Papers by Author: Jian Bo Zhang

Abstract: Microstructural characterization of Al-Cu-Mg-Ag alloy ageing at low and elevated temperature were investigated by differential scanning calorimeter (DSC) and transmission electron microscopy (TEM). The results show that the precipitation sequence is significantly influenced by the ageing temperature. With prolonging of ageing at 65°C, G.P. zones on the plane of {100}α separates out with no precipitation of Ω phase. After 10h ageing at 160°C,the phase of Ω separates out and dominant the microstructure, while a small quantity of θ′separates out as well.

Abstract: A new free-form surfaces shape-adaptive polishing tool is introduced in this paper, which can change its pose with the surface of workpiece. The simulation of this tool system’s polishing process is taken using ADAMS, and the kinematics of the shape-adaptive tool on the curvature varying surfaces of the workpiece is investigated. The simulating results indicate that the tool system can fit the varying curvature and slope of the workpiece’s surface very well.

Abstract: Aspheric surfaces of high precision and low roughness are widely used in the military field, the aeronautics and astronautics field and some high-tech fields. Therefore, research works on the methods and equipments of digitalized polishing for aspheric surfaces are a hot issue in the modern precision manufacturing. The traditional precision manufacturing mainly depends on the higher precision equipments to promote the surface quality of aspheric surfaces, but the cost of equipments seems to be extremely expensive. Taking the general CNC lathe of two axis interpolation as a platform, and basing on the controllable damping characteristic of the Magnetorheological Fluids (MRF), a new kind of compliant polishing tool system for aspheric surfaces is developed in this paper. The tool system keeps the polishing force to be stable by the torque servo unit of MRF, and implements the compliant polishing.

Abstract: . Lots of new automatic polishing methods and equipments have been developed to solve the problem of low efficiency and quality in the traditional handwork curved surfaces polishing. However, these methods and equipments are complex and difficult to be applied in the industrial production. This paper proposes a new technology of rotate surface compliant polishing based on NC lathe cutter radius compensation. An efficient and compact rotate surfaces compliant polishing system is developed, which consists of a NC lathe, flexible polishing tool, workpiece, fixture and also the automatic programming software MASTERCAM. The polishing tool-path and NC code can be created in MASTERCAM. The value of the cutter radius compensation can also be set in NC code, so that the rotated surfaces can be polished by a traditional NC lathe. Experiment of polishing the aluminum sphere workpiece is taken, and the satisfying surface quality is achieved.

Abstract: Hard-brittle materials can be polished by hydrodynamic suspension, which is based on the theory of sound eradiating. Owing to the high-speed rotating of the polishing tool, the polishing slurry would form dynamic pressure in the clearance between the work-piece and the tool. The dynamic pressure supplies abrasive particles the energy needed to impact on the work-piece surface, so the dynamic pressure will directly affect the machining effect. In order to obtain the steady and consistent machining quality, it’s necessary to implement the compliant control in the machining process, and adjust the dynamic pressure when needed. This paper utilizes piezoelectric ceramic micro-displacement actuating to investigate the technique that can achieve the control of micro-displacement between the polishing tool and the work-piece. It provides an effective mean for hydrodynamic slurry pressure in the hydrodynamic suspension ultra-smooth machining.