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Book ChapterDOI

Experimental Investigation on Geometric Error in Single-Point Incremental Forming with Dummy Sheet

TL;DR: In this paper, the influence of dummy sheet thickness, step size, wall angle, and feed rate on geometrical error in terms of root-mean-squared error (RMSE) of formed part is investigated.
Abstract: Single-point incremental forming (SPIF) process is an emerging sheet metal forming process in which constraint of using dedicated press tools is eliminated. Some process limitations like poor surface finish, longer forming time, higher geometrical error, and uneven wall thickness distribution restrict its applicability in sheet metal industry. But SPIF process with dummy sheet has the capability to overcome some of the prevailing limitations of SPIF process. In the present paper, influence of dummy sheet thickness, step size, wall angle, and feed rate on geometrical error in terms of root-mean-squared error (RMSE) of formed part is investigated. Box Behnken design is used to design the experiments. From the analysis of experimental result, it is found that dummy sheet thickness, step size, and wall angle are significant process parameters influencing RMSE. No significant influence of feed rate on RMSE is observed. RMSE increases with increase in dummy sheet thickness and wall angle, while it decreases with increases in step size. As feed rate increases, there is nominal decrease in RMSE which is desirable. So higher feed rate is recommended to reduce forming time. Further, empirical model is developed to predict RMSE. Also, optimization of process parameters is performed to minimize RMSE. Confirmation experiments were performed in order to check the accuracy of developed predictive model and it is found that predicted results are in good agreement with experimental results.
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Journal ArticleDOI
TL;DR: In this paper, a part whose geometry was chosen to be representative for sheet formability through incremental sheet forming (ISF) was formed considering the different ISF techniques, and the influence on the produced part of the adopted tool path step depth increment was investigated.
Abstract: The present paper deals with incremental sheet forming (ISF), a metal forming process developed in the last 20 years. Main advantages characterising this technology are its high flexibility and the possibility of reducing development times and costs. ISF consists of a simple hemispherical tool, moved by a CNC machine or a robot, which locally deforms a metal sheet moving along a defined path. The desired part profile can be obtained using three ISF techniques: single point incremental forming (SPIF) and two points incremental forming (TPIF) with either negative or positive die. In this work, a part, whose geometry was chosen to be representative for sheet formability through ISF, was formed considering the different ISF techniques. Moreover, the influence on the produced part of the adopted tool path step depth increment was investigated. Experimental tests were conducted and the results were analysed in terms of forming forces, material formability, process accuracy and final part thickness.

17 citations

Journal ArticleDOI
TL;DR: In this paper, a wide investigation on 6082-T6 aluminium alloy was carried out with the aim to determine the influence of process parameters on thinning behavior, and the ANOVA analysis was executed on the experimental data designed by DOE.
Abstract: Incremental Sheet Forming is a promising process for the small batch manufacturing of sheet metal parts due to its flexibility and to the high formability achievable. In the Incremental Sheet Forming process a localised state of deformation is imposed by the CNC controlled motion of a simple tool. Although the process potentiality, its industrial application is still bordered by some drawbacks such as excessive material thinning, part inaccuracy or process time. In the last years, several works were carried out by the researcher all over the world mainly focused on material formability. However further efforts are required in order to overcome the above specified drawbacks. In particular, concerning the material thinning, the simple Sine Law allows to predict the actual sheet thickness in a rough way. In fact, the Sine Law takes into account the initial thickness and the wall slope angle, neglecting all the others process parameters. For this reason, a more robust tool which takes into account the whole process complexity is strongly necessary. In this paper a wide investigation on 6082-T6 aluminium alloy was carried out with the aim to determine the influence of process parameters on thinning behaviour. Finally, with the aim to obtain a reliable model to predict the thinning, the ANOVA analysis was executed on the experimental data designed by DOE. All the other details are reported in the paper.

17 citations

Journal ArticleDOI
Haibo Lu1, Yanle Li1, Zhaobing Liu1, Sheng Liu1, Paul A. Meehan1 
TL;DR: In this paper, a study on step depth, a critical parameter in ISF, for improving the geometric accuracy, surface quality and formability is presented. But the part geometric accuracy obtained in the current ISF process, however, has not met the industry specification for precise part fabrication.
Abstract: Incremental Sheet Forming (ISF) is a new-emerging sheet forming process well suited for small batch production or prototyping because it does not need any dedicated dies or punches. In this forming process, sheet metal parts are formed by a smooth-end tool in a stepwise way, during which plastic deformation is highly localized around the tool end. The part geometric accuracy obtained in the current ISF process, however, has not met the industry specification for precise part fabrication. This paper deals with a study on step depth, a critical parameter in ISF, for improving the geometric accuracy, surface quality and formability. Two sets of experiments were conducted to investigate the influence of step depth on part quality. Dimensional accuracy, surface morphology and material fracture of deformed parts were compared and analysed. An optimum value of step depth was suggested for forming a truncated cone. The present work provided significant fundamental information for the development of an advanced ISF control system on tool path control and optimization.

17 citations