• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.1
• /
• pp.40-46
• /
• 2007

High speed machining has become the main issue of metal cutting. Due to increase of the rotational speed of the spindle, problems such as the run-out errors and reduced stiffness must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an analysis of static stiffness in the main spindle interface. Finite element analysis is performed by using a commercial code ANSYS according to variation of cutting force, clamping force and rotational speed. From the finite element results, it is shown that the rotational speed and clamping force mostly influence on the variation of the static stiffness in the main spindle interface.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1749-1752
• /
• 2005

High speed machining has become the main issue of metal cutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evaluation of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.3 s.180
• /
• pp.147-155
• /
• 2006

High speed machining has become the main issue of metal rutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evolution of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.05a
• /
• pp.405-406
• /
• 2012

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.3
• /
• pp.278-283
• /
• 2013

While Built-in Spindle is working in machining center, the tool is changed by ATC(Automatic Tool Changer) automatically. However, impurities could be stacked in front of spindle because of chips formation while machining, and positional error between spindle and tool could be generated. Compressed air holes are necessary for removal of the impurities. But, the diameter and number of compressed air hole are different for each built-in spindle in market. In this paper, flow analysis is carried out to find out the efficient figuration of the compressed air hole by using velocity and pressure distributions.

• Journal of Fisheries and Marine Sciences Education
• /
• v.25 no.4
• /
• pp.775-780
• /
• 2013

한국산 해조 3종, Umbraulva olivascens (P.J.L. Dangeard) G. Furnari, Bryopsis minor Womersley, Sargassum polycystum C. Agardh에 대한 형태학적 및 분류학적 주해가 제시된다. Umbraulva olivascens는 뚜렷한 올리브 체색, 파상형 연변, 엽체의 구멍 및 조하대 서식처에 의해 특징지어진다. Bryopsis minor는 작은 조체, 모든 방향에서 많은 분지, 기부에 잘록함이 없는 선형의 소지, 두드러진 가지 흔적을 결여하는 축, 뚜렷한 중심 피레노이드를 갖는 엽록체, 주축과 비슷한 길이의 가지 및 뚜렷하지 않은 주축을 갖는 것이 특징적이다. Sargassum polycystum은 조체 모든 부분에서 나는 원통형 내지난형의 돌기, 가시가 있는 뚜렷한 중륵을 갖는 전연 내지 다소 거치연의 잎과 드물게 나는 기낭을 갖는 것으로 특징지어진다. 이 3종은 여기서 한국 해조상에 처음 기록된다.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.5
• /
• pp.1176-1181
• /
• 1995

Microdrilling is one of the most difficult operations because of the poor chip discharge and the weakness of tool. This study is concerned about the development of a microdrilling monitoring system that is useful for minimizing the tool breakage and enhancing the machinability in the air spindle based microdrilling. The system is composed of a drilling state detection unit and an adaptive step-feed control unit that controls the micro-stepping motor driven spindle axis. Drilling states such as overload, tood breakage are recognized by the change of the air spindle speed which is measured via the reflective photo sensor. Based on the monitoring results, the adaptive step-feed control algorithm adjusts the step increment to keep the decrease of spindle speed within a specified range. The results of evaluation tests have shown that the developed system is very effective to prevent the breakage of microdrill and improves the productivity in comparison with the conventional microdrilling.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.1
• /
• pp.73-79
• /
• 2013

In this study, NIMAX material has been processed using the three-dimensional measuring instrument and white light interferometer. they were tested to roundness and surface roughness and results are as follows: As for a cutting characteristic, it indicated that F4 showed a lower result than 2F showed due to the high hardness of the material and showed a good result when spindle rotation speed and tool feed were low. As for the measurement of roundness through 3-Dimensional measuring machine, it indicated that 4F showed a good result like the condition of cutting component and that roundness showed a good result when spindle rotation speed of 1,700 rpm and tool feed speed of 85 mm/min were applied. As for the surface roughness of processing surface, Surface roughness showed better 4F than 2F and conditions of spindle rotation speed 1,700 rpm, tool feed rate 55 mm/min showed good results in the Ra $0.4025{\mu}m$.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1999.07a
• /
• pp.3-9
• /
• 1999

4절 기구를 이용한 크랭크식 식부 장치는 원하는 제적을 비교적 쉽게 합성할 수 있지만, 그 구조상 발생하는 가진력에 의해 주축의 최대 회전 속도가 약 300 rpm 전후로 작업 속도는 약 0.8 m/sec로 한정되어 있다. 이러한 단점을 보완하고 기계 이용 수익을 높이기 위해 편심 기어열을 이용한 고속, 저진동의 로터리식 식부 장치에 대한 연구가 1984년 일본에서 시작되었다. 로터리식 고속 식부 장치는 현재 대부분의 승용 이앙기에 채택되어 있으며 최고 1.2m/sec의 속도로 작업할 수 있다(산경정남, 1986; 산경정남 등, 1989). 그러나, 전량 수입 및 기술 이전에 의존하는 로터리식 식부 장치는 다음과 같은 문제점을 가지고 있다. 1) 로터리식 식부 장치의 식부 궤적은 원에 가까운 난형을 가지므로 식부후 토양에 생기는 구멍이 크랭크식 식부 장치에 의한 것보다 커서 식부 자세가 불량하고 뜬묘가 많이 발생한다. 2) 로터리식 식부 장치의 식부 제적은 상하 방향의 길이가 크랭크식보다 짧아 앞서 이앙한 모의 줄기 부분이 겹치는 브릿지(bridge) 현상이 자주 발생하며 벼 생육에 불리하다. 3) 로터리식 식부 장치의 조당 수입 판매 가격은 약 30만원으로 6조식 승용 이앙기에 부착할 경우 국내 승용 이앙기 평균 판매 가격인 960만원의 약 19%인 180만원을 차지하여 국산 이앙기의 경쟁력을 감소시킨다. (중략)