• 제목/요약/키워드: In Mold Grain

검색결과 67건 처리시간 0.024초

AZ91D 합금의 기계적 성질 및 금형충전성에 미치는 결정립 미세화 원소의 영향 (Effects of Grain Refining Elements on the Mechanical Properties and Mold Filling Ability of AZ91D Alloy)

  • 김정민;박준식
    • 한국주조공학회지
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    • 제31권2호
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    • pp.79-82
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    • 2011
  • Various grain refining alloying elements such as Sr, TiB, and Ca were added to AZ91D and their effects on the mechanical properties and mold filling ability were investigated. The average grain sizes of those alloys were significantly reduced by the small amounts of the alloying elements. Ca addition was the most remarkably effective in reducing the grain size, however it was found to deteriorate the mold filling ability and tensile properties. TiB addition was observed to be the most efficient for both grain refinement and mold filling.

쾌속 조형 공정을 이용한 다이캐스팅 제품의 시작 공정 개발 (Development of the Simulated Die Casting Process by using Rapid Prototyping)

  • 김기돈;양동열
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2002년도 금형가공 심포지엄
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    • pp.180-186
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    • 2002
  • The simulated die-casting process in which the traditional plaster casting process is combined with Rapid Prototyping technology is being used to produce Al, Mg, and Zn die-casting prototypes. Unlike in the die-casting process, molten metal in the conventional plaster casting process is fed via a gravity pour into a mold and the mold does not cool as quickly as a die-casting mold. The plaster castings have much larger and grosser grain structure as compared as the die-castings and the thin walls of the plaster mold cavity may not be completely fillet Because of lower mechanical properties induced by the large grain structure and incomplete Idling, the conventional plaster casting process is not suitable for the trial die-casting Process. In this work, an enhanced trial die-casting process has been developed in which molten metal in the plaster mold cavity is vibrated and pressurized simultaneously. Patterns for the casting are made by Rapid Prototyping technologies and then plaster molds, which have runner system, are made using these patterns. Imparted pressurized vibration to molten metal has made grain structure of castings much finer and improved fluidity of the molten metal enough to obtain complete filling at thin walls which can not be filled in the conventional plaster casting process.

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AC2B 알루미늄 주조합금의 응고균열 강도에 미치는 금형 예열온도의 영향 (Effect of Mold Preheat Temperature on Solidification Crack Strength of AC2B Aluminum Alloy)

  • 김헌주
    • 한국주조공학회지
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    • 제34권5호
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    • pp.162-169
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    • 2014
  • The effect of the mold preheat temperature on the solidification crack strength was investigated in AC2B aluminum alloy. A tension type apparatus as part of a solidification crack test which could measure the stress-strain relationship quantitatively was utilized. The evaluation of the solidification crack strength with varying mold preheat temperatures was performed by the test procedure established in this research. When the mold preheat temperatures were $250^{\circ}C$, $150^{\circ}C$ and $50^{\circ}C$, the solidification crack strengths were found to be $7.8Kgf/cm^2$, $12.9Kgf/cm^2$ and $28.6Kgf/cm^2$, respectively. In the same way, when the mold preheat temperatures were $250^{\circ}C$, $150^{\circ}C$ and $50^{\circ}C$, the corresponding temperatures of the failure sites were $610^{\circ}C$, $600^{\circ}C$ and $571^{\circ}C$, and the calculated solid fractions were 14.0%, 29.3% and 50.8% when the specimens failed, respectively. The solidification crack strength increased in proportion to the solid fraction of the failure site. The solidification crack strength obtained in this test is assumed to reflect the effects of metallurgical factors on the thermo-plastic characteristics of a solidifying alloy such as the grain size of the solid, the grain morphology, and the distribution of solid grain.

쾌속조형을 이용한 다이 캐스팅 제품의 시작 공정 설계 및 제작 (Design and Development of the Simulated Die casting Process by using Rapid Prototyping)

