Advanced Materials Research Vols. 538-541

Abstract: In general, the thin-walled casting with the thickness less than 2mm is not easy to be prepared using low-pressure die casting (LPDC) technology because of its poor filling-ability. In this paper, the LPDC process of A356 thin-walled aluminum alloy was simulated based on the selection of appropriate boundary conditions in order to save the cost. The simulation results compared with experimental results indicate the numerical simulation technology is an effective tool for reducing the manufacturing cost and improving the casting quality.

Abstract: In this paper,a kind of 3-UPU spatial parallel mechanism is introduced. Through deep analysis of the degree-of-freedom (DoF) for the platform using screw theory， the position and orientation of the moving platform is discussed. At last, the 3D virtual prototype modeling of this 3-UPU parallel mechanism based on software ADAMS is developed; the kinematics simulation and analysis are also carried out accordingly. From the simulation results, we can see that the proposed calculation of the DoFs and kinematics analysis is correct.

Abstract: The best is to read these instructions and follow the outline of this text. The coal mine production safety is one of China's current problems to be solved, do a good job monitoring and control of underground gas and coal dust is a key link to achieve safety in production. In this paper, the programming model is used to find the best ventilation rate and then control the mine gas and coal dust concentration effectively. Based on “Coal Mine Safety Regulations” and characteristics of coal dust and gas explosion with the relationship of mutual influence, we come to the possibility of coal mine explosion hazard. Finally, with the linear regression knowledge, we figure out the relationship between the wind speed and concentration of gas and coal dust, then we express the gas density and dust concentration in different parts of the mine by air volume function, through the limit of safe production on the gas concentration and coal dust concentration, to find constraints on air volume, construct a linear programming model, finally get optimum ventilation rate and the optimal control method.

Abstract: The numeric simulation of effect of X-shape submerged nozzle on flow of molten steel in a mold for 160mm×160mm concasting billet has been carried out by viscous fluid mechanics theory and CFD software Fluent. It was verified that during pouring with X-shape submerged nozzle, the vortex molten steel entering into mold by guide of vortex guidance channel which was formed with top and bottom surface of two semioval flow guidance plate and invert taper pipe to availably reduce impact depth, promote inclusion and gas bubble aggregating and floating off, and improve concasting efficiency.

Abstract: Hydraulic excavator is a typical and complicated engineering machine by combination of mechanical, control and hydraulic system. It is very important for coupling analysis by use of multiple simulation tools. Hydraulic excavator mechanical model was constructed based on Pro/E 4.0. Virtual prototype of hydraulic excavator was finished by use of ADAMS interface function and carried on a lot of kinematics and dynamics simulation analysis. Hydraulic cylinder circuit was derivated based on ADAMS/Hydraulics. Working principle of bucket arm hydraulic cylinder was analyzed. Mechanical and hydraulic simulation of bucket rod hydraulic cylinder was finished. Bucket rod hydraulic cylinder velocity was obtained. Simulation results show coupling simulations have certain theory value and practical significance. They can provide evidence for trial and optimization of physical prototype.

Abstract: In order to improve the efficiency and precision of steel ball grinding, analysis the main factors which influence them, and then introduce the method of improvement, bring in the conception of damping board system, thus obtain the new craft plan of ball grinding. At last, obtain the corresponding technological requirement and design mentality by modeling analysis, to provide basis for the further research later.

Abstract: Mold filling and solidification of molten steel for 750mm×450mm×300mm continuous casting mold of single SEN and double SEN are simulated by using CFD commercial code Flow-3d. The distributing diagrams of velocity field and temperature field and the location and shape diagrams of free-surface during mold filling process are obtained. Influences of single SEN model and double SEN model on velocity field and solidification are analyzed. It is found that double SEN model can lighten circumfluence intensity at the upper of mold, quicken solidification speed of steel liquid in the mold, which is favorable to improving the quality of billet and enhancing pull speed.

Abstract: Abstract. It explained that the quenching crack distribution characteristics and formation mechanism of the vehicle hub axles. Quenching crack of the vehicle hub axles was always the longitudinal crack and distributes in the inner wall .The crack was thin and long with the phenomena of crack cross and associated. The results of finite element simulation show that the internal stress value of the vehicle hub axles is up to 300Kgf / mm2 with the common action of the structure stress and heat stress, it is far more than 40MnBH steel tensile limit. This is the main reason of quenching crack. So for controlling quenching crack, it is need control raw materials, optimization of the quenching process and quenching medium replacement and so on.

Abstract: Whether blade profile of aircraft engine is reasonable depends on whether the surface pneumatic distribution given is satisfactory[1,2].In the experiments of optimization design,we discover that the design results are too dependent on surface velocity distribution with the following problems:The first is that the blade bend does not meet the requirements;The second is that blade thickness does not meet the requirements;The third is that the profiles of suction and pressure surfaces are not superposed very well at the leading and following edges with mouth open or cross;The fourth is that some situations of non-design behaviour are not taken into account. In this paper,these issues of blade bend optimization are discussed.

Abstract: Based on the ANSYS finite element calculation and analysis results to do the optimization design research of a large space transformer substation steel tower．To meet the constraints in steel tower frame under the minimum steel weight as the goal, the original web members of tower system structure would be optimized which was in different web members system as contrast．The optimization of the determined web members system met the design requirements and were more reasonable in economy．