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Selective Laser Melting 방식으로 적층가공된 Ti-6Al-4V 합금의 내마모성 특성에 미치는 고온 UNSM 처리 영향에 대한 연구
산성충호(Choongho Sanseong),노준석(Jun-Suek Ro),편영식(Young-Sik Pyoun),아마노프 아웨즈한(Auezhan Amanov) 한국트라이볼로지학회 2020 한국윤활학회지(윤활학회지) Vol.36 No.1
In this study, the effects of ultrasonic nanocrystal surface modification (UNSM) treatment at room and high temperatures (RT and HT of 400oC) on friction and wear behavior of Ti-6Al-4V alloy prepared by selective laser melting (SLM) were investigated. The objective of this study is to improve the mechanical properties and frictional behavior of Ti-6Al-4V alloy by UNSM treatment. Dry friction and wear tests were conducted using a ball-on-disk method at RT with a bearing steel as the counter ball. Due to the high HT and UNSM treatment, the surface hardness tended to increase and surface roughness tended to reduce. X-ray diffraction (XRD) analysis showed that nanocrystallization structure and compressive residual stress were formed at the surface layer after UNSM treatment at both RT and HT. After UNSM treatment, it was observed that the wear rate was reduced by about 6% for the specimen treated at RT and a 28% reduction for the specimen treated at HT in comparison with the untreated one. Based on scanning electron microscope (SEM) images showed that the damage caused by fatigue wear occurred in the wear track of the heattreated specimen, and it is believed to be the cause of the highest wear rate. Mechanical properties and wear resistance of Ti-6Al-4V alloy were improved and prospect of industrial application was confirmed. Further research is still required to improve the characteristics of SLM Ti-6Al-4V alloy to the level of wrought Ti-6Al-4V alloy.
J.P.B.A Sembiring,Seimi Choi,Choongho Sanseong,Junsuek Ro,A. Amanov,Y.S. Pyun 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.5
The existing ultrasonic assisted grinding used for machining hard and brittle material still has some drawbacks, such as low material removal rate rapid tool wear and low quality of surface finish. To resolve those problem, a retrofit idea of existing concept is propose. In this paper, an idea to retrofit the existing ultrasonic assisted grinding machining center is proposed by changing the spindle design, tool tip and the modification of ultrasonic transducer. The consideration behind design changing and modification of existing concept will be discussed. Due to the design changing and modification, the capability of high speed rotational machining and the elliptical tool motion of 2D Vibration Assisted Machining (VAM) are expected to be obtained. Due to the elliptical tool motion, it is expected that the cutting force can be reduced, extension of tool life, capability to cut the brittle material in ductile regime and improvement surface finish can be obtained.
Experimental Study on Effect Ultrasonic in Incremental Forming Process
Darisuren Shirmendagva,Seimi Choi,J.P.B.A Sembiring,Choongho Sanseong,Junsuek Ro,A. Amanov,Y.S. Pyun 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.5
The spring-back effect during Incremental forming still becomes a concern because affects the dimensional accuracy of the finished part. To resolve it, ultrasonic vibration was introduced to incremental forming process. The addition ultrasonic during incremental forming was reported reducing the spring-back effect, decreasing the force for forming and increasing tool life due to reduced friction. In this experimental study, the comparison between conventional incremental forming. Ultrasonic Assisted incremental forming and Ultrasonic incremental forming was done. The results showed there is no significant difference between the conventional incremental forming process and ultrasonic incremental forming in terms or dimensional accuracy and surface finish. Therefore, the elimination of rotation spindle could be done which possibly reduce cost of device and operation.