JPS6119276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thread cutting device for a cycle stitch sewing machine that is driven by a starting operation and stops after forming a certain number of stitches. The present invention relates to a thread cutting device in which a thread cutting cam that rotates in conjunction with a thread cutting mechanism such as a thread cutting knife disposed in a sewing machine bed cuts sewing thread in conjunction with each other.

Conventionally, this type of thread cutting device has been publicly known in Japanese Patent Application Laid-open No. 48-82952 filed by the present applicant, but the device shown in the embodiment can move in one direction and move in the other direction. The pressing body, which is fixed to the control lever that transmits and interrupts the rotation of the driving body to the main shaft by the return movement, releases the thread cutting cam and the thread cutting mechanism by moving the control lever that interlocks the driving body and the main shaft in one direction. By cutting off the interlock and disabling the operation of the thread cutting mechanism while the sewing machine is running, the movement of the control lever that interlocks the driving body and the main shaft is returned to interlock with the thread cutting cam and the thread cutting mechanism to prevent inertial rotation of the main shaft after the sewing machine is cut off. Since the sewing thread is cut by the phase change of the rotating thread cutting cam, there is no problem as long as the inertial rotational force of the main shaft after cutting is sufficient to operate the thread cutting mechanism. There is a drawback that if the inertial rotation of the main shaft stops before the mechanism completes its operation, the sewing thread cannot be cut. In particular, the inertial rotational force of the main shaft is proportional to the rotational speed of the main shaft when interlocking with the prime mover, so in order to prevent the above drawbacks, it is necessary to use thread trimming cams depending on when sewing at high speeds and when sewing at low speeds. It was necessary to adjust the operating timing of the thread cutting mechanism.

This invention is capable of cutting the sewing thread reliably even when the rotational speed of the sewing machine is changed by interlocking the thread cutting cam and the thread cutting mechanism before cutting off the interlocking movement between the driving body and the main shaft. The purpose is to obtain a mechanism.

