DE19752686B4 - Method and device for detecting stones in a conveyed stream - Google Patents

Abstract

method for detecting stones in the flow of conveyed material a continuous conveyor and for determining their three-dimensional size by means of a radiometric measurement system where a higher Density in the volume of transported goods across from the bulk material (5) by the reduction associated with the penetration of the conveyed material the radiation is recognized as a stone (6) in its height-wise extent, being its width through the over the entire width of the webbing (3) distributed radiation receiver determined is a reduced by the stone (6) received signal of the identify emitted radiation and its length recognized by the time period that gets through by the stone body at the known conveying speed caused reduction of the radiation intensity occurs, characterized in that by the radiometric measuring system every millisecond the density of the belt conveyor located on the belt conveyor Bulk material over the entire width of the conveyor belt (3) measured and this density as the basic density in the computer by the Evaluation software is detected and registered and the cross section with the higher laden middle area of the ...

Description

The The invention relates to a method and device for detecting Stones in the flow of conveyed material a continuous conveyor and for determining their three-dimensional size by means of a radiometric Measuring system according to the preamble of the first claim for the method with a device according to the preamble of the fourth claim, which together with an evaluation unit and a Aushalteinrichtung at a mining device allow an automatic endurance of stones by the receiving organ when removing stone-infiltrated soils into the material flow have arrived and the disturbances in the flow of goods or damage the conveyor system to lead can.

In order to avoid damage to the opencast mining equipment and the subsequently arranged belt systems and belt traversing equipment, stones are removed from a certain size from the Fördergutstrom; they are endured. This takes place in such a way that the stone which has reached the conveyed material stream is recognized at the earliest possible time and is then preferably endured at a point where the conveyed product stream moves in free fall by a grate which is temporarily pivoted into the conveyed material stream. Such a Steinaushalteeinrichtung is for example from the patent to DE 197 52 596 C1 known. Steiner is a suitable system that, together with an evaluation method, enables the stones to be identified in terms of size for the reliable detection of a conveyed material stream consisting of bulk material.

Such a device for the automatic detection of stones in a Fördergutstrom is according to the patent DE 195 27 935 C1 known for a bucket wheel excavator. After a stone has been picked up by the paddle wheel, it is guided together with the other conveyed material on the discharge chute on the Schaufelradband. Based on the fact that a stone generates different vibrations than bulk material when it hits the transfer chute, acceleration sensors are installed at regular intervals below the chute in the impact area and constantly measure the vibrations generated by the conveyed material. In a detection, evaluation and control unit, these vibrations are evaluated according to their characteristics and if this coincides with that of a stone, a Steinaushalteeinrichtung is pivoted into the Fördergutstrom that endures the stone thus determined. Problems can arise in this solution when there is so much bulk material on the discharge chute that the impact of the stone is strongly attenuated and thus the characteristic of the stone impact vibrations are distorted. In addition, there are distortions by Fördergutbrocken or by frost floes. Furthermore, according to the patent DE 42 30 626 C2 a method and a device for volume flow measurement of the bulk material on belt conveyors known by ultrasound. The contour of the free surface of the bulk material is continuously measured by non-contact distance measurement by means of ultrasonic sensors and calculated the delivery volume according to the pulse transit time measuring principle. In order to obtain reliable information about the weight of the conveyed material, a radiation measuring device is installed below the continuous conveyor, which measures the density of the conveyed material on the basis of the different radiation intensity. It is always assumed that a uniform density of the bulk material cross-section.

From the patent DE 197 19 032 C1 Furthermore, a method for detecting stones in the flow of a conveyor and for determining their three-dimensional size by means of a radiometric measuring system is known. In the method, the change in the radiation intensity of a radiation source is used when penetrating a conveyed material and determined in dependence on the continuously adapted to the bulk material bulk density, the length, width and height of a foreign storage, especially of stones in Nutzmineralstrom. If a stone with a certain edge length occurs, it is determined via an evaluation unit, if the stone has an edge length below a certain size and thus can remain in the flow or if it is above a certain size and must be sustained.

Of the Invention is based on the object, the method for detecting of bodies different density so evolve that with one for stones sufficient radiation source the different radiation intensity, which when illuminated a bulk material flow is measured for the detection of stones in a bulk flow and for the determination their three-dimensional extent to use.

