Abstract:
A chute for an optical sorter sorting machine allows objects to be sorted to drop under gravity from the lower end of the chute, thereby supplying the objects to an optical detection section. The chute is provided with: a first portion which includes a portion for receiving the objects to be sorted which are supplied from a supply section; and a second portion which continues from the first portion The first portion is composed of a single part and has: flat surfaces along which the objects to be sorted flow down; and connection surfaces. The flat surfaces located upstream are bent downward, and the connection surfaces located downstream are is bent upward to form a smooth undulation in the surface along which the objects to be sorted flow down.

Description:
TECHNICAL FIELD  
       [0001]    The present invention relates to an optical sorting machine for sorting out granular articles such as grains and plastic pellets on the basis of colors or the like, and particularly relates to a chute used for the optical sorting machine. 
       BACKGROUND ART  
       [0002]    Conventionally, an optical sorting machine is known for sorting out raw material composed of grains such as rice, barley, wheat, oats, beans and nuts, plastic pieces such as pellets and beads, fine articles such as drugs, ores and volcanic soil, or other granular articles into good articles or defective articles and/or excluding foreign objects and the like contaminating the raw material. 
         [0003]    Optical sorting machines of this kind include one of the type in which a chute with a predetermined width is inclined and disposed on the downside of a granular article feeding part. 
         [0004]    The optical sorting machine sorts out the granular articles by: feeding a large amount of granular articles to the chute having the predetermined width from the granular article feeding part; irradiating, with light, the granular articles which flow down the chute surface, spreading in the width direction, and which undergo free fall along a predetermined path from the lower end of the chute; receiving the reflected light and the like from the granular articles to detect defective articles, foreign objects and the like contained in the raw material; and excluding the detected defective articles, foreign objects and the like from the predetermined path. 
         [0005]    Incidentally, in the above-mentioned optical sorting machine, when the raw material is granular articles with long and thin shapes such as long grain rice, granular articles with viscosity on the surfaces such as parboiled rice, or the like, the plural granular articles overlapping with and/or being joined to one another are liable to cause unevenness of the flow of the granular articles on the chute surface. As a result, there has been a problem that failure in detection of defective articles and the like, and/or failure in exclusion, for example, exclusion of good articles mixed up with the defective articles can arise. 
         [0006]    Therefore, as for the optical sorting machines, a chute for preventing unevenness of the flow of granular articles is proposed (see Patent Literature 1). 
         [0007]      FIG. 7  shows a schematic diagram for explaining the chute disclosed in Patent Literature 1,  FIG. 8  shows a lateral view of the chute shown in  FIG. 7 . Moreover,  FIG. 9  shows an enlarged view of the B part in  FIG. 8 . 
         [0008]    A chute  6  disclosed in Patent Literature 1 includes components  61  to  64  composed of a plurality of plate shapes with flat surfaces. 
         [0009]    In the chute  6 , the downstream side end part of the component that positions on the upstream side is overlapped with the upstream side end part of the component that positions on the downstream side sequentially, and thereby, the flat surfaces of the plurality of components  61  to  64  are assembled with the steps included to form the surface which granular articles flow down. 
         [0010]    According to the above-mentioned chute  6 , since the granular articles disperse due to the impacts in dropping over the steps, unevenness of the flow of the granular articles on the chute surface can be prevented. 
         [0011]    However, in the above-mentioned chute  6 , as shown in  FIG. 9 , since the granular articles dropping over the step are liable to cause hops thereof, a problem arises that the flow of the granular articles is hardly stabilized on the surface of the component that positions on the downstream side. 
         [0012]    Moreover, in the above-mentioned chute  6 , since powdery dusts are liable to swirl when the granular articles are dropping over the steps and there is a risk that powdery dusts  65  sticking and deposited on the step part contaminate the granular articles as foreign objects, the step part is needed to be cleaned periodically. 
       CITATION LIST  
     Patent Literature 
       [0000]    
       
         Patent Literature 1 U.S. Patent Application Publication No. 2010/0096300 
       
     
       SUMMARY OF THE INVENTION 
     Technical Problem 
       [0014]    Therefore, an object of the present invention is to provide a chute which does not cause hops of granular articles and deposition of powdery dusts and which can prevent unevenness of the flow of granular articles on the surface. 
         [0015]    Moreover, an object of the present invention is to provide an optical sorting machine including a chute which does not cause hops of granular articles and deposition of powdery dusts and which can prevent unevenness of the flow of granular articles on the surface. 
