Advanced Materials Research Vols. 538-541

Abstract: Tube hydroforming with radial crushing (THFRC) process is one of tube hydroforming methods that is suitable for overlong structure parts forming process avoiding wrinkling and bursting failure. In this paper, the Forming Margin Diagram (FMD) for THFRC process was presented to optimize loading paths. Initially, parameters of Finite Element (FE) simulation in this study were represented, which contained FE model and linear loading paths. Afterwards, boundaries of the FMD were delimited based on real working status. Moreover, curves of corner radius, bursting failure and thickness uniform rate were determined by FE simulation results to establish the FMD, and the curves and zones on the FMD were analyzed simultaneously. Furthermore, features of contour lines were discussed, and the usage of the FMD was introduced.

Abstract: Superplastic forming in Al6063/SiCp composites having a wide range of applications in aerospace and automobile industries due to the high strength and wear resistance[7]. High percentage of elongation was obtained only at high temperatures. At high temperatures liquid phase will form in the grain boundaries. Due to the liquid phase, grain boundary sliding was easy to get the Newtonian viscous flow[1]. In composites high ductility was obtained only the temperature more than 560°C. The maximum dome height of 19 mm was obtained at 580°C. Temperature is more than 600°C the material was failed, fracture was occurred.

Abstract: In this study, the parameters (i.e., contact stress at the die-sheet interface and the punch velocity) were measured by the installation of film stress sensors in the fine-blanking die. A regression model was established to investigate the degree of importance of the parameters and their interaction on reducing the crack ratio of fine-blanked surface. Analysis of variance (ANOVA) was then performed to check the adequacy of the regression model. The optimal results of the regression model agreed well with the experimental result. The regression analysis indicated that the contact stress have a major influence, followed by the interaction and the punch velocity. The importance of the interaction means that the ability of contact stress in crack ratio reduction depends on the level of punch velocity. The result could be useful to facilitate an improvement in the quality of the fine-blanked parts by the optimization parameters.

Abstract: Pressurization control system plays an important role in the process control at the stages of riser-tube filling, mold-filling, pressure-increasing and pressure maintaining in counter-gravity casting. Casting quality is affected by the precision of pressurization control system to a great extent. Input and output scaling factors of conventional fuzzy controller are static, which is hard to ensure a suitable state for various counter-gravity casting equipments. A new fuzzy controller with self-tuning scaling factors has been developed in our laboratory, which will be described in this paper. Input and output scaling factors of fuzzy controller are tuned by different error ranges. When the differential pressure error is large, output scaling factor is increased to speed up dynamic response. At the same time, input scaling factors are also increased in order to reduce steady state error. Compared to fuzzy controller and conventional PID controller, fuzzy-PID controller with self-tuning scaling factors has more steady-state precision and excellent robustness. Experimental results show that at riser-tube filling stage and mold-filling stage the gas flow is stable, and the tracking property of pressurization control system is very satisfactory.

Abstract: In this thesis, CAE software is used to carry out the injection molding analysis of mobile phone battery cover and simulate the filling and cooling process so as to determine the formability of plastic parts and product quality. In the process of product design, it can also predict possible defects so as to optimize mold structure, save production costs, and improve quality and efficiency of cell phone battery cover design.

Abstract: For the steel castings which is thin wall, uniform thickness, complex structure, and no special mechanical properties, it is feasible that the foundry technology was designed according to the last solidifying feeding mechanism. Adopting this process for the thin wall steel castings, the pouring temperature must be controlled and the gating system be designed rationally. Using self-feeding shrinkage in solidification, and the casting was poured and congealing at the same time. The shrinkage of finally congealing part was fed by small riser or gating system (no riser). Using this foundry technology, the casting process yield and surface quality of casting may be improved, the production cost is reduced, and the requirements of mechanical properties can be met.

Abstract: Effect of vanadium and nitrogen concentration in V-N steel and cooling rate after deformation on grain refinement has studied in this paper. The results show that with the increase of vanadium and nitrogen concentration, ferrite grain size is smaller compared with carbon steel; with the increase of cooling rate after deformation, ferrite grain size is finer and pearlite content of microstructure significantly is reduced too. Compared with the Nb-bearing steel, as long as selecting reasonable the process parameters and adding the appropriate vanadium, nitrogen to the steel, V-N steel can also get a good strength and toughness, and the cost is lower than Nb-bearing steel. This method of producing the steel with good Strength and toughness is very suitable to China who possesses the abundant vanadium resource, but is lack of niobium.

Abstract: The article focuses on the discussion of size relationship of melt viscosity of ultra-thin wall injection molding, revising the viscosity model of traditional stimulant Cross-WLF. It takes the theory of Uhland wall-slip, trying to analyze the influence which the wall-slip of the molding makes on injection molding. It also points out the limitation of constant heat transfer coefficient in the molding. The change rules of the heat transfer coefficient is among the study. Using the method of numerical simulation and experience, the article verifies the consistency of experience result and the change of the factors, such as using ultra-thin viscosity model, wall-slip and the change of heat transfer coefficient while doing the simulation.

Abstract: Squeeze casting(liquid forging), a process technology that combines casting- forging and near net-shape high-quality engineering components，is always subjected high attention of the industrial circle. The squeeze casting technology which refers to improve the products properties and expand the applicable range of the squeeze casting is developing fast. With the Flourishing development of car industry and the constant renewal of National Defense Equipment, it raises a new requirement for squeeze casting industry. This paper discusses the process technology and casting machine of domestic and overseas.

Abstract: It has conducted a study on the cost calculation of spray component mould manufacturing process. In general, it is the present state that calculating machining time and cost for a unit process in mould manufacturing process depends on past experiences. In other words, it does not go beyond the level of computing and management by estimation based on the data conducted in the past. Accordingly, in the development of mould and new products tried for the first time, the cost calculation is not reasonable and thus a lot of time is needed. That is to say, not being able to actively and reasonably respond to the needs of the market that are changing every moment, the loss of management and money due to losing opportunities is frequently taking place. In this context, It have developed and applied a system that can reasonably calculate the cost by taking account of machining time calculation theory, machine, tool, material and working environment. As a result, calculating the time needed for a unit process in mould manufacturing process is possible, and it is possible to classify major processes and suggest alternatives in management. The system developed in this study used Visual Basic Language and SQL Database under Windows environment.