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이재령(Jaeryung Lee),김성진(Seong Jin Kim),박현달(Hyundal Park) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
This paper describes the weight reduction technology of brushless DC (BLDC) motor with both advanced magnetic powder core instead of Si sheet steel core and copper cladding aluminum (CCA) instead of copper winding. In order to apply the high-density magnetic core for BLDC motor, the warm compaction process with die wall lubrication was used in this work. In general, the density of magnetic core is strongly associated with the core loss. The motor efficiency was improved as the magnetic core density was increased. Results showed that the oil pump motor using the advanced magnetic powder core was decreased about 10% in size and reduced about 10% in weight comparing to the convention motor with Si sheet steel core. Consequently, the motor and oil pump system containing the advanced powder core was satisfied the requirements during the performance and durability test.
김기정(Kijung Kim),김기범(Kibum Kim),김성진(Seong Jin Kim),박현달(Hyundal Park) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
The novel PM (powder metallurgy) steel for automotive power-train gear components were developed to reduce manufacturing cost, while meeting the requirements. The high-density PM steel was manufactured by mixing using special Cr-Mo atomized iron powders, high-pressure compaction, and sintering. Tensile strength, charpy impact, bending fatigue, and contact fatigue tests for the PM steel were carried out comparing to the conventional forged steel. The pinion gears for 6-speed auto-transmission were also manufactured by helical pressing, sintering, and external rolling process (selective surface densification). In order to evaluate the durability of the PM parts, the auto-transmission durability tests were performed using dynamometer tests. Results showed that the PM steel fulfilled the requirements for pinion gears indicating suitable bending and contact fatigue strengths. The PM gears also showed improved gear tooth profile and better performance during the transmission durability tests. In particular, the PM gears manufactured by helical pressing and selective surface densification showed a significant advantage in reducing the manufacturing cost of about 30% as compared to the conventional forged steel gear manufactured by tooth machining (hobbing, shaving, and grinding) process.
Studies on the Coating Materials for Forming Dies of Advanced High Strength Steel Sheets
Sungchul Cha(차성철),Hoyoung Kong(공호영),Iksoo Kim(김익수),Kunuk Park(박건욱),Hyundal Park(박현달) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
To increase the safety and lighten the weight of car body and chassis, the application of advanced high strength steel (AHSS) is being rapidly expanded. Current forming dies with thermal diffusion (TD) of vanadium carbide or coatings (AlTiCrN+MoS2, TiAlN) don’t have enough wear resistance and durability. The coatings shall have complex material properties, e.g. wear, temperature, fatigue resistance and low friction property. The main concept of coating and layer development is to add the low friction property through carbon addition to temperature resistant elements. The toughness, fatigue resistance and bonding are realized through nitrided layer, CrN or TiN and multilayer structure. Total 18 coatings are compared and discussed in this work. As conclusion, TiAlCN and AlTiCrN+CN show the competitive solutions.