Field of the Invention

The present invention related to fasteners.

Background of the Invention

One type of fastener comprises a bolt and a nut where the nut is threadably engaged with the bolt so as to apply a clamping force between the nut and a head of the bolt. When using a nut and bolt to fix objects together, access is required to opposite sides of the objects to enable the bolt to be passed through aligned holes in the objects from one side and engaged with a nut held on the opposite side, and then for one or both to be held and rotated.

Another type of fastener known as an expansion fastener or anchor comprises a shaft having a wedge at an end which is drawn into an expansion sleeve by rotating a nut which is engaged with an opposite end of the shaft and abuts the sleeve. When this type of fastener is inserted into a hole and the nut rotated, the sleeve is expanded outwardly to apply pressure against a circumferential wall of the hole. In effect this increase the frictional force holding the fastener against the wall of the hole they fastening the fastener in the hole.

Summary of the Present Invention

In one aspect the invention provides a fastener comprising: a retainer for insertion through a hole through one or more objects so that an engagement surface of an expandable portion of the retainer clears the hole, the retainer comprising an internal thread; a bolt comprising a head and an external thread for threadably engaging the internal thread of the retainer; wherein rotation of the bolt relative to the retainer expands the expandable portion so that the engagement surface is wider than the hole and moves the engagement surface to a position where the one or more objects are clamped by action of the head of the bolt and the engagement surface. The engagement surface may comprise one or more shoulders, the or each shoulder formed about an outer surface of the retainer and having a surface capable of contacting a surface adjacent the hole in a last of the one or more objects in which the retainer is inserted, wherein the surface of the or each shoulder lies substantially perpendicular to an axis of the hole in the one or more objects.

The retainer may comprise an activation piece having a wedge portion; and, a sleeve comprising the expandable portion capable of at least partly receiving the wedge portion.

The wedge portion may be arranged to expand the expandable portion when the activation piece is pulled in a first direction such that the engagement surface is wider than before the expandable portion is expanded, and the engagement surface is able to apply a force substantially in the first direction in response to continued pulling of the activation piece.

The activation piece may comprise a flange at one end.

The activation piece may comprise a longitudinal axis, and an internally threaded hole extending at least partly along the longitudinal axis.

The wedge portion may be positioned at an end of the longitudinal axis opposite the flange.

The activation piece may comprise a first cylindrical portion between the wedge portion and the flange.

The activation piece may comprise a second cylindrical portion of a smaller outer diameter than the first cylindrical portion and located between the wedge portion and the first cylindrical portion.

The wedge portion may be conically shaped to reduce in outer diameter in a direction away from the flange.

The expandable portion may have a first section and a second section which are separated by the or one of the shoulders. The sleeve may have a maximum width which is no greater than a maximum width of the activation piece before the expandable potion is expanded.

The expandable portion may be capable of expanding to a width greater than a maximum width of the activation piece when expanded by the activation piece.

The sleeve may comprise a longitudinal axis and a concentric portion having an inner circumferential surface of constant inner diameter and an outer circumferential surface of constant outer diameter and from which the expandable portion coaxially extends.

The expandable portion may comprise a plurality of longitudinally extending sections capable of outward deflection by the wedge portion when the expanding portion is expanded.

The expandable portion may have an inside surface portion of reducing inner diameter in a direction away from the concentric portion.

The inside surface portion may have a first wall portion contiguous with the inner circumferential surface of the concentric portion and having a first opening angle.

The inside surface portion may have a second wall portion contiguous the first wall portion and having with a second opening angle which is larger than the first opening angle.

The inside surface portion may have a third wall portion contiguous with the second wall portion and having a third opening angle larger than the second opening angle.

The second section may be narrower than the first section and the second section may be located to lie at least in part in the hole.

The shoulder and the first section may be arranged to move radially outward when the expanding portion is expanded such that at least a part of the shoulder and the first section are larger in width than the maximum width of the activation piece.

The second portion may be capable of applying an expansion force to the interior of the hole when the expandable portion is expanded.

In a second aspect the invention provides a method of fastening one or more objects having a hole the one or more objects, said method comprising: inserting a retainer through hole so that an engagement surface of an expandable portion of the retainer clears the hole; threadably engaging a bolt with an internal thread of the retainer; rotating the bolt relative to the retainer to expand the expandable portion so that the engagement surface is wider than the hole and to move the engagement surface to a position where the one or more objects are clamped by action of the head of the bolt and the engagement surface.

