JPS6158200B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a feed dog which can be moved in four directions so as to protrude and retract from the feed dog hole of the throat plate and feed the fabric to be sewn in a predetermined direction in cooperation with the presser foot. In order to do this, the material to be sewn is always kept submerged from the feed dog hole so that it can be freely fed by the operator's hand.
The present invention relates to a sewing machine equipped with a so-called drop feed mechanism and a thread cutting mechanism that moves along a predetermined path below the throat plate so as to cut sewing thread.

In a sewing machine equipped with the drop feed mechanism of the feed dog mentioned above, when installing a thread cutting mechanism that moves along the horizontal plane between the throat plate and the hook to catch and cut the stitching thread, the feed dog may be depressed. In this state, the feed dog comes to be located within the path of the moving knife of the thread cutting mechanism or in contact with the path, and as a result, the moving knife and the feed dog collide with each other due to the movement of the moving knife and are damaged. This poses a danger and is a problem when installing a thread cutting mechanism in the sewing machine.

In this invention, when the feed dog is in the sunken state,
The purpose of this invention is to solve the above problem by retracting the feed dog out of the movement path of the thread cutting mechanism when the thread cutting mechanism is activated.

Embodiments of the present invention will be described below with reference to the drawings. As shown in Figures 1 and 2, a driving shaft 1 that is linked to a driving motor (not shown) is rotatably supported in the center of the sewing machine bed, and the front end surface is attached to the tip of the driving shaft 1 to form a cam surface. A thread trimming cam 2 and a chainstitch cam 3 are installed at the rear end, and a horizontal feed cam 4 is installed at the rear end.
are respectively fixedly arranged, and in the intermediate part, a vertical feed cam 5 having a track groove 5a formed on the outer periphery is arranged so as to be able to slide in the axial direction and rotate together with the driving shaft 1, and in front of it (on the left side in Figs. ), a cylindrical body 6 whose outer diameter is the same as or slightly larger than the lower part of the vertical feed cam 5 is fixedly arranged, and a driving shaft 1 and a rotating shaft 7 rotatably arranged parallel to the driving shaft 1 Spur gears 8 and 9 (FIG. 2) which are fixed to each other are used to interlock the rotary shaft 7 so that one rotation of the driving shaft 1 rotates the rotating shaft 7 twice. At the tip of the bed part, a rotary hook shaft 11 is provided with a well-known fully rotary hook 10 on which a bobbin wound with thread can be attached and detached at the front end, and is rotatable about an axis horizontally orthogonal to the axis of the rotating shaft 7. The rear end of this hook shaft 11 and the rotating shaft 7
bevel gears 12 and 13 having the same number of teeth at the tips of the
is fixed and interlocked so that one rotation of the rotary shaft 7 causes the hook shaft 11 to rotate once, so that when the drive shaft 1 rotates once, the hook shaft 11 rotates twice.

