• 제목/요약/키워드: near-net shape

검색결과 94건 처리시간 0.212초

티타늄디스크 근사정형 열간단조시 금형속도의 최적화 (Die-Speed Optimization in Titanium-Disk Near-Net Shape Hot-Forging)

  • 박종진
    • 대한기계학회논문집
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    • v.19 no.4
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    • pp.896-907
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    • 1995
  • Titanium 6242(.alpha. + .betha.) alloy has a good strength/weight ratio and is used for aircraft components such as engine disks and compressor blades. When this material is forged at an elevated temperature, the process parameters should be carefully controlled because the process window of this material is quite narrow. In the present investigation, a rigid-thermoviscoplastic finite element method is used to predict the deformation behavior and temperature/strain distributions in an engine disk during near-net shape hot forging. The purpose of the investigation is to obtain a proper ram speed profile, assuming the hydraulic press used in the forging is capable of varying ram speed during loading. In result, it was found that the ram speed at constant strain-rate of 0.5/sec shows a sound deformation behavior, a relatively uniform deformation and a good temperature distribution. This information is also valuable in predicting resulting microstructures in the disk.

온간 성형 하에서 Al 합금 분말의 정밀정형에 대한 유한요소해석 (A Finite Element Analysis for Near-net-shape Forming of Al6061 Powder under Warm Pressing)

  • 김기태;양훈철;김종광
    • 대한기계학회:학술대회논문집
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    • pp.507-512
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    • 2003
  • A finite element analysis for near-net-shape forming of Al6061 powder was performed under warm pressing. The advantages of warm compaction by rubber isostatic pressing were discussed to obtain parts with better density distributions. To simulate densification and deformed shape of a powder compact during warm pressing, the elastoplastic constitutive equation based on yield function of Shima-Oyane was implemented into a finite element program(ABAQUS). The hyperelastic constitutive equation based on the Ogden strain energy potential was employed to analyze nonlinear elastic response of rubber. Finite element results were compared with experimental data for Al6061 powder compacts under warm pressing.

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Upper Bound Analysis for Near-net Shape Forging of a Crown Gear Form

  • Lee, Seung-Dong;Kim, Won-Il;Kim, Yohng-Jo
    • International Journal of Precision Engineering and Manufacturing
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    • v.1 no.2
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    • pp.94-104
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    • 2000
  • A kinematically admissible velocity field for near-net shape forging of a crown gear form is proposed. This takes into account the profiled shape of the teeth chosen by approximating these kinematically as radially straight taper teeth, (rectangular and trapezoidal teeth). The upper bound to the forging load, the relative forging pressure and the deformed configurations, with both the initially solid circular cylindrical and hollow billets, are predicted using the velocity field at varying incremental punch movements considering differing frictional factors. These and other results are given and commented upon.

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냉간 조합압축과 상압소결에 의한 세라믹 분말의 정밀정형과 유한요소해석 (Near-Net-Shape Forming and Finite Element Analysis for Ceramic Powder Under Cold Combination Pressing and Pressureless Sintering)

  • 김홍기;이형만;김기태
    • 대한기계학회논문집A
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    • v.24 no.2
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    • pp.526-534
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    • 2000
  • Near-net-shape forming of zirconia powder was investigated under the combination of cold die and isostatic pressing and pressureless sintering. A novel combination pressing technique, i.e., die com paction under cold isostatic pressing, allowed to produce a complex shaped ceramic powder compact with the controlled dimensions and relatively uniform density distributions. The constitutive models proposed by Kim and co-workers for densification of ceramic powder under cold compaction and high temperature were implemented into a finite element program (ABAQUS). Experimental data for relative density distributions and deformations of zirconia powder compacts produced by cold combination pressing and pressureless sintering were compared with finite element results. Finite element results agreed well with experimental data.

온간 성형 하에서 A1 합금 분말의 정밀정형에 대한 유한요소해석 (A Finite Element Analysis for Near-net-shape Forming of A16061 Powder under Warm Pressing)

  • 김종광;양훈철;김기태
    • 대한기계학회논문집A
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    • v.27 no.11
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    • pp.1897-1906
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    • 2003
  • A finite element analysis for near-net-shape forming of A16061 powder was performed under warm rubber isostatic pressing and warm die pressing. The advantages of warm compaction by rubber isostatic pressing were discussed to obtain a part with better density distributions. The shape of rubber mold was designed by determining a cavity shape that provides a desired shape of the final powder compact. To simulate densification and deformed shape of a powder compact during pressing, the elastoplastic constitutive equation based on yield function of Shima-Oyane was implemented into a finite element program(ABAQUS). The hyperelastic constitutive equation based on the Ogden strain energy Potential was employed to analyze nonlinear elastic response of rubber. Finite element results were compared with experimental data for Al6061 powder compacts under warm die pressing and warm isostatic pressing.

