Materials Science Forum Vols. 800-801

Abstract: Micro-channels are widely used in many fields. There are a lot of burrs in the process of micro-channel machining, which affect the performance of micro-channels. In this study, some polishing experiments are conducted for the burr removal of micro-channels by the micro slurry jet on the home made micro slurry jet machining system. The morphology and the roughness of the micro-channels are measured. The factors to influence the burr removal and the micro-channel surface quality are analyzed in order to take measures to improve the surface quality. The results show that the micro slurry jet polishing not only removes the micro channel burrs, but also improves the micro channel surface quality. It is helpful to increase the flow of medium inside micro channel.

Abstract: Micro tools play an important role in micro/nano maching and their geometries should bedesigned according to the specific workpiece material to get the requested maching quality [1]. LiFis a kind of soft brittle crystal and has been widely used as nuclear fusion target on which microstructures should be milled. This paper designs two types of straight-edge end milling tool specialfor LiF milling. Firstly, depending on the former tools designed, the critical disciplines for microtool design is provided. Secondly, two types of ultra-hard milling tool of 1mm diameter is designedaccording to the disciplines mentioned. Then FEM model is established and optimizationalsimulation is conducted to get the proper tool geometry angles.

Abstract: Laser-assisted machining (LAM) is a hybrid cutting process in which a laser beam is used to heat and soften the workpiece locally in front of the cutting tool edge. The rapid temperature rise at the shear zone reduces the yield strength and work hardening of the workpiece, which makes the plastic deformation of difficult-to-machine materials easier during machining. LAM provides a reduction in the cutting forces/specific cutting energy, longer tool life, better surface integrity, and high productivity over traditional cutting. This paper presents the technical characteristics, material removal mechanism and the application of machining hard-to-machine material in LAM. The latest development of LAM and future scope are summarized in this paper.

Abstract: In order to solve the problem that delamination and bur will be easily produced in the process of the carbon fiber reinforced plastic (CFRP) composites, the cutting experiment of CFRP machined by pulsed Nd:YAG laser has been carried out. In the meantime, this paper investigates the mechanism of interaction between infrared laser and CFRP composite material and the quality of kerf influenced by different laser parameters and cutting directions. The study found that choosing appropriate laser parameters and cutting direction are effective means to get smaller heat affected zone (HAZ). This paper analysis the cross section morphology of kerf .The results show that the cross section does not appear stratified phenomenon and the surface is smooth, so the feasibility that infrared laser can be used to cut CFRP composites is verified.

Abstract: A new process of fabricating microstructures through micro electrochemical milling (micro EC milling) is proposed. The experiment equipment with a new type of ultra-short pulse supply was developed for micro EC milling. By controlling the movement track of simple micro tool electrode rotating at high speed on NC three-axis feed worktable, microstructures with high precision can be milled by micro-ECM under ultra-short pulse current. Micro EC milling can greatly improve the machining status in the tiny machining gap and thus make machining stable by simple rotary column electrode. The process of the NC generating micro-ECM integrating CAD/CAM technology is studied. G code for machining complex microstructures can be generated by the universal CAD/CAM of traditional milling based on UG software. Last, Microstructures with high precision were milled by this process, for example the micro trench with width of about 50μm.

Abstract: Numerical simulation to the temperature of laser cladding can simulate the process of its technique, which can also optimize the parameters of the technique and predict the defects of the cladding. In this paper, a three-dimensional finite element powder-feed laser single cladding model of the transient temperature field was built based on APDL in ANSYS, where the Gaussian distribution of heat source, forced convection heat transfer and the motion of laser heat source are simulated .The results reveal how the main technique parameters affect the distribution of the temperature, and make a prepare for the experiment of laser cladding.

Abstract: Magnesium alloy has widely been used in automotive sector due to its light weight, low density, high stiffness, and excellent casting performance and easy to recover and utilize. The magnesium alloy automotive engine cylinder cover was chosen as researching object to simulate its die casting filling process based on die casting filling process theory and numerical simulation analysis software JSCAST. The simulation results show that the utilization of die-casting simulation software for improving product quality and production efficiency has certain significance during the production of magnesium alloy die casting process.

Abstract: The performance of the micro nozzle is determined primarily by its machined surface topology and geometric profile. A circular cross-section micro-Laval nozzle is modeled and studied by using numerical simulation in this paper. The real residual height and residual area of machined nozzle surface with ball-end milling cutter are proposed. A micro-Laval nozzle was machined successfully. It is found that the ball end milling cutter with large radius is suitable for finishing operations in the viewpoint of nozzle performance. Moreover, the serial process of drilling and milling has been proved by experiments with which both high-level machining accuracy and performance can meet the nozzle requirement.

Abstract: In the paper, a new polishing head is researched and developed. How to set a magnetic feild is a key factor in magnetic-electrochemical compound polishing. To add a magnetic field that is parallel to electrical field, the electrochemical reaction can be changed greatly. Additionally, to add a magnetic field whose direction is changed to and fro, the efficiency of the polishing can be improved especially. In order to adapt to this theory, a new polishing head in magnec-electrochemical compound polishing is required resarch and development. Furthermore,the tool can be fixed on spindle of CNC easily and the tool is flexible so it can make the polishing head and workpiece touch evenly each other. Especially being noticed, the head of magnetic-electrochemical compound polishing tool is a series in order that the head can be replaced conveniently according to different surface. At last, the tool is tested and its function is perfect.

Abstract: With the recent development of domestic hydropower industry, length, weight, size, material and structure of the rotor machining of large motors and generators manufactured workpiece special processing equipment and process methods have become increasingly demanding, aiming at market high precision, good quality, technical indicators have a good guarantee of the large rotor machining center with plenty of needs static frame, developed a long piece, big weight, material and structural special processing equipment. This equipment has proven high accuracy, good quality, technical indicators have a good guarantee to solve practical problems that exist in the above production. The large hydrostatic rotor machining center frame, not only to solve the large generators, turbine rotor shaft heavy machining of technical problems, but also to ensure the accuracy and stability of the product processing.