JPS599190B2 - automatic cutting device for sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic cutting device for cutting a sewn piece sewn onto a fabric or a hollow ring formed continuously at the edge of a fabric, and particularly relates to an automatic cutting device for cutting a sewn piece sewn onto a fabric or a hollow ring formed continuously on the edge of the fabric. The front edge and the rear edge of the fabric to be processed are detected by a single fabric detector, and a cutter placed a predetermined distance from the fabric detector is activated based on the detection signal of each edge outputted by the fabric detector. activate it,
The present invention relates to an automatic cutting device for a sewing machine that cuts the sewn pieces and the like at the front edge and rear edge of the fabric.

In conventional devices of this kind, the main shaft of the sewing machine rotates during the time between when each edge of the fabric is detected by the fabric detector and when the cutter is activated. There were a number of them.

If the cut point of the sewn piece is made to coincide with the edge of one edge of the fabric, for example, the front edge, the fabric will not be cut to exactly the same size and shape. There is a slight difference, however, in this type of device as described above, the edge of the fabric is always required to be guided under the needle in a constant posture with respect to the feeding direction of the fabric; It is difficult to do so, and there is a risk of cutting a part of the fabric due to the fact that the sewing machine has intermittent feed, etc., so it is important to align the edge of the fabric with the cut point of the sewn piece, etc. was extremely difficult.

In addition, if the sewn piece is cut at a position slightly away from the edge of the fabric, for example on the front edge side, so as not to cut the fabric, the edge of the fabric may become the fabric detector. Since the time from detection to the cutter operation or the number of rotations of the sewing machine main shaft during that time is the same for the front edge and the rear edge of the fabric, the sewn portion Both pieces had the defect of cutting the fabric.

Therefore, the present invention was made in view of the above-mentioned defects, and the time from when the front edge of the fabric is detected by the fabric detector until the cutter is activated is longer than when the trailing edge of the fabric is detected by the fabric detector. The time from detection until the cutter is activated is longer, and at the front edge of the fabric, before the front edge reaches the cutter placement position; After that, the cutter is actuated after the edge reaches the cutter placement position,
An automatic sewing machine capable of cutting a sewn piece sewn onto a fabric or an empty ring formed continuously at the edge of the fabric without cutting the fabric at the front edge and rear edge of the fabric. The object of the present invention is to provide a cutting device.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings.

In FIGS. 1 and 2, 1 is a fabric, 2 is a sewn piece such as a sewing tape sewn onto the fabric 1, and 3 is a bed to which the fabric 1 is fed.

4 is a light source installed above the bed 3, and 5 is a photoelectric element installed below the bed 3.

6 is a cutter for cutting the sewn piece 2.

D1 is a fabric detector which is composed of the light source 4 and the light source element 5 (!-) and which detects the presence or absence of fabric 1 and generates a detection signal; D2 is a fabric detector that detects the presence or absence of fabric 1 and generates a detection signal; This is a rotation signal generator that generates rotation signals.

7 is a polarity selection circuit connected to the output side of the fabric detector D1.

LP and LR are conducting wires led out from this polarity selection circuit 7.

NOR is a NOR circuit, one input side of which is connected to conductor LP via an inverter circuit IVI, and the other input side connected to conductor LR.

FFI is a first flip-flop circuit, and its set side S is connected to the output side of the NOR circuit NOR.

FF2 is a second flip-flop circuit whose set side S is connected to conductor LR via an inverter circuit IV2 and whose reset side R is connected to conductor LF.

MM is a monostable multivibrator connected to the output side of the rotation signal generator D2.

TC is a time constant change terminal derived from this monostable multiplex bibreak MM, and this time constant change terminal T C
It is connected to the output side Q of the 81 flip-flop circuit FF2.

8 is an integrating circuit connected to the output side of the monostable multi-bibreak MM, and this integrating circuit 8 has a clear side C.

NAD is a NAND circuit, one of which is connected to the output side of the monostable manorret vibrator MM via the DC conversion circuit 9, and the other input side is connected to the output side Q of the 7-lip-flop circuit FF1. , its output side is connected to the clear side C of the integrating circuit 8.

10 is a voltage comparison circuit connected to the output side of the integrating circuit 8, and the output side thereof is connected to the reset side H of the 7-rip-7-lop circuit FF1M.

