JPH0122626Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field In this invention, after the sewing work is completed, the thread hook reciprocates below the throat plate to capture the upper thread and lower thread connected to the looper from the end of the sewing. The present invention relates to a thread cutting device used in a double chainstitch sewing machine, which cuts by pulling a thread in cooperation with a cutting blade.

Prior Art In general, the thread cutting device of a conventional double chainstitch sewing machine first adjusts the thread tension by loosening the thread when the needle is located near the top dead center after stopping sewing and the needle thread loop is close to the looper. The thread tension is released by the device,
Next, the cutting blade moves with the thread hook to the cutting position, and then only the thread hook moves further, and when it retreats, it catches the upper thread and lower thread that are connected to the end of the sewing from the looper, and pulls them to the cutting blade waiting at the cutting position. It is designed to be cut.

Problems to be Solved by the Invention As mentioned above, in conventional thread cutting devices, the thread loosening device, cutting blade, and thread hook are operated in sequence after the sewing machine has completely stopped. It took a long time to cut the thread, and this was one of the obstacles to further speeding up the sewing process.

In order to speed up thread cutting, even if you try to operate the thread hook while the needle is moving upwards from the bottom dead center to the top dead center when sewing is stopped, the needle plate will There is a problem in that the thread hook must be moved forward and backward so as not to interfere with the movement of the needle that moves up and down in the narrow space below, the feed dog that moves back and forth, and the looper that moves in an arc left and right. The hook must follow the looper and enter into the upper thread loop that is being expanded by the looper, and must also engage the lower thread that runs from the cloth on the throat plate to the tip of the moving looper. In other words, unless the thread hook advances with precise timing in milliseconds and follows the movement of the looper, the needle, feed dog,
In order to prevent collisions with the looper and thread trimming errors, the timing must be adjusted accurately for each sewing condition, and adjustment requires skill.

Furthermore, the drive source for the thread cutting device of the conventional double chain stitch sewing machine mentioned above usually uses a solenoid or an air cylinder, but when the former is used, the solenoid itself drives the cutting blade and the thread. In order to move the hook, a device with a large load capacity must be used, and when the latter is used, the thread cutting device is complicated and expensive.

An object of the present invention is to provide a thread cutting device for a sewing machine that solves the above-mentioned problems.

Means for Solving the Problem In order to achieve this objective, the present invention aims to connect the arm provided on the looper swing shaft to the thread cutting device via the clutch mechanism while the needle is rising from the bottom dead center to the top dead center at the end of sewing. The upper thread (needle thread) and lower thread (looper thread) are both cut by engaging with the needle thread.

In other words, the present invention includes a thread hook that moves back and forth between the throat plate and the looper, captures and pulls the needle thread and bobbin thread that are connected to the sewing end from the looper, and the needle thread that is captured and pulled by the thread hook. and a thread cutting device for a double chainstitch sewing machine equipped with a cutting blade that cuts the bobbin thread in cooperation with a thread hook, which is rotatably pivoted to the sewing machine frame and includes a lever and a lever for reciprocating the thread hook. , an arm that is attached to the looper swing shaft and swings; a thread hook that reciprocates between the throat plate and the looper to catch and pull the upper thread and lower thread that are connected to the end of the sewing from the looper; In the thread cutting device of a double chainstitch sewing machine, which is equipped with a cutting blade that cuts the upper thread and lower thread that are captured and pulled by the thread hook in cooperation with the thread hook, the thread is rotatably pivoted to the sewing machine frame. A lever for reciprocating the hook, an arm that is attached to the looper swing shaft and swings, and a shaft that is supported by a shaft parallel to the looper swing shaft and slides in the axial direction to swing the arm. It can be switched between a working position that advances into the working range and a non-working position that retreats outside the working range, and includes a rocking body that engages and rotates with the arm when advancing to the working position, and a spring that moves the lever in the direction of the return movement of the thread hook. a transmission device that transmits the movement of the oscillating body moved by the arm to the lever after the arm engages with the oscillating body while the looper is moving forward, and drives the lever in the direction in which the thread hook moves forward; , which is equipped with an actuating body that switches the position of the rocking body in response to an input operation.

Fig. 1 shows a double chainstitch sewing machine that forms chain stitches through the cooperative work of a needle 1 and a looper 2.A thread tensioner 7 and a thread handler 8 are installed on the outside of the vertical body.
and a thread loosening device 9 having a pin (not shown). As is known in the art, each upper thread is raised by the above-mentioned thread handling and the pin is raised and inserted between the tension discs, and the upper tension disc is lifted up, that is, the tension is released by the thread tension device 7 and the thread is pushed up by the thread handling. and pulling out the bobbin thread from the spool which is the thread supply source.