The solution is to use the law that, as the thickness of the stones increases, the difference between the rays emitted on one side and the rays received on the opposite side increases proportionally. Based on the different bulk properties, which have a different radiation attenuation result, should the tat account for material values in the measurement result.

The The object is achieved by a method having the features of the first claim solved by a device having the features of the fourth claim.

The Method for the automatic detection of stones in a conveyed stream based on a density measurement of the components of the conveyed material. Due to the different density of Fördergutbestandteile bulk material and Stones will be the density of the main bulk material as Basic density considered and rated. Their difference to the stone density is the measure for the Steinerkennung. The more precisely this difference can be determined, the higher it is the probability of finding the stones. As the properties of the bulk material the change the soil components and by external influences such as Moisture increase or decrease, which may have influences on the density, can change with a redefinition of the base density the difference to the density the stones are redetermined.

at the procedure becomes the higher Density in the volume of transported goods across from through the bulk material with the penetration of the conveyed material accompanying reduction of radiation as a stone in its elevation recognized. The width of a stone is through the over determined the entire width of the webbing distributed radiation receiver, the one reduced by the stone received signal of the sent Identify radiation. The length of a stone is recognized by the length of time that passes through the stone body at the known conveying speed caused reduction of the radiation intensity occurs.

to execution In this method, the calculator is programmed to measure the bulk density determine yourself and by specifying a safety value automatic a limit for defines the distinction of a stone from the bulk material. Changes detects the density of the bulk material this the calculator and he puts a new, this changed Conditions adapted limit. This system can therefore be referred to as a self-learning system. Through this automatic adjustment changing conditions a high probability of stone detection is possible. With the use of a second radiation source, a laser radiation source, for the Finding possible changes the surface by measuring the distance from the laser radiation source becomes the bulk material surface the computer enabled, with the aid of the measured value for the Density between stones and bulk material and shingles to distinguish. These two sources of radiation must therefore be different so that they do not affect each other and so falsifies the measurement results would.

For the density measurement of the bulk material and the stones including The determination of their three-dimensional extent required a radiation source found, on the one hand strong enough to penetrate the stones, on the other hand, they are not harmful Actions on persons working in the field of such a facility exercises. The was with the low radiation intensity, the bundling of the rays and a Arrangement on the conveyor in one area allows in the immediate vicinity in the extended one Radiation direction no people stop.

The permanent Querying and evaluating the measured values every millisecond leads to accurate measurement results.

Further details and advantages of the subject invention are explained with reference to the following description, in which he is shown as a preferred embodiment, a radiometric Messsytem for the automatic Steinaushaltung a bucket wheel excavator. The accompanying drawing shows the basic structure of the device for stone detection and their arrangement in the framework 1 of the Schaufelradauslegers of a bucket wheel excavator shown in a section.

In the framework 1 of the bucket wheel boom is the carrying roller garland 2 with the upper run of the conveyor belt 3 , Below are the carrying roles 4 arranged for the lower strand. On the conveyor belt 3 is the picked up by the paddle wheel and transferred to this continuous conveyor bulk material 5 , Furthermore, on the conveyor belt 3 Einstein 6 represented, which has such a size, which could lead to increased wear or even damage and destruction of the subsequent conveyor complex in a further transport and therefore by the Steinaushalteeinrichtung, such as from the patent application after file reference P 197 52 596.2 known in the transfer of conveyor belt 3 the boom to be sustained on the subsequent intermediate belt from the Fördergutstrom.

The radiometric measuring system for stone detection consists of a radioactive radiation source 7 Cobald-60th To detect the density of the conveyed material components bulk material 5 and stones 6 sufficient low radiation intensity. This low radiation intensity and the bundling of the beams to a narrow range cause neither the lateral inspections of the wheel boom nor the timetable of the bucket wheel excavator time restrictions on the residence of persons are imposed or even additional protective measures become necessary. Under the upper run of the conveyor belt 3 are evenly spaced across the width of the conveyor belt 3 distributes eight radiation receivers 8th , so-called detectors arranged on the radiation source 7 are aligned for density measurement of the bulk material.

Parallel to the radioactive radiation source 7 for the density measurement is still a second measuring device, a laser scanner 9 for measuring the conveyed goods height in the region of the first radiation source 7 arranged on the drawing behind this.

The two measuring devices 7 and 9 as well as the radiation receivers 8th are connected to an electronic computer, which is programmed by a corresponding evaluation software so that it can perform the process steps described below, taking into account the belt speed and the distance still to be taken to the Aushalteeinrichtung.

