Papers by Author: Zhen Long Wang

Abstract: Aiming at machining deep micro-holes in titanium alloy, an experimental approach for EDM adopted a fuzzy control system was introduced. The fuzzy control system based on statistics of discharge states, that pulse interval and jumping height as control parameters, was self-developed. The suitable parameter for the deep micro-hole EDM process can be handily adjusted and modified in visual MATLAB fuzzy editor. A lot of experiments for titanium alloy micro-hole machining were performed on the EDM machine tool adopting the fuzzy control system. A titanium alloy deep micro-hole with 80μm in diameter and 15 in the ratio of depth-diameter is obtained. The process and results of experiments show that the process stability and efficiency be improved; due to the fuzzy control system and its suitable control parameters are applied.

Abstract: Inspired by the squid’s funnel which can bend flexibly, a kind of biomimetic squid funnel actuated by shape memory alloy (SMA) wires was developed for controlling the jet direction in this article. With the application of Pulse Width Modulation (PWM) technique, experimental investigation was conducted. And the results show that, the bending angle of the biomimetic squid funnel can be controlled by changing PWM duty cycle and the final stable resistance of SMA wire decreases while the duty cycle is increased. The relationship between the banding angle of the biomimetic squid funnel and the resistance of SMA wire is approximately inverse linear. The feasibility of jet direction control with the biomimetic squid funnel was verified by a simulated jetting experiment.

Abstract: According to the principle of muscular hydrostats, a flexible biomimetic octopus arm is put forward firstly. The method of vector control for the flexible biomimetic octopus arm is presented and analysed in detail. Based on the combination of ARM (advanced RISC microprocessor) and FPGA (Field Programmable Gate Arry), a control system for the flexibie biomiometic octopus arm is discussed, and the functions of every components is analysed. To verify the feasibility and reliability of the method of vector control, experimets are carried out. The experimemtal results demonstrate that this method applied in the control of the biomimetic octopus arm has a good performance.

Abstract: An experimental biomimetic water-jetting propulsion vehicle for robot cuttlefish is presented. Firstly the cuttlefish swimming mode and mantle muscle structure is analyzed as the theory basis. Secondly the vehicle is designed and manufactured. The vehicle is actuated by SMA wires. Through rational structural design, it can achieve flexible water-jetting propulsion like cuttlefish mantle. Thirdly the geometrical model of the biomimetic mantle cross section is built. At last, the performance of the propulsion machine is tested by experiment. The experimental results are mainly about the response curves of the mantle outside diameter, the strain of SMA wire and the swimming displacement with time. The maximum contractive distance of the biomimetic mantle along the vertical direction is 6 mm, the maximum strain of SMA wire is -1.8 %. The maximum swimming speed is 45 mm/s.

Abstract: In this paper, a thermo-physical model of the electric discharge machining process using finite element method is presented. In this model, parameters such as convection, the latent heat and the thermal properties based on temperature dependent etc. are studied to predict the temperature distribution in the workpiece. The temperature field simulation and experiment were carried out by adopting parameters through optimum pulse curve, and amending the effects of recast layer, the simulation results amended shows a better agreement with experimental results, indicating a theoretical foundation for mechanism of material removal in EDM machining.

Abstract: This paper discusses a processing preparation for micro-electrode array fabrication by micro wire electrical discharge machining. Based on a self-developed micro-WEDM machine tool and adopted thin tungsten wire electrode of 30μm in diameter, a series of experiments on micro-electrode array machining are introduced. The relationship between the discharge gap and working area of wire discharge under given voltage is investigated. The examination for micro-girder structure forming process has gone along and the axle journal's minimized width of least micro girder which could not bring on machining flexural thermal deformation has been obtained. The clamping method of work-piece intended for electrode array fabrication is analyzed and a special fixture is designed. The factors affecting forming accuracy are summarized. An amounted 5×5 squared-disk-type micro-electrode array structure with a high aspect ration, namely 20μm in axle journal width and 500μm in length of a single electrode, has been machined successfully.

Abstract: In this paper micro-electrochemical turning for fabricating microelectrode is presented. A stainless steel film with 50 μm thickness as turning tool is the cathode and a rotary tungsten rod for the proposed microelectrode fabrication is the anode. By applying ultra short pulses in micro seconds, dissolution of the anode can be restricted to the small region very close to the cathode. Due to rotation of the anode and movement of the cathode along the rotary axis direction, the anode uniformity corrosion was improved and its rotating concentricity was ensured simultaneously. A micro-electrode with a high aspect ration, namely 20 μm in diameter and 2500 μm in length has been fabricated in the low concentration electrolyte, 4%NaOH.

Abstract: This paper discusses a design of a flexible bending biomimetic octopus arm unit. Firstly, bending function of the octopus arm is analyzed. Secondly, the structure of the arm unit driven by shape memory alloy (SMA) is presented which can realize flexible bending. Meanwhile, mechanical model of the arm unit is established to find the proper parameters of the arm unit. Finally, experiments are carried out to demonstrate the feasibility of the structure.

Abstract: Inspired by some batoid fishes using horizontal trigonal pectoral fin for propulsion or maneuverability, a micro flexible mimetic propulsor actuated by shape memory alloy (SMA) wires is presented. Firstly, based on the motion characters of the pectoral fin of manta ray, a simplified kinematics model was set up. Secondly, a three-dimensional numerical simulation on the oscillatory fin was performed by computational fluid dynamic (CFD) to investigate the interaction with the surrounding fluid and the propulsive force production. Thirdly, action experiment of the propulsor is done to verify the concept. At last, the propulsive performance of the propulsor is evaluated through thrust force measurement experiments. The experimental results accord with the CFD results well. The propulsor have potential feasibility applying in automatic underwater vehicles (AUV).

Abstract: In this paper a kind of architecture for an energy-saving EDM supply composed of three serial stages in the topology and its practical design are discussed. Various special controllers and its assisted circuits are introduced in the each of the three serial stages. The PFC controller UC3854 placed on the front stage provides satisfactory input power factor of the system. The PWM controller UC3875 mounted on the middle stage realize the closed control of the current of the inductance limiting machining current. An embedded controller PIC16F877 on the final stage is chosen to setting such machining variables as peak current, discharge duration and pulse interval. The communication with host PC is also realized by the same embedded controller. The architecture based on model of multi-controller parallel working guarantees capacity of the system real-time process. The prototype of the energy-saving EDM pulse supply using MOSFET power device is developed. A lot of experiments have demonstrated the feasibility and stability of the practical design.