• Title/Summary/Keyword: near-net shape

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Development of Aerospace Components Forming Technology using Superplasticity and Diffusion Bonding Characteristic (초소성 및 확산접합을 이용한 우주항공 부품 성형기술 개발)

  • Lee, Ho-Sung;Yoon, Jong-Hoon;Yi, Yeong-Moo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.8 no.3
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    • pp.51-55
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    • 2005
  • In this paper, a near net shape technology using superplasticity and diffusion bonding characteristics was presented for application to various components of aircraft and missiles. Due to these special characteristics of some aerospace alloys, it is possible to produce complex components to shape very near final dimension with enhanced design freedom, reduced material usage, and overall saving of weight and cost. The high pressure vessel for a space launcher was fabricated with Ti-6Al-4V alloy by superplastic forming and diffusion bonding process and the failure characteristics are compared with conventionally fabricated vessel spin formed and TIG welded. The structural integrity of the superplastic forming and diffusion bonding process was successfully demonstrated.

Influence of the Morphology and the Particle Size on the Processing of Bronze 90/10 Powders by Metal Injection Moulding (MIM)

  • Contreras, Jose M.;Jimenez-Morales, Antonia;Torralba, Jose M.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.503-504
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    • 2006
  • The MIM technology is an alternative process for fabricating near net shape components that usually uses gas atomised powders with small size $(<\;20\;{\mu}m)$ and spherical shape. In this work, the possibility of changing partially or totally spherical powder by an irregular and/or coarse one that is cheaper than the former was investigated. In this way, different bronze 90/10 components were fabricated by mixing three different types of powder, gas and water atomised with different particle sizes, in order to evaluate how the particle shape and size affect the MIM process.

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Compacting Press의 CNC화

  • Sano, Kazumi
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.6-8
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    • 1995
  • Among powder metallurgy products, complex shaped parts are difficult to be produced. Even i9f it shall be compacted until pet shape, the parts are easily apt to crack. thus it causes inferior productivity.It is present condition that net ahaped parts are obtained by adding after treatment. Clutch hub, pulley, representative partawifh upper 2 steps, tower 3 steps parts are corresponded to the above case. In recent years. muired parts are get to be thinner and thinner, and therefore extremely high compacting techniaues are required. Definition of most preferable com~actingp arts are I) Uniform density 2) Non crack and 3) Realization of net shape or near net shape productlon. For the above purpose, YOSHIZUKA baa developed n now oreas applying hydraulic servo control system.

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Process variables and die life for cold forging (냉간단조용 금형 수명에 미치는 공정 변수의 영향)

  • Lee Y. S.;Choi S. T.;Kwon Y. N.;Rhyim Y. M.;Lee J. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.215-218
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    • 2005
  • For the production of cold forged parts with near-net-shape attributes, the quality of the tool system is responsible for an essential portion of costs fer the finished components. Therefore, a tool lift is one of the important issues on cold forging industry. There are many complicated variables related with tool life, such as material, heat-treatment, coating, lubricant, process design. In this study, heat-treatment of tool material and lubricant are investigated to improve the tool life. Deep cryogenic treatment of tool steel is very efficient to improve the wear resistance due to the fine carbide. And, friction factor of lubricants for cold forging are measured by the ring compression test. Zinc-Phosphate and $MoS_2$ lubricant is effective to sustain the friction factor under 0.1.

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Yield and Compression Behavior of Semi-Solid Material by Upper Bound Method (상계법에 의한 반융용 재료의 항복과 압축거동)

  • 최재찬;박형진;박준홍
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.195-198
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    • 1995
  • In Semi-Solid Forging, it is necessary to control the forming variables accurately in order to make near-net-shape products. Generally, the defects of products may occur due to liquid segregation which can be caused by the degree of deformation and condition of friction in Semi-Solid Forging, where the segregation is to be predicted by flow analysis. This paper presents the feasibility of theoretical analysis model using the new yield function which is proposed by Doraivelu et al. to the flow analysis of the semi-solid dendritic Sn-15%Pb alloys instead of adopting the yield criterion of Shima & Oyane which is used by Charreyron and usefulness of the adopted yield function. The distribution of the liquid fraction at various strains in radial direction and the influence of friction are estimated by Upper Bound Method.

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Fabrication of a Part by Heating and Forming in the Semi-solid State of the SKH51 Material (SKH51의 반응고 상태에서의 가열 및 성형에 의한 부품 제조)

  • Lee, Sang Yong
    • Journal of the Korean Society for Heat Treatment
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    • v.27 no.3
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    • pp.127-132
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    • 2014
  • The semi-solid metal forming process has been applied to realize a near-net shape fabrication of a high speed tool steel. A complicatedly shaped part out of SKH51 was successfully manufactured by introducing pertinent materials, tooling and processing conditions. A SKH51 billet with globular grains was heated at temperatures between 1300 and $1350^{\circ}C$ using high frequency induction heater to get semi-solid microstructure before high rate injection of mushy metal into a die cavity for the forming process. It was necessary to control the preheating of dies between 300 and $400^{\circ}C$ to maintain the homogeneous microstructure during the semi-solid metal forming process. Significant defects such as pores, high fraction of liquid fraction and segregation could be removed from the part by using air vents.

