Advanced Materials Research Vols. 291-294

Abstract: The feasibility of using modern computers in manufacturing has evolved an era in the development of several new sheet metal forming process. The concept of profile forming technique has been investigated for production of sheet metal components. Profile forming is a very promising technology to manufacture sheet metal producs by CNC controlled movement with simple forming tool. Profile forming was developed as a flexible, alternative manufacturing method to effectively prototype stampings and produce in small lots. Cylindrical Cup is formed on Aluminium sheet of grade Al 3003 (O) without using punch and die. Formability of material, maximum wall angle, Surface roughness, thinning of sheet and Microstructural characteristics of Aluminium sheet are studied.

Abstract: Since conical parts have wide applications in the industry and forming these parts is one of the most complex and difficult fields in sheet metal forming processes, the study on different methods in forming these parts can be useful. Hydroforming and conventional multistage deep drawing are two deep drawing processes which have been used to form conical parts. Hydroforming deep drawing is one of the special deep drawing processes which have been introduced in order to overcome some inherent problems in the conventional deep drawing with rigid tools. In the present work, an experimental program has been carried out to compare the drawing load variation and maximum drawing load in forming pure copper conical-cylindrical cups with the thickness of 2.5 mm by hydroforming and conventional multistage deep drawing processes. The results of the study demonstrate that drawing load variation is more uniform in the forming of conical parts by hydroforming deep drawing process. The maximum drawing load for drawing copper blank occurs at a higher amount in hydroforming process.

Abstract: By the apparatus of differential scanning calorimetry (DSC), scanning electron microcopy (SEM) and wide angle X-ray diffraction (WAXD), The effect of vibration on the microstructure and mechanical properties of high-density polyethylene (HDPE) sheets, obtained through vibration plasticating extruder in low temperature, were measured and analysed. The result show that the tensile strength was much improved under the reciprocating axial vibration in low temperature. The phenomenon indicate that the vibration extrudate in low temperature has higher crystallinity, perfect crystallite, and strong inter-spherulite ties, which account for enhancement of the mechanical properties of sheets, compared to conventional static extrusion.

Abstract: The microstructures and mechanical properties of Mg9AlZnGdY alloy after T6 heat treatment in lost foam casting (LFC) are compared with that of AZ91D magnesium alloy. The results show that the microstructures of Mg9AlZnGdY alloy after T6 heat treatment consist of the α-Mg solid solution, β-Mg₁₇Al₁₂ precipitation phase, a small amount of rod Al₂Y and block Al₂Gd phases, which are distributed over grain boundaries of the α-Mg phase. The thermal stability of Al₂Y and Al₂Gd phases offers the pinning effect on the grain boundary under high temperature, and therefore, the grain boundary sliding is eliminated and the high-temperature strength is increased. After the T6 heat treatment, the tensile strength of Mg9AlZnGdY alloy was 235MPa at room temperature, and 156MPa at 200°C. Compared with that of AZ91D alloy, the tensile strength was increased by 19.3% and 38.1% respectively.

Abstract: By using finite element method, the causes of forming defects such as shortage of material and punching recess thickened during drill pipe joints forging were studied and some solutions were put forward. According to the numerical simulation results, one forming defect named shortage of material caused by the metal irregular flow at the bottom of necking die, which can be resolved by reducing the die forming-angle and increasing the width of the punch. On the condition with D₀/d₀≤2.6 (D0 refers to outer diameter, d₀ refers to inner diameter), necking process can be completed with one-step backward extrusion. The thicker punching recess is formed by the accumulated metal which was scraped by the punch during necking extrusion. This kind of defect can not be eliminated, but can be minimized by improving friction conditions.

