• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.375-379
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• 1997

Thermal drift of the machine tool spindle due to temperature increase dominates the major source of the machine tool error. To compensate the thermal errors, software based error correction methods could be implemented. In th~s case, we need model to map the relationship between temperature and thermal distortion. Traditionally, two or three different methods have been trled: step increase of spindle speed, constant, random. The latter two methods are described in the document of ISOlDIS230-3. In this research, three different methods were verified through the experiments from the viewpoint of compensation of thermal distortion. Constant spindle speed turned out good enough for monitoring the behavior of the thermal drift and modeling the relationship between temperature and thermal distortion.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.154-162
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• 1997

A real time error compensation system was developed to improve the quasistatic volumetric accuracy of a machining center by using sensing, metrology, modeling, and computer control techniques. Including thermal errors, 32 error components are formulated in the time-space domain. Fifteen thermal sensors are used to characterize the temperature field of the machine. A compensation controller based on the IBM/PC has been linked with a CNC controller to compensate for machine errors in real time. The maximum linear displacement error in 4 body diagonals were reduced from 140 ${\mu}m$ to 34.5${\mu}m$ with this compensation system, and the spindle thermal drift in space was reduced from 147.3 ${\mu}m$ to 16.8 ${\mu}m$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.1023-1027
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• 2000

In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to analyze the thermal characteristics under several operating conditions, experiments performed with the touch probe unit and five gap sensors on the vertical and horizontal machining centers.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.453-457
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• 2001

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric and thermal errors of the machine tools. In this study, the compensation device is manufactured in order to compensate thermal error of machine tools under the real-time. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to compensate thermal characteristics under several operating conditions, experiments performed with five gap sensors and manufactured compensation device on the horizontal machining center.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.449-453
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• 2000

In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to analyze the thermal characteristics under several operating conditions, experiments performed with the touch probe unit and five gap sensors on the vertical and horizontal machining centers.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.16-23
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• 2004

Thermally induced errors of machine tools have been recognized as one of the most important issues in precision machining. This is probably the most formidable obstacle to obtain high level of machining accuracy. To this regard, the experimental compensation methodologies such as software-based method or origin shift of machine tool axes have been suggested. In this research, to cope with thermal deformation, a model based correction was carried out with the function of an external machine coordinate shift. Models with multi-linear regression or neural network were investigated to selected a good one for thermal compensation. Consequently, multi-linear regression model combined with origin shift was verified good enough form the machining of dot matrices of plate with ball end milling.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.214-219
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• 2001

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. In this study, the compensation device and temperature-based algorithm have been presented in order to compensate thermal error of machine tools under the real-time. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to compensate thermal characteristics under several operating conditions, experiments performed with five gap sensors and manufactured compensation device on the horizontal machining center.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.111-117
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models the thermal errors for error analysis and develops an on-the-machine measurement system by which the volumetric errors are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments show that the developed system provides a high measuring accuracy, with repeatability of $\pm$2$\mu\textrm{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be also improved by using the developed measurement system when the spherical ball artifact is mounted on a modular fixture.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.120-128
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments, performed with the developed measurement system, show that the system provides a high measuring accuracy, with repeatability of $\pm$2${\mu}{\textrm}{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be improved by using the developed measurement system when the spherical ball artifact is mounted on the modular fixture.