Particle size distribution measuring device

Abstract

To accurately measure grain sizes of granular materials and accurately calculate a grain size accumulation curve of the granular materials.SOLUTION: A plurality of recesses 24 capable of holding each of granular materials 2 are formed, with a space therebetween, on a placement face part 20 to which a granular material mixed with the granular materials 2 having different grain sizes D is charged, and the granular materials 2 are moved on the placement face part 20 as the placement face part 20 is vibrated by a vibration part 14 and is thereby held in the plurality of recesses 24. When the grain sizes D of the granular materials 2 are calculated on the basis of image data generated by imaging the granular materials 2 that are dispersed on the placement face part 20, and when a grain size accumulation curve that indicates the distribution of the grain sizes D of the granular materials 2 in the granular material on the basis of the calculated grain sizes D of the grain materials 2, the granular materials 2 are not stacked or contacted with each other unlike conventional cases. The grain size D of each of the granular materials 2 can be accurately measures, making it advantageous for accurately calculating the grain size accumulation curve of the granular materials 2, and also advantageous for accurately and efficiently evaluating the granular material.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a particle size distribution measuring device. [Background technology]

[0002] Conventionally, when measuring the particle size of granular materials such as aggregates such as sand and gravel that are mixed with cement to make concrete, or embankments that are piled on land to make it level or give it a slope, and calculating a particle size accumulation curve that shows the particle size distribution, a method has been used in which the granular material is sieved using multiple sieves with different mesh sizes, and the proportion of the mass of the granular material that passed through each sieve to the total mass of the granular material is calculated. This method has the problem that it requires a lot of manual labor and time. Therefore, Patent Document 1 proposes a technique for determining the particle size of a granular material from image data generated by capturing an image of the granular material with a digital camera. Patent document 2 also proposes a technology in which a granular material is dispersed by applying vibration to the granular material, the granular material is imaged to generate image data, the particle size of the granular material is calculated based on the image data, and a particle size accumulation curve is calculated based on the calculated particle size of the granular material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-038865 A [Patent Document 2] Patent No. 6319791 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology of Patent Document 1, there is a concern that the granular materials may overlap or come into contact with each other when imaged, which is disadvantageous in accurately calculating the particle size of the granular material from the image data of the granular material. In addition, although the technology of Patent Document 2 involves vibrating the granular material to disperse it, simply vibrating it is insufficient to reliably eliminate overlapping or contact between granular materials, which is disadvantageous in accurately calculating the particle size of the granular material from image data of the granular material. Therefore, the above two conventional techniques have room for improvement in terms of accurately measuring the particle size of granular material and accurately calculating the particle size accumulation curve. The present invention has been devised in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a particle size distribution measuring device that is advantageous for accurately measuring the particle size of granular material and accurately calculating the particle size accumulation curve of the granular material. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, one embodiment of the present invention is a particle size distribution measuring device comprising a loading surface onto which a granular material containing a mixture of granular materials of different particle sizes is loaded, a vibration unit which applies vibration to the loading surface to disperse the granular material on the loading surface, an imaging unit which images the granular material dispersed on the loading surface to generate image data, an image processing unit which calculates the particle size of the granular material based on the image data, and a particle size distribution calculation unit which calculates a particle size accumulation curve showing the particle size distribution of the granular material in the granular material based on the particle size of the granular material calculated by the image processing unit, wherein a plurality of recesses capable of holding each of the granular materials are formed at a distance from each other on the loading surface, and each of the granular materials moves across the loading surface and is held in the plurality of recesses due to vibration of the loading surface by the vibration unit. In one embodiment of the present invention, at least one of the contour area of ​​the recesses and the depth of the recesses varies stepwise in all or part of the plurality of recesses. In one embodiment of the present invention, the plurality of recesses are regularly arranged over substantially the entire area of ​​the placement surface. In one embodiment of the present invention, the plurality of recesses are randomly arranged over substantially the entire area of ​​the placement surface. One embodiment of the present invention is characterized in that the contour of the recess is circular, elliptical or polygonal, and the diameter of the circle, or the major and minor axes of the ellipse, or the length of the sides of the polygon are set to known values. In one embodiment of the present invention, a surface of the placement surface portion is formed of a material having a large coefficient of friction with respect to the granular material. One embodiment of the present invention is characterized in that filter sections are dispersed and formed over almost the entire area of ​​the placement surface except for the multiple recesses, through which granular material smaller than a predetermined minimum particle size is sifted out. One embodiment of the present invention is characterized in that the particle size distribution calculation unit calculates the particle size accumulation curve of the remaining granular material excluding the granular material having a particle size smaller than the minimum particle size as a first particle size accumulation curve, estimates the particle size accumulation curve of the granular material having a particle size smaller than the minimum particle size based on the first particle size accumulation curve as a second particle size accumulation curve, and calculates the entire particle size accumulation curve of the granular material by combining the first particle size accumulation curve and the second particle size accumulation curve. Effect of the Invention

