EP3900849B1 - Optical sorting system for sorting granular particles - Google Patents

Description

From the prior art, such as EP 0 705 650 A2 , optical sorting systems for the sorting of granule particles are known, with granule particles supplied by means of the sorting systems being able to be divided or sorted at least into a first and second granule fraction. The optical sorting systems known from the prior art usually have a metering chute for transferring the granulate particles to be sorted onto a conveyor belt, via which the particles to be sorted can be applied to the conveyor belt using gravity. It is also known from the prior art to accelerate the granulate particles to a defined speed by means of the conveyor belt and to throw them off the conveyor belt at a discharge end and to transfer them into a free trajectory, to detect the granulate particles at a distance from the discharge end by means of an optical sensor device and Depending on a detection criterion, the particles to be separated which do not meet the required quality criteria are rejected by means of a discharge device.

From the WO 2016/096802 A1 and from the EP 3 488 932 A1 are sorting systems for bulk materials with a conveyor belt and at least one electrical or electromagnetic excitation device or a magnetic device in the area of a The end of the conveyor belt is known. The aforementioned sorting systems use the properties of different electrical conductivity inherent in the sorted goods in order to use the excitation device or magnet device to cause different forces to separate the bulk goods into different fractions.

The optical sorting systems known from the prior art have the disadvantage that an uncontrolled amount of granulate particles is fed onto the conveyor belt, such that it is not ensured that only a monolayer of granulate particles is applied to the conveyor belt by means of the metering chute. Furthermore, the discharge devices known from the prior art, which are implemented using air pulses and shovel devices, are inaccurate and do not enable precise discharge of deviating particles.

Based on the aforementioned prior art, the object of the present invention is to improve the known optical sorting systems in such a way as to enable reliable detection and discharge of the granulate particles to be rejected, as well as to reduce the required installation space of the optical sorting system and to increase its sorting speed.

According to the invention, the object is achieved by an optical sorting system for sorting granulate particles into at least a first and second granule fraction with the features of claim 1, wherein, among other things, the optical sorting system has a dosing device, a conveyor belt, an optical sensor device, a discharge device, a control device and comprises at least a first and second granule fraction outlet. It is envisaged that the granulate particles are applied to the conveyor belt in a monolayer via the metering device, accelerated to a defined speed by means of the conveyor belt, thrown off the conveyor belt at a discharge end and transferred into a first free trajectory, the optical Sensor device generates optical recordings of the granulate particles in the area of the discharge end, preferably after the discharge, and transmits them to the control device, the control device using the optical recordings and evaluating at least one detection criterion to assign the granulate particles to the at least one first or second granule fraction and when assigning a granulate particle a control pulse is transmitted to the discharge device for the second granule fraction, wherein in the area of the free flight path of the granulate particles is arranged at a defined distance from the discharge end of the first granule fraction outlet, and wherein at
By transmitting a control pulse, the discharge device transfers the granule particles assigned to the at least one second granule fraction into at least a second trajectory before reaching the first granule fraction outlet and discharges them into at least one second granule fraction outlet.

The granulate particles are applied to the conveyor belt at a first end opposite the discharge end. The granulate particles are applied to the conveyor belt via a metering device, by means of which a defined amount of granulate particles is applied to the conveyor belt per unit of time. The amount of granulate particles applied via the metering device per unit of time is controlled in such a way that a monolayer of granulate particles is applied to or produced on the conveyor belt. In the context of the present invention, a monolayer is understood to mean a distribution of the granulate particles on the conveyor belt in which there are no overlaps between the granulate particles on the conveyor belt. The granulate particles therefore do not lie one above the other on the conveyor belt, but rather are spaced apart from one another or touch one another.

It can be provided that the granulate particles are pre-screened by an upstream sieving device before being applied to the conveyor belt, that metallic foreign particles in the granules are removed by means of a metal separator and, if necessary, that the granulate particles are electrostatically discharged by means of at least one ionizer before being applied to the conveyor belt. Furthermore, it can be provided that the granulate particles are freed from dust particles by means of a countercurrent wind separator before they are applied to the conveyor belt. The aforementioned pretreatment steps ensure that only granulate particles pass through the detection area of the optical sorting system, which can be reliably detected and do not leave any damage or contamination in the area of the optical sensor device and the discharge device. In particular, it is made possible to remove metallic foreign bodies and, for example, unwanted dust particles before they are applied to the To remove the conveyor belt in such a way that the aforementioned contaminants no longer pass through the area of the optical sensor device. Contamination of the conveyor belt and the lighting background can also be largely ruled out using the pretreatment steps.

When thrown off the conveyor belt, the granulate particles are transferred into a first free trajectory with an idealized theoretical free throwing parabola. When the granulate particles transition from the conveyor belt into the free flight path, they initially only have the conveyor belt speed, which at the same time represents the initial flight speed of the particles. Essentially two forces influencing the trajectory act on the granulate particles along the first free trajectory: air resistance and, in addition, the force of gravity or gravity - which causes the theoretical or idealized parabolic trajectory of the granulate particles after being thrown off the conveyor belt.

