Patent GB-1198642-A (GB)
Title: Method and Apparatus for Making Self-Locking Internally Threaded Fasteners.
IPC: B05B12/16
Filed: 1967-05-17
Abstract: 1,198,642. Endless conveyers, shoots. ELASTIC STOP NUT CORP. OF AMERICA. 17 May, 1967 [31 May, 1966], No. 22831/67. Headings B8A and B8S. [Also in Divisions B2 and F2] A lock nut is made by establishing a deposit of plastics powder upon the screw-threaded surface with the boundaries of the deposit spaced axially from the ends of said surface, and by heating the nut to fuse the powder deposit for causing the latter to adhere to said surface. Nuts 30 slide down a shoot, and after passing under an axial length-gauging bar, enter a hopper 118, where they lodge in successive notches 128 formed in the periphery of a disc 120 rotating about a horizontal axis. The nuts are retained in the notches by a shroud plate 138 until they engage an inclined surface 142 on a guide bar 144, and thereby drop on to the upper run of an endless conveyer chain 146 between successive lugs 150 projecting upwardly from the latter. The nuts are then transferred to pins 32 made from a fluoroplastic and projecting horizontally from an endless conveyer belt 34 constructed from a phenolic resin. Each pin 32 has a shank 40 and a reduced end portion 42 joining shank 40 at a shoulder 180. Portion 42 is cut away to form a shoulder 44 and an inclined portion 50. The path of belt 34 progressively approaches that of chain 146 until the portions 42 enter the bores in the nuts 30. Failure of a pin to engage in a nut results in the displacement of a spring-biased lever for actuating means adapted to stop the apparatus. The nuts are then orientated angularly on the pins by engagement with a flat bar 64 and any electrostatic charge thereon is discharged by means 66. Belt 34 is then supported on a rigid track 182 and confined thereto by a guide roller 202, track 182 being so arranged as to incline pins 32 upwardly at an angle of about 45 degrees.The nuts are then seated on the shoulders 180 by engagement with a downwardly-biased roller 196 mounted in a frame 68, before passing to means 75 adapted to fill the cavity 70, defined between shoulder 44, inclined portion 50 and the adjacent screw-threaded surface of the nut, with plastics powder 76 such as nylon 11. Means 75 comprises a rotatable but normally stationary disc 218 having a throat 216 communicating with a funnel 214 containing powder 76, a rotatable but normally stationary disc 224 coaxial with disc 218 and formed with a slot 226 normally communicating with throat 216, and a disc 228 coaxial with discs 218, 224 and continously rotated by means of a shaft 230. Disc 228 carries a number of spouts 232 adapted, on rotation of disc 228, to communicate successively with slot 226 to convey powder to the cavity 70 of a pin and nut arranged to pass in synchronism under spout 232. The angular position of disc 218 may be varied to regulate the amount of powder delivered. Disc 224 is connected by a linkage to means adapted, when the apparatus is inoperative, to turn disc 224 for positioning slot 226 out of communication with throat 216. A spout 232, on reaching a position diametrically opposite slot 226, communicates, via passages 260, 264 and a nozzle 226, with a compressed air duct, for discharging any remnants of powder therefrom. Each nut on leaving the means 75 passes under a compressed air jet 77 for removal of excess powder from cavity 70, and the end face of the nut is then cleaned by a rotary brush 90 associated with electrostatic discharge means 91. The nuts then pass through the field of high frequency induction heating coil means 97, whereby the plastics powder fuses and adheres as a patch to the screwthreaded surface. The nuts then travel through a comparatively long path before being finally removed from the pins 32 by stripper means 98. After leaving the heating means 97 the pins 32 are returned to the horizontal position and thereby project radially inwards while passing over the end roller 312, the centrifugal force developed at roller 312 thus tending to maintain the nuts upon the shoulders 180. Natural cooling may be assisted by air blown on the pins from a perforated tube 314, and the nuts may be additionally cooled by contact with water in a trough 316. The stripping means 98 comprises a pair of spaced-apart plates between which the pins 32 pass, and which diverge from the path of belt 34. The stripped pins are cleaned by rotary brushes 350 and pass through air jets from a perforated pipe 354.