JPH10300680A - Method for inspecting foreign object in injected resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inspecting a foreign object that can accurately detect the size of the foreign object included in a resin that is circulated through a pipe and further can estimate the type of the foreign object based on its color. SOLUTION: Insulation resin such as polyethylene is injected from an extrusion machine 4 to the cavity of an extrusion mold 3 via a pipeline 20. The part of a transparent pipe 2 is provided halfway through the pipeline 20, an optical measurement means consisting of a laser light source 11 and a light receiver 12 is provided at the upstream side of a resin flow so that they oppose while pinching the transparent pipe 2 at the part of the transparent pipe 2, and a CCD camera 13 as a means for picking up an image is arranged at the downstream side of the resin flow so that the image of the transparent pipe 2 is picked up sideways. Then, when an optical measurement means recognizes the passage of the foreign object, the above image pick-up means is operated and an image containing the above foreign object is obtained and the three- dimensional shape of the foreign object is obtained from the two-dimensional information of the foreign object being obtained from the above optical measurement means and the above image information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for producing a crosslinked polyethylene insulated power cable (CV cable), an extrusion-molded connection portion and a block-molded connection portion, for example. And a method for directly inspecting for the presence of foreign matter.

[0002]

BACKGROUND OF THE INVENTION Extrusion molding type connection (EMJ) of CV cable and block molding type connection (BMJ)
In the formation of the block mold insulator used in J), a method of injecting a molten resin insulator from an extruder into a mold is employed. Here, since the electrical characteristics of EMJ and BMJ are greatly influenced by the inclusion of foreign matter in the insulator,
It is extremely important to check for foreign matter at the time of resin injection.

[0003] As such a foreign substance inspection method, an inspection by X-ray photography has been generally adopted. However, this method has a disadvantage that foreign substances such as cotton fibers which are insensitive to X-rays cannot be detected. is there. Therefore, as a method adopted in recent years, there are a laser beam system and a CCD camera system. In these methods, for example, a transparent portion using a transparent polyethylene resin and a glass window is provided in a part of a resin supply line from an extruder, and the entire amount of the resin injected into a mold is directly inspected in the transparent portion. It is.

In the laser beam system, the size of a foreign substance is calculated by irradiating a resin stream to be inspected with a laser beam and capturing a shadow blocked by the foreign substance as an image. Specifically, as shown in FIG. 1, a transparent glass tube 2 through which resin P flows.
Is irradiated with a laser beam from a laser projector 11 from the outer surface side of. That is, light from a laser oscillator 111 that generates a single-wavelength laser light is
Irradiation is performed so as to scan in the radial direction of the glass tube 2 in a state where the beam is narrowed down using the beam 2. On the other hand, the laser light is received by the light receiver 12 having the photomultiplier tube 121 on the opposite side of the glass tube 2. When the resin P flows including the foreign matter C, the shadow blocked by the foreign matter C is scanned every time, that is, the presence of the foreign matter is detected as a change in the amount of received light for each scanning line,
Based on this, the size of the foreign matter C is determined by, for example, creating and processing a screen.

Here, since the light passing through the glass tube 2 is a laser beam of a single wavelength, there is no refraction, and the image of the foreign matter C is not enlarged by the lens effect. However, glass tube 2
The resin P flowing inside is not uniform at all, but slow near the tube wall and fast at the center. Therefore, when analyzing an image captured by setting the reference of the flow velocity of the resin P at the center of the tube, when the foreign matter C passes near the center of the glass tube 2, the size thereof can be accurately determined, but the size of the foreign matter C near the tube wall can be determined. When passing through, there is a disadvantage that the shape of the foreign substance is recognized in a state of being elongated and deformed.

In the CCD camera system, a resin flow to be inspected is imaged by a camera, and an image taken from the camera is processed and analyzed to detect the size and color of the foreign matter. Specifically, as shown in FIG. 2, a transparent glass tube 2 in which a resin P is flowing is placed on a CCD camera 1 from an outer surface side thereof.
3, the video is recorded by the VTR 14 and processed by the image processing device 15, so that the size of the foreign matter C,
It is to know the color.

