• 제목/요약/키워드: Holding time

검색결과 1,043건 처리시간 0.032초

Thixoforming을 위한 Al-7%Si-0.3%Mg 합금의 유도 가열 조건이 구상화 조직에 미치는 영향 (Effect of Induction Heating Conditions on Globular Microstructure of Al-7%Si-0.3%Mg Alloy for Thixoforming)

  • 정홍규;강충길
    • 한국주조공학회지
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    • 제18권5호
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    • pp.450-461
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    • 1998
  • The optimal reheating conditions to apply the thixoforging and semi-solid die casting process were investigated by changing the reheating time, the holding time, the reheating temperatures, the capacity of the induction heating system, and the adiabatic material size. In the case of solid fraction fs=50% (for semi-solid die casting), the microstructure of SSM (specimen size:$d76{\times}l90$) at the condition of the first elevating time of 4 min, holding time of 1 min and holding temperature of $350^{\circ}C$, the second elevating time of 3 min, holding time of 3 min and holding temperature of $575^{\circ}C$, the third elevating time of 1 min, holding time of 2 min and holding temperature of $584^{\circ}C$, capacity of Q=8.398KW is obtained with globular microstructure and finest. In addition, in the case of solid fraction fs=55% (for thixoforging), the SSM (specimen size:$d76{\times}l90$) at the condition of the first elevating time of 4 min, holding time of 1 min and holding temperature of $350^{\circ}C$, the second elevating time of 3 min, holding time of 3 min and holding temperature of $570^{\circ}C$, the third elevating time of 1 min, holding time of 2 min and holding temperature of $576^{\circ}C$, capacity of Q=12.04KW is obtained with the finest globular microstructure. We saw that the most important factor in a three-step reheating process is the final holding time.

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산업체 급식소에서 제공되는 음식의 조리후 보관방법에 따른 품질평가 (A Study on the Quality Control for the Holding Method of Food Served by an Industry Foodservice Establishment)

  • 김혜영;고성희
    • 한국식품조리과학회지
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    • 제12권2호
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    • pp.129-137
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    • 1996
  • The purpose of this study was that to estimate the microbial and sensory quality by the method and time of holding in the step of holding of Cow's Knee Broth, Stir-Fry Pork and Cooked Cuttlefish that were provide at the industry foodservice establishment, then to suggest safer feeding by the reasonable holding method. The results are as follows: Cow's Knee Broth: holding at room temperature was shown that the number of mi- crobiology by passage of the holding time was higer than the case of holding at steam table, but it was lower after reheating it. As a result of sensory test, it was exellent to holding at steam table and to reheat after holding room temperature within four hours and six hours each. Stir-Fry Pork: as a result of microbial analysis, in the case of holding at the steam table microbes increased safer two hours, but after four and six hours they little reduced. In the case of holding at room temperature the number of microbes increased according to the passage of time. As a result of sensory analysis, its taste of room temperature holding was fine until four and six hours each. Cooked Cuttlefish: as a microbial analysis, it was shown that the amount of total plate counts of room temperature holding ten times as high as the latter after six hours. As the result of sensory analysis, the cold holding was better until six hours and the room temperature holding was fine just until two hours. As a result of food poisoning bacteria, it was negative in every test in sample against Salmonella, Staphylococcus aureus, Vibrio parahaemolyticus.

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반용융 단조에서 가압유지 시간에 의한 미세조직의 특성 (Microstructural Characteristics by Compression Holding Time in Semi-Solid Forging)

  • 최재찬;박형진;이병목
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 고액공존금속의 성형기술 심포지엄
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    • pp.174-182
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    • 1997
  • The technology of Semi-Solid Forging (SSF) has been actively developed to fabricate near-net-shape products using light and hardly formable materials. Generally, the SSF process is composed of slug heating, forming, compression -holding and ejecting step. After forming step in SSF, the slug is compressed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. The compression holding time that can affect microstructural characteristics and shape of products is important to make decision, where it is necessary to find overall heat transfer coefficient properly which has large effect on heat transfer between slug and die. This paper presents the procedure to predict compression holding time of obtaining the final shaped part with information of temperature and solid fraction for a cylindrical slug at compression holding step in closed-die compression process using heat transfer analysis considering latent heat by means of finite element method. The influence of the predicted compression holding time on microstructural characteristics of products is finally investigated by experiment.