Advancement in Powder Metallurgy of Aluminum Alloys

  • Takeda, Yoshinobu
    • Journal of Korean Powder Metallurgy Institute
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    • v.5 no.4
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    • pp.340-344
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    • 1998
  • Along with the growth of conventional ferrous powder metallurgy (PM), PM of aluminum alloys has been intensively investigated in Japan. Although rapidly solidified aluminum alloy powder was first used in the USA,/sup 1)/ commercialization for consumer market was first realized in Japan./sup 2)/ In order to achieve the viable cost-performance including Near Net Shape (NNS) formability, we developed three processes, powder extrusion, powder forging and sintering. The new powder extrusion process does not use either capsulation or vacuum degassing. The new powder forging does not need lateral flow. The new sintering process does not use liquid phase. The performance achieved by the processes is outstanding mechanical or physical properties that has potential to substitute cast iron, steel, titanium Metal Matrix Composite (MMC) or Ingot Metallurgy (IM) aluminum alloys. Cooperation with customers, powder suppliers and research associations contributed to the advancement of PM aluminum alloys in Japan.

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The Effect of Gate Shape for Semi-Solid Forging Die on the Filling Limitation (반용융 단조금형의 Gate 형상이 성형성에 미치는 영향)

  • Son Y. I.;Kang C. G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.178-184
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    • 2000
  • To obtain high quality component with thixoforming process, it is important that the homegeneous distribution of solid particles without liquid segregation. In closed-die semi-solid forging process, liquid segregation is strongly affected by injection velocity than any other process variables because the material has to travel relatively long distance to fill the cavity through a narrow gate before solidification begins. The optimal injection velocity and die temperature were investigated to fabricate near-net-shape compressor component called Al frame.

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Processing of Metallic Materials by Gas Atomized Spray Forming (고성형성 합금 제조를 위한 가스 분무성형 공정)

  • Baik, K. H.;Seok, H. K.
    • Transactions of Materials Processing
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    • v.14 no.7
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    • pp.587-594
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    • 2005
  • 분무성형공정은 급냉응고 및 결정입자 제어에 따른 고품위 소재 개발의 장점과 함께 고밀도 near-net-shape 제품의 제조가 가능한 합금제조기술이다 분무성형체의 미세조직은 적층표면에 도달하는 액적들의 평균 열용량, 즉 고상분율에 의하여 결정되며, 이는 액적의 비행과정에서의 분사가스-액적간의 열전달과 적층표면에서의 열유입과 열유출 속도에 영향을 받는다. 실제 다양한 공정변수들이 복합적으로 미세조직 형성과정에 영향을 미치지만, 균일한 미세조직을 얻기 위하여서는 적층표면에서의 온도와 고상분율을 항상 일정하게 제어하여야만 한다 즉, 적층표면 온도를 분무 성형공정중에 지속적으로 측정하여 이를 공정 제어 시스템에 feedback하여 원하는 적층표면온도를 유지하도록 공정변수를 제어하는 것이 필수적이다. 분무성형에 제조된 성형체는 합금원소의 편석이 없고 미세한 등방성의 결정립으로 이루어진 특징적인 미세조직을 나타낸다 이와 같은 미세조직으로 인하여 분무성형체는 우수한 성형성과 기계가공성을 나타내며, 또한 분무성형-후속가공된 최종 제품은 잉곳주조에 의하여 제조된 것과 비교하여 크게 향상된 기계적 성질을 가진다.

The Effects of Fabrication Conditions on Forging Limitation and Mechanical Property in Semi-Solid Forming Process (반용융 단조공정에 있어서 제조 조건이 성형성과 기계적 성질에 미치는 영향)

  • 정경득;강충길
    • Transactions of Materials Processing
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    • v.10 no.3
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    • pp.214-222
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    • 2001
  • The homogeneous distribution of solid region without liquid segregation is important in terms of high quality component during thixoforming process. In closed die semi-solid forging process, liquid segregation is strongly affected by injection velocity than solid fraction because the material has to travel relatively long distance to fill the cavity through a narrow gate. The designed die by computer simulation data was used to thixoforging process. The thixoforming velocity to prediction the liquid segregation had been determined with strain rate associated with multistage velocity control during compression test of semi-solid material. The optimal forging velocity and die temperature were investigated to produce the near-net-shape compressor component. The mechanical properties of thixoformed component were tested with various die and material temperatures before and after heat treatment.

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