Machining precision is attenuated by thermal factors. Making use of neural network's strong self-learning and data fitting ability
a novel method based on improved BP-neural network algorithm is proposed for comprehensive error compensation of multi-axis machine tools. An improved algorithm introducing steepness factor and amplification factor is presented to improve the convergence efficiency affected by slow decline of neurons error surface
and to predict and compensate machining precision of motion axes. The measured data of the temperature of each key heat source and displacement errors of motion axis of the large A/B double-pendulum angle gantry milling machine are respectively regarded as input and output. A machining precision error prediction model of machine tool is established and trained by the improved BP-neural network. The nonlinear relationship between temperature and displacement errors is obtained. Cutter location data file of workpiece is modified accordingly and machining precision is improved. Simulation and experiments indicate that this method reduces the prediction errors and computing period compared with the conventional BP-neural network. It is unnecessary to greatly reform the existing machine tools for application of the comprehensive error compensation system.
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