Papers by Author: Tan Jin

Abstract: The local distribution of the convection heat transfer coefficient (CHTC) of grinding fluids along the wheel-work contact zone under high speed grinding conditions has been investigated. A new approach has been proposed to derive the distribution of CHTCs along the contact zone by using the measured grinding temperatures and linking the distribution of local heat flux and heat partitioning to the workpiece, wheel and grinding chips. It has been found that the worktable speed is the key factor affecting the pattern of CHTC distribution, whilst the grinding speed strongly affects the overall magnitudes of the CHTCs. Down grinding mode is beneficial for achieving effective cooling under creep-feed conditions. The distribution of CHTC under faster worktable speeds shows a rather different pattern, which has to be considered when selecting the grinding mode and grinding fluid supply strategy.Keywords: Grinding, Fluid, Convective heat transfer coefficients, Temperature, High speed

Abstract: In this paper, there are two kinds of material (cermet and cemented carbide) to be used. Different grinding conditions were performed for evaluation of RMS of acoustic emission(AE) signals and understanding the effect of each grinding parameter on AE RMS during grinding process. A kind of on-line monitoring method based on wavelet analysis and acoustic emission was raised and the nonlinear relation model between AE RMS,wavelet energy coefficients and wheel passivation state was built. During the process,the wavelet analysis method was used to decompose the original signals for extracting wavelet energy coefficients. The results of experiments indicates that AE RMS increases with increasing table speed;The corresponding relation between AE RMS and table speed is good and could take the table speed as the main parameter for studying wheel passivation state. As a result, the nonlinear relation model can monitor the wheel passivation degree on-line accurately through training. This provides a kind of viable method which has very high practical value for confirming the wheel dressing cycle.

Abstract: The grinding temperature in wheel-workpiece contact zone in HSDG of alumina ceramic was measured using the grindable K type thermocouple. Effects of the grinding conditions, including wheel velocity, feed rate and depth of cut, on the temperature were investigated. The results indicate that the grinding temperatures measured under different grinding conditions varied from 100 to 300 °C. The grinding zone temperature exhibits a reasonably linear relationship with the average energy flux, i.e. the higher the energy flux, the higher the corresponding grinding zone temperature will be.

Abstract: The residual stress on the ground surface of workpiece in high efficiency deep grinding (HEDG) has been investigated. It has been found that the mechanism in forming the ground surface residual stress in HEDG is much different to that in the conventional shallow cut grinding process. It is not a thermally dominant event as in most of the shallow cut grinding mode; it is instead driven by the combined effects of both the thermal and mechanical loadings. The compressive plastic deformation near the workpiece surface during grinding and the short contact time in the HEDG regime, makes it possible to generate compressive surface stresses even when the surface temperatures are above 700-800°C.