• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.441-446
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• 2001

This paper presents the thermal characteristics analysis of a high-speed HMC spindle system with angular contact ball bearings, built-in motor, oil-jet lubrication method, oil jacket cooling method, and so on. The spindle system is composed of the main spindle and sub-spindle which are mechanically connected by a flexible coupling. The spindles are supported by two front and rear bearings, and the built-in motor is located between the front and rear bearings of the sub-spindle. The thermal analysis model of spindle system 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 material of bearing ball, spindle speed and coolant temperature.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.139-146
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• 2006

The spindle system with a built-in motor can be used to simplify the structure of machine tools, to improve the machining flexibility of machine tools, and to perform the high speed machining. For more quantitative analysis of a built-in motor's dynamic characteristics, that of tile mass and stillness effects are considered. And the drawbar in the spindle can be in various condition according to supporting stiffness between drawbar and shaft. Therefore, in this paper following items are performed and analyzed : 1. Modal characteristics of the spindle. 2. Analysis of rotor's mass and stiffness effects. 3. Modal characteristics of the spindle including drawbar, rotor and tool. The results show enough stiff supports must be provided between shaft and drawbar to prevent occurring drawbar vibration lower than the natural frequency of 1st bending mode of the spindle, and considering the mass and stiffness of built-in motor's rotor is important thing to derive more accurate results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.1
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• pp.43-49
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• 2007

Multi-function and miniaturization of the medical equipment and tele-communication systems need small and high precision machined parts. For the economic machining of the small size workpiece it should be machined by small and high precision machine tools with high speed machining. The belt type driving system in turning lathe has a limitation of spindle speeds because of the vibrations from driving mechanism, built-in type of driving mechanism is used to reduce the vibration. However, the main spindle of the built-in motor is connected directly to the motor, so the heat generation of the motor and bearing makes bad influence of the accuracy of machine tools. In this study, the analysis of heat generation from motor and bearings supporting main spindle and experiment were carried out. The results of theoretical simulation of temperature and deformation of the main spindle are good agreement with those of measured.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.3
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• pp.261-267
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• 2009

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. Therefore, it is important to recognize the effect of unbalance mass. This paper presents analysis of dynamic behavior of a high speed spindle with a built-in motor. The spindle is supported by the angular contact ball bearings and the rotor is fixed at the middle of spindle. The spindle used in CNC automatic lathe has been investigated using combined methodologies of finite elements and transfer matrices. The Houbolt method is used for the integration of the system equations and the dynamic behavior of spindle is obtained considering unbalance mass of rotor. Results show that increasing rotational speed of spindle magnifies the whirl responses of spindle seriously. Also the whirl responses of spindle are affected by the other factors such as unbalance mass and bearing stiffness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1021-1026
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• 2000

The thermal characteristics of high-speed air spindle system with built-in motor are studied. Experiment and finite element method analysis obtain temperature rise and temperature distribution of housing. For the analysis three-dimensional model is built and temperature rise and distribution in thermal steady state are computed for each rotational frequency. Generally. It is said that the heat generation of air bearing is negligible. But it is certain that the heat generation of air bearing can not be negligible especially in high-speed conditions Frequency response test for air spindle system is executed. In case that the heat generation of air spindle system is high, natural frequency of the system becomes lower when it reaches thermal steady-state and it means that the stiffness of air hearing becomes smaller due to the change of bearing clearance. It is shown that the temperature rise of all spindle system causes thermal expansion md induces the variation of hearing clearance. In consequence the st illness of air bearing becomes smaller.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.51-55
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• 2003

In this paper, the authors propose a new high performance Built-in Type spindle motor drive using vector-controlled technique at 15,000 r/min. Control method is changed by variation of motor speed in a conventional Built-in type spindle drive. In the drive system to be presented, the conventional vector control is used in the low-speed range, and the vector control without encoder is used in the high-speed range. Furthermore, in order to drive the motor from 0 to 15,000 rpm smoothly, the vector control with encoder in the low-speed range (from 0 to 8,000 rpm) is utilized and the vector control without encoder in the high-speed range (from 8,000 to 15,000 rpm) is utilized. This paper describes problem of control method in conventional spindle drive and proposes control method as variation of motor speed

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.03a
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• pp.9-16
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• 1995

The thermal deformation of machine tool spindle influences the performance of the manufacturing systems for precision products. In this research thermal analysis of a high speed machine tool spindle with the rolling bearing and the built-in motor is carried out using Finite Difference Method. The thermal boundary conditions describing the hear generation in the bearing and built-in motor are considered in the simulation. And various convective boundary conditions are assumed with the empirical formula in the references. From the simulation results the characteristics of each element affecting the dynamic thermal behaviour of the machine tool spindle systems have been clarified. This model can be well applied to the future development of the high speed spindle systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.184-185
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• 2008

Modal analysis is an important and essential process in design of a high speed machining center. Generally, modal analysis of a built-in spindle system has not taken the work piece's shape and dimension into consideration. Since small and long work pieces influence greatly the natural frequency of the entire system, the high speed spindle system which continuously makes small machine parts by long work pieces for improvement of machining time has to consider the machining work pieces. Therefore frequency characteristics of the spindle system with long work pieces are studied in this paper.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.59-64
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• 1998

In this study, a motor-integrated high-speed spindle system with $\psi$65mm $\times$ 25,000rpm is developed by introducing the oil-jet lubrication method, ceramic angular contact ball bearings, a built-in motor and so on. And oil-jet lubrication experiments fur evaluating the system performance are performed under various operation conditions. Especially, in order to establish the oillet lubrication conditions related to the development of a high-speed spindle system, the effects of oil supply rate and rotational spindle speed are investigated on the temperature rise, temperature distribution, motor current and so on.

• 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.