EXPANSION ANCHOR WITH BULGED ZONE

Abstract

An expansion anchor including an anchor bolt, and at least one expansion shell located at the anchor bolt, wherein the anchor bolt includes a wedge zone for expanding the at least one expansion shell, an abutment zone forming a rearward stop for the expansion shell, the abutment zone being located rearwardly of the wedge zone, and a rear zone for intruding tensile force into the anchor bolt, the rear zone being located rearwardly of the abutment zone, and wherein, located between the abutment zone and the rear zone, and spaced from the abutment zone, the anchor bolt includes a bulged zone, which radially protrudes on the anchor bolt.

Claims

1-16. (canceled)

17. An expansion anchor comprising: an anchor bolt; and at least one expansion shell located at the anchor bolt; the anchor bolt including: a wedge zone for expanding the at least one expansion shell; an abutment zone forming a rearward stop for the expansion shell, the abutment zone being located rearwardly of the wedge zone; a rear zone for intruding tensile force into the anchor bolt, the rear zone being located rearwardly of the abutment zone; and between the abutment zone and the rear zone, and spaced from the abutment zone, a bulged zone radially protruding on the anchor bolt.

18. The expansion anchor as recited in claim 17 wherein in the bulged zone (16), the anchor bolt has a larger maximum radius or a larger maximum diameter than in the abutment zone.

19. The expansion anchor as recited in claim 17 wherein the anchor bolt includes an intermediate zone located between the bulged zone and the abutment zone.

20. The expansion anchor as recited in claim 19 wherein the intermediate zone is threadless,

21. The expansion anchor as recited in claim 19 wherein the intermediate zone has a greater longitudinal extension than the abutment zone.

22. The expansion anchor as recited in claim 17 wherein a distance of a least parts of the bulged zone from the abutment zone equals a distance of a least parts of the wedge zone from the abutment zone.

23. The expansion anchor as recited in claim 17 wherein the bulged zone has bulged zone channels.

24. The expansion anchor as recited in claim 23 wherein the bulged zone channels run parallel to a longitudinal axis of the anchor bolt.

25. The expansion anchor as recited in claim 23 wherein the bulged zone channels are surface grooves.

26. The expansion anchor as recited in claim 17 wherein the wedge zone has wedge zone channels.

27. The expansion anchor as recited in claim 26 wherein the wedge zone channels are surface grooves.

28. The expansion anchor as recited in claim 26 wherein the bulged zone has bulged zone channels and at least some of the wedge zone channels are axially aligned with the bulged zone channels.

29. The expansion anchor as recited in claim 17 wherein in the abutment zone, the anchor bolt includes an abutment ring radially protruding on the anchor bolt.

30. The expansion anchor as recited in claim 17 wherein in the rear zone, the anchor bolt includes an outer thread.

31. A method for manufacturing an expansion anchor as recited in claim 17, the method comprising: forming the anchor bolt using a cross wedge rolling step.

32. A method for installing an expansion anchor as recited in claim 17, the method comprising: inserting the expansion anchor into a hole to position the bulged zone in an area of the hole in which a minimum diameter of the hole is smaller than a maximum diameter of the anchor bolt in the bulged zone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The invention is explained in greater detail below with reference to preferred exemplary embodiments, which are depicted schematically in the accompanying drawings, wherein individual features of the exemplary embodiments presented below can be implemented either individually or in any combination within the scope of the present invention.

[0048] FIG. 1: is a perspective view of an embodiment of an inventive expansion anchor;

[0049] FIG. 2: is a perspective view of the anchor bolt only of the expansion anchor of FIG. 1;

[0050] FIG. 3: is a side view of the anchor bolt only of the expansion anchor of FIG. 1;

[0051] FIG. 4: is a cross-section, 4-4, according to FIG. 3, of the anchor bolt only of the expansion anchor of FIG. 1;

[0052] FIG. 5: is a cross-section, 5-5, according to FIG. 3, of the anchor bolt only of the expansion anchor of FIG. 1; and

[0053] FIG. 6: shows the anchor of FIG. 1, located in a hole in a substrate, in longitudinal sectional view.

DETAILED DESCRIPTION

[0054] The figures show an embodiment of an inventive expansion anchor. The shown expansion anchor is of the stud type and has an elongate anchor bolt 10 defining a longitudinal axis 99 (see, e.g., FIG. 3), and an expansion shell 30, arranged adjacent to the anchor bolt 10 in a front or tip region of the anchor bolt 10. In the present embodiment, the expansion shell 30 is an expansion sleeve, which surrounds the anchor bolt 10.

