• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.36-43
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• 2008

This research is tendencious to manufacture solid piston-rod of shock absorber as hollow piston-rod using friction welding. The SM45C has been welded to the SM45C-pipe in order to investigate the effect of upset pressure on friction weldability. The friction time and upset pressure was variable conditions under the conditions of spindle revolution of 2,000rpm, friction pressure of 55MPa, and upset time of 2.0seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests were studied of friction weld, and so the results were as follows. When the upset pressure is sufficient, gets the high tensile strength. The optimal welding conditions were n=2,000rpm, $P_1$=55MPa, $P_2$=95MPa, $t_1$=1.5sec, $t_2$=2.0sec when the total upset length is 4.5mm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7745-7753
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• 2015

Gas springs of the television is to control the piston speed when operating under along stroke(200~300 mm, television elevation)is possible. User by this principle is capable of elevation adjustment. First carried out a flow analysis of the piston. A piston speed adjustment technique for precise pipe type cross-section was examined. The piston structure for flow rate control and elevation action is proposed. This study is the development of a gas spring of more than 50 inch television with a large television stand. Hollow piston rod for optimal control(the outer diameter 19.9 mm, the inner diameter 13.9 mm) was injected into the nitrogen gas(0.3 mm/s) in. As a result, the flow rate the pressure drop of the piston rod as the increase was increased without any change of the external force. As a result, control of the displacement via the gas spring is possible.

• Transactions of Materials Processing
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• v.20 no.3
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• pp.236-242
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• 2011

The two objectives of this study were, first, to determine the optimal friction welding process parameters using finite element simulations and, second, to evaluate the mechanical properties of the friction welded zone for large piston rods in marine diesel engines. Since the diameters of the rod and its connecting part are very different, the manufacturing costs using friction welding are reduced compared to those using the forging process of a single piece. Modeling is a generally accepted method to significantly reduce the number of experimental trials needed when determining the optimal parameters. Therefore, because friction welding depends on many process parameters such as axial force, initial rotational speed and energy, amount of upset and working time, finite element simulations were performed. Then, friction welding experiments were carried out with the optimal process parameter conditions resulting from the simulations. The base material used in this investigation was AISI 4140 with a rod outer diameter of 280 mm and an inner diameter of 160 mm. In this study, various investigation methods, including microstructure characterization, hardness measurements and tensile and fatigue testing, were conducted in order to evaluate the mechanical properties of the friction welded zone.

• Tribology and Lubricants
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• v.38 no.6
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• pp.227-234
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• 2022

Recently, the demand for improving energy efficiency has rapidly increased because of the growing concerns over environmental issues. In this work, the tribo-test and simulation for the initial wear and lubrication performance were performed for the piston pin in the small end system of the connecting rod of a marine engine, to obtain useful data for improving the efficiency of marine engine systems. In addition, a diamond-like carbon (DLC) coating was applied to the piston pin to explore feasibility of eliminating the bush used in the system. The initial wear and lubrication characteristics between the uncoated piston pin and bush were compared with that between the DLC-coated piston pin and connecting rod in the tribo-test. The simulation for the wear and lubrication performance according to the wear progression was conducted based on the data obtained from the test. The wear characteristics were quantitatively assessed by the wear depth and wear volume, and the lubrication performance was characterized with the change of pressure and minimum oil film thickness with respect to the crank angle. It was found that the DLC-coated piston pin may provide better initial wear characteristics and lubrication performance. The results of this work may provide fundamental information for marine engines with improved efficiency.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.39-46
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• 2000

In this paper, the analysis of dynamic characteristics and performance investigation of the ER damper are investigated. The ER damper is based on a double rod actuator and an electric field are applied to the moving electrode composed of cylinder and piston. The performance of the ER damper is length of piston electrode field and its velocities. The experimental and calculated results show that the characteristic of the ER damper varies with the magnitude of the electric field.

