Tool Chipping Detection Using Peak Period of Spindle Vibration During End-Milling of Inconel 718

Gu-Seon Kang,Seung-Gi Kim,양기동,박경희,Dong Yoon Lee 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.11

This paper presents a new approach to detecting tool chipping by analyzing peak period of spindle vibration, for changing the tool securely before the occurrence of a tool fracture. Peak period analysis refers to the observation of time differences for adjacent peak values, which gives the quantitative variation in time domain. Peak period refers to the time difference for adjacent peak values and indicates changes of frequency component based on the tool condition, thus, it can be used to monitor tool condition. During the end-milling of Inconel 718, monitoring variables such as cutting force, spindle vibration, and spindle current are monitored with sensors. The correlations of monitoring variables are analyzed by comparing them from the perspective of machining pass and tooth period. The spindle vibration is used for detecting the tool chipping and then the peak periods at each machining pass are featured with a statistical value. The result is significantly successful for detecting tool chipping. As chipping occurs in the tool, the magnitude of the feature value increases significantly. Furthermore, the real-time chipping detection capabilities of the proposed method are tested.

다양한 스톤 치핑에 의한 차량하부 손상예측

은효준(Hyojun Eun),추용주(Yongju Chu),이승엽(Seung-Yop Lee) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

In these days, there is a paradigm shift from internal-combustion-engine vehicles to electric vehicles. Most electric vehicles developed include batteries mounted at the bottom, near the rear wheels. Hence, the robust design of underbody parts against the impact of external bodies or random stone chipping need to be made. In this study, the mathematical modeling and statistical probability analysis of stone chipping and tire slip are performed for identifying and confirming the critical zones of the vehicle underbody that may be damaged by stone chipping. Thereby, stone chipping can be predicted by simulations using the employed mathematical model, before conducting experimental verification using the existing methods. Furthermore, the development cost and time can be reduced because the elements of the designed underbody can be analyzed for robustness, and the safety factor can be established during the design stage.

[응용논문] 다구찌 기법을 적용한 Stone Chipping에 의한 변형량 최소화를 위한 환경 요인 분석

추용주(Yong-Ju Chu),은효준(Hyo-Jun Eun),정시욱(Si-Uk Jung),이승엽(Seung-Yop Lee) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.7

Most electric vehicles manufactured these days include battery packs and powertrain parts mounted at the bottom near the rear axle or rear wheel. In this study, we analyzed and identified the main factors for determining stone chipping deformation, which causes the unwanted destruction of underbody parts while driving electric vehicles. By analyzing the average level on the stone chipping phenomena and signal-to-noise ratio, the influence of external impact factors(e.g., velocity, mass, shape, and material property) on stone chipping deformation was confirmed based on the Taguchi method. Based on the analysis of the stone chipping impact diagram, we can propose a design guideline for the underbody parts in order to reduce the development cost and time.

LCD 패널의 응력 해석을 통한 단순화 칩핑 허용균열 길이 예측

김주희,명만식 대한기계학회 2019 大韓機械學會論文集A Vol.43 No.12

In this study, we assessed the effect of chipping generated in the process of cutting of an LCD panel and the effect of abrasives used to remove such chipping. For this, stress changes of 9- and 4-inch wide LCD panels with external weights were measured for defects; further, ground and non-defective LCD panels were also assessed. From the results, the chipping on the LCD panel was observed to increase stress locally and weaken the hardness, but the grinding for removal of chipping relieved the concentration of stress, similar to that of the non-defective panel. LCD 패널 제작과정에서 다양한 칩핑이 발생한다. 이는 초기 균열의 형태로 패널의 내구성에 영향을 미칠 수 있다. 본 연구에서는 칩핑이 LCD 패널의 내구성에 미치는 영향을 확인하고 칩핑 제거를 위해 수행되는 연마가공의 효과를 확인하였다. 이를 위해 외부 하중에 대한 9인치와 4인치 LCD 패널의 응력 변화를 연마 가공된 LCD 패널과 가공되지 않은 패널에서 비교하였다. 결과적으로 LCD 패널에 발생한 칩핑은 국부 응력집중 현상으로 인해 내구성이 약화되는 것을 확인하였다. 칩핑 제거를 위한 연마 작업은 손상이 없는 패널과 같이 응력집중 현상이 완화되는 것을 확인하였다.

