US3843984A — All metal self-locking screw fastener

Claim 1

Independent Claim 223 words

A method of fabricating a fastener having an external screw thread for engagement with a complementary internal screw thread of a complementary fastener, characterized by the steps of: forming the fastener with the external screw thread; forming a longitudinal axial bore of circular cross-sectional configuration in the leading end of the fastener with an axially outward portion of the bore increased in diameter and with the radial dimension of the circumferential wall of the bore thickened at the axially inward portion of the bore; expanding at least one minor circumferential portion of the thickened wall of the fastener radially outward to form a recess or recesses in the thickened wall of the fastener to provide the reduced portion of the bore with a non-circular cross-sectional configuration and to form the fastener with a corresponding radially outwardly protruding lobe or lobes and to cause the pitch diameter of the external screw thread to be locally increased to conform to the lobe or lobes; and enlarging the bore of the fastener to thin the circumferential wall, whereby the local increase in the pitch diameter of the external screw thread causes interference fit of the external screw thread with said complementary internal screw thread, the interference fit causing inward resilient displacing of the lobe or lobes by virtue of the thinned circumferential wall of the bore.

Claim 2

Independent Claim 223 words

A method of fabricating a fastener having an external screw thread for engagement with a complementary internal screw thread of a complementary fastener, characterized by the steps of: forming the fastener with the external screw thread; forming a longitudinal axial bore of circular cross-sectional configuration in the leading end of the fastener with an axially outward portion of the bore increased in diameter and with the radial dimension of the circumferential wall of the bore thickened at the axially inward portion of the bore; expanding at least one minor circumferential portion of the thickened wall of the fastener radially outward to form a recess or recesses in the thickened wall of the fastener to provide the reduced portion of the bore with a non-circular cross-sectional configuration and to form the fastener with a corresponding radially outwardly protruding lobe or lobes and to cause the pitch diameter of the external screw thread to be locally increased to conform to the lobe or lobes; and enlarging the bore of the fastener to thin the circumferential wall, whereby the local increase in the pitch diameter of the external screw thread causes interference fit of the external screw thread with said complementary internal screw thread, the interference fit causing inward resilient displacing of the lobe or lobes by virtue of the thinned circumferential wall of the bore.

Claim 3

Dependent Claim 80 words

A method as set forth in claim 1 in which the enlarging of the bore is concentric to the axis of the fastener and is of sufficient diameter to eliminate said recesses, whereby the wall of the fastener is locally increased in thickness by said lobe or lobes and the remaining portion of the wall of the fastener is of uniform thickness as measured from the internal diameter of the bore to the major diameter of said external screw thread.

Claim 4

Dependent Claim 29 words

A method as set forth iN claim 2 in which the fastener wall is locally increased in thickness by inserting a punch of polygonal configuration into the fastener bore.

Claim 5

Dependent Claim 31 words

A method as set forth in claim 1 in which three circumferential portions of the fastener wall are expanded to the form three outwardly protruding lobes on the external screw thread.

Claim 6

Dependent Claim 27 words

A method as set forth in claim 4 in which the three lobes as measured from center to center are substantially equally spaced circumferentially of the fastener.

Claim 7

Dependent Claim 19 words

A method as set forth in claim 5 in which the three lobes are of substantially equal circumferential extent.

Claim 8

Independent Claim 221 words

A method of fabricating a fastener having an external screw thread for engagement with a complementary internal screw thread of a complementary fastener, characterized by the steps of: forming a longitudinal bore in the leading end of the fastener of circular cross-sectional configuration with an axially outward portion of the bore increasing in diameter and with the radial dimension of the wall of the fastener thickened at the axially inward portion of the bore; expanding at least one minor circumferential portion of the thickened wall of the fastener radially outward to form a recess or recesses in the wall of the bore to make the bore noncircular in cross-sectional configuration and to form the fastener with a corresponding radially outwardly protruding lobe or lobes and to cause the pitch diameter of the external screw thread to be locally increased to conform to the lobe or lobes; and enlarging the bore to eliminate said recess or recesses in the wall of the bore and to form the fastener with an enlarged bore of uniform inside diameter, whereby the local increase in the pitch diameter of the external screw thread causes interference fit of the external screw thread with said complementary internal screw thread and the interference fit causes inward resilient displacing of the lobe or lobes by virtue of the enlarged bore.

