JPS5949830B2 - Sewing machine cutter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sewing machine that sequentially sews a large number of work cloths, and in particular, thread chains, tapes, etc. connected to the front edge, θ, and rear edge of each sewn work cloth. This invention relates to a cutter device that automatically cuts with a cutter.

Generally, in a sewing machine equipped with this type of cutter device, the leading edge and trailing edge of the work cloth are detected by a detector placed near the seam forming means, and after a predetermined period of time based on the detection signal, A cutter placed on the cloth feeding side of the detector is operated to cut thread chains, tapes, etc. connected to the front and rear edges of the workpiece cloth at a predetermined distance from the ends of the cloth. I was supposed to.

Furthermore, in the sewing machine configured as described above, when the front edge of the workpiece cloth is detected by the detector, the workpiece cloth is forcibly transferred by the action of the cloth feeding means consisting of a feed dog, a cloth presser foot, etc.; When the trailing edge is detected, the workpiece cloth is released from the action of the cloth feeding means and is slowly transported by an air feeding device, etc. Therefore, the cutter operation timing when the trailing edge is detected is set to the time when the leading edge is detected. It was possible to cut thread chains, tapes, etc., leaving equal lengths from both the front and back edges of the fabric.

However, for example, as shown in FIG. 3, in an overlock sewing machine, a plurality of side edges S1. S2
When sewing is performed continuously in the directions of arrows A and B along (After 30 mm is formed, it is cut by a cutter) When sewing the next side edge S2, the side on which the chain L is formed is sewn first.

In the sewing process, after the first side edge S1 is formed, the workpiece cloth is carried by the worker again in the cloth feeding direction and is used to sew the side edge S2.

For this reason, when sewing the next side edge S2 described above, the thread chain L is located at the sewing start end, and since this chain L is made of flexible thread, it may sway, causing the front edge of the workpiece cloth to Before the leading edge of the workpiece cloth is normally detected by the detector that detects the edge, the chain L crosses the detector, causing an erroneous detection signal (the chain L is usually about 5 mm wide, and one of the chains L Detects the front edge of the work cloth on the side,
A similar signal is generated, and a signal similar to that for detecting the trailing edge of the work cloth is generated on the other side.

) may occur and the cutter may be activated.

In such cutter malfunctions, when the leading edge of the work cloth is incorrectly detected, the detector detects the leading edge before the normal leading edge detection, and the cutter operation timing is set relatively quickly as described above. However, when the trailing edge is misdetected, the cutter operation timing is set late as described above, so the cutter malfunctions and the workpiece cloth is cut. There is a risk of

there were.

The present invention has been made to solve the above-mentioned problems, and includes a sewing machine equipped with cloth feeding means for feeding the work cloth in one direction in the vicinity of the seam forming means. At least one detector is disposed near the means 1 to detect the presence or absence of the work cloth, and at least one detector is disposed on the cloth feeding side from the detector to detect the presence or absence of the work cloth. A cutter for cutting a chain or the like, actuating means for the cutter, and said detection.

a first timing setting means for activating the actuating means after a predetermined period of time has elapsed based on the detection of the leading edge of the work cloth by the detector; a second timing setting means for activating after a predetermined time different from a predetermined time by the first timing setting means, and a time interval between leading edge detection and trailing edge detection by the detector, If the time interval is extremely shorter than the time interval during sewing of regular processed cloth,
By providing a disabling means for disabling the second timing setting means, when the front edge and the rear edge of the regular work cloth are detected by the detector, different operation timings are provided. When the cutter is activated, it is possible to reliably cut thread chains, tapes, etc. connected to the front and rear edges, leaving equal lengths from those edges, and the detector is If a malfunction occurs due to the thread chain or tape, and the time interval between the detection of the leading edge and the detection of the trailing edge by the detector is extremely shorter than the time interval during normal work cloth sewing, the trailing edge To provide a novel cutter device for a sewing machine in which the operation of a cutter due to erroneous detection is disabled and the possibility of cutting workpiece cloth due to malfunction of the cutter can be reliably prevented.

Below, the configuration of an overlock sewing machine embodying the present invention will be explained with reference to the drawings. In the drawing, 1 is the head of the overlock sewing machine (hereinafter referred to as the sewing machine) M, which is fixed to the cloth board 2, and 3 is the needle. The sewing machine constitutes a seam forming mechanism in cooperation with a looper (not shown), and forms overlock seams on the work cloth K.

