JP3901343B2 - Falling object detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a detection device for detecting the fall of a polymer melt generated during a spinning process.
[0002]
[Prior art]
There are many abnormalities that occur in the spinning process, and among these, there are those in which the melt-spun polymer falls as a polymer mass without forming a yarn. Such fallen objects are caused by the polymer adhering to the nozzle plate, the leakage of the nozzle pack, and the like, and various measures have been taken, but cannot be completely eliminated. In particular, when such an abnormality occurs in the nonwoven fabric manufacturing process by the spunbond method, the aspirator for pulling the yarn is clogged, or the polymer lump is caught in the calender device used in the subsequent hot-pressing process, causing damage to the rollers. Etc. occur.
[0003]
The present inventors have previously proposed a detector for detecting the occurrence of such an abnormality and taking appropriate measures so as not to damage the apparatus (Japanese Utility Model Laid-Open No. 1-78171). However, since this device detects a decrease in illuminance due to the light reaching the detector being blocked by the dropped polymer lump, it reacts to things other than the polymer lump, such as yarn swaying. There was a problem of malfunction.
[0004]
[Problems to be solved by the invention]
The present invention is intended to solve the above problems and to provide an apparatus for selectively detecting only falling objects such as polymer lumps in the spinning process.
[0005]
[Means for Solving the Problems]
As a result of repeated studies to solve such problems, the present inventor has arrived at the present invention. That is, the present invention provides a light quantity comprising a light source unit arranged so as to sandwich the yarn group on the upstream side along the melt-spun yarn group and a light receiving unit comprising a self-scanning photodiode array. A set of detectors, a set of light quantity detectors comprising a light source part arranged so as to sandwich the yarn group downstream thereof and a light receiving part comprising a self-scanning photodiode array, and a light quantity detector on the upstream side A falling object detection device comprising: a time interval detection device for detecting a time interval between the occurrence time of the change in light intensity obtained in step 1 and the occurrence time of the change in light intensity obtained on the downstream side Is a summary.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0007]
The light source unit used in the present invention is not limited as long as a self-scanning photodiode array (hereinafter referred to as an image sensor) that is a light receiving unit irradiates light having a wavelength with sufficient sensitivity. As the type of light source, the shadow of the falling object to be detected needs to be generated on the light receiving surface of the image sensor, so that it emits a parallel light beam, a diffused light beam from a point light source, or a convergent light beam that converges to one point. Although it is ideal, it does not necessarily have to be a perfect parallel light beam, a diffused light beam, or a convergent light beam, as long as it can irradiate a light beam having directivity to the extent that a shadow is formed on the light receiving surface of the image sensor. It is also possible to use natural light as the light source as long as the above-described conditions are satisfied.
[0008]
An image sensor, which is a light receiving unit, is a device in which a plurality of photoelectric conversion elements are arranged in a line or a plane, and the signals of individual elements in the photoelectric conversion element group are extracted in a certain order in synchronization with external signals. A metal oxide silicon (MOS) type or a charge coupled device (CCD) type manufactured and commercially available using known techniques can be used. In order to achieve the object of the present invention, a linear image sensor in which photoelectric conversion elements are arranged in one row can sufficiently exhibit the effect, but a planar image sensor in which elements are arranged in two dimensions is used. You can also.
[0009]
The reason why the image sensor is used in the light quantity detector of the present invention is that the image sensor can obtain information on the position along the scanning direction. Usually, the spinneret used for spinning has a certain width, and the spun yarn also has a spread. The spinneret used in the nonwoven fabric manufacturing process by the spunbond method, in particular, has a rectangular shape that spreads in the sheet width direction. In the case of ordinary spot-shaped light receiving elements, a large number of light receiving elements are arranged in the horizontal direction. Otherwise, the position in the width direction of the fallen object that falls along the yarn cannot be known, and the intended effect cannot be obtained. If a large number of light receiving elements are arranged, it is possible in principle to obtain the same effect as in the present invention. However, in reality, only a very low position resolution can be obtained, which is not practical. On the other hand, when an image sensor is used, the same effect as when about 1000 elements are arranged in the range of several centimeters can be obtained, and an arbitrary optical system can be arranged immediately above the image sensor to thereby form an arbitrary space. There is an advantage that a resolution can be obtained.
[0010]
The resolution in the lateral direction (perpendicular to the direction of the yarn) is determined by the number of BITs of the image sensor and the optical system arranged immediately above, but can also be changed by processing the output signal of the image sensor. If a circuit is provided so that a plurality of continuous elements in the image sensor can be collectively regarded as one element, the spatial resolution can be lowered arbitrarily. The horizontal direction to detect in consideration of the number of elements (several hundreds to thousands) of ordinary image sensors, the space for spinning process, the available optical system, the position accuracy of the two sets of light quantity detectors arranged above and below, etc. The resolution may be determined, but it is usually preferable to set the resolution to about 5 to 20 mm at the center of the spun yarn. If this amount is too small, only those falling through two extremely limited points can be detected, and conversely if too large, malfunction increases.
[0011]
