JPS6023635B2 - sewing machine - Google Patents

Description

[Detailed description of the invention] Technical field This invention relates to a sewing machine.

BACKGROUND ART For example, in a conventional automatic thread trimming sewing machine, the thread trimming signal is generated based on a thread trimming signal generated while the needle moves from a lower position to an upper position in synchronization with the lifting of the thread take-up body of the thread take-up mechanism at the end of a sewing operation. The thread cutting mechanism is activated, and necessary threads such as upper and lower threads connected to the work cloth are captured, let out, and then cut.

However, in this conventional sewing machine, depending on the type and thickness of the work cloth used for sewing, the type and thickness of the thread, the operating speed of the thread trimming mechanism, etc., some thread remains on the needle side after the thread is cut by the thread trimming mechanism. If there is a large variation in the length of the upper thread and the remaining length of the upper thread is short, the upper thread will come off the needle when the next sewing starts, making it impossible to continue sewing, or the remaining length of the upper thread may be short. If the thread length is long, there will be a large amount of thread ends remaining on the underside of the workpiece fabric during the next sewing process, resulting in a decrease in the quality of the workpiece, and sometimes the thread ends connected to the workpiece cloth must be manually cut and removed. There was also a need to do so.

Purpose of the Invention The present invention has been made in order to eliminate the above-mentioned defects in conventional sewing machines, and its purpose is to eliminate the problems within several stitches from the start of the first thread supply operation of the thread take-up mechanism at the start of sewing. By pulling up the needle thread from the needle side, if you pull out a long length of the needle thread before cutting it after the end of the sewing operation, the thread will be pulled up when the next sewing starts. It is possible to optimize the amount of thread remaining at the beginning of the warp of the seam, to prevent the thread from coming off at the beginning of sewing, and to improve the appearance of the beginning of sewing. By providing a resistance imparting means for imparting resistance to the thread on the needle thread path between the thread take-up mechanism and the needle, even if the needle thread is suddenly pulled up, the inertia of the needle thread eye will prevent it from being pulled up more than the required amount. The object of the present invention is to provide a sewing machine in which this problem is completely prevented.

EXAMPLE An example of the present invention will be described below with reference to the drawings.
Frame 1 of the sewing machine includes arm 2 and bed (not shown)
A main shaft (not shown) is rotatably supported within the arm 2.

A needle bar 4 having a needle 3 (shown in FIG. 4) at its lower end is supported on the head of the arm 2 so as to be movable up and down, and a presser bar 5 having a presser foot (not shown) at its lower end is movable up and down. is supported by. As shown in FIG. 4, a well-known fully rotary thread catcher 6 is provided in the bed, and an outer hook 6b having a tip 6a and an inner hook 6c whose rotation is restrained by an inner hook stopper 7.
When a bobbin case 8 containing a bobbin (not shown) is attached, the needle moves with the rotation of the main shaft, rotates at twice the speed of the main shaft, and cooperates with the needle 3. A lock stitch is formed on the processed cloth. As shown in FIG. 4, a fixed blade 9 of a thread cutting mechanism is arranged in the bed near one side of the thread catcher 6.

A movable blade 10 of a thread cutting mechanism is rotatably disposed near the pond side of the thread trapping device 6 so as to correspond to the fixed blade 9, and the tip thereof has a thread handling section 10a and a thread catching recess 10b. and a blade portion 10c are formed. At the end of the sewing operation, the movable blade 10 is rotated clockwise in FIG. 4 based on a thread trimming signal issued while the needle 3 moves from the lower layer to the upper position, and the upper thread TI The needle thread TI and the bobbin thread T2 connected to the work cloth are caught at the same time when they come off the tip 6a of the outer hook 6b, and are fed out, and then cut in cooperation with the fixed blade 9. It is supposed to be done. In this case, the thread payout amount is the minimum required amount L that will not cause the thread to come out at the start of the next sewing after thread cutting.
This is the amount plus the extra yarn amount of 1. The arm 2
A thread take-up mechanism is provided inside the thread take-up mechanism that is operated as the main shaft rotates, and as shown in FIGS. It protrudes onto the path of the upper thread TI guided to the needle 3 through the thread hole 11a, so that the upper thread TI can be inserted through the thread hole 11a. Then, as the thread take-up body 11 descends, the upper thread TI is supplied to the thread catcher 6, and as the thread take-up member 11 rises, the upper thread TI caught by the thread catcher 6 is picked up. It is about to be done. A main thread tension device 13 is provided on the front surface of the arm 2 so as to be located on the needle thread path closer to the needle thread supply source than the thread take-up body 11 .

