JP2016065855A - Resin piece selection method and resin piece selection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin piece selection method and a resin piece selection device that are used for selecting a recyclable resin piece from among mixed crushed pieces including various kinds of materials at high speed.SOLUTION: This selection method includes: an X-ray inspection step of exposing a resin piece to an X-ray which includes a first X-ray and a second X-ray differing in an energy range, and then measuring first penetration intensity being intensity of the first X-ray penetrating the resin piece and second penetration intensity being intensity of the second X-ray penetrating the resin piece; a first determination step of using the first penetration intensity to determine whether or not the resin piece is a candidate for a useful resin piece; a second determination step of using a difference value obtained from the first penetration intensity and the second penetration intensity to determine whether or not the resin piece determined to be the candidate for the useful resin piece is the useful resin piece by the first determination step; and a collection step of collecting the resin piece determined to be useful on the basis of a determination result in the second determination step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin piece sorting method and a resin piece sorting apparatus, and in particular, contains a specific element from a large number of resin pieces having various shapes and a mixture of various types of resin and foreign substances other than resin. The present invention relates to a method for sorting resin pieces to remove the resin pieces and a resin piece sorting apparatus using the method.

  When an object made of a substance is irradiated with X-rays, the amount of X-rays absorbed by the object is determined by the type and density of elements contained in the substance and the thickness of the object. When you want to distinguish multiple objects of different materials according to X-ray absorption characteristics, it is necessary to consider the influence of the elements contained in the object on X-ray absorption and the influence of the thickness of the object on X-ray absorption There is. When the influence of the former is larger than the influence of the latter, the material of the object can be determined from the X-ray transmittance. For example, when determining a metal foreign object contained in food, it is possible to determine the presence or absence of a metal foreign object only by acquiring an X-ray transmission image.

  However, when the element numbers of the elements contained in the respective samples are close, the influence of the thickness of the object on the X-ray absorption cannot be ignored compared to the influence of the contained elements on the X-ray absorption. Therefore, in principle, it is difficult to distinguish substances contained in each object from the amount of X-ray absorption for a large number of objects having different shapes.

  When a substance having a similar X-ray absorption tendency is contained inside by X-ray absorption measurement, for example, as a technique for enabling determination of bone in a body tissue or determination of bone foreign matter in food, the energy subtraction method is Are known. In the energy subtraction method, by using two types of X-rays having different energy regions, the absorption characteristics of each X-ray are measured, and the difference between the contained substances can be detected with high sensitivity by taking the difference. Specifically, with respect to the measurement object, the absorption characteristics by low energy X-rays and the absorption characteristics by high energy X-rays are measured, the natural logarithm of each obtained transmittance is taken, and appropriately selected parameters are used. Difference processing is performed after weighting. As will be described later, by appropriately selecting the weighting coefficient, the difference value for a specific substance in the object to be measured can be theoretically zero regardless of the thickness of the object to be measured. It is possible to distinguish a substance from other substances with high sensitivity.

  In order to use the energy subtraction method, it is necessary to measure absorption by two types of X-rays having different energies, and in the past, two X-ray sources and two X-ray sensors were used. At present, dual energy X-ray sensors that can detect absorption of low-energy X-rays and high-energy X-rays using an X-ray source that generates continuous X-rays are used. By using one X-ray source and one dual energy X-ray sensor, the energy subtraction method can be used.

  In order to make maximum use of the effect of the energy subtraction method, it is necessary to set the weighting parameters optimally. As a method for automatically setting parameters, a method of performing independent component analysis after acquiring an image based on X-ray transmission intensity has been proposed (see, for example, Patent Document 1). According to this method, an image obtained by emphasizing only a substance to be determined is obtained through a series of processes of image acquisition, image conversion for independent component analysis, setting parameters from the converted image, and acquiring an image in which only foreign matter is emphasized. Can be acquired.

  On the other hand, in the waste plastic recycling business, resin pieces containing additives that interfere with recycling and metal foreign objects to be removed from various waste plastic resin pieces are accurately classified and useful for recycling. There is a need for a technology that sorts only resin pieces.

JP 2010-91483 A

  Applying the energy subtraction method described above to a recycling plant for resin materials generated from waste home appliances, etc. to distinguish useful resin materials from those that contain additives that are not suitable for recycling The following points need to be considered.

  1. The resin piece that is the object of the sorting operation is a mixture of resin pieces obtained by crushing resin parts containing various additive materials. A wide variety of additive materials to be removed in sorting operations.

  2. Since multiple determinations are made individually for a large number of resin pieces that are irregularly arranged on the transport device, it is necessary to perform simultaneous multiple processing at high speed.

  Examples of additives that hinder the recycling of resin materials include glass fibers and brominated flame retardants. Industrially, it is necessary to determine and remove a resin containing additives having different properties using a single apparatus.

  Moreover, in order to perform simultaneous selection of a plurality of resin pieces at high speed, it is not appropriate to use advanced processing such as image diagnosis. Therefore, for each measurement value of the target resin piece, it is necessary to select by directly using the difference value calculated by the energy subtraction method. The inventor of the present application accurately discriminates by comparing with a preset threshold when there are a plurality of types of additive materials to be removed and the absorption tendency of the elements constituting each additive material with respect to X-rays is different. I found that there is a case that can not be.

  In particular, when the energy subtraction method is applied to a sorting operation in a resin material recycling factory, there are cases where metal is included as a foreign material to be measured.

  The present invention has been made in order to solve the above-described problems. Among resin pieces containing various materials, a recyclable resin piece, a resin piece and a resin that are not suitable for recycling are provided. It is an object of the present invention to provide a sorting method for sorting resin pieces that can be recycled by classifying foreign materials other than those at high speed, and a sorting device for sorting resin pieces using the method.

  In addition, selection means here the act which selects the thing (utility material) judged to be useful for any reason which can be recycled.

  According to the resin piece sorting method of the present invention, the resin piece is irradiated with X-rays including the first X-ray and the second X-ray having different energy ranges, and the intensity of the first X-ray transmitted through the resin piece. X-ray inspection process for measuring the first transmission intensity, and the second transmission intensity, which is the intensity of the second X-ray transmitted through the resin piece, and the resin in which the resin piece is useful by using the first transmission intensity Obtained from the first transmission intensity and the second transmission intensity for the resin piece determined to be a candidate for a useful resin piece by the first determination step for determining whether or not it is a candidate for the piece, and the first determination step. The second determination step for determining whether or not the resin piece is useful using the difference value obtained, and the collection for collecting the resin piece determined to be useful based on the determination result of the second determination step A process.

