• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.25-28
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• 2002

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.56-64
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• 2002

Machine tools are engineered to give high dimensional accuracy in machining operation. However, errors due to thermal effects degrade dimensional accuracy of machine tools considerably, and many machine tools are equipped with thermal error compensation function. In general, thermal errors can be generated in the angular directions as well as linear directions. Among them, thermal errors in the angular directions contribute a large amount of error components in the presence of offset distance as in the case of Abbe error. Because most of thermal error compensation function is based on a good correlation between temperature change and thermal deformation, angular thermal deformation is often to be the most difficult hurdle for enhancing compensation accuracy. In this regard, this paper investigates the effect of thermal bending to total thermal error and gives how to deal with thermally induced bending effects in thermal error compensation.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.886-893
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• 2011

To increase the reliability and positional accuracy of a machine tool, a novel capacitive displacement sensor having a cylindrical shape is presented to measure the axial displacement of a machine tool spindle. Characteristics of the sensor were analyzed by numerical simulation. The sensor was built into a specific machine tool spindle and its performance was experimentally investigated. The accuracy of a thermal error compensation system of a machine tool can be enhanced greatly using proposed sensor.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.7
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• pp.595-600
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• 2016

An orbital grinding system uses a special motion to machine crankshafts in ships. When a crankshaft is operated, eccentric pins rotate and a grinding wheel moves in order to grind the pins. Thermal error caused by heat generated in the grinding process decreases the quality of the final product. In this study, the thermal error of an orbital grinding system caused by heat generation was investigated in order to predict the extent of thermal error that can occur during the grinding process. Since the machine position changes during orbital grinding, the pin part is divided into 30 degree intervals and heat is generated. Total thermal error was measured by summing the thermal errors associated with the pin and the grinding wheel. Total thermal error was found to reach a maximum at 60 degrees and a minimum at 210 degrees because of the shape of the crankshaft.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.754-761
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• 2013

Thermal displacement is an important issue in machine tool systems. During the last several decades, thermal error compensation technology has significantly reduced thermal distortion error; this success has been attributed to the development of a precise, robust thermal error model. A major advantage of using the thermal error model is instant compensation for the control variables during the modeling process. However, successful application of thermal error modeling requires correct determination of the temperature sensor placement. In this paper, a procedure for predicting thermal-mode-based thermal error is introduced. Based on this thermal analysis, temperature sensors were positioned for multiple heat-source models. The performance of the sensors based on thermal-mode error analysis, was compared with conventional methods through simulation and experiments, for the case of a slide table in a transient state. Our results show that for predicting thermal error the proposed thermal model is more accurate than the conventional model.