JP7591191B2 - Optical sorting machine - Google Patents

Description

The present invention relates to an optical sorting machine that optically sorts granular materials such as grains and resin pellets based on color, etc.

Conventionally, optical sorting machines are known that separate raw materials consisting of grains such as rice, wheat, beans, and nuts, resin pieces such as pellets and beads, fine items such as pharmaceuticals, ores, and shirasu, as well as other granular materials, into good and bad products and remove foreign objects that may be mixed into the raw materials.

One of these types of optical sorters has a chute having a predetermined width disposed at an incline below a granular material supply section.
This optical sorting machine supplies a large amount of granular material from a granular material supply section to a chute having a specified width, and the granular material spreads out in the width direction and flows down the surface of the chute, and is allowed to fall freely from the bottom end of the chute along a specified trajectory. Light is then irradiated onto the granular material, and the transmitted light and reflected light from the granular material are received to detect defective products and foreign objects contained in the raw material, and the detected defective products and foreign objects are eliminated, thereby sorting the granular material (see Patent Documents 1 and 2).

In the optical sorting machine described in Patent Document 1, the granular material supply section includes a tank and a vibrating feeder, and in the optical sorting machine described in Patent Document 2, the granular material supply section includes a tank and a rotary valve, and in both cases, the granular material in the tank can be stably delivered toward the chute by the vibrating feeder or rotary valve.

However, with each of the optical sorting machines, when the amount of granular material stored in the tank becomes low, the delivery of the granular material from the vibrating feeder or rotary valve becomes unstable, and the granular material becomes sparse in the width direction of the chute and flows down while bouncing on the surface, which makes it easy for errors to occur in detecting and rejecting defective products, etc., and causes a decrease in sorting accuracy.

To solve this problem, Patent Document 3 proposes an optical sorting machine that can change the width of the granular material flowing down the chute surface after it has been fed onto the chute and while it is flowing down the chute surface. This has the effect of preventing a decrease in sorting accuracy by narrowing the width of the granular material flowing down the chute surface, even if the amount of granular material stored in the storage means decreases and the amount of granular material fed from the feeding means decreases. ...

JP 2009-50760 A Japanese Patent Application Publication No. 11-223604 JP 2013-17918 A

However, in the optical sorting machine described in Patent Document 3, it is necessary to separately provide a discharge width changing means (such as a shutter with a small opening or a guide member that narrows the flow width) on the chute to change the discharge width of the granular material, which could complicate the structure and increase manufacturing costs.
In addition, if the flow of granular material becomes sparse in the width direction of the chute, the chute width is physically narrowed, so if there is a delay in the response of the feed width changing means, there is a risk that the sorting accuracy will decrease.

In consideration of the above problems, the technical objective of the present invention is to provide an optical sorting machine that can maintain high sorting accuracy without providing a separate physical mechanism such as a means for changing the feed width of the chute, even when the granular material is scattered in the width direction of the chute and flows down while bouncing on the surface.

In order to solve the above problem, the invention according to claim 1 provides an optical sorting machine comprising: a chute that allows granular material to flow downward at an incline at a predetermined flow rate; an optical detection unit that inspects the granular material falling from the bottom end of the chute at a predetermined position; an ejector that rejects and sorts the granular material based on a detection result by the optical detection unit; an ejector control unit that, when rejecting and sorting the granular material, sets a delay time from when the optical detection unit detects the granular material at the predetermined position to when the ejector rejects the granular material at a rejection position and sets an appropriate rejection duration for rejecting the granular material; and an ejector condition changing unit that, based on the flow rate of the granular material, sets the rejection duration and the delay time previously set by the ejector control unit to be longer when the flow rate is small and shorter when the flow rate is large,
The ejector control section employs a technical measure in which the flow rate level is divided into a plurality of stages, and the ejection duration time and the delay time are set for each stage.

In the invention according to claim 2, it is preferable to provide a flow rate calculation unit that calculates the flow rate density of the granular material from an image captured by an imaging unit provided in the optical detection unit, and calculates the flow rate of the granular material from the flow rate density.

In the invention according to claim 3, a storage tank for storing the granular material is provided upstream of the chute, a storage amount detection unit is provided in the storage tank, and the flow rate of the granular material flowing down the chute is estimated from the storage amount detected by the storage amount detection unit.

