스마트 공장에서 자동화 공정을 위한 소형 자동 윤활 장치 구현

이유리,김형준,김만호 한국산업융합학회 2020 한국산업융합학회 논문집 Vol.23 No.5

Automatic lubrication devices are applied in various fields, such as huge machinery, construction machinery or commercial vehicles, to lower maintenance costs and protect the devices. In addition, the automatic lubrication device reduces frequent component failures cause by friction and allows the machine to replace the lubricating oil replenishment work carried out by the manager. However, the automatic lubricating device used in large machinery or commercial vehicles is relatively large, containing a large amount of lubricant in the space to be lubricated. On the other hand, a smart factory, such as a home appliance or cosmetics factory, lacks space to install large automatic lubrication devices, and it is difficult to distribute electricity. Therefore, there is a need for an automatic lubrication device that can be used in various environments that require lubrication. In this paper, a small automatic lubrication device is proposed for smart factories that have changed parts of existing factories, such as electronics factories, to minimize friction arising from mechanical parts, etc. In particular, the structure of lubricating pumps and component parts that are the core of automatic lubrication devices was described so that they could be utilized in various fields. Finally, a test bed environment is established for the proposed automatic lubrication device to evaluate its performance and verify its applicability.

Analytical study about effects of kerosene lubrication on slip, heat, and temperature of a cylindrical roller bearing

김동현,김명호,박지수 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

An aero-engine’s cost, weight, and complexity can be greatly reduced if fuel is used for lubrication instead of oil. However, there are not many published works about the effect of fuel lubrication on the rolling element bearings‘ motion. This research analytically investigates the effects of kerosene lubrication on the cage slip, heat generation, and temperature of a cylindrical roller bearing. We developed an in-house program composed of a simplified quasistatic model to predict the cage slip and a thermal network model to predict the bearing’s heat generation and temperature. The in-house program was verified with respect to data from previous researches. Four types of lubrication were investigated using the in-house program: under-race lubrication by oil, under-race lubrication by fuel, jet lubrication by oil, and jet lubrication by fuel. We conducted a parametric study by changing the bearing’s rotational speed, lubricant flowrate, and inlet lubricant temperature to compare the kerosene lubrication of an imaginary aircraft engine bearing to conventional oil lubrication.

Synergistic Effect of a Coating and Nano-Oil Lubricant on the Tribological Properties of Friction Surfaces

조용일,김수형,박정훈,구본철,이재근,박원규,이재열 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

In this study, we evaluated the tribological properties of grey cast iron (GC200) surfaces with and without MoS2 coating that were lubricated with either mineral oil or mineral oil in which fullerene nanoparticles were dispersed (i.e., nano-oil),by using a disk-on-disk type tribotester. A series of friction tests were performed using the disk-on-disk type tribotester under various normal forces, and the friction coefficient and friction surface temperature were monitored simultaneously. First, we observed that the friction coefficient of the GC200 surface that has a MoS2 coating and is lubricated with mineral oil was 32% lower than that of the GC200 surface without a MoS2 coating. Second, we found that the friction coefficient of GC200surfaces lubricated with nano-oil was approximately 74% lower than that of GC200 surfaces lubricated with mineral oil. This suggested that the effectiveness of nano-oil lubrication in reducing the friction between GC200 surfaces is considerably higher than that of MoS2 coating or mineral-oil lubrication. In order to examine the effects of both the coating and nano-oil lubrication, friction tests for MoS2-coated GC200 surfaces under nano-oil lubrication was performed. We observed the following: (i) the friction coefficient of MoS2-coated GC200 surfaces lubricated with nano-oil were approximately 82%lower than that of uncoated GC200 surfaces lubricated with mineral oil; (ii) the nano-oil lubrication even tended to prevent the coating from peeling off, presumably because the fullerene nanoparticles added in the mineral oil acted as ball bearings. These observations suggested that the presence of a coating on friction surfaces and the addition of nanoparticles in mineral oil lubricant have a synergistic effect in significantly reducing the friction between friction surfaces.

