• 제목/요약/키워드: High Speed Precision Machining

검색결과 350건 처리시간 0.036초

볼엔드밀을 이용한 고속가공에서 가공환경 변화에 따른 열특성 평가 (Evaluation of thermal characteristics by cutting environments in high speed ball end-milling)

  • 이채문
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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    • pp.34-38
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    • 2000
  • The trend of cutting process today goes toward higher precision and higher efficiency. Many thermal/frictional troubles occur in high-speed machining of die and mold steels.In this paper, the thermal characteristics are evaluated in high sped ball end-milling of hardened steel(HRc42). Experimental work is performed on the effect of cutting environments on tool life and cutting temperature. Cutting environments involve dry, wet(20bar), compressed chilly air at -9$^{\circ}C$, compressed chilly air at -35$^{\circ}C$. The measuring technique of cutting temperature using implanted thermocouple is used. The cutting temperature is about 79$0^{\circ}C$, 35$0^{\circ}C$ and 54$0^{\circ}C$ in dry, wet and compressed chilly air at +9$^{\circ}C$, respectively. The tool life for compressed chilly air at -9$^{\circ}C$ is longer than all other cutting environments in experiment.

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유전 알고리듬을 이용한 소형 고속스핀들 시스템의 바-피더 지지부의 위치 최적선정 (Optimum Bar-feeder Support Positions of a Miniature High Speed Spindle System by Genetic Algorithm)

  • 이재훈;김무수;박성훈;강재근;이시복
    • 한국정밀공학회지
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    • 제26권11호
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    • pp.99-107
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    • 2009
  • Since a long work piece influences the natural frequency of the entire system with a miniature high speed spindle, a bar-feeder is used for a long work piece to improve the vibration characteristics of a spindle system. Therefore, it is very important to design optimally support positions between a bar-feeder and a long work piece for a miniature high speed spindle system. The goal of the current paper is to present an optimization method for the design of support positions between a bar-feeder and a long work piece. This optimization method is effectively composed of the method of design of experiment (DOE), the artificial neural network (ANN) and the genetic algorithm (GA). First, finite element models which include a high speed spindle, a long work piece and the support conditions of a bar-feeder were generated from the orthogonal array of the DOE method, and then the results of natural vibration analysis using FEM were provided for the learning inputs of the neural network. Finally, the design of bar-feeder support positions was optimized by the genetic algorithm method using the neural network approximations.

장구형 웜 나사의 절삭 엔드밀 공구 형상에 따른 치형 정밀도 분석 (Analysis of Tooth Profile Accuracy of Enveloping Worm Thread Depending on End Mill Tool Shape)

  • 강신준;김용환
    • 소성∙가공
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    • 제28권4호
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    • pp.183-189
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    • 2019
  • Cylindrical worm reducers are generally used in various fields and forms throughout the industry, and demand is increasing due to their role as an integral part of the industry. Market trends require high-load, high-precision components, and small-sized reducers with large loads. When using a cylindrical worm reducer, a reducer designed with a reduced center distance while maintaining the same output torque results in gear wear. To overcome this difficulty, an enveloping worm gear reducer is introduced and studied. In this paper, three types of end mill tools are used to evaluate the tooth profile accuracy for each tool shape during machining of the tooth profile for a non-developed surface worm thread. The effect of the endmill shape on the accuracy of the tooth profile was analyzed by performing 3D modeling of the surrounding worm tooth profile based on the Hindley method. In this study, we analyzed tooth profile accuracy, tooth surface roughness, and tooth surface machining time, etc. Through the study, efficient machining conditions for the enveloping worm gears and the influence of parameters on the process were presented.

엔드밀 원형 가공 시 런아웃에 따른 가공조건 최적화 (Optimization of Processing Conditions According to Run-out During End-mill Round Machining)

  • 이하늘;최희관;김영신;전의식
    • 한국기계가공학회지
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    • 제20권1호
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    • pp.57-65
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    • 2021
  • With the increased utilization of CAM programs, end-mill processing is most commonly used for machining and metal processing. In particular, hole or shaft machining has high assembly precision, which inevitably leads to high utilization of end mills. However, the analysis of quality characteristics according to the process conditions of end mills is not performed systematically at the site, causing poor quality and productivity. The most influential factor of quality is the runout of the end mill. In this paper, the number of turns of the end mill, number of tool blades, cutting direction, and artificial runout volume were determined to identify the correlation between the epicenter, cylindricality, and surface roughness. Two types of end mills, three levels of runout, three levels of rotational speed, and two cutting directions were considered and 36 rounds of hole processing were conducted. For the analysis of shape characteristics according to the set process variables, the experimental planning method was applied to the measured specimen and the processing characteristics were analyzed according to the runout of the end mill through correlation analysis.

