pedal is depressed to the rear depressed position.

The needle-up signal generator 124 switches the rotation position of a metallic disk member having a small opening formed at a predetermined circumferential position provided on a sewing machine main shaft (not shown) driven by the sewing machine motor 115 to a vicinity switch. And outputs a needle up signal to the input / output interface 130 when the sewing needle 24 is at the uppermost position.
The needle down signal generator 125 is configured similarly to the needle up signal generator 124, and outputs a needle down signal to the input / output interface 130 when the sewing needle 24 is at the lowest position.

The control device C includes a CPU 132 and an input / output interface 13 connected to the CPU 132 via a bus 131 such as a data bus.
0, a ROM 133 and a RAM 140.

The ROM 133 stores a control program for upper thread processing control including upper thread holding control and thread loosening control.

The set thread loosening time (t2) data is stored in the thread loosening set time data memory 141 of the RAM 140. The upper thread release set time data memory 142 stores the set release time (t3) of the upper thread Ns. The flag memory 143 is reset (data is “0”) when the operation mode for operating the upper thread end holding mechanism 51 is set, and is set (data is “0”) when the non-operation mode for not operating is set. 1 ") is stored. The needle-down signal generator 125
The count value of the under-needle signal input from (i.e., the content thereof is I) is stored. Further, the RAM 140 is provided with various memories for temporarily storing the results calculated by the CPU 132.

Next, a routine of the upper thread processing control performed by the control device C of the sewing machine M will be described with reference to FIGS. 12 to 16 based on the flowcharts of FIGS. 11 (a) and 11 (b). I do. However, in order to easily understand the description, the operation mode is set by the setting switch 126 in order to use a general upper thread Ns having a low degree of expansion and contraction, the foot pedal 123 is depressed to the front depressed position, and S1 to S18 are depressed. This will be described from the execution of the sewing operation. In the figure, Si (i = 1, 2, 3,...) Indicates each step, and T1 to T9 in FIG. 12 indicate timings, respectively.

When the foot pedal 123 is operated from the front depressed position to the rear depressed position via the neutral position at the time of T1 during the execution of the sewing, and the stop command signal of the “L” level is input as the depressed signal (S19: Yes), when the two needle down signals are input from the needle down signal generator 125 and the count value I becomes "2" at T2 (S20: Yes, S21, S22: Yes), the thread trimming solenoid 48 and the thread loosening. Each of the solenoids 20 is driven (S2
3). Thereafter, when the sewing machine motor 115 is rotated at a low speed and a needle up signal is input from the needle up signal generator 124 (S24: Ye
s), the driving of the thread trimming solenoid 48 is stopped (S25), the driving of the sewing machine motor 115 is stopped, and the brake in the sewing machine motor 115 is activated by the brake signal. It stops (S26). Then, at T4, the lowering solenoid 56 is driven for a predetermined time (for example, 60 msec) (S27). Accordingly, as described above, the thread gripping link member 82 and the thread holding link 91 move from the solid line position in FIG.
The 100 and the holding force applying member 97 move to the thread holding position shown in FIG. Subsequently, the first solenoid 59 is driven for a predetermined time (for example, 60 msec) (S28). Therefore, the thread holding member 1
Only the thread 00 moves to the thread catching position and returns to the thread holding position again with the thread end of the upper thread Ns extending from the eye hole 25 of the sewing needle 24 captured by the hook portion 101, and the thread of the holding force applying member 97 Presser section
In cooperation with 98, the upper thread end is held. Then the first
At T5 when the driving of the solenoid 59 is stopped, the driving of the thread loosening solenoid 20 is also stopped (S29).

Here, an operation of stably stabilizing the length from the eye hole 25 of the sewing needle 24 to the upper thread end held by the thread holding member 100 will be described.

When the upper thread Ns is cut at T2, the upper thread Ns is supplied to the movable blade 40 via the thread hooking section 152 by the movement of the movable blade 40, so that the thread hooking section 152 is It moves from the working position to the non-working position due to the sliding friction with At this time, since the spring rotation restricting member 155 is moved to the forward position by the driving of the thread loosening solenoid 20, the contact portion 153 is at a position facing the locking portion 157. When the upper thread Ns is cut,
153 is locked by the locking portion 157, and the thread take-up spring 151 is held at its inoperative position. As a result, since the rotation of the thread take-up spring 151 is restricted at the inoperative position, the length of the upper thread end from the eyelet 25 to the upper thread end is constant regardless of the type of the upper thread Ns. On the other hand, even if the driving of the thread loosening solenoid 20 is stopped when the upper thread end is captured by the driving of the first solenoid 59, the upper thread Ns is kept in the upper thread end holding mechanism 51 and the thread tension mechanism 1
And the thread take-up spring 151 is held in its inoperative position.

