Machinability and cutting force modeling of 7055 aluminum alloy with wide temperature range based on dry cutting

摘要

The machinability of 7055 aluminum alloy with wide temperature range is examined, with focus on the three cutting forces, surface quality and work hardening of the material under low, medium, and high temperatures. The results demonstrate that, under low temperature, the work hardening depth of 7055 aluminum alloy is almost insensitive to the cutting speed, whereas at a higher cutting speed, the work hardening degree of the material first decreases and then increases; both the work hardening degree and hardening depth are significantly positively correlative to the cutting depth: the work hardening degree is positively correlative, though not so significantly, to the feed rate, while the work hardening depth is insensitive to the feed rate and remains at 100 mu m in all cases. Under high temperature, the work hardening degree of 7055 aluminum alloy is positively correlative to the cutting speed; at depths smaller than 80 mu m below the machined surface, the work hardening degree is negatively correlative to the cutting depth; at depths larger than 80 mu m below the cutting surface, the work hardening degree of the material becomes significantly positively correlative to the cutting depth. A mathematical model of three cutting forces in dry cutting with wide temperature range is established based on wide temperature-range dynamic impact experimental results and the orthogonal cutting model, and modified using the LMSE (least mean square error) principle. The errors between the predicted and experimental three cutting forces, after modification, are all smaller than 10%, which is within the permissible limit of error. This verifies that the modified three cutting force prediction model can predict cutting forces accurately.