HK1175224B - Fastening element - Google Patents

Description

Fastening piece

Technical Field

The present invention relates to a fastener for anchoring in an undercut borehole.

Background

Such a fastener for anchoring in an undercut borehole is known from the publication DE4011229a 1. The fastening element described in this document is particularly suitable for fixing plate-like elements, such as natural stone slabs, to a load-bearing structure. The fastening element is designed as an undercut anchor and has a shaft section and an expansion element. On the rod section, at its insertion-side front end, a conical expansion body is provided, with which an annular or sleeve-shaped expansion element can be expanded. Furthermore, the pole segment has a load means at the rear. The expansion element is formed by a sleeve-shaped metal ring which is designed roof-like in the form of a pitched roof or with a plurality of roof-like curved sections.

Furthermore, an expansion sleeve is arranged on the shank section of the fastening element. If the expansion sleeve is moved axially along the rod section in the direction of the conical expansion body, the expansion sleeve presses the expansion element via the conical expansion body widening in the insertion direction, thereby spreading the ring open so that it at least partially fills the undercut of the undercut borehole. By expanding the expansion body, the fastening element is positively anchored in the borehole. The force is thus transmitted from the plate-like member to the load-bearing structure via the fastener, which is connected to said load-bearing structure via a load means designed as an external thread.

Disclosure of Invention

The invention aims to solve the technical problem of creating a different fastener.

To this end, the invention proposes a fastening element for anchoring in an undercut borehole, having a shaft section and an expansion element, wherein an expansion body for expanding the expansion element and a load-bearing means are provided on the shaft section, wherein the expansion element is designed in the form of a sleeve and has an annular base body on which an expansion flap is provided on the insertion side, the expansion flap having an opening, characterized in that the expansion flap comprises an annular wall, which comprises two webs and an engagement region which is designed essentially in a curved manner, wherein the expansion flap is an element which is radially outwardly expanded when the expansion element is expanded.

The fastener according to the invention for anchoring in an undercut borehole comprises a shank segment and an expansion element. The rod section has an expansion body for expanding the expansion element and a load-bearing means. The expansion body is in particular designed as a conical section which widens in the insertion direction and is arranged on the insertion-side front end of the rod section. The load means is configured, for example, as an external thread. The expansion element is designed in the form of a sleeve, wherein "sleeve-shaped" means that the expansion element substantially surrounds the rod section in the circumferential direction. The expansion element is in particular a sleeve which is closed in the circumferential direction. "loading direction" or "loading side" refers to the direction in which the fastener is placed into the borehole or the side of the borehole into which the fastener is placed.

The fastening element according to the invention is characterized by a special design of the expansion element. The expansion element has an annular base body on which at least one expansion sheet is arranged on the insertion side. The annular base body is arranged in particular at the end of the expansion element that is located at the rear in the insertion direction. The annular base body is preferably closed on its own. "intumescent sheet" means an element that moves radially outward away from an annular base when the intumescent element expands. If the fastening element is located in the undercut borehole and the expansion element is pressed against the expansion body, for example by means of an expansion sleeve, the expansion tabs are moved radially outward by the conically widening expansion body, so that the expansion tabs engage in the undercut and at least partially fill it. The expansion sheet has openings in the form of fully closed perforations, which are arranged in particular such that they reduce the cross section of the expansion sheet in the region where it is connected to the annular base body. The opening is located in the expansion flap, so that the opening moves substantially together with the expansion flap outwards when the latter is spread apart. The opening may in particular be provided in the region of the expansion sheet facing the base body, so that the opening is surrounded by the expansion sheet and the base body. This creates a defined hinge-like curvature of reduced cross section on the expansion flap, on which the expansion flap is easily bendable. The expansion element is thus easily spread apart, so that only a small axial force is required to expand the expansion element into the undercut in the borehole. The fastening element according to the invention can thus also be inserted into very thin components without the expansion of the expansion element damaging the component. The remaining part of the expansion flap can thus be designed solid, so that it fills the undercut as completely and evenly as possible, and the expansion flap itself is so stable therein that large stresses can be transmitted from the component to be fastened into the load-bearing structure by means of the expansion element.

