• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.3
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• pp.51-57
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• 2006

Hydro-mechanical punching was developed for preventing burr formation. Circular hole punching and Finite element method(FEM) analysis were conducted to investigate shearing characteristics of this process in comparison with conventional and mechanical counter punching. In this process hydrostatic pressing with appropriate medium was utilized instead of counter punch, which resulted in the delay of the point that the fracture is initiated and clean shearing surface was obtained. FEM analysis was utilized to find out optimum processing parameters and shearing mechanism for burr-free hole punching.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.6
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• pp.15-21
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• 1997

This study is performed for investigating the effects of stripping and counter punching forces on shearing characteristics in fine blanking of T-shaped products, such as camber, burr-height and dimensional accuracy, etc by experiments. Conventional hydraulic press is used for experiments so that both the stripping force and counter punching force can be arbitrarily adjusted by another hydraulic unit connected to the fine blanking die. Specimens are selected as hot rolled steel sheet and carbon steel sheet commonly used in auto- mobile company. Based on the experimental results, both the dimensional accuracy and the burr height are not influenced by the stripping and counter punching forces, wherease the camber height representing dish- shaped deflection is much influenced by them, it can be seen through this study that the finely cut surface of T-shaped blank can be obtained even in conventional hydraulic press if additional equipments and specially designed die are employed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.598-602
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• 1996

This study is performed for investigating the effects of stripping and counter punching force on shearing characteristics in fine blanking, such as camber, burr-height and dimensional accuracy, etc by experiments. Conventional hydraulic press equipped with specially designed hydraulic unit is used for experiments so that both the stripping force and counter punching force are arbitrarily adjusted according to experimental conditions. Two kinds of materials, hot rolled steel sheet(1mm, 3mm) and pure aluminum(1mm, 3mm) are selected in order to examine the influence of strength and thickness of working materials in blanking of T-shaped products. Based on the experimental results of this study, it can be concluded that the finely cut surface of sheared blank can be obtained even in conventional hydraulic press if additional equipments and special dies are employed.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.157-163
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• 1996

This paper is concered on the development of low-cost fine blanking die with two fluid chambers of which the pressure can be controlled by a hydraulic unit and its application to producting circular blanks in a conventional hydraulic press, not in a special triple-action press usually adopte in fine blanking operation. Four important working parameters affecting on the precision accuracy of products such as existence and position of Vee-ring, stripping force and counter punching force are primarily considered for experiments. Finite element analysis by suing ABAQUA software is approxi- mately made for blanking of circular specimen with a flat stripper plate and then compared with experimental measurements. The the theoretical prediction of camber height which represents deflection of a dish-shaped specimen after blanking seems to give a qualitatively good agreement. It is shown through experiments the the camber height decreases with decreasing stripping force and also with increasing counter punching force, but particularly depending on the latter much more than the former.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.52-56
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• 2006

Punching tools like an electrodes are made by milling or etching or EDM. These methods had time consuming, low efficiency and air pollution. So, we have developed a shearing device which counter punching method for burrless cutting of micro wire. Using the straightened SUS304 wire with $200{\mu}m$ diameter, we confirmed the tendency of the shear plane for punch tools. It was impossible to completely remove the bun in the shearing process. In order to minimize the burr size and fine shear plane, we have accomplished the various experiment conditions such as the U-groove, the effect of the counter punch, shear angle and clearance. The results of the experiments show that indentation, slip plane and bent shape were related to the shear angle and clearance.