Koncepcja algorytmu sterowania wydajnością przenośnika ścianowego.

Wprowadzanie w nowoczesnych przenośnikach ścianowych możliwości zasilania silników napędowych za pomocą przemienników częstotliwości umożliwia sterowanie ich prędkością. Jednym z podstawowych problemów sterowania prędkością ruch łańcucha w przenośniku ścianowym jest jej dostosowanie do zakładanej wydajności kombajnu ścianowego. Zbyt niska prędkość przenośnika może być powodem jego zasypania i, w przypadku niewystarczającej mocy, utknięcia (problemu z rozruchem). Z kolei zbyt wysoka prędkość może powodować straty mocy i niewykorzystanie jego potencjalnej wydajności (jest to jednak mniej niebezpieczne). W polskich kopalniach, w większości przypadków, po rozruchu, przenośniki ścianowe pracują z nominalną (maksymalną) prędkością (wydajnością). Nowoczesne przenośniki są wyposażone coraz częściej w przemienniki częstotliwości, za pomocą których zasilane są ich silniki napędowe. Pozwala to na zmianę prędkości obrotowej tych silników. W artykule przedstawiono koncepcję algorytmu sterowania prędkością (wydajnością) ścianowego przenośnika zgrzebłowego, umożliwiającego dostosowanie jego wydajności do bieżącego obciążenia przenośnika

Testing the Impact of Braking Algorithm Parameters on Acceleration and Braking Distance for a Suspended Monorail with Regard to Acceptable Travel Speed in Hard Coal Mines

Increasing the maximum speed limit of suspended monorails, which became a very popular means of auxiliary transport, is one of the aspects of improving the efficiency of work in underground coal mines. It is especially important to enable higher (than allowed by the law) travel speed, when moving the crew to and from the workplace, which is often very distant from the shaft, and can take more than one hour of travel. Increasing this speed will make it possible to extend the effective working time of miners, which should have a positive impact on the economics of the mine. However, driving at a higher speed is also associated with increased risk of a negative impact of dynamic overload to people, e.g., during emergency braking of the suspended monorail. The concept of sequential emergency braking was developed in order to avoid excessive deceleration affecting passengers and the operator of the monorail, as well as to minimize the dynamic loads acting on the rail suspensions and on the roadway support frames, which could cause serious accidents. The developed assumptions with regard to the new method of braking are innovative in the area related to hard coal mining, where there are currently no such solutions. According to the principles of the developed concept, the total braking force was divided into two stages. The activation of the second stage depends on the deceleration measured after the time delay from activation of the first stage of braking. We present the results of the numerical simulations, which aimed to analyze the impact of changing the parameters of the braking algorithm on the braking deceleration, the braking time, and the braking distance. The possibility of changing the braking force and downward emergency braking on a high inclination angle were also taken into account during the numerical simulations. Use of the developed emergency braking algorithm enables the optimization of this process at a higher speed than is currently used. This aspect is also very important in increasing the safety for people travelling at a higher speed limit. The numerical simulations provide knowledge for safety in terms of the dynamic overload during emergency braking, without injury risk to miners or damage to equipment

Testing the Impact of Braking Algorithm Parameters on Acceleration and Braking Distance for a Suspended Monorail with Regard to Acceptable Travel Speed in Hard Coal Mines

Increasing the maximum speed limit of suspended monorails, which became a very popular means of auxiliary transport, is one of the aspects of improving the efficiency of work in underground coal mines. It is especially important to enable higher (than allowed by the law) travel speed, when moving the crew to and from the workplace, which is often very distant from the shaft, and can take more than one hour of travel. Increasing this speed will make it possible to extend the effective working time of miners, which should have a positive impact on the economics of the mine. However, driving at a higher speed is also associated with increased risk of a negative impact of dynamic overload to people, e.g., during emergency braking of the suspended monorail. The concept of sequential emergency braking was developed in order to avoid excessive deceleration affecting passengers and the operator of the monorail, as well as to minimize the dynamic loads acting on the rail suspensions and on the roadway support frames, which could cause serious accidents. The developed assumptions with regard to the new method of braking are innovative in the area related to hard coal mining, where there are currently no such solutions. According to the principles of the developed concept, the total braking force was divided into two stages. The activation of the second stage depends on the deceleration measured after the time delay from activation of the first stage of braking. We present the results of the numerical simulations, which aimed to analyze the impact of changing the parameters of the braking algorithm on the braking deceleration, the braking time, and the braking distance. The possibility of changing the braking force and downward emergency braking on a high inclination angle were also taken into account during the numerical simulations. Use of the developed emergency braking algorithm enables the optimization of this process at a higher speed than is currently used. This aspect is also very important in increasing the safety for people travelling at a higher speed limit. The numerical simulations provide knowledge for safety in terms of the dynamic overload during emergency braking, without injury risk to miners or damage to equipment

Wirtualne prototypowanie kolejki podwieszonej w aspekcie zwiększenia jej dopuszczalnej prędkości jazdy w kopalniach węgla kamiennego

