• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.213-219
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• 2002

A cone-shaped active magnetic healing spindle system for high speed internal grinding with built-in motor that has 7.5kW power and maximum rotational speed of 50,000 rpm is designed and built. Using cone-shaped AMB(Active Magnetic Bearing) system, the axial rotor dick and magnets of conventional 5-axis actuating design can be eliminated. so this concept of design provides a simple magnetic bearing system. In this paper, the cone-shaped electromagnets are designed by magnetic circuit theory, and a de-coupled direct feedback PID controller is applied to control the coupled magnetic bearings. The designed crone-shaped AMB spindle system is built and constructed with a digital control system, which has TMS320C6702 DSP, 16 bit AD/DA, switching power amplifier and gap sensors. As the AMB system provides high damping ratio eliminating overshoot and resonance speed, this spindle runs up to 40,000 rpm stably with about 5${\mu}{\textrm}{m}$ of runout.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.999-1002
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• 1997

In this study, in order to set ELID conditions in the internal grinding wheel, the characteristics with the variations of grit size, output voltage and peak current were examined by using conventional machining center(M/C) equipped with electrolytic in-process dressing(EL1D). The initial working voltage was lowered and the working current was high with increasing grit size. The insulating layer thickness increased, as the final voltage increased with the output voltage and peak current. The initial wear rate of the wheel machined with ELID were measured indirectly by using surface roughness tracer. The initial wear rate of the wheel with ELID increased along with high grit size. In case that the grit size with ELID was low, the output voltage and peak current had to be increased to increase the insulating layer thickness. In case of the high grit size, the output voltage and the peak current were established low, which made the insulating layer thickness decreased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.79-83
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• 2001

A cone-shaped active magnetic bearing spindle system for high speed internal grinding is designed and tested. The cone-shaped AMB system consists of only 4 couples of magnet, it can be smaller and lighter than conventional radial-axial-type AMB system. In this paper, the cone-shaped electromagnets are designed by magnetic circuit theory, and de-coupled direct feedback PID controller is applied to control the coupled magnetic bearings. The designed cone-shaped AMB spindle system is built and constructed with a digital control system, and tested its stbility and dynamic performances. As the results of the tests, this spindle runs up to 40,000 rpm with about 5 ${\mu}{\textrm}{m}$ of runout, and the AMB system provides high damping ratio eliminating overshoot and resonance speed.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.395-398
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• 1997

In the modem manufacturing system, to achieve the unmanned automation, the stability of accuracy is required through a long working period. The thermal deformation of precision machine is predominant in this long time stability. While grinding slender and long workpiece at cylindrical grinding machine, we support workpiece using steadies to prevent the vibration of workpiece. The thermal deformation of the machine by grinding and internal heat source cause processing errors, so the steadies for compensating the thermal deformation in real time are strongly needed. In order to compensate these thermal deformation and grinding processing errors, the device to determine the precise positioning having the stroke of 10.mu.m is necessary. This paper suggests design and make the device to determine the precise positioning using thermoelectric device, to investigate the control characteristics and presents the heat actuator will be very useful in machine tool.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.6
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• pp.109-118
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• 1991

In this study, it is intended to investigate the effect of the grinding conditions such as table feed, down feed, cross feed of residual stress distribution. And this distribution is investigated upon the grinding direction and the its orthogonal direction at ground layers. The material is used carbon steel (SM20C) which usually used to motor axis. And in order to be considered as Bernoulli-Euler beam, the dimension of the specimen is appropriately designed. According as corroiding the ground surface, the residual stress layers are removed and strain which occured on account of unbalance of internal stress is detected by rosette-gate. Through A/D converter and computer, these values are saved and evaluated residual stress by stress-strain relation formula. Finally, these results are diagrammatized with Auto Cad. The results obtained are as follows. As the depth from the ground surface increases in grinding direction and its orthogonal direction, tensile residual stress exists in the surface, and subsequently it becomes compressive residual stress as it goes downward. As the table feed, the cross feed and the down feed increase, maximum residual stress is transformed form the tensile to the compressive.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.155-162
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• 2000

