井式气体渗碳炉在工件出炉后,为了防止炉内风扇轴在高温下变形,停炉后风机必须继续运转到炉温降至550℃以下再停机。为此,将原控制线路(图1)在a点断开,按图2虚线所示线路接上单刀双掷钮子开关K后,实现了炉内风扇按给定的温度自停。钮子开关K安装在控制柜面板上,标注上“正常”、“风冷”字样。当K与b接通时,控制线路依 Pit gas carburizing furnace After the workpiece is released, in order to prevent the furnace fan shaft deformation under high temperature, after stopping the fan must continue to run to the furnace temperature dropped below 550 ℃ and then shut down. To this end, the original control line (Figure 1) is disconnected at point a, according to the dotted line in Figure 2 connected to the single-pole double-throw button switch K, the furnace fan to achieve a given temperature of self-stop. Button switch K installed in the control panel, marked “normal”, “air-cooled” words. When K and b connected, the control circuit in accordance with