EXPANSIBLE ANCHOR

Abstract

An expansible anchor for anchoring in a drilled hole, having a shank. An expansion sleeve of the expansible anchor can be arranged to be expanded radially by drawing in an expander body. In order to hold the expansion sleeve in place axially during expansion in a drilled hole there is arranged on the shank a resilient ring which has an annular main body having a weakened position, so that to modify its diameter the resilient ring is deformable in the circumferential direction. At least one projection extending radially outwards from the main body is arranged on the resilient ring.

Claims

1. An expansible anchor for anchoring in a drilled hole, having a shank which has an expander body, a neck portion and a load-application means which are arranged one after the other along a longitudinal axis, wherein in an unexpanded state there is arranged on the neck portion an expansion sleeve which is expansible radially by drawing the expander body into the expansion sleeve, wherein on the shank there is arranged a resilient ring for holding the expansible anchor in a drilled hole, which resilient ring has an annular main body having a weakened position, so that to modify its diameter the resilient ring is deformable in a circumferential direction, and wherein the main body has an opening in which the shank is accommodated, and wherein the diameter of the resilient ring in the undeformed state is larger than the diameter of the expansion sleeve in the unexpanded state, wherein the resilient ring has at least one projection extending radially outwards from the main body.

2. The expansible anchor according to claim 1, wherein at least three radially extending projections are arranged on the main body.

3. The expansible anchor according to claim 1, wherein the diameter of the resilient ring in the undeformed state is larger than the maximum diameter of the expander body.

4. The expansible anchor according to claim 1, wherein the diameter of the resilient ring in the undeformed state is a maximum of 1.3 times larger than the maximum diameter of the expander body.

5. The expansible anchor according to claim 1, wherein the resilient ring has at least one receiving space into which the projection is movable on insertion of the expansible anchor into a drilled hole.

6. The expansible anchor according to claim 1, wherein the expansion sleeve has at least two expansion shells which are separated from one another by slots in the circumferential direction but are integrally connected to one another by at least one connecting web.

7. The expansible anchor according to claim 6, wherein the quotient of the cross-sectional area of the connecting web with respect to the maximum diameter of the expander body is a maximum of 0.22 mm.

8. The expansible anchor according to claim 6, wherein the quotient of the cross-sectional area of a connecting web with respect to the axial length of the slot that is adjacent to the connecting web in the axial direction is a maximum of 0.25 mm.

9. The expansible anchor according to claim 6, wherein the axial length of a connecting web is shorter than the radial thickness of the connecting web.

10. The expansible anchor according to claim 6, wherein the axial length of the connecting web is shorter than 2.5 mm.

11. The expansible anchor according to claim 1, wherein the load-application means is an external thread which extends as far as the rear end of the expansible anchor.

Description

[0020] FIG. 1 is a side view of an expansible anchor according to the invention;

[0021] FIG. 2 is a further side view of the expansible anchor according to the invention;

[0022] FIG. 3 shows an axial section through the expansible anchor according to the invention in the plane III-III;

[0023] FIG. 4 shows an axial section through the expansible anchor according to the invention in the plane IV-IV; and

[0024] FIG. 5 shows detail V of FIG. 1.

[0025] The Figures show an expansible anchor 1 according to the invention as a fixing element for anchoring in a drilled hole (not shown) in an unexpanded state outside a drilled hole. The expansible anchor 1 extends along a longitudinal axis L from an end 2, which is at the front in the introduction direction E, to a rear end 3. The expansible anchor 1 is implemented as what is known as a bolt anchor having an elongated, peg-like shank 4 formed in one piece from steel. Starting from the rear end 3, an external thread 5 is provided on the shank 4 as load-application means 6, which external thread extends as far as the rear end 3 of the expansible anchor 1 and on which a washer 7 is arranged and onto which a nut 8 has been screwed. The external thread 5 is adjoined in the introduction direction E by a cylindrical spacer portion 9. In front of the spacer portion 9 in the introduction direction E there is arranged a neck portion 10 which is likewise cylindrical, but has a diameter which is smaller than the diameter of the external thread 5. The neck portion 10 is adjoined in the introduction direction E by an expander body 11, forming the front portion of the shank 4, which has a conical expander portion 12 which widens in diameter in the introduction direction E up to a maximum diameter DK of the expander body 11.