Due to existing shape deviations of the different granulate particles to be sorted, but also due to deviations, such as unevenness, in the surface of the conveyor belt, in reality there are deviations of the thrown granulate particles from the idealized, theoretically assumed throwing parabola or trajectory. A scattering therefore occurs with regard to the trajectory of the granulate particles after they are thrown off the conveyor belt, such that the entirety of the thrown-off granulate particles describe a first corridor of the first free trajectory. As the distance of the thrown granulate particles from the discharge line at the discharge end of the conveyor belt increases along the trajectory, the resulting deviations from the idealized trajectory increase, such that the flight corridor of the granulate particles increases or expands as the distance to the discharge end increases. According to the invention, it can be provided to produce the optical images of the granulate particles at the shortest possible distance from the discharge line of the granulate particles from the conveyor belt. This embodiment has the Advantage of a low scattering of the trajectory of the granulate particles at the detection point, so that the depth of field of the sensor device is given while at the same time optimal lighting over the background.

The intended conveyor belt extends as a revolving, quasi-endless conveyor belt along the running direction of the conveyor belt from a first deflection device in the area of the end at which the granulate particles are fed onto the conveyor belt to a second deflection device at the discharge end at which the granulate particles are removed from the The conveyor belt is transferred into a free flight path and thus thrown off. Below the second deflection device, offset in the direction of the first deflection device, there is a third deflection device, which enables an oblique belt return. Between the two opposite first and second deflection devices, the conveyor belt essentially has a flat conveyor belt surface with a flat surface course in the conveyor belt direction. The conveyor belt can be delimited laterally by opposing belts in order to prevent the granulate particles from being thrown off or lost to the side and to allow the granulate particles to rebound on the belt surfaces.

The two opposite side conveyor belt edges run at a short distance from the side plates. The distance between the side plates and the edge of the conveyor belt creates an air gap through which a fluid stream can flow or be expelled. The opposing bands, which laterally delimit the conveyor belt, are arranged parallel to the plane of the conveyor belt surface at a small distance above the conveyor belt surface. The two opposite bands are each arranged at a distance from the two opposite side plates via corresponding spacers. The distance between the respective side plate and the band can be adjusted using a movable spacer, such that the resulting Transport belt width can be adjusted or finely adjusted via the spacers. The provision of fastening the bands via the spacers enables the air flow, which is carried out between the conveyor belt and the side panels, to be carried out to the area above the respective bands or the conveyor belt.

In the area of the deflection device on the discharge side, the conveyor belt is transferred from the flat course in the running direction into a surface course that is convex in the running direction of the conveyor belt. The transition between the flat and convex course forms a transition line transversely or orthogonally to the running direction of the conveyor belt, which is referred to as the discharge line, at which the granulate particles transition from the state resting on the conveyor belt into a free trajectory. The conveyor belt surface therefore essentially curves downwards away from the horizontal running direction in the area of the discharge end.

The discharge device can deflect at least one granule particle from the free trajectory by emitting at least one air pulse, or give it a desired speed vector with a defined speed amount and a defined direction. The resulting velocity vector is chosen such that it deviates from the velocity vector of the granulate particle along the free trajectory and directs or transfers the at least one particle into a second trajectory, which deviates from the first trajectory. The use of air pulses in the area of the discharge device to deflect the granulate particles from the free trajectory has the advantage that particles can be repeatedly deflected by the discharge device at very short time intervals without influencing the subsequent particles during ejection. This makes it possible to sort the stream of granulate particles with a high belt load, whereby a large amount of granules per unit of time can be sorted with the system according to the invention and thus the efficiency of the optical sorting system according to the invention can be increased compared to the prior art.

Particularly preferably, the at least one particle to be discharged is accelerated by the discharge device compared to the current speed on the first free trajectory and, after application of the air pulse, has a speed that is increased or at least the same as the speed on the first free trajectory. In particular, the magnitude of the speed can be accelerated in the direction of the trajectory of the granulate particle. The acceleration of the ejected particles compared to the flight speed on the free flight path prevents subsequent particles from impacting the ejected particle, which means that a build-up of the particles due to the particle ejection can be avoided.

The transport path along the conveyor belt and in particular the conveyor belt surface can run essentially along a flat plane which is approximately orthogonal to the vector of the earth's gravity or gravity and thus essentially horizontally aligned. The alignment of the conveyor belt or the conveyor belt surface essentially along a flat plane, which is essentially orthogonal to the vector of gravity, has the advantage that the particles fed onto the conveyor belt can calm down relatively quickly after being fed onto the conveyor belt . can reduce their kinetic energy relatively quickly due to the task on the conveyor belt, such that the particles only have the conveyor belt speed, at least in the area of the discharge end. In particular, it is avoided that the particles slide down from the conveyor belt at the discharge end due to their own weight and thus have an uncontrolled additional amount of speed. The granulate particles are transported along the transport path from the first end of the conveyor belt, at which the granulate particles are placed on the conveyor belt, to the discharge end accelerated to the sorting speed, which corresponds to the conveyor belt speed.

The at least one granule particle is deflected by the discharge device by means of at least one air pulse in such a way that the granule particle, which was assigned to the at least one second granule fraction, is discharged into the at least one second fraction outlet.

In the most basic embodiment of the sorting system according to the invention, the granulate particles to be sorted are sorted into a first and a second granule fraction. The first granulate fraction is preferably the so-called good fraction, into which the granulate particles are sorted, which correspond to the required quality criteria and therefore have no defects. The first granule fraction arrives along the parabola of the free flight path after being thrown off the conveyor belt into the first granule fraction outlet without additional intervention.

