• 한국정밀공학회지
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• 제14권2호
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• pp.102-112
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• 1997

This paper describes the method that can construct kinematically admissible velocity fields for forging of gear-like components which have tooth shape around the cylinder. The kinematically admissible velo- city fields for the various gear-like components, involute spur gear, trapezoidal spline, square spline, ser- ration and trochoidal gear, were constructed by pilling up the velocity components according to the shape of tooth and billet. The billets, of hollow and solid, were Al 2218 and 2024. To verify the method, the analyses and experiments were carried out and compared with each other. For analyses, the half pitches of com- ponents were divided into several deformation regions based on their tooth profile. A neutral surface was used to represent the inner flow of material during forging. Its location varied with the energy optimazation and its contour varied with the number of teeth. In experiment, the contour of material filling up the tooth zone is hyperbolic curve caused by the frictional drag on the interface of die-wall/workpiece but, in the analysis, it is an arc which retains the same contour during all forging operation.

• 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.

• 한국안전학회지
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• 제7권4호
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• pp.85-94
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• 1992

This paper, discribes analysis of theree - dimensional extrusion with the use of dual stream functions, By this method admissible velocity fields for the extrusion of three- dimensional flow was newly derived kinematically. For square section the extrusion pressure was calculated by numerical solution program which was based on the upper bound analysis. The relationship between relative extrusion pressure and reduction of area, relative die length and constant friction factors were successfully calculated which was newly developed in this study. The results could be applied to design extrusion die.

• 한국산업융합학회 논문집
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• 제2권2호
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• pp.187-194
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• 1999

Closed-die forging of spline was analysed using the upper bound elemental technique, Two different forging methods, denoted here as side extrusion-forging and upset forging, were proposed, The kinematically admissible velocity fields for each of the forging methods, which could express trapezoidal, rectangular and serration tooth forms, were presented. Upper bounds to forging loads and deformed configurations were predicted using the velocity fields. Theoretical results were compared with experimental ones. Experiments with lead were carried out at room temperature where grease was used as a lubricant. The present investigation revealed that analytical forging loads were reduced by using the side extrusion-forging but the upset forging could improve configuration of the final forged splines.

• 한국정밀공학회지
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• 제15권2호
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• pp.90-98
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• 1998

Forging of internal involute gears with alloy steel has been analyzed by means of upper bound method. Kinematically admissible velocity fields for forging of internal gear were proposed. It was assumed that the shape of free flow surface during forging operation is a straight line perpendicular to the plane of symmetry. Using the suggested velocity fields, forging loads and relative pressures were calculated by numerical method. Consequently forging die should be successfully designed without fracture or failure during forging operation. Experiments were carried out with the designed die and SCM415 alloy steel as billet material. The calculated loads were compared with experimental one and they are in good agreement with experimental inspections. As a result, the calculated solutions would be useful to predict the loads and the designed die is suitable for forging of internal involute spur gear with alloy steel. The forged gear is measured to be KS 4 class and its class should be improved by subsequent working such as shaving after forging operation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.67-67
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• 2003

자동차, 항공기, 산업기계, 운반기계, 철도차량, 공작기계 등 거의 모든 산업부문에서 사용되는 베벨기어의 냉간단조 공정 및 금형 설계를 위한 해석을 수행하였다. 소성가공에 의해 생산된 베벨기어는 기계적 성질이 우수하여 동력 전달장치의 수명연장 및 신뢰성, 소형화 등을 달성할 수 있으며 생산 원가 절감의 효과가 크기 때문에 냉간 단조의 공정설계는 매우 중요하다. 베벨기어의 단조에 대한 상계해석 결과는 금형 설계 시 프레스에 필요한 단조하중을 예측할 수 있으므로 프레스의 최적성형과 안전한 금형 설계를 도모할 수 있다. 따라서 본 연구에서는 베벨기어의 냉간 단조시의 내부 동적 가용속도 장을 제시하였고 단조하중, 금속유동 등을 계산하였다. 또한 강소성 유한요소해석을 동시에 수행하여 제시한 동적 가용속도장의 적절성을 비교 검토하였다. 본 연구의 결과는 베벨기어의 적절한 냉간 단조 성형공정 및 공정설계를 위한 기초자료로 활용될 수 있을 것이다.

• 한국기계가공학회지
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• 제19권9호
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• pp.15-23
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• 2020

Spline is a machine component using transmits rotating energy with grooves on internal of boss and external periphery of shaft. Internal spline is generally produced by machining process. However, to reduce manufacturing cost and save time, plastic deformation process such as backward extrusion is gradually adapted for spline production. In plastic deformation process, forming load, stress on tools and flow flaws should be taken into account to have sound products. For this purpose, kinematically admissible velocity fields for Upper Bound Method in backward extrusion of internal spline has been suggested, then forming load and relative pressure have been calculated. Internal spline forming experiments have been con-ucted under hydraulic press and the calculated forming load well predicts the load of experiment.