• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.451-454
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• 2003

The Oil Coolers is very important unit for the stable thermal performance in machine tools, semiconductor equipments and high precision measuring systems. To select a proper oil cooler for the temperature control of core unit in a machine, not only cooling ability but also static and dynamic sensitivity of temperature sensors are considered. In this paper, the relationship between cooling ability and inflow oil temperature is identified. The cooling ability is increased with the increase of inflow oil temperature. The oil temperature control errors of a cooler are influenced by mainly sensitivity of temperature sensors and heating velocity in a machine. The validity of error cause analysis for temperature control is proved by real cooling experiments with inflow and outflow temperature sensors.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.4
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• pp.345-351
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• 2015

Machine tools usually consume more energy in cooling systems than in spindle motors. This is largely because circulation pumps in the cooling systems are continuously powered to measure the temperature of spindle motors. In this paper, energy saving algorithms are proposed, which modify this behavior of the circulation pumps in such a way that the circulation pumps run only when it is likely that the information on the temperature is critical to bang-bang control of compressors in cooling systems. A mathematical model is established that explains heat transfer phenomena near the spindle motors. The power consumptions are measured for individual components in a machine tool, and the parameters that appear in the mathematical model are estimated. Computer simulations are performed with the estimated parameters, and the results are compared with the experimental ones. It turns out that a large amount of energy can be saved by using the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.980-984
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• 2002

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design condidering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verified the test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirm approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective method in thermal-appropriate design.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.98-101
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• 2001

Linear motor feature a direct connection to the machine tool, therefore a direct route for heat transfer. The heat dissipation of linear motor machine is affected by the maximum temperature rise of the primary part, coil and the cooling method. To minimize temperature induced dimension changes and decrements of performance, linear motor machine require effective cooling mechanism. To evaluate cooling performance of existing linear motor machine, some experiments about temperature profile are performed using thermocouple recorder. Due to the lack of information about internal structure, only some finite element modeling is prepared and analyzed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.414-419
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• 1997

Linear motor feature a direct connection to the machine tool, therefore a direct route for heat transfer. The heat dissipation of linear motor machine is affected by the maximum temperature rise of the primary part, coil and the cooling method. To minimize temperature induced dimension changes and decrements of performance, linear motor machine require effective cooling mechanism. 1'0 evaluate cooling performance of existing linear motor machine, some experiments about temperature profile are performed and evaluated using thermocouple recorder. Due to the lack of information about internal structure. only some finite element modelling is prepared and analyzed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.73-78
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• 1998

In this paper, we have studied about the thermal expansion of the ball screw used for the CNC machine tools. The hollow ball type is used for the ball screw. We have compared the conventional cooling system and function with the improved cooling system and function which is developed the path providing cooling oil in hollow ball screw. That is the temperature variation and positioning accuracy are analyzed of the ball screw. We have obtained the following results through this experiment. 1) The improved cooling system of the hollow ball screw for CNC machine tools was developed 2) The improved cooling system of the hollow ball screw has a large effectiveness on restraining the thermal expansion of the ball screw. 3) The positioning accuracy of the ball screw was improved about 2~4$\mu$m using temperature -controlled cooling oil.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.71-72
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• 2006

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.266-271
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• 2003

The numerical study was carried out to effectively cool Induction motor applied to a washing machine. The outer rotor made of steel periodically spins up and down. The stator consists of the thin layered iron plates and copper coil. The effective cooling system is necessary to solve the reliability problem caused by the electric losses at the coil and the iron plate. Because the heat transfer rate of the natural convection in partially open space is generally low, thus it is necessary to enhance the heat transfer using rotating perforated plate. The flow phenomena around the motor are very complex due to the motor geometry and the outer rotor motion. The mixed convection takes place due to the slow rotation speed. The three dimensional flow simulation was performed using rotating reference frame technique and Boussinesq approximation but the radiation effect was neglected. It was found that the angle and direction of the cooling blades play an important role in the stator temperature.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.126-133
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• 2008

Linear motors are efficient mechanism that offers high speed and positioning accuracy. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speed and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. This paper presents an investigation into the thermal behavior of linear motors with the objective of deriving the optimum cooling conditions. To reach these goals several experiments were carried out, varying operating and cooling conditions. From the experimental results, this research proposed cooling conditions to improve the thermal characteristics of the linear motors.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.332-336
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• 2000

Cooling characteristics of cooling jacket for spindle system with built-in motor are studied. For the analysis, three dimensional model for the cooling jacket is built by using finite volume method. The three dimensional model includes the estimation on the amount of heat generation of bearing and built-in motor and the thermal characteristic values such as heat flux on the boundary. Numerical results show that flow rate are important factors for cooling characteristics of cooling jacket.