• Title/Summary/Keyword: Laser heat source

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Analytical Study of the Determination of Distance between the Laser Heat Source and Tool for Laser-Assisted Machining (레이저보조가공에서 열원과 공구 사이의 거리선정을 위한 해석적 연구)

  • Baek, Jong-Tae;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.8
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    • pp.699-704
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    • 2015
  • Laser-assisted machining has shown its potential to significantly improve product quality and reduce manufacturing costs; additionally, laser-assisted turning (LAT) and laser-assisted milling (LAM) have been studied by numerous researchers. A research study on the determination of the distance between the laser heat source and the tool for laser-assisted machining, however, has not yet been attempted; we conducted such an analysis by using a finite-element method and heat-transfer equation. The results of this analysis can be used as a reference for the determination of the distance between the laser heat source and the tool for laser-assisted machining.

a Study on Heat Source Equations for the Prediction of Weld Shape in Laser Micro-welding (미세 레이저 용접에서 용융부 형상예측을 위한 열원의 방정식에 관한 연구)

  • 장원석;나석주
    • Journal of Welding and Joining
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    • v.18 no.4
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    • pp.76-81
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    • 2000
  • In this research, various heat source equations that have been proposed in previous study were calculated and compared with new model in various laser parameters. This is to treat the problem of predicting, by numerical analysis, the thermo-mechanical behaviors of laser spot welding for thin stainless steel plates. A finite element code, ABAQUS is used for the heat transfer analysis with a three-dimensional plane assumption. Experimental studies if the laser spot welding have also bee conducted to validate the numerical models presented. The results suggest that temperature profiles and weld dimensions are varied according to the heat source of the laser beam. For this reason, it is essential to incorporate an accurate description of the heat source.

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Analysis of Moving Heat Source for Laser Assisted Machining of Plate by Feed Rate Control (이송속도 조절에 의한 평판 레이저 보조가공의 이동 열원해석)

  • Kim, Kwang-Sun;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.12
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    • pp.1341-1346
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    • 2011
  • Currently, many researches are carried out for laser assisted machining, which is one of the important fields in materials difficult to process. However, a prediction of heat source is difficult because of moving heat source. In this paper, a thermal analysis of laser assisted machining of plate by change of heat source size is performed, and preheating temperature by adjusting the feed rate is controlled. It was recognized that the maximum preheating temperature increases according to the decrease in heat source size, and feed rate need to adjust as high speed. The results of this analysis can be used as a reference for preheating temperature prediction in laser assisted milling.

Thermal Analysis for Laser Assisted Turning of Square Bar using Laser Heat Source Projection Method (사각형재의 레이저 예열 선삭에서 레이저 열원 투영법을 이용한 열해석)

  • Kim, Jae-Hyun;Choi, Jun-Young;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.12
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    • pp.1353-1358
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    • 2011
  • LAT(Laser Assisted Turning) is a method that applies a machining process after softening a workpiece in which a preheating process is locally applied to its machining section using laser heat source. LAT shows several advantages, such as high productivity, reduction of manufacturing cost, high quality. Analysis of temperature distribution after preheating for LAT is very difficult due to its very small heat input area and large energy and its movement. Also, the LAT for a square bar is more difficult because the shape of a laser heat source can be changed according to the rotation of the workpiece. In this study, thermal analysis for LAT of square bar was performed using laser heat source projection method. And, the analysis results were compared with the results of the prior study of numerical calculation method. It is thus shown that the proposed method is efficient for the thermal analysis of a shaped bar.

Laser Preheating Method for Three-Dimensional Laser Assisted Milling (3차원 레이저 보조 밀링을 위한 레이저 예열 방법에 관한 연구)

  • Oh, Won-Jung;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.12
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    • pp.1031-1037
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    • 2015
  • Laser assisted machining (LAM) is an effective method with which to effectively process difficult-to-cut materials. Simple machining processes, such as turning and linear tool paths, have been studied by many researchers. But, there are few research efforts on LAM workpieces using threedimensional shapes because of difficulties controlling the laser heat on workpieces with inclined angles or curved surfaces. Two methods for machining three-dimensional workpieces are proposed in this paper. The first is that the heat source shape and laser focal length are maintained using an index table. Second, a rotary type laser module is controlled using an algorithm to move the laser heat source in all directions. This algorithm was developed to control the rotary type laser module and the machine tool simultaneously. These methods are verified by a CATIA simulation.

