サーメット工具の耐欠損性に関する研究(第2報) : 刃先温度とすくい面負荷が工具欠損に及ぼす影響

概要

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Fracture mechanism of TiC simple carbide type cermet tool in intermittent cutting has been studied with regard to cutting edge temperature and cut-ting force. Machining tests were conducted on a lathe by cutting steel bar having narrow slots. Cutting speed was varied from l.25m/s to 4.17m/s and feed rate from O.2mm/rev to O.4mm/rev, whereas depth of cut was maintained constant (1.5mm) throughout the tests. Cumulative failure probability was determined at each cutting condition. Tool life at 5096 reliability decreases at low cutting speed and at high cutting speed together with high feed rate. Early failure increases due to brittleness of the material at the former and due to plastic deformation of the cutting edge at the latter. Fracture mechanism of a cutting edge varies according to the temperature at a depth of O.2mm beneath tool face (Ps). When the temperature at P, remains below specific temperature (Tc), the cutting edge fails through brittle fracture, but when the temperature becomes higher than Tc, a parallel crack is formed and gradually propagates under the tool face, and finally fast failure breaks the cutting edge. This specific temperatute Tc was found to be about 1070 K.
公益社団法人精密工学会の論文
1983-04-05