• 한국자동차공학회논문집
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• 제24권1호
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• pp.67-73
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• 2016

The application of titanium has been gradually rising because the utilizing ranges for low weight and high strength are rapidly increased by the need for improving the fuel economy in production industries such as the aviation and automotive in recent. The purpose in this study is to investigate the appropriate cutting conditions on the life of flat and round end mills by measuring the maximum cutting temperature relative to the machining time, and calculating the wear rates of cutting tool with the spindle speed and feed rate of vertical machining center as a parameter in the titanium roughing cut machining which is widely used in critical parts of aircraft, cars, etc. When the wetted roughing cut machining of titanium with a soluble cutting oil is conducted by the flat and round end mills, the maximum cutting temperatures for a variety of spindle speed and feed rate are measured at ten-minute intervals during 60 minutes by an infrared thermometer, and the wear rates of cutting tool are calculated by the weight ratios based on tool wear before and after the experiment. It is found that the maximum cutting temperature and the wear rates of cutting tool are raised as the cutting amount per tool edge is increased with the rise of feed rate, in this experimental range, and as the frictional area due to the rise of contacting friction numbers between tool and specimen is increased with the rises of cutting time and spindle speed. In addition, the increasing rate of maximum cutting temperature in the flat and round end mills are the highest for the cutting time from 50 to 60 minutes, and the wear rate of cutting tool in the flat end mill is 1.14 to 1.55 times higher than that in the round end mill for all experimental conditions.

• 한국컴퓨터정보학회논문지
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• 제14권10호
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• pp.55-61
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• 2009

본 연구는 웨이퍼 다이싱 공정의 가공정보들을 수집하여 실시간으로 관리하는 생산시점의 정보관리시스템에 대한 연구이다. 개발한 시스템은 POP용 단말기, 라인 컨트롤러 및 네트웍으로 구성된다. LAN은 상위관리시스템을 연결하며, RS485 네트웍은 하위시스템인 라인 컨트롤러와 단말기를 연결한다. 라인 컨트롤러는 POP 단말기와 서버를 연결하기 위해 사용된다. 웨이퍼의 실시간 가공정보는 기계, 제품, 작업자의 정보발생원들로부터 얻고, 이들은 최적절삭조건을 계산하기 위하여 사용된다. 수집된 정보는 절삭속도, 순수의 여부, 처리 중인 블레이드의 누적 절삭량 및 불량 웨이퍼의 수이다. 상위시스템의 생산계획정보는 웨이퍼 가공공정의 관리를 위해서 현장에 전달되며, 생산결과정보는 현장에서 수집하여 서버로 전달되고 필요한 형태로 정보가 가공되어 공정관리용 정보로 사용된다. 개발한 시스템을 반도체 웨이퍼 가공공정에 적용한 결과, 생산진전상태, 각 기계에 대한 작업시간 및 비작업시간의 해석 및 웨이퍼 불량률의 해석이 가능하며, 이들은 다이싱 공정의 품질 및 생산성 향상을 위한 생산공정 관리정보로 활용할 수 있을 것이다.

• 한국공작기계학회논문집
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• 제16권4호
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• pp.64-70
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• 2007

This paper presents a study on the effects of feedrate and shotpeening on the fatigue life of A17075-T6 specimens. For this purpose, six groups of specimens, each of which consists of eight specimens, were first machined at six different feedrates(0.05, 0.10, 0.15, 0.20, 0.25, 0.30mm/rev). Half of eight specimens in each group were then peened and the others remained un-peened. Then, the fatigue life was measured by using 4-point rotatry bending machine. One observation was that the fast the feedrate was, the large the diameter of a specimen was. To make sure that the bending stress was the same in all cases, different loading conditions were thus applied to specimens based on their diameters. Next, comparison of fatigue life among twelve sets of specimens(six groups times two sets, peened and un-peened) was performed. Finally, based on machining cost analysis, a guideline for optimal feedrate was presented.

• 한국기계가공학회지
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• 제13권4호
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• pp.99-105
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• 2014

The domestic airline industry undertakes the production of finished products by assembling existing self-described components via a design process which involves assembly and production steps, after which many of the finished products are exported. However, high reliability and stability must be guaranteed, because customers require high-precision components at the time of manufacturing. In the aircraft parts industry, the mass production of high-value-added parts is limited. Therefore, a small production scale depending on the part is used, as many types of conventional CNC lathe machines with X-axis and Z-axis as well as Z-axis and C-axis CNC milling are used. The parts also rely on high-pressure air to increase production. The most important factors are good stability during processing, as high-precision parts are required, as noted above. It was found that as the C-axis rotation speed increased, the diameter of the cutting tool decreased with a decrease in the surface roughness, while the workpiece rotation speed increased with an increase in the surface roughness.