• • Der Hauptbestandteil des Fördergutes ist das Schüttgut 5, dagegen kommen Steine 6 nur vereinzelt vor.
• • Die Steine 6 können entweder teilweise oder vollständig vom Schüttgut 5 eingeschlossen sein, sie können aber auch auf den Schüttgut 5 liegen.
• • Schüttgut 5 hat eine geringere Dichte als Steine 6.
• • Förderguthöhe und die Dämpfung der das Fördergut durchdringenden Strahlen verhalten sich zueinander proportional.
• • Die Schüttguthöhe ist bei einem gemuldeten Förderband 3, bezogen auf den Querschnitt, unterschiedlich.
• • Das Schüttgut 5 kann im Fördergutstrom gleichmäßig verteilt sein, es kann aber auch in Form von Klumpen oder Schollen auftreten.
• • Der für die Schüttgutdichte gemessene Wert kann sich durch die Veränderungen der Zusammensetzung des Schüttgutes 5 und/oder durch die Veränderung des Feuchtigkeitsgehaltes verändern.
• • Steine 6, deren Größe sich innerhalb eines durch einen oberen und einen unteren Grenzwert gekennzeichneten Bereiches befindet, sollen automatisch ausgehalten, kleinere Steine 6 können weiterbefördert und größere Steine 6 sollen aus dem kürzesten Weg aus dem Fördergutstrom entfernt werden.

For the method for automatic detection of stones 6 In a conveyed stream, the following basic considerations are assumed:

• • The main component of the conveyed material is the bulk material 5 , on the other hand, there are stones 6 only occasionally before.
• • The stones 6 can be either partial or complete of the bulk material 5 but they can also be trapped on the bulk material 5 lie.
• • bulk material 5 has a lower density than stones 6 ,
• • Product height and the damping of the radiation penetrating the conveyed material are proportional to each other.
• • The bulk goods height is with a troughed conveyor belt 3 , based on the cross section, different.
• • The bulk material 5 can be evenly distributed in the Fördergutstrom, but it can also occur in the form of lumps or clods.
• • The value measured for the bulk density may be due to changes in the composition of the bulk material 5 and / or by changing the moisture content.
• • stones 6 , whose size is within a range marked by an upper and a lower limit, should automatically endure smaller stones 6 can carry on and larger stones 6 should be removed from the shortest route from the Fördergutstrom.

