Flexure hinges have been widely used as mechanisms for high precision positioning stages that have a micrometer or nanometer resolution. This paper describes the analysis of a 3-DOF rotationally symmetric hinge for the vertical mask aligner stage. The vertical mask aligner stage was designed to overcome the bending of masks by gravity. In order to align the mask and the wafer, the vertical mask aligner stage has one linear motion and yaw rotating motions (Z, Θx, Θy). The new vertical mask aligner stage will try to use rotationally symmetric hinges. These rotationally symmetric hinges would act as guide mechanisms. However, the exact 6-DOF stiffness analysis of the rotationally symmetric hinge did not use these hinges as guide mechanisms. Therefore, this paper focuses on the stiffness analysis of the rotationally symmetric hinges.
According to the recent rise in oil prices, interest in FCC Unit (Fluid Catalytic Cracking Unit) energy recycling is increasing. Such FCC Unit is a facility which refining low-valued bunker C oil into high-valued gasoline. Pressure vessel that refines crude in FCC Unit needs various interpretation because it operates under high-temp and pressure. Our concern about this FCC Unit is increasing. Experiments about its safety is not enough. In this paper, whether FCC Unit has structural stability or not, we found out FEM(Finite Element Method) analysis after trying 3D modeling by using FCC Units condition of design and critical stress as a translating data. First, we researched the safety of structure applying external factors using the natural frequency. The structure is safe from modal analysis result, the first natural frequency is 13.614Hz , beyond the of the frequency range of the wind (0.001~8Hz) and earthquake (0.1~10Hz).
The propeller shaft of rear-wheel drive vehicle is an axis which transfers power from an engine to rear-wheel through differential gear box. In this study, we studied the properties of friction welding required to produce the aluminum propeller shaft of lightweight rear-wheel-drive vehicle. We studied welding property to apply Al 7075-T6 aluminum yoke to automobile connects driving shaft and differential gear box. Here, solid phase friction welding method was used. In friction welding process, the principal parameter is spindle speed, up-set pressure and up-set time. We analyzed variable characteristics of friction welding strength according to the change of the spindle rate and up-set pressure. Friction welding strength was analyzed with ultimate tensile strength test with universal testing machine (UTM). The Al 7075-T6 was used as the round bar of the diameter of 25mm. The ultimate tensile strength was 552.3 MPa. It is 94% of ultimate tensile strength of pure Al 7075-T6 material. The main parameters of characteristics are discussed in detail based on analysis of the main effects plot and multi-vari chart. Finally, the core factors to get the maximum effect of friction welding investigated.
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