       Solution to the Problem 
       [0016]    In order to achieve the above-mentioned objects, the present invention is characterized in a chute for an optical sorting machine, the chute: receiving a sorted article fed from a feeding part; allowing the received sorted article to flow down a surface; and after that, allowing the sorted article to undergo free fall from a lower end and to be fed to an optical detecting part, the chute including: a first part including a part for receiving the sorted article fed from the feeding part; and a second part succeeding the first part and allowing the sorted article to undergo free fall from the lower end, wherein the first part is composed of one component, the first part has: a plurality of flat surfaces which the sorted article flows down; and a joint plane joining the plurality of flat surfaces at an obtuse angle in a direction in which the sorted article flows down, the joint plane is configured by bending the flat surface that positions on an upstream side downward and the flat surface that positions on a downstream side is configured by bending the joint plane upward, and thereby, a smooth undulation is formed on the surface which the sorted article flows down. 
         [0017]    In addition, regarding the chute according to the present invention, it is preferable that the joint planes are formed such that their slopes are less than 90 degrees when they are disposed in the optical sorting machine. 
         [0018]    Regarding the chute according to the present invention, it is preferable that, while having the joint plane at a lower end of the first part, the first part is detachably attached to a chute body including the second part and is smoothly succeeded by the second part via the joint plane included at the lower end by being attached to the chute body. 
         [0019]    Regarding the chute according to the present invention, it is preferable that the first part and the second part are integrally formed of one component. 
         [0020]    The present invention is characterized in an optical sorting machine including: a chute: receiving a sorted article fed from a feeding part; and allowing the received sorted article to flow down a surface; optical detecting means for detecting the sorted article in free fall from a lower end of the chute at a predetermined detecting position; and ejector means for sorting out the sorted article on the basis of a detection result of the optical detecting means, wherein the chute includes: a first part including a part for receiving the sorted article fed from the feeding part; and a second part succeeding the first part and allowing the sorted article to undergo free fall from the lower end, the first part is composed of one component, the first part has: a plurality of flat surfaces which the sorted article flows down; and a joint plane joining the plurality of flat surfaces at an obtuse angle in a direction in which the sorted article flows down, the joint plane is configured by bending the flat surface that positions on an upstream side downward and the flat surface that positions on a downstream side is configured by bending the joint plane upward, and thereby, a smooth undulation is formed on the surface which the sorted article flows down. 
       Advantageous Effects of the Invention 
       [0021]    According to the chute of the present invention, since sorted articles disperse due to the impacts in their movements from the flat surface that positions on the upstream side to the flat surface that positions on the downstream side, unevenness of the flow of the sorted articles on the chute surface can be prevented. 
         [0022]    Moreover, since, in the first part of the chute according to the present invention, smooth undulations are formed on the surface which the sorted articles flow down and the sorted articles move between the plurality of flat surfaces with moderate impacts, hops of the sorted articles hardly arise on the first part. 
         [0023]    Furthermore, in the chute according to the present invention, since the first part is composed of one component and the continuity of the component is maintained, deposition of powdery dusts does not arise on the first part. 
         [0024]    Regarding the chute according to the present invention, when, while having the joint plane at a lower end of the first part, the first part is detachably attached to a chute body including the second part and is succeeded by the second part via the joint plane included at the lower end by being attached to the chute body, the first part can be properly modified according to the sizes, kind and the like of the sorted articles. 
         [0025]    Moreover, in that case, in the chute according to the present invention, since the first part can be detachable, the first part and the chute body can be cleaned easily. 
         [0026]    Furthermore, in the chute according to the present invention, when the plural sorted articles are granular articles such as short grain rice without a risk that they overlap with and/or are joined to one another, the first part can be detached in the usage. 
         [0027]    Moreover, regarding the chute according to the present invention, when the surface of the joint plane included at the lower end is smoothly succeeded by the surface of the second part without a step in attaching the first part to the chute body, the sorted articles can move between the flat surface that positions on the most downstream side of the first part and the surface of the second part with moderate impacts, and thus, hops of the sorted articles and deposition of powdery dusts hardly arise. 
         [0028]    Regarding the chute according to the present invention, when the first part and the second part are integrally composed of one component, since the continuity of the component is maintained, the sorted articles can move smoothly between the surface of the first part and the surface of the second part and hops of the sorted articles and deposition of powdery dusts do not arise. 
