DE102011051592B4 - Device for monitoring a conveyor system for detecting longitudinal slots in a conveyor belt by means of a slot protection system - Google Patents

Abstract

Device for continuous and non-destructive monitoring of a conveyor system (1) with the following components:
- an endless closed conveyor belt (2) with a supporting-side cover plate (3) and a running-side cover plate (4), each made of a polymeric material with elastic properties and with an embedded tension member;
- drums (5), support rollers (6) and support frames, whereby the aforementioned components in conjunction with the conveyor belt (2) form a material-conveying upper run (A) with a feed point (7) for the conveying material (8) and a mostly material-free lower run (B); and
- a slot protection system for detecting longitudinal slots in the conveyor belt (2), which is provided with at least one sensor (9) which detects the surface of the support-side cover plate (3) within a material-free area and/or the surface of the running-side cover plate (4) of the passing conveyor belt (2) without contact, a process computer taking over the evaluation of the data acquisition;
characterized in that
- the supporting-side cover plate (3) and/or the running-side cover plate (4) of the conveyor belt (2) is/are provided with at least one electrically conductive polymer layer (10) which extends as a strip in the transverse direction of the conveyor belt; and that
- the sensor (9) is an electrically conductive measuring probe to which an electrical alternating signal is applied, the voltage being selected such that a measurable signal is produced due to the dielectric displacement current, wherein in the event of longitudinal slitting of the conveyor belt (2) with destruction of the electrically conductive polymer layer (10) the previously existing signal is eliminated due to the higher resistance, associated with a warning or automatic stoppage of the conveyor system (1).

Description

• - einem endlos geschlossenen Fördergurt mit einer tragseitigen und laufseitigen Deckplatte aus jeweils einem polymeren Werkstoff mit elastischen Eigenschaften sowie mit einem eingebetteten Zugträger;
• - Trommeln, Tragrollen und Traggerüste, wobei die vorgenannten Bauteile in Verbindung mit dem Fördergurt ein materialförderndes Obertrum mit einer Aufgabestelle für das Fördermaterial und ein zumeist materialfreies Untertrum bilden; sowie
• - einem Schlitzschutzsystem zur Erfassung von Längsschlitzen des Fördergurtes, das mit wenigstens einem Sensor versehen ist, der berührungslos die Oberfläche der tragseitigen Deckplatte innerhalb eines materialfreien Bereiches und/oder die Oberfläche der laufseitigen Deckplatte des vorbeilaufenden Fördergurtes erfasst, wobei ein Prozessrechner die Auswertung der Datenerfassung übernimmt.

The invention relates to a device for the continuous and non-destructive monitoring of a conveyor system with the following components:

• - an endless closed conveyor belt with a supporting side and a running side cover plate each made of a polymer material with elastic properties and with an embedded tension member;
• - drums, support rollers and support frames, whereby the aforementioned components in conjunction with the conveyor belt form a material-conveying upper run with a feed point for the conveyed material and a mostly material-free lower run; and
• - a slot protection system for detecting longitudinal slots in the conveyor belt, which is provided with at least one sensor which detects the surface of the supporting-side cover plate within a material-free area and/or the surface of the running-side cover plate of the passing conveyor belt without contact, with a process computer taking over the evaluation of the data acquisition.

Regarding the construction of a conveyor belt, particular reference is made to the following patent literature: DE 25 20 943 A1 DE 38 01 120 A1 DE 25 32 190 A1 DE 43 33 839 A1 DE 44 36 042 A1 EP 0 753 471 A1 EP 0 336 385 A1 WO 2008/034483 A1

• Naturkautschuk (NR)
• Butadien-Kautschuk (BR)
• Chloropren-Kautschuk (CR)
• Styrol-Butadien-Kautschuk (SBR)
• Nitrilkautschuk (NBR)
• Butylkautschuk (IIR)
• Ethylen-Propylen-Kautschuk (EPM)
• Ethylen-Propylen-Dien-Kautschuk (EPDM)
• SBR/NR-Verschnitt
• SBR/BR-Verschnitt
• NR/BR-Verschnitt

