Papers by Author: Zhen Yu Zhao

Abstract: The different initial morphologies of polished surface is one of the important factors affecting the quality of laser polishing. In order to investigate the flow characteristics of the molten pool with different morphologies, a two-dimensional (2D) axisymmetric numerical model is established based on the COMSOL software. The nonisothermal flow interface is used to couple the heat transfer and fluid flow, and simulate the evolution process of the molten pool with three different surface morphologies. The results show that the initial shape is a smooth plane, the flow velocity of the molten pool is stable and always in thermocapillary regime, then the protrusions were generated at the edge of the molten pool. Likewise, with the increase of the surface curvature, the capillary becomes the main driving force to eliminate the surface asperities. While the flow velocity and instability of the molten pool enhance, and the depth of the molten pool increases with the heat transfer generated by the mass flow along the z-axis direction.

Abstract: In the paper, the injection process of mold sleeve is simulated with Moldflow software, and the filling time, cavitation, weld, and causes warping are analyzed. The warping effects on the workpiece surface quality. Moldflow software can optimize gating system and shorten the fill time, improve the quality of plastic surface, reduce the number of repair mode, and shorten the product development cycle.

Abstract: The forming scheme of a side-plate of the core part in parallel flow evaporator was studied. Two forming schemes were compared and the explicit dynamic software DYNAFORM was applied to make simulations about the forming processes. According to comparisons between two forming schemes, the optimized scheme and process parameters were determined. Multi-station dies were designed based on the optimized process. Successful experiments with the dies showed that numerical simulation provided an efficient way for the optimization of the forming scheme in the side-plate production.

Abstract: At present, high speed machining (HSM) features in high efficiency, high precision, high flexibility and high quality. HSM technology involves many factors, including cutting mechanisms, machining performance, tool path and other aspects. The key techniques on HSM such as linear interpolation, circular interpolation, cubic B-spline curve interpolation, non-uniform rational B-spline (NURBS) curve interpolation and their respective characteristics are paid more attention and expatiated.

Abstract: High speed machining (HSM) features in high efficiency, high precision, high flexibility and high quality. The key techniques on HSM such as linear interpolation, circular interpolation, cubic B-spline curve interpolation, non-uniform rational B-spline (NURBS) curve interpolation and their respective characteristics are paid more attention and expatiated. Circle arcs are approximated by using intersecting polygons instead of general inscribed polygons. NURBS interpolation algorithms can reduce feedrate fluctuation and improve machining accuracy.

Abstract: In the manufacturing industry, high speed milling plays a very important role. The paper introduced a number of essential core component of the key technologies in high speed machining center such as powerful computer numerical control systems, motion control card, post –processing method, processed trajectory control technology (Look Ahead) and high speed processing of programming. The speed control, post processing and look-ahead control are focused on considering, and the corresponding improved methods are brought forward.

Abstract: Based on the amount of tool overhang under different high speed machining experiment, the overhang length on the high speed impact of cutting force in milling process is studies. On the basis, the proposed tool overhang and optimum program are proposed in high speed milling, through the rational use of tools to improve processing capacity of the tool.

Abstract: High Speed Milling (HSM) is well known as an innovative key technology for modern machining. HSM can obtain very high surface qualities, subsequent manually finishing operations can be eliminated in many cases totally or at least partially. Theoretical and experimental researches have proven that the cutting force in a high speed milling process has significant influences both on surface roughness and deflection of the cutting tool. In this paper, mould steel for high speed milling experiments by multi-factor test on the high speed milling machine tools. By studying the relation of overhang length, cutting speed and cutting force of cutting parameters, the cutting force tested is analyzed in high speed milling. When mold steel is cut at high speed, the influence of cutting speed on cutting force is studied, which has a guidance in the actual production.

Abstract: The paper describes the important role of Moldflow technology and status. Through the application of Moldflow / MPI (Moldflow Plastics Insight) software for CAE under a comprehensive analysis of the shell molds, injection molding parameters such as mold temperature, melt temperature, injection time and injection pressure are used to simulate the actual production process. This shows the Moldflow technology plays a significant role in the mold development process for optimizing plastic products design, plastic mold design and injection process parameters, etc.

Abstract: Pocket corner in the high-speed milling (HSM) often occur under-cut, over-cut, vibration and other phenomena. This not only reduces tool life, seriously affected the work-piece machining accuracy and processing efficiency. In the paper, the impact of cutting speed on cutting forces is studied in the pocket corner based on the high-speed milling experiments. The results show that cutting force increased slightly with the increase in cutting speed, and that cutting force no significant change with the increase in radial depth of cut.