Wenzhi Fu

Research on the elastic cushion conditions in multi-point thermoforming for polymer sheet

Multi-point thermoforming is a new flexible technique for manufacturing three-dimensional polymer sheet parts. The fixed die utilized in conventional thermoforming process is replaced by a multi-point die, which can be reconfigured rapidly and nearly cost-free. In the present study, the effects of the elastic conditions on the surface quality and shape accuracy of the formed workpiece have been investigated through experiments and numerical simulations. The results show that an elastic cushion with proper thickness and hardness can significantly improve the surface quality of the workpiece. It has also been found that the application of lubrication can improve the shape accuracy of the formed workpiece.

Numerical simulation of multi-point forming accuracy for polycarbonate sheet

Multi-point forming is an advanced flexible manufacture technology, which has been used in many fields successfully. In order to provide a flexible method for forming a polymer, multi-point forming is applied to the manufacture of polycarbonate sheet. An optimized DSGZ constitutive model is established to describe the stress–strain relation of polycarbonate sheet, and its parameters are determined according to experimental data. The multi-point forming process of polycarbonate sheet is introduced briefly, and a simple calculating scheme of punch height is developed. Numerical simulations of spherical and saddle-shaped parts are carried out by dynamic explicit finite element analysis, and the effects of punch number and punch radius on the surface accuracy and shape accuracy are studied. The multi-point forming experiments of polycarbonate sheet are done, and the comparisons of shape error between experimental parts and objective parts are conducted, which show that the polycarbonate products have good surface accuracy and shape accuracy.

Numerical investigation of flexible clamp stretch forming

Multi-clamp stretch forming technology has been used in sheet metal for years, however, the arrangement of clamps change with the shape of stretching die is rather new. The goal of this research is to optimize the processing parameters of flexible clamp stretch forming machine. First, the forming characters of flexible clamp stretch forming is introduced, the feasibility of this technology is proved, the experimental prototype is developed, and the existing problem is discovered by a lot of experiments. Then, the optimized scheme is proposed, and numerical simulations of optimized parameters for flexible clamp stretch forming machine have been performed. Finally, the contrast of forming force, stretching strain and thickness of spherical parts formed by FCBSF and FCBDSF are carried out by numerical simulation. The excellence of the optimized flexible clamp stretch forming machine is verified by forming experiments.