• 한국정밀공학회지
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• 제13권4호
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• pp.136-142
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• 1996

Automatic monitoring of cutting process is one of the most important technology in machining. AE sensing technology has been applied to monitoring process and proved to be effective in detecting tool abnor- malities such as tool wear and fracture. In this experimental study. AE signals were detected from the tool holder for continuous and interrupted cutting, which obtained from changing workpice material configuration, under control of constant cutting speed from CNC lathe. From statistical and frequency analysis, the AE signals were analyzed to obtaining the characteristics of continuous and interrupted cutting conditions and tool failure. The Kurtosis values decreased but RMS voltages increased as the cutting speed increased, in both continuous and interrupted cutting. RMS voltage is suddenly increased but Kurtosis value is suddenly decreased when tool failure condition. Power spectrum density of AE signals when tool failure reaches extreme value around 0.065 cycles/ .mu. m.

• 한국소음진동공학회논문집
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• 제19권11호
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• pp.1214-1221
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• 2009

A high-speed spindle can be very sensitive to rotating mass unbalance which has harmful effect on many machine tools. Therefore, the balancing procedure to reduce vibration in rotating system is certainly needed for all high-speed spindles. So, balancing procedure was performed with a spindle-bearing system for CNC automatic lathe by using numerical procedure. The spindle is supported by the angular contact ball bearings and the motor rotor is fixed at the middle of spindle. The spindle-bearing system has been investigated using combined methodologies of finite elements and transfer matrices. The balancing was performed through influence coefficient method and the comparison was made by whirl responses between before balancing and after balancing. As a result, balancing of simple spindle model reduced whirl orbit magnitude in case of a completely assembled spindle model.

• 한국기계가공학회지
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• 제21권4호
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• pp.23-30
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• 2022

Small-scale production is increasing, and the manufacturing industry is gradually changing into a smart manufacturing industry. Therefore, research on securing optimal cutting conditions for factors affecting machining precision during cutting is very important. Therefore, the purpose of this study is to After machining the inner diameter hole of SCM415 steel with a cermet tool on a CNC automatic lathe, the surface roughness, dimensional accuracy, and dimensional straightness are measured according to the feed rate to analyze the machining characteristics and suggest optimal cutting conditions. The test material was cut using a cermet tool for secondary cutting after a round bar with a diameter of 20 mm was mounted on a CNC automatic lathe. The cutting length was fixed at 0.5 mm, and the cutting speed was fixed at 3200 rpm. When the feed rate was changed to 0.05, 0.1, and 0.15 mm/rev, the respective surface roughness during the 15th test was measured. Consequently, The lower the feed rate, the better is the surface roughness. In addition, the optimum cutting conditions for SCM415 steel were observed to be the most ideal cutting conditions than the condition of 0.05 mm/rev at a cutting speed of 3,200 rpm and a feed rate of 0.1 mm/rev.

• 한국기계가공학회지
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• 제18권2호
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• pp.22-28
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• 2019

In this study, we describe the mechanical design of the cylindrical workpiece inspection system which that can inspect the workpiece machined in the CNC lathe. The workpiece automatic measuring device is composed of a workpiece aligning mechanism, a workpiece diameter measuring mechanism, and a workpiece height measuring mechanism. If the workpiece machined on the CNC lathe is placed on the pedestal of the cylindrical workpiece inspection system, the workpiece aligning mechanism moves the workpiece to the diameter-measuring position and the height- measuring positions, and the diameter-measuring mechanism and the height- measuring mechanisms sequentially measure the diameter and the height of the workpiece. The cylindrical workpiece inspection system was designed and manufactured. The characteristic experiment was conducted to confirm the operation of the machine tool of the cylindrical workpiece inspection system. As a The result of the characteristic test shows that, the workpiece automatic measuring device operated safely.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.300-306
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• 2005

This paper presents the methodology for measuring eccentricity of the machined cylindrical part using CCS(cylindrical capacitance spindle sensor) signal in the CNC turning process. We use capacitance type sensor to take full advantage of averaging effect by using large capacitance area to encompass the whole side of a sensor. The intentionally proposed initial eccentricity is applied to the experimental testpieces, and their resultant relationships between CCS orbits and eccentricities are investigated. As a result, the possibility as a automatic detection apparatus for the CNC lathe is considered based on the linearities of CCS signal and magnitude of eccentricity of machined cylindrical surfaces.

• 한국정밀공학회지
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• 제11권6호
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• pp.185-199
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• 1994

This study has been performed to present a new automatic tool wear measurement by digital image processing. The purpose of this paper is to develop an automatic tool wear measuring system based on the image processing which can be applied to the quasi-real time measurement of the characteristics of insert tip in turning. Tool wear monitoring is one of the key-problems, for the development of control systems of modern unmanned factory which are not completely solved now. In oredr words at present complete qualitative and quantitative information on tool wear morphology is required, at least on the following aspects : flank wear, its dimensions and distribution on the maximum and mean values on VB pqrqmeter in the various zones of the wearland. crater wear, its main dimensions and values of KT parameters. This research has been performed to this technique made possible by designing a proper lighting system to the worn tool with following features : The flank wear is measured by observing the active cutting part from a proper direction and by lighting the wearland by a diffuser optic system. The crater wear is visualized by lighting the tool by a He-Ne gas laser system developed in this study. By means of this system it is research to evaluate classical parameters of tool wear and to have complete information about tool wear morphology.