In the preferred embodiment, the second granule fraction is the so-called rejection fraction, which does not meet the required quality criteria and, for example, has defects such as color deviations, inclusions or shape deviations. The granulate particles that do not meet the required quality criteria are assigned to the second granule fraction by means of the sensor device by evaluating at least one detection criterion and are then transferred by means of the discharge device into a second trajectory that deviates from the first free trajectory, the granule particle being assigned to the rejection fraction , is transferred to the second granulate fraction outlet. According to the invention, however, the granulate particles can continue to be assigned to a plurality of first or second granule fraction outlets based on a plurality of detection criteria.

According to the invention, it can be provided that the optical sensor device generates recordings of the granulate particles in the area of the free flight path, the recordings being at a horizontal distance relative to a discharge line of the conveyor belt, on which the granulate particles are discharged, in the range of 5 mm to 40 mm, preferably in the range from 5 mm to 15 mm. According to the invention, however, it can also be provided to generate recordings of the granulate particles resting on the conveyor belt in the transport direction in front of the discharge line in the area of the discharge end of the conveyor belt by means of the optical sensor device, the recordings preferably being at a horizontal distance in the range of 5 mm to 40 mm, preferably in the range of 5 mm to 15 mm, generated from the discharge end. The arrangement of the optical sensor device for generating the recording immediately behind the discharge line of the conveyor belt has the advantage that the granulate particles to be detected in the above-described detection range only have small scatters in the trajectory, such that the sensor device focuses very precisely on the trajectory of the granulate particles or can be aligned. The generation of the optical recordings lying on the conveyor belt directly in the area in front of the discharge line has the advantage that the particles are guided in a defined detection plane, such that the optical detection device can be aligned and focused precisely on the particles to be detected. Another advantage in detecting the granulate particles lying on the conveyor belt is that the particles have a defined background in the form of the conveyor belt or the conveyor belt surface.

According to a preferred embodiment of the device according to the invention, it can be provided that the sensor device comprises a central visual axis, wherein the visual axis with the tangent of the free flight path at the intersection of the visual axis with the free flight path forms an angle in the range of 75 ° to 115 °, preferably in Range from 85° to 95°.

The central visual axis of the sensor device is defined by the sensor elements of the sensor device in connection with the optical beam path through an optics of the sensor device located in front of the sensor elements. The sensor device can be designed as a line sensor with a large number of individual sensors arranged in a row or alternatively as a two-dimensional surface sensor with a large number of individual sensors, which are arranged next to one another in columns and rows in a sensor matrix. The individual sensors can be referred to as pixels. The central visual axis in the area of the individual sensors is defined as a straight line which runs orthogonally to the plane of the individual sensors and intersects it at the center of the individual sensors. The visual axis can be redirected and influenced accordingly by the optics in front of the individual image sensors.

For example, the sensor device can be a CMOS sensor or a CCD sensor, which is focused on a specific detection area by means of optics in front of the sensor. The visual axis runs from the focus area through the optics to the sensor elements of the sensor device. It can also be provided that the sensor elements of the sensor device are formed by several commercially available CMOS sensors or CCD sensors.

The angle between the visual axis and the tangent of the free flight path is measured in a plane transverse to the direction of flight or trajectory of the granulate particles, with the angle on the side facing away from the discharge end between the visual axis and the tangent being determined.

The sensor device can generate recordings of the thrown granulate particles at a frequency in the range of 36 kHz to 150 kHz. The design of the sensor device with a frequency in the range from 36 kHz to 150 Khz enables a stream of granulate particles at a very high speed over the to detect optical sensor device and thus make it accessible to optical sorting.

Particularly preferably, the image recorded by the sensor device has a resolution in the range of 10 μm to 50 μm, preferably 15 μm or 25 μm, per pixel or individual image sensor. Due to the high resolution, it is possible to resolve and examine very small errors (artifacts) using the optical detection device.

According to a further preferred embodiment of the invention, it can be provided that the discharge device is arranged in the area of the free trajectory of the granulate particles at a horizontal distance relative to the detection line in a distance range of 2 cm to 9 cm, preferably in the range of 2 cm to 5 cm is. The arrangement of the discharge device in the areas described and therefore very close behind the discharge end has the advantage that the free trajectory of the granulate particles in this area still has a relatively small scatter, such that the granulate particles still approximately have the idealized theoretically calculated trajectory and so that the location of each granulate particle can be reliably determined via the flight speed and the distance of the discharge device relative to the detection line. This in turn makes it possible to prevent incorrect discharge of the discharge device and to safely eject the detected particles with errors or deviations without affecting further particles.

Furthermore, it can be provided that a lighting device is arranged in the area of the discharge end above and/or below the free trajectory of the granulate particles for illuminating the granulate particles. The provision of the lighting device makes it possible to achieve shorter exposure times with the optical sensor device and, in connection with this, also to enable higher image repetition rates, which in turn enable a higher optical resolution of the optical sorting system.

The lighting device comprises at least one light source, in particular a light-emitting diode. Furthermore, it can be provided to actively adjust and change the illumination intensity and the illumination color, in particular the wavelength or the color spectrum of the illumination device, using control electronics. By controlling the illumination intensity or the illumination color or the wavelength of the emitted light, the optical sorting system according to the invention can be adapted to the granulate particles to be sorted and their color or their optical properties.

