Key Engineering Materials Vols. 426-427

Abstract: The cutting force in manufacture process was observed with Kistler dynamometer. A special clamp was designed to simulate the real condition of blade cutting. Series of experiments were done. Cutting force reflected structure of the blade and movement of machine. Cutting force was changed with feed speed varied and the rotation of axis B & C. Resultant cutting force was uniform in back and basin of blade and increased with cutting speed went up. Resultant force was waved in edge of blade. Back and basin forces were lager than edge force in X direction. Force X invoked vibration.

Abstract: Using OptiStruct as the tool of optimization, the topology optimization of one special carriage’s square cabin is studied. The methodology of structural topology optimization is present and the key technology is discussed. the weight of the top-placed facility pedestal is set as the optimization objective,and its optimization model is developed. The establishment method of the optimization objective function, design variables and constraint condition are introduced. Through optimization calculation, the result of topology optimization is analyzed. The conclusion provides a significant researching basis for lightening the weight of cab.

Abstract: Grinding processes are mainly technique employed widely as a finishing process in a variety of materials, such as metals, hardness and brittleness and ductile materials machining to achieve good dimensional and form accuracy of the product with acceptable surface integrity. However, grinding is associated with high specific energy requirements which may be an order higher than that required in other conventional machining processes such as turning, planning, milling etc. Therefore, in grinding process, high grinding zone temperature may lead to thermal damage to the work surface, induces micro-cracks and tensile residual stresses at the ground surfaces, which deteriorate surface quality and integrality of the ground surface. Therefore, grinding fluids are applied in different forms to control such high temperature, but they are ineffective, especially under high speed grinding conditions where the energy of the fluid is not sufficient to penetrate the boundary layer of air surrounding the wheel. Moreover, the conventional flood supply system demands more resources for operation, maintenance, and disposal, and results in higher environmental and health problems. Therefore, there are critical needs to reduce the use of cutting fluid in grinding process, and cryogenic cooling grinding is a promising solution. The work presented in this paper aims at evaluating the grind ability and surface integrity of the nickel base super alloy resulting from the application of cryogenic cooling.

Abstract: The article discusses the application of MSA in the process of quality control of production, under the relevant requirements in ISO/TS16949. With DWST experimental platform of large electronic current as an example, it analyzes the data achievement, the application of statistics and the methods of analysis report in the evaluation of variations on bias, stability, linearity, repeatability and reproducibility. The research gives a guide to the effective implement of MSA in the production and manufacture.

Abstract: The problem of the parametric sensitivity of fuzzy reliability analysis was discussed in this paper. Firstly, based on the concept of cut-set of fuzzy mathematics, a computational model is introduced. Then, the expression of cut-set of fuzzy mathematics is built in the case of normal random stress and normal fuzzy strength, and the effect of each parameter is analyzed. Finally, a simulation method is given to obtain the numerical solution of parametric sensitivity, and its validity is proved successfully by an example.

Abstract: Taking the mechanics characteristic of electromotor, the mass of slide and the sliding friction into account, the resolving calculating formulae for the kinematics and dynamic analysis of bull-nose plane six-rod mechanism is educed based on the dynamics principle. The disposing method of friction force operation direction is proposed. The computing simulation of this mechanism shows that the speed fluctuation would be aggrandized with the friction considered and the periodic change of friction force direction would be presented in the periodic change of acceleration. At last, the adding flexible component for the computing simulation near to actual movement is pointed out.

Abstract: Loci were studied of the lips movement with axial vibration for both non-disjunction and dis-junction pattern of the twist drill, with the proof that for the dis-junction pattern the chip might be broken by the special loci of the lips without any additional external forces. Positions of the same two points on the two major cutting edges were presented in detail with the rotation angle between the two points, 180 deg. Difference of the two loci, h, was the chip thickness that altered instantly and when it was zero the chip broke. Minimum difference hmin was taken as a criterion for vibration drilling pattern. Non-disjunction pattern of vibratory drilling came out when hmin ＞0 and disjunction pattern arrived otherwise. Expressions for the two patterns showed that vibratory parameters and cutting parameters have influenced h considerably.

Abstract: Laser drilling is extensively used in the aerospace and aircraft industries. The most important application is the drilling of fine cooling holes in aero turbine engine components such as nozzle guide vanes and blades. However, laser-drilled holes are typically associated with a number of inherent defects such as recast layer and spatter. In order to solve these problems, a novel hybrid process of laser drilling assisted with jet electrochemical machining (JECM-LD) has been developed to improve the overall quality of laser-drilled holes. The process based on the application of a jet electrolyte, being aligned coaxially with the focused laser beam, on the workpiece surface. The effects of the jet electrolyte during the process mostly consist of electro chemical reaction, effective cooling with materials and transporting debris. A pulsed Nd:YAG laser with frequency doubling is used in the JECM-LD experiments. On the basis of a measurement of laser attenuation in electrolyte, an experimental apparatus system is built and JECM-LD experiments are performed on 0.5mm thickness nickel-based superalloy sheets with the system. The optical microscope is used to detect the experimental results. It is found that the recast layer and spatter have been effectively removed during the JECM-LD compared with laser drilling in ambient atmosphere conditions. The efficiency of JECM-LD with millisecond green laser is about 70% of laser drilling in air.

Abstract: Based on the vacuum plate glazing produced in laboratory, the residual stress field of seal edge in vacuum plate glazing caused by heat load was researched by electrometric method, and the distribution of residual stress field were successfully measured. The residual stress field of seal edge in vacuum plate glazing was analyzed by numerical calculation, and then the established mathematical model was solved by finite element method and distribution rule of its residual stress was obtained. The effect of linear expansibility and coupled stress of the solder in seal edge on the residual stress of vacuum plate glazing was discussed. The result showed that calculated and experimental results were similar. The relation between intensity of residual stress and elasticity modulus was obtained. The theoretical principle was provided for analyzing allowable value of the residual stress of seal edge in vacuum plate glazing.

Abstract: The crater diameter and depth of the surface machined by electrical discharge machining (EDM) were used to evaluate indexes for EDMed surface. The influence of discharge parameters selected on the crater diameter and depth in mirror-like surface EDM process was investigated, and the optimization scheme was obtained. An L16 (44×23) Taguchi standard orthogonal array was chosen for the design of experiments. Experimental results indicate that peak current and open discharge voltage have more influence on the crater diameter and depth in comparison with pulse off-time and pulse duration. Also the results confirm that the crater depth is about 10 to 20 percent of its diameter while the near-mirror EDM conducted in the NAK80 steel with fine discharge parameters.