JP3086800B2 - Method and apparatus for measuring particle size distribution of sand or gravel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring method and a measuring apparatus for measuring the particle size distribution of sand or gravel at a production site for concrete sand or gravel.

[0002]

2. Description of the Related Art In general, the mechanical strength of concrete greatly depends on the particle size distribution of sand and gravel (aggregate) mixed therein. At a quarry site supplying gravel, sand or gravel having a particle size distribution within the JIS standard is required. Must be produced and supplied. Conventionally, as a particle size distribution measuring device for sand or gravel,
Gravel is reduced to J by oscillating multiple sieves.
A method of classifying by particle size based on IS standards, or a method of using a laser beam to fly sand in the light to refract light and measure the particle size distribution from the degree of refraction, and furthermore, a CCD
There was a method of measuring using a camera, and the like.

[0003]

Among the conventional techniques as described above, a method of classifying each mesh using a sieve is as follows.
Currently, it is practiced in various places, but when it is actually measured on site, sand or gravel is in a mud state, and there is a problem that sand and sand are stuck together and cannot be classified according to particle size. Therefore, sand or gravel must be dried once, which requires a long time, and it is impossible to measure the particle size distribution in real time. Furthermore, the sieve causes clogging once it is used, necessitates cleaning and requires a large number of measuring personnel, it takes about half a day for measurement, delays feedback to the manufacturing equipment, and automatic control cannot be performed. There is a disadvantage that.

Further, the method using laser light has a drawback that accurate measurement can be performed for extremely small sand, but measurement cannot be performed for sand or gravel having a size that completely blocks the laser light. The method using a CCD camera is suitable for measurement of an extremely small particle size distribution, but has disadvantages such as a narrow field of view for measurement of a large amount of sand or gravel, and an expensive apparatus.

[0005] In order to solve these difficulties, if there is an apparatus capable of easily distributing the gravel (approximately 0.1 mm to 5 mm) having a relatively large particle size and measuring it at a high speed, the production apparatus is controlled in real time to adjust the particle size. it can. Therefore, there is provided a sand or gravel particle size distribution measuring device that centrifugally separates wet sand or gravel without drying, irradiates the light, and calculates the particle size distribution of the sand or gravel theoretically based on the amount of transmitted light. I did it.

The term "sand" as used in the present invention refers to a set of fine rock grains, and usually has a diameter of 2 mm or less, and
It refers to particles that are a fraction of a millimeter or more. The term "gravel" refers to a mixture of pebbles and sand. The invention can be used for both sand and gravel. The applicants first used a light-transmissive rotating disk with stepped grooves for each particle size between two disks, charged sand and water and other solvents, and rotated at high speed to centrifuge the sand. Is distributed and integrated, and scanned by an optical system provided with the rotating disk interposed therebetween, and compared with basic data based on a reference particle size obtained in advance from a change in output voltage caused by the amount of transmitted light to calculate a particle size distribution. A method for measuring the particle size distribution is provided (Japanese Patent Application No. 9-318488).

However, in this method, sand and gravel having the same particle size are inserted in a fixed amount, and the mass of the sand or gravel is determined based on a change in the amount of transmitted light at that time, and there are many procedures. The present invention solves the above-mentioned difficulties, and allows water-containing sand or gravel to be directly introduced into a rotating disk having a tapered (slope-shaped) gap to continuously separate particles by particle size. To provide a measuring method and a measuring apparatus for measuring the particle size distribution of sand and gravel which can be measured in a short time by a sensor unit and by automatic driving, can be used continuously on site, and can minimize errors. It is assumed that.

