High Speed Cutting Behavior Research Of AZ31 Magnesium Alloy

Magnesium alloy has many excellent physical and mechanical properties, such as lower density, high specific strength, and it is widely applied in the field of aerospace, communications and weapons. The low slip system, high thermal conductivity and the poor plastic deformation ability at room temperature will have an important influence on the behavior of the magnesium alloy in the high speed cutting process. In this paper, the influence factors and mechanism of magnesium alloy cutting behavior are studied, and the experimental research and theoretical analysis are carried out. AZ31 magnesium alloy as experimental materials in this paper, the influence of cutting parameters on cutting force, cutting chip morphology and surface processing quality were analyzed, and explored the magnesium alloy chip formation mechanism. Finally, the model roughness was established based on the Tipnis rough degree model, combining with the experimental data of this paper. The important conclusions can be concluded as follows:1) When the cutting speed increases from 2000 r/min to 4400 r/min, the cutting force of X and Z increase first and then decrease, reaching the peak value when the cutting speed is 2600 r/min. When the cutting speed is more than 3800 r/min, the cutting force of Y increases. When the cutting feed rate increases from 0.03 mm/r to 0.11 mm/r, the three direction cutting force all increase, and the the cutting force of Z increases by 110%, the cutting force of Y increases by 80%, the cutting force of X increases by 30%. When the cutting depth increases from 0.5 mm to 2.5 mm, the three direction cutting forces are all in an increasing trend, the cutting force of X increases by 23%, the cutting force of Y increases by 27%, and the cutting force of Z increases by 21%.2) When the cutting speed increases from 2000 r/min to 4400 r/min, the degree of tooth increases by 70%, and the tooth pitch decreases first and then increases, while the chip surface begins to fold, also happens second shear. When the cutting feed rate increases from 0.03mm/r to 0.11mm/r, the degree of tooth increases by 81%, and the tooth pitch increases by 58%, fracture and dislocation occurres on the tooth surface. When the cutting depth increases from 0.5mm to 2.5mm, the degree of tooth increases by 32%, and the tooth pitch increases by 33%, micro cracks and fracture occurres in the tooth surface.3) When cutting speed increases from 1000 r/min to 2200 r/min, the surface rough decreased 23%, the metamorphic layer decreases 29%, the hardened layer decreases by 68?m. When the cutting feed rate increases from 0.03mm/z to increase 0.11mm/z, the metamorphic layer increases by 34%, the hardened layer depth increases by 40?m, the roughness increases by 56%. When the cutting depth increases from 0.5mm to 2 mm, the metamorphic layer increases by 24%, the hardened layer increases by 36?m and roughness increases by 36%.4) Based on Tipnis rough model and the orthogonal experiment, the roughness prediction model is established and it is Ra=103.01924V-0.5197?p0.0941f0.1465. It is found that the error were within 10%, comparing the theoretical predictions value and between the actual measured values. In addition, the model was proofed by strict mathematical test,showing that cutting speed, cutting depth and cutting feed rate have significant impact on surface roughness.