[0026] On the neck portion 10 there is arranged an expansion sleeve 13 consisting of three expansion shells 14 which are separated from one another in the circumferential direction U by slots 15 but are integrally connected to one another by connecting webs 16. The expansion sleeve 13 is expansible radially by drawing the expander body 11 into the expansion sleeve 13 between the expansion shells 14, with the result that the diameter DS of the expansion sleeve 13 is enlarged relative to the unexpanded state shown in the Figures. The expansion shells 14 are curved in the circumferential direction U and together form in cross-section a circular ring interrupted by the slots 15, as can be seen in FIG. 4. The slots 15 are widened at their rear ends by circular widened portions 17 which facilitate expansion of the expansion sleeve 13. The connecting webs 16 close the slots 15 at their rear ends and are arranged at the rear end of the expansion sleeve 13.

[0027] Between the expansion sleeve 13 and the transition from the neck portion 10 to the spacer portion 9, which transition is in the form of an annular step, there is arranged a resilient ring 18 for holding the expansible anchor 1 in a drilled hole. The resilient ring 18 has an annular, slotted main body 19 which is severed in a circumferential direction U at one location by a weakened portion 20, formed as a slot, so that on the main body 19 there are two ends 21, 22 which are directed towards one another and are movable relative to one another, with the result that to modify its diameter DF the resilient ring 18 is deformable in the circumferential direction U. As a result of the weakened position 20, the main body 19 forms an open circular ring having an opening 23 for receiving the neck portion 10 of the shank 4, as can be seen in FIG. 3.

[0028] Projections 24 are arranged on the main body 19 of the resilient ring 18 distributed in the circumferential direction U, which projections have been produced integrally with the resilient ring 18 from plastics, extend radially from the main body 19 and in the undeformed state define the diameter DF of the resilient ring 18. In the undeformed state shown in the Figures, the diameter DF of the resilient ring 18 is larger than the diameter DS of the expansion sleeve 13 in the unexpanded state shown in the Figures. In addition, in the undeformed state the diameter DF of the resilient ring 18 is 1.16 times larger than the maximum diameter DK of the expander body 11. In the circumferential surface of the main body 19 there are arranged rectangular recesses as receiving spaces 25 for the projections 24, there being a receiving space 25 for each projection 24. The projections 24 are arranged in the form of cantilever arms at the front ends of the receiving spaces 25 and extend radially from the main body 19 obliquely towards the rear. Their free ends can be resiliently bent in the axial direction, with the result that the diameter DF of the resilient ring 18 is modified and is able to adapt to the diameter of a drilled hole. On insertion of the expansible anchor 1 into a drilled hole, the projections 24 can, by bending, be moved into the receiving spaces 25 and can to at least some extent be accommodated by the receiving spaces 25. Each of the receiving spaces 25 therefore has a volume substantially corresponding to the volume of the associated projection 24.

[0029] The expansion shells 14 are connected to one another by connecting webs 16. In order that the expansion sleeve 13 can be expanded easily, that is to say in order that as small as possible an axial load can be used to push the expander body 11 between the expansion shells 14 axially, that is to say along the longitudinal axis L and in a direction opposite to the introduction direction E, with the result that the expansion shells 14 are moved radially outwards, the connecting webs 16 have a small cross-sectional area and accordingly a small moment of inertia. The cross-sectional area of a connecting web 16 is calculated from the axial length aV of the connecting web 16 and the radial thickness dV of the connecting web 16. The quotient of the cross-sectional area of the connecting web 16 with respect to the maximum diameter DK of the expander body 11 is 0.16 mm. The quotient of the cross-sectional area of the connecting web 16 with respect to the axial length aS of the slot 15 adjacent to the connecting web 16 in the axial direction is 0.13 mm. In absolute numbers, in the case of the expansible anchor 1 illustrated herein the axial length aV of the connecting web 16 is 1.0 mm, while the radial thickness dV of the connecting web 16 is 1.25 mm.

