JP2007159973A - Thread cutter of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize the driving source of a movable knife capable of cutting a thick thread. <P>SOLUTION: This thread cutter 100 is provided with the movable knife 2 reciprocating between a waiting position and a thread catching position, a fixed knife 4 reciprocating between the waiting position and an operating position and cutting a sewing thread in cooperation with the movable knife 2 in the operating position, a front stopper 7 retaining the fixed knife at the waiting position, a rear stopper 8 retaining the fixed knife 4 at the operating position, a thread retaining spring 5 energizing the movable knife 2 to the side of the fixed knife 4, a knife pressure adjusting plate 6 energizing the movable knife 2 to the side of the fixed knife 4 with an energization force stronger than that of the thread retaining spring 5, a knife stand 1 retaining the respective members, and a thread cutting solenoid 10 as a driving source for driving the movable knife 2. The knife pressure adjusting plate 6 has such a shape as energizing the movable knife 2 to the side of the fixed knife 4 in the operating position but non-energizing it in the waiting position, so that a sufficient pressure for cutting the thick thread is generated in cutting, however, no such pressure is generated in starting from the waiting position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thread trimming device for a sewing machine, and more particularly to a thread trimming device for a sewing machine having a moving knife having a catching section for catching a sewing thread and a fixed knife for cutting the sewing thread by sliding contact with the moving knife.

2. Description of the Related Art Conventionally, there is known a thread trimming device for a sewing machine, which is provided in a sewing machine bed and has a moving knife that moves forward and backward in the vicinity of a needle drop position after the end of sewing, and a fixed knife that meshes with the moving knife (for example, Patent Documents). 1).
The moving knife includes a catching section that catches the upper thread and the lower thread when moving backward after moving forward in the vicinity of the needle drop position. Then, the upper thread and the lower thread captured by the capturing section are pulled together, and these threads are cut in cooperation with the fixed knife.
The fixed knife is retracted to the standby position next to the needle drop position when sewing, but the thread is cut to shorten the cut end length of the thread sewn to the sewing product after cutting. When doing this, it moves to the vicinity of the needle entry position and performs thread trimming. And after cutting | disconnection, the structure which retracts | saves to a stand-by position again is taken so that it may not interfere with needle up-and-down movement.
Furthermore, in the conventional thread trimming device of the sewing machine, by holding the proximal end portions of the moving knife and the fixed knife so that they are in contact with each other, the blade parts of each other are brought together by the elastic force of the fixed knife and the moving knife itself. Is in contact (sliding contact) with an appropriate pressing force. In addition, by providing a spring for urging the base end of the moving knife toward the fixed knife, the cutting end of the lower thread is between the moving knife and the fixed knife in the state where both the moving knife and the fixed knife are retracted to the standby position after cutting. The lower thread can be held until the next sewing by holding the thread.
JP-A-9-299660

By the way, generally, when sewing a thick fabric, a thick thread (hereinafter referred to as a thick thread) is used. When the thick thread is cut by a thread trimming device of a sewing machine having a moving knife and a fixed knife. Needs to set a high contact pressure between both knives.
For this reason, when the pressing force of the moving knife against the fixed knife is set to be high in the conventional thread trimming device of the above-described conventional sewing machine, the elastic force of the spring that biases the moving knife toward the fixed knife is set to be high. The structure which raises a pressure was taken.
However, when such a pressing force is set high, the frictional force between the two increases, so that a large driving force is required when the moving knife moves forward and backward, particularly at the start thereof. For this reason, it is necessary to increase the size of the drive unit of the thread trimming device when sewing with a thick thread, which is not necessarily a desirable configuration when reducing the size and cost of the thread trimming device. There was an inconvenience.

  An object of the present invention is to reduce the size of a driving source of a moving knife capable of cutting a thick thread.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes a moving knife provided with a yarn catching portion that reciprocates between a standby position and a yarn catching position, a sliding contact with the moving knife, and a standby position. A fixed knife that reciprocates between the operating position approaching the needle drop point and cooperates with the moving knife at the operating position to cut the sewing thread. A first urging member and a second urging member for energizing, wherein the first urging member urges the moving knife at a standby position of the moving knife, and the second urging member A thread trimming device for a sewing machine that biases a fixed knife or a moving knife at an operation position of the fixed knife.

