• Title/Summary/Keyword: Turning test

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An Experimental Study on the Turning Property of Welded Material (용접부의 선삭특성에 관한 실험적 연구)

  • Jang, Bok-Deuk
    • Journal of the Korean Society for Precision Engineering
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    • v.3 no.3
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    • pp.13-21
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    • 1986
  • Turning property of metal is affected by the cutting condition, tool geome- try and cutting material. But the turning property of welded material is not welknown. Welded structures usually contain nonhomogeneity, defects and resi- dual stresses due to differential contraction between welded metal and base metal. In this paper, authors conducted the experimental test on the turning property, by changing turning condition and welding electrodes of the welded specimens. The results obtained in these experimental tests are as follows; (1) Within the limit of this experimental test, the cutting force of the weld zone is bigger than that of base metal, and this phenomena is caused by the different mechanical property of the weld zone. The range of the variation of cutting force in the weld zone is caused by the nonhomogeneity of the weld zone, respectively. (2) The surface roughness follows the general characteristic of the effect of cutting condition on the surface roughness and the surface roughness of the weld zone shows coarse surface comparing with that of the base metal. (3) The specimen welded by the electrode E4301, shows worse cutting property than that of E4361 and E4313.

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A FAMILY OF TESTS FOR TREND CHANCE IN MEAN RESIDUAL LIFE WITH UNKNOWN TURNING POINT

  • Na, Myoung-Hwan;Kim, Jae-Joo
    • Proceedings of the Korean Society for Quality Management Conference
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    • 1998.11a
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    • pp.259-268
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    • 1998
  • A family of test statistics is proposed for testing whether or not the mean residual life(MRL) changes its trend. We do not assume that the turning point or the proportion before the turning point is known. This family includes the test statistic proposed by Aly (1990) and Hawkins, Kochar and Leader (1992) for complete samples. We establish the asymptotic null distribution of test statistics and obtain asymptotic critical values of the asymptotic null distribution using Durbin's approximation. We study Monte Carlo simulation to compare the proposed tests with previously known tests.

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A Study on the Limitation of the Action to Avoid Collision for Super Huge Vessel, Based on Result of Her Crash Astern and Turning Tests (초대형선의 충돌피항동작에 관한 고찰 -TURNING AND CRASH ASTERN TEST의 결과를 중심으로-)

  • Koo, Hong
    • Journal of the Korean Institute of Navigation
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    • v.5 no.1
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    • pp.25-35
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    • 1981
  • Since 1960 tankers and bulk carriers have rapidly increased in size up to 500, 000 dwt. in operating as main system of transportation for the international trade at sea, and studies are doing carried out by various groups with a view to increasing the size still further. However, the service speed of these ships has remained almost constant, and steering devices of them have nearly not changed, comparing with regular size of a dry cargo ship. This creats the dituation where stopping distance and advance are proportionally longer for larger ships. In case of collision at sea, these vessels have been arised some serious casualties, such as sinking, fire and oil pollution. This paper analyzers a study for the handling of super huge vessels to avoid collision at sea, basing on the results of the crash astern test and turning test of them.

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Hydrodynamic evaluation for developing the inflatable kayak (인플래터블 카약 개발을 위한 유체역학적 성능평가)

  • Hah, Chong-Ku;Lim, Lee-Young;Ki, Jae-Seok
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.6
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    • pp.623-630
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    • 2013
  • This study was to evaluate hydrodynamic performance evaluation between an abroad product, a developed inflatable kayak and new developed kayaks. In order to test, inclining and turning trial test were carried out in the Ocean engineering Basin. Also, resistance test was carried out using a reduced scale model in the circulating water channel. In conclusion, stability of KONA was evaluated was the most greatest, the coefficient of resistance and center of gravity from RD-FK-12 were considerable, and turning performance of RD-FK-11 was greater than this of KONA and RD-FK-12.

Turning Behavior of Tractor-Trailer System by Computer Simulation (컴퓨터 시뮬레이션에 의한 트랙터와 트레일러의 선회운동)

  • Kim, J.H.;Choi, C.H.
    • Journal of Biosystems Engineering
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    • v.16 no.4
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    • pp.346-354
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    • 1991
  • Turning behavior of tractor-trailer system was studied to guide the tractor and trailer. Based upon kinematic relationship between the tractor and the trailer, a mathematical model was developed and analyzed by computer simulation. A field test was carried out to verify the mathematical model. Following conclusions were drawn from this study. 1. A mathematical model and a simulation program for turning behavior of tractor-trailer system were developed. 2. The results of the field tests showed that the RMS errors were less than 0.33m and the mathematical model based upon kinematic relationship can be used for mapping guidance system for tractor and trailer. 3. As the steering angle was increased, the turning radius was decreased. When the tractor travelled at the low speed, the travel speed of the tractor did not affect turning radius but did affect running time and stability for steering. 4. When the tractor travelled under the critical velocity, the towed trailer followed smoothly. When the the tractor travelled faster than the critical velocity, the towed trailer oscillated. The critical velocity was determined from the specification of the tractor and the trailer.

