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为了降低高速吹瓶机中凸轮机构带动的模具合模时出现的接触力,提出了基于机构动力学-控制系统协同仿真和优化的凸轮廓线优化设计方法。首先,建立吹瓶机模具运动控制系统模型,目标函数是在最大接触力约束下运动时间最短。其次,根据赫兹接触理论中接触力与变形量的关系,引入位移状态变量,将高速无冲击凸轮廓线设计问题转化为位移无超调的最速控制问题。通过机构动力学与控制系统协同仿真与优化,获得无超调约束下运动时间最短的控制系统参数和运动速度,并通过调整位移偏置量来实现接触力控制。最后,将最优运动曲线转化为凸轮曲线。仿真结果表明,新设计的凸轮曲线可以在更高速度时保持软着陆,有效降低了振动冲击,疲劳寿命达到1.4×107次。
In order to reduce the contact force of the mold driven by the cam mechanism in the high speed blow molding machine, a method of cam profile optimization based on the co-simulation and optimization of the mechanism dynamics control system is proposed. First of all, the bottle blowing machine mold motion control system model is established. The objective function is to minimize the movement time under the maximum contact force constraint. Secondly, according to the relationship between contact force and deformation in Hertzian contact theory, the displacement state variables are introduced to convert the design problem of high-impact and non-impact cam profiles into the most speed-control problem with no overshoot displacement. Through the co-simulation and optimization of mechanism dynamics and control system, the parameters and velocity of the control system with the shortest movement time under the constraint of overshoot are obtained, and the contact force control is achieved by adjusting the displacement offset. Finally, the optimal motion curve into a cam curve. The simulation results show that the newly designed cam curve can maintain a soft landing at a higher speed and effectively reduce the vibration impact with a fatigue life of 1.4 × 107 times.