Design And Experimental Research Of The Flexible Die Used For Invar-sheet Thermforming

In recent years, invar die has been widely used in the manufacture of theaircraft composite skin，its ways of processing has been paid more and moreattention. But because of the single piece and little batch production and the poormachinability, invar should not be used for processing of punching die and milling.The thickness of invar steel to be machined maybe11millimeter or above, hotstamping and punching processing can reduce the forming force and improveforming quality, so the design of flexible die used for invar thermal forming hasvery important practical significance.First, experiments of invar compression were carried out on the hightemperature, then obtained stress-strain curve of invar and determined the formingtemperature, providing the basis for the numerical simulation method of sheetforming process. The arrangement scheme of basic units was researched and basedon this proposed my own design, providing the theoretical basis for structuraldesign of flexible mold.Then, the overall device system of flexible die were designed, including theselection of hydraulic machine, the design of flexible die, the height adjustingdevice, the electrical control system and software. Simulated the stamping processof plate through the software ABAQUS, obtained the forming force which canprovide the basis for the selection of hydraulic machine. Considering the influenceof temperature, flexible die and the height adjusting device was designed to beseparate type and the innovatively design of flexible die and the height adjustingdevice was proceed, verification and optimization of main parts were carried outthrough the ANSYS simulation to meet the requirements of the design. Based on therequirements of automatic adjustment, the control system was designed, throughclosed-loop control system for stepping motor, the height adjustment unit was madeto move on the timing belt/precision linear of X-scale and Y-scale precisely and thenadjusted the height of the basic units for surface modeling. The corresponding shapeadjusting software were designed which was based on the development platform ofLabVIEW, the software interface is friendly and maneuverability is very strong.Finally, performed the shape adjusting test of basic unit, then discussed the sources of its overall shape adjusting error；Rigidity test was also carried out and theresults showed that the rigidity met requirements of the design.