GB1583566A

GB1583566A - Expansion anchor device

Info

Publication number: GB1583566A
Application number: GB36161/77A
Authority: GB
Original assignee: Fermo D J
Current assignee: Fermo D J
Priority date: 1976-09-02
Filing date: 1977-08-30
Publication date: 1981-01-28
Also published as: ZA765270B

Description

(54) EXPANSION ANCHOR DEVICE (71) DORIN JOSEPH FERMO, a South African citizen of 55 Northwold Avenue, Saxonwold, Johannesburg, Transvaal Prov ince, Republic of South Africa, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement This invention relates to an expansion anchor device adapted to expand into engagement with predrilled holes in cementitious material, masonry, rock and the like.

It is the object of this invention to provide a relatively simple yet effective device of the above type.

In accordanee with this invention an expansion anchor device is provided comprising a hollow cylindrical member which is machined from solid bar and which is adapted to -expand radially, said member having a tapered internal wall section extending along at least part of the length thereof and a shaped expansion element held captive in and movably located in the member and adapted to act on the tapered wall section to expand the member upon relative longitudinal movement thereof, said cylindrical member having at least two angularly spaced longitudinally extending slits therein extending from a first end of the member and along part of the length of the member which includes the tapered wall section.

Preferably, the expansion element will be held captive in the cylindrical member by inwardly projecting lips defining said first end of the member, and the shape expansion element will be in the form of a truncated cone having radially outwardly projecting formations which extend into and are slidable along the slits in the member.

The cylindrical member will preferably have a circumferential recess in its outer surface and at least one knurled circumferential rib, and the expansion element will preferably take the form of either a head on a screwthreaded stud or a nut-like form in which case a screwthreaded hole is provided therethrough.

These and other features of the invention will become apparent from an embodiment now described by way of example only with reference to the accompanying drawings in which: Fig. 1 is a section side elevation of a cylindrical member forming part of an expansion anchoring device; Fig. 2 is a side elevation of a shaped expansion element included in the device; Fig. 3 is an end view of the shaped expansion element; and Fig. 4 is a side elevation of an alternative wedge shaped element.

As shown in Figs. 1 to 3 an expansion anchor device comprises two parts, namely, a hollow cylindrical member or sleeve 1 and a shaped expansion element 2 in the form of a truncated cone shaped nut.

The sleeve 1 has a bore therethrough which is enlarged as indicated by numeral 3 towards one end 4 and the intermediate wall section 5 is outwardly tapered towards this end. The angle of taper is preferably approximately 7W . At least two longitudinal slits 6 are formed in the sleeve and commence at the end 4 thereof having the enlarged part of the bore, and extend along part of the length of the sleeve. The slits are located at diametrically opposed positions or, in the case of more than two slits, at equally circumferentially spaced locations and extend axially inwardly beyond the tapered wall section 5.

In the longitudinal region over which the slits 6 extend, a circumferential recess 7 is formed in the outer surface of the sleeve. In the recess two spaced circumferential ribs 8 remain which are knurled so that their outer peripheries stand somewhat proud of the sleeve surface. The ends 9 of the recess taper inwardly so that a sudden diameter change in the sleeve is avoided and other corners and edges are radiused. The longitudinal location of the recess is such that the tapered wall section is opposite the part of the recess nearer the enlarged part of the bore.

The sleeve is machined from bar or rod which allows it to be accurately manufactured and conveniently mild steel can be used since it has the required property of being capable of deforming somewhat without fracturing.

The cone-shaped nut 2 is dimensioned to fit into the enlarged portion 3 of the bore in the sleeve and the cone angle is approximately 15 to conform with the tapered wall section 5. The cone-shaped nut is axially bored and the bore 10 is screw threaded so that a bolt or other screw threaded fastener 11 can be screwed into the cone in the sleeve to expand the latter as the cone acts on the tapered wall section and moves away from the end 4. The cone is also machined and is held captive in the sleeve by inwardly projecting lips 12 on the adjacent end 4 of the sleeve formed by bending walls defining this end inwardly.

To prevent relative rotation between the sleeve and cone-shaped nut, the latter is provided with radially projecting formations 13 which, in the operative position, are located in the slits 6 in the sleeve. These formations can slide along the slits as the cone-shaped nut moves longitudinally relative thereto.

