Flow drill screw, apparatus equipped with flow drill screw, and method for joining at least two workpieces.

Abstract

The present invention relates to a flow drill screw having a shank and a screw head having a drive configuration, wherein the shank comprises a partial tapping thread and a threadless tip for hole forming, the tip for hole forming having at least a partially polygonal cross section, the polygonal cross section having a plurality of convex first peripheral portions with a large radius of curvature and a plurality of convex second peripheral portions with a small radius of curvature, each of the second peripheral portions with a small radius of curvature positioned between the two first peripheral portions with a large radius of curvature, and the increase in the cross-sectional area of ​​the tip is greater in a first region of length extending from the free end of the tip to 0.2 to 0.4 times the length from the free end of the tip, particularly up to one-third of the length, than in the region of the remaining portion of the tip up to the tapping thread.

Claims

1. A flow drill screw (10) having a shank (12) and a screw head (14) having a drive configuration, In a flow drill screw (10), the shank (12) partially has tapping threads (24) and a threadless tip (22) for hole formation, the tip (22) for hole formation having at least partially a polygonal cross-section, the polygonal cross-section having a plurality of convex first peripheral portions with a large radius of curvature and a plurality of convex second peripheral portions with a small radius of curvature, each of the second peripheral portions with a small radius of curvature being positioned between two of the first peripheral portions with a large radius of curvature, A flow drill screw (10) characterized in that the increase in the cross-sectional area of ​​the tip (22) is greater in a first region (30) of the length extending from the free end of the tip (22) to 0.2 to 0.4 times the length from the free end of the tip (22), particularly up to one-third of the length, than in a region extending over the remaining portion of the tip (22) to the tapping thread (24).

2. The flow drill screw (10) according to claim 1, characterized in that the increase in the cross-sectional area of ​​the tip (22) in a second region (32) that is provided following the first region (30) and extends to 0.4 to 0.7 times the length of the tip (22), particularly occupying two-thirds of the length of the tip (22), is greater than the increase in the cross-sectional area in a third region (34) that is provided following the second region (32) and extends to the beginning of the tapping thread (24), particularly occupying three-thirds of the length of the tip (22).

3. The flow drill screw (10) according to claim 1 or 2, characterized in that the difference (dimension K) between the diameters of the circumscribed circle (dimension C) and the inscribed circle (dimension E) of the polygonal cross-section changes when viewed over the length of the hole-forming tip.

4. The flow drill screw (10) according to claim 3, characterized in that the difference (dimension K) between the diameters of the circumscribed circle and the inscribed circle of the polygonal cross-section is greater than 0, and in particular 0.1 mm or more, when viewed over the entire length of the hole-forming tip.

5. The flow drill screw (10) according to claim 3 or 4, characterized in that the difference (dimension K) between the diameters of the circumscribed circle and the inscribed circle of the polygonal cross-section increases from the free end of the hole-forming tip, and then decreases again up to the transition portion to the tapping thread.

6. The difference in diameter (dimension K) between the circumscribed circle and the inscribed circle of the polygonal cross-section increases within the first region (30) of the length of the hole-forming tip (22) from the free end of the hole-forming tip, and then decreases again up to the transition to the tapping thread (24), as described in claim 5, for the flow drill screw (10).

7. The difference in diameter between the circumscribed circle and the inscribed circle of the polygonal cross-section (dimension K) increases from the starting value to 2 to 3 times the starting value, and in particular, the starting value is measured at a point 1 / 10 to 1 / 20 of the length of the hole-forming tip from the free end of the tip, characterized in that, the flow drill screw (10) according to claim 5 or 6.

8. The flow drill screw (10) according to claim 7, wherein the starting value of the difference (dimension K) between the diameters of the circumscribed circle and the inscribed circle of the polygonal cross-section is 0.1 mm to 0.2 mm, and more particularly 0.1 mm to 0.15 mm.

9. The difference in diameter (dimension K) between the circumscribed and inscribed circles of the polygonal cross-section increases within the first region (30) of the length of the hole-forming tip (22) from the free end of the hole-forming tip (22), and then decreases again to the starting value at the free end of the tip, particularly at 1 / 20 to 1 / 10 of the length of the tip, or decreases to 1.6 to 1.3 times the starting value, as described in any one of claims 1 to 8.

10. A flow drill screw (10) according to any one of claims 1 to 9, characterized in that, when viewed over the length of the hole-forming tip, the angular positions of the first and second peripheral portions with respect to the central longitudinal axis of the shank change.

11. The flow drill screw (10) according to claim 10, characterized in that the angular positions of the first and second peripheral portions vary over the entire length of the tip, between an angle greater than 0° and less than 50°, particularly between 20° and 45°.

12. The flow drill screw (10) according to claim 10 or 11, characterized in that the angular positions of the first and second peripheral portions change more significantly within the first region (30) of the length of the tip (22) than within the second region (32) and third region (34) of the length of the tip (22), the second region (32) is provided following the first region (32), and the third region (34) extends to the transition portion to the tapping screw thread (24).

13. The flow drill screw (10) according to claim 11 or 12, characterized in that the angular positions of the first peripheral portion and the second peripheral portion vary within the first region (30) of the length of the tip (22) between an angle greater than 0° and less than 50°, particularly between 20° and 45°.

14. A flow drill screw (10) according to any one of claims 1 to 13, characterized in that the radius of curvature of the free end of the tip (22) is 0.4 mm to 0.6 mm.

15. The flow drill screw (10) according to any one of claims 1 to 14, characterized in that the length of the hole-forming tip (22) is 40% to 60%, particularly 50%, of the length of the shank (12).

16. The flow drill screw (10) according to any one of claims 1 to 14, characterized in that the flow drill screw (10) is manufactured from alloy or non-alloy tool steel.

17. The flow drill screw (10) according to claim 16, characterized in that the tool steel is hardened.

18. The flow drill screw (10) according to claim 16 or 17, characterized in that the flow drill screw (10) has a corrosion-resistant coating and a seal.

19. An apparatus comprising a flow drill screw (10) according to any one of claims 1 to 18, and at least two workpieces (62, 64) joined to each other by the flow drill screw (10), The apparatus wherein the length of the tip (22) is greater than or equal to the length of the through hole produced in the at least two workpieces (62, 64) by the flow drill screw (10).

20. A method for joining at least two workpieces (62, 64) using a flow drill screw (10) according to any one of claims 1 to 18, A method for joining at least two workpieces (62, 64), characterized by manufacturing a through hole with the hole-forming tip (22) of the flow drill screw (10), and after manufacturing the through hole, tapping threads (24) of the flow drill screw (10) into the through hole.

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