Papers by Keyword: Forming

Abstract: Deep drawing process is one of the important processes in sheet metal forming. One of the challenge that faces the deep drawing process is selecting the optimal values of process parameters for the deep drawing process. In order to find the optimum values of these parameters, it is necessary to study their influence on the deformation behaviour of the sheet metal. This paper develops a simulation model for deep drawing process based on Simufact sheet metal forming module to study the effect process parameters on the deep-drawing characteristics. The study also obtained the distribution of strain on the drawn product. Three process parameters are considered in this study namely, punch radius, die radius and clearance, the effect of these process parameter on the required force as well as on the quality of the product are investigated.

Abstract: The wet compression molding (WCM) process enables short cycle times for production of fiber-reinforced plastics due to simultaneous infiltration, viscous draping and consolidation in one process step. This requires a comprehensive knowledge of occurring mutual dependencies in particular for the development of process simulation methods and for process optimization. In this context, it is necessary to develop suitable test benches to enable an evaluation of the outlined viscous draping behavior. In order to evaluate and suitably design the draping process, grippers are mounted on a surrounding frame, which enables targeted restraining of the local material draw-in during forming. In supporting the development of the new test bench, first experimental and simulation results are compared, which thereby enables a first validation of the simulation approaches. Results show a good agreement between experimental and numerical results in terms of shear deformation and final gripper displacement under dry and viscous conditions. Results recommend that future development for investigations of viscous draping effects should focus an enabling measurement of gripper displacement during the forming process. Beyond that, the modular test bench design enables experimental and virtual draping optimization and deduction of blank holder concepts for WCM tools.

Abstract: One of the biggest environmental challenges of Vietnam is plastic wastes without recycling such as bottle, cans, plastic bag. The Vietnamese government have recognized these problems and called the reforming campaign to develop the sustainable technology to re-producing the wasted plastic. Thus, this research aims to contribute to deal with the issue by designing a plastic recycling machine. To satisfy domestic market of over 120 units at the first time, this research attempted to make a small machine at a low cost, but its throughput still reaches about 8kg plastic/hour and it can run within 16 consecutive hours a day. Hence, most of components is expected to be supplied by local vendors. As the result, the product price as well as maintenance cost is anticipated to be reduced. With the aim to produce the automated machine can incorporate continuous raw materials flow and at the same time move melted plastic in screw conveyor as defined by the regulation of the Programmable Logic Controllers (PLC) with timer to detect a velocity of melted plastic which come out from a nozzle of the screw conveyor and go to a mold. The hydraulic pressure, then, applies force to compressing and forming products. There are potential risks that can happen in fact, to deal with them. That is a reason Computer aid engineering and Finite element method modeling were conducted to make sure the force pressed in mold sufficiently and controlled the thickness of production as customer requirements.

Abstract: The tailoring of mechanical and technological properties of the initial material in sheet metal forming has been widely investigated and successfully applied. The benefits of such an approach can be found in the improvement of both the post-forming performances of the manufactured component and the forming process capabilities. Different strategies can be found and most of them involve a microstructural alteration by a selective heat source (e.g. laser, induction, UV light). The use of aluminium alloys combined with these strategies has been extensively investigated, while magnesium alloys are almost not yet considered from this viewpoint. In this work, we investigated the effect of a selective laser heat treatment on an AZ31 magnesium alloy sheet. After laser heat treating a single track in the centre of a blank with different heat input values, bulge tests at elevated temperatures were conducted. The dome height evolution was continuously acquired during the tests and differences between the untreated specimen and the laser treated ones have been characterized. The effect of the laser treatment was evaluated also in terms of thickness distribution of the formed specimens. A thickness discontinuity was found along the treated specimens in the transition zone between the treated and the untreated material. Results highlighted that an effective change in the forming behaviour can be induced in the treated zone depending on the laser heat input. It has thus been shown that this approach can be employed for tailoring the magnesium alloy blank properties prior to the gas forming at elevated temperatures.

