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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.
References
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Journal ArticleDOI
TL;DR: First experimental results show that the formability of the alloy Ti Grade 5 (TiAl6V4), which is usually used in aeronautic applications, can be increased.
Abstract: Asymmetric Incremental Sheet Forming (AISF) is a relatively new manufacturing process. In AISF, a CNC driven forming tool imposes a localized plastic deformation as it moves along the contour of the desired part. Thus, the final shape is obtained by a sequence of localized plastic deformations. AISF is suitable for small series production of sheet metal parts as needed in aeronautical and medical applications. Two main process limits restrict the range of application of AISF in these fields. These are the low geometrical accuracy of parts made from titanium alloys or high strength steels and, for titanium alloys, the limited formability at room temperature. In this paper a new concept for laser-assisted AISF is introduced including the required components. Furthermore, the CAX tools used for programming the NC path for the forming tool and the laser spot are illustrated. First experimental results show that the formability of the alloy Ti Grade 5 (TiAl6V4), which is usually used in aeronautic applications, can be increased.

101 citations

Journal ArticleDOI
01 Jul 2001
TL;DR: In this article, an incremental tube-forming method was proposed in which forming is carried out by a series of movements of a hemispherical head tool without using any die or mandrel that corresponds to the product shape.
Abstract: In a previous paper a new incremental tube-forming method was proposed in which forming is carried out by a series of movements of a hemispherical head tool without using any die or mandrel that corresponds to the product shape. This paper aims to develop a similiar method that can form flat metal sheets into three-dimensional shapes without using dedicated dies. For this purpose, very simple and compact tooling is devised and put on the bed of a numerically controlled (NC) machine tool. It can be controlled with an NC program, which is made by commercial CAD/CAM (computer aided design/manufacture) systems. The method is broadly applicable to any product where the outer surface is convex, and is examined for the forming of an aluminium sheet into cones and pyramids having an arbitrary number of sides with a half-apex angle with a minimum of 10°. Sharp edges between adjacent sides of the pyramid are easily formed. The ratio of the wall thickness of the product to that of the original sheet correspo...

93 citations

Journal ArticleDOI
TL;DR: In this paper, three different techniques namely, Artificial Neural Networks (ANN), Support Vector Regression (SVR) and Genetic Programming (GP) have been used for surface roughness estimation in single point incremental forming (SPIF) process.
Abstract: Single point incremental forming (SPIF) is a novel and potential process for sheet metal prototyping and low volume production applications. This article is focuses on the development of predictive models for surface roughness estimation in SPIF process. Surface roughness in SPIF has been modeled using three different techniques namely, Artificial Neural Networks (ANN), Support Vector Regression (SVR) and Genetic Programming (GP). In the development of these predictive models, tool diameter, step depth, wall angle, feed rate and lubricant type have been considered as model variables. Arithmetic mean surface roughness (Ra) and maximum peak to valley height (Rz) are used as response variables to assess the surface roughness of incrementally formed parts. The data required to generate, compare and evaluate the proposed models have been obtained from SPIF experiments performed on Computer Numerical Control (CNC) milling machine using Box–Behnken design. The developed models are having satisfactory goodness of fit in predicting the surface roughness. Further, the GP model has been used for optimization of Ra and Rz using genetic algorithm. The optimum process parameters for minimum surface roughness in SPIF have been obtained and validated with the experiments and found highly satisfactory results within 10% error.

83 citations

Journal ArticleDOI
TL;DR: In this article, the results obtained from a new sheet forming process based on a general purpose CNC machine equipped with a special tool are presented, where all the tool components are designed by FEM simulations which have furnished the value of the applied loads.

79 citations