JPS584595A - Needle yarn cutter of sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention opens the movable blade of the thread cutting means in conjunction with the movement of the presser foot, and swings the thread cutting shaft via a cam linked to manual operation of the operating lever. , the thread cutting means is advanced to the needle thread cutting position with the movable blade open, and then the movable blade is closed and the needle thread running from the needle to the cloth is clamped between the presser plate 51 and the lower part thereof is moved. Regarding a needle thread cutting device of a sewing machine that cuts the needle thread in cooperation with a fixed force and moves to a backward/retracted position while holding the cut end of the needle thread connected to the needle, the above-mentioned operation that activates the thread cutting means in particular. The purpose is to make lever operation easier.

In this type of thread cutting device, for example, as described in Japanese Utility Model Publication No. 55-40141, after the needle thread is cut by a thread cutting means in conjunction with the operation of an operating lever, the presser foot is raised and the presser foot is raised. Following this, the thread cutting means rises to allow the rise of the presser foot, and at the same time, the thread cutting means is moved from the cutting position to the retracted position outside the vertical path of the needle as described above so as not to hit the needle during this rise. When the lever is moved and the operating lever is released, the elastic force of the return spring acting on the operating lever causes the presser foot and the thread cutting means to return to their original positions while operating in a direct order opposite to the above action. . In order to produce this action, an "elastic force" is always acting on the thread trimming shaft that pushes the thread cutting means to the retreat position, and a cam facing the following arm fixed to the thread trimming shaft is used. When the operating lever is operated, the thread cutting means is moved to the thread cutting position at the higher part of the cam against the elastic force, and then returned to the retreat position by the elastic force at the lower part, and when the operating lever is released, the cam is moved. It is configured to return to its original state by removing the follower arm against the above-mentioned "elastic force". When the thread cutting means moves to the thread cutting position, the movable blade is brought into contact with the closing part of the engaging body provided on the presser foot to close the movable blade, and during sewing, the engaging body is released by moving the presser foot 2. The movable blade is opened by engaging the movable blade with the pin of the movable blade and pushing it from the retracted position to the thread cutting position. However, when the movable blade is closed, the presser plate is in pressure contact with the upper surface of the movable blade, so the "elastic force" that acts on the thread cutting shaft to open the movable blade at the open part of the engaging body due to the movement of the presser foot is It is strong enough to overcome the frictional force between the movable blade and the presser plate and maintain the thread cutting means in the retracted position.

Therefore, the return spring that acts on the operating lever so that when the operating lever is released, the cam eliminates the follower arm at the high position and returns, has a strong elastic force that overcomes the above-mentioned "elastic force".
As a result, conventional sewing machines of this type have disadvantages in that the operating lever is difficult to operate, resulting in poor operability and significant operator fatigue.

The present invention solves the above-mentioned conventional drawbacks by providing a blocking means that acts to prevent the thread cutting means from moving to the thread cutting position when the movable blade is engaged with the engaging body related to the movement of the presser foot. It is something to do.

Embodiments of the present invention will be described below with reference to the drawings.

The sewing machine of this embodiment is a known buttonhole edge overstitch sewing machine as described in Japanese Patent Application No. 51-20993. That is, as shown in FIG.
When the drive pulley 84 rotates counterclockwise around the center, the drive pulley 84, which is constantly rotating in conjunction with a motor (not shown), connects to the driven pulley 85 fixed to the main shaft (not shown) via the forked arm 86. At the same time as the pressure is applied, the stop portion 87 is disengaged from the driven pulley 85 and the sewing machine starts. - Also, when the sewing machine is started, the presser foot 33 moves back and forth along a straight line, and the needle 66 swings in a direction perpendicular to the moving direction of the presser foot every time it moves up and down.
In addition, the swing base line of the needle 66 changes in conjunction with the forward and backward movement of the presser foot 33, and after forming a predetermined number of stitches, the needle 66 is removed from the fabric and stops in the upward state, and immediately before stopping, the needle 66 moves upward from the fabric. A knife (not shown) falls between the rows of stitches and acts to cut out the buttonhole.