According to the first aspect of the present invention, when the moving knife is disposed at the operating position, the moving knife is biased toward the fixed knife by the first biasing member and the second biasing member. Thereby, for example, even when sewing a thick cloth, a sufficient cutting pressure for cutting the thick thread used for sewing the thick cloth can be secured, and the thread trimming operation can be performed smoothly. it can.
Further, the second urging member does not urge the moving knife toward the fixed knife when the moving knife is located at the standby position. That is, a large urging force does not act between the moving knife and the fixed knife at the time of starting and retreating of the moving knife, particularly at the time of starting. Therefore, the driving force for starting the moving knife can be greatly reduced, and the moving knife drive source can be reduced in size, and further, the thread trimmer can be reduced in size and cost.
In addition, since the moving knife can be pressed toward the fixed knife mainly only when the thread is cut, it is possible to effectively prevent malfunction during the moving movement of the moving knife, especially during start-up. Reliability can be improved.
In addition, when the second urging member is configured to urge the moving knife or the fixed knife with a stronger urging force than the first urging member, it is possible to ensure smooth movement of the moving knife. A thick thread can be cut smoothly.

(Overall configuration of the embodiment)
Hereinafter, a thread trimming apparatus 100 (hereinafter simply referred to as a thread trimming apparatus 100) according to an embodiment of the present invention will be described in detail with reference to FIGS.
As shown in FIG. 1, the thread trimmer 100 according to the present embodiment is attached to the lower surface of a needle plate 22 disposed in the vicinity of the needle drop position along the upper surface of a sewing machine bed (not shown).

As shown in FIG. 2, the thread trimmer 100 includes a moving knife 2 that reciprocates between a standby position and a thread catching position, and an operating position that approaches the standby position and the needle drop point and is behind the needle drop point. The fixed knife 4 that cuts the sewing thread in cooperation with the moving knife 2 at the operating position, the front stopper 7 that holds the fixed knife 4 at the standby position, and the fixed knife 4 at the operating position. The stopper 8, the thread holding spring 5 as a first urging member that urges the moving knife 2 toward the fixed knife 4, and the moving knife 2 is fixed with a stronger biasing force than the thread holding spring 5. A female pressure adjusting plate 6 as a second urging member that urges toward the knife 4 side, a knife base 1 that holds these members, and a thread trimming solenoid 10 as a drive source that drives the moving knife 2 are provided. ing.
In the following description, the direction in which the moving knife 2 moves forwards and backwards is defined as the X-axis direction (the direction in which the moving knife 2 stops when the moving knife 2 stops is the forward direction, and the return direction is the backward direction). A direction orthogonal to the axial direction and horizontal to the upper surface of the needle plate 22 is defined as a Y-axis direction, and a direction orthogonal to both the X-axis direction and the Y-axis direction is defined as a Z-axis direction.
Further, the “standby position” refers to the position P1 (see FIGS. 3 and 4) where the moving knife 2 and the fixed knife 4 are most retracted in the forward and backward movement along the X-axis direction. And the stand-by position of the moving knife 2 and the stand-by position of the fixed knife 4 are in a state where their tips are aligned at the same position.
Further, the “operation position” is a position where the fixed knife 4 is most advanced, and refers to a position P2 (see FIGS. 11 and 12) where the fixed knife 4 performs thread trimming in cooperation with the moving knife 2.
The “thread catching position” refers to the vicinity of the needle drop position in the sewing machine bed, and refers to a position P3 (see FIGS. 9 and 10) between the most advanced position of the moving knife 2 and the operating position.

The knife base 1 is attached to the lower surface of the needle plate 22 as shown in FIG.
A long groove 1a for holding a fixed knife 4 and a moving knife 2 (to be described later) slidably along the X-axis direction is formed on the upper surface of the knife base 1, that is, one end surface facing the needle plate 22.
The bottom surface of the long groove 1a is provided with a long hole 1b that penetrates the female base 1 in the Z-axis direction and extends along the longitudinal direction of the long groove 1a (see FIGS. 1 and 9).

