深孔贫油变刚度/阻尼钻削系统的调控策略及排屑机制研究

MQL deep-hole drilling is one of the most value-adding manufacturing processes, but the challenges in practical drilling process, such as the real-time controllability of chip-removal state and the tool dynamic behaviors , have severely restricted the popularization application of MQL deep-hole drilling yet. On the basis of the working mechanism of explored vibration suppression structure, this project will focus on the control strategies of drilling tool vibration using variable stiffness or damping and chip-removal mechanism. In order to improve the quality of machined hole, the partitioning problem of the fuzzy-input space of vibration mode is converted into the initial-value problem of the input space, and an intelligent recognition method is proposed to identify the quality of machined hole accurately. By introducing the mode filtering technology, the active control equation of drilling tool vibration is built in independent modal space, and simultaneously, the objective function of performance and the optimizing form of control variable are determined in the control rule of drilling tool vibration according to the optimal control theory. Furthermore, the hydrodynamic characteristics of air/oil mist, such as mean pressure drop, transient pressure surge and temperature, are found in chip-removal process, and then a novel impulse chip-removal system is designed so as to regulate the chip-removal state and temperature in cutting area easily. Finally, the optimal coupling relationship and matching or selecting rules of the machining quality, cutting parameters and the structural features parameters of drilling tool system are discovered, as well as the control strategies of the hole quality are obtained. To sum up, the relevant research findings in this project will lay the theoretical and application foundations for developing MQL deep hole drilling.

深孔贫油钻削是一种极具附加价值的切削工艺，但实际加工中刀具振动及排屑状态的实时调控性差，已严重制约了该工艺的普及应用。本项目在已探明的振动抑制构型工作机理的基础上，研究深孔贫油变刚度/阻尼钻削系统的调控策略及排屑机制问题。以加工孔品质的精确控制为目标，将刀具振动模式的模糊输入空间划分问题转化为初始输入空间的初值问题，提出以振动时频信息为输入特征的加工品质智能辨识方法；通过引入模态滤波技术，构建刀具振动独立模态空间的主动控制模型，并基于最优控制理论确定刀具振动控制律中目标性能函数及控制量的优化形式；发现不同排屑状态下切削气/液雾体的压力衰减、瞬时波动及温度的变化特征，提出一种新的可实时调控排屑状态和切削区域温度的脉冲式排屑系统设计方法；探明加工品质与切削工艺参数、刀具系统结构特征参数的最佳耦合关系及其匹配选择准则，进而形成精确控制加工品质的策略，为发展深孔贫油钻削技术奠定理论及应用基础。

深孔贫油钻削是一种极具附加价值的切削工艺，但实际加工中刀具振动及排屑状态的实时调控性差，已严重制约了该工艺的普及应用。本项目在已探明的振动抑制构型工作机理的基础上，研究了深孔贫油钻削变刚度/阻尼刀具系统的调控策略及排屑机制问题。以加工孔品质的精确控制为目标，将振动模式的模糊输入空间划分问题转化为初始输入空间的初值问题，提出以振动时频信息为输入特征的加工品质智能辨识方法；以深孔切削热的形成机理为基础，提出了一种基于深孔制件局部温度信息来反演追踪切削热通量时空分布的方法。同时，结合Navier-Stokes对流传热方程，获得了在一个完整脉冲激励周期内切削液流场动态速度分布的演化规律，探明了脉冲式切削液流体力的幅值与频率对切削区域的温度分布及冷却效率的影响机制；运用矩阵传递函数方法，使得变刚度/阻尼辅助支撑、授油器及刀具结构等局部关键设计参数融入进深孔刀具系统动力学方程。结合切削稳定性判据，研究了深孔钻削刀具系统的稳定性与加工转速、钻削深度及施加的励磁电流之间的关联关系；将刀具在物理空间的振动信息转入到模态空间，构建了独立模态空间的深孔刀具系统状态控制方程，避免了传统物理空间所需控制参量多且相互耦合的缺陷。采用最优模态性能指标锁定要摧毁或抑制的模态参数，并结合Luenberger模态状态观测器，将刀具振动的模态位移和模态加速度信息引入到极点配置修正后的反馈增益矩阵中，计算获得了对目标振动模态“精确打击”的实际制振控制力。这些为发展深孔贫油钻削技术奠定理论及应用基础。