| Research Abstract |
The magnitude of leadframe is actually the order of 10ィイD2-6ィエD2m. However, it is impossible to perform the experiment of the order of 10ィイD2-6ィエD2m.Hence, the experiment of the order of 10ィイD2-3ィエD2m Has been performed. The difference between the conventional blanking and the blanking of leadframe lies in the ratio of the width of the blank t the thickness of the blank. In the conventional blanking, since the width of the blank is much larger than the thickness of the blank, the shape of the blank resembles a strip. On the other hand, in the blanking of leadframe, since the width of the blank is as large as the thickness of the blank, the shape of the blank resembles a bar. The punch and the die are designed in the consideration of the difference. First, the width of the punch is set to be 10mm and the distance between two holes of the die is set to be 6.0mm, 6.4mm, 6.8mm, 7.2mm, 8.0mm, 8.4mm, 8.8mm, 9.2mm, and 9.6mm. The thickness of the blank is set to be 6mm, 8mm, 10mm and 12mm. He
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nce, the ratio of the width of the blank to the thickness of the blank changes from 0..5 to 2. Next, the experiment of blanking is performed using copper, aluminum(H) and aluminum(O). According to the experiment, the deformation of the material is characterized in the use of the die of 6.8mm and the die of 8.8mm. Hence, the deformation of the material in the use of the two dies is clarified by the strain analysis of the grid method. First, in the blanking using the die of 8.8mm, the deformation of the material is confined in the zone of the deformation of the material is no confined in zone of the punch-die clearance. On the other hand, in the blanking using the die of 6.8mm, the deformation of the material is not confined in the zone of the punch-die clearance. Next, the analysis of the blanking of the leadframe is performed under the assumption of various ductile fracture criterion using the computer program which has been developed by the authors for the analysis of blanking. As a result, the deformation of the material from the stage of the appearance of a crack to the stage of the meeting of two cracks using the conventional ductile fracture criterion is much larger than the deformation of the material obtained by the experiment, while the deformation of the material using our proposed ductile fracture criterion is as large as the deformation of the material obtained by the experiment. Hence, the validity of our proposed ductile fracture criterion has been confirmed. Less
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