유한요소법을 이용한 유압브레이커 Cylinder와 Piston의 열-구조 연성해석을 통한 안정성 평가

임동욱,박윤수,신봉철,Lim, Dong-Wook,Park, Yoon-Soo,Shin, Bong-Cheol 한국금형공학회 2018 한국금형공학회지 Vol.12 No.1

This study proves the causes of cylinder and piston jam by scratches which is the fatal problem of hydraulic breaker through the thermal analysis and thermal-structural coupled field analysis. The trouble from the scratch is a complex problem which can be caused by manufacturing process (this is an internal factor) and the users mistake or contamination in the hydraulic circuit (these are an external factor). Hence, it's not easy to investigate the causes, also hard to prevent the recurrence. In this reason, hydraulic breaker manufacturers are trying to improve the manufacturing process such as machining, heat treatment, grinding, cleaning, also to prevent the contamination in hydraulic circuit and to remove the remains. It's being managed thoroughly by manufacturers. This study shows the effect of the temperature rise by the frictional heat generated when the piston hits the tool on the hydraulic oil while the hydraulic breaker is operating, also the temperature distribution when it starts to affect main components of hydraulic breaker. The stress and the amount of deformation also could be found through thermal-structural coupled field analysis. It proved that the stress and deformation are proportionally increased according to the temperature rise in hit area, and it affects the cylinder and the viscosity of hydraulic oil inside the cylinder when it heats up beyond the certain temperature.

소형 유압실린더 개발을 위한 전산해석적 연구

김성현,이성현 한국기계기술학회 2023 한국기계기술학회지 Vol.25 No.4

Hydraulic cylinders are hydraulic system parts widely used in various industries such as construction machinery, machine tools, robots, automobiles, and automation systems. The maximum capacity of vane pumps used in machine tools is 70bar, but the actual operating pressure is less than 50bar. The allowable pressure of a commercial hydraulic cylinder is 140 - 210 bar, so it is heavy and uneconomical because it uses thick and strong materials. In this paper, we intend to develop a small and lightweight hydraulic cylinder suitable for the allowable pressure of 50bar or less so that it can be used in the hydraulic system field. In order to develop a compact hydraulic cylinder, flow analysis, and structural analysis were conducted under piston forward and backward conditions. The analyzed flow rate value was calculated to be suitable for the operation of the hydraulic cylinder. As a result of comparing the stress calculated under the forward/backward condition of the piston with the yield stress of the material, the safety factor was calculated to be more than 2.5.

유압실린더의 로드아이 변형률 특성 연구

김성현(Sung-Hyun, Kim),박종원(Jong-Won, Park),이기천(Gi-Chun, Lee),백민혁(Min-Hyeok, Baek),김재훈(Jae-Hoon, Kim) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.5

A truck that can lift the lid of the loading box using hydraulic or pneumatic cylinders. It is called Wingcar in the related industry in the wingbody vehicle by the name which derives from the appearance that the loader cover is opened like a wing In the domestic market, large-sized commercial vehicles with 2.5 tons or more produce about 60.000 units a year, and 30.000 are produced as wing-body vehicles, about 50%. It is known that it is common in Asia, and it is hard to see it in Europe and North America where the curtain side method is mainstream. It is known that the market size of the hydraulic cylinders for wing body automobile is about 10 times as large as the domestic market for the domestic companies to enter the Japanese market. The seal and packing of cylinder produced in Korea, due to the characteristics of maintain the function for a long-term once it is installed and it is difficult to maintenance through exchange, it should be careful in the design. More than 95% of domestic cylinder seals are manufactured using global brands such as BUSAK, MERKEL and NOK, which is a stumbling block to cost reduction. The hydraulic cylinder rod eye has a process of finishing the deformed roundness by welding the rod eye after the rod roughing and post-processing. Comparing the shape of the load eye. the strain of each part according to the thurst of the hydraulic cylinder for the wing body was checked and compared, and the cylinder load eye suitable for the use environment was selected.