[0008]

According to a first aspect of the present invention, there is provided a light-transmitting rotating device having a tapered groove in which a gap between two disks is gradually narrowed from a center toward a radial direction. A dispersing means which is a disk, a centrifugal separating means for simultaneously introducing and rotating a solvent such as sand or gravel and water into the grooves of the rotary disk, and distributing and accumulating sand or gravel by centrifugal force; Scan with the sensor part of the optical system provided,
From the change in the output voltage caused by the amount of transmitted light, composed of a central processing unit for calculating a particle size distribution, between two discs
Of gravel or gravel caught in the gaps of sand in order of decreasing particle size
Calculation of particle size distribution by central information processing means based on accumulation
The method for measuring the particle size distribution of sand or gravel was conducted.

According to a second aspect of the present invention, there is provided a method for measuring the particle size distribution of sand or gravel, in which the rotating disk rotates forward and backward with a quick stop therebetween. In the third invention, a method for measuring the particle size distribution of sand or gravel serving as a light projecting unit and a light receiving unit by laser using an optical system using a one-dimensional line sensor. According to a fourth aspect of the present invention, a tapered groove formed of two light-transmitting synthetic resin disks detachable in the thickness direction, having a gravel inlet, and gradually narrowing from the center toward the radial direction inside. Dispersing means which is a rotating disk provided with a centrifugal separator having a drive circuit adapted to perform forward and reverse rotation on the rotating disk and a brake circuit for suddenly stopping the rotating disk, and provided with the rotating disk interposed therebetween. A sensor unit for measuring a change in output voltage due to the amount of transmitted light using the optical system, a driving unit for moving the optical system in a radial direction from a reference point of the turntable, the dispersing unit, the centrifugal separation unit, the sensor unit and A central information processing means for controlling the drive unit and calculating the grain size of the gravel from the measurement result of the output voltage;

(Function) In the first invention, the sand or the gravel and the water put into the rotating disk as the dispersing means are blown in the circumferential direction by the centrifugal force of the centrifugal separating means, and the taper between the two disks is formed. Are distributed and accumulated in the groove in the order of larger particle size. The sand or gravel caught in the tapered (slope-shaped) groove can move so as to be widely distributed according to continuous or intermittent rotation or inversion of the turntable. Therefore, there is an effect that the particle size distribution is performed more accurately.

The distribution state is scanned by an optical system provided with a rotating disk interposed therebetween, and from the change in output voltage caused by the amount of transmitted light, the particle size distribution is calculated by the central information processing means by comparing it with basic data obtained in advance. be able to. The basic data obtained in advance is based on the output voltage value obtained by throwing the granularity indicated by the specified sieve based on the JIS standard into the turntable of the present invention, and the accuracy is high. Has become.

According to the second aspect of the present invention, since the rotating disk is rotated in the normal or reverse direction with a quick stop therebetween, sand or gravel can be widely distributed in the slope-shaped groove gradually narrowing. In the third invention, since the optical system uses a one-dimensional line sensor and is a light projecting unit and a light receiving unit using a laser, it is possible to more accurately measure an output voltage by irradiating a belt-like laser.

According to a fourth aspect of the present invention, there is provided an apparatus for realizing the measuring method according to the first aspect of the present invention, wherein the rotating disk is constituted by two light-transmitting synthetic resin disks which can be attached and detached in a thickness direction, and a gravel inlet is provided. It has a tapered shape as a slope-shaped groove that gradually narrows from the center in the radial direction from the center, so that when this rotating disk is rotated by the drive circuit, the gravel that is input is distributed according to the particle size by centrifugal force Be accumulated. The distribution accumulation state can be regarded as a change in output voltage generated by the amount of transmitted light of an optical system provided with the rotating disk interposed therebetween. Since the optical system moves in the radial direction from the outer periphery of the turntable to the reference point, the distribution state of sand or gravel can be accurately detected.

Since the two disks are detachable,
The introduction of sand and gravel and the discharge of sand and gravel after the particle size measurement can be easily performed by separating the disk, and can be returned to the original state by washing with water, and can be used continuously. The central information processing means operates the dispersion means, the centrifugal separation means, the sensor section and the drive section, respectively, and, based on a measurement result of the output voltage obtained by the sensor section, calculates a particle size distribution by comparison with basic data obtained in advance. Can be calculated.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a measuring method and a measuring apparatus for measuring the particle size distribution of sand or gravel, which can automatically measure sand and gravel for concrete and provide an automatic operation system for an aggregate plant. It can be taken inside.
In the conventional separation based on the coarse particle ratio, since an operation and a judgment by a human are added, the result differs depending on the skill level. On the other hand, the present invention enables quick processing and unification of accuracy.