  Moreover, the resin piece sorting apparatus according to the present invention includes an X-ray irradiation that irradiates the resin piece with an X-ray including a first X-ray and a second X-ray having different energy ranges. X-ray intensity measurement for measuring the first transmission intensity, which is the intensity of the first X-ray transmitted through the resin piece, and the second transmission intensity, which is the intensity of the second X-ray transmitted through the resin piece The first determination unit that determines whether the resin piece is a candidate for a useful resin piece using the first transmission intensity and the first transmission intensity, and the first determination unit determines that the resin piece is a candidate for a useful resin piece The determination result of the 2nd determination part which determines whether it is a useful resin piece using the difference value obtained from the 1st transmission intensity and the 2nd transmission intensity about the done resin piece, and the 2nd determination part And a sorting unit for sorting and collecting the resin pieces.

  According to the resin piece sorting method of the present invention, the X-ray transmission intensity is measured and determined by the first determination step as the first step, and then determined by the second determination step using the energy subtraction method as the second step. By doing so, it is possible to quickly distinguish between a resin piece to be collected and a foreign material such as a resin piece or metal to be removed. Further, even when there are a plurality of elements contained in the resin piece, the resin piece can be selected by making a determination with high accuracy.

It is a determination flowchart for determination of a useful resin piece and a removal target in Embodiment 1 of this invention. It is a figure which shows the relationship between the transmission intensity of a low energy X-ray, and the thickness of a resin piece in Embodiment 1 of this invention. It is a figure which shows the relationship between the difference value and thickness about the measuring object after passing through the 1st determination process for demonstrating the determination method which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the difference value S and the thickness of a measuring object for demonstrating the determination method of Embodiment 1 of this invention. It is a determination flowchart for determination of a useful resin piece and a removal target in Embodiment 2 of this invention. It is a figure which shows the example of the area | region 1 set to the transmission intensity | strength of the low energy X-ray in Embodiment 2 of this invention. It is a figure which shows the example of the area | region 2 set to the difference value in Embodiment 2 of this invention. It is a figure which shows the adjustment method of the threshold value 1 with respect to the transmission intensity of a low energy X-ray in Embodiment 2 of this invention. It is a figure which shows the relationship between the transmission intensity of a low energy X-ray, and a difference value for demonstrating the automatic adjustment of a difference value parameter in Embodiment 2 of this invention. It is a figure which shows the relationship between the transmission intensity of a low energy X-ray, and a difference value for demonstrating the automatic adjustment of a difference value parameter in Embodiment 2 of this invention. It is a determination flowchart for determination of the useful resin piece and removal target in Embodiment 3 of this invention. It is a figure which shows the relationship between the transmission intensity of a low energy X-ray, and the thickness of a resin piece in Embodiment 3 of this invention. It is a figure which shows the relationship between the difference value S and the thickness of a resin piece in Embodiment 3 of this invention. It is a figure which shows typically the structure of the selection apparatus which concerns on Embodiment 4 of this invention. It is a figure which shows typically the structure of the selection apparatus which concerns on Embodiment 5 of this invention. It is a figure which shows typically the structure of the selection apparatus which concerns on Embodiment 6 of this invention.

  Hereinafter, embodiments of the invention will be described with reference to the drawings. Since the present invention is particularly effective when used as a sorting target for sorting resin pieces used for recycling from waste plastic, in the following, an example of using waste plastic resin pieces as a sorting target will be described. Will be explained.

Embodiment 1 FIG.
Many plastic materials used for home appliances or the like contain glass fibers in order to increase the strength, or add a flame retardant to impart flame retardancy. To collect waste plastic from waste home appliances and use it again as a plastic material, exclude resin pieces made of plastic containing these additives, and select only resin pieces made of useful plastic materials. There is a need to. Here, a resin piece that does not contain an additive or the like that hinders recycling and is desirably selected for use in recycling is referred to as a “useful resin piece”. The “additive” in this specification is an element having a small element number (here, hydrogen (H), carbon (C), nitrogen (N), oxygen (O)) which is a main constituent element of the resin. ) Refers to additives having other elements. Moreover, since it can utilize for recycling if there is little content of an additive, you may handle as a useful resin piece.

  In the case where the resin piece contains glass fiber, an element such as silicon (Si) having a relatively high energy X-ray absorption rate is lower than that of a relatively low energy X-ray absorption rate. Contains. Hereinafter, such a resin piece is referred to as an X-ray absorbing small foreign material.

  Further, since the flame retardant contains an element such as bromine (Br) as an additive, the absorption rate of relatively high energy X-rays does not decrease compared to the absorption rate of relatively low energy X-rays. Needless to say, foreign matter made of metal itself also has a large X-ray absorption. Hereinafter, the resin piece to which bromine is added and the metal piece are collectively referred to as X-ray absorbing large foreign matter. The X-ray absorbing small foreign matter and the X-ray absorbing large foreign matter are collectively referred to as a removal object.

  FIG. 1 is a diagram showing a determination flowchart for determining useful resin pieces and removal objects in Embodiment 1 for carrying out the present invention.

First, in step S11, the X-ray irradiation unit irradiates the measurement target with low energy X-rays and high energy X-rays having different energy ranges, and the respective transmission intensities I _H and I _L are measured by the X-ray sensor. get. That is, step S11 is an X-ray inspection process. Here, the low energy X-ray and the high energy X-ray can use different wavelength regions in the continuous X-ray spectrum. Ideally, it is desirable to measure the transmission intensity of each X-ray at the same point and at the same timing. The X-ray irradiation unit irradiates X-rays using an X-ray source that generates continuous X-rays, and simultaneously measures low-energy X-ray transmission intensity I _L and high-energy X-ray transmission intensity I _H. By using an X-ray sensor that can perform the above-described measurement, the above-described measurement can be performed. As such an X-ray sensor, for example, there is one having a structure in which two types of photodiode arrays with scintillators are combined in two upper and lower stages. The upper array detects low energy X-rays, and the lower array detects high energy X-rays transmitted through the upper stage.

Next, in step S12, a control device such as a sequencer compares the low-energy X-ray transmission intensity _IL with a preset threshold value 1 (first determination step). Here, as a setting method of the threshold value 1, X-ray transmission intensity is measured in advance for a useful resin piece group having a maximum thickness that can be taken by a known useful resin piece, and all useful resin pieces are obtained. A method in which a value lower than the X-ray transmission intensity is set as the threshold value 1 is used. When the threshold value 1 set in this way is used, the X-ray transmission intensity is higher than the threshold value 1 for all useful resin pieces.

Controller, X-ray transmission intensity I _L and the threshold 1 and the result of the comparison, is smaller than the threshold value 1 is the X-ray transmission intensity I _L (S12: YES), the process proceeds to step S31.

In step S31, the control device determines that the measurement target is a removal target.
If the X-ray transmission intensity _IL is equal to or greater than the threshold 1 (S12: NO), the control device determines that the measurement target is a useful resin piece candidate. Since the resin piece not containing an additive is composed of an element having a small element number, when compared with a resin piece having the same thickness, the resin containing the other elements in the additive has more X-rays. Absorb much.

