고속 디버링 머신의 개발에 관한 연구

구자함(Ja-Ham Koo),김인환(In-Hwan Kim),허남수(Nam-Soo Hur) 한국기계가공학회 2013 한국기계가공학회지 Vol.12 No.5

A high speed deburring machine was developed based on the analysis of magnetic contact force, forced vibration, stiffness and deformation of the structure. After 3 dimensional CATIA modelling, the stiffness and the deformation properties of the deburring machine in static and dynamic condition using finite element method were analyzed. Both static and dynamic simulation results showed that designed high speed deburring machine was well satisfied the stability properties at the operating condition. we have performance test program for the real system to evaluate the simulation results.

CNC 자동선반용 고속,소형 회전형 공구헤드(Swivel Tool Head)의 설계 및 성능시험

구자함 ( Ja Ham Koo ),정성원 ( Sung Won Chung ),박종민 ( Jong Min Park ),김종순 ( Jong Soon Kim ),김인환 ( In Hwan Kim ),권순구 ( Soon Goo Kwon ) 한국경영공학회 2012 한국경영공학회지 Vol.17 No.3

It has been required that a small-size high-speed swivel tool head be improved for productivity of a CNC automatic lathe. It has been a growing interest in shorter machining times with an increasing cutting speed. However, the increase in a rotating speed of a swivel tool head causes adverse effects: vibration and noise from a swivel tool head system. In this study, the fatigue life and contact pressure of a swivel tool head system were calculated, and its static and dynamic characteristics, such as vibration, noise, and precision, were measured using a reliable test device. With all these results, we developed a new prototype of a small-size high-speed swivel tool head, showing less noise and better precision than those of conventional ones.

고속 스핀들의 동적거동과 밸런싱 해석

구자함(Ja-Ham Koo),권순구(Soon-Goo Kwon),김종순(Jong-Soon Kim) 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.1

공작기계 응용에 있어서 고속 및 고효율 가공의 추세는 스핀들의 고속화를 지속적으로 요구하고 있다. 내장형 모터를 장착한 스핀들은 가공시스템의 구조를 단순하게 한다. 하지만 로터에는 불평형 질량에 의해 진동이 발생하며, 이를 제거하기 위한 밸런싱 작업은 필수적이다. 이 논문에서는 내장형 모터를 장착한 고속 스핀들의 동적거동을 해석하였다. 불평형 질량, 베어링 강성, 회전 속도의 변화에 따른 휘돌림 궤적을 해석하였고, 이를 저감시키는 방법을 모색하였다. 또한 Timoshenko 빔 요소를 적용하여 스핀들-베어링 시스템을 모델링하고, 영향 계수법을 적용하여 밸런싱 과정을 시뮬레이션 하였다. 스핀들의 경우, 불평형 하중이 작용할 때, 베어링 지지점에서 가장 작은 휘돌림 궤적이 나타났으며, 양단에서 가장 큰 휘돌림 궤적을 나타내었다. 스핀들의 회전속도가 증가함에 따라 스핀들 선단에서의 휘돌림 궤적도 증가하였다. 베어링의 강성이 커짐에 따라 휘돌림 궤적 또한 증가하였다. 밸런싱 전, 후의 휘돌림 궤적 반경은 최대 73%까지 감소함을 확인할 수 있었다. 이러한 연구 결과는 CNC 자동선반의 스핀들 고속화에 중요한 정보를 제공하고 있다. A spindle with a built-in motor can be used to simplify the structure of a machine tool system, but the rotor inevitably has unbalanced mass. This paper presents an analysis of the dynamic behavior. The spindle was used in a CNC lathe and investigated using the finite element method and transfer matrices. The high-speed spindle can be very sensitive to the rotation of an unbalanced mass, which has a harmful effect on many machine tools. Thus, a balancing procedure was performed with a spindle-bearing system for the CNC lathe by numerical analysis. The balancing was performed through the influence coefficient method, and the whirl orbit radii before and after balancing were compared to evaluate the effects. The results show that the rotational speed of the spindle seriously affects the whirl responses of the spindle. The whirl responses were also affected by other factors, such as the unbalanced mass and bearing stiffness. The balancing of the assembled spindle model significantly reduced the whirl orbit magnitude.

영향계수법을 이용한 고속 스핀들의 밸런싱에 관한 연구

구자함(Ja-Ham Koo),김인환(In-Hwan Kim),허남수(Nam-Soo Hur) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.4

The spindle with a built-in motor can be used to simplify the structure of machine tool system, while the rotor has unbalance mass inevitably. A high-speed spindle can be very sensitive to rotating mass unbalance which has harmful effect on many machine tools. Therefore, the balancing procedure to reduce vibration in rotating system is certainly needed for all high-speed spindles. So, it was performed with a spindle-bearing system for CNC automatic lathe by using numerical procedure. The spindle is supported by the angular contact ball bearings and the motor rotor is fixed at the middle of spindle. The spindle-bearing system has been investigated using combined methodologies of finite elements and transfer matrices. The balancing was performed through influence coefficient method and the comparison was made by whirl responses between before balancing and after balancing. As a result, balancing of simple spindle model reduced whirl orbit magnitude in case of a completely assembled spindle model.