The moving knife 2 is fitted in the long groove 1a of the female base 1, and is provided so as to be slidable along the X-axis direction which is the longitudinal direction of the long groove 1a (see FIG. 9).
The moving knife 2 is a long plate material whose one end (tip) on the front side is formed in a wedge shape, and the upper surface side of the tip portion, that is, the surface facing the needle plate 22 is an inclined portion 2b (see FIG. 4). ). Further, a blade portion 2c is provided in the vicinity (backward) of the inclined portion 2b, and as a yarn catching portion for catching the sewing thread when the moving knife 2 moves backward and forward behind the blade portion 2c. A hook 2a is formed (see FIGS. 2 and 7).
Further, on the other end (base end) side of the moving knife 2, a moving method pin 3 protruding from the upper and lower surfaces of the moving knife 2, a first cam portion 2d for releasing a front stopper 7 described later, and a rear A second cam portion 2e for releasing the engagement of the stopper 8 is provided.

  The lower end of the moving female pin 3 protrudes from the lower surface side of the moving knife 2, and is provided in a state of projecting downward from the lower surface of the female base 1 through the long hole 1b of the female base 1 described above ( (See FIG. 1). The lower end of the moving female pin 3 is connected to a moving knife driving arm 16 described later, so that the driving force of a solenoid 10 described later is transmitted to the moving knife 2. Further, the upper end portion of the moving female pin 3 protruding above the moving knife 2 is slidably inserted into a long hole 4d of the fixed knife 4 described later.

The fixed knife 4 is a plate-like member that is long in the X-axis direction, and is arranged on the moving knife 2 in the long groove 1a of the knife base 1 described above.
At the tip of the fixed knife 4, that is, one end on the front side in the X-axis direction and the end on the same side as the tip of the moving knife 2, a blade portion 4 c is provided with a cutting surface protruding downward. . When both the moving knife 2 and the fixed knife 4 are arranged at the standby position, the blade part 4c is arranged so as to face the vicinity of the middle of the inclined surface of the inclined part 2b described above, the upper surface of the moving knife 2 and the lower surface of the fixed knife 4 Are formed at a height that does not hinder the substantially entire contact (see FIG. 4).
In addition, hook portions 4a and 4b that can be engaged with and disengaged from a front stopper 7 and a rear stopper 8, which will be described later, are provided on the front and rear of the fixed knife 4 on one side in the Y-axis direction (see FIGS. 5 and 11). ).

An elongated hole 4d that extends through the stationary knife 4 in the Z-axis direction and is elongated in the X-axis direction is provided from the substantially central part in the longitudinal direction of the stationary knife 4 to the vicinity of the rear end. The upper end of the above-described moving female pin 3 is slidably inserted into the elongated hole 4d.
The rear edge of the elongated hole 4d is located at a position where the movable female pin 3 and the movable knife 2 connected to the fixed knife 4 through the elongated hole 4d are positioned at the standby position (see FIG. 3). The front and rear positions of the stationary knife 4 are set so that the stationary knife 4 is also placed at the standby position (see FIG. 3) in contact with the rear edge.
The front edge of the long hole 4d is moved to the most advanced position (see FIGS. 9 and 10) after the engagement between a front stopper 7 (to be described later) and the hook portion 4a is released by the cam portion. In this case, the front and rear positions of the moving knife 2 and the fixed knife 4 are set so that the moving knife 2 contacts the front edge and the moving knife 2 and the fixed knife 4 integrally move forward. Then, when the moving knife 2 is most advanced, the blade portion 4c provided at the tip of the fixed knife 4 is arranged at the working position for performing thread trimming.

Here, although the fixed knife 4 should originally be immovable, in order to avoid contact with a sewing needle (not shown) that drops into a needle hole 22a formed in the needle plate 22 and drops the needle during sewing. In addition, in the present embodiment, a configuration is adopted that can be retracted to a standby position beside the needle hole 22a.
That is, the fixed knife 4 is provided between the standby position (see FIGS. 3 and 4) and the working position for thread trimming (see FIGS. 9 to 12) so as to freely reciprocate with the reciprocating movement of the moving knife 2. The sewing thread is cut in cooperation with the moving knife 2 at the operating position.
In this way, the fixed knife 4 is configured to be able to reciprocate between the standby position and the action position, so that the cutting position can be as close as possible to the needle drop position, and after the thread trimming, on the lower side of the fabric. The cut end portion of the remaining sewing thread can be shortened.

