数控机床传动机构精度可靠性优化研究

Optimization of precision reliability for the transmission mechanism of NC machine

针对数控机床误差溯源不充分导致精度低、可靠性差等问题,对数控机床误差建模、精度可靠性分析、精度优化设计等方面进行了研究。基于多体系统理论建立了数控机床空间几何误差模型,分别对数控机床各方向传动机构进行了结构分析,建立了多层映射误差传递模型;基于数控机床传动机构精度可靠性函数,应用一次二阶矩法对含混合不确定性的数控机床传动机构开展了精度可靠性分析;以可靠性分析结果作为精度性能判断标准,结合灵敏度分析结果,建立了以制造成本最低为优化目标、满足精度要求为约束的精度分配优化模型,并利用遗传算法和蒙特卡洛法进行了数控机床传动机构的精度分配优化。研究结果表明:经过精度分配优化后,某数控机床传动机构精度可靠性由96. 89%提高到99. 87%,制造成本降低34. 74%。

Aiming at the problems of low precision,poor reliability caused by inadequate error tracing of the transmission mechanism of NC machine,the error modeling,precision reliability analysis and precision reliabilityof NC machine were researched. The space geometric error model of NC machine was established based on the multi-body system theory,through structure tracing of the transmission mechanism,the multi-layer mapping error transfer model of transmission mechanism was established. Based on the precision reliability function of the transmission mechanism of NC machine,the precision reliability analysis of mixed uncertain of the transmission mechanism of NC machine was carried out via the first order two order moment method（ FOSM）. The reliability analysis result which was used as the standard of precision performance judgment,combined with the results of sensitivity analysis,the optimization model of precision distribution was established,which takes the lowest manufacturing cost as the optimization goal and satisfies the requirement of precision as the constraint. The genetic algorithm and Monte Carlo method were used to optimize the precision distribution of the transmission mechanism of NC machine. The results indicate that,after precision distribution optimization,the precision of transmission mechanism of NC machine is optimized from 96. 89% to99. 87%,and the manufacturing cost is reduced by 34. 74%.