Patent EA-001018-B1 (EA)
Title: Screw for fastening metal or plastic sections or plates onto a base
Inventor: PALM ERICH
IPC: E04D3/36
Filed: 1997-10-09
Abstract: 1. A screw for fastening metal and/or plastic sections or plates to a substructure, comprising a shank with a threaded portion and a drive portion for applying a driving device, characterized in that the portion (6) of the shank (2) adjacent to the drive portion (3) flares toward the drive portion (3) conically, in the manner of a stepped cone or following a curve as viewed in cross section, and in that the diameter (DK) of the end of the flaring portion (6) of the shank (2) close to the drive portion is larger than the diameter (D2) of the borehole (14) receiving the screw (1) in the section (10) to be fastened and thus is also larger than the core diameter (D1) of the threaded portion (5) of the screw (1). 2. A screw according to claim 1, characterized in that the flaring portion (6) of the shank (2) extends directly to the drive portion (3) or to the underside (7) of the drive portion (3) formed as the screw head. 3. A screw according to claim 1, characterized in that the diameter (DK) of the end of the flaring portion (6) of the shank (2) close to the drive portion is larger than the outside diameter (DG) of the threaded portion (5) on the shank (2). 4. A screw according to one of claims 1 to 3, characterized in that the drive portion (3) comprises two regions (27, 28) disposed successively in axial direction with different structures for a tool drive. 5. A screw according to claim 4, characterized in that one region (27) of the drive portion (3) is designed for engagement of the driving tool and the other region (28) is designed for application of a tool for reverse rotation of the screw (1) if necessary, wherein a predetermined breaking point (29) acting as a stripping safeguard is formed between the two regions (27, 28) of the drive portion (3). 6. A screw according to claim 1, characterized in that the end of the shank (2) facing away from the drive portion (3) is constructed as the boring part (4). 7. A screw according to claim 1, characterized in that the end of the shank (2) facing away from the drive portion (3) is constructed as the penetration point (30) which self taps the borehole. 8. A screw according to claim 1, characterized in that the threaded region (5) of the shank (2) is of double-threaded construction. 9. A screw according to claim 1, characterized in that the threaded region (5) of the shank (2) is formed with a self-cutting thread. 10. A screw according to claim 8 or 9, characterized in that the threaded region (5) of the shank is constructed in the manner of an orbiform curve, for example with trilobular shape. 11. A screw according to one of claims 1 to 3, characterized in that the flaring portion (6) is trumpet-shaped. 12. A screw according to one of claims 1 to 3, characterized in that the flaring portion (6) is bell-shaped. 13. A screw according to one of claims 1 to 3, characterized in that the flaring portion (6) has the shape of a truncated cone. 14. A screw according to one of claims 1 to 3, characterized in that the drive portion (3) for a driving device is designed directly as an internal drive in the flaring portion (6) of the shank (2). 15. A screw according to claim 1 and any of the preceding claims, characterized in that the flaring portion (6) is provided on its surface with projections and/or depressions, with ribs (31), grooves, knurlings or the like.