JPS5839559B2 - Stitch thread holding device for double chainstitch sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a thread cutting device I for a double chainstitch sewing machine that is capable of forming a double chainstitch by the cooperation of a needle and a looper, each holding a thread. The movable blade moves to capture the needle thread and looper thread of the fabric material at the seam, and the fixed blade cuts the captured thread. By clamping the looper thread with the looper and maintaining the clamping until a predetermined time after the start of the next seam formation, the looper thread end can be prevented from coming off from the looper, and the next seam can be formed reliably. This invention relates to a stitching thread holding device.

Conventionally, in the thread cutting device of this type of sewing machine, the fixed blade movable blade and the holder are arranged in an overlapping state at a predetermined position away from the needle path, and the movable blade overlaps the fixed blade and the holder when the thread is cut. The hook moves forward from the gap to a position where it crosses the needle path, and then moves back, and during the return movement, the tip hook captures the needle thread and looper thread, and the captured thread is held between the lower surface of the moving blade and the upper surface of the holder. There is a known device in which the captured thread is clamped and cut between a movable blade and a fixed blade. , the clamping portion of the looper thread that is clamped between the movable blade and the holder becomes very short, and as a result, the clamping becomes easier and the clamping is maintained until the predetermined time to start forming the next seam. This has the drawback that the purpose of preventing the looper thread from coming off from the looper cannot be sufficiently achieved.

In addition, the looper thread end held between the movable blade and the holder was forcibly pulled apart by the force of feeding the fabric when the next seam was formed. The timing is not constant, and as a result, if the pull-off timing is too early, the looper thread end will come out of the looper, and if the pull-off timing is delayed, the movement of the tip of the cloth due to cloth feeding is blocked, resulting in the cloth feeding effect. This has the disadvantage that the next seam shape after the thread is cut is very unstable, making it impossible to form a proper seam.Furthermore, the clamping pressure at the looper thread end changes the thickness of the thread. Therefore, in order to stabilize the above-mentioned separation timing, it is necessary to adjust the clamping pressure by the movable blade and holder each time the thickness of the thread changes.
There was a significant inconvenience in terms of operability.

The object of the present invention is to provide a sewing thread holding device that does not have these drawbacks.

An embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a movable blade having a hook 2 at its tip for catching sewing white thread and a cam surface 3 at its base. Rotatably supported.

5? j Consists of an elastic plate with approximately the same shape as the movable blade 1, and a step screw 4
It is a holder that is rotatably supported on the sewing machine frame concentrically with the movable blade 1 below the movable blade 1, and its tip is bent downward and the tip is connected to the tip of the movable blade 1 by its own elastic force. A locking portion 6 is provided at the base.

As shown in FIGS. 1 and 3, 7 is rotatably connected at one end to the movable blade 1 by a hook 8 so as to sandwich the center of the holder 5 and prevent the holder 5 from rotating counterclockwise. When the movable blade 1 rotates clockwise around the stepped screw 4 with this link, the holder 5 also rotates clockwise around the stepped screw 4 by the shaft 8.

The other end of the link 7 is rotatably connected to one arm of a connecting body 9 having two arms rotatably supported on the sewing machine frame;
One end of a connecting link 11 is rotatably connected to the other arm.

The other end of the connecting link 11 is on the right side of the connecting body 9 (Fig. 1)
, it is rotatably connected to a first arm of a rotating body 10 having three arms rotatably supported on a sewing machine frame.

A second arm extending horizontally below the first arm of the rotating body 10 is connected to a notch 14 provided at the tip of the armature 13 of the second electromagnet 12 supported on the sewing machine frame. One end of the link 16 is loosely fitted, and the other end of the link 16 is rotatably connected through a shaft 15 having a blocking body 40 at its lower end.

Further, a spring 17 is interposed between the tip of the second arm of the rotating body 10 and the sewing machine frame, and due to the action of this spring 17, the rotating body 10 receives an acting force in a counterclockwise direction about the rotation fulcrum. .

A spring 18 is interposed between the third arm of the rotating body 10 and the holder 5, and the holder 5 receives a counterclockwise force around the step screw 4 due to the action of this spring.