In a third aspect the invention provides method of fastening a wear plate to a support structure comprising: forming respective holes in the support structure and the wear plate; locating the wear plate on one side of the support structure in a juxtaposition where at least one hole in the wear plate registers with a hole in the support structure to form an extended hole ; inserting a retainer through the extended hole from a side adjacent the wear plate so that an engagement surface of an expandable portion of the retainer clears the extended hole on a side adjacent the support; threadably engaging a bolt with an internal thread of the retainer; rotating the bolt relative to the retainer to expand the expandable portion so that the engagement surface is wider than the extended hole and the engagement surface is moved to a position where the wear plate is fastened to the support structure by a clamping like action between the head of the bolt and the engagement surface.

The method may comprise forming the hole in the wear plate which registers with the hole in the support structure to have a conical circumferential surface and utilising the head of hte bolt to transfer force to the circumferential surface of the hole. In another aspect the invention provides a retainer for a fastener, the retainer capable of insertion through a hole through one or more objects and comprising: a sleeve having an expandable portion which comprises an engagement surface; an activation piece having a wedge portion, the activation piece capable of engaging a bolt and causing the expandable portion to expand; wherein when the retainer is inserted into the hole and the engagement surface clears the hole, the activation piece is capable of expanding the expandable portion such that the engagement surface is wider than the hole and moves the engagement surface to a position where the engagement surface abuts and applies a force to a surface of one of the objects through which the retainer is inserted so as to clamp the one or more objects by action of the engagement surface and a bolt engaged with the retainer.

In another aspect the invention provides a fastener comprising: a bolt having an external thread; and a retainer, the retainer comprising: an activation piece having an internal thread, a wedge portion and a flange portion; and a sleeve arranged to at least partly receive the wedge portion, the sleeve comprising an expandable portion having an engagement surface, wherein the wedge portion is arranged to expand the expandable portion such that the engagement surface is wider than before the expandable portion is expanded when the activation piece is moved in a first direction by the bolt when the bolt is threadably engaged with the internal thread, and the engagement surface is able to apply a force substantially in the first direction in response to continued movement of the activation piece by the bolt such that the force contributes to a clamping action between the bolt and the engagement surface.

In yet another aspect the invention there provides a fastener component comprising: an activation piece having a wedge portion; and a sleeve arranged to at least partly receive the wedge portion, the sleeve comprising an expandable portion having an engagement surface, wherein the wedge portion is arranged to expand the expandable portion such that the engagement surface is wider than before the expandable portion is expanded when the activation piece is moved in a first direction , and the engagement surface is able to apply a force substantially in the first direction in response to continued movement of the activation piece when the expandable portion is expanded.

Brief Description of the Drawings

In order to provide a better understanding, the embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a cross-sectional side elevation of a retainer of a fastener according to an embodiment of the present invention; Fig. 2 is a cross-sectional side elevation of a sleeve component of the retainer of Fig. 1 ;

Fig. 3 is a cross-sectional side elevation of an activation component of the retainer of Figure 1 ;

Fig. 4 is a cross-sectional side elevation of a fastener in accordance with the present invention, comprising the retainer of Fig. 1 in an activated state; and

Fig. 5 is an end view of the fastener of Fig. 4 looking at the right hand side of the elevation of Fig. 4.

Detailed Description of Preferred Embodiment

Referring to Figs. 1-3 there is a fastener component in the form of a retainer 10. The retainer 10 comprises an activation piece 12 and a sleeve 14. The activation piece 12 comprises an elongated body with an axially extending through-hole 20 provided with an internal thread 36. The activation piece 12 comprises: wedge portion 22 at one end 25, a radially extending flange 30 at an opposite end 27, and cylindrical portions 26 and 28 of different diameter which space the wedge portion 22 from the flange 30. The wedge portion 22 has a conical outer surface 24 tapering in a direction from the flange 30 toward the end 25. An outer circumference of the flange 30 forms or constitutes a maximum outer diameter of the activation piece 12. End 25 has a radially extending surface 38 which lies in a plane perpendicular to a longitudinal axis of the hole 20. The conical surface 24 extends from a radial outer edge of the surface 38 to one end of the cylindrical surface 26. The cylindrical surface 26 extends axially with constant diameter to one end of the second cylindrical surface 28 at which there is a stepped increase in outer diameter. This forms a circumferential shoulder 29 about the activation piece 12. Flange 30 has an outer circumferential surface 34 which transitions to a radially extending surface 40 at the end 27. An underside wall 32 of flange 30 is countersunk or rebated to incline toward end 27 in a radial inward direction.