Claim 9

Independent Claim 221 words

A method of fabricating a fastener having an external screw thread for engagement with a complementary internal screw thread of a complementary fastener, characterized by the steps of: forming a longitudinal bore in the leading end of the fastener of circular cross-sectional configuration with an axially outward portion of the bore increasing in diameter and with the radial dimension of the wall of the fastener thickened at the axially inward portion of the bore; expanding at least one minor circumferential portion of the thickened wall of the fastener radially outward to form a recess or recesses in the wall of the bore to make the bore noncircular in cross-sectional configuration and to form the fastener with a corresponding radially outwardly protruding lobe or lobes and to cause the pitch diameter of the external screw thread to be locally increased to conform to the lobe or lobes; and enlarging the bore to eliminate said recess or recesses in the wall of the bore and to form the fastener with an enlarged bore of uniform inside diameter, whereby the local increase in the pitch diameter of the external screw thread causes interference fit of the external screw thread with said complementary internal screw thread and the interference fit causes inward resilient displacing of the lobe or lobes by virtue of the enlarged bore.

Claim 10

Dependent Claim 83 words

A method as set forth in claim 7 in which the longitudinal bore is formed concentrically of the axis of the fastener and the enlarging of the bore is concentric to the axis of the fastener, whereby the wall thickness of the fastener is locally increased by said lobe or lobes and the remaining portion of the wall of the fastener is of uniform thickness as measured from the internal diameter of the bore to the major diameter of said external screw thread.

Claim 11

Dependent Claim 44 words

A method as set forth in claim 7 in which three circumferential portions are enlarged to create three outer lobes in the screw thread and in which the three lobes as measured from center to center are substantially equally spaced circumferentially of the fastener.

Claim 12

Dependent Claim 24 words

A method as set forth in claim 9 in which the three lobes are of substantially equal dimension as measured circumferentially of the fastener.

Claim 13

Dependent Claim 173 words

In a method of fabricating a fastener having an external screw thread which comprises: forming a longitudinal bore in the externally threaded fastener body with the bore having a reduced diameter inner axial portion and an outer axial portion of increasing diameter including a conically tapered surface; inserting a mandrel within said axial bore into contact with a minor circumferential area of the conically tapered surface; said mandrel having a tapered leading end whose angle of taper is no greater than the angle of taper of the conically tapered surface, and exerting a force on said minor circumferential area through said mandrel to expand at least one minor circumferential portion of the wall of the reduced diameter inner axial portion, whereby an axial force exerted against the conically tapered surface is converted to a radial force in expanding a minor circumferential portion of the wall of the reduced diameter portion to form an outwardly protruding lobe on the fastener and to locally increase the pitch diameter of the external thread on the fastener.

Claim 14

Dependent Claim 173 words

In a method of fabricating a fastener having an external screw thread which comprises: forming a longitudinal bore in the externally threaded fastener body with the bore having a reduced diameter inner axial portion and an outer axial portion of increasing diameter including a conically tapered surface; inserting a mandrel within said axial bore into contact with a minor circumferential area of the conically tapered surface; said mandrel having a tapered leading end whose angle of taper is no greater than the angle of taper of the conically tapered surface, and exerting a force on said minor circumferential area through said mandrel to expand at least one minor circumferential portion of the wall of the reduced diameter inner axial portion, whereby an axial force exerted against the conically tapered surface is converted to a radial force in expanding a minor circumferential portion of the wall of the reduced diameter portion to form an outwardly protruding lobe on the fastener and to locally increase the pitch diameter of the external thread on the fastener.

Claim 15

Dependent Claim 53 words

A method as set forth in claim 11 in which as viewed in longitudinal section the angle of taper of the leading end of the mandrel relative to the axis of the mandrel is less than the angle of taper of the conically tapered surface relative to the axis of the longitudinal bore.

Claim 16

Dependent Claim 32 words

A method as set forth in claim 11 in which the mandrel has a leading inner diameter which is the same or less than the diameter of the reduced inner diameter portion.

Claim 17

Dependent Claim 25 words

A method as set forth in claim 11 in which the axial bore is a blind bore formed in the leading end of the fastener.

Claim 18

Dependent Claim 25 words

A method as set forth in claim 11 in which three minor circumferential portions are expanded to form three corresponding outer lobes on the fastener.

Claim 19

Dependent Claim 25 words

A method as set forth in claim 15 in which the three lobes are measured center to center are equally spaced circumferentially of the fastener.

Claim 20

Dependent Claim 23 words

A method as set forth in claim 15 in which the three lobes are of equal dimension as measured circumferentially of the fastener.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1977-10-28	1978-04-29	1978-10-29	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1981-10-28	1982-04-29	1982-10-29	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1985-10-28	1986-04-29	1986-10-29	$7700.00	Window Closed / Lapsed

All metal self-locking screw fastener

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