JP7575997B2 - Imaging device for particle size distribution measurement - Google Patents

Description

The present invention relates to an imaging device for measuring the particle size distribution of a material consisting of a large number of aggregates transported by a conveyor.

Concrete is manufactured by mixing cement, aggregate, and water, but since its properties change depending on the mix ratio of each material as well as the aggregate's particle size and distribution, it is necessary to understand the particle size and particle size distribution of the aggregate in order to control the quality of concrete. With regard to aggregate, in some cases commercial products with pre-adjusted particle size are used, while in other cases products that have not been adjusted for particle size, or crushed material that has been directly crushed in a crusher installed at the manufacturing site are used. In the latter case, it is necessary to understand the particle size distribution at the manufacturing site before the concrete is manufactured.

For this reason, it has been common practice at manufacturing sites to photograph aggregates as they fall freely from a conveyor that transports them, and to measure the particle size distribution of the aggregates based on the photographed images. In addition, technology has been proposed to rectify the flow of the aggregates (materials) being photographed in order to improve the accuracy of measuring the particle size distribution.

JP 2012-202757 A (Patent Document 1) discloses a configuration in which material discharged from an endless belt of a conveyor is made to flow down an inclined plate with diffusion protrusions on its surface.

JP 2018-155612 A (Patent Document 2) discloses a configuration in which all material discharged from the endless belt of a conveyor is taken into a straightening section, and the material is made to flow smoothly down by a rotating pin provided in the straightening section.

Technology has also been proposed for the past in which a portion of the material being transported by a conveyor is sampled and photographed. In JP 2003-275570 A (Patent Document 3), when pellets produced by a granulator move along a conveyor or fall from the conveyor, a tilted plate is inserted a specified distance to sample a portion, and the sampled pellets are photographed by a camera, thereby suppressing measurement errors due to pellet overlap and measuring the particle size.

JP 2012-202757 A JP 2018-155612 A JP 2003-275570 A

In the technology of Patent Document 1, when a large amount of material falls from the conveyor, the diffusion protrusions can cause the material (aggregate) to stagnate, which can reduce processing capacity.

Even with the technology of Patent Document 2, when a large amount of material falls from the conveyor, overlapping of aggregates in the depth direction (front-to-back direction) as viewed from the photographing unit is not sufficiently eliminated even if the rotating pin disperses the material in the width direction, and there is a risk of an error occurring between the particle size distribution measured from the photographed image and the actual particle size distribution.

In addition, if there is a large variation in the particle size of the aggregate piled up on the conveyor, smaller particle sizes tend to accumulate at the bottom, so if a portion of the material on the conveyor in the thickness direction (upper part) is sampled, as in Patent Document 3, there is a risk of an error in the particle size distribution between the sampled portion of the aggregate and the entire aggregate.

The present invention has been made to solve the above problems, and its purpose is to provide an imaging device for measuring particle size distribution, which enables accurate measurement of aggregate particle size distribution based on the captured image, even when a large amount of material falls from the conveyor.

According to one aspect of the present invention, a photographing device for measuring particle size distribution is a photographing device for measuring particle size distribution of a material consisting of a large number of aggregates transported by a conveyor, and includes a diverting section, a screen section, and a photographing section. The diverting section is disposed on the falling trajectory of the material discharged from the front end of the conveyor in the transport direction, and divertes the material so that some of the aggregates in the width direction fall relatively forward and other aggregates in the width direction fall relatively backward. The screen section is disposed below the diverting section, and is disposed between the front side aggregates and the rear side aggregates diverted by the diverting section. The photographing section is disposed facing the screen section, and photographs either the front side aggregates or the rear side aggregates.

Preferably, the diversion section includes at least one intersecting plate that intersects the drop trajectory and has a length equal to or greater than the cross-sectional thickness of the drop trajectory, and a space section that is adjacent to the intersecting plate in the width direction and allows a portion of the material to pass forward.

More preferably, the multiple cross plates are made of plate-like members having at least one slit that forms a space.

