Research Of Powder Compact Forming

Powder metallurgy is a kind of metallurgy method for metal materialsand workpieces which possess suitable shape and performance throughforming and sintering. It has become an important producing method formaterials and workpieces, and is found increasing application in modern hightechnology areas.Powder forming is one of the key operations in PM part manufacture.Loose raw powder is densified to a green compact which possesses denifitegeometry shape, size, density, and intensity in powder forming.Formingmethods contain special forming and compact forming, which is an necessaryprocess in most PM manufacture. Special forming methods, such as isostaticpress, powder forging, injecting forming are also applicated increasingly.What's more, the appearance of some new forming techniques, such as warmcompaction, warm flow compaction, dynamic magnetic compaction, highvelocity compaction, makes PM the most remarkable advanced materials andmachine parts manufacturing technology, also makes it be regarded seriouslyand researched widely in most countries.In compaction, green compact is acted on by compact pressure, sidepressure, strip pressure, elasticity effect and so on. These powders decide finalgreen density or have direct or indirect relation with green density. Powderparticles take place elastic deform, plastic deform and brittle fracture.PM materials is complex of matrix and pore. Generally speaking,physical property and mechnical performance of materials depend on densityin PM parts manufactureing.As a result, green density design is the main gist of the design and manufacture of PM machine structural parts?densityimprovement of powder product is also a research hotspot in PM all the time.Density distribution of green compact is not uniform in altitude directionand cross section. In green compact upside connecting with die, densityincreases from center to edge, density and hardness are maximal at the edge oftop. Density distribution in green compact underlayer is reverse with upside.Density distribution of green compact is affected by several factors,both diewallfinish improvement and duplex compact can improve uniformity ofdensity distribution.Warm compact can produce iron PM accessories at low cost,and manyexperiments have proved highdensefunction of warm compact. Particlerearrangement is the leading densifying mechanism, and plastic deform whichsupply harmony for rearrangement is another important mechanism.According to statistical analysis, several famous compact equations aresuitable only in certion range.Balshin equation is only suitable in mediumpressurearea for hard particle? Kawakita and Heckle equation have biggisherror in lowpressurearea. Ge Rongde analyzed compact equations of all kindsof powder and brought forward a allpurposecompact equation. This allpurposecompact equatin has not only higher precision but also widerapplicability.Compared with casting and forging connecting rod, powder forgingconnecting rod has higher reliability and better general technologicaleconomic benefit, and is replacing forging steel connecting rod in largequantity. Singlesinteredsteel connecting rod has huge economic benefit,and itwill replace not only plenty of casting connecting rod but also some powderforging steel connecting rod.Exploiture and optimization of manufacturingtechnique of temperature presssinteringconnecting rod will have a strongimpact on casting, die forging, PM forging connecting rod.At present, producing engine connecting rod with ordinary aluminium is a research area.It is proved that extrusionforgingand powder forgingtechnology are both feasible to produce aluminium alloy connecting rod, butthey are still in stage of research at present. PM technology can possiblyaccelerate industrial manufacture and applicaton of aluminium alloyconnecting rod in 21th centry.My thesis entirely summaries the application, present development andfuture of PM, describes the basic course of compact, all kinds of powders andinfluencing factors in compact. The emphasis of my thesis is the research ofgreen density, which analyzes densifying mechanism and density distribution,compares densifying between cool and warm compact, constracts andcompares several produce technology of connecting rod, also indicates PMconnecting rod will have huge impact on traditional connecting rod. It offersabandunt basic preparations for following research work and experiments, andit also can be regarded as a background and reference for the following study.