• Title/Summary/Keyword: Minimum Quantity

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Analysis of computational fluid dynamics on design of nozzle for integrated cryogenic gas and MQL(minimum quantity lubrication) (극저온 가스와 MQL(minimum quantity lubrication)의 복합 분사를 위한 하이브리드 노즐 설계에 관한 전산유체역학 해석)

  • Song, Ki-Hyeok;Shin, Bong-Cheol;Yoon, Gil-Sang;Ha, Seok-Jae
    • Design & Manufacturing
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    • v.13 no.3
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    • pp.41-47
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    • 2019
  • In conventional machining, the use of cutting fluid is essential to reduce cutting heat and to improve machining quality. However, to increase the performance of cutting fluids, various chemical components have been added. However, these chemical components during machining have a negative impact on the health of workers and cutting environment. In current machining, environment-friendly machining is conducted using MQL (minimum quantity lubrication) or cryogenic air spraying to minimize the harmful effects. In this study, the injection nozzle that can combined injecting minimum quantity lubrication(MQL) and cryogenic gas was designed and the shape optimization was performed by using computational fluid dynamics(CFD) and design of experiment(DOE). Performance verification was performed for the designed nozzle. The diameter of the sprayed fluid at a distance of 30 mm from the nozzle was analyzed to be 21 mm. It was also analyzed to lower the aerosol temperature to about 260~270K.

Estimation of Tracking Vibration Quantity for an Optimal Tracking Controller Design (최적 트랙킹 제어기 설계를 위한 트랙킹 진동량 추정)

  • Lee, Moon-Noh;Jin, Kyoung-Bog;Lee, Jong-KeuK
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.5 s.98
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    • pp.578-585
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    • 2005
  • In this paper, we present a schematic method estimating the tracking vibration quantity occurring in the track-following system of an optical recording device. A tracking loop gain adjustment algorithm is introduced to estimate accurately the tracking vibration quantity in spite of the uncertainties of the tracking actuator, Accordingly, the tracking vibration quantity can be estimated from the tracking error, the controller output, the nominal actuator model, and a compensated gain. An optimal tracking controller can be designed from a minimum tracking open-loop gain calculated by the estimated tracking vibration quantity The proposed vibration quantity estimation and controller design method are applied to the track-following system of an optical recording device and are evaluated through the experimental result.

Design of a Robust Tracking Controller by the Estimation of Vibration Quantity (진동량 추정을 통한 강인 트랙킹 제어기의 설계)

  • Lee, Moon-Noh;Jin, Kyoung-Bog;Yun, Ki-Bong
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.9
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    • pp.856-860
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    • 2007
  • This paper presents a robust tracking controller design method for the track-following system of an optical recording device. A tracking loop gain adjustment algorithm is introduced to accurately estimate the tracking vibration quantity in spite of the uncertainties of the tracking actuator. A minimum tracking open-loop gain is calculated by the estimated tracking vibration quantity and a tolerable limit of tracking error. A robust tracking controller is designed by considering a robust $H_\infty$ control problem with the weighting function of a slightly larger gain than the minimum tracking open-loop gain. The proposed controller design method is applied to the track-following system of an optical recording device and is evaluated through the experimental result.

Numerical Analysis of Thermal Characteristics of a Milling Process of Titanium Alloy Using Nanofluid Minimum-Quantity Lubrication (티타늄 합금의 나노유체 극미량 윤활 밀링 공정 열특성에 관한 수치 해석 연구)

  • Kim, Young Chang;Kim, Jin Woo;Kim, Jung Sub;Lee, Sang Won
    • Journal of the Korean Society for Precision Engineering
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    • v.34 no.4
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    • pp.253-258
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    • 2017
  • This paper presents a numerical study on the thermal characteristics of a milling process of titanium alloy with nanofluid minimum-quantity lubrication (MQL). The computational fluid dynamics (CFD) approach is introduced for establishing the numerical model for the nanofluid MQL milling process, and estimated temperatures for pure MQL and for nanofluid MQL using both hexagonal boron nitride (hBN) and nanodiamond particles are compared with the temperatures measured by thermocouples in the titanium alloy workpiece. The estimated workpiece temperatures are similar to experimental ones, and the model is validated.

