• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.958-968
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• 1994

This paper presents a dynamic analysis of the high-speed spindle system for vertical machining center using finite techniques. The computed natural frequencies are compared with the measured frequencies obtained from experimental modal analysis. The results show that the bending and twisting deformations of the spindle housing dominate in the lowest modes owing to low dynamic stiffness of the housing structure. The design parameters in the analysis are : (a) panel thickness of the housing (b ) height of the housing, and (c) spindle-to-column distance of the housing. Through sensitivity analysis and optimizing simulation considering design constraints, an optimal design of the spindle system has been obtained.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.2
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• pp.37-43
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• 2004

High speed machining is a machining process which cuts materials with the fast movement and rotation of a spindle in a machine tool. It reduces machining time because of the high feed and the high speed of a spindle. In addition it gets rid of post processes for high precision machining. When the high speed machining is applied to especially hardened steel, operators should select the proper parameters of machining. This can produce machining surfaces which is qualified with good surface roughness. This paper presents a method for selecting machining parameters to minimize surface roughness with high speed machining in cutting the hardened steels. Experimental data for surface roughness are collected in a machining shop based on the cutting feed and the spindle rotation. The data fits in hi-cubic polynomial surface of mathematical form. From the model this research minimize the surface roughness to find the optimal values of the feed and the spindle speed. This paper presents a program which automatically generates optimal solutions from the raw data of experiments.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.3
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• pp.149-156
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• 1992

A method for designing high speed spindle is presented in order to enhance the machining accuracy in consideration of vibration characteristics. Experimetal evaluations of the spindle HS 430 as a prototype are made efficiently with the help of bending vibration modes for nonrotational and rotationalstate comparing with the commercial spindle V430. As a result the spindle of HS 430 shows the superior performance than that of V 430.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.06a
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• pp.35-49
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• 2000

Over the past ten years we have wethnessed a revolution in metalcutting in the field of High Speed Machining. As machining speeds continue to increase, particularly spindle RPM, forces created by unbalance in the spindle, cutting tool, and toolholder require close attaention. It has been observed that these forces, if left uncompensated, can results in poor surface finish, loss of tool life, and spindle bearing failure. The sources of this unbalance needs to be identified and elimated in order to create a smooth, vibration free condition and allow the machine tool and its spindle to operate properly.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.671-679
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• 2012

This paper presents an estimation procedure for axial displacement in spindle equipped with angular contact ball bearings due to rotational speed. High-speed spindle-bearing system experiences axial displacement due to thermal expansion and rotational speed-dependent characteristics of angular contact ball bearings. This paper deals with the axial displacement caused by the rotational speed-dependent effects such as centrifugal force and gyroscopic moments. To this end, a bearing dynamic model is established that includes all the static and dynamic properties of angular contact ball bearing. An analytical formula to calculate the axial displacement based on contact angles between ball and races is derived to discuss the physics regarding the axial displacement in spindle. The proposed dynamic model is compared with a reference and a commercial program. Numerical examples are presented to show the effects of centrifugal force and gyroscopic moment on the axial displacement. The proposed model is also validated with an experimental result.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.428-432
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• 2004

The important problem in the high speed spindles is to reduce and minimize the thermal effect by the motor and ball bearings. Thermal characteristics according to the bearing preload and hollow shaft cooling are studied for the test spindle with the oil mist lubrication and high frequency motor. Bearings and motor e main heat generation, and heat generation by ball bearings as a function of load, viscosity and gyroscopic moment effect are considered. Temperature distribution and thermal displacement according to the speed of spindle are measured by thermocouple and gap sensor. The results show that the fitting preload and hollow haft cooling are very effective to minimize the thermal effect by the motor and ball bearings.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.473-474
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• 2008

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.93-98
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• 2003

High speed precision machines have been introduced to the CNC industry in order to improve productivity, shorten the appointed date of delivery and reduce the prime cost. High speed machines have more functions then general machines, and they were proved in performance. The production and sales of the high speed machines have been increased not only in domestic market but also all over the world. Accordingly, machines are faster, there are lots of problems to be solved. One of the most difficult problems is the thermal displacement on the main spindle due to generated heat while the spindle is rotated in high speed. Since the thermal displacement directly effects the quality of the machined parts, utmost efforts to minimize the thermal displacement have to be given from the beginning of designing machines. In practice, variety of methods are attempted and practiced to minimize the thermal displacement such as design of symmetrical frame, adoption of high speed bearings, application of compensation system using non-contact sensor and use of forced circulating lubrication system with oil cooler. Even if these variable methods have been practically used in the industrial field, generated heat has not been Perfectly Prevented lienee, in this paper, the characteristics of thermal displacement were investigated when several kinds of oil were tested for a high speed machine with forced circulating lubrication system within the same atmosphere and under the same conditions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.47-53
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• 2004

High speed precision machines have been introduced to the CNC industry in order to improve productivity, shorten the appointed date of delivery and reduce the prime cost. High speed machines have more functions then general machines, and they were proved in performance. The production and sales of the high speed machines have been increased not only in domestic market but also all over the world. Accordingly, machines are faster, there are lots of problems to be solved. One of the most difficult problems is the thermal displacement on the main spindle due to generated heat while the spindle is rotated in high speed. Since the thermal displacement directly effects the quality of the machined parts, utmost efforts to minimize the thermal displacement have to be given from the beginning of designing machines. In practice, variety of methods are attempted and practiced to minimize the thermal displacement such as design of symmetrical frame, adoption of high speed bearings, application of compensation system using non-contact sensor and use of forced circulating lubrication system with oil cooler. Even if these variable methods have been practically used in the industrial field, generated heat has not been perfectly prevented. Hence, in this paper, the characteristics of thermal displacement were investigated when several kinds of oil were tested for a high speed machine with forced circulating lubrication system within the same atmosphere and under the same conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1016-1020
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• 2000

In this study, a structural characteristics analysis system for motor-integrated high-speed spindle systems, “SpindleX”, is developed based on the Timoshenko theory and the multi-layered finite element method. Since “SpindleX” has the various analysis modules related to static deflection analysis, modal analysis, frequency response analysis, unbalance response analysis and so on, it is useful in performing systematically and quantitatively the design and evaluation processes of spindle system under the windows GUI environment. Also, to enhance the user-friendliness, “SpindleX” possesses the various additional functions such as the DXF file interface for auto-importing the shape and geometric data of spindle system from the DXF file, the bearing database for auto-importing the mechanical properties and geometric data of bearing by the bearing number, and the graphical visualization for certificating the imported and analysed data of spindle system.