A thread cutting shaft 5 is arranged parallel to the axial direction of an upper shaft (not shown) in the arm 4 below the arm 4 which is connected to the ped 1 and forms the body part 2 and the jaw part 3. A bearing body 8 is rotatably supported around a support shaft 7 perpendicular to the thread cutting shaft 5 on a support body 6 fixed to the thread cutting shaft 5. Fits loosely and freely. The tip of the thread cutting shaft 5 is loosely fitted into a longitudinally long hole 10 of a receiving body 9 fixed to the jaw part 3, and a locking pawl 11 is formed at the lower end of the base of the thread cutting shaft 5 protruding from the bearing body 8. A rotating arm (following arm) 130 has a roller 12 parallel to the axis of the thread cutting shaft in the center.
Fix the base. Furthermore, as shown in FIG. 1.2, the thread cutting shaft 5 is always protected from an axial force acting to the right by a weak spring 15 compressed and placed between the end surface of the bearing body 8 and the end surface of the rotating arm 13. As shown in Fig. 3, a lower thread trimming lever 17 whose upper end is rotatable on the trunk 2 by a stepped screw 16 is always moved clockwise by a weak spring 19 provided between the upper spring hook 18 and the rotating arm 13. It receives the rotational force of. As shown in Figure 3, the trunk 2
There is a chain 2o connected to a foot pedal (not shown) at the tip.
The base of the approximately L-shaped operating lever 21 connected to the lever 21 is rotatable by a stepped screw 22, and is provided so that the upper end surface thereof hits the bottom of the stepped screw 16 and stops under the constant force acting clockwise by a spring 28. . Further, a roller 14 having a spherical outer periphery is provided at the protruding end of the operating lever 2I toward the base end of the thread cutting shaft 5 so as to be rotatable about a substantially perpendicular shaft. The left end of the cam body 26 is rotatably connected to the bobbin thread trimming lever 7 by a step screw 24, and the right end thereof has a cam portion 25 that is pressed against the roller 12 of the rotating arm 13 by the force of a spring 19. The section is rotatably supported by a step 27.

As shown in FIGS. 1 and 4, on the flat lower surface of the support plate 67 fixed to the side surface of the arm 4 near the body 2, a vertical shaft part perpendicular to the axis of the thread cutting shaft 5 is attached to the base end of the swinging body 69. Step screw with 7
It is movably supported by 0. As shown in FIGS. 2 and 4, the swinging body 69 has a free end extending between the base end of the thread cutting shaft 5 and the roller 14 of the operating lever 21, and has a slope 71 on the end surface corresponding to the roller I4. The oscillator 69 is constantly rotated clockwise around the stepped screw 7o in FIG. The rollers 14 are provided so as to come into pressure contact with the surface on which the rollers 72 are formed.

The bent feed arm 29 shown in FIG. 1 has its base rotatably rotated by a shaft 3I in a direction perpendicular to the axial direction of the upper shaft with respect to a movable body 30 that moves as desired left and right in conjunction with a sewing machine mechanism. A support plate that supports a presser foot 33, the tip of which extends below the jaw 3 and has a hole 32 formed therein, which is located at the sewing machine seam portion of the upper surface of the bed 1 and surrounds the buttonhole edge and the seam. 34 and the member 3 fixed to the lower end of the presser bar 35
A raising plate 39 having a long groove 38 on the left and right into which a shaft 37 protruding from the thread cutting shaft 5 in a direction perpendicular to the thread cutting shaft is loosely fitted thereinto is fixed thereto. A groove 40 having a cross section It-shaped is formed, and a rotatably provided guide roller 41 is brought into contact with the tip of the shaft 37 of the member 36 from above the groove 40, and the downward pressure of the presser bar 35 is applied to the groove 40. It acts on the presser foot 33 via the rollers 41 and the grooves 40. Furthermore, a pair of closed portions 42 and open portions 43 are formed on the lower surface of the distal end of the feed arm 29 and have surfaces that intersect with the axial direction of the upper shaft (the moving direction of the presser foot 33) and that face each other. The engaging body 44 is fixed.