Abstract: Co-continuous polymer blend has attracted broad interest in many technique fields due to its unique ability to be transferred into porous material with interconnected micro-channels. And combined with some surface patterning, it can provide material of hierarchical porous structure. A key challenge in the fabrication of material of desired morphology is the ability to control the interface movement. Here, we incorporate the thermo-geometrically controlled annealing and hot embossing to fabricate hierarchical microporous structures with well defined morphology and topography. Various novel structures demanded for many emerging applications can be created by judiciously using this newly developed technique.

Abstract: Due to the recent development both in the numerical simulation technology and computer technology, the role of numerical simulation in sheet forming industry has been continuously increasing in recent years. This paper describes the application of numerical simulation technology in the forming process of a complex box-type part with Dynaform and gives a fairly accurate forecast of defects that may appear in the forming process. Prediction of the effect of design parameters such as blank holding force and drawbeads on forming quality is investigated. The study indicates that blank holding force and drawbead directly affect the metal flow and formability of stamping. Then, by adjusting blank holding force and setting appropriate drawbeads, an optimized stamping process plan is obtained and is validated in experiments. Finally the phenomenon and displacement of distortion springback are predicted in the springback simulation, which is useful to further improve the quality of this kind of part.

Abstract: Understanding the mechanism of the forming of the welded pipe may help the engineer to design the shape of forming rollers and forming technology. It is hard to study the forming process of the welded pipe by both the method of experiment and numerical modeling because of too much nonlinear factors included in the forming process such as elastic-plastic large deformation and non linear contact. Although many research works have been conducted in this field by the method of experiment or numerical modeling, but few of the works deal with the whole forming process of the welded pipe. The main difficulties in the numerical modeling are of huge computational labor time, witch has been over the ability of the hardware and software of the computer. The whole process of roll forming of welded pipe has been simulated by nonlinear finite element method with ANSYS and LS-DYNA solver, the distribution of both stresses and strains have been got successfully. Mapping meshes and the rigid models for rollers have been used in the analysis in order to decrease the number of the elements. Numerical results and parameter study have shown that the forming rollers of both the level and vertical are the key factors to the forming process. It is believe that the method used in the paper can also be used to study the forming process of both cage roll forming and flexible forming.

Abstract: Packaging material of electronic goods requires higher strength, higher reliability, and lower expansion coefficient .What’s more, forming process is important. The Fe-Ni-Co alloy has a low expansion coefficient and good structure stability, so it is often used for packaging materials for the semiconductor industry. The shape of electronic packaging parts is so complex that the traditional manufacturing processes are difficult to form and it costs more, which greatly limits the application of Fe-Ni-Co alloy in complex electronic packaging parts. Metal (ceramic) powder injection molding (MIM / CIM) is a new near net shape technology. In this paper, we analyze the structures and characteristics of Gehause which is an electronic packaging box that has been successfully used in the MIM process to produce it. In this process, we adopted a new material of Fe-Ni-Co alloy, a specia binder and SPC (Statistical Process Control) technology which control parameters of injection molding and weight of parts. After sintering, the mechanical properties and precision of finished products meet all demands. Therefore, MIM technology can greatly improve the production efficiency, save materials and reduce production costs in producing Gehause.

Abstract: Tube hydroforming with radial crushing (THFRC) process is particularly applicable to the tube which is difficult to shape due to lack of axial feeding. In this paper, the formability of the circular tube expanded into a triangle cross-section under the simple loading paths is explored by using the numerical simulation. The effect of the forming mode and the loading paths on bulged profile, wall-thickness distribution and the potential fracture location of the bulged tube are analyzed. The results showed that constraint conditions at tube ends have small influence on the bulged profile and wall-thickness distribution. Moreover, the larger the peak value of the internal pressure is, the better material filling ability and higher accurate the tube bulged profile are. Furthermore, the higher forming accuracy, the better material filling ability and wall-thickness distribution are gained in THFRC than those in free hydro-bulging (FHB) process, and they can be obtained under constant than linear pressure loading paths. Finally, the potential fracture location of the bulged tube in THFRC process is quite different from that in FHB process.