The top and bottom cover plates usually consist of a rubber mixture containing a rubber component or a rubber component blend, a cross-linking agent or a cross-linking system comprising a cross-linking agent and an accelerator, and usually other mixture ingredients, in particular a filler and/or a processing aid and/or an anti-aging agent and/or a plasticizer and/or other additives (e.g. fibers, color pigments). The rubber base in this case is in particular:

• natural rubber (NR)
• butadiene rubber (BR)
• chloroprene rubber (CR)
• styrene-butadiene rubber (SBR)
• nitrile rubber (NBR)
• butyl rubber (IIR)
• ethylene-propylene rubber (EPM)
• ethylene-propylene-diene rubber (EPDM)
• SBR/NR blend
• SBR/BR blend
• NR/BR blend

CR has been of particular importance so far, as it is characterised by high flame, weather and ageing resistance, particularly for conveyor belts used in underground mining. In surface mining, NR and the above-mentioned blends ( DE 10 2009 043 904 A1 ) has become more important.

Due to the vulcanization of a rubber mixture of the type mentioned above, the conveyor belt obtains the required elastic properties.

Steel or aramid ropes running in the longitudinal direction of the conveyor belt are used as embedded tension members, with steel ropes being particularly important. In particular, in conjunction with steel rope conveyor belts, an embedded transverse reinforcement made of synthetic material is also used to protect against slits. secorden, for example made of polyamide, are used ( WO 2008/034483 A1 ). The tension member can also be a textile fabric, in particular a single- or multi-layer fabric, for example a polyester-polyamide fabric.

In most cases, a conveyor belt is guided in a conveyor system in an open form, within the frame of a troughed support roller chair.

However, in the last 20 years, the closed conveyor system using a tubular conveyor belt has also been further developed. In addition to the drums (drive drum, reversing drum), support rollers and support frames, the system components in the closed conveyor system are usually correction rollers and a hold-down roller when closing the conveyor belt. In this regard, reference is made in particular to the following patent literature: DE 36 06 129 A1 DE 10 2009 003 552 A1 DE 36 12 765 A1 EP 0 336 385 A1 DE 43 33 839 B4

Other components of a conveyor system can be a feed chute within the upper run, deflection rollers in the area of the lower run and conveyor belt profiles made of a polymer material, for example edge profiles.

Conveyor belts are subjected to great stress when they are hit by the material being conveyed, such as ore. This often leads to damage to the conveyor belt's supporting cover plate, in the form of cuts, material breakouts or other damage. These are critical for the service life of the conveyor belt and must therefore be detected as early as possible. Signs of wear due to abrasion can also occur on the running-side cover plate in contact with the drums and support rollers and possibly with other roller components mentioned above. In addition, the supporting and/or running-side cover plate of a steel cord conveyor belt can be slit open by the steel cords under extreme loads, whereby the synthetic cord cross reinforcement already presented offers - although not always - sufficient slit protection. Ultimately, the tension member can also be damaged during continuous operation, which can have a negative impact on the tensile force of a conveyor belt.

