Advanced Materials Research Vols. 443-444

Abstract: In order to maintain the synchronization between the development of total control system of product line and the manufacturing of hardware devices, virtual designs and simulation technologies have been utilized and virtual product line has been built, which was used for developing the total control system that was based on EtherCAT technology and was for distributed processing. First, according to the characteristics and structures of hardware devices, mathematical models were built up. Then, device simulation system and total control system according to the mathematical models of devices have been developed, and also discussions have been made on the synchronous control of product line and the dynamic setup of working procedures in the total control system. Finally, the characteristics of the system have been tested and analyzed in the following two aspects: data acquisition and system response.

Abstract: The mechanical properties of a new Zr-based bulk metallic glass at low temperatures were investigated. The results indicate that the fracture strength increases significantly (4.9%) and the global plasticity increases somewhat when testing temperature is lowered to 123K. The stress-strain curve of the sample deformed exhibits more serrations and smaller stress drop due to formation of more shear bands at low temperature than at room temperature.

Abstract: The application of powder particle size measurement in engineering field are introduced, the major powder particle size research methods are also included. Furthermore we analyzed the characteristics of these methods. Based on these, we proposed a method, which makes full use of Matlab to process and analyze the SEM image of powders to get powder particle size and the distribution, and the method achieve a good effect. Finally, In order to verify the processing method, the authors performed an example of the approach. Based on the results, it can be confirmed, therefore, the method using MATLAB is convenient to analyze the powder particle size.

Abstract: In this study, high-purity Li₂CO₃ was prepared by carbonation-decomposition and ion-exchange methods using the industrial-grade lithium carbonate, and the effect of cycles and ion-exchange of the mother liquor on purification was investigated. Results showed that the process of cycles can improve the purity and productivity of Li₂CO₃. The impurities (such as K, Na, Ca and Mg) could be removed in the process. The purity of product decreased and the impurity contents increased after 4 cycles. At the same time, the ion-exchange process by D412 resin was used to deeply remove the residual Ca and Mg after the simple carbonation-decomposition and cycle process. The comparison of different flowing speed of solution through the ion-exchange resin indicated that the low flowing speed was beneficial for the deep removal of the Ca and Mg. considering the problem of efficiency, the flowing speed of 10-20 ml/min was appropriate. The high purity and productivity of Li₂CO₃ indicated that the carbonation-decomposition method combining with the mother liquor cycles and ion-exchange method has a good perspective in the field of lithium carbonate purification.

Abstract: In this paper, the forming processes, main effect factors and change law of the cutting direction burr in orthogonal cutting have been studied and related theories are analyzed based on the cutting experiments. The result shows that the forming processes of cutting direction burr consist of normal cutting, flexure deformation of end surface of workpiece, plastic effect, continuous cutting and shear-break separating in orthogonal cutting. And a new phenomenon was found that cutting direction burr is formed with the shear-break separation of the chip and workpiece machined surfaces. In addition, the size of cutting-direction burr varies with workpiece materials, cutting parameters and geometric parameters of cutting tool. The study may be important science and practical value in order to control and reduce cutting burr in precision machining.

Abstract: The Cemented carbide cutting tool is widely used in more machining factory, the 5 types of cemented carbide materials: YT30+Ta, YTS25, YH1, 726 and 758 and Selected to make brazing and cutting test. The experiment results shown that: (a) the hardness of cemented carbide cutting tool after being brazed does not change, redoes HRA0.1~0.2; (b) YT30+Ta, YTS25 types of cemented carbide could be brazed using 105# solder, brazing quality could be very well; (c) Wear characteristic of machine-clamping and brazed cemented carbide cutting tool is normal and hardly change in T<150 minutes. The study makes theory and experiment foundation to widely use cemented carbide cutting tools.

Abstract: In order to improve the reliability of automatic mechanical transmission (AMT) system, brushless DC motor was employed as the gear shift actuating mechanism of AMT instead of brush DC motor. Hardware circuitry and software programs of electronic control unit (ECU) were designed. Bench test was conducted and experimental results indicate that the design of gear shift actuating mechanism based on brushless DC motor meets the requirements of practical application and improves the reliability of AMT system.

Abstract: The paper studies the linear vibrating mechanical behaviors of double-walled carbon nanotubes (DWCNTs) with the initial axial stress under the temperature field. The DWCNTs are modeled as double elastic shells coupled together through vdW interaction between inner and outer nanotubes. Based on the model, the relation between the amplitudes and the frequencies of the tubes is achieved. The results show that the initial axial stress could crucially affect the existence of the natural and intertube frequencies. Meanwhile, it is also concluded that the temperature change is significant for natural frequency, but weakly affects intertube frequency and amplitude ratios.

Abstract: In the process of milling thin-walled plate, chatter is one of the major limitations on productivity and part quality even for high speed and high precision milling machines. Therefore, it is necessary to avoid chatter with a suitable choice of cutting condition. This paper studies the dynamic stability models of milling the thin-walled plate by analyzing the geometrical relationship of cutting, and derives the mathematic expressions in theory. Moreover, this paper develops a three-dimensional lobes diagram of the spindle speed, the axial depth and the radial depth. Through the three-dimensional lobes, it is possible to choose the appropriate cutting parameters according to the dynamic behavior of the chatter system.

Abstract: The paper presents a new improved method for structural dynamic reanalysis with large change in structure topology possessing added degrees of freedom (DOF). The method，which is based on twice reduced model of original and topological structures, combines independent mass orthogonality and Rayleigh-Ritz analysis. Two numerical examples were used to show that the presented method can provide efficient and high quality approximation result for eigenvalues reanalysis when large modifications of the structural topology are made.