Friction Experiment of Linear Motion Roller Guide THK SRG25

Cheng, De-Jun,Yang, Wan-Suk,Park, Je-Hong,Park, Tae-Jo,Kim, Su-Jin,Kim, Gyung-Ho,Park, Chun-Hong 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.3

Friction is a characteristic that can be found in machine elements in common engineering use, and it has great effect on the machining performance of a machine tool. Linear motion (LM) guides supported by rolling elements are used for accurate positioning of precision machine. For accurate positioning, the frictional behavior of the LM guide must be understood. In this investigation, a new experiment is conducted to measure friction, and the behavior of LM roller guide friction is measured under various external loads, preloads, velocities, and lubricants. The results obtained from experiment are compared with reference data, and the experimental friction equation of LM roller guide THK SRG25 is achieved from experiment, which can be used to calculate LM roller guide friction and control positioning accuracy.

Friction Experiment of Linear Motion Roller Guide THK SRG25

De-Jun Cheng,김수진,양완석,박재홍,박태조,김경호,박천홍 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

Friction is a characteristic that can be found in machine elements in common engineering use, and it has great effect on the machining performance of a machine tool. Linear motion (LM) guides supported by rolling elements are used for accurate positioning of precision machine. For accurate positioning, the frictional behavior of the LM guide must be understood. In this investigation, a new experiment is conducted to measure friction, and the behavior of LM roller guide friction is measured under various external loads, preloads, velocities, and lubricants. The results obtained from experiment are compared with reference data, and the experimental friction equation of LM roller guide THK SRG25 is achieved from experiment, which can be used to calculate LM roller guide friction and control positioning accuracy.

지진하중을 받는 구조물의 성능에 기초한 마찰감쇠기 설계

민경원,김형섭 한국지진공학회 2003 한국지진공학회논문집 Vol.7 No.6

이 논문의 주된 목적은 지진을 받는 구조물의 비탄성 거동을 제어하기 위해 Coulomb 마찰감쇠기의 제어성능을 산출하는 것이다. 능력스펙트럼법을 이용하여 다양한 건물의 내진성능이 평가되나, 만약 평가된 성능수준이 목표수준에 미치지 못할 때는 추가적인 감쇠비를 산출하게 된다. 추가적인 감쇠비를 얻기 위한 마찰감쇠기의 리더 마찰력은 등가 점성 감쇠의 개념을 사용하여 산정된다. 이와 같이 제안된 방법의 효과를 증명하기 위해, 다양한 주기와 항복 후 강성비를 가진 단자유도 구조물들에 대하여 수치해석을 수행하였다. The main objective of this paper is to evaluate the control performance of a coulomb friction damper(CFD) for controlling the inelastic behavior of seismically excited structures, The seismic performances of various buildings are evaluated using capacity spectrum method(CSM), and the additional dampings are calculated If the evaluated performance levels of the buildings are below the target level. Maximum friction force of the CFD to achieve additional damping is provided using the concept of equivalent viscous damping, Numerical simulations for single degree of freedom(SDOF) systems with various structural periods and post yield stiffness ratios demonstrate the effectiveness of the proposed procedure.

변위비례식 마찰댐퍼 시스템의 임펄스 가진 응답해석

최명진,박동훈 한국소음진동공학회 2004 한국소음진동공학회 논문집 Vol.14 No.5

An Amplitude Proportional Friction Damper (APFD), in which the friction force is proportional to the system displacement, has been introduced and mathematically modeled. To understand the damping characteristics of APFD, analytical solutions for the impulse response has been derivedand compared to the viscous damper. It is found that APFD system has very similar damping characteristics to viscous damper even though it is a friction damper. APFD may be used as a cost-effective substitution for the viscous damper and could also be used to improve the simple friction or Coulomb dampersince APFD works with no stick-slip and always returns to original position when external disturbance is disappeared.

