Key Engineering Materials Vols. 426-427

Abstract: The main purpose of this paper is to apply the extension method based on the spectrum of the vibration signal for motor mechanical fault diagnosis. The measured data of mechanical fault in induction motors are adopted to carry out the spectrum analysis and then establish the extension element model. According to the distance and the correlation function value concept of extension theory, one can calculate the correlation degree of various fault type and then determine the most possible category of mechanical fault in induction motors. Finally, some simulation and experimental results are made to verify the effectiveness of the proposed motor mechanical fault diagnosis method.

Abstract: The flyweight of powder metallurgy is a complex structure part of VE distribution pump. The components of the powder forming process often contain the defects such as instability of the quality, over tolerance of the size accuracy, and disqualification of the appearance. By analyzing the causes of defects and corresponding measures is taken. A once pressing compaction method is used to produce qualified products.

Abstract: A DLC/SEBS/A187/Si multilayer was prepared by self-assembled monolayer (SAM) method and pulse filtered catholic vacuum arc source (FCVA) technology. Microstructure and frictional properties of the film were investigated by using X-ray photoelectron spectroscopy (XPS), AFM, SEM and UMT-2MT tribometer. Results showed that the peaks appearing at 287.8eV for XPS demonstrated the successfully graft of SEBS on the couple agent(A187); The surface of the top DLC film was compactly and uniformly distributed; Friction coefficient of the prepared film was not sensitive to velocity under low load and the coefficient ranged from 0.1 to 0.15, but at high load, the tribological property of the film deteriorated with the increasing of sliding velocity, when the normal load was 2N and the sliding speed was 30 r/min, only the top DLC film was scratched out, but when the sliding velocity increased to 240 r/min, the whole prepared film was scratched out.

Abstract: Based on the analysis of feature parameters for the screw, presented the uniformed mode of the spiral surface with variable pitch and variable diameter, discussed in detail the formation of it with four-axis linkages of the machine. The major parts of the processing system was designed. CAPP of the spiral surface in special milling operation was put forward and successfully realized in the workshop, taking the operation of a screw head as an example, for premium quality.

Abstract: Based on the analysis of origination of the machining errors, and selection of major influencing factors - those errors rising from the machine tool, the fixture, and the cutting tool, the error signal source library was created at the sampling points on coordinates X, Y, and Z. By making use of the written knowledge and workshop experience, the library was extendable and built with technique of ADO database access. And virtual real-time presentation of machining errors on the machined surfaces was also constructed with a mathematical model of weighed random method, considering the error of the sampling points and the drifting of the sampling points themselves from the perfect position. And a virtual measurement system was formed for the test of errors of the machined surfaces of mechanical components programmed with Visual C++ 6.0and OpenGL 3Dgraphical library. An example of the step-shaft with five kinds of tolerances was given and has been shown that the virtual system with the extendable library of errors and model for weighed random method was practical. Such weighed random method presented well the real errors of processing operations on the field with the proper model showing the principle of the error origination in metal machining.

Abstract: To realize the constant pressure water supply, a frequency converter is used to control the periodic duty of three pumps in this paper. Then, the communication between host computer and field control equipment is studied and realized by using industry Ethernet Graphical control interface, and remote monitoring is realized.

Abstract: Special remelting techincs including repeating the heating and quenching process for several times, electromagnetic mixing during the melting, increasing the superheating temperature, prolonging isothermal time can effectively decrease or remove the effect of impurity in raw materials on the glass-forming ability (GFA) of the alloy system. These technics were introduced to improve GFA of Fe60Co8Zr10Mo5W2B15 alloys (△Tx = 64 K, Trg = 0.61, Trg’= 0.59). Bulk metallic glasses of Fe60Co8Zr10Mo5W2B15 with the shape of rods (φ3×40) and plates (1×10×20) were casted into fully glassy state. It was proved the GFA of Fe60Co8Zr10Mo5W2B15 with industrial raw materials is very close to that with high purity raw materials. Fe60Co8Zr10Mo5W2B15 bulk metallic glass with industrial raw materials shows better potential appliance for their low cost.

Abstract: This paper focuses on the effects of heat source profiles during thermal analysis of grinding. Three different models of heat source, namely triangular model, parabolic model and elliptic model, have been suggested and their numeric formulas are provided. These models take into account of the variation of heat flux along the contact zone, so as to improve the accuracy of numeric results. Finite Element Analysis (FEA) is utilized to investigate the temperature distributions under different thermal models and the effects of two profile parameters (η and ξ). The result is a) peak temperature decreases as η increases and the location of peak value moves backwards simultaneously; b) peak temperature decreases as ξ increases and the location of peak value moves forwards simultaneously.

Abstract: Flakes with a size of 20×4×0.8mm3 and rods of (Fe68B25Nd7)96Nb4 bulk metallic glass (BMG) with a diameter of 1.5 and 3mm were cast. Rods a diameter of 1.5 mm were proven to be XRD amorphous. High vacuum environment during the fabrication will benefit the formation of fully amorphous BMG. The super-cooled liquid regions of (Fe68B25Nd7)96Nb4 is 59°C and the reduced glass transition temperature is 0.624 indicating good glass-forming ability. The critical cooling rate for glass formation for (Fe68B25Nd7)96Nb4 melt is about 294°C/s by computer simulation (Fe68B25Nd7)96Nb4 BMG shows soft magnetic property while partially crystallized sample shows hard magnetic property.

Abstract: To explore machining properties of the EDM in gas basically, thermal fields of single pulse discharge in gas and liquid were analyzed by FEM software ANSYS. Crater size and thermal strain graph affected by instantaneous high temperature owing to single spark were simulated. They can provide references for optimizing parameters of comparative experiments of single pulse EDM in liquid and gas.