Meitan xuebao (Sep 2023)
Study on temperature and wear behavior of disc cutter in cutting coal rock
Abstract
The heat generation mechanism, wear behavior and quantitative relationship between cutting load and coal rock characteristics of the interaction between the cutting tool of mining machinery and coal rock mass, are the keys in solving the wear failure short life of the cutter, and realizing the safe and efficient heading. By comprehensively analyzing the impact of temperature on tool life, wear, and cutting efficiency, the temperature and wear distribution law of disc cutter in cutting coal rock are explored, and the heat generation mechanism and wear characteristics of disc cutter in cutting coal rock are revealed. Under the cutting conditions of non-vibration and axial excited vibration, the heat flux calculation formulas of the cutter wedge surface and the blade are established by friction work. Based on the semi-infinite heat transfer model under the condition of instantaneous point heat source and heat compensation principle, the heat transfer models of wedge irregular surface heat source and blade line heat source of disc cutter are given, and the temperature mathematical model of any point is established. Also, the influence of relevant parameters on the temperature field of cutter was solved and analyzed. Using the finite element ABAQUS, and discrete element EDEM software, the study simulates the temperature field and wear characteristics of disc cutter in cutting coal rock at different feed speeds, and sets up an experimental system for vibration cutting coal rock with disc cutter. Furthermore, the study tests the temperature characteristics of coal rock broken by disc cutter, and comprehensively investigates the distribution law of temperature and wear behavior characteristics of disc cutter in theory, simulation, and experiment. The results show that the characteristics of temperature variation of disc cutter are mainly concentrated on the blade, which decreases gradually from the blade to the wedge surface. The temperature distribution along the circumference of disc cutter is like a parabola, and the temperature decreases gradually from the middle blade to both sides. Under different feed speeds, the steady-state average maximum temperatures obtained by theoretical calculation (cutting time tends to infinity) of non-vibration and axial excited vibration are 374.76 ℃ and 245.72 ℃ respectively. The average maximum temperatures obtained by simulation (cutting time is about 3 s) are 80.13 ℃ and 73.60 ℃ respectively, and the average maximum temperature without vibration is 8.87% higher than that with vibration. And the experimental results (cutting time is about 3 s) are 72.56 ℃ and 66.99 ℃, and the average maximum temperature without vibration is 8.45% higher than that with vibration, the average error between simulation and experiment is 11.69%. In the experimental process of disc cutter in cutting coal rock, the circumferential spin phenomenon of the cutter is conducive to its evenly wear, and vibration cutting is more obvious than non-vibration. The temperature dissipation of the disc cutter blade presents a nonlinear downward trend, which is rapidly transferred from the blade to the wedge surface, its structural form can avoid aggravating the local wear of the cutter due to the accumulation and concentration of temperature. The disc cutter wear is concentrated at the blade, the relative wear along the circumference is a parabola distribution, the relative wear of the middle blade is larger, and the relative wear of the two side blades is gradually reduced. And the ABAQUS simulation combined the cutter wear model estimates the characteristic law of relative blade wear, which are the same as that obtained by EDEM simulation. The relative wear amount of disc cutter circumference is consistent with the temperature characteristic law, the correlation coefficients are higher than 0.90, cutting temperature can characterize the cutter wear. The internal connection between the temperature distribution characteristics of disc cutter in cutting coal rock and its wear law is obtained by comprehensive theory, simulation, and experiment, the three temperature variation laws are consistent, which verifies the accuracy and effectiveness of the cutter heat transfer model.
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