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An Evaluation of Factors on the Influence Roundness in Turning Based on the Taguchi Method (다구찌 방법에 기초한 선삭에서 진원도에 영향을 미치는 인자에 관한 평가)

  • Kang, Shin-Gil;Lee, Chang-Ho;Jang, Sung-Min
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.4
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    • pp.495-501
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    • 2011
  • The purpose of this study is to improve the roundness of CNC turning so that helps the operator to choose the right turning conditions to produce a product with the given parameters. This paper focuses on determining the optimal levels of machining factors for circular shaft with CNC turning. For this purpose, the optimization of factors is performed based on experimental design method. A design and analysis of experiments are conducted to study the effects of these factors on the roundness by using the SIN ratio, analysis of ANOVA, and F-test. Factors, namely, fixed pressure, wall thickness, depth of cut, and feed rate are optimized with consideration of the roundness. The boring tool used in this study is a tungsten carbide coated. The material of workpiece is Al6061 and the machining method is dry cutting.

Analysis of Cutting Properties with Reference to Amount of Coolant used in an Environment-Conscious Turning Process

  • Yang, Seung-Han;Lee, Young-Moon;Kim, Young-Suk
    • Journal of Mechanical Science and Technology
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    • v.18 no.12
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    • pp.2182-2189
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    • 2004
  • In the recent years, environmentally conscious design and manufacturing technologies have attracted considerable attention. The coolants, lubricants, solvents, metallic chips and discarded tools from manufacturing operations will harm our environment and the earth's ecosystem. In the present work, the Tukey method of multiple comparisons is used to select the minimum level of coolant required in a turning process. The amount of coolant is varied in 270 designed experiments and the parameters cutting temperature, surface roughness, and specific cutting energy are carefully evaluated. The effects of coolant mix ratio as well as the amount of coolant on the turning process are studied in the present work. The cutting temperature and surface roughness for different quantity of coolant are investigated by analysis of variance (ANOVA) - test and a multiple comparison method. ANOVA-test results signify that the average tool temperature and surface roughness depend on the amount of coolant. Based on Tukey's Honestly Significant Difference (HSD) method, one of the multiple comparison methods, the minimum level of coolant is 1.0 L/min with 2% mix ratio in the aspect of controlling tool temperature. F-test concludes that the amount of coolant used does not have any significant effect on specific cutting energy. Finally, Tukey method ascertains that 0.5 L/min with 6% mix ratio is the minimum level of coolant required in turning process without any serious degradation of the surface finish. Considering all aspects of cutting, the minimum coolant required is 1.0 L/min with 6% mix ratio. It is merely half the coolant currently used i.e. 2.0 L/min with 10% mix ratio. Minimal use of coolant not only economically desirable for reducing manufacturing cost but also it imparts fewer hazards to human health. Also, sparing use of coolant will eventually transform the turning process into a more environment-conscious manufacturing process.

Hydrodynamic Evaluation for Developing the New Inflatable Kayak (신형 인플래터블 카약 개발을 위한 유체역학적 성능평가)

  • Hah, Chong-Ku;Kim, Ho;Lim, Lee-Young;Ki, Jae-Suk
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.3
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    • pp.334-341
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    • 2015
  • This study is to evaluate hydrodynamic performance evaluation between three kinds of inflatable kayaks, that is, a frame kayak, a needle knife kayak, and a v-hull kayak. In order to test, inclining and turning trial test are performed in the Ocean Engineering Basin. Also, a resistance test is performed with a reduced scale kayak in the circulating water channel. Consequently, First, the moment arm of a v-hull kayak is the largest with 132.4mm, but turning radius of one was the smallest of them. Second, the resistance of a needle knife kayak is the smallest with 71N, the center of gravity of one was the lowest with 0.128m of them, and then needle knife kayak occurs in a draft overall. Consequently, the v-hull kayak has had the advantages on restoring force and turning performance than others. The needle knife kayak has been more excellent on resistance and center of gravity than others.

Temperature analysis of each coolant level in turning by a multiple comparison (다중비교를 이용한 선삭가공시 절삭유량에 따른 온도변화분석)

  • 박태준;양승한;이영문;김희술
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.1033-1036
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    • 2001
  • The object of this paper is to find out a coolant level, which is economic and similar to the conventional level, high level, in cutting temperature. For this, new coolant level, called a low level, was proposed, which is about 1/4 of conventional level. And the cutting temperature of each coolant level in turning was analyzed using statistical method. Firstly, it was analyzed that the temperature mean of each coolant level is not equal by ANOVA-test. Secondly by Tukey's HSD, one of multiple comparisons, it was analyzed that the temperature mean of low level is similar to that of high level and different from that of none level.

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A Comparison of Engineering Students' Learning Performance in Introductory Statistics of Traditional and Real-time Online Class Types (통계학 개론 대면과 실시간 비대면수업에서 공학전공 학생들의 학습 성취도에 대한 비교 연구)

  • Choi, Kyungmee
    • Journal of Engineering Education Research
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    • v.26 no.3
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    • pp.42-48
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    • 2023
  • We compare engineering students' learning performance in introductory Statistics classes of the two class types, traditional in-classroom classes with a few reports and real-time online classes with quizzes. Rates of missing classes and turning in homeworks are also included to explain learning attitude. Scores of quizzes, midterm test and final test are used to assess performance. Upto the midterm, the class type is not significant, but rates of missing classes and turning in homeworks are significant. Since the midterm, in-classroom class type reveals better final performance than real-time online class type, rate of turning in homeworks is significant, but rate of missing classes is not significant.