A cutter operating circuit 11 is connected to the output side of the voltage comparison circuit 10, and the output side thereof is connected to a cutter operating solenoid 12.

The operation of the embodiment of the present invention having the above configuration will be explained with reference to A to (2) in FIG. 3 and the waveform diagram in FIG. 5.

In the waveform signal shown at A in Figure 3, the high potential is
is the output potential of the fabric detector D1 when the fabric 1 is absent, and the low potential is the output potential of the fabric detector D1 when the fabric 1 is present.

Therefore, the fabric detector D1 detects the leading edge of the fabric 1 and generates a leading edge detection signal, which is the rising edge of the signal A, and detects the trailing edge of the fabric 1, and generates a trailing edge detection signal, which is the rising edge of the signal A. Generate a signal.

Generally, the sewing machine's main shaft rotation speed is maintained at a constant normal rotation speed to sew the sewing piece 2 onto the fabric 1, so the case where the sewing machine main shaft is at a constant normal rotation speed will be explained below. .

When the fabric detector D1 outputs a signal A and the signal A is input to the polarity selection circuit 7, the polarity selection circuit 7 outputs a signal having the waveform shown in B2 in FIG.
A signal having a waveform shown at B1 in FIG. 3 is output from the circuit.

The signal B2 is inverted by the inverter circuit IV1, and the logic between this inverted signal and the signal B1 is determined by the NOR circuit NOR, and the signal with this logic determined is sent to the flip-flop circuit F.
It is input to the set side S of F1.

Trailing edge detection pulse appearing on signal B1 or signal B2
When the leading edge detection pulse appearing at The signal falls and remains at a low potential.

'Now, when the fabric detector D1 detects the trailing edge of the fabric 1 and outputs the rising edge of the signal A, the polarity selection circuit 7
outputs a trailing edge detection pulse shown as signal B1 from conductor LR.

Thereafter, when the edge detection pulse is input to the set side S of the flip-flop circuit FF1 via the NOR circuit NOR, the flip-flop circuit FFI is set and its output side q
The output signal ■ falls and maintains a low potential.

At the same time, when the trailing edge detection pulse is input to the set side S of the flip-flop circuit FF2 via the inverter circuit IV2, the flip-flop circuit FF2 is set, and the E of FIG. The signal with the waveform shown in rises and maintains a high potential.

On the other hand, the rotational signal generator D2 outputs a signal with the waveform shown in F in FIG. 3 regardless of the signal A, and the monostable multivibrator MM is triggered at the rising edge of the signal F and outputs a signal in the waveform shown in G in FIG. Outputs a signal with the waveform shown.

'The flip-flop circuit FF2 outputs the high potential of the signal E from its output side Q, and when that high potential is input to the time constant change terminal TC, the time constant of the stable multi-vibration break MM is changed, and the output signal G It outputs the pulse PG2 shown in FIG.

The signal G in which this pulse PG2 appears is input to the DC conversion circuit 9 and converted into direct current, and is also input to the integration circuit 8 to increase the output potential of the integration circuit 8.

When the output potential of the integrating circuit 8 rises from the reference potential S as shown in waveform 2 in FIG. 4 and reaches the set potential VD set in advance in the voltage comparator circuit 10, the voltage comparator circuit 10 generates a signal. .

When this signal is input to the cutter operating circuit 11, the cutter operating circuit 11 generates a signal pulse P2 having a waveform shown at H in FIG. 3 on its output side.

This pulse P2 is input as a cutter operation pulse to the cutter operation solenoid 12 to operate the cutter 6.

Further, the output signal of the voltage comparison circuit 10 is input to the reset side H of the flip-flop circuit FF1 to reset the flip-flop circuit FFI, causing the output signal (2) of the circuit FF1 to rise and maintain a high potential.

At this time, since the main shaft of the sewing machine is rotating and the monostable multivibrator MM is generating pulses, the output signal of the DC conversion circuit 9 is at a high potential and opens the NAND circuit NAD, which causes the flip-flop circuit FFI to open. The output signal ■ passes through the NAND circuit NAD and is supplied to the clear side C of the integrating circuit 8, lowering the output potential of the integrating circuit 8 from the set potential VD to the reference potential VS.

