• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.74-79
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• 2003

When workability at the a certain bulk deformation process is defined as the maximum plastic deformation capability that the workpiece can sustain without causing any cracks or fracture, the workability is dependent on the microstructure, initial workpiece shape, stress state developed during the deformation process, strain rata and presence of the interfacial friction between workpiece and tool. For a review purpose, the workability definition and test methods are summarized depending on the applied stress state at bulk deformation process in Table 1 at the text. In this study, the cold workabilities of as-cast A16061 bulk material have been measured and comparatively analyzed at the primary tensile stress state by using tensile specimens, the primary compressive stress state by using cylindrical specimens, and the forming limit diagram by ductile fracture.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.123-127
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• 1999

This paper suggests the establishment of high-accuracy and high-efficiency machining method of scroll shape workpiece by using the feed control method. The cutting paths for machining the inside and outside surfaces of the scroll-shape workpiece are calculated, and the calculation method of the cutting chip areas based on the coordinate of the base circle is shown. A feed control method is proposed for a constant cutting area and cutting force. By machining test of scroll shape workpiece, The machined accuracy of wrap, tool wear, and surface roughness are evaluated. By this method, Reduction of the machining time and large increase of the efficiency can be expected.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.3-8
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• 2007

A machining system that generates accurate relative motions between the tool and workpiece is required to realize ultra precise machining or measurements. Accuracy improvements for each element of the machine are also required. This paper proposes a machining system that uses a compensation device for the six-degree-of-freedom (6-DOF) motion error between the tool and workpiece. The compensation device eliminates elastic and thermal errors of the joints and links due to temperature fluctuations and external forces. A hexapod parallel kinematics mechanism installed between the tool spindle and surface plate is passively actuated by a conventional machine. Then the parallel mechanism measures the 6-DOF motions. We describe the conception and fundamentals of the system and test a passively extensible strut with a compensation device for the joint errors.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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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.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.107-112
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• 1997

In this study of made Autmation system is moving linear transfer system for mainly forming of small electronic unit and other at press line. This system for loading and unloading a workpiece has been installed in a press in order to load and unload a workpiece from a press die. Main Control method be used PLC. It took data of input from each sensor and send signal of output to actuator by sequence program also, we try to Characteristics test of this system has good condition when operating with raser measurmant.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06b
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• pp.8-18
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• 1998

The effect of press warm forming in cylindrical deep drawing of stainless-aluminum clad sheet metals are examined . The temperature of die and blank holder is varied from room temperature to 20$0^{\circ}C$, while the punch is kept cooled during test to increase the fracture strength of workpiece on the punch corner area. Test materials chosen for experiments are STS304-Al050-STS304, STS304-A1050-STS430-, STS304 and Al050 metals and teflon film as a lubricant is used on both sides of a workpiece. The limit drawing ration as well as quality of drawn cups (distribution of thickness and hardness)are investigated and discussed.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.627-634
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• 2014

Machine tool vibration is well known for reducing machining accuracy. Because vibration response of a linear structure generally depends on its transfer function if the magnitude of excitation were kept constant, this study introduces a RET(Random Excitation Test) based on FRF method to evaluate stiffness of a prototype HDMTL(Heavy-Duty Multi-Tasking Lathe) for large crankshaft of marine engine. Firstly, two force loops of the lathe and corresponding structural loops were identified:1) workpiece - spindle - head stock - main bed, 2) workpiece - tool post - carriage bed. Secondly, compliances of each structural loop were measured respectively using RET with a hydraulic exciter and then converted into stiffness. Finally, the measured stiffness was compared with that obtained previously by FEM analysis. As the result, both measured and computed stiffness were closely in agreement with each other. And the prototype HDMTL has evidently sufficient rigidity above ordinary heavy-duty lathes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.136-143
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• 2002

Warm draw die technique which is one of the new forming technologies to improve formability of sheet metal is applied to the cylindrical and square cup drawing of stainless-aluminum clad sheets. In experiments the temperature of die and blank holder is varied from room temperature to $180^{\circ}C$, while the punch is cooled by circulation of coolant to increase the fracture strength of workpiece on the punch comer area. Test materials chosen for experiments are STS304-A1050-STS304 clad sheets. Teflon film as a lubricant is used on both sides of a workpiece. The limit drawing ratio and relative drawing depth as well as quality of drawn cups(distribution of thickness)are investigated and validity of warm drawing process is also discussed. No separation between each laminated material after drawing occurred through inspection by microscope as well as application of penetrant remover and bond strength test. Therefore, warm forming technique was confirmed to give better results in deep drawing of stainless clad sheet metal.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.1
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• pp.63-70
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• 1988

Laser cutting system uses a gas jet to remove the molten or varpozed material from the workpiece. The quality of the laser cut can be strongly influenced by the gas flow charac- teristics formed through the nozzle. Laser cutting experiments were carried out for SS41 and SUS 304 to investigate the relationship between cut quality and cutting pressure. The cutting speed, nozzle pressure and nozzle to workpiece distance were also considered. The cut specimens were inspected by various manners such as dross observation, surface roughness test and kerf width measurement. Based on the data of pressure measurement on workpiece and the results of cut surface inspection, the influence of the considered cutting conditions on cut quality could be evaluated. The results of this study will be valuable in planning the optimal laser cutting process and in designing the laser cutting nozzle.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.117-120
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• 2003

Warm deep drawing which is one of the new forming technologies to improve formability of sheet metal is applied to the cylindrical cup drawing of Mg-alloy sheet metal. In experiments the temperature of die and blank holder is varied from room temperature to $300^{\circ}C$, while the punch is cooled by circulation of coolant to increase the fracture strength of workpiece on the punch corner area. Test material chosen for experiments is AZ31 magnesium sheet metal. Teflon film as a lubricant is used on both sides of a workpiece. The limit drawing ratio as well as thickness distributions of drawn cups are investigated and validity of warm deep drawing process is also discussed.