• Title/Summary/Keyword: laser surface hardening process

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Estimation of hardening depth using neural network in LASER surface hardening process (레이저 표면경화공정에서 신경회로망을 이용한 경화층깊이의 측정)

  • 박영준;우현구;조형석;한유희
    • 제어로봇시스템학회:학술대회논문집
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    • 1993.10a
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    • pp.212-217
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    • 1993
  • In this paper, the hardening depth in Laser surface hardening process is estimated using a multilayered neural network. Input data of the neural network are surface temperature of five points, power and travelling speed of Laser beam. A FDM(finite difference method) is used for modeling the Laser surface hardening process. This model is used to obtain the network's training data sample and to evaluate the performance of the neural network estimator. The simulational results showed that the proposed scheme can be used to estimate the hardening depth on real time.

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The Effect of Hardening Methods and Process Parameters on Surface Hardening of Ti-6Al-4V Alloy (Ti-6Al-4V 합금의 표면 경화 시 경화기구 및 공정변수가 표면 경화에 미치는 영향)

  • Seo, D.M.;Y., H. Jeong;Hwang, T.W.;Moon, Y.H.
    • Transactions of Materials Processing
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    • v.28 no.1
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    • pp.27-33
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    • 2019
  • The effect of hardening methods and process parameters on surface hardening of a Ti-6Al-4V Alloy has been investigated in this study. To characterize the effectiveness of the respective surface hardening methods, samples of a Ti-6Al-4V alloy were self-quenched, laser-nitrided, laser-carburized, laser-carbonitrided at the same laser irradiation conditions. This experimental procedure was followed by comparing the microstructural evolutions and mechanical properties of the respective samples after the laser surface hardenings. The hardening characteristics of the respective laser surface hardenings were well defined in this study, and the hardness was significantly influenced by the reaction compounds and laser energy density.

Estimation of Hardened Depth in Laser Surface Hardening Processes Using Neural Networks (레이저 표면경화공정에서 신경회로망을 이용한 경화층깊이 추정)

  • 박영준;조형석;한유희
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.8
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    • pp.1907-1914
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    • 1995
  • An on-line measurement of the workpiece hardened depth in laser surface hardening processes is very much difficult to achieve, since the hardening process occurs in depth wise direction. In this paper, the hardened depth is estimated using a multilayered neural network. Input data of the neural network are the surface temperatures at arbitrary chosen five surface points, laser power and traveling speed of laser beam torch. To simulate the actual hardening process, a finite difference method(FDM) is used to model the process. Since this model yields the calculation results of the temperature distribution around the workpiece volume in the vicinity of the laser torch, this model is used to obtain the network's training data and laser to evaluate the performance of the neural network estimator. The simulation results show that the proposed scheme can be used to estimate the hardened depth with reasonable accuracy.

Estimation of Hardening Layer Depths in Laser Surface Hardening Processes Using Neural Networks (레이져 표면 경화 공정에서 신경회로망을 이용한 경화층 깊이 예측)

  • Woo, Hyun Gu;Cho, Hyung Suck;Han, You Hie
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.11
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    • pp.52-62
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    • 1995
  • In the laser surface hardening process the geometrical parameters, especially the depth, of the hardened layer are utilized to assess the integrity of the hardening layer quality. Monitoring of this geometrical parameter ofr on-line process control as well as for on-line quality evaluation, however, is an extremely difficult problem because the hardening layer is formed beneath a material surface. Moreover, the uncertainties in monitoring the depth can be raised by the inevitable use of a surface coating to enhance the processing efficiency and the insufficient knowledge on the effects of coating materials and its thicknesses. The paper describes the extimation results using neural network to estimate the hardening layer depth from measured surface temperanture and process variables (laser beam power and feeding velocity) under various situations. To evaluate the effec- tiveness of the measured temperature in estimating the harding layer depth, estimation was performed with or without temperature informations. Also to investigate the effects of coating thickness variations in the real industry situations, in which the coating thickness cannot be controlled uniform with good precision, estimation was done over only uniformly coated specimen or various thickness-coated specimens. A series of hardening experiments were performed to find the relationships between the hardening layer depth, temperature and process variables. The estimation results show the temperature informations greatly improve the estimation accuracy over various thickness-coated specimens.

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A study on monitoring and control in laser transformation hardening process (레이저 표면 경화 공정의 계측 및 제어에 관한 연구)

  • 우현구;조형석;한유희
    • 제어로봇시스템학회:학술대회논문집
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    • 1993.10a
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    • pp.883-888
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    • 1993
  • This paper proposes a monitoring method using an infrared temperature sensor in laser surface hardening process. To investigate the validity of the method a series of experiments are performed for various conditions. The experimental results show that the surface temperature depends upon the laser power, travelling speed and surface conditions of a specimen. Especially, the laser surface hardening process is greatly influenced by the surface conditions of the specimen, such as coating thickness and materials.

