Low torque wood screw

• US 5,516,248 A
• Filed: 09/07/1994
• Issued: 05/14/1996
• Est. Priority Date: 09/07/1994
• Status: Expired due to Term

• Current Assignee: Abbott-Interfast Corporation
• Original Assignee: Abbott-Interfast Corporation
• Inventors: DeHaitre, Lon
• Primary Examiner(s): Meyers, Steven N.
• Assistant Examiner(s): LUU, TUYET PHUONG PHAM
• Application Number:
  US08/302,130
• Time in Patent Office: 615 Days
• Field of Search: 411/386, 411/387, 411/399, 411/411, 411/424
• US Class Current: 411/387.2
• CPC Class Codes: F16B 23/0015 substantially rectangular, e.g. one-slot head
• CPC Class Codes: F16B 25/0015 the material being a soft organic material, e.g. wood or plastic F16B25/0031 takes precedence
• CPC Class Codes: F16B 25/0057 the screw having distinct axial zones, e.g. multiple axial thread sections with different pitch or thread cross-sections
• CPC Class Codes: F16B 25/0078 with a shaft of non-circular cross-section or other special geometric features of the shaft
• CPC Class Codes: F16B 35/041 Specially-shaped shafts shape of thread F16B33/02
• CPC Class Codes: F16B 35/065 with self-countersink-cutting means

Abstract

A low torque fastener screw for securing a wooden workpiece to a substrate includes an elongated body defining a longitudinal axis and having an enlarged head formed on one end, an external pointed thread formed on an opposite end, an elongated unthreaded shank between the enlarged head and the threaded end, and a reamer formed at the juncture of the shank and thread. The reamer has a plurality of longitudinal cutting edges formed about its periphery which ream out the hole formed by the threaded end to a diameter larger than the shank, thereby reducing frictional resistance to rotation of the screw and optimizing the torque applied by the driving tool.

Claims

1. A low torque fastener screw for securing a wooden workpiece to a substrate, the fastener screw comprising:

an elongated body defining a longitudinal axis;

an enlarged head portion disposed on an end of the elongated body, the head portion having a generally planar end surface disposed substantially transverse to the longitudinal axis and having a drive recess therein;

an external thread disposed on an opposite end of the elongated body and terminating in a point to facilitate entry of the screw into the wooden workpiece and substrate;

an elongated generally cylindrical shank coaxial with the longitudinal axis and disposed between the enlarged head and the thread; and

a generally annular reamer surface coaxial with the longitudinal axis and disposed between the external thread and elongated shank, the reamer surface having an outer diameter larger than the shank but less than a major diameter of the external thread so as to ream a clearance hole for substantially non-interfering entry of the elongated shank into the wooden workpiece as the fastener screw is driven through.

2. The fastener screw as in claim 1 wherein the enlarged head portion further comprises an underside defined by a generally concave annular surface interposed between the end surface and the shank.

3. The fastener screw as in claim 2 wherein the enlarged head portion further comprises a plurality of outwardly projecting serrations formed about a periphery of the concave surface, each of the serrations extending substantially from the end surface to the shank and being inclined relative to the longitudinal axis of the screw in a direction of a thread lead angle of the external thread so that the serrations burr into a fibrous surface of the wooden workpiece bending a portion of the fibrous surface surrounding the enlarged head portion in a direction of drive to reduce torque to ease countersinking of the enlarged head portion and effect a self-locking action with the fibrous surface as the screw is threaded into the fibrous surface.

4. The fastener screw as in claim 1 wherein the external thread further comprises a single lead thread.

5. The fastener screw as in claim 1 wherein the external thread further comprises a generally longitudinal chip relief slot formed therein adjacent the pointed end.

6. The fastener screw as in claim 1 wherein the reamer further comprises a plurality of axially extending serrations surrounding the elongated body.

7. The fastener screw as in claim 6 wherein the axially extending serrations further comprise an axial length substantially equal to a diameter of the external thread of the fastener screw.

8. The fastener screw as in claim 1 wherein the fastener screw further comprises a deck screw.

9. A low torque screw for securing a wooden workpiece to a substrate, such screw comprising:

an elongated unitary body divided into a first end and a second end along a longitudinal axis by a circumferential series of axially extending serrations of a generally larger overall diameter than a center portion of the first end;

an enlarged head portion disposed on a distal end of the unitary body at the first end, the head portion having a generally planar end surface disposed substantially transverse to the longitudinal axis of the center portion of the first end and having a drive recess therein, the head portion having an underside defined by a generally concave annular surface interposed between the end surface and the center portion of the first end;

an external thread disposed on the second end of the unitary body terminating in a point at a distal portion of the second end, the external thread having a generally longitudinal cutting edge and chip relief slot formed therein adjacent the pointed end.

10. The low torque screw as in claim 9 wherein the axially extending serrations are of an axial length substantially equal to a diameter of the external thread.

11. The fastener screw as in claim 9 wherein the external thread further comprises a single lead thread.

12. The fastener screw as in claim 9 wherein the fastener screw further comprises a deck screw.

13. A low torque screw fastener system for securing a wooden workpiece to a substrate comprising:

a wooden workpiece;

a substrate;

a fastener screw comprising;

an elongated body defining a longitudinal axis;

an enlarged head portion disposed on an end of the elongated body, the head portion having a generally planar end surface disposed substantially transverse to the longitudinal axis and having a drive recess therein;

an external thread disposed on an opposite end of the elongated body and terminating in a point to facilitate entry of the screw into the wooden workpiece and substrate;

an elongated generally cylindrical shank coaxial with the longitudinal axis and disposed between the enlarged head and the thread; and

a generally annular reamer surface coaxial with the longitudinal axis and disposed between the external thread and elongated shank, the reamer surface having an outer diameter larger than the shank but less than an outer diameter of the external thread so as to ream a clearance hole for substantially non-interfering entry of the elongated shank into the wooden workpiece as the fastener screw is driven through.