碳化硅装甲陶瓷的磨削钻孔及机理

碳化硅陶瓷因其高硬度和高脆性,孔加工异常困难。分析了碳化硅装甲陶瓷材料去除时的临界切削厚度以及其对金刚石强研磨性的磨削特性,研制了不同胎体性能的烧结金刚石薄壁钻头以及不同结构的钎焊、电镀钻头,对碳化硅陶瓷进行了磨削钻孔实验。分析了轴向压力及主轴转速对加工效率的影响和碳化硅陶瓷的磨削钻孔机理。结果表明:烧结金刚石钻头容易钝化、打滑,加工效率低;钎焊钻头磨损严重;电镀薄壁钻头的加工效率最高,钻头寿命最长,孔加工质量最好,但轴向压力不宜超过800N,主轴转速不宜超过2600r/min。脆性断裂去除是碳化硅陶瓷材料的主要去除方式,磨削表面同时具有脆性断裂和塑性流动的特征。采用双面加工工艺,避免孔出口的崩豁,改善了孔的加工质量。

Analysis and optimization of drilling parameters for tool wear and hole dimensional accuracy in B_4C reinforced Al-alloy

Cutting parameters were evaluated and optimized based on multiple performance characteristics including tool wear and size error of drilled hole. Taguchi＇s L27, 3-level, 4-factor orthogonal array was used for the tests. It is shown that generally abrasive wear and built up edge （BUE） formation were seen in the tool wear, and the comer wear was also of major importance. Flank wear of the cutting tool was found to be mostly dependent upon particle mass fraction, followed by feed rate, drill hardness and spindle speed, respectively. Among the tools used, TiAlN coated carbide drills showed the best performance with regard to the tool wear as well as hole size. Grey relational analysis indicated that drill material was the more influential parameter than feed rate and spindle speed. The results revealed that optimal combination of the drilling parameters could be used to obtain both minimum tool wear and diametral error.