A locking body 19 is rotatably supported on the sewing machine frame by step screws 20 in proximity to the movable blade 1 and the holder 5, and the locking body 19 is engaged with the cam surface 3 of the movable blade 1. A locking piece 22 is provided to lock the locking portion 6 of the holding body 5 to the locking portion 21, and a spring 23 is interposed between the locking portion 21 and the sewing machine frame so that the locking portion 21 is pressed against the cam surface 3. Apply force so that they match.

A fixed blade 24 that cuts the stitching thread in cooperation with the hook 2 of the movable blade 1 is fixed to the sewing machine frame at a position opposite to the fast-moving path of the needle on the movement path of the tip of the movable blade 1. Blade 24
An elastic body 25 for pressing the movable blade 1 against the fixed blade 24 is provided between the sewing machine frame and the sewing machine frame.

A movable body 26 is rotatably supported on the sewing machine frame by a shaft 2γ, and this movable body 26 is connected to a thread tension device (not shown) that controls the tension of stitching threads such as needle thread and looper thread. As shown in FIG. 2, when the movable body 26 is at the solid line position, tension is applied to the stitching thread, and when it is at the two-dot chain line position, the tension is released.

One end of the horizontally extending arm of the movable body 26 is loosely fitted into a notch (not shown) at the tip of an armature 29, which is constantly pressed upward by a spring 32 of a first electromagnet 28 supported on the sewing machine frame. The other end of a link 31 that passes through the shaft 30 and is rotatably connected is rotatably connected.

Further, a vertical body 33 is provided below the first electromagnet 28 and moves up and down in conjunction with the movement of the armature 29.
An actuating piece 3 is provided with a protruding piece 35 that engages with the upper and lower bodies 33 and a connecting arm 36 that protrudes upward on a shaft 34 supported below.
7 is rotatably supported, and a spring 38 is fitted so that the operating piece 37 receives a force acting counterclockwise in FIG. Consolidate oppression.

Further, a shaft 39 is supported on the second electromagnet 12 on the left side of the actuating piece 37 (FIG. 2), and a blocking body 40 extending in the self-regulating direction on the shaft 39 and located below the armature 13 of the second electromagnet 12 is connected to the shaft 39. An engaging blocking piece 41 and a connecting piece 42 extending downward
The rotary body 43 provided with the rotary body 43 is rotatably supported.

The connecting arm 36 provided on the actuating piece 37 and the connecting piece 42
are rotatably connected to each other by a connecting link 44.

When the blocking piece 41 engages with the blocking body 40, there is a slight gap between the opposing side walls, as shown by the solid line in FIG.

FIG. 1.2.3 shows a state in which the first electromagnet 28 and the second electromagnet 12 are inactive, and the thread cutting device (1
When the first electromagnet 28 is activated and the armature 29 moves downward against the spring 32 due to its magnetic force, the moving body 26
rotates around the shaft 27 and moves from the solid line position to the two-dot chain line position, and the tension on the stitching thread is released and the upper and lower bodies 33
moves from the solid line position to the two-dot chain line position, the actuating piece 37 rotates clockwise (FIG. 2) about the shaft 34 against the spring 38, and the rotating body 43 rotates around the shaft 34 via the connecting link 44. 39 in the counterclockwise direction (FIG. 2), the blocking piece 41 moves from the solid line position to the two-dot chain line position and is disengaged from the blocking body 40.

When the second electromagnet 12 is activated, the rear armature 13 moves to the right due to its magnetic force, and when the rotating body 10 is rotated clockwise (FIG. 1) against the spring 17, the connecting link 11 is moved. The connecting body 9 also rotates clockwise (Fig. 1) through the
The movable blade 1 is rotated counterclockwise (FIG. 1) about the step screw 4 via the link 7.

Therefore, as shown in FIG. 4, above the looper 45, which is stopped by the upper stop mechanism of the sewing machine needle bar with the needle thread loop locked around it below the throat plate at its most advanced position,
The tip of the movable blade 1 passes on a path that crosses the movement path of the needle, and as shown in FIG. Capture one of the loops and the looper thread.

