Self-tapping screw fastener with improved thread construction

Details Self-tapping screw fastener with improved thread construction Self-tapping screw fastener with improved thread construction

Filed on

1975-06-20

Date issued

1977-06-07

Examiner

Frazier, Roy D.

Other Related Categories

85 47, F16B 3302

Type

Patent

Status

active

Patent number

040275736

Description

ABSTRACT:
A screw fastener formed with improved thread construction adapted to provide a staged or graduated entry into a workpiece. The fastener comprises a shank section formed with an integral driving head at one end and a tapered or conical point section at the other end, and a raised helical thread extending from near the tip of the conical point substantially throughout the length of the point and shank sections. The diameter of the thread increases gradually from the point tip along the length of the conical surface and then decreases in diameter - or increases at a lesser degree - as it approaches the cylindrical shank section.
The fastener may also comprise a second raised helical thread, parallel to and lying within the first thread and extending from near the junction of the conical point section and the cylindrical shank section substantially throughout the length of the shank. The leading edge of the second thread extends part-way down the conical point and overlaps axially the decreasing diameter portion of the first thread.
A modified version of the present invention includes a screw of the type described with a relatively short lead screw formed on the point near the tip and a substantial gap with no threads along the conical point surface leading to the shank section. This modification is intended primarily for joining lamina together.

REFERENCES:
patent: 408531 (1899-08-01), Rogers
patent: 449887 (1891-04-01), Rogers
patent: 684774 (1901-10-01), Baggs
patent: 1827615 (1931-10-01), Rosenberg
patent: 2382019 (1945-08-01), Miller
patent: 3124408 (1964-03-01), Oestereicher
patent: 3207023 (1965-09-01), Knohl
patent: 3703843 (1972-11-01), Laverty
patent: 3861269 (1975-01-01), Laverty
patent: 3902399 (1975-09-01), Yotti
patent: 3942405 (1976-03-01), Wagner

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