Reference numeral 4 denotes a needle plate having a needle hole through which the needle 3 passes, and a feed dog 5 that makes four known movements moves in and out.

Reference numeral 6 denotes a presser foot, which cooperates with the feed dog 5 to constitute a cloth feeding device for feeding the work cloth K in one direction.

C is a cutter that is composed of a lower blade 7 embedded in the cloth plate 2 on the feeding side from the throat plate 4 and an upper blade 8 that rotates perpendicularly to the blade surface of the lower blade 7, and is used for sewing. At times, the chain L or tape, etc. connected to the front and rear edges of the work cloth is cut.

This chain L is driven by the sewing machine M, and the needle 3 is moved as shown in FIG. 2 immediately before and after sewing the work cloth K.
By the operation of the upper and lower loopers, the tongue piece 6a of the presser foot 6
and the tongue of the throat plate 4, and are fed in the direction of the cutter C.

Therefore, as shown in FIG. 3, this chain L having a width of 5 mm and a length of about 20 to 30 mm is connected to the front and rear edges of the side edge S1 of the work cloth.

Reference numeral 10 denotes a chain suction pipe which is disposed adjacent to the upper blade 8 and extends in the cloth feeding direction, and which is connected to a means (not shown) for generating negative pressure such as a blower. In the vicinity of the upper blade 8, a chain suction hole 10a is formed as shown in FIG.

Therefore, the chain L, tape, etc. connected to the front and rear edges of the work cloth cut by the cutter 0 are sucked in through the chain suction hole 10a and removed.

Reference numeral 11 denotes an electromagnetic drive body fixed to the back surface of the sewing machine head 1 to operate the cutter C; 12 an electromagnetic drive body 11;
As shown in FIG. 4, its lower end is pivotally connected to a lever 13 by a shaft 14.

15 connects its base end to the other end of the lever 13 and the fixing screw 1.
6, and the chain suction pipe 10
It is pivotally supported by a support member 17 disposed on the back surface of the cutter, and its tip is fixed to the base end of the upper blade 8 of the cutter 〇.

Therefore, the vertical movement of the operating rod 12 of the electromagnetic drive body 11 rotates the rotating shaft 15 via the lever 13, and the upper blade 8 is rotated to perform a cutting operation.

Reference numeral 20 denotes a cloth detection device that detects the transferred work cloth K from above the cloth plate 2, and includes a first photosensor 21 and a second photosensor 20.
As shown in FIG. 5, the second photosensor 22 is located near the drop point of the needle 3 (in this embodiment, the workpiece cloth is located at a position 35 mm away from the drop point toward the feed side as a reference). K) and the first
The photo sensor 21 is placed on the work cloth at a certain distance (75 m in this embodiment) from the second photo sensor 22 on the feed direction line.
m) on the cloth feeding side.

Both sensors 21 and 22 are composed of a light emitting element such as a light emitting diode and a light receiving element such as a phototransistor, and embed light from the upper light emitting element into the cloth plate 2.

The light is sensed by a light receiving element through a reflective plate (not shown) provided, and cloth detection is performed by blocking the light from the work cloth K.

In this embodiment, a detection signal is generated which is at a high level (high potential) when the light is blocked by the work cloth K, and at a low level j (O potential) when the light is not blocked.

Next, in order to operate the cutter device configured as described above in conjunction with the sewing machine M, a control circuit built into a control box fixed to the leg of the sewing machine M will be explained based on FIGS. 6 and 7. .

Reference numeral 30 denotes a NAND circuit, and one input terminal of the NAND circuit is connected to a signal that is connected to the terminal after a certain period of time based on the detection signal from the first photosensor 21 (the presser foot of the sewing machine M is lowered when the cloth is detected by the photosensor 21). After that, the sewing machine drive signal MC (see Fig. 7C) generated in the sewing machine M is driven (there is a time delay) is input to the other input terminal. The detection signal C25W (see FIG. 7C) of the second I sensor 22 is input.

31 is a monostable multi-bibrator that operates by capturing the leading edge fall of the output signal of the NAND circuit 30, and determines the operation timing of the upper blade 8 of the cutter 〇 in response to this output signal. The front edge of the work cloth being transferred to the feed side at a constant speed is connected to the second photosensor 2.
After passing between 2 and the reflector, before reaching the cutting position of the front edge or the cutter C, the chain L connected in front of the front edge
(In this example, cut 20 to 30 mm from the front edge.)
The timing of the output waveform from the output terminal Q is adjusted using the pulse width T1 shown in FIG. 7E.

