Advanced Materials Research Vols. 602-604

Abstract: To explore application of step gating system in LFC, filling process of two types of step gating system was simulated, their filling patterns were found, and several engineering examples were analyzed basing on these patterns. It was found the metal start filling through all ingates almost simultaneously if the gating system is open, otherwise the sequence of the ingate filling follow increasing sequence of streamline length from the inlet. It was also found the metal volume through each ingate increased gradually bottom-top when the common step gating system is filled by EPS, but when the common step gating system is open or step gating system have an auxiliary sprue, the metal volume decreases gradually. Analysis on several engineering examples shows the simulation confluence of two liquid metal fronts is basically in accordance with the casting defect locations.

Abstract: The die-casting die of end cover of one diesel engine was designed. A double-stage linkage hydraulic core-pulling mechanism was designed and used in the die-casting die according to the complex structural features of the end cover casting. This double-stage linkage hydraulic core-pulling mechanism could achieve secondary core-pulling and decompose the packaging force. The disadvantages of deformation, crack, abruption in orifice or thin-walled parts of the casting could be overcome. The practice shows that the structure of die-casting die of end cover of diesel engine is reasonable, reliable, and applicable.

Abstract: As the important bearing structure of aircraft high pressure systems, the properties of air ducts are directly related to the flight safety. In order to improve air ducts formation quality and reduce the forming processing cost, improving the tube bulging processes is needed. The key technology of bulging processes is one of the choices of dielectric bulging, through to the liquid medium, plastic medium, the elastic medium, viscous medium and solid medium forming technology characteristic analysis, this study describes the advantages and disadvantages of various media.

Abstract: The quality of the plastic part depends on the material characteristics, the mold design, and the process parameters, one of which is more important. It involves many sub-design tasks that determine the cost and performance in the early conceptual mold layout design phase. Base-Cover was injection molded with acrylonitrile–butadiene–styrene (ABS)/polycarbonate (PC) [ABS/PC] alloy resin and its process parameters was analyzed by commercial Moldflow software. The optimum gate location and melt filling time were determined, and the optimum injection temperature was obtained by analyzing the shrinkage of the product after molding. An effective regression model was developed to determine the mathematical relationship between the process parameters (mold temperature, melt temperature, injection pressure, injection time, and cooling time) and the volumetric shrinkage by utilizing the analysis data.

Abstract: Forming severity is one of the significant indexes to assess formability of tube hydroforming. The state of strain can be accurately reflected when tube reaches forming limit, mechanical rules during forming processes can be revealed as well by using the forming limit diagram (FLD). By contrast with FLD of sheet metal, the FLD of tube hydroforming is seen as different. In this paper, the importance of FLD of tube hydroforming was discussed briefly; typical methods established to FLD of tube hydroforming were listed and classified; characteristics and insufficiencies of those methods were pointed out; advantages of forming limit stress diagram (FLSD) were introduced simply. Furthermore, the main problem and the trend of development in FLD of tube hydro-forming were summarized.

Abstract: How to build a stable pipe roller design algorithm system has become the difficulty of modern steel pipe roller design. Although the theory researching cold bending forming is more now, but the theory used to guide pass design is less. This paper studied and established the new rolling process model based on spline finite strip theory. It’s good to Shape the way time and build the chain storeing deformation way Agent structure in transition region. It helped to realize intelligent single channel cold bending forming a stress and strain description. And it is usefull to establish forming theory and the parameters contact of the pass design. In a word, it provided the theory basis for the precise pass design.

Abstract: ABAQUS software is used to simulate the stamping process of the Y-shaped tube to study the feasibility of stamping forming. The simulation results are analyzed to study how fabrication holes affect the ability of sheet metal forming. The results show that it is possible to form the Y-shaped tube by stamping; fabrication holes with reasonable size and location can improve the distribution of stress and strain, and enhance the limit deformation ability of the sheet.

Abstract: From PTFE baseband prepared by three-dimensional drawing, after the processing of different temperature and time. And then by twisting, hot drawing and heat setting, the PTFE filament was prepared in appropriate tension conditions. The surface morphology of the resulting filaments was observed by SEM, the result shows that the uniformity of the PTFE membrane has been improved by using three-dimensional drawing process, hot drawing processes had a great effect upon the breaking strength and elongation at break of PTFE fibers. In order to keep ensure reasonable mechanical properties, the draw ratio in the range of 20 to 50 times to adjust the temperature controlled at 150°C to 300 °C.

Abstract: The concept of discrete die bending of rectangular tube is proposed, and the FE model is set up. The phenomenon of section distortion of rectangular tube generated by discrete die bending is analyzed. The feasibility of discrete die used for bending of rectangular tube is proved by comparing the section distorted rate generated by both discrete die and integral die. A lots of numerical simulation of the influence factors of section distortion are analyzed, the results show that larger the bending radius is or the thicker the rectangular tube is or the larger the yield strength of rectangular tube is, the smaller the section distorted rate will be. Then the dimple generated by discrete die is described, and the influence factors are studied, the results shows that the smaller the bending radius is or the thinner the rectangular tube is or the smaller the yield strength of rectangular tube is, the stronger the dimples on the rectangular tube will be.

Abstract: To improve the production quality of mini-car spoke components, the forming process of mini-car spoke components is numerically simulated by DYNAFORM, and the geometry models of punch, die, blank holder and sheet metal are established, the effect of round-hole flange coefficient, material parameters and forming craft on flanging forming is evaluated by simulation computation method, and the suggestions for improvement are discussed. The results indicates that the increase in material yield strength has a great influence on flanging cracking; and through improving flanging process, the cracking defects of round-hole flanging in the spoke components can be controlled, the cracking rate reduces to 0.1 ‰, and the better product quality can be obtained.