• • Durch die radiometrische Strahlungsquelle 7 wird im Millisekundentakt die Dichte des Fördergutes gemessen. Ausgehend davon, dass sich im Normalfall überwiegend Schüttgut 5 auf dem Förderband 3 befindet, erhält der Rechner immer den gleichen bzw. nahezu die gleichen Werte. Da die Schwächung der Strahlen an den Seiten infolge der abnehmenden Schüttguthöhe höher als im mittleren Bereich der Mulde ist, nehmen die Messwerte nach außen hin zu. So werden die unterschiedlichen Böden hinsichtlich ihrer Dichte als Schüttgut 5 erkannt und als solches durch die Auswertesoftware erfasst und im weiteren Verfahren als Grunddichte berücksichtigt. Dabei werden auch die Seitenbereiche mit nach außen abnehmender Schüttguthöhe mit ihren tatsächlichen Messwerten berücksichtigt und erfasst. Als solche Böden unterschiedlicher Dichte können beispielsweise Sand, Kies, Schluff oder Ton auftreten. Ändern sich die Eigenschaften des Schüttgutes 5 und damit seine Dichte, wird dies vom Rechner mit Hilfe der Auswertesoftware erkannt und die Grenze der Dichte zwischen dem Schüttgut 5 und den Steinen 6 wird neu festgelegt. Damit kann das System auf veränderte äußere Bedingungen reagieren und der Grenzwert zwischen der Dichte zwischen dem Schüttgut 5 und den Steinen 6 wird immer nur so hoch wie nötig festgesetzt, wodurch sich die Erkennungsgenauigkeit für die Steine 6 erhöht.
• • Des weiteren kann es bei mit Wasser gesättigten Böden zur Schollenbildung kommen, wodurch nicht mehr von einer gleichmäßigen Schüttung ausgegangen werden kann. Damit das System ein solches Vorkommen infolge der dadurch verursachten größeren Strahlungsdämpfung nicht als Stein 6 bewertet, wird wie auch bei bindigen Böden durch die parallel zur Strahlungsquelle 7 eingesetzten Laserscanner 9 zur Messung der Förderguthöhe vorgesehen. In diesen Fällen, in denen die Schollenbildung auftritt bzw. in denen sich Klumpen bilden, wird die jeweilige Förderguthöhe mit der Fördergutdichte ins Verhältnis gesetzt und so erkannt, ob das Fördergut eine gleichbleibende bzw. nahezu gleichbleibende Dichte aufweist und damit als Schüttgut 5 erkannt und bewertet wird oder ob sich die Dichte deutlich erhöht und so als Stein 6 erkannt wird.
• • Taucht ein Stein 6 im Fördergutstrom auf, was im Rechner als Gegenstand mit einer erhöhten Dichte erkannt wird, erfolgt seine Größenbestimmung durch eine Ermittlung seiner Kantenlängen. Seine Breite wird durch die Anzahl der nebeneinander angeordneten Strahlungsempfänger 8 ermittelt, die ein Signal höherer Dichte empfangen und seine Länge durch die Zeitdauer des Empfangs eines solchen Signals in Abhängigkeit von der bekannten Bandgeschwindigkeit.
• • Die Steine 6 in verschiedenen Größenbereichen können bei Bedarf automatisch gezählt werden.
• • Bei Steinen 6 einer Kantenlänge in einem bestimmten, durch einen Maximalwert und einem Minimalwert begrenzten Bereich werden ausgesondert. Dazu wird eine Aushalteeinrichtung in Abhängigkeit vom noch zurückzulegenden Förderweg zeitverzögert in Funktion gebracht. Wird Größe der Steine 6 gegenüber der mit dem Aushaltebereich gekennzeichneten Größe der Steine 6 unterschritten, verbleiben diese Steine 6 auf dem Förderer und sie werden weiter befördert. Überschreitet hingegen die Größe der Steine 6 das mit der oberen Begrenzung des Aushaltebereiches vorgegebene Maß, wird der Antrieb des Auslegerbandes 3 stillgesetzt und der Baggerführer schwenkt den Ausleger in einen Bereich, von wo aus er nach einer Umkehr der Förderrichtung des Auslegerbandes 3 den Stein 6 über dessen äußeres Ende abgeworten wird.

The process for the automatic detection of stones in a conveyed stream proceeds in the following steps:

• • Through the radiometric radiation source 7 is measured in milliseconds the density of the transported material. Based on the fact that normally bulk material 5 on the conveyor belt 3 the computer always receives the same or almost the same values. Since the weakening of the rays on the sides is higher than in the middle region of the trough due to the decreasing bulk material height, the measured values increase towards the outside. Thus, the different soils in terms of their density as bulk material 5 detected and detected as such by the evaluation software and taken into account in the further process as the base density. At the same time, the side areas with outwardly decreasing bulk material height with their actual measured values are taken into account and recorded. As such soils of different density, for example, sand, gravel, silt or clay can occur. Change the properties of the bulk material 5 and thus its density, this is detected by the computer using the evaluation software and the limit of the density between the bulk material 5 and the stones 6 will be redefined. This allows the system to react to changing external conditions and the limit between the density between the bulk material 5 and the stones 6 is always set only as high as necessary, resulting in the recognition accuracy of the stones 6 elevated.
• • In addition, it can lead to floe formation in soils saturated with water, whereby it can no longer be assumed that there is a uniform bed. So that the system does not consider such occurrence as a stone due to the greater radiation attenuation caused thereby 6 is evaluated, as well as in cohesive soils by the parallel to the radiation source 7 used laser scanner 9 provided for measuring the Förderguthöhe. In these cases, in which the floe formation occurs or in which form lumps, the respective Förderguthöhe is set with the Fördergutdichte ratio and thus recognized whether the conveyed material has a constant or nearly constant density and thus as bulk material 5 is recognized and evaluated or whether the density increases significantly and thus as a stone 6 is recognized.
• • Dive a stone 6 in the conveyed stream on, which is recognized in the computer as an object with an increased density, its sizing is determined by determining its edge lengths. Its width is determined by the number of adjacent radiation receivers 8th which receives a signal of higher density and its length by the duration of the reception of such a signal in dependence on the known tape speed.
• • The stones 6 in different size ranges can be counted automatically if necessary.
• • For stones 6 of an edge length in a certain range limited by a maximum value and a minimum value are discarded. For this purpose, a holding device is brought into function in a time-delayed manner as a function of the conveying path still to be covered. Will size of the stones 6 opposite the size of the stones marked with the staging area 6 fallen below, these stones remain 6 on the conveyor and they are carried on. Exceeds the size of the stones 6 the predetermined with the upper limit of the Aushaltebereiches measure, the drive of the boom band 3 stopped and the excavator operator pivots the boom in an area from where he after a reversal of the conveying direction of the boom belt 3 the stone 6 is waived over its outer end.