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알루미늄소재의 재가열 공정에서 구상화의 크기가 기계적 성질에 미치는 영향 (The Effect of globule size on the Mechanical Properties in Reheating Process of Aluminium Alloys)

  • 박상문;강충길
    • 소성∙가공
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    • 제11권2호
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    • pp.155-164
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    • 2002
  • One of the important steps on semi-solid forming Is the reheating process of raw materials to the semi-solid state. This Process is not only necessary to achieve the required SSM billet state, but also to contro1 the microstructure of the billet. In reheating process, the globule size is determined by the holding time of last heating stage. Therefore, some experiments to investigate the relationship between the mechanical properties and the holding time in the last heating stage was performed. The alloys used in this experiment were 357, 319 and A390 alloys. The experiments of reheating were performed by using an Induction heating system with the capacity of 50kw. This paper shows the evolution of the microstructure according to the holding time of last reheating stage. Furthermore, to evaluate the effect of globule size controlled by holding time in last heating stage uniaxial tension test was performed. The strain-stress curves were plotted according to the holding time.

Thixoforging 공정을 위한 알루미늄 재료의 유도 가열 (Induction Heating of Aluminum Alloys for Thixoforging)

  • 정홍규;강충길
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1998년도 춘계학술대회논문집
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    • pp.107-112
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    • 1998
  • The semi-solid materials(SSMs) fabricated under electric-magnetic stirring condition are necessary to be applicated in the thixoforging process. The optimal reheating conditions to thixoforging process were investigated with changing the reheating time, holding time, reheating temperatures, capacity, and adiabatic material size. In the case of solid fraction fs=50%, the microstructure of SSM (specimen size:d76X 190) at the condition of the first reheating time 4min, holding time lrnin and reheating temperature 350%, the second reheating time 3min, holding time 3min and reheating temperature 575C, the thlrd reheating time lmin, holding time 2min and reheating temperature 584'C, capacity Q=8.398KW, and adiabatic material size 53mm is obtained with globular microstructure and finest.

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금속 인서트 사출 성형품의 수축 현상에 관한 연구 (A Study of Shrinkage Phenomena on Injection modeled Pa Metal Insert)

  • 김영수
    • 한국자동차공학회논문집
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    • 제7권9호
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    • pp.112-118
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    • 1999
  • Shrinkage behavior was investigated to obtain more accurate dimensions of injected molding parts for free and restricted shrinkage conditions. various parameters for metal inserted injection process, such as thickness of resin, holding pressure and time, mo이 temperature and restriction condition of mold, were considered for the analysis of shrinkage phenomena. For numerical analysis, MOLDFLOW software was used to find the deterministic parameters of filling time, temperature, pressure and holding time. Also , experimental shrinkage effects were measured through actual injection molding process and the resin thickness was under controlled as 3 mm , 5 mm, and 7mm for the shapes of plastic gear made of Polymide(PA) and Polyxymethlene(POM). The main parameters of these injection processes were found to be holding pressure, holding time and mold temperature in the case of metal inserted molding.

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Moldflow를 이용한 드럼세탁기 케이스의 사출성형공정에 관한 연구 (A study on the Injection Molding Process of the Case of Drum Type Washer using Moldflow)

  • 박철우
    • Journal of Advanced Marine Engineering and Technology
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    • 제33권1호
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    • pp.90-96
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    • 2009
  • Injection molding process is one of the most important methods to produce plastic parts with high efficiency and low cost. Today, injection molded parts have been increased dramatically the demand for high strength and quality applications. This report investigates that the optimum injection molding condition for minimum of shrinkage. Molding shrinkage is occurred by several reasons such as thermal shrinkage, a hardening process and compressibility. This report concentrate on shrinkage by a hardening process. As Change a holding pressure and holding time, checked deflections of X, Y, Z directions by shrinkage based on same condition. In conclusion, it was found that holding pressure is stronger and holding time is longer, the deflection by shrinkage is smaller because injection molding needs enough time for cooling and high density. The FEM Simulation CAE tool. Moldflow, is used for the analysis of injection molding process.

