公开(公告)号：EP1498576A4

公开(公告)日：2006-05-10

申请号：EP02722785

申请日：2002-04-25

申请人： HITACHI CONSTRUCTION MACHINERY

发明人： NOZAKI SATOSHI ,  ABE TAKASHI ,  ARAI OSAMU ,  ARAI KAZUHIRO

IPC分类号： E02F3/47 ,  E21B7/00 ,  E21B7/02 ,  E21B11/04

CPC分类号： E02F3/47 ,  E21B7/003 ,  E21B7/02

摘要： A drilling device (2) for an earth drill, wherein locking bodies (3d, 3j) are provided on an inner member (3) connected to a kelly-bar (1) and a locking body receiving part (6f) is provided on an outer member (6), the outer member (6) comprises a cylindrical bucket (7) and an openable bucket (8) contained in the cylindrical bucket (7), the locking bodies (3d, 3j) are locked to the locking body receiving part (6f) by rotating the inner member (3) in forward direction when the drilling device (2) is in the fully retracted state to prohibit the vertical movement of the inner member (3) relative to the outer member (6), a force in pull up direction is given to the kelly-bar (1) to rotate the drilling device with a load smaller than the weight of the drilling device (2) applied to a drilled object by rotating the drilling device so that a drilling can be performed using an earth drill with a small drive force and the large drilling device (2), and a projection (3k) provided on the outer periphery of the inner member (3) is movably fitted in vertical direction to a guide rail vertically installed on the inner periphery of a second member (5) so that a ground obstacle can be removed by rotating in the state of being held by the openable bucket (8).