At this time, the locking portion 6 provided at the base of the holding body 5 is locked by the locking piece 22 of the locking body 19, and the holding body 5 is located at its original position.

Furthermore, if the movable blade 1 rotates counterclockwise to let out the captured stitching threads such as needle thread and looper thread, the 4th B
As shown in the figure, the cam surface 3 provided at the base of the movable blade 1 presses the engaging portion 21 of the locking body 19 against the spring 23 (FIG. 1), and the locking body 191- is pressed against the step screw 20. counterclockwise around (
As a result, the locking piece 22 of the locking body 19
The locking portion 6 of the holder 5 is disengaged, and the holder 5 is rotated counterclockwise (FIG. 1) about the step screw 4 by the action of the spring 18.

Then, the tip of the holder 5 follows almost the same path as the tip of the movable blade 1, and just before the stitching thread caught between the movable blade 1 and the fixed blade 25 is cut, the lower surface of the movable blade 1 and the holder 5
Sandwich only the looper thread between the upper surfaces, and in this state
As shown in the figure, the movable blade 1 engages with the fixed blade 25 to cut the seam thread.

Next, when the first electromagnet 12 operates for a short time and then becomes inactive, the armature 13 moves to the left by the action of the spring 17, and the rotating body 10 rotates counterclockwise (FIG. 1) to rotate the above-mentioned parts. acts in the opposite direction, and the movable blade 1 detours clockwise.

Then, the holder 5 is rotated clockwise together with the movable blade 1 by the shaft 8 connecting the movable blade 1 and the link 7 while holding the looper yarn end, and returns to the original position shown in FIG. 3.

At this time, the first electromagnet 28 is also deactivated, and the above-mentioned components linked thereto act in the opposite direction, so that tension is applied to the stitching thread by the thread tension device, and the blocking piece 41 returns to the position shown in the solid line in FIG. and engages with the blocking body 40.

Thereafter, as will be described later, when the next stitch pattern is started by driving the sewing machine, only the second electromagnet 12 is activated again after a few stitches and the armature 13 is moved to the right.

However, if the armature 13 moves slightly to the right, the blocking piece 41 locks the blocking body 40 and the armature 13
This prevents the entire stroke of the movable blade 1 from rotating slightly counterclockwise.

However, the holding body 5 remains locked to the locking body 19, and therefore the looper yarn end (1) held between the movable blade 1 and the holding body 5 is released.

FIG. 5 is an electric circuit diagram for controlling the first electromagnet 28 and the second electromagnet 12, a part of which is shown in logic.

In the figure, F is a flip-flop circuit, ND is a NAND circuit,
IV is an inverter circuit, DR is a drive circuit, N is a NOR circuit, OD is an on-delay circuit, BR is a shift register circuit, MB? '! Motor/brake coil, R is the auxiliary motor, MS is the electromagnet for controlling the safety device,
MP is a first electromagnet, MT is a second electromagnet, LSW is a low speed drive switch, DSW is a lower stop switch, TSWl is a thread trimming switch, S is a conductive detection body that is fixed to the main shaft of the sewing machine and rotates together with the main shaft, If the notch formed in the detection body S is located at the main contact point, it will be located at the needle bar (1 point), and if it is located at the bottom contact point, it will be located at the needle bar 6. It is related to be located at bottom dead center.

Although not shown in the drawings, the contacts of the L SW, I) SW and TSW are opened and closed by an operating pedal of a sewing machine or the like.

Therefore, the operation will be explained with reference to Fig. 5. In Fig. 5, state C1 is a state in which the sewing machine is stopped and the needle bar is located at the top dead center. From this state, the operating pedal is depressed forward to turn the LSW. When opened (double-dot chain position), the signal is transmitted to the NOR circuit N1 via the inverter circuit IVI, and the signal of the NOR circuit N1 is transmitted to the inverter circuit IV2 and the drive circuit D.
is transmitted to the motor brake coil MB via RI,
Motor brake coil MB becomes inactive, auxiliary motor R is driven via drive circuit DR2, and the sewing machine rotates at low speed.