Theoretical Analysis of Power Requirement of a Four-Row Tractor-Mounted Chinese Cabbage Collector

Swe Khine Myat,ISLAM MD NAFIUL,Chowdhury Milon,ALI MOHAMMOD,Wing Sandah,전현종,이상희,정선옥,김대건 한국농업기계학회 2021 바이오시스템공학 Vol.46 No.2

Purpose Analysis of power requirement is the key issue to ensure the optimal design. The objectives of the study were to investigate theoretically the tractor hydraulic power and draft power requirement of a tractor-mounted Chinese cabbage collector system and to suggest design guidelines. Methods The major components of the Chinese cabbage collector under development were a belt type conveyor, a hydraulic motor, and three hydraulic cylinders. Hydraulic motor power, cylinder hydraulic power, and draft power for various speeds under unloaded and loaded conditions were calculated using theoretical equations. Different tractor configurations (44~74 kW), soil types (sand, silt, and clay), and hydraulic fluid capacity (1~5m3/hr) were considered to determine the tractor hydraulic power and engine power requirement. Results The power requirement of the hydraulic motor for the unloaded and loaded conditions was 1.14 kW and 1.24 kW, respectively, under the 120-rpm conveyer speed. Hydraulic power of 2 ×10−3 kW was required to fold or unfold the collecting conveyor. The maximum required draft power levels were 0.67, 0.81, 0.94, and 1.21 kW for the hard, firm, tilted, and soft soil conditions, respectively. Based on the results, the total maximum power requirement was calculated as 15.14 kW, of which 7.25 kW is for the hydraulic power (48%) and 7.89 kW for the draft power (52%), respectively. Conclusion The analysis of power requirements presented in this research can help estimate the tractor hydraulic power and draft power requirement to run a tractor-mounted Chinese cabbage collector efficiently.

유압실린더 구동식 전도수문의 부하 해석 프로그램 개발

이성래(Seong-Rae Lee) 유공압건설기계학회 2011 유공압건설기계학회 학술대회논문집 Vol.2011 No.6

The load analysid program of rotating-type floodgate actuated by the hydraulic cylinders is developed using the Excel program language. The mathematical model of the floodgate actuating system is derived. Then the mathematical model is transformed into Excel program which calculates the water pressure moment, gate weight moment, cylinder length, cylinder force and cylinder pressure versus gate angle of 0~60[deg] upon the physical and geometrical parameters such as the gate weight and the installation positions of gate, roller, link, hydraulic cylinder. The user can install the Excel language in low cost and understand it easily comparing to the Matlab or Visual C++ languages.

The Performance Evaluation of a Hydraulic and Magnetic Clamp Device Manufactured to Transport with Safety the Curved Steel Plate Required for Shipbuilding

문병영,이기열,박광복,홍영준,이성범 한국마린엔지니어링학회 2015 한국마린엔지니어링학회지 Vol.39 No.5

As a new technical approach, a hydraulic and magnetic clamp device was attempted to realize a magnetic clamp crane system that uses 8 simultaneously actuating individual hydraulic cylinders. Through this approach, a Sr type of ferritic permanent magnet (SrO ․ 6Fe2O3), not the previously employed electro-magnet, was utilized for the purpose of lifting and transporting the heavy weighted and oversized curved steel plates used for manufacturing the ships. This study is aimed at manufacturing and developing the hydraulic magnetic clamp prototype, which is composed of three main parts – the base frame, cylinder joint, and magnet joint – in order to safely transport such curved steel plates. Furthermore, this research was pursued to conduct a performance evaluation as to the prototype manufacture and acquire the planned quantity value and the development purpose items. The most significant item for a performance evaluation was estimated for the magnetic adhesive force (G) and in this process, a ferritic permanent magnet (Sr type) with 3700~4000 G of residual induction (Br) and 2640/2770 Oe of coercive force (Hc) was utilized. In addition, other relevant items such as hoist tension (kN), transportation time (sec), and the applied load (Kgf) exerted on the hydraulic cylinders were also evaluated in order to acquire the optimum quantity value. As a result of the evaluation, the relevant device turned out to be suitable for safely transporting the curved steel plates.

