穿孔帯鋸による挽材に関する研究(II) : 挽材性能に及ぼす穿孔形の影響

This study was made to examine and estimate what difference in the sawing efficiency coused by the perforated bandsaw with elliptical holes. The bandsaw blades are classified by their holes as shown in Fig. 1 and Fig. 5 but these original saws are excepted. These sawing tests were done under such practical condition as follows :
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Bandsaw mashine (20HP) with equipped automatic carriage (3HP) ・・・・・42 inches
Bandsaw thickness ・・・・ 24 B. W. G.
〃 Width ・・・・・ 4 inches
Wood species ・・・・・・ BUNA (Fagus crenata Blume)
Dia. of logs ・・・・・・ 15-55cm
Length of logs ・・・・・ 200±2cm
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The cutting speed was 41.9 m/s and the feed speed were made as fast possible within a limit of good cutting. The cutting force Fkg was calculated from the net electrical power required by the saw to cut timber which was expressed by correcting the wattmeter reading with the data from the brake tests. The thickness of wood cut per tooth d mm was calculated by measuring the feed speed to cut timber. Resalts of these tests are shown in Figs. 2-4 (sawblades No. 1-No. 3) and in Figs. 6 , 7 (sawblades No. 4, No.5)
The main results obtained are considered as follows :
(a) The smoll elliptical hole (9.5mm × 40.0mm)
The sawing properties (F and d etc) are not so influenced even if the sawblades are punched and the hole's rate ε% are increased (Eig. 3 , 6)
These facts show, so to speak, that the circular hole shown in Fig. 2 (area : 284 <mm>^2) shoul be better than the elliptical one (area : 361<mm>^2)
(b) The large elliptical hole (19.0mm × 40.0mm)
The sawing properties (F and d etc) rise when the hole's rate ε% is 3.2 (Fig. 4) but foll down after the rate ε% is increased to 6.4 (Fig. 4). The electrical efficiencies (d/F) of the perforated bandsaw blades are better than the original ones (Fig. 4 Fig. 7). These facts indicate that the efficiencies of the large elliptical form (684<mm>^2) are nearly equal to that of the circular ones (284<mm>^2), in spite of the famer's area is larger than the latter's one. Therefore, the elliptical form's saw blades are less practical from the view point of the intensity and the saving for the bandsaw blade. (Fig. 10 show the models of the practical perforatedband saw blades.)