At the gravel collection site, the coarse grain ratio (F
The (M value) indicates a value obtained by adding the particle size of 10.0 mm to 0.15 mm and dividing by 1000 (fine module). However, an expert can grasp the condition only by grasping the sand. In the present invention, in order to know such an FM value, a light-transmissive rotating disk provided with a groove gradually narrowing according to the particle size between two disks is used, and sand and gravel and water are charged and rotated. Dispersing means and centrifuging means for distributing and accumulating sand and gravel by centrifugal force, and measuring the distribution of sand or gravel by this centrifuging means using an optical system and comparing it with basic data previously classified and analyzed Then, the particle size distribution of the sample was instantaneously calculated by a personal computer or other central information processing means, so that the particle size distribution could be determined objectively.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is an explanatory view of the particle size distribution measuring method and apparatus of the present invention, and FIG. 2 is a perspective view showing an overall image. In FIGS. 1 to 4, reference numeral 1 denotes a rotating disk, and two disks are stacked as dispersing means,
A tapered groove 2 is provided in which the gap between these disks is gradually narrowed from the center in the radial direction. 3 is a gravel inlet. The rotating disk 1 is a disk made of a transparent synthetic resin made of an acrylic resin. When water, sand, or gravel is supplied through the gravel inlet 3 with good light transmittance, even if the resin disk has small scratches due to water, it is filled. It is suitable for measuring the amount of transmitted light. The tapered groove 2 is formed, for example, with an inclination of 1 degree.

The turntable 1 is connected to a motor and a drive circuit to constitute a centrifugal separator 4. Reference numeral 5 denotes a brake system which enables rapid stoppage while rotating the rotating disk 1 forward and backward. 5 and 6, reference numeral 6 denotes a sensor unit.
It comprises a light projecting unit 6a and a light receiving unit 6b using a line sensor. A laser was used as the optical system.

As shown in FIG. 7, a line sensor 6 is mounted on a linear rail 7 and constitutes a sensor section which is driven in a radial direction by a stepping motor 8 and an encoder 9 at a minute interval on the turntable 1. Reference numeral 10 denotes a central information processing means that controls the centrifugal separation means 4, the sensor unit 6, and the driving unit using a computer, and calculates the grain size of the gravel by comparing the output voltage change obtained by the sensor unit with the reference data. did.

The method for measuring sand or gravel according to the present invention will be described below. (First step) Water is inserted from the gravel inlet 3 of the turntable 1. The turntable 1 is processed as shown in FIGS. Innumerable scratches on the surface are filled with water, improving light transmission. The turntable 1 is detachably fixed with bolts and nuts. Therefore, at the end of the measurement, the cleaning can be performed separately. (Second step) The line sensor 6 is moved to near the center of the turntable 1.

The line sensor moves toward the center of the turntable. (Third step) The rotating disk 1 is rotated at 1000 rpm. By merely adding water to the turntable, air remains therein, and the entire tapered groove 2 cannot be filled with water. By rotating the turntable at high speed, air can be generated by centrifugal force. (Fourth step) Decrease the rotation speed of the turntable.

In order to accurately measure data of one turn of the turntable, the number of revolutions is reduced. When the width of the laser beam of the line sensor 6 is 15 mm, the outer circumference of the turntable has a diameter × pi = 40.
0 × 3.14 = 1256 mm. To measure one round, 1
256/15 = 83.7 times. As a precaution, it was set to measure 168 times per lap.