The sleeve 14 has an axial hole 48 with longitudinal axis concentric with that of hole 20 when sleeve 14 is mounted or received on activation piece 12. Sleeve 14 comprises a concentric cylindrical portion 50 having constant (but different) inner and outer diameter and a plurality, in this case four, of axially extending finger-like section 54, which comprise an expandable portion 52. It is envisaged that other numbers of sections may be employed, such as eight, ten, twelve or more. Each section 54 extends in a circumferential direction for about ninety degrees, i.e. a quarter circle. An end of sleeve 14 distant the portion 50 has a dish-shaped substantially radially extending surface 68, which is formed by the end surfaces of the sections 54. The sections 54 are separated by longitudinal slits 56. When there are more than four sections 54, each section will extend circumferentially for about x° where x = 360/number of sections. Thus for eight sections x° = 360/8 = 45°.

An inside surface of hole 48 comprises a surface portion 55 of the concentric portion 50 which is of constant inner diameter and a contiguous portion 57 of reducing inner diameter in a direction away from the cylindrical portion 50.

Portion 57 comprises: a first inside wall surface 58 which is contiguous with the surface portion 55 and sequentially contiguous, second inside wall surface 60, and third inside wall surface 62. The opening angle of each of the wall surfaces 58, 60 and 62 is progressively larger. The opening angle is an angle from an axially extending line to the surface, for example as illustrated by β Fig. 2. This means that the surface portion 57 tends to narrow at a greater rate with respect to distance through the length of the hole 48 in a direction from portion 50 to the end surface 68. The surfaces 55, 58, 60, and 62 are shaped so as to interact with the surfaces 24, 26 and 28 as described further below.

The largest internal diameter of the wall surface 62 is smaller than the smallest diameter of the surface 24. The surface 60 is shaped similarly to the corresponding surface 24, although it has a slightly larger opening angle and is slightly longer. The largest diameter of the surface 60 is larger than the largest diameter of the surface 24 and larger than the diameter of the surface 26. The largest diameter of the surface 60 is slightly smaller than the diameter of the surface 28. The largest diameter of the surface 58 is substantially the same as the diameter of the surface 28. The inner diameter of surface 55 is substantially the same as the outer diameter of surface 28.

The sleeve 14 has an end surface 70 at an end opposite surface 68. The cylindrical portion 50 has an outer diameter 74 substantially the same as the diameter of the surface 34. Thus the activation piece 12 and the sleeve 14 have the same maximum outer diameter prior to the sleeve 14 being expanded by the activation piece 14. Each of the sections 54 has an outer surface profiled so as to comprise a conically shaped portion 76 with increasing outer diameter extending from the surface 68 toward end surface 70, a substantially radially extending engagement surface or shoulder 72 and a substantially cylindrical surface 78 of the same diameter as the outer diameter of the cylindrical surface 74. The sections 54 are comprised of a material which will flex when the activation piece 12 wedges the inside surface 62 apart so as to expand the expandable portion 52, which radially moves the engagement surface or shoulder 72. The location of the shoulder 72 when viewed in the axial direction is near the transition between inside surfaces 60 and 62. As explained below the shoulder or engagement surface 72 abuts a face adjacent the hole of an object in a plane substantially perpendicular to an axis of hole in the object through which the retainer 10 is passed.

Referring to Figs. 4 and 5, a bolt 100 is used in corporation with the retainer 10 so as to fasten one or more objects together. In this case the objects are a wear plate 130 and a support structure 140. Wear plate 130 has a hole 131 formed with a conical interior surface 132. The support structure 140 has a hole 143 formed with a cylindrical interior surface 144. The holes 131 and 143 are concentric and may be considered as together forming an extended hole. Bolt 100 has a circular head 102 and interfaces with the conical surface 132 by a recessed washer-like device 120. The device 120 comprises a conical outer circumferential surface 124 tapered at an angle complimentary to that of surface 132, a central recess 125 of constant inner diameter extending from a large diameter end of the surface 124, and a radial inwardly extending wall 122 near a small diameter end of the surface124. Head 102 sits within the recess 125 with a radially extending surface 110 of the head 102 abutting the wall 122. Bolt 100 is formed with a hexagonal hole 108 in which an Allen key can be inserted for turning the bolt 100. The outer conical surface 124 of washer-like device 120 is able to transfer force applied by bolt 100 in an axial direction against the wall 122 to the conical surface 132 of wear plate 130.