유압실린더의 쿠션링 형상에 따른 쿠션 특성 연구

이용범(Y. B. Lee),고재명(J. M. Ko),박종호(J. H. Park) 유공압건설기계학회 2008 드라이브·컨트롤 Vol.5 No.2

Hydraulic excavator consists of booms, arms, bucket, and cylinder. The cylinder make these structures moved and the cushion parts of cylinder in operation absorb the great impact which is stemmed from high velocity and pressure at cushion parts of cylinders. The cushion technology of cylinders has a great effect on the operator’s comfortable as well as protecting equipment from damage by suppressing the inertia of the hydraulic excavator. In this study, three hydraulic cylinders have different shapes of a cushion ring, respectively. we studied optimal cushion pattern by analyzing the change of cushion pressure and time, according to supply pressure and velocity variations.

The Performance Evaluation of a Hydraulic and Magnetic Clamp Device Manufactured to Transport with Safety the Curved Steel Plate Required for Shipbuilding

Moon, Byung Young,Park, Kwang Bok,Hong, Young Jun,Lee, Sung Bum,Lee, Ki Yeol The Korean Society of Marine Engineering 2015 한국마린엔지니어링학회지 Vol.39 No.5

As a new technical approach, a hydraulic and magnetic clamp device was attempted to realize a magnetic clamp crane system that uses 8 simultaneously actuating individual hydraulic cylinders. Through this approach, a Sr type of ferritic permanent magnet ($SrO{\cdot}6Fe_2O_3$), not the previously employed electro-magnet, was utilized for the purpose of lifting and transporting the heavy weighted and oversized curved steel plates used for manufacturing the ships. This study is aimed at manufacturing and developing the hydraulic magnetic clamp prototype, which is composed of three main parts - the base frame, cylinder joint, and magnet joint - in order to safely transport such curved steel plates. Furthermore, this research was pursued to conduct a performance evaluation as to the prototype manufacture and acquire the planned quantity value and the development purpose items. The most significant item for a performance evaluation was estimated for the magnetic adhesive force (G) and in this process, a ferritic permanent magnet (Sr type) with 3700~4000 G of residual induction (Br) and 2640/2770 Oe of coercive force (Hc) was utilized. In addition, other relevant items such as hoist tension (kN), transportation time (sec), and the applied load (Kgf) exerted on the hydraulic cylinders were also evaluated in order to acquire the optimum quantity value. As a result of the evaluation, the relevant device turned out to be suitable for safely transporting the curved steel plates.

언밸런스 방지를 위한 유압실린더의 궤적 추종 제어

최종환(Jong-Hwan Choi) 한국기계가공학회 2008 한국기계가공학회지 Vol.7 No.3

The work to raise the bridge plate by using two hydraulic cylinders is very dangerous when generating the unbalance state between cylinders. For solving this problem, one cylinder is forced to follow the trajectory of another cylinder instead of applying the same trajectory to two cylinders at once. In this paper, the control method for dynamic stable on lifting the bridge plate is proposed. The simulation model is derived by using commercial software, AMESim and MatLab/simulink. The PID controller is designed on one cylinder for following the reference trajectory and the adaptive controller is designed on another cylinder for tracking the displacement of one cylinder. The performance improvement is shown by comparing the simulation results through computer simulation.

외압을 받는 두꺼운 원통형 내압용기의 붕괴하중 해석

이재환,박병재 대한조선학회 2019 大韓造船學會 論文集 Vol.56 No.2

Number of studies on the buckling of thin cylindrical pressure vessels, such as submarine pressure hull and pipe with a large ratio of diameter/thickness, have been carried out in the naval and ocean engineering. However, research about thick cylinder pressure vessel has not been active except for the specific application in nuclear area. There are not many papers for the estimation of buckling and ultimate load capacity of thick cylinders for the deep sea usage. Thus, it is important to understand the theoretical bases of the buckling and collapse process and the derivation process of such loads for the proper design and structural analysis. The objective of this study is to survey the collapse behavior, to analyse and clarify the derivation procedure and to estimate the ultimate collapse load for thick cylinder by analyzing relevant books and papers. It is found that the yielding begins at the internal surface of the thick cylinder and plasticity develops from the internal surface to the external surface to generate collapse. Also the initial imperfection of cylinder develops flattening and consequently accelerates buckling and finally ultimate collapse. By comparing the collapse loads of aluminum thick cylinder by applying equations herein, it is shown that the equations analyzed are appropriate to obtain collapse load for thick cylinder.