No abstract

Considering that the movement trajectory of roadheader cutting head directly affects the surface morphology characteristics of roadway forming, the creation mechanism of roadway contour obtained by cutting head cutting roadway is analyzed. The robot kinematics analysis method was used to determine the coordinates of the roadheader cutting head in the roadway space coordinate system, and the mathematical model of the cutting head cutting the roadway contour was constructed. Through numerical calculation, the differences of roadway morphology characteristics formed by three different types of cutting heads are analyzed. The orthogonal experiment was designed, and the regression equation under multiple factors was solved with the experimental results. The influence of cutting feed rate, cutting Angle, cutting head radius and cutting head cone Angle on the morphology characteristics of cutting surface was analyzed by regression calculation and theoretical calculation. The research results show that the roadway surface obtained by "spherical crown + cylinder" cutting head is the most uneven, and the roadway surface obtained by "spherical crown + cone + cylinder" cutting head is the most flat. With the decrease of cutting lifting Angle, cutting feed, cutting head cone Angle and the increase of cutting head crown radius, the smoothness of roadway obtained by cutting is higher.

Considering that the trajectory of the cutting head of the longitudinal axis roadheader directly affects the surface morphology of the roadway, the formation mechanism of the outer profile of the roadway obtained by the cutting head is analyzed, and the dynamic model of the cutting part was constructed. The variation law of the vibration swing angle of the cutting head under different working conditions was obtained, and the coordinate of the cutting head of the roadheader in the roadway space coordinate system was determined by using the robot kinematics analysis method. The mathematical model of cutting the outer outline of the roadway by the cutting head is constructed. Through the numerical calculation and analysis, the characteristics of the formed outer profile of the roadway were analyzed considering the influence of the vibration of the cutting head. The results show that the difference between the “pit” and the “peak ridge” obtained by considering the vibration of the cutting head is larger than that without considering the vibration of the cutting head, which shows that the outer outline of the roadway obtained by the real cutting is more rougher than that without considering the vibration of the cutting head. With the increase of the cutting lifting angle, the maximum and average value of the difference between the “pit” and the uplift “peak ridge” on the coal and rock shows an increasing trend, and with the increase of the cylinder pressure, the maximum values of the horizontal swing angle “pit” and the uplift “peak ridge” gradually increase. The vibration of the cutting head when cutting coal and rock will have a great influence on the outer profile of the roadway, which cannot be ignored in the research of accurate autonomous cutting control algorithm of roadheader. The research results of this paper can provide a basis for the optimization of cutting parameters and high-precision forming control method of roadheader.

To deeply analyse the dynamic characteristics of the scraper conveyor during operation, the mechanical characteristics of the coupled longitudinal and torsional vibrational modes under excitation by cargo loading are studied. Based on the Kelvin‒Voigt model and the point-by-point tension method, a model of the coupled longitudinal and torsional vibrations of the scraper chain drive system is established. Then the functional program is constructed and the numerical simulation is carried out. Finally, the correctness of the model is verified by comparison with experiments. The research results reveal the torsional vibration characteristics of the scraper chain drive system under two different working conditions, light load and medium load, and determine the influence area of the torsional vibration of the scraper. The results of this analysis provide a theoretical basis for the subsequent optimization of the scraper parameters, the prediction of scraper chain drive system failure, and the calculation to give an early warning before failure occurs.

Taking into account the safety factor of the conventional calculation of chain is in accordance with the two chain to bear external load is calculated, and the actual situation of the two chains of load is not uniform, this paper uses nonlinear dynamic finite element software ABAQUS, the simulation system of scraper chain under bias load, torsional vibration in the process of chain distribution should be produced stress and strain. A torsional vibration model of Kelvin-Voigt scraper chain and system based on the analysis of the vibration characteristics of material loading and clamping the chain scraper chain under torsion. Twist vibration from two adjacent scraper chain as a finite element analysis model of the boundary conditions, the finite element analysis of the stress and strain of the chain, we obtain two kinds of different conditions in the chain link stress strain response and the maximum stress and strain distribution, provide the basis for follow-up in the chain of life prediction, safety factor calculation.