Papers by Keyword: Material Flow

Abstract: Conventional friction stir welding of aluminium to copper often results in the formation of deleterious intermetallic compounds. In order to overcome this concern, an innovative procedure consisting of using an aluminium run-on plate is presented. Long continuous aluminium-copper welds, without any defect, were obtained by this procedure. The run-on plate inhibits the formation of intermetallic compounds around the pin by allowing the use of high tool offset, without the formation of discontinuities at the interface. The generation of an aluminium volume around the tool, which detaches very small copper particles from the copper plate, gives rise to stir zones composed of a uniform distribution of copper particles in an aluminium matrix and with a minimal formation of intermetallic compounds. Comparing to the conventional welds, a significant improvement in the mechanical strength was achieved by welding with this non-conventional procedure.

Abstract: New groove pass series for long products must be developed by backward engineering starting with the necessary mechanical properties and geometry of the final shape, with a highly iterative manual effort and with numerous manual decisions. Usually, established groove sequences are adopted in this process without consideration of material requirements of the rolled materials and work roll limitations, while other groove shapes may provide better final results. In order to achieve precision in the material flow, time-consuming FE-Methods are already being used in the reverse engineering. The aim of the presented fast approach is to obtain an optimal roll contour for simple irregular groove sequences using generalized, roll-technical justified and experimentally evaluated design criteria coupled with a fast 3D approach for stress state, material flow and fast approaches for the assessment of the elastic stress state resp. work safety of the rolls. By direct coupling the material flow calculation e.g. with fast microstructure models the microstructure development and the required end properties are integrated into the optimization process. Parts of the calculation code discussed are available via the open source project PyRolL which is continuously updated by the Center of Groove Pass Design of TU Bergakademie Freiberg and free available within the terms of the BSD-3-Clause License [1]. The Python-based framework allows maximum adaptability to own needs via a flexible plugin system for inclusion of own models and routines.

Abstract: Friction Stir Process (FSP) is considered one of the most convenient, effective, and environmental friendly manufacturing processes. In these processes, a tool involves a pin that blends the material around it and a shoulder that creates frictional heat. On the other hand, the pin mixes the soft material to refine the grain structure. This paper aims to investigate a thermal model using Altair to numerically simulate the temperature distribution profiles of 7075 Aluminum Alloy material using FSP. Using a novel technique called Smoothed-Particle Hydrodynamics (SPH), we extracted the temperature distribution in the Stir Zone (SZ) for 900 RPM, 1200 RPM, and 1500 RPM Tool Rotational Speed (TRS) with constant Tool Traverse Speed (TTS). The temperature results obtained are incremental with increasing TRS. As a result, the temperature achieved from 900 RPM to 1500 RPM has increased by 21.20%. In addition, the obtained temperature is almost 50% of the melting point. The material flow on both Advancing Side (AS) and Retreating Side (RS) shows the thorough material mixing. The SPH technique helps to investigate the proper material flow modeling by dividing the AS and RS nodes and it was observed that they have thoroughly been mixed near the FSP tool pin.

Abstract: Friction stir diffusion bonding (FSDB) has been applied to lap dissimilar foils joints of aluminum alloy on top of commercial purity (CP) titanium. FSDB of the foils was successfully performed through stirring only the upper aluminum foil by the air spindle with an extremely-high rotation speed of 105,000 rpm. By using smooth surface of the tool tip, FSDB with micro indentation less than or equal 10μm could be carried out to improve the surface condition of the joint and the indentation depth required for joining was reduced. The material flow of the upper aluminum alloy foil in the FSDB was investigated by deposited platinum-palladium as the tracer material on the surface of the lower titanium foil. Then it was confirmed that the vestiges of vigorous stirring appeared in the region given at a distance from tool center while little vestiges was found in the other region. These regions seemed to be bounded by a radius of about 0.6 mm from the tool center. Moreover, the bonding strength distribution as a function of the distance from the tool center was likely correspondent to the stirring state.

Abstract: This paper describes the necessary measures to create an adaptable material flow and energy simulation for melting and die-casting plants. Based on two reference plants, the structural and intralogistical differences are emphasized and examined. These differences specify the necessary extensions to a previously created simulation environment in order to be able to analyze variable plant configurations. Special emphasis is put on the creation of a simplified energy model that allows the modeling of melting furnaces based on rudimentary datasets. Using the adaptable material flow and energy simulation two measures and their effects on the in-plant energy efficiency as well as productivity are analyzed. The simulation results suggest energy savings potentials for both plants and measures to increase productivity for one of the analyzed plants.

