• 드라이브 ㆍ 컨트롤
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• 제19권4호
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• pp.10-18
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• 2022

Air-drop hammer press and counterblow hammer press are widely used power-drop forging hammersemploying different forging blow mechanisms. It is important and necessary to analyze mechanical vibrations of these two different hammers in their forging processes in order to develop high performance forging hammers. In this study, these two forging hammers were mathematically modelled as mass-spring-damper systems. For these two different types of forging hammers, the forging efficiency and mechanical vibrations due to hammer forging blow were theoretically analyzed and compared. The force transmitted to the ground was also determined and compared. Especially, effects of mass ratio and restitution coefficient on forging efficiency were investigated.

• 한국기계가공학회지
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• 제21권8호
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• pp.43-52
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• 2022

The vibration characteristics of a hammer press are important parameters for machine design and production control. In this study, a counterblow hammer press was mathematically modelled as a mass-spring-damper system in order to analyze its vibration characteristics. The forging efficiency was theoretically derived as a function of the mass ratio, momentum ratio, and the coefficient of restitution And the effects of the mass ratio, momentum ratio and the restitution coefficient on the forging efficiency were also investigated for two particular cases of the unit mass ratio and unit momentum ratio. Additionally, the vibration responses of the counterblow hammer press due to the ram colliding impact were analyzed, and the force transmitted to the foundation through the mounting unit was determined.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.338-341
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• 2009

In this paper, three-dimensional finite element approach to determining the number of blows in hammer forging is presented. Energy efficiency which is a major factor affecting the number of blows in hammer forging is assumed to decrease linearly as die-material contact area increases. The approach is applied to predicting the number of blows in counterblow hammer forging of large crank shaft for medium sized ship engine.

• 대한기계학회논문집
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• 제19권6호
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• pp.1539-1544
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• 1995

Copper blow test to measure the forging capability of 35 ton counterblow hammer and upset of plasticine on the model hammer to investigate the change of the blow efficiency during the forging process have been performed together with finite element analyses of these experiments. The blow efficiency of the hammer has been found to be dependent on the friction and on the contact area between the die and the workpiece. The effects of the volume and the aspect ratio of the billet have not been found. Inferring from the experimental results and Schey's empirical formula on the forging load, we expect that the efficiency also varies with the flow stress of the workpiece material and with the shape complexity of the forging product.