Due to the longer distance of moving the crew to the workplace in hard coal mines, the possibility of increasing the maximum permissible speed of suspended monorails was considered. To ensure an adequate level of safety, decelerations affecting the crew in the case of emergency braking in various travelling conditions were analysed. The computational model was verified based on the results of the bench tests on a dedicated test track. The article presents a comparison of results of numerical calculations with measurements at the test stand, and results of numerical simulations in relation to the criterial states that could not be checked at the test stand as well as the analysis of overloads that affect the crew during the emergency braking. These overloads have a significant impact on safety of the operator and passengers, and their determination and analysis may be the basis for assessing the degree of safety as well as for the development of guidelines for designing the additional equipment for the operator's cabs and passenger cars, i.e. components increasing their safety.W związku z wydłużającym się czasem dojazdu załogi do miejsca pracy w kopalniach węgla kamiennego, rozważana jest możliwość zwiększenia maksymalnej dopuszczalnej prędkości jazdy kolejek podwieszonych. W celu zapewnienia odpowiedniego poziomu bezpieczeństwa, przeprowadzono analizy opóźnień oddziałujących na załogę w sytuacji awaryjnego hamowania w odniesieniu do różnych stanów kryterialnych. Model obliczeniowy został zweryfikowany w oparciu o wyniki badań stanowiskowych, przeprowadzonych na dedykowanym torze testowym. W artykule przedstawiono porównanie wyników obliczeń numerycznych oraz zmierzonych na stanowisku badawczym oraz wyniki symulacji numerycznych w odniesieniu do stanów kryterialnych, których nie można było sprawdzić na stanowisku badawczym, oraz przedstawiono analizę przeciążeń, jakie oddziałują na załogę w sytuacji awaryjnego hamowania. Wartości te mają duży wpływ na bezpieczeństwo operatora i pasażerów, a ich wyznaczenie i analiza może stanowić podstawę do oceny stopnia bezpieczeństwa oraz wytyczne do zaprojektowania dodatkowego wyposażenia kabin operatora i wozów pasażerskich, w postaci elementów zwiększających bezpieczeństwo ich użytkowania

Analysis of impact of longitudinal inclination of a chain conveyor on dynamical phenomena during operation

Armoured face conveyors (AFCs) of length even up to 500 meters are used in coal mines for transportation of run-of-mine. The method of their installation depends on the geological and mining conditions and on a coal seam position. Operation of AFC in a horizontal or inclined position is allowed. The maximum accepted inclination is determined by the machine manufacturer. Two directions of longitudinal inclination of the conveyor have to be considered: upward and downward transportation of excavated material. Both the angle and the direction of inclination of the conveyor have a significant impact on the dynamics of its operation. Change in inclination of AFC results in tension of the chain. Loosening the scraper chain can lead to blockage, what can be a reason of damage. Excessive chain tension results in speeding up frictional wear of conveyor components. Determination of an impact of longitudinal inclination of the conveyor on a degree and a place of loosening or excessive tension of the chain was the objective of the numerical analyses, the results of which are presented. Analysis were performed using the developed numerical model of the Rybnik 850 conveyor. These analyses are a part of the preparatory work aiming at development of the control algorithm of AFC, to prevent the formation of unfavorable dynamic effects during the conveyor operation

Analysis of impact of longitudinal inclination of a chain conveyor on dynamical phenomena during operation

Armoured face conveyors (AFCs) of length even up to 500 meters are used in coal mines for transportation of run-of-mine. The method of their installation depends on the geological and mining conditions and on a coal seam position. Operation of AFC in a horizontal or inclined position is allowed. The maximum accepted inclination is determined by the machine manufacturer. Two directions of longitudinal inclination of the conveyor have to be considered: upward and downward transportation of excavated material. Both the angle and the direction of inclination of the conveyor have a significant impact on the dynamics of its operation. Change in inclination of AFC results in tension of the chain. Loosening the scraper chain can lead to blockage, what can be a reason of damage. Excessive chain tension results in speeding up frictional wear of conveyor components. Determination of an impact of longitudinal inclination of the conveyor on a degree and a place of loosening or excessive tension of the chain was the objective of the numerical analyses, the results of which are presented. Analysis were performed using the developed numerical model of the Rybnik 850 conveyor. These analyses are a part of the preparatory work aiming at development of the control algorithm of AFC, to prevent the formation of unfavorable dynamic effects during the conveyor operation

Dynamic analysis of scraper conveyor operation with external loads

A load to an armoured face conveyor (AFC) during coal mining is changeable and very difficult or even impossible to be predicted. Changes of the load to the upper scraper chain affect the load of the driving motor and generate changes in a scraper chain tension. Impact of increasing the external load to the upper scraper chain on the operation of electric motors and on the scraper chain tension is presented. The developed numerical model of the Rybnik 850 conveyor enabled identifying the places of the scraper chain high tension or places of its loosening. An impact of changing frequency of driving motor voltage on AFC’s operational conditions was tested and analysed using the AFC’s numerical model. During tests, tension of the scraper chain on the discharge end and the return end was recorded. High tension of the scraper chain and its loosening during the changeable load were also recorded on upward and downward transportation of run-of-mine material

Wpływ regulacji wybranych parametrów przenośnika zgrzebłowego na stan jego pracy

W długich przenośnika ścianowych, na skutek zmiennego obciążenia urobkiem oraz sprężystego wydłużenia łańcucha zgrzebłowego powstają stany okresowego lub stałego luzowania lub nadmiernego napięcia łańcucha. Stany takie często są przyczyną zerwania łańcucha. W celu poprawy stanu pracy opracowano algorytm sterowania wybranymi parametrami pracy przenośnika. W artykule przedstawiono modułowy model obliczeniowy ścianowego przenośnika zgrzebłowego, który posłużył do przeprowadzenia symulacji numerycznych. Przeprowadzono analizę wpływu regulacji wybranych parametrów pracy przenośnika na stan napięcia łańcucha zgrzebłowego. Wyniki symulacji potwierdzają możliwość poprawy stanu napięcia łańcucha poprzez regulację wybranych parametrów pracy przenośnika