Expanding anchor

Abstract

The present disclosure provides an expansion anchor having an anchor bolt, an expansion sleeve surrounding the anchor bolt, and a wedge located in a front region of the anchor bolt for wedging the expansion sleeve, wherein the expansion sleeve has a front end face facing the wedge, wherein at least one expansion slit is provided within the expansion sleeve, wherein the expansion slit starts at the front end face of the expansion sleeve, wherein the expansion slit has a stem and a head adjoining the stem, wherein the head is wider than the stem, and wherein the stem is located between the head and the front end face, characterized in that the head is positioned eccentrically relative to the stem.

Description

TECHNICAL FIELD

[0001] The invention relates to an expansion anchor. Such an anchor is provided with an anchor bolt, an expansion sleeve surrounding the anchor bolt and a wedge located in a front region of the anchor bolt for wedging the expansion sleeve, wherein the expansion sleeve has a front end face facing the wedge, wherein at least one expansion slit is provided within the expansion sleeve, wherein the expansion slit starts at the front end face of the expansion sleeve, wherein the expansion slit has a stem and a head adjoining the stem, wherein the head is wider than the stem, and wherein the stem is located between the head and the front end face of the expansion sleeve. BACKGROUND

[0002] EP 2848825 A1 discloses an expansion anchor, wherein the expansion sleeve has at least one web on its inner side, which web engages with a groove in the anchor bolt. Thus, the expansion sleeve has a non-uniform wall thickness. During installation, the web is displaced radially outwardly by the wedge of the anchor bolt.

[0003] WO 19081300 A1 describes an expansion anchor having an expansion sleeve abutment wall provided on the expansion body. The expansion sleeve abutment wall can engage with the expansion sleeve to provide interlocking when the anchoring process reaches the push-in state. The expansion sleeve abutment wall can be provided at the end of a recess provided in the expansion body. Based thereon, WO 19243084 A1 further teaches to provide said recess with a non-axially symmetric cross section. According to WO 19243084 A1, the expansion sleeve likewise has a non-uniform wall thickness.

[0004] WO 15067578 A1 describes an expansion anchor having a recess provided in the wedge, wherein the recess reduces the contact surface between the expansion sleeve and the wedge.

[0005] EP 2514979 A1 shows an anchor bolt having an eccentric region, which widens the expansion sleeve upon rotation of the anchor bolt.

[0006] EP 2309138 A2 and WO 12126700 A1 describe anchor bolts having a structured wedge. SUMMARY

[0007] It is an object of the present invention to provide an expansion anchor which is particularly easy to manufacture and / or has particularly high performance.

[0008] This object is achieved by an expansion anchor.

[0009] The anchor of the present invention is characterized in that the head is located eccentrically with respect to the stem.

[0010] Thus, the head is offset relative to the stem, in particular in circumferential direction, and in particular by a distance d o Thus, the stem center line defined by the stem does not pass through the center of mass of the head. In particular, the combination of stem and head can have a non-axially symmetric profile and / or a profile of the shape of a musical note.

[0011] The expansion slit defines forwardly facing expansion fingers of the expansion sleeve, which are radially wedged outwards by the wedge during installation of the anchor. Due to the head being wider than the stem in circumferential direction, the head forms a constriction, i.e. a weakening, in the adjacent expansion fingers, thereby facilitating the wedging out of these expansion fingers. On the other hand, when the expansion sleeve is manufactured in a bending process, the head tends to define the bending point due to its rearward arrangement and due to its width. By arranging the head eccentrically relative to the stem, the bending point associated with the manufacturing process can be repositioned in circumferential direction, which can be advantageous in this respect. Nonetheless, the head can still serve to facilitate the outward expansion of the adjacent expansion fingers. Thus, an anchor of particularly good performance can be obtained in particular with little effort.

[0012] The anchor bolt is an elongated body. The wedge and the anchor bolt are in particular connected to transfer the tensile force. In particular, if the expansion anchor is a so-called sleeve-type expansion anchor, the wedge body can be threadedly connected with the anchor bolt, for example. In particular, if the expansion anchor is a so-called stud-type expansion anchor, the wedge can also be fixed tightly to the anchor bolt. In the case of a stud-type expansion anchor, it is particularly preferred that the wedge and the anchor bolt are integral, i.e. they form one piece. If the expansion anchor is a so-called stud-type expansion anchor, the anchor bolt is preferably provided with a forwardly facing shoulder for the expansion sleeve to abut against and for the expansion sleeve to be advanced into the borehole. The wedge is part of the expansion anchor.