According to a preferred embodiment, the lighting device can be arranged at a distance in the horizontal direction from the discharge line of the conveyor belt in the range of -40 to 40 mm, preferably in the range -40 to 15 mm, particularly preferably centrally above the detection line. The negative values correspond to a distance in front of the drop line in the transport direction, positive values correspond to a distance behind the drop line in the direction of flight.

Furthermore, it can be provided that an illumination background is arranged opposite in the direction of the light rays emitted by the lighting device relative to the free trajectory of the granulate particles. The illumination background makes it possible to photograph optical images of the granulate particles to be detected with a known and defined background, in particular a known background color or known background structure. This makes it possible to reliably detect color deviations or other artifacts in the particles to be detected. In particular, the arrangement of the lighting background when generating the optical images prevents the particle from capturing additional scattered light from the environment and thus optical artifacts from being reflected in the granule particle to be detected, which in turn could lead to optical misinterpretations.

Provision can also be made to actively illuminate the lighting background, with the lighting intensity as well as the lighting color or wavelength of the lighting background being actively controllable. Alternatively, the lighting background can also be designed as a passive background area, which is preferably adapted to the color of the granulate particles.

According to the invention, it is further provided that at least one separating blade is arranged behind the discharge end in the discharge direction of the granulate particles between the first free trajectory and the at least one second trajectory, wherein the separation sword can comprise an end face that tapers to a point relative to the discharge end in the form of a sharp knife edge . The provision of a separating blade between the first free trajectory and the second trajectory makes it possible to achieve precise separation of the granulate particles belonging to the first granule fraction and the second granule fraction. The provision of a tapered end face in the form of a knife edge ensures that granules hitting there are deformed (energy absorption) and thus granulate particles do not rebound too directly into the first free trajectory, which could disrupt the sorting process or lead to a particle jam in the area of the granule outlets or optical sorting.

The at least one separating blade is essentially designed as a partition and can comprise a flat or curved surface course in the plane of the discharge corridor, which preferably runs parallel to the first flight path, wherein the at least one partition is preferably arranged at a defined distance below the flight path.

Preferably, it can be provided that a longitudinal axis of the separating blade is relative to the tangent to the first idealized trajectory of the granulate particles Intersection point between the longitudinal axis of the separating blade of the first trajectory is arranged to enclose an angle in the range of 5 ° to 45 °.

Furthermore, it can be provided that the separating blade is arranged to be displaceable along its longitudinal axis in order to adapt to the trajectory of the granules.

In a particularly preferred embodiment, the end face of the separating blade can have a horizontal distance relative to the detection line in the range of 10 to 80 mm.

It can be provided that the metering device comprises at least a first and a second sieve deck, the granulate particles being passed over the sieve decks, with the granulate particles above a second average particle diameter being separated by means of the first sieve deck and the granulate particles below a first average particle diameter being separated through the second sieve deck are separated, in such a way that granulate particles with an average particle diameter between the first and second particle diameters are fed to the conveyor belt. The two sieve decks ensure that only granulate particles with an average particle diameter in a defined area between a first and second diameter are fed to the conveyor belt. This ensures that only granule particles in a defined size range reach the area of the sensor device in order to keep the resulting deviations in the trajectory of the granule particles within a defined framework and thus limit the flight corridor due to the scattering of the trajectory of the granule particles.

Preferably, it can be provided that the metering device further comprises at least one metering channel, via which the granules are applied after passing through the sieve decks and via which the granules are fed onto the conveyor belt. The dosing channel can be designed as a flat surface and is essentially horizontally aligned and also has a small distance, preferably in the vertical direction a distance that is smaller than the average particle diameter, relative to the conveyor belt surface. The metering device, which runs along a horizontal plane and has a small distance in the vertical direction from the conveyor belt or the conveyor belt surface, has the advantage that the granulate particles fed onto the conveyor belt via the metering device only have a low initial energy (potential energy and kinetic energy). , which makes it possible to quickly calm down the granulate particles on the conveyor belt.

Particularly preferably, the metering trough at a discharge end of the metering trough, at which the granulate particles are fed from the metering trough onto the conveyor belt, essentially has the width of the conveyor belt. Alternatively, however, it can also be provided to provide several metering channels across the width of the conveyor belt.

Furthermore, it can be provided that the metering device additionally comprises a vibration device, via which the sieve decks and/or the metering trough can be set in vibration.

The oscillation amplitude, the shape and orientation of the oscillation amplitude as well as the frequency of the oscillation amplitude of the vibration device can be flexibly adjusted.

Furthermore, it can be provided that two ionization devices arranged offset from one another are provided in the metering device, with the granulate particles to be fed onto the conveyor belt being passed through the two offset ionization devices before being fed onto the conveyor belt. The longitudinal axes of the ionization devices are essentially orthogonal to the longitudinal axis of the conveyor belt. Due to the ionization devices arranged offset from one another, any electrical charges that may still be present on the granulate particles can be removed from them in such a way that they are released from the metering device onto the conveyor belt essentially uncharged in order to avoid possible repulsion or attraction effects of the granulate particles due to existing electrical charges on the acceleration belt and to prevent free flight.

By means of the ionization device, the ambient air is locally ionized or electrically charged, such that electrical charges of the granulate particles can be derived from the granulate particles through the ionized air.

It can be provided that the discharge device is formed by a large number of individual nozzles, which are arranged above or below the free trajectory of the particles.

Particularly preferably, an air guide device or several air guide devices can be arranged in front of the individual nozzles of the discharge device, with the air flow ejected by the individual nozzles being redirected in a defined direction via the air guide device.

