整体叶轮铣削颤振在线预测和抑制的关键技术研究

Integral impellers are the key components for some equipments in aviation, aerospace fields, and their milling stability are directly related to the parts' processing quality. However, it is the key and difficult problem to assure machining stability in studying milling chatter mechanism and chatter suppression technologies. Aimed at ruled sculpture surface milling stability problems, relative chatter formation mechanism and control strategies about online prediction and suppression will be raised. At first, a sculptured surface milling dynamic model including processing path parameters will be studied, which uses differential geometry method according to the geometry relationship between the tool and workpiece. Based on the built dynamic model, coupling laws between the tool and workpiece will be studied during surface residual allowance changes with uneven curvature changes. Secondly, milling stability criterion will be put forward for integral impellers milling chatter, which is based on the obtained laws. Thirdly, to realize ruled surface's milling chatter online prediction, an intelligent expert system based on BP neural network and fuzzy control algorithm will be integrated into an open architecture CNC system, which can realize signals' online analysis. Finally, to realize chatter online suppression, the strategies including both an adaptive control algorithm for spindle speed and NURBS nano interpolation function, which can be synchronously open to compact interpolation step length with considering the requirements of both accuracy and stability, will be studied. The open architecture CNC system realization technologies will also be studied and developed, which can realize milling chatter online suppression for sculptured surface. Related research results will promote the high quality processing of integral impellers.

整体叶轮是航空、航天等领域设备的关键部件，其铣削稳定性关系零件的加工质量。而颤振机理和抑制技术研究是保证加工稳定性的关键和难点，课题拟针对直纹面叶轮铣削稳定性问题，研究其颤振的生成机理并提出在线预测和抑制的控制策略。首先，根据刀具和工件曲面铣削时的几何关系，采用微分几何方法，研究包含加工路径参数的铣削动力学模型。以建立的模型为基础，研究曲面残留余量随曲率不均匀变化对刀具和工件间的耦合规律。其次，基于获得的规律提出整体叶轮铣削颤振的稳定性判据。然后，研究在开放式数控系统中引入基于BP神经网络和模糊控制的智能专家系统，通过对采集的信号进行在线分析实现颤振在线预测的技术。最后，为了实现颤振在线抑制，研究主轴转速适应控制、并能同步开启综合考虑精度和稳定性要求的曲面NURBS纳米插补功能以密化插补步长的策略。研究曲面铣削颤振在线抑制的开放式数控系统实现技术。研究成果将促进整体叶轮的高品质加工。

整体叶轮的叶片在加工中极易产生颤振，严重影响叶片的表面加工质量，迫切需要在考虑切削力、铣削振动的动态特性和机床的动力学特性等因素的基础上，对叶轮加工颤振的产生机理及在线检测、抑制的策略进行深入研究。因此，本项目以直纹面整体叶轮铣削颤振为研究对象，研究了刀具和叶片工件铣削过程中基于NURBS连续插补的空间切屑厚度模型；研究了切屑厚度随加工参数的变化规律；研究了考虑工件几何曲率特性的动态铣削力系数模型，实现了对直纹面叶片类复杂工件铣削力的动态预测。研究了弱刚度工件条件下叶片的铣削变形规律，建立了柔性刀具条件下的动态铣削力模型，并分析了叶片压力面和吸力面铣削过程中刀具在空间中的振动特性。在此基础上，研究了基于铣削力和振动加速度信号的时域、频域铣削颤振的实时预测技术。在开放式五轴数控铣床平台上，基于耐奎斯特判据建立了主轴转速在线适应控制模型、基于Y向恒力铣削变进给速度和 NURBS 纳米插补功能策略分别实现了叶轮铣削颤振的在线抑制。本课题的立项和完成可丰富和完善复杂薄壁曲面五轴铣削颤振的形成机理及在线预测和控制的相关策略，在实际应用中有利于基于参数在线适应控制技术在五轴叶轮加工中的应用，具有较高的学术意义和应用价值，研究成果将促进整体叶轮的高品质加工。