  FIG. 2 is a diagram showing the relationship between the transmission intensity of low-energy X-rays and the thickness of the resin piece, and shows a determination method for the threshold value 1. FIG. 2 shows the results of an experiment conducted to verify the principle. The horizontal axis in FIG. 2 indicates the thickness of the resin piece that is the measurement object, and the vertical axis in FIG. 2 indicates the transmission intensity of low energy X-rays. Here, the X-ray transmission intensity (incident intensity) when there is no object to be measured is set to 4095. The points indicated by circles show the results for useful resin pieces, the points indicated by triangles indicate the results for X-ray absorbing small foreign matter, and the points indicated by squares indicate the results for X-ray absorbing large foreign matter. Each point indicates a value when the thickness is increased by 1 mm for each type of measurement target, and the results of the same type of measurement target are connected by a solid line.

  In the measurement of FIG. 2, the useful resin piece contains no additive. A resin containing glass fiber (containing Si as an element) as an additive is used as an X-ray absorbing small foreign material, and a brominated flame retardant (containing Br as an element) is used as an X-ray absorbing large foreign material. A resin containing 5 wt% was used. Also, a tungsten target X-ray tube is used as the X-ray source, and X-rays are generated at a tube voltage of 50 kV. A tungsten target is capable of generating high intensity continuous X-rays and is an appropriate X-ray source for the present application. In addition, rhodium (Rh), molybdenum (Mo), chromium (Cr) and other targets that generate not only continuous X-rays but also characteristic X-rays at a tube voltage of 50 kV or less take into account the absorption band of the measurement object. It is possible to use above.

  In FIG. 2, a broken line written in the horizontal axis direction indicates a threshold value 1 set in advance. The control apparatus determines that the measurement target having an X-ray transmission intensity lower than the threshold 1 is a removal target, and determines the measurement target having an X-ray transmission intensity equal to or higher than the threshold 1 as a selection target candidate. Note that a measurement target having an X-ray transmission intensity of threshold value 1 may be determined as a removal target.

  In the case of a resin piece using waste plastic as a raw material, the size of the resin piece is not uniform, and since there are several types of plastic as a material, the actual transmission intensity value varies depending on various factors. Therefore, if the threshold value 1 is set low, the recovery rate of useful resin pieces increases, but the removal target with a high X-ray transmission intensity and a small thickness is mixed. On the other hand, when the threshold value 1 is increased, the recovery rate of useful resin pieces decreases, but many removal objects can be removed.

  That is, as is apparent from FIG. 2, there are objects to be removed that cannot be removed by determining the X-ray transmission intensity. This is because X-ray absorption is affected not only by the elements contained in the measurement object but also by the thickness of the measurement object. If it is not determined in step S12 that the measurement target is a removal target, the process proceeds to a difference value calculation step in step S13.

In step S13, the control device calculates the difference value S by the energy subtraction method using the low energy X-ray transmission intensity I _L and the high energy X-ray transmission intensity I _H acquired in step S11. Here, a method of calculating the difference value will be specifically described.

The low energy X-ray transmission intensity of the measurement object is I _L , the high energy X-ray transmission intensity is I _H , the attenuation coefficient for low energy X-ray is μ _L , the attenuation coefficient for high energy X-ray is μ _H , and the irradiation X-ray If the intensity is I0 and the thickness of the object to be measured is t, the following expressions (1) and (2) are established. FIG. 2 shows t in the formula (1) on the horizontal axis and _IL on the vertical axis.

  When natural logarithms are taken for both sides of the expressions (1) and (2), the following expressions (3) and (4) are obtained.

  A value obtained by multiplying each value of Expression (3) and Expression (4) by a difference value parameter, which is an arbitrary constant, is referred to as a difference value. If the difference value parameter is k and the difference value is S, the difference value is obtained by the following equation (5).

In order to actually calculate the difference value S, it is necessary to set the difference value parameter k in advance. As can be seen from Equation (5), the difference value S is the product of the term (μ _L −k · μ _H ) calculated from the density of the measurement object and the attenuation coefficient depending on the material of the contained element and the term of the thickness t. Basically, it is a value affected by the thickness t, similarly to the X-ray transmission intensity. However, when k is set such that (μ _L −k · μ _H ) is 0, S = 0 can be set regardless of the thickness t of the measurement object. By setting k such that S = 0 for a useful resin piece, it is theoretically possible to determine that a value other than S = 0 is a removal target. As an example of the setting method of the difference value parameter k, a plurality of low energy X-ray transmission intensities and high energy X-ray transmission intensities are measured in advance for a known useful resin piece, and the average value of the difference values S is 0 most. A method of setting a value close to is mentioned.

  Step S14 is the second stage determination (second determination step) in which the difference value S calculated in this way is compared with the threshold value 2 for the difference value. As for the setting method of the threshold value 2, as in the case of the threshold value 1, the difference value S is calculated using the difference value parameter k set in advance as described above for the previously known useful resin pieces, and all useful values are calculated. A method of setting a value smaller than the difference value S of the resin pieces as the threshold value 2 is used.

  FIG. 3 is a diagram showing the relationship between the difference value and the thickness of the measurement object after the first determination step, and the situation when the difference value S of the measurement object and the threshold value 2 are compared in step S14. Is shown. In FIG. 3, the horizontal axis represents the thickness of the measurement object, and the vertical axis represents the difference value S. As in FIG. 2, the points indicated by circles are the results for useful resin pieces, the points indicated by triangles are the results for X-ray absorbing small foreign matter, and the points indicated by squares are the results for X-ray absorbing large foreign matter. Indicates. Among the points of the X-ray absorbing small foreign matter and the X-ray absorbing large foreign matter, the point having a large thickness is not shown in FIG. 3 since the determination has already been completed in step S12. As the point of the useful resin piece shows, when the difference value parameter set by the above-described method is used, the difference value S of the useful resin piece does not depend on the thickness of the useful resin piece and is a value around 0. I take the. Therefore, by setting the threshold 2 as shown by the dotted line in FIG. 3, it is possible to determine useful resin pieces and removal objects with high sensitivity.

  In step S14, if the control device compares the difference value S of the measurement object with the threshold value 2 and the difference value S of the measurement object is smaller than the threshold value 2 (S14: YES), the process proceeds to step S31. . If the difference value S of the measurement object is greater than or equal to the threshold 2 (S14: NO), the process proceeds to step S32.

In step S31, the control device determines that the measurement target is a removal target.
In step S32, the control device determines that the measurement target is a useful resin piece. In addition, what is necessary is just to determine suitably which value the threshold value 2 is divided into.

  After determining whether the resin is useful, the useful resin is collected and collected (collecting step). The object to be removed is removed separately from useful resins.

  Here, it is described in detail why it is necessary to perform the selection through the two-stage determination as in the first embodiment, instead of using only the difference value for the foreign substance determination.

  Conventionally, it has been considered that it is possible to determine useful resin pieces and objects to be removed only by steps S13 to S14 in FIG. However, the inventor of the present application has paid attention to the fact that, when the object to be removed contains a wide variety of elements, such as waste plastic for the purpose of recycling, erroneous determination occurs only by the determination by the difference method.

