Comparison of accuracy stability using a thermal compensator and grating ruler

Abstract

Heidenhain Co. Ltd. is about ¥13000 (ML1140). The larger the size of machine, the higher the cost of grating ruler. The higher prices limit the application of grating rulers on middle and low-level machine tools. Thermal error is an important factor for the accuracy stability of CNC machine tools. Motors, bearings, hydraulic system are the main sources of thermal errors. The error compensation method is a "soft technology" and has been studied for many years. However, it has not been widely used. The main reasons are: (1) the prediction accuracy is related to the number of temperature sensors according to the commonly used method, such as multiple regression method [4-7]. Many temperature sensors are needed on machine tools to achieve a higher prediction accuracy. This increases the cost and lowers the reliability of temperature acquisition system. (2) The robustness of commonly used models is poor [8, 9]. When the moving positions and speeds in actual machining are different in modeling, the predicted result is always poor, particularly for the multiple regression method.

CPLD-Based Displacement Measurement System for Nanoscale Grating Ruler

“…In this paper, the CPLD2018 chip is mainly used to subdivide the direction output control signal circuit of a nano-quality conductor grating ruler [23]. According to the directional phase shift relationship between the two orthogonal direction encoding control signals, the two orthogonal inputs of the chip are encoded.…”