Self-locking fastener

Claim 2

A self-locking male member having a generally helical male thread, a female member having a generally helical preformed female thread mating with said male thread, said male thread having interfering convolutions spaced from the entering end of said male member which have root interference with the crest of said female thread and displace female thread material between the flanks of the mating threads, said male and female threads having limits of size prior to assembly so prescribed as to provide in assembly a flank clearance along said interfering convolutions such that there is space for the receipt of such displaced material, said male thread having in at least a partial convolution adjacent said entering end a swaging flank portion which is modified relative to the corresponding flank portions of said interfering convolutions by being offset towards the male thread flank portion which it confronts and hence spaced therefrom a distance less than the distance between confronting flank portions of said interfering convolutions, so that upon withdrAwal of said male member from said female member said swaging flank portion will swage the displaced material in said space back toward the crest of said female thread.

Claim 3

Male and female members as defined in claim 1, wherein said female thread prior to assembly has a minor diameter less than the minor diameter of said interfering convolutions of said male thread.

Claim 4

Male and female members as defined in claim 2, wherein said swaging flank portion is offset toward the male thread flank which it confronts a distance such that upon entry of said male member said swaging flank portion will mate closely with the opposing flanks of the female thread having at most a transition fit therewith.

Claim 5

Male and female members as defined in claim 1, wherein said female thread prior to assembly has a minor diameter greater than the minor diameter of said interfering convolutions of said male thread, said swaging flank portion being sufficiently offset toward the male thread flank which it confronts as to have positive interference with the opposing flanks of said female thread upon entry of said male member and to swage such opposing flank material toward the crest of said female thread for interference with said roots of said interfering convolutions of said male thread as aforesaid.

Claim 6

Male and female members as defined in claim 4, wherein said male thread has a raised root nearer than said swaging portion to said entering end adapted, upon withdrawal of said male member from said female member, to swage material displaced to the crest of the female thread by said swaging flank portion back along the flank thereof.

Claim 7

A self-locking screw having a generally helical male thread, said screw having interfering convolutions spaced from the entering end formed with an axially inclined truncated root being free of protuberances, said axially inclined root defining portions of maximum and minimum diameter, said screw being self-locking by root interference in said interfering convolutions when threadedly engaged with a female thread so dimensioned relative to said male thread as to provide flank clearance for the reception of material displaced from the crest of the female thread by said root interference, said screw having in at least a partial convolution adjacent its entering end a swaging flank portion along the flank thereof adjacent the inclined root portion of maximum diameter, said swaging flank portion being modified relative to the corresponding flank portions of said interfering convolutions by being offset from the remainder of the flank from which it extends toward the flank portion which it confronts and hence spaced therefrom a distance less than the distance between confronting flank portions of said interfering convolutions, so that upon withdrawal of said screw from a female thread dimensioned as aforesaid, said swaging flank portion will swage the material displaced from the crest of such female thread back toward such crest.

Claim 8

A self-locking screw having a generally helical male thread, said screw having interfering convolutions spaced from the entering end formed with an axially inclined truncated root being free of protuberances, said axially inclined root defining portions of maximum and minimum diameter, said screw being self-locking by root interference in said interfering convolutions when threadedly engaged with a female thread so dimensioned relative to said male thread as to provide flank clearance for the reception of material displaced from the crest of the female thread by said root interference, said screw having in at least a partial convolution adjacent its entering end a swaging flank portion along the flank thereof adjacent the inclined root portion of maximum diameter, said swaging flank portion being modified relative to the corresponding flank portions of said interfering convolutions by being offset from the remainder of the flank from which it extends toward the flank portion which it confronts and hence spaced therefrom a distance less than the distance between confronting flank portions of said interfering convolutions, so that upon withdrawal of said screw from a female thread dimensioned as aforesaid, said swaging flank portion will swage the material displaced from the crest of such female thread back toward such crest.

Claim 9

The screw defined in claim 6, wherein said partial convolution has a modified pitch which is different than the pitch of the remainder of said male thread, producing the aforesaid swaging flank portion on one side of said partial convolution and also producing a relieved flank portion on the opposite side thereof.

Claim 10

The screw defined in claim 6, wherein the half angle of said swaging flank portion measured from the thread crest is greater than that of the corresponding flank portions of the said interfering convolutions.

Claim 11

The screw defined in claim 8, wherein the half angle of the other flank portion of said partial convolution measured from the thread crest is less than that of the corresponding flank portions of said interfering convolutions.

Claim 12

The screw defined in claim 6, having a raised root portion nearer than said swaging flank portion to said entering end adapted, upon withdrawal of said screw from a female thread dimensioned as aforesaid to swage material displaced to the crest of such female thread by Said swaging flank portion back along the flanks thereof.

Claim 13

The screw defined in claim 6, wherein said swaging flank portion is disposed adjacent the root of said partial convolution and terminates below its crest.

Claim 14

The screw defined in claim 6, wherein the angle of said swaging flank portion as measured at the root is greater than that of the corresponding flanks of said interfering convolutions.

Claim 15

The screw defined in claim 12, wherein the angle of the other flank portion of said partial convolution as measured at the root is less than that of the corresponding flank portions of said interfering convolutions.