The advantage offered by this method of stone detection is that it is a self-learning system. The main component of the material to be conveyed, the bulk material, is determined in terms of its density as a function of the height on the boom belt 3 measured and evaluated by the measuring system in cooperation with the evaluation software. This allows narrower limits to the auszustenden stones 6 be pulled, whereby a higher detection accuracy is achieved.

Claims (4)

Method for detecting stones in the flow of conveyed material of a continuous conveyor and for determining its three-dimensional size by means of a radiometric measuring system, in which a higher density in the conveyed material volume relative to the bulk material ( 5 ) by the reduction of the radiation as a stone associated with the penetration of the conveyed material ( 6 ) is recognized in its height-wise extent, wherein its width by the over the entire width of the webbing ( 3 ) distributed radiation receiver is detected, the one through the stone ( 6 ) detected reduced radiation signal of the emitted radiation and its length is detected by the period of time, which occurs by the stone body at the known conveying speed reduction of the radiation intensity, characterized in that by the radiometric measuring system in the millisecond constantly the density of the bulk material located on the belt conveyor over the entire width of the conveyor belt ( 3 ) and this density is detected and registered as a basic density in the computer by the evaluation software and the cross section with the higher loaded middle area of the conveyor belt ( 3 ) and in their height in the edge regions of the bulk material cross section to the outside decreasing mass of bulk material by a continuously decreasing difference of the radiometric radiation source ( 7 ) emitted radiation in relation to those of the radiation receivers ( 8th ) is measured and with the value thus determined for the basic density of the bulk material ( 5 ) a limit increased by a safety amount is formed which is below the value of the density of a stone to be sustained ( 6 ), and when a change in the density of the bulk material, this value is constantly corrected and if this upper limit of the density of the bulk material ( 5 ) is exceeded, this as a stone ( 6 ) and the size of the stone ( 6 ) is measured in terms of its three-dimensional extent, its width being determined by the number of juxtaposed receivers ( 8th ), which receive a signal of higher density and whose length is determined by the time duration of the reception of such a signal in dependence on the known belt speed and if the detected stone ( 6 ) has an edge length, which is in a range between a lower and an upper limit value, a signal for endurance of the stone is given, which lies below the lower limit value, the stone ( 6 ) remains in the product flow and • is greater than the upper limit, a signal to stop the conveyor given and this stone ( 6 ) by a change in the conveying direction of the conveyor belt ( 3 ) is returned from the conveyor belt. Method according to claim 1, characterized in that that the basic density of the different conveyed as a threshold change through the excavator operator manually or through another special device software, in which the soil types for others evaluation operations on the device are already predetermined and so on different soil types optimal mining and extraction conditions reached, switched on the computer belonging to the device becomes. A method according to claim 1, characterized in that by an additional laser scanner ( 9 ) by a distance measurement between laser scanners ( 9 ) and the surface of the bulk material in addition the bulk material height is measured, whereby the height of the material to be conveyed is set in relation to the measured density by the evaluation software and if the upper limit value of the determined density is exceeded this is recognized as a stone and its size is then determined. Device for detecting stones in a conveyed stream for the application of the method according to claims 1 and 3, characterized in that a radiometric measuring system with a radioactive radiation source ( 7 ) known radiation intensity from the top of the bulk material ( 5 ) is directed and bundled, and below the conveyor belt ( 3 ) over its width at regular intervals receiver ( 8th ) are arranged, and that in the effective range of the radiometric measuring system parallel to a laser measuring device ( 6 ) is arranged for measuring the Förderguthöhe and the radiometric measuring system and the laser measuring device ( 9 ) is connected to an electronic evaluation unit and this evaluation unit with a control unit for a Steinaushaltevorrichtung in combination.