지능형 주축 설계 기술

황영국(Young-Kug Hwang) 한국정밀공학회 2014 한국정밀공학회 학술발표대회 논문집 Vol.2014 No.10월

꼭지점 계획을 이용한 주축 사이즈와 베어링간 길이 결정

황영국(Young-Kug Hwang),이춘만(Choon-Man Lee) 한국생산제조학회 2008 한국생산제조시스템학회 학술발표대회 논문집 Vol.2008 No.10

The spindle is the main component in machine tools. The static and dynamic stiffness of the spindle directly affect the machining productivity and surface integrity of the workpiece. The static and dynamic stiffness of the spindle depend on the shaft size, bearing arrangement, bearing span length, and so on. Therefore, the selection of shaft size and bearing span length are important to improve the spindle stiffness. This paper presents an determination of shaft size and bearing span length in spindle design step. In order to select the optimal bearing and built-in motor locations with constraint conditions, the extreme vertices design was applied. The results show that extreme vertices design is usable for spindle design with design constraints.

공작기계용 고속ㆍ고능률 주축을 위한 가변예압량 결정에 관한 기초연구

황영국(Young-Kug Hwang),이춘만(Choon-Man Lee) 한국생산제조학회 2009 한국생산제조시스템학회 학술발표대회 논문집 Vol.2009 No.10

Modern machine tool spindles simultaneously require high stiffness and fast rotation characteristics for high speed, highly efficient processing, as well as for a wide range of use rotation. In order to this, a variable preload technology is needed so that the bearing that can apply a greater preload to raise the stiffness of the spindle at the low speed range and a smaller preload at the high speed range to reduce heat generation, as opposed to greater stiffness, and to allow high speed rotation. This paper propose the algorithm for determining the variable preload. For determination of a variable preload, the bearing life, rigidity, and the gyroscopic slip were considered as the constraint conditions. The bearing life was calculated by simultaneously considering the spindle rotational speed and external load.

주축 런아웃이 절삭흔과 표면거칠기에 미치는 영향에 관한 연구

황영국(Young-Kug Hwang),이춘만(Choon-Man Lee) 한국생산제조학회 2007 한국생산제조학회지 Vol.16 No.2

The radial error motion of a machine tool cutter/spindle system is critical to the dimensional accuracy of the parts to be machined. This paper presents an investigation into spindle run-out effects on cutting mark and surface roughness. We experimented the effects of spindle run-out on surface roughness in flat-end milling by cutting AL 7075 workpiece in various cutting conditions. In order to analyze the effects of run-out on the surface roughness, the spindle's radial error motions was measured by mounting a sphere target onto the spindle as a reference. From the experimental results, it was found that spindle run-out makes a directive effects on surface roughness in flat-end milling.

리니어모터 구조 최적화를 통한 성능 향상 [1]

황영국(Young Kug Hwang),이춘만(Choon Man Lee),은인웅(In-Ung Eun) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.5

고속 주축에서 클램핑력 및 회전수 변화에 따른 주축 인터페이스 접촉률 변화에 관한 연구 (1)

황영국(Young Kug Hwang),이춘만(Choon Man Lee),정원지(Won Jee Chung) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.3

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 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.

전자석을 이용한 주축용 베어링의 예압 조절 장치에 관한 연구

황영국(Young-Kug Hwang),김웅(Woong Kim),이춘만(Choon-Man Lee) 한국생산제조학회 2009 한국생산제조시스템학회 학술발표대회 논문집 Vol.2009 No.5

In today's machining environment, heavy cutting at a low speed and light cutting at a high speed, as are often performed on a single machine tool, must be carried out successively for highly efficient machining as well as high speed machining. Therefore, current machine tool spindles require great stiffness and high speed rotation performance simultaneously. To that end, a preload device is needed so that the bearing that can apply a greater preload to raise the stiffness of the spindle at the low-speed range while a smaller preload at the high-speed range to reduce heat generation as opposed to greater stiffness and to allow high-speed rotation. In this study, the new concept of an automatic variable preload device that can adjust the preload applied to spindle bearing using electromagnetic was proposed. A prototype for the automatic variable preload device using electromagnetic was created. With the prototype, it was confirmed that the preload device based on the proposed structure worked properly.

고속ㆍ정밀 이송용 리니어모터 개발을 위한 열적 안정성 향상에 관한 연구

황영국(Young Kug Hwang),이춘만(Choon Man Lee),은인웅(In-Ung Eun) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.6

Linear motors are efficient mechanism that offers high speed and positioning accuracy. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speed and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. This paper presents an investigation into the thermal behavior of linear motors with the objective of deriving the optimum cooling conditions. To reach these goals several experiments were carried out, varying operating and cooling conditions. From the experimental results, this research proposed cooling conditions to improve the thermal characteristics of the linear motors.

복합소재를 사용한 직선모터용 경량이송테이블 개발

황영국(Young-Kug Hwang),은인웅(In-Ung Eun),이춘만(Choon-Man Lee),서용원(Yong-Won Seo) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.4

Linear motors are efficient mechanism that offers high speed and positioning accuracy. By eliminating mechanical transmission mechanisms, much higher speeds and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. Therefore, it is necessary to design moving table with high stiffness, high efficiency and light weight construction. This paper presents the development of moving table using composite material. In order to develop light weight construction of moving table, finite element analysis is performed to find best moving table construction and composite stacking sequence. NASTRAN and MINITAB were used as the optimizer. A prototype for the moving table using composite material was created.

절삭력에 의한 공구와 공작물의 상대적 변형량 예측 [1]

황영국(Young-Kug Hwang),이춘만(Choon-Man Lee) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.9

Any relative deformation between the cutting tool and the workpiece at the machining point, results directly in form and dimensional errors. The source of relative deformations between the cutting tool and the workpiece at the contact point may be due to thermal, weight, and cutting forces. Thermal and weight deformations can be measured at various positions of the machine tool and stored in the compensation registers of the CNC unit and compensated the errors during machining. However, the cutting force induced errors are difficult to compensate because estimation of cutting forces are difficult. To minimize the error induced by cutting forces, it is important to improve the machining accuracy. This paper presents the pre-calculated method of form error induced by cutting forces. In order to estimate cutting forces, Isakov method is used and the method is verified by comparing with the experimental results. In order to this, a cylindrical-outer-diameter turning experiments are carried out according to cutting conditions.