Furthermore, it can be provided that the air flow ejected from the individual nozzle and redirected via the air guide device has a horizontal speed of at least 1.5 m/s. The horizontal speed component is adapted to the conveyor belt speed or the current particle flight speed at the time of passing the discharge device.

Furthermore, it can be provided according to the invention that a compensating air duct extending from the second fraction outlet in the horizontal direction is arranged in the area of the at least one second fraction outlet, the compensating air duct being formed by a base plate and two opposite side plates is formed as a channel that is open at the top and the bottom plate is designed to fall in the direction of the second fraction outlet.

Particularly preferably, the base plate has an angle in the range of 0 to 25° relative to a horizontal.

Furthermore, it can be provided according to the invention that the at least one second fraction outlet comprises a lateral opening in a wall of the outlet, the opening being covered with an air-permeable filter device.

Furthermore, it can be provided according to the invention that the conveyor belt is formed from an electrostatically conductive belt material or that the conveyor belt comprises electrostatically conductive belt material.

The conveyor belt can have a deflection edge at the discharge end with a radius of the conveyor belt surface of less than 20 mm, in particular less than 10 mm.

Due to the small radii of the deflection edge of the conveyor belt in the area of the discharge end, the resulting flow effects in the area of the deflection edge can be kept low. This has the advantage that the thrown granulate particles are not or only slightly influenced in their trajectory due to the resulting flow conditions at the deflection edge in the area of the throwing end.

It can preferably be provided that the conveyor belt comprises a belt material in which reinforcing fibers, such as in particular carbon fibers, are embedded in the running direction of the conveyor belt. Furthermore, it can be provided that the conveyor belt is designed as a revolving endless belt, the conveyor belt comprising two belt ends which have a toothed weld seam are connected to one another and wherein the weld seam has an angle in the range of 35 to 55 °, particularly preferably an angle of 45 °, relative to the running direction of the conveyor belt. According to a preferred embodiment, it can be provided that the conveyor belt comprises a conveyor belt surface for transporting the particles, the conveyor belt surface having a low surface roughness, particularly preferably of 0.2 μm.

Furthermore, it can preferably be provided that the absolute numerical value of the length of the transport path of the granulate particles along the conveyor belt, measured in meters, corresponds to the absolute numerical value of the running speed of the conveyor belt, measured in m/s. Furthermore, it can particularly preferably be provided that the conveyor belt is driven at a running speed in the range of 1 m/s to 3 m/s, particularly preferably in the range of 1.5 m/s to 2.5 m/s.

The optical sorting system according to the invention is explained in more detail below with reference to the attached figures using exemplary embodiments.

Fig. 1

eine Seitenansicht eines Ausführungsbeispiels einer erfindungsgemäßen optischen Sortieranlage,

Fig. 2

eine Schnittansicht durch eine beispielhafte Ausführungsform einer erfindungsgemäßen Dosiereinrichtung 4 in Zusammenschau mit dem Aufgabeende 7a eines Transportbandes 7, sowie

Fig. 3

die Schnittansicht einer beispielhaften Ausführungsform einer erfindungsgemäßen optischen Sortieranlage im Bereich des Abwurfendes 7b des Transportbandes 7.

Show it:

Fig. 1

a side view of an embodiment of an optical sorting system according to the invention,

Fig. 2

a sectional view through an exemplary embodiment of a metering device 4 according to the invention in conjunction with the feed end 7a of a conveyor belt 7, and

Fig. 3

the sectional view of an exemplary embodiment of an optical sorting system according to the invention in the area of the discharge end 7b of the conveyor belt 7.

The Fig. 1 shows a schematic side sectional view of an exemplary embodiment of a sorting system according to the invention. The granulate particles 100 to be sorted are fed to the optical sorting system at an upper end of the optical sorting system via a material inlet 1 and are sorted into two granule fractions 1 by the exemplary optical sorting system shown. The first granule fraction is the so-called good fraction, whereby the granule particles 100 in the first granule fraction correspond to the set quality criteria and are removed from the optical sorting system via the first granule fraction outlet 21, whereas the granule particles 100, which do not correspond to the required quality criteria, are removed the second granulate fraction outlet 22 is removed from the optical sorting system. A countercurrent air classifier 2 is arranged downstream of the material inlet 1 for pre-sorting the granulate particles 100 before they are placed on the conveyor belt 7, via which possible dust particles can be separated from the granulate particles 100 to be sorted. Furthermore, an all-metal separator 3 is arranged downstream of the countercurrent air classifier 2, via which possible metal particles can be removed from the granulate particles 100 supplied. The metering device 4 is arranged downstream of the all-metal separator 3, via which, according to the invention, the granulate particles 100 are fed onto the conveyor belt 7. In the area of the discharge end 7b of the conveyor belt 7, an optical sensor device 9 as well as a lighting device 10 and a discharge device 12 are arranged. Furthermore, in the exemplary embodiment shown, a separating blade 11 was arranged in the area of the free flight path 201 of the granulate particles 100 to separate the first granule fraction outlet 21 and the second granule fraction outlet 22.

