• Transactions of Materials Processing
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• v.15 no.9 s.90
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• pp.654-659
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• 2006

In this paper, the real shapes of micro tool deflection were observed. In micro endmilling process, micro tool deflection generates very serious problems in contrast to macro tool deflection. For analyzing the micro tool deflection, the trend of micro tool deflection was observed using real captured images in this paper. To get the real images of micro tool deflection, micro slot cutting processes were executed under cutting volume using micro endmill($Dia.\;200{\mu}m$) and real images of tool deflection were obtained during cutting processing by high-speed camera. Finally, the extent of tool deflection was calculated by the deflection angle according to cutting volume.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.57-63
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• 2014

At present, a high-speed swivel tool head of a small size is required to improve the productivity of CNC automatic lathes. Hence, there is growing interest in shorter machining times with higher cutting speeds. However, an increase in the rotation speed of a swivel tool head also has adverse effects, such as vibration and noise caused by the swivel tool head system. In this work, the fatigue life and contact pressure of a swivel tool head bearing system driven by gears were calculated. Based on the calculated results, a prototype swivel tool head was manufactured and its static and dynamic characteristics, i.e., the vibration, noise and precision, were measured using a reliability testing device which allows the application of cutting force to the end of the swivel tool head.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.158-161
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• 2003

Recently, the evolution in production techniques (e.g. high-speed milling), the complex shapes involved in modem production design, and the ever increasing pressure for higher productivity demand a drastic improvement of the dynamic behavior of the machine tool axes used in production machinery. And also machine tools of multi functional and minimized parts are increasingly required as demand of higher accurate in some fields such as electronic and optical components etc. The accuracy and the productivity of machined parts are natural to depend on the linear system of machine tools. The complex workpiece surfaces encountered in present-day products and generated by CAD systems are to be transformed into tool paths for machine tools. The more complex these tool paths and the higher the speed requirements, the higher the acceleration requirements are needed to the machine tool axes and the motion control system, and the more difficult it is to meet the requirements. The traditional indirect drive design for high speed machine tools, which consists of a rotary motor with a ball-screw transmission to the slide, is limited in speed, acceleration, and accuracy. The direct drive design of machine tool axes. which is based on linear motors and which recently appeared on the market. is a viable candidate to meet the ever increasing demands, because of these advantages such as no backlash, less friction, no mechanical limitations on acceleration and velocity and mechanical simplicity. Therefore performance tests were carried out to machine tool axes based on linear motor. Especially, dynamic characteristics were investigated through circular test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.46-51
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• 2002

A grinding technology is very essential to finish the surface of IT and BT industrial application parts such as wafer, optical connection part and lenses etc. However the finding machine has bead depended on imports. Especially, it is completely imported for machining high precision part relevant to domestic electric and communicational industries. The amount to import grinding machine is about $110milions. It takes about 35% of total import amount of all the machine tools. A domestic finder manufacturer is a very small-scaled bussinessman and research facilities is poor. Recently, it is increasing to demand high speed and precision grinding technology because it brings cost down and value added up. Its further study will be something related to inteligent grinding system fur value added and high precision part. It will make domestic grinding technology to its advanced country level.

• 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.

• Korean Journal of Computational Design and Engineering
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• v.18 no.2
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• pp.148-154
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• 2013

Han-ok (the Korean traditional house) is famous for its beauty and healthful aspects. However, its construction cost is too high because of the manual process of parts such as rafter, timber, etc. These days, many people want to build a modernized Korean traditional house at a low cost. In order to do so, the rafter machining process is required to be automatized using a CNC machine. It is also observed that, generally the timber does not have a uniform shape. Therefore, it is also needed to examine the timber shape before starting its processing. This paper presents the concept design of the rafter processing CNC machine, and a 3D laser scanning system. The laser scanner is developed to acquire 3D details of the timber shape. Furthermore, the results of simulated experiments are presented to investigate surface roughness during the machining process of the timber. Since cutting parameters largely influence on surface roughness and cusps formation, it is needed to achieve optimal machining parameters. Several experiments were carried out changing cutting parameters such as cutting tool diameter, feed-rate, and spindle speed.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.9
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• pp.125-132
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• 2002

We use a compound-cam twin arm structure and random tool access method to achieve a faster ATC (Automatic Tool Changer) system for the accurate position and rotation control of a tool magazine and an exchange am. Based on the data obtained from various sensors, it is possible to follow the sequence of commands in each control step for an exchange arm. However, it is not so easy to reduce the exchange time of the system because of the slow responses of the sensors and execution mode delays of PLC (Programmable Logic Controller) scan time. In this paper, we propose a new programmed limit-switch position control method to obtain the shortest possible delays for the random tool access method and compound-cam twin arm structure. With some experimental results, we have achieved below 0.9sec tool exchange time with the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.5
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• pp.500-505
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• 2012

Recently, a high speed spindle is an essential part of machine tools to satisfy latest demand of high precision product and machining of hard materials. But, there are many disadvantages such as heat generation of built-in-motor, bearing friction, noise, vibration and displacement because of the high speed. Many researches on spindle systems have been conducted for solving these problems. In this study, technical trend of machine tools spindle systems are analyzed with patent PSM, mapping and grouping. The analysis is carried out for the applied patent during January 2000 and December 2009 in Korea, Japan, EU and U.S.A. And development of the direction, strategy and promising technologies of the spindle system are suggested.

• Laser Solutions
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• v.18 no.1
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• pp.1-6
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• 2015

High welding speed and narrow weld seam are favorable for welding of magnesium alloy. Magnesium alloy is recommended for the smart frame because it has several advantages such as low density, high thermal conductivity, EMI shielding capability and good cast ability. This study is for the assembly welding of the magnesium smart frame with high productivity, good performance and low cost. The window for battery on AZ91D frame produced by die-casting was prepared by CNC machining. Corresponding AZ31 blank of 0.2mm thickness was prepared by die-blanking cut. All system set was fixed at the stationary bed but the laser beam was manipulated by scanner up-to 1,000mm/s speed. The weld joint between AZ31 sheet and AZ91D frame was welded by fiber laser on 850~1,000W output power. The joint showed penetration enough but some humping bead. The distortion by the weld heat was almost free because of the quick dissipation of the heat by small beam size and fast welding. Consequently, the thinner magnesium foil was assembled successfully to the magnesium frame of mobile phone.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.62-68
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• 2019

In this paper, we describe the design and manufacture of a control system for an automatic loading system that inserts and removes workpieces after machining. The control system was manufactured using DSP for high speed and consists of a power unit, a control unit, a communication unit, and a display unit. We connected the control system to the mechanical system of the automatic workpiece loader to test the characteristics, which allowed us to raise and lower the automatic workpiece loading system to the desired position. The successful test demonstrates that we can use the control system to control the workpiece automatic loading system.