Fasteners

Abstract

A fastener 1 comprising a sleeve (2 Fig 1) with an axial bore 4, an externally threaded proximal end 6 and a distal end 10 having a cylindrical outer surface, the bore has a first diameter at the proximal end that tapers to a smaller second diameter, the distal end is circumferentially divided into two or more radial sectors by radial slots 18a-d extending through a wall at the distal end portion, a pin with an outer diameter that is greater than the second diameter of the bore which when driven down the bore from the proximal end of the sleeve forces apart the sectors of the distal end portion radially outwards, an internally threaded nut 28 for engagement with the proximal end portion of the sleeve, at least part of the outer surface of the distal end portion is knurled or ribbed (12 Fig 2). The outer surface of the distal end portion may have a pattern of straight ribs or ribs that extend axially. The whole of the outer surface of the distal end portion may be substantially knurled or ribbed. A part of the outer surface of the distal end portion may not be knurled or ribbed.

Description

DESCRIPTION Technical Field The present invention relates to fasteners for fastening to a structural member such as a box section, for example. Background Art A known fastener (or “peg anchor”) is sold by Advanced Bolting Solutions Ltd of 8 Frog Island, Leicester, LE3 5AG. The fastener includes a sleeve with an axial bore therethrough. The sleeve has an externally screw-threaded proximal end portion that extends from a proximal end of the sleeve, and a distal end portion having a cylindrical outer surface. The bore has a first diameter at the screw-threaded proximal end portion and tapers to a second diameter at the distal end portion. The second diameter is smaller than the first diameter. The distal end portion is circumferentially divided into four sectors by four radial slots. The slots extend through a wall of the distal end portion and extend axially along part of the distal end portion. The fastener includes a pin that is positioned in the bore of the sleeve. The pin has an outer diameter greater than the second diameter of the bore. The fastener also includes an internally screw-threaded nut for screw-threaded engagement with the proximal end portion of the sleeve. In use, the distal end of the fastener is received through an opening in a structural member such as a wall of a box section, for example. The diameter of the opening is only slightly larger than the diameter of the sleeve. The nut is in screw-threaded engagement with the sleeve and is positioned at the proximal end. The fastener may be received through the opening until the nut abuts the structural member. The pin is driven down the bore of the sleeve from the proximal end of the sleeve. When the end of the pin reaches the taper, it forces apart the sectors of the distal end portion - i.e., so that the sectors move radially outwardly. This increases the outer diameter of the distal end portion of the sleeve. The nut is then tightened. This moves the distal end portion of the sleeve towards the nut and eventually a part of the distal end portion may be drawn in to the opening of the structural member. Further movement of the sleeve is eventually prevented by the forced-apart sectors of the distal end portion of the sleeve which will not fit through the opening. In other words, the wall of the structural member is sandwiched between the nut and the forced-apart sectors of the distal end portion of the sleeve. Summary of the Invention The present invention provides an improved fastener (or improved “peg anchor”) comprising a sleeve with an axial bore therethrough, the sleeve comprising an externally screw-threaded proximal end portion extending from a proximal end of the sleeve, and a distal end portion having a cylindrical outer surface, the bore having a first diameter at the screw-threaded proximal end portion and tapering to a second diameter at the distal end portion, the second diameter being smaller than the first diameter, the distal end portion being circumferentially divided into two or more sectors by radial slots extending through a wall of the distal end portion and extending axially along part of the distal end portion; a pin having an outer diameter greater than the second diameter of the bore, which pin on being driven down the bore of the sleeve from the proximal end of the sleeve forces apart the sectors of the distal end portion radially outwardly; and an internally screw-threaded nut for screw-threaded engagement with the proximal end portion of the sleeve; wherein at least part of the outer surface of the distal end portion is knurled or ribbed. The outer surface of the distal end portion of the sleeve may be knurled or ribbed -i.e., formed with a pattern of straight, angled, or crossed ribs or ridges. Substantially the whole of the outer surface of the distal end portion may be knurled or ribbed. In particular, the pattern of ribs or ridges may extend all the way around the circumference of the distal end portion. Alternatively, the pattern of ribs or ridges may extend only part of the way around the circumference of the distal end portion or may extend in two or more regions of the distal end portion that are spaced apart in the