• 제목/요약/키워드: kinematically-admissible velocity field

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상하면의 마찰이 틀린 비직각주 소재의 3차원 업셋팅에 관한 연구 (A study on the three-dimensional upsetting of non-prismatic blocks considering different frictional conditions at two flat dies)

  • 김종호;류민형;양동열
    • 대한기계학회논문집
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    • 제13권3호
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    • pp.345-352
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    • 1989
  • 본 연구에서는 3차원 변형형상을 갖는 소재에서 상하금형면의 마찰이 다른 경우에, 작각주 소재와 비직각주 소재(non-prismatic block)에 대해서 적용할 수 있는 동적 가용 속도장(kinematically admissible velocity field)을 유도해 내고자 한다.이론계산에 있어서 가공경화를 고려하기 위해 소성변형 영역을 유한개의 요소들로 나누고 이들 각 요소에 대해서 유효변형도, 유효응력을 계산하여 에너지 소비율을 계산하였다.

상계요소법에 의한 클러치 치형의 밀폐단조해석 (Closed-Die Forging Analysis of Clutch Teeth Using An Upper Bound Elemental Technique)

  • 양정호;이상태;김용조
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1996년도 추계학술대회 논문집
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    • pp.134-138
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    • 1996
  • A simple kinematically admissible velocity field for closed-die forging of clutch teeth is analysed which takes account of the profiled teeth chosen kinematically by approximating these as straight taper teeth. The upper bound load and the deformed configurations are predicted by the velocity field at varying punch movements considering differing frictional factors. Experiments were carried out using a model material of plasticine at room temperature where talcum powder was used as a lubricant. The theoretical predictions of the forging load and the relative pressures are found to be in reasonably good agreement with the experimental results.

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중공 원형 소재로부터 다각형 튜브 제품의 평금형 전방 압출에 대한 최종단계의 상계해석 (An Upper-Bound Analysis of the Square-Die Forward Extrusion of Regular Polygonal-Shaped Tubes from hollow-Cylindrical Billets at Final Stage)

  • 김동권;조종래;배원병
    • 한국정밀공학회지
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    • 제12권11호
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    • pp.91-97
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    • 1995
  • In this study, a deformation model for the regular polygonal-shaped tubes from hollow-cylindrical billets is proposed and a kinematically admissible velocity field is obtained from this deformation model. The final stage upper-bound extrusion load and the average extruded length are determined by minimizing the total power consumption with respect to chosen parameters. Experiments have been carried out with hard solder billets at room temperature. The theoretical predictions of the extrusion load are in good agreements with the experimental results and there is generally reasonable agreement in average extruded height between theory and experiment.

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상계해법에 의한 원형빌렛으로부터 타원 단면을 가진제품의 압출가공의 비틀림 해석 (An Upper Bound Analysis for the Twisting Phenomenon of Extrusion of Elliptical Shapes from Round Billet)

  • 김한봉;진인태
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1998년도 춘계학술대회논문집
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    • pp.210-213
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    • 1998
  • A kinematically admissible velocity field is developed for the analysis of twisting of extruded products. The twisting of extruded product is caused by the linearly increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis, the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance and is increased linearly by axial distance from die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product increase with the die twisting angle and the aspect ratio of product and friction condition and reduction area and show that angular velocity increases with the decreases in die length.

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상계해법에 의한 압출가공의 비틀림 해석 (An Upper Bound Analysis for the Twisting Phenomenon of Extrusion)

  • 김한봉;진인태
    • 소성∙가공
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    • 제7권4호
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    • pp.340-346
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    • 1998
  • A kinematically admissible velocity field is developed for the analysis of twisting of the extruded products with elliptical shapes from round billet. The twisting of extruded product is caused by the lin-early increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product in creases with the die twisting angle, the aspect ratio of product the friction condition, the reduction of area, and decreases with the die length.

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평다이를 사용한 편심압출가공에서의 비유동영역의 형상과 굽힘속도분포에 관한 상계해석 (An Upper Bound Analysis of the Shapes of the Dead Metal Zone and the Curving Velocity Distribution in Eccentric Plane Dies Extrusion)

  • 김진훈;진인태
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1998년도 춘계학술대회논문집
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    • pp.250-253
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    • 1998
  • The kinematically admissible velocity field is developed for the shapes of dead metal zone and the curving velocity distribution in the eccentric plane dies extrusion. The shape of dead metal zone is defined as the boundary surface with the maximum friction constant between the deformable zone and the rigid zone. The curving phenomenon in the eccentric plane dies is caused by the eccentricity of plane dies. The axial velocity distribution in the plane dies is divided in to the uniform velocity and the deviated velocity. The deviated velocity is linearly changed with the distance from the center of cross-section of the workpiece. The results show that the curvature of products and the shapes of the dead metal zone are determined by the minimization of the plastic work and that the curvature of the extruded products increases with the eccentricity.