• 한국정밀공학회지
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• 제12권10호
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• pp.5-17
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• 1995

기계가공(Machining)중에서 가장 기본적인 것이 선삭(Turning)작업이며, 이 가공은 선반(Lathe)에 의해서 행하여지고 있는 것은 다 아는 사실이다. 공작기계의 발달과 금속 절삭 원리(Principles of metal cutting)는 선반을 중심으로 약 일세기동안 꾸준히 발전해 오고 있으며, 수없이 쏟아져 나온 연구논문들의 대부분이 선반에 의한 가공과 그 공작기계에 의해서 이루어졌으며 앞으로도 계속 보통선반, CNC선반의 토대 위에서 이루어지리라고 보고 있다. 공작기계 중에서 CNC 선반의 발달 과정을 요약해보면 1960년대의 대량 생산시대에는 Programmable control 방식의 자동 터렛트(Turret) 선반이 개발되어 생산 공정이 비교적 간단한 양산 가공기로서 환영을 받게 되었다. 1970년대에 들어서면서 다품종소량생산이 중요시되었고, 그때 NC 선반시대가 시작되었다고 볼 수 있다. 현 싯점에서 볼 때 이것은 중품종중량생산 이라고 말할 수 있으며, Turret 선반의 NC화 즉, Multi-tool에 의한 선반의 복합가공이 가능해졌지만 Tooling에 문제가 발생하였다. 1980년에 들어서 각종 MC 들이 광범위하게 발달, 보급되는 경향에 따라서 NC 선반도 고능률화의 일환으로 고속화와 더불어 회전공구인 End mill. Drill. Tap 등의 복합가공이 가능한 복합선반이 차례로 개발되었고 선삭공구와 회전공구등의 자동공구교환(Automatic Tool. Changing. ATC)이 가능해지고 Y축 보정(Co-mpensation)기구를 부착한 대형 Turning center가 개발되어 보급되게 되었다.

• 대한기계학회논문집
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• 제18권4호
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• pp.805-815
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• 1994

The development of automatic production systems has a trend toward Computer Integrated Manufacturing System(CIMS) in recent years. In hardware configuration, CIMS are composed of intelligent CAD/CAM work stations, multifunction CNC machining centers including material handling systems. The DNC systems present the key element of automation hierarchy in a FMS. A DNC system is one which connects a number of numerically-controlled machines to a common memory in a digital computer for part program storage with provision for on-demand distribution of part program data to machines using communication in hierarchical structure of central computer, control computer and cell controller. This paper describes the development of Behind-the-Tape-Reader(BTR) type DNC system using CYBER 180-830 as a central computer and IBM PC-386 cell control computer and NC lathe with FANUC 5T NC controller. In this system, the connection between central computer and cell control computer is done via RS-232C serial interface board, and the connection between cell control computer and FANUC 5T controller is done via parallel interface board. The software consists of two module, central computer communication module for NC program downloading and status uploading, NC machine running module for NC operating.

• 한국기계가공학회지
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• 제11권4호
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• pp.104-110
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• 2012

The spindle with a built-in motor can be used to simplify the structure of machine tool system, while the rotor has unbalance mass inevitably. A high-speed spindle can be very sensitive to rotating mass unbalance which has harmful effect on many machine tools. Therefore, the balancing procedure to reduce vibration in rotating system is certainly needed for all high-speed spindles. So, it was performed with a spindle-bearing system for CNC automatic lathe by using numerical procedure. The spindle is supported by the angular contact ball bearings and the motor rotor is fixed at the middle of spindle. The spindle-bearing system has been investigated using combined methodologies of finite elements and transfer matrices. The balancing was performed through influence coefficient method and the comparison was made by whirl responses between before balancing and after balancing. As a result, balancing of simple spindle model reduced whirl orbit magnitude in case of a completely assembled spindle model.

• 대한치과기공학회지
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• 제30권1호
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• pp.57-63
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• 2008

The purpose of this study was to ascertain the effect of different abutment height and different taper of abutment on retention force of cemented implant-supported prostheses. Test specimens consisted of different abutment height group(3mm, 4mm, 5mm, 6mm, 7mm) and different taper(degrees) abutment group($4^{\circ},\;5^{\circ},\;6^{\circ},\;7^{\circ},\;8^{\circ}$). The surfaces of abutments and crowns were manufactured and finished by automatic lathe(CNC). Luting cement(Tokuso Ionomer) was prepared according to the manufacturer's instruction. And the cylinders were sealed onto the abutments and loaded in compression at 5kg for 10minutes. Excess cement was removed from the abutment-cylinder junction and the specimens were stored at room temparature for 24 hours. Specimens were tested in tension using a universal testing machine. Within the limits of this study, the following conclusions were drawn: 1. The increase in abutment height result in improvement in retention strength(P<0.05). 2. The increase in taper of abutment result in decrease in retention strength(P<0.05). 3. The decrease in abutment height result in decrease in retention strength, besides has a significantly lower retention strength at 3mm abutment height. 4. The increase in taper of abutment result in decrease in retention strength, besides has a significantly lower retention strength at $7^{\circ}$ abutment.