In a preferred embodiment of the fastening element according to the invention, the opening can also be formed such that it penetrates the expansion flap over a substantial part of its surface, so that the expansion flap is formed exclusively by an annular wall which comprises two webs and an engagement region which is located at the front in the insertion direction. The wall is particularly thin, which means that its thickness is small compared to the size of the orifice. In correspondingly larger openings, the material thickness of the wall is small, so that the expansion flap itself can be deformed more easily. The deformability of the annular wall of the expansion sheet reduces the pressure exerted on the borehole wall via the expansion element, in particular when installing the fastening element into a narrow borehole. If the expansion sheet is struck with its free end, the engagement zone, against the wall of the borehole, the wall of the expansion sheet is compressed and deformed, and therefore such a fastener is easier to install than a fastener with an expansion sheet having only small apertures. For the deformability, it is particularly advantageous if the web of the wall connecting the annular base body to the front engagement region of the wall forming the free end is designed to be as slender as possible, so that it can be easily pressed. The length of the tab, determined by its ratio of length to its width, is preferably in the order of 1 to 4, preferably between 1.5 and 3.0.

In a preferred embodiment of the strand of the fastening element, the engagement region connecting the webs to one another at their front ends facing away from the annular base body is formed substantially in a curved shape. "curved" here means, in particular, that the engagement region is a part of a circular ring, i.e. has a surface which is enclosed between two concentric circles. "curved" describes various types of connections which enable the engagement region to be constructed stably by means of a kind of camber. When the arched engagement region comes onto the borehole wall, it is easily deformed, in particular the compressive stresses acting on the engagement region are transferred by the arching action to the web, which is then bent or compressed, so that the pressure exerted on the borehole wall is reduced. In particular, for elongate webs which can be easily bent or compressed under defined stresses, defined deformations of the expansion webs are brought about, so that the components are protected against damage due to the pressure during the application of the fastening means.

In a preferred embodiment of the fastening element according to the invention, the expansion sheet is designed to taper in the direction of its free end. This has the advantage that the expansion sheet is more easily deformed when it hits the borehole wall. When the expansion sheet has, for example, webs, the webs are inclined relative to the borehole wall as a result of the tapering. When the free end of the expansion leaf strikes the borehole wall, then both compressive stresses and bending moments are introduced into the web as a result of the inclination, so that the web is already deformed under low compressive stresses. The stresses that can be generated by the insertion of the fastening element into the borehole wall are thereby reduced, in particular when the expansion sheet is pressed against the borehole bottom. For the deformability, it is particularly advantageous if the openings taper in the direction of the free end of the expansion sheet, in particular if the tapering of the openings corresponds to a tapering of the expansion sheet. In this way, for example, the web can be formed relatively slim.

In a further preferred embodiment of the fastening element according to the invention, the first part of the rotation prevention device is provided on the shaft section, preferably on the expansion body of the shaft section. The first part of the anti-rotation device is designed in particular in the form of a nose ridge. The nose ridge corresponds to the distracted expansion element such that the distracted expansion element cannot rotate relative to the shaft segment and in the axial direction thereof. If the fastener expands in the undercut bore hole, the friction between the bore hole wall and the distracting expansion element prevents rotation of the expansion element relative to the bore hole, and the first part of the anti-rotation device prevents rotation of the rod section relative to the expansion element and thus also relative to the bore hole or the component. It is thus possible, for example, to thread a nut without problems onto a load-bearing component which is designed as an external thread, in order, for example, to fix a fastening element to a load-bearing structure, but without the fastening element rotating with it when the nut is threaded. For example, an annular groove can be formed on the annular base of the fastening element, which groove corresponds to the nose. To increase the friction between the expansion element and the borehole wall, an uneven element may be provided on the expansion element. The uneven elements are, for example, nosed or toothed projections, embossments or groove-like depressions.

The opening of the expansion plate is preferably designed such that it corresponds to the first part of the anti-rotation device and together with this first part forms the anti-rotation device. The first part of the anti-rotation device, for example the nose ridge, is snapped into the opening of the expansion plate, which in this case forms the second part of the anti-rotation device, and the rod section is prevented from rotating in the circumferential direction by the form-fitting connection with the expansion element. In this case, the orifice fulfils a dual function: it achieves a convenient expansion of the expansion element and, if necessary, a deformation of the expansion tabs and, in addition, constitutes a second part of the anti-rotation device. Thus, no additional component is required on the expansion element as a second part of the anti-rotation device.

