Prediction of Path Deviation in Robot Based Incremental Sheet Metal Forming by Means of an Integrated Finite Element – Multi Body System Model

2009 ◽  
Vol 410-411 ◽  
pp. 365-372 ◽  
Author(s):  
Horst Meier ◽  
Roman Laurischkat ◽  
C. Bertsch ◽  
Stefanie Reese
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Tool Path ◽  
Body System ◽  
True Path ◽  
Incremental Sheet Metal Forming ◽  
Path Prediction ◽  
Multi Body

The main influence on the dimensional accuracy in incremental sheet metal forming results from the compliance of the involved machine structures and the springback effects of the workpiece. This holds especially for robot based sheet metal forming, as the stiffness of the robot’s kinematics compared to a conventional machine tool is low, resulting in a significant deviation of the planned tool path and therefore in a shape of insufficient quality. To predict these deviations, a coupled process structure model has been implemented. It consists of a finite element (FE) approach to simulate the sheet forming and a multi body system (MBS) modeling the compliant robot structure. The forces in the tool tip are computed by the FEA, while the path deviations due to these forces can be obtained using the MBS model. Coupling both models gives the true path driven by the robots. Built on this path prediction, mechanisms to compensate the robot’s kinematics can be implemented. The current paper describes an exemplary model based path prediction and its validation.

Incremental sheet metal forming of Ti–6Al–4V alloy for aerospace application

2020 ◽  
Vol 44 (1) ◽  
pp. 56-64 ◽  
Author(s):  
R. Mohanraj ◽  
S. Elangovan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Sheet Metal ◽  
Process Parameters ◽  
Experimental Work ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Geometric Accuracy ◽  
Element Analysis ◽  
Incremental Sheet Metal Forming

Driven by an increasing demand from the aerospace industry, thin sheet forming of titanium and its alloys is gaining prominence in scientific research. The design and manufacture of aerospace components requires the utmost precision and accuracy. It is essential to have good control over the process parameters of the forming process. Processes such as incremental sheet metal forming (ISMF) are highly controlled in the current manufacturing environment, but improvements in geometric accuracy and thinning are still needed. Although ISMF has greater process competence for manufacturing airframe structures with minimal costs, the process has its own negative effect on geometric accuracy due to elastic springback and sheet thinning. In this study, finite element analysis and experimental work are performed, considering process parameters such as spindle speed, feed rate, step depth, and tool diameter, to study the geometric accuracy and thinning of Ti–6Al–4V alloy sheet, while incrementally forming an aerospace component with asymmetrical geometry. The results are useful for understanding the geometric accuracy and thinning effects on parts manufactured by single point incremental forming (SPIF). Results from finite element analysis and experimental work are compared and found to be in good agreement.

New Method for Blank Expansion of Rectangular Box

2011 ◽  
Vol 308-310 ◽  
pp. 1004-1007
Author(s):  
Liu Ru Zhou ◽  
Hai Ming Wan
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Tool Path ◽  
Incremental Forming ◽  
Apex Angle ◽  
Forming Limit ◽  
Forming Process ◽  
Incremental Sheet Metal Forming ◽  
Planning Experiment

The principle of NC incremental sheet metal forming as well as the process planning, experiment of the square conical box forming are presented. Because the deformation of sheet metal only occurs around the tool head and the deformed region is subjected to stretch deformation and thins, and surface area increases. Sheet metal forming stepwise is to lead to the whole sheet metal deformation. The sine law indicates that the thickness of the square conical box wall is close to zero when the half-apex angle of the square conical box wall is close to zero. Therefore, we must know the forming limit half-apex angle to ensure that the forming can be carried out successfully, i.e., to ensure that the deformed region with a certain thickness will not fracture. It will succeed in square conical box incremental forming in a single tool-path if the forming is carried out with an angle which is larger than the forming limit half-apex angle. The fracture in the forming component can be avoided by these methods. A square conical box of uniform wall-thickness can be formed by NC incremental forming process. The thickness of deformation area is increased by increasing half-apex angle. The wrinkle in the forming component can be avoided by these methods.

Compensations for Tool Path to Enhance Accuracy During Double Sided Incremental Forming

2015 ◽  
Author(s):  
Rakesh Lingam ◽  
Anirban Bhattacharya ◽  
Javed Asghar ◽  
N. Venkata Reddy
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Tool Path ◽  
Incremental Forming ◽  
Single Point ◽  
Three Dimensional ◽  
Geometric Accuracy ◽  
Forming Process ◽  
Incremental Sheet Metal Forming

Incremental Sheet Metal Forming (ISMF) is a flexible sheet metal forming process that enables forming of complex three dimensional components by successive local deformations without using component specific tooling. ISMF is also regarded as die-less manufacturing process and in the absence of part-specific dies, geometric accuracy of formed components is inferior to that of their conventional counterparts. In Single Point Incremental Forming (SPIF), the simplest variant of ISMF, bending near component opening region is unavoidable due to lack of support. The bending in the component opening region can be reduced to a larger extent by another variant of ISMF namely Double Sided Incremental Forming (DSIF) in which a moving tool is used to support the sheet locally at the deformation zone. However the overall geometry of formed components still has unacceptable deviation from the desired geometry. Experimental observation and literature indicates that the supporting tool loses contact with the sheet after forming certain depth. Present work demonstrates a methodology to enhance geometric accuracy of formed components by compensating for tool and sheet deflection due to forming forces. Forming forces necessary to predict compensations are obtained using force equilibrium method along with thickness calculation methodology developed using overlap that occurs during forming (instead of using sine law). Results indicate that there is significant improvement in accuracy of the components produced using compensated tool paths.