One end of the front stopper 7 is rotatably supported by the knife base 1, and the other end engages with the hook portion 4 a formed on the front side of the side edge of the fixed knife 4 described above. It has become. The engaging portion 7a is always urged toward the fixed knife 4 by the hook spring 9.
The front stopper 7 functions as a positioning member that engages with the hook portion 4a to prevent the fixed knife 4 from moving forward in accordance with the forward movement of the moving knife 2, and holds the fixed knife 4 at the standby position ( (See FIGS. 3, 5 and 7).
The front stopper 7 is configured such that when the moving knife 2 (moving female pin 3) moves forward to a predetermined position, the engagement between the front stopper 7 and the hook portion 4a is released by the first cam portion 2d described above. After the release, the fixed knife 4 is allowed to move in the forward direction (see FIG. 9).

The rear stopper 8 is arranged symmetrically with the front stopper 7 with respect to the advancing / retreating movement direction of the moving knife 2, and one end of the rear stopper 8 is rotatably supported by the knife base 1 like the front stopper 7, and the other end is hooked. The engaging portion 8a is engaged with the portion 4b. Similarly to the front stopper 7, the engaging portion 8 a is always urged toward the fixed knife 4 by the hook spring 9.
The rear stopper 8 functions as a positioning member that prevents the fixed knife 4 from moving backward due to the backward movement of the moving knife 2 by engaging with the hook portion 4b, and holds the fixed knife 4 in the operating position (FIG. 9 and FIG. 11).
The rear stopper 8 is also configured such that when the moving knife 2 (moving female pin 3) is retracted to a predetermined position, the engagement between the rear stopper 8 and the hook portion 4b is released by the second cam portion 2e. After the release, the fixed knife 4 is allowed to move in the backward direction (see FIG. 3).

As shown in FIG. 1, the thread trimming solenoid 10 is disposed in the sewing machine bed portion, and is provided on a shuttle shaft base 20 that rotatably holds a rotary shaft (hook shaft) of a hook that performs sewing in cooperation with a sewing needle. It is attached. As shown in FIG. 2, the drive unit 11 of the thread trimming solenoid 10 is rotatably connected to one end of a shaft holder 13 via a link 12. The other end of the shaft holder 13 is fastened and fixed to a substantially central portion of the shaft 14 that is rotatably supported along the Z-axis direction in the sewing machine bed portion. One end of a link 15 is eccentrically connected to the upper end of the shaft 14 so as to be eccentric from the rotation center of the shaft 14, and the other end of the link 15 is connected to a substantially central portion in the longitudinal direction of the moving knife driving arm 16. It is pivotally connected. One end of the moving knife driving arm 16 is rotatably supported in the sewing machine bed portion, and a bifurcated portion 16 a is formed at the other end of the moving knife driving arm 16. A slit 18 is formed between the bifurcated portion 16a.
In the slit 18, the lower end of the above-described dynamic female pin 3 is slidably inserted (see FIG. 1).
The shaft 14 reciprocates in response to the driving of the thread trimming solenoid 10, and the moving knife 2 moves forward through the link 15 and the moving knife driving arm 16.
Further, the moving knife 2 moves backward by rotating the shaft 14 in the reverse direction by driving the cam 21 interlocked with a sewing machine main shaft (not shown).
In other words, the moving knife 2 in the present embodiment is configured such that when a control unit (not shown) detects the last needle drop (final needle) in the sewing operation, the thread trimmer solenoid 10 is turned ON to move from the standby position to the most advanced position. After the forward movement is performed and then the solenoid 10 is turned off, the backward movement is performed by driving the cam 21. The drive mechanism of the cam 21 is well known in the art and will not be described in detail in this embodiment.

