Characteristics of shear stress based on magnetorheological fluid flexible fixture during milling of the thin-walled part

With light weight and good overall structure, thin-walled part has been widely used in various fields like aerospace. However, it has low stiffness in the cutting process. Traditional fixture clamping workpiece has a long positioning and adjustment cycle and is likely to deform, making it difficult to control machining efficiency and quality. In this study, a mechanical-magnetorheological fluid (MRF) composite flexible clamping method was proposed, and a theoretical mathematical model of the shear stress of MRF was constructed. The real value and the theoretical value of shear stress show consistent upward and downward trends. Based on the prediction model, the coupling relations between magnetic field intensity and thickness and position of workpiece were studied. Results demonstrate that workpiece thickness has less significant influence on shear stress compared with workpiece position. Combined with the experimental results, the smaller the workpiece thickness and the closer to the magnetic field, the larger the shear stress. The shear stress of the workpiece 1 mm thick is 21.5% higher than that of the workpiece with the thickness of 8 mm at position of 10 mm. Finally, the thin-walled part was used to demonstrate MRF clamping. Compared with the traditional clamping method, the proposed method can decrease the cutting force by 14.3%. Moreover, the residual stress sigma(x)and sigma(y)decrease by 37.0% and 43.9%,the flatness value decreases by 55.6%, and the roughnessR(a),R(z)andR(q)decrease by 55.6%, 53.2%, and 56.7%. The quality of the thin-walled part was effectively controlled.