複合材料重低音音箱之製作及量測

Fabraction and Testing of Composite Heavy Bass Sound Box

張瑞榮(R. R. Chang) ； 林純華(C. H. Lin) ； 蘇承佑(C. Y. Su)

《中華科技大學學報》 51期 (2012/04) Pp. 77-94

https://doi.org/10.7095/JCUST.201204.0074

摘要

本研究為研發製造重低音音箱及模態測試，利用複合材料質輕、高強度的特性及乾式玻璃纖維疊層包覆成音箱本體和上蓋板，並在中間加入瓦楞板作為彈性材來降低音箱頻率的結構。製程首先將模具抽真空，再利用樹脂轉注真空成型法（VA-RTM）注入樹脂於含有預成形物的模具內，使模穴內樹脂與玻璃纖維及瓦楞板充分膠合浸潤，並熱硬化成形，如此可減輕音箱結構重量及降低加工成本。在模態實驗下使用加速規量測音箱共振頻率，以敲擊試驗取得音箱本體共振頻率之數據，再以雷射自動震盪掃頻器測定喇叭單體的自然頻率，以測定出與音箱共振頻率值。聲壓試驗獲得喇叭單體與音箱頻譜分析圖，並比較其複材音箱與單體的聲壓及音箱尺寸設計對駐波產生之聲壓影響。

關鍵字

重低音喇叭音箱 ； 樹脂轉注真空成型法 ； 共振頻率 ； 頻譜分析

並列摘要

The sound box was fabricated via the VA-RTM approach in which the foam core wrapped by glass fabric was placed in a steel mold, epoxy resin was injected into the mold to cover the skin of the box, and the inner part of the mold was vacuumed during the resin injection process. The cured sound box was subjected to model testing to validate the reliability of the box. The vibration characteristics (natural frequencies) of elastically laminated composite sound box used for heavy bass sound radiation are compared to single speaker. In the vibration testing of the sound radiator, the B&K 3650C data acquisition system was used to provide a series of harmonic sine function signals sweeping in a specific frequency range to the electro-magnetic exciter to make the speaker vibrate. The speaker response signals picked up by the laser gun (OFV 350) and vibrometer (OFV 2500) were analyzed using the FFT analyzer of the B&K 3650C data acquisition system to construct the frequency response spectrum of the speaker. It has been shown that the sound box has significant effects on the vibration characteristics of the heavy bass sound radiators.

並列關鍵字

Heavy sound box ； VA-RTM ； Natural frequencies ； Frequency response spectrum