[0013] The expansion sleeve surrounds the anchor bolt, in particular the longitudinal axis of the anchor bolt. In particular, the expansion sleeve can be a single piece.

[0014] Preferably, the anchor bolt, the expansion sleeve and / or the wedge are each steel components. For example, these steel parts can comprise carbon steel or stainless steel.

[0015] In particular, the anchor bolt can have a tension introduction structure in a rear region of the anchor bolt. The tension introduction structure serves to introduce the tensile force into the anchor bolt. The tension introduction structure can be a thread, in particular an external thread, provided on the anchor bolt, for example. The tension introduction structure can also be a head or a bayonet-type lock, for example, which forms the largest cross section.

[0016] The wedge region of the wedge is intended to be used for expanding the expansion sleeve, in particular radially with respect to the longitudinal axis, when the wedge is moved back with respect to the expansion sleeve. The wedge converges on its lateral surface towards the rear of the anchor and / or towards the tension introduction structure, wherein the focus of the convergence can preferably be the longitudinal axis. This in particular means that the radial distance of the lateral surface of the wedge from the longitudinal axis becomes smaller towards the rear of the wedge. In particular, the wedge region forms a wedge for the expansion sleeve.

[0017] The at least one expansion slit cuts the expansion sleeve and subdivides the expansion sleeve into expansion fingers. In particular, the at least one expansion slit runs through the wall thickness of the expansion sleeve, i.e. the expansion slit forms a radial perforation of the expansion sleeve. The expansion slit starts at the front end face and extends back into the expansion sleeve. Preferably, the expansion slit extends approximately parallel to the longitudinal axis, but it can also be angled with respect to the longitudinal axis. The stem of the expansion slit is located between the head of the expansion slit and the front end face of the expansion slit, i.e. the head is located rearward of the stem. In particular, the head can define the rear end of the expansion slit. The head is wider than the stem, in particular in the circumferential direction. In some embodiments, the front end face of the expansion sleeve can be provided with a triangular structure that converges into the slit, for example to provide a rounding. The triangular structure can be wider than the head, at least in certain regions of the triangular structure.

[0018] Preferably, the expansion sleeve has a plurality of expansion slits starting at the front end face of the expansion sleeve. If a plurality of expansion slits is provided, at least some of these expansion slits, preferably all of these expansion slits, are preferably configured like the at least one expansion slit described herein.

[0019] The expansion sleeve can also have one or more additional slits. In contrast to the expansion slits, these additional slits can not have a head.

[0020] In the case where the term "longitudinal axis" is used, this term is in particular to refer to the longitudinal axis of the anchor, which is also typically the longitudinal axis of the anchor. According to the usual definition, the "longitudinal axis" can be an axis that extends in the longitudinal direction, i.e. in the direction of the length of the anchor. In the case where the terms "radially", "axially" or "circumferentially" are used, these terms are in particular to be understood with respect to the longitudinal axis of the anchor.

[0021] Preferably, the head has an elongated profile. It is particularly preferred that the elongation axis of the elongated profile extends approximately perpendicular to the stem. Thus, the head has a non-circular elongated profile, wherein preferably the elongation axis of the elongated profile extends approximately perpendicular to the stem. Providing a head with an elongated profile can allow to displace a bending point related to the manufacturing process of the expansion sleeve, which can provide a smoother curvature and / or further facilitate the manufacturing in a particularly easy manner.

[0022] In particular, the present application can be used for expansion anchors, wherein the expansion sleeve has a non-constant wall thickness, i.e. wherein the wall of the expansion sleeve varies depending on the position on the expansion sleeve. The non-constant wall thickness can be provided in order to improve anchoring performance, as further detailed in e.g. EP 2848825 A1 (which application is included herein by reference).

[0023] Advantageously, the head is eccentrically entered into the region of the expansion sleeve with reduced wall thickness with respect to the stem. Thus, by the eccentricity, the head reaches into the region of the expansion sleeve with reduced wall thickness. In other words, the offset reduces the average wall thickness along the profile of the head, i.e. the average wall thickness along the profile of the head is smaller compared to an imaginary state in which the head is centered with respect to the stem. This can effectively resist a breakage of the expansion sleeve when the expansion sleeve is formed by bending a substantially flat blank, and / or improve the roundness of the expansion sleeve after such a bending operation. Furthermore, the radial expansion resistance of the expansion sleeve can be reduced, whereby the initial anchoring can be improved. Furthermore, a separation of the expansion fingers during pull-out can be effectively resisted.

