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.

基于废旧镁碳砖的转炉热态修补料的研制与应用

为了回收再利用废旧镁碳砖,进一步提高耐火资源的利用率和附加值,以废旧镁碳砖颗粒、MS95烧结镁砂细粉、改性沥青为主要原料制备转炉热态修补料,分别研究了改性沥青(加入质量分数7%~21%)、Al粉(1%、2%和3%)和Al+B_4C复合粉(Al粉加入质量分数分别为1%、2%和3%,B_4C粉加入质量分数为0.5%)加入量对转炉热态修补料性能的影响,并选择最佳配方,进行了工业试验。结果表明:1)单独引入改性沥青19%(w)作为结合剂时,转炉热态修补料的铺展性能和强度均较好;2)同时添加3%(w)的Al粉和0.5%(w)的B_4C粉,与单一使用Al粉作为添加剂相比,可以显著提高试样的耐压强度和抗氧化性;3)以废旧镁碳砖为主要原料生产的转炉热态修补料具有铺展性好,补炉附着性强,烧结速度快,使用寿命长的优点,能满足转炉补炉要求,且优于现场使用的修补料。