The Simulation of Robot Based Incremental Sheet Metal Forming by Means of a New Solid-Shell Finite Element Technology and a Finite Elastoplastic Model with Combined Hardening

2011 ◽  
Vol 473 ◽  
pp. 875-880 ◽  
Author(s):  
Yalin Kiliclar ◽  
Roman Laurischkat ◽  
Stefanie Reese ◽  
Horst Meier
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Kinematic Hardening ◽  
Industrial Robots ◽  
Solid Shell ◽  
Forming Process ◽  
Incremental Sheet Metal Forming ◽  
Shell Finite Element

The principle of robot based incremental sheet metal forming is based on flexible shaping by means of a freely programmable path-synchronous movement of two tools, which are operated by two industrial robots. The final shape is produced by the incremental infeed of the forming tool in depth direction and its movement along the geometry’s contour in lateral direction. The main problem during the forming process is the influence on the dimensional accuracy resulting from the compliance of the involved machine structures and the springback effects of the workpiece. The project aims to predict these deviations caused by resiliences and to carry out a compensative path planning based on this prediction. Therefore a planning tool is implemented which compensates the robot’s compliance and the springback effects of the sheet metal. Finite element analysis using a material model developed at the Institute of Applied Mechanics (IFAM) [1] has been used for the simulation of the forming process. The finite strain constitutive model combines nonlinear kinematic and isotropic hardening and is derived in a thermodynamical setting. It is based on the multiplicative split of the deformation gradient in the context of hyperelasticity. The kinematic hardening component represents a continuum extension of the classical rheological model of Armstrong–Frederick kinematic hardening which is widely adopted as capable of representing the above metal hardening effects. The major problem of low-order finite elements used to simulate thin sheet structures, such as used for the experiments, is locking, a non-physical stiffening effect. Recent research focuses on the large deformation version of a new eight-node solid-shell finite element based on reduced integration with hourglass stabilization. In the solid-shell formulation developed at IFAM ([2], [3]) the enhanced assumed strain (EAS) concept as well as the assumed natural strain (ANS) concept are implemented to circumvent locking. These tools are very important to obtain a good correlation between experiment and simulation.

Robot-Based Incremental Sheet Metal Forming – Increasing the Part Accuracy in an Automated, Industrial Forming Cell

2009 ◽  
Vol 410-411 ◽  
pp. 159-166 ◽  
Author(s):  
Horst Meier ◽  
B. Buff ◽  
V. Smukala
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Tool Path ◽  
Cost Effective ◽  
Programming System ◽  
Forming Process ◽  
Incremental Sheet Metal Forming ◽  
Metal Forming Process ◽  
Formed Part

This paper describes new developments in incremental, robot-based sheet metal forming (Roboforming). Roboforming is a dieless sheet metal forming process which ensures cost-effective manufacturing of prototype parts and small batches. An approach for increasing the part accuracy in Roboforming is presented. It is developed in a cooperative project funded by the German Federal Ministry of Education and Research called Roboforming. The project concentrates on the development of an industrial applicable system design. The use of standard components allows a modular and scalable set-up. A servo loop, consisting of sensors and a programming system, represents the basis of this design and shall guarantee higher part accuracies by measuring the deviations between a formed part and its target geometry. The deviations are used to derive corrected tool paths. The correction is performed by an adjustment vector for every point on the tool path. The theory for this strategy and first results are presented in this paper.

The Effect of Forming Half-Apex Angle on Incremental Sheet Metal Forming

2010 ◽  
Vol 139-141 ◽  
pp. 1514-1517 ◽  
Author(s):  
Liu Ru Zhou
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Tool Path ◽  
Sheet Material ◽  
Sheet Thickness ◽  
Apex Angle ◽  
Forming Limit ◽  
Forming Technology ◽  
Incremental Sheet Metal Forming

The incremental sheet metal forming technology is a flexible forming technology without dedicated forming dies. The locus of the forming tool can be adjusted by correcting the numerical model of the product. The effect of forming half-apex angle on forming process with all kind of sheet material, sheet thickness and ironing ratio is researched. The limit half-apex angle is different for all kind of sheet material and thickness. The limit half-apex angle is smaller for the larger thickness of sheet metal. It will succeed in square conical box incremental forming in a single tool-path if the forming is carried out with an angle which is larger than the forming limit half-apex angle θ. The ironing ratio ψt is decided by the forming half-apex angle θ. The ironing ratio ψt varies with θ. The ironing ratio ψt is smaller when is larger.

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