Therefore, to explain the structure of the main thread tension device 13 in detail, as shown in FIG.
A cylindrical thread tension stand 15 is fixed therethrough, and as shown in FIGS. 5 and 7, an insertion hole 15a is formed on the outer periphery near the front end of the thread tension stand 15. A thread tension shaft 17 is fixed through the thread tension stand 15 by a fixing screw 16, and a threaded portion 17 is provided at the front end of the thread tension shaft 17.
a is formed, and a locking groove 17b is formed on the outer periphery of the substantially central portion. A pair of thread tension discs 18 are rotatably inserted and supported at the front end of the thread tension shaft 17, and the upper thread TI is passed between the thread tension discs 18.

A thread tension spring 19 is inserted into the thread tension shaft 17 in front of the thread tension disc 18, and both thread tension discs 18 A predetermined thread tension pressure is applied to the upper thread TI in between. On the other hand, a sub-thread tension device 21 is provided on the upper surface of the arm 2 so as to be located on the needle thread path closer to the needle thread supply source than the main thread tension device 13.

As shown in FIG. 1, the auxiliary thread tension device 21 includes a pair of thread tension discs 22, a housing 23 containing a thread tension spring (not shown), and an adjustment dial 2 for adjusting thread tension pressure.
4 to apply a predetermined thread tension pressure to the upper thread TI between the thread tension discs 22. Further, as shown in FIGS. 5 and 7, a thread take-up spring 25 is installed approximately in the center of the thread tension shaft 17 in the thread tension stand 15 of the main thread tension device 13, and one end of the thread take-up spring 25 is attached to the thread tension shaft 17. 17, and the other end protrudes outward through the through hole 15a of the thread tension board 15, and the other end is connected to the thread tension blood 18 of the main thread tension device 13. A thread hooking portion 25a for hooking the needle thread TI is formed by bending on the needle thread path on the needle 3 side.

The thread hooking portion 25a of the thread take-up spring 25 is always urged toward the first position shown by the solid line in FIG. When the upper thread is supplied to the thread wheel auxiliary device 6 by lowering, the thread hooking portion 25a is moved to the first position and the upper thread T is moved to the first position.
At the end of the operation of picking up the upper thread from the thread catcher 6 by absorbing the slack of the thread take-up part 11, the thread hooking part 25a
is moved to a second position shown by the chain line in FIG. 7 to allow the needle thread TI to be fed out from the needle thread supply source. As shown in FIGS. 5 and 8, the thread tension shaft 1 is located between the thread tension disc 18 of the main thread tension device 13 and the thread take-up spring 25.
A lock plate 26 is rotatably supported on the lock plate 7, and an engagement pin 26a is protruded from the tip thereof, and an engagement piece 26b facing the thread take-up spring 25 is bent and formed on the outer periphery of the base end. ing.

As shown by the solid line in FIG. 1 and the two-dot chain line in FIG. The movement of the thread taker 25 between the first position and the second position is allowed, and the locking plate 26 is rotated to the other position, as shown by solid lines in FIGS. 2 and 7. When this is done, the engaging piece 26b engages with the thread take-up spring 25 in the vicinity of the thread hook 25a, and the thread take-up spring 25 is immovably held at the first position. As shown in FIGS. 1 to 3, a first solenoid 28 is attached to the front surface of the sewing machine arm 2 via a placket 27, and its armature 28a protrudes when demagnetized and retracts when energized.