육계의 계류 시간에 따른 닭고기의 육색, PSE 발생 및 외관 특성 (Effect of Holding Time of Broiler at Slaughter House on Color, PSE, Appearance of Chicken Meat)

  • 채현석;유영모;정석근;함준상;안종남;장애라;유효순
    • 한국가금학회지
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    • 제35권2호
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    • pp.177-182
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    • 2008
  • 본 연구는 육계를 도계장에 도착한 후 수송 차량위에서 $1{\sim}2$시간, $7{\sim}8$시간, $14{\sim}15$시간 동안 계류시키면서 일반 도계장에서 사용하는 방법으로 도체를 처리하고, 통닭 및 부분육의 품질을 조사하였다. 계류 시간에 따른 통닭의 품질은 계류 시간이 짧은 $1{\sim}2$시간 처리구에서 계류 시간이 긴 $14{\sim}15$시간 처리구보다 $1^+$ 등급 출현율이 14% 정도 많이 나타났고, 특히 부분육에서 가슴육의 $1^+$ 등급 출현율이 계류 $1{\sim}2$시간 처리구에서 15% 정도 높게 나타났다. 가슴육의 PSE 출현율이 도계장내에서 육계가 수송 트럭위에서 장시간 계류함에 따라 높게 나타났다. 도체의 pH 변화는 짧은 $1{\sim}2$시간 계류보다 $7{\sim}8$시간 계류에서 보다 낮은 pH를 나타냈으나, 계류 시간이 $14{\sim}15$시간으로 장기화될 때 다시 $1{\sim}2$시간 계류와 비슷한 값을 나타냈다. 육색에서 명도는 $1{\sim}2$시간 계류 보다 $7{\sim}8$시간 계류에서 보다 낮은 명도 값을 나타내었다. 계류 시간이 $14{\sim}15$시간으로 증가함에 따라 근육 및 표피에서 다시 상승하는 경향을 나타냈다. 적색도 값은 계류 시간에 따라 큰 차이가 없었으나, 황색도 값에서는 짧은 $1{\sim}2$시간 계류에 비하여 $7{\sim}8$시간, $14{\sim}15$시간 계류에서 더 낮은 황색도 값을 나타내었다. 육색에 대해 전체적 고찰하였을 경우, 계류 $7{\sim}8$시간에서 육색 변화가 비교적 낮게 나타났다. 결과적으로 장시간 계류하는 것은 전체적으로 닭고기 품질을 저하시키는 큰 요인으로 작용하였다.

반용융 압출을 위한 AA7075 합금의 조직제어 (Microstructural Control of AA7075 Alloy for Thixoextrusion)

  • 윤영옥;김영직;김세광;조형호
    • 한국주조공학회지
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    • 제25권6호
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    • pp.249-253
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    • 2005
  • The present study focuses on 7075 aluminum wrought alloy to investigate the potential industrial applications of thixoextrusion process. The microstructural evolution of 7075 aluminum wrought alloy for thixoextrusion has been investigated as a function of isothermal holding temperature and time in the partially remelted semisolid state. The results showed that the liquid fraction increased with increasing isothermal holding temperature and time while the average grain size was inversely proportional to isothermal holding temperature and time up to 5min. However, there was no big change of liquid fraction and average grain size with respect to isothermal holding temperature and time. The important fact that the liquid fraction and average grain size were almost uniform after 5 min holding time is considered very useful for thixoextrusion in terms of process control.

가변 지속시간을 갖는 이벤트 기반 원격제어 (Event Based Tele-Operation with Variable Holding Time)

  • 박준영;박장현
    • 한국정밀공학회지
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    • 제19권12호
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    • pp.70-77
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    • 2002
  • Necessity of the tole-operation has been increased in many fields. Since the Internet is inexpensive and available all over the world, it is a strong candidate for the transmission media of the tole-operation. However, the Internet has random time delays that may cause instability in the system especially if the tole -operation is bilateral. In the past few years many attempts have been made to overcome the random time delay, So far, they are still insufficient in terms of performance. The ‘Variable holding time’ is introduced to improve the performance of the ‘Event based tole-operation’ which controls a system with a non-time action reference. By holding each event for proper time, the system can quickly respond and be stabilized. The proper holding time should be selected based on the characteristics of the task that the system performs. The factors that reflect those characteristics are investigated. The fuzzy logic is employed to obtain the proper holding time for each event while the tole-operation system is in operation. The experimental results presented in this paper verify effectiveness of the proposed method.