Device and method for correcting transmission error of precise numerical control machine closed loop servo system

Abstract

The invention discloses a device and a method for correcting a transmission error of a precise numerical control machine closed loop servo system. The method comprises the steps of: adopting a position detection and feedback unit to receive an encoder signal sent by a main servo motor and a grating signal fed back by a grating signal detection system, namely, receive an actual position and speed signal of the numerical control machine, comparing with a position and speed instructed value sent by the numerical control machine, computing a position and speed compensation value, issuing an order by a position compensator and a speed compensator to drive an auxiliary servo motor so as to drive the numerical control machine to correspondingly regulate the position and speed to realize the position and speed compensation function. The invention decreases the abrasion aggravating phenomenon caused by a screw rod repeatedly and rapidly rotating with a small angle, so the invention not only promotes the reliability, the service life of the screw rod and the compensation precision of the system, but also decreases the high demand on the property of the servo motor and lowers the cost. The device of the invention can be used as an auxiliary assembly for rapidly feeding and moderating.

Description

technical field [0001] The invention relates to the field of error correction of a CNC machine tool servo system, in particular to a transmission error correction device and method for a closed-loop servo system of a precision CNC machine tool. Background technique [0002] The fully closed-loop servo system is mainly composed of a position speed comparison link, a servo drive amplifier, a feed servo motor, a mechanical transmission device and a linear displacement measurement device; it has the functions of detection and feedback correction for the movement of the moving parts of the machine tool, and adopts DC servo motor or AC Servo motors are used as drive components. The grating or inductive synchronizer installed directly on the workbench is used as the position detection device to form a high-precision full-closed-loop position control system. Through position detection and feedback, the system adjusts the position and speed of the servo motor through the comparison ...

AI Technical Summary

Problems solved by technology

The control and compensation of the position and speed of the workbench are realized by the rotation of the screw driven by the servo motor. The structure is simple, but various nonlinear factors such as the stiffness of the mechanical transmission device, frictional damping characteristics, and backlash have a great impact on the stability of the system. The impact makes the installation and debugging of the closed-loop feed servo system more complicated, so it is only used on high-precision and large-scale CNC machine tools

[0004] Even if the installation and debugging are careful, after using this compensation mechanism for a period of time, due to the slender lead screw and large moment of inertia, repeated and rapid small-angle rotations for error compensation will lead to increased wear of the lead screw and rotation at both ends. The rigidity of the pair decreases and the gap becomes larger, which causes the movement of the screw itself, so that when the full closed-loop system performs error compensation, it will drive the worktable to move through the screw nut, causing the error compensation of the closed-loop system to have a negative effect, the movement is intensified, and the speed is further accelerated. Vibration and wear of the lead screw are caused, and the accuracy cannot be maintained. In severe cases, the lead screw must be replaced, which reduces the reliability of the lead screw and reduces the service life of the lead screw

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