• 제목/요약/키워드: Tool Stress

검색결과 1,037건 처리시간 0.023초

Force Prediction and Stress Analysis of a Twist Drill from Tool Geometry and Cutting Conditions

  • Kim, Kug-Weon;Ahn, Tae-Kil
    • International Journal of Precision Engineering and Manufacturing
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    • 제6권1호
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    • pp.65-72
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    • 2005
  • Drilling process is one of the most common, yet complex operations among manufacturing processes. The performance of a drill is largely dependent upon drilling forces, Many researches focused on the effects of drill parameters on drilling forces. In this paper, an effective theoretical model to predict thrust and torque in drilling is presented. Also, with the predicted forces, the stress analysis of the drill tool is performed by the finite element method. The model uses the oblique cutting model for the cutting lips and the orthogonal cutting model for the chisel edge. Thrust and torque are calculated analytically without resorting to any drilling experiment, only by tool geometry, cutting conditions and material properties. The stress analysis is performed by the commercial FEM program ANSYS. The geometric modeling and the mesh generation of a twist drill are performed automatically. From the study, the effects of the variation of the geometric features of the drill and of the cutting conditions of the drilling on the drilling forces and the stress distributions in the tool are calculated analytically, which can be applicable for designing optimal drill geometry and for improving the drilling process.

유한요소법에 의한 공구인선의 응력분포에 관한 연구

  • 김정두
    • 한국정밀공학회지
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    • 제1권1호
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    • pp.50-58
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    • 1984
  • In the present paper are calculated and compared the stresses on the normal tools and the restricted tools which have three various rake angles by Least Square Method. The results obtained are summerized as follows. The tool displacement at rake angle .alpha. = 12 .deg. and .alpha. = 0 .deg. is positive value in the principal cutting direction and negative value in the feed direction. At rake angle .alpha. = -12 .deg. the displacement is negative value in both of directions. The principal stress of the restricted and normal tool is maximum at the tip of the tool, the shear stress is maximum after a certain distance from the tip. The result of FEM and P.E method shows that in the range of rapid decreasing of normal stress of the tool edge, the shear stress is maintaining a certain value. This is due to the friction characteristic of the chip.

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겉보기 응력 개념에 기반한 공구각에 따른 비절삭저항 변화 분석 (Analysis on Specific Cutting Resistance Variation by Tool Angles Based on a Concept of Representative Stres)

  • 전은채;최환진;이규민;이윤희;제태진;김정환;최두선
    • 한국기계가공학회지
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    • 제13권2호
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    • pp.64-72
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    • 2014
  • In the past, prism patterns have been linear triangular shapeswith a $90^{\circ}$ angle; however, new micro prism patterns having acute angles or obtuse angles have recently been the subject of demandin the display, lighting and photovoltaic industries. Micro-cutting experiments for micro-prism patterns having $60^{\circ}$, $90^{\circ}$, and $120^{\circ}$ angles on an electroplated Ni mold were performed and it was found in this study that the specific cutting resistance increased with a decrease in the tool angles (prism pattern angles). The cause of this variation had been thought to be the increase of the ploughing force due to tip rounding and the friction force due to the edge effect. However, the depth of the cut was large enough that it was possible to neglect these effects. Therefore, this study introduced the concept of representative stress of indentation. The measured stress was varied according to the indentation depth eventhoughthetestedspecimenswereidentical ; the varied stress was termed the representative stress. According to indentation theory, the strain that the Ni mold experienced increased with a decrease in the tool angle. Based on the stress-strain relationship, higher strain means higher stress and higher specific cutting resistance. Therefore, the specific cutting resistance was higher at smaller tool angles that had higher strain and stress.

냉간단조 생산성 향상 사례 (Case studies for productivity enhancement on cold forging)

  • 최석탁;이일환;권용철;이정환;이영선
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 춘계학술대회 논문집
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    • pp.42-47
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    • 2007
  • The characteristics of the tool system give many effects into the costs and qualities for the finished components. Therefore, a tool life is one of the important issues on cold forging industry. However, since variables related with tool life are many complicated, the studies for solution should be investigated by the systematic research approach. The shape and process changes of die, the hardness changes of material and the tolerance of dies to decrease the die stress are analyzed by the FEM software. The heat-treatment of tool material is investigated to improve the tool life. Deep cryogenic treatment of tool steel is very efficient to improve the wear resistance due to the fine carbide. And, it is investigated that the shape and dimension of tool give effect into both tool life and quality of forged product..

