US 4,701,348 A · Method of coating the threads of a fastener

Abstract

A method of applying a coating, such as a fluorocarbon barrier coating, to the threads of a fastener, particularly suitable for applying a coating to a female fastener having a threaded bore. The method includes forming a fluid suspension of the coating material, such as an unpolymerized fluorocarbon in an organic solvent, forming a drop of the coating material fluid suspension on the tip of an ultrasonic transducer and bringing the tip into proximity with the fastener threads, which are preferably preheated. The ultrasonic tip is then vibrated in the ultrasonic range, exploding the drop and coating the fastener threads with a fine mist of the fluid suspension. The fastener is then heated to vaporize the solvent and polymerize the coating material where the coating material is polymerizable. When coating female fasteners, the tip of the ultrasonic transducer is preferably lowered within the thread cylinder, adjacent the top thread.

Claims12

Dependent claims

A method of coating the threads of a fastener, comprising the following steps:

(a) forming a fluid suspension of said coating material in the form of a fine powder in a fluid solvent;
(b) heating said fastener threads;
(c) forming a drop of said coating material fluid suspension on the tip of an ultrasonic head and bringing said head into proximity with said heated fastener threads;
(d) vibrating said head in the ultrasonic range, exploding said drop and coating said threads with a fine mist of said coating material fluid suspension;
and
(e) further heating said fastener threads to vaporize said solvent, forming a dry coating on said threads.

3 more elements

A method of coating the threads only of a plurality of female fasteners with a relatively thin coating of a solid coating material, each fastener having a threaded bore and said method comprising the following steps:

(a) forming a suspension of said coating material in the form of a relatively fine powder suspended in a vaporizable fluid solvent;
(b) moving said fasteners individually below the tip of an ultrasonic transducer and forming a drop of said coating material suspension on the end of said ultrasonic transducer tip, and tip having a diameter which is substantially less than the internal diameter of said female fastener threaded bores;
bores;
(c) lowering said ultrasonic transducer tip into one of said threaded female fastener bores and vibrating said tip in the ultrasonic range, exploding said drop and coating said threaded female fastener bore with a fine mist of said coating material fluid suspension;
and
(d) raising said transducer tip and further heating said fasteners to vaporize said solvent forming a dry coating on said threaded bore.

3 more elements

Dependencies are inferred from the claim text.

Method of coating the threads of a fastener

Life of this patent

Method of coating the threads of a fastener

Life of this patent

Abstract

Claims12