JPS6327036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a thread cutting device used in a sewing machine, which cuts sewing thread through cooperation between a fixed blade and a movable blade.

Prior Art In this type of conventional thread cutting device, for example, as shown in Japanese Patent Application Laid-Open No. 53-97545,
As a mechanism for making the movable blade perform cutting operations,
The cam rotates in conjunction with the sewing machine's drive mechanism,
Generally, the cam follower is engaged by the spring force of a spring, and the movement of the cam follower due to the cam action is transmitted to the movable blade. In this case, a spring with strong spring force is used to engage the cam follower with the cam surface so that the movable blade moves accurately according to the cam surface, so that the cam follower is strongly pressed against the cam surface. It becomes necessary to do so. Therefore, in the conventional thread cutting device, a problem arises in that a large load is applied to the drive mechanism of the sewing machine such as the sewing machine motor.

Purpose of the Invention An object of the present invention is to solve the problems in the prior art described above, to enable the cutting operation of the movable blade to be performed smoothly with a light load, and to ensure that the movable blade does not move freely during normal sewing. An object of the present invention is to provide a thread cutting device that can prevent thread cutting.

Composition of the Invention The present invention includes a movable blade for cutting sewing thread in cooperation with a fixed blade, a rotatable operating member for reciprocating the movable blade, and a rotatable operating member that is rotatable integrally with the operating member. a driven gear; a driving gear that rotates in conjunction with the drive mechanism of the sewing machine; Interlocking means for connecting and interlocking the gear and the driving gear;
a locking member that engages with the operating member during normal sewing, prevents rotation of the operating member, and holds the operating member at a predetermined angular position;
A disengagement control is provided between the locking member and the interlocking means in order to separate the locking member from the operating member at the start of thread trimming and re-engage the operating member at the end of thread trimming. Its gist is that it consists of means.

Operation With the above configuration, during normal sewing, the locking member engages with the operating member to prevent rotation of the operating member and hold the operating member at a predetermined angular position. Further, the interlocking means disengages the driven gear and the driving gear.

At the start of thread cutting, the disengagement control means disengages the locking member from the operating member. On the other hand, the interlocking means connects and interlocks the driven gear and the driving gear in order to rotate the operating member. Then, since the actuating member is released, the actuating member rotates in conjunction with the drive mechanism of the sewing machine via the interlocking means. The rotation of the operating member causes the movable blade to reciprocate. At this time, the movable blade cooperates with the fixed blade to cut the thread.

Further, at the end of thread cutting, the disengagement control means causes the locking member to engage the actuating member again.

Embodiment Hereinafter, an embodiment embodying the present invention will be described based on the drawings. As shown in FIGS. 1 and 2, a support plate 13 is fixed to the bottom surface of the upper plate 12 of the sewing machine bed 11. As shown in FIGS. A hook stopper plate 14 is fixed to the front end of the upper surface of this support plate 13, and an inner hook stopper 14a at the tip thereof.
is fitted into the inner hook retaining fitting portion 15a of the inner hook 15.

As shown in FIGS. 1 and 3, the support plate 13
A fixed blade 17 is fixed to the upper surface of the blade stand 16 fixed above, and its tip becomes a cutting edge 17a.

A movable blade 19 is rotatably supported at its base end by a shaft 18 on the support plate 13, and its tip can be inserted between the blade stand 16 and the fixed blade 17. The movable blade 19 has a blade surface 1 at its sharp tip.
9a, a thread catcher 19b, and a thread introduction groove 19c located between the blade surface 19a and the thread catcher 19b. When the movable blade 19 rotates from the solid line position to the two-dot chain line position in FIG. 1, the sharp tip enters the upper thread loop, and
By returning and rotating from the two-dot chain line position to the solid line position, the fabric side limb of the needle thread and the bobbin thread are captured in the thread catching section 19b and introduced into the thread introduction groove 19c, and then the blade surface 19a and The needle thread and bobbin thread are cut by cooperation with the distal cutting edge 17a of the fixed blade 17. The contact pressure between the cutting edge 17a of the fixed blade 17 and the blade surface 19a of the movable blade 19 is adjusted based on the movement of the screw 20 and the lock nut 21, as is clear from FIG.

As shown in FIGS. 1, 2, and 6, an actuation disk 23 as an actuation body rotatably supported by a vertical shaft 22 is disposed on the support plate 13, and its outer periphery is is one triangular notch 23a
is formed. A connecting link 2 is provided between the upper surface of the operating disk 23 and the lower surface of the movable blade 19 near the proximal end.
4 is interposed therebetween, and when the operating disk 23 rotates once in the direction of the arrow, the movable blade 19 is rotated once reciprocally via this connecting link 24.

