Advanced Materials Research Vols. 538-541

Abstract: Cutting pick is a kind of widely-used consumptive mining tool. The traditional producing technics of cutting pick body is foundry, or machining after roughly forging, or machining directly from metal bar. By former technics, the property of products is poor, and by latter, the material availability is low and the cost is high. The patent technology for cutting pick body warm extrusion introduced in this paper can overcome all the disadvantages mentioned above. In this paper, by analyzing the characteristic of cutting pick body warm extrusion, adopting the principle of power balance to solve the approximate solution of strain forces, the approximate calculating formulas of extruding power are deduced. The main factors affecting on extrusion force are determined theoretically. This research can be used as basis to design tooling and choose proper equipment for this new technology.

Abstract: Forgings quality depends on the blooming processes and the deforming processes. The blooming processes are composed of upsetting and stretching, both of which influence the forgings quality very much. However, it is ignored. Methods are put forth to improve the forgings quality. It is surely of much significance.

Abstract: Mold flow software is used to conduct mold flow analysis of copier parts, simulate its filling and cooling process, and predict possible defects in the product design process in order to determine the formability of plastic parts and product quality. The optimal mold structure can be obtained by comparing different solutions so as to save production costs and improve product quality and efficiency.

Abstract: Using finite element method, the molten steel flow process in soft-contact electromagnetic continuous casting mold is simulated. The results show that the molten steel surface were affected by the electromagnetic force and shrink to the centre, near meniscus zone the flow velocity of steel increases and appears an obvious circumfluence, a large number of inclusion float and are absorbed by flux; on the other hand, the turbulent kinetic energy significant increases in circumfluence area, this exacerbates the reaction between flux and liquid steel, the initial size of the solidification organization are refined, and the surface quality of slab are enhanced.

Abstract: In this paper the explicit dynamic finite element method with the software of ANSYS/LS-DYNA to simulate the cold-roll forming process of special-channel steel sheet is studied, and it can reveal the forming rule, and analyze mechanical performance, which has specific theory significance and application value.

Abstract: The silicon aluminum alloy casting with the large, thin wall and high surface quality requirements is produced with the inversion pouring process of vacuum sealed molding casting. The quartz sand was dried by 30 (0.425, 0.300, 0.212 screen) groups water, and the plastic film was dried to soft at 60 ~ l00 °C and the vibration frequency of the vibration worktable was 50 Hz, and the amplitude was 0.5~1mm,and the vacuum degree was 0.040 ~ 0.075 MPa. The inversion pouring was driven by Hydraulic drive with 60 ~ 90 s filling time. The inversion pouring process with smooth gas discharge, reasonable temperature distribution and good shape of casting thin wall, which improves the liquid metal liquidity, the mechanical properties and surface quality, and meets the using requirement.

Abstract: Warm compacting behavior and sintering performance of 316L stainless steel powders were studied. Results showed that green density and strength of samples made in warm compaction were much higher than that in cold compaction. Under pressure of 700MPa, green density and strength in warm compaction were 7.01 g•cm^-3 and 30.7MPa, which were higher than cold compaction by 0.19 g•cm^-3 and 10.7MPa. When sintered in hydrogen-nitrogen atmosphere for 60 minutes, sintered density, tensile strength and elongation all increased with the rise of sintering temperature. At 1300°C, Sintered density, tensile strength and elongation were 7.42 g•cm^-3, 545MPa, 28.0%, respectively.

Abstract: Aiming at solving the problem of the complicated structure and difficult 3D modeling of cross wedge rollors, the article does some research on the 3D cross wedge die based on STL documents. In accordiance with the data of parametric cross wedge die, adopting the STL document format, aotomatically construct the 3D shape of the model, this method can increase the efficiency of designing the modeling of cross wedge rollors; since most CAM, CAE systems can read STL document, this method can speed up the CAE and CAM systems in order to provide 3D geomatrical model quickly.

Abstract: In the method that the oxygen-free copper strips are produced through undercurrent horizontal continuous casting-cold rolling process, there are some coarse grains, microscopic cracks, shrinkage, shrinkage and segregation defects in the oxygen-free copper strip billet, which debase the densities of the strip billet, and are the main reasons for rejected castings during machining operation. Through the orthogonal experiment of the technical factors in the casting process, the mapping model of artificial neural networks have been established using the data obtained in the experiments, which built the relationship among the densities of casting blank and technological factors. With the help of this model, the optimal casting conditions have been researched by using GA optimizations method and real experiments. The results show that micro-structure of castings was improved and the densities of the strip billets are enhanced.

Abstract: The effect of the Al₂O₃ additive on the densification behavior, microstructure and mechanical properties of the B₄C–xwt%Al₂O₃ composites sintered by means of spark plasma sintering (SPS) process were investigated. It was found that addition of Al₂O₃ improve the sinterability of B4C at temperatures between 1700 and 1800°C remarkably. The composite samples which with an addition of 4 wt% Al₂O₃ and sintering at 1750°C exhibits excellent mechanical properties (relative density: 98.82%, hardness: 90.6 HRA).