손상 LCD 패널의 응력 해석을 통한 허용균열 예측

김주희(Ju Hee Kim),명만식(Man Sik Myeong) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

In this study, we figured out the effect of chipping generated in the process of cutting off LCD panel and the effect of grinding for removal chipping. For this, stress change of 9 inches LCD panel with external weight was measured on defected LCD panel, Grinded LCD panel and indefective LCD panel each. As a result, the chipping on LCD panel rise stress locally and weaken hardness, but the grinding for removal the chipping relieve concentration of stress as indefective panel.

마이크로 포커스 X-ray CT를 이용한 콘크리트 손상균열의 정량적 평가

정자혜 ( Jahe Jung ) 대한지질공학회 2018 지질공학 Vol.28 No.3

본 연구에서는 치핑작업중에 콘크리트에 발생할 수 있는 손상균열을 정량분석하기 위해 X-ray CT 이미지를 이용하는 방법을 제안하고자 한다. 이를 위해 치핑작업을 수행한 후, 균열이 발생한 콘크리트 블록을 코어링하여 직경 50 mm, 길이 100 mm의 시편을 준비하였다. 그 후 마이크로 포커스 X-ray CT 촬영을 하여 얻은 이미지를 3D 이미지로 재구성(reconstruction)하였다. 이렇게 얻어진 3D CT 이미지에 3DMA (3 Dimensional Medial axis Analysis)법을 적용하여, 손상 평가 파라메타로 시편의 위치에 따라 균열의 성질을 평가하여 손상을 분석하였다. 분석결과 치핑에 의한 손상은 치핑 표면으로부터 3 cm 깊이까지 발생한 것으로 나타났다. 또한 CT이미지 공간분석법에서 사용되는 여러 파라메타 중 공극률 지표(Porosity index), Burn number 그리고 Medial axis 의 파라메타를 이용해 치핑표면 근처의 손상 분석이 가능하다는 것이 확인되었다. 이 방법은 내부구조에 변화가 발생한 암석을 대상으로 한 연구에서도 비파괴 상태로 내부의 균열 평가, 가시화에 적용가능하다. This study developed a method to quantitatively measure the size of cracks in concrete using X-ray CT images. We prepared samples with a diameter of 50 mm and a length of 100 mm by coring cracked concrete block that was obtained by chipping. We used a micro-focus X-ray CT, then applied the 3DMA method (3 Dimensional Medial axis Analysis) to the 3D CT images to find effective parameters for damage assessment. Finally, we quantitatively assessed the damage based on sample locations, using the damage assessment parameter. Results clearly show that the area near the chipping surface was damaged to a depth of 3 cm. Furthermore, X-ray methods can be used to evaluate the porosity index, burn number, and medial axis, which are used to estimate the damage to the area near the chipping surface.

Study on the Influence of Variation of Contact Arc Zone on the Single-Pass Sawing of Sapphire Wafer

Jianyun Shen,Lang Lu,Yuanyuan Gong,Xipeng Xu 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.9

Single-pass sawing (SPS), a significant cutting process widely used in the manufacturing of optical components in optoelectronic fields, which can greatly improve the quality of products by reducing the proportion of edge chipping. In this paper, the mechanism of SPS was introduced by a novel approach of deep analysis of the variation of the contact arc zone. Setting sapphire wafers as the workpiece, this study performed the comparative experiments in three specific arc zones, which would further make a thorough inquiry on the related machining mechanism. The difficulty degree of machining and the topography of surface quality during SPS process were also analyzed. The difficulty degree of machining was reflected by the sawing force ratio, and the machining surfaces of sapphire wafers were compared by SEM and Digital Microscope. The results indicate that the lower the arc is, the easier it can be machined during SPS. And the best surface quality appears in Arc 2 (arc angle = 20°), which can be set as an excellent reference for the machining of other materials during SPS. The single-pass sawing mechanism is also derived on the basis of the traditional cutting mechanism model, which will further serve as useful references to both the industrial machining and the academia.

