JP2001305085A - Method and device for measuring purity of plastic piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily measure the purity of a selected plastic piece. SOLUTION: Plastic pieces spread all over the bottom face part of a heating tray 6 are heated from the bottom face part. The infrared images of the plastic pieces in one or both of raised temperature state and the heat-radiated temperature lowered state after being heated to a specified temperature are picked up by a camera part 11 of a thermographic device 2. A purity arithmetic processing part 14 of a purity detector 3 extracts the plastic pieces with different heat conductivity, from the temperature distribution of the plastic pieces in the infrared image, and measures the purity of plastic from the area ratio of plastic pieces with different heat conductivity in the total area of the plastic pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the purity of plastics, for example, for measuring the sorting accuracy of plastic pieces that have been recycled and sorted by material.

[0002]

2. Description of the Related Art For example, a resin surface is irradiated with infrared rays,
In some cases, the reflected wave is detected to measure the material component of the resin.

[0003]

However, the above-mentioned conventional measuring device measures the intensity by irradiating a wide surface such as a plastic bottle with infrared rays, and measures the purity of the separated and collected material of the crushed plastic pieces. Could not be done.

An object of the present invention is to solve the above-mentioned problems and to provide a method and an apparatus for measuring the purity of a plastic piece which can measure the purity of a selected plastic piece with high accuracy.

[0005]

In order to achieve the above object, a method for measuring the purity of a plastic piece according to the first aspect of the present invention is a method for heating a plastic piece spread on a bottom surface to increase the temperature, After heating the spread plastic pieces, take one or both infrared images in a state where the temperature decreases by cooling and extract plastic pieces with different thermal conductivity from the temperature distribution of the plastic pieces in this infrared image, The purity of the plastic is measured from the ratio of the area of the plastic pieces having different thermal conductivities in the entire area of the piece.

[0006] According to the above configuration, when the spread plastic pieces are heated, the temperature increases in order from the one having the highest thermal conductivity. In addition, when cooling from a heated state, the material having good thermal conductivity is cooled and the temperature drops. In this way, an infrared image is taken using the inherent thermal conductivity of the plastic piece, and the purity of the plastic piece can be easily and accurately measured from the thermal image.

According to a second aspect of the present invention, there is provided an apparatus for measuring the purity of a plastic piece, the heating tray having a heating means for laying the plastic piece on the bottom, and the heating and cooling states of the plastic piece laid on the bottom of the heating tray. A thermography device that captures at least one of the images by a camera unit, outputs an infrared image signal, processes the infrared image signal in an image processing unit to form an infrared image, and a plastic piece obtained from the infrared image by the image processing unit And a purity detection device having a purity calculation processing unit for measuring the purity by calculating the mixing ratio of the plastic pieces having different thermal conductivity from the temperature distribution.

According to the above construction, when the plastic pieces spread on the heating tray are heated, the temperature rises by increasing the temperature in ascending order of the heat conductivity, and when the heat is radiated or cooled from a predetermined heating state, the heat conduction is reduced. It cools from a good rate and the temperature drops. By utilizing the inherent thermal conductivity of the plastic piece in this way, an infrared image of the heated or cooled plastic piece is taken by a thermographic device, and the purity can be easily and accurately measured from the thermal image. .

Further, in the plastic piece purity measuring device according to the present invention, the plastic piece is photographed in both the heating and cooling states and the cooling and cooling state, and the purity of the plastic piece is measured from both infrared images. Is what you do.

[0010] According to the above configuration, since the plastic pieces having different thermal conductivity are extracted from both the temperature distribution of the rise and the fall of the temperature, the purity can be measured more accurately.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the apparatus for measuring the purity of a plastic piece according to the present invention will be described with reference to FIG.

This purity measuring device comprises a heat transfer vessel 1, a thermographic device 2, and a purity detecting device 3.
The heat transfer container 1 has a heating tray 6 that is crushed into a substantially uniform size and is spread so that the plastic pieces selected by the sorting device do not overlap the bottom portion, and the bottom portion of the heating tray 6 can be uniformly heated. A heater 7 as a heating means, and a cover container 8 that covers the heating tray 6 and the heater 7 are provided. A power supply device 10 is connected to the heater 7 via a power switch 9.

The thermographic apparatus 2 is provided through the ceiling of the cover container 8 and captures an image of the entire bottom surface of the heating tray 6 to output an infrared image signal. Processing unit 1 for forming an infrared image of a plastic piece on the bottom part by using
2 and a memory 13 for storing signals processed by the image processing unit 12.