circumferential direction. The pattern of ribs or ridges may extend from the transition between the screw-threaded proximal end portion and the distal end portion towards the distal end of the sleeve - i.e., so that the pattern of ribs or ridges extends all the way to, or close to, the transition at the proximal end of the distal end portion. This is the part of the distal end portion that is likely to be received in the opening of the structural member when the fastener is being fastened thereto as described in more detail below. The pattern of ribs or ridges may extend all the way to the distal end of the sleeve, or there may be a narrow band at the distal end of the sleeve that is not knurled or ribbed. In one arrangement, the distal end portion is formed with a pattern of straight ribs or ridges that extend axially - i.e., along the longitudinal axis of the sleeve. In use, the distal end of the sleeve (which corresponds to the distal end of the fastener) is received through an opening in a structural member such as a wall of a box section, for example. The diameter of the opening is only slightly larger than the diameter of the sleeve. The nut is in screw-threaded engagement with the sleeve and is positioned at the proximal end of the sleeve (which corresponds to the proximal end of the fastener). The fastener may be received through the opening until the nut abuts the structural member. The pin is driven down the bore of the sleeve from the proximal end of the sleeve. When the distal end of the pin contacts the tapered portion of the bore, it forces apart the sectors of the distal end portion - i.e., so that the sectors move radially outwardly. The distal end of the pin may be tapered. The outer diameter of the pin may be a close tolerance match to the first diameter of the bore. The nut is then tightened. This moves the distal end portion of the sleeve towards the nut and eventually a part of the distal end portion may be drawn in to the opening of the structural member. In particular, at least part of the knurled or ribbed distal end portion may be drawn into the opening of the structural member. The pattern of ribs or ridges define “teeth” that “bite” into the structural member and prevent the sleeve from rotating relative to the structural member while the nut is being tightened. Further movement of the sleeve is eventually prevented by the forced-apart sectors of the distal end portion of the sleeve which will not fit through the opening. In other words, the structural member is sandwiched between the nut and the forced-apart sectors of the distal end portion of the sleeve. The pattern or ribs or ridges also help to secure the fastener within the opening and prevent relative rotation while the fastener remains fastened or secured to the structural member. Drawings Figure 1 is a side view of the sleeve of a fastener according to the present invention; Figure 2 is a detail view of the distal end portion of the fastener of Figure 1 where the knurled pattern comprises axially-extending ribs or ridges; Figure 3 is an end view of the distal end of the sleeve of Figure 1; Figure 4 is a cross-section view of the sleeve of Figure 1; Figure 5 is a side view of an expansion pin of the fastener according to the present invention; and Figures 6 to 9 show how the fastener of the present invention may be fastened to a structural member, e.g., to a wall of a steel box section. Referring to Figures 1 to 5, a fastener 1 according to the present invention comprises a sleeve 2 with an axial bore 4 therethrough. The sleeve 2 comprises an externally screw-threaded proximal end portion 6 extending from a proximal end 8 of the sleeve. A distal end portion 10 of the sleeve 2 has a cylindrical outer surface. At least part of the outer surface of the distal end portion 10 is knurled or ribbed - this is indicated in Figures 1 and 6 to 9 by the cross-hatched region. In particular, the outer surface of the distal end portion 10 may be formed with a pattern of straight, angled, or crossed ribs or ridges. Figure 2 shows an example where the outer surface of the distal end portion 10 of the sleeve 2 is formed with a pattern of straight ribs or ridges 12 that extend axially - i.e., along the longitudinal axis of the sleeve 2. But it will be understood that other patterns are possible, e.g., where the straight ribs or ridges are angled or crossed to define a particular knurled pattern such as a diamond pattern, for example. Figure 2 shows that the ribs or ridges 12 extend all the way around the circumference of the distal end portion 10. The ribs or ridges 12 extend from the transition between the screw-threaded proximal end portion 6 and the distal end portion 10 towards the distal end 14 of the sleeve 2. There is a narrow band 16 at the distal end 14 of the sleeve 2 that is not knurled or ribbed - i.e., the ribs or ridges 12 do not extend all the way to the distal end 14 of the sleeve 2. The outer diameter of the sleeve 2 is substantially constant along its axial length - i.e., the proximal end portion 6 and the distal end portion 10 have substantially the same outer diameter as shown. The distal end portion 10 is circumferentially divided into four sectors 10a, 10b, ..., lOd by radial slots 18a, 18b, ..., 18d. It will be understood that other types of