摘要
数控机床在整个加工空间中的不同位姿下,其运动精度的变化对机床的工作精度与效率的提高有着重要影响。定义运动精度稳定性,并提出利用闭环传递函数的灵敏度研究数控机床运动精度稳定性的方法。建立双惯量进给系统模型,针对解析求解的复杂性,使用渐近线近似法求取闭环传递函数关于传动刚度的灵敏度函数,揭示半闭环/全闭环下灵敏度函数的显著不同;在此基础上,根据典型运动误差相关指令的频谱分布特点,分析传动刚度变化对稳态跟随误差、准停过程振动超调量、圆运动半径误差的影响规律。发现其中指令频宽与控制带宽的比值为主导因素,即仅当指令频宽接近控制带宽时才有显著影响,其他重要的影响因素为控制结构(半闭环/全闭环)和控制带宽与机械共振频率的比值;以系列仿真验证了上述影响规律。
The fluctuation of CNC machine’s dynamic accuracy, due to different configurations in whole work space, have great effects on the improvements of working accuracy and effectiveness. The concept of dynamic accuracy consistency is defined, and a method using sensitivity of close loop transfer function to study it is presented. A two-mass mechanical model is constructed and an asymptote approximation approach is presented to avoid analytical difficulties. The obtained sensitivity functions show significant differences of semi close loop and close loop control. On this basis, spectrum features of commands relate to typical dynamic errors are studied and used to find the effects of transmission stiffness variations on the change of tracking error, residue vibration overshoot, and circular radius error. It’s concluded that the main factor in the effects is ratio of command frequency spectrum width to close loop band width, i.e. there’s significant change only when the two are close. Other main factors are control structure （semi close loop or close loop）, and the ratio of close loop band width to mechanical resonance frequency. A series of simulation experiments verified the achieved conclusion.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2014年第23期128-133,共6页
Journal of Mechanical Engineering
基金
国家重点基础研究发展计划(973计划
2009CB724407)
国家自然科学基金(51235009)资助项目
关键词
数控机床
进给系统
传动刚度变化
运动精度稳定性
CNC machine
feed drive systems
transmission stiffness variations
dynamic accuracy consistency