It is desirable for the screen portion to be integrally formed at the lower end of the plate-shaped member.

It is also desirable to provide a drop guide section on both sides of the non-photographing surface of the plate-shaped member in the width direction.

Preferably, the imaging device for measuring particle size distribution further includes a position changing means for changing the position of the crossing plate between an intersecting position where the crossing plate intersects with the falling trajectory and a non-intersecting position where the crossing plate does not intersect with the falling trajectory.

The imaging device for measuring particle size distribution may further include an adjustment means for adjusting at least one of the inclination angle, installation height, and front-to-rear position of the cross plate.

The flow dividing section may be composed of a material branching member in which front and rear inclined plates that receive the material from below are arranged alternately along the width direction.

According to the present invention, it is possible to provide images of aggregates for measuring the aggregate particle size distribution with high accuracy, even when a large amount of material falls from the conveyor.

1 is a side view showing a schematic configuration of an imaging device according to an embodiment of the present invention; 5A and 5B are diagrams showing the configuration of a sampling plate constituting a flow dividing section in an embodiment of the present invention. 3A and 3B are diagrams showing simulation results when the sampling plate of FIG. 2 is used. 4 is a graph comparing the grading of sampled aggregates with the grading of original aggregates based on the simulation results of FIG. 3. 13A to 13C are diagrams illustrating an example of additional functions of a sampling plate according to an embodiment of the present invention. 1A to 1C are diagrams showing a state in which the arrangement (tilt, height, front-rear position) of a sampling plate during use has been adjusted in an embodiment of the present invention. 13A to 13D are diagrams showing other configuration examples of the sampling plate. 13A and 13B are diagrams illustrating a flow dividing section (material branching member) provided in an imaging device according to a modified example of an embodiment of the present invention.

The embodiment of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are given the same reference numerals and their description will not be repeated.

＜About the overview＞
An overview of an imaging device for particle size distribution measurement (hereinafter, abbreviated as "imaging device") according to an embodiment of the present invention will be described below. Fig. 1 is a side view showing a schematic configuration of an imaging device 1.

Referring to FIG. 1, the imaging device 1 is disposed downstream of the conveyor 101 in order to measure the particle size distribution of material M, which is composed of a large number of aggregates (including gravel and sand) transported by the conveyor 101. The conveyor 101 is a belt conveyor having an endless belt. In this embodiment, the downstream side (the right side of the paper) in the transport direction of the conveyor 101 is referred to as the front, and is indicated by the arrow A1 in FIG. 1. The direction perpendicular to the front-rear direction (the direction of the arrow A1 and the opposite direction) is referred to as the width direction. The width direction corresponds to the horizontal width direction of the endless belt of the conveyor 101.

The conveyor 101 conveys the material M supplied from an aggregate supply section (not shown), which serves as the discharge outlet of the crusher, forward by rotating an endless belt. At this time, a large number of aggregates are conveyed forward while piled up on the conveyor 101, i.e., while having a certain thickness. Therefore, the material M discharged from the downstream end of the conveyor 101 falls while remaining at a high density. The conveyor 101 is positioned so that the downstream end is slightly higher than the upstream end.

Figure 1 shows a schematic diagram of a trajectory (hereinafter referred to as the "fall trajectory") 90 along which aggregate falls freely from the conveyor 101 to the material M. The fall trajectory 90 has a thickness that corresponds to the overlap of the aggregate on the conveyor 101. The cross-sectional thickness of the fall trajectory 90 corresponds to the distance between the outermost surface 91 and the innermost surface 92 of the material M.

The imaging device 1 mainly comprises a diverter section 11, a screen section 12, and an imaging section 13. The diverter section 11 is disposed on the falling trajectory 90, and divertes the material M discharged from the conveyor 101 in the front-rear direction. Specifically, the diverter section 11 divertes the material M so that some of the aggregate in the width direction falls relatively forward, and other aggregate in the width direction falls relatively backward. In other words, the diverter section 11 divertes the material M in the front-rear direction without dividing it in the thickness direction.