As shown in FIGS. 1, 2, and 5, a locking lever 25 as a locking member is rotatably supported at the base end of the shaft 18 that supports the movable blade 19. A triangular locking pawl 25a that can be engaged with the notch 23a is formed in the middle part, and a release pin 25b with an oblique lower end is also provided in the middle part, as shown in FIG. It is built protruding towards the front. The spring 26 locks the locking lever 25 so that its locking claw 25a is connected to the notch 23a.
The purpose is to bias it in the direction of locking it. As shown in FIG. 1, when the locking pawl 25a of the locking lever 25 is locked in the notch 23a of the actuating disk 23, the rotation of the actuating disk 23 is prevented and the actuating disk 23 is held in a predetermined angular position. As a result, the connecting point between the connecting link 24 and the operating disc 23 connects the center of the shaft 22, which is the center of rotation of the operating disc 23, and the center of the shaft 18, which is the center of rotation of the movable blade 19. The movable blade 19 is located at the solid line position, slightly on the opposite side of the arrow P direction from the X-ray.

As shown in FIGS. 2 and 6, an auxiliary frame 31 is fixed to the lower surface of the support plate 13, and a shaft 22 for supporting the actuating disk 23 is inserted and supported in a hole 32 formed in the auxiliary frame 31. There is. Its axis 22
A driven gear 33 made of a bevel gear is supported. Furthermore, as is clear from FIGS. 2 and 4, a pair of protrusions 33a protrude from the driven gear 33.
is fitted into a fitting groove 23b formed in the actuating disk 23, so that the actuating disk 23 and the driven gear 33 rotate integrally.

As shown in FIGS. 4 and 8, a drive gear 35 is fixed to the tip of a feed cam drive shaft 34 that is connected to a hook drive shaft (not shown) and rotates in conjunction with the drive mechanism of the sewing machine. .

As shown in FIG. 2, FIG. 4, FIG. 5, FIG. 7, and FIG.
A support shaft 36 extending in the left-right direction perpendicular to 2 is supported rotatably and movably in the axial direction, and an intermediate gear body 37 is fixed to the right end thereof. The intermediate gear body 37 is always meshed with a first gear 38 made of a fan-shaped bevel gear of approximately 120 degrees that can mesh with the driven gear 33, and with the drive gear 35, and is twice or more as large as the drive gear 35. A second gear 39 is formed integrally with the first gear 38 so as to have a tooth width, and a partition wall 40 with a partially open part is formed at the center of the outer periphery of the second gear 39. has been done.

As shown in FIG. 9, when the sewing machine main shaft and the feed cam drive shaft 34 are located at a position corresponding to the lowest point of the needle and the second gear 39 is located at a predetermined rotation angle, the drive The meshing teeth of the gear 35 and the open part of the partition wall part 40 face each other,
The intermediate gear body 37 and the support shaft 36 are allowed to move in the axial direction; otherwise, the meshing teeth of the drive gear 35 and the partition wall 40 face each other, and the intermediate gear body 37 and the support shaft 36 is prevented from moving in the axial direction.

As described above, when the open part of the partition wall part 40 and the meshing teeth of the driving gear 35 face each other, and the intermediate gear part body 37 is moved to the left side as shown in FIG. The first gear 38 is located within the meshing range with the driven gear 33, and as shown in FIG. within the range. In this state, the first gear 3
8 is rotated in the direction of arrow Q in FIG. 5, the shoulder portion 38a of the first gear 38 engages with the release pin 25b, and the locking lever 25 is moved to the position shown by the two-dot chain line in FIG. After the locking pawl 25a is rotated and disengaged from the notch 23a of the actuating disk 23, the first gear 38 meshes with the driven gear 33 and the actuating disk 23 rotates once in the direction of arrow P in FIG. be done. Therefore, the driving gear 35, the intermediate gear body 37, and the driven gear 33
etc., constitute an interlocking means for rotating the operating disk 23 based on the operation of the drive mechanism of the sewing machine, and the first gear 38 and the release pin 2
5b constitutes a dissociation control means for controlling dissociation of the locking lever 25 and the actuating disk 23.

Furthermore, as shown in FIG.
7 is moved to the right side, the first gear 38 is separated from the position of the driven gear 33 and the release pin 25b.

As shown in FIGS. 2 and 5, a collar 41 having an annular recess 41a on the outer periphery is fixed to the left end of the support shaft 36. As shown in FIGS.

As shown in FIG. 2, FIG. 4, FIG. 6, and FIG. 7, a connecting lever 44 is rotatably supported at the intermediate portion of a bracket 42 fixed to the auxiliary frame 31 by a shaft 43. A pin 44a protruding from one end is fitted into the annular recess 41a of the collar 41, and as the connecting lever 44 is rotated to the left or right, the pin 44a
4a and the collar 41, the support shaft 3
6 is moved to the left or right. A spring 46 is wound around the collar 45 on the shaft 43, and one end of the spring 46 applies a spring force to the pin 44a. The intermediate gear portion 37 is biased in one direction so that the first gear 38 of 37 is separated from the driven gear 33.