In the exemplary embodiment of the optical sorting system, as is also the exemplary embodiment of the optical sorting system Fig. 1 can be removed, is in the area of the second fraction outlet 22 one of the second Fraction outlet 22 is provided with a compensating air duct 221 extending essentially in the horizontal direction, the compensating air duct 221 being delimited laterally and downwards by a base plate 222 and two opposite side plates 223. The compensating air channel 221 is designed as a channel that is open at the top and from which air can escape. The compensating air channel 221 serves to reduce the volume and air speed of the air expelled by the discharge device 12 so that no dynamic pressure arises in the second fraction channel 22. The bottom plate 222 is designed to slope down in the direction of the second fraction outlet 22 or to rise as the distance from the second fraction outlet 22 increases. The base plate 222 has an angle β relative to an imaginary horizontal. In the embodiment according to Fig. 1 has, the second fraction outlet 22 has a side opening 220, which is provided in a wall of the outlet 22, the opening 220 being covered with an air-permeable filter device 224. By means of the air-permeable filter device 224, it is possible for the air flow emitted via the discharge device 12 to be discharged in the area of the second outlet 22 via the side opening 220. The air-permeable filter device 224 prevents granule particles 100 from being discharged in the area of the second granule fraction outlet via the side opening 220 and from being introduced into it, in particular when a compensating air duct 221 is arranged. The conveyor belt 7 runs in the upwardly open compensating air duct 221, with the side edges of the conveyor belt 7 running at a distance from the side plates 223. Through the gap between the side plates 223 and the conveyor belt 7, the air introduced into the equalizing air duct 221 is discharged laterally upwards on the conveyor belt. This embodiment has the advantage that air volumes introduced by the discharge device 12 can be removed, so that no back pressure arises. Bands can be arranged on the two side plates 223 via spacers (not shown), which laterally delimit the conveyor belt surface of the conveyor belt 7 and prevent the transported granulate particles 100 from being thrown off to the side.

The conveyor belt 7 can be designed as a revolving endless belt, with a conveyor belt surface 7s being provided for the transport of the granulate particles 100, which preferably has a low surface roughness.

The Fig. 2 shows a schematic view of an exemplary embodiment of a metering device 4 according to the invention and its arrangement in the area of the feed end 7a of a conveyor belt 7 of an optical sorting system according to the invention. In the Fig. 2 Dosing device 4 shown has an upper material feed 40, in which the granulate particles 100 are transferred to the dosing device. The metering device 4 shown has a first screen deck 41 and a second screen deck 42 arranged underneath, as well as a base plate 43 and a metering channel 45. The granulate particles 100 fed to the metering device via the material feed 40 first pass through the first screen deck 41, by means of the first screen deck 41 the granulate particles 100 are separated above a second average particle diameter and the particles that are too large are removed from the optical sorting system via an ejection 41a in such a way that they are no longer fed to the conveyor belt 7. The granulate particles 100, which have an average diameter below the second average particle diameter, fall through the openings of the first sieve deck 41 onto the second sieve deck 42 underneath, the granulate particles 100 being separated below a first average particle diameter by means of the second sieve deck 42 and via an ejection 43a in the base plate 43 are removed from the metering device 4. As a result, the particles with a diameter that is too small and removed via the ejection 43a are also removed from the optical sorting system in such a way that they are no longer fed to the conveyor belt 7. In the interaction, the two sieve decks 41 and 42 ensure that only granulate particles 100 with an average particle diameter d in a range between a first lower diameter d1 and a second upper diameter d2 Conveyor belt 7 is fed. This ensures that only granulate particles 100 with a defined size range reach the area of the sensor device 9 in order to keep the resulting deviations in the first free trajectory 201 within a defined framework and thus limit the flight corridor due to the scattering of the trajectory of the granulate particles 100 . An uncontrolled collision and rebound of the granulate particles 100 on undesired devices or surfaces of the optical sorting device is thus reliably avoided. The metering device 4 shown also has two ionization devices 44 arranged oppositely offset, between which the granulate particles 100, which are discharged from the second sieve deck 42 onto the metering trough 45, are electrically discharged in such a way that only electrically uncharged granule particles 100 are released by means of the metering trough 45 the task end 7a of the conveyor belt 7 is abandoned. The metering channel 45 is designed as a flat surface, which runs essentially horizontally. The metering channel 45 is arranged at a small vertical distance a457 from the surface 7s of the conveyor belt 7. The vertical section a457 is preferably designed to be smaller than the average particle diameter d of the granulate particles 100. The metering device 4 shown is further connected to a vibration device 46 in such a way that vibrations generated by the vibration device 46 can be transmitted at least to the two sieve decks 41, 42 and/or the metering trough 45. As in Fig. 2 shown, the metering device 46 can also be arranged in such a way that all elements of the metering device are caused to vibrate. The vibrations generated by the vibration device 46 can be adjustable, in particular with regard to their vibration amplitude, the shape and orientation of the vibration amplitude as well as the frequency of the vibration amplitude of the vibration device 46.

The illustrated section of the conveyor belt 7 in the area of the feed end 7a illustrates the arrangement of the exemplary metering device 4 in the area of the feed end 7a of the conveyor belt 7. The conveyor belt 7 has via a belt material 72, which has a conveyor belt surface 7s for the transport of the granulate particles 100 and in the transport direction 70 the fed granulate particles to an in Fig. 2 discharge end 7b of the conveyor belt 7, not shown, is transported. The granulate particles 100 are applied to the conveyor belt 7 via the metering device 4 and in particular via the metering channel 45 to the conveyor belt 7 at a first end of the conveyor belt 7a, the so-called feed end of the conveyor belt 7, which is opposite the discharge end 7b. A defined amount of granulate particles 100 per unit of time are fed onto the conveyor belt 7 via the metering channel 45 by means of the metering device 4. The amount of granulate particles 100 per unit of time applied via the metering device 4 is controlled in such a way that a monolayer of the granulate particles 100 is applied to the conveyor belt 7. A monolayer is understood to mean a distribution of the granulate particles 100 on the conveyor belt 7 in which there are no overlaps between the granulate particles 100 on the conveyor belt 7. The granulate particles 100 therefore do not lie one above the other on the conveyor belt 7, but are preferably spaced next to one another or touch one another and are essentially distributed over the entire conveyor belt width.