The pulse P2 shown in the output signal H of the cutter actuation circuit 11 acts as a cutter actuation pulse to actuate the cutter 6 which is interlocked with the cutter actuation solenoid 12.

By this operation of the cutter 6, the sewn piece 2 is cut at the rear edge of the fabric 1.

Next, the fabric detector D1 detects the front edge of the fabric 1 and sends a signal A.
When outputting the falling edge of , the polarity selection circuit 7 outputs a leading edge detection pulse shown as a signal B2 from the conductor LF at the falling edge.

When the leading edge detection pulse is input to the set side S of the flip-flop circuit FFI via the inverter circuit IVI and the NOR circuit NOR, the flip-flop circuit FF1 is set, and the output signal (2) from its output side Q falls to a low level. Maintain potential.

At the same time, when the leading edge detection pulse is input to the reset side R of the flip-flop circuit FF2, the flip-flop circuit FF2, which had been set by the trailing edge detection pulse, is reset, and the output signal from the output side Q of the flip-flop circuit FF2 is reset. E falls and maintains a low potential.

Flip-flop circuit FF2 receives signal E from its output Q.
When the low potential is input to the time constant change terminal TC, the monostable multivibrator MM outputs the pulse PG shown in the output signal G without changing the time constant.
Outputs I.

The signal G in which this pulse PGI appears is input to the DC conversion circuit 9 and converted into direct current, and is also input to the integration circuit 8 to increase the output potential of the integration circuit 8.

When the output potential of the integrating circuit 8 rises from the reference potential vS and reaches the set potential VD, as shown by waveform (2) in FIG. 4, the voltage comparator circuit 10 generates a signal.

When this signal is input to the cutter operating circuit 11, the cutter operating circuit 11 generates a pulse P1 indicated by a signal H on its output side.

This pulse P1 operates the cutter 6 as a cutter operation pulse similarly to the pulse P2.

Further, the output signal of the voltage comparison circuit 10 is input to the reset side H of the flip-flop circuit FFI, and this circuit FFI
The output signal ■ is raised and maintained at a high potential.

The NAND circuit NAD, which is open due to the high potential output signal from the DC conversion circuit 9, passes the output signal ■ of the flip-flop circuit FF1 and supplies it to the clear side C of the integrating circuit 8, thereby increasing the output potential of the integrating circuit 8. is lowered from the set potential VD to the reference potential vS.

Thus, the pulse P1 appearing as the output signal H of the cutter operating circuit 11 is applied to the cutter 6 as a cutter operating pulse.
Activate.

By this operation of the cutter 6, the sewn piece 2 is cut at the front edge of the fabric 1.

In the embodiment of the present invention detailed above, t shown in FIG.
When the main shaft of the sewing machine is at the normal rotation speed, the fabric detector D
1 is the time from when the rear edge of the fabric 1 is detected until the cutter 6 cuts the sewn piece 2, and the distance between the fabric detector D1 and the cutter 6 shown in FIG. 1, the regular rotation, etc. be predetermined based on

In FIG. 4, tO is the time when the fabric detector D1 detects the leading or trailing edge of the fabric 1, tl, t2 is the time st3 when the cutter actuation pulses P1 and P2 are generated, and the time t is the time when the cutter operation pulses P1 and P2 are generated. This is the time when it has passed.

Waveform 3 shown in FIG. 4 shows that when the cutter 6 does not have the operation delay time ts, that is, the cutter 6 sews the material at the rear edge of the fabric 1 at the moment when the cutter operation pulse is input to the cutter operation solenoid 12. This figure shows how the output potential of the integrating circuit 8 changes when the attached piece 2 is cut, and the slope of the waveform 3 is preset based on the time t and the potential difference VD-VS. It is adjusted by the circuit constant for setting 8.

Waveform 2 shown in FIG. 4 represents how the output potential of the integrating circuit 8 changes when considering the case where the cutter 6 has an operation delay time ts in the waveform 3, and the slope of the waveform 2 is the time t − It is determined based on ts and the potential VD-VS, and is adjusted by a circuit constant for adjusting the operation delay time of the integrating circuit 8.

Waveform 1 shown in FIG. 4 has waveform 2 at time T (=t2
-tl), it shows how the output potential of the integrating circuit 8 changes, and the slope of the waveform 1 is determined based on the time tts-T and the potential difference VD-VS, and when the monostable multipibrator MM Adjusted by circuit constant for constant change.

