Effect of inclination and rotation of the sheet on sheet thinning and formability in robot assisted incremental sheet metal forming
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Incremental sheet forming
Material Flow
Incremental Sheet Forming (ISF) is a relatively new flexible sheet metal forming process mainly oriented to small batches production and prototyping. The technology has been conceived to enable flexible forming of sheet metal parts based on CNC governed punch movements, being the use of conventional milling machines possible if vertical maximum force is controlled. During the process, a simple shape punch is moved against the surface of the sheet, such that a localised deformation is caused, and the use of spatial punch movements enables the forming of complex 3D shapes.However, the process has some drawbacks: high geometrical inaccuracies, an emphasised problem in complex non‐axisymmetric parts, poor final surface quality due to the friction between the punch and the blank, limitations to obtain steep walls and the need of large process times due to the nature of the process.In this paper, the stretch forming is used together with the Incremental Sheet Forming in order to overcome the process limitations, aiming to optimise the material flow and minimise the thinning. Numerical, Finite Element Modelling, and experimental results are presented using a real case study.
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Material Flow
Incremental sheet forming
Deep drawing
Rapid Prototyping
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Forming limit diagram
Flanging
Incremental sheet forming
Formality
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Incremental sheet forming
Stylus
Deep drawing
Metal forming
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Incremental sheet forming
Material Flow
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Abstract In this work it is assessed the potential of combining conventional and incremental sheet forming processes in a same sheet of metal. This so-called hybrid forming approach is performed through the manufacture of a pre-forming by conventional forming, followed by incremental sheet forming. The main objective is analyzing strain evolution. The pre-forming induced in the conventional forming stage will determine the strain paths, directly influencing the strains produced by the incremental process. To conduct the study, in the conventional processes, strains were imposed in three different ways with distinct true strains. At the incremental stage, the pyramid strategy was adopted with different wall slopes. From the experiments, the true strains and the final geometries were analyzed. Numerical simulation was also employed for the sake of comparison and correlation with the measured data. It could be observed that single-stretch pre-strain was directly proportional to the maximum incremental strains achieved, whereas samples subjected to biaxial pre-strain influenced the formability according to the degree of pre-strain applied. Pre-strain driven by the prior deep-drawing operation did not result, in this particular geometry, in increased formability.
Incremental sheet forming
Deep drawing
Strain (injury)
Pyramid (geometry)
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Incremental sheet metal forming is becoming a popular approach for forming intricate shapes especially for rapid prototyping and small batch production of sheet metals. In this work, the formability of Aluminium sheet metal in a single-point incremental forming (SPIF) has been investigated numerically and the effect of the feed rate, the vertical feed (pitch) and the spindle revolution on the formability have been studied. Parameters study results built a base for enhancing SPIF process and presenting two approaches to optimize forming path. In these approaches, variation of vertical pitch has been considered and the effects of this parameter on the strain distribution and formability have been studied. It is found that these methods normalize the strain distribution and improve the formability. Finite element method (FEM) with the aid of design of experiments (DOE) technique is used for predicting the parameters effects and optimizing forming path. Experiments are also carried out to verify the validity of numerical results.
Incremental sheet forming
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Material Flow
Incremental sheet forming
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Abstract Unlike conventional forming processes, incremental forming (IF) does not require any part-specific tooling. It is a flexible forming process that is suitable to form user-specific shapes and for low volume production. The IF process has been recognized as a promising manufacturing process over conventional forming for the materials having decent formability. However, it does not give reliable results while forming hard to form materials. A few investigations revealed that heat plays a vital role in enhancing the formability. On heating, the yield stress of the materials gets reduced, the ductility increases, and hence the formability improves. Thus, for the materials having poor formability, an advance IF technique, elevated temperature incremental forming (ET-IF), has been developed. ET-IF involves incremental forming of the sheets while being heated by an external heat supply. This research study focuses on the execution of the ET-IF process and its comparison with the conventional IF process. A radiation type heating device to perform the ET-IF process is designed and fabricated. The experimental investigations were carried out on 1 mm thick AA 1050 sheets by carrying out the IF process at room temperature and enhanced temperatures. Experimentation was initiated with performing straight grove tests, which were later extended to form a few more shapes. Experimental results confirm the delay in fracture and intensification of formability with the ET-IF process in comparison to that of the IF process at room temperature. The work overcomes the limitation and enlarges the scope of application of the IF process.
Incremental sheet forming
Ductility (Earth science)
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