[0024] The present application is explained in greater detail below with reference to preferred exemplary embodiments which are depicted schematically in the drawings. Individual features of the exemplary embodiments presented below can be realized within the scope of the present application, either alone or in arbitrary combination. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a side view of the anchor of

[0026] Figure 2 is a perspective view of the expansion sleeve of the anchor of Figure 1

[0027] Figure 3 is a side view of the expansion sleeve of the anchor of Figure 1

[0028] is a sectional view A-A of the expansion sleeve of the anchor according to Figure 4 Figure 1 Figure 3 is a sectional view A-A of the expansion sleeve of the anchor according to DETAILED DESCRIPTION

[0029] The drawing shows one embodiment of an expansion anchor of the present application. The expansion anchor comprises an elongated anchor bolt 10 defining a longitudinal axis 99, an expansion sleeve 30 surrounding the anchor bolt 10, and a wedge 12 provided on the anchor bolt 10, i.e. near the front end of the anchor bolt 10. The wedge 12 is designed for radially wedging outwards into the expansion sleeve 30 when the wedge 12 is pulled into the expansion sleeve 30 in a rearward direction, i.e. in a pull-out direction. To this end, the side surface of the wedge 12 is at least partially converging rearward. The longitudinal axis 99 extends through the front end of the anchor bolt 10 and through the rear end of the anchor bolt.​​​

[0030] The anchor 10 has a neck near and behind the wedge 12. The expansion sleeve 30 at least partially surrounds this neck at least before installation of the anchor. At this neck, the diameter of the anchor 10 can be minimal.

[0031] In the present embodiment, the expansion anchor is a stud-type anchor. Thus, the anchor 10 has a forward-facing shoulder 17 at the rear end of the neck for axial engagement with and advancement of the expansion sleeve 30. In this case, the wedge 12 is integral with the rest of the anchor 10, but in alternative embodiments, the anchor 10 can be composed of several separate parts.

[0032] In the rear region of the anchor 10, the anchor 10 is provided with a tension introduction structure 18, here for example an external thread provided on the anchor 10. However, this is merely an example, other structures such as an internal thread, a bayonet mechanism or a head can also be envisaged.

[0033] The expansion sleeve 30 is a C-clip and is provided with a plurality of expansion slits 36', 36'', 36''', 36''''. Each of these expansion slits 36', 36'', 36''', 36'''' starts at the front end face 31 of the expansion sleeve 30 (i.e. at the end face of the expansion sleeve 30 facing the wedge 12) and extends towards the rear end of the expansion sleeve 30 (and thus towards the rear end of the anchor 10). Each of the expansion slits 36', 36'', 36''', 36'''' passes radially through the expansion sleeve 30, i.e. each of the expansion slits 36', 36'', 36''', 36'''' separates the expansion sleeve 30.

[0034] The expansion slit 36' comprises a stem 61' and a head 63' adjoining the stem 61'. The head 63' is arranged rearward of the stem 61'. Thus, the stem 61' is arranged between the head 63' and the front end face 31 of the expansion sleeve 30. The head 63' forms the rear end of the expansion slit 36'. The stem 61' is a narrow, substantially straight groove. The head 63' has a greater width in the circumferential direction (i.e. around the longitudinal axis 99) than the stem 61'. Due to its width, the head 63' forms a local weakening of the adjacent expansion sleeve 30, thus facilitating the expansion of the expansion sleeve 30.

[0035] In the shown embodiment, the stem 61' extends substantially in the axial direction, i.e. substantially parallel to the longitudinal axis 99. However, an angled configuration can also be envisaged.

[0036] The head 63' is non-circular, elongated, for example approximately elliptical in profile, with the elongated direction generally following the circumferential direction of the anchor 10. The head 63' is positioned eccentrically with respect to the stem 61 '. Thus, the centerline of the stem 61'does not include the center of mass of the head 63'; i.e., the center of mass of the head 63' is at a distance d from the centerline of the stem 61 ' o .

[0037] The expansion sleeve 30 has a non-constant wall thickness, i.e. the wall thickness t depends on the position on the expansion sleeve 30, in particular on the circumferential position. The head 63' is positioned eccentrically with respect to the stem 61'towards a region of the expansion sleeve where the wall thickness is reduced. In other words, the head 63' reaches into a region of smaller wall thickness compared to an imaginary arrangement where the head 63' would be positioned centrally with respect to the stem 61 '.