This pulse width T1 is adjusted by a resistor 32 and a capacitor 33 that determine the time constant of the monostable multivibrator 31, and is set to a pulse width of T1-3T1-3O in this embodiment.

34 has three input terminals, two of which receive the detection signal C2 of the second photosensor 22, respectively.
5W and a negation signal MC (see FIG. 7C) obtained by negating the sewing machine drive signal MC, the NOR circuit comprising:
The other input terminal is connected to the output terminal Q of a monostable multivibrator 35 that operates upon the falling edge of the negation signal MC and generates an output signal with a relatively long pulse width T4 as shown in FIG. 7F. are doing.

This pulse width T4 is the same as or longer than the time required for the second photosensor 22 to detect the leading edge of the work cloth after the generation of the negative signal MC (however, it is longer than the time required for the second photosensor 22 to detect the trailing edge of the work cloth. This output waveform rises when the second photosensor 22 passes the trailing edge of the work cloth.

In this embodiment, a resistor 36 and a capacitor 37, which determine the time constant of the monostable multivibrator 35, are used to set the pulse width T4 to Q, 5 seconds.

Therefore, when sewing the work cloth K, the second photosensor 22 detects the chain L having a width of about 5 mm connected to the front edge of the work cloth before the front edge of the work cloth K is sewn, and thereby the front end of the chain L is detected. The time required to pass from the second photo sensor 22 to the rear end (width of the chain L) (the width of the chain L), as shown in FIG. , generates a chain L detection signal (rises when detecting the front end of chain L, falls when detecting passage of the rear end) with pulse width Tx,
Even if it is input to the NOR circuit 34, the output signal of the monostable multivibrator 35 is long enough, so the NOR circuit 34 is not affected by the detection signal of this chain L, and the output signal of the monostable multivibrator 35 in the previous stage remains at a low level. is maintained.

38 is a monostable multivibrator that operates by capturing the rise of the output signal from the NOR circuit 34 in the previous stage from low level to high level, and determines the operation timing of the upper blade 8 of the cutter C in response to this output signal. The work cloth K is released from the feed means such as the feed dog 5, and is slowly transferred to the feed side by an air feed device (not shown), so that the trailing edge completely passes through the cutting position of the cutter C. After that, the timing of the output signal from the output terminal Q is adjusted with the pulse width T2 shown in FIG. ing.

In this embodiment, the pulse width T2 is set to 100 m5ec by a resistor 39 and a capacitor 40 that determine the time constant of the monostable multivibrator 38.

41 is the monostable multivibrator 31.3, respectively.
This is a NOR circuit which inputs the output from each output terminal Q of 8, and by inputting the output signal from each output terminal Q, an output waveform as shown in FIG.

Reference numeral 42 denotes a monostable multivibrator which operates by capturing the rising edge of the output waveform of the NOR circuit 41 in the previous stage, and its output terminal Q shows an output waveform with a pulse width T3 shown in FIG. 7J.

Therefore, the operation T of the monostable multivibrator 31 for timing of cutting the chain L connected to the front edge of the work cloth
After one hour and 12 hours after the operation of the monostable multi-vibrator 38 for cutting the chain L connected to the trailing edge of the processed cloth, the monostable multi-vibrator 42 is operated and maintained for 13 hours.

It should be noted that the sum of the pulse width T3 and the pulse width T1 of the monostable multi-bi break 31, which is the time T1+T3, is the second
e) - This pulse width T3 is the same as the pulse width T1 so that the time required for transferring the work cloth from the detection position of the sensor 22 to the cutter position 〇 is the same as or shorter than that of the monostable multivibration break. The time constant of 42 is adjusted and set by a resistor 43 and a capacitor 44.

45 is a switching I transistor whose emitter is grounded, and whose base terminal is connected to the monostable multivib break 4.
At the same time, the collector terminal is connected to the operating electromagnetic coil 46 of the operating rod 12 built in the electromagnetic drive body 11 that operates the cutter 〇.

Therefore, the electromagnetic coil 46 is excited based on the operation signal from the monostable multivibrator 42 in the previous stage, and the cutter 0 cuts the chains at both the front and back edges of the work cloth in a timely manner.

Next, the general operation of the control circuit configured as described above will be explained.

First, as shown in FIG. 2, the chain L extends linearly from the tongue piece 6a of the presser foot 6 in the cutter direction.
A case will be described in which the photosensor 22 operates normally without blocking the frost detection light of the photosensor 22.