The thread cutting device has a cutting blade 1 as shown in FIGS.
5 and a thread hook 16, the former is attached to one of a pair of slide bars 18 and 19 that is slidably fitted to a guide member 17 attached to a sewing machine frame (not shown), and the latter is attached to the other one. Slide bar 19
are fixed with screws 20, respectively, and both 15,
16 is an engagement piece 2 attached to one slide bar 18
1 protrudes from the engaging piece, and is always integrated by being in elastic contact with the engaging piece 25 attached to the other slide bar 19 by the action of a spring 24 attached to a pin 23 loosely fitted into the fixing member 22. I am now able to move around. Then, the intermediate part is pivoted to the sewing machine frame, and the slide bar 1 is inserted into the elongated hole 27 formed at one end.
The cutting blade and the thread hook 16 initially move together as a unit due to the forward movement of the lever 29 with the pin 28 loosely fitted into the lever 29, that is, the clockwise rotation of the lever in FIG. A stopper 26 attached to the end engages with the guide member 17 to prevent the slide bar 18 from moving forward, and after the cutting blade has stopped, only the thread hook 16 moves further (see FIG. 3). When the lever 29 moves back, first,
After the thread hook 16 retreats and captures the upper thread and lower thread extending from the looper to the sewing end and cuts them with the cutting blade 15, the engagement piece 25 joins to the engagement piece 21, and thereafter the spring 24 Against this action, the thread hook and cutting blade move back together to their original positions as shown in FIG.

The operations of the cutting blade and thread hook described above are almost the same as the previous ones, and there is no difference at all.

The thread cutting device further includes an operating mechanism for the lever 29, which is a characteristic feature of the present invention, and this operating mechanism will be explained below.

A bracket 31 fixed to the sewing machine frame has a guide shaft 32 and a movement shaft 33 parallel to the guide shaft.
The guide shaft 32 is fixed to the bracket 31, and the movement shaft 33 is slidably provided.The movement shaft 33 further has a block 35 connected to the link mechanism 11 and a pin 36 projecting from the side. Block 3
7, a steady rest body 38 whose bifurcation is fitted onto the guide shaft 32 to stop the rotation of the motion axis, and the lever 29
A block 40 having a pin 39 provided above, which is loosely fitted into a long hole 30 formed at the other end, is fixed thereto, and a spring 41 is attached to a guide shaft between the bracket 31 and the steady rest 38, and the above-mentioned The motion axis is biased to the right in the figure, and the block 40 is brought into elastic contact with the bracket 31.

By adjusting the fixing position of the steady rest body 38 to the movement shaft 33 from side to side, the urging force of the spring 41 in the rightward direction can be arbitrarily adjusted to be strong or weak.

A bell crank 44 has a pin 36 protruding from the side of the block 37 fitted into a fork 43 at one end.
It is rotatably and slidably supported by a shaft 45 provided protruding from the bracket 31, and has a fork 46 at the boss portion.
, and a roller 47 is pivotally attached to the other end.

The bell crank 44 is stationary during sewing, independent of the moving parts of the sewing machine, but
The arm 13 is moved in the axial direction of the shaft 45 by the rotation of the lever 49 fitted to the lever 49, and the roller 47 reciprocates the looper 2 in a direction perpendicular to the feeding direction. After reaching the position, the arm 13 rotates against the action of the spring 41.

Here, the arm 13 is spaced apart from the roller 47 when the looper 2 is at the farthest retreat, that is, when the looper 2 is located at the right end in FIG. 1 (see FIG. 4). While the movement in the axial direction is not obstructed, the roller 4 is
7, so that the bellcrank is rotated out of timing with the movement of the looper.

A vertical shaft 5 rotatably supported by a bracket 31
The lever 49 attached to the arm 1 is biased clockwise by a spring 53 to cause the bell crank 44 to come into elastic contact with the head of the shaft 45, thereby moving the roller 47 out of the range of action of the arm 13. It is located in A solenoid 55 is provided to rotate the lever 49 against the action of a spring 53 and move the bell crank 44, and when the solenoid is energized, it engages a pin 57 projecting on the lever 49. plunger 5
6 protrudes and pushes the pin 57.

