Prediction and control of pillow defect in single point incremental forming using numerical simulations

Isidore, Besong Besong Lemopi; Hussain, G.; Shamchi, Sahand Pourhassan; Khan, Wasim

doi:10.1007/s12206-016-0422-0

Cited by 37 publications

(12 citation statements)

References 15 publications

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“…Therefore, the geometric deviation in region A is less dependent on the process parameters. On the other hand, the pillow effect that develops in region C develops from the bending of the metal sheet (due to in-plane stresses) [39]. This is because the material is largely deformed in the transverse direction within the tool vicinity.…”

Section: Discussionmentioning

confidence: 99%

Multistage Tool Path Optimisation of Single-Point Incremental Forming Process

et al. 2021

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Single-point incremental forming (SPIF) is a flexible technology that can form a wide range of sheet metal products without the need for using punch and die sets. As a relatively cheap and die-less process, this technology is preferable for small and medium customised production. However, the SPIF technology has drawbacks, such as the geometrical inaccuracy and the thickness uniformity of the shaped part. This research aims to optimise the formed part geometric accuracy and reduce the processing time of a two-stage forming strategy of SPIF. Finite element analysis (FEA) was initially used and validated using experimental literature data. Furthermore, the design of experiments (DoE) statistical approach was used to optimise the proposed two-stage SPIF technique. The mass scaling technique was applied during the finite element analysis to minimise the computational time. The results showed that the step size during forming stage two significantly affected the geometrical accuracy of the part, whereas the forming depth during stage one was insignificant to the part quality. It was also revealed that the geometrical improvement had taken place along the base and the wall regions. However, the areas near the clamp system showed minor improvements. The optimised two-stage strategy successfully decreased both the geometrical inaccuracy and processing time. After optimisation, the average values of the geometrical deviation and forming time were reduced by 25% and 55.56%, respectively.

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Section: Discussionmentioning

confidence: 99%

Multistage Tool Path Optimisation of Single-Point Incremental Forming Process

et al. 2021

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“…Nevertheless, it is still questionable which method can reduce thin- Micari et al [164] hinted that the reduced component accuracy of articles formed by ISF results from the following two typologies of error: springback in the wall and the pillow effect on the minor undeformed base. Isidore et al [165] used Finite Element Analysis (FEA) for the prediction and control of the pillow effect in SPIF. Three-dimensional FEA and experiments were used to carry out incremental forming of aluminium 1050 and study the effect of different tool sizes and shapes.…”

Section: Thickness Distributionmentioning

confidence: 99%

Recent Developments and Future Challenges in Incremental Sheet Forming of Aluminium and Aluminium Alloy Sheets

Trzepieciński

Najm

Oleksik

et al. 2022

Metals

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Due to a favourable strength-to-density ratio, aluminium and its alloys are increasingly used in the automotive, aviation and space industries for the fabrication of skins and other structural elements. This article explores the opportunities for and limitations of using Single- and Two Point Incremental Sheet Forming techniques to form sheets from aluminium and its alloys. Incremental Sheet Forming (ISF) methods are designed to increase the efficiency of processing in low- and medium-batch production because (i) it does not require the production of a matrix and (ii) the forming time is much higher than in conventional methods of sheet metal forming. The tool in the form of a rotating mandrel gradually sinks into the sheet, thus leading to an increase in the degree of deformation of the material. This article provides an overview of the published results of research on the influence of the parameters of the ISF process (feed rate, tool rotational speed, step size), tool path strategy, friction conditions and process temperature on the formability and surface quality of the workpieces. This study summarises the latest development trends in experimental research on, and computer simulation using, the finite element method of ISF processes conducted in cold forming conditions and at elevated temperature. Possible directions for further research are also identified.

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“…The third type of geometric error in the SPIF is a protrusion or concave curvature occurring on the undeformed bottom of the part. This phenomenon is known as a ‘pillow effect’, and according to Isidore et al [ 56 ], it is one of the main reasons for geometric inaccuracy in the SPIF process. The pillow effect is a result of sheet bulging due to the transition of elastic deformations from the non-plastically deformed central zone to the rest of the workpiece [ 57 ] as shown in Figure 1 , but some unknowns regarding this phenomenon exist, making it difficult to predict and control.…”

Section: Accuracy Of the Spif Processmentioning

confidence: 99%

Finite Element Simplifications and Simulation Reliability in Single Point Incremental Forming

et al. 2022

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Single point incremental forming (SPIF) is one of the most promising technologies for the manufacturing of sheet metal prototypes and parts in small quantities. Similar to other forming processes, the design of the SPIF process is a demanding task. Nowadays, the design process is usually performed using numerical simulations and virtual models. The modelling of the SPIF process faces several challenges, including extremely long computational times caused by long tool paths and the complexity of the problem. Path determination is also a demanding task. This paper presents a finite element (FE) analysis of an incrementally formed truncated pyramid compared to experimental validation. Focus was placed on a possible simplification of the FE process modelling and its impact on the reliability of the results obtained, especially on the geometric accuracy of the part and bottom pillowing effect. The FE modelling of SPIF process was performed with the software ABAQUS, while the experiment was performed on a conventional milling machine. Low-carbon steel DC04 was used. The results confirm that by implementing mass scaling and/or time scaling, the required calculation time can be significantly reduced without substantially affecting the pillowing accuracy. An innovative artificial neural network (ANN) approach was selected to find the optimal values of mesh size and mass scaling in term of minimal bottom pillowing error. However, care should be taken when increasing the element size, as it has a significant impact on the pillow effect at the bottom of the formed part. In the range of selected mass scaling and element size, the smallest geometrical error regarding the experimental part was obtained by mass scaling of 19.01 and tool velocity of 16.49 m/s at the mesh size of 1 × 1 mm. The obtained results enable significant reduction of the computational time and can be applied in the future for other incrementally formed shapes as well.

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Prediction and control of pillow defect in single point incremental forming using numerical simulations

Cited by 37 publications

References 15 publications

Multistage Tool Path Optimisation of Single-Point Incremental Forming Process

Multistage Tool Path Optimisation of Single-Point Incremental Forming Process

Recent Developments and Future Challenges in Incremental Sheet Forming of Aluminium and Aluminium Alloy Sheets

Finite Element Simplifications and Simulation Reliability in Single Point Incremental Forming

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