fastener may have two, three or five or more sectors and radial slots, for example. Each slot 18a, 18b, ..., 18d extends through a wall 14 of the distal end portion 10 and extends axially along a substantial part of the distal end portion 10 as shown. Each slot 18a, 18b, ..., 18d extends axially from the distal end 14 of the sleeve 2 and the four slots form a cross-shaped opening in the planar end face of the distal end 14 as shown in Figure 3. Referring to Figure 4, the bore 4 has a first diameter at the screw-threaded proximal end portion 6 and tapers to a second diameter at the distal end portion 10. The fastener 1 includes an expansion pin 20 having an outer diameter that is greater than the second diameter of the bore 4. The expansion pin 20 is also longer than the length of the bore 4 so that when it is positioned in the bore with its tapered distal end 22 at the tapered portion 24 of the bore, its non-tapered proximal end 26 projects or extends beyond the proximal end 8 of the sleeve 2. This is shown clearly in Figures 6 and 7. The fastener 1 includes an internally screw-threaded nut 28 (see Figures 6 to 9). The nut 28 is in screw-threaded engagement with the proximal end portion 6 of the sleeve 2. Referring to Figure 6 to 9, the fastener 1 may be fastened to a structural member 30 such as a steel box section, for example. A hole or opening 32 is formed in a wall of the structural member 30, e.g., by drilling. The opening 32 has a diameter that is a close tolerance match to the outer diameter of the sleeve 2 of the fastener 1. Figure 6 shows how the distal end 14 of the sleeve 2 is received through the hole or opening 32. The expansion pin 20 is positioned in the bore 4 and the nut 28 is in screw-thread engagement with the proximal end potion 6 of the sleeve 2 and positioned the proximal end 8 of the sleeve. The fastener 1 is received through the opening 32 until the nut 28 abuts the structural member 30 - see Figure 7. The expansion pin 20 is driven down the bore 4 of the sleeve 2. The tapered distal end 22 of the expansion pin 20 forces apart the sectors 10a, 10b, ..., lOd of the distal end portion 10 of the sleeve 2 - i.e., so that the sectors 10a, 10b, ..., lOd move radially outwardly as shown in Figure 8. This increases the outer diameter of the distal end portion 10 of the sleeve. The nut 28 is then tightened. Tightening the nut 28 moves the distal end portion 10 towards the nut 28 and eventually a part of the distal end portion 10 is drawn into the opening 32 of the structural member 30. In particular, at least part of the knurled or ribbed distal end portion 10 is drawn into the opening 32 of the structural member 30. This is shown in Figure 9 where part of the cross-hatched region that indicates the knurled or ribbed part of the distal end portion 10 of the sleeve 2 is located within the opening 32. The pattern of ribs or ridges (e.g., the straight ribs or ridges 12 shown in Figure 2) acts as “teeth” and “bite” into the steel of the structural member. This prevents the fastener 1 from rotating relative to the structural member 30 while the nut 28 is being tightened to the required torque. Eventually further movement of the sleeve 2 is prevented by the forced-apart sectors 10a, 10b, ..., lOd of the distal end portion 10 of the sleeve 2 which will not fit through the opening 32. As shown in Figure 9, the structural member 30 is sandwiched between the nut 28 and the forcedapart sectors 10a, 10b, ..., lOd of the distal end portion 10 of the sleeve 2. The pattern or ribs or ridges 12 also help to secure the fastener 1 within the opening 32 and 5 prevent relative rotation after the nut 28 has been tightened to the required torque and while the fastener 1 remains fastened to the structural member 30.

Claims

1. A fastener comprising:a sleeve with an axial bore therethrough, the sleeve comprising an externally screw-threaded proximal end portion extending from a proximal end of the sleeve, and a distal end portion having a cylindrical outer surface, the bore having a first diameter at the screw-threaded proximal end portion and tapering to a second diameter at the distal end portion, the second diameter being smaller than the first diameter, the distal end portion being circumferentially divided into two or more sectors by radial slots extending through a wall of the distal end portion and extending axially along part of the distal end portion;a pin having an outer diameter greater than the second diameter of the bore, which pin on being driven down the bore of the sleeve from the proximal end of the sleeve forces apart the sectors of the distal end portion radially outwardly; andan internally screw-threaded nut for screw-threaded engagement with the proximal end portion of the sleeve;wherein at least part of the outer surface of the distal end portion is knurled or ribbed.

2. A fastener according to claim 1, wherein the outer surface of the distal end portion comprises a pattern of straight ribs or ridges that extend axially.

3. A fastener according to claim 1 or claim 2, wherein substantially the whole of the outer surface of the distal end portion is knurled or ribbed.

4. A fastener according to claim 1 or claim 2, wherein at least part of the outer surface of the distal end portion is not knurled or ribbed.

Images