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레이저 직접금속성형기술을 이용한 금형재 표면보수 특성 연구
손영명(Young-Myung Son),장정환(Jeong-Hwan Jang),주병돈(Byeong-Don Joo),임홍섭(Hong-Sup Yim),문영훈(Young-Hoon Moon) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7
Direct laser metal forming technology was applied to restore the damaged mold surface. In order to estimate melting characteristics of the 20 ㎛ Fe-Cr-Ni powder, single layer experiments were performed at various levels of heat input. The process window of the 20 ㎛ Fe-Cr-Ni powder provided feasible process parameters for the smooth regular surface. The cross hatching scanning strategy on the multiple layer experiment was performed to reduce the thickness non-uniformity of edge portions compared with the one direction scanning. To estimate the coherence between the melted powder and the basematal, the tendency of hardness distribution has been observed. The hardness of the melted and the remelted zone was distributed from 400HV to 600HV. It is over 2 times compared of the hardness of the basemetal. Experimental results show that the mold restoring process using direct laser metal forming can be successfully applied in the mold repair industry.
주병돈(Byeong-Don Joo),이성문(Sung-Mun Lee),손영명(Young-Myung Son),문영훈(Young-Hoon Moon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Hydroforming technology draws attentions of automotive industries due to its advantages such as weight reduction, increased strength, improved quality and reduced tooling cost. Hydroformed automotive parts used as structural components in vehicle body frame often have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. In this study, hydroforming process for the flanged tubular parts was proposed. Tube hydroforming experiments were conducted at various conditions. Forming characteristics at various pressure conditions were evaluated. With optimized condition flange was sucessfully formed. The results show that flanged automotive parts can be successfully produced with tube hydroforming.
Fiber laser를 이용한 공구강 AISi H13의 표면경화 연구
이재호(Jae Ho Lee),장정환(Jeong Hwan Jang),주병돈(Byeong Don Joo),손영명(Young Myung Son),문영훈(Young Hoon Moon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Laser surface heat treatments comprise a wide variety of techniques by which hard and wear-resistant layers can be obtained on surface without affecting the bulk material. It is known that the performance of these kinds of treatments is highly influenced by the different parameters involved in the process, such as the thermophysical properties of the material or the laser beam settings: pulse width, power and scan rate to the workpieces. In this research, an attempt has been made to improve the surface hardness and wear properties of AISI H13 tool steel through solid solution hardening and refinement of microstructures using a 200W fiber laser as a heat generating source. The hardness of laser melted zone was investigated. As a result, the hardness of as-received AISI H13 tool steel was approximately 240Hv, the hardness of after laser surface heat treatment was around 480~510Hv. In order to identify the effect of heat input on the laser melting zone, many scanning conditions were controlled. The hardening depth and width were increased with the increase in the heat input applied. After investigation, application of experimental results will be considered for mold industry.