Abstract: The stiffness of metal formed products strongly affects the dynamic behavior of structures in which they are integrated. Forming processes underlie short and long-term variations which cause the stiffness to be uncertain.In the application of resonant shunted piezoelectric transducers for vibration attenuation, uncertain stiffness may cause significant reduction in the vibration attenuation performance due to imprecise tuning. In the past, large efforts were made to control one or more geometrical feature of products while weightier features that cause uncertainty have not been addressed.In this paper, a single point incremental forming process of a membrane-like spring element on a servo press with a 3 degrees of freedom drive system is investigated. This spring element is used in a beam support for lateral vibration attenuation with resonant shunted transducers as well as axial buckling stabilization.To reduce uncertainty caused by process variations, an offline closed-loop control of product stiffness is presented. Different product and forming criteria are integrated into a control approach based on an optimization routine. By making use of a model-based prediction of the product properties, the approach shows how to realize a multi-objective control.

Abstract: Joining by forming is an attractive assembly method for mass produced parts due to easiness in execution, no heat effect, various material combinations etc. and industrial applications have been increased in electric and automotive industries. In this paper, a disc plate and stepped shaft is assembled by forming. Assembling is achieved by indenting the disc with a stepped and grooved shaft up to a certain depth. Through the experiments using an aluminum disc and a steel shaft, the influence of the overlap length and penetrating depth of the stepped section on joining force, axial strength and dimensional change of the disc plate are investigated. Disassembling tests revealed that the joint by the proposed method had sufficient axial strength if the groove of the shaft was completely filled.

Abstract: Inner vessel in reactor assembly of sodium cooled fast reactor separates hot and cold pool sodium. The shape of inner vessel is optimized with reduced upper & lower shell diameters and toroidal redan for future Fast Breeder Reactor (FBR). This results in higher buckling strength and reduced thickness and hence reduced weight. To achieve the intricate toroidal shape with specified dimensional tolerances, a comprehensive technology development exercise was carried out successfully for the manufacture of inner vessel 30° sector. The achieved profile of the redan meets the specified dimensions and other design requirements. Spring-back observed in the sector was small. To verify the developmental exercise results, a finite element analysis (FEA) of forming of inner vessel sector was performed on finite element software ABAQUS. In this paper, FEA results and spring back are discussed. Spring back assessed is maximum at the center and relatively lower towards the edges for the redan with the chosen radius of 5980 mm.

Abstract: For a deeper understanding of the forming behaviour of perforated aluminium sheets (Al99.5) in micro deep drawing processes, tensile and stretch forming tests are performed at forming speeds of 0.1 mm/s and 0.25 mm/s. The sheets have thicknesses of 100 µm and 200 µm, a perforated rectangular hole geometry of 300 µm x 300 µm and a bar width of 40 µm. During stretch-forming tests the flow characteristics and failure mechanisms within the mesh structure are determined. An isotropic forming behaviour with low ductility is observed. The maximum stretch-forming depth is increased at increasing perforated area. The mesh structure failure is peripherally obtained due to notch effects, friction and micro related size effects within the mesh structure. Moreover, the results show that cracks and necking within the mesh structure occur only tangentially to the punch movement due to high uniaxial stresses caused by the forming process.

Abstract: Applying bulk forming processes on sheet metals enables the manufacturing of functional components with local wall thickness distributions. Using tailored blanks improves the forming of the functional components and increases the material efficiency. One process for manufacturing tailored blanks with defined sheet thickness distributions is a flexible rolling process. However, this process requires a complex process strategy. Additionally, tailored blanks out of high-strength steels from this process have failed in subsequent forming. Thus, a new rolling concept with a defined shaping of the material into a die cavity has been developed. This new concept requires the development of a new process strategy. In this paper, the general qualification and first results of the new concept are presented.

Abstract: The aluminium alloy AW-6016-T4 sheet is the most widely used alloy for simple-shapeouter body parts for passenger vehicles at room temperature. However, for complex parts, such asthe B-pillar, the room temperature formability of AW-6016-T4 sheet is not sufficient. Simultaneoushot stamping and quenching is a viable alternative, but there is still limited information about theinfluence of process parameters on both the formability during the process and the part strength atthe end of the process. A combination of thermo-kinetic simulation and experiments were used toinvestigate the influence of process parameters in the simultaneous hot stamping and quenchingprocess.Increasing the heating rate from 1 to 100 K s-1 during heating to the solution heat treatment (SHT)temperature was found to have no significant influence on the UTS. However, a SHT time of 4 minis required to achieve highest strength by the end of the process chain. Increasing the amount ofdeformation and cooling rate after SHT have a positive influence on the finished part. PredictedDSC curves and Yield strength values from MatCalc were in good agreement with the experimentalresults.