Papers by Keyword: Plastic Forming

Abstract: Spinning is a type of plastic forming in which a tool such as a roller is pressed against a rotating plate or tube to gradually deform the shape and obtain a product with the same shape as the forming die. This processing method has the advantage that it can be processed seamlessly but has the drawback of causing internal defects due to deformation. In this study, the purpose is to obtain basic knowledge about the internal defect generation mechanism in spinning, and to perform cold and hot spinning with high diameter reduction under various conditions on Al-Mg-Si alloy tube. From the experimental results, it was confirmed that the inner defects increased as the diameter reduction ratio increased. It was considered that the main cause of the occurrence of inner defects was that, at a high diameter reduction ratio, the amount of processing was large, so that the increase of material flow led to increase of wall pressure.

Abstract: This paper describes a production process for experiment and finite element method (FEM) analysis of cold forming of SUS304 pipe. These large diameter pipes such as φ114.3 mm are used for a plant as a flow channel of gas and liquid. The connection of pipes are generally welded at the plant. However, the other connecting method are required from a viewpoint of making the plant environment worse by welding. Therefore, flaring process of large diameter pipes were proposed. This flaring process is one of a method of pipe flange forming. The formed pipes were connected used with loose flange. Flaring process was generally hot process, thus it has some problem such as becoming complex of forming machine and accuracy of dimension. In this study, cold flaring process of SUS304 pipe was proposed to satisfy these requisitions. Experiment and FEM analysis of cold flaring process were performed to clarify the optimum forming conditions for the flat length of connecting surface such as a diameter of punch, punch stroke and taper angle of dies. As a result, a gap between punch and die was needed to match the pipe wall thickness.

Abstract: A uni-axial compression test of solid wood containing a melamine formaldehyde resin and moisture at a heating condition was carried out to investigate fluidity of solid wood aiming at application of wood-flow-forming with an acceptable pressure level. Results show that there is a preferable moisture condition for initiation of flow phenomenon of the resin-treated wood. Since the decrease in the flow stress of wood generating pronounced size change in the drying process was distinguished, there might be a positive effect of the non-equilibrium state in moisture on the ease in generation of flow deformation.

Abstract: Silver alloys, due to its specific properties are widely used in different branches of industry, with approximately 95% of the world silver production is used in the photographic industry and for jeweller production. Moreover Poland is a significant producer of silver in the world, and takes the 6th place on the list of the world's silver producers with the KGHM Polish Copper Company production on the first place among global companies providing silver on the market, with an annual production at 1281 tones. Because of this impotent role of silver, this work presents microstructure and mechanical properties investigations results of the long aged Ag-Cu alloys used mainly for mint monetary production. The purpose of this work was to determine the microstructural changes after 32 and 40 year of natural ageing time, with appliance of transmission electron microscopy as well as light microscopy. A very important issue - one of the investigations directions is also the possibility of study of spinodal decomposition process, which occurred in this alloy. After the long-time ageing of the material, there are detected morphological different areas of the Ag-α and Cu-β phase. As an implication for appliance in real conditions - as coin metal, or in electronic and chemical industry branches, there is the possibility of application of long term ageing for mechanical properties improvement by natural ageing method. Some other investigations should be performed in the future, but the knowledge found in this research shows an interesting investigation direction, where a low cost but long term treatment operations can be applied.

Abstract: To investigate the effect of the additive agents such as polyethylene glycols (PEGs), melamine formaldehyde resin (MF-resin) and phenol formaldehyde resin (PF-resin) on the flow deformability of solid wood, free compression tests during heating were performed. Various molecular weights ranging from 200 to 20,000 for PEGs and almost similar molecular weight around 380 for MF-resin and PF-resin were applied. It was found from the compression tests that the yield stress indicating wood cell deformation resistance was drastically decreased with smaller molecular PEGs in wood, whereas the initiation of flow behavior, which is derived from detachment/slippage between cells, occurred at lower pressure with larger molecular PEGs. For generating the flow behaviors of solid wood, smaller molecular resin/substance was not always suitable. Thermosetting agents also act as a plasticizer during heating and especially the PF-resin showed better softening effect as well as a promoter of flow behavior than the MF-resin with almost similar molecular weight. This indicates that it is important for generating flow behavior to consider affinity/compatibility of resin to wood constituents. A maximum flow deformation ratio in the tangential direction of wood reached 180 % when using PEG 20,000 and MF-resin as an additive agent. It was also demonstrated that using PF-resin and MF-resin deep cup products shaped by a backward extrusion process had a better size stability against water, steam, and acetone.