As shown in FIG. 5, a transmission body 1 is provided with an engaging pin 14a at one end at the intermediate portion of the rotating shaft 7.
The other end of 4 is connected to the cylindrical body 6 whose lower surface of one end is disposed on the driving shaft 1 (A, D, E in FIG. 7).
It is loosely supported so as to face the outer circumferential surface of the vertical feed cam 5 shown in FIG. One end of a swinging link 16 is swingably supported on this support shaft 15, and the other end of the swinging link 16 extending upward is provided with the transmission body 14 on the lower surface of one end. The other end of the rocking plate 17, which has an engaging portion 17a that engages with the engaging pin 14a, is swingable about an axis parallel to the support shaft 15, and the engaging portion 17a is connected to the transmission body 1 by the coil spring 18.
The upper surface of the rocking plate 17 has a needle plate 19a that protrudes from and retracts from the throat plate 19a arranged at the seam portion of the sewing machine bed surface and extends laterally along the feed dog hole. A feed dog 20 that is movable in a direction (horizontal direction in FIG. 5) is fixedly arranged. In the middle part of the swing link 16, the other end of the fork link 21, which has a fork part for holding the horizontal feed cam 4 at one end, is supported so as to be swingable about an axis parallel to the support shaft 15. A guide pin 22 is fixed to the middle part of the forked link 21, and a roller 24 is disposed at the tip thereof to loosely fit into a guide groove 23a of a well-known guide box 23 appropriately arranged in the bed part. As is well known, this guide box 23 regulates the swinging of the two-pronged link 21 caused by the rotation of the horizontal feed cam 4 according to the angle of the guide groove 23a, and allows the swinging link 16 to be centered around the axis of the support shaft 15. The angle of the guide groove 23a, that is, the amount of swing of the swing link 16 can be changed as appropriate by adjusting means (not shown) appropriately arranged on the sewing machine frame. As can be seen from these configurations, the rotation of the driving shaft 1 rotates the horizontal feed cam 4 and the vertical feed cam 5, and the rotation of the horizontal feed cam 4 causes vibrations generated via the forked link 21 and the guide box 23. The swinging of the moving link 16 causes the feed dog 20 to swing in the horizontal direction, and the swinging of the swing plate 17 generated via the transmission body 14 due to the rotation of the vertical feed cam 5 causes the feed dog to swing. 20 is vertically oscillated, and by combining these horizontal and vertical oscillations, the feed dog 20 makes a so-called four-movement and presses the presser foot (not shown) at the lower end of the presser rod disposed on the sewing machine arm. (No) to send the fabric to be sewn.
In front of the driving shaft 1 and below the hook 10, a control shaft 25 is arranged so as to be swingable about a horizontal axis parallel to the driving shaft 1, and at its front end (left end),
A driven portion 26a facing the outer circumferential cam surface of the chainstitch cam 3
The oscillating body 26 formed with a oscillating body 26 is supported in a oscillating manner, and an upright piece 27 is fixedly arranged opposite to the inner end surface of the base of the oscillating body 26.
Both bent portions of the control body 28, which is bent into a U-shape and has an engaging portion 28a extending upward, are loosely fitted and supported, and the vertical feed cam 5 is inserted between the bent portions on both sides. Forked portion 2 that loosely fits into the track groove 5a of
The primary conversion body 29 forming 9a is also loosely supported,
A coil spring 30 is connected to the control shaft 25 between the right end surface of the switching body 29 and the inner end surface of the right bent portion of the control body 28.