In use, the sleeve is inserted into a hole 14 in a wall or the like and the knurled ribs 8, provide, with a correctly drilled hole, an initial frictional engagement with the wall of the hole. As the cone-shaped nut is moved longitudinally the sleeve expands into locking engagement with the wall of the hole and the provision of the tapered wall 5 over only part of the length of the sleeve results in a surface to surface contact with the cone as opposed to a line contact when the anchor is tight. Furthermore, the cone apex angle could be made to increase near the wider end 15 thereof to prevent excessive expansion of the sleeve. This is effected by the stepped portion 15 contacting the outer end of the tapered wall 5 at which stage the person inserting the anchoring device will notice a sudden increased resistance to axial movement of the nut.At this stage the anchor will have reached its maximum expansion point for which it is designed.

The tapering ends 9 of the recess reduce weakening of the sleeve as the walls thereof bend outwardly.

The cone-shaped nut and bolt may be replaced by a screw threaded shank 16 (see Fig. 4) having a conical formation 17 defining a head at one end. The outer surface of the conical formation may be identical to that described above, with respect to the nut.

WHAT I CLAIM IS: 1. An expansion anchor device comprising a hollow cylindrical member which is machined from solid bar and which is adapted to expand radially, said member having a tapered internal wall section extending along at least part of the length thereof, and a shaped expansion element held captive in and movably located in the member and adapted to act on the tapered wall section to expand the member upon relative longitudinal movement thereof, said cylindrical member having at least two angularly spaced longitudinally extending slits therein extending from a first end of the said member and along part of the member which includes the tapered wall section.

2. A device as claimed in claim 1, in which the expansion element is held captive in the cylindrical member by inwardly projecting lips defining said first end of said member.

3. A device as claimed in claim 1 or claim 2 in which the expansion element has a tapered outer operative surface thereon.

4. A device as claimed in any one of claims 1 to 3, in which the expansion element is in the form of a nut having a screw threaded bore therein.

5. A device as claimed in any one of claims 1 to 4 in which the expansion element is in the form of a head at one end of screwthreaded shank.

6. A device as claimed in any one of the preceding claims in which the expansion element has formations co-operating with formations or the slits in the cylindrical member to prevent relative rotation of these two parts.

7. A device as claimed in any one of the preceding claims in which the cylindrical member has in its outer surface a circumferentially extending recess and a circumferential rib.

8. A device as claimed in claim 7, in which the outer surface of the rib is knurled.

9. A device substantially as herein described or exemplified with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. capable of deforming somewhat without fracturing. The cone-shaped nut 2 is dimensioned to fit into the enlarged portion 3 of the bore in the sleeve and the cone angle is approximately 15 to conform with the tapered wall section 5. The cone-shaped nut is axially bored and the bore 10 is screw threaded so that a bolt or other screw threaded fastener 11 can be screwed into the cone in the sleeve to expand the latter as the cone acts on the tapered wall section and moves away from the end 4. The cone is also machined and is held captive in the sleeve by inwardly projecting lips 12 on the adjacent end 4 of the sleeve formed by bending walls defining this end inwardly. To prevent relative rotation between the sleeve and cone-shaped nut, the latter is provided with radially projecting formations 13 which, in the operative position, are located in the slits 6 in the sleeve. These formations can slide along the slits as the cone-shaped nut moves longitudinally relative thereto. In use, the sleeve is inserted into a hole 14 in a wall or the like and the knurled ribs 8, provide, with a correctly drilled hole, an initial frictional engagement with the wall of the hole. As the cone-shaped nut is moved longitudinally the sleeve expands into locking engagement with the wall of the hole and the provision of the tapered wall 5 over only part of the length of the sleeve results in a surface to surface contact with the cone as opposed to a line contact when the anchor is tight. Furthermore, the cone apex angle could be made to increase near the wider end 15 thereof to prevent excessive expansion of the sleeve. This is effected by the stepped portion 15 contacting the outer end of the tapered wall 5 at which stage the person inserting the anchoring device will notice a sudden increased resistance to axial movement of the nut.At this stage the anchor will have reached its maximum expansion point for which it is designed. The tapering ends 9 of the recess reduce weakening of the sleeve as the walls thereof bend outwardly. The cone-shaped nut and bolt may be replaced by a screw threaded shank 16 (see Fig. 4) having a conical formation 17 defining a head at one end. The outer surface of the conical formation may be identical to that described above, with respect to the nut. WHAT I CLAIM IS:

1. An expansion anchor device comprising a hollow cylindrical member which is machined from solid bar and which is adapted to expand radially, said member having a tapered internal wall section extending along at least part of the length thereof, and a shaped expansion element held captive in and movably located in the member and adapted to act on the tapered wall section to expand the member upon relative longitudinal movement thereof, said cylindrical member having at least two angularly spaced longitudinally extending slits therein extending from a first end of the said member and along part of the member which includes the tapered wall section.