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

In the head of the sewing machine 1, the main shaft 2 is rotatably supported so that its rear end protrudes from the rear end face of the sewing machine frame, and the protruding part has a recess 3a formed in a part of its outer periphery. A disc-shaped thread trimming cam 3 and a disc-shaped cut-off cam 4 having a locking step 4a formed on a part of the outer periphery are fixed, and a pulley 5 is rotatable with respect to the main shaft 2 behind the cam 3. At the same time, a clutch mechanism 6 is arranged between the pulley 5 and the main shaft 2 to transmit the rotation of the pulley 5 to the main shaft 2 as is or at a reduced speed, or to interrupt the transmission. Table (not shown)
A belt 7 is stretched between the pulley of a drive motor (not shown) fixedly arranged on the lower surface of the drive motor so that the pulley 6 rotates on the main shaft 2 by the drive of the drive motor. At the lower rear end surface of the sewing machine frame, a pressing part 8a extending downwardly and an arc-shaped long hole 8 are formed at the upper end, and a lever part 8a extending laterally and a supporting part are formed at the lower end. A fitting hole 8e (first, second
The operating lever 8 is provided with a locking piece 9a facing the outer circumferential surface of the operating lever 4 at its upper end, and a fitting pin 9b that fits into the elongated hole 8b of the operating lever 8 at its base. The lever 9 is rotatably supported by a step screw 10 around an axis parallel to the main shaft 2, and one end of the leaf spring 11 is attached to the support piece 8d, and the other end presses the back surface of the shutoff lever 9 to shut it off. The lever 9 is fixed so as to apply a clockwise elastic force. Although not shown, a locking piece 9a of the cutoff lever 9 is located between the cutoff lever 9 and the clutch mechanism 6, as shown in FIG.
The rotation transmission of the pulley 5 to the main shaft 2 is cut off at the sewing machine locking position where the locking piece 9a is fitted into the locking step 4a, as shown in B and c in FIG.
The cutoff lever 9 is rotated counterclockwise so that the cutoff lever 9 is located between the position where it engages with the outer peripheral surface of the cutoff cam 4 (state C) and the position where it is slightly separated (state shown by the solid line B), and the sewing machine drive position is reached. , the rotation of the pulley 5 is decelerated and transmitted to the main shaft 2, and further, at B in FIG.
As shown by the two-dot chain line, the locking piece 9a blocking cam 4
In the sewing machine drive position where the cutoff lever 9 is rotated counterclockwise so as to move further away from the outer circumferential surface of ). As shown in Fig. 1, a feed shaft 12 is supported rotatably around an axis orthogonal to the main shaft 2 at the rising part of the machine frame that connects the sewing machine head and the base. A feed cam 13 is fixed, which is interlocked with the main shaft 2 so as to rotate at a reduced speed, and has one end protruding from the right side of the rising portion and has an annular guide groove A (only the front side shown) on the front and rear surfaces. A cutoff lever 9 is placed on a part of the outer periphery of the central portion at a position where the clutch mechanism 6 is controlled via the control mechanism so that the interlock between the main shaft 2 and the pulley 5 is cut off, that is, state A in FIG. Recessed portion 14a as a regulating release mechanism
and recesses 14b, 1 on both sides of the recess 14a for regulating the cutoff lever 9 to the state shown by the solid line B in FIG.
A control cam 14 having a disk shape as an outer diameter and forming part of a locking mechanism that restricts the cutoff lever 9 to the state shown by the two-dot chain line in B in FIG. 4 by its outer peripheral surface. to be fixed. Further, at the lower right side of the rising portion, a stepped screw 15 allows the intermediate portion of a transmission lever 16, which constitutes a part of the L-shaped locking mechanism, to be rotated about an axis parallel to the feed shaft 12. The lever 16 is always supported by applying an elastic acting force (not shown) in a counterclockwise direction, and an engagement pin 1 that engages with the outer peripheral surface of the control cam 14 is provided at one end of the lever 16.
7 is fixedly arranged, and the other end is fitted into the fitting hole 8d provided in the lever portion 8b of the operating lever 8,
The lever portion 8b and a foot pedal (not shown) arranged below the sewing machine table are connected by a chain 18 as a starting mechanism. On the other hand, a sliding plate 19 is slidably disposed on the upper surface of the sewing machine bed, and a presser arm 20 whose tip extends below the sewing machine chin is disposed at the center of the upper surface.
A support plate 22 in which a needle drop hole (not shown) of No. 1 is formed.
to be fixed. Between this sliding plate 19 and the guide groove A on the front and rear surfaces of the feed cam 13, the rotation of the feed cam 13 causes the sliding plate 19 to move in the front-rear direction, left-right direction, or in the left-right direction. A suitable interlocking mechanism (not shown) is installed for sliding in the composite direction.

A supporting frame 23 is fixed to the distal end surface of the presser arm 20, and the lower end of each supporting frame 23 is bent at a right angle to sandwich the workpiece between it and the supporting plate 22. Two presser plates 24 and 25 having a pressing portion and needle drop holes 24c and 25a formed in the pressing portions corresponding to the needle drop holes of the support plate 22 are supported so as to be movable up and down.

