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

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.7 s.172
• /
• pp.146-154
• /
• 2005

Recently, the high-speed and intelligence technology of machine tools are developed for the high efficiency of productivity Under the operating condition from the high-speed of machine tools, the various failure modes can occur in core units of manufacturing system. Therefore it is for the reliability concept of machine tool to be required in a design level. And the above-stated technology must be accommodated in the feeding and spindle subsystem, etc those are the core units of machine tools. In this study, we are developed the test-bed of sliding cover (C-plate) in order to evaluating reliability and estimating failure modes of feeding subsystem under operating conditions. The reliability experiment using the developed test-bed and the additional structural analysis executed on single and double structure. We found out the weak parts of sliding cover and were able to predict a life cycle from the experiment results. In this study, we propose the new C-plate model with double link structure to apply the high-speed machine tool in the fundamental guideline.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.52 no.10
• /
• pp.583-590
• /
• 2003

This paper deals with speed control of DC servo motor using a high gain obserber. It was designed to estimate rotor speed of DC servo motor and it carries out speed control from the feedback of the estimated speed signal. Also, PI controller was used in speed controller. In order to verify the performance of the high gain observer which is proposed in this paper, it is compared estimate performance of Luenberger Observer and High Gain Observer with the computer simulation. Effectiveness of the proposed high gain observer is proved from the experiment to compare the case with a speed sensor to the case with high gain observer in the speed control of DC servo motor.

• International Journal of Precision Engineering and Manufacturing
• /
• v.7 no.1
• /
• pp.18-23
• /
• 2006

Cutting by a high speed laser cutting machine is one of most effective technologies to improve productivity. This paper has presented the cutting characteristics and optimal cutting conditions in a high speed feeding type laser cutting machine by using Tacuchi method in the design of experiment. An L9(34) orthogonal array is adopted to study the effect of adjustment parameters. The adjustment parameters consist of cutting speed, laser power, laser output duty and assistant gas pressure. The surface roughness of sheet metal is regarded as a quality feature. Analysis of variance is performed in order to evaluate the effect of adjustment parameters on the quality feature of laser cutting process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.959-962
• /
• 2000

In this study, the micro shaft was fabricated by high speed etching process. The integration of the kinetic energy of circumference and the effect of etching takes less time to fabricate the micro shaft than any other conventional methods. First, the end part of the rod(SKD11) was dipped in chemical solution(FeCl$_3$) and the rod rotated at high speed(3500-10000rpm). Experimental setup was simply composed of high speed motor. chemical solution and $\Phi$ 1 mm rod. The main factors of diameter control are chemical concentration, reaction time and rpm. has a result. the diameter of the dipped rod was decreased by 200${\mu}{\textrm}{m}$ by high speed rotation and its shape and surface was good. From this experiment, we found the possibility to manufacture micro shaft without very expensive equipment.

• Journal of the Korean Society for Railway
• /
• v.7 no.2
• /
• pp.120-124
• /
• 2004

Computer aided simulation is an essential part in planning, design, and operation of railway systems. To determine the adequate performance and specification of railway system, it is necessary to calculate train performances such as distance, speed, power during train's running. This paper presents result of train performance simulation using the program that developed for Korea high speed train. To verify result of simulation, we have compared that with experiment data.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.12
• /
• pp.2100-2108
• /
• 2001

The impinging tones by high-speed plane jets are experimentally investigated to study the edgetone characteristics. Experiment used a slit nozzle and a wedge system to generate edgetones. The jet in the experiment is varied from low to high subsonic speed to obtain the effect of the speed on the frequency characteristics of impinging tones. The experimental data obtained previously fur edgetones and platetones by various nozzles are compared with the present edgetone data. And the condition of tone generation, the frequency ranges, the effective source point and the sound pressure level are compared and discussed. It is found that the jet speed has no diect influence on the impinging tone characteristics. Regardless of the jet speed, the effective source point is about a quarter wavelength downstream from the edge tip. With increase in jet speed, the influence of the nozzle configuration is decreased and the operating frequencies show good coincidences by normalized parameters based on the slit thickness.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1418-1423
• /
• 2004

High speed machining experiment on the heat-treated mold steel(STAVAX and CALMAX of hardness HRc 53) is carried using TiAlN coated ball endmill. Tool life and wear characteristics under the various machining parameters and cooling methods are investigated. Effect of cooling method on life and wear of the tool was compared. For most cases, tool life was not determined by the amount of wear but by th chipping on the cutting edge. It is found that tool manufacturer's cutting parameters generally agrees with the results of this experiment.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.12
• /
• pp.21-28
• /
• 2004

In modem manufacturing industries such as the airplane and automobile, aluminum alloys which are remarkable in durability have been utilized effectively. High-speed machining technology for surface roughness quality of workpiece has been applied in these fields. Higher cutting speed and feedrates lead to a reduction of machining time and increase of surface quality. Furthermore, the reduction of time required for polishing or lapping of machined surfaces improves the production rate. Traditional milling process for high speed cutting can be machined with end mill tool. However, such processes are generally cost-expensive and have low material removal rate. Thus, in this paper, face milling cutter which gives high MRR has developed face milling cutter body for the high speed machining of light alloy to overcome the problems. Also vibration experiment to detect natural frequency in free state and frequency characteristics during machining are performed to escape resonance.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.10
• /
• pp.163-170
• /
• 2002

The dynamic model of a high-speed vacuum circuit breaker mechanism with spring-actuated cam and linkage is derived to simulate the high-speed closing and opening operations. Its validation for an analysis of high-speed motion behavior is checked through experiments. The characteristics of the friction on the camshaft are investigated using the nonlinear pendulum experiment. The parameters of the friction model are estimated using the optimization technique. The analysis exhibits that the friction of the pendulum depends on stick-slip, Stribeck effect and viscous damping. Comparing simulation results with actual responses using a high-speed camera, the appropriateness of derived dynamic models for the rapid closing and opening operations is shown. The spring motion, which has much influence on the closing responses, is observed.