JP2793260B2 - Sewing defect detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICABILITY The present invention relates to a method of sewing a sewing machine using, for example, an overlock sewing machine or the like, as shown in FIG.
A sewing defect detection device that detects a sewing defect such as a detachment of the sewing at the fabric side ends 1a and 2a and a displacement of the fabric at the fabric end ends 1b and 2b shown in FIG. About.

2. Description of the Related Art As the above-mentioned apparatus, those shown in FIGS. 7 and 8 are known. The former device is provided with a light transmission type sensor including a light emitter 52 and a light receiver 53 at a position closer to the sewing machine than the needle drop A of the sewing needle 51 that moves up and down, so that a heavy cloth passing through the detection unit is provided. When the number of sheets changes, the received light intensity changes to detect sewing failure.

On the other hand, in the latter device, the material to be sewn is positioned before the needle drop A of the sewing machine and at a position corresponding to the fabric sewing area [sewing width B by the seam (e)] with the sewing machine needle 54.
A first detecting member 55 for detecting the number of overlapping sheets 1 and 2 (indicated by a solid line and a broken line, respectively) is provided.
A second detection member 56 for detecting the number of overlapping fabrics to be sewn 1 and 2 is also provided at a position further forward than 55 and outside the fabric sewing area to detect sewing failure.

Problems to be Solved by the Invention Meanwhile, in the case of the former device, as shown in FIG. 9, for example, as compared with the upper fabric 1 aligned by the worker, the lower hard-to-see fabric 2 is fed. If the sensor attempts to deviate from the stitch by shifting in the cloth width direction (X direction) orthogonal to the direction (Y direction), the sensor will detect one sheet of cloth, and sewing failure (this will be referred to as “separation detachment”) will be detected. Although it can be detected, as shown in FIG. 10, the end ends 1b,
Sewing defect where 2b is shifted in the Y direction (this is called fabric shift)
When this occurs, there is a problem that this may not be detected.

On the other hand, in the case of the latter device, stitching can be detected by the first detecting member 55 near the needle drop A, and cloth displacement can be detected by the first detecting member 55 far from the first detecting member 55. Although the detection can be performed by the two detecting members 56, there is another problem that it is not possible to determine whether or not the length of the fabric deviation satisfies the allowable length.

That is, it is unavoidable that the fabric displacement in the Y direction slightly occurs when sewing any fabric, and if the fabric displacement is within such an allowable range, the fabric displacement is conversely caused. Although there is no need to detect that there is, the conventional apparatus shown in FIG. 8 does not consider the interval between the two detecting members 55 and 56 in the Y direction at all. Even in this case, it is expected that an erroneous detection of a fabric shift is performed.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a sewing defect detection device capable of detecting a sewing detachment and preventing a cloth shift from being detected unless the length exceeds an allowable length.

Means for Solving the Problems A sewing defect detection device according to the present invention detects a number of overlapping fabrics to be sewn at a position before a needle drop in a sewing machine and at a position corresponding to a fabric sewing area by a sewing needle. And a second sensor for detecting the presence or absence of the fabric to be sewn at a distance further forward than the first sensor and at a separation distance along the fabric feeding direction that corresponds to the fabric misalignment allowable length. And the detection sensor of
When the first detection sensor detects one piece of cloth and the second detection sensor detects the presence of cloth, an AND circuit that generates a sewing failure signal based on those detection signals is provided.

In the present invention, since the separation distance of the first and second detection sensors along the cloth feeding direction is set to the cloth deviation allowable value, the cloth is fed in a state where the cloth deviation is shorter than this separation distance. Then, when the first detection sensor is detecting one piece of cloth, the second detection sensor does not detect the cloth, and it is not determined that the cloth is shifted through the AND circuit. On the other hand, when the cloth is sent in a state where the cloth shift is longer than the separation distance between the two detection sensors, the second detection sensor has the cloth when the first detection sensor detects one piece of cloth. Is detected, it is determined through the AND circuit that there is a fabric misalignment. Also, in the case of sewing breakage as shown in FIG. 6, when the first detection sensor detects one piece of cloth, the second detection sensor detects the presence of the cloth. This detachment can be detected.

FIG. 1 is a perspective view showing an overlock sewing machine having a sewing defect detection device according to the present invention. In the drawing, reference numeral 3 denotes a sewing needle, 4 denotes a needle plate, 5 denotes a presser foot, and A denotes a needle drop position, and a sewing stitch having a width as shown in FIG. Thus, the fabric to be sewn (not shown) is overlock-stitched.
Here, a portion corresponding to the width of the stitch is referred to as a fabric sewing area.

The needle plate 4 is fixed in a state where the needle plate 4 is buried in the cross plate 6 with its upper surface flush with the upper surface of the cross plate 6, and the entire appearance of the needle plate 4 is as shown in FIG. . The cloth is sent to the cross plate 6 in a direction from the near side to the back, that is, in the cloth feeding direction Y.

