Advanced Materials Research Vols. 97-101

Abstract: Based on the character of plate rolling, the temperature model was developed by considering the influence of radiation, convection, water descaling, and roll conductivity and deformation energy. The factors affect the finishing temperature of the plate were analyzed, including the holding time during control rolling, rolling speed, slab temperature and pass number. Holding time, rolling speed and slab temperature have significant influence on finishing temperature, and pass number has great influence on finishing temperature of thick plate, but has little on finishing temperature of media plate.

Abstract: This paper proposes the validity of a Gabor filter bank for feature extraction of solder joint images on Printed Circuit Boards (PCBs). A distance measure based on the Mahalanobis Cosine metric is also presented for classification of five different types of solder joints. From the experimental results, this methodology achieved high accuracy and a well generalised performance. This can be an effective method to reduce cost and improve quality in the production of PCBs in the manufacturing industry.

Abstract: Based on hydrodynamic lubrication theory, a mathematical model of grinding fluid field in flood is sets up in this paper. Hydrodynamic pressure and velocity of grinding fluid are calculated by multigrid method. Additionally, crude model about the coarseness of grinding wheel and workpiece is built on the basis of slick model and solutions are obtained by multigrid method. Solutions of slick model and crude model are compared. Result shows that the solution of slick model is in good agreement with the crude model and verifies the experimental analysis.

Abstract: A physics-based material processing simulation is approached to research the machining distortion for titanium alloy aircraft monolithic component by the finite element method (FEM). Several key technologies, such as material constitutive model, material removal methodology of machining process, determination and application of cutting loads, have been implemented to improve the accuracy of finite element simulation. To verify the FEM result, an experiment is carried out. The distortion position and dimension of aircraft monolithic component resulting from FEM show a good agreement with the experiment result, which indicates that the key technologies presented in the paper are practicable and can be used to simulate the machining process of monolithic component to predict its distortion.

Abstract: Asymmetrical rolling is usually used on some special rolling produce. It offers lower rolling pressure, more reduction and better crystallographic textures. In recent years asymmetrical rolling has become more important due to realization of improved properties of the strip. In this paper, a elasto-plastic finite element method code has been developed to simulate the asymmetrical rolling of strip, considering unequal roll radii, unequal speed ratio between the upper roll and lower roll, different exit thickness and different reduction. Meanwhile, The profile, crown and edge drop of strip, as well distribution of front tensile stress were discussed in different rolling process. It makes better preset values for the online control system and good results was obtained.

Abstract: This paper reports a study on oxide film formation mechanism in electrodeless ELID grinding. The formation mechanism of oxide film was analyzed based on electrochemical principles, its formation model was built and the growth process was also simulated. The simulation results showed that the oxide film thickness h and its growth rate g are nonlinear functions of time t, voltage and duty cycle are important factors which take effect on g and h, and the electrodeless ELID grinding is a process of weak electrolysis and suitable to use micro wheel.

Abstract: The lens molding technology has become a promising fabrication method for glass lens, especially for aspheric glass lens in batch. Because during the real compression molding, the error compensation for mold shape turns very difficult, the mold needs to be repaired repeatedly to meet the requirements of lens molding. To solve this problem, a cooperative design scheme is proposed. However, the scheme is not limited to solving the mold repairing; it also aims to providing the integrated and optimal design for aspheric glass-lens mold. In fact, the cooperative scheme is a collaborative software platform, which integrates with data processing, optical design, finite element analysis, error compensation and mechanical design for lens molding. On this platform, users only need to submit the (camera) lens parameters or measured data of aspheric lens, and then the platform can provide the final mold drawings, which will be input in the CNC software of ultra-precision machine and guide the mold fabrication. Meanwhile, the cooperative platform is Network-based PDM system, so designers could remotely communicate with it and help to finish the mold design jointly. In this case, the cooperative design could tremendously improve the efficiency and accuracy of lens molding.

Abstract: The critical overburning temperature of chromium forged steel was experimented and discussed by DSC method and metallographic analysis of heat-treatment samples. Temperature increase during forging process and effects of some alloying elements on overburning temperature were simulated respectively by using Deform-3D and Thermo-calc software. The results of linear regression analysis showed that increased temperature has a prop relationship between volume and rate of forging process. Besides, a monotonic decreasing relationship is found between the content of alloying elements with overburning temperature in the scope of the composition of chromium forged steel. It is found that carbon has the major effect on the overburning temperature.

Abstract: This paper proposes a semi-analytical method for the prediction of rolling force for rod rolling. The grooves of the passes are oval-round and round-oval. The mathematical model of rolling force is based on Shinkura and Takai’s model, but incorporates the effects of recrystallization and the alloy elements. Hot rod rolling experiments are conducted to examine the proposed semi-analytical method. The predicting values are compared with the mill log data, and they agree excellently over the whole rolling course. The predictions indicate that recrystallization affects the resistance of the material during hot rod rolling.

Abstract: In order to increase the efficiency of machine tools, the development of machine tools is toward higher speed and accuracy. The higher speed of spindle causes more thermal deformation, which reduces the accuracy of machine tools. In this study, finite element method is used to simulate the thermal deformation of spindle caused by the friction loads between spindle and bearings. The bearing load is estimated by the basic load rating from the bearing vendor and the required life of bearing. The simulated results are compared with experimental measurements to verify the analysis model. The result shows that the stabilized temperature of spindle increases as the speed increaser, while the stabilized displacement of spindle slightly increases as the speed increases.