| 摘要 |
1,067,917. Coating apparatus. ELASTIC STOP NUT CORPORATION. Nov. 12, 1964 [June 1, 1964; Sept. 23, 1964], No. 46181/64. Headings B2K and B2L. [Also in Division F2] In order to render a nut or bolt self-locking a mound of thermoplastic material in powdered form is applied over a limited area of the threaded surface and heated so that the thermoplastic material flows into a free pool. Apparatus for depositing the powder over a limited area of a bolt thread surface comprises a ceramic support 112 having a slot 114 to receive and mask at least one half of the periphery of a bolt 86. A metal mask 116, which may be made of metal foil encases the ceramic cradle 112 and bolt 86 and is provided with an aperture 118. The mask 116 is in contact with the shank of the bolt and is earthed so that electrostatically charged granules of the powder sprayed from an electrostatic gun 20 are directed through the aperture 118 and de- Dosited on the unmasked. earthed thread surface. After the powder has been sprayed on to the bolt the latter is disconnected from the ground connection and the bolt inserted in a heating oven or other heating unit and brought to the desired melting temperature. The powdered thermoplastic material is applied to a nut 2 by apparatus which comprises a sheet metal sleeve 66 having a V-shaped notch 68 at one end and a flange 70 for supporting the nut. A plunger 74 is slidably mounted in the sleeve 66 and formed with a stop shoulder 76, the forward end being cut way on one side of its axis to form a transversely flat and longitudinally tapered surface 80 which forms with the wall of the sleeve a metering notch. Powdered thermoplastic material is fed into the sleeve 66 when the plunger is in retracted position, the nut is inserted over the sleeve into abutting engagement with the flange 70 and telescoping of the sleeve with the nut is effected by suitable abutments 82, 84 being brought into position to hold the nut and sleeve against axial movement. The nut is then conveyed to a supported plate and positioned in the magnetic field of a high frequency induction coil and removed from the forward end of the sleeve to allow the thermoplastic material to fuse into a free pool. The thermoplastic material may be a polyamide such as nylon 11.
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