In a preferred embodiment of the fastening element according to the invention, at least two expansion webs are provided on the base body of the expansion element, which webs are separated from one another in the circumferential direction by a recess. The annular base body is provided with a plurality of expansion disks, so that the geometry of the expansion disks is optimally adapted to the geometry of the undercut of the borehole, and the openings can be designed such that an optimal force transmission is achieved and the expansion elements can be opened with a low axial force. In particular, the bending of the expansion disks required for the annular-shaped borehole can be minimized in the circumferential direction by arranging a plurality of expansion disks, which are distributed over the circumference on the annular base body. If the expansion flap is bent greatly in the circumferential direction, the expansion element is prevented from being easily spread apart, since the expansion flap itself must be bent during expansion.

Preferably, the recess between the at least two expansion tabs is designed such that it corresponds to the first part of the anti-rotation device. Alternatively, the recess in this case forms the second part of the anti-rotation device. Particularly advantageous is the design of the two different parts and optionally the second part of the anti-rotation device. Thus, an aperture may be provided in one or more of the expansion tabs and there may be gaps between the expansion tabs. It is ensured that the first part of the anti-rotation device, after a slight axial rotation of the rod section, is already in contact with the second part of the anti-rotation device, which corresponds to the first part and together with the latter forms the anti-rotation device.

In a further preferred embodiment of the fastening element according to the invention, a stop abutment oriented radially inward is provided on the annular base body of the expansion element. This stop table ensures a defined stop point of the expansion element on the expansion body of the rod section. A stop shoulder corresponding to the stop shoulder is preferably provided on the expansion body. The stop shoulder, together with the stop table, serves as a stop element and limits the relative movement between the expansion element and the expansion body. The stop element thus prevents the expansion element from being pressed too far into the borehole and/or the undercut by axial forces, as a result of which harmful stresses are generated in the region of the borehole wall, which could damage the component.

Preferably, the expansion element of the fastening element according to the invention is a stamped part, in particular a stamped and bent part made of metal. This allows simple and cost-effective production of the expansion element and the fastening element according to the invention.

Drawings

The invention is explained in detail below with the aid of embodiments shown in the drawings.

In the drawings:

FIG. 1 is a view of a fastener according to the present invention in an unexpanded condition;

FIG. 2 is a cross-sectional view of FIG. 1;

FIG. 3 is a perspective view of a fastener according to the present invention in a first, expanded condition;

FIG. 4 is a perspective view of a fastener according to the present invention in a second, expanded condition;

FIG. 5 is a perspective view of the expansion element in an unbent condition as a stamping; and

fig. 6 is a top view of the expansion sheet of the stamping of fig. 5.

Detailed Description

Fig. 1 and 2 show a fastener 1 according to the invention in the unexpanded state and how it can be inserted into an undercut, not shown, borehole in a loading direction E. The installation direction E is parallel to the longitudinal axis a of the fastener 1. The fastener 1 is designed as an undercut anchor for anchoring in an undercut borehole, not shown. The fastener 1 consists of a shank segment 2, an expansion element 3 and an expansion sleeve 4.

The rod section 2 is a taper bolt with a cylindrical section 5 and a conical section 6 connected to the cylindrical section on the insertion side, which conical section forms the front end of the rod section 2. The cylindrical section 5 has a load means 7 in the form of an external thread. The load device 7 is used, for example, for fastening the fastener 1 to a load-bearing structure, which is likewise not shown. The conical section 6 forms an expansion body 8, the diameter of which increases in the insertion direction E. When the expansion element 3 is moved in the insertion direction E towards the conical portion 6, the expansion element 3 is expanded by the expansion body 8. At the transition between the cylindrical section 5 and the conical section 6, the diameter of the conical section 6 is greater than the diameter of the cylindrical section 5, so that a circular ring surface is produced which extends radially beyond the cylindrical section 5 and forms the stop shoulder 9. A nose 10 is provided on the front of the insertion side of the conical section 6 as a first part 11 of the anti-rotation device. The nose ridge 11 projects convexly radially, i.e., as a standard with respect to the longitudinal axis a, beyond the outer lateral surface 12 of the conical portion 6.