However, the CCD camera system requires a long processing time, cannot process the next screen during processing, and cannot perform continuous processing in real time. For this reason, a two-stage system is required in which the video is temporarily recorded on the VTR 14 and image processing is performed as needed. Also,
Since the glass tube 2 is photographed from the outside, the foreign matter C is magnified and imaged by the lens effect of the glass tube 2, so that there is a problem that the image needs to be corrected.

[0008] The present invention solves the above-mentioned problems, and can accurately determine the size of foreign matter contained in a resin flowing through a pipe.
It is another object of the present invention to provide a foreign matter inspection method capable of estimating the type of foreign matter based on the color.

[0009]

According to the method of the present invention, a transparent pipe portion is provided in a supply pipe of a resin to be injected into a predetermined location, and the transparent pipe is provided upstream of a resin flow. Optical measuring means for optically scanning one cross section to recognize the passage of foreign matter is provided, and imaging means for imaging the transparent tube from the side is provided on the downstream side, and the optical measuring means is provided with foreign matter. When the passage of the object is recognized, the image pickup means is operated to obtain an image containing the foreign matter.

Further, according to another method of the present invention, a transparent pipe portion is provided in a supply pipe of a resin to be injected into a predetermined location, and a cross section of the transparent pipe is provided upstream of the resin flow. Optically scanning means for optically scanning the part to recognize the two-dimensional size of the foreign matter from the passage of the foreign matter and the amount of light shielding, and imaging means for imaging the transparent tube from the side on the downstream side. When the optical measurement unit recognizes the passage of the foreign matter, the imaging unit is operated to obtain an image including the foreign matter, and the two-dimensional information and the image information of the foreign matter obtained from the optical measurement unit are obtained. A three-dimensional shape of the foreign matter is obtained.

Further, it is preferable that the color of the foreign matter is determined based on the image information.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The method of the present invention compensates for the disadvantages of both the laser beam system and the CCD camera system by organically linking them, and enables high-performance analysis of foreign substances in a shorter time.

FIG. 3 shows an example in which the present invention is applied to injection molding of a block mold insulator used for a block mold type connection (BMJ). In the figure, reference numeral 3 denotes an extrusion die in which a pair of cores 31 and 32 whose ends are subjected to a pencil ring imitating a cable to be connected are opposed to each other, and a metal cylindrical shape is provided on the opposed portion. By disposing the high-voltage shield electrode 33 made of a body, a spindle-shaped cavity 30 is formed on the inner surface of the mold 3. In addition, even in the case of the extrusion mold type connection part (EMJ), the cores 31 and 32 are used.
Can be applied in the same way, only replacing the actual cable.

An insulating resin such as polyethylene in a molten state is injected into the cavity 30 of the extrusion die 3 from the extruder 4 via a pipe 20. A part of the transparent pipe 2 is provided in the middle of the pipe 20 so that the injected resin can be observed from outside. As the transparent tube 2, a glass tube is preferable, but a heat-resistant transparent resin tube or the like may be used.

In the transparent tube 2 portion, an optical measuring means comprising a laser projector 11 and a light receiver 12 is provided on the upstream side of the resin flow so as to face the transparent tube 2 with the transparent tube 2 interposed therebetween. On the side, a CCD camera 13 as an imaging means is arranged so as to image the transparent tube 2 from the side. Note that S is illumination for the CCD camera 13. It is preferable that two or more CCD cameras are arranged at different positions, because the three-dimensional shape of the foreign matter can be easily captured.

Here, as described with reference to FIG. 1, a laser beam is emitted from the laser projector 11 so as to optically scan one cross section of the transparent tube 2. Then, the light transmitted through the transparent tube 2 is received by the light receiver 12, and if foreign matter is mixed in the resin, the foreign matter blocks the laser beam, causing a change in light receiving characteristics. The light receiving signal is transmitted to the processing device 5, where the light receiving characteristic, that is, the change in the light blocking amount due to the passage of the foreign matter, first recognizes the presence of the foreign matter, and further estimates the two-dimensional size of the foreign matter. Done.

