| Electroplastic effect refers to the phenomenon that the flow stress decreases significantly with the application of high density current pulses on the plastic deformation of materials. Since the electroplastic effect was found in the 1950s and 1960s, a lot of researches were carried out to study the mechanism and application of electroplastic effect, but the application scope is still limited at present. This paper presents a new application of electroplastic effect: electroplastic roll hemming process. And the preliminary study and discussion on this process is carried out in this paper, as summarized below:1. According to the problems existing in roll hemming process, the help of electroplastic effect in solving these problems is discussed. And the feasibility of this process is also analysed.2.Based on the analysis of the problems about application of electric pulse, insulation, et al., which are indispensable in realizing electroplastic roll hemming process, a set of electroplastic roll hemming equipment is designed.3. Based on the principle of work balance, an analytical model of roll hemming process with straight edge is established, and computational formula for roll hemming force at each step is derived. The predicted roll hemming force agree with the result of production experience,and have the upper bound property.4.An electric pulse assisted stress relaxation test is carried out, to study the stress relaxation behaviour of metal under the affect of electric pulse. And the influence of thermal expansion is estimated and compensated. At last, the influence of electric pulse on the stress relaxation behavior of QP980 is discussed. |
