セミドライによる高速深穴加工条件の最適化

抄録

For ISO 14001 compliance, there is a growing need to shift from machining with water-based coolants to dry or semi-dry machining. In the drilling of oil holes in engines, shifting to semi-dry machining is also necessary from the standpoints of energy conservation and zero emissions. Engine oil holes have to be drilled at a low cutting efficiency to avoid drill break due to the great depth and small diameter of the holes, so the cycle time is extremely long. The present study, which applied quality engineering to find optimum conditions for high-speed semi-dry drilling of deep holes, addressed an urgent need to improve the efficiency of a drilling process that had been converted to semi-dry machining. Based on the energy evaluation concept, this study measured electric power consumption and the weight of the material removed. Since the experiment itself was carried out by drilling deep holes with high efficiency, it was anticipated that many drills would break, and in fact they did, so the experimental data were analyzed by the pass/fail method as well as by evaluating weight of material removed and electric power consumption, and the results were compared. The optimum conditions obtained from both types of analysis were practically the same. Semi-dry drilling under the optimum conditions produced various economic benefits, including an energy saving effect and a zero-emission effect.