Among the aggregates piled up on the conveyor 101, those with smaller particle sizes tend to accumulate at the bottom, and the particle size of the material M varies in the cross-sectional thickness direction. The diversion section 11 diverts the material M in the forward and backward directions without dividing it in the thickness direction, so the diversion section 11 can sample a portion of the aggregate while maintaining the particle size distribution of the aggregate. A specific configuration example of the diversion section 11 will be described in detail later.

The screen section 12 is disposed below the diversion section 11, and is disposed between the front aggregate and the rear aggregate diverted by the diversion section 11, as shown in FIG. 2(B) etc. described below.

The photographing unit 13 is disposed facing the screen unit 12 and photographs either the aggregate on the front side or the aggregate on the rear side. In other words, the photographing unit 13 photographs a portion of the aggregate sampled by the diverter unit 11. In this embodiment, the photographing unit 13 is disposed forward of the screen unit 12 and photographs the aggregate that is diverted to the front side by the diverter unit 11 and falls.

The image captured by the image capture unit 13 is sent to an information processing terminal 103 such as a personal computer or tablet, where the aggregate particle size and particle size distribution are calculated (estimated). The calculation of the aggregate particle size based on the captured image can be achieved by a known method such as binarization processing.

All aggregate (material M) that falls from the diversion section 11 may be stored in a hopper (not shown), fed into another crusher (not shown), or transported to the next process by another conveyor 102. The conveyor 102 is located below the screen section 12 and transports the material M, for example, from the rear to the front.

<Example of the configuration of the flow dividing section>
In this embodiment, the diverter 11 is realized by a sampling plate 20 arranged to intersect with the drop trajectory 90. The sampling plate 20 is a plate-shaped member having at least one slit. The sampling plate 20 extends in the up-down direction and is arranged perpendicular to the front-rear direction (along the width direction). The sampling plate 20 is formed of a material having rigidity, such as a steel plate.

The sampling plate 20 is attached to the casing 10 to which the imaging unit 13 is attached, for example, in a vertical state, via a support member 14. The sampling plate 20 faces the downstream end of the conveyor 101, and is typically positioned relatively close to the conveyor 101.

The sampling plate 20 constituting the diversion section 11 will be described in detail with reference to Figure 2. Figure 2(A) is a schematic diagram of the sampling plate 20 as viewed from the front (from the direction indicated by the arrow IIA in Figure 1), and Figure 2(B) is a cross-sectional view of the sampling plate 20 along line IIB-IIB in Figure 2(A). Figure 2(A) shows the cross-sectional shape of the drop trajectory 90 intersecting the sampling plate 20, i.e., the outline of the material M discharged from the conveyor 101, as shown in a schematic diagram framed by imaginary lines (two-dot chain lines). Note that the arrow A2 in Figure 2(A) indicates the width direction.

Referring to FIG. 2(A), the sampling plate 20 is typically approximately rectangular in shape in a plan view. The width dimension W1 of the sampling plate 20 is larger than the width W10 of the drop trajectory 90, and the sampling plate 20 is provided with a plurality of (e.g., two) vertically elongated slits 21 spaced apart from one another along the width direction. That is, the sampling plate 20 alternates between slits 21, which are through holes penetrating in the plate thickness direction, and plate portions (hereinafter referred to as "cross plates") 22 without slits 21 in the width direction. In other words, the sampling plate 20 is formed by a plurality of (three in this example) cross plates 22 spaced apart from one another along the width direction.

Therefore, only a portion of the aggregate discharged from the conveyor 101 passes through the slits 21 and falls forward (flow path F1 in FIG. 2B), while the remainder hits the rear surface (rear surface) of the cross plate 22 and flows down along the rear surface of the cross plate 22 (flow path F2 in FIG. 2B). In this way, the slits 21 form a space that allows a portion of the material M to pass through.

