Geometrical Accuracy in Two-Stage Incremental Sheet Forming with Active Medium

2021 ◽  
pp. 65-74
Author(s):  
S. Thiery ◽  
N. Ben Khalifa
Author(s):  
S. Thiery ◽  
M. Zein El Abdine ◽  
J. Heger ◽  
N. Ben Khalifa

AbstractA strategy to adjust the product geometry autonomously through an online control of the manufacturing process in incremental sheet forming with active medium is presented. An axial force sensor and a laser distance sensor are integrated into the process setup to measure the forming force and the product height, respectively. Experiments are conducted to estimate the bulging behavior for different pre-determined tool paths. An artificial neural network is consequently trained based on the experimental data to continuously predict the pressure levels required to control the final product height. The predicted pressure is part of a closed-loop control to improve the geometrical accuracy of formed parts. Finally, experiments were conducted to verify the results, where truncated cones with different dimensions were formed with and without the closed-loop control. The results indicate that this strategy enhances the geometrical accuracy of the parts and can potentially be expanded to be implemented for different types of material and geometries.


2016 ◽  
Vol 716 ◽  
pp. 395-401 ◽  
Author(s):  
Jan Brüninghaus ◽  
Yan Volfson ◽  
Jobst Bickendorf ◽  
Sigrid Brell-Cokcan

The formability and geometrical accuracy in incremental sheet forming can be increased using a force-controlled support tool. The main problems in using such a kinematic support tool is the positioning of forming and support tools, while maintaining force magnitude and alignment. A new tool for this was developed systematically using a morphological box. It uses a spring controlled rotation of the tool tip to maintain the force. Since the rotation axis is not in line with the tool tip axis and the tool tip can freely rotate around its axis, roll friction conditions can be achieved. The center of gravity of the rotating part of the tool is placed in the rotating axis and the force is therefore independent from the alignment of the tool in space. It has a mechanical stop with locking option in the vertical position and is therefore also fully usable as a forming tool. While the prototype is manually controlled, concepts for a fully automated version have been designed, as well. First tests are in line with results described in literature, showing that direction and magnitude of force have an influence on the formability.


Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 661
Author(s):  
Roman Ulrich Christopher Schmitz ◽  
Thomas Bremen ◽  
David Benjamin Bailly ◽  
Gerhard Kurt Peter Hirt

Incremental sheet forming (ISF) is a flexible sheet metal forming process to realize products within short time from design to the first produced part. Although fundamental research on ISF has been carried out around the world, ISF still misses commonly required tolerances for industrial application. In this study, the influences of tool path as well as intrusion depth of the forming tool into the sheet material on the geometrical accuracy were investigated. In the conducted experiments, both flat and stretch-formed sheet metal blanks with different tool paths and intrusion depths were examined. Experimental and numerical investigations showed that changes in the range of a tenth millimeter of the intrusion depth with a consistent tool path lead to different resulting part geometries. A better understanding of the sensitive influence of the tool path and the intrusion depth on the resulting geometry might lead to more accurate parts in the future.


CIRP Annals ◽  
2019 ◽  
Vol 68 (1) ◽  
pp. 313-316 ◽  
Author(s):  
Noomane Ben Khalifa ◽  
Sebastian Thiery

Author(s):  
Gerhard Hirt ◽  
Roman Kordtomeikel ◽  
Thomas Bremen ◽  
Marvin Laugwitz ◽  
David Bailly

Author(s):  
Abdulmajeed Dabwan ◽  
Adham E Ragab ◽  
Mohamed A Saleh ◽  
Atef M Ghaleb ◽  
Mohamed Z Ramadan ◽  
...  

Incremental sheet forming is a specific group of sheet forming methods that enable the manufacture of complex parts utilizing computer numerical control instead of specialized tools. It is an incredibly adaptable operation that involves minimal usage of sophisticated tools, dies, and forming presses. Besides its main application in the field of rapid prototyping, incremental sheet forming processes can be used for the manufacture of unique parts in small batches. The goal of this study is to broaden the knowledge of the deformation process in single-point incremental forming. This work studies the deformation behavior in single-point incremental forming by experimentally investigating the principal stresses, principal strains, and thinning of single-point incremental forming products. Conical-shaped components are fabricated using AA1050-H14 aluminum alloy at various combinations of fundamental variables. The factorial design is employed to plan the experimental study and analysis of variance is conducted to analyze the results. The grey relational analysis approach coupled with entropy weights is also implemented to identify optimum process variables for single-point incremental forming. The results show that the tool diameter has the greatest effect on the thinning of the SPIF product, followed by the sheet thickness, step size, and feed rate.


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