| 摘要 |
PROBLEM TO BE SOLVED: To separately grip an inner tube and an outer tube by providing an inner tube chuck having an L-shaped inner chuck piece for opening outward with a pin as a fulcrum and an outer tube chuck having an outer chuck piece thread-mounted on the tip of a chuck bolt. SOLUTION: An L-shaped inner chuck piece 23 to which a plate-like support piece 21a has an inner tube chuck 20 for gripping an inner tube by fitting the tip of the inner chuck piece 23 in a cutout 11a of a spindle 11 with a pin 24 as a fulcrum. An outer chuck piece 33 for gripping an outer tube in a tip screw part is screwed in a chuck bolt 34 to which ring-shaped support hardware 31 is fixed, and the outer chuck piece 33 has an outer tube chuck 30 for going in and out of a hole of the spindle 11. Thus, since the inner tube chuck largely opens, the inner/outer tubes can be separately connected from above a drill head to connect a rod longer by a stroke or more of the drill head.
|