As described with reference to FIG. 2, the CCD camera 13 is connected to a VTR 14 for recording a photographed image and an image processing device 15 to constitute an image pickup means. This imaging means is configured to operate in response to a foreign object recognition signal sent from the processing device 5. That is, when the processing device 5 of the optical measuring means recognizes the passage of the foreign matter, the image of the CCD camera 13 installed downstream of the resin flow is taken into the image processing device 15, thereby containing the foreign matter. An image is obtained efficiently. The image thus obtained is processed by the image processing device 15, and the three-dimensional shape of the foreign matter is obtained from the two-dimensional information of the foreign matter obtained from the optical measuring means and the image information. Usually,
The VTR 14 constantly records an image, and captures an image into the image processing device 15 only when a foreign object passing signal is received.

Here, the optical measuring means may serve only to detect the presence or absence of the passage of foreign matter, and the image pickup means may be operated based on the foreign matter passing signal to capture an image containing foreign matter. . In this case, the CCD camera 1
If two or more units 3 are arranged so that they can be viewed stereoscopically, the corresponding three-dimensional shape of the foreign matter can be known.

The above is the outline of the present invention. Hereinafter, the principle of detecting foreign matter and the like will be described in more detail. FIG. 4 is an explanatory diagram showing a foreign matter measurement state by an optical measurement means including a laser projector 11 and a light receiver 12. The casting resin (polyethylene commonly used in BMJs and the like, which is generally transparent) flowing through the transparent tube 2 is such that when flowing through a cylindrical tube, the center portion is fast (
(The length of the arrow is the speed.) Flow In comparison with this, there is a characteristic that the flow near the pipe wall is slow. Therefore, when foreign matters of the same shape exist at the center of the transparent tube 2 and on the tube wall side, the foreign matter on the tube wall side is naturally slow, and the distance between the foreign matters increases with time.

In such a situation, the laser projector 11
When a laser beam (beam) is scanned in a horizontal direction at regular intervals on one cross section of the transparent tube 2 and a signal that blocks a light beam by a foreign substance when passing through the inside of the transparent tube 2 is detected by the light receiver 12, it is illustrated. Such a foreign substance detection signal is obtained. And
When this signal is synthesized and processed and displayed, when the size of the foreign matter is determined based on the resin flow velocity at the center of the transparent tube 2, the foreign matter c1 near the center of the tube can be detected almost accurately, Since the foreign substance c2 interrupts the laser beam many times, it is detected vertically and elongated. In addition, there is a method of performing a partial correction by simulating the flow of the resin in the transparent tube 2, but the flow of the resin in the tube is not simple but difficult.

As described above, it is difficult to accurately grasp the three-dimensional shape of the foreign matter by using only the optical measuring means including the laser projector 11 and the light receiver 12. However,
At least the two-dimensional shapes d1 and d2 of the foreign matter c1 near the center and the foreign matter c2 on the tube wall side can be grasped almost accurately. That is, it is possible to detect how much the foreign matter having the cross-sectional sizes d1 and d2 has passed through one section of the transparent tube 2.

On the other hand, as described above, when an image is picked up by the CCD camera 13, the image is enlarged horizontally by the lens effect of the transparent tube 2. However, unlike the case where the resin flow is foreseen, the partial magnification by the lens effect can be obtained in advance, and there is an advantage that correction is easy.

Therefore, when the optical measuring means disposed on the upstream side recognizes that there is a foreign substance to be detected, the CCD camera 13 is operated to take in an image. More specifically, the first signal obtained by capturing the presence of a foreign substance by the optical measurement means is used as an image capture signal of the imaging means, and an image is input to the image processing device 15 by the CCD camera 13 to perform calculation processing. This image capture is performed after the foreign matter detection signal from the optical measuring means arrives and time-adjusted until the presence of foreign matter in the field of view of the CCD camera 13 based on the flow of the resin. In order to allow another signal to be input during the calculation, a necessary image capturing memory is installed in the image processing device 15 in advance so that processing can be performed at any time. It is preferable to keep it.

As a result, an image of the foreign matter contained in the resin flow as viewed from the side of the transparent tube 2 can be obtained. Since the foreign matter in this image is enlarged by the lens effect of the transparent tube 2, if the true value is calculated by taking into account the correction value in each part of the image which has been obtained in advance, the accurate value is obtained. It is possible to determine the size and shape (two-dimensional shape in the lateral direction) of the foreign matter as viewed from the side.

