To enable efficient and continuous production of high-quality semi-flexible metal bellows, a combined methodology integrating finite element simulation and experimental validation was utilized for mold optimization. A multi-objective evaluation system was developed based on three-dimensional finite element analysis of medium-diameter thin-walled bellows spinning. This system incorporated waveform quality, deformation inheritance characteristics, and bellows deflection angle to evaluate key mold parameters, such as pitch, diameter, tooth thickness, and pitch reduction during multi-pass forming. The findings reveal that mold pitch significantly influences the length of the peak and trough regions in semi-flexible bellows. As the pitch increases, the ratio of straight to non-straight segments demonstrates a linear growth trend. Mold diameter primarily affects the actual pressing depth of the troughs, with excessively large diameters causing a rapid rise in equivalent strain and deflection angle. Mold tooth thickness predominantly impacts the entering angle and trough width of the bellows. Reducing tooth thickness enhances the entering angle, thereby facilitating subsequent forming stages. The excessive reduction of die pitch can lead to the inaccessibility of subsequent forming, which should be controlled at about 10%. The optimal mold parameters were identified, including an inner diameter of 80 mm and a tooth thickness of 2 mm. Multi-pass forming experiments were conducted using these optimized parameters, successfully producing semi-flexible metal bellows. The maximum error between simulated and experimental waveform results was within 2%, and the deflection angle error remained below 10%, confirming the high computational accuracy of the simulation model. This study establishes a theoretical framework for the design of spinning forming molds for semi-flexible metal bellows.
Liu et al. (Mon,) studied this question.