As described above, when the solenoid 55 is energized, it pushes the bell crank 44 and moves the roller 47 to the operating position of the arm 13. During the clockwise rotation, the arm must be held in the active position against the action of the spring 53, and therefore the vertical shaft 51 has a
A latch lever 59 is provided at its upper end, and its intermediate portion is rotatably supported by a shaft 60 attached to the sewing machine frame, and is always supported by a spring 61 on one side 62a.
When the latch lever 59 is rotated by the excitation of the solenoid 55, one side of the engaging body pivots away from the upper surface of the latch lever, and is locked to the side surface of the latch lever 59. The latch lever is prevented from moving back due to the action of the spring 53 (see FIG. 5).

For the engaging body 62, when the engaging body comes off the top surface of the latch lever and rotates due to the action of the spring 61, the engaging body is prevented from rotating beyond a certain amount so that it does not rotate too much and come off the side surface of the latch lever. It is desirable to provide a stopper to When the bell crank 44 is rotated by the arm 13 and the movement shaft 33 moves forward and backward to the left, the engaging body that engages with the side surface of the latch lever and prevents the lever from moving backward is such that its tip surface 33a is The other side portion 62b is rotated by pushing against the action of the spring 61 (see FIG. 4);
When the axis of motion moves farthest to the left, that is, thread hook 1
6 is disengaged from the side surface of the latch lever when it is moved forward the most, and immediately after the engagement body is disengaged from the side surface of the latch lever, the latch lever moves back on the lower surface of the engagement body by the action of the spring 53. At the same time, the bell crank first moves in the axial direction and returns to its original position, and the rollers 47 move back and are disengaged from the arm 13.

Next, the bellcrank returns to rotation as the movement axis moves back, ie, moves to the right, by the action of the spring 41.

In the above, the backward movement of the latch lever is restricted by engaging the engaging body with the side surface of the latch lever, and the rollers are held in the working position of the arm 13.However, the arm 13 rotates clockwise. During this time, the solenoid 55 may be continuously energized to maintain the roller at the operating position.

Further, in the above embodiment, the block 3 is attached to the motion axis 33.
7, a steady rest body 38, and a block 40 are attached. For example, the block 40 may be formed with a fork spanning the guide shaft 32 to function as a steady rest body, or the pin 36 may be attached to the block 40. It is also possible to consolidate them into one or two blocks.

Furthermore, instead of mounting the spring 41 on the guide shaft 32, a spring may be provided on the lever 29, the bell crank 44, or the link mechanism 11 that exerts the same action as the spring 41, and the spring biases the lever 49 clockwise. 53 may also be replaced by a compression spring that is attached to the shaft 45 and brings the bell crank 44 into elastic contact with the head of the shaft 45.

Further, the solenoid in the above embodiment can be replaced with a mechanical means such as a cam that operates in conjunction with the sewing completion operation.

In addition, the cutting blade is similar to this known thread cutting device,
Although the cutting blade is moved forward to the cutting position, it is also possible to fix the cutting blade and cut the thread by moving only the thread hook forward and backward, or by arranging the cutting blade and thread hook facing each other, It is also possible to capture the upper and lower threads when the thread hook moves forward and cut the threads with the cutting blade.

The sewing machine drive motor used in the sewing machine equipped with this device is equipped with a normal needle positioner, and when the pedal is pressed back down, the solenoid 55 is energized for a certain period of time, and the needle rises from the dead center. It is designed to stop at dead center.

Next, the operation of this device will be explained.

Immediately after suturing, when the pedal is pressed back, the solenoid 55 is energized at the needle's bottom dead center, and its plunger 56 rotates the lever 49 via the pin 57, pushes the bell crank 44, moves it in the axial direction, and moves the roller 47 in the axial direction. is moved to the operating position of the arm 13. At this time, the engaging body side 62a comes off the upper surface of the latch lever 59 and engages with the side surface thereof, thereby keeping the roller 47 in the above-mentioned operating position. Then, simultaneously with the rise of the needle, the looper swing shaft 12 rotates (see Figure 6A).
The arm 13 engages with the roller 47 and the bell crank 4
4 to move the movement shaft 33 forward. Along with this, the thread tension is released by the thread tension device 7 via the link mechanism 11, and the upper thread and lower thread are pulled out from the spool by thread handling, while the lever 29
pivots to advance the cutting blade 15 and thread hook 16. Initially, the cutting blade and the thread hook move together as one (see Fig. 6B), but after the cutting blade 15 stops, only the thread hook 16 moves further following the looper 2 (see Fig. 6C). When the looper 12 moves forward the most and reaches the leftmost position, the thread hook also stops moving forward (see Figure 6D). Near the top dead center of the needle, the movement shaft tip 33a touches the other side of the engaging body 62b.
Press and remove one side of the lever from the latch lever to release the lever. The lever 49 is then returned by the action of the spring 53, the bell crank 44 moves back, and the engagement between the roller 47 and the arm 13 is released. Therefore, the movement shaft 33 moves back while rotating the bell crank 44 by the action of the spring 41, pivoting the lever 29 and moving the thread hook 16 backward. On its way back, the thread hook captures the upper thread and bobbin thread connected to the end of the sewing from the looper 2, and when pulling them under the cutting blade 15 located in the forward position, cuts the thread hook with the cutting blade (first (See Figure 6E), it returns to its original position together with the cutting blade.