         [0029]    According to the optical sorting machine of the present invention, since sorted articles flowing down the chute surface disperse due to the impacts in the movements from the flat surface that positions on the upstream side to the flat surface that positions on the downstream side, unevenness of the flow of sorted articles on the chute surface can be prevented. 
         [0030]    Moreover, since, in the first part of the chute in the optical sorting machine according to the present invention, smooth undulations are formed on the surface which the sorted articles flow down and the sorted articles move with moderate impacts between the plurality of flat surfaces, hops of the sorted articles hardly arise on the first part. 
         [0031]    Furthermore, in the chute of the optical sorting machine according to the present invention, since the first part is composed of one component and the continuity of the component is maintained, deposition of powdery dusts does not arise on the first part. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a lateral cross-sectional view of an internal structure of an optical sorting machine. 
           [0033]      FIG. 2  is a schematic diagram of a chute according to an embodiment of the present invention. 
           [0034]      FIG. 3  is a lateral view of the chute in  FIG. 2 . 
           [0035]      FIG. 4  is an enlarged view of the A part in  FIG. 3 . 
           [0036]      FIG. 5  is a schematic diagram of a chute according to another embodiment of the present invention. 
           [0037]      FIG. 6  is a lateral view of the chute in  FIG. 5 . 
           [0038]      FIG. 7  is a schematic diagram of a conventional chute. 
           [0039]      FIG. 8  is a lateral view of the chute in  FIG. 7 . 
           [0040]      FIG. 9  is an enlarged view of the B part in  FIG. 8 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS  
       [0041]    Embodiments according to the present invention will be described with reference to the drawings. 
       &lt;Optical Sorting Machine&gt; 
       [0042]      FIG. 1  is one example of an optical sorting machine using a chute according to the present invention and shows a simplified lateral cross-sectional view of the internal structure of the optical sorting machine. 
         [0043]    An optical sorting machine  1  shown in  FIG. 1  includes a granular article feeding part  2 , a chute  3  and an optical sorting part  4 . 
         [0044]    The granular article feeding part  2  is disposed in the upper part of the optical sorting machine  1  and includes a tank  21  and a vibratory feeder  22  for feeding granular articles in the tank  21 . 
         [0045]    The chute  3  has a predetermined width and is disposed inclining on the downside of the granular article feeding part  2 . 
         [0046]    A large amount of granular articles continuously fed from the vibratory feeder  22  of the granular article feeding part  2  continuously flow down the surface of the chute  3  on the basis of the action of gravity, spreading in the width direction, and after that, are allowed in free fall along a predetermined path from the lower end of the chute  3 . 
         [0047]    The optical sorting part  4  includes: a pair of optical detectors  41   a  and  41   b  arranged in front of and behind the falling path of the granular articles; a discriminating device  42  for judging the granular articles to be good articles or defective articles on the basis of imaging signals of the optical detectors  41   a  and  41   b ; an ejector  43  for excluding the defective articles on the basis of the judgment results of the discriminating device  42  to sort out the granular articles into the good articles or the defective articles; and a discharge hopper  44  for discharging the granular articles sorted out into the good articles or the defective articles by the ejector  43 . 
         [0048]    Herein, the optical detectors  41   a  and  41   b  contain line sensors and/or area sensors such as CCDs operable for granular articles in free fall which are spreading from the lower end of the chute  3  in the width direction, and they respectively include: imaging means  411   a ,  411   b  such as CCD cameras capable of receiving light with a wavelength range of NIR (near-infrared light), visible light, ultraviolet light or the like; illumination means  412   a ,  412   b  such as fluorescent lamps, halogen lamps and LED light sources for illuminating a detecting position O on the falling path of the granular articles; and backgrounds  413   a  and  413   b  as the backgrounds in imaging the granular articles at the detecting position O with the imaging means. 
         [0049]    Moreover, similarly to the optical detectors  41   a  and  41   b , the ejector  43  is operable for granular articles in free fall which are spreading from the lower end of the chute  3  in the width direction, and includes a nozzle  431  from whose plural nozzle holes formed in the width direction the air can be selectively ejected. 
         [0050]    In the above-mentioned optical sorting machine  1 , the granular articles stored in the tank  21  of the granular article feeding part  2  are continuously fed to the chute  3  via the vibratory feeder  22 , are allowed to undergo continuous free flow-down on the surface of the chute  3  in the state of spreading in the width direction, and after that, are allowed to undergo free fall from the lower end of the chute  3  along a predetermined path. 
