• 한국산학기술학회논문지
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• 제19권11호
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• pp.338-343
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• 2018

최근 금형산업과 다양한 산업에서 사용되고 있는 CNC 공작기계는 제품 공정 증가에 따라 작업효율, 생산 품질과 작업자의 안전성이 중요해지고 있다. 특히 4차 산업으로 산업구조가 바뀜에 따라 CNC 공작기계는 기존의 고정밀, 고능률화를 넘어 ICT 스마트 가공에 대한 다양한 연구가 진행되고 있다. 이에 CNC 절삭가공 시 생산제품의 품질을 균일하게 하고 재현성을 향상시키기 위한 다양한 공구 수명 예측 연구가 진행되어 왔다. 이러한 과정에서 기존의 확장된 Taylor 공구 수명식을 이용하여 공구 수명을 예측하였을 경우 예측결과와 실제 실험 결과와의 오차가 상당하다. 이에 본 논문에서는 공구 수명 관련 가공 실험을 통해 공구 수명에 대한 데이터를 확보 한 후 이를 기초로 유전알고리즘을 이용하여 최적의 공구 수명 매개변수를 추정하였다. 이때 공구 수명에 관련하여 공구 마모 관련 정보를 삽입하여 공구 마모량에 따른 공구 수명을 정확하게 예측할 수 있도록 구성하였으며, 이를 통해 공구 수명식을 보다 정확하게 최적화할 수 있도록 하였다.

• 한국정밀공학회지
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• 제28권1호
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• pp.11-18
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• 2011

A worm screw is widely used in a geared motor unit for motion conversion from rotation to linear. For mass production of a high quality worm, the current rolling process is substituted with the milling process. Since the milling process enables the integration of all operations of worm manufacturing on a CNC(Computer Numerical Control) lathe, productivity can be remarkably improved. In this study, the tooling system for side milling on a CNC lathe to improve machinability is developed. However, the cutting tool-workpiece interference is important factors to be considered for producing high quality worms. For adaptability of various worms machining, the tool-workpiece interference simulation system based on a tool-tip trajectory model is developed. The developed simulation system is verified through several kinds of worms and experimental results.

• 한국공작기계학회논문집
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• 제13권6호
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• pp.56-63
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• 2004

The real-time NURBS interpolation method using 2-stage interpolation is studied. The 2-stage interpolation method that compensates for interpolation errors within machine BLU is proposed. The interpolation result was filtered by an Acceleration/Jerk limitation equation. Through this 2-stage interpolation, both the interpolation error condition and the motion kinematics could be satisfied. Using computer simulation in which interpolation results are evaluated by a numerical iteration method, it is shown that the 2-stage interpolation algerian could interpolate target curves precisely with geometric and dynamic contentment. The proposed algorithm was implemented in the CNC simulator system and an experimental un was conducted to identify the real-time adaptation.

• 한국기계가공학회지
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• 제8권4호
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• pp.76-82
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• 2009

A worm screw is widely used in a geared motor unit for motion conversion from rotation to linear motion. For mass production of a high quality worm, the current roll forming process is substituted with the milling cutter process. Since the milling cutter process enables the integration of all machining operations of worm manufacturing on a CNC(Computer Numerical Control) lathe, productivity can be remarkably improved. The tooling system for side milling cutter on the CNC lathe to improve machinability is developed. However, the runout of spindle and cutting tips are important factors to be considered for producing high quality worms because the tooling system has multiple tips. In this study, surface roughness variations accuracy according to runout was investigated in side milling cutter for worm screw. The result shows by simulation and experiment.

• 한국정밀공학회지
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• 제26권12호
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• pp.47-54
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• 2009

A worm screw is widely used in a geared motor unit for motion conversion from rotation to linear. For mass production of a high quality worm, the current rolling process is substituted with the milling process. Since the milling process enables the integration of all operations of worm manufacturing on a CNC(Computer Numerical Control) lathe, productivity can be remarkably improved. In this study, the tooling system for planetary milling on a CNC lathe to improve machinability is developed. However, the cutting tool-workpiece interference is important factors to be considered for producing high quality worms. For adaptability of various worms machining, the tool-workpiece interference simulation system based on a tool-tip trajectory model is developed. The developed simulation system is verified through several kinds of worms and experimental results.

