SiCp/Al复合材料高速切削去除机理及表面质量研究

High-speed Cutting Removal Mechanism and Surface Quality of SiCp/Al Composites

目的探究高速加工下SiCp/2024Al复合材料切屑形成机理及加工表面质量情况,为改善该材料加工性能提供理论依据。方法设计高速正交铣削实验,对SiCp/2024Al复合材料进行不同切削速度下的高速加工,并通过对切屑形态、切削力、切削能耗、加工表面形貌及加工硬化情况进行分析,探明高速加工下材料去除机理及加工表面质量变化。结果在较低速度下复合材料的切屑形成过程为第一变形区的剪切变形和SiC颗粒破碎,切屑形态为锯齿状;切削速度在300~800 m/min时,随着速度的提高复合材料切屑连续性下降,切削速度在1000 m/min时,复合材料韧脆性能发生转变,切屑呈现崩碎状;切削力在切削速度300~1000 m/min时,随速度提高明显减小,主切削力由300 m/min时的320 N左右下降至1000 m/min时的180 N左右,切削能耗显著降低;失效的SiC颗粒破坏加工表面质量,而高速加工对表面质量有一定改善,切削速度由300 m/min提高到1000 m/min时,表面粗糙度由0.68μm下降至0.47μm,加工硬化深度也随切削速度提高而减小。结论在一定条件下,高速加工有助于改善SiCp/2024Al复合材料的加工性能,其动态力学性能将发生变化,切削力和切削能耗下降,加工表面变形程度降低、质量提高。

SiCp/2024Al composites,which are particle-reinforced aluminum matrix composites,have the advantages of high specific strength and specific module,high hardness,excellent wear and corrosion resistance,etc.,and have a broad application prospect in the aerospace field,but they also have issues such as serious tool wear and poor surface quality in their machining due to the hard particle-reinforced phase,making them difficult to machine,whereas high-speed machining,as an advanced manufacturing technology,is a highly advantageous technical means for the machining of difficult-to-machine materials in addition to high machining efficiency and precision.Therefore,high-speed orthogonal milling experiments were conducted in this paper for 45%volume fraction SiCp/2024Al composites to compare their machinability over a wide range of cutting speeds and to analyze their chip formation mechanism and machined surface quality under high-speed machining.High-speed orthogonal milling experiments on flake SiCp/2024Al composites were conducted by controlling the cutting speed in the speed range of 300-1000 m/min.In the experiments,the cutting edge of the insert was made parallel to the spindle direction,and the width of the cutting edge was ensured to be larger than the thickness of the workpiece.The chip morphology,cutting force,cutting energy consumption,machined surface morphology and machining hardening were collected and monitored to investigate the material removal mechanism and machining surface quality changes under high-speed machining in order to analyze the high-speed machinability of SiCp/2024Al composites.The experimental results show that the chip formation process of composites at lower cutting speeds consists of shear deformation and SiC particle fragmentation in the primary deformation zone,and the chip morphology is serrated.In the cutting speed range of 300-800 m/min,the chip continuity of composites decreased as the speed increased,and the composites underwent a ductile-to-brittle transition at 1000 m/min,and the chips gradually appeared to be fragmented.The cutting force in the cutting speed range of 300-1000 m/min decreased significantly as cutting speed increased,and the main cutting force decreased from about 320 N at 300 m/min to about 180 N at 1000 m/min,and the cutting energy consumption also decreases significantly with the increase of cutting speed,the cutting energy consumption decreases from 1.07 GJ/m3 at 300 m/min to 0.62 GJ/m3 at 1000 m/min.The failed SiC particles damaged the machined surface,while the high-speed machining improved the surface quality.With a cutting speed of 300-1000 m/min,the surface roughness decreases from 0.68μm to 0.47μm,and the machining hardening depth also decreases with the increase of cutting speed.High cutting speed corresponds to higher strain rate,summarize the above findings,the dynamic mechanical behavior of the composites changes under high-speed machining,and the material undergoes a ductile-to-brittle transition,which affects the degree of deformation of the removed layer material and the machined surface,resulting in a decrease in chip continuity,increased brittleness,and the cutting force and cutting energy consumption decrease.The deformation of the machined surface decreases,and the surface quality improves,so high-speed machining under certain conditions can help improve the machinability of SiCp/2024Al composites.