Abstract:  Weak stiffness components were sensitive to the stress, and it was hard to guarantee the flatness after machining. To solve this problem, A MRF process was proposed to improve the flatness. The deformation mechanism of the components was clarified, and the residual stress relaxation was considered as the main cause of the deformations, which was predicted by an established model. The simulation results show that the deformations are about 9.5 μm by single-side machining, while the deformations are about 0.7 μm by turning over machining. Thus, the machining strategy by turning over was proposed based on the simulation deformation results. Experiments were conducted to verify the simulation. The results reveal that serious deformations happen by single-side machining, while the deformations recover by turning over machining, and the flatness converged efficiently. By the turning over machining strategy, the flatness peak and valley(PV)  value reduce from 4.6 μm and 5.9 μm to 2.0 μm respectively on a 200×2 mm weak stiffness flat component of copper. 

Key words: weak stiffness component, magnetorheological finishing（MRF）, residual stress, flatness

摘要： 弱刚性平面构件对应力极其敏感，加工后平面度难以保证，为解决该问题，提出通过磁流变抛光工艺改善工件的平面度。通过有限元仿真，阐明弱刚性构件磁流变抛光变形的机理，提出残余应力的不对称释放是造成工件变形的主要原因，并建立加工过程中工件变形预测模型。仿真结果表明，采用单面加工时，变形为9.5 μm；采用翻面加工时，变形为0.7 μm。根据仿真中工件变形的情况，提出了翻面加工的策略，并通过实验进行验证。实验结果表明，单面加工时，工件变形严重，而采用翻面加工时，变形会产生回复现象，从而使得工件平面度得到有效收敛。进而，提出了弱刚性构件磁流变修形抑制技术，即通过翻面等量材料去除实现工件表面残余应力的对称释放，并在200 mm、厚2 mm的纯铜弱刚性平面构件上应用该技术，两个面的平面度PV值分别从4.6 μm和5.9 μm降低到2.0 μm。

关键词: 弱刚性平面构件, 磁流变抛光, 残余应力, 平面度