[0006] According to one embodiment of the present invention, a plurality of recesses capable of holding each individual granular material are formed at a distance from one another on a loading surface onto which a granular material mixture of granular materials of different particle sizes is loaded, and vibration of the loading surface causes each individual granular material to move across the loading surface and be held in the plurality of recesses. Therefore, the particle size of the granular material is calculated based on image data generated by imaging the granular material dispersed on the mounting surface, and when calculating a particle size accumulation curve showing the particle size distribution of the granular material, the granular material does not overlap or come into contact with each other as in the conventional method. Therefore, the particle size of each granular material can be accurately measured, which is advantageous for accurately calculating the particle size accumulation curve of the granular material, and is advantageous for efficiently and accurately evaluating granular materials. In addition, making all or part of the multiple recesses so that at least one of the area of ​​the recess's outline and the depth of the recesses differs in stages is advantageous in ensuring that granular materials of various shapes and sizes are held in the recesses, and is advantageous in accurately measuring the particle size of each granular material and accurately calculating the particle size accumulation curve of the granular material. In addition, arranging the recesses regularly over almost the entire area of ​​the mounting surface is advantageous in maximizing the number of granular materials that can be held in the recesses, in efficiently performing image processing by the image processing unit, in easily forming the mounting surface, and in easily setting conditions such as the shooting distance of the imaging unit. Furthermore, by arranging multiple recesses randomly over almost the entire area of ​​the mounting surface, each granular material is more likely to be held in the multiple recesses regardless of the direction in which each granular material moves due to vibration, which is advantageous in efficiently separating each granular material. Furthermore, if the diameter of the circle of the recess, or the major and minor axes of the ellipse of the recess, or the length of the sides of the polygon of the recess, are set to known values, it is advantageous for the image processing unit to use these known values ​​as reference dimensions to easily calculate the area of ​​the granular material from the image data by image recognition. Furthermore, if the surface of the mounting surface is made of a material with a high coefficient of friction against the granular material, the vibration of the mounting surface makes it easier for the granular material to roll, and each piece of granular material that overlaps or touches each other becomes easier to separate, making it easier for each piece of granular material to be held in the recess, which is advantageous for accurately measuring the particle size and accurately calculating the particle size accumulation curve of the granular material, and is advantageous for efficiently and accurately evaluating the granular material. Furthermore, by dispersing and forming a filter section on the mounting surface section, through which granular material smaller than the minimum particle size is screened out, it is possible to generate image data by excluding granular material smaller than the minimum particle size that cannot be accurately imaged. This makes it possible to accurately calculate the area equivalent diameter of the granular material, which is advantageous in improving the accuracy of the calculated particle size accumulation curve. In addition, the particle size accumulation curve of the remaining granular material excluding granular material smaller than the minimum particle size is calculated as a first particle size accumulation curve, the particle size accumulation curve of the granular material smaller than the minimum particle size is estimated based on the first particle size accumulation curve as a second particle size accumulation curve, and the first particle size accumulation curve and the second particle size accumulation curve are combined to calculate the particle size accumulation curve of the entire granular material, which is advantageous in accurately evaluating the particle size of the granular material without having to take images of the granular material smaller than the minimum particle size, which is time-consuming. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram showing a configuration of a particle size distribution measuring device according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram showing the configuration of a control system of the particle size distribution measuring device according to the first embodiment. [Diagram 3] FIG. 2 is a perspective view showing a container of the particle size distribution measuring device according to the first embodiment. [Figure 4] 1A is a plan view showing a schematic diagram of the placement surface, and FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A, showing a state in which granular material is held in the recess. [Diagram 5] FIG. 1A is a plan view showing a schematic diagram of a first modified example of the mounting surface portion, and FIG. 1B is a cross-sectional view taken along line BB in FIG. [Figure 6] 13A is a plan view showing a schematic diagram of a second modified example of the mounting surface portion, and FIG. 13B is a cross-sectional view taken along line BB in FIG. 13A, showing a state in which granular material is held in the recessed portion. [Figure 7] 13A is a plan view of a recess in a third modified example of the mounting surface portion, FIG. 13B is a cross-sectional view taken along line BB in FIG. 13A, and FIG. 13C is a cross-sectional view taken along line CC in FIG. [Figure 8] 3 is an operation flowchart of the particle size distribution measuring device according to the first embodiment. [Figure 9] 1 is an explanatory diagram showing an example of image data of granular material dispersed on a mounting surface portion; [Figure 10] 2 is a diagram showing an example of a particle size accumulation curve calculated by the particle size distribution measuring device according to the first embodiment. FIG. [Figure 11]FIG. 11 is a plan view showing a mounting surface of a container of a particle size distribution measuring device according to a second embodiment. [Figure 12] FIG. 11 is a diagram showing an example of a particle size accumulation curve calculated by the particle size distribution measuring device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (First embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the terms used in this specification will be explained. Granular materials are materials used, for example, in civil engineering and construction work, and specifically include aggregates such as sand and gravel that are mixed with cement to make concrete, and embankment materials that are piled up on land to make it flat or give it a slope. Aggregates and fill materials are composed of granular materials that are a mixture of granular materials of different particle sizes. The area equivalent diameter is known as a definition of the particle size of a granular material. The area equivalent diameter is the area defined by the contour of the granular material when it is assumed to be a sphere and projected onto a plane; in other words, the area defined by the contour of the granular material as identified on image data captured by an imaging device is taken as the projected area of ​​the sphere, and is calculated as the diameter of this sphere. The reason for calculating the area equivalent diameter as the particle diameter of the granular material is that the granular material is irregular in shape and comes in various forms. Granular materials that make up aggregates and embankments are classified as follows according to the range of particle size D (JISA0207:2018 (Geotechnical Engineering Terminology)). Clay content: particle size D<0.005mm Silt content: 0.005mm≦particle size D<0.075mm Sand content: 0.075mm≦Particle size D<2mm Gravel: 2mm≦grain size D<75mm Stone content: 75mm≦particle size D

