| 摘要 |
PURPOSE:To excavate a horizontal hole having a square cross section. CONSTITUTION:A rotary partition wall 4 is supported rotatably freely with a support plate 3 fixed inside of a skin plate 1 having a square cross section. A rotary shaft 15 is fitted rotatably freely in a position being eccentric to the center of the skin plate 1 of this rotary partition wall 4. A cutter head 20 is fixed to one end of the tip of this rotary shaft 15, and an external teeth gear 31 is fixed to the other end, and the external teeth gear 31 is meshed with an internal teeth gear 32. When the rotary partition wall 4 is rotated by an electric motor 42, the rotary shaft 15 and the cutter head 20 make planetary motion together with the external teeth gear 31. Thereby, an excavating part constituting an equilateral triangle of the cutter head 20 draws a locus whose envelope is a square shape, and excavates a horizontal hole having a square cross section. Excavated earth and sand or small stones are introduced in a chamber 16, and are agitated together with muddy water sent in from a mud feed pipe 52 by the first agitating blade 7 and the second agitating blade 27, and are discharged outside from a mud discharge pipe. |