가압소결과 열간 등가압소결에 의한 세라믹 분말의 정형 성형 (Near-net-shape forming of ceramic powder under hot pressing and hot isostatic pressing)

  • 권영삼;김기태
    • 대한기계학회논문집A
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    • v.21 no.1
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    • pp.73-82
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    • 1997
  • High temperature densification behaviors of alumina powder compacts were investigated under hot pressing and hot isostatic pressing. An alumina part of valve-head shape was fabricated under hot pressing and its forming process was simulated by finite element calculation. an alumina powder compact encapsulated by a stainless steel container was also densified under hot isostatic pressing. Inhomogeneous deformations during hot isostatic pressing due to the canning effect were observed experimentally and predicted by finite element analysis.

열간 배압 성형 기술을 이용한 Al-Si합금 스크롤의 정형 제조 기술 (Hot Precision Forging with a Back-pressure of Al-Si Alloy for Scroll Type Compressor Parts)

  • 이영선;이정환;이상용;박영도;이운섭
    • 소성가공
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    • v.9 no.1
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    • pp.52-58
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    • 2000
  • Hot precision forging with a back pressure was investigated for manufacturing of compressor parts made of Al-Si alloy. Disk-shaped blank made of Al-Si alloy was hot forged, and ribs were formed by loading back pressure on their top. The influence of the back pressure and die temperature on forgeability and properties of parts made of Al-Si alloy were examined. Using the F.E.M. simulation, we found the optimum vallue of back-pressure. The prototypes of scroll parts were forged into the near-net shape and satisfied the required properties.

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자유단조공정에서 기공폐쇄 예측을 위한 유한요소해석 (FEM Analysis for the Prediction of Void Closure On the Open Die Forging Process)

  • 민규영;임성주;최호준;최석우;박용복
    • 한국소성가공학회:학술대회논문집
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    • pp.71-74
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    • 2008
  • In order to resolve the problems which appear after the clean large ingot production process, the impurities which are involved in the steel smelting process should be removed by developing cleaner materials. Through the rationalization of cogging process that is the first forging process of large ingot the quality is to be improved. For the sake of the optimization of an open die forging process and the improvement of the subject matter frequency ratio, a hazard precise die forging process must be developed and a Near Net Shape Forming accomplished. As a result, energy can be reduced by minimizing an after control process. In order to produce large axes and other forming parts, processing techniques are to be developed. In this context, this paper is a study about a reduction ratio, dies width ratio and rotary angles, the amount of overlap, and intends to analysis cogging processes, utilizing Deform-3D cogging module

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펄스자장을 이용한 고이방화 Nd-Fe-B자석의 종축자장성형방법

  • 김동환;장동열;김승호;김상면;장태석
    • 한국자기학회:학술대회 개요집
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    • pp.34-35
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    • 2003
  • 고에너지적 Nd-Fe-B계 소결자석 제조를 위한 펄스자장 성형시, 금형 및 다양한 성형조건이 자석의 이방화율 향상에 미치는 영향에 대하여 조사하였다. 일반적으로 butterfly, disk or coin 형태의 자석을 제조하는 방법으로는, 종축자장성형법(Axial Die Press, ADP)을 이용하여 최종제품의 near-net shape으로 성형 및 소결하는 방법과, 횡축자장성형법(Transverse Die Press, TDP)을 이용하여 blick or cylinder 형태로 제조한 후 여러 단계의 가공공정을 거쳐 최종제품으로 제조하는 방법이 적용되고 있다. 그러나, ADP의 경우 분말의 자장정렬 후 성형단계에서 성형밀도가 증가함에 따라 배향의 틀어짐 현상이 증가하므로 이방화율 향상의 한계가 있어 (BH)$_{MAX}$+iHc=54 이상의 자석은 제조되기 어렵고, TDP의 경우 고이방화 자석의 제조가 가능하나 복잡한 형상의 제품을 직접 성형할 수 없어 성형/소결 후 복잡한 가공공정을 거쳐야 하므로 재료의 손실뿐만 아니라 고가의 가공비용이 소요되므로 경제적인 문제점을 갖게 된다. 반면에, 펄스자장 종축성형방법(PDP)은 3T~5T의 펄스자장을 이용하여 분말의 정렬 및 성형을 동시에 수행함으로써 TDP보다 향상된 배향율이 얻어질 수 있으며, ADP으로만 실현 가능한 복잡한 형성의 자석을 near-net shape으로 제조가 가능한 잇점이 있다.다.

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