is interposed in a state surrounding the control body 28 to apply an elastic force so that the switching body 29 is always pressed against the inner end surface of the left bent portion, and the receiving piece 31 is fixed to the left side of the left bent portion of the control body 28. A coil spring 32 is also interposed between the receiving piece 31 and the outer end surface of the left bent portion in a state surrounding the control shaft 25 to apply an elastic force to the control body 28 to the right. Further, on the right side of the control body 28, it is bent into a U-shape, and the tip of the bent portion on the right side is extended to form a guide hole 33a, and a support piece 33b that extends horizontally above the control shaft 25 is formed. The bent portions on both sides of the movable body 33 are loosely fitted and supported on the control shaft 25, and on the control shaft 25 between the bent portions on both sides,
The regulating pin 34 is fixedly arranged so as to project upward, and an engagement pin 35 projecting upward is also fixedly arranged on the support piece 33b. Further, a downwardly protruding branch piece 36 is fixedly arranged at the rear end (right end) of the control shaft 25, and a coil spring 37 is interposed between the tip of the branch piece 36 and an appropriate position on the bed section, so that the control shaft 25 for clockwise rotation as shown in FIG.
6, a guide pin 38 is fixedly arranged parallel to the control shaft 25 to guide the movable body 33 so that it can move in the axial direction while preventing its rotation. Above this movable body 33, an operating shaft 39 is rotatably supported around a horizontal axis perpendicular to the control shaft 25, and one end thereof has an engaging portion 28a of the control body 28.
fixes a cam 40 that engages with the rightward elastic force of the control body 28 by the coil spring 32, and fixes an operation dial 41 to the other end that can be operated by an operator. This operation dial 4
The control body 28 moves in the axial direction of the control shaft 25 in accordance with the change in the cam surface of the cam 40 due to the rotational operation of step 1, and the lower surface of the cam 40 and the engaging portion 28 move in the axial direction of the control shaft 25.
When the control body 28 moves to the right due to the engagement with the control body 28, as shown in FIG. As a result, the transmission body 14 engages only the outer peripheral surface of the cylindrical body 6, and the transmission body 14 escapes from the position facing the lower surface of the one end of the transmission body 14, and the transmission body 14 engages only the outer peripheral surface of the cylindrical body 6, and the transmission body 14
0 is a state in which the throat plate 19 is sunk from the feed dog hole 19a. In this state, even if the driving shaft 1 rotates, the swing plate 17 does not swing up and down, and the feed dog 2
0 is maintained in a depressed state. A support shaft 42 is fixedly arranged vertically at the tip of the bed, and a support piece 43a is formed in the middle of the support shaft 42 to face the front surface of the upper end of the swinging body 26. Notch 10 formed on the front surface of the upper end of the inner pot 10a
It rotatably supports the other end of the chain stitch looper 43, which has a locking portion 43b facing the front wall of b, and is provided with more elastic force than the coil spring 37 at appropriate positions within the chain stitch looper 43 and the bed section. A rotational force is applied to the chain stitch looper 43 in the direction in which its locking portion 43b joins the front wall of the notch 10b through the weak coil spring 44, and the support piece 43a
An adjusting screw 45 is screwed and supported so that its tip moves toward and away from the front surface of the rocking body 26, and the tip also moves toward and away from the front surface of the upright piece 27 disposed on the control shaft 25 at the base of the rocking body 26. An adjustment screw 46 is screwed and supported.

