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성백주(Baek Ju Sung),양희선(Hui Sun Yang),이종배(Jong Bae Lee) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
The pneumatic swivel unit is possible to perform repetitive moving work by rotating the rotary actuator while the pneumatic chuck is fixed to the object. Gears are formed in the rack piston, so that the driving shaft, in which the pinion gear is formed, rotates due to the reciprocating motion of the rack piston. The wear of the rod seal results in a loss of independence between the hole and the hole in the driving shaft, resulting in a leakage failure. In this paper, a life test method to reproduce the main failure mode of this swivel unit was developed and a reliability evaluation method of the swivel unit was established by selecting the comprehensive performance test, the environmental test and the safety test items. The life test method was based on the actual conditions of use, and the whole swivel unit was subjected to a straight-chuck-backward-rotation cycle as one cycle. Six samples were tested at a reliability level of 70% and a failure-free life test of 1.54 million cycles.
성백주(Baek Ju Sung),양희선(Hui Sun Yang),이종배(Jong Bae Lee),김도식(Do Sik Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
공작기계는 핵심 산업에 적용되는 기계부품을 가공하는 기계이다. 그 중에 선반은 가공할 공작물을 파지하고, 고속으로 회전시키면서 고정 공구를 이용하여 필요한 형상을 가공하는 장치이다. 그러므로 공작물을 파지하기 위한 클램핑 시스템과 파지한 공작물을 고속으로 회전하기 위한 스핀들 시스템이 필요하며, 대부분의 선반에서는 각각의 동력원이 클램핑 시스템 구동을 위한 유압동력과 스핀들 시스템 구동을 위한 전동기동력으로 이원화하여 사용되고 있다. 이러한 방식은 스핀들 시스템에서 벨트와 풀리의 마찰 및 벨트의 슬립에 의한 효율 저하뿐만 아니라 소음, 진동 발생 및 유지보수에 어려움이 있다. 또한 공작기계의 고속화 다기능화, 자동화 및 초정밀화에 능동적인 대처가 어렵다. 본 논문에서는 유압동력이 배제된 전기구동 방식 선반용 스핀들 시스템의 동력전달장치를 설계하여, 최대추력 35 kN, 드로우바 이송량 25 mm 이상을 구현할 수 있도록 시스템을 개선하였다. 설계개선에 있어서 ANSYS를 이용한 구조해석을 진행하고 동력전달장치에서 발생되는 등가응력을 분석하여 제품 설계에 반영하고 이에 대한 성능평가를 통해 타당성을 검증하였다. 현재 해당 제품에 대한 수명시험이 진행되고 있으며 향후 수명시험결과를 이용한 전기구동 선반용 주축의 수명특성을 분석하고 신뢰성 파라미터를 산출할 예정이다. Machine tools are machines that process machine parts that are applied to core industries. Among them, a lathe is a device that grips a workpiece to be processed, rotates at high speed, and processes a required shape using a fixed tool. Therefore, a clamping system for gripping the workpiece and a spindle system for rotating the gripped work at high speed are required and in most lathes, each power source is used by dualizing hydraulic power to drive the clamping system and electric motor power to drive the spindle system. This method has difficulty in generating noise, vibration, and maintenance as well as lowering efficiency due to friction between belt and pulley and slip of the belt in the spindle system. In addition, it is difficult to conative cope with the high-speed, multi-functional, automation and ultra-precision of machine tools. In this paper, the power transmission system of the spindle system for an electric driven lathe was designed without hydraulic power, and the system was improved to achieve a maximum thrust of 35 kN and a drawbar stroke of 25 mm or more. In design improvement, structural analysis using ANSYS was conducted, and the equivalent stress generated in the power transmission system was analyzed and reflected in the product design, and the feasibility was verified through performance tests. The life test of the product is currently in progress, and in the future, it is planned to analyze the life characteristics of the spindle for an electric drive using the life test results and calculate the reliability parameters.
성백주(Baek Ju Sung),김도식(Do Sik Kim),이종배(Jong Bae Lee) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
The change of linearity of torsion spring results in the change of torque characteristic of variable valve in the exhaust system. Torque characteristic of the variable valve effects on the noise emissions of exhaust system, this phenomenon increases the uncomfort of automobile and causes the environmental pollution problem. This paper proposes a computation method of spring constant of torsion spring which is one of the important components of variable valve for maintaining the continuous torque characteristic of variable valve, and some pieces of prototype of torsion spring and variable valve are manufactured by use of the calculated constants. And also, we proved the propriety of the constants by experiments using the prototypes.
성백주(Baek-Ju Sung),이성규(Sung-kyu Lee),장무성(Mu-Seong Chang),김도식(Do-Sik Kim) 한국신뢰성학회 2019 신뢰성응용연구 Vol.19 No.2
Purpose: In recent years, the drone industry has emergedas a future growth engine. Servomotor malfunction is one of the causes of falls during drone flight. In this paper, we address the causes of servomotor failure and verify the reliability of commercially available drones. Methods: The software application Minitab (Minitab, LLC) was used to select the lifetime distribution for servomotor life data analysis. The validity of the parameter estimate was verified using the statistical hypothesis test of the data corresponding to each test condition, and the guaranteed life was determined. Results: The shape parameter and the scale parameter of the servomotor were estimated to be 1.49 and 93.574 cycles, respectively, and the servomotor lifespan was estimated to be 117,602 cycles at the lower 95% confidence limit. This result implies that the product remains reliable for a period shorter than the warranty period. Conclusion: The life tests of servomotors widely used in the industry revealed that the reliability of the products is poorer than expected. In particular, as the demand for drones increases, product reliability will become a very important factor. It is expected that the results of this study will be useful to manufacturers and users.
성백주(Baek-Ju Sung),이성규(Sung-Kyu Lee),박태국(Tea-Kook Park),장무성(Mu-Seong Chang) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The closed expansion tank is installed in the pipe system which supplies heating and cooling water to the building. It prevents the pipe from corrosion or failure by completely sealing the pipe and stopping the airflow within the pipe. Also, the closed expansion tank gives stability to the piping system and solves the cool-down problems caused by air locking. However, after using the closed expansion tank for a long period, bladder damage appears due to accumulated fatigue and stress from inside of the pipe because of temperature change in the system water. This problem can cause serious piping system failure. In this paper, life test equipment of 2 sets expansion tank was designed through the field condition. And also, the shape parameters and life analysis results of the closed expansion tank which based on the life test data were suggested.