臺灣博碩士論文加值系統

本研究目的在於透過有限元素分析方法建立出針對雷射重熔表面性質之模擬系統，主要利用COMSOL Multiphysics多重物理量耦合分析軟體進行設計，首先藉由探討雷射重熔影響成品質量之原理，並分析雷射重熔主要能夠改善表面品質之影響因素，設計出重熔製程參數作為模擬分析之主要設定參數，再透過模擬結果計算出表面粗糙度，並利用田口方法找出最佳參數組合，最後再進一步對實驗數值進行比較，探討出模擬方法之可靠性與可行性。
在本研究中，為了模擬出雷射重熔改善粗糙成品的效益，主要以一具有粗糙表面之金屬模型進行模擬，此模型表面透過隨機函數產生不平整變化，並透過耦合熱傳及流體的方式，以及將雷射功率、掃描速度及掃描間距作為製程參數對金屬模型進行雷射重熔的分析計算，其中以熱傳模組建立出雷射熱源對金屬模型進行加熱，再透過流體模組中的兩相流計算熔融金屬的流動，並追蹤出金屬與氮氣之間的界面變化，由此方式得出金屬模型之表面變化，最後再整理隨製程參數變化之表面粗糙度數值，搭配直交表繪製出品質特性因子反應表及反應圖，藉以得出最佳參數組合。
由模擬結果得知，以高雷射功率搭配低掃描速度及短掃描間距能得到較低的表面粗糙度，且模擬結果透過田口方法所得出最佳參數組合與實驗結果相符，而在模擬中以最佳參數組合使金屬模型表面粗糙度由6.231um下降至0.445um。

A simulation system for the properties of laser remelting surface through finite element analysis method has been establish by COMSOL multi-physics coupling analysis software. The principle affecting the quality of finished products and the factors improving surface quality of laser remelting are taken into investment. Several studies have investigated the temperature variation of the laser remelting process. However, several researchers ignore the influence of coupling heat transfer and fluid. Therefore, the aim of this research attempt to analyze the effect of remelting process parameters on surface roughness by two-phase flow method.
In the beginning of experimental design, the remelting process parameters (laser power, scanning speed and scan-line spacing) are designed as the main setting parameters of simulation analysis. Secondary, the simulation results are used to calculate the surface roughness and the Taguchi method is applied to investigate the relation between process parameters and surface roughness. Finally, the simulation results are compared with the experimental data to explore the reliability and feasibility of the simulation method.
Results show that higher laser power with lower scanning speed and shorter scan-line spacing can achieve lower surface roughness. The optimal parameter combination obtained by the Taguchi method is consistent with the experimental result. The optimal combination of parameters reduces the surface roughness Ra from 6.231 um to 0.445 um.

摘要 i
Abstract ii
誌謝 iii
目錄 iv
表目錄 v
圖目錄 vi
第一章 緒論 1
1.1 前言與動機 1
1.2 研究方法 4
1.3 論文架構 5
第二章 文獻探討 6
2.1 雷射表面性質探討 6
2.2 雷射重熔參數研究 7
2.3 模擬分析之應用 13
第三章 模擬方法分析與測試 21
3.1 模擬原理探討 21
3.2 兩相流方法 22
3.2.1 兩相流—等位函數(Level Set) 22
3.2.2 兩相流—相位場(Phase Field) 23
3.3 控制方程式 24
3.3.1 流體熱傳 24
3.3.2 層流、兩相流 26
3.4 初步模型測試 27


第四章 實驗設計與結果 33
4.1 不平整模型 33
4.2 邊界條件設置 37
4.2.1 雷射移動熱源 37
4.2.2 雷射路徑 38
4.2.3 模型屬性 38
4.2.4 邊界對流 39
4.2.5 熱輻射 40
4.2.6 氮氣進出口 40
4.2.7 初始介面 41
4.2.8 材料設定 42
4.3 網格 43
4.4 重熔參數 45
4.5 模擬結果 47
4.5.1 表面粗糙度 47
4.5.2 最佳參數組合 54
4.5.3 溫度分析 55
4.5.4 流速分析 62
4.5.5 掃描距離 63
4.5.6 蒸發 64
第五章 結論與未來展望 65
5.1 結論 65
5.2 未來展望 66