전해 인프로세스 드레싱(ELID)의 응용기술로써 간헐적 드레싱(ELID II) 및 무전극 드레싱(ELID III)이 원통내면 마무리 연삭에 이용되고 있다. 주철본드(CIB-D) 및 메탈레진본드 다이아몬드 숫돌(HRB-D)이 이 방식들에 사용되고 있다. 경면 가공에 있어서 이 두방식은 미립의 숫돌이용으로 일반연삭기에 정밀부속 장치의 보완없이 이용될 수 있다. ELID II 연삭에서 CIB-D숫돌은 파이프 형상의 전극에 의하여 간헐적으로 드레싱되고, 반면에 MRB-D 숫돌은 인프로세스 드레싱 되며 전극은 필요로 하지 않는다. 본 연구에서는 ELID II 및 ELID III 방식에 있어서, 연삭조건 및 연삭입자크기에 대한 연삭특성을 비교검토 하였다. 그 결과, ELID II, III방식 공히 대단히 작은 표면거칠기를 갖는 경면이 얻어짐을 확인하였다.

• Journal of Welding and Joining
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• v.26 no.4
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• pp.55-60
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• 2008

Structural reliability of electrical panels installed in naval vessels is of critical importance from structural performance viewpoint. The panels may be exposed to vibration and fatigue loadings from internal and external sources and wave loading which cause fatigue cracking. In this study, common methods such as burr grinding and post weld heat treatment (PWHT), for the fatigue strength improvement of weldments are investigated. Burr grinding is carried out using a electric grinder in order to remove surface defects and improve the weld bead profile. And also PWHT is carried out for the purpose of removing residual. The effectiveness of the two post treatment methods is evaluated in terms of fatigue strength improvement of welded structures.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.2
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• pp.59-70
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• 1990

Crack of breaking toughness of most Ceramics material is 1-5MPa .root.m but that of Zirconia Ceramics is improved to be 6-8MPa .root.m and its development of machining difficult-to-machine material is on the rise as urgent subject. For general Zirconia Ceramics machining, diamond grinding wheel is generally used by selecting an appropriate one and establishing grinding condition but due to such limitations as economics, grinding efficiency and machining geometry, great interest in machining method being used for diamond tool is emphasized. But it is reported that diamond tool is oxidized by cutting heat in the air and is graphitized in vacuum, which causes bad effects on tool life. In this study, to restraint cutting heat the internal side of tool is cooled, and restraint low temperature cooling system and being experimented. Further, the machinability of diamond tool for Zirconia Ceramics machining is analyzed with respect to tool wear and stress.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.5
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• pp.44-50
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• 2006

Cam mechanisms are one of the most popular devices for generating irregular motion and are widely used in many automatic equipments, such as textile machinery, internal combustion engines and other automatic devices. In order to obtain the positive motion of follower by rotating cam, its shape should be correctly designed and manufactured. In present paper, a CAD/CAM system is developed for shape design of disk cams using relative velocity method and NC code generation using the biarc curve interpolation. And, a disk cam is successfully manufactured by the developed CAD/CAM system. Thus, it is shown that the developed CAD/CAM system can be used for high precision cam profile CNC grinding machine.

• Journal of Life Science
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• v.26 no.6
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• pp.651-656
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• 2016

Bee pollen is produced by honeybees and is considered one of the most balanced and nourishing nutritional supplements available. Historically, bee pollen has been prescribed for its healing properties and consumed for its high-energy supply. Recent research has provided evidence that bee pollen has diverse biological activities, such as anti-oxidant, anti-inflammatory, anti-bacterial, and even anti-cancer effects. However, the outer membrane of the pollen grain, exine, is highly resistant to most acidic solutions, high pressure, and even digestive enzymes, and the resulting low bioavailability limits its nutritional and clinical applications. This study applied a wet-grinding method to destroy the exine effectively, and it then examined the pollen's enhanced biological activity. First, microscopic observations provided strong evidence that wet grinding destroyed the exine time-dependently. In addition, the content of polyphenols, well-known ingredients of bee pollen and used as internal standards for the quality control of commercial pollen preparations, increased up to 11-fold with wet grinding. Further, the anti-oxidant activity demonstrated on the ABTS anti-oxidant assay, as well as the DPPH radical scavenging assay, was also dramatically increased. Together, the results presented here support a new technology by which bee pollen can be used as a resource for medical, nutritional, and cosmetic applications.