Avaliação das condições tribológicas em estampagem de chapas através do ensaio de dobramento sob tensão

Abstract

The lubrication in sheet metal forming plays an important role in the production process, helping to reduce the wrinkling, premature fracture and very localized thinning of the sheet thickness. To this end, the lubricant should be able to reduce friction at low levels but not so low that promote other kinds of defects such as wrinkling of the sheet. A good lubrication also reduces premature wear of the stamping tools used to produce parts, as it is essential for success in the process of developing new parts. In this work, four lubrication condi-tions were evaluated (3 liquid lubricants and the absence of lubricants) by the bending under tension test (BUT) and deep drawing test. The performance of the lubricants were evaluated by measuring the maximum force of deep drawing test, the forces on each side of the sheet, torque and vertical force on the pin of the BUT test. The material used was the commercially pure aluminum AISI AA1100 alloy. The results indicate that the best lubricant always show the best performance no matter what type of test, but the measurement of torque facilitates the identification of it. It was also observed that the measurement of vertical force generated at the pin is smaller the more inefficient is the lubricant.