A remeshing technique for large strain analysis of fine-blanking

Abstract

Fine-blanking is a well-known metal forming process, growing in popularity due to high quality, reproducible formation of near net shape parts. Strain analysis is an important quantitative measure for investigating metal deformation. A deeper understanding of the strain analysis of fine-blanking could bring forth further applications and breakthroughs in this technology. However, only limited literatures are available on strain analysis of fine-blanking, despite the fact that this technology had been used for years. This is mostly due to the severe and localized deformation of fine-blanking obstructing the measurement of strain. To solve this problem, a new experimental remeshing technique was developed for the large strain analysis of fine-blanking in this research project. In this project, large strain analysis of fine-blanking was investigated through the use of a new remeshing technique on major deformation area. Grid patterns were etched on the meridian planes of specimens of low carbon steel sheets by photochemical method. These prepared specimens were then fine-blanked, with a step increment of 20% till the total punch penetration reached 80% of the material thickness. Results of the experimental remeshing showed the highest effective strain values at the punch tip and die corner, where the deformation was highly localized. The effective strain values at the punch tip were found to be 1.19, 2.90, 6.77and 11.78 for a total punch penetration of 20%, 40%, 60% and 80% of the material thickness respectively, indicating that an increase in total punch penetration was associated with an increase of effective strain value. The severity of deformation augmented with the percentage of the increase of total punch penetration. This study clearly shows that, by employing this newly developed remeshing technique, the measurement of large strain is no longer hindered by the severe deformation usually occurring in fine-blanking. This study also demonstrates that a more intensive strain analysis of fine-blanking is able to be achieved with the aid of this novel technique.