• 제목/요약/키워드: tool

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회주철(GC250)의 고속가공을 위한 엔드밀공구의 형상 설계 및 가공성 평가 (Shape Design and Machinability Evaluation of Flat End mill for High Speed Machining of GC250 Material)

  • 이상용;김전하;강명창;김정석;강호연
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2002년도 추계학술대회 논문집
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    • pp.292-296
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    • 2002
  • In the present investigation, the improvement of processing efficiency in the high speed machining of GC250 is explored. This study is to evaluate the tool performance in difficult-to-material using the new developed tool. Tool performance evaluation are conducted by tool wear, surface roughness, chattering in machined surface. The tool wear of A type was smaller than B type. In type B tool the chatter mark was observed in machined surface. The good surface roughness was obtained in type A tool. Consequently, the tool performance of A type is better than B type.

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알루미나 세라믹 가소결재의 피삭성 -다이아몬드 및 CBN공구의 절삭 성능- (Machinability of Pre-sintered Alumina Ceramics)

  • 김성청
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 1996년도 춘계학술대회 논문집
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    • pp.41-46
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    • 1996
  • In this study, unsintered and pre-sintered low purity alumina ceramics were machined with various tools to clarify the machinability, optimum tool materials and optimum cutting conditions. The main conclusions obtained were as follows. (1)In the case of dry cutting, the sintered diamond and natural diamond tools exhibit better performance in machining of the ceramic pre-sintered at lower temperature, and the tool lives of both tools in machining the ceramics pre-sintered at high temperature becomes extremely short. (2)The performance of CBN tool becomes better in dry machining of the ceramics pre-sintered at higher temperature. (3)When the pre-sintered ceramics were wet machined with sintered diamond, the tool life becomes considerably long, and higher cutting speed can be used than in the case of the CBN and ceramic tools, the tool lives becomes shorter at wet cutting than at dry cutting, especially exhibiting extremely short tool life in wet cutting with ceramic tool.

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고속 볼앤드밀링에서 공구마모를 고려한 공구의 가공경사각 선정 (Selection of Machining Inclination Angle of Tool Considering Tool Wear in High Speed Ball End Milling)

  • 고태조;정훈;김희술
    • 한국정밀공학회지
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    • 제15권9호
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    • pp.135-144
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    • 1998
  • High speed machining is a key issue in die and mold manufacturing recently. Even though this technology has great potential of high productivity. tool wear accelerated by high cutting speed to the hardened materials is other barrier. In this research, we attempted to reduce tool wear by considering tool inclination angle between tool and workpiece. The boundary lines describing machined sculptured surfaces were represented by both of cutting envelop condition and the geometric relationship of successive tool paths. Chip cross section, and cutting length could be obtained from the calculated cutting edge and the rotational engagement angle. From the simulation results, machining inclination angle of tool of $15^\circ$ was good enough from the point of tool wear and cutting force, and this value was verified through the cutting experiment of high speed ball end milling.

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곡면 다듬질에서 접촉해석에 근거한 유연공우 경로 설정 (Determination of Flexible Tool Path in Curved Surface Finishing Based on Contact Analysis)

  • 조성산;이승영;유용균
    • 한국정밀공학회지
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    • 제17권11호
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    • pp.69-74
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    • 2000
  • Roughness of curved surfaces finished with flexible tools depends on the tool/work contact pressure and area. In this study, non-Hertzian closely conforming elastic contact theory is employed to analyze the tool/work contact and to generate a tool path producing a constant pressure at initial contact points. Finishing experiments on curved surfaced are conducted using the tool path. For comparison, curved surface finishing is also performed along the tool path producing a constant tool/work interference depth. It is demonstrated that the tool path of constant contact pressure improves the finished surface roughness.

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유한유쇼법을 이용한 미소절삭기구의 절삭인자 규명에 관한 연구 (A study on the effect of cutting parameters of micro metal cutting mechanism using finite element method)

  • 황준;남궁석
    • 한국정밀공학회지
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    • 제10권4호
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    • pp.206-215
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    • 1993
  • The finite element method is applied to analyze the mechanism of metal cutting, especially micro metal cutting. This paper introduces some effects, such as constitutive deformation laws of workpiece material, friction of tool-chip contact interfaces, tool rake angle and also simulate the cutting process, chip formation and geometry, tool-chip contact, reaction force of tool. Under the usual plane strain assumption, quasi-static analysis were performed with variation of tool-chip interface friction coefficients and tool rake angles. In this analysis, cutting speed, cutting depth set to 8m/sec, 0.02mm, respectively. Some cutting parameters are affected to cutting force, plastic deformation of chip, shear plane angle, chip thickness and tool-chip contact length and reaction forces on tool. Several aspects of the metal cutting process predicted by the finite element analysis provide information about tool shape design and optimal cutting conditions.