When the operating pedal is returned to its original position, the LSW is closed, and when the notch of the rotating detector S reaches the main contact position, the auxiliary motor R is deactivated and the motor brake coil MB is activated. The rotation of the auxiliary motor R is stopped, and the sewing machine stops with the needle bar located at the top dead center.

When the operating pedal is depressed with the heel, the DSW opens, and the signal is transmitted to the NOR circuit N1 via the NAND circuit ID 2° flip-flop circuit F3 and the NAND circuit ND3, and the signal output from the NOR circuit N1 is transmitted to the inverter circuit IV2 and the drive circuit. The motor brake coil MB is deactivated via the circuit DR1, and the auxiliary motor R is driven via the drive circuit DR2, and the sewing machine ? ! Rotate at low speed again.

When the notch of the detection body 8 reaches the lower contact point, the signal is transmitted to the NOR circuit N1 via the inverter circuit IV4 and the NAND circuit ND3, and the auxiliary motor R becomes inactive again and the motor brake coil MB is activated. Then, the auxiliary motor R stops, and the sewing machine stops with the needle bar positioned at the bottom dead center.

At this time, even if the DSW is closed by operating the operation pedal, the signal entering the NOR circuit N1 does not change, so the auxiliary motor R is maintained in a stopped state, that is, a state in which the needle bar is located at the bottom dead center.

Then, when you further press down on the control pedal with your heel, the TS
W opens, and the signal is sent to the NAND circuit N1)5, the on-delay circuit OD1, the flip-flop circuit F4. The signal is transmitted to the NOR circuit N1 via F3 and the NAND circuit ND4, and the motor brake coil is again deactivated by the signal from the NOR circuit N1, and the auxiliary motor R is activated to rotate the sewing machine at a low speed, and the detection object S is turned off. When the main contact position is reached, the signal to the NOR circuit N1 changes and the sewing machine stops again with the needle bar at the top dead center position.

At this time, inverter circuit IV5, NOR circuit N2, NAND circuit ND6, inverter circuit IV6, and drive circuit 1
) The electromagnet MS of the safety device is activated via R3 and prevents the operating pedal from being depressed forward.

On the other hand, at the same time that the notch of the detection body S reaches the main contact position, the signal is transferred to the NAND circuit ND7 and the inverter circuit IV? and drive rotation 1) Activate the first electromagnet MP28 via R4 to release the tension on the stitching thread caused by the thread tension device.

Further, the signal output from the inverter circuit IV7 is transmitted to the on-delay circuit OD2, and after a short period of time, the signal output from the on-delay circuit OD2 is transmitted to the second electromagnet MT12 via the NOR circuit N3 and the drive circuit DR5.
As a result, as described above, the movable blade 1 or step screw 4 is rotated counterclockwise, and after catching the stitching threads such as needle thread and looper thread, the holder 5 is also rotated counterclockwise. The looper thread is moved between the movable blade 1 and the movable blade 1, and the tip of the movable blade 1 engages with the fixed blade 25 to cut the captured stitching thread.

Then, the signal output from the NOR circuit N3 is transmitted to the on-delay circuit OD3, and after a short period of time, the signal output from the on-delay circuit OD3 is transmitted to the NAND circuit ND.
9 and the second electromagnet MT12 is deactivated via the drive circuit DR5, whereby the movable blade 1 and the holder 5 rotate clockwise around the step screw 4 while holding the looper thread between them due to the action of the spring 17. and return to the original position.

Furthermore, the signal (j
The signal is transmitted to the flip-flop circuit F4 and the NAND circuit ND6 via the differential 1 circuit ND8 and the flip-flop circuit F5, and the signal transmitted to the flip-flop circuit F4 causes the NAND circuit ND7. The first electromagnet MP28 is deactivated via the inverter circuit 7 and the first drive circuit DR5, and tension is applied to the white sewing thread by the thread tension device.

On the other hand, the signal transmitted to the NAND circuit ND6 deactivates the electromagnet MS of the safety device via the inverter circuit IV6 and the drive circuit 1)R3, thereby making it possible to press the operating pedal forward.

