• 한국기계가공학회지
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• 제20권5호
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• pp.1-7
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• 2021

In recent years, automated process technology has allowed for the rapid manufacturing of metal parts. Maintaining high product quality is of vital importance during the production of these parts. Surface defects occurring after processing can compromise their assembly precision and performance. In this study, a deburring tool was developed that can remove burrs generated from drilling. Through the evaluation of processing, burrs were completely removed at entrance and exit surfaces. Therefore, this newly developed deburring tool shows better performance than deburring tools currently in use.

• 한국기계가공학회지
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• 제18권6호
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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.

• 한국정밀공학회지
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• 제29권8호
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• pp.813-817
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• 2012

Laser assisted machining (LAM) is machining method that performs a machining for workpieces using laser beam preheating. LAM is in the early stage of its applications and has only been used in limited fields including turning, planning and micro end-milling throughout the world. LAM system should be able to move to the laser radiation direction and to rotate on a tool path for machining of complex shapes. A laser module with two-axis manipulator is designed in this study. It has been performed static structural analysis and shape modification of the manipulator. As the results of shape modification it has been obtained better results than the initial model. These results will be able to use in development of the two-axis manipulator.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.660-663
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• 1997

In recent manufacturing process, the increase of productivity is required by reducing machining time with the increase of cutting force. However, the excessive increase of cutting force can cause tool breakage, and have a bad effect on both the manufacturing machine and the workpiece. Thus, it is necessary to estimate and control cutting force in real time during the process. In this study, use of disturbance observer is proposed for the indirect cutting force estimation. The estimated cutting force is used for the real time control of feedrate, making the actual cutting force follow the reference force command. Since the suggested method does not need an expensive sensor like a dynamometer, the method is expected to be used practically. By reducing the machining time resulting from making the actual cutting force follow the reference force, the increase of productivity are also expected, and the quality of cutting surface has been improved due to the adjusted feedrate. Besides, an actual constant cutting force guarantees the prevention of tool breakage. To show the effectiveness of the suggested cutting force control method, an experimental setup has been made without the force sensor, applied to several workpieces. Experiments show that the suggested method is superior to the conventional method operated by constant feedrate.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.660-665
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• 2002

Mirror surface finish of Si-wafers has been achieved by rotary in-feed machining with cup-type wheels in ELID grinding. But the diameter of the workpiece is limited with the diameter of grinding wheel in the in-feed machining method. In this study, grinding experiments by the rotary surface grinding machine with straight type wheels ware conducted, by which the possible grinding area of the workpiece is independent of the diameter of the wheels. For the purpose of investigating the grinding characteristics of large scale diametrical silicon wafer, grinding conditions such as rotation speed of grinding wheels and revolution of workpieces are varied, and grinding machine used in this experiment is rotary type surface grinding n/c equipment with an ELID wit. The surface ground using the SD8000 wheels showed that mirror like surface roughness can be attained near 2 - 6 nm in Ra.

• 한국생산제조학회지
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• 제23권3호
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• pp.273-278
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• 2014

This study presents a chatter vibration avoidance program for the milling process. Chatter vibration has a negative effect on workpieces and spindle-tools. When chatter vibration occurs, the cutting tool is loaded dynamically, a chatter pattern is generated on the workpiece, and the tool life is reduced. The developed program is composed of various modules such as an FFT analyzer, an impact test analyzer, a chatter vibration indicator, and a spindle speed recommender. The proposed program is verified using an AISI D2 cutting experiment in milling process. The effect of chatter vibration on the machining condition can be simulated by the suggested method, and successfully exploited to avoid chatter vibration.

• 한국생산제조학회지
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• 제22권4호
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• pp.747-754
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• 2013

This study introduces a recently designed desktop-sized NC turning system and its components. This machine is designed for the ultra-precise turning of parts with a diameter of 0.5-20 mm with minimum space usage for the machine. This study aims to achieve submicron-level accuracy of movements and good rigidity of the machine for precision machining using the desktop-sized machine. The components such as the main machine structure, air bearing servo spindle, and XZ stage with needle roller guides are designed, and the designed machine is built with a PC-based CNC controller. Its static and dynamic stiffness performances and positioning resolutions are tested. Through machining tests with single-crystal diamond tools, a form error less than $0.8{\mu}m$ and surface roughness (Ra) of $0.03{\mu}m$ for workpieces are obtained.

• 한국정밀공학회지
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• 제32권8호
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• pp.687-692
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• 2015

LAM (Laser-Assisted Machining) is an effective method for processing difficult-to-cut workpieces. The focal length of a LAM system is changed by the change of the workpiece shape during laser preheating; this problem is solved by changing the lens of the laser module. Linear- and rotary-type lens changers were developed to change the laser lens of a LAM system. The linear-type lens changer is operated by a motor with a ball-screw, and the rotary type is operated by a stepping motor. The natural frequency and structural stability of the laser lens changers were confirmed by using a finite element analysis; in addition, the functions of the lens changers were verified by measuring the iterative accuracy. The measured results show that the rotary-type lens changer is more accurate than the linear-type changer.

• 한국정밀공학회지
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• 제18권8호
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• pp.139-149
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• 2001

The effects of the cutting conditions on the surface roughness of workpiece in turning were studied in this paper. The workpieces made of carbon steel SM20C and SM45C were tamed without the support of the tailstock center. Cutting conditions were changed in three or flour steps in each parameter and cutting fluid was used. The surface roughness results of tests were measured and the effects of the cutting conditions were analyzed by the method of analysis of variance. The summary of the experimental research is as follows. The main parameters were cutting speed, fred-rate, depth of cut, and the interactions between speed and fled-rate, speed and depth of cut, and fred and depth of cut. As cutting speed increased, surface roughness showed lower value. The surface roughnesses of feed-rate 0.102 mm/rev and 0.147 mm/rev were better than those of feed-rate 0.05 mm/rev and 0.2 mm/rev.

• 한국정밀공학회지
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• 제15권2호
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• pp.114-123
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• 1998

In the end milling process, the information of the surface errors plays an important role in adaptive control systems for precision machining. As the measuring accuracy of the surface errors directly matches the control's, it is an important factor for evaluating the performance of the system. In order to obtain the surface errors, the prediction using the cutting force, torque, motor power etc. is frequently practiced owing to the easiness in measurement. In the implementation of the prediction, the information on the cutting depths make it concrete and precise. Actually the axial depth of cut limits the range of the calculation. In general, it is not easy to know the cutting depths due to irregular shape of workpieces, inaccurate positioning of them on the table of machine tool, and machining error in the previous cutting. In addition to, even if cutting depths are informed, it is difficult to match the individual position of the cutter on the varying shape of the work material. This work suggests an algorithm estimating the cutting depths based on cutting force and makes it precise to predict the surface error. The proposed algorithm can be applied in more extensive cutting situations, such as presence of the tool wear, change of the work material hardness, etc.