JPH042872A - Sensor for pulled yarn - Google Patents

Abstract

PURPOSE:To accurately and quantitatively sense the presence of pulled yarn from figure pattern modulation by bringing a running cloth into contact with a load cell, simultaneously providing a flat plate on the side opposite through the aforementioned cloth and carrying out the Fourier transformation of the sensed variation in tension. CONSTITUTION:A beltlike cloth 5 is brought into contact with a load cell 1 in the central part of two feed rollers 4 and simultaneously and continuously run on a flat plate 6 provided on the side opposite through the above-mentioned cloth 5 with a roller system to sense variation in tension. An output signal sensed with the aforementioned load cell 1 is inputted to a signal processing circuit 2 to carry out the Fourier transformation. The resultant figure pattern is then displayed on a display device 3 to discriminate defects of pulled yarn from pattern modulation based on the variation in tension caused by the pulled yarn present in the aforementioned cloth 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hanging line detection device. More specifically, "hanging thread" is a type of defect inherent in textiles.
The present invention relates to a detection device for detecting.

(Prior Art) A "hanging thread" is a type of defect inherent in textiles. In other words, in a textile structure formed by warp and weft threads crossing each other, threads with abnormally high tension may be mixed into some of the warp threads or weft threads, and these are called "hanging threads".
This is called a defect and is treated as a defect.

Traditionally, inspection of defects inherent in textiles has relied solely on the visual or tactile sense of an expert. In recent years, in order to automatically detect defects in these textiles using machines,
Several proposals have been made. However, detection of the "hanging thread" still relies heavily on the visual sense and tactile sense of an expert, and no method or device for automatically detecting this has been proposed. Even in its normal state, textiles have extremely complex structures.

Even for experts, the current situation is that they supplement the information obtained from vision with the information obtained from the tactile sensation of directly touching the fabric with their fingers, especially when it comes to detecting "hanging threads."

(Problems to be Solved by the Invention) These inspections using human vision and tactile sense require skill on the part of the person performing the inspection, and are not always sufficient in terms of efficiency and accuracy. These problems are fatal when inspecting fabrics produced in large quantities using multiple looms. That is, as mentioned above, even in its normal portion, a woven fabric has an extremely complicated structure, and there is no small variation in the tension of the warp and weft yarns. Detection of hanging threads is the process of extracting particularly large deviations from this variation, and a certain standard should originally be set for this. However, even with the eyes and hands of an expert, it is virtually impossible to constantly inspect many fabrics with a constant standard.

In recent years, it has become possible to stabilize the quality of industrial products at a high level through thorough QCl, or quality control. It is amazing how much quality control has been carried out.

The inventors of the present invention have conducted intensive research in view of this situation, and have found that
We have achieved the next invention related to a device that can detect hanging threads with good reproducibility and with a certain standard.

(Method R for Solving the Problems) That is, the present invention includes a conveyance unit that runs a fabric in a belt shape, a sensor that senses tension fluctuations in the running direction of the fabric by contacting the fabric, and This hanging line detection device includes a device for Fourier transforming tension fluctuations, and a fabric support plate provided on the opposite side of the sensor across the fabric.

The present invention is an apparatus for detecting "hanging threads" by detecting variations in the thickness of textiles caused by the hanging threads inherent in the textiles. In addition, the means for detecting this thickness variation generally involves detecting the displacement in a direction different from the direction of movement of an object that moves relatively on the surface of the fabric while in contact with the fabric. It is.

Such a detection device detects a hanging thread inherent in a weft by transporting the fabric continuously or intermittently using a roller system, etc., and applying a certain amount of load while in contact with the fabric. This is realized by providing a sensor that detects displacement of a movable object in a direction perpendicular to the fabric, which is provided to press against the fabric.

In addition, in detecting the hanging threads inherent in the warp threads, while transporting the fabric, a certain amount of load is applied while the fabric is in contact with the fabric on the side opposite to the surface in contact with the flat plate. This is achieved by detecting the displacement of a movable object in a direction perpendicular to the textile fabric, which is provided to press against the textile fabric and is moved in a direction perpendicular to the transport direction of the textile fabric.

Furthermore, the present invention is characterized in that the presence of a "hanging thread" is identified from the Fourier transform pattern of a signal of "fabric tension change" obtained as a "thickness variation." In an apparatus having a "mechanism for conveying textiles continuously or intermittently" as in the present invention, signals may be affected by eccentricity of the rollers, vibrations of the drive motor, natural vibrations accompanying the transport of the textiles, etc. Considerable noise components are superimposed.

Therefore, when observing the obtained signal along the time axis (or the distance traveled by the moving object along the fabric), it is difficult to simply judge the amplitude of the signal at a certain predetermined threshold level. Detection method: "Tsuri thread"
There is a possibility that signals caused by this may be overlooked.

As described above, many of these noise components are unique to the device and have a certain degree of periodicity.

Furthermore, noise components that do not have periodicity often have relatively small amplitudes, and moreover, on average, they can often be considered white noise. In contrast, the signal obtained when a "hanging string" is detected has a sudden waveform with no periodicity. Since such a Fourier transform pattern of a sudden, non-periodic signal is a unique spectral pattern with a very wide frequency band, it is relatively easy to distinguish it from a noise component.

Defects can be identified using Fourier patterns by directly determining the Fourier transform pattern itself obtained by a spectrum analyzer, etc. through image processing such as image matching, or by determining the frequency band unique to the device from the signal in advance. One possible method is to apply a threshold after avoiding it by filtering. Preferably, a determination method using a circuit that discriminates a specific frequency range included in a signal obtained from a sensor and a circuit that detects fluctuations in the signal level in the specific frequency range can be used.

