Papers by Author: H.T. Zhang

Abstract: Due to the complexity of machine tool thermal errors affected by various factors, a new combining prediction model, based on the theory of gery system GM (1,1) model, is applied to the trend prediction of machine tool thermal errors. The degree of smoothness of primary data sequence is first improved by function transform method and sequentially grey system GM (1,1) model is established; second, time series analysis model is established by remnant sequence of GM (1,1) model to amend the precision of grey system GM (1,1) model. Thus, the precision of combining prediction model is further improved. Through the prediction study on thermal error modeling in a spot NC turning center, testing results showed that combining prediction model can highly improve machine tool’s prediction precision and make it more effective for real-time compensation of machine tool thermal error.

Abstract: The volumetric positioning precision of CNC machine tools is the key factor to get high machining precision, so the analysis, measurement and compensation of the volumetric error is becoming more and more important. In this paper, the modeling results of 3-axes CNC machine tools with four different configurations are given based on rigid body theory and homogeneous coordination transformation matrices. An improved sequential step diagonal measurement method is proposed and analyzed because the current laser measurement methods are complex and time cost. At the final section of the paper, the measurement data was applied into the error compensation and the sequential step diagonal measurement method was validated efficient and convenient.

Abstract: Being a high efficient technique for metal surface treatment , centrifugal grinding is widely applied in the field of polishing and burring for small-sized asymmetric parts. During the process of centrifugal grinding, the dynamic characteristics of the abrasive flow, which is determined by the planetary driver ratio of the instrument, has a profound impact on the quality and producing efficiency of the workpiece. Targeting on the massive abrasive, this paper investigates experimentally theinfluence of the planetary driver ratio of the instrument to the producing quality and efficiency. On one hand, a high-speed photograph is employed to record the movement of the abrasive flow in the processing of centrifugal grinding. The dynamic characteristics of the abrasive flow have been investigated for different planetary driver ratios. By qualitative analyzing the high-speed photographing results, the perceptual knowledge of the characteristics and the kinematic rules of the abrasive flow have been obtained. On the other hand, the surface roughness data at different planetary gear ratio and polishing time have been measured. The influence of planetary gear ratio on producing process have been illustrated by plotting the roughness-time curve combined with the high-speed photograph so as to provide a scientific basis for optimizing the parameters of design and technology.