Therefore, the sewing machine is driven by pressing the operating pedal forward to start forming the next seam, and the inverter circuit IV
3 through shift register circuits SRI, SR2,
SR3 is the predetermined number of rotations of the detection object S (in the example (3 rotations)
After detecting this, only the second electromagnet MT12 is activated again via the NAND circuit ND9 and the drive circuit DR5 by a signal output from the shift register circuit SR3, thereby causing the movable blade 1 to move slightly counterclockwise as described above. It rotates to release the looper yarn end that was held between it and the holding body 5.

In this invention, a holder that moves forward following the forward movement of the moving blade holds the looper thread captured by the moving blade between the lower surface of the moving blade and when forming the next seam after cutting the thread. By moving the movable blade slightly forward at a predetermined time, the end of the looper yarn held between the movable blade and the holder is actively released, allowing the movable blade to be moved from the capture point of the movable blade to the holder. The looper thread that extends through the lower surface to the thread hole of the looper can be held between the lower surface of the movable blade and the upper surface of the holder for a sufficient length, so that it is possible to hold the looper thread for a sufficient length between the lower surface of the movable blade and the upper surface of the holder. As a result, the looper thread can be reliably held until the end of the looper, and the looper thread can be prevented from slipping out from the looper, and the seam shape acid action can be stabilized at all times. The looper thread end held between the threads is released by a mechanical force at a predetermined time when the next seam is formed, so the release time can always be kept constant. The thread removal of the looper thread end from the looper can reliably prevent interference with the fabric feeding action caused by too slow release time, so that the next seam shape acid action after thread cutting can always be stabilized. Furthermore, there is no need to adjust the clamping pressure of the looper thread end each time the thickness of the sewing thread changes, resulting in improved operability.

[Brief explanation of drawings]

Fig. 1 is a plan view of C; Fig. 2 is a partial front view; Fig. 3 is a perspective view of Fig. 1; Fig. 4 is an explanatory diagram showing the order of opening thread trimming of A, B, and C; Fig. 5 is an electrical It is a circuit diagram.

Claims (1)

[Scope of Claims] 1. A double chainstitch sewing machine capable of forming a double chainstitch by the cooperation of a needle and a looper, each holding a thread, which reciprocates between three opposing positions across the needle path. A movable blade 1 is operable to move, and is provided with a hook part 2 at the tip and a cam part 3 at the base for capturing the needle thread and looper thread of the fabric material in the seam during forward movement; An electromagnet 1 which is connected to and moves the movable blade forward when activated and backward when not activated.
2, a fixed blade 24 which is fixedly disposed at the end position of the backward motion of the movable blade and cuts the captured thread in cooperation with the movable blade that moves forward; and a fixed blade 24 which can reciprocate directly below the movable blade along the movement path of the movable blade. In addition, a locking part 6 is formed at the base, and a tip part is formed at the tip to clamp the looper thread on the looper side from the catching point with the lower surface of the movable blade during forward movement, and the elastic force follows the forward movement of the movable blade. A holder 5 that moves forward and backward in mechanical association with the return movement of the movable blade; It has an engaging part 21 that presses against the base and a locking piece 22 that faces the locking part 6 of the holder 5, and the locking piece 22 engages with the locking part 6 at the beginning of the forward movement of the movable blade. A locking body 19 that prevents the forward movement of the holding body 5 and causes a cam portion of the movable blade to disengage the locking piece 22 and the locking portion 6 at the beginning of the forward movement of the movable blade.
and a first activation signal for activating the electromagnet for a short time in response to a thread trimming signal, and a second activation signal for activating the electromagnet again after a predetermined number of stitches have been formed immediately after the next stitch after thread cutting, or after a predetermined time has elapsed from the start of sewing. an electric circuit which generates two actuation signals; and an electric circuit arranged to act on the electromagnet or the movable blade, so that when the electromagnet is actuated by the first signal from the electric circuit (and an inactive position which allows forward movement of the movable blade over its entire range); A sewing machine stitching thread holding device comprising: a blocking piece 41 that moves to an operating position that blocks forward movement of a movable blade midway when an electromagnet is activated by a second signal from an electric circuit;