FIG. 4 is a diagram illustrating the relationship between the difference value S and the thickness of the measurement object for explaining the determination method according to the first embodiment. In FIG. 4, the horizontal axis indicates the thickness of the measurement object, and the vertical axis indicates the difference value S calculated from the low energy X-ray transmission intensity I _L and the high energy X-ray transmission intensity I _{H of the} measurement object. In addition, the points indicated by circles are useful resin pieces, the points indicated by triangles are X-ray absorbing small foreign matters, the square points are X-ray absorbing large foreign matter data, and the threshold 2 position is indicated by a broken line.

  As can be seen from FIG. 4, the response to the thickness of the difference value is different between the X-ray absorbing small foreign matter and the X-ray absorbing large foreign matter. For this reason, if it determines with the difference value of a measurement target object being the threshold value 2 or less that it is a removal target object, a misjudgment will arise especially regarding an X-ray absorption large foreign material. Here, the cause of erroneous determination will be described.

The difference value S is the product of the term − (μ _L −k · μ _H ) and the term t from the equation (5). Therefore, the difference in response to the thickness t as shown in FIG. 4 occurs when the sign of-([mu] _L- k. [Mu] _H ) is different. Of the terms-([mu] _L- k. [Mu] _H ), the value of k is a value set based on a useful resin piece. The value of μ varies depending on the object to be measured. Put the mu _0L and mu _0H values of mu for useful resin pieces, respectively. When the value of k is set so that the term of − (μ _L −k · μ _H ) is 0 for a useful resin piece, the following equation (6) is established.

_{Thus, - (μ L -k · μ} H) is - since it becomes _{- {μ L (μ 0L /} μ 0H) μ H}, measurement object, at _{μ L / μ H> μ 0L} / μ 0H In some cases, the slope of the change of the difference value S with respect to the thickness t is negative. This corresponds to the X-ray absorbing small foreign matter in FIG. Further, there is the object to be measured, the inclination of the change relative to the thickness t of the _{μ L / μ H <μ 0L} / μ when it is _0H is the difference value S is positive. This corresponds to the X-ray absorbing large foreign matter in FIG.

When X-ray absorbing small foreign matters, that satisfy the property of _{μ L / μ H> μ 0L} / μ 0H may with the same resins useful pieces of absorption of X-ray absorbing small foreign matter and high-energy X-rays, X The line-absorbing small foreign matter means that the amount of absorbed low energy X-rays is larger than that of useful resin pieces. As described above, the X-ray absorbing small foreign matter also contains an element having an atomic number larger than that of the contained element contained in the useful resin piece. Therefore, the measurement object has a large absorption in the region where the X-ray sensor for low energy X-rays reacts among the irradiated X-rays, and in the region where the X-ray sensor for high energy X-rays reacts, When the absorption is small, the slope of the change of the difference value S with respect to the thickness t is negative.

Conversely, X-rays absorbed large foreign body satisfies the characteristics of the _{μ L / μ H <μ 0L} / μ 0H. This formula means that when there is a useful resin piece with the same amount of X-ray absorption large foreign matter and low energy X-ray absorption, the X-ray absorption large foreign matter has more high energy X-ray absorption than the useful resin piece. To do. The X-ray absorbing large foreign matter contains an element having a larger atomic number than that of the X-ray absorbing small foreign matter, and an element having a larger atomic number absorbs X-rays having higher energy. Therefore, when the measurement object has a large absorption in the X-ray energy range detected by the X-ray sensor for high energy X-rays among the irradiated X-rays, the change of the difference value S with respect to the thickness t is changed. The slope is positive.

  The foreign substance determination method according to the first embodiment is necessary when the width of the elements contained in the foreign substance is wide, and in particular, the thickness t of the measurement object is large in order to avoid erroneous determination due to the difference value S. By performing the determination in the region based on the transmission intensity of the low energy X-ray, and then performing the determination based on the difference value S, it is possible to improve the accuracy of the selection.

  In the recycling of resin, when trying to distinguish the resin to be recycled from the foreign material, a resin containing 10 wt% or more of glass fiber as a foreign material and a resin containing 1 to 10 wt% of a brominated flame retardant are mixed. To do. In addition to silicon (Si) and bromine (Br), waste plastic may contain chlorine (Cl), calcium (Ca), titanium (Ti), zinc (Zn), antimony (Sb), etc. Since there are a wide variety of elements, the method of this embodiment is effective for improving the accuracy of selection.

  As a result of further experiments, it was confirmed that this method can determine the foreign material to be removed even when chlorine-based resin such as vinyl chloride resin is removed as a foreign material. As described above, the present invention has an advantage that it is possible to perform sorting determination with one apparatus for waste plastic pieces containing various additives. Further, by improving the accuracy of sorting, it is possible to improve the quality of the collected material without impairing the collection amount.

Embodiment 2. FIG.
In the second embodiment, in addition to the determination method described in the first embodiment, a determination method that sequentially adjusts the threshold value 1, the threshold value 2, and the difference value parameter k is used.

  FIG. 5 is a determination flowchart for determining useful resin pieces and removal objects in the second embodiment. Steps S21, S23, S25, and S30 correspond to steps S11, S12, S13, and S14 of FIG. 1 described in the first embodiment, and the functions are the same.

  In the method of the second embodiment, in addition to the threshold value 1 and threshold value 2 and the difference value parameter k used for the above determination, the control device newly adds a region 1 for the X-ray transmission intensity and a region 2 for the difference value S. Preset to. Region 1 is set as a range of low-energy X-ray transmission intensity that a useful resin piece can take.

  FIG. 6 is a diagram showing an example of the region 1 set to the transmission intensity of low energy X-rays. The region 1 is a region between two broken lines corresponding to the X-ray transmission intensity on the same graph as FIG. (Range indicated by an arrow). The range of the region 1 is provided to determine that the resin piece is useful, and is a standard similar to the threshold value 1. However, the region 1 allows more resin pieces to be determined as useful resin pieces than the resin pieces determined by the threshold value 1. For example, in the line of a recycling plant, it is desirable to always set a range including useful resin pieces even if the value of the transmission intensity varies due to factors such as changes in the composition of resin pieces for each lot. Further, as will be described later, the region 1 is not used as a criterion for selecting the resin pieces.

  Further, the region 2 is set as a range of difference values that can be taken by a useful resin piece. FIG. 7 is a diagram illustrating an example of the area 2 set as the difference value, and the setting example of the area 2 is described in the same graph as FIG. Similar to region 1, region 2 allows more resin pieces to be determined as useful resin pieces than the resin piece determined by threshold value 2. The determination result as to whether or not it is included in the region 1 and the region 2 is used for the sequential adjustment of the threshold value 1, the threshold value 2, and the difference value parameter k.

Next, the step operation of FIG. 5 will be described.
In step S21, the X-ray irradiation unit irradiates the measurement target with low energy X-rays and high energy X-rays having different energy ranges, and acquires the respective transmission intensities I _H and IL by the X-ray sensor.