  • 김기돈;양동열;정준호;박태권
    • 한국정밀공학회지
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    • 제18권7호
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    • pp.167-173
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    • 2001
  • The simulated die-casting process in which the traditional plaster casting process is combined with Rapid Prototyping technology is being used to produce AI, Mg, and Zn die-casting prototypes. Unlike in the die-casting process, molten metal in the conventional plaster casting process is fed via a gravity pour into a mold and the mold does not cool as quickly as a die-casting mold. The plaster castings have much larger and grosser grain structure as compared with the normal die-castings and the thin walls of the plaster mold cavity may not be completely filled. Because of lower mechanical properties induced by the large grain structure and incomplete filling, the conventional plaster casting process is not suitable for the trial die-casting process to obtain quality prototypes. In this work, an enhanced trial die-casting process has been developed in which molten metal in the plaster mold cavity is vibrated and pressurized simultaneously. Patterns for the casting are made by Rapid Prototyping technologies and then plaster molds, which have a runner system, are made using these patterns. Pressurized vibration to imparted molten metal has made grain structure of castings much finer and improved fluidity of the molten enough to obtain complete filling at thin walls which may not be filled in the conventional plaster casting process..

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알루미늄청동의 합금성분 및 냉각속도에 따른 특성변화에 관한 연구 (A Study on the Change of Properties of Al-bronze Due to Alloy Elements and Cooling Rate.)

  • 정운재;김헌주;김동옥;윤의박
    • 한국주조공학회지
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    • 제8권3호
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    • pp.271-281
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    • 1988
  • Al-bronze has a good mechanical property, corrosion resistance and castability, so being highlighted for the new copper alloy. So, effects of alloy composition and cooling rate in the mechaincal properties and solidification behavior have been investigated. The results obtained are as follows; 1) Change in volume on solidification is larger in metal mold casting than in sand mold casting. And it decreases by the addition of Al. 2) The mechanical property in metal mold casting is superior to the one in sand mold casting, and the inclination is obvious up to 9% Al, after heat-treatment ($885^{\circ}C$, $1.5hrs\;{\rightarrow}\;W\;{\cdot}\;Q\;{\rightarrow}\;540^{\circ}C$, 3hrs) 3) By adding Al, the mechanical property is slightly increased up to 9% Al, Above 9% Al, it is increased rapidly, and is accelerated by adding Fe. 4) Cooling rate and hardness, and grain size and cooling rate are related as follows in the range of $1100^{\circ}C$ to $1200^{\circ}C$ pouring temperature. Grain size(${\mu}m$)=$929.6422{\times}cooling\;rate(^{\circ}C\;/\;sec)^{-0.51537}$ Hardness(BHN)=$765.45713{\times}grain\;size({\mu}m)^{-0.31058}$.

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사형(砂型)의 열전달(熱傳達)에 관(關)한 연구(硏究) (A Study on Heat Transfer in Sand Molds)

  • 이종남;김광배
    • 한국주조공학회지
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    • 제2권1호
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    • pp.2-11
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    • 1982
  • In order to investigate the relationship between the thermal characteristics of the various molds as green sand mold, dry sand mold, $CO_2$ mold and shell mold, and the solidification characteristics of molten metal, the thermal analysis of rarious molds and melt were performed. The structure of Al-Castings was a/so observed. Results obtained in this experiment were as follows : 1) The heating rate of the molds was increased in the order of green sand mold, $CO_2$ mold, dry sand mold and shell mold, On the other hand the solidification time of the melts was shortened in the order of dry sand mold castings, $CO_2$ mold castings, green sand mold castings and shell mold castings. 2) The arrest temperature period in the heating curve of the green sand mold was resulted from the eraporation of moisture contained in mold, which was transfered to the outer side of the mold. 3) The temperature fluctuation of the melt in the shell mold was considered to be resulted from the combution heat of resin contained in the mold. 4) The amounts of heat absorption of the molds were increased in the order of dry sand mold, $CO_2$ mold, green sand mold and shell mold. 5) The higher the solidification rate was, the longer was its shrinkage pipe and the finer its grain size.

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수수 이삭곰팡이 증상에서 분리한 Fusarium속 균의 다양성 및 병원성 (Diversity and Pathogenicity of Fusarium Species Associated with Grain Mold of Sorghum)