[0009] The particle size accumulation curve indicates the distribution of particle sizes of the granular materials that make up the granular material. As shown in Figure 9, the particle size accumulation curve is represented by a semi-logarithmic graph with the particle size D of each granular material on the horizontal axis (logarithmic scale) and the passing mass percentage P (also called the accumulated passing rate) on the vertical axis (linear scale). The passing mass percentage P is the mass percentage of granular material having a particle size D or less relative to the total, that is, the percentage of the total mass of granular material having a particle size D or less relative to the total mass of all granular material.

[0010] Next, the configuration of the particle size distribution measuring device 10 according to the present embodiment will be described. As shown in FIGS. 1 and 2, the particle size distribution measuring device 10 includes a container 12, a vibration section 14, an imaging section 16, and a computer 18. As shown in Figure 3, the container 12 is used to pour granular material containing a mixture of granular materials of different particle sizes, and is formed with an open upper portion and has a mounting surface 20 and a side wall 22 that rises from the periphery of the mounting surface 20. In this embodiment, the placement surface portion 20 has a rectangular plate shape, but the shape of the placement surface portion 20 is not limited and may be a circle, a polygon, or the like. The placement surface 20 is where the granular material is poured. FIG. 4A is a plan view showing a schematic diagram of the placement surface portion 20, and FIG. 4B is a cross-sectional view taken along line BB in FIG. 4 and subsequent figures, only the placement surface portion 20 of the container 12 is shown, and the side wall 22 is omitted. The placement surface portion 20 has a surface 2002 extending on a single plane, and a plurality of recesses 24 capable of holding the granular materials 2 one by one are formed in the surface 2002 and spaced apart from one another. As the vibrating section 14 described below vibrates the mounting surface 20 , each of the granular materials 2 moves across the mounting surface 20 and is held in one of the recesses 24 . All or some of the plurality of recesses 24 have at least one of the area of ​​the contour of the recesses 24 when the mounting surface portion 20 is viewed in plan and the depth of the recesses 24 that differ in a stepped manner.

[0011] In this embodiment, the surface 2002 of the supporting surface portion 20 extends on a single plane, but as long as the granular material 2 is retained in the recess 24, the shape of the remaining surface 2002 of the supporting surface portion 20 excluding the recess 24 is arbitrary. For example, a convex portion or a curved surface protruding on the opposite side of the recess 24 may be formed on the remaining surface 2002 of the supporting surface portion 20 excluding the recess 24, so that the granular material 2 located on the convex portion or the curved surface can easily enter the recess 24 and be easily retained in the recess 24.

[0012] In the example of Figure 4, the multiple recesses 24 are concave hemispherical shapes with different diameters from one another, and therefore the diameter d1 of the circle that forms the outline of the recess 24 when the supporting surface portion 20 is viewed in a plane (in other words, the area of ​​the circle) and the depth d2 of the multiple recesses 24 are formed with dimensions that differ in stages.