A Study on the Optimal Cutting Condition in Boring using MQL System (MQL장치를 이용한 보링 가공시 최적절삭조건에 관한 연구)

  • Han, Dong-Yong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.4
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    • pp.82-87
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    • 2011
  • Lubrication has an important role to reduce frictional forces and temperature between cutting chips and the face of a tool. However, it has harmful effects to workers' health and working environment. The purpose of this thesis is to find cutting conditions through the quality analysis in boring for SM45C steel using MQL(Minimum Quantity Lubrication). Machining process is super drill, tip drill, end mill and boring in order. Experimental factors of boring and the quantity of mist air are properly selected. With the analysis of experimental data, this thesis shows that boring with MQL improves the surface roughness when spindle speed is 934rpm or feeding speed is 74mm/min.

Experimental Characterization of Turning Process of Titanium Alloy Using Cryogenic Cooling and Nanofluid Minimum Quantity Lubrication (극저온 냉각 및 나노유체 극미량 윤활을 적용한 티타늄 합금의 선반 절삭가공 특성에 관한 연구)

  • Kim, Jin Woo;Kim, Jung Sub;Lee, Sang Won
    • Journal of the Korean Society for Precision Engineering
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    • v.34 no.3
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    • pp.185-189
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    • 2017
  • Recently, titanium alloys have been widely used in aerospace, biomedical engineering, and military industries due to their high strength to weight ratio and corrosion resistance. However, it is well known that titanium alloys are difficult-to-cut materials because of a poor machinability characteristic caused by low thermal conductivity, chemical reactivity with all tool materials at high temperature, and high hardness. To improve the machinability of titanium alloys, cryogenic cooling with LN2 (Liquid Nitrogen) and nanofluid MQL (Minimum Quantity Lubrication) technologies have been studied while turning a Ti-6Al-4V alloy. For the analysis of turning process characteristics, the cutting force, the coefficient of friction, and the surface roughness are measured and analyzed according to varying lubrication and cooling conditions. The experimental results show that combined cryogenic cooling and nanofluid MQL significantly reduces the cutting forces, coefficients of friction and surface roughness when compared to wet condition during the turning process of Ti-6Al-4V.

The Study for EOQ md OMMIP Comparison Analysis According to Order Lead Time Change (조달기간 변동에 따른 EOQ와 OMMIP 비교분석 연구)

  • Oh Sae-Kyung;Choi Jin-Yeong
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.27 no.4
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    • pp.83-89
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    • 2004
  • In this paper MIP(mean inventory period) Model and OMMIP decision flow have been developed. MIP model can calculate mean inventory period which is subject to the order quantity alternative plan. OMMIP decision flow leads how can decide the most minimized order quantity in mean inventory period among various order quantity alternatives. This paper also suggests how to select the order quantity with minimum inventory period as optimal order quantity by means of comparison each mean inventory period with other mean inventory period, after simulating EOQ and order quantity of OMMIP calculated in MIP model.

Optimal Ballasting in the Preliminary Ship Design Stage (초기설계 단계에서의 최적 발라스트 용량에 관한 연구)

  • Gang, Won-Su
    • 한국기계연구소 소보
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    • s.15
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    • pp.117-125
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    • 1985
  • It is usual practice to ballast a sip to maintain requires operational safety at sea. However, excessive ballasting may reduce the operational economy of a ship. Therefore, The determination of the optimal location and quantity of ballast water is one of the important works at the preliminary design stage. To provide a convenient tool to ship designers the program for the determination of the optimal location and program the effect of the change of ballast water quantity in each tank on some characteristics of a ship, such as trim, initial stability and heel, is investigated and the minimum quantity of ballast water for each tank which satisfies the operational safety requirements is calculated.

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A Dynamic Lot-Sizing Problem with Backlogging for Minimum Replenishment Policy (최소공급량 정책을 위한 추후조달 롯사이징 문제)

  • Hwang, Hark-Chin
    • Journal of Korean Institute of Industrial Engineers
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    • v.36 no.1
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    • pp.7-12
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    • 2010
  • This paper considers a dynamic lot-sizing problem with backlogging under a minimum replenishment policy. For general concave production costs, we propose an O($T^5$) dynamic programming algorithm. If speculative motive is not allowed, in this case, a more efficient O($T^4$) algorithm is developed.