针对采煤机摇臂在截割载荷作用下可靠性差的问题,对MG500/1180-WD采煤机摇臂动态特性进行分析。建立摇臂有限元模型,通过模态分析得到摇臂固有频率及主振型。模态分析表明,摇臂主要振动模式为电机壳体及行星头弯曲扭转振动。通过实验模态分析,以固有频率为判定指标,对有限元模型进行验证。选取电机壳体壁厚等5个设计变量,研究摇臂固有频率随设计变量的变化规律。根据重载截割实际工况对摇臂进行谐响应分析,计算摇臂振动响应。结果表明:摇臂中部老塘侧壁厚是影响摇臂固有特性的关键因素;摇臂在行星1级2倍频、直齿1级2倍频、直齿2级2倍频及8阶固频激励下动态应力较大;采煤机摇臂形成了以1、3阶振型模态振动为主要特征的弹性振动并导致摇臂铰接耳处产生应力集中;分析结果可为采煤机摇臂结构优化设计及可靠性分析提供参考。
The dynamic characteristics of MG500/1180-WD shearer’s rocker arm were studied aiming at the problem of its poor reliability under cutting loads. The simplified finite element (FE) model for the arm was established and its natural frequencies and main modal shapes were obtained with modal analysis. Modal analysis showed that the main vibration modes of the arm are bending-torsional vibration of planet head and motor shell. Through test modal analysis, taking its natural frequencies as the judgement index, the FE model was validated. Choosing 5 design variables including motor shell’s wall thickness, etc., the variation law of the arm’s natural frequencies with the design variables was studied. Harmonic response analysis for the arm was conducted under the condition of heavy cutting loads, and the vibration responses of the arm were calculated. The results showed that the thickness of old pond side wall in the middle of the arm is the key factor influencing the arm’s natural characteristics; the arm’s dynamic stresses are larger under loads with double of the planet’s 1st frequency, double of the spur gear’s 1st one, double of the spur gear’s 2nd one, and the 8th natural frequency; the arm’s elastic vibration mainly has features of its 1st and 3rd modal shapes to cause stress concentration at the arm hinge ear; the analysis results provide a reference for the optimal design and reliability analysis of a shearer’s rocker arm.