Search

Because of product miniaturization, demand for cups created by deep drawing has increased. However, because thin sheet materials exhibit poor deep drawing formability, using deep drawing on micro/meso cups is rather difficult. In this study, punch surfaces with microridges were used to enhance deep drawing formability. The concept was based on the observation that punch surfaces with microridges near the punch nose could disperse the drawing force of punches on sheet materials and delay the cracking of sheet materials. In this study, cylindrical cups composed of copper alloy were used. First, punch surfaces with microridges were designed and the Deform 2D software was used for analyzing the formability of deep drawing by using punch surfaces with and without microridges. Second, drawing dies were designed and produced, and an experiment was conducted to verify the results of the analysis. The study results indicated that commercial forming analysis software can be used to simulate the effect of microridges on deep drawability accurately. A comparison between the two punch surface types revealed that punch surfaces with microridges exhibited a slightly increased drawing force (3%) compared with those without microridges. Concurrently, the effect of punch surfaces with microridges increased forming height by at least 100%.

The design of progressive dies is a very knowledge-intensive, complex, and time-consuming process. This paper describes a computer-aided structural design system for progressive dies with drawing, bending, and punching operations. Taking advantage of a pre-built design knowledge and database, this system is able to output designs of the main and standard parts of a progressive die upon users inputting a minimum set of design information. Our system is implemented on top of CATIA V5 software and uses its built-in modules, including Part Design, Assembly Design, and Knowledge Advisor. Our system also consists of an inference engine and a user interface. The experimental results show that our system successfully reduced the design time from about seven working days to within 2 h for the structural design of the main and standard parts of a progressive die of an upper shell for a mobile phone, which can dramatically save on design time and cost and also provide excellent design quality.

Most rotators and stators of motors or generators as well as the cores of transformers are produced by laminated plates of electric steel to reduce the energy loss caused by eddy current. Therefore, it is essential to predict as well as improve the shearing quality of the electric steel plates and thus help increase the efficiency of the machines. Most investigations overlook the planar anisotropy in the numerical analysis of the shearing process. The simplified 2-D analysis was adopted instead of the 3-D analysis. In this work, DEFORM 3D analysis is used which takes into account the anisotropy of the plate material. Normalized Cockcroft & Latham damage criterion is used in determining the occurrence of fracture during the shearing. The result shows that the 3-D analysis predicts well in the burnish depth while roughly in rollover due to insufficient resolution of the element size. The 2-D analysis tends to underestimate the burnish depth attributed to the improper selection of lower critical damage values and predicts scattered rollover.