On both sides of the tip of the presser arm 20, the tip passes through a through hole (not shown) formed in the rear end surface of the support frame 23, and the presser plates 24, 25 are connected to each other.
The intermediate portions of the rotating bodies 26 and 27 fitted into fitting grooves (not shown) formed in the shaft 28 are rotatable by the shaft 28, and an elastic acting force (not shown) is always applied in a counterclockwise direction about the axis. Due to this acting force, the holding plates 24 and 25 receive a downward force, and the pressing portions at the lower ends of the holding plates 24 and 25 are pressed against the upper surface of the supporting plate 22.
On the other hand, a presser arm 2 is provided between the rear ends of the rotating bodies 26 and 27.
A pressure shaft 29 is arranged to cross above the sewing machine head, and a pressure shaft 29 is formed in the lower end surface of the sewing machine head in connection with depressing or releasing a presser foot lifting pedal (not shown) located below the sewing machine table. An elevating plate 30 that can be moved up and down through a hole (not shown) is disposed above the pressing shaft 29 so as to intersect with it. As shown in FIGS. 2 and 4, on the rear end surface of the sewing machine frame, arm A is located on the right side of thread trimming cam 3, and arm B is located on the right side of thread trimming cam 3. A step screw 3 is inserted between the thread cutting cam 3 and the pressing portion 8a of the operating lever 8 so that the intermediate portion thereof is located between the thread cutting cam 3 and the pressing portion 8a of the operating lever 8.
The arm A is provided with an engagement pin 33 that engages with the outer peripheral surface of the thread trimming cam 3, and the arm B is provided with an engagement pin 33 that is actuated by the pressing portion 8a of the operating lever 8. A dowel pin 34 is provided. On the other hand, as shown in FIG. 2, the arm C has the upper end of a vertical interlocking rod 35 rotatably interlocked, and the lower end of the interlocking rod 35 is connected to the lower end of the sewing machine frame by a step screw 36. L-shaped connecting link 37 rotatably supported
Rotatably connected to one end of. Further, a fixed knife 39 is fixed to the lower surface of the throat plate 38 fixedly disposed on the upper surface of the tip of the sewing machine bed near the needle hole (not shown), and a knife 39 for cutting the sewing thread is fixed to the fixed knife 39 in cooperation with the fixed knife 39. The moving knife 40 is rotatably supported at its other end under the throat plate so that the female part at one end horizontally crosses the path of the needle, and one end of the connecting link 41 is rotatably supported at the middle part of the moving knife 40. The other end is rotatably connected to one end of a rotary link 42 whose intermediate portion is rotatably supported on the lower surface of the throat plate, and the other end of the rotary link 42 and the other end of the connecting link 37 are rotatably connected. The ends are connected by a connecting rod 43. Further, a spring hanging piece 44 is fixed at an appropriate position on the rear end surface of the sewing machine frame, and a coil spring 45 is hung between it and one end of the connecting link 37, which always applies a counterclockwise force to the connecting link 37. . Due to the acting force of the connecting link 37, the oscillator 31 is always subjected to an acting force in a counterclockwise direction around the step screw 32 via the connecting rod 35.

The present invention has the above configuration, and its operation will be explained next. When the sewing machine 1 is stopped, the engagement pin 17 of the transmission lever 16 is fitted into the recess 14a of the control cam 14, as shown in A of FIGS. The locking piece 9a is in the locking position where it is fitted into the locking step 4a of the cut-off cam 4, and the swinging body 31 is in the locking position due to the action of the coil spring 45.
is pressed against the outer peripheral surface of the thread trimming cam 3. First, when the lifting plate 30 is lowered by operating the presser foot lifting pedal, the pressing shaft 29 is pushed down by its lower edge, and the rotating bodies 26 and 27 are rotated clockwise around the axis of the shaft 28. The holding plates 24 and 25 are raised, and the respective lower end pressing portions are raised from the support plate 22.