• 한국기계가공학회지
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• 제18권10호
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• pp.27-33
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• 2019

The aviation industry has grown beyond the simple processing and assembling of aircraft parts and now designs and exports finished aircraft. In this study, the vertical CNC milling rotational speed and feed rate were parameters to investigate the life of tools according to their shape: (flat, round, and ball end mill) in the rough cutting of titanium. These tools are widely used in aircraft manufacturing and assembly. The purpose of this study is to measure the cutting temperature generated during the cutting process and calculate the rate of tool wear. This will be accomplished by measuring the tool weight before and after cutting the specimen and to compare it with the results of previous studies. Our study showed that the maximum cutting temperature increased as cutting time, tool rotational speed, and feed rate increased. The highest cutting temperatures were recorded for the ball, round, and flat end mill, respectively. Tool wear for the ball, round, and flat end mill increased as the speed and feed rate increased. The flat end mill exhibited the highest rate of wear from a minimum of 0.62% to a maximum of 2.88%.

• 한국도로학회논문집
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• 제10권4호
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• pp.225-234
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• 2008

본 연구는 아스팔트 혼합물의 변형강도에 대한 적정 하중재하속도를 선정하기 위하여 수행하였다. 이를 위하석 직경(D) 40mm, 하단의 원형 절삭반경(r)을 10.0mm의 하중봉으로 Kim test의 하중재하속도를 분당 10mm, 30mm, 50mm, 70mm로 하여 변형강도를 측정하고 반복주행시험을 수행하여 얻어진 소성변형 특성치와의 상관관계에 대하여 회귀분석을 수행하였다. 하중재하속도별 변형강도 값은 하중재하속도가 증가함에 따라 변형강도도 증가하는 경향을 보였다. 이것은 하중재하속도가 변형강도에 미치는 영향이 큰 요소임을 알 수 있었다. 하중재하속도에 따른 변형강도와 반복주행시험 결과인 최종침하깊이 및 동적안정도와의 상관성 분석을 통해 30mm/min의 하중재하속도가 가장 적합한 것으로 나타났다. 하중 30mm/min 하중재하속도가 불가능한 시험기의 30mm/min 하중재하속도에서의 변형강도는 제안된 환산계수를 적용해야 한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.321-327
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• 1993

In order to maintain the cutting force at a desired level during peripheral end milling processes in spite of variation of the depth of cut and other machining conditions, a feedrate override. Apaptive Control Constraint (ACC) system are developed. Feedrate override was accomplished by a developed MMC board and PMC interface techniques. Nonlinear model of the cutting process was linearized as an adaptive model with time varying paramrters. Integral type estimators were introduced for on-line identification of cutting and control parameters in peripheral and milling processes. Zero Order Jold (ZOH) type degital control methodology which uses pole-placement concepts was applied for the ACC system. Performance of the developed ACC system was confirmed on the vertical machining center equipped with FANUC OMC for a large amount of experiment

• 산업경영시스템학회지
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• 제33권4호
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• pp.153-158
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• 2010

This study presents a single machine scheduling algorithm to minimize total cost(lateness cost, earliness cost and failure cost) by controlling machining speed. Generally, production scheduling uses the information of process planning and machining speed is not changed at production scheduling. And failure cost is not consider for scheduling algorithm. Therefore, the purpose of this study is to consider the change of machining speed for efficient production scheduling. And performance criteria for algorithm considers total cost. Especially, failure cost of product by increasing machining speed is considered.

• 한국공작기계학회논문집
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• 제11권2호
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• pp.95-102
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• 2002

Due to the development of the CNC machine tool and CAM software, sculptured surface machining can be broadly used in die and mold industries and ball end milling process is often used for the sculptured surface machining. It is found out how feedrate affects the precision of the machining and also tried to study the most suitable feedrate in specific cutting condition. Two eddy current sensors were used far measuring tool deflections of X, Y axis, dynamometer for cutting force and roundness tester for roundness. It was found that the tool deflection is getting better as tool path is going to further from the center of convex surface. The reason is that the cutting force is increased as the tool approaches to the center. Examining the roundness, cutting force and tool deflection characteristics, it was found that the most suitable feedrate is 90mm/min in convex surface and 120mm/min in concave surface.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.471-474
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• 2004

In this paper, a NURBS surface interpolator is proposed which can deal with shapes defined from CAD/CAM programs on a surface basis and can improve contour accuracy. The proposed interpolator is based on newly defined G-codes and includes online tool-path planning suitable for NURBS surface machining. The real-time interpolation algorithm, considering an effective machining method for each machining process and minimum machining time, is executed in an online manner. The proposed interpolator is implemented on a PC-based 3-axis CNC milling system and evaluated through actual machining in terms of machining time and regulation of feedrate and cutting force in comparison with the existing method.