The number of revolutions is reduced so that the computer measures 168 times per revolution. It was about 640 revolutions. However, since this value is affected by the temperature or the like, the value may be appropriately 168 times or less, and may be controlled by a program. (Fifth step) The line sensor as the sensor unit is moved toward the outside of the turntable.

After the rotation speed of the turntable is reduced, a 5-pulse signal is sent to the stepping motor 8 to move the stage and the line sensor by 60 μm. (Sixth step) At this point, the output voltage from the line sensor is measured, and the data is sent to the personal computer. After moving the line sensor, the output voltage at that radius is measured for 168 points for one round. Import the measured data to a personal computer, average it, and save the data. (Seventh Step) The above fifth and sixth steps are repeated to scan from near the center to the outside of the turntable.

A total of 14000 pulses and 2800 points were measured. (Eighth step) Stop the turntable and insert gravel. Sand or gravel separated according to the following particle diameters is mixed in a predetermined amount, and the mixture is inserted into a turntable. φ = 10.0 to 4.75 φ = 4.75 to 2.36 φ = 2.36 to 1.18 φ = 1.18 to 0.60 φ = 0.60 to 0.30 φ = 0.30 0.15 φ = 0.15 0 Principle of measurement When light is sent from the light-emitting unit to the light-receiving unit in a certain space, if there is nothing, the transmitted light amount is 100%, but half of the light is blocked halfway When blocked by an object, the amount of transmitted light is reduced by half to 50%. In the present invention, when a mask is applied so as to block the rotating disk in a fixed fan shape, the amount of transmitted light changes depending on the mask amount. As a result, as shown in FIG. 8, it was found that the relationship between the change in the amount of transmitted light due to the mask and the output voltage can be expressed by a linear expression.

Using this relationship, the volume of the gap between the rotating disks is determined in advance. By measuring how much the output voltage when sand or gravel is inserted is lower than the output voltage when nothing is inserted, this is the sand or gravel existence probability. When the existence probability is multiplied by the volume, the volume of sand or gravel is obtained. Hereinafter, details of a method and apparatus for recording the reference data and calculating the particle size distribution by the central information processing means based on the data will be described.

FIG. 9 is a particle size distribution table of the sand or gravel used in the experiment of the present invention. Each sample is a mesh and has a particle size distribution. The turntable used had a radius of 200 mm. The tapered (slope) gap has an inclination of 1 degree. Sample 1 is φ2 = 2.36 to 1.18 and 0.62
5g, φ = 0.30-0.15 0.312
Example using 5 g Sample 2 was 0.3 g of φ = 1.18 to 0.60.
And φ = 2.36 to 1.18, 0.25
Example 3 using g = 0.50 to 0.30 for sample 3 at 0.75
g = 0.30 to 0.15 0.6
25g, φ = 2.36 to 1.18, 0.31
Example using 25 g Sample 4 is 0.3 g of φ = 0.60 to 0.30
And φ = 0.30 to 0.15 0.25
g = 0.136g with φ = 2.36 to 1.18
This is an example in which Sample 1 and Sample 3 and Sample 2 and Sample Bottle 4 were compared in the same amount and in different ratios. Measurement of particle size distribution About sample 1 Fig. 10 When only water and gravel are inserted, the distance from the center of the turntable and the output voltage ratio Fig. 11 The characteristic diagram showing the normalized existence probability Fig. 12 The distance from the center of the turntable Volume diagram Fig. 13 Distance from the center of turntable and sand or gravel distribution characteristic diagram Fig. 14 Gravel distribution correction characteristic diagram About sample 2 Fig. 15 When only water and gravel are inserted, distance from the center of turntable and output voltage ratio FIG. 16 is a characteristic diagram showing the normalized existence probability. FIG. 17 is a distance and volume diagram from the center of the turntable. 18 is a distance and gravel distribution characteristic diagram from the center of the turntable. FIG. 19 is a gravel distribution correction characteristic diagram. 5 shows a change in output voltage. It is considered that the inconsistency in the case of water only is due to fine scratches on the turntable.

