碟盘刀具截割煤岩温度及磨损行为研究

Study on temperature and wear behavior of disc cutter in cutting coal rock

  • 摘要: 采掘机械截割刀具与煤岩体作用的产热机制、磨损行为及截割载荷与煤岩特征定量关系,是解决截割刀具磨损失效、寿命短,实现安全、高效掘进巷道的关键。通过综合分析温度对刀具寿命、磨损及截割效率的影响,探究碟盘刀具截割煤岩的温度及磨损分布规律,揭示碟盘刀具截割煤岩的产热机制与磨损特性,在无振动和轴向激励振动截割条件下,通过摩擦做功分别确立了刀具楔面和刀刃的热流密度计算关系式,基于瞬时点热源情况下半无限体传热模型和热补偿原理,给出了碟盘刀具楔面不规则面热源和刀刃线热源的传热模型,建立了任意一点的温度数学模型,解算分析相关参数对刀具温度场影响,利用有限元ABAQUS和离散元EDEM软件,模拟不同进给速度下碟盘刀具截割煤岩的温度场及磨损特性,搭建碟盘刀具振动截割煤岩的实验系统,测试碟盘刀具破碎煤岩的温度特征,综合理论、模拟和实验探究碟盘刀具温度与磨损行为特征及分布规律。结果表明:碟盘刀具温度变化特征主要集中在刀刃上,从刀刃向楔面逐渐递减,沿碟盘刀具圆周温度呈类抛物线分布,温度从中间刀刃向两侧逐渐减小;不同进给速度下,无振动和轴向激励振动理论计算(截割时间趋于无穷大)获得的稳态平均最高温度分别为374.76和245.72 ℃,模拟获得的(截割时长3 s左右)平均最高温度分别为80.13和73.60 ℃,无振动的平均最高温度高于振动8.87%,实验获得的(截割时长3 s左右)分别为72.56和66.99 ℃,无振动的平均最高温度高于振动8.45%,模拟和实验的平均误差为11.69%;碟盘刀具截割煤岩实验过程中刀具出现的周向自旋现象利于其均匀磨损,振动截割相对于无振动更为明显;碟盘刀具刀刃温度耗散呈现非线性下降趋势,从刀刃向楔面快速传递,其结构形式可避免因温度累积集中而加剧刀具局部磨损;碟盘刀具磨损集中在刀刃处,圆周相对磨损量呈类抛物线分布,中间刀刃相对磨损量较大,两侧刀刃相对磨损量逐渐减小,ABAQUS模拟结合刀具磨损模型估算刀刃相对磨损量特征规律与EDEM模拟给出的相同;碟盘刀具圆周相对磨损量与温度特征规律相吻合,相关性系数均高于0.90,截割温度能够表征刀具磨损情况。综合理论、模拟和实验获得了碟盘刀具截割煤岩的温度分布特性与磨损规律的内在关联,3者温度变化规律具有一致性,验证了刀具传热模型的准确性和有效性。

     

    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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