The length dimension L1 of each slit 21 is equal to or greater than the thickness T10 of the cross section of the falling trajectory 90. That is, each slit 21 has a length that spans from the outermost surface 91 to the innermost surface 92 of the material M. The same is true for the cross plates 22 adjacent to the slit 21. In this way, since the slit 21 and each cross plate 22 adjacent to the slit 21 have a length that is equal to or greater than the thickness T10, the material M can be divided and dropped in two directions, forward and backward, while maintaining the same particle size distribution as the material M (all aggregate) being transported by the conveyor 101.

The shape of the slits 21 is not particularly limited, but is preferably vertically long, and may be a trapezoid with the lower end width L3 being longer than the upper end width L2, as shown in the figure. It is desirable that the widths (L2, L3) of each slit 21 be determined so that the amount of aggregate sampled through the slit 21 is 1/2 or less of the total.

When two slits 21 are provided as in this embodiment, it is desirable that the width of each slit 21 (for example, the average value of L2 and L3) is 1/5 or less of the width W10 of the falling trajectory 90. This allows the aggregate to be sampled that passes through the slits 21 to fall while being dispersed in the width direction.

Note that each slit 21 must have a width equal to or greater than the maximum particle size of the aggregate to be processed. For example, if the maximum particle size of the aggregate is approximately 40 mm to 50 mm, it is desirable that the widths L2, L3 of each slit 21 be specifically between 60 mm and 150 mm.

In this embodiment, the width of the slit 21 is determined so that the aggregate permeability (the proportion of aggregate sampled forward out of the material M discharged from the conveyor 101) is 20% to 40%. As an example, the width L2 of the upper end of the slit 21 is approximately 80 mm, and the width L3 of the lower end of the slit 21 is approximately 120 mm.

<Simulation results>
Simulation results when the sampling plate 20 having the above-mentioned configuration is used and the permeability of the aggregate is set to 20% to 40% are shown in Fig. 3. Fig. 3(A) and (B) are views of the state in which the material M is diverted by the sampling plate 20, as seen from the front (front side) and diagonally rear (rear side), respectively. In this example, the sampling plate 20 is disposed near the upper end of the falling trajectory 90 so as to sample the aggregate immediately after it falls forward from the conveyor 101.

As shown in Figures 3(A) and (B), only a portion of the high-density aggregate (material M) in the width direction discharged from the conveyor 101 passes through the slit 21 and falls forward along the fall trajectory 90. At this time, as shown in Figure 3(A), the aggregate ma that passes through the slit 21 falls dispersed in the width direction because its density decreases. In other words, overlap in the front-to-rear direction is reduced. Also, as shown in Figure 3(B), the entire thickness of the material M being transported by the conveyor 101 passes through the slit 21.

In this way, by using the sampling plate 20 of this embodiment, it is possible to sample aggregate with reduced overlap in the front-to-rear direction without changing the particle size distribution of the aggregate. Therefore, it is possible to reduce measurement errors in particle size distribution compared to when the high-density aggregate discharged from the conveyor 101 is directly photographed. In addition, because the configuration samples aggregate falling along the falling trajectory 90, it is possible to prevent a decrease in processing capacity due to the accumulation of aggregate.

Figure 4 is a graph comparing the particle size of the aggregate ma that passed through the slits 21 of the sampling plate 20, i.e., the sampled aggregate ma, with the particle size of the original aggregate (material M) based on the simulation results of Figure 3. The horizontal axis of the graph shows sieve openings of 0 to 40 mm in 5 mm increments, and the vertical axis of the graph shows the cumulative passing rate (0 to 100%). As in this simulation, even when there is variation in the particle size of the aggregate, the particle size distribution of the original aggregate and the particle size distribution of the sampled aggregate are approximately the same. From this, it can be seen that by using the sampling plate 20 of this embodiment, it is possible to measure the particle size distribution of aggregate easily and accurately.

<Means for changing the position of the sampling plate>
2A and 2B, the imaging device 1 further includes a position changing means 30 for changing the position of the sampling plate 20. The position changing means 30 changes the position of the sampling plate 20, for example, by rotating the sampling plate 20 in the forward and backward directions about the support member 14 as a rotation axis, to an intersecting position P1 (shown by a solid line) where the sampling plate 20 intersects with the falling trajectory 90, and a non-intersecting position P2 (shown by an imaginary line) where the sampling plate 20 does not intersect with the falling trajectory 90.