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Determination of stress state in formation zone by central slip-line field chip

  • Toropov Andrey;Ko Sung Lim
    • International Journal of Precision Engineering and Manufacturing
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    • 제6권3호
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    • pp.24-28
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    • 2005
  • Stress state of chip formation zone is one of the main problems in metal cutting mechanics. In two-dimensional case this process is usually considered as consistent shears of work material along one of several shear surfaces, separating chip from workpiece. These shear planes are assumed to be trajectories of maximum shear stress forming corresponding slip-line field. This paper suggests a new approach to the constriction of slip-line field, which implies uniform compression in chip formation zone. Based on the given model it has been found that imaginary shear line in orthogonal cutting is close to the trajectory of maximum normal stress and the problem about its determination has been considered as well. It has been shown that there is a second central slip-line field inside chip, which corresponds well to experimental data about stress distribution on tool rake face and tool-chip contact length. The suggested model would be useful in understanding mechanistic problems in machining.

웹 기반의 시각적 스트레스 증후군 선별에 관한 연구 (A Study of Web based Screening for Visual Stress Syndrome)

  • 장영건
    • 대한인간공학회지
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    • 제28권4호
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    • pp.91-99
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    • 2009
  • A visual stress may provoke migraine, cephalalgia, intervene a long term reading and learning capability and reduce the productivity of a laborer who uses computer for a good while. In this study, a web based screening tool for visual stress was developed, it applied to 72 visually normal young persons in parallel with traditional questionnaire about symptoms of visual stress. To estimate visual stress, It is proposed to measure difference of visual search time of Han Gul characters as targets between visual stressful pattern and non-visual stressful pattern as global background of characters. As a result of test, 5 subjects were screened whose mean visual search time in the stressful pattern with 6 CPD spatial frequency increase significantly more than in none stressful pattern(t-test, one-tailed, p=$1.0407\times10^{-11}$). 2 of them were diagnosed as mild visual stress syndrome in the clinic. None had visual distortion and 50% of subjects had visual discomfort in results of the questionnaire. Correlation between visual search time increase rate and normalized number of visual discomfort may be slight(C. coefficient=0.1355). This study may contribute as a basic research for screening person with migraine, visual reading disabilities and VDT syndrome. It is required to apply the test to visual reading disabilities, migraine with visual distortion and/or visual discomfort as well as normal person for higher reliability of the screening tool.

크기효과가 고려된 미소절삭시의 온도 및 응력특성에 관한 유한요소해석 (A Finite Element Analysis for the Characteristics of Temperature and Stress in Micro-machining Considering the Size Effect)

  • 김국원;이우영
    • 한국정밀공학회지
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    • 제15권10호
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    • pp.128-139
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    • 1998
  • In this paper, a finite element method for predicting the temperature and stress distributions in micro-machining is presented. The work material is oxygen-free-high-conductivity copper(OFHC copper) and its flow stress is taken as a function of strain, strain rate and temperature in order to reflect realistic behavior in machining process. From the simulation, a lot of information on the micro-machining process can be obtained; cutting force, cutting temperature, chip shape, distributions of temperature and stress, etc. The calculated cutting force was found to agree with the experiment result with the consideration of friction characteristics on chip-tool contact region. Because of considering the tool edge radius, this cutting model using the finite element method can analyze the micro-machining with the very small depth of cut, almost the same size of tool edge radius, and can observe the 'size effect' characteristic. Also the effects of temperature and friction on micro-machining were investigated.

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최근 10년간 간호사의 스트레스에 관한 국외연구 동향분석 (Trend Analysis of Nurses' Stress Based on the Last 10 Years of International Research)

  • 이복임
    • 한국직업건강간호학회지
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    • 제21권1호
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    • pp.27-36
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    • 2012
  • Purpose: The purpose of this study was to identify the trends of nurses' stress based on the last 10 years of international research and to suggest directions for future research. Methods: Fifty three articles between 2002 and 2011 were selected using key words such as 'nurse' and 'stress' from the PubMed and CINAHL. Results: The number of experimental studies increased. The nurses from the various fields were studied. Most studies used a reliable and valid tool for measuring stress of specific nursing staff. The Internet survey was recently used for a data collection method. Significant variables correlated with nurses' stress were categorized into 8 domains: Individual susceptibility, quantitative workload, qualitative workload, physical environment, organizational factors, and interpersonal conflict. Conclusion: In Korea, the next phase of research on nurses' stress needs to consider the experimental study design to find more specific causal relationships. Also, it is necessary to develop the nurses' stress tool for reliable and valid measurement.