In step S22, the control device checks whether or not the X-ray transmission intensity I _L used for comparison with the threshold value 1 in S23 is a value included in the range of the region 1 set in advance. If the X-ray transmission intensity _IL is a value included in region 1 (S22: YES), the process proceeds to step S24.

In step S24, the control device turns on the flag A. Thereafter, the process proceeds to step S25. Note that the control device used in the present embodiment includes a storage unit that stores the above-described measurement values and setting values. If it is determined in step S22 that the X-ray transmission intensity I _L is not within the region 1, the process proceeds to step S23.

In step S <b> 23, the control device performs a first determination process based on a comparison between the X-ray transmission intensity _IL and the threshold value 1. If it is determined in step S23 that the X-ray transmission intensity I _L is greater than or equal to the threshold value 1, the process proceeds to step S25, and if it is determined that the X-ray transmission intensity I _L is less than the threshold value 1, the process proceeds to step S23. Proceed to S31.

In step S25, the control device calculates the difference value S by the energy subtraction method using the low energy X-ray transmission intensity I _L and the high energy X-ray transmission intensity I _H acquired in step S21.

  In step S26, the control device checks whether or not the obtained difference value is a value included in the range of the area 2 set in advance. If the difference value is a value included in the area 2, the flag B is set. Set to ON.

  In step S27, when both the flag A and the flag B are ON, the control device stores the values measured in S21 as an array in the storage unit. This is because when both the flag A and the flag B are ON, there is a high probability of being a useful resin piece.

  In step S28, the control device resets the threshold value 1, the difference value parameter k, and the threshold value 2 using the data stored in S26.

In step S <b> 29, the control device performs the first determination process again by comparing the X-ray transmission intensity _IL and the threshold value 1. If it is determined in step S29 that the X-ray transmission intensity I _L is greater than or equal to the threshold value 1, the process proceeds to step S30. If it is determined that the X-ray transmission intensity I _L is less than the threshold value 1, the process proceeds to step S30. Proceed to S31.

  In step S <b> 30, the control device performs a second determination step by comparing the difference value S of the measurement object with the threshold value 2. If the control device compares the difference value S of the measurement object with the threshold value 2 and the difference value S of the measurement object is smaller than the threshold value 2 (S30: YES), the process proceeds to step S31. If the difference value S of the measurement object is 2 or more (S30: NO), the process proceeds to step S32.

In step S31, the control device determines that the measurement target is a removal target.
In step S32, the control device determines that the measurement target is a useful resin piece.

  Here, details of the resetting method of the threshold value 1, the difference value parameter k, and the threshold value 2 will be described. The resetting in S28 is performed based on the data stored in S27 for a plurality of measurement objects. The timing for resetting may be, for example, every time when the data stored in S27 is accumulated for a preset number, such as 1000 measurement objects, or each time the determination is made, May be performed sequentially using data up to the number set in advance. In any case, unless the data stored in step S27 has been accumulated, the operation in step S28 is not performed.

  FIG. 8 is a diagram for explaining a method of adjusting the threshold value 1 with respect to the transmission intensity of low energy X-rays. In FIG. 8, measured values obtained using a polypropylene resin piece sample as a useful resin piece are plotted on a graph with the X-ray transmission intensity on the horizontal axis and the difference value on the vertical axis.

  The reason why the values of useful resin pieces in the graph are sparse is that there is a solid difference for each resin piece. In the adjustment of the threshold value 1, paying attention to the value on the horizontal axis in FIG. 8, the ratio of the total number of data exceeding the threshold value 1 can be adjusted by moving the threshold value 1 up and down (moving in the horizontal direction in FIG. 8). it can. For example, the maximum yield can be selected by adjusting the X-ray transmission intensity of all the resin pieces to be higher than the threshold value 1. On the other hand, the quality of useful resin pieces can be improved by setting the data of a certain ratio to be smaller than the threshold value 1.

  As a specific example of a method for automatically adjusting the threshold value 1 by calculation, a method for setting an erroneous determination rate, which is a ratio for determining a useful resin piece as an object to be removed, will be described. For example, if the allowable determination error rate is set to 1%, the number of values below the threshold 1 among the X-ray transmission intensity data included in the region 1 is set to 1%. When the erroneous determination rate is set to 0%, the minimum value of the X-ray transmission intensity data in the region 1 is set as the threshold value 1. In addition, as an example of a method for automatically adjusting the threshold value 1 by calculation, for example, a fixed value (for example, X-ray transmission intensity value) for the minimum value of the X-ray transmission intensity of a useful resin piece as shown in FIG. , A value reduced by 50 to 100) is used as a threshold value 1 to give a margin for determination accuracy.

  On the other hand, in order to reduce the ratio of erroneously determining the object to be removed as a useful resin piece, a threshold value 1 is set to a value higher than the minimum value of the X-ray transmission intensity by a certain value (for example, a value of 50 to 100). Can do.

  In this way, the quality of the selected product can be managed in real time by adjusting the threshold value 1 as appropriate while storing a large amount of data in consideration of the measurement error of the X-ray transmission intensity value.

Next, resetting of the difference value parameter k will be described. 9, for explaining the automatic adjustment of the difference value parameter k, which is a diagram illustrating the relationship of the transmitted intensity I _L and the differential value of the low-energy X-rays.

  In FIG. 9A, an approximate straight line calculated from each point of the same data as that used in FIG. 8 is indicated by a broken line. FIG. 9B shows a state in which the difference value parameter is reset. The difference value parameter is an optimal value when the value of the vertical axis of each point of the graph for a useful resin piece is close to 0. Therefore, as shown in FIG. It is desirable to become. Therefore, an approximate straight line is calculated when each value is plotted with the horizontal axis representing the X-ray transmission intensity and the vertical axis representing the difference value, and the difference value parameter k when the slope is closest to 0 is automatically set as the optimum value. can do.

  Here, an example of a specific method for automatically resetting the difference value parameter k will be described. A geometric average value of all the stored low energy X-ray transmission intensities is calculated, and similarly, a geometric average value of the high energy X-ray transmission intensities stored in the storage unit is calculated. About each geometric mean value, after dividing by the X-ray transmission intensity value when there is no object to be measured, each natural logarithm is taken.

  A value obtained by dividing the calculated value by the low energy X-ray transmission intensity by the calculated value by the high energy X-ray transmission intensity is reset as a difference value parameter. When the geometric mean value of the low energy X-ray transmission intensity is ILGM, the geometric average value of the high energy X-ray transmission intensity is IHGM, and the X-ray transmission intensity when there is no object to be measured is I0, the differential parameter k to be reset is It is calculated by the following equation (7).

