Powder die-filling is an important process in the process of powder pressing. The effect of mold filling directly affects the subsequent pressing process and ultimately affects the quality of products. During the filling process, the air in the die has an obvious effect on the filling behavior, which seriously reduces the filling efficiency of the powder. Aiming at the influence of air in the process of powder filling, a set of inspiratory linear die-filling system was designed. The system is mainly composed of control module and mechanical module, in which the mechanical module includes two parts: filling device and inhalation device. The iron powder filling trial was carried out by using this system. The movement speed of the shoe was set as 250mm/s. It was found that the filling efficiency of the aspirated filling was improved by nearly 30% compared with that of the gravity filling. The results show that the aspirated die-filling can effectively reduce the influence of air on the powder filling behavior, and improve the filling efficiency of the powder die-filling.

The restitution coefficient is used to characterize the energy loss in particle impact, which is an important parameter for discrete element simulation and mechanical system motion analysis. However, the restitution coefficient of many materials needs to be determined, and the key material properties affecting the restitution coefficient are still unclear. In this paper, the acoustic frequency sampling method was used to study the restitution coefficients of 10 representative particles. The effects of material density and specific strength on the restitution coefficient and the relationship between the restitution coefficient and the damping coefficient were investigated. The results show that the particle restitution coefficient is inversely proportional to the density except for aluminium. The relationship between particle restitution coefficient and specific strength is not significant.