Density Distribution Rules Of Powder Metallurgical Step Parts Bearing The Single-action Pressing

Some complex machine elements with special properties or of difficult-to-produce through other technics can be produced by means of modern powdermetallurgy technique. PM technique is regarded as a high-tech undertaking of thenational development priorities. When the powder metallurgical parts bear thesingle-action pressing, the powder density influenced by friction, flow, shape, etccould be in uneven distribution. This situation presents more obvious on the stepparts. According to the designed sample model, this thesis adopts experimentalmethodology, studies the density distribution rule of different step shape underdifferent rate and pressure， initially establishes the mathematical relations ofparameters, aims at providing a certain reference for designing the parts’ structureand mapping out technological process.At the beginning of this thesis, the density distribution of the step partsinfluenced by different pressing pressure and rate is investigated. The experimentalresults indicate that friction condition and fluidity are the main factors leading to theuneven distribution of the density. The influence of pressing pressure and rate to thestep density is mainly linear change. When the parts become less dense, the densityof step parts increases with the improvement of pressing pressure and rate.Under the circumstance of unchanged basic configuration and certain pressingparameters, the size of step parts determines its density. With the increasing of theheight and diameter ratio, the density contrast decreases. The reason for the changeof density contrast is analyzed based on the powder’s compression ratio and flowfactor.For the sake of providing reference significance for the step parts sampledesign, the thesis also establishes the changing diagram, analyzes the data andconcludes the approximate formula between the ratio of height to diameter and thedensity.