JP3345486B2 - Foreign object inspection method for polymer extruder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter inspection method for detecting the presence or absence of foreign matter in a polymer extruded from a polymer extruder, and more particularly to a method for detecting foreign matter continuously and with high accuracy. It relates to the inspection method.

[0002]

2. Description of the Related Art Crosslinked polyethylene insulated cables in which polyethylene is extruded and crosslinked by a polymer extruder have been widely used, and as the voltage has been increased, fine foreign substances in an insulator have become a problem. ing.

Conventionally, when inspecting for such foreign matter in an insulator, resin pellets before being put into an extruder are extracted, formed into a thin film, for example, on a separate line from cable manufacturing, and then a minute spot is formed. There has been adopted a method of irradiating a laser beam and detecting a foreign substance from a change in transmitted light, or a method of detecting a foreign substance from measurement of a shadow by strobe light.

[0004]

However, if the inspection of foreign matter as described above is performed on a separate line from the cable manufacturing, the foreign matter is indirectly grasped. There is a problem that the presence or absence of foreign matter cannot be accurately determined.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional circumstances, and is characterized by providing a light transmitting portion in a polymer flow path portion of a polymer extruder. At least the light- transmitting window and light-receiving window of the light- transmitting part
And a light transmitting member made of glass.
A heating means is provided on the outer periphery of the light portion, and a light source and an optical element for light projection are provided on one of the light transmitting portions to allow sheet-shaped parallel light to enter the polymer flow path, and to the other, By installing a light-receiving device for dividing and receiving the width of the parallel light into 1/1000 to 1/10000 and receiving the transmitted light of the incident light, foreign matter in the polymer is detected , and
At the time of detection, the object to be inspected passes through the light transmitting part by the heating means.
There the polymer of interest in the foreign matter inspection method of this <br/> a polymer extruder, characterized in that to maintain heated above its melting point.

[0006]

As described above, the light transmitting portion is provided in the channel portion of the extruder.
At the same time, by using a heating means in the light transmitting portion , foreign substances can be continuously detected with respect to the whole amount of the extruded polymer. Since the light is divided into 1000 and 1/10000 and light is received, not only the presence or absence of a foreign substance but also the size and the position of the foreign substance can be grasped. If a single-wavelength sheet-like laser beam is used as the light source,
The effect of diffraction due to foreign matter can be reduced. In addition, at the time of detection, the polymer passing through the light-transmitting part by heating means
Can be heated to and maintained above its melting point,
The effect of light scattering due to the temperature drop can be minimized.
In this case, foreign objects can be detected with higher accuracy.

[0007]

FIG. 1 is a schematic explanatory view showing one embodiment of an apparatus system for carrying out a foreign matter inspection method for a polymer extruder according to the present invention. In the figure, reference numeral 1 denotes an extruder to which pellets such as polyethylene are supplied, and the polymer melted therein by heating is continuously extruded from the lower left end in the figure by rotation of an internal screw. At the lower left end of the extruder 1, a light transmitting section 2 for detecting foreign matter in the polymer is provided, and a die or the like for manufacturing a cable is installed ahead of the light transmitting section 2.

The light transmitting section 2 is formed by a connecting pipe 3 as shown in FIG. 2, and the connecting pipe 3 is formed of a light transmitting member such as quartz glass or the like. At least the light projecting window 3a and the light receiving window 3b are also made of a light transmitting member such as quartz glass.

On the side of the light projecting window 3a, a light projecting light source 4 such as an LD and optical elements 5 and 6 such as a lens and a diffraction grating are installed. Is converted into a sheet-like parallel light [height (height) by the action of the optical elements 5 and 6.
Is substantially the same as the inner diameter of the conduit 3 and the width (thickness) of the light is 0.5-1 mm, and the light enters the polymer flow path P flowing through the connecting conduit 3. At the same time, on the side of the light receiving window 3b, a light receiving unit is formed by arranging a group of light receiving units for receiving the light by dividing the light receiving width (thickness) of the sheet-shaped parallel light into 1/1000 to 1/10000. Vessel 7
Is installed to receive the transmitted light of the light that has entered the polymer flow path P.

