Influence of binder pressure zones on the robustness of restraining forces in sheet metal forming

Leocata, Salvatore; Senner, Thomas; Saubiez, Jean-Marc; Brosius, Alexander

doi:10.1016/j.promfg.2019.02.128

Cited by 6 publications

(3 citation statements)

References 16 publications

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“…He concluded that the drawbead restraining force is affected greatly by friction conditions and bead geometry. Leocata et al [ 26 ] carried out the strip tensile test to analyse the restraining force for different pressure zones. It was found that an increased surface roughness leads to a decreased sensitivity of friction to variations in the amount of lubricant.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Friction Phenomena Existed in Drawbead in Sheet Metal Forming

et al. 2021

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The article presents the results of friction tests of a 0.8 mm-thick DC04 deep-drawing quality steel sheet. A special friction simulator was used in the tests, reflecting friction conditions occurring while pulling a sheet strip through a drawbead in sheet metal forming. The variable parameters in the experimental tests were as follows: surface roughness of countersamples, lubrication conditions, sample orientation in relation to the sheet rolling direction as well as the sample width and height of the drawbead. Due to many factors that affect the value of the coefficient of friction coefficient, artificial neural networks (ANNs) were used to build and analyse the friction model. Four training algorithms were used to train the ANNs: back propagation, conjugate gradients, quasi-Newton and Levenberg–Marquardt. It was found that for all analysed friction conditions and sheet strip widths, increasing the drawbead height increases the COF value. The chlorine-based Heavy Draw 1150 compound provides a more effective friction reduction compared to a LAN-46 machine oil.

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Section: Introductionmentioning

confidence: 99%

Modelling of Friction Phenomena Existed in Drawbead in Sheet Metal Forming

et al. 2021

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“…This is a key factor to consider when attempting to predict industrial forces because, due to the tool elastic deformations that are produced during closing and the geometrical deviations that the tool may have after its machining and hand polishing, an important difference between numerical and experimental results can be found in terms of uplift force. It must also be taken into consideration that in order to achieve an homogeneous contact between the tool surfaces and to counteract the elastic deformation, the different components of industrial stamping tools are generally manually spotted during their initial try-out phase [8]. This way the geometrical deviations between the different contact surfaces are very much reduced which in fact can give as a result an evolution of the uplift forces during the try-out phase.…”

Section: Methodsmentioning

confidence: 99%

“…Gil et al [7] already proved this by showing that numerical errors in the predicted frictional forces generate substantial differences in the final numerical predicted geometry when compared to the experimental one. Furthermore, Leocata et al [8] have recently proved the importance of the binder pressure zones in the robustness of the restraining force, demonstrating that the contact pressure achieved in the inner ring of the drawbead is of high importance and determines the stability of the drawing process. Therefore, an accurate prediction of the uplift force is also important for the optimum performance of drawing tools.…”

Section: Introductionmentioning

confidence: 99%

New drawbead tester and numerical analysis of drawbead closure force

Gil

Mendiguren

Galdos

et al. 2021

Int J Adv Manuf Technol

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Currently, a great deal of controversy exists regarding the real forces generated in drawbeads during sheet metal forming processes. The present work focuses on the analysis of the uplift force. First, a detailed literature review is carried out to analyse previous experimental procedures used to measure uplift forces. It is found that previous setups do not perfectly replicate the real geometry of industrial drawbeads. In order to obtain reliable forces, an experimental drawbead tester capable of adequately replicating industrial drawbeads is developed. Later, a variety of steels ranging from mild steels to 3rd-generation ultra-high-strength steels are tested and reliable uplift and also restraining force values are obtained. The main purpose of the work is to share with the research community reliable experimental data that allows precise evaluation of the accuracy of current drawbead models and that supports the generation of new numerical and equivalent drawbead models. In parallel to the experimental procedure, a step forward in the understanding of the drawbead closing phenomena is also achieved through a 2D numerical model. The main purpose of the model is to identify the variables that greatly affect uplift force. Going beyond previous studies, in which some variables were analysed, the present work covers, in a holistic manner, the impact that material properties, the geometry of drawbeads and contact behaviour between sheet and drawbead have on the uplift force. It is determined that surprisingly minor geometrical deviations in the drawbead nominal geometry have a large impact on the uplift force.

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