Identification of mechanical parameters for position-controlled servo systems using sinusoidal commands

Yoo, Min-Sik,Choi, Seung-Cheol,Park, Sang-Woo,Yoon, Young-Doo The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.6

This paper proposes an identification method for mechanical parameters based on position control. To improve motion control performance, the moment of inertia and friction components must be considered. Based on mechanical equations, the proposed method estimates the moment of inertia, viscous friction coefficient, and Coulomb friction in the off-line state. Mechanical parameters are obtained from the integral values for the products of the torque, speed, and position using the 90° phase relationship between acceleration and velocity. Simulation and experimental results demonstrate the validity and accuracy of the proposed method. Since its implementation is simple, this method can be applied easily to industry.

An Enhanced Force Bounding Approach for Stable Haptic Interaction by Including Friction

백상윤,박상수,류제하 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.6

There is an inherent trade-off between stability and transparency in haptic interaction systems when interacting with virtual environments. Therefore, no perfect transparency can be displayed with absolute stability. For meaningful interactions, anyhow, some level of transparency is necessary for providing realistic feelings. On the other hand, robust stability must absolutely be guaranteed against any virtual environments because unstable behaviors disrupt contact realism completely and/or may also injure human operators. In order to increase magnitude transparency of the haptic interaction system, this paper proposes a way of systematic inclusion of Coulomb friction component in the previous force bounding approach. In the inclusion, two type of force bounding approach are derived. The less conservative condition can generate significantly higher magnitude transparency in terms of the initial contact crispness as well as the steady-state contact force for very stiff virtual objects. However, there occur some contact oscillations to diminish contact realism due to the energy accumulation during free motion. In order to avoid contact oscillations, a more conservative condition is proposed for systematically removing the past accumulated energy. The proposed algorithm is also compared with the other similar algorithm. Comprehensive experimental results are presented to show the effectiveness of the proposed approaches.

디스크 스프링의 적층 배열에 따른 완충장치의 감쇠에 관한 연구

고석훈(Seok Hoon Ko),최명진(Myung Jin Choi) 한국가스학회 2008 한국가스학회지 Vol.12 No.4

본 연구에서는 비선형 디스크 스프링과 고무링으로 구성된 완충장치의 감쇠에 관하여 연구하였다. 고무링의 마찰력과 디스크 스프링의 이력현상을 측정하여, 디스크 스프링의 적층 배열에 따른 이력곡선을 근사하고, 소산되는 에너지의 양을 추산하였다. 마찰력과 소산 에너지에 근거하여 네 종류의 감쇠 해석모델을 제시하였으며, 각각의 모델에 대한 충격응답을 고찰하였다. 고무링의 마찰력보다는 디스크 스프링의 이력현상이 완충장치의 감쇠거동에서 더 큰 영향을 미치었다. 가장 실용적인 감쇠 모델로는 소산되는 총 에너지의 양에 근거한 등가 점성 감쇠 모델이 다른 감쇠 모델보다 적합하다는 결론을 얻었다. The damping of a shock absorption device composed of nonlinear disk spring stacks and rubber rings was investigated. Friction forces of rubber rings and hysteresis of disk springs were obtained experimentally. The hysteresis curves of several types of disk spring stacks were approximated, from which the energy dissipated was estimated. Based upon the friction force and the energy dissipated, 4 damping models were presented and shock responses of the damping models were investigated. The hysteresis of disk spring is more meaningful than the friction of the rubber ring for the damping. For practical use, equivalent viscous damping model for total energy dissipated per cycle was suggested.