Then, the switch signal SS from the setting switch 126 is read (S2), and since the switch signal SS is at the "L" level, the flag F is reset (S4).
At the time of T6, when the foot pedal 123 is operated to depress the front depressed position (the depressed signal is at the “H” level) (S6: Y
es) When the operation mode is set to use a general upper thread Ns having a low degree of expansion and contraction (S7: Yes), the first timer M1 provided in the control device C has a predetermined time t1 (for example, , 100 msec) is stored and counting is started (S
8), at T7 when the predetermined time t1 has elapsed (S9: Yes), the sewing machine motor 115 is driven at a low speed by the sewing machine motor drive signal (S10), and the setting data t2 of the thread loosening setting time data memory 141 is stored in the control device. Is stored in the second timer M2 in C (S1
1) When the thread loosening solenoid 20 is driven (S12) and a needle down signal is input from the needle down signal generator 125 (S13: Yes),
The setting data t3 of the upper thread release set time data memory 142 is stored in the third timer M3 in the control device C (S14), and when the time of the third timer M3 is T8 (S15: Yes), for example, When descending from the uppermost position to form a loop of the upper thread Ns and the entanglement (knot) of the upper thread Ns and the lower thread Bs is formed, the upper moving solenoid 55 is driven for a predetermined time (for example, 60 msec) (S16). ). At this time, the release position (the first position) of the yarn holding member 100 immediately after the movement of the yarn holding member 100 and the holding force applying member 97 from the yarn holding position shown in FIG. 16 to the standby position shown in FIG.
The upper thread end is released at the time of (see Fig. 5). Thereafter, at the time T9 when the second timer M2 times up, for example, when the sewing of several stitches is performed and the upper thread Ns and the lower thread Bs are surely entangled (S17: Yes), the thread loosening solenoid 20 Is stopped and the sewing machine motor 115 is driven at high speed (S1
8), sewing is continued continuously.

Here, the operation of the upper thread Ns not falling out of the eyelet 25 at the time of starting sewing will be described.

Simultaneously with the start of sewing, the thread loosening solenoid 20 is driven, the spring rotation restricting member 155 moves to the forward position, and the thread take-up spring 151, which has moved to the inoperative position when sewing is stopped, is Continue to hold in working position. Accordingly, since the thread take-up spring 151 does not rotate to the operation position and is sewn at a low speed, the first and subsequent stitches are sewn while the length of the upper thread end is kept constant, and the upper thread Ns is sewn. Never get out of

In this way, the upper thread end of the upper thread Ns cut at the end of sewing is held at the thread holding position near the side of the sewing needle 24 located at the uppermost position by the thread holding mechanism 51, and the upper thread end is sewn. Since the thread is held from the start until the confounding of the upper thread Ns and the lower thread Bs is formed, the end of the upper thread Ns moves to the back side of the fabric W by the sewing operation of the second and subsequent stitches as shown in FIG. It does not remain on the front side, and the upper thread end does not become entangled with the lower thread Bs in a bird's nest shape, eliminating the need for thread picking work, significantly improving the sewing product quality at the start of each sewing. it can.

On the other hand, when sewing is started (S6: Yes), when the non-operation mode is set by the setting switch 126 to use a special upper thread Ns having a high degree of elasticity such as nylon (S7: No). The upper moving solenoid 55 is driven for a predetermined time to move the thread holding member 100 and the holding force applying member 97 to the standby position (S30), and thereafter the upper thread is operated without operating the upper thread end holding mechanism 51 in S31 to S41. A normal sewing operation of operating only the thread cutting mechanism 3 without holding the end is performed.

Incidentally, while providing a large number of slits on the periphery of a disk-shaped disk attached to the upper shaft driven by the sewing machine motor 115, a pulse generator for outputting a pulse signal from a sensor through these slits was provided. Thread loosening set time (t
The number of pulses of this pulse signal may be used instead of 2) and the upper thread release set time (t3).

As described above, when a special upper thread Ns having a high degree of expansion and contraction is used, the upper thread end is not held. , The thread can be sewn with clean stitches from the initial stage of sewing without the thread coming off from the eye holes 25 of the sewing 24.

The setting switch 126 can be provided at any place other than the operation panel 123 that does not hinder the sewing operation.

