• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.221-226
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• 2002

This paper presents the thermal characteristics analysis of a high-speed HMC(horizontal machining center) with spindle speed of 30,000rpm and fried rate of 40m/min. The spindle speed is achieved by introducing angular contact ball bearings, oil-jet lubrication method, oil jacket cooling method, and so on. The spindle system is a motor-separated type composed of the main spindle and sub-spindle which are mechanically connected by the flexible coupling. The spindles are supported by two front and rear bearings, and the built-in motor is located between the front to and rear bearings of the sub-spindle. The thermal analysis model of HMC is constructed by the finite element method, and the thermal characteristics in the design stage are estimated based on temperature distribution and heat flow under the various testing conditions related to spindle speed and feed rate.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.4
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• pp.422-426
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• 2011

The spindle system is very important unit for the product accuracy in machine tools. A spindle system is designed by using the angular contact ceramic ball bearings, built-in motor, oil-air lubrication method and oil jacket cooling method. The static and dynamic analysis and stiffness evaluation of 45,000rpm spindle for machine tool has been investigated. Using a finite element method, we obtained some analyzed a static and dynamic characteristics of a spindle, such as natural frequency, harmonic analysis and we got the value of compliance through it. We evaluated stiffness by taking the inverse this value. A 45,000rpm spindle is successfully developed using the results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.405-406
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• 2012

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.767-772
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• 2011

The thermal deformation of machine tool spindle influences the performance of the manufacturing systems for precision products. According to previous studies, major factors that will affect the stiffness of the spindle include spindle diameter, elasticity of the material, bearing stiffness and bearing span. It is difficult to change spindle diameter or elasticity of the material. but change of bearing position is easy in the given range compared to other factors. In this paper, we will find a solution to minimize thermal deformation through Change the span of the bearing.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.104-110
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• 2012

The spindle with a built-in motor can be used to simplify the structure of machine tool system, while the rotor has unbalance mass inevitably. A high-speed spindle can be very sensitive to rotating mass unbalance which has harmful effect on many machine tools. Therefore, the balancing procedure to reduce vibration in rotating system is certainly needed for all high-speed spindles. So, it was performed with a spindle-bearing system for CNC automatic lathe by using numerical procedure. The spindle is supported by the angular contact ball bearings and the motor rotor is fixed at the middle of spindle. The spindle-bearing system has been investigated using combined methodologies of finite elements and transfer matrices. The balancing was performed through influence coefficient method and the comparison was made by whirl responses between before balancing and after balancing. As a result, balancing of simple spindle model reduced whirl orbit magnitude in case of a completely assembled spindle model.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.691-696
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• 2000

Cooling characteristics of cooling jacket for spindle system with built-in motor are studied. Three dimensional model was selected for the analysis of the helical-type cooling jacket. This model includes the estimation on the amount of heat generation from bearing and built-in motor and the thermal characteristic values such as heat flux on the boundary. The temperature distributions are analyzed and the cooling by Nusselt number and total heat transfer coefficient. Numerical results show that stream-wise cross section area and flow rate are important factors for cooling characteristics of cooling jacket.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.105-111
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• 2012

High speed machining is the core technology that influences the performance of machine tools, and the high speed motor spindle is widely used for the high speed machine tools. The important problem in high speed spindle is to minimize the thermal effect by motor and bearing and frequency effect. This paper presents the thermal characteristic analysis and frequency experiment for a high speed spindle considering the flow rate of cooling oil. A high speed spindle is composed of angular contact ceramic ball bearings, high speed built-in motor, oil cooling jacket and so on. The thermal analyses of high speed spindle need to minimize the thermal effect and maximize the cooling effect and they are carried out under the various cooling conditions. Heat generations of the bearing and the high speed motor are estimated from the theoretical and experimental data. To find out the characteristic of vibration, the high speed spindle is excited in operational range. This result can be applied to the design and manufacture of a high speed tapping spindle.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.47-51
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• 1996

Unsteady-state temperature distributions and thermal deformations of a spindle system are studied in this paper. Three dimensional model is built for analysis, and the amount of heat generation of bearing and the thermal characteristic values including heat transfer coefficient are estimated. Temperature distributions and thermal deformations of a model are analyzed using the finite element method and the termal boundary values. Numerical results are compared with the measured data. The results show that thermal deformations and temperature distributions of a high precision spindle system can be reasonably estimated using the three dimensional model and the finite element method.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.398-403
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• 2004

The demand of high speed machining is increasing because the high speed cutting providers high efficiency of process, short process time, improved metal removal capacity and better surface finish. Active magnetic bearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting. The automatic control concept of magnetic bearing system provides ability of intelligent control of spindle system to increase accuracy and flexibility by means of adaptive vibration control. This paper describes a design and development of a milling spindle system which includes built-in motor with power 5.5㎾ and maximum speed 70,000rpm, HSK-32C tool holer and active magnetic bearing system. Magnetic actuators are designed for satisfying static load condition. The Performances of manufactured spindle system was examined for its static and dynamic stiffness, load capacity, and rotational accuracy. This spindle was run up to 70,000 rpm stably, which is 3.5 million DmN.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.494-499
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• 2003

This paper concerns the static, dynamic and thermal characteristics analysis of a high-speed spindle system for horizontal machining centers with 45mm x50,000rpm. The spindle system is designed based on the angular contact ceramic ball bearings, built-in motor, oil-air lubrication method and oil jacket cooling method. The structural and thermal analysis models of spindle system are constructed by the finite element method. The static and dynamic characteristics are estimated based on the static deformation, modal parameter, mode shape and frequency response function, and the thermal characteristics are estimated based on the temperature rise, temperature distribution and thermal deformation. The analysis results illustrate that the designed spindle system has excellent structural and thermal stabilities