| 摘要 |
PURPOSE:To make it possible to excavate a hole having a square section and to promote crushing operation for gravel. CONSTITUTION:A shell 1 having a square section is used, and an external gear 42 is interlocked with an internal gear 41 through a crankshaft 52 to make planet motion. A rotary shaft 15 fixed to the external gea 42 is on a rotary partition 7 in a state of eccentricity to the center of the shell 1. A cutter head 20 makes also planet motion with the planet motion of the external gear 42 and the rotary shaft 15, an excavation section forming a regular triangle of the cutter head 20 descrikes a square locus, and a section corresponding to an outside diameter of the shell 1 excavates a square hole. A cone 21 of the cutter head 20 makes planet motion with the planet motion of the rotary shaft 15, so that gravel is held between a hood 2 and the cone 21 and crushed. Gravel passing through an opening 31 of a slit plate 30 is only guided to a chamber 13. |