Abstract: The paper presents the results of a mathematical model of the material flow during Friction Stir Welding (FSW) of aluminium alloys using a Finite Element Analysis. The authors presented their work on a two-dimensional visco-plastic model, using User Define Functions (UDF) in a commercial CFD code (FLUENT). The model developed was validated by microstructural investigations on experimental FSW joints and by a comparative analysis of temperature distribution field of the experimental FSW joint and numerical simulated model. The results confirmed that the mathematical model describes with a good precision the material flow and temperature field during FSW process.

Abstract: The study focuses on the examination and development of simulation based measures to increase the energy efficiency and productivity in the non-ferrous melting and die-casting industries. The high energy consumption of gas-fueled melting furnaces is caused by production fluctuations in the foundry. Currently the control of the operating processes is decentralized and based on empirical process experience and inaccurate information of the operating state. The acquisition of the plant wide supply situation of the die casting machines with liquid aluminum is an essential condition for solving the problem of inefficient working melting furnaces. Their representation is grounded on specially defined key figures.In a first step the filling levels of the different liquid aluminum sources (melting furnaces) are considered as one unit as well as the filling levels of the different liquid aluminum sinks (die-casting machines). This assumption leads to the so called storage distribution key figure which describes the current supply situation of the die casting plants with liquid aluminum. This single key figure is able to assess the complex plant wide supply state. This key figure allows the real time evaluation of the operating state (production safety). Another important key figure is the residual running time of the die casting machines. Both key figures can be used for controlling the operating processes, too. A simulation is needed in order to analyze these operating processes because otherwise it would interfere with the real production process. The simulation of the complete material flow of the aluminum starts with its delivery in solid and liquid form, continues with the melting in furnaces and leads to the production process in the die casting machines. Energetic key figures such as the gas consumption and the specific melting rate of the melting operation can be determined by bidirectional coupling with a physically based energy model of the melting furnaces. The simulation model was validated by measured data obtained in an industrial plant.The storage distribution key figure and the residual running time key figure can be used in order to provide Smart Services to increase energy efficiency and productivity in specific operating states. Adjusting the cleaning times of the melting furnaces or controlling the fork lift trucks are potential examples. The results of initial simulations show the effects of different control measures based on these key figures. Smart Services in real operation can be implemented as an assistance system but for the implementation in real operation a central data processing is indispensable prerequisite.

Abstract: This work deals with the effect of volume percentage of nanoreinforcement to fabricate nanosurface composite by Friction Stir Processing (FSP) and also studied the role of tool rotational speed and traverse speed to get the defect free condition to fabricate successful surface composite. The material flow pattern, dispersion of the reinforcement particles in the stir zone was examined. From the phase/volume fraction analysis, it was observed that the nanoAl₂O₃ particles were well dispersed in the stir zone. The results indicate that the better microstructural, mechanical properties were obtained at 1150rpm /15mm/min condition. A significant improvement in microhardness was exhibited by surface nanocomposite as compared to the as - received aluminum.

Abstract: In multiple stages forging, an appropriate pre-form has reduced production cost, loss of material, and forging load, and it has also improved die life. However, it is difficult for beginner to make the process design of the pre-form because they have poor technical information. For example, experts have experimental knowledge how to form an oval cylinder by upsetting of a right cylinder with a mild-wedged die. This oval upsetting needs no container with oval hole. This paper investigates the oval upsetting with the relationship between the nose angle of the mild-wedged die and the shape of the product for assistance of the process design in forging. As the results, when the mild-wedged die having an appropriate angle and nose radius was applied to the upsetting, the oval cross-sectional ratio of the major axis to the minor axis achieved 1.45.

Abstract: Shearing is the cutting of a sheet material with a punch and a die. The cut surface obtained by shearing is composed of rollover, a sheared surface, a fracture surface and burr. It has been reported that rollover is formed by the insufficiency of material and material flow in the lateral direction. However, the rollover in the sheet material on the die and that in the sheet material under the punch have not been evaluated individually in previous studies. In this report, the relationship between the material flow and the formation of rollover in the sheet material on the die is discussed on the basis of experimental results obtained by image processing. The relationship between the material flow and the formation of rollover in the sheet material under the punch also is discussed. Double-sided shearing with a counter punch was carried out. The deformation of the sheet material was observed through reinforced glass using a high-speed CCD camera. The image processing was carried out to investigate the material flow. The results were as follows. When the clearance is small, the material flow in the clearance is toward the sheet material on the die. When the clearance is large, the material flow in the clearance is toward the sheet material under the punch. The area of rollover in the sheet material on the die is equal to the sum of the amount of material flow in the clearance and that in the lateral direction. On the other hand, the area of rollover in the sheet material under the punch is equal to the sum of the amount of material flow in the lateral direction under the punch, that in the clearance and the insufficiency of material. These findings are useful for considering the relationship between the material flow and the formation of rollover in the case that the rollover in the sheet material on the die and that in the sheet material under the punch are evaluated individually.