Effects of the invention As described above, the thread cutting device of the present invention operates in conjunction with the swing of the looper while the needle rises from the bottom dead center to the top dead center by pressing the pedal back down after the completion of the suturing operation. The thread hook moves forward following the looper, and like the thread cutting device on conventional double chainstitch sewing machines, after the sewing operation is complete, the needle reaches the top dead center and the sewing machine stops completely. Compared to a case in which the thread hook moves forward later, the time required for the thread to be cut after the completion of the suturing work is shortened, and the speed of the suturing work can be increased. The looper swing shaft is used as the drive source to move forward, and after the looper reaches the left dead center and stops, it moves back due to the action of the spring, so no power is required for the backward movement, so it can be used as a drive source like conventional ones. There is no need to use a large-capacity solenoid or air cylinder, the structure is simple, and the power required for thread trimming can be reduced, and the looper swing axis has a relatively large swing angle, making it easy to control the timing and stroke of the thread hook. ,
The thread cutting device is directly connected to the looper swinging shaft, which allows the thread hook to accurately follow the movement of the looper, preventing thread cutting errors and other problems.
Further, by changing the angle at which the arm is attached to the looper swing axis, the timing can be easily adjusted.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a double chainstitch sewing machine equipped with a thread cutting device according to the present invention, Fig. 2 is a perspective view of the thread cutting device when it is not in operation (during sewing), and Fig. 3 is a perspective view of the same when it is in operation. FIG. 4 is a front view of the main parts of the apparatus, FIG. 5 is a partially cutaway plan view of the main parts of the apparatus, and FIGS. 6A to 6E are explanatory diagrams showing the order of operation. 1... needle, 2... looper, 10... thread cutting device, 12... looper swing axis, 13... arm,
15... Cutting blade, 16... Thread hook, 29... Lever, 32... Guide shaft, 33... Movement axis, 35,
37, 40...Block, 38...Steady rest body,
41... Spring, 44... Bell crank, 47...
Colo, 49...Lever, 53...Spring, 55...
Solenoid, 56... plunger, 59... latch lever, 61... spring, 62... engaging body.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A thread hook that moves back and forth between the throat plate and the looper and captures and pulls the upper thread and lower thread that are connected to the end of the sewing from the looper, and the thread hook A thread cutting device for a double chainstitch sewing machine is equipped with a cutting blade that cuts captured and pulled upper thread and lower thread in cooperation with a thread hook. a lever 29 for moving the looper, an arm 13 that is attached to the looper swing shaft 12 and swings, and a lever 29 for swinging the looper swing shaft 12;
It is pivoted on a shaft 45 arranged parallel to the arm 13, and can be switched between an active position in which the arm 13 slides in the axial direction and advances into the swing range of the arm 13, and a non-active position in which it retreats outside the range. A swinging body 44 engages with the arm 13 and rotates when advancing, and a spring 41 urges the lever 29 in the backward movement direction of the thread hook 16, and the arm 13 engages with the swinging body 44 while the looper moves forward. Thereafter, transmission devices 33, 37, 40, 41 transmit the movement of the swinging body 44 moved by the arm 13 to the lever 29, and drive the lever 29 in the forward movement direction of the thread hook 16.
Then, the operating body 49 is operated to switch the swinging body 44 from the non-working position to the working position by an input operation, and also to switch the swinging body 44 from the working position to the non-working position after the thread hook 16 reaches the forward end. Thread cutting device for double chainstitch sewing machine. (2) A spring 53 that acts on the actuating body 49 and urges the rocking body 44 to retreat to a non-acting position, and an engaging body 62 having first and second engaging portions 62a, 62b are provided. The first engaging portion 62a engages with a member 59 that is integrated with the actuating body 49 when the oscillating body 44 is in the operating position, thereby causing the oscillating body 44 to engage with the spring 5.
The reciprocating member 33, which constitutes the transmission position, reaches the forward end and pushes the second engaging portion 62b, thereby engaging the member 59. A thread cutting device for a double chainstitch sewing machine according to claim 1, in which the connection is canceled.