Finite Element Analysis on the Improvement of Residual Deformation of the Part After Pulse Laser Welding of Circular Cover (원형 커버의 펄스 레이저 용접 후 부품 잔류변형 개선에 관한 유한요소해석)

  • Kim, Kwan-Woo;Cho, Hae-Yong
    • Journal of Welding and Joining
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    • v.33 no.6
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    • pp.60-66
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    • 2015
  • Molten zone shape of pulse laser welding is affected by welding conditions such as beam power, beam speed, irradiation time, pulse frequency, etc. and is divided into conduction type and keyhole type. It is necessary to design heat source model for irradiation of laser beam in the pulse laser welding. Shape variables and the maximum energy density value of the heat source model are different depending on the molten zone shape. In this paper, pulse laser welding simulation for joining of cylindrical part and circular cover was carried out. The heat source model for pulse laser beam with circular path was applied to the heat input boundary condition, radiative and conductive heat transfer were considered for the thermal boundary condition. For each phase, thermal and mechanical properties according to temperature were also applied to analysis. Analytical results were in good agreement with the molten zone size of specimen under the same welding conditions. So, the reliability of the welding simulation was verified. Finally, the improvements for reducing residual deformation after cover welding could be reviewed analytically.

Analysis of Overlapping Heat Zones in Laser-Assisted Machining (레이저보조가공에서 중첩열원에 관한 해석 연구)

  • Baek, Jong-Tae;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.12
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    • pp.1023-1029
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    • 2015
  • Laser-assisted machining (LAM) is one of the most effective methods for enhancing the machinability of difficult-to-cut materials, such as titanium alloys and various ceramics, and has been studied by many researchers. LAM is a method that facilitates machining by softening a workpiece using a laser heat source. The advantages of the LAM process are decreases in tool wear, cutting force, and surface roughness. However, when the material is over-heated, melting or burning can occur. This study analyzed the heat source distribution with regard to overlapping of preheating on the laser heating path with an acute angle, a right angle and obtuse angles. Then, a power reduction method was proposed to reduce the melting and burning of the workpiece.

A Study on the Three-Dimensional Heat Flow Analysis in the Laser Welding for Deep Penetration (레이저 심 용입 용저에서 3차원 열유동 해석에 관한 연구)

  • 이규태;김재웅
    • Journal of Welding and Joining
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    • v.18 no.3
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    • pp.76-82
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    • 2000
  • In this study, three-dimensional heat flow in laser beam welding for deep penetration was analyzed by using F.E.M common code, and then the results were compared with the experimental data. The models for analysis are full penetration welds and are made at three different laser powers (6, 9.9, 4.5 kW) with two different welding speeds (5.8mm/s, 5mm/s). The characteristics of thermal absorption by the workpiece during deep penetration laser welding can be represented by a combination of line heat source through the workpiece and distributed heat source at the top surface due to the plasma plume above the top surface. This gives an insight into the way in which the beam interacts with the material being welded. The analyses performed with the combined heat source models show comparatively good agreement between the experimental and calculated melt temperature isotherm, i.e, the fusion zone boundary. The results are used to explain the "nail head" appearance of fusion zone, which is quite common in laser beam welds.eam welds.

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Heat Source Modeling of Laser Keyhole Welding: Part 1-Bead Welding (레이저 키홀 용접의 열원 모델링: Part 1-비드 용접)

  • Lee Jae-Young;Lee Won-Beom;Yoo Choong-Don
    • Journal of Welding and Joining
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    • v.23 no.1
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    • pp.48-54
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    • 2005
  • Laser keyhole welding is investigated using a three-dimensional Gaussian heat source, and the heat source parameters such as the keyhole depth, welding efficiency and power density distribution factor are determined in a systematic way. For partial penetration, the keyhole depth is same as the penetration and is predicted using the experimental data. The welding efficiency is calculated using the ray-tracing method and the power density distribution factor is determined from the bead shape. Full penetration is classified into the transition, normal and excessive modes depending on the degree of keyhole opening. Thermal analysis of the bead-on-plate welds is conducted using the Gaussian heat source, and the calculated weld geometries show reasonably good agreements with the experimental results.

Finite element analysis for surface hardening of SM45C round bar by diode laser (다이오드 레이저를 이용한 SM45C 환봉 표면경화 열처리의 유한요소해석)

  • Cho, Hae-Yong;Kim, Kwan-Woo;Lee, Jae-Hoon;Suh, Jeong;Kim, Jong-Do
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.683-688
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    • 2007
  • Surface heat treatment of SM45C round bar by diode laser was simulated to find it's condition by using commercial finite element code MARC. Due to axisymmetric geometry, a quarter of model for SM45C round bar was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat and mass density were given as a function of temperature. Rotation speed of round bar and feed rate of beam were considered to design heat source model. Shape parameter values of heat source were determined by beam profile. As results, Three dimensional heat source model for diode laser beam conditions of surface hardening has been designed by the comparison between the finite element analysis results and experimental data on SM45C round bar. Diode laser surface hardening for SM45C round bar was successfully simulated and it should be useful to determine optimal heat treatment condition.

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