Now, when the work cloth K is fed in from the feed side in the state shown in FIG. MC is generated, the sewing machine M is driven, and the work cloth K is sewn.

Then, when the work cloth K is transferred and the second photosensor 22 detects its front edge, it generates a detection signal C25W.

As a result, the NAND circuit 30 outputs an output waveform shown in the seventh figure.

At this time, the monostable multivibrator 31 in the next stage captures this falling edge of the leading edge and generates the pulse signal shown in FIG. The signal is input to the monostable multivibrator 42 at the next stage.

The monostable multi-bi break 42 operates by catching this trailing edge rise.

Therefore, after the second photosensor 22 detects the front edge, the cutter C is not operated immediately, and the cutter C is cut after T1 hours after the front edge of the work cloth is transferred by the feed dog 5 or the like just before the cutter C. -〇 is activated, and the chain L extending forward from the front edge is cut in a timely manner leaving a certain length from the front edge, and after 13 hours, the cutter 〇 retreats so as not to interfere with the transfer to the work cloth.

The cut chain L is then sucked into the chain suction pipe 10 and removed.

During this operation period, the signals MC, C25W shown in FIG. 7B, C, and F and the output signal from the monostable multivibrator 35 are input to the NOR circuit 34,
As shown in FIG. 7G, since the NOR circuit 34 is maintained at a low level, the monostable multivibrator 38 at the next stage does not operate.

After the cutting operation of the chain L connected to the front edge is completed, the work cloth is sewn and sequentially transferred to the delivery side, and the second photosensor 22 detects the passing of the rear edge of the work cloth. Then, the detection signal C25W falls as shown in FIG. 7C.

As a result, the output waveforms of the NAND circuit 30 rise simultaneously, but the monostable multivibrator 31 at the next stage does not operate.

On the other hand, the NOR circuit 34 rises from low level to bi level as shown in FIG. 7G by this detection signal C25W.

As a result, the monostable multivibrator 38 for cutting the chain L connected to the trailing edge in a timely manner operates and generates the pulse signal shown in FIG. 7H.

Then, the next stage monostable multivibrator 42 is operated via the NOR circuit 41.

Therefore, after the second photosensor 22 detects the trailing edge of the work cloth, the cutter C is immediately activated, and there is no risk that the trailing edge of the work cloth will be accidentally cut by the cutter 〇. Twelve hours after the trailing edge passes the position of the cutter C using an air feed device, etc., the cutter 〇 is activated, and the chain L connected to the trailing edge is cut in a timely manner leaving a certain length from the trailing edge. , 13 hours later, the same cutter 〇 retreats and prepares for the next cutting operation.

Next, as shown in Fig. 3, when first sewing the side edge S of the work cloth and then sewing the side edge S2, a chain L as shown in Fig. 2 is positioned at the sewing start end. This chain L is made of flexible thread, which causes it to wobble,
Even if this chain L crosses the second photosensor 22 before the front edge of the workpiece cloth is normally detected,
A case will be described in which a detection signal for performing a cutter operation similar to the detection signal C25W of the front and rear edges of the work cloth is generated.

That is, the second photosensor 22 has a width of 5 across it.
Chain detection with a pulse width Tx shown in FIG. 7K, which detects the front end of the chain L of about mm and rises from low level to bilevel, and after Tx time, detects passage of the rear end and falls to low level. The signal is generated before the second photosensor 22 detects the leading edge of the work cloth.

In this case, the chain L connected to the front edge of the work cloth
A monostable multivibrator 31 for cutting the chain L and the work cloth in a timely manner generates an output signal as shown in FIG. It is operated with the output waveform shown in M.

Therefore, in this case, the two cutters C are operated by the monostable multi-by break 31, but the first operation is based on the signal when the workpiece cloth K is not yet relative to the second photosensor 22, so the workpiece cloth Do not cut the leading edge of the

Then, in the second operation, the chain L is cut at a good timing, leaving a certain length from the front edge of the work cloth, as in the normal operation described above.

On the other hand, during this operation period, the detection signal C25W including the detection signal of the chain L with this pulse width Tx is inputted to the next stage monostable multivibrator 38 via the NOR circuit 34.
The monostable multivibrator 38 is activated by the falling edge of the detection signal of chain L for 12 hours (lQ
After Qmsec), cutter C is attempted to operate.