According to the invention of claim 1, the removal duration and delay time of the ejector operation, which are preset in the ejector control unit based on the flow rate of the granular material flowing on the chute, are set to be longer when the flow rate is small and set to be shorter when the flow rate is large. Therefore, even if the flow rate of the granular material flowing on the chute decreases and the granular material flows down the chute surface in a sparse state and the granular material flows down the chute surface while bouncing, changing the falling speed, the removal duration and delay time of the ejector operation are changed, so that there is no risk of errors in detecting and removing defective products or foreign objects, and defective products and foreign objects can be accurately removed, thereby maintaining high sorting accuracy.

According to the invention of claim 2, when determining the flow rate of the granular material flowing down the chute, the flow density of the granular material is calculated from the image obtained by the imaging unit provided in the optical detection unit, and the flow rate is determined by a flow rate calculation unit that calculates the flow rate of the granular material from the flow rate density.Therefore, the granular material flowing down the chute can be directly observed, a decrease in the flow rate of the granular material can be detected early, and the removal duration and delay time of the ejector operation can be changed at an appropriate timing.

According to the invention of claim 3, a storage tank for storing the granular material is provided upstream of the chute, and a storage amount detection unit is provided in the storage tank. The flow rate of the granular material flowing down the chute is estimated from the storage amount detected by the storage amount detection unit. Therefore, a decrease in the storage amount of the granular material in the storage tank is detected, and then a decrease in the flow rate of the granular material flowing down the chute is estimated. Therefore, a decrease in the flow rate of the granular material can be detected early, and the removal duration and delay time of the ejector operation can be changed at an appropriate timing.

FIG. 1 is a schematic vertical cross-sectional view showing an internal structure of an optical sorting machine in one embodiment of the present invention. FIG. 2 is a block diagram of a control processing means of the optical sorting machine in one embodiment of the present invention. FIG. 13 is an image showing the flow of granular matter captured by the optical detection unit. FIG. 2 is a diagram illustrating an overview of flow levels in one embodiment of the present invention.

The following describes an embodiment of the optical sorting machine of the present invention with reference to the drawings. Figure 1 is a schematic vertical cross-sectional view showing the internal structure of the optical sorting machine 1 in this embodiment, and Figure 2 is a block diagram showing the configuration of the control processing means of the optical sorting machine 1.

(Configuration of optical sorting machine)
As shown in FIG. 1, the optical sorting machine 1 is provided within a machine frame 2 with a chute 4 as a means for transporting granular material (grains) at an angle of about 60 degrees from the horizontal position to transport the grains, a storage tank 5 for storing the grains, a vibrating feeder 6 for transporting the grains from the storage tank 5 to the chute 4, optical detection units 7a, 7b provided above and below the falling trajectory of the grains falling from the lower end of the chute 4, an ejector 8 provided further below, a non-defective product recovery gutter 9 located below the ejector 8 on the same inclined line as the chute 4 and for receiving grains that fall along the falling trajectory without being subjected to the air jet from the ejector nozzle 80, a defective product recovery gutter 10 provided in parallel to the non-defective product recovery gutter 9 for recovering defective grains that have been subjected to the air jet from the ejector nozzle 80, and an auxiliary defective product recovery gutter 11 for recovering defective grains that have missed the air jet from the ejector nozzle 80 and bounced off surrounding members. A sensor 5a is disposed at a predetermined position in the storage tank 5, and when the sensor 5a detects that the amount of grains in the storage tank 5 falls below a predetermined amount, it transmits a signal.

The chute 4 is flat and groove-free to allow the grains to slide in a wide band, and a cover 4a is provided to prevent the grains from spilling out of the chute 4.

The vibrating feeder 6 is configured such that a feeder trough 6a is supported on a support portion 6b, and grains can be supplied to the chute 4 by operating a vibrating member such as an electromagnetic driving coil 6c. The shape of the chute 4 described above may be such that a groove is formed, and the cross-sectional shape of the groove may be U-shaped, V-shaped, concave, or the like, as appropriate.

The optical detection units 7a and 7b, which are the inspection units that perform the optical inspection, are surrounded by boxes 12a and 12b, respectively. The box 12a, which is in front of the falling trajectory of the grains, houses a CCD camera 13a for visible light, a NIR camera 14 for near-infrared light, visible light sources 15a and 15b such as fluorescent lamps, a near-infrared light source 16a such as a halogen lamp, and a background 17a that faces the optical detection unit 7b.

