基于变绳长岸桥起升耦合系统动态特性研究

Study on dynamic characteristics of lifting coupling system of quayside container crane based on variable length wire rope

以岸桥为研究对象,建立了包含变长度钢丝绳与大梁、小车滑轮组、小车和起升质量的起升耦合振动系统模型,利用Hamilton原理建立了系统纵向振动微分方程,应用有限差分法进行离散化求解。对起升过程中的起升动载系数及影响因素进行了计算和分析,得到了在梯形加速及制动时大梁和起升质量的振动响应和起升绳中动张力曲线,以及耦合系统前四阶固有频率的变化曲线。另外,对变频电机驱动下的动载特性进行了研究。研究表明:起升质量离地初速度对起升动载系数影响最大,与其呈线性递增关系;起升系统振动存在耦合一致性,振动响应在加速度变化时发生突变,最大幅值出现在起升加速阶段,重物速度降至为0后存在残余振动。起升系统频率随绳长减小而增大;相比有级调速起升重物,变频电机的无极调速起升更加平稳。额定起升加速时间与起升动载系数呈指数关系,应将其值设定在第一个拐点之后。额定起升速度与起升动载系数呈线性正比关系,且影响较小,折中设定该参数值,可保证起升效率和平稳性。

Aiming at the quayside container crane, a lifting coupled vibration system is established including variable length wire rope, girder, pulley block of trolley, trolley and lifting load. The finite difference approach is applied to discretize differential equations of longitudinal vibration of the system developed by employing the Hamilton’s principle. The dynamic lifting coefficient and its influencing factors during hoisting process are calculated and analyzed, the vibration response curves of the girder and the lifting load and the dynamic tension curves of hoisting wire rope, and the first four nature frequency curves of the coupled system are obtained duringtrapezoidal acceleration and braking. At the same time, the dynamic characteristics driven by frequency conversion motor of the system are studied. Results show that the dynamic lifting coefficient increases linearly with the initial speed of the lifting mass from the ground, which has the greatest impact. There is coupling consistency in the hoisting system, its vibration responses change abruptly when the acceleration changes, the maximum amplitude occurs in the hoisting acceleration stage, and the residual vibration exists when the lifting load speed drops to zero. The frequency of hoisting system increases with the decrease of the rope length. Compared with the lifting of the load with the step speed regulation, the stepless speed regulation lifting of the variable frequency motor is more stable. The rated lifting acceleration time has an exponential relationship with the dynamic lifting coefficient, which should be set after the first inflection point. The rated lifting speed has a linear proportional relationship with the dynamic lifting coefficient, and its influence is less. And its parameter should be set in compromise to ensure the lifting efficiency and stability.