[0038] The head 63' has a width w measured in the circumferential direction perpendicular to the longitudinal axis 99 h and a length l measured parallel to the longitudinal axis 99 h . Preferably, the ratio of the width w h of the expansion anchor to the nominal diameter d nom is >= 0.25 and / or <= 1.0 and / or the ratio of the length l h of the expansion anchor to the nominal diameter d nom is >= 0.2.

[0039] The expansion slot 36'' also comprises a stem 61'' and a head 63'', wherein these items are arranged and configured similar to the expansion slot 36' such that the above description applies mutatis mutandis. The expansion slot 36''' also comprises a stem 61''' and a head 63''', wherein these items are arranged and configured similar to the expansion slot 36' such that the above description applies mutatis mutandis. The expansion slot 36'''' also comprises a stem 61'''' and a head 63'''', wherein these items are arranged and configured similar to the expansion slot 36' such that the above description applies mutatis mutandis. The expansion slots 36', 36'', 36''' are blind slots, thus they do not reach the rear end of the expansion sleeve 30. Thus, the head 63' defines the rear end of the expansion slot 36', the head 63'' defines the rear end of the expansion slot 36'', and the head 63''' defines the rear end of the expansion slot 36'''. On the other hand, the expansion slot 36'''' is a through slot, which extends all the way through the expansion sleeve 30, i.e. from the front face 31 of the expansion sleeve 30 to the rear end of the expansion sleeve 30. Thus, the expansion slot 36'''' has a tail 64'''' which extends from the head 63'''' to the rear end of the expansion sleeve 30. Thus, the head 63'''' is axially located between the stem 61'''' and the tail 64''''.

[0040] In the present embodiment, the front face 31 of the expansion sleeve 30 comprises a triangular structure which converges into the expansion slots 36', 36'', 36''', 36''''. Figure 3 In the case of the expansion slot 36', the corresponding triangular structure is marked with reference 32' in Fig. 3. The remaining expansion slots 36'', 36''', 36'''' have a similar triangular structure provided at the front face 31. This triangular structure provides a rounding of the front face 31 which can resist wear at the wedge 12.

[0041] In use, the expansion anchor is introduced into a hole of the base plate 6, with the front end first. Subsequently, the wedge 12 is pulled into the front face 31 of the expansion sleeve 30. In the present embodiment, this is achieved by pulling the anchor bolt 10 and the wedge 12 together backwards, in particular by tightening the nut 8 provided on the tension introduction structure 18 of the anchor bolt 10. This loads the expansion sleeve 30 radially outwards, thereby locking the expansion anchor on the base plate.

[0042] The expansion slots 36', 36'', 36''', 36'''' and the associated triangular structures define expansion fingers 39', 39'', 39''', 39'''' on the expansion sleeve 30. The configuration of the described expansion slots 36', 36'', 36''', 36'''' and in particular the described offset allow for relatively long expansion fingers 39', 39'', 39''', 39''''. f The length l s and / or the nominal diameter d nom of the expansion anchor

[0043] l f / l s > 0.8

[0044] l f / d nom > 1.3.

Claims

1. An expansion anchor, having - an anchor bolt (10), - an expansion sleeve (30) surrounding the anchor bolt (10), and - a wedge (12) in a front region of the anchor bolt (10) for wedging the expansion sleeve (30), wherein the expansion sleeve (30) has a front end face (31) facing the wedge (12), - wherein at least one expansion slit (36) is provided within the expansion sleeve (30), wherein the expansion slit (36) starts at the front end face (31) of the expansion sleeve (30), wherein the expansion slit (36) has a stem (61) and a head (63) adjoining the stem (61), wherein the head (63) is wider than the stem (61), and wherein the stem (61) is located between the head (63) and the front end face (31) of the expansion sleeve (30), characterized in that - the head (63) is positioned eccentrically relative to the stem (61).

2. The expansion anchor according to claim 1, characterized in that the head (63) has an elongated profile, wherein an elongation axis of the elongated profile extends approximately perpendicular to the stem (61).

3. The expansion anchor according to one of the preceding claims, characterized in that the expansion sleeve (30) has a non-constant wall thickness (t), wherein the head (63) is eccentric relative to the stem (61) into an expansion sleeve region in which the wall thickness (t) decreases. ​ ​ ​

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