조명기구의 배광해석용 소프트웨어 개발

허남돈,한욱표,구자함,김훈,Hur, Nam-Don,Han, Uk-Pyo,Koo, Ja-Ham,Kim, Hoon 한국조명전기설비학회 2003 조명·전기설비학회논문지 Vol.17 No.5

배광분포를 측정함으로써 조명기구의 모든 광학적 특성을 계산해낼 수 있으며 이를 바탕으로 조명설계를 수행할 수 있다. 이러한 일련의 측정과 해석을 위해 배광측정기의 개발시에 배광해석용 소프트웨어 개발이 동시에 이루어져야 한다 연구진이 현재 개발하고 있는 소프트웨어는 조명기구의 광학적 특성을 파악하는 데 있어, 상당히 유용한 기능들을 포함하고 있다. 또한, 조명설계에 있어 근본적인 문제 해결의 과학적 검증을 제공함은 물론, 더 나아가 조명계산에 있어 하나의 표준을 마련하는 데 기여할 수 있을 것으로 보인다. By measuring intensity distribution, it is possible to calculate all of optical characteristics of luminaire, and through it we are able to realize lighting design. On developing goniometer, development of software for analyzing and measuring of optical characteristics is needed. Software developed now by our lab. contains very useful functions to analyze optical characteristics of luminaire. Also in lighting design it can provide scientific verification of solution for fundamental issues, furthermore in lighting calculation it would be able to contribute toward providing one of the standards.

고속 회전형 공구헤드의 설계 및 성능시험

김인환(In-Hwan Kim),구자함(Ja-Ham Koo),허남수(Nam-Soo Hur) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.5

At present, a high-speed swivel tool head of a small size is required to improve the productivity of CNC automatic lathes. Hence, there is growing interest in shorter machining times with higher cutting speeds. However, an increase in the rotation speed of a swivel tool head also has adverse effects, such as vibration and noise caused by the swivel tool head system. In this work, the fatigue life and contact pressure of a swivel tool head bearing system driven by gears were calculated. Based on the calculated results, a prototype swivel tool head was manufactured and its static and dynamic characteristics, i.e., the vibration, noise and precision, were measured using a reliability testing device which allows the application of cutting force to the end of the swivel tool head.

지게차용 습식 브레이크의 스퀼소음 저감에 관한 실험적 연구

김태종(Kim, Tae-Jong),구자함(Koo, Ja-Ham),정의봉(Jeong, Weui-Bong),김영현(Kim, Young-Hyun),주원호(Joo, Won-Ho) 한국소음진동공학회 2010 한국소음진동공학회 논문집 Vol.20 No.12

The wet brakes used in an industrial forklift often produce noise on braking. Elimination or reduction of this squeal noise is an important task for the improvement of comforts. In this paper, a test rig was developed which was possible for testing of brake noise and an experimental measurement on squeal noise was performed. The causes of the brake noise are identified by experimenting how the factors such as automatic transmission fluid, the groove of friction-plate pad and the material of friction-plate pad affect the squeal noise. In order to identify the squeal characteristics, the signal analyses for noise are performed by using frequency spectrums. Experimental results showed that the viscosity of automatic transmission fluid and the groove pattern of friction-plate pad largely affect the reduction of the wet brake squeal noise in an industrial forklift.

CNC 자동선반 고속 스핀들의 밸런싱에 관한 연구

김태종(Kim, Tae-Jong),구자함(Koo, Ja-Ham),이시복(Lee, Shi-Bok),김문생(Kim, Moon-Saeng) 한국소음진동공학회 2009 한국소음진동공학회 논문집 Vol.19 No.11

A high-speed spindle can be very sensitive to rotating mass unbalance which has harmful effect on many machine tools. Therefore, the balancing procedure to reduce vibration in rotating system is certainly needed for all high-speed spindles. So, balancing procedure was performed with a spindle-bearing system for CNC automatic lathe by using numerical procedure. The spindle is supported by the angular contact ball bearings and the motor rotor is fixed at the middle of spindle. The spindle-bearing system has been investigated using combined methodologies of finite elements and transfer matrices. The balancing was performed through influence coefficient method and the comparison was made by whirl responses between before balancing and after balancing. As a result, balancing of simple spindle model reduced whirl orbit magnitude in case of a completely assembled spindle model.

왕복동형 압축기의 낙하충격 시뮬레이션 및 실험적 검증

김태종(Kim, Tae-Jong),김문생(Kim, Moon-Saeng),구자함(Koo, Ja-Ham) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.6

A reciprocating compressor used in domestic refrigerators can be subjected to many different forms of shock. These shocks are usually experienced during transporting the products from a manufacturer to customers. The hermetic structure of this kind of compressor makes it difficult to conduct drop tests for identifying the failure mechanism and their drop behaviors. The drop/impact simulation for a reciprocating compressor has been carried out with the explicit code LS-DYNA and its validation has been experimentally verified. Simulation results are in good agreement with those of drop test. The present method of drop/impact simulation provides an efficient and powerful solution to improve the design quality and reduce the design period.

배광 측정기기를 위한 조명 계산용 소프트웨어 개발

허남돈(Nam-Don Hur),한욱표(Uk-Pyo Han),구자함(Ja-Ham Koo),김훈(Hoon Kim) 한국조명·전기설비학회 2003 한국조명·전기설비학회 학술대회논문집 Vol.2003 No.-

현재, 연구진이 개발하고 있는 배광 측정기기를 위한 조명 계산용 소프트웨어는 일반적인 조명치들에 대한 계산 결과는 물론, 조명기구의 광학적 특성을 파악하는데 필요한 데이타를 제공한다. 조명용 배광 측정기기를 통해 조명기구의 배광 분포를 측정하게 되면, 이를 바탕으로 기구의 광학적 특성을 계산해낼 수 있는데, 이는 현재 개발하고 있는 조명 계산용 소프트웨어로 실현이 가능하다. 이러한 일련의 조명기구의 배광 측정과 그 해석이 조명 계산용 소프트웨어 개발의 주된 목적이라 할 수 있다. 본 논문에서는 그 동안 개발된 소프트웨어의 내용을 정리한 것이다.