When the material to be sewn is inserted between this pressing portion and the support plate 22 and the operation of the presser foot lifting pedal is released, the presser plates 24 and 25 are lowered by the elastic acting force of the rotating bodies 26 and 27. The material to be sewn is held between the support plate 22 and the support plate 22. So, if you press the foot pedal,
The operating lever 8 is rotated counterclockwise in FIGS. 2 and 4 about the axis of the step screw 10 via the chain 18, and the transmission lever 6 is thereby rotated against the counterclockwise elastic force. 1, the engagement pin 17 comes out of the recess 14a of the control cam 14, and at the same time, as shown in B of FIG. The engaging pin 34 provided on arm B is pushed up and the oscillating body 31 is rotated clockwise around the step screw 32 against the action of the coil spring 45, and the locking pin 33 provided on arm A is rotated clockwise around the step screw 32. At the same time, the right edge of the elongated hole 8b of the operation 8 presses the fitting pin 9b of the cutoff lever 9 in a circular manner, and the cutoff lever 9 resists the action of the leaf spring 11. The stepped screw 10 is rotated counterclockwise about its axis to reach the drive position. Due to the rotation of the cutoff lever 9, the locking piece 9a comes out of the locking step 4a of the cutoff cam, and at the same time, the rotation of the pulley 5, which is idling on the main shaft 2 in conjunction with the driving motor, is decelerated and the main shaft 2 At the same time, the feed shaft 12 also rotates at a reduced speed with respect to the rotation of the main shaft 2, and the feed cam 13 and rotating cam 14 rotate in the direction of the arrow in FIG. 3. If the foot pedal is released when the concave portion 14b of the control cam 14 comes to a position facing the engagement pin 17 of the transmission lever 16, the counterclockwise elastic force of the control cam 14 will cause the engagement pin to 17 is recess 1
4b is maintained in the pressed state, and the operating lever 8 is locked in the locking position by the other end of the transmission lever 16, and the cutoff lever 9 is maintained in the drive position. Therefore, as shown in FIG. 3B, when the control cam 14 further rotates, the engagement pin 17 of the transmission lever 16 is pushed outward by the outer peripheral surface of the control cam 14, and the transmission lever 16 is further rotated clockwise. The operation lever 8 is further rotated counterclockwise by the other end, and the cutoff lever 9 is also further rotated counterclockwise through the fitting pin 9b by the elongated hole 8b, and the locking piece 9a is rotated. moves to the position indicated by the two-dot chain line B in FIG. 4, and the rotation of the pulley 5 is directly transmitted to the main shaft 2, so that the sewing machine 1 is driven at high speed. While the sewing machine 1 is driving, the sliding plate 1 is moved by the feed cam 13.
9 slides in a predetermined direction on the sewing machine bed, and the needle drops one after another into predetermined positions on the work piece held between the presser plates 24, 25 and the support plate 22, thereby forming stitches.

Then, just before the control cam 14 completes one rotation, the engagement pin 17 of the transmission lever 16 is connected to the control cam 1.
4 into the recess 14a from the outer periphery of the transmission lever 1.
6 rotates slightly counterclockwise around the step screw 15 due to the elastic acting force, and the operating lever 8 returns to rotate clockwise. When the pressure is slightly released, the cutoff lever 9 also rotates back clockwise under the action of the leaf spring 11 so that its locking piece 9a moves from the two-dot chain line position B in FIG. 4 to the solid line position, and the pulley 5 is decelerated and transmitted to the main shaft 2. After the main shaft 2 rotates, the third
As shown in C in the figure, the engagement pin 17 of the transmission lever 16 fits into the recess 14a of the control cam 14, and the transmission lever 16 further rotates counterclockwise and returns, thereby causing the operation lever 8 to further rotate clockwise. As shown in FIG. When the rotation returns, the engagement pin 33 of the arm A comes into pressure contact with the outer peripheral surface of the thread trimming cam 3, and when the operating lever 8 returns, the long hole 8b
The pressing of the engagement pin 9b of the cutoff lever 9 is completely released, but the locking piece 9a does not return to the position where it comes into pressure contact with the outer peripheral surface of the cutoff cam 4 and cuts off the interlocking movement between the main shaft 2 and the pulley 5. remains blocked.

When the main shaft 2 further rotates counterclockwise from the state shown in FIG. , first the engagement pin 33
is recessed into the recess 3a by the action of the coil spring 45, and the rocking body 31 rotates counterclockwise around the step screw 32. As a result, the movable knife 40 shown in FIG. 2 is rotated from the lower surface of the fixed knife 39 to the upper and lower suture thread engaging positions via the connecting rod 43, the rotating link 42, and the connecting link 41.

