• Title/Summary/Keyword: reheating method

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A Study on the Estimation of One-dimensional Beat Fluxes on the Slab in Reheating Furnace by Using Inverse Analysis (역해석을 이용한 가열로 내 소재의 1차원 열유속 추정에 관한 연구)

  • Kang, Deok-Hong;Kwag, Dong-Seong;Kim, Woo-Seung;Lee, Yong-Kuk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.1
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    • pp.61-68
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    • 2003
  • This study deals with the use of the conjugate gradient method for the simultaneous estimation of two unknown boundary heat fluxes on the slab in reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. The heat flux estimations for three different cases of measurement locations in the slab are performed: non-skid, skid, and shift-skid zones. The estimated heat fluxes for three cases indicated the three regions having local peak values of heat fluxes. The estimated temperatures at measurement locations were in good agreements with the measured temperatures within 5% relative error.

A Study on Optimum Reheating Process of Automotive Aluminum Piston using Neural Network and the Taguchi Method in Semi-Solid forming (반용융 성헝에서의 다구찌 방법과 신경망을 이용한 자동차 알루미늄 피스톤의 최적 재가열 과정에 대한 연구)

  • 윤재민;김영호;박준홍;최재찬
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.902-905
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    • 2000
  • As the manufacturing processes of automotive engine piston, gravity die-casting, squeeze casting, hot forging and powder forging process are generally used for the various specifications. As the semi-solid forming(SSF) is compared with conventional casting such as gravity die-casting and squeeze casting for the characteristics of its process, the product without inner defects such as gas porosity and segregation can be obtained and its microstructure is globular grain. In SSF process, the materials are heated up to the temperature between the solvus and liquidus line at which the materials exists in the form of liquid-solid mixture. In this time, Discussion is given about reheating process of row material and results are presented regarding accurate temperature and process variables controlling for right solid fractions.

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A Study on the Estimation of One-dimensional Heat Fluxes on the Slab in Reheating Furnace by Using Inverse Analysis (열해석을 이용한 가열로 내 소재의 1차원 열유속 추정에 관한 연구)

  • Kwag, Dong-Seong;Kang, Deok-Hong;Kim, Ki-Hong;Lee, Yong-Kuk;Jeong, Hong-Gyu;Kim, Woo-Seung
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.254-259
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    • 2001
  • This study deals with the use of the conjugate gradient method for the simultaneous estimation of two unknown boundary heat fluxes on the slab in reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. The heat flux estimations for three different cases of measurement locations in the slab are performed: non-skid, skid, and shift-skid zones. The estimated heat fluxes for three cases indicated the three regions having local peak values of heat fluxes. The estimated temperatures at measurement locations were in good agreements with the measured temperatures within 5% relative error.

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An Inverse Analysis on the Estimation of Two-dimensional Overall Heat Absorptance on the Slab in the Reheating Furnace (가열로 내 소재의 2 차원 총괄열흡수율 추정에 관한 역해석)

  • Kang, Deok-Hong;Kwag, Dong-Seong;Kim, Woo-Seung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.11 s.242
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    • pp.1257-1264
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    • 2005
  • An inverse problem to determine two-dimensional total heat exchange factor is studied for the prediction of the slab temperature in the reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. This inverse analysis employs the conjugate gradient method. The overall heat absorptances for 12-zones of the cross-section of the slab are estimated. The estimated temperatures at measurement locations are in good agreements with the measured temperatures.

The Study on the Gas Temperature Set by Calculating the Sensitivity of Slab Temperature in Reheating Furnace (소재온도 감도계산을 통한 가열로내 분위기온도 설정방안 연구)

  • Gang, Deok-Hong;Kim, Gi-Hong;Lee, Yong-Guk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.8
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    • pp.1030-1036
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    • 2001
  • A new mathematical model to determine the optimal gas temperatures in reheating furnace was proposed for the good quality of products. This model employs sensitivity method to calculate the optimal gas temperatures in each zone for heating the slab up to its discharging target temperature and for heating it uniformly. This method was validated by showing that the calculated discharging temperature of the slab was in a good agreement with its prescribed discharging target one through an off-line simulation.

Impact of Cooking, Storage, and Reheating Conditions on the Formation of Cholesterol Oxidation Products in Pork Loin

  • Min, Joong-Seok;Khan, Muhammad I.;Lee, Sang-Ok;Yim, Dong Gyun;Seol, Kuk Hwan;Lee, Mooha;Jo, Cheorun
    • Food Science of Animal Resources
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    • v.36 no.1
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    • pp.23-28
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    • 2016
  • This study investigates the effect of cooking, storage, and reheating conditions on the formation of cholesterol oxidation products (COPs) in pork loin. Samples of pork loin procured 24 h postmortem were initially processed and assessed for total fat and cholesterol content. The cooking methods evaluated were pan roasting, steaming, oven grilling, and microwaving. Cooked pork loin samples were stored at 4℃ and reheated after 3 and 6 d of storage using the original method of preparation or alternately, microwaving. Fat content increased significantly with cooking as a result of the loss in moisture but cholesterol content remained unchanged. Pan roasting and microwave cooking caused a significantly higher production of COPs, as with the process of reheating using microwave, pan roasting, and oven grilling methods. The major COPs found in pork loin were cholestanetriol, 20-hydroxycholesterol, and 25-hydroxycholesterol, whose concentrations varied according to the different cooking and reheating methods used. Moreover, the aerobic storage of cooked pork loin under a refrigerated condition also increased the formation of cholesterol oxides on reheating.