The box 12b behind the grain fall path houses a CCD camera 13b for visible light, visible light sources 15c and 15d such as fluorescent lamps, a near-infrared light source 16b such as a halogen lamp, and backgrounds 17b and 17c for facing the optical detection unit 7a. The box 12a and 12b are fitted with window members 18a and 18b made of transparent glass on the grain fall path side.

In the ejector 8 of the optical sorting machine 1 of this embodiment, 48 ejector nozzles 80 are arranged in a row at equal intervals in the same direction as the width direction of the chute 4, and each ejector nozzle 80 is provided with an ejector solenoid valve 81 that turns on/off the injection of compressed air. The number of ejector nozzles 80 can be changed appropriately depending on the width dimension of the chute 4, etc. In addition, the ejector 8 of this embodiment is capable of storing compressed air inside, and is configured so that air is supplied from an air compressor (not shown) through an air supply pipe 22. In addition, one or more sub-tanks (not shown) for temporarily storing air may be provided between the ejector 8 and the air compressor. With this configuration, there is no risk of air shortage even when the amount of air injected from the ejector nozzle 80 is large.

A front door 24 that can be rotated up and down by an air cylinder 23 is provided on the inclined wall at the front of the machine frame 2, making it easy to perform maintenance work such as cleaning. In addition, below the front door 24, there is a liquid crystal display 25 that functions as a setting input means that combines a touch panel control panel and a monitor, and a power switch (not shown). By arranging the liquid crystal display 25 and power switch at eye height of the operator, the machine can be easily operated.

As shown in FIG. 1, a defective product receiving port 27, a non-defective product receiving port 28, and an auxiliary defective product receiving port 29 are provided as receiving ports for the sorted grains, and a sample removal section 30 is provided above the defective product receiving port 27.

Next, the configuration of the control processing means of the optical sorting machine 1 will be described with reference to Figure 2. The CCD cameras 13a and 13b for visible light and the NIR camera 14 for near-infrared light are electrically connected to a signal processing unit 31 to perform binarization processing of the acquired images, and the signal processing unit 31 is further connected to a memory unit 32 that stores the images and performs the necessary processing. The aforementioned liquid crystal display 25 is electrically connected to the memory unit 32.

Furthermore, the signal processing unit 31 includes at least an image data acquisition unit 33 that temporarily stores image data, a threshold data storage memory 34 that stores threshold data for determining whether the acquired image data is to be treated as a good or defective product, a binarization calculation mechanism 35 that performs binarization processing on the acquired image data, a good/defective product determination unit 36 that functions as a determination unit for determining whether the product is good or defective, and an ejector control unit 37 that controls the operation of the ejector 8.

The CCD cameras 13a and 13b for visible light and the NIR camera 14 for near-infrared light are each connected to an amplifier that amplifies the voltage value via an I/V converter (not shown) that converts the light quantity detection value into a voltage value. The amplified voltage value (detection signal) is then compared with the threshold value stored in the threshold data storage memory 34 in the pass/fail judgment unit 36 to determine whether the product is pass or fail.

The memory unit 32 also includes at least an image data storage memory 38 that stores data from the image data acquisition unit 33 as necessary, a threshold data calculation mechanism 39 that calculates a threshold value for determining whether a grain is good or bad based on the image data stored in the image data storage memory 38, an ejector condition change unit 40 that changes the operation of the ejector 8, and an operation signal receiving mechanism 41 that receives touch operation signals on the LCD display 25 and outputs processed image data to the LCD display 25.

The good/bad product determination unit 36 in the signal processing unit 31 is electrically connected to the ejector control unit 37, which changes the operating conditions of the ejector 8 in the ejector condition change unit 40 in the memory unit 32, and controls the ejector drive circuit 42 to remove defective kernels based on the changed operating conditions. Examples of changes in the operating conditions of the ejector 8 include the delay time of the ejector operation and/or the duration of the ejector.