The expansion element 3 has an annular base body 13 at its rear end, which surrounds the cylindrical portion 5 of the rod section 2 annularly as a closed sleeve. Four expansion disks 14 are arranged on the base body 13 on the insertion side, which are spaced apart from one another in the circumferential direction by means of recesses 15. A radially inwardly directed stop abutment 16 is formed on the annular base body 13 at its rear end, which stop abutment acts as a stop element together with the stop shoulder 9 of the rod section 2. The expansion flaps 14 each have an aperture 17 in the form of a full-round perforation, which is arranged approximately in the center of each expansion flap 14. Through the opening 17, an annular wall 21 is produced on the expansion flap 14, which has an engagement region 18 for engagement in a not shown undercut of a likewise not shown bore, and two webs 22 which connect the engagement region 18 and the base body 13 to one another with a hinge-like bend 19. Due to the aperture 17, the hinge-like bend 19 is designed to be very easy to bend. A relatively small axial load directed in the insertion direction E is therefore sufficient to cause the expansion flaps 14, together with the openings 17 and the wall 21, to be spread radially outward by the displacement of the expansion elements 3 onto the conical section 6 of the rod section 2. The engagement region 18 is designed to be solid and stable, so that large forces can be transmitted between the borehole wall and the fastener 1 via the engagement region.

The wall 21 is made thinner and thus easily deformable, due to the larger opening 17 comprising the major part of the surface of the expansion sheet 14. The wall 21 has in the form of a ring with webs 22 which are connected to one another by a curved engagement region 18. The tabs 22 are relatively elongate, as best seen in fig. 5 and 6. The slender nature of the tab 22 facilitates its upsettability. The curved design of the engagement region 18 makes it possible to guide the compressive stresses acting on the engagement region 18 when the expansion sheet 14 strikes the borehole wall to the web 22 via the engagement region 18. Compressive stresses act in the webs and, due to the spacing between the engagement region 18 and the webs 22 in the circumferential direction and due to the inclination of the webs 22, bending moments additionally act in the webs 22. Since the engagement region 18 is curved and is formed as a part of a circular ring with an outer radius R, the engagement region 18 acts as a more stable arch. Under the action of the compressive stresses, which are mainly directed to the webs 22, the engagement region 18 can be slightly deformed, and the webs 22 are deformed under a smaller and more precisely defined load due to their elongate configuration. This has the advantage that no large forces acting in the longitudinal direction a, as are formed, for example, when the expansion element 3 expands, are transmitted via the expansion sheet 14 to the bottom of the borehole.

Both the expansion plate 14 and the opening 17 are tapered in the direction of the free end of the expansion plate 14, while the unbent stamped part shown in fig. 5 and 6 is tapered in the radial direction toward the engagement zone 18. The apex angle α of the constriction is 30 °, wherein this angle is generally preferably between 20 ° and 40 °. Here, the width B of the tab 22 remains substantially constant. The length L of the webs 22 can in this case be simply equivalent to the height H of the openings 17 in the radial direction, so that the slenderness of the webs 22, i.e. the ratio of the height H to the width B, is approximately 2.2. This facilitates deformability of the expansion sheet 14. Due to the constriction, the annular engagement region 18 is smaller and more stable, whereas the web 22 is longer. Thus, under the action of the compressive stresses, the arched engagement region 18 directs the compressive stresses directly to the web 22 and generates an additional bending moment in the web 22. The tab 22 can be easily collapsed and defined deformed upon itself. The fastening element 1 according to the invention can therefore also be inserted into very thin components without the components being damaged by the expansion of the expansion element 1.

The expansion sleeve 4 is designed as a hollow cylinder. The cavity designed as a cylindrical bore 20 has an inner diameter which substantially corresponds to the outer diameter of the cylindrical section 5 of the rod section 2. If the expansion sleeve 4 is displaced in the insertion direction E by an axial force, which is applied, for example, by a pressing device, not shown, the expansion sleeve 4 presses the expansion element 3 beyond the expansion body until the stop abutment 16 strikes the stop shoulder 9 of the rod section 2. Even if the axial force is then increased, the expansion element 3 cannot move further in the insertion direction E. It is possible to prevent the expansion element 3 from being excessively expanded. By moving the expansion element 3 onto the expansion body 8, the expansion flaps 14 are spread radially outward and are bent in the region of the hinge-like bend 19. The open state is shown in fig. 3 and 4.