As the rotation of the main shaft 2 further progresses, the engagement pin 33 recessed into the recess 3a of the thread trimming cam 3 is pushed up from the recess 3a, thereby causing the oscillator 31 to rotate clockwise in the opposite direction to the above, and each connection The movable knife 40 captures one of the upper thread loops and the bobbin thread that go around the hook in its hook part, moves back to the lower surface of the fixed knife 39, and cooperates with the fixed knife 39 to thread the upper and lower threads. Cut the sewing thread.

Almost at the same time as the cutting of the sewing thread by the movable knife 40 is completed, the locking piece 9a of the cutoff lever 9 fits into the locking step 4a of the cutoff cam 4 as shown in FIG. It rotates clockwise from the state shown in FIG. 4 and reaches the stop position shown in FIG. 4, thereby cutting off the interlock between the pulley 5 and the main shaft 2.
As shown in FIG. 4A, the locking step 4 is attached to the upper end of the locking piece 9a.
a is engaged and the main shaft 2 is stopped at a position where the needle is approximately at the top dead center.

In the above embodiment, when the movable knife 40 is driven by the interlocking movement of the thread trimming cam 3 and the movable knife 40, the pulley 5 and the main shaft 2 are in an interlocking state. The interlock between the pulley 5 and the main shaft 2 may be cut off during or immediately before driving. In other words, the moving scalpel 40
Even if the interlock between the pulley 5 and the main shaft 2 is cut off during the drive of The movable scalpel 40 may be driven at a time when the amount is large. Also,
In the above, the cutoff lever 9 and the cutoff lever 8 are formed separately, and during the starting operation, both levers move in one direction to cut off the interlocking movement between the thread trimming cam 3 and the movable knife 40, and the main shaft 2 and the pulley 5, and after forming a predetermined number of stitches, the operation lever 8 is first set to the unlocking position, and the thread trimming cam 3 and the movable knife 40 are operated in conjunction with each other.
After bringing the two into an interlocking state, the interlocking operation between the main shaft 2 and the pulley 5 is cut off by setting the cutoff lever 9 to the stop position. However, as shown in FIG. The pressing body 50 as an operation lever shown in the publication is fixedly arranged on the cutoff lever 9 and driven, that is, the cutoff lever 9 is rotated counterclockwise to interlock the pulley and the main shaft. When in position, the pressing body 5
0 pushes up the engagement pin 34 of the arm B of the swinging body 31 and separates the engagement pin 33 of the arm A from the outer peripheral surface of the thread trimming cam 3 so as to interrupt the interlock between the thread trimming cam 3 and the moving knife 40. 5), and after the predetermined number of stitches have been formed, the cutoff lever 9 rotates back slightly clockwise and its locking piece 9a engages with the outer peripheral surface of the cutoff cam 4 (at this time, the pulley (The rotation is transmitted to the main shaft in a decelerated state), and the pushing up of the engaging pin 34 of the rocking body 31 by the pressing body 50 is released, and the thread cutting cam 3
Alternatively, the movable knife 40 may be interlocked, and then the locking piece 9a may be fitted into the locking step 4a of the cutoff cam 4 to interrupt the interlocking movement between the main shaft and the pulley. In this case, as shown in FIG. 6, instead of fixing the pressing body 50 as an operating lever to the cutoff lever 9, the pressing body 50 is rotatably arranged on the rear end surface of the sewing machine frame, and this pressing body 50 and the cutoff lever 9 may be connected by a link 51 to transmit the movement of the cutoff lever 9 to the pressing body 50.

