The Effect Of Die's Gap On Hot Forming And Its Optimization Method

With the vigorous development of the automotive industry, the demand for automobile lightweight and crashworthiness become higher and higher. The technology of hot stamping has been widely used in the production of automobile parts, and are paid more attengtion by many scholars.Through the combination of experiments and simulation, the influence of die's close clearance to distribution of temperature and forming quality of the hot stamping part had been analyzed. The main work are as follows.1 A method to monitor die's close gap was proposed. It not only provides reliable measurement basis for the study of mold clearance's effect in hot stamping, but also can be used in adjusting the die and monitoring the quality of parts. In the first place, the eddy current displacement sensor was calibrationed, and obtainde the effective of the sensor measurement range. Then, a set of mold clearance measurement experiment was designed, through monitoring the stamping gaps of symmetric plate and asymmetric ones, the reliability of this method are discussed.2 By adjusting the die's gap, the experiments and simulations of hot forming was done in different clearance, then the influence of the mould clearance on hot forming sheet temperature and the relevant mechanical properties of the specimens was studied. Completed the hot forming experiments and simulation works under the four mold clearance 0.9 t, 1.0 t, 1.1 t and 1.2 t(t is the thickness of the sheet), got the corresponding temperature distribution curve, and compared the forming mechanics performance in four conditions.3 Reasons cause uneven clearance was studied, from the perspective of mold design, a kind of method for determining the drawing die pressure center based on finite element analysis was put forward. The principle of the new method to determine the pressure was expound. Through a certain type of B pillar, the new method has carried on, and obtained the difference between the center of pressure and geometric center. In the vertical direction, the influence of deflection torque to stamping force was also discussed.The study of the inflence of die's gap on hot stamping has certain reference significance for the future research. And two new methods proposed in this paper has a certain guiding significance for hot forming or even the whole stamping industry.