• 한국산업보건학회지
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• 제28권2호
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• pp.230-239
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• 2018

Objective: The purpose of this study is to identify the kinds and exposure levels of health hazards in the metalworking process in relation to acute poisoning accidents caused by methanol in 2016. Methods: The number of industries, workplaces, exposed workers, regional distribution, and exposure level of health hazards in metalworking process were investigated based on employee exposure assessment database provided by KOSHA (the Korea Occupational Safety and Health Agency), which was collected from workplace hazard evaluation programs in Korea. Exposure metrics for methanol were assessed by RCR (risk characterization ratio). Results: The numbers of processes, workplaces, and exposed workers of metalworking, which include CNC (computer numerical control) were 25, 14,405, and 169,102 respectively. The numbers of samples of chemical hazards including methanol were 91,325, and it was found that workers in metalworking were exposed to 249 kinds of chemical hazards. There were 16 kinds of special controlled substances including beryllium. It is estimated that the number of workplaces involving CNC process was 2,537, and the number of exposed workers was 27,976. In CNC process, the total number of workplaces handling methanol was 36, and 298 workers were estimated to be exposed. There was no exceeded that surpassed the OEL and 49% of samples were below the limit of detection. Methanol exposure concentrations in Gyeonggido Province were statistically significantly higher than in other areas (p <0.0001). Conclusions: In the metalworking process including CNC, there is exposure to a wide variety of health hazards. There was no sample exceeding the OEL for methanol. Therefore, it is necessary to recognize the limits of the employee exposure assessment system and urgently improve measures to prevent the occurrence of events like methanol poisoning.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.85-90
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• 2001

Recent general Press brake has many problems in cutting high accurate products in the progress of industry. Previous hand-operated press brake needs many pre-processing works to adjust bending ang1e and marking-off works to calculate bending length. Also, the hand-operating work makes many geometric errors and has difficulty for variety-mass production. To solve these problems, this paper proposes Computer Numerical Control (CNC) general press brake and development of servo-control system based on database for reduction of geometric errors and pre-processing work time and high accuracy bending work.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.410-413
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• 1997

Recent general press brake has many problems in cutting high accurate products in the progress of industry. Previous hand-operated press brake needs many pre-processing works to adjust bending angle and marking-off works to calculate bending length. Also, The hand-operating work makes many geometric errors and has difficulty for variety-mass production. To solve these problems, this paper proposes Computer Numerical Control (CNC) general press brake and development of servo-control system based on database for reduction of geometric errors and pre-processing work time.

• 한국기계가공학회지
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• 제20권5호
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• pp.27-34
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• 2021

This study analyzes machining characteristics and presents optimal cutting conditions by measuring the surface roughness, dimensional accuracy, and dimension straightness based on the feed rate after processing the inner diameter hall of SCM415 steel using an automatic CNC(Computerized Numerical Control) lathe. The testing material was cut using an 11.8 mm-diameter Chamdrill after mounting the 32 mm-diameter round bar on an automatic CNC lathe. The cut depth was set at 3 mm, and the cutting speed was fixed at 1500 rpm. The surface roughness, dimensional accuracy, and dimension straightness of 15 testings were measured by changing the feed rate to 0.05, 0.1, and 0.15 mm/rev, respectively. It was difficult to process more than 15 tests during the maching due to noise or break. Additionally, the optimum cutting of SCM415 steel showed excellent surface roughness in the 10^th and 11^th of testing at cutting speed and feed speed of 1500 rpm and 0.05 mm/rev, respectively. The dimensional accuracy was measured in three dimensions after drilling, which showed good results with an average range of 0.0138-0.0208 mm. Moreover, the lower the feed speed, the higher the accuracy. Additionally, the measurement results of the dimensional straightness showed that the straightness is the straightness was the best at the 1^th and 2^th cutting regardless of the feed speed.

• 한국정보통신학회논문지
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• 제22권12호
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• pp.1675-1683
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• 2018

본 논문은 CNC(Computer Numerical Control) 장비로부터 나사선 형태로 가공된 나사를 비전 시스템을 통해 선별된 양품을 이송해 주는 철재 파렛트에 삽입될 NFC(Near Field Communication) 안테나 모델링에 대한 연구이다. 여기서 사용되는 CNC 장비는 IoT((Internet of Things)) 해당하는 ICT(Information & Communication Technology)을 접목 시키고, 서비스 인터넷에 해당하는 POP(Point Of Production System)을 연결하여 쌍방향으로 자유롭게 정보를 교환하면서 생산하는 스마트팩토리 시스템 기술이 반영하여 진화된 장비이다. 따라서 본 연구에서는 기존 아날로그식 장비에 POP 모니터링 시스템을 접목하여 자재 관리로 사용되는 철재 파렛트에 삽입된 NFC 안테나를 나사 가공품에 대한 위치 정보를 수집할 수 있도록 철재 파렛트 특성을 고려하여 현장 검증을 통해 그 특성을 알아보았다.