  Next, the threshold value 2 is reset using the stored X-ray transmission intensity value and the reset difference parameter k. FIG. 10 is a diagram for explaining the relationship between the transmission intensity of low-energy X-rays and the difference value, and a method for resetting the threshold 2. FIG. 10 shows the same data as FIG. 9B, and the difference value is calculated using the reset difference value parameter k for each stored X-ray transmission intensity. After the recalculation, the threshold 2 is adjusted in the same manner as the reset of the threshold 1. The method of automatically adjusting the threshold 2 is similar to the case of the threshold 1, in which a permissible misjudgment rate is set in advance and the threshold 2 is set so as to satisfy the permissible misjudgment rate. A value with a margin may be used.

  As described above, by setting the region 1 and the region 2, the recovery rate is set so that only a certain proportion is removed with respect to the threshold 1 and the threshold 2 without determining that all the objects to be removed are removed. It is possible to set a value exceeding the value that a useful resin piece can take.

  In addition, when the threshold value and the difference value parameter are sequentially adjusted by the method of the second embodiment, when the distribution of the material of the measurement object is different from time to day or from day to day, the material variation is judged accuracy. Can be suppressed. In particular, when a resin piece obtained by crushing waste plastic is used as a measurement target, the characteristic distribution of a useful resin piece to be collected as well as an object to be removed is not constantly controlled. The determination accuracy can be improved.

Embodiment 3 FIG.
In the third embodiment, in addition to the determination methods of the first and second embodiments, information on the thickness of the measurement object is separately obtained and fed back to the determination, thereby enabling more accurate sorting. The present invention relates to a foreign matter determination method. Here, a description will be given in addition to the first embodiment.

  FIG. 11 is a determination flowchart for determining useful resin pieces and removal objects in the third embodiment. Compared to FIG. 1, step S44 corresponds to step S11, step S45 corresponds to step S12, step S46 corresponds to step S13, and step S47 corresponds to step S14.

  First, in step S41, the thickness of the measurement object is measured using a laser type thickness measuring instrument or the like.

  In step S42, the object to be measured is classified according to the measured thickness. For example, a thickness of less than 1 mm is applied to one of a plurality of predetermined categories such as T1, 1 mm or more and less than 3 mm being T2. A value corresponding to the thickness of the object to be measured can be assigned by setting the threshold 1, threshold 2, and difference value parameter values used in the flowchart of FIG. FIG. 12 is a diagram showing the relationship between the transmission intensity of low energy X-rays and the thickness of the resin piece in the third embodiment. In FIG. 12, since the threshold value 1 represented by the broken line has a different value for each section, it is a step-like function with respect to the thickness.

  As described in the first embodiment, the difference value S obtained by the energy subtraction method is a value that does not depend on the thickness for a useful resin piece, but changes according to the thickness for an object to be removed. Further, as described in the second embodiment, the difference values of useful resin pieces also vary depending on individual differences. For this reason, the threshold value 2 is set to a different value for each thickness category as in the case of the threshold value 1, thereby allowing variation due to individual differences in useful resin pieces, particularly for thick resin pieces. It becomes possible to increase the yield of useful resin pieces.

  FIG. 13 is a diagram showing the relationship between the difference value and the thickness of the resin piece when the threshold value 2 is set according to the thickness of the measurement target in the third embodiment. In order to facilitate understanding, only the values of useful resin pieces and X-ray absorbing small foreign matters are shown, and foreign matters in the region removed in the first determination step are also plotted. Here, since the difference value of the useful resin piece is a value not related to the thickness as described above, the threshold value 2 may be constant regardless of the thickness of the resin piece. The degree of thickness of each section depends on the time required to measure one object to be measured and the accuracy of thickness measurement. If the thickness of the object to be measured is uniform and can be measured with an accuracy of 0.1 mm or less, foreign matter can be determined by measuring only the X-ray transmission intensity without using the difference value. When a crushed resin piece is applied as an object, the thickness of each piece of resin to be measured is not uniform. The present invention has been made for such a situation. However, in the third embodiment, the thickness measurement is performed prior to the X-ray inspection process, so that even when the thickness variation is large. Accurate sorting can be performed.

  In step S43, according to the classification determined in step S42, the control device selects threshold value 1, threshold value 2, and difference value parameter k. For example, the control device selects threshold value 1 such as threshold value 1-1 for the measurement target section T1 and threshold value 1-2 for the measurement target section T2 (not shown). The control device selects the threshold 2 as a threshold 2-1 for the section T1 to be measured and a threshold 2-2 for the section T2 to be measured (not shown). The control device selects the difference value parameter as k1 for the section T1 to be measured and k2 for the section T2 to be measured (not shown).

  The subsequent processes in steps S44 to S49 are the same as the processes in steps S11 to S14, S31, and S32 in FIG.

  Among the determination procedures shown in FIG. 11, the determination procedure of FIG. 5 described in the second embodiment can be used for the steps after step S44. In that case, for the X-ray transmission intensity stored in S26, the area to be stored is changed for each category determined in S32.

  In that case, for the X-ray transmission intensity stored in S27, the area to be stored is changed for each category determined in S32. When resetting the threshold value 1, the threshold value 2, and the difference value parameter in S28, the data used for the resetting calculation is only the value of the same category. For example, the control device calculates the threshold value 1-i, the threshold value 2-i, and the difference value parameter ki using the data of the stage Ti of the thickness of the resin piece 3.

  As shown in FIG. 2, the X-ray transmission intensity changes depending on the thickness of the measurement object, and as shown in FIG. 4, the difference value of the removal object also changes depending on the thickness. By introducing the determination method according to the third embodiment, it becomes possible to suppress the influence of variations due to individual differences in useful resin pieces and removal objects, so that the determination accuracy for sorting can be improved. .

Embodiment 4 FIG.
In Embodiment 4 according to the present invention, the determination method described in Embodiment 1 is used to quickly sort out useful resin pieces from a large amount of waste plastic pieces including foreign matter determination and removal objects. A possible sorting device will be described.

  FIG. 14 is a diagram schematically showing a configuration of a sorting apparatus according to Embodiment 4 of the present invention. The sorting apparatus 100 includes a supply unit 1 that supplies a plastic piece 3 of waste plastic to the transport unit 2, an X-ray irradiation unit 4 that irradiates the resin piece 3 with X-rays, and an X-ray that detects X-rays transmitted through the resin piece 3. A detection unit 5, a control unit 6, and a sorting unit 7 that sorts the sorted resin pieces are provided.

Next, the operation of the sorting apparatus 100 will be described in detail.
First, the resin piece 3 which is a measurement object is supplied onto the transport unit 2 configured by a belt conveyor or the like by the supply unit 1 configured by a hopper and a feeder. The transport unit 2 may be a simple slider or a slide. The resin piece 3 is a mixture of a useful resin piece and an object to be removed. The resin piece 3 conveyed by the conveyance unit 2 is irradiated with X-rays under the X-ray irradiation unit 4 composed of an X-ray source installed at the upper part downstream of the conveyance unit 2. X-rays that have passed through the resin piece 3 are detected by an X-ray detection unit 5 configured by a dual energy X-ray sensor installed immediately below the X-ray irradiation unit 4. This dual energy X-ray sensor is a line-shaped sensor having a width comparable to that of the transport unit 2, and can detect X-ray intensities at a plurality of points on a straight line by a plurality of pixels. Therefore, a plurality of resin pieces 3 may be transported on the transport unit 2 in a state of being arranged in a direction perpendicular to the transport direction. The resin piece 3 is released from the transport unit 2 into the air and passes through a space sandwiched between the X-ray irradiation unit 4 and the X-ray detection unit 5. A signal detected by the X-ray detection unit 5 is transmitted to the control unit 6. The control unit 6 determines whether the resin piece 3 is a useful resin piece or an object to be removed.

