JPS5940146A - Method for detecting foreign matter in extrusion resin - Google Patents

Abstract

PURPOSE:To inspect all quantities of extruded resin and to improve detection sensitivity, by providing a transparent window for detection to a connecting part of the tip end of a cylinder of an extruder and a head and detecting a foreign matter by passing laser light through the resin by using this window. CONSTITUTION:A transparent window for inspection 6 is provided to a connecting part 5 of the tip end of a cylinder 3 with built in a screw 2 in an extruder 1 and a neck part of a crosshead 4. This window is formed in square e.g. at the part 5 and is attached transparent hard glass (e.g. boric acid glass) 7, 7 etc. having high pressure resistance and also high heat resistance at a part of both side wall faces facing each other and is formed by fixing with plates 8, 8. Further, a scanning device 9 emitting a laser light L is provided at one side of the window 6 and a photodetector 10 receiving the laser light L is provided at the other side of the window 6. For this reason e.g. in case of covering an electrically conductive body 11 with a polyethylene 12 containing a cross-linking agent, the laser light L from the scanning device 9 is irradiated to the polyethylene resin by heating through the window 6 and the transmitted laser light L is received by the photodetector 10.

Description

Detailed Description of the Invention The present invention provides a method for detecting foreign matter in extruded resin, which detects foreign matter such as baked resin (commonly known as amber or black) or metal contained in resin extruded by an extruder. It is related to.

For example, when extruding a resin such as polyethylene onto an electric wire conductor using an extruder, it is necessary to detect foreign substances such as amber, black, or the like in the extruded resin in order to ensure quality.

Conventionally, to detect this kind of foreign matter, the presence of foreign matter in the resin was detected by pulling out a part of the resin in the form of a tape from a part of the head after extrusion and irradiating it with laser light or the like.

However, when using this overflow method by partially pulling out the resin from the outside, the amount of overflow resin is only about 1wt of the total amount of extruded resin, and it is basically a sampling inspection to check the state of foreign matter in the entire resin. There were problems with accuracy, as there was a risk that the results would not be reflected accurately. Furthermore,
For example, in the case of polyethylene containing a crosslinking agent, the drawn resin has a temperature below its melting point at the body temperature, which causes problems such as crystallization of the resin, poor transparency, and reduced sensitivity for detecting foreign substances. In fact, it was not possible to distinguish the foreign substance unless it had a thick streak of 40 μm or more.

The present invention was made in view of these conventional problems, and its feature is that the inspection part is brought to the connection part (throat neck part) between the extrusion-like cylinder tip and the head. That is, if a transparent window for detection is provided at this connection, a source such as a laser beam will be emitted on both sides of this window. Basically, a full-volume inspection is carried out by installing a conduit device (light emitter) that emits light and a light receiver that receives this light, to accurately reflect the state of foreign matter in the entire extruded resin, and to check the contamination of the entire extruded resin. The good transparency of the resin improves the detection sensitivity of lying objects.

The present invention'f will be explained in more detail below with reference to an embodiment shown in the drawings.

FIG. 1 shows an example of an extruder useful in carrying out the present invention. This extruder 1 has a screw 2 installed at the tip of a cylinder 3 and a connecting part 5 as a throat neck of a crosshead 4. A transparent window 6 for detection is provided. Although the configuration of this window 6 is not particularly limited, for example, as shown in FIG.
A) As shown in (B), the connection part 5 is formed in a rectangular shape, and a transparent and highly pressure-resistant material (approximately i
ookg/CTn2) and has high heat resistance (about tao
'c) A hard glass (for example, boric acid glass) 1.1 or the like may be attached and fitted into the plate 8.8.

A scanner 9 that emits laser light is installed on one side of the window 6, and a light receiver 10 that receives the laser beam is installed on the other side.

With the device configured in this way, for example, the wire conductor 11
In the case of coating polyethylene 12 containing a crosslinking agent, in order to carry out the present invention, the laser light from the laser beam detector 9 is irradiated into the polyethylene resin through the window 6, and the transmitted laser light is transmitted to the light receiver 10. Just accept it. If the received light signal (information) of the 17-za light is subjected to various appropriate electrical processes, the presence of foreign matter such as burnt resin or metal can be detected very easily.

In addition to this detection, the cylinder 3 is equipped with a detection hole 6.
Since the 50 connecting portions of the head 40 are the portions through which the entire amount of extruded resin passes, virtually the entire amount is inspected, and a large amount of information regarding the inadvertent contamination of foreign matter can be obtained. That is, tRn
Detection information with a high degree of accuracy reflecting the true state of foreign matter contamination as a whole can be obtained. Furthermore, at this connection part, a crosslinking agent is added; 1! In the case of IJ ethylene, it is maintained at a temperature exceeding its melting point, and there is almost no appearance of rounding, polyethylene crystallization, or deterioration due to the influence of the outside air, and it has good transparency and extremely high sensitivity for detecting foreign substances. It will improve. Incidentally,
According to tests conducted by the present inventors, it was possible to detect 30 tt or more.

In the above examples, crosslinked cracked polyethylene has been explained as the resin used, but the present invention is not limited to this, and other resins such as nylon may be used as long as the resin has transparency that allows laser light to pass through. ,polypropylene,
Of course, it can also be applied to polycarbonate and the like. In addition, in the present invention, the laser light includes not only the so-called laser beam but also a detection action beam similar to a laser beam as long as it is a parallel light source that is permeable to the resin and can be detected. All you need to do is use a travel device and light receiver that are compatible with this.

As is clear from the above description, according to the present invention, a transparent window for detection is provided at the connection between the tip of the cylinder and the head of the extruder, and this window is utilized to allow laser light to pass through the resin. Since this method is designed to detect foreign substances in a single manner, it is possible to perform all 31 inspections of extruded resin, and to provide an excellent method for detecting foreign substances in extruded resin with high detection sensitivity. .

[Brief explanation of drawings]

FIG. 1 is a schematic partial vertical sectional view showing an example of an external extruder useful in carrying out the present invention, and FIG.
) are a cross-sectional view and a side view showing a detection window provided in the extruder of FIG. 1. DESCRIPTION OF SYMBOLS 1... Extruder, 3φ...Cylinder-14--Head, 5... Connection part, 6, e, window, 90, Scanner, 10... Light receiving k, 12, 1111 resin,
L...Lave light. 12 -257- 8 7

Claims (1)

[Claims] Connection part between extruder cylinder tip and head (throat neck)
A transparent detection window is provided on one side of the window, a scanner that emits a light beam such as a laser beam is installed on one side of the window, and a light receiver that receives the light beam is installed on the other side of the window. A method for detecting foreign matter in pressed resin, characterized in that the foreign matter is detected by irradiating the resin into the resin, allowing the light to pass through the resin, and receiving the transmitted light beam with the light receiver.