Advances in Machining & Manufacturing Technology IX

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Authors: Shu Huang, Jian Zhong Zhou, Yi Bin Chen, Yue Qing Sun, Jian Jun Du
Abstract: An emerging process named laser compound forming of plate was presented by analyzing the advantages of laser thermal-stress forming (LTF) and laser peen forming (LPF) respectively. This technique combined the heat effect of continuous laser and mechanical effect of pulsed laser. Based on introducing the process of laser pre-stressed compound peen forming, the mechanism of plastic deformation and residual stress were analyzed. In order to apply pre-stressed load, a CO2 laser was used to scan SUS304 stainless plate according to the designed tracks firstly, the basic shape were formed and the contours of plate’s surface were measured by the optical scan measuring system, reverse engineering software Imageware was used to establish the virtual models of plate. Then the virtual models were inverted into finite element models by FEM code ABAQUS. The optimum distribution of residual stress field was obtained by adjusting laser parameters and controlling tracks of LPF. Finally, the optimized laser parameters and processing condition were used for LPF experiment. The results indicated that the anticipated shape could be obtained, and both side of the plate hold residual compressive stress after laser compound forming.
Authors: Zong Jun Tian, Li Da Shen, Yin Hui Huang, Guo Ran Hua
Abstract: This paper describes an investigation of nano-SiC reinforced ceramic coating, which has included NiCrAl and Al2O3+13wt%TiO2 coatings pre-produced by atmosphere plasma spraying, implemented by laser sintering. Commercial NiCrAl powders were plasma sprayed onto 45 steel substrates to produce a bond coating with thickness of ~100μm. The Al2O3-TiO2 based coating with ~500μm thickness was then plasma sprayed on top of the NiCrAl bond coating. With CO2 laser, nano-SiC powders were laser sintered on Al2O3-TiO2 based coatings. The microstructure and chemical composition of the modified based coatings were analyzed by such detection devices as scanning electronic microscope (SEM) and x-ray diffraction (XRD). The results show that the size of SiC grains has no obvious growth. In addition, due to the nanostructured SiC phase and laser remelting, the modified coatings exhibited better abrasion resistance than those unmodified samples.
Authors: Wei Ping Wang, Singare Sekou, Ya Xiong Liu, Di Chen Li, Bing Heng Lu, Jue Wang
Abstract: The traditional method to manufacture the medical implant or prosthesis is based on sculpting and on the tissue site,or takes impressions of the entire face about human. The accuracy and efficiency of medical implant or prosthesis produced by conventional method is heavily relied on the skill and experience of both designer and manufacturer. In this paper, an integrated method of medical implant manufacture is approached. This integrated strategy was to establish a system that allows fabrication of facial prosthesis from digital information, and integrates the rapid prototyping with modeling technology of complex three-dimensional geometry from high-resolution non-invasive imaging, reverse engineering and computer aided design. The research results have shown that the integrated method can produce more exact-fit medical implant, that is, the physical model of the implant is more exactly fitted on the skull model. The advantages of this method are that the surgeon can plan and rehearse the surgery in advance, and a less invasive surgical procedure, and less time-consuming reconstructive, and an adequate esthetic can result.
Authors: Yong Li, Yong Tang, Xi Bing Li, Wen Jun Deng, Zhi Xin Zeng
Abstract: The manufacturing process of micro-grooves inside thin-walled copper heat-pipe is always complicated and difficult. Separately adopted GCr15 and W18Cr4V multi-tooth mandrel, a series of experiments have been done to machine axially inner micro-grooves of micro-heat-pipe with oil-filled steel-ball spinning technology to analyze the mandrel effect and failure mechanism. It was studied how the tooth-shape of multi-tooth mandrel affects the inner micro-groove shape of the copper tube and how the working position of multi-tooth mandrel affects groove-wall surface morphology and groove path. The wear and fracture characteristics of multi-tooth mandrel are introduced. It is proved that the form of GCr15 mandrel failure in machining micro-grooves is tooth-broken or tooth-collapsed, and its service life is short. Differently, the form of W18Cr4V mandrel failure is felt wear, and its service life is long.