Since the case of only water is desired to be set to "0", it was standardized. Here, the normalization means to plot again on the figure how much the output voltage when the gravel is inserted is lower than the output voltage when only water is used.
This ratio is the existence probability (γ) of gravel at that point (FIGS. 11 and 16). γ = (Vo−Vs) / Vo, where Vo is the output voltage when only water is used, and Vs is the output voltage when gravel is inserted.

When the volume at each radius of the turntable is determined and multiplied by the existence probability, the volume of sand or gravel at each radius is determined (FIGS. 12 and 17). The volume is determined by dividing each range and integrating them. If the density is constant irrespective of the volume, the ratio of the respective volumes becomes the particle size distribution of sand or gravel (FIG. 13, FIG. 1).
8).

FIGS. 13 and 18 show that even if sand or gravel having the same particle size is distributed in the tapered gap as in the present invention, the dispersion position differs depending on the orientation of the cube as compared with the sieve type distribution. A case arises (see FIG. 20). (A) and (b) are model diagrams of sieving of gravel by a sieve, and (c) and (d) are model diagrams of the present invention when they enter a tapered gap. In the case of gravel, even if the height is the same, if the width is different, the accumulation range will be different.

Therefore, in order to correct this, a certain amount of sand or gravel having each particle size was put in a tapered gap to examine what range actually accumulates, and the results were standardized. The thing is as shown in FIG. The range determined from this result is as follows. φ = 2.36 to 1.18-distance from center 65.98 to 120.16 φ = 1.18 to 0.60-distance from center 120.16 to 152.08 φ = 0.60 0.30-distance from center 152.08 to 167.14 φ = 0.30 to 0.15-distance from center 167.14 to 174.70 φ = 0.15 to 0-from center Distance 174.70 to 179.98 A re-examination of the measurement results using these values is shown in FIG.
4. It is the gravel distribution correction characteristic diagram of FIG. 19, and the measurement accuracy was improved. 14 and FIG. 19, φ = 2.36 to
A large error is seen in the range of 1.18, and FIGS.
Is measured as a large volume at a position 90 mm from the center. This is presumed to be due to internal scratches on the turntable. Different Particle Size Distribution Measurements We examined what happens when the above results were measured for gravel with different particle size distributions. Gravel having the same mass as a whole was examined using samples 3 and 4 in FIG. The results are as shown in FIGS. Again, a large error was observed in the range of φ = 2.36 to 1.18, but in other respects, good results were obtained as characteristics.

[0032]

According to the present invention, it is not necessary to dry the sand because the sand or the gravel can be put in together with the solvent such as water from the inlet of the turntable and separated by the centrifugal separation means. Therefore, the sand can be separated in a short time, and the grooves are tapered, so that the state of accumulation by centrifugal force according to the particle size can be easily measured using an optical system.

A method and an apparatus which can measure the particle size distribution of sand or gravel easily and promptly by measuring the amount of transmitted light at each position after the separation by the centrifugal separation means and comparing with the reference data can be provided. In particular, since the grooves of the turntable are tapered, sand or gravel could be separated for each continuous particle size. Further, by using the normal rotation, reverse rotation and quick stop means, the distribution of sand or gravel can be made wider, and it is possible to provide an efficient and accurate sand or gravel particle size distribution measuring method and measuring device. did it.

[Brief description of the drawings]

FIG. 1 is an overall view of the apparatus of the present invention.

FIG. 2 is a perspective view of the device of the present invention.

FIG. 3 is a half sectional view of a rotary disc.

FIG. 4 is an enlarged sectional view of a main part of the turntable.

FIG. 5 is a perspective view of a sensor unit.

FIG. 6 is a perspective view showing a line sensor of a sensor unit.

FIG. 7 is a perspective view of a driving unit of the sensor unit.

FIG. 8 is a diagram showing the relationship between the amount of transmitted light and the output voltage.

