• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.11
• /
• pp.2723-2729
• /
• 1993

Moire principles are applied to the measurement of the spindle radial error motion. As opposed to conventional techniques, no master cylinder or ball is needed in the measurement so that the offset and out-of-roundness errors of the master can be inherently eliminated. Two periodic circular gratings are used, one is made on the spindle and the other is held stationary on the reference frame. When the two gratings are seen superimposed during spindle rotation, an interference fringe pattern is observed from which the information on the eccentricity between the two gratings can be extracted with high precision. The optical design and fringe analysis techniques of a prototype measurement system are described in detail with exemplary measurement results.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.1
• /
• pp.78-84
• /
• 2014

The rotation of a spindle unit must be accurate for high-quality machining and to improve the quality of the machine tools.Therefore, the proper measurement of the rotation accuracy and ensuring a proper analysis are very important. Separate processes are necessary because spindle errors and roundness errors associated with the test balls can both factor into the measured rotation error values. We used three methods to discern test ball errors and analyzed which could be deemed as the most proper technique in a test of the rotation accuracy of the main spindle of a machine tool.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.643-644
• /
• 2008

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1352-1357
• /
• 2004

Thermal error compensation has been developed for CNC (Computer Numerical Control) machining center with moving heat sources. The thermal error in CNC machining center has an effect on machining accuracy more than the geometric error does. Thus, temperature distributions of a spindle unit have been analyzed numerically by a Finite Differential Method and experimentally by an infrared (IR) camera in this study. A multiple variable method has been derived to estimate the thermal deformation of the machine origin stably and effectively after measuring deformation and temperature data. The experimental results for a vertical machining center have shown that the thermal errors of the machine origins were reduced more than 30% by the developed method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.1005-1008
• /
• 1995

The spindle is a very important part of machine tool. The evaluation of spindle motion is required for improving the performance of machine tools. The evaluation tools have been developed for precison spindle by the reversal technique, and 3D error map motion of spindle is proposed. This technique makes us understand the total movement of spindle more easily. The proposed technique has been successfully applied to practical machine tools, giving high potentials for the spindle performance measurement.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.5 s.176
• /
• pp.1343-1351
• /
• 2000

Thermally induced errors have been significant factors affecting the machine tool accuracy. In this paper, the spindle thermal error has been focused, where the 5 degree of freedom thermal error components are considered. An effective measurement system has been devised for the 5 DOF thermal errors, consisting of gap sensors and thermocouples around the micro-computer interfaced environment. Several thermal error modeling techniques are also implemented for the thermal error prediction: multiple linear regression, neural network and system identification methods, etc. The performance of the thermal error modeling techniques is evaluated and compared, giving the system identification method as the optimum model having the least deviation. The developed system for the thermal error measurement and modeling was practically applied to a CNC machining center, and the spindle thermal errors were effectively compensated around the micro computer-machine tool interfaced networks. The machine tool accuracy was improved about 4-5 times typically.

• Tribology and Lubricants
• /
• v.27 no.1
• /
• pp.13-18
• /
• 2011

The ultra-precision products which recently experienced high in demands had included the large areas of most updated technologies, for example, the semiconductor, the computer, the aerospace, the media information, the precision machining. For early 21st century, it was expected that the ultra-precision technologies would be distributed more throughout the market and required securing more nation-wise advancements. Furthermore, there seemed to be increasing in demand of the single crystal diamond tool which was capable of the ultra-precision machining for parts requiring a high degree of complicated details which were more than just simple wrapping and policing. Moreover, the highest degree of precision is currently at 50 nm for some precision parts but not in all. The machining system and technology should be at very high performed level in order to accomplish this degree of the ultra-precision.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.23 no.4
• /
• pp.368-373
• /
• 2014

This paper presents the dynamic modeling and analysis results for a spindle supported by angular contact ball bearings (ACBBs) subjected to angular misalignment. Although ACBBs are widely used in spindle systems, their characteristics in regard to angular misalignment have rarely been investigated. A simulation program was developed to calculate the dynamic characteristics of a simple spindle model that is supported by angular contact ball bearings subjected to angular misalignment. Angular misalignment is shown to introduce anisotropy into the angular contact ball bearings and then split the natural frequencies in spindles. Simulations were also performed to show the possibility of evaluating bearing misalignment using natural frequency measurements.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.922-925
• /
• 2000

Generally, the machining accuracy in ball end milling directly depends on the rotational accuracy affected by the spindle speeds. The effects of spindle speeds for rotational accuracy in the high speed regions are more dominant than those in the low speed regions. This paper will investigate effects that the Increased speed affects on the rotational error according to the increase of a rotational speed and machining characteristics of the high speed ball-end milling in various rotational speeds and on various materials by using the high speed air-bearing spindle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.579-585
• /
• 2003

This paper investigates the whirling, tilting and flying motion of a HDD spindle system supported by FDB experimentally. Experimental setup is built to measure the flying, whirling and tilting motion of the HDD spindle system, and three capacitance probes fixed on the xyz-micrometers measure the displacement of a HDD spindle system in the xyz-directions. This research shows that the tilting and whirling motion is mostly dependent on the centrifugal force and the gyroscopic moment due to the unbalanced mass of a HDD spindle. It also shows that the rotating HDD spindle starts to float to the equilibrium position in the z-direction until the weight of the rotating spindle is equal to the supporting pressure generated in the upper and lower thrust bearing.