NZ553425A - A safety anchor - Google Patents

Abstract

A safety anchor is disclosed. The safety anchor includes a base portion (30), adapted to be connected to a structural member, an attachment means (24), adapted to be attached to a lanyard line, and a stem (22) between the base portion (30) and the attachment means (24). The stem (22) has a region (26), bounded by at least one shoulder (27) of reduced cross-sectional area compared to the remainder of the stem (22). In the event of a predetermined force or greater applied to the attachment means (24), the stem (22) is adapted to at least initially bend at the region (26) of reduced cross-sectional area.

Description

10053303065* ;55 3 4 25 ;PATENTS FORM 5 PATENTS ACT 1953 ;Our Ref: 800004NZ Dated: 22 February 2007 ;COMPLETE SPECIFICATION ;A safety anchor ;I, Andrew Douglas Pridham, an Australian Citizen, of 28 Farnsworth Avenue, Campbelltown, New South Wales, 2560, Australia, 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: ;0013E(688607_1):IRG ;1 ;A Safety Anchor Field of the Invention ;The present invention relates to a safety anchor. The invention has been primarily developed for use as a single point safety anchor for securing a harnessed worker while working at height, and will be described with reference to that application. However, it will be appreciated that the invention is not limited to that application. ;Background of the Invention ;Australian standards and corresponding standards in other countries require that any person working at a significant height must be protected against falling. One such means of fall protection involves the worker wearing a safety harness which is connected by a lanyard line to a safety anchor attached to the roof or other such elevated surface. The anchor is capable of arresting the load generated by the worker in the event of a fall. Typically, the safety anchor must be capable of arresting loads of up to 21kN, which equates to the situation where two workers are attached to a single safety anchor. ;However, many buildings are not capable of withstanding the significant forces generated during a fall, unless additional structural strengthening is carried out. ;Accordingly, some existing safety anchorage systems are designed with a specific focus on reducing the forces applied to the structure in the event of a fall. One such existing anchor points includes a tapered stem section with a diameter that reduces along its length. In the event of a sufficiently large force during a fall, the stem bends to take on an overall curved profile, and so absorbs a portion of the fall energy. ;A disadvantage of these safety anchors is that complex and expensive mounting systems are involved. A further disadvantage is that there is an inferior energy reduction regarding the force applied to the structure. Accordingly, additional strengthening of the structure may be required. ;Object of the Invention ;It is an object of the present invention to overcome or ameliorate one or more of the above described disadvantages, or at least to provide a useful alternative to existing safety anchors. ;la ;97450-2:KEH ;2 ;Summary of the Invention ;The present invention provides a safety anchor including: ;a base portion adapted to be connected to a structural member; ;5 an attachment means adapted to be attached to a lanyard line; and a stem between said base portion and said attachment means, said stem having a region, bounded by at least one shoulder, of reduced cross-sectional area compared to the remainder of the stem; ;wherein, in the event of a predetermined force or greater being applied to the 10 attachment means, said stem is adapted to at least initially bend at the region of reduced cross-sectional area. ;Preferably, the region of reduced cross-sectional area is further bounded by a second shoulder. ;The region of reduced cross-sectional area preferably occupies between 6% and 15 22% of the length of the stem, most preferably about 13%. ;The region of reduced cross-sectional area is preferably closer to the attachment means than the base portion. ;The shoulder adjacent to the base portion is preferably between 63% and 71% of the length of the stem measured from the base, most preferably 68%. 20 The region of reduced cross-sectional area preferably has an area which is 40% ;of the area of the remainder of the stem. ;Preferably, the stem between the base portion and the region of reduced cross-sectional area and the stem between the attachment means and the region of reduced cross-sectional area each have a substantially constant cross-sectional area over their 25 entire lengths. ;Preferably, the stem between the base portion and the region of reduced cross-sectional area and the stem between the attachment means and the region of reduced cross-sectional area each have substantially constant and equal cross-sectional area over their entire lengths. ;30 Preferably, the stem between the base portion and the region of reduced cross- ;sectional area and the stem between the attachment means and the region of reduced cross-sectional area each have substantially constant and equal circular cross-sectional area over their entire lengths. ;The region of reduced cross-sectional area is preferably circular in cross-section. ;INTELLECTUAL PROPERTY OFFICE OF N.Z. ;3 0 MAY 2008 ;97450 4:JIS _ _ ;RECEIVED ;2a ;The attachment means is preferably an eyelet. ;The stem preferably includes a threaded portion adapted to engage the base portion. ;97450 4:JIS ;The eyelet is preferably integrally formed with the stem by means of a drop forging process. ;The safety anchor preferably includes a permanently fitted malleable handle adapted to assist in attaching the anchor to the structural member. ;Brief Description of the Drawings ;A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: ;Fig. 1 shows a safety anchor according to the present invention, ;Fig. 2 is a detail of the stem of the safety anchor, adaptable to be connected to alternative mounting brackets, ;Fig. 3 shows the safety anchor of figure 1 mounted with a bracket to a structural member, ;Fig. 4 shows a side view of the safety anchor of figure 1 installed on a structural member, ;Fig. 5 shows a second mounting arrangement in which the safety anchor is mounted to a structural purlin having a "C" or "Z" section, ;Fig. 6 is a side view of the safety anchor mounted to a purlin having a "C" ;section, ;Fig. 7 is a side view of a mounting arrangement similar to figure 6 mounted on a purlin having a "Z" section, ;Fig. 8 shows a safety anchor mounted on a section of roof cladding, ;Fig. 9 is a plan view of the safety anchor shown in figure 8, ;Fig. 10 is a detail of a mounting bracket for the safety anchor shown in Figs. 3 ;and 4, ;Fig. 11 is a detail of the mounting bracket shown in Figs. 8 and 9, ;Fig. 12 shows the mounting