Further, in the embodiment described above, the cutoff lever 9 and the operating lever 8 are arranged in the predetermined interlocking relationship by the fitting pin 9b and the elongated hole 8b, respectively, and after the starting operation, the outer circumferential surface of the control cam 14 is operated via the transmission lever 16. The operating lever 8 is locked in the locking position, the cutoff lever 9 is locked in the drive position rotated counterclockwise, and after a predetermined number of stitches have been formed, the locking is released and the thread trimming cam 3 and The operating lever 8 returns to the unlocking position so that the movable knife 40 is interlocked, and the cutoff lever 9 is maintained in the drive position where the main shaft and pulley are linked by the cutoff cam 4, and then returns to its movable position to release the main shaft and pulley. As shown in FIG. 7, an actuation lever 52 is fixedly arranged on the cutoff lever 9 and connected to a foot pedal (not shown) by a chain 53. 52
Two hooks 54 forming part of the locking mechanism
a and 54b are disposed, and a transmission lever 55 constituting a part of the locking mechanism is rotatably disposed between the hook body 54 and the feed cam 13. One end is formed with a claw 55a that engages and disengages the hook of the hook body 54, and the other end is an engaging portion that engages with two protrusions 56 and 57 as a release mechanism arranged on the outer peripheral surface of the feed cam 13. 55b, and when the cutoff lever 9 is rotated counterclockwise via the operating lever 52 to the driving position by the starting operation, the pawl 55a of the transmission lever 55 engages with one hook 54a of the hook body 54. to lock the cutoff lever 9 at the drive position shown by the solid line in Figure B, and block the interlocking movement of the thread trimming cam 3 and the moving knife by the pressing body 50 fixedly arranged on the cutoff lever 9. After forming a predetermined number of stitches, the above One protrusion 56 of the feed cam 13 engages with the engaging portion 55b of the transmission lever 55, momentarily rotating the transmission lever 55 counterclockwise, and this rotation causes the pawl 55a to engage the hook 54a.
and then hook the cutoff lever 9 to another hook 54b.
Lock it in the position where it has returned slightly clockwise (B
position) and rotate the pulley on main axis 2
In addition, this slight return movement of the cutoff lever 9 causes the pressing body 50 to be transmitted in a decelerated state.
The locking of the rocking body 31 by the thread cutting cam 3 is released.
After that, the next protrusion 57 engages with the engaging portion 55b of the transmission lever 55, and the claw 55a
may be disengaged from the hook 54b of the hook body 54, and the cutoff lever 9 further rotates back to the stop position, thereby cutting off the interlocking movement between the main shaft and the pulley. In this case, the cutoff lever 9 and the pressing body 50
If these are formed as separate bodies, as shown in FIG. 8, a hook mechanism A is provided between the cutoff lever 9, the pressing body 50, and the feed cam 13, each of which constitutes a part of the locking mechanism. , B, and the projection 58 as a release mechanism arranged on the outer peripheral surface of the feed cam 13 first releases the pressing body 5 as an operating lever.
0 may be returned to the lock release position, and then the cutoff lever 9 may be returned to the stop position.

