Experimental Investigation of Friction Effects Enhanced by Tool Geometry and Forming Method on Plane Strain Sheet Metal Forming

Abstract

An experimental study on friction was conducted on aluminum and steel sheets for automotive applications. Cold-rolled mild and high strength steel, electrogalvanized steel and aluminum grades Al6111T4 and Al 2008T4 were tested under various levels of bending under tension, plain strain forming mode. The friction and forming severity of the tests were promoted through the use of a set of tools of decreasing radii sizes. The test methods includes flat platens, draw bead simulation, 90-degree bending under tension and tools with rectangular geometry. A systematic pattern of frictional behavior, common to all tests was observed. An initial spike, associated to static friction, was followed by a more stable plateau. The effects of the static friction on the forward flow were studied in function of parameters such as the testing method, the tool radii, the testing speed, etc. The results showed that the static friction may be increased by the forming method, and its effects on the forward flow varied significantly depending on the material and lubrication. Based on the results of this study, general forming practices for these materials were recommended.

Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 26–28, 1998

KEY WORDS:

• Friction Testing
• Stick-Slip
• Bench Tests

Notes

Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 26–28, 1998