Patent GB-564057-A (GB)
Title: Improvement in method and means for coiling wire inserts for screw connections
IPC: B21F3/04
Filed: 1942-11-27
Abstract: 564,057. Coiling. AIRCRAFT SCREW PRODUCTS CO., Inc. Nov. 27, 1942, No. 16848. Convention date, Jan. 31, 1942. [Class 83 (iv)] In making wire coil inserts for screw connections, particularly inserts such as described in Specification 497,309, [Group XXV], wire is drawn to a cross-section having side portions converging outwardly with respect to the axis, but at a slightly smaller angle than that desired in the finished coil so as to compensate for changes during coiling, and the wire is then gripped over a length somewhat smaller than the diameter of the insert to form a tang, and coiling is started from the end of the length to produce a coil of external diameter corresponding to the male member of the connection while guiding the wire to prevent it twisting about the wire axis and then cutting and releasing the coil. The wire may have a rounded or angular base portion. In the former case, the rounded portion is slightly larger than that required and in the latter case the angle of the base portion is slightly greater than that required in the finished insert. The wire may be pear-shaped, or diamond shaped in crosssection and is made by first drawing round stainless steel or bronze wire through a carbide die, a steel wire being first annealed, pickled, cleaned and oxide coated ; and a bronze wire cleaned. An oxide coating is then provided and the wire drawn through grooved rolls to produce the desired section. The shaped wire may be fed by a reciprocating gripper feed 19 through straightening-rolls 141 and passes through a two-part guide 15 with a groove of shape corresponding to that of the wire, and then through a severing device 16 into the coiler 17. Alternatively, the wire may be fed by hand directly through the guide, cutter and coiler. The coiler consists of a screw-threaded rotary mandrel 42, Fig. 5, provided with adjustable end stops 45 and 98, 99, and keyed to a hollow shaft 33 rotated by a crank 39 in ball bearings 29, 30. The mandrel is traversed in a screw-threaded fixed member 51, the grooves in the members 51, 42 together corresponding to the cross-section of the wire and engaging between them a wire coil 53 of similar shape. At the end of the member 51 is secured a die 54 having a similar thread groove to co-operate with the mandrel to effect the coiling and at the same time to size the wire. The severing device comprises a segment 72, Fig. 3, with grooved face 74 co-operating with a grooved fixed blade 78. The segment is mounted on a spindle 73, Fig. 6, having a squared end on which is mounted a lever 84 controlled by a spring 87<1> so as normally to return the cutter into inoperative position. The lever 84 is connected by a link 90 and lever 93 to a hand lever 95. The squared end also carries a lever 85 which engages the stop 98 towards the end of the coiling operation, but prior to severing the coiled length. After passing the wire through the guide 15 into the cutter, the lever 95 is operated to cut the forward end of the wire on a slant, as shown at 13, Fig. 2. Then the feed mechanism 19 is operated to feed the wire through a slot 61, Fig. 8, in the end of the mandrel. This slot is flared 'at 62 so that the wire may be coiled round the first turn of the groove in the mandrel which is of smaller diameter than the remainder so as to facilitate subsequent insertion of the coil into the screw connection. The other side of the slot has a grooved face 68 to prevent the wire tilting in the slot and the end is bevelled at 67. On rotation of the mandrel the wire is guided through the groove in the blade 78 and by a roller 69 on the die face. When the stop 98 engages the lever 85 coiling is stopped and the lever 95 operated to sever the rear end of the wire. At the same time the lever 85 is raised so that the coiling of the end of the wire may be completed. When the end of the coil is free of the die it opens out by spring tension and is pushed forward by the bevelled end 67 of the mandrel. -It can be stripped off the mandrel by reverse rotation thereof. The tang 11 may be notched at 14 to facilitate severance thereof after the coil has been inserted into the screw connection. The wire feed consists of a pair of wedge-shaped jaws 117, 118, Fig. 4, laterally movable in a slot in a bar 111 connected by a link 135 to an operating lever 133, the bar being mounted in a groove in a slidable plate 108 which is normally held in position by a spring-pressed ball 128. The plate 108 has lateral slots 110 to receive wedge-shaped members 114, 115, separated by balls 123 from the jaws 117, 118. When the lever 133 is pushed forward the jaws close on the wire 20 by wedge action, and the plate 108 is then traversed together with the bar 111. On retraction of the lever the jaws are first released and the plate 108 withdrawn when the jaws the rear side of the slot 110. The position and stroke of the feed lever may be variedby adjustable stops 138 secured in slots 139, 140. In an automatic machine, a driving shaft 206 carries cams 212, 211, 210 respectively for rotating the mandrel, effecting the feed and operating the cutter. In such apparatus, the stops 45, 98 and lever 85 of the previous form are dispensed with.' The cam 212 operates a lever 228 which reciprocates a rack 224 connected by exchangeable gearing with the mandrel shaft, the cam 211 operates a spring controlled lever 242 connected to the feed mechanism and the cam 210 operates a lever 235 on the cutter shaft 73. In one revolution of the shaft 206, the rack is first advanced by the cam 212, then stopped, then again advanced short distance and then returned. The cams 211 and 210 reciprocate the levers 242, 235 at different times once in each revolution. In starting, the shaft 206 is turned by hand until the forward end of the wire projects from the cutter and is severed thereby. The Specification as open to inspection under Sect. 91 states that the wire may be of round, square, or unsymmetrical section. This subjectmatter does not appear in the Specification as accepted.