• 기계와재료
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• v.11 no.2 s.40
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• pp.53-61
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• 1999

The paper describes a characteristics analysis for cushion pressure and cushion stroke time at hydraulic cushioning cylinder. In hydraulic cushioning cylinder, an inertia exaggerates a kinetic energy at a reciprocation that collide with an end of stroke and generate a destructive shock, noise and vibration within the structural and operating member of machine of equipment. In order to reduce which cause to undesirable noise, vibration and fatigue in hydraulic control system, it is indispensible measure a cushion parameters at cushion region of hydraulic cushioning cylinder. A cushioning device is applied to absorb high impact energy and to decelerate a fast travelling object, too. At an experimental results, it turns out that cushion pressure is mainly a function of the external load and cylinder input flowrate rather than the supply pressure.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.44-48
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• 2010

Hydraulic cylinder is one of many part on the hydraulic excavator working. Cushion has the important function of protecting cylinder against the shock when the piston comes at end position. Also, the cushion of cylinder has a great effect on the operator's comfortable. In this study, we have done a comparative analysis through computer simulation and experimental value on pressure that occurs on a cylinder moving excavator.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.2
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• pp.14-19
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• 2008

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.

• 기계와재료
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• v.25 no.3
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• pp.6-15
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• 2013

유압프레스의 단점을 극복하기 위해서 서보모트를 장착하여 성형속도를 높인 서보 유압프레스를 개발하게 되었으며, 특히나 서보모터를 국내산으로 적용하여 듀얼형으로 유압시스템의 효율성을 높여 최종적으로 개발함으로써 서보 유압프레스를 완전 국산화하였다. 또한 하사점 위치 제어의 용이성을 확보하기 위해 프레스 램용 메인 실린더에 톱니나사부를 만들어 임의의 위치에 정지할 수 있는 정지정도 및 하사점 위치 제어정밀도를 향상시켰으며, 유량의 미세 제어를 통해 프레스 램의 동작성을 개선코자 하였다. 다이쿠션은 메인 실린더와의 연계 제어를 통해 제품의 손상 방지 및 제품 추출의 용이성을 확보하였으며, 소재의 종류나 제품의 형상 특성에 따라 프리모션 제어가 가능한 지식기반형 자율제어 시스템을 적용하였다. 듀얼 서보시스템과 유압펌프가 연계구동함에 따라 기존 유압프레스 보다 약 40%이상의 에너지절감을 달성할 수 있을 것으로 예측되며, 현재 에코머신 인증제도에 대한 논의가 활발한 시점에서 매우 적합하고 필요한 하이브리드형 서보 유압프레스의 국산화 개발 사례라고 하겠다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1901-1907
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• 2010

A hydraulic cylinder is a primary component of an excavator and is used for activating attachments such as boom, arm, and bucket. Generally, the cylinder is prone to structural problems such as buckling and fatigue failure caused by cyclic high pressure. Therefore, the safety margin for fatigue, yield, and buckling during the design lifetime should be evaluated at the durability-design stage. The durability design includes basic and detailed stages. In the basic design, the principal dimensions of the rod and tube are determined by considering the working force, speed, and range with respect to yield and buckling. In the detailed design, the dimensions of the rod notch, welds, tube end, gland, orifice, and cushion ring are determined by considering the fatigue safety. We present and discuss the overall procedure for durability design and the related analysis techniques.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.365-366
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• 2006

Hydraulic circuit breaker is the most popular type of electric power circuit breaker because of its superiority of operating performance and capacity. For the improvement of hydraulic circuit breaker's operating performance, it is very important to analyze its dynamic behavior characteristics. In this study, hydraulic circuit is modeled, analyzed and experimented. As a result, the experimental data agree well with the numerical ones, and the numerical results can be applied to the design and the improvement of hydraulic electric power circuit breaker.