         [0051]    The granular articles in free fall are imaged at the detecting position O on the falling path by the imaging means  411   a ,  411   b  of the pair of optical detectors  41   a  and  41   b  in the optical sorting part  4 . 
         [0052]    The granular articles imaged by the imaging means  411   a ,  411   b  are compared with thresholds regarding the signal levels of the imaging signals in light amount and color components by the discriminating device  42 , and judged to be any of the good articles and the defective articles. 
         [0053]    Then, the granular articles are sorted out into the good articles or the defective articles, the defective articles excluded from the predetermined falling path with the air ejected by the ejector  43  on the basis of exclusion signals sent from the discriminating device  42 . The good articles and the defective articles are discharged from a good article discharge chute  441  and a defective article discharge chute  442  of the discharge hopper  44 , respectively. 
         [0054]    Incidentally, the optical sorting machine using the chute according to the present invention only has to include: a feeding part for feeding granular articles to the chute; optical detecting means for detecting the granular articles in free fall from the chute lower end; and ejector means for excluding and sorting out specific granular articles on the basis of the detection results of the optical detecting means. Specific configurations of the feeding part, the optical detecting means and the ejector means are not limited to those mentioned above. 
       &lt;Chute&gt; 
       [0055]      FIG. 2  shows a schematic diagram for explaining a chute according to the embodiment of the present invention.  FIG. 3  shows a lateral view of the chute shown in  FIG. 2 . Moreover,  FIG. 4  shows an enlarged view of the A part in  FIG. 3 . 
         [0056]    The chute  3  according to the embodiment includes: a first part  31  including a part for receiving the granular articles fed from the vibratory feeder  22  of the granular article feeding part  2  in the optical sorting machine  1 ; and a second part  32  which succeeds the first part  31 , allows the granular articles received by the first part  31  to flow down the surface, and after that, allows them to undergo free fall from the lower end. 
         [0057]    As shown in  FIG. 2  and  FIG. 3 , the cute  3  according to the embodiment is formed, for example, by processing a plate material composed of one component such as a stainless steel plate having a flat surface by means of a press or the like. 
         [0058]    The first part  31  has a plurality of flat surfaces  34   a  to  34   c  which the granular articles flow down and a plurality of joint planes  35   a  to  35   c  joining the plurality of flat surfaces at obtuse angles in the direction in which the granular articles flow down. 
         [0059]    Specifically, in the first part  31 , the first joint plane  35   a  is formed by bending the downstream side end part of the first flat surface  34   a  positioning on the upstream side downward, and the second flat surface  34   b  is formed by bending the downstream side end part of the first joint plane  35   a  upward. Moreover, the second joint plane  35   b  is formed by bending the downstream side end part of the second flat surface  34   b  downward, and the third flat surface  34   c  is formed by bending the downstream side end part of the second joint plane  35   b  upward. Furthermore, the third joint plane  35   c  is formed by bending the downstream side end part of the third flat surface  34   c  downward. 
         [0060]    Then, in the chute  3  according to the embodiment, the downstream side end part of the third joint plane  35   c  is succeeded by a flat surface  36  of the second part  32  which surface is in a mode where the end part is bent upward, and thereby, smooth undulations are formed on the entire chute surface which the granular articles flow down. 
         [0061]    Herein, in the chute  3  according to the embodiment, the joint planes  35   a  to  35   c  are formed such that their slopes are less than 90 degrees when they are disposed in the optical sorting machine. 
         [0062]      FIG. 4  is an enlarged view of the A part in  FIG. 3  and shows movements of the granular articles between the plurality of flat surfaces  34   a  and  34   b . 
         [0063]    As shown in  FIG. 4 , according to the chute  3  of the embodiment, the granular articles move from the first flat surface  34   a  positioning on the upstream side to the second flat surface  34   b  positioning on the downstream side with moderate impacts. 
         [0064]    Therefore, according to the chute  3  of the embodiment, since the granular articles disperse due to the impacts in their movements between the flat surfaces  34   a  to  34   c  and  36  on the first part  31  and the second part  32 , it can be prevented that the granular articles flow down the surface of the chute  3  in the state of overlapping with and/or being joined to one another, and as a result, unevenness of the flow of the granular articles on the chute surface can be prevented. 
         [0065]    Moreover, in the chute  3  according to the embodiment, since the smooth undulations are formed on the surface which the granular articles flow down and the granular articles move between the flat surfaces  34   a  to  34   c  and  36  with moderate impacts, hops of the granular articles hardly arise on the chute surface. 