Synergistic Effect of a Coating and Nano-Oil Lubricant on the Tribological Properties of Friction Surfaces

Cho, Yong-Il,Park, Jung-Hoon,Ku, Bon-Cheol,Lee, Jae-Keun,Park, Warn-Gyu,Lee, Jae-Yeol,Kim, Soo-Hyung 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.1

In this study, we evaluated the tribological properties of grey cast iron (GC200) surfaces with and without $MoS_2$ coating that were lubricated with either mineral oil or mineral oil in which fullerene nanoparticles were dispersed (i.e., nano-oil), by using a disk-on-disk type tribotester. A series of friction tests were performed using the disk-on-disk type tribotester under various normal forces, and the friction coefficient and friction surface temperature were monitored simultaneously. First, we observed that the friction coefficient of the GC200 surface that has a $MoS_2$ coating and is lubricated with mineral oil was 32% lower than that of the GC200 surface without a $MoS_2$ coating. Second, we found that the friction coefficient of GC200 surfaces lubricated with nano-oil was approximately 74% lower than that of GC200 surfaces lubricated with mineral oil. This suggested that the effectiveness of nano-oil lubrication in reducing the friction between GC200 surfaces is considerably higher than that of $MoS_2$ coating or mineral-oil lubrication. In order to examine the effects of both the coating and nano-oil lubrication, friction tests for $MoS_2$-coated GC200 surfaces under nano-oil lubrication was performed. We observed the following: (i) the friction coefficient of $MoS_2$-coated GC200 surfaces lubricated with nano-oil were approximately 82% lower than that of uncoated GC200 surfaces lubricated with mineral oil; (ii) the nano-oil lubrication even tended to prevent the coating from peeling off, presumably because the fullerene nanoparticles added in the mineral oil acted as ball bearings. These observations suggested that the presence of a coating on friction surfaces and the addition of nanoparticles in mineral oil lubricant have a synergistic effect in significantly reducing the friction between friction surfaces.

Vapor Phase Lubrication을 통한 금속의 마찰 및 마멸 특성

김대은,양지철,성인하 한국트라이볼로지학회 2002 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.34 No.1

phase lubrication can be used as an alterative lubrication method to overcome the demerits of liquid and solid lubrications. In this work, the tribological characteristics of metals are investigated under vapor phase lubrication. It was found that the friction coefficient and wear volume can be controlled efficiently by the amount of vapor phase lubricant delivered to the sliding interface. The friction coefficient could be reduced to about 0.1 under vapor lubrication. Also, depending on the amount of vapor lubrication delivered to the system, the width of the wear track could be varied between 50 to 250 Um. It is shown that vapor phase lubrication mechanism is very effective to control the friction and wear phenomena without the use of excessive oil.

Oil film deposition characteristics and judgment of lubrication effect of splash lubricated gears

Feng-xia Lu,Kun Wei,Meng Wang,Mou Li,He-yun Bao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5

To study the oil film deposition characteristics of splash lubricated gears and determine whether their meshing area is completely lubricated, this study proposes the concept of judging the splash lubrication-deposition characteristics-inlet oil film thickness-lubrication effect. The critical oil film thickness that characterizes the full lubrication of the gear meshing area was obtained as 14.5428 μm by using elastohydrodynamic lubrication (EHL) theory. Based on computational fluid dynamics (CFD) method, based on the renormalization group (RNG) k-ɛ two-equation turbulence model, dynamic mesh model and volume of fluid (VOF) model, the numerical calculation of the intermediate gearbox in splash lubrication is carried out. The oil film deposition thickness of the gear tooth that was about to enter the meshing area was calculated to be 95.6207 μm. It was found that the meshing area is fully lubricated under the rated operating conditions.

틸팅 패드 베어링의 트라이볼로지 특성 평가를 위한 유막두께 측정 방법 연구

김미루(Mi-Ru Kim),이득우(Deug-Woo Lee),이승준(Seung-Jun Lee),시티 누르파딜라 빈티 자이니(Siti Nurfadilah Binti Jaini),정재호(Jae-Ho Jung) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.5

In studies on lubrication analyses, researchers have investigated mixed lubrication as well as hydrodynamic lubrication. One of these published studies concerns lubrication analysis by considering not only the surface roughness but also the slope parameter of the friction surface; in the study, the relative slope of the pad bearing surface was confirmed to influence the friction characteristics. However, verification of whether the lubrication analysis values are comparable to those of the friction tests is yet to be conducted. In this study, to experimentally verify the results of this previous lubrication analysis, we developed an experimental device to derive the slope parameter and analyzed the results. The film thickness was calculated by analyzing the slope parameter obtained from the friction tests and was then used as the input value for lubrication analysis.