In the vicinity of the first solenoid 28, a thread payout lever 30, which also serves as a thread puller, is supported by a stepped screw 29 on the front surface of the arm 2, and one arm portion 30a of the lever 30 is connected to the armature 28a via a connecting link 31. ing.
Further, this thread pay-out lever 30 is urged to rotate clockwise in FIG. 1 by a spring 32. And the first
As shown in the figure, when the first solenoid 28 is demagnetized, the biasing force of the spring 32 rotates the line pay-out lever 30 to a position where it is regulated by the stopper 33, and as shown in FIG. , the first solenoid 2
8 is energized, the thread pay-out lever 30 is rotated counterclockwise and placed in a substantially horizontal state. The main thread tension device 13 is located at the tip of the other arm portion 30b of the thread letting-out lever 30.
A first auxiliary thread tension device 34 is provided between the first auxiliary thread tension device 21 and the first auxiliary thread tension device 21 .

As shown in FIG. 6, the first auxiliary thread tension device 34 is
It consists of a thread tension shaft 35, a pair of thread tension bloods 36 attached to the thread tension shaft 35, a thread tension spring 37, and an adjustment dial 38 for adjusting the thread tension pressure.
The upper thread TI is held between them. Then, the first solenoid 28 is energized and the thread pay-out lever 30 is activated.
By being rotated from the position shown in the figure to the position shown in Figure 2,
Upper thread TI held between the first auxiliary thread tension device 34
is fed out from the needle thread supply source. This amount of payout is approximately equal to the needle thread TI caught and fed out by the movable blade 1 of the thread trimming mechanism. A thread letting-out means is constituted by a first solenoid 28, a thread letting-out lever 30 having a second auxiliary thread tension device 34, and the like. A release plate 39 is fixed to the upper part of the sewing machine arm 2, and when the thread pay-out lever 30 is placed in the position shown in FIG. The thread is inserted between both tension discs 36 of the container 34, and the thread clamping pressure is released. the first solenoid 2
8, a second solenoid 41 is fixed to the front surface of the sewing machine arm 2 via a bracket 40, and its armature 41a protrudes during depletion and is retracted during excitation.

This second solenoid 41, the thread pay-out lever 30
The needle thread pulling means is constituted by the above. A lock lever 43 is rotatably supported by a stepped screw 42 near the second solenoid 28, and a connecting link 44 is interposed between one arm portion 43a of the lock lever 43 and the armature 41a. One arm portion 43a of the lock lever 43 has a hook portion 43b that can hook the one arm portion 30a of the thread letting-out lever 30, and a cam surface 43c that can engage the one arm portion 30a of the thread letting-out lever 30. A stopper 45 made of a screw is provided on the other arm portion 43d. The lock lever 43 is prevented from rotating counterclockwise in FIG. 1 by a spring 46. As shown in FIG. 1, when the second solenoid 41 is deactivated, the lock lever 43 is rotated to a position where it engages with a stopper 47 on the sewing machine arm 2 by the biasing force of the spring 46. As shown in FIG. 3, when the second solenoid 41 is energized, the lock lever 43 is rotated a predetermined amount clockwise from the position shown in FIG. Furthermore, when the thread letting-out lever 30 is rotated counterclockwise with the excitation of the first solenoid 28 while the lock lever 43 is regulated in position by the stopper 47, the thread letting-out lever 30 is rotated counterclockwise. Cam surface 43 of lock lever 43
Thread tension pressure is applied to the front surface of the sewing machine arm 2 by a stepped screw 48 in the vicinity of the main thread tension device 13, which is stopped by the stop portion 43b after engaging the lock lever 43 and pushing away the lock lever 43. A first release lever 49 serving as a release means is supported so as to be able to be rolled around, and has a sandwiching portion 49a formed at its tip, and a second portion engaging the engagement pin 26a on the lock plate 26 at its intermediate portion. A prong 49b is formed.

