scholarly journals Strain Induced Surface Change in Sheet Metal Forming: Numerical Prediction, Influence on Friction and Tool Wear

2021 ◽  
Vol 5 (2) ◽  
pp. 29
Author(s):  
Yutian Wu ◽  
Viktor Recklin ◽  
Peter Groche
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Wear Behavior ◽  
Numerical Prediction ◽  
Wear Testing ◽  
Surface Roughening ◽  
Bead Geometry ◽  
Friction Behavior ◽  
Strip Drawing

In sheet metal forming, free deformation of the sheet takes place frequently without contact with forming tools. The pre-straining resulting from the free deformation leads to a surface roughening of the sheet metal. It is assumed that the roughening has an influence on friction and wear behavior of the following forming process as well as the painting quality after the manufacturing. In this paper, a numerical prediction based on a polycrystalline model is first proposed to predict the effect of surface roughing based on the material data of the as-received state of the sheet metal. Different states of strain are analyzed and the numerical result is validated through experimental evaluation. Besides the numerical prediction, the friction behavior after pre-straining is evaluated in strip drawing tests and the coefficient of friction (COF) is calculated. For interpretation of the measured COF, the surface roughness after the friction test and the surface image are evaluated by a transparent toolset. It is shown that the surface transformation as a result of pre-straining has a negative influence on the lubricating effect of the sheet metal and degrades the friction behavior. Finally, the influence of the strain-induced surface roughening on wear is discussed based on wear testing in strip drawing test with draw bead geometry.

Effects of Rolling Direction and Lubricant on Friction in Sheet Metal Forming

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Xiaojun Liu ◽  
Mathias Liewald ◽  
Dina Becker
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Rolling Direction ◽  
Alloy Sheet ◽  
Friction Behavior ◽  
Drawing Test ◽  
Strip Drawing ◽  
The Coefficient Of Friction ◽  
Surface Microstructures

Lubrication and friction at workpiece-tool interface play an important role in product quality control of sheet metal forming process. Surface microstructures of sheets have a great influence on the development of lubrication films. In order to investigate the effects of the rolling direction of aluminum alloy sheet and lubricant on the friction behavior in sheet metal forming, strip drawing test was used. The sample used was electric discharge texturing (EDT) surface. Lubricants, both with and without additives, were used. The strip drawing tests were performed at angles between the sliding and rolling directions of 0–90 deg. Variations in the sheet surface topography were analyzed by comparing the sheet surface microstructures and its 3D surface parameters before and after the strip drawing test. Results of the strip drawing tests indicate that the kind and amount of lubricant have great influences on friction at the interface, and the lubricant with additives benefits improving the friction behavior between the sheet and the tool. The EDT surface of the aluminum alloy sheet has an anisotropic frictional property during deep drawing process due to different angles between the sliding and rolling directions. When the sliding direction is parallel to the rolling direction, the coefficient of friction has the highest value. When the angle between the sliding and rolling directions increases, the coefficient of friction decreases. The surface microstructure of the sheets after the strip drawing test at different angles between the sliding and rolling directions has been modified, and its 3D surface parameters decrease significantly to a different degree.

scholarly journals Temperature induced friction increase in friction test and forming demonstrator for sheet metal forming

2021 ◽  
Author(s):  
Jan Filzek ◽  
Daniel Keil ◽  
Holger Schröder
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Transient Effects ◽  
Friction Test ◽  
Drawing Test ◽  
Machine Operators ◽  
Strip Drawing ◽  
Flat Strip ◽  
The Individual

High process stability is needed in sheet metal forming industry. This can be achieved by predicting and controlling the transient process and temperature variation, especially at start of production. In this connection, the temperature induced friction changing plays a significant role because it leads to product failures. The handling of the transient friction effects is currently done reactively, based on the individual experience of the machine operators. In future, those transient effects need to be controlled. This paper shows initially an analysis of the temperature induced friction increase in a well-known and proven flat strip drawing test. Different tribological systems were tested at tool temperatures between 20 and 80 °C. The temperature increase results in a higher friction of up to 77 %. Several influences on friction increase will be presented. These friction influences were verified afterwards with a heated forming demonstrator under laboratory conditions.

scholarly journals Numerical modelling of microscopic lubricant flow in sheet metal forming. Application to plane strip drawing

2017 ◽  
Vol 112 (3) ◽  
pp. 203-237 ◽  
Author(s):  
Y. Carretta ◽  
R. Boman ◽  
J. Bech ◽  
N. Legrand ◽  
M. Laugier ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Lubricant Flow ◽  
Strip Drawing

scholarly journals Wear Behavior of MoS 2 Lubricant Layers During Sheet Metal Forming

2017 ◽  
Vol 183 ◽  
pp. 357-362 ◽  
Author(s):  
Bernd-Arno Behrens ◽  
Hans Jürgen Maier ◽  
Sven Hübner ◽  
Christian Bonk ◽  
Amer Almohallami ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Wear Behavior

scholarly journals Experimental identification of essential features of micro strip drawing with double deflection

2018 ◽  
Vol 43 (2) ◽  
pp. 1-5
Author(s):  
Lewin Rathmann ◽  
Frank Vollertsen
Keyword(s):  
Experimental Evidence ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Maximum Distance ◽  
Contact Zones ◽  
Experimental Identification ◽  
Optical Projection ◽  
Strip Drawing ◽  
The Moment

In sheet metal forming contact between blank and die edge is reduced to local contact zones. For micro range, they can easily be found during a simulation, but an experimental evidence is difficult. Therefore, an optical projection of strip drawing with double deflection is presented and it is demonstrated that the contact zones can be identified using this method. These results are compared to those from simulation and it is shown that they reflect the simulative results. The results are presented on the basis of using a die with a die radius of r = 0.6 mm. The height of the gap between die edge and blank at the moment of their maximum distance is determined in the experiment to d = 18 ± 9 μm while it is d = 2 μm in the simulation.

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