Then, arithmetic processing is performed from information on the two-dimensional shape (cross-sectional direction two-dimensional shape) of the foreign matter obtained by the optical measuring means and information on the lateral two-dimensional shape based on this image information. Thus, the three-dimensional shape of the foreign matter can be obtained. Here, the foreign substance information including the distortion caused by the resin flow velocity difference in the transparent tube detected by the optical measuring means is corrected by collating with the image information. Further, it is possible to estimate what the foreign substance is based on the color information included in the image information. According to this method, the size, shape, color, and the like of the foreign matter can be detected very quickly by suppressing the image processing to a necessary minimum as compared with the conventional method that always performs the image processing.

As described above, the laser projector 11
Is a CCD camera 1 on the upstream side of the resin flow in the transparent tube 2.
Although 3 is disposed on the downstream side, when laser light from the laser projector 11 is incident on the CCD camera 13, the captured image may be affected by the color of the laser light. Therefore, the laser projector 11 and the CCD camera 13 are arranged so as to be sufficiently spaced so as not to exert such an influence, or a light shielding device is provided between the two so as to take in the color of the foreign substance itself. There is a need.

The case where the present invention is applied to a connection portion of a CV cable such as an EMJ or a BMJ has been described above. In addition, for example, a supply line of an insulating layer resin in a cable manufacturing apparatus or a general molding apparatus for a resin cast body It can be suitably applied to the production of various products requiring high quality control by casting using a transparent resin, such as a resin supply line in the above.

[0028]

As described above, according to the method for inspecting foreign matter in injected resin according to the present invention, by using an inspection apparatus using a laser and an apparatus using a CCD camera together, the high detection sensitivity of the laser beam system is obtained. And high-speed processing capability,
It is possible to simultaneously utilize the ability of the CCD camera system to identify foreign substances. In other words, the CCD camera system, which requires a relatively long time for analysis but can detect accurate foreign matter information, is executed only when the presence of foreign matter is detected by the laser beam method. The substance can be estimated from the size, color, and shape, and harmful foreign substances can be determined.

Thus, for example, when the present invention is applied to the injection of a resin insulator into a mold in the formation of an EMJ of a CV cable or the formation of a block mold insulator used for a BMJ, foreign matter is quickly judged and injected. Since the quality of the resin to be performed can be determined at an early stage, there is an excellent effect that a material loss due to a defect and a waste of working time can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a foreign substance inspection by a laser beam method.

FIG. 2 is an explanatory diagram showing foreign substance inspection by a CCD camera system.

FIG. 3 is an explanatory view of a case where the present invention is incorporated in a BMJ block mold insulator molding apparatus.

FIG. 4 is an explanatory diagram for explaining a foreign matter detection state by a laser beam method.

[Explanation of symbols]

 Reference Signs List 11 laser projector 12 light receiver 13 CCD camera 2 transparent tube P resin C foreign matter

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02G 15/08 H02G 15/08 H

Claims (3)

[Claims] 1. A transparent pipe portion is provided in a supply pipe of a resin to be injected into a predetermined location, and a cross section of the transparent pipe is optically scanned upstream of the resin flow to recognize the passage of foreign matter. The optical measuring means is provided with imaging means for imaging the transparent tube from the side on the downstream side.When the optical measuring means recognizes the passage of the foreign matter, the imaging means is operated to remove the foreign matter. A method for inspecting foreign matter in an injected resin, characterized by obtaining an image containing the same. 2. A transparent pipe portion is provided in a supply pipe of a resin to be injected into a predetermined location, and a cross section of the transparent pipe is optically scanned on the upstream side of the resin flow to allow passage of foreign matter and light shielding amount. Optical measuring means for recognizing the two-dimensional size of the foreign matter from the camera, and imaging means for imaging the transparent tube from the side on the downstream side, and the optical measuring means recognizes the passage of the foreign matter. An image including the foreign matter is sometimes obtained by operating the imaging means, and a three-dimensional shape of the foreign matter is obtained from the two-dimensional information of the foreign matter obtained from the optical measuring means and the image information. Inspection method for foreign substances in injected resin. 3. The method according to claim 1, wherein the color of the foreign matter is further obtained based on the image information.