Advanced Materials Research Vol. 548

Abstract: Electrochemical Micro-Machining fields the solution for the challenges posed by future micro and nano machining technique as it offers innumerable advantages. The electrochemical micro machining can effectively be used for high precision machining operations. Intended for micro fabrication of TiGr5 based components like Nozzle Plate for Ink Jet Printer head and delicate 3D -electronic circuit board components, and components of avionics, the electrochemical micromachining is primarily employed. In this research study, an attempt is being made to evaluate and access the influence of machining parameters namely the voltage, current, electrolyte concentration and pulse on off ratio on the Radial overcut, and Machining Time during drilling of micro holes in 0.5mm thick TiGr 5. Preliminary investigations are carried out to create an optimized parameter window that defines the operating range of the governing parameters. Further, a central composite factorial experimental design technique is being applied to determine the optimal combination of the machining parameters level. Response surface methodology is used to determine the influence of the varying input parameters on the output product features.

Abstract: Multi-axis CNC machining shows great advantages in manufacturing parts with geometries being defined by complex surfaces. NURBS (Non-Uniform Rational B-Spline) interpolation and polynomial interpolation are two new types of interpolation to improve productivity. Compared to the NURBS interpolation, the polynomial interpolation can gain higher productivity. However, no commercial software tool is available to generate polynomial interpolation CNC programs. This paper proposes a postprocessor to generate polynomial interpolation multi-axis CNC program. A case study with simulations demonstrated that the polynomial interpolation program generated by the proposed postprocessor has higher machining efficiency than liner interpolation and NURBS interpolation program.

Abstract: In order to achieve simulation validation before machining and optimization for the processing, the vertical NC miller machining simulation system based on VERICUT was built on. Analysis showed the framework of simulation system, and researched the implementation processing of simulation system from the built of virtual machine model, setting of virtual processing environment, configuration of simulation and etc. Finally, a simulation machining instance was given by applying this system, and NC tool path was also been optimized which played a good effect.

Abstract: By using the information entropy theory, a solution to Weibull-small sample prior distribution of system reliability is proposed, which aims at solving the reliability estimation of high-end CNC. Firstly, the prior information is converted from subsystem level into system level based on entropy theory. Then, the prior distribution is solved with the constrained maximum entropy method. Finally, multi-information is fused based on the entropy weighs. It is proved by a case example that this method can obtained the prior distribution under Webull-small sample effectively.

Abstract: In order to manage equipment maintenance work and reduce enterprise cost, a new prediction method of reliability parameters is proposed based on failure time in this paper. The reliability model was built based on failure time, and the reliability parameters were obtained by the empirical modeling method. Then parameters from historical data were used as predictive model parameters, which applied the exponential smoothing methods to establish predictive models based on historical data. Finally, prediction model of reliability was built by the predicted parameters used the above method. With failure data of CNC machine tool as an example, analysis of living example indicated that the proposed method acted effectively, and the precision of prediction is quite ideal, which help consumers of CNC machine tool provide the decision support of equipment maintenance management; meanwhile, strengthen the enterprise's competitive power to some extent.

Abstract: The effect of using Cr12MoV steel made by Wire Electrical Discharge Machining (W-EDM) for electrical silicon sheet punches was characterized and investigated. The surface roughness and HRC of the samples so prepared was examined. Wear resistance of the Cr12Mov for punch by W-EDM treatment was assessed by measurement of weight method. The results show that the W-EDM parameters influence the punches’ wear resistance and wear weight loss was influenced by hardness loss greatly.

Abstract: The nonlinear blind source separation is a practical and effective method in processing mechanical vibration signal, but it has the limitation which learning rate is fixed. It will take a long time for iterative parameters to get convergence. In this paper, a variable rate nonlinear BSS is proposed. The learning rate of the algorithm is adjusted based on iterative error in the different stopping iterating time and inverse proportion. The proposed algorithm increasing the efficiency of the nonlinear BSS and de-noising the vibration signals. Experiment on gears shows that the signal gained by the method more impersonality represents the gear condition

Abstract: Through the field test of Mayanpo slope at Xiangjiaba Hydropower Station, external deformation, deep deformation, groundwater level and stability of the slope with weak interlayer are analyzed in this paper. The results show that: ① displacement deformation increases with time and decreases with increasing depth. Changes of displacement can be divided into three stages: deformation rapidly increases in the early, and slowly increases in the medium, and becomes gradually stable in the later. Changing rate of displacement decreases with time, and the rate can also be divided into three stages, basically consistent with the displacement changing stage; ② a certain thickness of weak interlayer and evident dislocation exists in slope strata. Dislocation rate first increases and then decreases until basically stable, and local fluctuation is mainly affected by rainfall and dynamic equilibrium adjustment of the slope internal deformation; ③based on the penalty function contact of pile soil and the surface of rock mass, the three-dimensional numerical model of coupling of seepage and strain has been established, and through analyzing and comparing with field test data, it is verified that the model is feasible in the study on slope deformation; ④ through stability analysis of Mayanpo slope by strength reduction FEM, stability coefficient is 1.72.

Abstract: Aircraft alternator is in the central position of the aircraft AC power system. The existing troubleshooting process is complex and tedious. In this paper, the aircraft alternator fault tree is established, and a fault example of under-voltage condition is analyzed in-depth qualitative and quantitative. According to the importance degree, the order of troubleshooting is obtained, making the fault diagnosis fast and effective. In order to overcome the limitation of the fault tree analysis, case-based reasoning is combined, making the fault diagnosis more comprehensive and accurate.

Abstract: Different from the reliability prediction method on handbook, the reliability prediction method based on Physics of Failure (PoF) model takes failure mechanism as theoretical basis, and combines the design in-formation with the environment stress of the product to predict the time to failure. When the uncertain of the parameters is considered to predict the reliability, Monte-Carlo calculation method is always used here. How-ever, the Monte-Carlo method needs large computational cost, especially for large and complicated electronic systems. A new reliability prediction method which combines the first order reliability with the reliability pre-diction method based on PoF model was proposed. The new method utilized the first order method to calculate the position of design point and reliability index, thus Monte-Carlo calculation process was avoided. Example calculation results showed that the new method improves the prediction efficiency without decreasing the accuracy of reliability, thus it is feasible for reliability prediction of electronic product in engineering.