| 摘要 |
PURPOSE:To prevent wasteful consumption of energy and to collect dust efficiently by making the point of the time when the acceleration of a fan is completed and the point of the time when cutting of an ingot is started always coincident. CONSTITUTION:A subtractor 22 indicates the acceleration start point D of a fan 9 successively, and a comparator 23 monitors the arrival or non-arrival of the point D at a cutting operation start point A successively. When the point D arrives at the point A, a relay 24 is driven, by which the acceleration of the fan 9 is started. When an intended cutting point C arrives at the point A upon further progression of the ingot 3, a relay 17 is driven and a gas cutter 8 starts cutting the ingot 3 at the point C. At the point A, the fan 9 completes acceleration and attains a high-speed running state. Thus the ponint A of the ingot 3 and the point of the time when the acceleration of the fan 9 is completed coincide perfectly, and the wasteful consumption of energy is prevented. |
