Method of detection null of the core drill status in the core drill

摘要

PURPOSE:To contactlessly detect proximity of a core drill to a workpiece further to invisibly detect blinding and wearing in an edge point by forming a grinding fluid chamber, which communicates with a core hole of the core drill, and a supply port and a communication port in this chamber and detecting a pressure of the respective ports to be compared. CONSTITUTION:A core hole 3a provided to penetrate through on the center axis of a core drill 3, grinding fluid supply passage 4a and a detection passage 4b for detecting a pressure are respectively formed in a grinding fluid chamber 2a formed in a spindle head 2. While a pressure sensor 7 is connected to the supply passage 4a, and a pressure sensor 9 is connected to the detection passage 4b, respectively. When the core drill 3 approaches a workpiece W, grinding fluid is not released from the core hole 3a with a detected pressure of the pressure sensor 7 equal to that of the pressure sensor 9, and a feed of the core drill 3 is stopped being based on a command of a comparator part 12. In this way, the feed is stopped immediately before contact with the workpiece W.