| 摘要 |
<p>1,149,649. Drilling pipes under pressure. T. D. WILLIAMSON Inc. 15 Sept., 1966 [16 June, 1966], No. 41247/66. Heading B3C. Apparatus for drilling a pipe containing fluid comprises a housing 10, a boring bar 11, and a lead screw 21. A nut 13 is secured to the top of the boring bar, co-operates with the lead screw, and is slidable in the non-circular bore of a tube 12. The latter is rotated by a worm and wheel drive 15, the worm of which can be driven at one end by a motor, or at the other end by a crank, a flywheel 20 being provided at one end. A slipping drive is provided between the tube 12 and the lead screw 21, and comprises a spider 22 keyed to the lead screw, and a thrust bearing 24 supported on the upper end 25 of tube 12, this end also being connected to a shoulder 27 on lead screw 21 via a ball bearing 26. A nut 28 is provided so as to adjust the degree of friction between the tube and lead screw. A friction holding connection between housing 10 and the tube 12 is provided, and comprises a spring-urged race 29 non-rotatably, but slidably, connected to housing 10 by a pin-andslot 32, 33, which frictionally engages balls 30 carried by spider 22 and supported in a race 31. In operation, nut 28 is tightened so that the lead screw, and tube 12 rotate together. Cap 37 is screwed on to the housing until the holding friction is enough to prevent rotation of the lead screw when the boring bar is rotated, so that the latter is fed at a high rate. When the tool encounters the work, the upward reaction of the boring bar, will increase the friction between nut 13 and lead screw 21, tending to cause the latter to turn and reduce the feed rate. The feed rate is therefore greater when the resistance to cutting is least, and slows down when the resistance increases. A window 41 in the housing allows the operator to see a scale on the boring bar so that he can read off the depth of cut.</p> |
