Expansion anchor with sleeve abutment walls

Abstract

An expansion anchor having an anchor bolt, an expansion sleeve surrounding the anchor bolt, and an expansion body located in a front region of the anchor bolt, wherein the expansion body has a converging zone for expanding the expansion sleeve. The expansion body has at least one expansion sleeve abutment wall facing the expansion sleeve. The invention also relates to a method for using such an expansion anchor.

Claims

1-22. (canceled)

23. An expansion anchor comprising: an anchor bolt; an expansion sleeve surrounding the anchor bolt; and an expansion body located in a front region of the anchor bolt, the expansion body having a converging zone for expanding the expansion sleeve, the expansion body having at least one expansion sleeve abutment wall facing the expansion sleeve.

24. The expansion anchor as recited in claim 23 wherein the at least one expansion sleeve abutment wall is configured to surmountably obstruct the expansion sleeve.

25. The expansion anchor as recited in claim 23 wherein the least one expansion sleeve abutment wall tapers towards a rear of the anchor bolt.

26. The expansion anchor as recited in claim 23 wherein a maximum slope of the at least one expansion sleeve abutment wall, measured with respect to a longitudinal axis of the anchor bolt, is greater than 30 and smaller than 80.

27. The expansion anchor as recited in claim 23 wherein the at least one expansion sleeve abutment wall has a maximum radial height of at least 0.3 mm.

28. The expansion anchor as recited in claim 23 wherein the at least one expansion sleeve abutment wall is located at a distance of at least 0.5*L1 from a rear end of the converging zone, wherein L1 is the length of the converging zone (23).

29. The expansion anchor as recited in claim 28 wherein the distance is at least 0.8*L1.

30. The expansion anchor as recited in claim 23 wherein the expansion body has, located in front of the converging zone, a transition zone, the at least one expansion sleeve abutment wall being located within the transition zone.

31. The expansion anchor as recited in claim 23 wherein the expansion body is provided with at least one abutment wall recess, the at least one abutment wall recess being limited by the at least one expansion sleeve abutment wall.

32. The expansion anchor as recited in claim 31 wherein the abutment wall recess is configured to receive a section of the expansion sleeve.

33. The expansion anchor as recited in claim 31 wherein the expansion sleeve has at least one slit, originating from a front end of the expansion sleeve, the at least one slit being located in a position where the at least one slit at least partly overlaps the at least one abutment wall recess or is configured to be bringable into a partly overlapping position by rotating the expansion sleeve around the anchor bolt.

34. The expansion anchor as recited in claim 31 wherein the expansion body has an arcuate cross-section adjacent to the at least one abutment wall recess.

35. The expansion anchor as recited in claim 23 wherein the at least one expansion sleeve abutment wall has a maximum angular width, measured at a longitudinal axis of the anchor bolt in a plane perpendicular to the longitudinal axis of the anchor bolt, that is greater than 50 and smaller than 90.

36. The expansion anchor as recited in claim 35 wherein the maximum angular width is greater than 60 and smaller than 80.

37. The expansion anchor as recited in claim 23 wherein at least one expansion sleeve abutment wall includes a plurality of expansion sleeve abutment walls.

38. The expansion anchor as recited in claim 23 wherein the expansion sleeve abutment walls are arranged abreast.

39. The expansion anchor as recited in claim 38 wherein that the expansion sleeve abutment walls span, in total, a minimum 120 and maximum 280 of the expansion body.

40. The expansion anchor as recited in claim 39 wherein that the expansion sleeve abutment walls span, in total, minimum 140 and a maximum 250 of the expansion body.

41. The expansion anchor as recited in claim 38 wherein the expansion body has maximum of 8 expansion sleeve abutment walls.

42. The expansion anchor as recited in claim 38 wherein the expansion body has maximum of 6 expansion sleeve abutment walls.

43. The expansion anchor as recited in claim 38 wherein the expansion body has maximum of 4 expansion sleeve abutment walls.

44. The expansion anchor as recited in claim 31 wherein at least one abutment wall includes a plurality of abutment wall recesses, wherein each abutment wall recess is limited by one of the at least one expansion sleeve abutment wall, wherein the plurality of abutment wall recesses cover 20% to 70% of a lateral surface of the expansion body.

45. The expansion anchor as recited in claim 44 wherein the plurality of abutment wall recesses cover 40% to 45% of the lateral surface of the expansion body.