A sensor mounting member 7 is fixedly provided on the needle plate 4 on the front side of the needle drop A, and mounting holes 7a and 7b are formed in the sensor mounting member 7 at two places along the fabric feeding direction Y. Have been. In the mounting hole 7a on the side near the needle drop A, a light projector 10a constituting one of the light transmission type first detection sensors 10 is provided. Above the light projector 10a, a light receiver 10b is attached to the sewing machine main body 30. It is mounted on the provided sensor mounting member 30a. The light receiver 10b is provided with a screw provided on the sensor mounting member 30a.
By loosening 30b and shifting the position, the fabric feeding direction Y
The position can be adjusted in the horizontal direction perpendicular to the direction, ie, the cloth width direction X.

In the mounting hole 7b remote from the needle drop A, a reflection type second detection sensor 11 is installed with the light projection direction facing upward,
The separation distance (pitch) L between the first detection sensor 10 and the second detection sensor 11 is equal to the end ends 1a and 2a of the fabrics 1 and 2 where the sewing is completed.
Is set to the maximum dimension that can be accepted as a good product. The X-direction positions of the two detection sensors 10 and 11 are within an area corresponding to the cloth sewing area.

The signals detected by the first and second detection sensors 10 and 11 are given to a sewing defect detection circuit shown in FIG. In addition to the first and second detection sensors 10 and 11, this detection circuit includes a rotation IC such as a Hall IC that is mounted on a pulley (both not shown) provided on the main shaft of the sewing machine and detects the presence or absence of rotation. A detection signal is also input from the detector 13, and these three signals are amplified by amplifiers 14, 15, and 16, respectively, and then are output from the comparator 17, the comparator 18, and the monostable multivibrator 1.
The signal is supplied to the AND circuit 20 via 9.

The threshold value of the comparator 17 is set to a low level corresponding to the amount of light received when the first detection sensor 10 detects two cloths,
The first detection sensor 10 outputs an H-level signal to the AND circuit 20 only when there is only one piece of cloth, which is set to a high-level intermediate value corresponding to the amount of received light when the number of sheets is detected. Further, the threshold value of the comparator 18 is set to an intermediate value between the light receiving level when the second detection sensor 11 does not have the cloth (when there is no reflection) and the high light receiving level at which the reflected light from the cloth is detected. , When the second detection sensor 11 is detecting the dough
An H level signal is output to the AND circuit 20.

When an H level signal is input from both the comparators 17 and 18 and the monostable multivibrator 19, the AND circuit 20 determines that the sewing is defective, and the RS flip-flop
Set 21,22. And flip-flops 21, 22
Is amplified through amplifiers 23 and 24, and then supplied to an alarm lamp 25 and an alarm buzzer 26. Thereby, the alarm lamp 25 is turned on, and the alarm buzzer 26 sounds to call attention of the worker. Reference numeral 27 denotes a reset timer circuit that closes the switch 27a after a predetermined set time has elapsed after detecting a sewing defect, and reference numerals 28 and 29 denote manual reset switches. These 27 to 29 can be used alternatively, and are provided to stop the alarm lamp 25 and the alarm buzzer 26.

Next, a description will be given of the details of the detection of a material deviation by the sewing defect detection device having the above-described configuration.

4 in FIG. 4 indicates the end ends 1b and 2b of the upper and lower doughs 1 and 2.
FIG. 4 is a diagram showing stepwise a process in which the fabric is fed in a state where the deviation is larger than the allowable value, that is, the separation distance L. FIG. 4 shows the deviation of the end ends 1b and 2b of the fabrics 1 and 2. FIG. 4 is a diagram showing a process in which the fabric is fed in a state where is smaller than an allowable value.

FIG. 5 is a truth value showing whether or not there is an output from the AND circuit 20 in each process together with the rotation signal, the output signal of the second detection sensor 11, and the presence or absence of the output signal of the first detection sensor 10. In each table, the left column shows the state when the sewing machine is running, and the right column shows the state when the sewing machine is stopped. In this figure, 1 is a case where there is an output, and 0 is a case where there is no output.

First, when the state shown in FIG. 4 is reached in a state where the cloth shift is larger than the separation distance L, the two cloths 1 and 2
Are present in the detection units of the first and second detection sensors 10 and 11. Therefore, since the second detection sensor 11 detects that there is a fabric, there is an output from the comparator 18, that is, the second detection sensor 11, but the first detection sensor 10 detects two fabrics. Therefore, there is no output from the comparator 17, that is, the first detection sensor 10, and as a result, there is no output from the AND circuit 20.