[0030] The expansion sleeve 13 has in the unexpanded state a diameter DS that is smaller than the nominal diameter of the expansible anchor 1. The nominal diameter of the expansible anchor 1 is the same as the nominal diameter of the drill to be used to drill the hole into which the expansible anchor 1 is to be introduced. In the case of the expansible anchor 1 according to the invention shown in the Figures the nominal diameter is 8 mm, whereas the diameter DS of the expansion sleeve 13 is 7.5 mm. The resilient ring 18, however, in the undeformed state has a diameter DF which, at 9.1 mm, is larger than the nominal diameter of the expansible anchor 1. When the expansible anchor 1 is inserted as intended into a drilled hole of a nominal diameter, the expansion sleeve 13 does not impede insertion, so that the expansible anchor 1 can be pushed or inserted into the drilled hole without a large amount of force, especially without using a hammer. During insertion, the radially outwardly extending projections 24 fold at least to some extent resiliently into the receiving spaces 25 of the resilient ring 18. The projections 24 rest with their radially outer, free ends in contact with the wall of the drilled hole and are pressed resiliently against the wall of the drilled hole. This gives rise to a frictional force between the resilient ring 18 and the wall of the drilled hole by means of which the resilient ring 18 is held axially fixed in the drilled hole, so that during expansion of the expansion sleeve 13 it is able to act as counter-bearing for the expansion sleeve 13. Once the expansible anchor 1 has been inserted, the shank 4 is moved out of the drilled hole in a direction opposite to the introduction direction E by tightening the nut 8. The expansion sleeve 13 is held axially by the resilient ring 18 as soon as the expander portion 12 of the expander body 11 is drawn between the expansion shells 14 of the expansion sleeve 13 and the expansion sleeve 13 thereby radially expanded. By virtue of the small cross-section of the connecting webs 16, only a small axial force is sufficient for the expansion shells 14 to be pressed apart radially by the expander body 11. That axial expansion force is smaller than the holding force of the resilient ring 18 acting as counter-bearing, which holding force likewise acts in the axial direction. As soon as the expansion shells 14 are pressed against the wall of the drilled hole by the expansion, the necessary expansion force can increase, because the expansion sleeve 13 is then itself clamped in the drilled hole so as to be axially fixed.

[0031] By virtue of its configuration according to the invention, the expansible anchor 1 shown in the Figures can easily, that is say using very little axial force, be introduced into a drilled hole and expanded, which renders handling by a user much simpler in comparison with the known bolt anchors. The expansible anchor 1 consists of a small number of parts, which are easy to assemble and therefore economical to produce.

LIST OF REFERENCE SIGNS

Expansible Anchor

[0032] 1 expansible anchor [0033] 2 front end of the expansible anchor 1 [0034] 3 rear end of the expansible anchor 1 [0035] 4 shank [0036] 5 external thread [0037] 6 load-application means [0038] 7 washer [0039] 8 nut [0040] 9 spacer portion [0041] 10 neck portion [0042] 11 expander body [0043] 12 expander portion [0044] 13 expansion sleeve [0045] 14 expansion shell [0046] 15 slot [0047] 16 connecting web [0048] 17 widened portion of the slot 15 [0049] 18 resilient ring [0050] 19 main body of the resilient ring 18 [0051] 20 weakened position [0052] 21 first end of the main body 19 [0053] 22 second end of the main body 19 [0054] 23 opening of the main body 19 [0055] 24 projection [0056] 25 receiving space of the resilient ring 18 for a projection 24 [0057] aS axial length of the slot 15 [0058] aV axial length of the connecting web 16 [0059] dV radial thickness of the connecting web 16 [0060] DF diameter of the resilient ring 18 [0061] DK diameter of the expander body 11 [0062] DS diameter of the expansion sleeve 13 [0063] E introduction direction [0064] L longitudinal axis [0065] U circumferential direction