• - Die Druckschriften DE 44 44 264 C1 , DE 197 15 703 A1 , DE 10 2009 025 848 A1 , WO 02/40 384 A1 , WO 2005/030621 A1 und US 4 621 727 A beschreiben einen Ansatz, bei der die Fördergurte mit Leiterschleifen in regelmäßigen Abständen versehen werden, deren Beschädigungen durch elektroinduktive Messverfahren detektiert werden können. Anstelle der Leiterschleifen oder in Kombination mit diesen können auch Transponder zum Einsatz gelangen. Was die bedeutsame Leiterschleifentechnologie und die hiermit verbundenen Probleme betrifft, wird an einer anderen Stelle noch näher eingegangen.
• - Die Druckschriften DE 195 39 980 A1 und EP 0 787 669 B1 beschreiben eine Überwachungseinrichtung unter Verwendung von quer zur Förderrichtung in den Fördergurt eingebauten Überwachungselementen und Identifikationselementen, die bei Vorbeiführen an ortsfesten Leseeinrichtungen sowohl den Zustand als auch die Position melden. Dieses Überwachungskonzept ist jedoch in seiner Umsetzung sehr aufwendig.
• - Die Offenlegungsschrift DE 198 40 081 A1 stellt ein System zur Überwachung einer einem Verschleiß unterworfenen Schicht vor. So wird beispielsweise eine ferromagnetische Schicht in die tragseitige und/oder laufseitige Deckplatte eingebettet, die das Signal eines darunter liegenden Transponders abschirmt, es sei denn, dass diese Schicht beschädigt ist. Auch dieses Überwachungskonzept ist sehr aufwendig und nur auf speziell ausgerüstete Fördergurte anwendbar.
• - Die Kontrolle des Zustandes der Stahlseile in Fördergurten erfolgt durch ein außen vorbeigeführtes induktives Feld ( DE 199 21 224 A1 ) oder durch ein magnetisches Feld ( DE 10 2006 036 668 A1 ). Nachteilig ist, dass hiermit nur Beschädigungen der Stahlseilstrukturen erfassbar sind.
• - Bei der Überwachung der Beschädigungen der tragseitigen und/oder laufseitigen Deckplatte kommen opto-elektronische Systeme, insbesondere in Form einer Zeilen- oder Flächenkamera, zum Einsatz, wobei diesbezüglich insbesondere auf folgende

In addition to regular visual inspection, there are various systems for monitoring the condition of the conveyor belt during operation of a conveyor system. An outline of the state of the art in this regard is given below:

• - The printed publications DE 44 44 264 C1 , DE 197 15 703 A1 , DE 10 2009 025 848 A1 , WO 02/40 384 A1 , WO 2005/030621 A1 and US 4 621 727 A describe an approach in which the conveyor belts are provided with conductor loops at regular intervals, the damage to which can be detected using electro-inductive measuring methods. Transponders can also be used instead of the conductor loops or in combination with them. The important conductor loop technology and the problems associated with it are discussed in more detail elsewhere.
• - The printed publications DE 195 39 980 A1 and EP 0 787 669 B1 describe a monitoring system using monitoring elements and identification elements built into the conveyor belt transverse to the direction of conveyance, which report both the status and the position when passed by stationary reading devices. However, this monitoring concept is very complex to implement.
• - The disclosure document DE 198 40 081 A1 presents a system for monitoring a layer subject to wear. For example, a ferromagnetic layer is embedded in the top and/or bottom cover plate, which shields the signal from a transponder underneath unless this layer is damaged. This monitoring concept is also very complex and can only be used on specially equipped conveyor belts.
• - The condition of the steel ropes in conveyor belts is checked by an external inductive field ( DE 199 21 224 A1 ) or by a magnetic field ( DE 10 2006 036 668 A1 ). The disadvantage is that this only detects damage to the steel cable structures.
• - When monitoring damage to the supporting and/or running side cover plate, opto-electronic systems, in particular in the form of a line or area camera, are used, with particular attention being paid to the following

Patent literature is referred to: DE 24 13 543 A1 DE 101 29 091 A1 DE 42 40 094 A1 DE 101 40 920 A1 DE 100 29 545 A1 EP 1 187 781 B1 DE 100 48 552 A1 WO 2005/023688 A1 DE 101 00 813 A1 WO 2008/031648 A1

• - Ferner ist eine Einrichtung zur zerstörungsfreien Inspektion eines Fördergurtes mittels energiereicher Strahlen, insbesondere Röntgenstrahlen, bekannt, wobei diesbezüglich insbesondere auf folgende Patentliteratur verwiesen wird:

DE 35 17 314 A1 JP 04158208 A (Patent Abstracts of Japan) WO 2006/066519 A1 JP 2000292371 A (Patent Abstracts of Japan) The extensive development work documented here underlines the increasing importance of this monitoring device. In addition to the great technical effort, this monitoring concept is dependent on a conveyor belt surface that is free of significant contamination. For this reason, the opto-electronic system is also equipped with a blow-out device, which, however, shows the limits of its economic efficiency.