2, the ejector drive circuit 42 is electrically connected to each ejector solenoid valve 81 that turns on/off the injection of compressed air by each ejector nozzle 80, and is configured to open and close each ejector solenoid valve 81 by inputting a drive signal. As described above, the ejector operation delay time is the time from when kernels are detected by the CCD cameras 13a, 13b and the NIR camera 14 for near-infrared light as optical detection means until a drive signal is input to each ejector solenoid valve 81. The ejector duration is the time that determines the length of compressed air injection from when a drive signal is input to each ejector solenoid valve 81 until a stop signal is input.

As described above, the ejector 8 of this embodiment has 48 ejector nozzles 80, each of which has a one-to-one correspondence with an ejector solenoid valve 81. Figure 2 shows the first ejector solenoid valve 81a, the second ejector solenoid valve 81b, and the third ejector solenoid valve 81c, which are adjacent to each other and capable of injecting compressed air, among the 48 ejector solenoid valves 81.

(Sorting process configuration)
The sorting process of the optical sorting machine 1 in this embodiment will be described in detail below.

The optical sorting machine 1 in this embodiment is characterized by the provision of an ejector condition change unit 40 that changes the ejection delay time and/or ejection duration preset by the ejector control unit 37 depending on the flow rate of grains falling from the bottom end of the chute 4.

Figure 3 is an image showing the flow of granular material captured by the optical detection unit. Images like those in Figure 3 can be acquired from the CCD cameras 13a, 13b of the optical detection units 7a, 7b and the NIR camera 14 for near-infrared light. Then, the flow rate data can be calculated from the ratio of the area of the granular material to the total area of this captured image, i.e., the flow rate density. This allows direct observation of the granular material flowing down the chute surface. The flow rate data can be calculated using the free capacity of the image data acquisition unit 33, binarization calculation mechanism 35, image data storage memory 38 (Figure 2), etc. as a flow rate calculation unit (not shown).

When judging the flow density with reference to Figure 3, in Figure 3(a), the flow rate of the grains flowing up the chute 4 is high and they are flowing in a dense state onto the chute 4. On the other hand, in Figure 3(b), the flow rate of the grains flowing up the chute 4 is low and they are flowing in a sparse state onto the chute 4. In this case, in the sparse state of Figure 3(b), the grains are more likely to float up from the bottom of the chute 4 while sliding down the chute 4 compared to the dense state of Figure 3(a). In other words, the grains flow down the surface of the chute 4 while "bouncing", and when they flow down like this, air resistance causes the falling speed to differ from the normal state.

Therefore, when the flow state of grains on the chute 4 changes from a normal "dense" state to a "sparse" state just before the end of operation, the ejector condition change unit 40 changes the ejection duration and delay time of the ejector 8 when removing defective grains. For example, as shown in FIG. 4, it is possible to set from level 1 (small flow rate) to level 3 (large flow rate). If the steady state of the flow rate is level 2, the ejection duration and delay time of the ejection are made longer than those of level 2 at level 1 where the flow rate is small, and the ejection duration and delay time of the ejection are made shorter than those of level 2 at level 3 where the flow rate is large. The ratio of the ejection duration and delay time of the ejection is preferably in the range of 1.1 to 1.9 times, assuming that the standard level 2 is 1.0. The ratio of the ejection duration and delay time of the ejection is preferably in the range of 0.4 to 0.9 times, assuming that the standard level 2 is 1.0.

In the "Level 1" setting shown in Figure 4, it is assumed that the grains will "bounce" as they flow down the surface of the chute 4, and even if the falling trajectory and falling speed change due to air resistance, the ejection duration and delay time are set long, so that compressed air is ejected for a sufficient period of time at the grains to be removed, ensuring that defective grains are removed, improving sorting accuracy and producing high-quality products.

On the other hand, in the setting of "Level 3" shown in Figure 4, the flow rate is excessive, so it is preferable to quickly select and remove the grains in order to maximize the processing capacity. In this case, the grains flow continuously in layers on the surface of the chute 4, and the "bouncing" phenomenon does not occur. In addition, since the ejection removal duration and delay time are set to be short, compressed air is quickly ejected for a short time on the grains to be removed, and defective grains can be removed reliably at high speed, improving the sorting accuracy and enabling the processing capacity to be maximized.

Other Embodiments
One embodiment of the optical sorting machine of the present invention has been described above. However, the present invention is not necessarily limited to the above-described embodiment, and includes, for example, the following modified examples.