components for attaching the safety anchor to a steel purlin, prior to installation, and ;Fig. 13 shows the mounting components of Fig. 12 in a bent condition after installation. ;Detailed Description of the Preferred Embodiments ;Fig. 1 shows a safety anchor 20. The anchor 20 includes a stem 22 made from a cylindrical steel rod and an eyelet 24 is attached to one end extremity 23 of the stem 22. ;3 ;97450-2 :KEH ;The stem 22 has a region of reduced cross-sectional area 26. The region 26 is bounded on each side by shoulders 27, 28, at which the stem 22 diameter changes between a reduced diameter and the full diameter. The region 26 has a reduced ability to resist bending (relative to the remainder of the stem 22) when a force is applied to the eyelet 24, by having a reduced moment of inertia about a generally central transverse axis X. The shoulders 27,28 provide radial surfaces 29. ;The extremity 23 is integrally formed with the eyelet 24. Alternatively, the extremity 23 can be threaded for engagement with another attachment means such as a bracket (not shown) for receiving a static line. The other end extremity 25 of the stem 22 has a threaded region 30 which engages with a mounting bracket 31 for attachment to the structure of a roof or other such elevated work site. ;The region 26 is located on the stem 22 closer to the extremity 23, relative to the extremity 25. The region 26 indicated by the dimension "B" in Fig. 2 occupies between 6% and 22% of the length of the stem 22, and typically 13%. The distance from the start of the threaded region 30 to the closest shoulder 27, indicated by the dimension "C" in Fig. 2 is between 63% and 71% of the length of the stem, and typically 68%. The region of reduced cross-sectional area 26 has an area which is 40% of the area of the remainder of the stem 22. ;In the mounting arrangement of Fig. 3, a stainless steel nut 32 is positioned on the stem 22 above the mounting bracket 31, and another stainless steel nut 33 is positioned on the stem 22 below the mounting bracket 31. When each of the nuts 32, 33 are fastened, the stem 22 is secured to the mounting bracket 31. The mounting bracket 31 is a stainless steel angle with equal length legs 34, 35. The bracket 31 has three apertures 36, located along its length as shown in Figs. 4 and 10 such that the safety anchor 20 can be selectively positioned at different locations along the length of the bracket 31. ;The vertically extending arm 35 of the bracket 31 is secured to a timber or steel beam 37 using bolts or screws (not shown) which are inserted through the holes 39. ;In an alternative mounting arrangement shown in Figs. 8 to 11, a mounting bracket 40 is attachable to a section of steel roof cladding 42. The bracket 40 (as seen in Fig. 8) includes a central portion which has downwardly depending arms 44, on each side, and each arm 44 is fastened to the roof cladding 42 with a number of Gespia rivets 46, as shown in Figs. 8 and 9. ;In this mounting arrangement, when secured to a section of roof cladding 42, a central portion of the mounting bracket 40 is raised sufficiently above the cladding 42, to provide a clearance between the cladding 42 and the lower side of the bracket 40 for ;4 ;97450-2:KEH ;accommodating the threaded extremity 25 of the stem 22, the nut 33 and a mounting plate 47. ;As shown in Fig. 9, the mounting bracket 40 is sufficiently large to permit a number of rivets 46 to be spaced along each arm 44. Any force applied to the safety anchor 20 (which is not absorbed by the anchor 20) is subsequently distributed through the rivets 46, into the underlying structural member. ;In a further mounting arrangement, the roof anchor 20 can be mounted to a steel purlin 48 from above the roof surface. As best seen in Figs. 6 and 7, the purlin 48 may be a "Z" section purlin 49, or a "C" section purlin 50. In this mounting arrangement a handle 52 (best seen in Figs. 12 to 13) having a hexagonal shaped holder 54 is placed around the lower nut 33. The other end of the handle 52 extends through a hole in the roof cladding 42, or alternatively projects from a side of the purlin 48, such that the handle 52 can be accessed from above the cladding 42 or purlin 50 by a worker. The handle 52 is permanently fitted and made from a malleable material. The nut 33 is welded to the mounting plate 47 to prevent the nut 33 from rotating while the stem 22 of the anchor 20 is being fastened to the nut 33. ;The eyelet 24 is formed integrally with the stem 22 by a drop forging process. In an Alternative embodiment, an attachment bracket such as a static line may be fitted to the stem 22. ;In one embodiment, the eyelet 24 is able to swivel relative to the stem 22, permitting the orientation of the eyelet 24 to change as a worker moves to a different location on the work site. ;Different lengths of the stem 22 are possible. For example, in the event that the roof anchor 20 is used for abseiling or attachment point purposes, the anchor 20 may have a shorter stem 22. ;The operation of the safety anchor 20 will now be described. The safety anchor 20 is connected to a structural member such as a timber beam 37, a steel purlin 48 or a portion of roof cladding 42 on a work site. A worker who is wearing a safety harness secures a lanyard line to the harness. A second end of the lanyard line having a carabiner (or other such fastener) is secured through the eyelet 24, such that the maximum distance that the worker can move relative to the safety anchor 20 is predetermined. ;In the event that the worker falls from the elevated work site, the force is transmitted through the lanyard line to the eyelet 24. Two distinct bending moments are subsequently applied along the length of the stem 22. The stem 22 is accordingly able to deform in two ways. Initially, deformation occurs at the region of reduced diameter 26. Subsequently, deformation occurs at the base end of the stem 22. ;5 ;97450-2:KEH ;The deformation may be elastic, plastic or a combination thereof. Permanent deformation can also occur in the mounting bracket 31, 40, depending on the size of the force. The deformation process results in energy generated by the force being absorbed by the anchor 20. ;After a fall has been restrained by the safety anchor 20, the anchor 20 is removed from the building structure and replaced with a new anchor 20. The mounting bracket 31, 40 is also replaced at this stage if required. ;An advantage of the present invention is that it provides superior energy absorption properties during a fall, such that a portion of force that would otherwise be applied to the structure is absorbed. ;A further advantage of the invention is that the superior energy absorption reduced the need to strengthen the underlying mounting structures. ;Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. ;97450-2:KEH ;6 *