As described above, a rotational force is always applied to the control shaft 25 in the clockwise direction in FIG. to rotate the rocking body 26 clockwise, thereby rotating the rocking body 26 in the clockwise direction.
As shown by the solid line, the driven portion 26 a of the chain stitch cam 3 is located away from the outer circumferential cam surface of the chain stitch cam 3 , and the rotation of the swinging body 26 causes the chain stitch looper 43 to be moved by the action of the coil spring 44 via the adjustment screw 45 . in the opposite direction to the force (the elastic force of the coil spring 37 is
The locking portion 43b is rotated by the
is maintained at a position away from the front wall of the notch 10b of the inner hook 10a. However, when the control shaft 25 is kept rotating in the counterclockwise direction against the action force of the coil spring 37 due to the action of the switching lever (to be described later) (the state indicated by the chain double-dashed line), the adjustment screw 4 is rotated by the upright piece 27.
6 is released, and as a result, the coil spring 4
4, the chainstitch looper 43 is rotated in the direction in which the locking portion 43b joins the front wall of the notch 10b, and the swinging body 26 is rotated counterclockwise via the adjustment screw 45. The driven portion 26a comes to be pressed against the outer circumferential cam surface of the chain stitch cam 3 (the state indicated by the two-dot chain line).

When the driving shaft 1 is rotated in this state and the chainstitch cam 3 rotates, the swinging body 26 swings due to the change in the cam surface, and the chainstitch looper 43 also swings around the support shaft 42 following this. , the locking portion 43b is the notch 10
It comes into contact with and separates from the front wall of b. This notch 1
Locking portion 4 of chain stitch looper 43 to front wall of 0b
The contact and separation of 3b makes it possible to form a single thread chain stitch with the needle thread in a well-known manner. The support shaft 42
Below the chainstitch looper 43, one end of the switching link 47 is provided, which has an engaging pin 47a at the middle part facing the cam surface 2a of the thread trimming cam 2, and a passive pin 47b at the rear end protruding downward. The switching link 47 is rotatably supported, and a coil spring 73 is interposed at an appropriate position within the switching link 47 and the bed section so that the engaging pin 47a is connected to the switching link 47 in the direction in which it joins to the cam surface 2a of the thread cutting cam 2. Gives rotational power,
On the right side of this switching link 47 and in the horizontal plane between the lower surface of the throat plate 19 and the upper end of the hook 10, the other end of the movable knife 48, which is formed in an L shape and has a thread catch hook 48a formed at one end thereof, is vertically moved. The switching link 47 is rotatably supported by a shaft 49, and the extension part 48b provided at the other end is connected to the switching link 47 by a connecting link 50. A fixed knife 51 is arranged to cooperate with the movable knife 48 to cut the stitching thread. At the rear of the thread trimming cam 2, the upper end engages and disengages the driven pin 47b arranged at the rear end of the switching link 47 to connect the engagement pin 47a to the cam surface 2a of the thread trimming cam 2 or to control it to the detached position. cam part 5 of
2a and a guide pin 52b arranged at the lower end is rotatably supported by a vertical support shaft 53, and a movable plate 54 is moved in the axial direction of the driving shaft 1 from below to the rear end of the bed part. a forked portion 5 disposed so as to be movable substantially in parallel, and into which the guide pin 52b of the intermediate body 52 is fitted to the tip of the movable plate 54;
4a, and a control pin 54b is fixedly arranged on the upper surface near the rear end so as to protrude upward. In a support frame (not shown) connecting the rear end of the bed section and the rear end of the arm section, the intermediate section of the connecting link 55 extending up and down is rotatably supported by a horizontal shaft 56, and the The switching link 47 is rotated in the clockwise direction (the first
The rotating force shown in Fig.) is applied to the lower end of the actuating piece 58.
is fixed, and slightly above it, the rear end of the moving plate 54 is rotatably connected, and a switch 59 related to the driving motor is disposed close to the operating piece 58. In addition, a rotating shaft 60 is rotatably supported within the jaw of the sewing machine arm with one end thereof protruding outward from the machine frame of the arm, and an operation for rotating the rotating shaft 60 is provided at the protruding end by the operator. The lever 61 is fixed, and the engagement piece 62 is fixed to the other end located inside the arm. In front of this rotation shaft 60, an L-shaped rotation link 63 is arranged so as to be rotatable about a horizontal axis, and one end of the rotation link 63 has an engagement pin that engages with the engagement piece 62. 64 is fixed, and the other end and the upper end of the connecting link 55 are connected by a connecting rod 65.

A needle 66, which moves up and down in the jaw via a well-known interlocking mechanism (not shown) by the rotation of the driving shaft 1 and is supported at its lower end, cooperates with the hook 10 in the bed to stitch the stitches. A needle bar 67 is arranged. In addition, at the rear end of the bed,
An L-shaped switching lever 68 is vertically aligned with one end facing the front end surface of the regulating pin 34 arranged on the control shaft 25 and the other end facing the rear end surface of the control pin 54b arranged on the moving plate 54. The switching lever 68 can be rotated via a connecting link 70 by an operating mechanism (not shown) appropriately arranged on the sewing machine frame.

Further, below the switching lever 68, a transmission lever 71 has one end facing the rear end surface of the engagement pin 35 disposed on the support piece 33b of the movable body 33, and the other end facing the control pin 54b of the movable plate 54. The intermediate portion thereof is arranged so as to be rotatable by a vertical shaft 72 facing the rear end surface. Although not shown, a well-known thread take-up mechanism is disposed in the sewing machine arm for picking up and releasing the needle thread in time with the formation of a stitch between the hook 10 and the needle 66.

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

When the operating lever 61 is in the inoperative position shown in FIG. 1, the connecting link 55 receives a clockwise rotational force from the coil spring 57, and this rotational force causes the movable plate 54 to move to the left in FIGS. 1, 2, and 6. It is receiving an acting force in the direction.

