| 摘要 |
<p>PCT No. PCT/GB94/00544 Sec. 371 Date Oct. 30, 1995 Sec. 102(e) Date Oct. 30, 1995 PCT Filed Mar. 17, 1994 PCT Pub. No. WO94/21409 PCT Pub. Date Sep. 29, 1994A threaded hole may be formed in a lid of an underground petrol tank without emptying the tank or removing the lid, using a tool (FIG. 3) having a taper tap section (61), an intermediate tap section (62) and a final tap section (63). At the leading end of the tool, there is a reamer section (60) and supported on the free end of the tool is a centerless hole cutter (50). A resilient mounting transmits drive from the main part of the tool to the cutter (50), but allows the cutter to float. A sleeve (23) surrounds the tool, so that a column of inert gas may be caused to lie in the cutting region. A magnet (57) mounted within the cutter (50) catches and holds a released disk of the cover. Also described is a rig (FIG. 1), for operating the tool (FIG. 3), and a method (FIG. 5) of securing a collar threaded into a hole formed by the tool.</p> |