[0055] The anchor bolt 10 as shown, e,g, in FIGS. 2 and 3, has, in its front region or tip region, a wedge zone 12 designed for radially expanding the expansion shell 30 when the wedge zone 12 is drawn into the expansion shell 30 in the rearwards direction, i.e. when the expansion shell 30 is moved forwards relative to the wedge zone 12 onto the wedge zone 12. For this purpose, the lateral surface of the anchor bolt 10 converges in the wedge zone 12 towards the rear of the anchor bolt 10, i.e. it converges towards the expansion shell 30, at least before the anchor is installed. Focus of convergence is preferably on the longitudinal axis 99.

[0056] In the present example, the anchor bolt 10 also has a transition zone 42, which is located forwards of and adjacent to the wedge zone 12, and a tip zone 41, which is located forwards of and adjacent to the transition zone 42. In the transition zone 42, the rearward convergence is smaller as compared to the wedge zone 12 or the rearward convergence is even zero, but preferably not reverse, i.e. it is not a forward convergence. In the present example, convergence is absent, i.e. zero, in the transition zone 42. In the tip zone 41, the lateral surface of the anchor bolt 10 converges towards the front end of the anchor.

[0057] The anchor bolt 10 has a neck zone 13, which is located adjacent to and rearwards of the wedge zone 12. The expansion shell 30 at least partly surrounds this neck zone 13, at least before installation the anchor.

[0058] Located at the rearward end of the neck zone 13, the anchor bolt 10 has an abutment zone 14, in which the anchor bolt 10 comprises an abutment ring, radially protruding on the anchor bolt 10 and forming a ring-shape shoulder facing forwards for axially engaging the expansion shell 30 and for advancing the expansion shell 30 forwards.

[0059] In the present case, the wedge zone 12 and the neck zone 13 are, by way of example, integral with the rest of the anchor bolt 10. However, a multi-piece design of the anchor bolt 10 is also possible.

[0060] In a rear region of the anchor bolt 10, the anchor bolt 10 has a rear zone 17, which is characterized in that the anchor bolt 10 is provided with an outer thread in this rear zone 17. The outer thread provides a load-introducing structure for introducing rearwardly-directed load into the anchor bolt 10.

[0061] Axially between the rear zone 17 and the abutment zone 14, the anchor bolt 10 has an intermediate zone 15, in which the maximum diameter d of the anchor bolt 10 is smaller when compared to the rear zone 17 and/or to the abutment zone 14. The rear zone 17 is adjacent to the abutment zone 14 and could be adjacent to the rear zone 17. However, in the present case, the anchor bolt 10 also has a bulged zone 16, located axially between the intermediate zone 15 and the rear zone 17. The bulged zone 16 is adjacent to the intermediate zone 15 and adjacent to the rear zone 17. The neck zone 13 and the intermediate zone 15 have the same length. The distance of the wedge zone 12 to the abutment zone 14 and the distance of the bulged zone 16 to the abutment zone 14 are the same.

[0062] As shown in FIG. 6, the anchor bolt 10 has a radius r measured from the longitudinal axis 99 and diameter d. The bulged zone 16 protrudes radially on the anchor bolt 10. In the bulged zone 16, the anchor bolt 10 has a larger maximum radius, measured from the longitudinal axis 99, than in the intermediate zone 15 and in the rear zone 17. Preferably, in the bulged zone 16, the anchor bolt 10 also has a larger maximum diameter than in the intermediate zone 15 and in the rear zone 17. Thus, the bulged zone 16 forms a ring surrounding the longitudinal axis 99, which juts out with respect to its surroundings. The bulged zone 16 can abut on the hole wall when the anchor is radially loaded, allowing force transfer to the substrate and thereby protecting the expansion mechanism provided by the wedge zone 12 and the expansion shell 30.

[0063] As can be seen particularly well in FIG. 6, in the bulged zone 16, the anchor bolt 10 preferably has a larger maximum radius, and preferably also a larger maximum diameter, than in the abutment zone 14, and more preferably also a larger maximum radius, and preferably also a larger maximum diameter, than in the wedge zone 12. This leads to particularly good support high up in the hole in the substrate 6. The radius r is measured originating from the longitudinal axis 99 and the diameter d through the longitudinal axis 99 in each case.

[0064] The expansion shell 30 is provided with a plurality of slits 36, which originate from the front end of the expansion shell 30 and extend towards the rear end of the expansion shell 30. The slits 36 can facilitate radial expansion of the expansion shell 30.

[0065] In the neck zone 13, the anchor bolt 10 is provided, on its lateral surface, with a plurality of neck zone grooves 23. These neck zone grooves 23 are radially accessible from the outside of the anchor bolt 10. The neck zone grooves 23 are longitudinal grooves each, extending parallel to the longitudinal axis 99. In cross-section, the neck zone 13 deviates from a circle at the neck zone grooves 23. The neck zone grooves 23 extend along the entire neck zone 13, into the wedge zone 12. The neck zone 13 is threadless.