Due to the acting force of this moving plate 54, the guide pin 52
The intermediate body 52 receives the rotational force in the counterclockwise direction in FIGS. 2 and 6 through the intermediate body 52, and the cam portion 52a at the upper end of the intermediate body 52 presses the driven pin 47b of the switching link 47 outward, and the coil spring 73 of the switching link 47 (because the elastic force of the coil spring 57 is stronger than that of the coil spring 73), the engagement pin 47a rotates counterclockwise around the support shaft 42, thereby causing the engagement pin 47a to move away from the cam surface 2a of the thread trimming cam 2. They are maintained at separate positions (the solid line state in FIG. 2, the two-dot chain line state in FIG. 6). Therefore, when the operation lever 61 is rotated clockwise with the needle bar 67 stopped at its top dead center (by a well-known fixed position stop mechanism) after the sewing machine has finished sewing, the locking piece 62 is attached to the rotation link 63. The engaging pin 64 is pressed to rotate the rotating link 63 counterclockwise (FIG. 1), and as a result, the connecting link 55 is rotated counterclockwise through the connecting rod 65 against the action of the coil spring 57. , and the moving plate 54 is moved to the right. This movement of the moving plate 54 causes the intermediate body 52 to rotate clockwise via the guide pin 52b, and the pressing of the driven pin 47b of the switching link 47 by the cam portion 52a is released, and the switching link 47 is moved by the coil spring 7.
3, the engagement pin 47a comes into pressure contact with the cam surface 2a of the thread trimming cam 2 (solid line state in FIG. 6). Then, by further rotating the operating lever 61 clockwise, the connecting link 55 is rotated counterclockwise, and the actuating piece 5 is rotated.
8 actuates the switch 59, which causes the driving shaft 1 to
The driving motor is operated for one rotation, and one rotation of the driving shaft 1 drives the needle bar 67 from its top dead center for one cycle, and when the needle 66 rises from its bottom dead center in that cycle, it is engaged. Matching pin 47
The switching link 47 follows the change in the cam surface of the thread trimming cam 2 through the action of the coil spring 73 via the coil spring 73, and is first rotated clockwise and then counterclockwise. Due to the rotation of the switching link 47, the movable knife 48 is moved to the shaft 4 via the connecting link 50.
9, and during the reciprocation, the thread catching hook 48a enters the needle thread loop that is wrapped around the inner hook 10a of the hook 10, as is well known, and by the backward movement, the thread catching hook 48a enters the needle thread loop that is wrapped around the inner hook 10a of the hook 10. The bobbin threads of the bobbin held in the bobbin 10a are captured and returned to the original position, and upon the return, the bobbin threads are cut in cooperation with the fixed knife 51. When the rotational operation of the operating lever 61 is released after the thread is cut, the connecting link 55 is released from the coil spring 57.
Due to the action of , the operating lever 61 is rotated clockwise and returned to the inoperative position shown in FIG.
Switching link 4 via moving plate 54 and intermediate body 52
7 is rotated counterclockwise against the coil spring 73 so that its engagement pin 47a engages the cam surface 2 of the thread trimming cam 2.
is maintained at a distance from a. Therefore, the related operation between the thread cutting mechanism and the chain stitching mechanism will be explained. As described above, the connecting link 7 is operated by an operating mechanism (not shown) appropriately arranged on the sewing machine frame.
When the switching lever 68 is rotated clockwise in FIG.
As a result, as described above, the oscillating body 26 is rotated counterclockwise by the action of the coil spring 44, and the driven portion 26a is pressed against the outer circumferential cam surface of the chainstitch cam 3. I come to do it.
When the sewing machine is driven in this state, that is, when the driving shaft 1 rotates, the chain stitch looper 43 is swung following the change in the cam surface of the chain stitch cam 3, and its locking portion 4
3b comes into contact with and separate from the front wall of the notch 10b provided in the pot 10a. Due to the connection of this locking portion 43b, the needle thread loop that is caught by the hook tip and then passed around the inner hook 10a and pulled upward from the notch 10b by the action of the thread take-up is moved in front of the needle drop point in the cloth feeding direction. is locked by the locking part 43b on the side,
In this state, when the needle 66 falls into the needle thread loop due to the next needle drop, the locking part 43b is moved to the notch 10b.
is separated from the front wall of the needle thread to release the locking of the needle thread loop, and by repeating this action, a single thread chainstitch is formed by the needle thread. Further, the switching lever 68 is moved to the second position via the connecting link 70 by the operating mechanism.
