Bending process is one of the most significant fields of application of sheet metal die.Sheet metals are exposed to some spring-back or spring-forward depending on elastic deformation following bending process.S235JR (1.0038) materials having a thickness of 4mm were bent with 90° punches having 5 different tip radiuses.The bending process was carried out by making the punch waited on the material for 30s (30s wait bending) and by removing the punch without waiting (direct bending).Specimens were prepared in three forms as non-heat-treated,normalized and tempered.At the same time,all experiments were performed at a deformation speed of 25mm/min.As a result,it was determined that as punch tip radius increased,the amount of spring-forward decreased.Although normalizing process applied to specimens increased the amount of spring-forward,tempering process decreased it.The amount of spring-forward was decreased in 30s wait bending process.
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