46. The expansion anchor as recited in claim 23 wherein expansion sleeve abutment walls of the at least one expansion sleeve abutment walls are arranged in a symmetric manner, the expansion sleeve abutment walls are arranged equidistantly around the expansion body, or the expansion sleeve abutment walls all have equal widths.

47. The expansion anchor as recited in claim 23 wherein a maximum thickness of the expansion sleeve is between 0.75 mm and 3.5 mm, or the converging zone has an apex angle between 10 and 40.

48. A method for using the expansion anchor as recited in claim 23, the method comprising: moving the expansion sleeve forward relative to the expansion body so that the expansion sleeve hits the at least one expansion sleeve abutment wall.

49. The method as recited in claim 48 wherein moving further includes overcoming the at least one expansion sleeve abutment wall subsequent to the hitting.

50. The method as recited in claim 48 wherein as the expansion sleeve is moved forward relative to the expansion body, a region of the expansion sleeve is inserted into at least one abutment wall recess.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The invention is explained in greater detail below with reference to preferred exemplary embodiments, which are depicted schematically in the accompanying drawing, where individual features of the exemplary embodiments presented below can be implemented either individually or in any combination within the scope of the present invention.

[0056] FIG. 1: a side view of an inventive expansion anchor,

[0057] FIG. 2: a cut-out of the front region of the anchor of FIG. 1 in sectional view A-A according to FIG. 1;

[0058] FIG. 3: a cross-sectional view B-B according to FIG. 1 of the anchor of FIGS. 1 and 2;

[0059] FIGS. 4 to 7: consecutive steps of a method for using the anchor of FIGS. 1 to 3 in a substrate, wherein, for the sake of clarity, the substrate is only shown in FIG. 4.

[0060] FIG. 4 shows the anchor in side view,

[0061] FIG. 5 in cut-out detail side view and

[0062] FIGS. 6 and 7 in cut-out sectional view, similar to FIG. 2.

DETAILED DESCRIPTION

[0063] The figures show an embodiment of an inventive expansion anchor. The anchor comprises an elongate anchor bolt 10 defining a longitudinal axis 99, an expansion sleeve 30, which surrounds the anchor bolt 10, and an expansion body 12 for the expansion sleeve 30 provided on the anchor bolt 10, namely in the vicinity of the front end of the anchor bolt 10.

[0064] As shown in particular in FIG. 2, the expansion body 12 has a converging zone 23 designed for radially expanding the expansion sleeve 30 when the expansion body 12 is drawn into the expansion sleeve 30 in the rearwards direction, i.e. when the expansion sleeve 30 is moved forwards relative to the expansion body 12 onto the expansion body 12. For this purpose, the lateral surface of the expansion body 12 converges towards the rear of the anchor, i.e. it converges towards the expansion sleeve 30, at least before the anchor is installed. In the present example, the expansion body 12 lateral surface is conical in the converging zone 23, with a focus of convergence on the longitudinal axis 99 and with apex angle shown in FIG. 1. However, this is merely an example and other converging designs are also possible.

[0065] In the present example, the expansion body 12 also has a transition zone 22, which is located forwards of and adjacent to the converging zone 23, and a tip zone 21, which is located forwards of and adjacent to the transition zone 22. In the transition zone 22, the rearward convergence is smaller as compared to the converging zone 23 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 converging zone 23 and the expansion body 12 has a cylindrical lateral surface in the converging zone 23, in particular cylindrical with a circular base. In the tip zone 21, the lateral surface of the expansion body 12 converges towards the front end of the anchor.

[0066] The anchor bolt 10 has a neck 25, which is located adjacent to and rearwards of the expansion body 12. The expansion sleeve 30 at least partly surrounds this neck 25, at least before installation the anchor. At the neck 25, the diameter of the anchor bolt 10 can be minimal.

[0067] In the present embodiment, the anchor is of the stud type. The bolt 10 has, at the rearward end of the neck 25, a shoulder 17 facing forwards for axially engaging the expansion sleeve 30 and for advancing the expansion sleeve 30 forwards. In the present case, the expansion body 12 is, by way of example, integral with the anchor bolt 10.

[0068] In a rear region of the anchor bolt 10, the anchor bolt 10 is provided with a tension-introducing structure 18, here in the form of an outer thread provided on the anchor bolt 10.

[0069] The expansion sleeve 30 is provided with a plurality of slits 36, 36, which originate from the front end of the expansion sleeve 30 and extend towards the rear end of the expansion sleeve 30. The slits 36, 36 facilitate radial expansion of the expansion sleeve 30. The expansion sleeve 30 has a maximum radial thickness t.sub.30 shown in FIG. 2.

