Process and device for drilling the soil

A device for drilling the soil including a carrying frame (29), a tool (6), displacement means for translation of said tool (6) in relation to said frame (29) in a given drilling direction (43) and means (13, 15) to support said frame (29) on the soil (1) at least toward the rear with reference to said drilling direction (43), characterized

• in that said displacement means for translation of said tool (6) in relation to said frame (29) in said drilling direction (43) includes:
• (a) means forming a slide (27,28) that is integral with said frame (29) and oriented parallel with said drilling direction (43),
• (b) a guide block (26) carried by said slide-forming means (27,28) and guided for translation therealong parallel with said drilling direction (43) in relation to said frame (29), said guide block (26) defining a housing (46) at least partly closed toward the rear and laterally and open toward the front in reference to said drilling direction (43),
• (c) pressure means (37,38) acting between said frame (29) and said guide block (46) in the direction of translation of the latter along said slide-forming means (27,28) in relation to said frame, at least in said drilling direction (43),
• (d) tube-forming means (20) having a rectilinear axis (44), the tube-forming means (20) being fitted in said housing (46) and in abutment in the interior of said housing, in relation to said guide block (26), toward the rear and laterally in reference to said drilling direction (43), into a position in which said axis (44) of said tube-forming means (20) is parallel with said drilling direction (43), but is free for translation within said housing (46) in opposite direction in relation to said drilling direction, and the dimension (L) of said tube (20) parallel with the axis thereof being larger than the dimension (L) of said housing (46) parallel with said drilling direction (43) so that said tube-forming means (20) has an end zone (19) projecting forwardly in reference to said drilling direction (43), outside said housing (46) of said guide block (26),
• and in that said tool (6) comprises
• (e) a boring bit (6) integrally carried by said end zone (19) of said tube (20) and externally having, successively from the front to the rear in reference to said drilling direction (43), a flat cutting edge across said axis (44) of said tube-forming means (20), a frustoconical cutting edge (16) revolving about said axis (44) and converging to the front in reference to said drilling direction (43), a cylindrical cutting edge (17) revolving about said axis (44) of said tube (20) and joining said frustoconical cutting edge, said cylindrical cutting edge (17) having a diameter (D) larger than the dimensions (d) that said tube (2) externally has in relation to its axis (44) and a dimension (.lambda.) measured parallel with said axis (44) that is smaller than that of said corresponding dimension (L) of said tube-forming means (20),
• (f) a stem integral with said boring bit (6) immediately behind said cylindrical cutting edge (17) of the latter in reference to said drilling direction (43), said stem (18) being inserted in said end zone (19) of said tube-forming means (20), detachable locking means (21) ensuring the integration of said stem (18) with said tube-forming means (20),
• (g) said guide block (26) has in reference to said drilling direction (43) a rear end zone where it integrally carries a plate (30) that closes said housing (46) toward the rear in reference to said drilling direction (43) so as to constitute a stop for an end (25) of said tube (20) opposite to said end zone (19) of the latter, and integrally carrying, inside said housing (46) and toward the front in reference to said drilling direction (43), a ring (31) that conforms in shape with said opposite end (25) of said tube (20) and immobilizes it transversely in relation to said drilling direction (43) and in that said guide block (26) has in reference to said drilling direction (43) a front end zone where it integrally carries a collar (32) that laterally closes said housing (46) in reference to said drilling direction (43) by surrounding said drilling direction in order to avoid any displacement of the tube (40) along a direction transverse to the drilling direction (43), said collar (32) conforming in shape with said tube (40) and immobilizing it transversely in relation to said drilling direction (43) in an intermediate zone (47) of said tube (40).