GB565418A - Device for inserting wire coils in tapped holes - Google Patents

Abstract

565,418. Inserting helices in tapped holes. AIRCRAFT SCREW PRODUCTS CO., Inc. May 7, 1943, No. 7255. Convention date, June 16, 1942. [Class 83 (iii)] Wire helices are inserted into tapped holes, e.g. to provide a wear resistant thread in soft material, such as wood, aluminium, or artificial material by contracting the diameter of the helix during insertion and then releasing the helix to permit it to spring into place. The helix, formed initially oversize, may have the leading end 11, Fig. 2, slightly reduced in diameter and provided with a tang 13. The inserting tool is in two main parts 14, 18. The part 25 of the sleeve member 18 is formed of a diameter at 26 to receive the uncontracted helix 10 and it is considerably cut away at 27 to permit lateral insertion of the helix. The front part 22 has a thread 23 of the diameter, or somewhat less than the diameter, of the tapped hole in which the helix is to be screwed. The mandrel 14, which has a tapered and slotted end 15, is then advanced through the helix to engage the tang in the slot and by means of the end 17 shaped for holding a driving and the knurled part 19 of the sleeve, the parts are relatively rotated further to coil the helix on the reduced diameter of the mandrel, leaving a part of a turn still engaged in the threaded end 22 to hold the helix contracted. The parts 14, 18 are then locked against reverse rotation by a screw 28 pressing on the mandrel through a fibre pad. Whilst so held the helix is screwed into the tapped hole to be lined and finally further movement of the mandrel relatively to the sleeve releases the helix and allows it to expand and seat itself firmly in the hole. Reverse rotation of the mandrel then removes the tang. In modifications, the rear end of the sleeve member is reduced in diameter, split and provided with a taper thread for a clamping nut to close this part of the sleeve on the mandrel. The helix-engaging end of the .sleeve tapers from the initial size of the helix to the contracted size. The helix then need not have a leading end 11 of reduced diameter.