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미소직선 공구경로의 NURBS 변환 (NURBS Post-Processing of Linear Tool Path)

  • 김수진;최인휴;양민양
    • 대한기계학회논문집A
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    • 제27권7호
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    • pp.1227-1233
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    • 2003
  • NURBS (Non Uniform Rational B-Spline) is widely used in CAD system and NC data for high speed machining. Conventional CAM system changes NURBS surface to tessellated meshes or Z-map model, and produces linear tool path. The linear tool path is not good fur precise machining and high speed machining. In this paper, an algorithm to change linear tool path to NURBS one was studied and the machining result of NURBS tool path was compared with that of linear tool path. The N-post including both a post-processing and a virtual machining software was developed. The N-Post transforms linear tool path to NURBS tool path and quickly shades a machined product on OpenGL view, while comparing a machined surface with a original CAD one. A virtulal machined model of original tool path and post-processed tool path was compared to original CAD model. The machining error and machining time of post-processed NURBS tool path were investigated.

자종공무마모계측시스템개발 (System Development for Automatic Tool Wear Measurement)

  • Kim, Y.I.
    • 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.

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Optimal design for face milling cutter by simulation

  • Kim, J.H.;Lee, B.C.;Kim, H.S.
    • 한국정밀공학회지
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    • 제10권2호
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    • pp.76-85
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    • 1993
  • Based on the cutting force model, three-dimensional optimal design model was developed and optimal designed tool which is minimized cutting force is developed by computer simulation technique. In this model the objective function which is minimized resultant cutting force was used and the variables are radial rake angle, axial rake angle, lead angle of the tool. The cutting forces using conventional and optimal tools by simulation, are compared and analyzed in time and frequency domains. In time domain the cutting force of optimal tool in feed direction was more reduced and less fluctuated than that of conventional tool. Cutting forces of optimal tool in X-and Z-directions are shown a little increased than those of conventional tool. In frequency domain amplitude of insert frequency components of optimal tool in feed direction was more reduced than that of convent- ional tool. The amplitudes of insert frequency components of optimal tool in X-and Z-direction are a little increased than those of conventional tool. As the reduction of amplitude and fluctuations of the cutting force, Optimal tool is considered that tool life and surface roughness would be improved, and stable cutting would be expected.

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환자간호의 질 평가를 위한 돌봄(caring) 측정도구의 개발 (Development of a Measurement Tool of Caring to Evaluate Quality of Nursing Care)

  • 이병숙
    • 대한간호학회지
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    • 제26권3호
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    • pp.653-667
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    • 1996
  • It is important to find indicators of quality nursing care to establish the excellence of nursing practice and for the development of nursing as a profession. Caring is one of the indicators which can represent professional nursing care. The purpose of this study was to develop a measurement tool of caring that could be used as an instrument for the evaluation of quality of nursing care. The Target population for the developed tool of caring is the adult patient. The mearsurement tool of caring was developed through the following steps. (1) A list of caring behaviors was made using qualitative researches on caring that has been done in Korea. (2) Caring behaviors in nurses were selected using the list of caring behaviors developed from Watson's 10 factors of caring. (3) Items for the measurement tool of caring were developed using the caring behaviors of nurses (4) Content validity of the developed items was evaluated by an expert panel. (5) The mearsurement tool of caring was developed after a pilot study (6) Internal consistency, and construct validity of the developed tool were verified. (7) The mearsurement tool of caring with the items verified for the internal consistency and construct validity was confirmed. As a result of the study, a mearsurement tool of caring, composed of 27 items with 3 factors, was developed. The Reliability coefficient of the tool was. 9578. The tool is a 5 point Likert scale. The factors of the tool and the number of items for each factor are, 1) accessibility and availablility, 15 items ; 2) emotional support and giving information, 8 items ; 3) providing a protective environment, 4 items.

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Nutrition Evaluation Screening Tool: An Easy to Use Screening Tool for Hospitalised Children

  • Dokal, Kitt;Asmar, Nadia;Shergill-Bonner, Rita;Mutalib, Mohamed
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • 제24권1호
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    • pp.90-99
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    • 2021
  • Purpose: Nutrition screening is vital to ensure patients are appropriately managed in hospital. In paediatrics there is currently no universally accepted nutrition screening tool. The Nutrition Evaluation Screening Tool (NEST) was developed as an easy to use and practical screening tool for hospitalised children. We aim to evaluate compliance of the NEST and assess agreement of the NEST with the already validated nutrition screening tools, Screening Tool for Risk on Nutritional Status and Growth (STRONGkids), Screening Tool for the Assessment of Malnutrition in Paediatrics (STAMP) and the Subjective Global Nutritional Assessment (SGNA) tool. Methods: Retrospective review of 102 patient episodes at the Evelina London Children's Hospital. Electronic records were used to assess NEST compliance and to complete the nutrition tools for each patient episode. Cohen's kappa was used to determine the level of agreement between each nutrition tool. Results: There was moderate agreement between the NEST and the two screening tools, STRONGkids (κ=0.472) and STAMP (κ=0.416) for patients on initial screening at admission. 87.2% of patient episodes were NEST compliant within 24 hours of admission to hospital. Conclusion: The moderate agreement between these two already validated screening tools enhances the NEST's validity as a paediatric screening tool. The NEST had the strongest correlation with the SGNA tool compared to other screening tools. The NEST is user friendly screening tool for hospitalised children.