FIG. 9: Particle size distribution diagram of a sample

FIG. 10 is an output voltage characteristic diagram of sample 1.

FIG. 11 is a normalized characteristic diagram of sample 1.

FIG. 12 is a volume diagram of sample 1.

13 is a gravel distribution characteristic diagram of Sample 1. FIG.

14 is a gravel distribution correction characteristic diagram of Sample 1. FIG.

FIG. 15 is an output voltage characteristic diagram of Sample 2.

FIG. 16 is a normalized characteristic diagram of sample 2.

FIG. 17 is a volume diagram of Sample 2.

18 is a gravel distribution characteristic diagram of Sample 2. FIG.

19 is a gravel distribution correction characteristic diagram of Sample 2. FIG.

FIG. 20 is a diagram illustrating distribution characteristics of the present invention.

FIG. 21 is a normalized characteristic diagram for determining a range.

FIG. 22 is an output voltage characteristic diagram of Sample 3.

FIG. 23 is a normalized characteristic diagram of Sample 3.

FIG. 24 is a volume diagram of Sample 3.

25 is a gravel distribution characteristic diagram of Sample 3. FIG.

FIG. 26 is a gravel distribution correction characteristic diagram of Sample 3.

FIG. 27 is an output voltage characteristic diagram of Sample 4.

FIG. 28 is a normalized characteristic diagram of Sample 4.

FIG. 29 is a volume diagram of Sample 4.

30 is a gravel distribution characteristic diagram of Sample 4. FIG.

FIG. 31 is a gravel distribution correction characteristic diagram of Sample 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turntable 6 Sensor part 2 Groove 7 Linear rail 3 Gravel inlet 8 Stepping motor 4 Centrifugal separation means 10 Central information processing means 5 Brake system

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Toshikatsu Kikuchi 1-4-19 Dojimahama, Kita-ku, Osaka-shi, Osaka Inside Osaka Crushed Stone Co., Ltd. (56) References JP-A-61-194329 (JP, A) JP-A No. 11-153536 (JP, A) JP-A-58-177781 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 15/02 G01N 15/04 JICST file (JOIS )

Claims (4)

(57) [Claims] 1. A dispersing means which is a light-transmitting rotary disk having a tapered groove in which a gap between two disks is gradually narrowed from a center toward a radial direction, and sand or gravel is provided in a groove of the rotary disk. And a solvent such as water are simultaneously injected and rotated, and a centrifugal separation means for distributing and accumulating sand or gravel by centrifugal force, and scanning by an optical system sensor unit provided with the rotating disk interposed therebetween, is caused by the amount of transmitted light. hooking the change in output voltage, made, a central processing unit for calculating a particle size distribution, the gap between the two disks in descending order of particle size
Based on the accumulated accumulation of sand or gravel,
A method for measuring the particle size distribution of sand or gravel, wherein the particle size distribution is calculated by steps . 2. The method for measuring the particle size distribution of sand or gravel according to claim 1, wherein the turntable rotates forward and backward with a quick stop therebetween. 3. An optical system using a one-dimensional line sensor,
The method for measuring the particle size distribution of sand or gravel according to claim 1, wherein the method is a light emitting part and a light receiving part by a laser. 4. A tapered groove made of two light-transmitting synthetic resin disks detachable in the thickness direction, having a gravel inlet, and gradually narrowing from the center in the radial direction from the center. Dispersing means which is a rotating disk provided with: a centrifugal separating means provided with a drive circuit configured to perform forward and reverse rotation on the rotating disk and a brake circuit for suddenly stopping the rotating disk; and provided with the rotating disk interposed therebetween. A sensor unit for measuring a change in output voltage due to the amount of transmitted light using the optical system, a driving unit for moving the optical system in a radial direction from a reference point of the turntable, the dispersion unit, the centrifugal separation unit, the sensor unit, and A central information processing means for controlling a drive unit to calculate a particle size of sand or gravel from a measurement result of an output voltage; and a particle size distribution measuring device for sand or gravel.