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상계해법에의한 원형빌렛으로부터 S형 단며의 압출가공의 비틀림 해석 (An Upper Bound Analysis for the Twisting Phenomenon of Extrusion of S shape from Round Billet)

  • 진인태
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 춘계학술대회논문집
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    • pp.130-135
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    • 1997
  • A kinematically admissible velocity field is developed for the analysis of twisting of extruded products. The twisting of extruded product is caused by the linearly increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis, the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance and is increased linearly by longitudinal distance from die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product changes with the aspect ratio of product and increases with the decreases in die length and in eccentricity of gravity center of the cross-section of workpiece at die entrance from that of the cross-section at the die exit.

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편심압출굽힘가공법에 의한 사각형 단면을 가진 중공 튜브제품의 U형굽힘가공에 관한 연구 (A Study on the U-bending of Rectangular Hollow Tube by the Eccentric Extrusion and Bending Process)

  • 김진훈;진인태
    • 소성∙가공
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    • 제7권5호
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    • pp.496-504
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    • 1998
  • The eccentric extrusion and bending process for the forming of the curved rectangular hollow tube is newly developed. Generally the bending process of hollow tube is the secondary process followed by the extrusion process of the hollow tube from the round billet. So many defects such as wrinkling and the difference of wall thickness can be happened during the secondary bending process. In order to avoid the defects the new process named as "the eccentric extrusion and bending process" is suggested and applied to the U-bending of rectangular hollow tube. In this paper the kinematically admissible velocity field between the dies surface and the internal plug boundary surface s developed for the curving velocity. By the using of this curving velocity field the curvature of extruded products can be calculated with the parameters such as eccentricity dies length friction constant aspect ratio.

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평다이를 사용한 편심 압출가공에서의 비유동 영역의 형상과 굽힘 속도 분포에 관한 상계해석 (An Upper Bound Analysis of the Shapes of the Dead Metal Zone and the Curving Velocity Distribution in Eccentric Plane Dies Extrusion)

  • 김진훈;진인태
    • 소성∙가공
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    • 제7권2호
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    • pp.177-185
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    • 1998
  • The kinematically admissible veolcity field is developed for the shapes of dead metal zone and the curving velocity distribution in the eccentric plane dies extrusion. The shape of dead metal zone is defined as the boundary surface with the maximum friction constant between the deformable zone and the rigid zone. The curving phenomenon in the eccentric lane dies is caused by the eccentricity of plane dies. The axial velocity distribution in the plane dies is divided in to the uniform velocity and the deviated velocity. The deviated velocity is linearly changed with the distance from the center of cross-section of the workpiece. The results show that the curvature of products and the shapes of the dead metal one are determined by the minimization of the plastic work and that the curvature of the extruded products increase with the eccentricity.

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경사진 돌출부가 있는 비축대칭 복합단조의 상계요소해석 (UBET Analysis of Combined Forging of Non-Axisymmetric Shapes With Inclined Protrusion)

  • 윤정호;양동열
    • 대한기계학회논문집
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    • 제14권1호
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    • pp.1-12
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    • 1990
  • 본 연구에서는 자유단조용 프레서를 이용하여 돌출부가 있는 비대칭 중공형단 조 제품을 생산할 수 있도록 금형장치를 설계.제작하고, Fig.1에서 보는 바와 같이 경 사진 돌출부가 있는 비축대칭 복합단조에 UBET를 적용하여 해석하였다. 단조시편은 원주형태를 가지도록 하였다. 즉 원주형 소재가 요구되는 비축대칭 단조제품으로 변 형되는 과정에서 단조하중, 재료가 돌출부를 충만하도록 하는 유동특성, 재료가 돌출 부로 차들어가는 속도 등에 영향을 주는 인자(예:펀치 직경의 크기, 금형 상하면의 각 도)의 특성을 이론적으로 해석하고 실험으로 확인하였다.