Furthermore, in the above embodiment, the cutoff lever 9, which is rotatably arranged around an axis parallel to the main shaft 2, transmits and controls the cutoff of the rotation of the pulley 5 via the clutch mechanism 6 by rotational operation. For example, as shown in Japanese Patent Publication No. 39-12725, the belt is moved from the main shaft through the belt shifter by rotating a cutoff lever that can be rotated about an axis perpendicular to the main shaft. The present invention may be implemented in a sewing machine in which the main shaft and the driving body are interlocked and disconnected by appropriately changing the high-speed pulley, low-speed pulley, and idling pulley arranged in the main shaft. That is, as shown in FIGS. 9 and 10, an idle pulley 62, a low-speed pulley 63, and a high-speed pulley are arranged on the main shaft 60 and have an intermediate portion rotatably supported on a shaft 61 perpendicular to the main shaft 60 on the rear end surface of the sewing machine. A cam lever 68 has a long hole 68a formed at one end and a notch 68b formed in the middle part above its rotational fulcrum. The other end of the cam lever 68 is rotatably supported, and one end of the cam lever 68 is rotatably and laterally movably supported on the side surface of the rear end of the sewing machine frame by a step screw 69 passing through the elongated hole 68a. A hook body 70 having two hooks 70a and 70b constituting a part of the locking mechanism is arranged below the dynamic fulcrum. A part of a locking mechanism is formed between this hook body 70 and a feed cam 71 arranged on the side surface of the sewing machine frame. The middle part of the transmission lever 72 is rotatably supported on the side of the machine frame by a step screw 73, and a pawl 72a is formed at one end of the transmission lever 72 to engage and disengage from the hook of the hook body 70, and the other end is provided with a claw 72a for engaging and disengaging from the hook of the hook body 70. An engaging portion 72b that engages with two protrusions 74 and 75 forming a release mechanism arranged on the outer peripheral surface of the cam 71 is formed. In addition, a thread trimming cam 76 is fixed to the main shaft 60, and a swinging body 77 having three arms A, B, and C formed on the rear end surface of the sewing machine frame is attached so that the arm A is on the right side of the thread trimming cam 76 (see Fig. 10). ), and the arm B protrudes from the side of the machine frame and is rotatably supported at its intermediate part by a step screw 78 so as to cross the upper end of the cam lever 68, and the arm A has an outer peripheral surface of the thread trimming cam 76. The arm C is rotatably connected to the upper end of a connecting rod 80, which is always given an upward elastic force by a coil spring, as shown in the above embodiment, and the oscillating body 77 is always a step screw 78
Receives a counterclockwise acting force centered on . First, when the cutoff lever 67 is rotated clockwise to the driving position, the belt 65 is passed through the belt shifter 66 and passed from the idle pulley 62 to the low speed pulley 63 and the high speed pulley 64 in order, and the main shaft 60 is driven. As the stitches are formed, the feed cam 71 rotates at a reduced speed. Also, the pawl 72a of the transmission lever 72 engages with one hook 70a of the hook body 70, and the cutoff lever 67 is moved to the drive position 4 (solid line shown in FIG. 9).
The arm B of the swinging body 77 is rotated clockwise by the upper edge of the cam lever 68, and the engagement pin 79 of the arm A is separated from the outer peripheral surface of the thread trimming cam 76 to remove the thread. A cutting cam 76 and a moving knife (not shown).
For the configuration from the connecting rod 80 to the moving scalpel, please refer to the previous embodiment. ) will be cut off. Therefore, when a predetermined number of stitches are formed, the feed cam 7
One protrusion 74 of the transmission lever 72
2b, the transmission lever 72 is instantaneously rotated counterclockwise, and the claw 72a is switched from the hook 70a to another hook 70b, and the cutoff lever 67 is slightly returned to the counterclockwise position. Locking (9th
(dotted chain line position in the figure), the belt shifter 66 transfers the belt 65 from the high speed pulley 64 to the low speed pulley 63 to decelerate the rotation of the main shaft 60, and
The cam lever 68 moves to the left and the notch 68
b moves to a position facing arm B of oscillating body 77, and as a result, oscillating body 77 is rotated counterclockwise by the upward acting force of connecting rod 80, and engagement pin 79 of arm A is moved to a position opposite to arm B of oscillating body 77. The thread cutting cam 76 is brought into pressure contact with the outer circumferential surface of the thread cutting cam 76, and the moving knife is interlocked with the thread cutting cam 76. Then, after a certain period of time, the next protrusion 75 engages with the engaging portion 72b of the transmission lever 72, the pawl 72a separates from the hook 70b, and the cutoff lever 67 returns to rotation in the counterclockwise direction (the ninth
The belt shifter 66 transfers the belt 65 from the low-speed pulley 63 to the idling pulley 62 to cut off the interlock between the driving body and the main shaft 60.
During this time, the moving knife is driven by the thread cutting cam 76 to cut the sewing thread.