연속파형 Nd:YAG 레이저를 이용한 SM45C 맞대기 용접의 공정 변수 (Process Parameters of Butt Welding of SM45C using a Continuous Wave Nd:YAG Laser Beam)

  • 유영태;노경보;오용석;김종신;임기건
    • 한국정밀공학회지
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    • 제20권7호
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    • pp.44-55
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    • 2003
  • The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. This paper describes the machining characteristics of SM45C carbon steel welding by use of an Nd:YAG laser. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. The major process parameters studied in the present laser welding experiment were position of focus, travel speed and laser power. Optical microscope and SEM were used to investigate the microstructures of the welded zone. The experimental results showed that penetration depth of the welding process increases with laser power. Both the microstructural investigation and the theoretical calculations indicated that materials undergoes a very high heating and cooling cycle during welding process. It was also found that the austenite nucleation takes place at the initial stage and the completion temperature of austenite transformation is much higher than in the case of the arc welding.

변곡점에서 공작기계의 윤곽오차 (Contouring Error of a Machine Tool at Inflection Points)

  • 안일혁;김성수;민경석;최우천;홍대희
    • 한국정밀공학회지
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    • 제20권11호
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    • pp.166-170
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    • 2003
  • Contouring errors are important especially for high speed and precision machining. In this study, contouring errors along contours having inflection points are studied. When a table of a machine tool moves along a circular path, acceleration acts toward the center of the circle. Thus, at inflection points, acceleration as well as inertia force changes its direction abruptly. The effect of inertia force on the contouring error is investigated in this study. It is found that the contouring error at an inflection point is proportional to the acceleration. This result can be useful in determining contouring errors along general paths.

원통 플런지 연삭시 연삭력에 관한 실험적연구 (Monitoring of Grinding Force in Plunge Grinding Process)

  • 박종판;박철우;이상조
    • 대한기계학회논문집A
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    • 제23권6호
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    • pp.881-894
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    • 1999
  • Cylindrical plunge grinding is widely used for final machining process of precision parts such as automobile, aircraft, measurement units. But in order to make parts which have high precision accuracy and high surface integrity, it is necessary to consider grinding characteristics due to accumulation phenomena of grinding wheel in plunge grinding process. In this study, in order to examine closely plunge grinding process, grinding power, grinding force, real depth of cut are monitored in transient state, steady state and spark out state. As the result, it is shown that grinding power and force are affected by dressing condition, depth of cut and speed ratio and that there exist threshold grinding force and it also affected by dressing condition. Also considered effects of grinding conditions on surface roughness and roundness of workpiece

연마제 워터 제트에 의한 쿼츠의 절단특성 (Cutting Characteristics of Quartz by Abrasive Waterjet)

  • 진윤호;정남용;김경훈
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 추계학술대회
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    • pp.922-927
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    • 2004
  • Abrasive waterjet (AWJ) cutting is an emerging technology for precision cutting of difficult-to-machining materials with the distinct advantages of no thermal effect, high machinability, high flexibility and small cutting forces. This paper investigated theoretical and experimental cutting characteristics associated with abrasive waterjet cutting of quartz GE214. It is shown that the proper variations of several cutting parameters such as waterjet pressure, cutting speed and cutting depth improve the roughness on workpiece surfaces produced by AWJ cutting. From the experimental results by AWJ cutting of quartz GE214, the optimal cutting conditions to improve the surface roughness were proposed and discussed.

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다이아몬드휠의 드레싱 조건에 관한 연구 (A Study on the Dressing Conditions of Diamond Wheel)

  • 하상백;정재극;이종찬
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1997년도 춘계학술대회 논문집
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    • pp.1020-1024
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    • 1997
  • Recently the use of ceramic materals has been greatly increased in the industries. But machining of the ceramics is quite unproductive because of their high stength,high hardness,and brittleness. The efficiency of the grinding operation of ceramics depends on the preparation of diamond grinding wheel, i.e.,truning and dressing. This paper describes some experimental results on the dressing conditions of diamond grinding wheel. The dressing performance is evaluated by the magnitude of normal grinding force. The better dressed wheels result in the lower normal grinding forces. The dressing performances of copper plate and aluminum oxide dressing stick are compared. The optimum dressing conditions including the grit size of dressing sticks, the depth of the dressing operation, and the dressing speed qre determined.

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볼나사 지지 구조와 베어링 조합 배열에 관한 연구 (A Study on Structure of Support Ball Screw and Arrangement of Combined Bearing)

  • 홍성오;정성택;조규재
    • 한국공작기계학회논문집
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    • 제11권3호
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    • pp.51-56
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    • 2002
  • In order to achieve high precision machine tools, Performance enhancement of feed drive systems is required. One of the important technical issues is how to decrease thermal expansion of ball screw in proportion to the increase of machining speed. When measuring force of stretch of ball screw, since not only actual expansion and the value of bending have to be considered, it is impossible to define the exact value of expansion. In addition, support bearings of ball screw gain considerable force in axial direction. It also generates thermal expansion on the ball screw, and deteriorates the performances of the hearings. In conclusion, it is impossible to give the pretension enough to absorb all the elongation due to thermal expansion generated during machine is running. If given bed column and saddle are all bent to chance machine accuracy, and the support bearings of ball screw is damaged.