Further, an engaging piece 49c is bent at the base end of the first release lever 49, and a stopper 46d made of a screw is attached so as to face the engaging piece 49c. The release lever 49 is urged to rotate counterclockwise in FIG. 1 by a spring 50. A connecting lever 51 is rotatably supported by the stepped screw 48 so as to be located between the engaging piece 49c and the stopper 49d. A connecting link 52 is pivotally attached to one end of the arm portion 30a of the thread letting-out lever 30, and an end portion of the connecting lever 51 is pivotally attached to the intermediate portion thereof. As shown in FIG. 1, when the first solenoid 28 is demagnetized and the thread pay-out lever 30 is placed in the needle thread release position (the position regulated by the stopper 33), The connecting lever 51 engages with the stopper 49d, thereby causing the first
The release lever 49 is disposed at one position, and its tip end clamping portion 49a is separated from the main thread tension device 13, and as shown in FIG. 30 is placed in the thread unwinding position (approximately horizontal position), the connecting lever 51 engages with the engaging piece 49c, and the first release lever 49 rotates counterclockwise from the position shown in FIG. The tip inserted portion 49a is connected to the main thread tension device 1.
The main thread tension device 13 releases thread tension pressure. Further, as shown in FIG. 3, the second solenoid 41 is energized and the lock lever 43 is activated.
When is rotated to a position away from the stopper 47,
The connecting lever 51 can be engaged with the stopper 45 of the lock lever 43, and when engaged, the spring 5
Due to the urging force of 0 and the engagement between the connecting lever 51 and the stopper 49d, the sandwiching portion 49a of the first release lever 49 is held in a state between the thread tension discs 18 of the main thread tension device 13, and Via the connecting link 52, the thread unwinding lever 30 is arranged at an intermediate position between the thread release position and the thread unwinding position. This intermediate position is
0 is the point where the thread returns to the needle thread supply source to pull up approximately half of the surplus thread amount 1. Furthermore, when the first release lever 49 is placed in the position shown in FIG. lock plate 2
When the engagement piece 26b of 6 is separated from the thread take-up spring 25 and the first release lever 49 is rotated to the position shown in FIG. 2, the lock plate 26 is rotated to the other position and engaged. Piece 26b engages thread take-up spring 25.

A second auxiliary thread tension device 53 is provided on the front surface of the sewing machine arm 2 on the needle thread path between the thread take-up body 11 and the needle 3, and applies thread tension pressure or resistance to the needle thread TI.

The configuration of the second auxiliary thread tension device 53 is similar to the first auxiliary thread tension device 34, including a thread tension shaft 54, a pair of thread tension discs 55, a thread tension spring (not shown), and an adjustment dial 5.
6. And each thread tension device 13
, 34, and 53 are set to become weaker in the order of the main thread tension device 13, the first auxiliary thread tension device 34, and the second auxiliary thread tension device 53. A second release lever 58 is rotatably supported near the second auxiliary thread tension device 53 by a stepped screw 57. This second release lever 58
, the second auxiliary thread tension device 53, etc. constitute a resistance applying means. One arm portion 58a of the second release lever 58 is formed with a recess 58b, and upper and lower inserting portions 58c and 58d located on both upper and lower sides of the recess 68b.
The other end of the connecting link 52 is connected to the other arm 58e of the second release lever 58, and as shown in FIG. 1 and FIG. , the upper and lower inserting portions 58c and 58d of the second release lever 58 are inserted between both thread tension discs 55 of the second auxiliary thread tension device 53 to release the thread tension pressure, and As shown in FIG. 2, when the thread pay-out lever 30 is in the intermediate position, the recessed portion 58b faces both thread tension bloods 55 and allows thread tension pressure to be applied. Next, the operation of the sewing machine configured as described above will be explained according to the flowchart shown in FIG.

Now, FIG. 1 shows a state in which the operating pedal (not shown) is depressed forward and sewing operation is being performed.