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Study on Characteristics of Laser Surface Transformation Hardening for Rod-shaped Carbon Steel (I) - Characteristics of Surface Transformation Hardening by Laser Heat Source with Gaussian Intensify distribution - (탄소강 환봉의 레이저 표면변태경화 특성에 관한 연구 (I) - 가우시안 파워밀도 분포의 레이저 열원을 이용한 표면변태경화 특성 -)

  • Kim, Jong-Do;Kang, Woon-Ju
    • Journal of Welding and Joining
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    • v.25 no.3
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    • pp.78-84
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    • 2007
  • Laser Material Processing has been replaced the conventional machining systems - cutting, drilling, welding and surface modification and so on. Especially, LTH(Laser Transformation Hardening) process is one branch of the laser surface modification process. Conventionally, some techniques like a gas carburizing and nitriding as well as induction and torch heating have been used to harden the carbon steels. But these methods not only request post-machining resulted from a deformation but also have complex processing procedures. Besides, LTH process has some merits as : 1. It is easy to control the case depth because of output(laser power) adjustability. 2. It is able to harden the localized and complicated a.ea and minimize a deformation due to a unique property of a localized heat source. 3. An additional cooling medium is not required due to self quenching. 4. A prominent hardening results can be obtained. This study is related to the surface hardening of the rod-shaped carbon steel applied to the lathe based complex processing mechanism, a basic behavior of surface hardening, hardness distribution and structural characteristics in the hardened zone.

Estimation of Hardened Layer Dimensions Using Multi-Point Temperature Monitoring in Laser Surface Hardening Processes (레이저 표면 경화 공정에서 다점 온도 모니터링을 통한 경화층 크기 예측)

  • 우현구
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.12
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    • pp.1048-1054
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    • 2003
  • In laser surface hardening processes, the geometrical parameters such as the depth and the width of a hardened layer can be utilized to assess the hardened layer quality. However, accurate monitoring of the geometrical parameters for on-line process control as well as for on-line quality evaluation is very difficult because the hardened layer is formed beneath a material surface and is not visible. Therefore, temperature monitoring of a point of specimen surface has most frequently been used as a process monitoring method. But, a hardened layer depends on the temperature distribution and the thermal history of a specimen during laser surface hardening processing. So, this paper describes the estimation results of the geometric parameters using multi-point surface temperature monitoring. A series of hardening experiments were performed to find the relationships between the geometric parameters and the measured temperature. Estimation results using a neural network show the enhanced effectiveness of multi-point surface temperature monitoring compared to one-point monitoring.

Development Process for High Power Diode Laser for Metal Surface Hardening (금속 표면경화용 고출력 다이오드 레이저 개발 프로세스)

  • Jang, Dong-Hwan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.2
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    • pp.11-22
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    • 2022
  • This paper presents the development process for a high-power diode laser for metal surface hardening. To combine the emissions from several laser bars, it is necessary to collimate the emitted light using an optical lens. Thus, to achieve a suitable power density and uniform beam profile, several optical layouts were proposed. To estimate the laser beam for a flat-top distribution, a numerical analysis was performed using the ZEMAX software, and the results were compared with the experimental results. With a focal lens assembled in a serial diode stack source, the design can utilize the advantage of compacting the overall beam size. Experimental results for a robotic system demonstrated the processing ability of this diode laser module in industrial laser hardening.

Surface Transformation Hardening for Rod-shaped Carbon Steels by High Power Diode Laser (고출력 다이오드 레이저(HPDL)를 이용한 탄소강 환봉의 표면변태경화)

  • Kim, Jong-Do;Kil, Byung-Lea;Kang, Woon-Ju
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.8
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    • pp.961-969
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    • 2007
  • The laser material processing has replaced a conventional material processing such as a welding, cutting, drilling and surface modification and so on. LTH(Laser Transformation Hardening) is one branch of the laser surface modification process. A lot of energy is needed for the LTH process to elevate workpiece surface to temperature of the austenite transformation($A_3$), which results from utilizing a beam with a larger size and lower power intensity comparatively. The absorptivity of the laser energy with respect to material depends on the wave length of a beam. This study is related to the surface hardening for the rod-shaped carbon steel by the high power diode laser(HPDL) whose beam absorptivity is better than conventional types of lasers such as $CO_2$ or Nd:YAG laser. Because a beam proceeds on the rotating specimen the pretreated hardened-phase can be tempered and softened by the overlapping between hardened tracks. Accordingly, the longitudinal hardness measurement and observation of the micro structure was carried out for an assessment of the hardening characteristics. In addition, a hardening characteristics as a hardenability of materials was compared in the point of view of the hardness distribution and hardening depth and width.

A Study on the Diode Laser Surface Hardening Treatment of Cast Iron for Die Material(II) -Comparison of Hardening Characteristics by the Parts Applied Heat Treatment- (금형재료용 주철의 다이오드 레이저 표면경화처리에 관한 연구(II) - 표면경화의 적용 부위에 따른 열처리 특성의 차이 -)

  • Kim, Jong-Do;Song, Moo-Keun;Hwang, Hyun-Tae
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.8
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    • pp.1048-1054
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    • 2011
  • Laser surface hardening process is the method of hardening surface by inducing rapid self quenching of laser injected area through transfer of surface heat to inside after rapid heating of laser injected area only by high density energy heat source. This surface treatment method does not involve virtually any thermal deformation by heat treatment nor accompanies any other process after surface hardening treatment. In addition, allowing local machining, this method is a surface treatment method suitable for die with complicated shape. In this study, die material cast iron was surface-treated by using high power diode laser with beam profile suitable for heat treatment. Since the shapes of die differ by press die process, specimens were heat-treated separately on plane and corner depending on the applied parts. At this time, corner heat treatment was done with optic head inclined at $10^{\circ}$. As a result, corner heat treatment easily involves concentration of heat input due to limitation of heat transfer route by the shapes compared with plane part, so the treatment accomplished hardening at faster conveying speed than plane heat treatment.