夹矸煤层条件下螺旋叶片磨损失效数值模拟研究

以MG400/951-WD新型采煤机螺旋滚筒为工程对象，利用Pro/Engineer分别建立螺旋滚筒与含夹矸煤岩的三维实体模型，并将耦合模型导入到ANSYS软件中进行相关的前处理设置。分别设置齿尖合金头、齿体、筒毂和螺旋叶片的密度、弹性模量、泊松比、抗压强度、抗拉强度等材料属性;以杨村煤矿含夹矸煤层为取样对象，通过试验分别测得了煤和夹矸的密度、弹性模量、泊松比、黏聚力、内摩擦角、抗拉强度和坚固性系数等物理、力学性质，完成对耦合模型材料属性的设置。分别定义含夹矸煤岩和螺旋叶片的本构模型为096_BRITTLE_DAMAGE和003_PLASTIC_KINEMATIC，通过关键字ADD_EROSION分别对含夹矸煤岩与螺旋叶片定义失效，用以表征煤颗粒被截落与螺旋叶片的磨损;基于实际工况，定义采煤机牵引速度为8 m/min，螺旋滚筒转速为60 r/min的初始运动状态，通过关键字DATABASE_RCFORC设置求解结果的输出，将最终的K文件导入LS-DYNA/SOLVER求解器进行求解。通过显示动力学仿真求解得到了螺旋叶片的磨损域、应力云图、工作载荷谱及总磨损体积等，结果表明:螺旋叶片的磨损主要集中在叶片的尾端及外缘部分，且叶片尾端磨损最为严重，这与实际工况下叶片的磨损情况相一致。这主要是由于堆积于叶片尾端的煤堆在被叶片推挤时，会产生较大的摩擦力，磨屑脱落产生犁沟状磨损带;同时螺旋滚筒截割过程中产生的非线性冲击载荷会使其产生较大的振动，导致齿座下端的叶片外缘部分与含夹矸煤岩发生接触，造成部分附加磨损。提取不同时刻螺旋叶片的磨损体积并利用Matlab软件拟合得到了螺旋叶片磨损体积的变化趋势，发现螺旋叶片的磨损量随工作时间逐渐增大，但磨损速率随工作时间逐渐减小，这主要是磨损表面微观轮廓不断变化引起的，与不同时刻磨损域的扩展情况相一致。利用Matlab软件对螺旋叶片的磨损轨迹进行拟合，获得了螺旋叶片的磨损轨迹方程。

Numerical simulation study on wear failure of helical blade in coal seam with dirt band

In terms of the spiral drum of new MG400/951-WD shearer,the 3D entity models were established for the spiral drum and coal rock with dirt band using the Pro/Engineer.Then the coupling model was imported into ANSYS software for pre-processing.Material properties such as density,elastic modulus,Poisson’s ratio,com-pressive strength and tensile strength of the tooth tip alloy head,the matrix,the hub and the helical blade were set respectively.The physical and mechanical properties such as density,elastic modulus,Poisson’s ratio,cohesion,internal friction angle,tensile strength and Protodyakonov’s coefficient of coal and dirt sand were measured by experiments on the coal seam with dirt band in the Yangcun coal mine,so as to set the material properties of coupling models.Constitutive models of the coal rock with dirt band and the helical blade were defined as 096_BRITTLE_DAMAGE and 003_PLASTIC_KINEMATIC,respectively.The interception of coal particles and the wear of the helical blade were characterized through defining the failure of the coal rock with dirt band and the helical blade with ADD_EROSION.Based on the actual working conditions,the initial movement state of the shearer was defined at a 8 m/min of shearer advanced speed and a 60 r/min of shearer drum rotation speed.The output of the solution was set with DATABASE_RCFORC,and the final K file was imported into LS-DYNA/SOLVER for a solution.The wear domain,the stress nephogram,the working load spectrum and total wear volume of the helical blade were obtained through exhibiting the dynamics simulation for a solution,showing that the wear of the helical blade was found at the tail end and the outer edge of the blade.The most severe wear was at the tail end of the blade,being consistent with the wear of the blade in the actual condition.It’s because a furrow wear land would be caused by wear debris falling off due to large friction resulted from the coal pile stacking at the tail end of the blade being pushed by the blade.Moreover,nonlinear impact loads generated in the cutting process of the helical drum would lead to large vibration,which brought about the outer edge of the blade at the lower end of the tooth holder being contact with the coal rock with dirt band,forming additional wears.Variation trends of the wear volume of the helical blade were obtained with Matlab after extracting the wear volume of the helical blade at different times,which found that the wear of the helical blade was increased with the working time,while the wear rate decreased with the working time.It’s caused by constant changes in the microscopic profile of the wear surface,which was consistent with the expanding wear domain at different times.The wear track of the helical blade was matched with Matlab to obtain the wear track equation of the helical blade.