• Journal of Welding and Joining
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• v.26 no.2
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• pp.55-61
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• 2008

Various research to reduce weight of a car is achieving. This research is tendencious to manufacture solid piston rod of shock absorber as hollow piston rod using friction welding. This study deals with the friction welding of SM45C to SM45C-Pipe that is used in car shock absorber, The friction time was variable conditions under the conditions of spindle revolution of 2,000rpm, friction pressure of 55MPa, upset pressure of 75MPa, and upset time of 2.0seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests were studied of friction weld, and so the results were as follows. 1. In tensile strength, the hole processing is better than non-hole processing. 2. When the friction time was 1.5seconds under the conditions, the maximum tensile strength of the friction weld happened to be 869MPa, which is 103% of SM45C's tensile strength and 91% of SM45C's Pipe. 3. When the friction time was 2.0seconds under the conditions, the maximum bending strength of the friction weld happened to be 1599MPa, which is 80% of SM45C's bending strength and 118% of SM45C's Pipe.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.409-410
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• 2002

In order to measure the oil-film pressure in sliding surface of machinery, we have developed a piezo-resistive type thin-film pressure sensor. To reduce the measurement error due to temperature and strain, the constituent of the pressure sensitive alloy was optimized and a new sensor shape was devised. In this study, we present the measurement results of the oil-film pressure distribution in engine connecting rod big-end bearing and piston pin- bosses with 3 different pin-boss shapes using the newly developed thin-film pressure sensor.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.4
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• pp.66-74
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• 1990

Friction between piston-ring assembly and cylinder wall of a spark ignition engine was evaluated under various engine operating conditions utilizing a grasshopper linkage system. The friction force was estimated by the force balance relation at the small end of connecting rod. Three forces were chosen to be measured for the objective. They were gas pressure inside the cylinder, inertia force of the piston-ring assembly, and the force exerted by the connecting rod. These forces were measured by a piezo type pressure sensor, an accelerometer and strain gauges, respectively. Comparisons were made with the frictional force evaluated by the conventional method where the assumption of constant rotational speed of engines was adopted. Due to the variation of rotational speed of engines, the conventional method was found to lead to a large error in the evaluation of the frictional force.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7166-7175
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• 2015

This paper is a study on using gas springs for reduced friction in the elevation of the large television stand. Target is applied to the operation of the elevation over 50-inch television that uses a gas spring. Gas seal lip technology is needed for development acting on the piston rod in order to obtain a reduction in friction in elevation operation. In order to acting on the gas seal lip technology, the improved friction force can be obtained through the inner diameter of gas seal lip, the design of cutting angle and the changes of material.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.4
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• pp.87-92
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• 2009

쇽옵서버 피스톤로드(shock absorber piston rod)는 자동차의 충격과 진동의 흡수에 작용하는 자동차 현가장치(suspension equipment)부품의 일종이다. 피스톤로드는 자동차 충격흡수에 매우 밀접한 영향을 주기 때문에 제조에 있어서 고도의 정밀도와 표면 매끄러움이 요구된다. 피스톤로드의 제조공정은 선삭, 홈가공, 밀링, 전조 등 여러 공정으로 구성되는데, 여기서 품질불량에 가장 크게 영향을 주는 공정은 선삭공정(lathing process)이다. 이는 선삭공정의 가공공구(insert component)가 주원인으로서 반복되는 가공으로 인한 공구의 마모(abrasion)나 파손(breakage)이 주요 원인으로 지적되고 있다. 따라서 가공 데이터를 수집 분석하여 공구의 교체시기를 파악한다거나 가공 부품의 측정 데이터가 관리도 상하한선 내에 있는지 등 가공 공정 전반에 대한 체계적인 공정관리 시스템 개발이 요구된다. 본 연구에서는 자동차 쇽업서버 피스톤로드 제조공정의 가공 정보를 체계적으로 수집하여 관리하고 분석하는 자동차 쇽업서버 피스톤로드 제조공정에 대한 공정관리시스템을 개발하는 것이 목적이다. 개발결과 피스톤 로드의 측정 치수 변화 및 불량발생을 측정, 감지할 수 있었으며, 본 시스템을 통해 가공공구의 치수오차를 보정(compensation)하고 공정의 불량발생을 조기에 방지 함으로써 불량률은 1/5로 경감하고 작업자 수도 1/2로 감소시킬 수 있었다.