Assuming that the waveforms 1 and 2 determined as described above represent changes in the output potential of the integrating circuit 8 when the sewn piece 2 is cut at the front and rear edges of the fabric 1, The time from when the trailing edge of the fabric 1 is detected by the fabric detector until the cutter operating pulse P2 is generated is longer than the time from when the leading edge of the fabric 1 is detected by the fabric detector until the cutter operating pulse P1 is generated. In this case, the time T becomes longer.

In this embodiment, in order to prevent the fabric from being cut together with the sewn piece when the main shaft of the sewing machine is at a constant normal rotation speed, for example, the sewn piece is attached to the edge of the fabric on the trailing edge side of the fabric. By setting the time t and the time T shown in FIG. 4 in advance so that the cutting is performed at a position slightly away from the sewing area, it is possible to cut only the sewn piece without cutting the fabric even at the front edge of the fabric. The amount of protrusion of the sewn piece from the edge of the fabric can be made approximately the same on the front edge and the rear edge of the fabric.

In addition, in this embodiment, since the point of generation of the cutter actuation pulse is determined according to the slope of the integrated output signal by integrating the pulse I-less signal with a frequency proportional to the rotational speed of the sewing machine main shaft, it is possible to When the rotational speed changes, for example when the rotational speed increases, the slope of the integral output signal increases and the cutter actuation pulse occurs earlier; on the other hand, when the rotational speed decreases, the integral output signal increases. The slope of the output signal becomes smaller and the cutter actuation pulse occurs later.

Thereby, the sewn piece can be cut so that the amount of protrusion of the sewn piece from the edge of the fabric is always equal to the preset amount, regardless of fluctuations in the rotational speed of the main shaft of the sewing machine.

As is clear from the above detailed description, the present invention detects the leading edge and trailing edge of the fabric using a single fabric detector, and calculates the width of a pulse signal having a frequency proportional to the rotational speed of the main shaft of the sewing machine as a result of the detection. Since the structure changes the generation point of the cutter actuation pulse according to the width of the changed pulse signal, the sewing machine can be sewn onto the fabric without cutting the fabric at the front edge and the rear edge of the fabric. It is possible to automatically cut the sewn pieces or empty loops formed on the edge of the fabric, and it is also configured to correct the point in time when the cutter operation pulse is generated according to fluctuations in the rotational speed of the main shaft of the sewing machine. , the sewn pieces can be cut so that the amount of protrusion of the sewn pieces from the edge of the fabric is always a preset amount regardless of variations in the rotational speed of the main shaft of the sewing machine.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the cloth edge detection state in the embodiment of the present invention, FIG. 2 is a block diagram of a circuit that controls the operation of the embodiment, and A to ■ in FIG. 3 are the operations of the embodiment. FIG. 4 is a waveform diagram showing changes in the output potential of the integrating circuit 8. 1 is a fabric, 2 is a sewing piece, 6 is a cutter, 11 is a cutter operating circuit, 12 is a cutter operating lens, D1 is a fabric detector, and D2 is a rotation signal generator.

Claims (1)

[Scope of Claims] 1. A sewing machine equipped with a cutter device 6, 11, 12 that detects the front edge and rear edge of a fabric 1 and then cuts the sewn piece 2, etc. on the fabric 1. , one fabric detector D1 that detects the leading edge and the trailing edge of the fabric 1 and generates a leading edge detection signal or a trailing edge detection signal; a rotation signal generator D2 that generates a rotation signal of a frequency; and a rotation signal generator D2 that generates a pulse signal in response to the rotation signal and sets the pulse width of the pulse signal to a first pulse width corresponding to the front edge of the fabric 1;
and a second pulse width that is narrower than the first pulse width and corresponds to the trailing edge of the fabric 1. pulse width designating means FF2 that generates a designation signal for designating a pulse width in accordance with the detection signal from the fabric detector D1; an integrating circuit 8 that integrates the pulse signal generated from the pulse generating means MM with a pulse width specified by the specified signal; and when the potential of the output signal from the integrating circuit reaches a predetermined potential, An automatic cutting device for a sewing machine consisting of a circuit 10 for operating a cutter device 6, 11, 12.