In this state, the first and second solenoids 28,
41 is exhausted, and the thread pay-out lever 30 is moved to the stopper 33.
The lock lever 43 is disposed at a release position where it is regulated by a stopper 47, and the lock lever 43 is disposed at a position where it is regulated by a stopper 47. Therefore, the pinching portion 39a of the release plate 39 is inserted between both thread tension bloods 36 of the first auxiliary thread tension device 34, and the thread clamping pressure by the first auxiliary thread tension device 34 is released. Further, the connecting lever 51 is rotated clockwise via the connecting link 52, and the first release lever 49 is rotated clockwise through the engagement between the connecting lever 51 and the stopper 49d of the first release lever 49. It has been rotated to

As a result, the pinched portion 49a of the first release lever 49 is separated from the main thread tension device 13, and the forked portion 49b of the first release lever 49 and the engagement pin 26 of the lock plate 26 are separated from each other.
The lock plate 26 is rotated counterclockwise through engagement with the lock plate 26, and the engagement piece 26b of the lock plate 26 is separated from the thread take-up spring 25. Therefore, the main thread tension device 13 is in the state of applying thread tension pressure, and the thread take-up spring 25 is in a state of being movable between the first position shown by the solid line in FIG. 7 and the second position shown by the chain line. Further, the second release lever 58 is rotated clockwise via the connecting link 52, and the lower grooved portion 58d is moved between both thread tension discs 5 of the second auxiliary thread tension device 53.
5, and the thread tension pressure of the second auxiliary thread tension device 53 is released. In this state, as the main shaft (not shown) rotates, the needle 3 and the thread take-up body 11 are moved up and down, and the thread catcher 6 is also rotated. A full stitch is formed, and as the thread take-up lever 11 descends during the stitch formation, the thread hooking portion 25a of the thread take-up spring 25 is moved from the second position to the first position by its own spring force. The slack in the upper thread TI is absorbed, and as the thread take-up lever 11 subsequently rises, the thread hooking part 25a of the thread take-up pan 25 is moved from the first position to the second position against its own spring force, and the thread is removed. At the same time, the insufficient needle thread amount for one pitch corresponding to the feed amount of the work cloth is let out from the needle thread supply source without being affected by the first auxiliary thread tension device 34.

Therefore, stitches with good thread closure are formed on the work cloth. When the forward depression of the operation pedal is released at the end of the sewing operation on the workpiece cloth, the main shaft is stopped at a rotation angle of 180 degrees, and the needle 3 is stopped at the downward position, as shown in FIG. be done.

Thereafter, when the operation pedal is pressed backward, the main shaft is rotated at a low speed, and the needle 3 is slowly raised from the lower position to the upper position, and the rotation angle of the main shaft is 230 degrees.
When the needle position is reached, a thread trimming signal is generated by a needle position detection device or the like. Therefore, based on the thread trimming signal, the movable blade 10 of the thread trimming mechanism shown in FIG. 4 is rotated clockwise, and the upper thread TI and upper thread T2 connected to the work cloth are captured simultaneously.
The yarn is cut after being let out by the amount L+1. On the other hand, when the thread trimming signal is output, the first
The solenoid 28 is energized and the armature 28a is retracted.

Therefore, the thread pay-out lever 30 is rotated counterclockwise from the position shown in FIG. 1, and the cam surface 43c of the lock lever 43 is
After the lock lever 43 is pushed away against the biasing force of the spring 46, it is hooked to the hook portion 43b and locked in the state shown in FIG. When the thread pay-out lever 30 is rotated counterclockwise in this way, the first auxiliary thread tension device 34 is separated from the tip pinching portion 39a of the release plate 39, and the upper thread is connected to the first auxiliary thread tension device 34. TI is clamped. Then, with the subsequent rotation of the thread pay-out lever 30, the upper thread TI is pulled out from the upper thread supply source V by the thread amount L11. Also, due to the rotation of the thread pay-out lever 30, the first and second release levers 49,
58 is rotated counterclockwise from the state shown in FIG. Entry 5
8c are respectively inserted between both thread tension discs 55 of the second auxiliary thread tension device 53.

