Advanced Materials Research Vols. 154-155

Abstract: This paper adopts area conversion method to measure the WC grain size manually, sets up a Fibonacci Sequence plane segmentation model based on the statistical data obtained, and studies the effect of the ratio of coarse WC grains to fine WC grains on dual grain structure cemented carbide. It is believed that when SWC (fine) / SWC (coarse) ratio is 0.382, theoretically speaking, the arrangement between WC grains is the tightest. Through investigating the effect of WC grain boundary fusion on its stacking density and contiguity, and the effect of the dissolution and precipitation of WC grains on SWC(fine) / SWC(coarse) ratio, and combining Li Guangyu’s random stacking structure of the cemented carbide theory, it expounds the formation mechanism of the dual grain structure cemented carbide—making a proper amount of fine WC grains fill in the gaps between coarse WC grains so as to increase the stacking density and contiguity of WC grains to the maximum degree, and to separate the accumulated Co-phase layer between coarse WC grains, so that the Co layer more evenly distributes among the fine WC grains.

Abstract: Immersion tin (I-Sn) coatings on copper were prepared in a stannous methanesulfonate bath with thiourea being the potential altering agent. The electrochemical displacement process was studied by the galvanic couple current method (GCCM) on an electrochemical workstation. The morphology of the I-Sn coatings were observed by field-emission-gun scanning electron microscopy (FEG-SEM). The I-Sn process can be divided into three stages: (i) rapid increase in galvanic current, (ii) sudden decrease in galvanic current after a peak current, and (iii) low or residual galvanic current stages. It is demonstrated that the galvanic current method is a useful and efficient tool to identify the optimum ending time of the immersion plating process. This optimum immersion time results in a smooth and conformal deposit with a fine grain size.

Abstract: Based on optimization theory, computer simulation and Virtual Manufacturing, the framework modeling of Virtual Assembly Production Line planning was built in order to solve its complex optimization. By planning static assembly production line, the static optimization solution can be obtained. Then, dynamic simulation planning of production line was put up in order to analyze and evaluate the capability of production line. Thereby, assembly planning can be improved and optimized more.

Abstract: A numerical control (NC) code program is usually generated by a complex CAD/CAM system, which does not include the value of the tool radius compensation. To increase the material machining accuracy within the permissible machining accuracy range, this paper presented the approach of the tool radius compensation for high-speed and high-accuracy material machining. The principle and method of the tool radius compensation were put forward and analyzed, the mathematical model of the tool radius compensation was deduced according to the correlative factors, and the algorithm of the tool radius compensation was constructed for high-speed and high-accuracy. The simulative and experimental results verified the feasibility and validity of the proposed approach.

Abstract: As a flexible manufacturing technique, Multi-point stretch forming (MPSF) is a suitable method for forming aircraft outer skin part. The traditional solid stretching die is replaced by the discrete multi-point die (MPSD), and the sheet metal is stretch-formed over the MPSD generated by serial adjusting mode or parallel adjusting mode. The MPSF can be used to form the parts of different shape and reduce the cost and leading time of stretching die fabrication for aircraft outer skin part. A series of numerical simulations on typical MPSF processes of aircraft outer skin part were carried out. The thickness of elastic cushion and free length are important factors to influence on the stretch forming results of stretch-formed parts. The numerical simulation results show that the thicker the elastic cushion is, the more valid the dimple will be suppressed .The longer the free length is, the easier the wrinkle will be brought.

Abstract: In order to investigate the mechanical properties of single crystal Cu nanorod with preset defects, the multiscale unixial tension simulation models of nanorods with two different crystallographic orientations are established. In two orientations, the dislocations are emitted firstly from the notch tip. The results show that the defect evolution, stress-strain curves and train energy vary with different crystallographic orientations. In setup, the deformation is ductile mode and it is fracture fashion in the setup.

Abstract: As reported in the previous report, increasing velocity by high-speed impulsive energy could improve the formability of AZ31 magnesium alloy. The improvement of ductility of AZ31 magnesium alloys can be observed, which is difficult to observe in usual cold forging techniques. This paper (Part II) is a coutinuation of the reported work in the previous paper. The forming of the AZ31 casting magnesium alloy was done. The hardness distribution of the test specimen was investigated for each experiment, and the microstructures are analyzed. The microstructural results indicate that adiabatic shear bands are formed and the microstructure is changed by the formation of huge amount of fine grained recrystallized structure. Furthermore, solid state is retained in the materials as well as the surface. [1]

Abstract: Brush plating has been an important technology for mending the scratched surface of the engineering parts in recent years. The duralumin alloy is common used structural material. The process for brush plating mending of deeply scratched surface of the parts made by 2A11 duralumin alloy is introduced, the technologic methods of 2A11 duralumin alloy are studied and analysed, the merits of the brush plating mending technology of 2A11 duralumin alloy are discussed in this article.

Abstract: With the development of the rapid prototyping manufacturing for ceramic parts, it is possible to shorten the manufacturing period of ceramic parts and improve the enterprise’s productivity efficiency. The development situation of the machine tools about rapid prototyping manufacturing for ceramic parts was introduced. A new-style device about rapid prototyping manufacturing for ceramic parts, which is based on the technology of laminated coalition and rapid concrete prototyping for ceramic parts, is designed. The basic constitutions, technical processing and working principle of the paving stock mechanism of the device have also been described. The PLC (programmable logic controller) is applied in the paving stock mechanism for controlling and runs well, which meets the requirements of automatic manufacturing for ceramic parts and improves the efficiency.

Abstract: In this paper, the two hybrid algorithms of back propagation artificial neural network and genetic algorithm were used in the optimum design of the hot pressing parameters of an advanced ZrO2/TiB2/Al2O3 nanocomposite ceramic tool and die material. Compared with the BP algorithm, the predicted results of hybrid algorithm indicated that the combination algorithm can offer a robust and efficient way for the fabrication process design of ceramic tool and die materials.