Papers by Keyword: Single Point Incremental Forming (SPIF)

Abstract: Flanges are commonly used in aircrafts to provide stiffness and support for the assembly Incremental Sheet Forming (ISF) processes have been approached to produce both stretch and shrink flanges as a low-cost alternative in the fabrication of a small number of parts and prototypes. This work analyzes stretch and shrink flanges of AA2024-T3 sheet with different geometries manufactured by Single Point Incremental Forming (SPIF). The numerical simulation using Finite Elements of the flanges allows evaluating the stress in successful and failed flanges. On the one hand, the formability of stretch flanges is usually evaluated in terms of principal strains within the Forming Limit Diagram (FLD). However, this approach does not seem to capture all the physics to explain the enhancement in formability observed in SPIF over the conventional forming. A formability analysis is performed in the field of stress triaxiality versus equivalent plastic strain, discussing the differences between successful and fractured specimens. On the other hand, for shrink flanging, the appearance of wrinkles is analyzed in terms of the compressive stresses along the flange during the incremental forming. This allows to determine a critical limit stress of winkling to predict the failure in practice for a given geometry and forming condition.

Abstract: Single point incremental forming (SPIF) is a choice of interest in many manufacturing industries due to its wide range of applications. Materials such as copper, aluminum, steel, and many others formed various complex shapes through this process. However, the forming process could sometimes result in process defects, which could strongly influence the formed parts' geometric accuracy. The twist defect is one of them, which incrementally twists the forming sheet with a small angle at each forming step. In this paper, twist phenomena in the SPIF process have been investigated both numerically and experimentally. In the experiment, Aluminum Alloy (AA5052) was used to form a truncated pyramid shape, and a room temperature tensile test has been conducted to achieve the material's tensile properties. Then, the material property used in the simulation study of the SPIF using LS-DYNA software, where twist defect, stresses, strain, and thickness distribution are studied. The results from simulation and experiment show significant similarity against the expected results and this conveys that the proposed FE model of the SPIF process can be used to investigate the presence of twist, distributions of stress and strain, and thinning locations in the formed part.

Abstract: The Single Point Incremental Forming Process (SPIF) is a forming technique of sheet material based on layered manufacturing principles. The forming tool is moved along the tool path while the edges of sheet material are clamped. The finished part is manufactured by the CNC machine. SPIF involves extensive plastic deformation and the description of the process is more complicated by highly nonlinear boundary conditions, namely contact and frictional effects have been accomplished. However, due to the complex nature of these models, numerical approaches dominated by the FEA are now in widespread use. The paper presents the data and main results of a study on effect of using cover blank in SPIF through FEA. The considered SPIF has been studied under certain process conditions referring to the test work piece, tool, etc., applying ANSYS 11.0. The results show that the simulation model can predict an ideal profile of processing track, spring back error of SPIF, the behavior of contact tool-work piece, the product accuracy by evaluation its thickness and strain distributions, the contact status and chattering among surface interface tool-work piece.

Abstract: Incremental Sheet Forming (ISF) process is Innovative and cost effective technology trend for forming products in manufacturing industries. The current research is to study and investigate the influence of incremental sheet forming process parameters on response surfaces of aluminium alloy sheet components. In this experiment, Aluminium alloy AA1050 sheet was selected to process forming by using CNC machining centre without expensive dies. Individual and interactive effect of different factors such as, thickness of sheet, tool diameter, vertical step, feed rate, and tool rotational speed at different levels were assessed to improve the processing time. For the design of experiment (DOE), Taguchi’s L27 orthogonal array was used to investigate and optimize the influencing ISF process parameters. From ANOVA results, it was found that for thickness reduction, the influencing factors were as following; feed rate (21.40 %); for roughness, tool rotation speed (20.43 %) and for hardness, thicknesses of sheet (39.49 %). Response Surface Methodology (RSM) showed that optimal values obtained were 0.46 mm, 10 mm, 0.6818 mm, 2232.32 mm/min., and 2626 rpm for thickness of sheet, tool diameter, vertical step, feed rate and tool rotational speed respectively. For percentage thickness reduction of 59.6%, minimum roughness 2.09μm, and maximum hardness 41.7 BHN, the confirmatory test showed values of 64.78 % thickness reduction, roughness of 2.14μm and hardness of 44.82 BHN that were in agreement with the predicted value.