However, the signal MC that negates the sewing machine drive signal MC in the previous stage
The pulse width T of the monostable multivibrator 35 that inputs
The output signal of 4 (0.5 sec) is sent to the second photosensor 2.
2 is input to the next stage NOR circuit 34 until the leading edge of the workpiece cloth is detected, so the output signal of the NOR circuit 34 is not influenced by the detection signal of the chain L, as explained in the normal operation mode. The state shown in FIG. 7G is maintained, and the monostable multivibrator 38 is not operated.

Therefore, even if the second hoist sensor 22 detects the passage of the chain L before detecting the front edge of the work cloth,
The monostable multivibrator 35 generates an output signal with a relatively long pulse width T4 (0.5 sec).
Timing for cutting the chain L connected to the trailing edge of the workpiece cloth The operation of the monostable multivibrator 38, which has a long operating time, is disabled, and there is a risk that the leading edge of the workpiece cloth will be cut based on the detection signal of the chain L. can be prevented.

After the cutting operation of the chain L connected to the front edge is completed, the detection signal C25W is sent as in the normal operation described above.
The monostable multivibrators 38 and 42 operate upon detecting the fall of the chain L, and cut the chain L connected to the trailing edge of the work cloth in preparation for the next cutting operation.

As described in detail above, the present invention provides a sewing machine equipped with a cloth feeding means for feeding a work cloth in one direction near the seam forming means, the sewing machine being arranged near the seam forming means,
at least one detector for detecting the presence or absence of work cloth; and a cutter disposed on the cloth feeding side from the detector and for cutting thread chains, etc. connected to the front and rear edges of the work cloth. and actuating means for the cutter;
The actuating means is actuated after a predetermined period of time has elapsed based on detection of the leading edge of the work cloth by the detector.

and a first timing setting means for activating the actuating means after a predetermined time different from a predetermined time by the first timing setting means based on the detection of the trailing edge of the work cloth by the detector. If the time interval between the first edge edge detection and the trailing edge detection by the second timing setting means and the detector is extremely shorter than the time interval during sewing of regular work cloth, the second timing setting means is set. and a disabling means for disabling the setting means, the front edge and the rear edge of the regular work cloth can be detected by the detector.

When cutting is performed, the cutters are activated at different timings to ensure that the thread chains, tapes, etc. connected to the leading and trailing edges are left with equal length from the leading and trailing edges. However, if the detector malfunctions due to the thread chain or tape, etc., the time interval between the detection of the front edge edge and the detection of the rear edge edge by the detector is longer than the time interval when sewing regular work cloth. If the length is extremely short, the cutter operation is disabled especially when the rear edge is incorrectly detected, and the possibility of cutting the work cloth due to cutter malfunction is reliably prevented, making it an industrially superior cutter device. It has the following effects.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing the overall configuration of an overlock sewing machine illustrating an embodiment of the present invention, Fig. 2 is an enlarged plan view of the main parts of the sewing parts of the overlock sewing machine, and Fig. 3 4 is an enlarged perspective view of the main parts of the cutter device, and FIG. 5 is a plan view of the overlock sewing machine.
FIG. 6 is a control circuit diagram of the cutter device, and FIGS. 7A to 7M are output waveform diagrams of the control circuit. Needle...3, Lower blade...7, Upper blade...
...8, Electromagnetic drive body ...11, Second photosensor ...22, Monostable multivibrator ...
...31, 35, 38, 42, NOR circuit...
・34,41. Overlock sewing machine...M,
Chain...... Processed cloth...K, Cutter...C0

Claims (1)

[Scope of Claims] 1. In a sewing machine equipped with a cloth feeding means for feeding the work cloth in one direction near the seam forming means, the sewing machine is arranged near the seam forming means and detects the presence or absence of the work cloth. at least one detector for cutting, a cutter disposed on the cloth feeding side with respect to the detector for cutting a thread chain, etc. connected to the front edge and rear edge of the work cloth; activating means; first timing setting means for activating the activating means after a predetermined time has elapsed based on the detection of the leading edge of the work cloth by the detector; a second timing setting means for activating the actuating means after a predetermined time different from the predetermined time set by the first timing setting means; and a leading edge detection and a trailing edge detection by the detector. A cutter device comprising: a disabling means for disabling the second timing setting means when the time interval is extremely shorter than the time interval during sewing of regular work cloth. 2. The cutter device according to claim 1, wherein the first and second timing setting means and the disabling means each include a monostable demulti-bi-break whose time constant is adjustable.