In the above embodiment, image acquisition from the CCD cameras 13a, 13b of the optical detection units 7a, 7b and the NIR camera 14 for near-infrared light was used when calculating the flow rate data, but this is not necessarily limited to this. For example, in order to detect when the operation of the optical sorting machine 1 is about to end, a sensor 5a may be disposed in the storage tank 5 installed in front of the chute 4, and the flow rate of the granular material flowing down the chute may be estimated from the storage amount detected by the sensor 5a.

In addition, in the above embodiment, the flow rate levels are set to three levels, from "Level 1" to "Level 3", but this is not necessarily limited to three levels, and any number of flow rate levels can be set.

In addition, in the above-described embodiment, the ratio at which the injection elimination duration and delay time are lengthened and the ratio at which the injection elimination duration and delay time are shortened are set, but any ratio can be set.

In the above-described embodiment, the flow rate data of the grains flowing down the chute 4 is automatically calculated, but it is also possible to add a switching means that allows the user to visually grasp the flow rate data and turn ON/OFF the extension of the spray removal duration and delay time or the shortening of the spray removal duration and delay time, and it is also possible to set these ratios individually and in detail.

Although the above describes the embodiment of the present invention and some variations, the above-mentioned embodiment of the invention is intended to facilitate understanding of the present invention and does not limit the present invention. The present invention may be modified or improved without departing from its spirit, and the present invention includes equivalents. Furthermore, the components described in the claims and specification may be combined or omitted to the extent that at least part of the above-mentioned problems can be solved or at least part of the effects can be achieved.

1 Optical sorting machine 2 Machine body 4 Chute 4a Chute cover 5 Storage tank 6 Vibration feeder 6a Feeder trough 6b Support section 6c Electromagnetic drive coil 7a Optical detection section 7b Optical detection section 8 Ejector 9 Good product collection trough 10 Defective product collection trough 11 Auxiliary defective product collection trough 12a Box body 12b Box body 13a CCD camera 13b CCD camera 14 NIR camera 15a Visible light source 15b Visible light source 15c Visible light source 15d Visible light source 16a Near infrared light source 16b Near infrared light source 17a Opposing background 17b Opposing background 17c Opposing background 18a Window member 18b Window member 22 Air supply pipe 24 Front door 25 Liquid crystal display 27 Defective product receiving port 28 Good product receiving port 29 Auxiliary defective product receiving port 30 Sample removal section 31 Signal processing section 32 Memory section 33, image data acquisition section 34, threshold data storage memory 35, binarization calculation mechanism 36, pass/fail determination section 37, ejector control section 38, image data storage memory 39, threshold data calculation mechanism 40, sorting strength setting section 41, operation signal receiving mechanism 42, ejector drive circuit 80, ejector nozzle 81, ejector solenoid valve 81a, first ejector solenoid valve 81b, second ejector solenoid valve 81c, third ejector solenoid valve

Claims (3)

a chute that allows the granular material to flow downward at a predetermined flow rate;
an optical detection unit that inspects the granular material dropping from the lower end of the chute at a predetermined position;
an ejector that rejects and separates the granular matter based on a detection result by the optical detection unit;
an ejector control unit that sets a delay time from when the granular object is detected at the predetermined position by the optical detection unit until when the granular object is removed at a removal position by the ejector, and also sets an appropriate removal duration for removing the granular object, when removing and sorting the granular object;
an ejector condition changing unit that sets the removal duration and the delay time, which are preset by the ejector control unit, to be longer when the flow rate is small and sets them to be shorter when the flow rate is large, based on the flow rate of the granular matter;
An optical sorting machine comprising:
The optical sorting machine, wherein the ejector control section divides the flow rate level into a plurality of stages, and sets the ejection duration and the delay time for each stage. Calculating a flow density of the granular matter from an image captured by an imaging unit included in the optical detection unit;
2. The optical sorting machine according to claim 1, further comprising a flow rate calculation unit that calculates the flow rate of the granular material from the flow rate density. a storage tank for storing the granular material is provided upstream of the chute;
The storage tank is provided with a storage amount detection unit,
2. The optical sorting machine according to claim 1, wherein the flow rate of the granular material flowing down the chute is estimated from the accumulated amount detected by the accumulated amount detection unit.

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