[1]光固化SLA介紹示意圖，2019年5月31日，取自https://www.machinedesign.com/3d-printing/what-s-difference-between-stereolithography-and-selective-laser-sintering
[2]熱熔擠製成型FDM介紹示意圖，2019年5月31日，取自 https://www.tth.com/3d-printing/fdm-prototyping/
[3]Vijay Laxmi Kalyani, Divya Bansal, “Future Communication Technology: A Comparison Between Claytronics And 3-D Printing,” Volume -3, Issue- 4, Aug. 2016, ISSN: 2394 - 8124
[4]直接能量沉積DED介紹示意圖，2019年5月31日，取自https://www.bintoa.com/directed-energy-deposition/
[5]S. Van Bael, “Micro-CT-based improvement of geometrical and mechanical controllability of selective laser melted Ti6Al4V porous structures,” Materials Science and Engineering A 528 (2011) 7423– 7431.
[6]Qian Jun Bo, Han Fei, Shi Yu-sheng, Wei Qing-song, “Notice of RetractionComparison of two scan strategies applied to the selective laser melting,” Published in International Conference on Computer Application and System Modeling 2010
[7]A. Temmler, E. Willenborg, and K. Wissenbach, “Designing Surfaces by Laser Remelting,” ICOMM 2012
[8]Nan Kang et al, “Effects of laser remelting process on the microstructure, roughness and microhardness of in-situ cold sprayed hypoeutectic Al-Si coating,” Surface & Coatings Technology 318 (2017) 355–359.
[9]Swee Leong Singa, Florencia Edith Wiriaa, Wai Yee Yeong, “Selective laser melting of titanium alloy with 50 wt% tantalum: Effect of laser process parameters on part quality,” International Journal of Refractory Metals & Hard Materials 77 (2018) 120–127.
[10]Juliana dos Santos Solheid, Hans Jurgen Seifert, Wilhelm Pfleging,“Laser surface modification and polishing of additive manufactured metallic parts,”Procediz CIRP 74 (2018) 280-284.
 

[11]Abdullah M. Khalid Hafiz, Evgueni V. Bordatchev, Remus O. Tutunea-Fatan, “Influence of overlap between the laser beam tracks on surface quality in laser polishing of AISI H13 tool steel,” Journal of Manufacturing Processes 14 (2012) 425–434.
[12]Jiou-You Liu, “The Investigation of Laser Remelting Parameters on Surface Properties,” 國立雲林科技大學，2017。
[13]Zhi-Xuan Wei, “Influences of scanning strategy effect on surface roughness in selective laser melting,” 國立雲林科技大學，2017。
[14]JU-HAN YANG, “Development of simulation system for selective laser melting at mesoscopic scale and defects analysis,” 明志科技大學，2018。
[15]Jun-Pou Chen, “Modelling and Simulation of Metal Powder Bed Fusion Process in Laser Additive Manufacture,” 國立聯合大學，2017。
[16]Loong-Ee Loh et al, “Numerical investigation and an effective modelling on the Selective Laser Melting (SLM) process with aluminium alloy 6061,” International Journal of Heat and Mass Transfer 80 (2015) 288–300.
[17]Yali Li, Dongdong Gu, “Parametric analysis of thermal behavior during selective laser melting additive manufacturing of aluminum alloy powder,” Materials and Design 63 (2014) 856–867.
[18]Donghua Dai, Dongdong Gu, “Tailoring surface quality through mass and momentum transfer modeling using a volume of fluid method in selective laser melting of TiC/AlSi10Mg powder,” International Journal of Machine Tools & Manufacture 88 (2015) 95–107.
[19]K.-H. Leitz, P. Singer, A. Plankensteiner1, B. Tabernig, H. Kestler1, L.S. Sigl, “Thermo-Fluiddynamic Modeling of Laser Beam-Matter Interaction in Selective Laser Melting,” Excerpt from the Proceedings of the 2016 COMSOL Conference in Munich.
 

[20]等位函數示意圖，2019年5月31日，取自 https://www.comsol.com/forum/thread/attachment/37361/The-level-set-methodfrom-MEMS-Module-5198.pdf
[21]過渡區示意圖，2019年5月31日，取自 https://cn.comsol.com/blogs/which-multiphase-flow-interface-should-i-use/
[22]移動熱源示意圖，2019年5月31日，取自 https://cn.comsol.com/blogs/how-to-make-boundary-conditions-conditional-in-your-simulation/