The retainer 10 is dimensioned so that the flange 30, and the surface 74 will fit through the hole 143 of the structure 140. A treaded shank 104 of the bolt 100 may be loosely engaged with the internal thread 36, or the retainer 10 may be inserted (without the bolt 100) and then the bolt 100 screwed in place. As the bolt 100 is wound it will draw the activation piece 12 towards the head 102. In doing so, the conical surface 76 will be drawn inside hole 143. As the activation piece 12 continues to be drawn towards the head 102, the wedge portion 22 will come up against the inside of, and begin to expand the expandable portion 52. In particular, surface 24 will spread the sections 54 apart. As this occurs the engagement surface 72 will move substantially radially and will be drawn towards and eventually abut a surface 142 of the support structure 140. The surface 142 lies in a plane perpendicular to respective axes of holes 131 and 143, and moreover is the rear face of a last of the objects (in this case the support structure 140) through which the retainer 10 is passed reference prior to coupling with bolt 100. Further, end surface 70 will abut the countersunk surface 32. Finally the conical surface 76 will contact inside surface 144. Surface 60 may remain substantially clear of surface 26. The expandable portion is shown expanded as 52' in Fig. 4.

As bolt 100 is tightened, surface 110 in combination with surface 72 provides a clamping action therebewteen, which includes the washer-like device 120, the wear plate 130 and the support structure 140.

The sections 54 can be biased so as to interfere with the inside surface 144 in order to provide sufficient friction, possibly with the assistance of a friction aiding or adhesive agent so as to prevent the sleeve 14 from rotating when the bolt 100 is tightened. Further the surfaces 55 and 28 may have an interference which prevents the activation piece from rotating as the bolt 100 is tightened. In addition or alternately the conical portion 76 and surface 144 may be provided with complementary splines and grooves that engage to prevent relative rotation. The surfaces 55 and 28 may be similarly configured.

A fastener comprising the bolt 100 and an embodiment of the retainer 10 is thus able to be inserted through one side of the objects to be fastened without there being need to access the other side. The fastener can then be tightened resulting in the expandable portion expanding outwardly and the engagement surface 72 being forced against the surface 142 thereby providing a clamping like action between the retainer 10 and the head 62 of the bolt 100.

The clamping action may be sufficient to draw the structure 140 and plate 130 together if they are not in contact, such as may be the case if the structure 140 was buckled.

If the bolt 100 is removed either by unscrewing, or by drilling it out, the activation piece 12 can be allowed to move back away from the sleeve 14, so as to allow the expanded expandable portion 52 to relax and contract, thereby reducing the outer diameter of the retainer allowing it to be pulled through the hole and be removed.

Now that an embodiment of the retainer 10 and associated fastener have been described in detail it will be apparent to those skilled in the art that numerous modifications and variations may be made without departing for the basic inventive concepts. For example a severable thread or tape made from cotton, or a plastics material may loosely tie the components 12 and 14 together to facilitate the insertion of the retainer 10 through the holes 131 and 143 without them totally separating. Such a thread can be cut by screwing bolt 100 into the 20. In a further variation the head 102 and washer like device 120 can be formed a single integral unit. This can be achieved for example by machining the head 102 to have an outer circumferential surface of the same shape as the device 120. In such a variation the head 102 can also be formed of a axial length the same as that of the hole 131 so that an upper surface of the head 102 will remain substantially flush with the a free face of plate 130 irrespective of the amount of rotation of bolt 100 required to tighten the fastener. Further the engagement surface or shoulder 72 is shown as a continuous circumferential shoulder. However this may be in the form of one or more circumferentially spaced shoulders, for example there may be four shoulders each extending circumferentially for sixty degrees with adjacent shoulders spaced by thirty degrees; or say six shoulders each extending circumferentially for thirty degrees with adjacent shoulders spaced by thirty degrees. All such modifications and variations together with outers that would be obvious to a skilled addressee are intended to be within the scope for the present invention, the nature of which is to be determined from the above description and the appended claims.