The purity detecting device 3 inputs an infrared image showing the temperature distribution of the plastic pieces from the memory 13 and extracts the parts of the plastic pieces whose rising temperature or falling temperature differs from the peripheral portion due to the different thermal conductivity. A purity calculation processing unit 14 for calculating the ratio of the occupied area of the plastic pieces having different thermal conductivities to the area of the entire plastic piece to obtain the purity; a display device 15 for displaying an image of the purity calculation processing unit 14; It comprises a processing unit 14, a camera unit 12, and an operation panel 16 for transmitting an operation signal to the power switch 9.

As shown in FIG. 3, the purity calculating section 14 starts heating or cooling based on the thermal conductivity of each plastic material shown in FIG. Acquire later image data (STEP
1) Then, the image data is binarized (STEP
2). Then, the pixels of the high temperature part or the low temperature part are extracted and the number of pixels is measured (STEP 3). Further, the ratio of the number of pixels of the plastic piece to the number of pixels = purity is calculated (STEP 4).

The plastic pieces are crushed almost uniformly, and the bulk specific gravity of the plastic pieces is 0.5 to
Since the specific gravity is 0.6 at 0.6 and the specific gravity is about 1.0, the gap between plastic supplements spread on the bottom of the heating tray 6 is about 40 to 50% of the entire bottom.
In the entire area of the binarized image, an appropriate value is selected for the entire plastic piece in the range of 50 to 60% according to the detection state.

According to the above embodiment, the purity of the easily separated plastic pieces can be easily and accurately measured by using the thermography apparatus, and the plastic pieces separated and recovered based on the purity can be measured. It is possible to accurately select a reproduction use purpose.

[0018]

As described above, according to the method for measuring the purity of plastic pieces according to the first aspect, when the spread plastic pieces are heated, the temperature rises in order from the one having the highest thermal conductivity and the temperature rises. Also, when cooling from a heated state,
The material having a good thermal conductivity is cooled to lower the temperature. In this way, an infrared image is taken using the inherent thermal conductivity of the plastic piece, and the purity of the plastic piece can be easily and accurately measured from the thermal image.

According to the apparatus for measuring the purity of a plastic piece according to the second aspect, when the plastic pieces spread on the heating tray are heated, the temperature rises in order from the one having the highest thermal conductivity, and the temperature rises. When heat is radiated or cooled from the heating state, the material having a good thermal conductivity is cooled and the temperature drops. By utilizing the inherent thermal conductivity of the plastic piece in this way, an infrared image of the heated or cooled plastic piece is taken by a thermographic device, and the purity can be easily and accurately measured from the thermal image. .

Further, according to the apparatus for measuring the purity of a plastic piece according to the third aspect, plastic pieces having different thermal conductivities are extracted from the temperature distribution of both rise and fall of the temperature, so that the purity can be measured more accurately.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a plastic piece purity measuring apparatus according to the present invention.

FIG. 2 is a view showing the thermal conductivity of a typical plastic used by the purity measuring device.

FIG. 3 is a flowchart showing an operation of a purity calculation processing unit of the purity measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat transfer container 2 Thermography device 3 Purity detection device 6 Heating tray 7 Heater 11 Camera part 12 Image processing part 14 Purity calculation processing part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hidehiko Maehata 1-7-89 Minami Kohoku, Suminoe-ku, Osaka-shi, Osaka F-term in Hitachi Zosen Corporation (reference) 2G040 AA02 AB08 AB09 BA02 BA25 CA02 CA12 CA23 CB03 DA06 DA12 DA15 EA02 EB02 EC03 FA04 HA02 HA16

Claims (3)

[Claims] An infrared image of one or both of a state in which the temperature is increased by heating a plastic piece spread on the bottom surface and a state in which the temperature is lowered by cooling the plastic piece spread on the bottom portion is described. By taking an image and extracting the plastic pieces having different thermal conductivity from the temperature distribution of the plastic pieces in this infrared image, measuring the purity of the plastic from the ratio of the area of the plastic pieces having different thermal conductivity in the entire area of the plastic piece. Characteristic method of measuring the purity of plastic pieces. 2. A heating tray for laying plastic pieces on a bottom part having a heating means, and an infrared image obtained by imaging at least one of a heating state and a cooling state of the plastic pieces laid on the bottom part of the heating tray by a camera part. A thermographic device that outputs a signal and processes the infrared image signal in an image processing unit to form an infrared image; and a plastic piece having a different thermal conductivity from a temperature distribution of the plastic piece obtained from the infrared image by the image processing unit. And a purity detecting device having a purity calculating section for calculating the purity by calculating the mixing ratio of the plastic pieces. 3. The apparatus for measuring the purity of a plastic piece according to claim 2, wherein both the heating and cooling states and the cooling and cooling states of the plastic piece are imaged, and the purity of the plastic piece is calculated from both infrared images. .