HEAD TUBE FOR CASING EXCAVATION TECHNIQUE

摘要

PURPOSE:To facilitate execution by forming a plurality of inclined cutting grooves gradually displaced to the rear end side of a tube toward the direction of rotation of a tube from a drilling-blade mounting section on the outer circumference of the tube and forming a cutting introducing hole communicated with the inside of the tube from the cutting grooves. CONSTITUTION:A plurality of cutting grooves 3 extended in the oblique upward direction at an inclination alpha deg. from the mounting sections of drilling blades 2 are shaped on the outer circumference of a head tube 1 at regular pitches P. Cutting introducing holes 5 having an arbitrary shape such as a circle, an ellipse, a square, etc. are formed at positions retreated from the noses of the blades 2 at fixed distances. Cuttings flowing out on the outer circumference of the tube 1 from the nose sections of the blades 2 are moved upward along the grooves 3 of the outer circumference by resistance between revolving torque and the wall surfaces of the holes, and taken into the tube 1 through the holes 5, and a cutting discharging function by the grooves 3 is held. Accordingly, the clogging of cuttings and the increase of the rotational resistance of a cylindrical tube are prevented, thus facilitating execution.