Papers by Author: Fei Hu Zhang

Abstract: Removed due to plagiarism

Abstract: As the grain size of nano ceramic has reached nanometer grade, it possesses high hardness, high wear resistance and high toughness. Therefore, the scalpel made by nano ceramic has the virtue of high wear resistance, good corrosion resistance, long service life, non-toxic, non-static, sharp edge and so on, but the processing of this kind of scalpel is extremely difficult. This paper prepares the nano-ceramic scalpel by using ELID grinding technology, and also studies the thickness, surface roughness, edge sharpness of scalpel. The research results show that the thickness of prepared scalpel is 0.3 mm, the surface roughness is 6-60 nm and the edge radius is 200 nm, the cutting experiment on suture shows that this scalpel can meet the requirements of international standard for medical scalpel when the cutting force is less than 0.8 N. This further proves that the ELID grinding technology is suitable for the preparation of nano-ceramic scalpel. The preparation technology and technological equipment of nano-ceramic scalpel are proposed on the basis of above achievements, and this technology possesses promising application prospect.

Abstract: According to this theory, the cavitation mechanism of ultrasonic-pulse electrochemical compound machining (UPECM) based on particle impact is proposed in the paper. The mechanism was studied particularly, and validated by experiments. The results show that ultrasonic cavitation promote pulse electrochemical compound machining, and particle impact has the catalysis of the anodic dissolution in the ultrasonic-pulse electrochemical compound machining. The results also indicate that the processing velocity can be improved under the particle impact, obtaining the surface quality in UPECM compound machining.

Abstract: A new method for extracting spectrum feature of gas flucturation of aerostatic guideway is proposed. The flatness error of workpiece surface includes much errors information, and the information contains high frequency signal and low frequency signal, for these errors information, a new identification method of turning errors of workpiece based on the wavelet transform and power spectral density analysis is proposed. According to the focal variation character of wavelet and the energy value of power spectral density analysis, the feature of gas flucturation of aerostatic guideway from the measured flatness error of workpiece is extracted and identified.

Abstract: Nanoparticle colloid hydrodynamic cavitation jet polishing (HCJP) is a super-smooth machining technology. This technology utilizes the interface reaction to remove material from the workpiece and uses cavitation effect to improve the processing efficiency. In this paper, the prototype equipment of HCJP is researched. Based on the prototype equipment, the processing experiments of pulsed jet nozzle, swirling jet nozzle and common cone-shaped nozzle have been done and the results of the experiments are compared with each other. The experiment results indicate that the roughness of the surfaces polished by three nozzles has remarkably decreased. The material removal rate of pulsed jet nozzle is the highest among the three types of nozzles. The material removal rate of the swirling jet nozzle is not improved obviously compared with the common cone-shaped nozzle. The processing experiment of monocrystalline silicon by the pulsed jet nozzle has been done and the roughness of processed surface is Ra 0.475 nm.

Abstract: The manufacturing system developed in this paper is mainly used for the ultra-precision grinding of the hard-cutting materials, such as high strength steel and carbonized tungsten, which are characteristics with axisymmetric aspheric surface. Under the priority of accuracy and grinding rigidity to design the key components of multi-axis linked parallel grinding system of aspheric surface, such as high speed grinding spindle, B axis grinding rotary table, clamps and center high adjusting system. Maximum speed of the grinding spindle is 90,000rpm, spindle rotating accuracy is 0.1μm, rotation-angle-accuracy of B axis is , center height adjusting accuracy is 0.1μm, using the system can realize parallel grinding of aspheric surface[1].

Abstract: A new method for extracting spectrum feature of motor unbalance and interference of alternating current (AC) is proposed. The flatness error of workpiece surface includes much errors information, and the information contains high frequency signal and low frequency signal, for these errors information, a new identification method of turning errors of workpiece based on the wavelet transform and power spectral density analysis is proposed. According to the focal variation character of wavelet and the energy value of power spectral density analysis, the feature of motor unbalance and AC from the measured flatness error of workpiece is extracted and identified.

Abstract: Al/SiCp composite material is rapidly advanced due to its applications to weapon, military, aeronautics and astronautics. In some cases, fields of research are stagnating for its difficulty in material processing. In this study, we are particularly concerned about the cutting mechanism of Al/SiCp through modeling and simulations on wear rate of the tools. These simulations of tool wear rate and cutting mechanism of Al/SiCp are proved by cutting tests on Al/SiCp with nanocemented carbide tool WC-7Co and common cemented carbide tool YG8. A detailed investigation suggests that the cutting instinct of Al/SiCp is of interrupted cutting process. And the grain loss, less tipping and blade fracture during tool wear results from high frequency intermittent shock by SiC grain. The wear behavior on the tool flank is mainly of grain loss. However, the wear behavior of the rake face is not only of grain loss, but also abrasive wear of WC grain by SiC grain. It is conclusively demonstrated that the model of tool wear rate is sufficient for revolution characterization of tool wear rate on grain size, volume fraction of reinforcement, and also significantly important to prove the interrupted cutting process mechanism of Al/SiCp.

Abstract: ELID grinding technology is used widely in the precision grinding of hard and brittle materials. The nature of passivating film play an important role in ELID mirror grinding. Spring’s stiffness of passivating film was researched from theory and simulation and experiment. And the theory of the dynamic stiffness of spring was proposed, based on this theory minimum mechanism of roughness of ELID grinding was proposed further, and experimental verification was done. Results show, the spring stiffness of passivating film is change with the grinding paramenter, and when implementing the precision grinding, the elastic deformation of oxide film reduces the exposure and grinding depth of the grinding grains, accordingly, ameliorating the grinding surface quality.

Abstract: The properties of oxide films are very important for improving the mass of ELID grinding surface. In this paper, a novel calculation model of thickness of oxide films was proposed; the theoretical calculation and simulation analysis were developed, and were compared with the corresponding experimental results. The results proved that the theoretical calculation and simulation results of the thickness of the oxide films had good agreement with the experimental results. This model could predict precisely the change of thickness of oxide film, the instinct of non-linear electrolysis was explained from a novel aspect of ability of pulsed electrolysis. This model could be used in the on-line control of electrolytic state during practical ELID grinding process.