Deformation prediction model for hollow thin-walled aluminum alloy structural parts under multiple load-sequence coupling conditions

Hollow thin-walled aluminum alloy structural parts (HTWASP) must be cut after welding during the actual processing process, and a welding stress field is inevitably generated owing to the welding heat effect in the process of welding the workpiece, leading to distortion of workpiece. To accurately and efficiently predict the deformation of HTWASP after multiprocess processing, equivalent load caused by process of welding was computed through connection inherent strain theory with welding thermal parameters. A dynamic simulation model of the milling process of HTWASP was established by welding equivalent load. The influences of spindle speed and tool diameter on the deformation remain stress of structural workpieces were analyzed. Additionally, the simulated values for the deformation of the workpiece were compared and analyzed through milling tests on these structural parts. The results showed that the range of stress values and stress effects was smaller when the spindle speed was higher. The distance of the stress effect was the smallest when machine speed was 2500 rpm and tool diameter was 20 mm. Milling stress value was the smallest when machine speed was 2500 rpm and tool diameter was 6 mm. Most of the deformation occurred in the hollow position of the upper and diagonal plate; in contrast, the distortion of vertical plate and weld seam was not significant. The minimum deformation was 0.501 mm at machine speed is 2500 rpm and tool diameter is 6 mm. In the non-high-speed cutting state, high speed reduced workpiece quality of aluminum alloy workpiece, and slot milling quality was the best when machine speed was 1000 r/min and tool diameter was 6 mm. The proposed model sequentially couples the welding and milling process loads, and a multiprocess deformation prediction model that increasingly conforms to the actual processing sequence is constructed, providing a reference for the high-precision and efficient prediction of the multiprocess deformation in hollow thin-walled structural parts.