Asymmetric single point incremental forming of sheet metal

A review on tailored blanks—Production, applications and evaluation

Shape and dimensional accuracy in Single Point Incremental Forming: State of the art and future trends

Considerable changes have occurred in metal forming in the last decade. A record of these changes can be found in keynote papers presented by the members of the Scientific Technical Committee—Forming, at the CIRP Annual General Meeting each year. The keynote papers are excellent references on important developments in metal forming and are used as a reference, globally. Not only is this paper a compendium of most of the keynotes presented, but from 2001 onward, it has updates on new information on five keynote subject areas. The authors of each keynote have written an update with new information that has developed since the writing of the keynote. The authors of each section are shown in order of presentation.

Metal forming progress since 2000

Single point incremental forming (SPIF) suffers from process window limitations which are strongly determined by the maximum achievable forming angle. Forming consecutive, intermediate shapes can contribute to a significantly enlarged process window by allowing steeper maximum wall angles for a range of part geometries. In this paper an experimentally explored multi-step toolpath strategy is reported and the resulting part geometries compared to simulation output. Sheet thicknesses and strains achieved with these multi-step toolpaths were verified and contribute to better understanding of the material relocation mechanism underlying the enlarged process window.

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Process window enhancement for single point incremental forming through multi-step toolpaths

Forming strategies and Process Modelling for CNC Incremental Sheet Forming

Incremental CNC sheet forming (ISF) is a relatively new sheet metal forming process for small batch production and prototyping. In ISF, a blank is shaped by the CNC movements of a simple tool in combination with a simplified die. The standard forming strategies in ISF entail two major drawbacks: (i) the inherent forming kinematics set limits on the maximum wall angle that can be formed with ISF. (ii) since elastic parts of the imposed deformation can currently not be accounted for in CNC code generation, the standard strategies can lead to undesired deviations between the target and the sample geometry.Several enhancements have recently been put forward to overcome the above limitations, among them a multistage forming strategy to manufacture steep flanges, and a correction algorithm to improve the geometric accuracy. Both strategies have been successful in improving the forming of simple parts. However, the high experimental effort to empirically optimize the tool paths motivates the use of process model...

Modeling of Optimization Strategies in the Incremental CNC Sheet Metal Forming Process

The work detailed in this paper focuses on a new forming strategy for the CNC incremental sheet forming (ISF) process that is appropriate to form steep flanges, e.g. for parts designed for deep-drawing. When parts are designed for deep-drawing, they usually contain steep or rectangular side walls that cannot be manufactured using the standard ISF strategies. Unlike prior approaches to obtain steep flanges through ISF, the present method achieves a rough approximation to the final part already in the preforming stage. This can be accomplished without excessive sheet thinning due to sheet bending and stretching at this stage. As a consequence, additional material can be used for the finishing stages, thus yielding a final part with largely reduced thinning. After basic studies on a simple benchmark problem, the new bending/stretching strategy is tested with an industrially applied part that is usually produced by deep-drawing. Finally, the ISF workpiece is evaluated against the deep-drawn component with respect to sheet thickness and geometric accuracy.

A new forming strategy to realise parts designed for deep-drawing by incremental CNC sheet forming

With respect to the preserving of ressources, lightweight construction and the application of new materials are becoming more and more important. This paper focuses on the manufacturing and processing of tailored products, i.e. Tailor Rolled Blanks (TRB). Their load optimised structure enables new approaches in lightweight construction. Contrary to the production of this kind of semi-finished products their further processing is still a challenging task. Investigation results of deep drawing and bending of Tailor Rolled Blanks with special emphasis on the avoidance of wrinkling and compensation of springback are presented. In addition to this, a new sheet forming process is described, which offers high potential especially towards prototyping and small series. Flexible CNC-controlled Incremental Sheet Forming is characterised by a systematical thinning of the processed areas with steep flanges. A combination of this process with dedicated blanks seems promising to obtain any kind of thickness distribution on the final product.

Manufacturing of sheet metal parts from tailor rolled blanks

The present paper focuses on a new methodology to quantitatively evaluate finite element calculations on incremental sheet forming (ISF). ISF is a new manufacturing process for prototypes and small lot sizes. In ISF, a part is manufactured by the CNC-driven movement of a simple tool, giving rise to very challenging problems concerning the efficient modeling of the alternating contact conditions and the material's response to the cyclic deformation. The quantitative validation of the finite element analysis is achieved by an optical deformation measurement system which has been enhanced by a new calibration procedure, yielding a precisely defined local coordinate system for deformation measurements during forming. In combination with mapping algorithms for large point sets, this allows for a quantitative validation of process simulations and material input data.

J. Ames

Papers

Forming strategies and Process Modelling for CNC Incremental Sheet Forming

Modeling of Optimization Strategies in the Incremental CNC Sheet Metal Forming Process

A new forming strategy to realise parts designed for deep-drawing by incremental CNC sheet forming

Manufacturing of sheet metal parts from tailor rolled blanks

Quantitative Validation of FEM Simulations for Incremental Sheet Forming Using Optical Deformation Measurement