One end of the thread holding spring 5 is fixed to one end of the knife base 1 positioned below the forward / backward movement path of the moving knife 2, and the other end is bent upward and is in contact with the moving knife 2. .
The thread holding spring 5 urges the moving knife 2 abutted to the other end toward the fixed knife 4, and the urging force (elastic force) of the thread holding spring 5 easily moves along the fixed knife 4. The biasing force is set to such an extent that does not hinder the forward / backward movement (see FIGS. 4 and 6).
The thread holding spring 5 is bent and moved upward from the vicinity of the edge of the knife base 1 on the side where the moving knife 2 moves forward, in contact with the moving knife 2 from below in the vicinity (backward) of the moving knife 2. Since the structure in which the urging force is applied to the knife 2 is adopted, the moving knife 2 is moved forward and backward from the time when the moving knife 2 is located at the standby position (see FIG. 4) to the time when it is located at the most advanced position (see FIG. 9). The moving knife 2 is urged toward the fixed knife 4 in the entire range of movement.

The knife pressure adjusting plate 6 is fixed to the knife base 1 with the base end thereof being overlapped below the thread holding spring 5, and the other end (tip) is the working position, that is, the moving knife 2 and the fixed knife 5. Are extended to the lower side of the cutting position where the thread trimming is performed (see FIG. 12).
The tip of the knife pressure adjusting plate 6 is bent so that the vicinity of the tip is convex upward, and the upper surface of the convex part of the knife base 1 on which the moving knife 2 is placed. It is set at a position higher than the bottom surface (upper surface) of the long groove 1a.
The range from the base end of the knife pressure adjusting plate 6 to the rise of the bent portion at the tip is extended substantially parallel to the lower surface of the knife base 1. That is, the knife pressure adjusting plate 6 biases the moving knife 2 toward the fixed knife 4 when the moving knife 2 is positioned between the standby position (see FIGS. 3 and 4) and the standby position and the operating position. When the moving knife 2 is positioned in front of the operating position and the operating position, the moving knife 2 is urged toward the fixed knife 4 side.
Further, the urging force (elastic force) of the knife pressure adjusting plate 6 is set to a value stronger than that of the thread holding spring 5, and the moving knife 2 is fixed with a urging force stronger than that of the thread holding spring 5. It is designed to be biased to the 4th side. In other words, the knife pressure adjusting plate 6 restricts the downward deflection of the moving knife 2 below the operating position, and resists the lower surface of the moving knife 2 against the urging force from the fixed knife 4 and the weight of the moving knife 2. It has a function of maintaining the height substantially the same as the bottom surface of the long groove 1 a of the female base 1.

(Explanation of operation of thread trimming device)
Next, the operation of the thread trimming device 100 having the above-described configuration will be described with reference to the drawings.
During sewing in which needle dropping is repeatedly performed by a sewing needle (not shown), both the moving knife 2 and the fixed knife 4 are arranged at the standby position (see FIGS. 1 and 2).
Next, when a control unit (not shown) detects the last needle drop, that is, the last needle, the solenoid valve that drives the solenoid 10 is turned on to start the thread trimming operation.
Specifically, when the solenoid 10 is driven, the shaft 14 rotates, the driving force is transmitted to the moving female 3 via the link 15 and the moving knife driving arm 16, and the moving knife 2 moves forward.
At the start of the forward movement of the moving knife 2, the front stopper 7 is engaged with the front hook 4a, and the fixed knife 4 is held at the standby position. Therefore, only the moving knife 2 moves forward at the start (see FIGS. 3 and 4).

Here, since the blade portion 4c of the stationary knife 4 is disposed above the inclined portion 2b at the standby position, the inclined portion 2b and the blade portion 4c are brought into contact immediately after starting, but the thread holding spring. 5 is easily bent downward with a light force, the inclined portion 2b and the blade portion 4c slide along with the forward movement of the moving knife 2, the tip of the fixed knife 4 moves upward, and the thread holding spring. 5 is bent downward, and the inclined portion 2b of the moving knife 2 can easily get over the blade 4c (convex shape downward) of the fixed knife 4. Then, the moving knife 2 that has passed through the blade portion 4c of the fixed knife 4 advances slightly downward from the horizontal direction (see FIG. 6).
During the forward movement, the tip of the moving knife 2 is brought into contact with the convex part of the knife pressure adjusting plate 6 and slides along the convex part. For this reason, the moving direction of the moving knife 2 is corrected in the substantially horizontal direction (see FIGS. 7 and 8). Along with this, the tip of the fixed knife 4 is further bent upward, and the contact pressure between the moving knife 2 and the fixed knife 4 increases.

