• Title/Summary/Keyword: Lobe Diagram

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Development of Resistance Spot Weldability Estimation Using Lobe Diagram for Steel Plate of Automobiles (로브곡선을 이용한 자동차용 신강재의 저항 점 용접성 평가 기술 개발)

  • Kim, Tae-Hyung;Lee, Dong-Ock;Rhee, Se-Hun
    • Journal of Welding and Joining
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    • v.23 no.4
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    • pp.59-65
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    • 2005
  • The resistance spot welding is one of the most commonly used welding process for joining the sheet metal in automotive manufacturing process due to higher deposition rates and higher economy achieved. Control variables in the resistance spot welding for achieving high quality are welding current, welding force and welding time. Generally at the manufacturing scene, welding current Vs welding time lobe diagram is used to estimate weldability because controlling welding force is not practical due to economical reasons. However new automotive steel plates have been developed to make lightweight automobiles and to improve resistance against rusting. Also the weldability of these steel plates are worst than the existing steel plates because of changing bare metal and surface plating effect. In consequence of above mentioned reasons, it is necessary to use welding force to present the lobe diagram. In this study, we obtained the welding force Vs welding current lobe diagram for commonly used GA steel plate and found that the second order repression model of tensile shear strength was useful in reducing the number of experiments, and the indentation, and thickness change during welding were used as a response to estimate quantitatively expulsion.

An Integrated Approach to the Improvement of Stability Lobes

  • Mohan, Sekar;Jonnalagadda, Srinivas;Kang, Nam-Cheol;Yang, Seung-Han
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.4
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    • pp.83-85
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    • 2008
  • Redundant spurious loops and overlapping segments in stability lobe diagrams cannot be removed easily by regular methods. A programmatic approach is presented to detect multiple spurious loops occurring within the lobes. They are identified by reorganizing the numerical lobe data into speed-depth corners for subsequent removal. The same principle is then extended to remove overlapping segments of adjacent lobes to obtain a final continuous stability map. Unlike existing methods, the proposed methodology requires no interface with additional editing software, and can also yield stability lobe diagrams more quickly. The methodology is presented with lobe diagrams constructed using milling and turning models.

Prediction of the Chatter during the Milling Process of the Machine Tool (밀링 가공시 채터 현상 예측 기술개발)

  • Seo, Jae Woo;Park, Hyung Wook
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.5
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    • pp.441-446
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    • 2015
  • Chattering during the milling process causes severe problems on both the workpiece and cutting tools. However, chatter vibration is the inevitable phenomenon that operators require the prediction before the process or monitoring system to avoid the chatter in real-time. To predict the chatter vibration with the stability lobe diagram, the dynamic parameters of machine tool are extracted by considering cutting conditions and adapting the material properties. In this study, experimental verifications were taken for various aluminum types with different feed rates to observe the effect of the key parameters. The comparison between experimental results and the predictions was also performed.

A Study for Resistance Spot Weldability of Pre-sealed Sheet Steel for Automobile Body by Using Pre-current (예비전류를 이용한 자동차용 프리실드 강판의 저항 점 용접성 향상에 관한 연구)

  • Park, Tae-Gyu;Yun, Sang-Man;Rhee, Se-Hun
    • Journal of Welding and Joining
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    • v.27 no.6
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    • pp.36-42
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    • 2009
  • In the present day, new performances are demanded for automobile body steel sheet for example, light weight, durability, resistance corrosion and environmental protection. For an improvement of resistance corrosion, European automobile companies developed pre-sealed steel in 1990's. Pre-sealed steel have organic coated layer upper zinc coated layer. Evaluating a resistance spot weldability of pre-sealed steel plate is important because resistance spot welding is used mainly in automobile body joining process. In this study, evaluating a weldability of pre-sealed steel plate was carried out using lobe diagram, dynamic resistance and high-speed image. Usually, Pre-sealed steel has poor weldability than GA steel's. To improve a weldability of pre-sealed steel sheet, pre-current was applied to welding process. Pre-current is applied prior to base-current. In conclusion, the weldability of pre-sealed steel has been improved than GA steel's by applying pre-current.

Evaluation of Weldability on the Resistance Spot Welding of DP60 Steels for Automotive Chassis (자동차 새시용 DP60강 인버터 DC 저항 점용접의 용접성 평가)

  • Kim, I.J.;Oh, I.H.
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.4
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    • pp.143-148
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    • 2011
  • This study analyzes the resistance spot weldability of DP60 steels. To analyze the resistance spot weldability of DP60 steels, tensile strength test and macro-section test were conducted for the resistance spot welds. Acceptable welding conditions were determined as a function of the resistance spot welding process parameters such as electrode force, welding time, and welding current. The lower limit of the welding lobe was the minimum shear tension strength for 590MPa-grade steel while the upper limit was determined whether or not expulsion was detected.

Milling Chatter Stability Analysis in Consideration of Gyroscopic Effect (자이로 스코프 효과를 고려한 밀링 채터 안정성 해석)

  • 박재현;홍성욱;김현수;박중윤
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.2
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    • pp.58-63
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    • 2000
  • The dynamics of spindle-bearing-workpiece system significantly affects the cutting condition and stability in milling process. The present paper investigates the chatter stability of milling process due to the change in the dynamics of spindle-bearing-workpiece systems. In particular, the present paper focuses on chatter stability due to the presence of gyroscopic effect. An eigenvalue problem approach to the stability of milling process is extensively used in this paper. To incorporate the rotational speed dependent gyroscopic effect, an iterative algorithm is proposed. A numerical example is provided for examining the chatter stability problem in the presence of gyroscopic effects.

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Aspherical Lens Manufacturing Technology in the Optical Storage Device (광 정보 저장 장치에서의 비구면 렌즈 가공 기술)

  • 이호철;김대식;이철우;김부태;양민양
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.964-967
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    • 2001
  • Aspherical lens with the higher numerical aperture has been needed in the optical storage device to increase the recording density on the disk. However, high numerical aperture means the large slope angle at the clear aperture of the lens. Therefore, the measurement and manufacturing technique including the lens molding process for the slope angle should be developed. In this paper, the evaluation technique was described for the optical performance of the aspherical lens. Aspherical form error brings about the wavefront error and the side lobe of the beam intensity profile. A schematic diagram of the aspherical lens manufacturing was drawn to explain the aspherical form error compensation. Finally, form error of the aspherical lens was defined and plotted using the raw data of the Formtalysurf.

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MASS EXCHANGE OF THE ECLIPSING BINARY WZ ANDROMEDAE (식변광성 WZ ANDROMEDAE의 질량교환)

  • Oh, Kyu-Dong
    • Journal of The Korean Astronomical Society
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    • v.10 no.1
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    • pp.23-30
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    • 1977
  • We have collected times of minimum light available in the literature for WZ Andromedae and analyzed the nature of the period variations. The O-C diagram of WZ And clearly shows that two abrupt changes near JD 2418000 and JD 2435000 are deduced by dp/p=$+4.24{\timesa}10^{-6}$ and dp/p=$-2.46{\times}10^{-6}$, respectively. For these period changes, we have introduced the equations which represent mass exchange in the close binery systems given by Biermann and Hall (1973), and the computation yieleled a mass flow of $7.42{\times}10^{-5}M$. from the hotter component to the cooler one. Due to the amount of mass flow, the period decrease may also be calculated. The theoritical new period after JD 2435000 became 0.69565858 days, which is in good agreement with the value 0.69566034 days found in the O-C diagram. In this computation, the mass ratio of WZ And suggested that the hotter star is the filling its Rochclooe, and thus WZ And is in Paczynski's stage II.

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