Here, details of the determination in the control unit 6 will be described. The determination procedure is as shown in the flowchart of FIG. Since the X-ray detection unit 5 can simultaneously acquire X-ray intensities at a plurality of points using a plurality of pixels arranged in a line, the determination procedure described below is performed on the measurement data for each pixel of the X-ray detection unit 5. Independent processing is performed. First, the numerical value acquisition unit 601 acquires the energy X-ray transmission intensity value I _L and the high energy X-ray transmission intensity I _H from the data acquired by the X-ray detection unit 5. When the numerical value acquisition unit 601 acquires numerical data, smoothing processing for noise reduction may be added separately.

The first determination unit 602 compares the acquired low energy X-ray transmission intensity I _L with the threshold 1 set by the setting unit 605. The first determination unit 602, if low-energy X-ray transmission intensity I _L is lower than the threshold 1, it is determined that the resin piece 3 as an object to, and transmits the signal to the output unit 606. The method for setting the threshold 1 is as described in the first embodiment.

  When the first determination unit 602 does not determine that the resin piece 3 is a removal target, the first determination unit 602 transmits the numerical value acquired by the numerical value acquisition unit 601 to the calculation unit 603. The calculation unit 603 calculates the difference value S using Expression (5) based on the transmitted numerical value and the difference value parameter k set in advance by the setting unit 605, and the result is subjected to the second determination. To the unit 604.

  The second determination unit 604 compares the difference value sent from the calculation unit 603 with the threshold value 2 set in advance by the setting unit 605. The second determination unit 604 determines that the resin piece 3 is a removal target when the difference value, which is the calculation result of the calculation unit 603, is smaller than the threshold value 2 as a result of the comparison, and sends a signal to the output unit 606. Send. When the difference value S is equal to or greater than the threshold value 2, the second determination unit 604 determines that the resin piece 3 is a useful resin piece and does not transmit a signal to the output unit 606. The output unit 606 transmits a removal signal to the selection unit 7 when a signal is transmitted from the first determination unit 602 or the second determination unit 604.

  When the removal signal is transmitted from the output unit 606, the sorting unit 7 collects a removal unit 71 configured by an air gun or the like for blowing the resin pieces 3 with compressed air, and a removal target that is sorted and removed by the air gun. And a recovery box 73 for recovering the resin piece 3 released from the transport unit 2 into the air without performing sorting and removal by an air gun.

  As a result of the determination in the control unit 6, if it is determined that the resin piece 3 is an object to be removed, the air gun of the removal unit 71 from the output unit 606 after the resin piece 3 passes over the X-ray detection unit 5. Is sent to the air gun, compressed air is fired from the air gun, and the resin piece 3 is blown off to the removal box 72.

  When the control unit 6 determines that the resin piece 3 is a useful resin piece, no signal is transmitted from the output unit 606, and the air gun of the removal unit 71 does not operate, so it is determined that the resin piece 3 is a useful resin piece. The resin piece 3 is collected in the collection box 73 in the orbit released from the transport unit 2 into the air.

  About said method, it is suitable when the useful resin piece which should be collect | recovered is contained in the whole measuring object more than the removal target object to remove. On the contrary, when the removal object to be removed is contained more than the useful resin piece to be collected, the useful resin piece may be selected by blowing high-pressure air.

  The control unit 6 determines whether the resin piece 3 is a useful resin piece or a removal target by using the numerical value for each pixel included in the X-ray detection unit 5. For this reason, even if the conveyance speed of the resin piece 3 in the conveyance unit 2 is set to a high speed of 50 m / min to 100 m / min, it is possible to sort without reducing the determination accuracy. Further, by using the two-stage determination by the first determination unit 602 and the second determination unit 604, the removal target object includes a resin piece containing an additive containing Si, and the atomic number from Si is 10 like Br. Even if it is a mixture of resin pieces containing an additive containing elements that are separated from each other, a high-speed, large-scale automatic selection is performed without human image determination by the apparatus configuration as in the fourth embodiment. Is possible.

  In addition, instead of transmitting a removal signal when it is determined that the object is to be removed, a sorting signal may be sent to a useful resin piece for sorting, or both the removal signal and the sorting signal are used. It is also possible to adopt a method of operating.

Embodiment 5 FIG.
In the fifth embodiment, a sorting apparatus 100a described in the second embodiment and capable of automatically changing a set value used for determination and capable of automatically sorting recycled resin and foreign matters will be described. .

  FIG. 15 is a diagram schematically showing the configuration of the sorting apparatus 100a according to the fifth embodiment. The same parts as those in FIG. 14 are given the same numbers. The flow until the resin piece 3 is conveyed and measurement is performed by the X-ray detection unit 5 and the flow until automatic selection is performed based on the signal output from the output unit 606 are the same as in the fourth embodiment. A determination operation in the control unit 6 which is a different part from the fourth embodiment will be described. The fifth embodiment is a device that can automatically and appropriately adjust and change threshold value 1, threshold value 2, and difference value parameter k, which are parameters for determining useful resin pieces. The determination procedure for determining useful resin pieces and removal objects is as shown in the flowchart of FIG.

  The numerical value acquisition unit 601 acquires the low energy X-ray transmission intensity and the high energy X-ray transmission intensity, and then transmits the data to the first determination unit 602 and simultaneously transmits the data to the flag A determination unit 607. The flag A determination unit 607 determines whether the low energy X-ray transmission intensity is included in the region 1 set in advance as a value that can be taken by a useful resin piece. When the low energy X-ray transmission intensity is included in the region 1, the flag A determination unit 607 transmits the determination result and the X-ray transmission intensity to the flag B determination unit. After determining the first stage, the first determination unit 602 transmits a removal signal to the output unit 606 when it is determined that the resin piece 3 is a removal target.

  Regardless of the result of the first determination by the first determination unit 602, the calculation unit 603 calculates a difference value. The calculation result of the difference value is transmitted to the flag B determination unit 608. The difference value calculation result is also transmitted to the second determination unit 604 when the first determination unit 602 does not determine that the object is a removal target. As a result of the second determination by the second determination unit, if it is determined that the resin piece 3 is an object to be removed, a removal signal is transmitted to the output unit 606 as in FIG. The flag B determination unit 608 receives the difference value of the calculation result from the calculation unit 603 only when a signal is received from the flag A determination unit 607. Thereafter, the flag B determination unit 608 determines whether or not the difference value is included in the range of the region 2 set as a value that can be taken by a useful resin piece. When the difference value is included in the region 2, the flag B determination unit 607 transmits the low energy X-ray transmission intensity and the high energy X-ray transmission intensity received from the flag A determination unit to the storage unit 609.