• - Furthermore, a device for the non-destructive inspection of a conveyor belt by means of high-energy rays, in particular X-rays, is known, in which regard reference is made in particular to the following patent literature:

DE 35 17 314 A1 JP 04158208 A (Patent Abstracts of Japan) WO 2006/066519 A1 JP 2000292371 A (Patent Abstracts of Japan)

The disadvantage is that with such radiation the monitoring system has to be integrated into a housing for safety reasons, which also shows the limits of economic efficiency.

Furthermore, this monitoring device primarily detects the inner workings of a conveyor belt, in particular the embedded steel cables.

The monitoring of a conveyor belt by means of a slot protection system using the conductor loops mentioned above has become particularly important, whereby the previous slot protection technology is discussed in more detail below.

A conductor loop or a conductor loop package is a package that consists of one or more endlessly connected (short-circuited) loops (contours) of any shape, for example meandering, straight, rectangular or figure-8. The contours can be made from various materials and construction elements, for example a steel cable, a conductive textile thread or a conductive polymer. They are embedded in the polymer package of the conveyor belt. This "sandwich" can be vulcanized into the supporting and/or running side cover plate of a conveyor belt during the production of a conveyor belt or subsequently, usually at a distance of 50 to 200 m. A conductor loop works according to the principle of electromagnetic induction.

With regard to the conductor loop technology and the conductor loop shape, particular reference is made to the following patent literature: DE 38 11 533 A1 DE 199 02 508 A1 DE 39 27 746 A1 DE 101 00 249 A1 DE 40 12 906 A1 EP 0 213 057 A1 DE 40 13 764 A1 WO 2005/030621 A1 DE 40 14 475 A1 WO 2010/133387 A1

• In der Offenlegungsschrift EP 0 213 057 A1 ist die Leiterschleife 8-förmig ausgebildet, und zwar im Rahmen von Mehrfachwindungen. In den beiden Fördergurtrandbereichen hat dabei die Leiterschleife ihre jeweils höchste Massenkonzentration.

In the following two disclosure documents, the conductor loop package is described in particular detail using commonly used conductor loop shapes:

• In the disclosure document EP 0 213 057 A1 The conductor loop is formed in the shape of an 8, namely in the form of multiple windings. The conductor loop has its highest mass concentration in the two conveyor belt edge areas.

In the disclosure document WO 2005/030621 A1 A conductor loop package is presented which comprises a first conductor loop. A second conductor loop is arranged within this first conductor loop. If necessary, a third conductor loop can be incorporated within this second conductor loop.

• Während des Anlagenbetriebes werden die Leiterschleifen von einer Abfragestation durch Kombination aus einem Sender und einem Empfänger und einer Schlitzüberwachungsstation abgefragt. Wenn eine Leiterschleife die Abfragestation passiert, wird mittels intakter Kontur bzw. Konturen ein elektromagnetisches Signal vom Sender auf den Empfänger übertragen. Dabei generiert der Sender ein wechselndes magnetisches Feld, das einen Strom in den leitenden kurzgeschlossenen Konturen einer Leiterschleife generiert. Dieser Strom generiert wiederum ein Magnetfeld, das vom Empfänger registriert wird, also nach dem Prinzip der elektromagnetischen Induktion. Wenn der Fördergurt in Förderrichtung geschlitzt und somit die Kontur bzw. Konturen der Leiterschleife zerstört ist, wird kein Signal vom Sender auf den Empfänger übertragen. Die Schlitzüberwachungsstation sendet ein Signal an die Zentralsteuerung der Förderanlage, wobei in diesem Fall der Fördergurt angehalten wird. Dadurch bleibt auch das Schadensausmaß begrenzt. Die Position von Leiterschleifen wird unabhängig von der Fördergurtgeschwindigkeit und von der Fördergurtlaufrichtung absolut und relativ zu den benachbarten Leiterschleifen mit Hilfe von wenigstens einem Näherungsinitiator bestimmt, der sich beispielsweise an einer Trommel befinden. Es gibt auch Lösungen zur Positionsbestimmung auf der Basis wenigstens eines Transponders. Das Schlitzschutzsystem wird an die Zentralsteuerung einer Förderanlage angeschlossen, die die gesamte Förderanlage steuert.