For example, a load cell, a magnetic sensor, an optical sensor, etc. can be used to measure the displacement of a movable object.

It is difficult to easily specify the load to press a movable object against the fabric, as it depends on the characteristics of each fabric, the degree of hanging thread to be detected, etc., but it is generally between 1g and 1g.
kg weight, preferably in the range of 5 g weight to 100 g weight.

The shape of the part of the movable object that comes into direct contact with the fabric is also difficult to specify because it depends on the characteristics of each individual fabric, the extent of the hanging thread to be detected, etc., but it is difficult to specify the shape of the part of the movable object that directly contacts the fabric, but it is difficult to specify the shape of the part of the movable object that directly contacts the fabric. For this purpose, a hemispherical shape is preferable as much as possible.

In addition, in the present invention, the detection rate of "hanging thread" can be improved by adding a mechanism for applying tensine in the transporting direction of the textile and in a direction perpendicular to the transporting direction to the hanging thread detection section, if necessary. is also possible.

EXAMPLES The present invention will be explained in more detail by way of Examples below, but the present invention is not limited thereto.

(Example) Example 1 FIG. 1 is a schematic explanatory diagram showing the detection part of the "hanging line detection device" in the present invention. As shown in the figure, two feed rollers are installed as part of the roller system that continuously conveys the fabric to be inspected, and a load cell is pressed against the fabric at the center of the two rollers. A flat metal plate is installed to detect changes in the thickness of the fabric due to the "hanging thread."

That is, in this case, the detection end of the load cell corresponds to the "movable object provided in contact with the textile" in the present invention, and the load cell body corresponds to "a sensor that detects displacement of the movable object in a direction perpendicular to the textile". ”.

The roller width is 190cm, and the feeding speed of the fabric is 0 to 75m by controlling the drive motor of the conveyance system with an inverter.
It was made variable between / minutes. The load with which the load cell was pressed against the fabric was 50 g.

The signal obtained from the load cell is displayed on a display after being Fourier transformed by FFT.

FIG. 2 is an example of a Fourier transform pattern of a signal obtained from a normal part without a hanging string. The peaks at some specific frequencies seen in the figure are due to roller eccentricity,
This is a noise component caused by the vibration of the drive motor, the natural vibration of the mechanical system, etc.

FIG. 3 is an example of a Fourier transform pattern of a signal obtained when the detection end of the load cell passes through a certain part of the hanging string. In Figure 2, the ``unique spectral pattern with a very wide frequency band'' of the signal obtained when a ``hanging string'' is detected, which is a sudden waveform with no periodicity, is superimposed. There is. It is relatively easy to separate these two types by image processing or the like.

Embodiment 2 FIG. 4 is a schematic explanatory diagram showing the detection portion of the "hanging line detection device" according to the present invention. As in Example 1, two feed rollers are provided as shown in the figure as part of the roller system that continuously conveys the fabric to be inspected, and a load cell is pushed onto the fabric at the center of the two rollers. A flat metal plate is installed on the back side of the cloth to detect changes in the thickness of the fabric due to the "hanging thread."

The roller width is 100cm, and the feeding speed of the fabric is 0 to 75m by controlling the drive motor of the conveyance system with an inverter.
It was made variable between / minutes. The load with which the load cell was pressed against the fabric was 40 g.

In addition, four load cells are arranged in parallel at intervals of 20 c + w, and each load cell traverses at 60 m/min in a direction perpendicular to the transport direction of the textile (transverse direction of the textile) (effective traverse length of each load cell is 20 cm, Effective detection width 80
c)).

The signal obtained from the load cell is selected by a BPF for only a specific frequency band, and then converted into the distance traveled on the fabric by the conveyance speed and displayed.

BPF is set in advance by FFT to avoid noise frequencies unique to the conveyance system (caused by eccentricity of rollers, natural vibrations of mechanical systems, etc.).

FIG. 5 is an example of a signal pattern obtained from a normal part without a hanging line. BPF prevents roller eccentricity,
Since noise components caused by natural vibrations of the mechanical system are removed, a signal with high flatness is obtained.

FIG. 6 is an example of a signal pattern obtained when the detection end of the load cell passes through a certain part of the hanging string. As shown in the figure, the variation in the thickness of the fabric caused by the hanging thread can be detected as a "displacement in the direction perpendicular to the fabric" of the load cell detection end. Signal processing that takes into account the concept of Fourier transform spectrum minimizes the influence of mechanical noise components. It was also shown that it is possible to detect hanging yarns included in the warp yarns of textiles by traversing the load cell.

(Effects of the Invention) According to the present invention, compared to human visual and tactile inspections,
It does not require any skill, is superior in terms of efficiency and accuracy, and has become possible to quantitatively determine criteria.

[Brief explanation of drawings]

Figures 1 and 4 are schematic diagrams of the apparatuses of Examples 1 and 2, Figure 2 is the Fourier transform pattern of a fabric without hanging threads detected by the apparatus of Example 1, and Figure 3 is a diagram of the hanging threads. FIG. 5 shows a Fourier transform pattern of a certain textile; FIG. 5 shows a signal pattern of a textile without hanging threads detected by the apparatus of Example 2; and FIG. 6 shows a signal pattern of a textile with hanging threads. 1...Load cell, 2...Signal processing circuit, 3...
Indicator, 4...Feed roller 5...Textile, 6...
・BPF

Claims (1)

[Claims] (1) A conveyance unit that runs the fabric in a belt shape, a sensor that detects tension fluctuations in the running direction of the fabric by contacting the fabric, a device that performs Fourier transform on the tension fluctuations detected by the sensor, and A hanging thread detection device that includes a fabric support plate on the opposite side of the fabric.