[0013] In addition, in the first modified example shown in Figures 5(A) and (B), the multiple recesses 24 have a square prism shape with sides having lengths L1 (in other words, the areas of the contours of the recesses 24) that vary in stages, and the depths d2 of the multiple recesses 24 are formed to be the same dimensions. In a second modified example shown in FIGS. 6(A) and 6(B), the recesses 24 are cylindrical with the same diameter d1, and the depths d2 of the recesses 24 vary in stages. In addition, in order to simplify the illustration, Figures 4, 5, and 6 show an example in which the dimensions of each part of the recess 24 (diameter d1, depth d2, length of one side L1) are changed in four stages, but the dimensions of each part of the recess 24 actually provided on the mounting surface portion 20 are set to many more stages.

[0014] Furthermore, the shape of the recess 24 when the mounting surface portion 20 is viewed from above is not limited to a circle or a square (rectangle), but may be a polygon such as a triangle or a pentagon. Furthermore, the shape of the recess 24 when the mounting surface portion 20 is viewed from above may be an ellipse having a major axis dA and a minor axis dB, as in a third modified example shown in FIGS. 7(A), (B), and (C). In the example of FIG. 7, the multiple recesses 24 are cylindrical with an elliptical cross section. In this case, the major axis dA and minor axis dB (in other words, the area of ​​the contour of the recesses 24) of the multiple recesses 24 may be the same or may differ in stages, and the depths d2 of the multiple recesses 24 may be the same or may differ in stages. Furthermore, the shape of the multiple recesses 24 when viewed in a plane, the area of ​​the contour of the recesses 24, the depth d2 of the recesses 24, and the cross-sectional shape of the recesses 24 are not limited to the examples described above, and in short, they may be of any type as long as the granular material 2 can be retained in the recesses 24. In the above example, the recesses 24 have the same shape in plan view, such as a circle or a square, but it goes without saying that recesses 24 of different shapes may be present. In addition, the examples of Figures 4, 5, and 6 show a case in which a plurality of recesses 24 are regularly arranged (in a grid pattern in this embodiment) across almost the entire area of ​​the mounting surface 20 when viewed in a plane, but the arrangement of the multiple recesses 24 may also be, for example, staggered. Furthermore, the plurality of recesses 24 may be randomly arranged over substantially the entire area of ​​the mounting surface 20 when viewed from above.

[0015] By forming multiple such recesses 24 in the mounting surface portion 20, when the granular material is loaded onto the mounting surface portion 20 and the mounting surface portion 20 is vibrated by the vibration portion 14, each of the granular pieces 2 that make up the granular material moves across the mounting surface portion 20 and is held in the multiple recesses 24. Furthermore, if two or more granular materials 2 are placed in one recess 24, the vibration of the mounting surface 20 will cause the multiple granular materials 2 to collide with each other inside the recess 24, and eventually the remaining granular materials 2 except for one granular material 2 will be ejected from the recess 24, resulting in the phenomenon of one granular material 2 being held in one recess 24.

[0016] Furthermore, if the diameter d1 of the circle, or the major axis dA and minor axis dB of the ellipse, or the side length L1 of the polygon, which are the contour of the recess 24, are set to known values, the known values ​​can be used as reference dimensions on the image data captured by the imaging device 16, as described below.

[0017] In addition, the container 12 including the mounting surface portion 20 can be constructed from conventionally known materials such as metal and synthetic resin, but if the surface 2002 of the mounting surface portion 20 is formed from a material with a high coefficient of friction with respect to the granular material 2, the vibration of the mounting surface portion 20 will make it easier for the granular material 2 to roll. Therefore, each of the granular materials 2 that overlap or contact each other becomes easier to separate, and each of the granular materials 2 moves easily to enter the recesses 24 and is easily held in the recesses 24. As a material having a large coefficient of friction with respect to the granular material 2, various conventionally known materials such as rubber can be used.