  • 최효원;홍성기;이영기;김완규
    • 한국균학회지
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    • 제41권3호
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    • pp.142-148
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    • 2013
  • 국내의 수수재배는 주로 소면적으로 이루어지며, 대부분 식용이나 사료용으로 사용되고 있다. 2007년부터 2009년까지 전국의 수수 재배 포장을 조사한 결과, 이삭에 곰팡이가 발생하는 증상을 다수 관찰하였다. 병징은 매우 다양한데, 심하게 감염된 이삭의 경우 곰팡이가 발생하였고, 부분적으로 감염된 경우에는 수수 종실이 변색되거나 불임립이 형성되었다. 총 90개의 Fusarium균을 분리하였으며, 형태적 배양적 특성 조사에 의한 동정 결과, F. thapsinum이 41개, F. proliferatum이 23개, F. graminearum이 12개 분리되었으며, F. incarnatum과 F. equiseti가 각각 5개, 3개 분리되었다. Elongation factor 1 alpha 유전자의 염기분석을 이용한 계통분석 결과, 대부분이 NCBI GenBank에 등록된 각 유전자와 일치하는 결과를 나타냈다. 분리된 병원균의 병원성 검정 결과, 우점종인 F. thapsinum, F. proliferatum, F. graminearum종이 병원성이 강한 것으로 조사되었다. 이 연구는 Fusarium균에 의해 발생한 수수 이삭곰팡이증상에 대한 첫 번째 보고이다.

AC4C 합금의 기계적 성질에 미치는 주조조건과 열처리의 영향에 관한 연구 (The Effect of Casting Condition and Heat Treatment on the Mechanical Properties of AC4C Alloy Castings)

  • 강효경;천병욱;최창옥
    • 한국주조공학회지
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    • 제13권5호
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    • pp.450-461
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    • 1993
  • AC4C alloy casts in the metallic mold, zircon sand mold, silica sand mold and shell mold with the pouring temperatures of 680, 710 and $740^{\circ}C$ have been investigated. The tensile strength, elongation and hardness of AC4C alloy castings have been influenced by the kind of molds used. The mechanical properties in zircon sand mold castings were greater than those in other sand mold castings, but were inferior to the properties in metallic mold castings. Eutectic Si particle size and DAS were increased in the order of metallic mold, ziron sand mold, silica sand mold and shell mold. Also, they were increased with the increase of pouring temperatures. DAS, eutectic Si particle size and grain size decreased with the increase of mechanical properties as the cooling rate increased. The eutectic Si particle size and DAS of AC4C alloy castings after T6 treatment were decreased in as-cast. The variation of eutectic Si particle size has been effected on the tensile strength, elongation and fractured surface.

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순수 티타늄 주조체의 주형온도에 따른 미세조직 및 기계적 성질 (Microstructures and Mechanical Properties of Pure Titanium Casting Specimens with Mold Temperatures)

  • 차성수;남상용;송영주
    • 대한치과기공학회지
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    • 제32권4호
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    • pp.307-315
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    • 2010
  • Purpose: The purpose of this study was to investigate the change of microstructures and mechanical properties of pure titanium casting specimens as a function of mold temperatures. Methods: The pure titanium castings were fabricated using the centrifugal vacuum casting method with different mold temperatures of $200{\sim}500^{\circ}C$. The resulting castings were characterized by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and vicker,s hardness tester. Results: In case of the mold temperatures over $400^{\circ}C$, the porosity, surface crack and large grain size were observed in resulting castings. Conclusion: In this work, The most suitable mold temperature in casting of pure titanium was $300^{\circ}C$.

주조용 Al-4wt%Mg-0.9wt%Si-0.3wt%Mn-0.15wt%Fe 합금의 결정립 미세화와 주조특성에 미치는 Ti, B, Zr 첨가원소의 영향 (Effect of Ti, B, Zr Elements on Grain Refinement and Castability of Al-4wt%Mg-0.9wt%Si-0.3wt%Mn-0.15wt%Fe Casting Alloy)

  • 김헌주;박수민
    • 한국주조공학회지
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    • 제35권5호
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    • pp.120-127
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    • 2015
  • The effects of Ti, B and Zr on grain refinement and castability were investigated in Al-4wt%Mg-0.9wt%Si-0.3wt%Mn-0.15wt%Fe alloy. Measurement of cooling curve and micro-structure observation were performed to analyze the effects of the addition of minor elements Ti, B and Zr during solidification. The prominence of effect on grain refinement was in increasing order for Ti, Zr and B element. Fine grain size and an increase of the crystallization temperature for ${\alpha}$-Al solution were evident as the amount of addition elements increased in this study. Addition of 0.15wt% Ti was most effective for grain refinement, and the resulting grain size of ${\alpha}$-Al solution for shell mold and steel mold were $72.3{\mu}m$ and $23.5{\mu}m$, respectively. Fluidity and shrinkage tests were perform to evaluate the castability of the alloy. Maximum fluidity length and minimum ratio of micro shrinkage were recorded for 0.15wt% Ti addition due to the effect of the finest grain size.