Next, when the moving knife 2 further moves forward, the first cam portion 2d pushes away the front stopper 7 to disengage the front hook 4a from the front stopper 7 (see FIG. 13), and the moving knife 2 further moves forward. As a result, the moving female pin 3 comes into contact with the front end of the long hole 4d. Then, the moving knife 2 and the fixed knife 4 integrally move forward, and the moving knife 2 is arranged at the most advanced position and the fixed knife 4 is arranged at the operating position (see FIGS. 9 and 10). At that time, the rear hook 4b of the fixed knife 4 and the rear stopper 8 are engaged with each other at a position immediately before the fixed knife 4 is disposed at the operating position.
Then, in a state where the fixed knife 4 is disposed at the operating position, the blade portion 4 c of the fixed knife 4 is disposed so as to face the convex portion of the knife pressure adjusting plate 6.

Next, the drive of the solenoid 10 is cut off (OFF), and the moving knife 2 starts to move backward by the operation of the cam 21 that rotates in synchronization with the sewing machine spindle (not shown). Since the rear hook 4b of the fixed knife 4 and the rear stopper 8 are engaged at the start of such backward movement, the fixed knife 4 is held in the operating position and only the moving knife 2 is moved backward.
After the backward movement start from the most advanced position, the sewing thread is captured by the hook 2a of the moving knife 2. Further, when the moving knife 2 moves backward and passes through the operating position of the fixed knife 4, thread cutting is performed by the blade part 2c of the moving knife 2 and the blade part 4c of the fixed knife 4 (FIGS. 11 and 11). 12).
Here, in the thread trimming device 100 according to the present embodiment, the convex portion of the knife pressure adjusting plate 6 that supports the moving knife 2 is disposed below the operating position where the thread trimming is performed by the moving knife 2 and the fixed knife 4. Therefore, the moving knife 2 does not escape downward when thread trimming is performed, and the state in which the moving knife 2 pushes the fixed knife 4 back is maintained. Therefore, sufficient contact pressure for cutting the thick thread is ensured between the moving knife 2 and the fixed knife 4.

After the thread trimming is completed, the moving knife 2 further moves backward. At that time, the sewing thread (lower thread) is sandwiched (held) between the moving knife 2 and the fixed knife 4. That is, the moving knife 2 and the fixed knife 4 in the present embodiment have a function as a cutting blade that performs thread trimming, a function as a spring material that presses the cutting blades, and a clamp member that holds the thread after cutting. It has three functions by itself.
When the moving knife 2 further moves backward, the second cam portion 2e pushes away the rear stopper 8, and the engagement between the rear hook 4b and the rear stopper 8 is released (see FIG. 14). Then, the moving knife 2 and the fixed knife 4 are integrally moved backward, and both are rearranged at the standby position (see FIGS. 1 and 2), and the thread trimming operation is completed.

(Effect of embodiment)
As described above, according to the thread trimming device 100 of the sewing machine according to the present embodiment, when the fixed knife 4 is arranged at the operating position, the thread holding spring 5 and an elastic force stronger than the thread holding spring 5 are provided. The moving knife 2 can be urged toward the fixed knife 4 by the knife pressure adjusting plate 6 having the above. Thereby, for example, even when sewing is performed on a thick cloth, a thread trimming operation for cutting a thick thread used for sewing the thick cloth or leather can be performed smoothly.
Further, the knife pressure adjusting plate 6 does not bias the moving knife 2 toward the fixed knife 4 when the moving knife 2 is located at the standby position, and fixes the moving knife 2 only at the working position where thread trimming is performed. It can urge to the knife 4 side. That is, it is possible to prevent a large urging force from acting between the moving knife 2 and the fixed knife 4 during the forward and backward movement of the moving knife 2, particularly at the time of starting (immediately after starting). Therefore, since the driving force for starting the moving knife 2 can be greatly reduced, the solenoid 10 that is a driving source for driving the moving knife 2 can be downsized, and the cost can be reduced.
In addition, it is possible to effectively prevent malfunction when the moving knife 2 moves forward and backward, and it is possible to improve the reliability of the thread trimming operation.
Further, the knife pressure adjusting plate 6 is configured such that one end side is supported by the knife base 1 and the other end side is extended to the vicinity of the working position, and the other end side is bent toward the fixed knife 4 side. Thus, the above-described effects can be obtained with a simple configuration.

