| 摘要 |
PURPOSE:To detect the anomaly of a tool by detecting the cutting-force variation pattern of a multiblade tool and calculating the self correlation coefficient from the cutting-force variation pattern and the delay pattern obtained by delaying the above-described variation pattern by a prescribed cycle and comparing said self correlation coefficient with a threshold value. CONSTITUTION:The variation of the cutting force of a milling cutter 13 is transmitted as the variation in the thrust direction onto a main shaft 15 and converted to a voltage by a thrust sensor 18. In a multiplication circuit 25, a signal x(t) and a delaying signal x(t-tau) are multiplied, and the result values are averaged in each prescribed cycle tau of a calculation circuit 24 in an averaging circuit 26, and outputted as self correlation coefficient. Then, said value is outputted as the self correlation coefficient R(tau) normallized in a division circuit 29. The result value is input into a comparator 30 and compared with the previously set threshold value A inputted from a control 31, and when the value is larger than a, it is confirmed as normal, and when the value is smaller than A, an anomaly signal 32 is inputted into an NC controller 12, and the feed of the milling cutter is suspended, and an operator is informed of the anomaly. |