Numerical simulation of concrete abrasion induced by unbreakable ice floes

Kim, Jeong-Hwan,Kim, Yooil The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper focuses on the numerical simulation of ice abrasion induced by unbreakable ice floe. Under the assumption that unbreakable floes behave as rigid body, the Discrete Element Method (DEM) was applied to simulate the interaction between a fixed structure and ice floes. DEM is a numerical technique which is eligible for computing the motion and effect of a large number of particles. In DEM simulation, individual ice floe was treated as single rigid element which interacts with each other following the given interaction rules. Interactions between the ice floes and structure were defined by soft contact and viscous Coulomb friction laws. To derive the details of the interactions in terms of interaction parameters, the Finite Element Method (FEM) was employed. An abrasion process between a structure and an ice floe was simulated by FEM, and the parameters in DEM such as contact stiffness, contact damping coefficient, etc. were calibrated based on the FEM result. Resultantly, contact length and contact path length, which are the most important factors in ice abrasion prediction, were calculated from both DEM and FEM and compared with each other. The results showed good correspondence between the two results, providing superior numerical efficiency of DEM.

Numerical simulation of concrete abrasion induced by unbreakable ice floes

Jeong-Hwan Kim,Yooil Kim 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper focuses on the numerical simulation of ice abrasion induced by unbreakable ice floe. Under the assumption that unbreakable floes behave as rigid body, the Discrete Element Method (DEM) was applied to simulate the interaction between a fixed structure and ice floes. DEM is a numerical technique which is eligible for computing the motion and effect of a large number of particles. In DEM simulation, individual ice floe was treated as single rigid element which interacts with each other following the given interaction rules. Interactions between the ice floes and structure were defined by soft contact and viscous Coulomb friction laws. To derive the details of the interactions in terms of interaction parameters, the Finite Element Method (FEM) was employed. An abrasion process between a structure and an ice floe was simulated by FEM, and the parameters in DEM such as contact stiffness, contact damping coefficient, etc. were calibrated based on the FEM result. Resultantly, contact length and contact path length, which are the most important factors in ice abrasion prediction, were calculated from both DEM and FEM and compared with each other. The results showed good correspondence between the two results, providing superior numerical efficiency of DEM.

가동물체형 파력발전장치에 적용되는 2차 에너지 변환 기계 시스템의 성능저하 요소 분석에 대한 연구

김태욱(Tae-Wook Kim),오재원(Jaewon Oh),이정희(Jung-Hee Lee),박지용(Ji-Yong Park),김경환(Kyong-Hwan Kim),하윤진(Yoon-Jin Ha) 한국해양환경·에너지학회 2020 한국해양환경·에너지학회 학술대회논문집 Vol.2020 No.11

2015년 파리기후협약을 통해 전 세계적으로 이산화탄소의 배출 감축을 의무화 하도록 강제하고 있다. 이러한 환경규제에 대응하기 위한 방안으로, 여러 신재생 에너지원 중 파력에너지는 삼면이 바다인 우리나라의 지리적 특성상 많은 관심을 받고 있는 에너지원 중 하나이다. 이에 따라, 최근 다양한 형태의 파력발전장치가 연구 개발되고 있는 상황이다. 그 중에서도, 가동물체형 파력발전 장치는 파도 에너지가 부체에 직접적인 영향을 주기 때문에 에너지 흡수 효율 측면에서 매우 유리하다. 본 연구에서는 가동물체형 파력발전 장치에 적용되는 대표적인 2차 에너지 변환 기계 시스템인 풀리-벨트 시스템을 대상으로 성능저하 요인을 분석하였고, 쿨롱 마찰 및 점성 마찰을 하중 형태로 고려하여 함께 물리모델에 인가할 수 있는 수식을 도출하였다. 이를 통해 성능저하 요소를 고려한 시스템의 효율 분석 및 평가가 가능할 것이라 판단된다. As a way to cope with recent environmental regulations, various types of wave power generators are being researched and developed. Among them, the movable object type wave power generator is very advantageous in terms of energy absorption efficiency because wave energy directly affects the floating body. In this study, the performance degradation factors were analyzed for the pulley-belt system, which is a representative secondary energy conversion mechanical system applied to a movable object type wave power generator. An equation that can apply Coulomb friction and viscous friction, which are performance degradation factors, to the physical model in the form of a load was derived. Through this, it is judged that it will be possible to analyze and evaluate the efficiency of the pulley-belt system considering the performance degradation factors.