Abstract: The thin metal plastic forming is an indispensable metal forming technology. Wrinkling is one of the common defects in plastic forming. If this kind of defects can be used properly, the formability of metal will be better. In this paper, the recent researches on the methods of identifying wrinkles, distinction of the useful wrinkles and harmful wrinkles, control and application of the wrinkles are summarized. The useful wrinkles are expected to improve the forming property.

Abstract: Stretch forming machine (SFM) is most effective plastic forming equipment for large-size, thin and flat-deformation parts, which can decrease the springback phenomenon in sheet metal forming. In order to enhance the performance of SFM, a flexible stretch forming machine (FSFM) was developed by the authors successfully, which is made up of jaw clamping mechanisms, stretching mechanisms, universal push-pull mechanisms, and a carriage. Our experimental results indicated that the rate of materials utilization and close-fitting dies can be increased to 80 %. In addition, FSFM can reduce the complex of control-system and decrease the expense of machine sharply. FSFM have been used for double-curved sheet metal manufacturing successfully, such as the cab of high-speed train. This work has a strong value in enhance the stretch forming technology for double-curved sheet metal parts.

Abstract: The paper presents effect of burnishing broaching process on the geometric structure of the steel tubes. Burnishing is a plastic surface treatment. Processing tools are hard and smooth surface. Burnishing elements of are ball, roll and disk. Burnishing be flat surfaces, and cylindrical shape. Burnished surfaces are cylindrical outer and inner. Because of the type of the force can be divided into static and dynamic burnishing. Due to the kinematics can be divided into sliding and roller burnishing. Occurrence of moving parts in direct contact with the material qualifies for the group process of burnishing rolling. The sliding burnishing design element property is part of the work surface burnished permanently attached to the handle. Burnishing is used as a finishing strengthens and smoothness, can be realized on the universal machine tools and machining centers, effectively replaces the machining operations such as grinding, reaming, honing and lapping.

Abstract: Plastic forming of metal material is a complex process. To predict and explore the forming law of these issues must be based on computer-based numerical methods. In this article, the shearing step of a textile knotted knife is studied. With the application of the DEFORM finite element analysis software, we make a dynamic numerical simulation of shear fracture on the tool sheet. After analyzing material’s stress and strain distribution in the plastic deformation zone and plastic flow vector in sheet deformation zone, the variable distribution curve of strain state can be obtained. And by comparing with the simulation experiment, acceptable product can be received. Through the numerical simulation, we can have an intuitive understanding of the plastic deformation process of this sheet, in the mean time; deeply understand the mechanism of plastic deformation. The numerical analysis method and the selection of the parametric have a significance of guiding and reference to the quality improvement of knotted knife products.

Abstract: The magnesium alloys, that have high specific strength, are often applied to the industrial products. However, the magnesium alloys exhibit low ductility at the room temperature on account of its hexagonal close-packed structure. It is difficult to give large deformation to the magnesium alloys at room temperature. Therefore, the plastic forming of a magnesium alloy sheet needs the process at warm temperature. In the present work, the procedure of thermal-mechanical coupled analyses are employed. The numerical simulations of warm deep drawings have been performed in order to evaluate the dependence of the temperature on the plastic forming of a magnesium alloy AZ31 sheet. The mechanical properties of the magnesium alloy AZ31 shall be described as the functions depending on temperature. The shapes of punches and die holes are rectangle whose aspect ratios are 1.5 or 2.0. The corners of punches and dies are heated locally at 473K. The influence of local heating on the formability have been investigated. The relation between the blank size and the formability has been also estimated. As the results of numerical simulations, it was shown that the formability of deep drawing was improved by local heating to the punch and the die. When the blanks of various sizes were tried, the distributions of the plastic strain rate around the die corner were changed. Therefore, the deviation of the plastic flow and the temperature distribution arose in a sheet. Consequently, it is necessary to optimize the blank sizes according to the shape of die holes in addition to the forming temperature.