초내열합금 Inconel의 가공성 평가

정경효,원종식,정윤교 國立 昌原大學校 産業技術硏究所 1996 産技硏論文集 Vol.10 No.-

Inconel, super heat-resistant alloy is superior in the toughness and the creep strength. It can especially endure high temperature and corrosion. It has been, therefore, broadly used in the various fields of atomic industry, aerospace, industrial mechanics and automobile etc. But such inherent properties as high temperature strength, an affinity with tool materials and low heat-conductivity etc. of Inconel alloy 600 degrade machinability. As a result, they cause many problems in the cutting process. In this study, machinability of Inconel alloy 600 was estimated on stand points of cutting force, tool wear and welding of chip for the cutting edge. Inconel alloy 600 was cut by precision high-speed lathe and tool material was used coated tungsten carbide insert(CTCI) and ceramic insert(CI) to be done in general. Cutting force is measured by the piezo type tool dynamometer and cutting edge is observed by scanning electron microscope(SEM). As a experiment result, obtained conclusions as follows. (1) In the case of cutting Inconel alloy 600 with CTCI, value of cutting force is similar its of SM45C. In this case, however, we can not avoid the cutting trobles that is ; the large width of fluctuations for cutting force and welding of cutting chips for cutting edge because of the toughness of the material. (2) In the case of using CI, the brittleness of the tool resulted in chipping. (3) Available cutting conditions of Inconel alloy 600 for CTCI and CI were established.

Utilization of woody pruning residues of apple trees

Najibeh Gilanipoor,Rafaele Spinelli,Ramin Naghdi,Akbar Najafi 한국산림과학회 2020 Forest Science And Technology Vol.16 No.4

Utilize agricultural residues from pruning brings many advantages including employment, social and economic benefit, rural development, natural forest protection, increased energy efficiency, and lower costs of raw material for the production of particleboard industry. In this study, the use of wood utilization of pruning residues from apple trees has been investi�gated by using chipping at the landing chipping methods (LCMs) and farm chipping meth�ods (FCM). These methods were conducted on seven farms, totaling 9.2 ha. A time study was used to estimate operation time and cost. Transportation of chips from the study area to factories was done with semi-trailers, trucks, and pickup trucks. The residue yield was between 1.8 and 2.0 green ton per hectare. The maximum time was related to chipping and the collection of residues and the most delay was mechanical. The residues were collected, chipped, and transported to the particleboard factory at a cost between US$10.18 and US$19.46 per ton, and the profit rate between US$15.5 and US$24.8 per ton depending on chipping methods and secondary transport system. Cost and the total time of LCM were lower than the FCM, and also production rate of LCM was higher than the FCM; therefore, this method was more effective in processing residues from apple trees. Regression techni�ques showed that in LCM, the effect of diameter and age was significant on residue process�ing time and in FCM, the effect of diameter, age, residue density, and functional the area was significant in residue processing time.

모래에 의한 차량 하부 스톤치핑 현상에 대한 실험 연구

신정훈(Jeong Hoon Shin),손정현(Jeong Hyun Sohn) 한국자동차공학회 2020 한국 자동차공학회논문집 Vol.28 No.5

Stone-chipping can result into cracks in the underbody of the vehicle, thus exposing the underbody to air corrosion. Corrosion can reduce the durability of the vehicle. To address this problem, many studies have been conducted to simulate the stone-chipping phenomena. Previous research showed simulation results of the stone-chipping phenomena, though they were not verified with experiments. In this study, the experimental setup was established to represent the stone-chipping phenomena and experimental results were compared with earlier studies that were obtained from a theoretical perspective. The scattering angle and the velocity of the particles were measured by using a high-speed camera. The rotational speed of the tire was set at 100, 110, 120, 130, and 140 RPM, respectively. The differences between the experiments and previous theoretical results ranged from 12 % to 20.4 %. Therefore, the theoretical approach may be modified in future studies to obtain more accurate results.