The slot protection system is an electrical device system that comprises at least one interrogation station, in particular in the form of a transmitter/receiver pair, at least one proximity sensor and/or at least one transponder and at least one slot monitoring station, for example in the form of a scanner, and functions according to the following principle:

• During system operation, the conductor loops are interrogated by a query station using a combination of a transmitter and a receiver and a slot monitoring station. When a conductor loop passes the query station, an electromagnetic signal is transmitted from the transmitter to the receiver using an intact contour or contours. The transmitter generates an alternating magnetic field that generates a current in the conductive, short-circuited contours of a conductor loop. This current in turn generates a magnetic field that is registered by the receiver, i.e. according to the principle of electromagnetic induction. If the conveyor belt is slotted in the conveying direction and the contour or contours of the conductor loop are thus destroyed, no signal is transmitted from the transmitter to the receiver. The slot monitoring station sends a signal to the central control of the conveyor system, in which case the conveyor belt is stopped. This also limits the extent of damage. The position of conductor loops is determined absolutely and relative to the neighboring conductor loops, regardless of the conveyor belt speed and the conveyor belt running direction, using at least one proximity sensor, which can be located on a drum, for example. There are also solutions for determining position based on at least one transponder. The slot protection system is connected to the central control of a conveyor system, which controls the entire conveyor system.

The main task of every conductor loop slot protection system is to stop a conveyor system when a longitudinal slot or a large conveyor belt damage occurs in the direction of conveyance. Limited conveyor belt notches or breakdowns must not be the cause of a conductor loop being damaged and thus a conveyor system coming to a standstill.

Because the contours in a commercially available conductor loop package, for example according to the gauge according to EP 0 213 057 A1 and WO 2005/030621 A1 , are very close to each other, there is a risk that all contours of the entire conductor loop package could fail due to a single local damage. Consequently, with such a package construction, unwanted system downtime and loss of time for the system operator are to be feared.

Another disadvantage is that the conductor loop/conductor loop package to be inserted into the supporting and/or running side cover plate represents a foreign body. The conductor loop and its endless connection are also subject to mechanical stress, which can lead to premature failure.

In summary, it can be stated that a slot protection system in conjunction with conductor loops embedded in the conveyor belt is susceptible to a variety of faults.

In the background of the overall problem mentioned above, the task is to provide a generic device for monitoring a conveyor system with a slot protection system in which the longitudinal slots of the conveyor belt are detected without conductor loops, while at the same time providing greater interference immunity and better mechanical durability.

• - die tragseitige und/oder laufseitige Deckplatte des Fördergurtes mit wenigstens einer elektrisch leitfähigen Polymerschicht versehen ist/sind, die sich als Streifen in Querrichtung des Fördergurtes erstreckt; und dass
• - der Sensor eine elektrisch leitfähige Messsonde ist, an die ein elektrisches Wechselsignal angelegt ist, wobei die Spannung derart gewählt ist, dass sich aufgrund des dielektrischen Verschiebestromes ein messbares Signal ergibt, wobei bei einem Längsschlitzen des Fördergurtes unter Zerstörung der elektrisch leitfähigen Polymerschicht das zuvor vorhandene Signal wegen des höheren Widerstandes entfällt, verbunden mit einem Warnhinweis oder automatischen Stillstand der Förderanlage.

This task is solved by

• - the supporting and/or running side cover plate of the conveyor belt is/are provided with at least one electrically conductive polymer layer which extends as a strip in the transverse direction of the conveyor belt; and that
• - the sensor is an electrically conductive measuring probe to which an alternating electrical signal is applied, the voltage being selected in such a way that a measurable signal is produced due to the dielectric displacement current, whereby in the event of longitudinal slitting of the conveyor belt, the electrical rically conductive polymer layer, the previously existing signal is eliminated due to the higher resistance, associated with a warning or automatic shutdown of the conveyor system.

The electrically conductive polymer layer replaces the conductor loop as part of a conductor loop slot protection system.