(Other)
In this embodiment, the knife pressure adjusting plate 6 is configured to press the moving knife 2 toward the fixed knife 4 side, but may be arranged to press the fixed knife 4 toward the moving knife 2 side.

It is a perspective view which shows the state in which the thread trimming device of the sewing machine which is embodiment of this invention was mounted in the shuttle shaft base. 1 is a perspective view showing a thread trimming device (drive system) for a sewing machine according to an embodiment of the present invention. It is a perspective view which shows the thread trimming device (standby position) of the sewing machine which is embodiment of this invention. It is a side view which shows the thread trimming device (standby position) of the sewing machine which is embodiment of this invention. It is a perspective view which shows the thread trimming device (at the time of moving knife starting) of the sewing machine which is embodiment of this invention. It is a side view which shows the thread trimming device (at the time of a moving knife start) of the sewing machine which is embodiment of this invention. It is a perspective view which shows the thread trimming device (at the time of a convex part passage) of the sewing machine which is embodiment of this invention. It is a side view which shows the thread trimming device (at the time of a convex part passage) of the sewing machine which is embodiment of this invention. It is a perspective view which shows the thread trimming device (most advanced position) of the sewing machine which is embodiment of this invention. It is a side view which shows the thread trimming device (most advanced position) of the sewing machine which is embodiment of this invention. 1 is a perspective view showing a thread trimming device (at the time of lower thread cutting) of a sewing machine according to an embodiment of the present invention. It is a side view showing the thread trimming device (at the time of lower thread cutting) of the sewing machine which is an embodiment of the present invention. In the thread trimming device of the sewing machine which is an embodiment of the present invention, it is a top view showing the state where engagement with a front hook and a front stopper was canceled by the 1st cam part. FIG. 6 is a plan view showing a state immediately before the engagement between the rear hook and the rear stopper is released by a second cam portion in the thread trimming device of the sewing machine according to the embodiment of the present invention.

Explanation of symbols

1 Female base 1a Long groove 1b Long hole 2 Moving knife 2a Hook (thread catcher)
2b Inclined portion 2c Blade portion 2d First cam portion 2e Second cam portion 3 Moving female 4 Fixed knife 4a Front hook 4b Rear hook 4c Blade portion 4d Long hole 5 Thread holding spring (first biasing member)
6 Female pressure adjustment plate (second biasing member)
7 Front stopper 7a Engagement part 8 Rear stopper 8a Engagement part 9 Hook spring 10 Thread trimmer solenoid 11 Drive part 12 Link 13 Shaft holder 14 Shaft 15 Link 16 Moving knife drive arm 16a Bifurcated part 17 Swing center 20 Hook shaft base 21 Cam 22 Needle plate 100 Thread trimming device (thread trimming device for sewing machine)
P1 Standby position P2 Action position P3 Yarn catch position

Claims (1)

A moving knife provided with a thread catching portion that reciprocates between a standby position and a thread catching position;
A fixed knife that slidably contacts the moving knife and reciprocates between a standby position and an action position approaching the needle drop point, and that cuts the sewing thread in cooperation with the moving knife at the action position;
A first urging member and a second urging member that urge the moving knife and the fixed knife in a direction in contact with each other;
The first biasing member biases the moving knife at the standby position of the moving knife,
The thread trimmer for a sewing machine, wherein the second urging member urges a fixed knife or a moving knife at an operating position of the fixed knife.

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