Optimum Fabrication Conditions and Reheating Characteristic of Semi-Solid Al-Zn-Mg-(Sc) Alloy by Inclined Cooling Plate (경사냉각판을 이용한 Al-Zn-Mg-(Sc) 반응고 합금 제조의 최적화 및 재가열 특성)

  • Kim, Tae-Hun;Shim, Sung-Yong;Park, Hyung-Won;Lim, Su-Gun
    • Journal of Korea Foundry Society
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    • v.29 no.5
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    • pp.213-219
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    • 2009
  • Optimum conditions for production of semi-solid Al-Zn-Mg alloy billets was carried out by the Taguchi design method. And, Al-Zn-Mg alloy billets contained Sc (free, 0.1 and 0.3 mass %) were fabricated at optimum conditions. Evolution of microstructure in semi-solid state was investigated through various liquid fractions, holding times and holding temperatures. The Al-Zn-Mg alloy billets reheated at $615^{\circ}C$ during 30min are grain growth and it was fractured due to increasing liquid fraction before quenching. And, during reheating up to $600^{\circ}C$, grain growth of Al-Zn-Mg alloy billets contained Sc (0.1 and 0.3 mass %) was not occurred in comparison with those of Al-Zn-Mg alloy without Sc. It was thought that $Al_3Sc$ phases have a pinning effect in grain boundary and Sc content of 0.1 mass% is able to inhibit grain growth effectively through reheating process.

A Billet Heat Transfer Modeling during Reheating Furnace Operation

  • Jang, Yu-Jin;Kim, Sang-Woo
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.863-868
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    • 2004
  • Reheating furnace is an essential facility of a rod mill plant where a billet is heated to the required rolling temperature so that it can be milled to produce wire. Sometimes, it is also necessary to control a transient billet temperature pattern according to the material characteristics to prevent a wire from breaking. Though it is very important objective to obtain a correct information of a billet temperature during furnace operation. Consequently, a billet temperature profile must be estimated. In this paper, a billet heat transfer model based on FEM (Finite Element Method) with spatially distributed emission factors is proposed and a measurement is also carried out for two different furnace operation conditions. Finally, the difference between the model outputs and the measurements is minimized by using the new optimization algorithm named uDEAS(Univariate Dynamic Encoding Algorithm for Searches) with multi-step tuning strategy. Hence, the information of billet temperatures can be obtained by using proposed model on various furnace operation conditions.

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A Study on the Mechanical Behavior of Welded Parts in Thick Plate during Post Welding Heat Treatment (厚板熔接部의 應力除去 熱處理時의 力學的 擧動에 關한 硏究)

  • 방한서
    • Journal of Welding and Joining
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    • v.11 no.4
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    • pp.103-111
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    • 1993
  • Recently, several high-tensile steels(e.g. 80kg and above, $2^{1/4}Cr$-1Mo)having good quality to high temperature and pressure-resistance are widely used to construct petroleum-plant and pressure vessel of heat or nuclear-power plant. However, in the steels, reheating crack at grain boundaries of the heat affected zone(HAZ) occures during post welding heat treatment(PWHT)to remove welding residual stress. In order to study theoretically the characteristics of reheating crack created by PWHT, the computer program of three-dimensional thermal-elasto-plasto-creep analysis based on finite element method are developed, and then the mechanical behavior(history of creep strain accumulation and stress relaxation, etc)of welded join in thick plate during PWTH is clarified by the numerical results.

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An Estimation of a Billet Temperature during Reheating Furnace Operation

  • Jang, Yu-Jin;Kim, Sang-Woo
    • International Journal of Control, Automation, and Systems
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    • v.5 no.1
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    • pp.43-50
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    • 2007
  • Reheating furnace is an essential facility of a rod mill plant where a billet is heated to the required rolling temperature so that it can be milled to produce wire. Although it is very important to obtain information on billet temperatures, it is not feasible during furnace operation. Consequently, a billet temperature profile should be estimated. Moreover, this estimation should be done within an appropriate time interval for an on-line application. In this paper, a billet heat transfer model based on 2D FEM(Finite Element Method) with spatially distributed emission factors is proposed for an on-line billet temperature estimation and also a measurement is carried out for two extremely different furnace operation patterns. Finally, the difference between the model outputs and the measurements is minimized by using a new optimization algorithm named uDEAS(Univariate Dynamic Encoding Algorithm for Searches) with multi-step tuning strategy. The obtained emission factors are applied to a simulation for the data which are not used in the model tuning for validation.