The Fig. 3 shows a section of an exemplary optical sorting system in the area of the discharge end 7b of the conveyor belt 7. In the illustrated embodiment according to Fig. 3 A lighting device 10 and a sensor device 9 are arranged in the area of the discharge end 7b above the first free flight path 201 of the granulate particles 100. A discharge device 12 is arranged along the direction of flight of the granulate particles 100 on the free flight path 201 following the lighting device 10. The optical sensor device 9 is arranged in such a way that it generates the optical images of the granulate particles 100 thrown off the conveyor belt 7 at the discharge line 71 and transmits them to the control device 13. The control device 13 is designed in such a way that it is based on the optical recordings of the sensor device 9 and the evaluation of at least one detection criterion assigns the thrown granulate particles 100 to the at least one first or second granule fraction and transmits a control pulse to the discharge device 12 when a granule particle 100 is assigned to the second granule fraction. When a control pulse is present, the discharge device 12 pushes an air stream 120 via an air nozzle 121, whereby the granule particle 100, which was assigned to the second granule fraction, is deflected from the first free trajectory 201 onto a second trajectory 202. The air flow 120 of the individual nozzle 121 is directed in a specific direction by means of at least one deflection device 122, such as a deflection plate. The first granule fraction outlet 21 is arranged in the area of the free trajectory 201 of the granule particles 100 at a defined distance from the discharge end 7b and when a control pulse is transmitted, the discharge device 12 moves the granule particles 100 assigned to the at least one second granule fraction into at least a second trajectory before reaching the first granule fraction outlet 202 transferred and discharged into at least one second granule fraction outlet 22. The optical sensor device 9 generates recordings of the thrown granulate particles 100 in the area of their free trajectory 201. The course of an exemplary free trajectory 201 is in the Fig. 3 represented by a dash-dotted line. The recordings generated by the sensor device 9 are generated at a first horizontal distance h719 relative to the discharge line 71 of the conveyor belt 7, at which the granulate particles 100 are thrown off the conveyor belt 7. Like in the Fig. 3 is shown as an example, the lighting device 10 is arranged above the free trajectory 201 of the granulate particles 100, which can alternatively also be arranged below the free trajectory 201. The exemplary lighting device 10 shown has several light sources, in particular a light-emitting diode. In particular, it can be provided that the lighting intensity and the lighting spectrum of the lighting device are actively controlled and adapted to the granulate particles 100 to be sorted. As in Fig. 3 shown is the lighting device 10 in the direction of the lighting device 10 An illumination background 14 is arranged opposite the emitted light rays relative to the free trajectory 201 of the particles 100. It can also be provided to actively illuminate the lighting background 14, whereby the lighting intensity and lighting color can also be actively changed. As also in Fig. 3 is shown, the first fraction outlet 21 and the second fraction outlet 22 are separated from each other in their upper area by a separating sword 11. The separating sword 11 is arranged behind the discharge end 7b in the discharge direction of the granulate particles 100 between the first free trajectory 201 and the at least one second trajectory 202, the separating sword 11 having a tapering end face 111 in the form of a knife edge that is directed relative to the discharge end 7b includes. It can be provided that the longitudinal axis 112 of the separating blade 11 is arranged relative to the tangent 201t to the first idealized trajectory 201 of the granulate particles at the intersection x between the longitudinal axis 112 of the separating blade 11 and the first trajectory 201 in such a way that the longitudinal axis 112 is one Angle α in the range of 40-60° or preferably 45°. The separating sword 11 can be designed to be linearly displaceable along its longitudinal axis 112, as shown by double arrow 113 in the Fig. 3 shown.

Claims (19)

1. Optical sorter system for sorting granulate particles (100) into at least a first and second granulate fraction (101, 102), comprising:

   - a dosage device (4);

   - a conveyor belt (7);

   - an optical sensor device (9);

   - a discharge device (12);

   - a control device (13); as well as

   - at least one first and second granulate fraction outlet (21, 22),

   - wherein the granulate particles (100) are fed onto the conveyer belt (7) in a monolayer via the dosage device (4), accelerated to a defined velocity by means of the conveyor belt (7), discharged from the conveyor belt (7) at a discharge end (7b) and transferred to a first free trajectory (201);

   - wherein the optical sensor device (9) generates optical images of the discharged granulate particles (100) and transmits the same to the control device (13);

   - wherein, by evaluating at least one detection criterion, the control device (13) assigns the discharged granulate particles (100) to the at least one first or second granulate fraction (101, 102) based on the optical images, and transmits a control pulse to the discharge device (12) when a granulate particle (100) is assigned to the second granulate fraction (102);

   - wherein the first granulate fraction outlet (21) is arranged in the area of the free trajectory (200) of the granulate particles (100) at a defined distance from the discharge end (7b);