Therefore, the thread tension pressure of the main thread tension device 13 is released, and the second auxiliary thread tension device 53 is also maintained in a state where the thread tension pressure is released. The thread TI is slackened to the extent that it is pulled out by the first auxiliary thread tension device 34, and is in a state where it can be easily let out. Therefore, the thread unwinding and cutting operations by the thread cutting mechanism described above are performed smoothly in this state. Furthermore, the first
With the rotation of the release lever 49, the lock plate 26 is rotated clockwise from the state shown in FIG.
The engagement piece 26b of No. 6 engages with the vicinity of the thread hooking portion 25a of the thread take-up spring 25, the thread hooking portion 25a is held at the first position, and its action is nullified.

Then, when the thread cutting mechanism finishes cutting the upper and lower threads T1 and T2 and the main shaft slightly exceeds the rotation angle of 60 degrees, its rotation is stopped and the needle 3 reaches the top dead center. The balance body 11 is stopped at the upper position where it has exceeded and slightly lowered, and the balance body 11 is stopped at the top dead center.

Further, when the sewing machine is stopped, the thread trimming signal is also erased, and the operation of the thread trimming mechanism is stopped based on the signal.
In this state, when the next sewing operation is started by depressing the operation pedal forward, the needle 3 is lowered from the upper stop position as the main shaft rotates, and the thread take-up body 11 is lowered from the top dead center. As shown in FIG. 3, the needle 3 and the thread catcher 6 cooperate to start forming a full stitch on the workpiece cloth.

Then, when the needle 3 passes through the bottom dead center of the first stitch and rises, and the balance body 11 reaches the bottom dead center, the detection signal is output and the second solenoid 41 is excited.

Therefore, the lock lever 43 is rotated from the position shown in FIG. 2 to the position shown in FIG. within the range of motion. When the lock lever 43 is disengaged from the thread letting-out lever 30, the thread letting-out lever 30 is moved to the second position by the biasing force of the spring 32.
The thread is about to be rotated from the thread letting-out position shown in the figure to the thread releasing position shown in FIG. Thread pay-out lever 301
The upper thread TI is stopped at the intermediate position shown in the figure, and the upper thread TI is pulled up from the needle 3 side by approximately half of the surplus thread amount 1. Also, the first
The release lever 49 engages with the connecting lever 51 at its stopper 49d, and is held in a pinched state with respect to the main thread tension device 13.

Therefore, the thread tension pressure release state of the main thread tension device 13 is maintained, and the locking state of the thread take-up spring 25 is maintained by the lock plate 26. Additionally, a second release lever 58
is rotatably disposed at an intermediate position, and its recessed portion 58b faces the second auxiliary thread tension device 53. Therefore, the second auxiliary thread tension device 53 applies thread tension pressure, that is, resistance, to the upper thread TI between the thread take-up body 11 and the needle 3. In this state, the thread take-up body 11 is raised from the bottom dead center toward the top dead center, and the excess yarn amount 1
The remaining approximately half of the amount of thread is pulled up from the needle 3 side.

Therefore, thread omission occurs at the beginning of sewing of the work cloth, and only the thread amount corresponding to the minimum length L remains, which prevents thread omission and does not damage the appearance. In addition, at this time, since the thread take-up spring 25 is immovably held at the first position by the lock plate 26 etc. as shown in FIG. The thread take-up spring 25 is not moved as the thread take-up spring 25 is moved up and down.
Due to the rise of the thread take-up body 11, the upper thread TI is removed from the thread catcher 6.
The thread theory is properly taken up and thread tightening is carried out, and beautiful seams with good thread ends are formed. This thread take-up spring 25
The action based on the lock is described in detail in Japanese Patent Application No. 55-51505 and Japanese Patent Application No. 51506-1987 by the same applicant, so please refer to these for details. Also, in this state, "as described above, resistance is applied to the upper thread TI by the second auxiliary thread tension device 53,
As the thread take-up body 11 rises, the upper thread TI will not be pulled up more than the required amount due to its own inertia, and there is no risk of the thread slipping out.