• - Elektrisch leitfähige Polymerschicht

In the following, advantageous design options of the device according to the invention with regard to the electrically conductive polymer layer and measuring probe are shown:

• - Electrically conductive polymer layer

The electrically conductive polymer layer extends over the entire conveyor belt width. This is an advantage over conductor loops, which cannot extend over the entire conveyor belt width due to the complete embedding in the polymer material of the load-bearing and/or running-side cover plate.

The thickness of the electrically conductive polymer layer is at least 25%, in particular at least 50%, of the cover plate thickness. Depending on where this polymer layer is located, this is the thickness of the load-bearing or running-side cover plate, which can have different thicknesses. The same thickness of a cover plate is not required.

The basis of the polymer layer can be an elastomer, thermoplastic elastomer or a thermoplastic. Of particular importance is an elastomer formed from a vulcanized rubber mixture, as described in the introduction to the description for the material for the load-bearing and running-side cover plates. The same rubber base can be used. For example, if the load-bearing and running-side cover plates consist of a vulcanized rubber mixture based on CR, the polymer layer can also be CR-based.

• - Die Partikel liegen als Metallpulver und/oder Metallfasern vor. Dabei beträgt bei Metallfasern in Form von Kurzschnittfasern die Faserlänge insbesondere 1 bis 6 mm.
• - Bei Einsatz von Metallverbindungen, beispielsweise Metallsalzen, beispielsweise Eisenchlorid (FeCl₃), oder Metalloxiden, beispielsweise indiumdotiertes Zinkoxid (ITO), ist die Pulverform vorrangig.
• - Die Partikel sind Ruß und/oder Kohlenstoff-Fasern. Der Ruß ist dabei insbesondere ein Leitruß. Bei den Kohlenstoff-Fasern beträgt die Faserlänge 50 bis 150 µm. Bei Verwendung von Kohlenstoff-Fasern sind bei einer Faserlänge von 3 bis 6 mm auch Kurzschnittfasern möglich.
• - Die Partikel sind Nanotubes und bestehen aus Kohlenstoff ( US 7 338 648 B2 ) mit der Kurzbezeichnung CNT. Nanotubes sind Röhren mit schichtartigem Aufbau von wenigen Nanometern Durchmesser.
• - Bei Einsatz von ionischen Flüssigkeiten, die aus einem kationischen und anionischen Teil bestehen, kommen beispielsweise zum Einsatz:

Kationen: Dialkylimidazolium, Alkylpyridinium, Tetraalkylammonium, Tetraalkylphosponium Anionen: Chlorid, Bromid, Tetrafluorborat, Tetrachloroferrat (III), Hexafluorophosphat, Alkylsulfonat

• - Die Partikel bestehen aus einem Polymer, einem Polymerblend oder einer Polymermischung mit elektrisch leitfähigen funktionellen Gruppen, die insbesondere Carbonylgruppen, insbesondere wiederum Estergruppen, sind. Eingesetzt wird/werden hier insbesondere ein Polyethylenglykolester und/oder ein Polyethylenglykolcarbonsäureester.

Electrically conductive particles are now mixed into the polymer layer, preferably evenly distributed. Various electrically conductive materials can be used for the electrically conductive particles, which are now part of the mixture ingredients, and an overview of these is provided below.

• - The particles are in the form of metal powder and/or metal fibers. In the case of metal fibers in the form of short-cut fibers, the fiber length is in particular 1 to 6 mm.
• - When using metal compounds, such as metal salts, such as iron chloride (FeCl ₃ ), or metal oxides, such as indium-doped zinc oxide (ITO), the powder form is preferred.
• - The particles are soot and/or carbon fibers. The soot is particularly a conductive soot. The fiber length of the carbon fibers is 50 to 150 µm. When using carbon fibers, short-cut fibers are also possible with a fiber length of 3 to 6 mm.
• - The particles are nanotubes and consist of carbon ( US 7 338 648 B2 ) with the abbreviation CNT. Nanotubes are tubes with a layered structure of a few nanometers in diameter.
• - When using ionic liquids that consist of a cationic and anionic part, the following are used, for example:

Cations: dialkylimidazolium, alkylpyridinium, tetraalkylammonium, tetraalkylphosponium Anions: Chloride, bromide, tetrafluoroborate, tetrachloroferrate (III), hexafluorophosphate, alkyl sulfonate

• - The particles consist of a polymer, a polymer blend or a polymer mixture with electrically conductive functional groups, which are in particular carbonyl groups, in particular ester groups. In particular, a polyethylene glycol ester and/or a polyethylene glycol carboxylic acid ester is/are used here.

