基于在机测量的薄壁件加工综合误差建模与补偿

Comprehensive Error Modeling and Compensation in Manufacturing of Thin-Walled Parts Based on On-Machine Measurement

薄壁零件因其优异的机械性能–重量比而广泛应用于航空航天等领域。但由于刚度低,薄壁件加工时受切削力与夹紧力的影响易产生变形,从而导致较大的加工误差。采用预测力致误差的解析解和有限元等方法难以应对复杂的加工工况。为解决这一难题,提出了一种综合误差补偿方法,可预测并补偿3大主要误差源:几何误差、热误差和力致误差。首先,对机床几何误差和热误差进行建模与补偿,为在线测量提供足够的运动精度。其次,采用在机测量方法获得力致误差。通过坐标变换方法,将各误差源的补偿值转换到同一坐标系中,实现了3个误差源的综合补偿。基于数控系统的原点偏移功能,开发了一套误差实时补偿系统。应用此补偿方法对两类薄壁件加工,加工误差降低74%以上,加工效率提高41%以上,充分验证了综合误差补偿方法的有效性。

Thin-walled parts are widely used in aeronautical,aerospace and automotive applications due to their high performance-to-weight ratio.The thin walls in these parts also lead to low rigidity during machining,making them susceptible to deformation under the influence of the cutting force and/or the clamping force.As a result of spring-back effect after machining,significant machining error occurs in the thin-walled workpiece in its stress-free state.Analytical solution and FEM analysis of the deformation phenomenon are not robust against various machining conditions.To address this issue,a comprehensive error compensation scheme is proposed to predict and compensate for three major error sources,i.e.geometric error,thermal error,and force-induced error.The geometric and thermal errors of the machine tool are modeled and compensated to provide high motion precision for on-machine measurement.The force-induced error is obtained using on-machine measurement data.Comprehensive compensation of all three error sources is achieved by transforming individual compensation values into the same coordinate system.A real-time compensation system is developed based on the numerical control system of the machine tool.Compensation experiments carried out on two types of thin-walled parts show(i)a reduction of machining errors by at least 74%and(ii)an improvement of machining productivity by at least 41%,which validates the proposed compensation scheme.