Subsequently, in the state shown in FIG. 4, the lower fabric 2 is still detected by the second detection sensor 11, but the end 1b of the upper fabric 1 is detected by the second detection sensor 11. Passes the detector. Therefore, since the second detection sensor 11 detects that there is cloth, and the first detection sensor 10 detects two cloths, there is no output from the AND circuit 20 in this case as well.

Further, when the state shown in FIG. 4 is reached, the end 1b of the upper cloth 1 passes through the detection section of the first detection sensor 10 while the lower cloth 2 is detected by the second detection sensor 11. I do. Therefore, since the second detection sensor 11 detects that there is cloth, and the first detection sensor 10 detects only one cloth,
Since there are outputs from the second detection sensors 10 and 11 and, of course, the rotation signal is also output, in this case, the AND circuit 20
Output occurs, the alarm lamp 25 lights, and the alarm buzzer
26 sounds the alarm.

Thereafter, when the state shown in FIG. 4 is reached, the cloth no longer exists in the detection unit of the second detection sensor 11. Therefore, the output from the second detection sensor 11 disappears, and no output is generated from the AND circuit 20. The alarm lamp 25 and alarm buzzer
26 is stopped manually or by a timer.
5 and the alarm buzzer 26 do not stop.

On the other hand, when the cloth shift is smaller than the separation distance L, the alarm lamp 25 is turned on and the alarm buzzer 26 sounds an alarm, that is, the second detection sensor 11 detects that there is cloth, and the first Since the detection sensor 10 does not detect only one piece of dough,
No output from AND circuit 20.

When the sewing machine is not moving, the rotation signal of the sewing machine is 0 in each state.
There is no output from the D circuit 20.

Therefore, by setting the separation distance L between the first and second detection sensors 10 and 11 to the allowable deviation value of the cloth end end as described above, if a cloth deviation exceeding the allowable length occurs, the worker is instructed. An alarm can be issued. Note that the allowable length can be changed by changing the separation distance L.

Further, in the case of the apparatus according to the present invention, the first detection sensor 10 is also provided in the case where the first detection sensor 10 is used even in the case of a sewing detachment occurring near the end end or in the middle of the cloth as shown in FIGS. When the cloth is detected, the second detection sensor 11 detects the presence of the cloth, so that such a detachment can be detected.

The second detection sensor 11 is not limited to the reflection type and may be a light transmission type, as long as it can detect the presence or absence of the cloth.

In the above embodiment, the X-direction positions of the two detection sensors 10 and 11 are set in the area corresponding to the cloth sewing area. The present invention is not limited to this, and the second detection sensor 11 may be installed outside the area corresponding to the cloth sewing area depending on the shape of the cloth end end. However, also in this case, the separation distance L in the cloth feeding direction Y is set to the allowable deviation of the cloth end end, and the first detection sensor 10 is installed in an area corresponding to the cloth sewing area. Keep it.

Further, in the above embodiment, a warning is given when a failure is predicted. However, the present invention is not limited to this, and when a failure is predicted, the corresponding product is collected or counted, or the sewing machine is stopped. You may.

Effects of the Invention As described above in detail, in the case of the present invention, the separation distance between the two detection sensors along the cloth feeding direction Y is made to match the allowable value of the cloth shift. A shift can be detected, and a stitch can be detected. Thereby, there is an effect that the inspection performed in the post-process can be omitted.

[Brief description of the drawings]

1 is a perspective view showing an overlock sewing machine having a sewing defect detecting device according to the present invention, FIG. 2 is a perspective view showing a main part of the present invention, and FIG. 3 is a sewing defect detecting circuit of the device of the present invention. FIG. 4 is a diagram for explaining the details of the detection of fabric misalignment by the apparatus of the present invention, FIG. 5 is a truth table showing the detection state in FIG. 4, and FIGS. ) Is a schematic diagram showing a state in which the sewing device has detected a detachment, FIGS. 7 and 8 are diagrams showing the configuration of two types of conventional devices, and FIG. 9 is a diagram in which the fabric is shifted in the X direction. FIG. 10 is a plan view showing a case (separation state), and FIG. 10 is a plan view showing a case where the cloth is displaced in the Y direction (a cloth deviation state). 1,2 ... fabric, 1a, 2a ... side edge, 1b, 2b ... end end, 3
... sewing machine needle, A ... needle drop, 10 ... first detection sensor, 11 ... second detection sensor, 20 ... AND circuit.

Claims (1)

(57) [Claims] 1. A first detection sensor for detecting the number of overlapping fabrics to be sewn is provided at a position before the needle drop in the sewing machine and at a position corresponding to a fabric sewing area by the sewing machine needle. A second detection sensor for detecting the presence or absence of the sewn cloth is provided at a position further away from the sensor and at a separation distance corresponding to the cloth shift allowable length along the cloth feed direction, and And a AND circuit for generating a sewing failure signal based on the detection signal when the first detection sensor detects one cloth and the second detection sensor detects the presence of the cloth. Detection device.