METHOD FOR FORMING LONG HOLE IN LONG SIZE ANCHOR BOLT, ETC.

摘要

PURPOSE:To efficiently form a long hole in a long size anchor bolt, etc., by heading an axial hole of the heading limit length in the central part of an axis of round metallic material and continuously forming a drilled hole in the extension part of an axial hole by machining. CONSTITUTION:At a 1st stage, the round axis metallic material 1 cut to a specified length is headed at each of several stages to form axial hole 2 of the heading limit length in the central part of the axis. At a 2nd stage continued to this, the drilled hole 2a is formed by cutting in the extension part of this axial hole 2. The diameter of this drilled hole 2a takes the same diameter as that of the axial hole 2 or a different, larger or smaller diameter and a tapered hole 21 is formed on that end part. In that case, an axis 11 of small diameter before threading is formed on the upper part of the round axis metallic material 1 and a buried tube part 12 is formed on the lower part. Thereafter, a thread groove is formed on the outer periphery of the axis 11 before threading and an expanding slot is formed on the buried tube part 12 to obtain the anchor bolt.