| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a new ground excavation technology capable of smoothly and efficiently excavating a large diameter hole in a base rock, without having adverse influence such as vibration and noise on a neighborhood building.SOLUTION: A ground excavation attachment 1 is composed of: a tip pilot head 2 including a plurality of semispherical tip guiding bits 3, 3 and 3, which are opposed so as to secure a passing clearance S1 of a coolant W in a discharge port 22 of a tip guiding cylindrical body 20, pivotally attached at an inclination of 45° to the central axis C of the tip guiding cylindrical body 20, and an attaching-detaching mechanism lower part 60 provided on the upper end of the tip guiding cylindrical body 20; and a main head 4 including a succeeding cylindrical body 40 having an attaching-detaching mechanism upper part 61 on the lower end thereof and a connection part 42 on the upper end thereof, and a plurality of semispherical succeeding bits 5, 5 and 5, which are opposed so as to secure a pilot head 2-installing clearance S2 around the periphery of the succeeding cylindrical body 40, pivotally attached at an inclination of 45° to the central axis C of the succeeding cylindrical body 40. The attaching-detaching mechanism upper part 61 can be non-rotatably combined with and connected to the attaching-detaching mechanism lower part 60.</p> |
