Abstract: This paper presents an experimental study in milling of SiCp/Al composites on a high precision machine by using chemical vapor deposition(CVD) diamond coated tools and polycrystalline diamond (PCD) tools. The tool wear was observed and measured by an optical microscope and a scanning electron microscope (SEM). The results show that the coating rupture causes the failure of the CVD diamond coated tools. The PCD tools’ wear is less. At the relatively low cutting speed, the wear pattern of PCD tools is the flank wear which caused by the abrasion of SiC particles. Due to the low cutting temperature, the graphitization of PCD tools does not happen. The wear mechanism of PCD tools will be the abrasive and adhesive wear.
Abstract: The paper presents a miniaturized two-spindle rapid denture repair system with applications on CAD/CAM dental restorations. The necessary functions possessed by denture processing system in medical treatment environment were defined, and the main technical parameters of the machining system were determined. The modal tests of the system structure were conducted for the key areas vibration mode. The volumetric geometric errors of the system were measured with laser interferometers. At last, the milling experiments of human molar crown denture were carried out with the mean surface roughness Ra value 0.8μm, which is consistent with the requirement of dental restoration.
Abstract: With its high grit retention and easiness to true and dress, the vitrified bond is widely used as a bond material for cBN and diamond grinding wheels. By giving electrical conductivity to the vitrified bond, application of electrical discharge trueing/dressing and detection of a workpiece position by electrical contact sensing will become possible. And moreover, application of the vitrified bonded wheels to various types of electro-assisted grinding processes (electrochemical or electro discharge assisted methods) is expected. In this study, vitrified bonded diamond segments with electrical conductivity were manufactured experimentally by mixing the fine copper powders in the vitrified bond matrix. As a result of investigation into the electro discharge trueing performance in the die sinking and wire electro discharge machining, it was found that a vitrified bonded wheel could be formed by electro discharge machining only because the bond was electrically conductive. In addition, the electro discharge complex grinding utilizing electric discharge machining was applied to the PCD cutting tool materials using the electrically conductive vitrified bonded wheel, and confirmed that the grinding could be continued for a long time maintaining a stable grinding force.
Abstract: In recent years, global economic development has led to rises in crude oil prices and the greenhouse effect. Developing renewable energy has become a major issue internationally. Biomass energy is one form of renewable energy. Biomass enery as a transportation fuel can be deliverd from fats, starch biomass fuel or biofuel, and cellulose biofuels. Because concerns exist that fats could lead to a food crisis, most nations have focused on researching and developing cellulose. In this study, we used coffee bean residue as a fuel source. We employed the pyrolysis process to produce pyrloysis oil products. We also used appropriate emulsion technology and suitable amounts of petroleum diesel for adding coffee bean residue to investigate the influence that coffee bean residue pyrolysis oil with low-add ratios (5 vol. %) has on diesel engine performance. The results indicated that coffee bean residue pyrlosis oil with low-add ratios resulted in an earlier diesel engine ignition time. Additionally, at low rpms, the diesel engine’s indicated specific fuel consumption (ISFC) was relatively low. However, ISFC was superior at higher rpms. In summary, when adding a portion of coffee bean residue pyrlosis oil to diesel engines, performance was superior during high-rpm operations compared to lower rpm. Pollutant emissions were also significantly improved. The results of this study can provide a reference for future high-add ratios and high-load engine tests.
Abstract: The drilled surface characteristic of epoxy resin reinforced by multi-directional carbon fibers is investigated based on experiments. With the emphasis on the effect of fiber direction, the mechanism of inhomogeneous surface topography is discussed. Besides, the mechanism of drilling-induced delamination and splitting defects are analyzed, and the drill condition and drilling parameters are also considered. It is indicated that the varied fiber direction is the main cause resulting in the inhomogeneous topography; delamination is easy to occur between two adjacent laminas which have different fiber directions, and it is more serious near the exit of drilled hole.
Abstract: A group of Zr-Ti-N coatings was prepared and studied to access their potential as a protective layer for micro drills to obtain cutting tool wear improvement. The coatings were grown using an industrial-scale four-target closed-field unbalanced magnetron sputtering ion plating system, employing one Ti and three Zr targets working in residual N2 atmosphere. To achieve Zr-Ti-N coatings with varying Ti doping content, the current applied to the Ti target was subjected to change from 0A to 3.6A while those to the Zr targets were kept constant. The coatings were characterized using GDOES, XRD, SEM, Vickers microhardness tester, scratch tester and Rockwell C indentation tester. Evaluation of wear improvement by Zr-Ti-N coatings for microdrills was conducted by machining of FR4 print circuit boards. It was found that the coatings with 16.5 at.% Ti doping content showed the highest microhardness and wear improvement for microdrills. Wear of microdrills with this coating could be reduced by a factor of two as compared with traditional TiN coated ones.
Abstract: The Zr-C:H coatings with various C2H2 flow rate were deposited on micro-drills (a diameter of 0.2 mm) used a closed field unbalanced magnetron sputtering system. The ultrahigh speed (drilling speed of 160000 rpm) through-hole drilling printed circuit board tests used to evaluate the drilling performance of the coated micro-drills. The rejection criteria of service lives of the coated micro-drills were evaluated using two different criteria: (1) a nail head ratio greater than 1.5; (2) a drilled hole surface roughness greater than 25.4 μm. Adopting a service life criterion of a nail head ratio of 1.5, the Zr-C:H-5 coating possesses the optimal high-speed machining performance, which yields a micro-drill lifetime of above 6000 drilled holes. It represents a three-fold improvement on that of an uncoated micro-drill and it also improves machining quality.
Abstract: Magnetic suspension technology is used in CNC machine tool. The guide which uses the electromagnetic force is suspended in the air without mechanical touch. There is no mechanical contact with the supporting components. It can eliminate friction and wear. Magnetic suspension structure guide can achieve fast and precise position, and increase the productivity of the equipment substantially. Magnetic suspension structure guide has a lot of significant advantages. The magnetic suspension rail can ensure the high positioning accuracy of machine tools platform from the structure, and reduce the inertial mass of the drive system, Improve platform mobile frequency response. Magnetic suspension system has both the advantages of Energy-saving and environmental protection. The magnetic suspension support extends the useful life of equipment, improves the operating conditions of equipment. It has broad application prospects in terms of transportation, machinery, appliances, materials, metallurgy, electrical, Material.
Abstract: Double patterning improves the development of immersion lithography, but it brings new challenges including the higher scanning velocity of wafer. In this paper, considering two typical injection types, the three-dimensional computational fluid dynamics model is developed to investigate the effect of injection parameters on immersion liquid during wafer scanning. By analyzing the velocity distribution of immersion flow and normal stress on the lens, the proper parameters of injection are proposed under the typical conditions, and the appropriate parameters which lead to effective renovation with low lens distortion are also given.
Abstract: In order to solve the flank concave problem of the rotary gear shaving cutter, a new worm type shaving cutter has been manufactured, which will be used on a gear hobbing achieving freedom shaving. And its tooth precision can reach 6-7 level. The main contents includes the worm normal section curve equation of the worm type shaving cutter involutes, the optimization of tooth fitting error and the linear fitting of the tooth curve of the normal section by the MATLAB genetic algorithm toolbox. According to GB/T6084-2001 hob series standard, the results showed that the error theory is less than 1/6 of the AA level.