Abstract Method of making a self-locking threaded element, e.g. a screw, including a strongly adhered plastic body or locking patch on its threaded surface where the locking patch is formed with a special configuration for effective locking engagement over a wide range of clearances between the element and mating threaded surfaces, in which method a stream of fine particles of heat softenable resin is directed against a threaded surface portion of a heated metallic element at a temperature lower than that effective to form a continuous convex curved deposit of resin. The threaded portion is kept in the stream of resin particles for a time sufficient to fill the valleys between threads to an extent of at least one-third in areas of the valleys adjacent the central line of the locking patch and to form thin resin deposits in areas spaced from the central line to give in effect an interupted ridge or bar useful to provide locking action over a wide range of clearances.
The method of providing a self-locking element as defined in claim 1 in which said threaded portion is brought to a temperature which will remain above about 400* F. for at least about 5 seconds after first contact with said stream of resin particles and said resin particles have a particle size of less than 400 microns.
Claim 2
Dependent Claim
26 words
The method of providing a self-locking element as defined in claim 2 in which said resin particles have a size of from 10 to 200 microns.
Claim 3
Dependent Claim
32 words
The method of providing a self-locking element as defined in claim 2 in which a resin primer coat is disposed on the surface of said threaded portion before heating said threaded portion.
Claim 4
Dependent Claim
88 words
The method of providing a self-locking element as defined in claim 2 in which said stream is a mixture of a major portion of fine particles of said normally hard thermoplastic and a minor portion of a heat-softenable tying agent, and said tying agent is fused on the surface of said threaded portion by heat from the surface of said threaded portion to wet said portion and to aid in building up and adhere deposits of said normally hard thermoplastic resin on the surface of said threaded portion.