In this way, the first stitch is formed, and the thread take-up body 11
When it reaches the top dead center, the second solenoid 41 is deactivated, the lock lever 43 is rotated to the position where it is regulated by the stopper 47, and the stopper 45 on the lock lever 43 is rotated.
is separated from the connecting lever 51.

Therefore, the thread pay-out lever 30 is returned to the release position by the biasing force of the spring 32, and the first release lever 49 is returned to the position where it is separated from the king thread tension device 13 via the connection link 52 and the connection lever 51. Further, the second release lever 58 is connected to the second auxiliary thread tension device 53 at the lower insertion portion 58d.
It returns to the position where it is inserted between both thread tension discs 55. Therefore, the first and second auxiliary thread tension devices 34 and 53 are brought into the state of releasing the thread clamping pressure, the main thread tension device 13 is brought into the state of applying thread tension pressure, and the first release lever 49 is rotated. As a result, the lock plate 26 is rotated and the thread take-up 25 is unlocked. As described above, in the embodiment described above, at the start of sewing, the needle thread TI is pulled up by a predetermined amount from the needle side by the thread pay-out lever 30'.

In the above embodiment, the needle thread TI was pulled up at the first stitch at the start of sewing, but it may be pulled up within a few stitches of the 2nd to 5th stitches, and if it is within that few stitches, the purpose is not sufficiently achieved. It will be done.

The number of stitches at which the effect occurs depends on the thickness of the fabric and the feed pitch, etc. The thinner the fabric and the smaller the feed pitch, the less resistance is applied to the needle thread, so it may be delayed from the start of sewing. It is possible to sufficiently pull out the thread even at the same timing. Effects of the Invention As illustrated in the embodiments, the present invention is configured to pull up the needle thread from the needle side within several stitches from the start of the first thread supply operation of the thread take-up mechanism at the start of sewing. If the upper thread is pulled out first after the sewing operation is completed and before cutting the upper thread, the amount of thread remaining at the beginning of the stitch can be optimized by pulling the thread up when the next sewing starts. A resistance applying means is provided on the upper thread path between the thread take-up mechanism and the needle to improve the appearance of the sewing start part and to apply resistance to the upper thread when the upper thread pulling means is activated. As a result, even if the upper thread is suddenly pulled up, an excellent effect is achieved in that it is prevented from being pulled up more than the required amount due to the inertia of the upper thread.

[Brief explanation of drawings]

1 to 9 show a first embodiment of the present invention, and FIGS. 1 to 3 are front views of the sewing machine arm at the time of sewing, thread cutting, and start of sewing, respectively, and FIGS. The figure is a perspective view showing the thread loop catcher and thread trimming mechanism, FIG. 5 is a sectional view showing the main thread tension device, FIG. 6 is a sectional view showing the first auxiliary thread tension device, and FIG. 7 is a thread take-up spring. FIG. 8 is a partial front view showing the main thread tension device in a state where the thread tension pressure is released;
FIG. 9 is a flowchart showing the operation of this sewing machine. Sewing machine arm...2, needle...3, take-up body...11, thread feed lever...3
0. Figure 6 Figure 7 Occupation Chart N Ship Chart Occupation Figure 4 Figure 5 Figure 8 ○ Ship

Claims (1)

[Claims] 1 A needle 3 supported vertically movably on an arm 2 of the sewing machine, and the arm 2 located closer to the needle thread supply source than the needle 3
and a thread take-up mechanism 11 etc. provided on the arm 2 on the side closer to the upper thread supply source than the needle 3, and within several stitches from the start of the first thread supply operation of the thread take-up mechanism 11 etc. at the start of sewing. Needle thread pulling means 30, 34, etc. for pulling up the needle thread from the needle 3 side; and Needle thread pulling means 30, 34, etc. installed on the needle thread path between the thread take-up mechanism 11, etc. and the needle 3. A sewing machine characterized in that it is provided with resistance imparting means 53, 58, etc. for imparting resistance to the needle thread during operation.