GB299677A - An improved apparatus for use in oil and like wells - Google Patents

Abstract

299,677. Ferguson, J. April 17, 1928 Milling - machines.-Superfluous lengths of oil-well casings are cut out and removed by means comprising a planetary milling-cutter with radial feed. The cutter is suspended in the well by a series of tubes 5 connected by screwed couplings each tube supporting a section of driving-shaft 4 by means of a ball race or washer at its upper end. The shaft sections are squared at their lower ends and formed with corresponding sockets at their upper ends, and the assembled shaft is driven from fast and loose pulleys through universal joints and a telescopic shaft 12 and bevel gearing 8 supported above the well. Reduction gearing is housed at 27. A further telescopic shaft transmits motion to the cutter 3 which is mounted in a slide in a slotted tube 21. A bar 35 slides in guides in the tube and is slotted to engage a pin 23b in the cutter slide. A screw 36 engages a nut secured to the bar 35 and is fixed to a guide frictionally engaging the well tube by contact pads 39<a> carried by spring arms. The screw 36 is thus held stationary during rotation of the tubes 5 and attached tube 21 causing the bar 35 to slide through its guides. The slot in the bar is of curved form to feed the cutter radially at a diminishing rate and return the cutter slide after the casing is severed without reversing the driving gear. Slow rotation of the tubes 5 to impart the orbital movement to the cutter is imparted by worm gearing 15 driven by ratchet gearing 32 from an adjustable throw crank on the end of the shaft 9. Two pawl carriers are provided one driving on the up stroke and the other on the down stroke and each pawl carrier has two pawls spaced to the effective pitch of the ratchet wheel in order to provide a fine adjustment for the rate of the orbital motion.. The ratchet wheel is secured to its shaft by a friction clutch to enable the motion to be disengaged. To adjust the radial position of the cutter slide to suit different diameters of casing a series of spaced holes for the pin 23<b> provide a coarse setting, the slide itself being in two parts bolted together with interposed shims for a fine setting. A second set of spring pads 19<a> engage the casing above the plane of the cut.