  The transmission intensity values for the plurality of resin pieces 3 are accumulated in the storage unit 609. Aggregation unit 610 recalculates threshold value 1, threshold value 2, and difference value parameter k, which are determination parameters, based on the accumulated data of a certain number or more. The method for setting these three parameters is as described in the second embodiment. The parameters recalculated by the totaling unit 610 are transmitted to the setting unit 605 and used for determination of the next resin piece 3.

  By using a sorting device having a mechanism for resetting parameters for determination as in the fifth embodiment, in addition to the effects of the fourth embodiment, it is due to time fluctuations and daily fluctuations of the supplied resin pieces 3. It is possible to prevent a decrease in foreign matter determination accuracy.

Embodiment 6 FIG.
In the sixth embodiment, automatic sorting for distinguishing useful resin pieces and removal objects based on the thickness measurement results and X-ray transmission intensity measurement results of the measurement objects described in the third embodiment. The sorting device 100b that enables the above will be described.

  FIG. 16 is a diagram schematically showing a configuration of a sorting apparatus 100b according to Embodiment 6 of the present invention.

  A thickness measuring unit 8, which is installed on the transport unit 2 and is composed of a laser type thickness measuring instrument or the like, measures the thickness of the resin piece 3 transported by the transport unit 2. After the thickness is measured, X-rays emitted from the X-ray irradiation unit 4 are irradiated in the same manner as described above, and the X-ray transmission intensity is measured by the transmission X-ray detection unit 5. In order to associate the thickness measurement result and the X-ray transmission intensity measurement result for one resin piece 3, the timing is adjusted by the timing adjustment unit 611.

  The timing adjustment unit 611 calculates the delay time until X-ray irradiation according to the feed speed of the transport unit 2 and associates the data. In addition, since the transport unit 2 has a certain width, the thickness measuring unit 8 determines the position information in the width direction orthogonal to the transport direction to distinguish the resin pieces 3 transported in parallel. Acquire at the same time as the measurement.

  Based on the thickness data, the control unit 6 selects a suitable thickness stage, and sequentially determines whether the resin piece 3 is a useful resin piece or an object to be removed using the determination parameter corresponding to the selected stage. Determine whether. The control unit 6 sets a threshold value 1, a threshold value 2, and a difference value parameter k used for determination based on the result measured by the thickness measurement unit 8. These parameters are set in advance by the setting unit 605 as a data table corresponding to the thickness stage of the resin piece 3. The thickness measurement result and the parameter selection procedure are as described in the third embodiment, and the process of sorting the resin piece 3 by the sorting unit 7 using the determination result is the same as in the previous embodiment. It is.

  The resin piece sorting apparatus 100b shows a device configuration when the thickness measuring unit 8 is added to the resin piece sorting apparatus 100 shown in FIG. 14, but the resin piece sorting apparatus 100b shown in FIG. A measuring unit 8 may be added. At this time, for example, when the thickness stages of the resin pieces 3 are T1, T2, T3,..., The difference value parameters k1, k2, k3,. In any configuration, the sorting accuracy can be improved by using the thickness measurement data.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, it becomes possible to process the collected waste plastics such as crushing and use the members selected from them as materials for new products.

  DESCRIPTION OF SYMBOLS 1 Supply part, 2 Conveyance part, 3 Resin piece, 4 X-ray irradiation part, 5 X-ray detection part, 6 Control part, 7 Sorting part, 8 Thickness measurement part, 71 Removal part, 72 Removal box, 73 Collection box, 100, 100a, 100b Sorting device, 602 first determination unit, 604 second determination unit, S11 X-ray inspection step, S12 first determination step, S14 second determination step.

Claims (9)

A first transmission intensity that is the intensity of the first X-ray transmitted through the resin piece by irradiating the resin piece with an X-ray including a first X-ray and a second X-ray having different energy ranges; An X-ray inspection step of measuring a second transmission intensity that is an intensity of the second X-ray transmitted through the piece;
A first determination step of determining whether the resin piece is a candidate for a useful resin piece using the first transmission intensity;
About the resin piece determined to be a candidate of a useful resin piece by the first determination step, it is a useful resin piece using the difference value obtained from the first transmission intensity and the second transmission intensity. A second determination step of determining whether or not,
And a collecting step of collecting the resin pieces determined to be useful based on the determination result of the second determination step. The first determination step includes a step of determining that the resin piece is a candidate for a useful resin piece when the first transmission intensity is equal to or greater than a first threshold value,
The said 2nd determination process is a selection method of the resin piece of Claim 1 including the process of determining that the said resin piece is a useful resin piece by the said difference value being more than a 2nd threshold value. Storing the first transmission intensity;
Modifying the first threshold using the plurality of stored first transmission intensities,
3. The resin piece sorting method according to claim 2, wherein the first determination step includes a step of performing the determination for a subsequent resin piece using the corrected first threshold value. Storing the first transmission intensity and the second transmission intensity;
Using the stored first transmission intensity and second transmission intensity to modify a difference value parameter for calculating a difference value,
3. The resin piece sorting method according to claim 2, wherein in the second determination step, the determination is performed on a subsequent resin piece using the modified difference value parameter. Using the stored first transmission intensities to modify the second threshold,
5. The resin piece sorting method according to claim 4, wherein, in the second determination step, the determination is performed on a subsequent resin piece using the corrected second threshold value. Prior to the X-ray inspection step, measuring the thickness of the resin piece,
The resin piece sorting method according to claim 2, further comprising a step of setting the first threshold according to the measured thickness of the resin piece. Prior to the X-ray inspection step, measuring the thickness of the resin piece,
The resin piece sorting method according to claim 4, further comprising a step of setting the difference value parameter according to the measured thickness of the resin piece. Prior to the X-ray inspection step, measuring the thickness of the resin piece,
The resin piece sorting method according to claim 2, further comprising a step of setting the second threshold according to the measured thickness of the resin piece. A transport section for transporting a resin piece;
An X-ray irradiation unit that irradiates the resin piece with X-rays including first X-rays and second X-rays having different energy ranges;
A transmitted X-ray intensity measuring unit that measures a first transmitted intensity that is the intensity of the first X-ray transmitted through the resin piece and a second transmitted intensity that is the intensity of the second X-ray transmitted through the resin piece. When,
A first determination unit that determines whether the resin piece is a candidate for a useful resin piece using the first transmission intensity;
About the resin piece determined to be a useful resin piece candidate by the first determination unit, it is a useful resin piece by using the difference value obtained from the first transmission intensity and the second transmission intensity. A second determination unit for determining whether or not
A resin piece sorting apparatus comprising: a sorting unit that sorts and collects the resin pieces based on a determination result of the second determination unit.

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