         [0066]    Furthermore, in the chute  3  according to the embodiment, since the entire surface of the chute is composed of one component and the continuity of the component is maintained, deposition of powdery dusts does not arise on the chute surface. 
         [0067]    The above-mentioned chute  3  according to the embodiment has been described, exemplified by the first part  31  having the three flat surfaces  34   a  to  34   c , whereas the first part  31  only has to have two or more flat surfaces. 
         [0068]    Moreover, in the above-mentioned chute  3  according to the embodiment, the plurality of flat surfaces do not have to be parallel to one another. 
         [0069]    In the above-mentioned chute  3  according to the embodiment, the part for receiving the granular articles fed from the vibratory feeder  22  of the granular article feeding part  2  in the optical sorting machine  1  may have two or more of flat surfaces continuing via the joint plane. 
         [0070]    In the chute  3  according to the embodiment, the part for receiving the granular articles may have a plurality of protruding parts on the flat surfaces. 
         [0071]    In the chute  3  according to the embodiment, when the part for receiving the granular articles has two or more flat surfaces continuing via the joint plane or has a plurality of protruding parts on the flat surfaces, dispersion of the granular articles flowing down the chute surface becomes effective. 
         [0072]    In the chute  3  according to the embodiment, the second part  32  may have a length enough to be able to stabilize the flow of the granular articles. 
         [0073]    Furthermore, dimensions of the chute  3  according to the embodiment can be properly determined in consideration of circumstances such as the dimensions and processing capability of the optical sorting machine and the sizes and kind of the granular articles as a sorting target. 
         [0074]    In addition, in the chute  3  according to the embodiment, the second part  32  has a flat surface, whereas it may have grooves with U shapes or V shapes which grooves are parallel to the direction of flow-down of the granular articles. 
       Another Embodiment According to the Present Invention 
       [0075]      FIG. 5  shows a schematic diagram for explaining a chute according to another embodiment of the present invention. Moreover,  FIG. 6  shows a lateral view of the chute shown in  FIG. 5 . 
         [0076]    In the chute  3  according to the embodiment, the first part  31  for receiving the granular articles is composed of another component separate from the chute body  37  including the second part  32 , and is detachably attached to the upper end of the chute body  37 . 
         [0077]    In the chute  3  according to the embodiment, the first part  31  has the same configuration as that of the first part  31  according to the embodiment that is shown in  FIG. 2  and  FIG. 3 , and is attached to the chute body  37  such that the surface of the third joint plane  35   c  in the first part  31  is smoothly succeeded by the flat surface  36  in the second part  32 . 
         [0078]    Therefore, according to the chute  3  of the embodiment, the first part  31  can be properly modified according to the sizes, kind and the like of the granular articles. 
         [0079]    In the chute  3  according to the embodiment, since the first part  31  is detachable, the first part  31  and the chute body  37  can be cleaned easily. 
         [0080]    Moreover, in the chute  3  according to the embodiment, when the plural granular articles are granular articles such as short grain rice without a risk that they overlap with and/or are joined to one another, the first part  31  can be detached in the usage. 
         [0081]    Moreover, regarding the chute  3  according to the embodiment, when the surface of the third joint plane  35   c  is smoothly succeeded by the flat surface  36  of the second part  32  without a step in attaching the first part  31  to the chute body  37 , the granular articles can move between the surface  34   c  of the first part  31  and the surface  36  of the second part  32  with moderate impacts, and thus, hops of the granular articles and deposition of powdery dusts hardly arise. 
         [0082]    It should be noted that the chute according to the present invention is not limited to the above-mentioned embodiments but modifications in configuration thereof may properly occur without departing from the scope of the present invention. 
       INDUSTRIAL APPLICABILITY  
       [0083]    The chute according to the present invention is significantly useful because hops of granular articles and disposition of powdery dusts do not arise and unevenness of the flow of granular articles on the surface can be prevented. 
       List of Reference Signs 
       [0000]    
       
           1  Optical sorting machine 
           2  Granular article feeding part 
           21  Raw material tank 
           22  Vibratory feeder 
           3  Chute 
           31  First part 
           32  Second part 
           33  Component 
           34   a - 34   c  Surfaces of first part 
           35   a - 35   c  Joint planes 
           36  Plane of second part 
           37  Chute body 
           4  Optical sorting part 
           42  Discriminating device 
           43  Ejector 
           44  Discharge hopper 
           6  Chute 
           61 - 64  Components 
           65  Powdery dusts