Abstract: Single Point Incremental Forming (SPIF) has become a popular technology of forming sheet materials in the recent decades. However, the springback phenomenon, an inborn property of almost all elasto-plastic materials, reduces the precision of dimensions of the products by the finished forming session. This paper attempts to find out a measure to minimize this unwanted obstacle by using both empirical and simulating methods in order to define the relations of springback values among the forming parameters such as diameter of the forming tool, its revolution per minute, its velocity and its feed rate. Analyzing these equations to extract the appropriate parameters of forming for enhancing the precision of SPIF products is the final aim of this paper.

Abstract: The Single Point Incremental Forming Process, SPIF, is a forming technique of sheet material based on layered manufacturing principles. The forming tool is moved along the tool path while the edges of sheet material are clamped on fixture by holder. The finished part is performed by the CNC milling machine. The description of the process is more complicated by highly nonlinear boundary conditions, namely contact and frictional effects have been accomplished. Due to the fact that the mathematical analysis of SPIF is complex, numerical approaches dominated by the FEA are now in widespread use. The paper presents the data and main results of a study concerning the effect of forming tool profile on SPIF through FEA, that permits the modeling of complex geometries, material behavior and boundary conditions. SPIF has been studied under certain process conditions referring to the test workpiece, tool, etc., using ANSYS 11.0. The results showed that the model of simulation can predict an ideal profile of processing track, spring back error of SPIF, the behavior of contact tool - workpiece, the accuracy of product by evaluation the strain and the stress distributions between forming tool and workpiece surface interface, and sample of results have been demonstrated.

Abstract: The Single Point Incremental Forming Process (SPIF) involves extensive plastic deformation. The description of the process is more complicated by highly nonlinear boundary conditions, namely contact and frictional effects have been accomplished. The SPIF analysis is mathematically complex. However, due to the complex nature of these models, numerical approaches dominated by the FEA are now in widespread use. The paper presents the data and main results of a study on SPIF through FEA, that permits the modeling of complex geometries, boundary conditions and material behavior. SPIF have been studied under certain process conditions referring to the test workpiece, tool, etc., using ANSYS 11.0. An important result is showing that the model of simulation can give as clearly the behavior of contact tool - workpiece and the effect it on strain and stress distributions, also on the accuracy of product. Relevant dependences between tool and workpiece surface interface and sample of results have been demonstrated.

Abstract: In this paper the influence of the bending effect in the formability of AISI 304 metal sheets in incremental forming is analyzed. For this purpose, a series of single point incremental forming tests were carried out using a variety of tool diameters and step downs. The spifability (formability in single point incremental sheet forming) of the metal sheets was studied in the light of circle grid analysis by means of the 3D deformation digital measurement system ARGUS®. The results show the importance of the bending effect, induced by the tool radius, in the enhancement of formability in incremental forming compared to conventional forming processes.

Abstract: Incremental sheet forming is a versatile manufacturing technology for small series production. This technique is, however, still challenged by limited accuracy. In incremental forming, each shape comes with its unique complexity and typical geometrical deviations. In this work, the applicability of FE modeling for the prediction of geometric inaccuracies in a shallow wall angle cone has been studied. Typical geometric inaccuracies for shallow sloped parts have been investigated both experimentally and by means of simulation. The evolution of underforming of the cone base as well as overforming of the cone wall during SPIF forming of truncated cone have been analysed. Based on the evaluation of the contact zone between the tool and the sheet, it has been concluded that an extended deformation of the sheet outside the tool contact zone is responsible for the overforming of the wall.

Abstract: Single point incremental forming has attracted the interest of researchers in the last decade for the production of prototypes and small batch production of sheet-based parts [1, 2]. This technique allows the manufacture of parts without using expensive die sets. The SPIF (Single point incremental forming) process can be performed on different equipments such as adapted CNC milling machines, serial robots and built proposed machines [3]. Every solution has advantages and disadvantages. This work presents the CAD/CAM strategies for a parallel kinematics SPIF machine, designed and built at the University of Aveiro [3]. This machine brings a new approach to the SPIF industry. The machinery used to perform SPIF operations has limitations in their work volume with limited movements and in the magnitude of applicable forces. With that in mind, this machine was projected to overcome that obstacle, and was provided with a system with 6 degrees of freedom, while maintaining the ability to apply high loads. The disadvantage is the increase in volume occupied by the kinematic system. The manufacture of new parts could be reached out with more flexibility on the chosen tool path. The first step is the product design in the commercial CAD system. Next step is generating the tool path of the forming tool. This step is very important to achieve the desired part shape. It is used a commercial CAM system (EdgeCAM 2012®), which has resources from three up to five axis strategies. The last step is to send the information to the machine’s control system, based on real-time software. This paper will describe each step with more details.