| 摘要 |
<p>PROBLEM TO BE SOLVED: To separate a ring sensor from a machining area so as not to be exposed to cutting oil by installing the ring sensor to a rotating union or earth line situated in the anti-tool side part of a main spindle. SOLUTION: A rotating union 20 rotated together with a main spindle 2 is arranged on the upper end part of a draw bar 7. An earth line 22 is connected to the rotating union 20 through a brush, and the earth line 22 is further connected to an earth (machine body). An annular ring sensor 21 is installed to the earth line 22. The ring sensor 21 may be installed to the rotating union 20. In detection of the work contact position of a tool 9, the ring sensor 21 is high frequency excited, and the tool 9 is brought into contact with a work W. Thus, a closed loop circuit L is formed in the route of the earth line 22, the rotating union 20, the main spindle 2, a tool holder 5, the tool 9, the work W and the earth, and a detection signal is obtained from the loop current carried in this circuit L.</p> |