Usually, a fallen object such as a polymer lump falls almost along the yarn at a constant speed. Therefore, when a fallen object is generated, the fallen object is first detected by the detector disposed on the upstream side, and the detector disposed on the downstream side detects the fallen object after a certain time. In other cases, for example, when only the upstream detector detects and the downstream detector does not detect, or vice versa, both detectors detect the time If the interval exceeds a certain range, there is no occurrence of a fallen object, which is a false detection due to some other cause. Therefore, after the detector arranged on the upstream side detects a change (decrease) in the light intensity in a specific range, the detector installed downstream is delayed by a predetermined time range. If a change in the light intensity (decrease) is detected at the same position as the detector, it is assumed that the polymer mass has dropped, and if a signal or alarm is issued, only the occurrence of the fallen object is separated. Can be detected. That is, to detect the time interval between the occurrence time of the light intensity change obtained by the upstream light quantity detector and the occurrence time of the same light intensity change obtained downstream in the falling object detection device of the present invention. A time interval detector is provided.
[0012]
In order to emit a signal only when the upstream and downstream detectors are detected in this order in a certain time range with the detectors arranged above and below, for example, the upstream detector detects a fallen object. If a gate circuit that opens for a certain period of time after detection is provided, and the downstream detector operates only while the gate circuit is open, the detection of the downstream detector can be performed. This means that the occurrence of falling objects has been detected. Alternatively, a circuit that stores the time when the falling object is detected by the upstream side and the downstream side is provided, and only when the upstream side and the downstream side are detected in order within a certain time by arithmetic operation, selection is made. May be.
[0013]
FIG. 1 is a schematic view schematically showing an example of the apparatus of the present invention. The light source unit 1 and the image sensor 2 of the light receiving unit are disposed so as to sandwich the yarn 4 being spun under the nozzle 3 of the melt spinning apparatus. Further, the light source unit 1 and the image sensor 2 of the light receiving unit of the same kind are arranged. Another set is installed at a position away from the downstream side along the spun yarn. The output signal of each image sensor is processed independently, and a circuit that emits a signal when the amount of light reaching the light receiving surface of the image sensor falls below a certain level, that is, when a fallen object blocks the light from the light source. Connected. Further, the gate circuit 7 including the delay circuit 5 and the one-shot multivibrator circuit 6 obtains a gate signal that opens for a certain time after a certain amount of time after the upstream light amount detector detects a decrease in the light amount. The detection signal of the fallen object is obtained by taking the logical product of the light intensity reduction signal obtained through the same processing as the upstream side from the light receiving element on the side.
[0014]
【Example】
Next, the present invention will be specifically described by way of examples.
[0015]
As the light source part, four 12V-50W halogen lamps were arranged, and a rubbed glass diffusion plate was attached to the front. The size of the light emitting part as a light source is 15 cm high and 40 cm wide. The image sensor of the light receiving unit was 512BIT, and a photographic lens with a focal length of 50 mm was attached to the front surface, and the image on the nozzle center plane was arranged on the light receiving surface of the image sensor. By dividing 512 BIT into 16 parts, a spatial resolution of 12 mm was obtained at the center of the spun yarn. The output signal of the image sensor was used as a fallen object detection signal through a circuit that detects that the signal intensity has dropped below a predetermined level by a comparison circuit after removing the clock component of the sensor.
[0016]
The light source unit and the image sensor of the detection unit were arranged below the nozzle of the melt spinning apparatus so as to sandwich the yarn being spun (upstream photodetector). Furthermore, another set of the same type of light source unit and detector unit was disposed along the spun yarn at a position 30 cm downstream from the upstream photodetector (downstream photodetector). The output signals of each image sensor are processed independently and connected to a circuit that emits a signal when the amount of light reaching the light receiving surface drops below a certain level, that is, when a falling object blocks the light from the light source. . This detection signal, delay circuit, and gate circuit consisting of a one-shot multivibrator circuit adjust the gate circuit that opens for 0.5 sec after 0.1 sec after the upstream detector detects a decrease in light intensity. The logical product with the light intensity decrease signal of the light quantity detector on the side was used as the fallen object detection signal.
[0017]
Using the apparatus as described above, the ability to detect falling objects during the spinning process was tested. 256 polyethylene terephthalate filaments were melt-spun from a spinneret with a diameter of 192 mm, and 100 small spheres of polyethylene terephthalate with a diameter of 2 mm prepared in advance were dropped along the yarn being spun. The result was a detection rate of 100%.
[0018]
【The invention's effect】
According to the apparatus of the present invention, the fallen object is generated only when the fall of the light intensity is detected at regular time intervals by using the fact that the fallen object falls substantially along the yarn, and the light quantity detectors arranged above and below detect the light intensity at a constant time interval. Therefore, it is possible to detect only a fallen object due to spinning failure without erroneously detecting a fall of the light intensity due to yarn fluctuation or other factors in the spinning process as a fallen object.
[Brief description of the drawings]
FIG. 1 is a schematic view schematically showing an example of an apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light source part 2 Light-receiving part which consists of image sensors 3 Spinning nozzle 4 Yarn 5 Delay circuit 6 One shot multivibrator circuit 7 Gate circuit

Claims (1)

A set of light quantity detectors comprising a light source unit and a light receiving unit comprising a self-scanning photodiode array arranged so as to sandwich the yarn group upstream of the melt-spun yarn group, The light intensity obtained by one set of light quantity detectors comprising a light source part arranged so as to sandwich the yarn group on the downstream side and a light receiving part comprising a self-scanning photodiode array, and an upstream light quantity detector. A falling object detection device comprising: a time interval detection device for detecting a time interval between the occurrence time of the change and the occurrence time of the change in the same light intensity obtained downstream.

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