| 摘要 |
PURPOSE:To keep an optimum clearance variable depending upon operating condition by providing a piezoelectric displacement element between jibs, which are interposed on the sliding surface of a sliding table movably disposed on a guide table, and a surface in contact with the jib back surface of the sliding table so as to control applied voltage. CONSTITUTION:Voltage is applied from a controller 29 to a piezoelectric displacement element 23 so that the element 23 is displaced so as to urge jibs 20, 21, 22, resulting in small clearance (h). The state of the clearance (h) is fed back to an integral controller 26 through a measuring device 27 on the basis of an output signal from a piezoelectric pressure element 24, and thereat, in the case of zero, the signal rapidly changes and a voltage value at this time is set as a reference value. A table 16 is started, and the current values of motors 5, 12, 14 are measured so as to be compared with the judgement data of a memory 28, and then, an operating condition is judged, and further, an optimum clearance is outputted to the integral controller 26 so as to be compared with an output from the measuring device 27, and next, another signal is sent to the controller 29 so that voltage is outputted to the piezoelectric displacement element 23, thereby obtaining the optimum clearance. |