A linking rod 47 serving as linking means is connected to another pin 44b protruding from the other end of the linking lever 44. The link rod 47 is pulled to the right in FIGS. 4 and 7 by a thread trimming signal based on the operation of a separately provided operating means, and the link lever 44 is rotated as shown in FIG. The intermediate gear part body 37 is moved to the left against the biasing force of 46.

Next, the operation of the thread cutting device of the sewing machine constructed as described above will be explained. Now, during normal sewing operation, as shown in FIG.
7 is moved to the left side, and the support shaft 36 is moved through the connecting lever 44 by the spring force of the spring 46.
The intermediate gear body 37 is disposed on the right side, and the first gear 38 is retreated from the meshing range with the driven gear 33 and the engagement position with the release pin 25b.
Further, as shown in FIG. 1, the locking pawl 25a of the locking lever 25 is engaged with the notch 23a of the operating disk 23, so that the operating disk 23 is locked at a predetermined rotational position. Therefore, the connection point between the operating disk 23 and the connection link 24 is located slightly on the opposite side of the arrow P direction from the line It is located on the bottom surface of 17.

Therefore, in this state, the sewing machine is driven,
The feed cam drive shaft 34 is rotated, and the drive gear 35
Even if the intermediate gear body 37 is rotated in the direction of arrow Q in FIG.
Since they are separated from each other, the rotational action is not transmitted to the movable blade 19, and the movable blade 19 maintains the locked state shown in FIG.

Then, the required sewing on the processed cloth is completed,
As shown in FIG. 9, it is assumed that the sewing machine is stopped at the needle down position. In this case, the meshing teeth of the drive gear 35 and the open part of the partition wall 40 of the second gear 39 face each other, allowing leftward movement of the intermediate gear part 37. After that, when an operation is performed to output a thread trimming signal, the fourth
The linking rod 47 in the position shown is pulled to the right. Therefore, the support shaft 36 is moved to the left through the rotation of the connection lever 44, and the intermediate gear body 37 is disposed on the left side.

In this way, when the intermediate gear body 37 is positioned to the left, the first gear 38
is located in the meshing region with the driven gear 33, and as shown in FIG.

In this state, the sewing machine main shaft is further rotated. As a result, when the feed cam drive shaft 34 continues to rotate, as is clear from FIG.
The locking lever 25 is rotated as shown by the two-dot chain line in FIG. The lock on the disc 23 is released.
Next, the first gear 38 meshes with the driven gear 33, the driven gear 33 is rotated, and the operating disc 23 is rotated.
is rotated in the direction of arrow P. Therefore, as is clear from FIG. 9, in the process of the sewing machine needle rising from the top surface of the needle plate, the movable blade 19 rotates via the connecting link 24 from the solid line position in FIG. 1 to the two-dot chain line position. After entering the loop of the needle thread at its tip, it moves backward to capture the fabric side leg of the needle thread and the bobbin thread, and the sewing machine needle moves downward and moves before reaching the top surface of the needle plate. Blade surface 19a of blade 19
The upper thread and the lower thread are cut between the cutting edge 17a of the fixed blade 17 and the cutting edge 17a of the fixed blade 17.

In this case, when the movable blade 19 starts rotating, the connection point between the connection link 24 and the operating disk 23 is
Since it is located slightly in front of the X-ray, the rotation speed of the movable blade 19 is slow at first and gradually increases, and when passing through the X-X line, the rotation direction is switched, It slows down again, then speeds up again, then stops. That is, the movable blade 19 is rapidly retracted after capturing the upper thread and the lower thread, and the cutting is performed in the rapidly moving state, so that the cutting can be performed reliably.

In this way, when the sewing machine main shaft and feed cam drive shaft 34 are rotated 240 degrees from the needle lowest point position,
After the engagement between the first gear 38 and the driven gear 33 is completed, one rotation of the operating disc 23 is completed, and the movable blade 19 has returned to the position shown in solid line in FIG. 1, the output of the thread trimming signal is released. At the same time, the open portion of the partition wall portion 40 of the second gear 39 and the meshing teeth of the drive gear 35 again face each other, allowing the intermediate gear portion 37 to move in the axial direction. Therefore, due to the spring force of the spring 46 on the connecting lever 44,
As the linkage rod 47 moves back to the left,
The intermediate gear body 37 moves back to the right together with the support shaft 36, and is in the state shown in FIG. 4.

This completes the operation for one cutting.