It should be noted that the thread tension mechanism 1, the tension release mechanism 2, and the thread trimming mechanism 3 in the above-described embodiment are merely examples, and it is a matter of course that various known structures can be used instead of these. Thread holding drive mechanism 52 and upper thread end holding mechanism
51 is only an example, and various existing ones are, of course,
It goes without saying that various modifications and alterations of the embodiment are used.

A supplementary description will be given of the correspondence between the means described in the claims and the components in the embodiments.

What corresponds to the mode setting means is the setting switch 126 of the operation panel 122 and the like. What corresponds to the thread holding driving means is the thread holding driving mechanism 52, and in particular, the second solenoid 54 including the upper moving solenoid 55 and the lower moving solenoid 56 of the thread holding driving mechanism 52; The first solenoid 59 corresponds to this.

FIG. 11 (a) shows an equivalent of the yarn holding control means.
The flowchart of (b) and the control device C for achieving the control are shown.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention. FIG. 1 is a front view of an arm portion of a sewing machine partially cut away, FIG. 2 is a partial side view of the sewing machine, and FIG. FIG. 4, FIG. 4 is a partial longitudinal sectional side view of a bed portion, FIG. 5 is a partial perspective view of a thread catcher and a thread cutting device, FIG. 6 is a partial side view of a thread holding drive mechanism, FIG. Is a side view of the drive mechanism for holding the yarn and the upper end holding mechanism, FIG. 8 is a sectional view taken along the line VIII-VIII of FIG. 7, FIG. 9 is a sectional view taken along the line of FIG. 8 IX-IX, and FIG. 11 (a) and 11 (b) are schematic flowcharts of a routine of upper thread processing control including upper thread holding control and thread loosening control, and FIG. 12 is a time chart of various signals. FIG. 13 is a mechanism diagram of an upper thread end holding mechanism and a thread holding drive mechanism, FIGS. 14 to 16 are partial front views showing respective states of the thread holding mechanism, and FIG. FIG. 18 and FIG. 19 are enlarged sectional views of the cloth showing the thread end of the upper thread at the sewing start portion, and FIG. 18 and FIG. 1 Thread tension mechanism 2 Thread tension release mechanism 3 Thread trimming mechanism 11 Fixed thread tension plate 12 Movable thread tension plate 15
… Thread tension shaft, 15A… Cam driven shaft, 20… Thread loosening solenoid, 30… Outer hook, 31 …… Inner hook, 34 …… Fixed blade, 40 ……
Movable blade, 48: Thread cutting solenoid, 51: Upper thread end holding mechanism, 52: Thread holding drive mechanism, 54: Second solenoid, 55: Upward solenoid, 56: Downward solenoid, 59
... 1st solenoid, 71 ... 1st link, 78 ... 2nd link, 80 ... 3rd link, 97 ... holding force giving member, 100
… Thread holding member, 132… CPU, 133… ROM, 140… RA
M, C ... Control device.

Claims (1)

(57) [Claims] 1. A sewing machine driven by a sewing machine motor, a balance driven up and down in synchronization with the sewing needle, a shuttle for interlacing an upper thread and a lower thread, and a needle plate and a shuttle in response to a thread trimming command. A thread trimming mechanism that automatically cuts the upper thread and the lower thread between the thread, a thread tension mechanism that applies a resistance to the upper thread between the thread supply source and the balance, and a thread tension mechanism that is added to the upper thread by the thread tension mechanism. A tension release mechanism for releasing the drag force, a thread catching position near the lowermost position of the sewing needle, a thread holding position near the side of the uppermost sewing needle, and a position above the thread holding position. A thread holding member movable to a standby position for releasing the upper thread end, and a holding force applying member for retaining the upper thread end in cooperation with the thread holding member at the thread holding position. A yarn end holding mechanism, the yarn holding member being operatively connected to the yarn holding member of the upper yarn end holding mechanism, and In the sewing machine having an automatic thread trimmer mechanism provided with a thread holding driving means for alternatively switching, an operation mode in which the upper thread end holding mechanism is operated and a non-operation mode in which the upper thread end holding mechanism is not operated are selectively set. Mode setting means for controlling the thread holding driving means to hold the thread holding member of the upper thread end holding mechanism at the standby position when the inoperative mode is set via the mode setting means, An automatic thread provided with thread holding control means for controlling the thread holding driving means in association with the end of the thread cutting operation of the thread cutting mechanism and the start of the sewing machine motor when the operation mode is set; Sewing machine with cutting mechanism.