베어링 편심도와 자세각에 따른 저어널 베어링의 윤활효과

김종도(Jong-Do Kim),왕일군(Yi-Jun Wang),윤문철(Moon-Chul Yoon) 한국기계가공학회 2015 한국기계가공학회지 Vol.14 No.5

The thickness of adsorbed molecular layers is the most critical factor in studying thin-film lubrication, and it is the most essential parameter that distinguishes thin-film from thick-film lubrication analysis. The thin film between the shaft and bearing surface within a very narrow gap was considered. The general Reynolds equation has been derived for calculating thin-film lubrication parameters affecting the performance of the circular journal bearing. Investigation of the load-carrying capacity and pressure distribution for the journal bearing considering the adsorbed layer thickness has been carried out. A Reynolds equation appropriate for the journal bearing is used in this paper for the analysis, and it is discussed using the finite difference method of the central difference scheme. The parameters, such as eccentricity and attitude angle, are used for discussing the load-carrying capacity of the journal bearing. The results reported in this paper should be applied to analysis of the journal bearing with different lubrication factors. The steady-state analysis of the journal bearing is conducted using the Reynolds model under thin-film lubrication conditions. For a journal bearing, several parameters, such as a pressure, load capacity, and pressure components of the bearing can be obtained, and these results can be stored in a sequential data file for later analysis. Finally, their distribution can be displayed and analyzed easily by using the MATLAB GUI technique. The load-carrying capability of the journal bearing is observed for the specified operating conditions. This work could be helpful for the understanding and research of the mechanism of thin-film lubrication.

돌기접촉을 고려한 거친 표면 위 다양한 패턴 형상에 따른 윤활 특성 연구

김미루(Mi-Ru Kim),이승준(Seung-Jun Lee),정재호(Jae-Ho Jeong),이득우(Deug-Woo Lee) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.4

Two surfaces that have relative motion show different characteristics according to surface roughness or surface patterns in all lubrication areas. For two rough surfaces with mixed lubrication, this paper proposes a new approach that includes the contact characteristics of the surfaces and a probabilistic method for a numerical analysis of lubrication. As the contact area of the two surfaces changes according to the loading conditions, asperity contact is very important. An average flow model developed by Patir-Cheng is central to the study of lubrication for rough surfaces. This average flow model also refers to a multi-asperity contact model for deriving a modified Reynolds equation and calculating the lubricant characteristics of a bearing surface with random roughness during fluid flow. Based on the average flow model, this paper carried out a numerical analysis of lubrication using a contact model by considering a load change made by the actual contact of asperities between two surfaces. Lubrication properties show different characteristics according to the surface patterns. This study modeled various geometric surface patterns and calculated the characteristics of lubrication.

고온용 폴리머 윤활 베어링의 특성과 응용평가 연구

김상근(Sangkeun Kim),한효섭(Hyoseup Han),한종대(Jongdae Han) 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.6

Polymer lubricant composed of porous structure resin retaining oil or grease provides oil lubrication, but it acts as solid. For synthesis of polymer lubricant, thermo plastics like polyethylene are normally used. Polymer lubricants are synthesized to be adjusted in composition from pure polymer to 60 percent content of oil. And then the internal space of bearing has been filled with polymer lubricant. Under severe operating conditions, bearings are usually damaged by grease deterioration, leakage and insufficient lubrication caused by insertion of water or foreign matters. In these conditions, polymer lubricating bearings which are packed with polymeric lubricant have been widely applied for satisfying maintenance cost and obtaining longer service life. In this work, two polymer lubricants optimized by SSRED (Six Sigma Robust Engineering Design) program using oil separation and OIT (oxidation induction time) values respectively. Then the performance of polymer lubricants for high temperature application was tested and evaluated. The optimized polymer lubricant by means of OIT value showed longer grease life than the optimized polymer lubricant by using oil separation.