When the control pin 34 is rotated counterclockwise in the figure, the pressure on the regulating pin 34 is released and the control shaft 25 is rotated clockwise in FIG. 3 by the action of the coil spring 37. The locking portion 43b is maintained at a position away from the notch 10b of the inner hook 10a (the position indicated by the solid line in FIG. 4), that is, the locking portion 43b is maintained at an inoperative position. In this state, if the bobbin wound with thread is set in the inner hook 10a and the sewing machine is driven, a final stitch is formed by knotting the needle thread and the bobbin thread. Therefore, when this chain stitch looper 43 is in an inoperative state, that is, when forming a regular stitch, the thread cutting mechanism is activated and the movable plate 54 is moved to the right (first and second
When the control pin 54b is moved to the position shown in FIG. 6, the control pin 54b engages with the other end of the switching lever 68 and rotates clockwise, thereby setting the chain stitch looper 43 into the operating state. Then, the needle thread loop that has passed around the inner hook 10a due to one cycle of stitch formation during the operation of the thread trimming mechanism is locked by joining the chain stitch looper 43 to the front wall of the notch 10b, With this, the catching hook 48a of the movable knife 48 catches the needle thread and bobbin thread between the needle plate 19 and the shuttle hook 10 with the needle thread loop tensioned, and the original position is the cutting point away from the catching point. Since the needle thread returns to its original position (FIG. 8), the needle thread is fed out from its source through the needle hole of the needle 66. Next, the related action between the thread cutting mechanism and the feed dog raising/lowering mechanism will be explained. As described above, when the lower surface of the cam 40 is made to face the engaging portion 28a of the control body 28 by rotating the operation dial, the control body 28 moves to the right on the control shaft 25 together with the switching body 29 due to the action of the coil spring 32. As the switching body 29 moves, the vertical feed cam 5 is also moved to the right on the driving shaft 1 and comes to escape from the position facing the lower surface of one end of the transmission body 14. Due to the action of the coil spring 18, the transmission body 14 engages only the outer circumferential surface of the cylindrical shaft 6, and the feed dog 20 sinks from the feed dog 19a of the throat plate 19, and is moved into the moving path of the moving knife 48 or into the thread cutting mechanism. maintained in its vicinity. Even if the sewing machine is driven in this state, the feed dog 20 does not feed the fabric to be sewn, and the operator can freely feed the fabric by hand, making it possible to perform, for example, stitching. Therefore, when the thread cutting mechanism is activated and the movable plate 54 moves to the right (Figs. 1 and 2), the control pin 54b engages with the other end of the transmission lever 71 and rotates the lever 71 clockwise. , one end of the transmission lever 71 presses the engagement pin 35 disposed on the branch piece 33b of the movable body 33 to the left, and as a result,
The movable body 33 is moved to the left on the control shaft 25, and as the movable body 33 moves, its left bent portion presses the right bent portion of the control body 28, and the control body 28 resists the action of the coil spring 32. move to the left. Due to this movement of the control body 28, the switching body 29 also moves to the left together with the vertical feed cam 5, but at the beginning of the operation of this thread cutting mechanism, the high surface of the vertical feed cam 5 is in the upper position, so the switching body 29 moves vertically. The left end surface of the feed cam 5 contacts and locks the right end surface of the transmission body 14, and therefore the movement of the switching body 29 is locked, and from then on, only the control body 28 is moved to the left. , the coil spring 30 is compressed between the right end surface of the switching body 29 and the inner end surface of the right bent portion of the control body 28 (FIG. 7C). Then, during one cycle of stitch formation by the operation of the thread cutting mechanism, the needle 66
When the lower surface of the vertical feed cam 5 reaches the upper position due to the rotation of the driving shaft 1 in time with the descent of the vertical feed cam 5,
Since the lower surface and the outer circumferential surface of the cylindrical body 6 almost match, the repulsion of the coil spring 30 causes the switching body to
9, the vertical feed cam 5 enters the lower surface of one end of the transmission body 14 (Fig. 7D), and when the needle 66 rises from the bottom dead center, the high surface position of the vertical feed cam 5 returns to the upper position. and raises the feed dog 20 via the transmission body 14 and the oscillating body 17, thereby raising the feed dog 20.
0 out of the path of the moving knife 48 that enters between the throat plate 19 and the hook 10 (Fig. E in Fig. 7),
Collision between the moving knife 48 and the feed dog 20 is prevented.