The sampling plate 20 located at the intersection position P1 is positioned approximately vertically with its back surface (non-photographed surface) facing straight backward, whereas the sampling plate 20 located at the non-intersection position P2 is inclined so that its lower end is further forward than its upper end, and its back surface faces diagonally downward. The inclination angle θ of the sampling plate 20 at the non-intersection position P2 is, for example, 30° to 50°.

A specific example of the configuration of the position change means 30 is shown in FIG. 2(A). The position change means 30 includes, for example, a support member 14 as a rotating shaft, an engaging portion 32 having an engaging pin 31 attached to the axial end of the support member 14 so as not to rotate relative to the support member 14, and an engaged portion 33 fixed to the side wall of the casing 10 and having a plurality of holes (not shown) in an arc shape with which the engaging pin 31 engages.

The rotation and positioning of the support member 14 is not limited to the example in which it is performed manually using the engagement pin 31, and it is also possible to rotate the support member 14 automatically by external control. For example, the position changing means may include the support member 14 as a rotation axis, a rotation drive unit for rotating the support member 14, and a control means for controlling the rotation drive unit to rotate the support member 14 by a predetermined angle (θ).

By providing such a position changing means 30, the sampling plate 20 can be retracted to the non-intersecting position P2 except when the photographing unit 13 is photographing (i.e., when the aggregate particle size distribution is not being measured). Therefore, wear on the sampling plate 20 caused by constant contact with the back surface of the sampling plate 20 can be suppressed or prevented. As a result, the frequency of maintenance of the sampling plate 20 can be reduced.

<Screen section>
1 and 2, in this embodiment, the screen unit 12 is provided integrally with the lower end of the sampling plate 20. In other words, the screen unit 12 is suspended and supported by the support member 14 via the sampling plate 20. This simplifies the configuration of the imaging device 1 and makes it easy to install the imaging device 1 on-site.

Specifically, the lower end of the sampling plate 20 and the upper end of the screen section 12 are fastened together by a fastening bolt or the like while overlapping each other. The upper end of the screen section 12 and the main body section below it may be bendable. In this case, regardless of the inclination angle of the sampling plate 20, the main body section of the screen section 12 can always be positioned vertically. Therefore, as shown in FIG. 2(B), even when the sampling plate 20 is retracted, the screen section 12 can be prevented from coming into contact with the imaging section 13.

The width dimension W2 of the screen portion 12 is equal to or greater than the width dimension W1 of the sampling plate 20. This prevents the aggregate mb (Figure 3 (B)) diverted to the rear side by the sampling plate 20 from appearing in the image captured by the imaging unit 13.

The sampling plate 20 itself may be extended downward, with the lower portion of the sampling plate 20 functioning as the screen portion 12.

<Additional functions of the sampling plate>
The additional functions of the sampling plate 20 will be described with reference to Fig. 5. Fig. 5(A) and (B) are plan views showing the back surface (non-photographed surface) and the front surface (photographed surface) of the sampling plate 20, respectively. Fig. 5(C) is a cross-sectional view of the sampling plate 20 taken along line VC-VC in Fig. 5(B).

As shown in Figures 5(A) and (C), it is desirable to provide a drop guide portion 41 on both sides in the width direction of the back surface (non-photographing surface) of the sampling plate 20.

The drop guide section 41 is realized, for example, by a pair of side walls 411, 412 extending in the vertical direction. The pair of side walls 411, 412 may be arranged in a tapered shape so that the distance between their lower ends is narrower than the distance between their upper ends. This allows the aggregate that hits the cross plate 22 of the sampling plate 20 to be straightened and allowed to fall. As a result, it is possible to reliably prevent the aggregate mb (Figure 3 (B)) that has been diverted to the rear side by the sampling plate 20 from being captured in the image.

