(19)
(11) EP 0 741 227 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
19.11.1997 Bulletin 1997/47

(43) Date of publication A2:
06.11.1996 Bulletin 1996/45

(21) Application number: 95203177.1

(22) Date of filing: 20.11.1995
(51) International Patent Classification (IPC)6: E21B 7/28
(84) Designated Contracting States:
DE FR GB

(30) Priority: 01.05.1995 JP 107464/95

(71) Applicant: HITACHI CONSTRUCTION MACHINERY CO., LTD.
Chiyoda-ku Tokyo 100 (JP)

(72) Inventors:
  • Aizawa, Kazuo
    Inashiki-gun, Ibaraki-ken 300-03 (JP)
  • Washimi, Takeo
    Kashiwa-shi, Chiba-ken 277 (JP)
  • Kusakawa, Nobuhiro
    Inashiki-gun, Ibariki-ken 300-04 (JP)
  • Hari, Masanori, 252-7, Aza Sonachi
    Fukushima-ken 979-61 (JP)
  • Satoh, Akira
    Kashiwa-shi, Chiba-ken 277 (JP)
  • Muraoka, Tadashi
    Inashiki-gun, Ibaraki-ken 300-12 (JP)
  • Aihara, Tomihiro
    Tsuchiura-shi, Ibaraki-ken 300 (JP)

(74) Representative: Smulders, Theodorus A.H.J., Ir. et al
Vereenigde Octrooibureaux Nieuwe Parklaan 97
2587 BN 's-Gravenhage
2587 BN 's-Gravenhage (NL)

   


(54) Borehole boring method and machine


(57) A pilot hole (6) is drilled in a ground (1) by a first drilling unit having a rotary table (3) and a down-the-hole drill (2) (see FIG. 1A). A guide rod (7) is inserted into the pilot hole (6). A second drilling unit (8) is then mounted on the guide rod (7). This second drilling unit (8) is provided with an earth drilling bucket (19a) for drilling the ground (1), hydraulic cylinders (60) for fixing a stationary unit (10) of the second drilling unit on a wall of a target borehole (7a) in the ground (1), and another hydraulic cylinder (21) for causing the earth drilling bucket (19a) to advance. Drilling reaction force during boring work can thus be supported by both the wall of the target borehole (7a) and the guide rod (7). While being rotated, the earth drilling bucket (19a) is caused to advance over a distance corresponding to a stroke of the hydraulic cylinder (21). This operation is repeated until the target borehole (7a) is formed over its entire length.






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