   - wherein, when a control pulse is transmitted, the discharge device (12) transfers the granulate particle (100) assigned to the at least one second granulate fraction (102) to at least a second free trajectory (202) before it reaches the first granulate fraction outlet (21) and discharges it into at least one second granulate fraction outlet (22),

   - characterized in that

   - downstream of the discharge end (7b), seen in the discharging direction of the granulate particles (100), at least one separating blade (11) is arranged between the one first free trajectory (201) and the at least one second free trajectory (202), the separation blade (11) having an end face (111) in the form of a knife edge pointed relative to the discharge end (7b).
2. Sorter system of claim 1, characterized in that the optical sensor device (9) generates images of the granulate particles (100) in the area of the free trajectory (201), wherein the images are generated at a horizontal distance (h719) relative to a discharge line (71) of the conveyor belt (7), at which the granulate particles (100) are discharged, in a range from 5 mm to 40 mm, preferably in a range from 5 mm to 15 mm.
3. Sorter system of claim 1 or 2, characterized in that the sensor device (9) includes a central line of sight (91), wherein the line of sight (91) forms an angle with the tangent (201t) of the free trajectory (201) at the intersection (X) of the line of sight (91) with the free trajectory (201) in a range from 75° to 115°, preferably in a range from 85° to 95°.
4. Sorter system of one of the preceding claims, characterized in that the discharge device (12) is arranged in the area of the free trajectory (201) of the granulate particles (100) at a horizontal distance (h719) relative to a discharge line (71) of the conveyor belt (7), at which the granulate particles (100) are discharged, in a distance range from 2 cm to 9 cm, preferably in a distance range from 2 cm to 5 cm.
5. Sorter system of one of the preceding claims, characterized in that an illumination device (10) is arranged in the area of the discharge end (7b) above and/or below the free trajectory (201) of the granulate particles (100) to illuminate the granulate particles (100).
6. Sorter system of claim 5, characterized in that the illumination device (10) is arranged at a distance (h719) in the horizontal direction relative to the discharge line (71) of the conveyor belt (7) in a range from 5 mm to 40 mm, preferably in a range from 5 mm to 15 mm.
7. Sorter system of claim 5 or 6, characterized in that seen in the direction of the light beams (10l) emitted by the illumination device (10), an illumination background (14) is arranged opposite the free trajectory (201) of the particles (100).
8. Sorter system of one of the preceding claims, characterized in that a longitudinal axis (112) of the separating blade (11) is arranged relative to the tangent (201t) to the first idealized trajectory (201) of the granulate particles (100) in the intersection (X) of the longitudinal axis (112) of the separation blade (11) and the first trajectory (201), such that it encloses an angle (α) in a range from 40° to 50°, preferably 45°.
9. Sorter system of claim 8, characterized in that the separating blade (11) is arranged to be slidable along its longitudinal axis (112).
10. Sorter system of claim 8 or 9, characterized in that the end face (111) of the separating blade (11) has a horizontal distance in a range from 10 mm to 50 mm.
11. Sorter system of one of the preceding claims, characterized in that the dosing device (4) comprises at least a first and a second screen deck (41, 42), wherein the granulate particles (100) are passed over the screen decks (41, 42), wherein by means of the first screen deck (41), granulate particles (100) above a second mean particle diameter (62) are separated, and the granulate particles (100) below o first mean particle diameter (d1) are separated by means of the second screen deck (42), such that only granulate particles (100) of a mean particle diameter (d) between the first and the second particle diameter are fed to the conveyor belt (7).
12. Sorter system of one of the preceding claims, characterized in that in the area of the at least one second fraction outlet (22), an equalization air channel (221) is arranged branching from the second fraction outlet (22) in the horizontal direction, wherein the equalization air channel (221) is formed as a channel open to the top by a sheet metal base plate (222) and two opposing sheet metal side plates (223), and wherein the sheet metal base plate (222) is inclined towards the second fraction outlet (22).
13. Sorter system of claim 12, characterized in that the sheet metal base plate (222) includes an angle (β) in a range from 0° to 25° with a horizontal.
14. Sorter system of one of the preceding claims, characterized in that the at least one second fraction outlet (22) has a lateral opening (220) in a wall of the outlet (22), wherein the opening (220) is covered by an air-permeable filter device (224).
15. Sorter system of one of the preceding claims, characterized in that the conveyor belt (7) comprises an electrostatically conductive belt material (72).
16. Sorter system of one of the preceding claims, characterized in that at the discharge end (7b), the conveyor belt (7) has a deflection edge (73) with a radius of the conveyor belt surface (7s) of less than 20 mm, in particular 10 mm.
17. Sorter system of one of the preceding claims, characterized in that the conveyor belt (7) comprises a belt material (72) in which reinforcing fibers, in particular carbon fibers, are embedded in the travelling direction (70) of the conveyor belt (7).
18. Sorter system of one of the preceding claims, characterized in that the conveyor belt (7) is designed as a circulating endless belt, wherein the conveyor belt (7) has two belt ends connected to each other by an interlocked weld seam, and wherein the angle of the weld seam relative to the traveling direction (70) of the conveyor belt (7) is in a range from 35° to 55°, preferably an angle of 45°.
19. Sorter system of one of the preceding claims, characterized in that the conveyor belt (7) comprises a conveyor belt surface (7s) for conveying the particles (100), wherein the conveyor belt surface (7s) has a low surface roughness.

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