注重流动性、充填性的粉末冶金用预混合铁粉的开发

Development of iron based pre-mixed powder improved flowability and filling-ability in PM manufacturing

压制生产率是粉末冶金生产过程中的一个重要课题。控制压制生产率的生产作业有:(1)粉末从料仓中的排出;(2)将粉末充填于模具型腔中。为了评定粉末的排出特性,设计了简易的粉末排出装置,用来测定铁基预混合粉的临界流出径。已证明临界流出径和料仓中粉末的流动型式密切相关。在将粉末充填于模具型腔内的作业中,发现将空气从模具型腔内排出是一个重要现象。与常规装粉靴相比,可将空气加速从模具型腔中排出的“搅拌式装粉靴”,能够提高装粉速率和减小粉末压坯重量的波动。

One of the most important subjects in the PM manufacturing is productivity of compacts. There are two processes that are controlling productivity in PM manufacturing. （1）Discharging of powders from the hopper. （2） Filling of powder into the die cavity. To evaluate the discharging characteristics of powders, the simplified discharging equipment was designed to measure the critical discharging diameter of iron based pre-mixed powder. The critical discharging diameter showed good relation to flow patterns of powders in the hopper. In the die filling process,the air release from the die cavity was found to be important phenomena. ＂Agitatingshoe＂ which can accelerate the air release from the die cavity was able to increase the filling rate and decrease the weight variation of compacts compared to a conventional feed shoe.