• KSTLE International Journal
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• 제3권1호
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• pp.17-22
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• 2002

Roughing of tool steel in its hardened state represents a real challenge in the die and meld industry and process improvement depends on research of tool material, coating technique, and lubrication. However, roughing of hardened steels generates extreme heat and without coolant flooding, tool material cannot withstand the high temperature without choosing the right tools with proper coating. This research conducted milling tests using coated ball end mills to study effects of cutting conditions and geometric parameters of ball end mills on the machinability of hardened tool steel. KP4 steel and STD 11 heat treated steels were used in the dry cutting as the workpiece and TiAIN coated ball end mills with side relief angle of 12$^{\circ}$ was utilized in the cutting tests. Cutting forces, tool wear, and surface roughness were measured in the cutting tests. Results from the experiments showed that 85 m/min of cutting speed and 0.32 mm/rev of feed rate were optimum conditions for better surface finish during rough cutting and 0.26mm/rev with the same cutting speed are optimum conditions in the finish cutting.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.407-408
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• 2006

• 한국재료학회:학술대회논문집
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• 한국재료학회 2007년도 추계학술발표대회 및
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• pp.8.1-8.1
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• 2007

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.63-67
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• 2000

A tool holder system has been designed to measure cutting forces in diamond turning. This system includes a 3-component piezo-electric tranducer. In this research, tool holder system is modeled by considering the element dividing, material properties, and boundary conditions using MSC/PATRAN. Mode and frequency analysis of structure is simulated by MSC/NASTRAN, for the purpose of developing the effective design. In addition, tool holder system is verified by vibration test using accelerometer. This system will aid to the development of Fast Tool Servo (FTS)

• 교육녹색환경연구
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• 제21권3호
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• pp.26-37
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• 2022

본 연구는 최근 국가 수준에서 대규모로 추진되고 있는 학교공간혁신 사업의 교육적 효과를 조사·분석하기 위한 도구를 개발하기 위해 수행되었다. 학교공간혁신의 교육효과를 분석하기 위해서는 학교공간혁신으로 변화되는 공간의 구조에 대한 분석이 우선 가능해야 하며, 공간의 변화에 따라 수반되는 교육의 변화 즉, 학교교육 및 학교생활, 교육적 성과 등에 대한 조사·분석이 가능해야 하며 이를 위한 사용자 설문조사 도구를 개발하였다. 본 연구를 통한 설문조사 도구는 학교공간혁신 사업에서 사전기획 단계에서의 사전조사 그리고 공간혁신의 교육적 효과 조사·분석을 위한 사후평가 도구로 활용 가능할 것으로 기대된다.

• 한국기계가공학회지
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• 제16권5호
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• pp.31-39
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• 2017

Research in the machine tool industry has focused on ICT-based smart machines rather than hardware technologies related to machine tools. Real-time tool-status monitoring is representative of this type of technology and has become important for measuring sensors during cutting processes. In this paper, we studied several research areas and used a round bar to conduct fundamental research into the axial displacement of the main spindle of a tool when it was subjected to a machining load. We were able to use the gap sensor to detect the axial displacement indirectly by using grooves with various shapes on the round bar and sensing the gaps between the grooves. We then determined the optimal groove shape for monitoring the tool state.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.395-405
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• 2019

In the present work, the effects of cutting parameters on surface roughness parameters (Ra), tool wear parameters (VBmax), tool vibration (Vy) and material removal rate (MRR) during hard turning of AISI 4140 steel using coated carbide tool have been evaluated. The relationships between machining parameters and output variables were modeled using response surface methodology (RSM). Analysis of variance (ANOVA) was performed to quantify the effect of cutting parameters on the studied machining parameters and to check the adequacy of the mathematical model. Additionally, Multi-objective optimization based desirability function was performed to find optimal cutting parameters to minimize surface roughness, and maximize productivity. The experiments were planned as Box Behnken Design (BBD). The results show that feed rate influenced the surface roughness; the cutting speed influenced the tool wear; the feed rate influenced the tool vibration predominantly. According to the microscopic imagery, it was observed that adhesion and abrasion as the major wear mechanism.

• 한국자동차공학회논문집
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• 제4권5호
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• pp.223-230
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• 1996

The quality and productivity in machining automobile parts are influenced by various factors such as cutting conditions, vibration, and used tool. To improve the quality and productivity of the automobile parts(torsion beam), lots of research on the evaluation of tool life and control of surface roughness has been required. Therefore, the width of flank wear, cutting force, and surface roughness are monitored to analyse the characteristics of tool wear and surface roughness at different tools. This experimental investigation is mainly focused on the characteristics of the tool wear, tool life and surface roughness in multi-insert milling of automobile parts(torsion beam) by using uncoated tungsten carbide tool(WC), TiN coated tool, and cermet tool.

• 경영과학
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• 제20권1호
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• pp.37-49
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• 2003

There is an increasing need to use mobile Internet as a research tool as wireless technology has been developing rapidly. However, little research has been conducted to confirm methodological validity of mobile Internet survey. This study examines the possibility of using mobile Internet as a survey tool by comparing survey results of mobile and stationary Internet surveys with the same questionnaire. The results were analyzed from both economic and theoretical perspectives. Both mobile and stationary Internet survey sites were implemented with supports from domestic mobile and stationary Internet portals and telecommunication companies. The results show that there exist several differences between two survey methods. First, many respondents who use mobile Internet gave up at the early stage. However, once people continued to respond, they answered the questions to the end. Second, means and standard deviations of mobile internet respondents were higher than that of stationary Internet. Third, the results of two survey methods were significantly different by comparing construct validity that includes both discriminant validity and convergent validity. Finally, this paper ends with implications and limitations of using mobile Internet as a survey tool.

• Structural Engineering and Mechanics
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• 제16권1호
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• pp.47-62
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• 2003

The nonlinear dependence aspect of various conical tool indentation parameters leading to an optimum tool semi angle value for easiest perforation is plotted and discussed explicitly in this work with the conclusion that tool angle has an optimum response towards most of the indentation parameters. Around this optimum angle, the aluminium sheets showed minimum fracture toughness as well as minimum work input to overcome the offered resistance. At the end, the mechanism leading to this phenomenon is presented with the conclusion that plastic flow dominates as the dimple semi cone angle reaches 35 and both pre and post plastic flow perforations lead the tool semi cone angle value towards this dimple cone semi angle of plastic flow initiation for its optimum performance. It is also concluded that specimen material failure is solely under tensile hoop stress and hence results into radial cracks initiation and propagation.