Numerical control method

摘要

In this numerical control method that drives the feed shaft of a machine tool (10) by means of a servo control unit (52), a transmission function is determined by modeling the operation of the servo control unit (52) of the feed shaft, the closed loop transmission function (GBP) of the position loop and/or the closed loop transmission function of the velocity loop of the servo control unit (52) of the machine tool is measured using the frequency response of the feed shaft, the control subject (PP) of the position loop and/or the control subject of the velocity loop is determined using the measured closed loop transmission function, the position loop modeling error (ΔPP) and/or the velocity loop modeling error is determined from the control subject, and at least one control parameter of the servo control unit (52) is calculated using the closed loop transmission function and/or the modeling error. As a result, the optimum plurality of control parameters corresponding to the state of the feed shaft is determined easily and automatically.

主权项

1. A numerical control method which uses a servo control unit to drive a feed axis of a machine tool, the numerical control method comprising steps of:
measuring at least one of a closed loop transfer function GBP of a position loop, which is found from a ratio of a position command and an actual position, and a closed loop transfer function GBV of a velocity loop, which is found from a ratio of a velocity command and an actual velocity, at the servo control unit of the machine tool by using a frequency response of the feed axis; finding at least one of a function of a control coverage Pp of the position loop and a function of a control coverage Pv of the velocity loop by using the measured closed loop transfer functions GBP, GBV; finding at least one of a modeling error ΔPp of the position loop and a modeling error ΔPv of the velocity loop from the control coverages Pp, Pv; and calculating, as a control parameter, a position proportional gain Kpp of the position loop from the closed loop transfer function GBP of the position loop and the modeling error ΔPp of the position loop and/or calculating, as a control parameter, a velocity proportional gain Kvp of the velocity loop and an integral gain Kvi from the closed loop transfer function GBV of the velocity loop and the modeling error modeling error ΔPv of the velocity loop, so that the feed axis of the machine tool is set with the calculated control parameters, wherein reciprocals of the closed loop transfer functions GBP, GBV are shifted in a direction in which a frequency of the frequency response increases so as to approach to the modeling errors ΔPp, ΔPv, respectively, and the position proportional gain Kpp, the velocity proportional gain Kvp, and the integral gain Kvi are calculated so that the reciprocals of the closed loop transfer functions GBP, GBV do not cross the modeling errors ΔPp, ΔPv, respectively.