In this way, in this thread cutting device, the rotational motion of the operating disk 23 is transmitted to the movable blade 19 via the connecting link 24, and the movable blade 19 is reciprocated, so that the above-mentioned Unlike conventional devices, there is no spring equivalent for strongly pressing the cam follower against the cam surface, and the cutting operation of the movable blade 19 can be performed smoothly with a light load. Note that the spring 26 shown in FIG.
A weak spring force is sufficient to lock the locking pawl 25a of the locking lever 25 into the notch 23a of the actuating disk 23, and even if the locking pawl 25a and the outer periphery of the actuating disk 23 come into contact, the sewing machine It has almost no effect on the drive mechanism.

Further, during normal sewing when the movable blade 19 is not used, the locking lever 25 locks the operating disc 23 so that it cannot rotate, so that the movable blade 19 can be prevented from moving freely during normal sewing, and the movable blade 19 It is possible to avoid a situation in which the sewing machine needle collides with the sewing machine needle and damages them.

Effects of the Invention As detailed above, the thread cutting device of the present invention includes a movable blade that cooperates with a fixed blade to cut sewing thread, and a rotatable operating member that reciprocates the movable blade. , a driven gear that can rotate integrally with the operating body, a driving gear that rotates in conjunction with the drive mechanism of the sewing machine, and the driven gear and the same gear are in a disconnected state during normal sewing, and when thread trimming. an interlocking means for connecting and interlocking a driven gear and a driving gear in order to rotate the operating member; and an interlocking means that engages with the operating member during normal sewing to prevent rotation of the operating member; A locking member that holds the actuating member at a predetermined angular position; and a locking member that is disengaged from the actuator when thread trimming starts, and engages the actuator again when thread trimming is completed. When the movable blade moves reciprocally, the disengagement control means is provided between the locking body and the interlocking means, which corresponds to a spring that strongly presses the cam follower against the cam surface, unlike conventional methods. Since the sewing machine does not require any additional equipment, a large load is not applied to the drive mechanism of the sewing machine such as the sewing machine motor. The locking member is disengaged from the operating member only when thread cutting is started, and the interlocking means connects and interlocks the operating member and the drive mechanism of the sewing machine, so that the cutting operation of the movable blade is It can be done smoothly.
In addition, it is possible to reliably prevent the movable blade from moving during normal sewing, thereby providing an excellent effect of avoiding dangers such as collision between the movable blade and the needle.

[Brief explanation of drawings]

The drawings show an embodiment of a thread cutting device embodying the present invention, in which FIG. 1 is a plan view of the sewing machine bed with the upper plate removed, and FIG. 2 is a sectional view taken along the line -- in FIG. 1. , Fig. 3 is a sectional view showing the fixed blade and the movable blade taken along the - line in Fig. 1, Fig. 4 is a sectional view taken along the - line in Fig. 2 during normal operation, and Fig. 5 is a sectional view taken along the - line in Fig. 2. 6 is a cross-sectional view taken along the line -- in FIG. 4, FIG. 7 is a sectional view corresponding to FIG. 4 when thread trimming is set, FIG. 8 is a perspective view showing the drive gear and intermediate gear body, and FIG. 9 is a time chart showing the operation of the thread cutting device. Fixed blade...17, Movable blade...19, Operating disc...
...23, Notch...23a, Locking lever...2
5. Locking pawl...25a, release pin...25b, first gear...38, shoulder...38a.

Claims (1)

[Claims] 1. A movable blade 19 that cooperates with the fixed blade 17 to cut the sewing thread, an actuating member 23 that is rotatable to reciprocate the movable blade 19, and the actuating member 23. A driven gear 33 that can rotate integrally, and a drive gear 35 that rotates in conjunction with the drive mechanism of the sewing machine.During normal sewing, the driven gear 33 and the gear 35 are in a disconnected state, and when thread trimming, the In order to rotate the actuating member body 23, an interlocking means connects and interlocks the driven gear 33 and the driving gear 35, and the interlocking means engages with the actuating member body 23 during normal sewing to prevent the rotation of the actuating member body 23. A locking member 25 that prevents the thread cutting and holds the operating member 23 at a predetermined angular position; and the locking member 25 is separated from the operating member 23 at the start of thread cutting, and the thread cutting is completed. A thread cutting device for a sewing machine comprising: a disengagement control means provided between the locking member 25 and the interlocking means in order to re-engage the actuating member 23 at a later time. 2. A patent claim in which the locking part body 25 has a locking pawl 25a, and the locking pawl 25a can be engaged with one notch 23a provided on the outer periphery of the actuating part body 23 by the action of a spring. The perforator thread cutting device according to item 1. 3. The interlocking means includes a fan-shaped gear 38, and the disengagement control means includes a pin 2 fixed to the locking part body 25 and engageable with a shoulder 38a of the fan-shaped gear 38.
Claim 1 or 2 containing 5b
The thread cutting device for the sewing machine described in Section 1.