[0018] As shown in FIG. 1, the vibration section 14 applies vibration to the placement surface section 20 to disperse the granular material 2 on the placement surface section 20 . In this case, the vibration direction is one or both of a direction along a plane parallel to the mounting surface portion 20 and a direction perpendicular to the mounting surface portion 20 (vertical direction). In this embodiment, a shaker 14A is used as the vibration unit 14, which shakes (shakes) a container 12 such as a test tube or an Erlenmeyer flask to mix and separate the sample therein. The shaker 14A includes, for example, a main body 1402 placed on the base 26, and a vibration table 1404 supported on the upper part of the main body 1402 so as to be capable of swinging and extending on a horizontal plane. The vibration table 1404 is vibrated in at least one of the horizontal and vertical directions by an actuator (not shown) built into the main body 1402 . In this embodiment, the container 12 is mounted on the vibration table 1404 and attached to the vibration table 1404 by a mounting fixture (not shown), so that the container 12 is vibrated together with the vibration table 1404 . With the container 12 attached to the vibration table 1404, the placement surface portion 20 extends on a horizontal plane. The shaker 14A is configured so that parameters such as the vibration direction, vibration amplitude, vibration frequency, and vibration time of the vibration table 1404 can be changed and set by manually operating the operation unit 1406 provided on the main body 1402. The vibration section 14 may have any configuration, and may be configured such that the container 12, which is supported so as to be capable of vibrating, is subjected to vibration from a conventionally known vibrator device, thereby imparting vibration to the placement surface section 20.

[0019] The imaging section 16 is constituted by an imaging device 16A such as a digital camera, and captures an image of the granular material 2 dispersed on the placement surface section 20 to generate image data (still image). The imaging section 16 is supported at a location spaced above the placement surface section 20 via a stand 28 arranged on a base 26, and is configured to be able to image the entire placement surface section 20 from above. Although Figure 1 shows a case where the mounting surface 20 is imaged by the imaging device 16A with the container 12 placed on the shaker 14A, it goes without saying that the imaging device 16A may also image the mounting surface 20 with the container 12 removed from the shaker 14A and placed on the base 26.

[0020] The computer 18 includes an input device 30, an output device 32, and an external storage device 34 in addition to a CPU, a ROM, a RAM, a hard disk drive, and an input / output interface, all of which are not shown. The ROM stores predetermined control programs and the like, while the RAM provides a working area. The hard disk device stores control programs for implementing an input unit 18A, an image processing unit 18B, a particle size distribution calculation unit 18C, an output unit 18D, and a communication unit 18E, which will be described later. The input / output interface provides an interface with the following input device 30, output device 32, and network 36. The input device 30 receives operational input from an operator, and includes a keyboard 3002 and a mouse 3004 . The output device 32 outputs information, and includes a display 3202 and a printer 3204 . The external storage device 34 stores information, and includes an external hard disk device, an external SSD (solid state drive device), a semiconductor recording medium such as a memory card or a USB memory, or an optical disk recording medium such as a DVD.

[0021] The CPU executes a control program for the hard disk device, thereby realizing an input unit 18A, an image processing unit 18B, a particle size distribution calculation unit 18C, an output unit 18D, and a communication unit 18E. The input unit 18A receives image data captured by the imaging device 16A. The image processing unit 18B calculates the particle diameter D of the granular material 2 based on the image data. That is, as described above, by setting the diameter d1 of the circle that defines the outline of the recess 24, or the long diameter dA and short diameter dB of the ellipse that defines the outline of the recess 24, or the side length L1 of the polygon that defines the outline of the recess 24 to known values, the image processing unit 18B uses these known values ​​as reference dimensions to calculate the area of ​​the granular material 2 by image recognition from the image data, and calculates the particle size D (area equivalent diameter) from the calculated area.

[0022] The particle size distribution calculation unit 18C calculates a particle size accumulation curve (see symbols C1 and C2 in Figure 10) showing the distribution of particle sizes D of the granular material 2 in the granular material based on the particle sizes D of the granular material 2 calculated by the image processing unit 18B. The output section 18D supplies data of the particle size accumulation curve calculated by the particle size distribution calculation section 18C to the output device 32 or the external storage device . The communication unit 18E communicates with a terminal (computer) not shown via a network 36 including the Internet or a dedicated line, and in this embodiment, transmits data of the particle size accumulation curve calculated by the particle size distribution calculation unit 18C to a terminal not shown.

[0023] Next, the operation of the particle size distribution measuring device 10 according to the present embodiment will be described with reference to the flow chart of FIG. First, a granular material, such as aggregate or fill material, whose particle size distribution is to be measured, is sampled (step S10). Next, the collected granular material is placed on the placement surface 20 of the container 12 (step S12). It is assumed that the container 12 is attached in advance to the vibration table 1404 of the shaker 14A. Then, parameters such as the vibration direction, amplitude, frequency, and vibration time of the shaker 14A are appropriately set, and the shaker 14A starts vibrating the mounting surface 20 (step S14). Due to the vibration of the mounting surface 20, the granular material placed on the mounting surface 20 is dispersed across the mounting surface 20, and as it moves, each of the granular pieces 2 that make up the granular material enters into the recesses 24 and becomes held in the recesses 24. That is, the individual granular materials 2 are held in the recesses 24 at a distance from each other without overlapping or contacting each other.