Also, as shown in Figs. 5(B) and (C), a protrusion 42 may be provided that protrudes forward from the lower side of the slit 21. The protrusion 42 is, for example, a rod-shaped member provided in the center of the lower side of the slit 21. This makes it possible to more reliably disperse the aggregate that has passed through the slit 21 of the sampling plate 20 in the width direction.

<Adjusting the placement of the sampling plate during use>
In this embodiment, the sampling plate 20 is arranged substantially vertically during use (photography), but as long as it intersects with the fall trajectory 90, it may be slightly inclined.

For example, as shown by the solid lines in FIG. 6(A), the sampling plate 20 may be inclined with respect to the vertically extending reference line B so that its lower end is in front of its upper end. Alternatively, as shown by the imaginary lines in FIG. 6(A), the sampling plate 20 may be inclined with respect to the reference line B so that its lower end is in back of its upper end.

Since the aggregate fall trajectory 90 may vary, for example, from site to site depending on the amount of aggregate transported by the conveyor 101 and the transport speed of the conveyor 101, an angle adjustment means (not shown) may be provided to adjust the inclination angle θx of the sampling plate 20. In this case, the position change means 30 described above may also serve as the angle adjustment means.

As shown in FIG. 6(B), a height adjustment means (not shown) may be provided for adjusting the installation height of the sampling plate 20, for example by adjusting the height (H1, H2) of the support member 14. This allows the height of the slit 21 to be adjusted, so that aggregate can be sampled appropriately at each site.

Furthermore, as shown in FIG. 6(C), a distance adjustment means (not shown) may be provided for adjusting the distance (degree of proximity) between the sampling plate 20 and the conveyor 101, for example by adjusting the front-rear position (X1, X2) of the support member 14. This allows the distance between the sampling plate 20 and the conveyor 101 to be adjusted, so that aggregate can be appropriately sampled at each site.

In this way, the imaging device 1 may further include an adjustment means for adjusting at least one of the inclination angle, installation height, and front-to-rear position of the sampling plate 20 (cross plate 22).

<Other configuration examples of the sampling plate>
In this embodiment, the sampling plate 20 has two slits 21, but is not limited to this example. For example, as in the sampling plate 20A shown in Fig. 7(A), the number of slits 21 may be one. Also, as in the sampling plate 20B shown in Fig. 7(B), the number of slits 21 may be three or more.

Also, like the central slit 21 of sampling plate 20B, the trapezoidal shape of some or all of the slits 21 may be upside down. Alternatively, the shape of the slits 21 is not limited to a trapezoidal shape, but may be rectangular, diamond-shaped, elliptical, or the like, as in sampling plate 20C shown in FIG. 7(C).

In either case, it is desirable that the slits 21 be arranged symmetrically about the center position in the width direction of the sampling plate.

Furthermore, as shown in FIG. 7(D), as long as there is at least a cross plate 22 narrower than the width W10 of the fall trajectory 90, the slit 21 is not essential. In other words, the diversion section 11 only needs to include at least one cross plate 22 having a length equal to or greater than the cross-sectional thickness T10 of the fall trajectory 90, and a space 21A (corresponding to the above-mentioned slit 21) adjacent to the cross plate 22 in the width direction. The sampling plate 20D has a connecting portion 23 that connects the upper ends of the multiple cross plates 22.

<Modification>
In the above embodiment, an example has been described in which the flow dividing section 11 is configured by a sampling plate including a space (slit) that allows a portion of the material M to pass forward, but the present invention is not limited to such an example.

The configuration of an imaging device 1A according to a modified example of this embodiment will be described with reference to Figure 8. Figure 8 (A) is a cross-sectional view showing a schematic configuration of the diverter section 11A of the imaging device 1A, and (B) is a plan view showing a schematic function of the diverter section 11A.

The imaging device 1A in this modified example has a diverting section 11A instead of the diverting section 11 in the first embodiment. The diverting section 11A is composed of a material diverting member 50 that diverges and discharges the material M discharged from the conveyor 101 in the forward and backward directions. In the imaging device 1A, the screen section 12 is disposed below the material diverting member 50, either integrally with it or separately.