Claims (17)

The claims defining the invention are as follows:

1. A safety anchor including: a base portion adapted to be connected to a structural member; an attachment means adapted to be attached to a lanyard line; and a stem between said base portion and said attachment means, said stem having a region, bounded by at least one shoulder, of reduced cross-sectional area compared to the remainder of the stem; wherein, in the event of a predetermined force or greater being applied to the attachment means, said stem is adapted to at least initially bend at the region of reduced cross-sectional area.

2. The safety anchor as claimed in claim 1, wherein the region of reduced cross-sectional area is further bounded by a second shoulder.

3. The safety anchor as claimed in claim 2, wherein the region of reduced cross-sectional area occupies between 6% and 22% of the length of the stem.

4. The safety anchor as claimed in claim 3, wherein the region of reduced cross-sectional area occupies about 13% of the length of the stem.

5. The safety anchor as claimed in any one of the preceding claims, wherein the region of reduced cross-sectional area is closer to the attachment means than the base portion.

6. The safety anchor as claimed in any one of the preceding claims, wherein the shoulder adjacent to the base portion is between 63% and 71% of the length of the stem measured from the base.

7. The safety anchor as claimed in claim 6, wherein the shoulder adjacent to the base portion is about 68% of the length of the stem measured from the base.

8. The safety anchor as claimed in any one of the preceding claims, wherein the region of reduced cross-sectional area has an area which is about 40% of the area of the remainder of the stem.

9. The safety anchor as claimed in any one of the preceding claims, wherein the stem between the base portion and the region of reduced cross-sectional area and the stem between the attachment means and the region of reduced cross-sectional area each have a substantially constant cross-sectional area over their entire lengths.

10. The safety anchor as claimed in any one of the claims 1 to 8, wherein the stem between the base portion and the region of reduced cross-sectional area 97450 4:JIS INTELLECTUAL PROPERTY OFFICE OF N.Z. 1 1 AUG 2008 8 and the stem between the attachment means and the region of reduced cross-sectional area each have substantially constant and equal cross-sectional area over their entire lengths.

11. The safety anchor as claimed in any one of the claims 1 to 8, wherein the stem between the base portion and the region of reduced cross-sectional area and the stem between the attachment means and the region of reduced cross-sectional area each have substantially constant and equal circular cross-sectional area over their entire lengths.

12. The safety anchor as claimed in any one of the preceding claims, wherein the region of reduced cross-sectional area is circular in cross-section.

13. The safety anchor as claimed in any one of the preceding claims, wherein the attachment means is an eyelet.

14. The safety anchor as claimed in claim 13, wherein the eyelet is integrally formed with the stem by means of a drop forging process.

15. The safety anchor as claimed in any one of the preceding claims, wherein the stem includes a threaded portion adapted to engage the base portion.

16. The safety anchor as claimed in any one of the preceding claims, wherein the safety anchor includes a permanently fitted malleable handle adapted to assist in attaching the anchor to the structural member.

17. A safety anchor substantially as described herein with reference to the accompanying drawings. Andrew Douglas Pridham By the Attorneys for the Applicant 97450 4:JIS INTELLECTUAL PROPERTY OFFICE OF N £ I 1 AUG 2008