In order to be able to screw a nut, not shown, onto the externally threaded load means 7 in the inserted and expanded fastening element 1 without the fastening element 1 rotating together in the bore hole, the fastening element 1 has an anti-rotation device. The nose ridge 10 on the conical section 6 of the spreading body 8 serves as a first part 11 of the anti-rotation device. Or, as shown in fig. 3, the orifice 17, which constitutes the second part of the anti-rotation device, is designed to correspond to the nose ridge 10, so that the orifice 17 and the nose ridge 10 can be brought into positive engagement with one another in the expanded state; or as shown in fig. 4, the indentation 15 acts as a second part of the anti-rotation means between the two expansion tabs 14. For this purpose, the recess 15 is designed to be able to engage in the same form-fitting manner as the nose ridge 10 in the open state. If the fastening element 1 is expanded in the borehole, the nose ridge 10 latches either in the opening 17 or in the recess 15 after expansion. Depending on the orientation of the expansion element 3 relative to the shaft section 2, a slight rotation of the fastening element 1 in the circumferential direction is necessary until the first part 11 of the anti-rotation device latches into the second part of the anti-rotation device. After latching, the rotation prevention device transmits a torque applied by the nut via the expanded expansion element 3 to the borehole wall, not shown, by means of a friction fit. Thereby preventing the fastener 1 from rotating with it in the bore hole.

The expansion element 3 of the fastener 1 is manufactured as a metal press-bent piece. The rod section 2 is likewise made of metal and can be produced cost-effectively by cold forging. Instead, the expansion sleeve 4 is made of fiber-reinforced plastic and is produced in a die-casting process. The fastening element according to the invention can therefore be produced cost-effectively and can be installed efficiently and simply on the basis of its design.

List of reference numerals

1 fastener

2 pole segment

3 expansion element

4 expansion sleeve

5 cylindrical section

6 conical section

7 load device

8 expansion body

9 stop shoulder

10 nose-shaped bump

11 first part of an anti-rotation device

12 outer surface

13 base body

14 expansion sheet

15 gap

16 stop table

17 orifice

18 region of engagement

19 hinge-like bend

20 drilling

21 wall

22 contact piece

E direction of charging

A longitudinal axis

Outer radius of R-land 18

Width of the B-tag 22

Length of L-shaped tab 22

Height of H orifice 17

Alpha apex angle

Claims (9)

1. A fastener (1) for anchoring in an undercut borehole,

with a rod section (2) and an expansion element (3),

wherein an expansion body (8) for expanding the expansion element (3) and a load device (7) are arranged on the rod section (2),

-wherein the expansion element (3) is designed as a sleeve and has an annular base body (13), on which base body (13) an expansion flap (14) is arranged on the insertion side, which expansion flap (14) has an opening (17), wherein the expansion flap (14) comprises an annular wall (21), which comprises two webs (22) and an engagement region (18), which engagement region (18) is essentially formed in a curved manner, wherein the expansion flap (14) is an element that is spread radially outward when the expansion element (3) expands, characterized in that the expansion flap (14) and the opening (17) both gradually contract in the direction of the free end of the expansion flap (14), the apex angle α at the contraction being between 20 ° and 40 °.

2. Fastener according to claim 1, characterized in that a first part (11) of the anti-rotation means is provided on the shank segment (2).

3. Fastener according to claim 2, characterized in that the opening (17) of the expansion tab (14) is designed to correspond to the first part (11) of the anti-rotation device and together therewith constitute the anti-rotation device.

4. Fastener according to claim 2, characterized in that at least two expansion tabs (14) are provided on the base body (13), which are separated from one another in the circumferential direction by means of the recesses (15).

5. Fastener according to claim 4, characterized in that the recess (15) is configured such that the recess (15) corresponds to the first part (11) of the anti-rotation device and together therewith constitutes the anti-rotation device.

6. Fastener according to one of claims 1 to 5, characterized in that a stop (16) oriented radially inwards is provided on the annular base body (13).

7. Fastener according to claim 6, characterized in that a stop shoulder (9) is formed on the expansion body (8), which together with a stop abutment (16) acts as a stop element for limiting the axial relative movement between the expansion element (3) and the expansion body (8).

8. Fastener according to one of claims 1 to 5, characterized in that the expansion element (3) is a stamping.

9. Fastener according to one of claims 1 to 5, characterized in that the annular base body (13) is closed on its own.