The material distribution member 50 is installed at a position lower than the installation height of the sampling plate 20 described above so as to receive from below all of the material M discharged from the conveyor 101 along the drop trajectory 90.

The material branching member 50 includes a front inclined plate 51 and a rear inclined plate 52 arranged alternately along the width direction as shown in FIG. 8(B). The aggregate received by the front inclined plate 51 rolls on the front inclined plate 51 and falls forward (flow path F11), and the aggregate received by the rear inclined plate 52 rolls on the rear inclined plate 52 and falls backward (flow path F12).

The number of front inclined plates 51 and rear inclined plates 52 is typically the same, but may be different. When the number of front inclined plates 51 and rear inclined plates 52 is the same (multiple), the material splitting member 50 can be realized by a reduction machine.

In this modified example, the density of the aggregate discharged in two directions from the material branching member 50 is reduced, so the overlap in the front-to-back direction of the aggregate photographed by the photographing unit 13 is reduced. In addition, since the material M is only divided in the width direction and not in the thickness direction, the particle size distribution of the aggregate can be calculated with high accuracy from the image of a portion of the aggregate (aggregate that has fallen forward) photographed by the photographing unit 13.

In this modified example, the imaging unit 13 may be disposed on the rear side of the screen unit 12, as shown by the imaginary line in FIG. 8(A). In other words, the imaging device 1A may capture an image of the aggregate discharged to the rear side by the material branching member 50.

In the above embodiment, the photographing unit 13 may also photograph the aggregate (aggregate mb in FIG. 3) that falls relatively backward along the cross plate 22 of the sampling plate 20.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

1, 1A: photographing device, 11, 11A: flow dividing section, 12: screen section, 13: photographing section, 20, 20A, 20B, 20C, 20D: sampling plate, 21: slit, 21A: space section, 22: cross plate, 30: position changing means, 41: fall guide section, 50: material branching member, 51: forward inclined plate, 52: rearward inclined plate, 90: fall trajectory, 101, 102: conveyor, M: material (aggregate), ma, mb: aggregate, P1: crossing position, P2: non-crossing position.

Claims (8)

An imaging device for measuring the particle size distribution of a material made of a large number of aggregates transported by a conveyor,
a dividing section that is disposed on a falling trajectory of the material discharged from the front end of the conveyor in the conveying direction, and divides the material so that a part of the aggregate in the width direction falls relatively forward and another part of the aggregate in the width direction falls relatively backward;
a screen portion disposed below the diverter portion and between the front side aggregate and the rear side aggregate diverted by the diverter portion;
an imaging unit disposed opposite the screen unit and configured to image either the front side aggregate or the rear side aggregate; The imaging device for measuring particle size distribution according to claim 1, wherein the flow dividing section includes at least one intersecting plate that intersects the fall trajectory and has a length equal to or greater than the thickness of the cross section of the fall trajectory, and a space section that is adjacent to the intersecting plate in the width direction and allows a portion of the material to pass forward. The imaging device for measuring particle size distribution according to claim 2, wherein the multiple cross plates are made of plate-like members having at least one slit that forms the space. The imaging device for measuring particle size distribution according to claim 3, wherein the screen portion is integrally provided at the lower end of the plate-like member. The imaging device for particle size distribution measurement according to claim 3 or 4, in which a drop guide is provided on both sides in the width direction of the non-imaging surface of the plate-like member. The imaging device for measuring particle size distribution according to any one of claims 2 to 5, further comprising a position changing means for changing the position of the intersecting plate between an intersecting position where the intersecting plate intersects with the falling trajectory and a non-intersecting position where the intersecting plate does not intersect with the falling trajectory. The imaging device for measuring particle size distribution according to any one of claims 2 to 6, further comprising an adjustment means for adjusting at least one of the inclination angle, installation height, and front-rear position of the cross plate. The imaging device for measuring particle size distribution according to claim 1, wherein the flow dividing section is composed of a material branching member in which a front inclined plate and a rear inclined plate that receive the material from below are arranged alternately along the width direction.

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