发电柴油机曲轴断裂案例的分析与教训

介绍某航运公司发电柴油机曲轴断裂的几个案例,对其产生的原因进行分析,并对修理工艺作较深入的探讨和评价,以从中吸取应有的教训。     

曲柄摇杆机构及其演化机构的γmin发生位置的探讨

曲柄摇杆机构及其演化机构被广泛地应用于生产,为了保证机构的传动性能良好,设计时必须确定最小传动角的下限,使得γmin≥[γ].文中根据曲柄摇杆机构及其演化机构杆长间的关系,用几何方法推导出了γmin的准确发生位置.     

A method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed presses

A new method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed mechanical presses was put forward. By analyzing the kinematic characteristics of a center-located slider-crank mechanism whose crank rotates at a constant angular velocity, the kinematic parameters of the slide, connecting rod and crank were formulated approximately. On the basis of the results above, three inertia forces and the input moment in the mechanism during its idle running were investigated and formulated by dynamic analysis. A verification experiment was performed on a slider-crank mechanism at a high-speed press machine. The forces derived from the established formulas were compared respectively with those obtained by the ADAMS software and the classical method of connecting rod mass substitution. It was experimentally found that the proposed formulas have an improved performance over related earlier techniques. By use of these results, a 1000 kN 1250 rpm four-point high-speed press machine was designed and manufactured. The slide of this press is driven by four sets of slider-crank mechanisms with symmetrical layout and opposite rotation directions to counterbalance the horizontal inertia forces. Four eccentric counterbalance blocks were designed to counterbalance the vertical force after their mass and equivalent eccentric radius were formulated. The high-speed press machine designed by the proposed counterbalance method has worked with satisfactory performance and good dynamic balance for more than four years in practical production.     

基于UG、ANSYS和ADAMS的联合仿真研究

论述了三维实体建模软件UG、有限元分析软件ANSYS和机械系统多体动力学分析软件ADAMS联合仿真的实现方法;以曲柄连杆机构的刚柔耦合模型的动力学分析为例,验证了联合仿真方法的可行性及效果。     

船舶总体弯曲变形对纵向布置曲柄摇杆机构极限摆角和最小传动角的影响

分析了船舶总体弯曲变形对沿船体纵向布置曲柄摇杆机构的机架尺寸所造成的伸长和缩减,并在深入研究机架尺寸缩减对曲柄摇杆机构极限摆角和最小传动角影响的基础上,提出了适用于沿船体纵向布置曲柄摇杆机构极限摆角和最小传动角的一组计算公式,最后以实例计算验证了船舶总体弯曲变形对曲柄摇杆机构极限摆角和最小传动角的影响程度。     

奔驰E320轿车雨刮器结构原理分析

对奔驰Ｅ３２０轿车雨刮器进行了运动分析、在雨刮器传动机构设计中,利用交叉连杆机构能解决雨刮器往复运动中摆角的设计问题,利用曲柄连杆机构呆实现在不增大雨刮器尺寸的前提下增大雨刮器擦拭视角。     

A Crank-Nicolson Difference Scheme for Generalized Rosenau Equation

Much effort has been devoted to researching the common Rosenau equation,but the numerical method of it has not been studied.In this paper,a conservative Crank-Nicolson difference scheme for an initial-boundary value problem of the generalized Rosenau equation is proposed.Existence and uniqueness of numerical solutions are derived.By method of discrete energy,the second order convergence and stability are discussed.Numerical examples demonstrate the theoretical results.     

具有匀速往复运动和急回特性的非圆齿轮-曲柄滑块机构的设计

非圆齿轮与曲柄滑块机构组合可以得到具有匀速往复运动和急回特性的滑块运动,有很大的实用价值。该文介绍了这类机构的设计方法。