Due to the change in the amount of received light, foreign substances contained in the polymer can be continuously detected. At this time, the light receiving unit 7 in which a large number of light receiving unit groups are arranged allows the sheet-shaped parallel light in the width direction of 1/1000 to 1/100.
Since the light is divided into 00 and received, it is possible to detect not only the presence or absence of the foreign matter but also the size and the position of the foreign matter. Furthermore, if a single-wavelength sheet-like laser beam is used as the light source 4 for light projection, the influence of diffraction by foreign matter can be suppressed to a small degree, so that detection can be performed with high accuracy.

A photodetector 7 in which a large number of the photodetector groups are arranged.
Examples thereof include a CCD line sensor.

Further, when detecting the foreign matter, a heating means 8 such as an electric heater is provided in the light transmitting portion 2 so that the temperature of the polymer in the light transmitting portion 2 is higher than the melting point of the polymer, for example, 110 ° C. or higher for polyethylene. If the temperature is maintained at a uniform temperature of 160 ° C. or more for polypropylene, the effect of light scattering is reduced due to the homogenization of the polymer due to the melting of the crystal part, and a better light transmittance can be obtained. For this reason, it is possible to detect foreign substances with higher accuracy.

[0013]

As is clear from the above description, the following excellent effects can be obtained by the method for inspecting foreign matter of a polymer extruder according to the present invention. (1) First, since the light-transmitting portion is provided in the channel portion of the extruder, it is possible to continuously and directly detect foreign matter over the entire amount of the extruded polymer, that is, in the case of a cable, over the entire length of the cable. it can. (2) In addition, since the light receiving width is divided into 1/1000 to 1 / 10,000 at the same time as the sheet-like parallel light of the incident light and received, the light receiving width is not limited to the presence or absence of foreign matter.
The size and position of the foreign matter can also be detected. (3) Further, if a single-wavelength sheet-like laser beam is used as the light source for light projection, the effect of diffraction due to foreign matter can be suppressed to a small degree, so that detection with higher precision becomes possible. (4) Further, if the temperature in the light-transmitting portion of the polymer flow path portion is maintained at a uniform temperature equal to or higher than the melting point of the polymer, the influence of light scattering can be minimized, so that the detection accuracy can be further improved. Improvement can be achieved.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional schematic perspective view showing an apparatus system for performing a foreign matter inspection method for a polymer extruder according to the present invention.

FIG. 2 is a partial cross-sectional schematic plan view showing a light transmitting unit of FIG. 1;

[Description of Signs] 1 Extruder 2 Translucent part 3 Connection conduit 3a Projection window 3b Receiving window 4 Projection light source 5 Optical element 6 Optical element 7 Receiver 8 Heating means P Polymer flow path

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Hasegawa 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. −3456 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 47/00-47/96 G01N 21/49 G01N 21/85

Claims (1)

(57) [Claims] 1. A light- transmitting portion is provided in a polymer flow path portion of a polymer extruder, and at least a light- transmitting window portion of the light- transmitting portion is received.
When the light window is made of glass light transmissive material,
A heating means is provided on the outer periphery of the light transmitting portion, and a light source and an optical element for projecting light are installed on one of the light transmitting portions so that sheet-shaped parallel light is introduced into the polymer flow path. Light,
On the other hand, the width of the parallel light is 1/1000 to 1/1000.
By installing a light receiver for receiving light divided into 0 and receiving the transmitted light of the incident light, foreign matter in the polymer is detected ,
In addition, at the time of the detection, the light-transmitting portion is moved by the heating means.
Heating the polymer to be inspected to above its melting point
A foreign matter inspection method for a polymer extruder, characterized by maintaining .