As described above, the present invention locks the starting mechanism in the driving position to start the sewing machine, and also cuts off the interlocking between the thread trimming mechanism and the thread trimming cam, so that the last needle after forming a predetermined number of stitches of the sewing machine is First, move the operation lever to the lock release position to interlock the thread trimming cam and thread trimming mechanism, then move the cutoff lever to the stop position,
Since the main shaft is configured to stop at a fixed position after the upper and lower threads are cut by the thread trimming mechanism, the rotation transmission from the driving body to the main shaft is cut off by moving the cutoff lever to the inactive position, and the thread trimming cam cutting means is removed. The cutting means can be operated when the rotational inertia of the main shaft is large when the cutting means cuts the sewing thread using the thread trimming cam.
For this reason, before or during thread cutting by the cutting means,
To prevent an accident in which the main spindle stops before reaching a predetermined stop position and cannot cut the thread, to ensure cutting of the sewing thread, and to accurately stop the main spindle at a predetermined stop position.

[Brief explanation of the drawing]

Fig. 1 is an overall perspective view of the cycle sewing machine, Fig. 2 is a perspective view of the thread trimming mechanism, and Fig. 3 is a front view of the control cam, and each figure shows the relationship between the control cam and the transmission lever during one cycle sewing. shows. FIG. 4 is a front view of the thread trimming cam mechanism section and the cutoff mechanism section as seen from the rear end of the sewing machine, and each figure shows the operating state at a time corresponding to each figure in FIG. 3. 5 to 10 show other embodiments, and FIGS. 5, 6 and 7,
B in FIG. 8 corresponds to FIG. 7 and 8A and FIG. 9 are side views of the rear end of the sewing machine, and FIG. 10 is a sectional view taken along the line -' in FIG. 9. In the figure, 2 is the main shaft, 3 is the thread trimming cam, 8.50.
68 is an operating lever as an operating means, 9.67 is a cutoff lever, 18 is a chain as a starting means, 13.
71 is a feed cam as a control cam, the control lever 14 and transmission lever 16 in FIG. 1, the hook body 54 and transmission lever 55 in FIG. 7, and the hook mechanism in FIG. 8.
AB and hook body 70 and transmission lever 7 in Fig. 9
2 are respective embodiments of the locking means, the control cam 14 in FIG. 1 and the protrusion 5 in FIG.
6, 57 and projections 58 in FIG. 8 and projections 74, 75 in FIG. 9 are respective examples of release mechanisms.

Claims (1)

[Scope of Claims] 1. A cutoff lever 9, 67 which is rotatable between a drive position where the rotation of the driving body is transmitted to the main shaft to drive the sewing machine and a stop position where the transmission is cut off and the main shaft is stopped at a fixed position. , thread trimming cams 3 and 76 forming cam portions fixed to the main shaft, and a rocking body 3 capable of engaging and disengaging from the thread trimming cam 3.
1, 77, a thread trimming mechanism that cuts the thread in conjunction with the oscillating body, moves to a locking position where the thread trimming cam and the oscillating body are disengaged from each other, and a locking release position where they are engaged. Operation levers 8, 50, 68, cutoff levers 9, 67, and operation levers 8, 50, 6
8, and by moving in one direction, the cutoff levers 9, 67 are rotated to the driving position to drive the sewing machine, and the operating levers 8, 50, 68 are set to the locking position, and the thread trimming cam 30 and the swinging body are connected to each other. 31, and the operation levers 8 and 5 to set the cutoff lever 9 to the drive position.
0 and 68 at the locking positions to keep the sewing machine in a driving state and keep the thread trimming cam and the swinging body in a disengaged state; A control cam that controls the number of stitches, and a thread trimming cam that, in conjunction with the control cam, releases the lock at the locking position of the operating lever by the locking mechanism at the final stitch of the sewing machine after forming a predetermined number of stitches. a release mechanism that engages the swinging body and then releases the locking of the cutoff lever at the driving position to set the stop position to cut off rotation transmission from the driving body to the main shaft and stop the sewing machine at a fixed position. Thread cutting device for sewing machine.