At the tip of the thread cutting shaft 5, as shown in FIGS. 1 and 2, there is a support arm 45 whose free end extends laterally from above the feed arm 29, bends downward, and extends behind the tip of the feed arm 29. The base of the supporting arm 45 is fixed, and a member 36 as shown in FIG.
A retaining piece 47 that fits loosely into an arcuate guide groove 46 formed in the
form.

Further, a support body 49 having a flat surface 48 is fixed to the end surface of the distal end of the support arm 45, and a fixed blade 5 is attached to the upper surface of the flat surface 48.
0 is provided, and a presser plate (
The pressing members) 51 are provided so as to overlap each other, and the closing portion 42 of the engaging member 44 is provided between the fixed blade 5o and the pressing plate 51.
A movable blade 54 is provided with a pin 52 that can engage with the open portion 43 and is rotatable by a stepped screw 53 to produce a cutting action between the fixed blade 5o and the tip of the fixed blade 5o.

A support body 58 that rotatably supports the engaging and disengaging body 55 by a shaft 57 is fixed to the movable body 30, and the engaging and disengaging body 55 has first and fourth supports.
As shown in the figure, a locking portion 59 facing the locking pawl 11 at the lower end of the rotating arm 13 and bent diagonally upward, and a flat portion 6 facing downward at the tip of a pressing plate 60 whose base is fixed to the bobbin thread trimming lever 17
1 and the stop piece 62 is reshaped, so that the stop piece 62 of the engaging and disengaging body 55 and the supporting body are always connected by the acting force of the compression spring 63 between the upper surface of the support body 58 and the lower surface of the engaging and disengaging body 55. 58
A rotational force is applied in a counterclockwise direction about the shaft 57 in FIG.

A ring 64 is provided at the center of the cam body 26 at the portion connected to the operating lever 21, and one end of the ring 64 is connected to a wire 65 that raises the presser bar 35 by indexing it downward through an appropriate mechanism. Also, the lower part of the ring 64 and the cam body 2
6, a gap is created between the lower part of the outer circumference of the lower thread cutter lever 17 and the lower part of the outer circumference of the lower thread cutter lever 17 when the operation lever 21 is released and its upper end surface is in pressure contact with the lower surface of the upper base of the bobbin thread cutter lever 17, as shown by the solid line in FIG. Configure it like this.

As shown in FIGS. 1 and 12, on the side surface of the feed arm 29, there is a low portion 74b and a high portion 7 that are continuous on the upper surface via a slope 74a.
4c is rotatably supported by a shaft 75 parallel to the support shaft 7, and this push-up body 74 is always given rotational force in the counterclockwise direction in FIG. 1 by a coiled spring 76. 1) Lower part 7 with one end pressed against stopper 77-
4b and the high portion 74C are provided so as to be substantially horizontal. On the other hand, the proximal end of the contactor 78 is fixed to the thread cutting shaft 5, and the free end thereof is arranged within the movement path of the high portion 74C of the push-up body 74. In addition, the above-mentioned high part 7 with respect to the contactor 78
4C, when the free end of the contact 78 rides on the high part 74C due to the movement of the feed arm 29, the roller 12 of the rotating arm 13 moves against the cam of the cam body 26 as shown in FIG. The thread cutting shaft 5 is provided so as to be maintained at a position rotated clockwise in the figure until it engages with the portion 25.

As shown in FIG. 3, there is a clutch lever 82 and a clutch lever 82 on the back of the sewing machine via a link 88 so as to prevent the sewing machine from being started by the chain 80 when the lever 21 is indexed downward. The connecting safety lever 89 and the rotation links 90 and 91 are respectively connected to the shafts, 92. q3. '94
The rotating link 90 has an upper end connected to a safety lever 89 via a link 95 and a lower end connected to an operating frame 96 via a coil spring 97. A pin 98 provided at the upper end is configured to engage with the right side of a long hole 99 formed in the operating frame 96.

