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  • 會議論文

刺繡機引起之樓板振動改善實例

Case Study: The Reduction of Floor Vibration Induced by Embroidery Machines

摘要


本文主要探討十層工業大樓中,廠房因置放14台刺繡機所引起之樓板振動問題,並就其引發上下樓層之振動噪音問題予以改善。廠房中主要有1.5噸與1.8噸等兩型機種,每部機器有17個針織頭同時作動,現象顯示該公司換過之三類隔振材料,仍會造成4樓窗戶格格作響,2樓也能聽到低頻噪音。鑑於上述問題,我們測試了該廠所選用過之HI-Mount,橡膠防震墊片,及榻榻米等三種減振材在單一機器運轉條件下之自然頻率,結果顯示HI-Mount之自然頻率約20Hz,遠高於機器轉速500-700 rpm,其他兩類則有所改善,但振動值仍高於1.6mm/s,屬於地震等級中“相當強”一級,尤有進者,我們測得三樓地板之自然頻率為9.6Hz及12Hz,兩頻率值均非常接近機器轉速,隔振不良會造成共振現象。 基於地板振動信號分析與機器運轉穩定性要求,我們選定了國產氣壓式減振器,配合適當的保護措施,測得1.5噸機上下運動模態在4.3Hz,而1.8噸機則為5.4Hz,均低於機器轉速。改善結果得到3樓地板振動僅為原來的4%-18%,平均值為0.20 mm/s,為原值的13%;4樓地板則降為0.11mm/s,為原值的9%;2樓地板降為0.10 mm/s,為原值的25%,均屬於“無感覺”等級,同時2樓噪音也消弭於無形。經一個月後作追蹤量測,仍保持狀況良好,由此證實測試選用之減振墊能經濟且有效地改善樓板振動情形。

關鍵字

振動 減振器 頻率響應函數

並列摘要


The floor vibration induced by 14 embroidery machines which stand on the third floor of a ten-storied building was analyzed and improved. There are two types of machines weighted 1.5 ton and 1.8 ton and each of them has 17 embroidery needles operating simultaneously. It was indicated that even though different kinds of isolators were used by the company, the glasses on a table on the fourth floor was severely shaken by the floor vibration. Besides, a disturbing noise was heard on the second floor. Due to these severe problems, we tested the three kinds of isolators: HI-Mount, Neoprene Rubber Pad and Straw Pad. In the case of one machine operating only, we found that HI-Mount was not suitable in such case since its natural frequency is about 20 Hz which is much higher than the machine operating speed, 500-700 rpm. The third floor vibration was improved by using the other two kinds of isolation pads, but its vibration level was still greater than 1.6 mm/s. According to the earthquake classification, it belongs to the degree of ”rather strong”. Moreover, we found that the lower natural frequencies of the third floor are 9.6 Hz and 12 Hz, respectively. Both frequencies are very close to the operating speed of the the machines. Based upon the dynamic analysis of the floor vibration and the restrictions of the machine operating conditions, we selected the appropriate Pneumatic Rubber isolators after a few tests. It reveals that the natural frequency of the isolator system in the vertical motion is 4.3 Hz for the 1.5 ton machine and 5.4 Hz for the 1.8 ton machine, respectively. The final measure results showed that the third floor vibration was reduced from 4% to 18% of the original floor vibration at five selected locations. The average vibration level on the third floor was reduced to 0.20 mm/s which is 13% of the original value. The fourth floor vibration level was reduced to 0.11 mm/s which is 9% of the original value. The second floor vibration level was reduced to 0.10 mm/s which is 25% of the original value. Both the second and the fourth floor vibration levels belong to the degree of ”no feeling”. At the same time, the disturbing noise is no longer existing on the second floor. During a month of monitoring, we found that the floor vibration levels are still kept as low as desired.

並列關鍵字

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