[0024] When a predetermined vibration time has elapsed and the vibration by the shaker 14A has stopped, the imaging device 16A captures an image of the entire mounting surface 20 to obtain image data (step S16). FIG. 9 shows an example of image data, in which each granular material 2 is depicted by a contour line. As shown in FIG. 9, the individual granular materials 2 are spaced apart from one another without overlapping or touching one another.

[0025] Next, the image processing unit 18B identifies the contours of each granular material 2 from the captured image data by image processing, calculates the area, and then calculates the area equivalent diameter of each granular material 2 as the particle size D (step S18). Then, the particle size distribution calculation unit 18C accumulates the number of granular materials 2 for each particle size D (step S20) and determines whether the accumulation has been completed for the entire number of granular materials 2 contained in the captured image data (step S22).If the determination result is negative, the process returns to step S20 and continues the accumulation, and if the determination result is positive, the process proceeds to step S24. The particle size distribution calculation unit 18C calculates the particle size accumulation curve shown in FIG. 10 based on the accumulation result of the number of granular materials 2 for each particle size D (step S24). The output unit 18D outputs the calculated particle size accumulation curve to the display 3202 to display it on the screen, or prints it out from the printer 3204. Alternatively, the output unit 18D supplies the calculated particle size accumulation curve to the external storage device 34 (step S26). Moreover, the output unit 18D transmits the calculated particle size accumulation curve from the communication unit 18E to another terminal via the network 36 (step S28). This completes the series of operations.

[0026] The calculated particle size accumulation curve is used to estimate the particle size of the granular material. FIG. 10 illustrates a particle size accumulation curve C1 with a gentle slope and a particle size accumulation curve C2 with a steep slope. Generally, the more gentle the slope of the particle size accumulation curve, the wider the range of particle size D of granular materials 2 contained, making the gaps between the granular materials 2 smaller and resulting in a stable state, and therefore the particle size of the granular material is evaluated as higher. Conversely, the steeper the slope of the particle size accumulation curve, the more granular material 2 with uniform particle size D is contained, which results in larger gaps between the granular materials 2 and an unstable state, resulting in a lower evaluation of the particle size of the granular material.

[0027] As described above, according to this embodiment, a plurality of recesses 24 capable of holding each of the granular materials 2 are formed at a distance from each other on the mounting surface 20 onto which a granular material mixed with granular materials 2 of different particle sizes D is fed, and as the mounting surface 20 is vibrated by the vibration section 14, each of the granular materials 2 moves across the mounting surface 20 and is held in the plurality of recesses 24. Therefore, when the particle size D of the granular material 2 is calculated based on image data generated by imaging the granular material 2 dispersed on the supporting surface 20, and a particle size accumulation curve showing the distribution of the particle size D of the granular material 2 in the granular material is calculated based on the calculated particle size D of the granular material 2, the granular materials 2 do not overlap or come into contact with each other as in the conventional method. Therefore, the particle size D of each granular material 2 can be accurately measured, which is advantageous for accurately calculating the particle size accumulation curve of the granular material 2, and is advantageous for efficiently and accurately evaluating granular materials.

[0028] Furthermore, according to this embodiment, all or some of the plurality of recesses 24 are configured so that at least one of the contour area of ​​the recesses 24 and the depth of the recesses 24 differs stepwise. This is advantageous in ensuring that granular materials 2 of various shapes and sizes are held securely in the recesses 24, and is also advantageous in accurately measuring the particle size D of each granular material 2 and accurately calculating the particle size accumulation curve of the granular material 2.

[0029] In addition, according to this embodiment, multiple recesses 24 are arranged over almost the entire area of ​​the mounting surface 20, which is advantageous in maximizing the number of granular material 2 that can be held in the recesses 24, and since the granular material 2 can be held in a scattered manner over almost the entire area of ​​the mounting surface 20, which is advantageous in efficiently performing image processing by the image processing unit 18B. In addition, according to this embodiment, multiple recesses 24 are arranged regularly on the mounting surface 20, which is advantageous in terms of easily forming the mounting surface 20, and since the granular material 2 held in the recesses 24 are arranged at approximately equal intervals, it becomes easier to set conditions such as the shooting distance when imaging the granular material 2 on the mounting surface 20 by the imaging device 16A, which is also advantageous in terms of efficiently performing image recognition processing by the image processing unit 18B.