Further, an L-shaped stopper 100 is supported on a support arm 45 hanging from the thread cutting shaft so as to be movable and lockable in the left and right directions in FIG. ' When the clutch lever 82 is rotated counterclockwise and the sewing machine is operated, the rotation link 90 is tilted as shown by the two-dot chain line, and the operating frame 9
6 to the right, the pivot link 91 is pivoted clockwise via the coil spring 97, and the pin 10.1 at its lower end is provided so as to press the right side surface of the stopper 100 to the left.

The present invention has the above configuration, and its operation will be explained next.

Figure 1.2.4 shows a state in which the sewing machine has completed one cycle of buttonhole edge stitching, the needle 66 has stopped near the top dead center, and the operating lever 21 is not operated. The movable blade 54 is open, and the upper end surface of the operating lever 21 is stopped in contact with the base of the bobbin thread cutting lever 17 as shown by the solid line in FIG. 4 due to the action of the spring 28.
As shown in FIG. 3, the rotating arm (following arm) 13 has its roller I2 pressed against the end surface of the cam body 26 by the acting force of the spring 19 to maintain the thread cutting shaft 5 at a constant rotating position, and also to cut the thread. The proximal end of the shaft 5 applies a clockwise pressing force to the oscillating body 69 in FIG. Pressure contact is made at the position shown in FIG. 2 which is lower than the portion 72. Also rotating arm 1
3. The locking claw 11 at the lower end of the stopper 6
2 is stopped in contact with one end surface of the support body 58.
It is located to the left of the locking portion 59 of No. 5. Further, as shown in FIG. 2, in the needle thread cutting unit (thread cutting means) supported by the thread cutting shaft 5 via the support arm 45, the pin 52 of the movable blade 54 is connected to the opening part 43 of the engagement bar 44. The fixed blade 50 and the movable blade 54 are rotated clockwise around the step screw 53, and the tips of the fixed blade 50 and the movable blade 54 are opened, and the tips of these blades retreat from the vertical movement path of the needle 66 diagonally to the upper right in FIG. position (retracted position).

From this state, when the operating lever 21 at the solid line position in FIG. 4 is operated in one direction via the chain 20 using a foot pedal or the like to the position indicated by the chain line in FIG. The parts in FIG. 4 move as shown in FIG. 5, and the needle thread cutting unit in FIG. 2 moves as shown in FIG. The cutting body advances during the vertical movement path of the needle 66 and the movable blade 54
rotates to cut the needle thread with the fixed blade 50, and the movable blade 5
4 and the presser plate 51 to hold the cut end on the needle side.

That is, due to the rotation of the operating lever 21, the step screw 27 at the center of the cam body 26 in FIG.
The lower part of the cam part 25 pushes the roller 12 to the right and rotates the thread cutting shaft 5 counterclockwise about its axis via the rotating arm 13. arm 13
The locking pawl 11 at the lower end pushes the locking part 59 of the locking/disengaging body 55 and gets over it, and the arm tensioning action of the cam body 26 rotates the bobbin thread cutting lever 17 clockwise around the step screw 16, and the pressing plate The tip 60 is located close to the upper surface of the flat portion 61 of the engaging/disengaging body 55. Due to the rotation of the operating lever 21, the roller 14 shown in FIG. 2 pushes the slope 71 of the rocking body 69 and
As a result, the oscillating body 69 rotates counterclockwise about the step screw 70, and moves the thread cutting shaft 5 to the left in the axial direction against the spring 5. By rotating the thread cutting shaft 5 counterclockwise about its axis and moving it to the left in the axial direction, the needle thread cutting body shown in FIG. 2 moves downward and to the left (cutting position). (To be more precise, it is a diagonal arc movement) Its tip moves forward in the vertical movement path of the needle 66, and the pin 52 hits the closing part 42, and the movable blade 54 rotates counterclockwise around the step screw 53, and presses down. After the needle thread is clamped between the lower surface of the plate 51 and the needle thread is clamped and cut in cooperation with the fixed blade 50, each part is
It will be in the state shown in Figure 6.