[0070] On the lateral surface of the expansion body 12 is provided a plurality of abutment wall recesses 66, 66, 66 (exemplarily three in the present case, but a different number can be also provided). These abutment wall recesses 66, 66, 66 are radially accessible from the outside of the expansion body 12. By way of example, they each have a roughly rectangular contour when seen in side view. Other contours are possible, however.

[0071] Each of the abutment wall recesses 66 is terminated at its front end by an expansion sleeve abutment wall 60. As there are three abutment wall recesses 66, 66, 66 in the present example, there are also three expansion sleeve abutment walls 60, 60, 60. Each of these expansion sleeve abutment walls 60, 60, 60 faces the expansion sleeve 30, i.e. faces rearwardly, and forms a surmountable axial stop for the front end, i.e. for the tip, of the expansion sleeve 30, as will be described in more detail below.

[0072] As shown in FIG. 2 and, by way of example, at expansion sleeve abutment wall 60, each of the expansion sleeve abutment walls 60, 60, 60 has a radial height h.sub.60 and a maximum slope .sub.max, measured longitudinally with respect to the longitudinal axis 99. As shown in FIG. 3 and, by way of example, at expansion sleeve abutment wall 60, each of the expansion sleeve abutment walls 60, 60, 60 has a maximum angular width .sub.max, in cross section and around the longitudinal axis 99. In total, all expansion sleeve abutment walls 60, 60, 60 span a total angle .sub.total around the longitudinal axis 99. The expansion sleeve abutment walls 60, 60, 60 are abreast, located at the same position along the longitudinal axis 99, and do not overlap in the circumferential direction. Therefore, .sub.total is here the sum of the maximum angular widths .sub.max of all expansion sleeve abutment walls 60, 60, 60, i.e. .sub.total .sub.max.

[0073] The expansion sleeve abutment walls 60, 60, 60 are all located in the transition zone 22. In particular, as shown in FIG. 2 and, by way of example, at expansion sleeve abutment wall 60, each of the expansion sleeve abutment walls 60, 60, 60 is located at a distance d.sub.60 from the axial rear end of the expansion body 12, i.e. from the rear end of the converging zone 23, which distance d.sub.60 is greater than the axial length L1 of the converging zone 23.

[0074] A method for using the anchor is illustrated in FIGS. 4 to 7.

[0075] In a first step of the method, shown in FIG. 4, the anchor is introduced, front end first, into a hole in a substrate 6.

[0076] Subsequently, the expansion body 12 is drawn into the front-end region of the expansion sleeve 30, i.e. the expansion sleeve 30 is pushed forwards relatively to the expansion body 12 and over the expansion body 12. In the present embodiment, this is achieved by pulling the anchor bolt 10 together with the expansion body 12 rearwardly, in particular by tightening a nut 8 provided on the tension-introducing structure 18 of the anchor bolt 10. Since the substrate 6 exerts radial pressure on the expansion sleeve 30, the expansion sleeve 30 slightly bend radially into the abutment wall recesses 66, 66, 66m when the expansion body 12 is drawn into the front-end region of the expansion sleeve 30. FIGS. 5 to 7 show consecutive positions of the expansion sleeve 30 relative to the expansion body 12 during drawing-in of the expansion body 12.

[0077] At some stage, as shown in FIG. 6, the expansion sleeve 30 axially hits, with its tip in the bent-in regions, the expansion sleeve abutment walls 60, 60, 60. This results in a form-fit type axial interlock of the expansion sleeve 30 with the expansion body 12 at the expansion sleeve abutment walls 60, 60, 60. This interlock leads to a temporary change of the expansion mechanism and can result in increased pull-out resistance without excessive stress of the substrate 6.

[0078] The interface between the expansion sleeve abutment walls 60, 60, 60 and the expansion sleeve 30 is so designed that the interlock can be overcome on purpose at high tensile loads, as shown in FIG. 7, leading to a return of the expansion mechanism, and potentially to particularly good resistance at high loads.

[0079] Tightening of the nut 8 might induce rotation of the expansion body 12 relative to the expansion sleeve 30 at the beginning of installation. But this rotation is soon stopped, namely when the edge of a slit engages a side wall of one of the abutment wall recesses 66, 66, 66m, e.g. when the edge of slit 36 engages side wall 69 of recess 66, as shown in FIG. 5.