The electrically conductive particles are present in an amount of 0.5 to 20% by weight, although an amount of 1 to 5% by weight is usually sufficient. If the support-side and/or running-side cover plate of the conveyor belt already has a low electrical conductivity due to the use of standard carbon black in the rubber mixture, the electrically conductive polymer layer in strip form is characterized by an increased electrical conductivity.

For further details of the electrically conductive particles, please refer to the published patent application WO 2009/003853 A2 referred to.

The electrically conductive polymer matrix in strip form is incorporated into the supporting and/or running side cover plate of the conveyor belt during its manufacture.

• - Elektrisch leitfähige Messsonde

In the longitudinal direction of the conveyor belt, several electrically conductive polymer layers in strip form can be present at a distance of, for example, 50 to 200 m.

• - Electrically conductive measuring probe

The sensor comprises two electrically conductive measuring probes, one measuring probe being arranged in each side area of the conveyor belt. This ensures optimum monitoring of the gaps in the conveyor belt. Any gaps usually occur in the middle of the conveyor belt, where the material is fed in.

The measuring probe is designed as a metal plate.

The measuring probe is also arranged at a distance of ≤ 10 mm from the passing conveyor belt. The preferred distance range is 2 to 5 mm.

In the longitudinal direction of the conveyor belt, several sensors in the form of these electrically conductive measuring probes can be present at a distance of, for example, 50 to 200 m.

The measuring probe is arranged in the upper run and/or the lower run on the side of the running side cover plate of the conveyor belt between the support rollers. It can also be arranged in the lower run on the support side cover plate of the conveyor belt. In this case, however, it is advantageous if the conveyor system is also equipped with a brush or a scraper that cleans the conveyor belt surface.

• 1 eine Förderanlage in der Seitenansicht;
• 2 eine Förderanlage im Querschnitt mit zwei Sensoren in Form elektrisch leitfähiger Messsonden;
• 3 eine Förderanlage in laufseitiger Draufsicht mit einer elektrisch leitfähigen Polymerschicht und zwei Sensoren in Form elektrisch leitfähiger Messsonden.

The invention will now be explained using embodiments with reference to schematic drawings.

• 1 a conveyor system in side view;
• 2 a conveyor system in cross-section with two sensors in the form of electrically conductive measuring probes;
• 3 a conveyor system in top view from the running side with an electrically conductive polymer layer and two sensors in the form of electrically conductive measuring probes.

1 shows a conveyor system 1 with a conveyor belt 2, comprising a supporting-side cover plate 3 and a running-side cover plate 4, each made of a polymeric material with elastic properties, for example a vulcanized rubber mixture based on CR, as well as an embedded tension member, for example in the form of steel cables.

In the running direction (arrow direction), the conveyor belt 2 is guided around the drum 5 from the lower run B to the upper run, with the material being conveyed within the upper run A. The feed point 7 for the conveyed material is located in the immediate area of the drum 5, which is usually the drive drum. The drum where the conveyor belt 2 is transferred from the upper run A to the lower run B, while the conveyed material is simultaneously discharged, is not shown here. The running-side cover plate 4 is supported on support rollers 6 within the upper run A and the upper run B.

2 now shows the conveyor system 1 in cross-section within the upper run, with the conveyor belt 2 transporting the conveying material 8. The trough-shaped conveyor belt is supported on three support rollers 6, which together form the support roller frame. In the side area of the conveyor belt, two sensors 9 in the form of electrically conductive measuring probes are now arranged on the support roller side. Each measuring probe consists of a metal plate.