Next, when the operating lever 21 shown by the chain line in FIG. 4 is further operated in one direction to the position shown by the two-dot chain line, the operating lever 21 further rotates counterclockwise, whereby each part in FIG. 5.6 moves to the seventh and eighth positions, respectively. Moving as shown in the figure, the needle thread cutting unit in the forward position retreats from the vertical movement path of the needle 66 and rises together with the presser foot 33.

That is, as the operating lever 21 is rotated, the cam body 26 shown in FIG. The tip of the spring 60 connects the flat part 61 of the engagement/disengagement plate 55 to the spring 63
is pushed against L7, and the locking/disengaging plate 55 is rotated clockwise about the shaft 57 to move the upper end of the locking portion 59 downward from the rotation path of the lower end of the locking claw 11 of the rotating arm 13. For this reason, rotating arm 1
3 is the rotation in the clockwise direction because it is not inhibited】2
is in contact with the cam portion 25 of the cam body 26 and rotates the thread cutting shaft 5 clockwise about its axis by the action force of the spring 19, and the locking pawl 11 is positioned to the left of the locking portion 59. . Further, due to the rotation of the operating lever 21, the roller 14 rides over the top of the protrusion 72 of the oscillating body 69 shown in FIG. Since the thread cutting shaft 5 rotates clockwise around the center, the thread cutting shaft 5 moves slightly to the right in its axial direction. By rotating the thread cutting shaft 5 clockwise about its axis and moving it to the right in the axial direction, the needle thread cutting unit shown in FIG. 6 moves to the left and to the right. Their tips are retracted from the vertical movement path of the needle 66;
In this position, the bead 52 of the movable blade 54 is connected to the open part 43.
Since the movable blade 54 and the F^1 constant blade constant force are not pushed, the tips of the movable blade 54 and the F^1 constant blade constant force are closed, and each part is in the state shown in FIGS. 7 and 8.

Furthermore, when the operating lever 21 is rotated, the ring 64
, the wire 65 is pulled downward and the presser bar 35 is raised, whereby the part 36 is raised and the shaft 37 and the hole 38 of the raising plate 39 are raised.
The feed arm 29 is rotated clockwise in FIG. 1 about the shaft 31 at its base to raise the presser foot 33, and as the member 36 is raised, the engaging piece 47 is loosely fitted into the groove 46.
is lifted, the thread cutting shaft 5 shown in FIG. 1 rotates clockwise about the support shaft 7, and the needle thread cutting unit rises together with the presser foot.

Furthermore, when the operating lever 21 indicated by the two-dot chain line in FIG. As shown in FIG. 0, the needle thread cutting unit moves from the retreated position to the right forward position away from the vertical movement path of the needle 66, and the needle thread cutting unit and the presser foot descend.

That is, when the operation lever 21 is released, the operation lever 2], the cam body 26, the bobbin thread trimming lever 17, the swinging body 69, the thread trimming shaft 5, the feed arm 29, etc. are moved in the opposite direction from when the operation lever is operated. When the operation lever 21 shown in FIG. 7 is first restored to the position shown in FIG. The roller 12 is pushed to the right by the cam surface 25 of 26 against the spring 19, and the thread cutting shaft 5 is rotated counterclockwise around its axis via the rotating arm 13. The rotation of the moving body 69 in the counterclockwise direction causes the thread cutting shaft 5 to be moved by the spring 15.
1, the needle thread cutting unit in FIG. 8 advances to the needle vertical movement path (cutting position) as shown in FIG. As shown in FIG. 5, the locking pawl 11 is located to the right of the locking portion 59 of the locking and disengaging body 55 which has been restored to its original state after being pressed against the tip of the pressing plate 60 by rotation of the bobbin thread cutting lever. Further, when the operation lever 21 is restored, the presser bar 35 is lowered, and the cloth presser foot 33 is lowered, and the thread cutting shaft 5 is also rotated counterclockwise in FIG. descend.

