Papers by Author: Ke Hua Zhang

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Authors: Ke Hua Zhang, Dong Hui Wen
Abstract: The interaction between the tungsten steel surface and the polishing fluid & abrasive were discussed by AFM, SEM and XRD test in order to compare the chemical performances and mechanical action of the tungsten steel polishing in the paper. The chemical mechanical polishing (CMP) and the mechanical polishing (MP) was employed, respectively. The experiments results indicated that the CMP with a higher the materials removal ratio than by MP. Because a chemical corrosion effect implies that slurries with the highest removal rate have high dissolution rate, and have a lower the residual stress, however the surface took on wrinkling.
Authors: Jin Fu Ding, Ke Hua Zhang, Guang Yi Mei, Fu Jin Yu
Abstract: In order to solve the difficulty of polishing process at present. Polishing posture was analyzed at the contact spot of polishing cutter with work piece in this paper, and how to layout the polishing path and its built method were discussed emphatically, carried out simulation analysis with Mastercam software, and proposed suitable building method of path according to different region using different polishing method. Finally, it is proved that an ideal effect would be achieved.
Authors: Ke Hua Zhang, Guo Feng Wang
Abstract: Development of ultra-smooth surface processing technology has great effect on the frontier technologies and defense industry, this attracts many countries to invest and highlight the research works related to ultra-smooth surface abrasive flow polishing technology. This paper gives a global review on the functional effect of ultra-Smooth surface abrasive flow polishing technology on the modern industry. Recent research achievements and machining accuracy developed by several famous universities were introduced and the principle and structure of the machining device were explained, according to the new demands for the future, the tendency of ultra-smooth surface abrasive flow polishing technology was suggested, especial emphasis on the precise polishing tool and the technology of soft contact between abrasive and workpiece.
Authors: Jin Fu Ding, Ke Hua Zhang, Yong Chao Xu
Abstract: In order to grasp the microcosmic mechanism of abrasive flow machining (AFM), find out the real law of grain cutting workpiece surface, make out a reasonable process parameters and improve the abrasive flow processing efficiency. The process of grain (near to workpiece surface, called as active grains) cutting workpieces material has been analyzed and the cutting force model has been established in present work. Firstly, at the beginning of the present work, the general process of grain cutting, wearing or deburring workpiece surface has been researched. Theoretical analysis shows that the cutting force not only derives from static force, such as abrasive medium viscoelasticity and grain squeezing, but also dynamic force, such as grain impacting load on the workpiece surface. In ordering to prove the dynamic force exists, one or two main dynamic process parameters (such as abrasive viscosity, extrusion pressure, piston velocity) are chosen, dynamic force is most sensitive to the variation of which, meantime, static force is not, and then the effects of main dynamic process parameters on cutting force value have been compared with the effects of others process parameters by several experiments in the present work. The experimental results show that with the same proportion of variation of process parameters, the change in cutting force (mainly axial cutting force) consists with theoretical results very well in some degree.
Authors: Ke Hua Zhang, Dong Hui Wen, Ju Long Yuan
Abstract: In order to achieve high efficiency and low damaged layer during sapphire lapping process, experimental research on the correlation between the surface quality and the abrasive grains wear in dual-lapping processing sapphire. The sapphire surface quality was characterized by roughness. Sapphire with (0001) orientation was lapped by 280 # boron carbide abrasive grits. The abrasive grains were analyzed by a laser diffraction particles size analyzer. The micro-surface uniformity and roughness were also presented by using WYKO equipment. Experimental results show that the abrasive grains size reduction was proportional to the improvement of the surface quality during the lapping, after 45min the abrasive size change tends to be uniform, the participation rate of abrasives grains in lapping process was between 0.2% and 16%. Sapphire with average roughness Ra<0.340μm, Rt<4.0μm, Rz<3.26μm, Rq<0.44μm, Ra0.523μm and Rt<6.0μm could be achieved by dual lapping processing with 280# boron carbide grits in 120 minutes.
Authors: Jin Fu Ding, Guang Yi Mei, Ke Hua Zhang, Fu Jin Yu
Abstract: In order to improve the surface quality and machining efficiency for mold polishing. Digital automatic Polishing is a good method, MasterCAM is the software that often is used for CAM machining, path layout and building method are emphasized according to the MasterCam’s curved surface processing path setting method, and aimed at the different curved surface use different polishing path building method, at last, the rationality of the polishing path building was validated.
Authors: Ke Hua Zhang, Dong Hui Wen, Ju Long Yuan
Abstract: Dual-lapping was a process to planarize the surface of the sapphire wafer, the nature of surface&subsurface damage and the surface uniformity was depended on the material removal mode and materials removal ratio. Material removal mode was studied in this paper, and the model of material removal was set up too. The SEM was used to scan the processed sapphire surface and the different removal style (two body and three body) were discovered. This research provided valuable insights into the material removal ratio and the dependence of lapping-induced damage on dual-lapping conditions, the asymmetry of abrasive granularity brought on the different materials removal mode and the surface asymmetry. The model was set up to qualitative analysis the material removal ratio in dual-lapping of sapphire, obtain the reasonable MMR and optimize the surface quality and the planarization result.
Authors: Q.L. Du, X.H. Chen, Ke Hua Zhang
Abstract: In this paper, based on analyzing the properties of medical Ti-6Al-4V Titanium alloy, the author takes the purpose of studying the machinability of the medical Ti-6Al-4V Titanium alloy and aims at improving the tool durability. The study starts from the tool material, geometrical parameters of the tools, usage for the cutting and other aspects in order to achieve the suitability of selecting cutting tool as well as the optimization of choosing cutting usage which lays the foundation for further investigation of the machinability of the medical Ti-6Al-4V Titanium alloy and carry out the online optimization of cutting parameters.
Authors: Guang Yi Mei, Ke Hua Zhang, Jin Fu Ding
Abstract: The surface roughness of the hydraulic prop had an important effect on the wear resistance, fatigue strength and property of fit. The ultrasonic surface rolling extrusion (USRE) processing experiment was employed to improve the surface roughness of the hydraulic prop, some machine parameters such as the tools transfer magnitude, feed were studied in detail, the contact style roughness tester( Mahr S2) was used to test the surface roughness of the workpiece. The experiment results showed that the USRE could improve the surface roughness evidently, the Ra value from 0.976μm reduce to 0.105 μm by one-hit machining. The feed was linear with the surface roughness, and when the tools’ amplitude was 6.5~8.5, there were a better surface roughness Ra 0.090μm. USRE processing the surface time and again could improve the surface state.
Authors: Ke Hua Zhang, Dong Hui Wen, Tao Hong, Ju Long Yuan
Abstract: This paper presents a finite element (FE) modeling of the nanoindentation test of sapphire, in which the finite element method was employed to study the mechanical characteristic of sapphire under the nanoindentation process. The results demonstrated that the nanoindentation FE models were able to simulate the indentation loading-unloading curves of the sapphire. The load and unload displacement curves of the simulation and experiment results can match with each other well, and then the properties used in the simulation should be the actual properties of the sapphire. The Mises stress field distribution of the sapphire sample was calculated to reveal the alteration from elastic region to plastic region, which are useful for indentifying the ductile to brittle change in the sapphire abrasive process.
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