[0030] Furthermore, by arranging multiple recesses 24 randomly over almost the entire area of ​​the mounting surface 20, each granular material 2 is more likely to be held in the multiple recesses 24 regardless of the direction in which each granular material 2 moves due to vibration, which is advantageous in efficiently separating each granular material 2.

[0031] Furthermore, if the diameter d1 of the circle of the recess 24, or the major axis dA and minor axis dB of the ellipse of the recess 24, or the length L1 of the sides of the polygon of the recess 24 are set to known values, it is advantageous for the image processing unit 18B to use the known values ​​as reference dimensions to easily calculate the area of ​​the granular material 2 by image recognition from the image data.

[0032] Furthermore, if the surface 2002 of the mounting surface 20 is formed from a material with a large coefficient of friction against the granular material 2, the vibration of the mounting surface 20 makes it easier for the granular material 2 to roll on the surface 2002 of the mounting surface 20, which makes it easier for each piece of granular material 2 that overlaps or touches each other to separate, and makes it easier for each piece of granular material 2 to be held in the recess 24. This is advantageous in that the individual granular materials 2 can be spaced apart from one another and held in the recesses 24, which is advantageous in that the particle size D can be accurately measured and the particle size accumulation curve of the granular materials 2 can be accurately calculated, which is advantageous in that the evaluation of the granular material can be performed efficiently and accurately.

[0033] (Second embodiment) Next, a second embodiment will be described with reference to FIGS. In the following embodiment, the same parts and members as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted, and the description will focus on the differences. In the first embodiment, the image of the granular material 2 is captured by the imaging device 16A regardless of the size of the particle diameter D of the granular material 2 that constitutes the granular material. However, when the granular material 2 has a small particle size D, the following problems may occur when the image is captured by the imaging device 16A. For example, when the particle size D of the granular material 2 is less than a predetermined value, for example, less than 2 mm (2000 μm), it becomes difficult to obtain image data that accurately captures the granular material 2 due to the optical specifications of the imaging device 16A. Therefore, granular material 2 having a particle diameter D less than a predetermined value cannot be accurately imaged, which is disadvantageous in accurately calculating the area and area equivalent diameter of the granular material 2 from the obtained image data. Furthermore, if one attempts to accurately image granular material 2 whose particle size D is less than a predetermined value, the magnification of the optical system must be changed to a higher magnification, which not only increases the cost of the imaging device 16A but also significantly changes the focal length of the optical system, making the imaging operation time-consuming and laborious, which is not practical.

[0034] On the other hand, it is known that the particle size accumulation curve can be approximated by, for example, the known Talbot function as an approximation function (approximation curve). Therefore, if the remaining range of the particle size accumulation curve excluding the range of small particle size D can be calculated (identified), it is possible to interpolate (estimate) the range of small particle size D on the particle size accumulation curve by identifying the above function based on the known portion of the particle size accumulation curve and extrapolating the particle size accumulation curve using this identified function.

[0035] Therefore, in the second embodiment, as shown in Figure 11, filter sections 38 are dispersed and formed over almost the entire area of ​​the supporting surface 20 except for the multiple recesses 24, which filter out granular material 2 having a particle size smaller than a predetermined minimum particle size Dmin. Therefore, by loading granular material onto the mounting surface 20 and vibrating the mounting surface 20, granular material 2 having a particle size D larger than the minimum particle size Dmin is retained in the recess 24, while granular material 2 having a particle size less than the minimum particle size Dmin passes through the filter section 38 and is removed from the mounting surface 20.

[0036] Furthermore, as shown in FIG. 12, the particle size distribution calculation unit 18C calculates the particle size accumulation curve of the remaining granular materials 2 excluding the granular materials 2 having a particle size smaller than the minimum particle size Dmin as a first particle size accumulation curve C10 shown by a solid line. Then, an approximation function is identified based on the first particle size accumulation curve C10, and this identified approximation function is used to estimate the range of the granular material 2 on the particle size accumulation curve that is less than the minimum particle size Dmin as a second particle size accumulation curve C11, shown by a dashed line. Then, the first particle size accumulation curve C10 and the second particle size accumulation curve C11 are combined to calculate the entire particle size accumulation curve C12 of the granular material 2.