Next, when the operation lever 21 in the state shown in FIG. 5 returns to the position O shown in FIG. 9 (solid line in FIG. Due to the force of the spring 19, the opening 12 tries to come into contact with the surface, but the locking claw 11 of the rotating arm 13 is stuck at the locking part of the locking and disengaging body 55 at a high position as shown in FIG. Section 59 I
F is thereby prevented from rotating the thread cutting shaft 5 to maintain the needle thread cutting unit in the forward position, and since the roller 14 of the thread cutting shaft 5 rides over the protrusion 72 of the rocking body 69, the spring 15 is Because the acting force causes the rocking body 69 to rotate clockwise around the step screw 70 in FIG. 2, it moves to the right in FIG. 1, and the needle thread cutting body is locked at the position shown in FIG. 10. , needle 66
The cutting action of the needle thread connected to the cloth is completed.

Next, from this state, after sewing the next stitching point, the thread 80 is pulled downward in FIG. is restrained in the retracted position, the movable blade 54 engages with the engaging body 44 and rotates clockwise against the frictional force with the presser plate 51 as shown in FIG. At the same time, the cut ends of the consecutive needle threads are released and preparations are made for the next needle thread cutting b. That is, the opening portion 43 of the engaging body 44 engages with the pin 52 of the movable blade 54 by the movement of the moving body 30 (feeding arm 29). When the contactor 78 climbs the slope 74a of the pressing body 74 and engages with the high portion 74C, the roller 12 is rotated clockwise in FIG.
Since it is pressed with a strong force, the thread cutting shaft 5 is prevented from rotating in the counterclockwise direction as shown in FIGS. 4 and 12. Also, at this time, the clutch lever 82 and the link mechanism 88°89.
The link 91 is rotated clockwise in FIG.
Since the thread cutting shaft 5 is pressed to the left in the figure by the strong force of the spring 97, the thread cutting shaft 5 is prevented from moving to the eleventh left. Therefore, after the opening part 43 engages with the pin 52, the feed arm 29 is further moved to the first position.
When the pin 52 moves to the left in Figure 0 and is pressed diagonally downward to the left in the figure, the force of the springs 15 and 19 acting on the thread cutting shaft 5 is weaker than the frictional force between the movable blade 54 and the presser plate 51. Since the thread cutting shaft 5 is maintained in the state shown in FIG. 4, the movable blade 54 is rotated clockwise about the shaft 53 in the retracted position as shown in FIG. Release the cut end of the needle thread on the needle side that was held between it and the open pass presser plate 51,
The parts shown in FIGS. 9 and 10 return to their original positions shown in FIGS. 2 and 4, respectively.

As described above, according to the present invention, the thread cutting means provided on the thread cutting shaft is rotated in one direction via the operating rail "-e" against the spring force that returns the thread cutting shaft. is moved from the retreat position to the cutting position, and during this movement, the movable blade is rotated closed in one direction by engagement with the closing part of the engaging body provided on the presser foot, and the needle thread is cut in cooperation with the fixed blade. At the same time, during the next operation of the sewing machine, when the presser foot moves, the movable blade is rotated in the opposite direction at the retracted position returned by the spring by engagement with the open part of the engaging body, and the tip of the movable blade is rotated in the opposite direction. In a needle thread cutting device that opens to release the cut end of the needle thread on the needle side from between it and the suppressing body, the thread is engaged when the engaging body and the movable blade engage with each other in conjunction with the movement of the presser foot. Since the structure is provided with a blocking means to prevent rotation of the cutting shaft, when the opening part of the engaging body engages with the movable blade to release the movable blade as in the conventional case, the thread cutting means There is no need to firmly restrain the thread trimming shaft against the force of the engaging body with its rotary spring so that it does not escape to the cutting position, and therefore the return spring force of the thread trimming shaft is used only to return the thread cutting shaft. If the needle is weakened to the necessary strength, the spring force that returns the operating lever in the opposite direction against this spring force will improve the operability of the weak needle thread cutting device and reduce operator fatigue.