Authors: Da Ping Wan, Hong Bin Liu, De Jin Hu, Hai Feng Wang
Abstract: The surface texture of sheet steel plays an important role for automotive applications. To achieve appropriate surface topographies and press-forming behaviour, a new laser coating texturing (LCT) technique aimed at texturing steel work-rolls was proposed. The laser texturing process was realized by applying laser pulses at very high repetition rates to produce innumerable micro-craters with the required shape profile on the surface of the rolls. Moreover, the surface alloying of the dimples was carried out on the substrates of bearing steel GCr15. The submicron WC-Co alloy metal powder was melted into the micro-craters by high laser energy. The effects of processing parameters on the properties of the laser textured samples were investigated. The dimpled surfaces were examined by a 3-dimensional surface profilometer. Microstructures of the coating layers were assessed by optical and scanning electron microscopy. The experimental investigations show that the laser-dimpled hard-coated surfaces exhibit compatible metallurgical interfaces with the substrates. The laser coating textured roll is demonstrated to have excellent abrasion resistance and a much longer service life. The abrasive wear resistance was 5 times higher than that of the substrates. The average surface microhardness values were as high as 700HV.
Authors: Ying Ning Hu, Cheng Yong Wang, Shan Shan Hu, Bang Dao Chen, Chang Xiong Chen
Abstract: By FEM module analysis and temperature distribution analysis of diamond saw blade with multi-holes base and different segment width, influence of different hole diameter, hole number and segment width to nature frequency is clear. Adopted single-factor test, sawing force and acoustic emission signal are measured by cutting several kinds of strength concrete in different cutting parameters. The analysis to characters of sawing force and acoustic emission helps to find out optimum structure of diamond saw blade with different segment width, more rational sawing parameter and its adaptability to workpiece material.
Authors: Yi Qing Yu, Yuan Li, Xi Peng Xu
Abstract: An experimental study was undertaken to compare the mechanisms of two different processes to dress metal-bonded diamond segments. In one case, a piece of vitrified SiC wheel was used as workpiece and sawn by diamond segments attached to a sawblade. In another process, a diamond segment was used as workpiece and ground by an Al2O3 wheel. Spindle power was measured in sawing and horizontal force was monitored in grinding, in which case the latter was then used to get the consumed power in grinding. Specific energies were then calculated from the measured or converted power. For sawing of SiC wheel with the diamond sawblade, the maximum specific energy was found to be only 0.5 J/mm3, whereas the specific energy was up to 25 J/mm3 in the grinding of the diamond segment.
Authors: Duo Sheng Li, Dun Wen Zuo, Rong Fa Chen, Yu Li Sun, Bing Kun Xiang, Wen Zhuang Lu
Abstract: In this paper, a new polishing technique was proposed to polish concave spherical surface by diamond spherical shell deposited by DC-Plasma Jet CVD(chemical vapor deposition), and preparation was studied from both experiment and theory. The deposited films were investigated by some techniques including: scanning electron microscopy (SEM), atom force microscopy (AFM), Raman spectroscopy, and roughness-profile-meter, which were used to analyze surface phase, microstructure, internal quality and surface roughness. The results show that the deposited diamond spherical shell film has some remarkable properties, such as high surface density, high hardness. Compared to traditional polishing techniques, it will have some potential advantages as convenient, flexible, efficient and precious. To adjust some important parameters as methane concentration, depositing time, and it can deposit the different size grain diamond spherical shell films, which are used to polish different precision degree concave spherical surfaces. Meantime, to change curvature of diamond spherical shell, it can adapt to polish various curvature radius concave spherical surfaces.
Authors: Wen Hui Li, Sheng Qiang Yang, Shi Chun Yang
Abstract: It is a difficult problem of surface finishing to the wheel hub. From the structure and finishing request of wheel hub and barrel finishing mechanism, a new technique project for wheel hub finishing is put forward and established. Its finishing mechanism is explained, and theoretic research is done. By analyzing effect factors and their rules, theoretic basis is settled for experimental research and industrial application. The study indicates that this process is very effective for wheel hub finishing.
Authors: Guang Bin Bu, Can Zhao, Dun Wen Zuo
Abstract: It was carried out that a HSM test for aluminum alloy (2A70) rotor with carbide cutter. It was investigated and analyzed that the influence of different cutting speed and feed speed on the roughness of blade’s finished surface. The experiment showed that high quality surface was easy to obtain by increasing the cutting speed and decreasing the feed. But when the cutting speed crossed the critical value, increase in the cutting speed caused slight decrease in the surface roughness. The feed decreased to a very small value, the roughness increased a little. It was expected that best surface roughness and machining efficiency could be obtained by selecting the appropriate cutting speed and feed.

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