인볼류우트 커터인선의 초기결손 예측에 관한 연구 (Study on the Analytical Prediction of Premier Chipping in Involute Gear Cutting Process)

  • 김재갑;김정두
    • 대한기계학회논문집
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    • 제16권7호
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    • pp.1266-1277
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    • 1992
  • 본 연구에서는 공구의 형상과 절삭조건에 따른 공구의 결손형태를 예측하기 위하여 현재 가장 널리 쓰이고 있는 인볼류우트커터의 결손형태를 절삭날의 응력분포 값으로 예측하고 실험에 의하여 검증함과 동시에 기어 절삭실험을 통한 공구 결손의 성장거동을 고찰하였으며, 또한 마멸과 결손이 발생함에 따른 절삭력의 변화와 평형을 관찰하여 상호관련성을 비교함으로써 인볼류우트 기어커터의 초기 결손을 해석적으로 예측하였다.

물리치료사의 업무 스트레스 현황과 대응수준 -부산지역을 중심으로- (An Analysis of Work Stress of Physical Therapist and Reaction)

  • 동종익;류황건;배성권
    • 보건의료산업학회지
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    • 제2권1호
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    • pp.37-55
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    • 2008
  • This study aims to enhance work efficiency and satisfaction by offering data that make a physical therapist cope with stress coming from the job efficiently by identifying and analyzing the job satisfaction and work stress perceived by a physical therapist, and the level of reaction of a physical therapist. The study distributed survey questionnaires to 300 physical therapists working in medical institutions in Busan via mail and by visit from March 3, 2007 by selecting them simply and randomly from the physical therapist list, and collected the questionnaires by March 20, 2007, 103 respondents were working at 17 general hospitals including a university hospital, 65 respondents at 12 medical centers, and 79 respondents at 39 doctor's offices. The study collected 251 copies, which showed the collection rate of 83.7%, and analyzed 247 copies (82.3%) excluding 4 copies of insincere answers. As a research tool for measuring job satisfaction the study used a tool employed for research into the job satisfaction of physical therapists who work at medical institutions in Gwangju, Jeonnam, and Jeonbuk by Kim Hee-Gwon(1992) and research regarding job satisfaction by Jeong Jeong-Hee(2004) as well as research regarding the factors of job satisfaction by Flippo(1980) & Seberhagen(1970) after adjusting the research tools to the purpose of the study. Also for questions about work stress, the study employed nurses' job stress measurement tool developed by Kim Mae-Ja and em Mi-Ok(1984) by modifying the tool to the purpose of the study, and for a measurement tool for reaction to stress, the study used a tool employed for research into reaction to stress of nurses at general hospitals by Choi Eun-Deok(2005) without modification. For data analysis, the study used the SPSS12.0 as a statistical method, and then used t-test or ANOVA for verifying actual numbers, percentile, average :score, standard deviation, rank, and difference. Also, the study conducted which is a post-test method for variables that show a significant difference at the level of p<.05 level after the analysis. The findings include the following. 1) The respondents' job satisfaction score was 3.21 points on the average (out of 5 full points). The peer relationship ranked the highest, posting 4.02 points on the average, and the job satisfaction with rewards was proven the lowest, posting 2.51 points. For the job satisfaction level by characteristics, there were significant differences (p<.05) in gender, hospital type, weekly working hours, monthly working days, number of patients per day, department in charge of therapy, and number of peers, and there was no significant difference in characteristics other than that. 2) The respondents' work stress score was 2.72 points (out of 5 full points) on the average. The respondents were shown to be under the highest stress when they suffered from excessive workload, posting 3.49 points on the average, and they were shown to be under the least stress when they had a conflict with peers at another department, recording 1.90 points on the average. for the job stress level by the characteristics of job, there was a significant difference in the reflection of job assessment(p<.05). 3) 1n respondents' reaction to stress, most of them were shown to make efforts in coping with stress, posting 2.80 points (out of 5 full points). For their experience of being wider stress, they answered that 'they felt depressed (2.85 points)" for their experience of coping with stress, they answered that 'they were indifferent to it or thought about something else' (2.62 points). Also, for their efforts in coping with stress, they answered that 'they were motivated to remove their strain by taking leave, playing, or using their preferences' (3.52 points), which ranked higher. For the level of reaction to stress by characteristics, there were significant differences by age, gender, marital status, total service years as a physical therapist, monthly working days, and department in charge of therapy(p<.05). It is necessary to offer correct information by conducting an in-depth analysis of the stressful situations of physical therapists who exert efforts in rehabilitating patients at hospitals by factor, and seeking management plans based on the research results. Also, it is necessary to develop a program for coping with stress efficiently for removing stress and to conduct research into the understanding and cooperation of administrators and persons in charge of physical therapists for reducing physical therapists' stress at hospitals.

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