Papers by Author: Jian Qiu

Abstract: Research on thermal field and thermal errors of NC machine tools were carried on using infrared imaging and laser distance measurement technologies. It mainly focused on the analysis of thermal field distribution of a three-axis horizontal machining center and the relationships between thermal behaviors and their temperatures. It was found experimentally that spindle thermal errors is one of the main errors sources of NC machine tools, and spindle thermal errors has been observed to be closely linked to the temperature distribution of machine tools. There was a significant increase in the axis positioning error related to the spindle temperature increasing. The elongations on Z direction are much larger than the extensions of X and Y directions. Finally, a method by adjusting spindle temperature to control spindle thermal errors was taken.

Abstract: Super high-speed point grinding is a good performance grinding with high surface quality due to its low force. To model point grinding forces including swivel angle formed by tilting wheel to the horizontal workpiece axis seems necessary. In this research, a point grinding force model was present, and the point grinding forces are influenced by factors such as grinding depth, wheel velocity, swivel angle as well as equivalent diameter. And then some experimental tests are carried out. It is found that the experimental data was in good agreement with theoretical model.

Abstract: This paper describes the grinding temperature characteristics in peel grinding. Some mathematical models such as average heat flux, triangular heat flux distribution and workpiece temperatures in the contact area are built. Using triangular heat flux model, the heat flow transferred to wheel and workpiece are analyzed. A 2D FEM model for thermal aspects of peel grinding process is presented and a finite element algorithm is implemented to solve the nonlinear problem. Finally, a peel grinding thermal field experiment was present.

Abstract: A study on the wear of Quick-point grinding wheel was carried on. The wheel wear was found having great influence on grinding performance and grinding quality. After analyzed the wear process and mechanism in Quick-point grinding, it was found the wear rate was directly related to some factors such as wheel width, workpiece speed, feed rate and Quick-point grinding angle, and it was indirectly affected by wheel speed and cutting depth. By means of some wear criteria, the wheel wear was able to be predicted. Furthermore, a wear model in wheel’s accurate area has been built up.

Abstract: It is important that preparing high quality grinding wheel to match Quick-point grinding processing. Using brazed CBN grinding wheel, grains can be combined with wheel matrix in high bonding strength, which is helpful to minimize wheel wear and to gain a good grinding ability. By establishing the connection between stress and its increment, the mechanical properties of wheel under different conditions is described. The wheel speed has effect on wheel matrix displacement and stress. Applying finite element method to optimize wheel structure, a final grinding wheel for Quick-point grinding is obtained.

Abstract: Separating the workpiece velocity on the plane of grinding wheel, it is helpful to analyze Quick-point grinding mechanism. There are some relations among wheel’s deflective angle, workpiece feed velocity and tangential velocity. In this research, the resultant workpiece speed, grinding contact zone and material removal mode is analyzed. And a model is established which is helpful to analyze the tendency of component grinding forces and force ratio. It is found the grinding force is influenced by the factors such as cutting depth, wheel velocity, grinding angle as well as equivalent diameter, respectively. Finally, a theoretical basis for actual processing is provided.

Abstract: With the help of the infrared camera temperature measurement technology, the systemic theoretical analysis and experimental research for temperature field and thermal error distribution in NC grinding machine is provided. Two different situations for temperature field and thermal error distribution are respectively measured while the free and loaded grinding by the new measurement method. The mathematical model of thermal error is built, and it shows that the actual error and the forecasted error from thermal error mathematical model have good comparability.