| 摘要 |
PURPOSE:To allow a machine tool to work with no more than normal torque even at the time of tool breakage by equipping a device to sense off any abnormal feeding with a variable current restriction command device and by furnishing a selection command device to control it in accordance with the processing program. CONSTITUTION:When fast feed is commenced, a restriction current device 4 is maximized so as to be capable of allowing the current up to momentary max. rating to flow through a feed motor 3 and a servo amplifier for driving 1. A selecting relay 41 is set to the max. voltage (d) by a control signal from NC device. In order to select a necessary and sufficient current restriction value for machining prior to feed for machining, a selecting relay 41 is selected among (a)-(c) and switching-over shall be made to it. When the tip of tool is broken, the machining reaction increases violently, however under restriction by the current limitation. An abnormality signal about saturation of the current value is sent out from a terminal C of the servo amplifier 1. |
