| 摘要 |
PURPOSE:To enable stable correction boring by inserting the orient guide pipe of a bore-center correcting device into an outer pipe and by boring a corrected bore way along the inclined bushing of the guide pipe in the driving method for orient boring. CONSTITUTION:In the case when the course of a bore deviates from an allowed target sphere, the outer pipe 4 is turned round until a tilt direction line 17 in a bore- center measuring device engaged with an outer-pipe engaging part reaches a correction angle and the measuring device is withdrawn. Next, the orient guide pipe 21 is inserted into the outer pipe 4 in such a manner that it is engaged with the outer- pipe engaging part. Then, a guide rib 11a is engaged with a bushing 7 for setting and a corrected bore way 9a is bored along the inclined bushing 22 of the guide pipe 21 by using an air hammer drill 23. Thereafter, the air hammer drill 23 and the guide pipe 21 are withdrawn and boring is driven along the new corrected bore way 9a. |