^ It has the effect of reducing

In the embodiment of the present invention, the push-up body 74 is made of a single member, but the high part 74c'i is made of a separate member so that the vertical position and horizontal position of the high part can be adjusted. Chirii.

[Brief explanation of drawings]

Figure 1 is a front view of the main parts, Figure 2 is a plan view, Figure 3 is a rear view of the sewing machine, Figure 4 is a sectional view taken along line IV-IV of Figure 5, and Figure 5 is a cross-sectional view of the sewing machine.
The figure shows the state when the needle thread is cut at the same location as in FIG. 4, FIG. 6 shows the state of the needle thread cutting unit at the same time, and FIG. 7 shows the state when the presser foot is raised at the same location as in FIG. 4. Fig. 8 shows the state of the needle thread cutting unit at the same time as above, Fig. 9 shows the state of the same part as Fig. 4 when the presser foot is lowered, Fig. 10 shows the state of the thread cutting means at the same time as above, and Fig. 11 shows the state of the thread cutting unit at the same time as above. The state of the thread cutting means at the initial stage of starting the sewing machine, the first
FIG. 2 is a sectional view taken along the cutting line in FIG. 1. Name of agent Patent attorney Nagoya - Yusho 9 years old 6 Figure y t. Fang 8 Mouth Sai (Oki 1O Su11 Illustration Sai 1?, Ki

Claims (1)

[Scope of Claims] A thread cutting shaft 5 supported horizontally on the machine frame so as to be able to swing around its own central axis and a horizontal orthogonal axis 7 to the thread cutting shaft, and a free end whose base end is fixed to the thread cutting shaft. A support arm 45 is arranged to face the suture part, a fixed blade 50 is fixed to the free end of the support arm, and an edge facing the fixed blade overlaps the upper surface of the fixed blade so as to open and close, and is rotatable to the support arm. It consists of a movable blade 54 with a bottle 52 supported on the upper surface of the free end and a suppressor 51 whose base end is fixed to the support arm 12 and whose free end is pressed against the upper surface of the movable blade. A thread cutting means 4 capable of cutting the lower part of the clamping part by the cooperation of the movable blade and the fixed blade after the needle system is clamped between the movable blade and the suppressor by rotating in the direction, and fixed to the thread cutting shaft. - an elastic body 19 having an elastic force that always presses and rotates the thread cutting shaft in one direction around its own central axis; In the first stage operation, the thread cutting shaft is rotated in the other direction against the elastic body to move the thread cutting means to the cutting position of the needle lower force, and in the second stage operation, the thread cutting shaft is rotated in one direction by the elastic body. (9) An operating lever 21 provided with a cam 26 that acts on a follower arm to move the moving thread cutting means from the cutting position to a retracted position horizontally distant from the needle; a return spring 28 which has an elastic force to move and lock in a position away from the step operating position in the opposite direction of the operating direction; By engaging the movable blade with the presser foot 33 which can be raised by pushing up from below, the movable blade closes -C with respect to the fixed blade in connection with the movement of the thread cutting means from the retreat position to the thread cutting position. An engaging body is provided in the presser foot with a closing portion 42 that acts as if the presser foot moves, and an opening portion 43 that acts to open the movable blade with respect to the fixed blade in relation to the movement of the presser foot, facing the pin of the movable blade. 44
and blocking means 74, 78, 76, which are provided on the presser foot and the thread trimming shaft and engage with the movement of the presser foot to prevent rotation of the thread trimming shaft when the engaging body and the movable blade are engaged. A sewing machine needle thread cutting device equipped with □.