Ti-6Al-4V之真空硬銲夾具設計與試驗

FIXTURE DESIGN FOR TESTING VACUUM BRAZING OF Ti-6Al-4V

黃明德(Ming -Te Huang)

指導教授 ： 李 碩 仁

元智大學/工程學院/機械工程學系/碩士(2009年)

摘要

鈦合金具有比強度高、耐疲勞強度及抗腐蝕能力佳等優點，於航太、醫療等領域有很多的應用。而真空硬銲因具有不需使用助銲劑且銲後外表美觀等優點，因此特別適用於銲接工件會與保護氣氛產生不良反應，或銲道內不允許殘留助銲劑之情況。因真空硬銲具有這些特性，使其大量應用於航太、核子以及電子領域中。但要以階層實驗方法獲得真空硬銲最佳參數，不但費時，成本也高。
本研究運用真空硬銲製程以及銀銅鈦合金(Ag68.8,Cu-26.7,Ti-4.5)填料，進行鈦合金(Ti-6A1-4V)接合。以最佳參數組合(硬銲溫度、接合間隙、加熱過程、表面粗度及搭接長度等)所需的實驗次數。另外，為了精確控制硬銲試片的接合間隙及搭接長度，本研究特別設計一組合夾具，並運用有限元素分析法，電腦輔助分析與模擬找到夾具設變前、設變後對銲接品質穩定改善。
本研究發現硬銲溫度、加熱過程、接合間隙、表面粗糙度對於銲道的機械強度有顯著影響。硬銲溫度880℃、持溫10分鐘、接合間隙0.05mm、表面粗糙度Ra0.3μm的參數組合，可達最佳的銲道強度。模擬夾具壓板直接壓在銲接面上，以35 in / lb可得穩定的加工品質。

關鍵字

真空硬銲 ； Ti-6Al-4V ； 銀基填料 ； 有限元素分析

並列摘要

Titanium alloys are excellent in strength-to-weight ratio, fatigue strength and corrosion resistance. These characters make them ideal for varied applications in aircraft,aerospace,and medical fields.Vacuum brazing does not require flux, so it is particularly well suited for joining parts which reacts adversely with other atmospheres or when entrapped fluxes or gases would be intolerable. Therefore, it has found wide applications in the aerospace, nuclear and electronic fields. Nevertheless, to obtain the optimum vacuum brazing process variables by factorial experiments is time and cost consuming.
This study applies vacuum brazing and silver-copper-titanium alloy (Ag-68.8, Cu-26.7, Ti-4.5) filler metal to join titanium alloy(Ti-6A1-4V). And, in order to reduce the number of factorial experiments in finding the
optimum vacuum brazing process variables combination (brazing temperature, join clearance, heating profile, surface roughness, overlap distance), the orthogonal array of Taguchi methods is adopted. A particular assembling fixture is designed to precisely control the join clearance and overlap distance of test specimens. In this thesis, a novel jig was conducted to improve the stability of the welding process. The finite element method and computer-aided engineering (CAE) analysis were employed to analyse the design change before and after design change of the jig.
In this study, it is found that control factors of brazing temperature, heating profile, joint clearance, and surface roughness have significant effects on the mechanical strength of a brazed joint. And, the combination of brazing temperature 880℃, holding time 10 minutes, joint clearance 0.05mm, surface roughess Ra0.3μm is optimal for maximum joint strength. The results of simulation showed that a stable welding process was obtained by forcing a proper assembly pressure of 35 in/lb on the blank holder of the jig which was directly contact with contact face.

並列關鍵字

Ti-6Al-4V ； Alloy ； Welding ； Brazing ； ANSYS

參考文獻

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