[0037] According to the second embodiment, filter sections 38 that screen out granular material 2 having a particle size smaller than the minimum particle size Dmin are formed and dispersed on the mounting surface section 20, so that image data can be generated by eliminating granular material 2 having a particle size smaller than the minimum particle size Dmin that cannot be accurately imaged by the imaging device 16A. Therefore, the area of ​​the imaged granular material 2 can be accurately calculated by the image processing unit 18B, in other words, the area equivalent diameter of the granular material 2 can be accurately calculated by the image processing unit 18B, which is advantageous in improving the accuracy of the particle size accumulation curve calculated by the particle size distribution calculation unit 18C. In addition, the particle size distribution calculation unit 18C calculates the entire particle size accumulation curve of the granular material 2 by combining the first particle size accumulation curve and the second particle size accumulation curve, which is advantageous in accurately evaluating the particle size of a granular material in which granular materials 2 with different particle sizes D are mixed, without having to take images of granular materials 2 with particle sizes less than the minimum particle size Dmin, which is time-consuming. [Explanation of symbols]

[0038] 2 Granular material 10. Particle size distribution measuring device 12 containers 14 Vibration section 14A Shaker 1402 Main body 1404 Vibration Table 1406 Operation section 16 Imaging unit 16A Imaging device 18 Computers 18A input section 18B Image processing section 18C Particle size distribution calculation section 18D Output section 18E Communication Department 20 Placement surface section 2002 surface 22 Side wall 24 Recess 26 Foundation 28 Stand 30 Input Devices 3002 Keyboard 3004 Mouse 32 Output Device 3202 Display 3204 Printer 34 External storage device 36 Network 38 Filter section d1 diameter d2 Depth L1 Length of one side C10 1st particle size accumulation curve C11 2nd particle size accumulation curve C12 Overall particle size accumulation curve

Claims

1. A loading surface portion onto which a granular material having a mixture of granular materials of different particle sizes is loaded; a vibration unit that applies vibration to the placement surface to disperse the granular material on the placement surface; an imaging unit that captures an image of the granular material dispersed on the placement surface and generates image data; an image processing unit that calculates the particle size of the granular material based on the image data; a particle size distribution calculation unit that calculates a particle size accumulation curve showing a distribution of particle sizes of the granular material in the granular material based on the particle sizes of the granular material calculated by the image processing unit, A plurality of recesses capable of holding the granular materials one by one are formed on the mounting surface and spaced apart from each other, the vibration unit vibrates the placement surface portion, causing each of the granular materials to move on the placement surface portion and be held in the plurality of recesses; At least one of the contour area of ​​the recess and the depth of the recess differs stepwise in all or part of the plurality of recesses. A particle size distribution measuring device characterized by:

2. The plurality of recesses are regularly arranged over substantially the entire area of ​​the placement surface.

2. The particle size distribution measuring device according to claim 1.

3. The plurality of recesses are randomly arranged over substantially the entire area of ​​the placement surface.

2. The particle size distribution measuring device according to claim 1.

4. The contour of the recess is circular, elliptical or polygonal, The diameter of the circle, or the major and minor axes of the ellipse, or the length of the sides of the polygon are set to known values.

4. The particle size distribution measuring device according to claim 1, wherein the particle size distribution measuring device is a particle size distribution measuring device.

5. The surface of the mounting surface portion is formed of a material having a large coefficient of friction with respect to the granular material.

5. The particle size distribution measuring device according to claim 1, wherein the particle size distribution measuring device is a particle size distribution measuring device.

6. A loading surface portion onto which a granular material having a mixture of granular materials of different particle sizes is loaded; a vibration unit that applies vibration to the placement surface to disperse the granular material on the placement surface; an imaging unit that captures an image of the granular material dispersed on the placement surface and generates image data; an image processing unit that calculates the particle size of the granular material based on the image data; a particle size distribution calculation unit that calculates a particle size accumulation curve showing a distribution of particle sizes of the granular material in the granular material based on the particle sizes of the granular material calculated by the image processing unit, A plurality of recesses capable of holding the granular materials one by one are formed on the mounting surface and spaced apart from each other, the vibration unit vibrates the placement surface portion, causing each of the granular materials to move on the placement surface portion and be held in the plurality of recesses; A filter portion is formed in a dispersed manner on almost the entire area of ​​the placement surface portion except for the plurality of recesses, and the filter portion is formed to sieve off the granular material having a particle size smaller than a predetermined minimum particle size. A particle size distribution measuring device characterized by:

7. the particle size distribution calculation unit calculates a particle size accumulation curve of the remaining granular material excluding the granular material having a particle size smaller than the minimum particle size as a first particle size accumulation curve, estimates a particle size accumulation curve of the granular material having a particle size smaller than the minimum particle size based on the first particle size accumulation curve as a second particle size accumulation curve, and calculates an overall particle size accumulation curve of the granular material by combining the first particle size accumulation curve and the second particle size accumulation curve; 7. The particle size distribution measuring device according to claim 6.

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