3 now shows the conveyor system 1 in the running direction (arrow direction) of the conveyor belt 2 in its running side view. The running side cover plate is provided with an electrically conductive polymer layer 10, which extends as a strip in the transverse direction of the conveyor belt and takes up the entire conveyor belt width. In the side area of the conveyor belt on its running side between the support rollers, the two sensors 9 in the form of electrically conductive measuring probes are located. An electrical change signal is applied, the voltage being selected such that a measurable signal is produced due to the dielectric displacement current, wherein in the case of a longitudinal slit of the conveyor belt 2, destroying the electrically conductive polymer layer 10, the previously existing signal is eliminated due to the higher resistance, associated with a warning or automatic stoppage of the conveyor system.

List of reference symbols (part of the description)

1

conveyor system

2

conveyor belt

3

load-bearing cover plate

4

running-side cover plate

5

drum

6

support rollers

7

feed point for the conveyed material

8

conveying material

9

Sensor in the form of an electrically conductive measuring probe Electrically conductive polymer layer in strip form

10 A

Obertrum

B

lower run

Claims (12)

Device for the continuous and non-destructive monitoring of a conveyor system (1) with the following components: - an endless closed conveyor belt (2) with a support-side cover plate (3) and a running-side cover plate (4), each made of a polymer material with elastic properties and with an embedded tension member; - drums (5), support rollers (6) and support frames, wherein the aforementioned components in conjunction with the conveyor belt (2) form a material-conveying upper run (A) with a feed point (7) for the conveying material (8) and a mostly material-free lower run (B); and - a slot protection system for detecting longitudinal slots in the conveyor belt (2), which is provided with at least one sensor (9) which detects the surface of the support-side cover plate (3) within a material-free area and/or the surface of the running-side cover plate (4) of the passing conveyor belt (2) without contact, wherein a process computer takes over the evaluation of the data acquisition; characterized in that - the support-side cover plate (3) and/or the running-side cover plate (4) of the conveyor belt (2) is/are provided with at least one electrically conductive polymer layer (10) which extends as a strip in the transverse direction of the conveyor belt; and in that - the sensor (9) is an electrically conductive measuring probe to which an alternating electrical signal is applied, the voltage being selected such that a measurable signal is produced due to the dielectric displacement current, wherein when the conveyor belt (2) is slit lengthwise, destroying the electrically conductive polymer layer (10), the previously present signal is eliminated due to the higher resistance, associated with a warning or automatic shutdown of the conveyor system (1). Facility according to claim 1 , characterized in that the electrically conductive polymer layer (10) extends over the entire conveyor belt width. Facility according to claim 1 or 2 , characterized in that the thickness of the electrically conductive polymer layer (10) is at least 25% of the cover plate thickness. Facility according to one of the Claims 1 until 3 , characterized in that electrically conductive particles are mixed into the polymer layer (10). Facility according to claim 4 , characterized in that the electrically conductive particles are evenly mixed. Facility according to one of the Claims 1 until 5 , characterized in that several electrically conductive polymer layers (10) are present at a distance in the longitudinal direction of the conveyor belt (2). Facility according to one of the Claims 1 until 6 , characterized in that the sensor (9) comprises two electrically conductive measuring probes. Facility according to claim 7 , characterized in that the two electrically conductive measuring probes are arranged such that one measuring probe (9) detects the respective side region of the conveyor belt (2). Facility according to one of the Claims 1 until 8 , characterized in that the electrically conductive measuring probe (9) is designed as a metal plate. Facility according to one of the Claims 1 until 9 , characterized in that the electrically conductive measuring probe (9) is arranged at a distance ≤ 10 mm from the passing conveyor belt (2). Facility according to one of the Claims 1 until 10 , characterized in that the electrically conductive measuring probe (9) is arranged in the upper run (A) and/or in the lower run (B) on the side of the running-side cover plate (4) of the conveyor belt (2) between the support rollers (6). Facility according to one of the Claims 1 until 11 , characterized in that the electrically conductive measuring probe (9) is arranged in the lower run (B) on the side of the support-side cover plate (3) of the conveyor belt (2).