• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.63-67
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• 1992

본 논문은 프레스나 해머로 생산되는 리브/웨브 형태를 갖는 축대칭 부품에 대한 블로커설계 자동화시스템의 개발에 관하여 설명한 다. 플레시를 갖는 밀폐형단조 공정에서 블로커 형상의 설계는 매우 중요하다. 일반적으로 단조공정에서 부품의 형상은 대부분 3차 원 형상이다. 그러나 복잡한 3차원 형상의 부품을 그대로 고려하여 설계한다는 것은 어려움이 많고 실용적이지도 못하다. 따라서 블로커를 설계할 때 부품을 단면으로 도려함으로서 설계작업을 단순화시킬 수 있다. 본 논문에서는 축대칭 형태의 부품만을 고려하였다. 한 부품단면은 리브나 웨브와 같은 부분단면들로 분할할 수 있으며, 이 부분단면들에 대하여 설계규칙과 데이타베이스를 적용함으로서 블로커형상을 설계할 수 있다. 부품단면의 형상을 분할하여 시스템 내에 인식시키기 위하여 단면을 도면요소표현, 좌표 및 반경표현 그리고 속성표현으로 나타냈으며 여기에 단면의 도면요소표현은 부품의 체적, 단면적, 원주길이 및 반단면의 질량중심을 계산하는데 쉽게 이용될 수 있다. 그리고 좌표 및 반경표현은 경사각, 코너반경과 필렛반경을 수정하는데 그리고 속성표현은 리브와 웨브의 형태와 특성을 고려하여 블로커를 설계하는데 이용될 수 있다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1211-1219
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• 1995

An upper bound elemental technique (UBET) program has been developed to analyze forging load, die-cavity filling and effective strain distribution for flash and flashless forgings. The simulation for flash and flashless forgings are applied axisy mmetric and plane-strain closed-die forging with rib-web type cavity. Inverse triangular and inverse trapezoidal elements are used to analyze flashless forging. The analysis is described for merit of flashless precision forging. Experiments have been carried out with pure plasticine billets at room temperature. Theoretical predictions of the forging load and the flow pattern are in good agreement with experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.5
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• pp.134-142
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• 1994

An upper bound elemental technique (UBET) is applied to predict variations of neutral plane and optimal position of the initial billet for rib-wep shaped ring forging. In the analysis, the neutral plane position and velocity fields are determined by minimizing the total power consump- tion with respect to chosen parameters. The degree of die-cavity filling by initial billet-position and the variations of neutral plane by friction condition are investigated. Experiments have been carried out with pure plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agrement with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.337-344
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• 1989

The upper bound elemental technique (UBET) is used to simulate the bulk flow characteristics in axisymmetric closed die forging process. Internal flow inside the cavity is predicted using a kinematically admissible velocity field that minimizes the rate of energy consumption. Application of the technique includes an assessment of the formation of flash and of degree of filling in rib-web type cavity using billets with various aspect rations. The technique considering bulging effect is performed in an incremental manner. The results of simulation show how it can be used for the prediction of forging load, metal flow, and free surface profile. The experiments are carried out with plasticine. There are good agreements in forging load and material flow in cavity between the simulation and experiment. The developed program using UBET can be effectively applied to the various forging problems.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.1
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• pp.7-15
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• 1998

An upper bound elemental technique(UBET) program has been developed to analyze forging load, die-cavity filling and effective strain distribution for flash and flashless forgings. The program consists of forward and backward tracing processes. In the forward program, flash, die filling and forging load are predicted. In backward tracing process, the optimum dimensions of initial billet in conventional forging are determined from the final-shape data based on flash design. And the analysis is described for merit of flashless precision forging. Experiments are carried out with pure plasticine billets at room temperature. The theoretical predictions of forging load and flow pattern are in good agreement with the experimental results.