[0066] Each of the neck zone grooves 23 has a first neck zone groove side wall and a second neck zone groove side wall, wherein these two neck zone groove side walls limit the respective neck zone groove 23 in the circumferential direction. Thus, the neck zone groove side walls are circumferential side walls. In FIG. 2, the first neck zone groove side wall of an exemplary neck zone groove 23 has been marked with reference numeral 71 and the second neck zone groove side wall of this exemplary neck zone groove 23 has been marked with reference numeral 72.

[0067] The intermediate zone 15 is threadless. However, in the intermediate zone 15, the anchor bolt 10 is provided, on its lateral surface, with a plurality of intermediate zone grooves 25. These intermediate zone grooves 25 are radially accessible from the outside of the anchor bolt 10. The intermediate zone grooves 25 are longitudinal grooves each, extending parallel to the longitudinal axis 99. In cross-section, the intermediate zone 15 deviates from a circle at the intermediate zone grooves 25. The intermediate zone grooves 25 extend along the entire intermediate zone 15, into the bulged zone 16.

[0068] Each of the intermediate zone grooves 25 has a first intermediate zone groove side wall and a second intermediate zone groove side wall, wherein these two intermediate zone groove side walls limit the respective intermediate zone groove 25 in the circumferential direction. Thus, the intermediate zone groove side walls are circumferential side walls. In FIG. 2, the first intermediate zone groove side wall of an exemplary intermediate zone groove 25 has been marked with reference numeral 73 and the second intermediate zone groove side wall of this exemplary intermediate zone groove 25 has been marked with reference numeral 74.

[0069] Each of the intermediate zone grooves 25 overlaps one of the neck zone grooves 23 in the radial and circumferential directions. The intermediate zone grooves 25 and the neck zone grooves 23 are aligned, so that the intermediate zone grooves 25 form extensions of the neck zone grooves 23.

[0070] The expansion shell 30 engages in the neck zone grooves 23. For this purpose, the expansion shell has axially extending thickenings, which project into the neck zone grooves 23. This engagement can form a rotational lock, which prevents rotating of the expansion shell 30 around the anchor bolt 10.

[0071] The bulged zone 16 is provided with bulged zone channels 26, extending longitudinally through the bulged zone 16. The bulged zone channels 26 are surface grooves in the present case. The bulged zone channels 26 allow passage of a fluid medium, for example of a hardenable mortar. Moreover, the bulged zone channels 26 can take up material of the anchor bolt 10, facilitating deformation of the bulged zone 16 and therefore facilitating insertion of the anchor bolt 10 into a hole.

[0072] The wedge zone 12, the transition zone 42 and the tip zone 41 are provided with wedge zone channels 22 (see, e.g., FIGS. 3 and 4), each extending longitudinally through the wedge zone 12, the transition zone 42 and the tip zone 41. These wedge zone channels 22 can facilitate manufacturing and/or improve installation and anchorage. The wedge zone channels 22 are aligned with the bulged zone channels 26. Both the wedge zone channels 22 and the bulged zone channels 26 are offset, in the circumferential direction, from both the neck zone grooves 23 and from the intermediate zone grooves 25, as can be seen particularly well in FIGS. 4 and 5.

[0073] In its front region, the anchor bolt 10 has a relatively high mirror symmetry: the intermediate zone 15 is, within usual manufacturing tolerances, mirror symmetric to the neck zone 13, and the bulged zone 16 has some symmetric resemblance to the wedge zone 12, all with respect to a mirror plane running perpendicular to the longitudinal axis 99 through the abutment zone 14. Moreover, the wedge zone 12 is provided with longitudinally running surface grooves (namely the wedge zone channels 22), and so is the bulged zone 16 (namely the bulged zone channels 26), and at least parts of the bulged zone 16 have the same axial distance from the abutment zone 14 as at least parts of the wedge zone 12. This high symmetry can give a particular symmetric distribution of forces during a cross wedge rolling manufacturing process.

[0074] When the anchor is installed, it is introduced, front end first, into a hole in a substrate 6. Subsequently, the anchor bolt 10, together with its wedge zone 12, is pulled back rearwardly, in particular by tightening a not-shown nut provided on the thread of the rear zone 17 of the anchor bolt 10. As a consequence, the wedge zone 12 is drawn into the front-end region of the expansion shell 30 and the expansion shell 30 is radially displaced, thereby anchoring the expansion anchor. The resulting configuration is shown in FIG. 6. The bulged zone 16 is so dimensioned that it creates an interference fit with the substrate 6 when located in the hole.