超音波熔接用聲學喇叭之分析與應用

Analysis and Application of Acoustic Horns for Ultrasonic Welding

吳孟倫(Men-lun Wu)

指導教授 ： 許坤明

國立虎尾科技大學/工程學院/機械與機電工程研究所/碩士(2007年)

https://doi.org/10.6827/NFU.2007.00013

摘要

超音波熔接是超音波加工應用的一種，而超音波聲學喇叭的良窳將嚴重影響到超音波熔接的效果。本文係將針對超音波熔接分為兩個部分進行探討，第一部分為有限元素分析軟體ANSYS輔助超音波熔接用聲學喇叭之設計，第二部分為ABS樹脂之超音波熔接參數建立。
第一部分採用有限元素分析軟體ANSYS進行超音波熔接用聲學喇叭的分析設計，以明和超音波公司所生產之三種形式喇叭的直徑比為基礎，計算出喇叭應有的理論尺寸，再經由ANSYS分析來獲得其自然頻率以及振幅放大比，並藉由市售的計頻器進行自然頻率值的驗證，以理論值驗證所求得的振幅放大比，所得數值再與商用之喇叭進行比較。
結果顯示，ANSYS模擬的自然頻率值要比實際的量測值小，公式計算的喇叭其模擬值與量測值的誤差要比商用者低，顯示了經由整體計算的喇叭於模擬值與實際值的一致性，而振幅放大比在模擬值和理論值的誤差約為5％左右，顯示了有限元素法的準確性。
第二部分利用田口式的L18直交表，試著找出在塑膠材料中，使用超音波熔接最佳熔接參數。實驗使用的材料為ABS樹脂，聲學喇叭為公式計算之複合形喇叭，超音波熔接機的輸出功率為2200瓦特，而熔接點的強度則利用拉伸試驗來測定。
實驗結果顯示，在ABS試件的熔接過程中，其出力段數、熔接時間、導能角的位置為最主要影響熔接點強度之因子。
未來可提供業者於理論的基礎上進行聲學喇叭的設計，並藉由ANSYS有限元素分析軟體來輔助，不僅大幅節省了試誤的時間和材料的耗費，在超音波熔接的效率與品質的提升上也有相當大的助益。

關鍵字

有限元素分析 ； 超音波熔接 ； 聲學喇叭 ； 熔接強度

並列摘要

Ultrasonic welding is one of the applications of ultrasonic machining, and the quality of acoustic horns has a great effect on ultrasonic welding. For progressing the ultrasonic welding, two fields were studied in this dissertation, the first part is the analysis and design of acoustic horns for ultrasonic machining, utilizing ANSYS finite element software. The second part is to find the optimum parameters of ultrasonic welding by Taguchi’s method.
Firstly, the theoretical dimensions of the horns are calculated and compared to three commercial available horns with different shapes. Moreover, their natural frequencies and amplitude are obtained through the analysis of ANSYS simulation, and then the numerical results are compared with commercial available horns. The results indicate that not only the natural frequencies of horns obtained by theoretical models are more close to the vibration frequencies of ultrasonic generators, but also the amplitudes are superior to commercial available horns. Therefore, the trial and error time for horn machining as well as dimension modification can be greatly reduced by the proposed approach of this work.
Secondly, by using an Taguchi’s L18(21×37) orthogonal array analysis to find the optimum parameters of ABS for ultrasonic welding. One can found that welding process, power regulator, welding time and the position of energy director are the main factors for welding strength.
This paper can provide a design method of acoustic horn base on theory in the future, and assist with ANSYS software. Not only the trial and error time for horn machining can be greatly reduced, but also advanced the efficiency and quality of ultrasonic welding.

並列關鍵字

finite element analysis ； ultrasonic welding ； acoustic horn ； welding strength

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