Papers by Author: Chun Jiang Zhou

Abstract: Size effect is a critical factor that needs to be considered when conducting micro mechanical machining processes. In this paper, a cutting process simulation technology is used to simulate a single tooth’s engagement with workpiece from the entry point to the exit point in a slot milling operation. The obtained specific cutting forces from simulation are employed to analyze the size effect and the minimum chip thickness with variable radii of tool edges. Micro machining experiments with different machining conditions are implemented by use of a high speed and high precision machining spindle to investigate the size effect on machined surface integrity and burr width. The optimal cutting parameters have been analyzed based on the simulation and cutting test results.

Abstract: This paper is to experimentally investigate the mechanical micro machining properties of AL6061-T6 using tungsten-carbide micro end mills. The cutting simulation based on Finite Element Analysis (FEA) method is also conducted to estimate cutting forces, cutting temperature, and minimum chip thicknesses. The simulation results are used for the determination of experimental machining conditions such as depth of cut, feed rates and cutting speeds. A number of slot micro-milling experiments were performed using 400um diameter micro end mills on a 3 Axis CNC machining center attached with a high precision and high speed spindle unit. The machined surface quality, geometric feature shape, cutting burr generation as well as build-up edges are observed in the cutting experiments. Optimum cutting parameters for a better surface quality and smaller burr sizes are suggested.

Abstract: The radial positioning accuracy and stiffness are two important indexes to measure the performance of tool system. Once HSK tool system is in operation, the gap between the spindle and shank will enlarge, thus will make the radial positioning accuracy and stiffness lower. The influence factor leading to this problem is analyzed in this paper through elastic mechanics and finite element analysis. It can get from the analysis that the double-position structure and certain amount of interface are key factors to keep HSK high radial positioning accuracy and stiffness. In addition, the influence of clamping force and rotate speed to radial stiffness is presented that higher speed and larger clamping force make the radial stiffness better. Finally, the paper has verified the analysis of radial stiffness through the experimental measurement with different fit of HSK.

Abstract: The coupling performance of tool system is the important factor for the machining quality of high speed machining. Based on the deformation of contact surfaces of HSK tool system, the paper makes the academic analysis by elasticity theory and finite element simulation to high speed spindle/tool shank coupling system. The property of the contact stress and the radial deformation as well as the torsional stiffness with different amount of interference has been analyzed. In this method, the paper brings forward how the amount of interference will affect the coupling performance. Thus, it will give academic evidence to design and select tool system in the process of high speed machining.

Abstract: The high speed machining technology of complex surface has been a focus of the study. Based on the analysis of cutting force model for ball-end cutters and cutting force tests of 3-axis machining, the paper brings forward the reasonable oblique angle of tool axis for complex surface with different curvature. According to the different feature of surface shape, the surface is classified in terms of oblique angle formed by tool axis and normal vector of surface. Meanwhile, the processing methods are proposed to adapt to classification of surface. Adopting 3+2 axis method in 5 axis machine to processing complex surface with different features by sub-regional process will effectively improve the surface quality and extend tool life. The paper finally put forward the high speed supplementary processing technology to process the boundary and transition area of surface.

Abstract: High speed machining is one of the advanced manufacturing technologies which have developed quickly in recent years. Tool technology is key factor which will make influence to the efficiency and precision of HSM. The paper has analysis the HSM tool technology in terms of material, shank structure and tool balance. It brings forward that tool material with high property must match with workpiece to get high efficiency and precision in HSM. Three type of shank are introduced and using HSK can get better working performance due to its double-surface positioning and short tapered shank. The paper finally put forward the online balancing test technology which can achieves the actual signal collection of dynamic balance, and make technical analysis as well as processing in high-speed cutting.

Abstract: The development of surface high-speed machining has put forward higher demands for uniform cutting load and smooth cutting tool path. Most current tool-path planning methods are based on constant scallop height, but they have the disadvantage of path point redundancy during the path discretization process. To overcome the problem, a tool path generation method of equal approximation error in each step for free-form surface is presented based on geodesic principle and curvature judgment. In this method, the NURBS curve is employed to realize smooth transition for adjacent two tool paths in high-speed machining. A certain angle of inclination of flat-end milling cutter during multi-axis machining improves the machining efficiency. Because of the advantage of this machining condition, the cutter location point generation algorithm during the machining condition is given by the method. The method is verified and simulated by C++. Experiment results proved that it can obtain uniform cutting load and continuous smooth cutting tool path during surface high-speed machining by the proposed method.