Procédé de blocage/freinage d'au moins une roue conique d'entrée d'un trépan d'un outil de forage consistant à utiliser au moins une roue dentée (1) dudit trépan comme élément d'entraînement d'une pompe hydraulique (P) pompant en circuit fermé (17) ledit circuit comportant un distributeur (9) commandé pour occuper soit une position ouverte soit une position fermée ; de telle sort que, en position ouverte, la pompe tourne librement sans absorber d'énergie, et que, en position fermée ladite pompe (P) soit hydrauliquement bloquée, ce qui bloque la rotation de la roue dentée (1).

A composite drill bit comprises: a drill bit body (1), a scraping-wheel (2), the drill bit body (1) further comprises a bit leg (3). The scraping-wheel (2) is mounted for rotation on the corresponding journal (6) of the bit leg (3), an outer-ring (4) is deployed on the scraping-wheel (2), wherein: the angular deflection α of the scraping-wheel (2) is in the range of 20° ≤ |α| ≤ 90°, the fixed cutting unit (8) with fixed cutters (8a) fixed thereon is deployed on the drill bit body (1). In the present invention, cutters on the scraping-wheel break rock by means of successive scraping, forming a cross-cutting area on the bottomhole accompanied by the cutters on the fixed cutting unit, thus achieving high rock-breaking efficiency, even wear, high cooling performance, and a longer service life for the cutters, bearings and the drill bit.

A roller cone bit comprising stress reduction means for reducing residual stress at the barrier (e.g., weld) (29) and the perimeter area (23) of the head (15) adjacent the outer diameter to increase the service load capacity and the service life of the roller cone bit. The stress reduction means comprises an inner weld (31) formed from a first material adjacent the ball plug (27). The weld (29)is formed on the inner weld (31) from a second material that has a higher strength than the first material.

A novel split threaded ring bearing member (42) for rolling cutter drill bits with at least a portion of its threads (48) having a different pitch than its mating threads (40) is disclosed. The pitch difference is designed so that the threaded ring can be seated or otherwise located precisely with respect to the other bearing elements within the drill bit to effectively control the axial displacement of the rolling cutter (18) on the bearing spindle (16) within a given tolerance range. Upon assembly, the difference in thread pitch causes the opposite, opposing mating thread flanks to engage, effectively applying a tensile or compressive force to a portion of the threaded ring bearing member (42), which gradually increases as the assembly is tightened. The result is an improved rolling cutter drill bit with a threaded ring cutter bearing system with excellent resistance to back-off which will not allow significant radial movement between the engaged threads, even if some back-off of the threads occurs.

A boring tool (10), particularly for use in concrete foundation pile construction, adapted for mounting to the lower end of a rod string (11) rotating about its longitudinal axis (x) and advancing along this axis. The boring tool comprises a roller (12) idly mounted with respect to the rods (11) and rotatable about an axis (y) inclined with respect to the longitudinal axis (x). The roller (12) has end portions (12a, 12b) located on opposite sides with respect to axis (x). The lower end portion (12b) of the roller (12) is fitted with a cutting bit (15) for disgregating soil. The roller has a fuse-like side surface and tapered upper (12a) and lower (12b) end portions, and a larger median portion (12c).

A method of manufacturing a rolling cutter drill bit of the kind where each cutter (18) is rotatably mounted on a bearing spindle (16) on the bit body (12) and is retained on the spindle by a threaded retention ring (42) in screw-threaded engagement with the cutter (18). The retention ring (42) is provided with an aperture (48) to expose a portion of the screwthread (40) on the cutter and an implement (52) is passed along a registering passage (26) in the spindle (16) and through the aperture (48) in the retaining ring (42) to deform or otherwise alter the exposed screwthread (40) in a manner to prevent subsequent relative rotation between the screw-threads, thereby locking the retention ring to the cutter. Instead of deforming the screw-thread (40) it may be formed with a recess (50) which is engaged by a pinning element (58) secured in the aperture in the retaining ring (42).