Longwall shearers operating in the underground mine workings move along the longwall face along the conveyor troughs. The haulage system, which is made up of two kinematic pairs in the form of track wheels installed in shearer movers, cooperating with the toothed route built in the conveyor’s throughs, is responsible for moving the shearer. The currently used solutions of longwall shearers’ haulage systems do not ensure proper cooperation of the track wheels with toothed segments, which results in failures and breakdowns in the operation of the longwall systems, causing significant financial losses. Rigid solution of the gear components used is the reason. The solution of the flexible toothed segment, allowing it to adapt to the longitudinal and transverse curvature of the AFC (armored face conveyor) route during cooperation with the track wheel, was developed as part of the research project jointly implemented by KOMAG Institute of Mining Technology, AGH University of Science and Technology, Łukasiewicz Research Network–Cracow Institute of Technology, Specodlew Innovative Foundry Company and Polish Mining Group Inc., co-financed by the European Regional Development Fund (contract no. POIR.04.01.04-00-0068/17). The general design and principle of operation of the suggested KOMTRACK system is given. The results of the comparative simulations and analyses are presented. The load and slip values during the cooperation of the track wheels with the standard and new suggested toothed segment were estimated. The effectiveness of cooperation in the shearer movement along a disturbed conveyor route was also compared.

In Polish underground mining plenty of dog headings are drilled with mechanical methods with the use of arm roadheaders equipped with milling units. Cutting tools applied on the units -rotary tangent bits in unfavourable mining and geological conditions or improper work conditions are affected by an accelerated wear process. It influences the speed and costs of drilling such excavations. The article presents a new and innovative solution of a mining head with asymmetric disc tools of complex trajectory elaborated at the Department of Mining, Dressing and Transport Machines, AGH University of Science and Technology, Krakow as an alternative for standard milling units. Advantages of the applied mining method using so called back incision were described as well as principles of construction and work of the suggested solution of the head. In order to work out a construction of the head prototype it was necessary to determine principles and guidelines based on laboratory tests. A construction of a specially prepared laboratory stand for examination of disc tools of complex trajectory, planned research methodology, course of tests and obtained results were presented. An analysis of the results allowed determining the above listed principles and guidelines for a construction of a prototype head. They were the base to work out, with cooperation of the REMAG Ltd Company in Katowice, a technical project of a new head solution, adapted for mounting on the arm of a medium arm roadheader KR 150. A constructed head underwent tests on a research stand on the REMAG testing area and received positive preliminary tests results.Keywords: roadheader, mining, hard rock, cutting head W polskim górnictwie podziemnym bardzo duża liczba wyrobisk korytarzowych drążona jest metodami mechanicznymi z wykorzystaniem ramionowych kombajnów chodnikowych, wyposażonych w organy frezujące. Stosowane na tych organach narzędzia skrawające -noże styczno-obrotowe, w niekorzystnych warunkach górniczo-geologicznych lub przy nieprawidłowych warunkach pracy, ulegają przyspieszonemu zużyciu. Wpływa to na prędkość i koszty drążenia tych wyrobisk. W artykule przedstawiono opracowane w Katedrze MGPiT AGH Kraków nowe i innowacyjne rozwiązanie głowicy urabiającej, z narzędziami dyskowymi niesymetrycznymi o złożonej trajektorii, jako alternatywę dla standardowych organów frezujących. Opisano zalety zastosowanej metody urabiania z wykorzystaniem tzw. tylnego podcinania

The use of asymmetrical disc tools for the mining of hard and very hard rocks is a promising direction for developing mechanical mining methods. A significant obstacle in developing mining methods with the use of asymmetric disc tools is the lack of adequate computational methods. A deep understanding of rock–tool interaction can develop industrial applications of asymmetric disc tools significantly. The fundamental problem in designing work systems with asymmetric disc tools is the lack of adequate analytical models to identify tool loads during the mining process. One reasonable approach is to use computer simulation. The purpose of the research was to develop a simulation model of rock cutting using an asymmetrical disc tool and then evaluate the developed model. In the article, the Discrete-Element Method (DEM) in LS-Dyna was adopted to simulate rock cutting with asymmetrical disc tools. Numerical tests were conducted by pushing the disc into a rock sample at a given distance from the sample edge until the material was detached entirely. Two types of rock samples were used in the simulation tests: concrete and sandstone. The independent variables in the study were the disc diameter and the cut spacing. To validate the simulation model, analogous laboratory tests were carried out. The article presents a comparison of the results of simulation and laboratory tests. The given comparison showed good accordance LS-Dyna model with the experimental studies. The proposed test results can be input data for developing simulation models on a larger scale. Thus, it will be possible to consider the complex kinematics of the dynamics of the rock-mining process with disc tools using the DEM simulation.

Underground salt mining accounts for about 16 percent of the total salt production worldwide. When excavating salt rock, the cutters of the road header come into contact with the rock. This produces friction and, consequently, a rise in temperature. Generally, as temperature increases, salt gradually loses its plasticity. The extent of these alterations depends on the presence of other minerals in the rock. This paper presents the results of laboratory tests on regularly shaped samples of salt. An analysis was performed of the results of compressive, tensile and induced-shear strength, and of Young's modulus, Poisson's ratio, cuttability index and side chipping angle. The testing was conducted on samples with a temperature of about 20°C and samples heated to 50°C and 80°C. The tests showed that as temperature increased, so did compressive and tensile strength, and longitudinal and transverse strain of salt. The temperature increase caused, however, a decrease in shear strength. The cuttability index and the side chipping angle also decreased when the heated samples were being cut. The percentage changes in the parameters within the 60-degree temperature range were as high as several dozen percent.

The article presents the idea of a new solution for KOMTRACK longwall shearer haulage system. Based on the analysis of test results of an earlier version of the FLEXTRACK haulage system, a new version of the KOMTRACK system was developed. Using the ANSYS LS-Dyna program, simulations of the longwall shearer’s drive wheel mating with the selected elements of the toothed haulage segment were performed. The purpose of the analyzes was identification of contact stress value of the elements of the feed system as a function of geometrical parameters of various solutions of the toothed bar. The result of the simulation was the selection of the rack solution for further field and industrial tests.