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タイトルヨミ
マルノコ ノ ソウオン ニ カンスル ケンキュウ クウキ リキガクテキ ニ ハッセイスル クウテン ソウオン ニツイテ
日本語以外のタイトル
A study of Aerodynamic Noise generation by Circular Saw Blades
ファイル
言語
日本語
著者
田中 千秋
長谷川 泰
塩田 洋三
高橋 徹
内容記述(抄録等)
The aerodynamic noise produced by idling circular saw blades was investigated experimentally. All blades used in this series of measurements were un-slotted, carbide tipped blades. They were 305 mm in diameter, and 1 mm, 1.25 mm and 1.65mm, respectively, in thickness. Carbide tips were 1 mm thick, and had 10 and 15 degrees in hook and clearance angles respectively. The number of teeth chosen was 4, 12, 24, 48 and 80. The tip speed of the blades, which was 34.4 m/sec, 45.5 m/sec, 68.6 m/sec and 89.4 m/sec, was altered by using different pulleys on the moter (Table 1).
The saws were tested in an anechoinc chamber whose external dimensions were 7.7 m^2 by 2 m high and which provided inverse square acoustic propagation for frequencies above 125 Hz. A microphone was placed 30 degrees to and 1 m from the end of the saw drive shaft as shown in Figure 1. Its height was 80 cm above the floor. The linear scale overall sound pressure level and 3 percent-octave band spectra of the noise which was generated by each blade tested was measured by a precision sound level meter, frequency analyzer and level recorder.
The results, based on the data presented, are as follows ;
1) The sound power increases as the 4.8th power of the blade tip speed (Fig. 2).
2) The sound power generated increases as the 0.5th and 1.4th power of the number of teeth and the blade thickness, respectively (Fig. 5 and 6).
3) Strouhal numbers based on the frequency of maximum sound pressure level, the carbide block thickness and the tip speed were between 0.12 and 0.25 for the range of Reynolds numbers based on blade radius tested. The Strouhal number of each blade was constant for the range of Reynolds numbers tested and increased with decreasing carbide block thickness (Fig. 4).
It is conjectured from these results that tip speed is the dominant factor in the noise production, that the noise sources of idling circular saws are some combination of monopoles and dipoles and that the dipole sound generation process is the major source of noise produced by saw blades.
掲載誌名
島根大学農学部研究報告
13
開始ページ
63
終了ページ
67
ISSN
0370940X
発行日
1979-12-15
NCID
AN00108015
出版者
島根大学農学部
出版者別表記
Shimane University, Faculty of Agriculture
資料タイプ
紀要論文
部局
生物資源科学部
備考
開学30周年記念号