As described above, the present invention includes a thread cutting mechanism that is movable below the throat plate to cut the stitching thread, an operating mechanism that is movable and associated with the operator so that the thread cutting mechanism is moved by the operation, and a sewing machine. The operating state in which the sewing machine protrudes and retracts from the feed dog hole of the throat plate disposed in the sewing machine bed during operation to intermittently feed the workpiece in cooperation with the presser foot, and the moving path of the thread cutting mechanism that retracts from the feed dog hole. a feed dog that can be switched to and maintained in an inoperative state in which the feed dog is located within and does not operate;
In a sewing machine equipped with a switching mechanism capable of switching the feed dog between an operating state and a non-operating state and maintaining the switching mechanism, when the feed dog is in an inactive state, the thread cutting mechanism is moved or the feed dog is switched in relation to the operation of the operating mechanism. By retracting the thread cutting mechanism to a position within the movement path of the thread cutting mechanism, for example, collision between the moving knife of the thread cutting mechanism and the feed dog can be reliably prevented.
To prolong the life of the sewing machine by preventing damage to these parts, and to prevent unexpected serious injuries to workers caused by broken parts flying off due to collision between the moving knife and the feed dog. It has advantages such as excellent safety.

In addition, in the above embodiment, when the thread cutting mechanism is activated, the feed dog is moved out of the path of the moving knife by interlocking the feed dog with the upper and lower feed cams, but the thread cutting mechanism The feed dog may be moved out of the path of the thread cutting mechanism by directly raising or lowering the feed dog in connection with the operation of the thread cutting mechanism. Even if the operating means is operated, the same effect as in the above embodiment can be obtained.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the sewing machine mechanism mainly consisting of the bed, Figure 2 is a plan view of the bed, Figure 3 is a sectional view taken along the -' line in Figure 1, and Figure 4 shows the hook and chain stitch. FIG. 5 is a cross-sectional view taken along line -' in FIG. 2, FIG. 6 is a plan view showing only the thread cutting mechanism, and FIG. 7 is a front view showing the elevating mechanism of the feed dog. Each figure shows the sequence of related actions between the lifting mechanism and the thread cutting mechanism. FIG. 8 is a partial perspective view of the hook portion. {2...Thread trimming cam, 47...Switching link, 48
...Moving knife, 50...Connecting link, 51...Fixed knife} Thread cutting mechanism. {52...intermediate, 53...
Support shaft, 54... Moving plate, 55... Connecting link, 6
0... Rotation shaft, 61... Operation lever, 62... Engagement piece, 63... Rotation link, 64... Engagement pin,
65...Connecting rod} Operating mechanism. {5...Vertical feed cam, 6...Cylindrical body, 14...Transmission body} Feed dog operating cam mechanism. {16... Swing link, 17... Swing plate, 18... Coil spring, 20... Feed dog} Feed dog mechanism. {28...control body, 29...switching body, 3
2...Coil spring, 40...Cam} switching mechanism.
{33... moving body, 35... engaging pin, 71...
Transmission lever｝Safety mechanism.

Claims (1)

[Scope of Claims] 1. Thread cutting mechanism 2, 47, in which a movable scalpel moves forward against elastic force below the throat plate and back by elastic force so as to capture and cut needle thread and bobbin thread. 48,5
0,51, and the driving motor is driven so that the cam 2 fixed to the driving shaft 1 rotates once in relation to the movement in the opposite direction, which resists the elastic force caused by manual operation when it is always subjected to an elastic force in one direction. The operating mechanisms 52 to 55, 60 to 65 have a thread trimming mechanism in contact with the cam, a cylindrical body fixed to the driving shaft as a concentric circle with the driving shaft, and a high portion having a radius larger than the outer diameter of the cylindrical body. A feed dog operating cam mechanism 6, 5, 14 consisting of a vertical feed cam that has a lower part with a diameter and is slidable in the axial direction of the driving shaft; one end is connected to the swing link 16, and the other end is Feed dog mechanisms 16, 17, 1 which are in pressure contact with the feed dog operating cam mechanism by elastic force and support the feed dog upwards.
8 and 20, the upper and lower feed cams are always moved in one direction away from the feed dog mechanism by elastic force to maintain the feed dog mechanism in an inactive state, and manually moved in the opposite direction against the elastic force. switching mechanisms 40, 28, 29, and 32 that move to connect the vertical feed cam to the feed dog mechanism and put the feed dog mechanism into an operating state; and a switching mechanism that moves the switching mechanism in the opposite direction in conjunction with manual operation of the operating mechanism. , safety mechanisms 71, 35, 33 arranged in association with an operating mechanism and a switching mechanism for connecting the vertical feed cam to the feed dog mechanism and lifting the inactive feed dog mechanism out of the moving path of the moving knife; A sewing machine equipped with