Until recently, members such as panels were joined using an adhesive by first coating one or both of the facing surfaces of the panels with the adhesive and then bringing the two panels together and holding them in place until the adhesive set. This requires that the members are handled with the adhesive already provided on the surfaces which is undesirable. Recently, in US-A-5830308, a method was proposed in which the panels are held together using double-sided adhesive tape and then the adhesive injected through an aperture in one of the panels. This also is undesirable in view of the need to handle double-sided adhesive tape and the requirement to provide an additional aperture for injecting the adhesive.

Various techniques have been disclosed in the past for using a fastener as a conduit for an adhesive or sealant.

Examples are described in EP-A-0082248 and GB-A-188708.

However, these rely on the presence of pre-formed grooves or slots in the members to be joined and into which the adhesive/sealant is injected. This is undesirable because of the need for special forms of members to be joined.

In accordance with one aspect of the present invention, a fastener comprises a fastener comprising a connection assembly including an elongate member having first and second sections for locating in respective aligned bores in respective first and second members to be joined together; and a spacer for causing the two members to be held in a spaced apart condition wherein the connection assembly limits movement of the first and second members away from each other and includes means to allow material to be injected between the members.

In accordance with a second aspect of the present invention, a method of joining first and second members

comprises inserting a fastener according to the first aspect of the present invention into aligned bores in the members; and injecting material between the members.

We have devised a triple function fastener which considerably simplifies the joining of members such as panels and the like. Firstly, the fastener accurately locates the two members relative to each other and holds them together before, during and after material injection.

Secondly, and importantly, the fastener controls and introduces the spacing between the two members. Thirdly, the fastener facilitates injection of material between the two members.

A variety of fasteners can be constructed in accordance with the invention.

In the preferred examples, the elongate member is a single, integrally formed piece although in other embodiments it could be formed by one or more pieces which are joined together, for example by being mutually screw threaded.

At least one of the first and second sections of the elongate member may be externally screw threaded. If the external screw thread is a self-tapping thread then it can be screwed directly into a bore of one of the members to be joined, for example if that member is made of a metal. In order to be able to join other materials, however, preferably the connection assembly includes, for each externally screw threaded section of the elongate member, an internally screw threaded insert having a laterally extending flange for engaging the associated member to be joined.

In several cases, it is necessary to gain access to both sides of the two members to be joined together.

Sometimes, this is not practical and therefore in other embodiments, the second section may have an expandable portion to lock into the bore of the second member. This could be achieved, for example, by providing a plug which is an interference fit in a bore in the elongate member,

the plug being pulled axially along the elongate member once it is inserted in the bore of the second member so as to cause the adjacent part of the elongate member to expand radially and lock into the bore. The plug can then be left in place to prevent escape of adhesive.

Conveniently, the means to allow material to be injected between the members includes a bore extending from one end of the elongate member at least to an aperture extending through the wall of the elongate member which will communicate in use with the space between the first and second members to be joined.

This provides a very convenient way of injecting material into the space between the members to be joined by using the same fastener to provide the supply path as is used to hold the members together.

Alternatively a groove or flattened exterior part of the elongate member can also provide a supply path to allow material to be injected.

Although a single aperture could be provided through the wall of the elongate member, preferably a plurality of apertures are provided which may be substantially equally circumferentially spaced and/or axially offset from one another.

The material to be injected could be an adhesive, sealant, non-hardenable liquid or gas.

The spacer preferably forms part of the elongate member. For example, it could be provided by a number of laterally extending flanges or fins, or a collapsible section of the elongate member. In another example, the spacer may comprise an expandable member which can be inserted through the bore in the first member and then laterally expanded between the first and second members.

In an alternative approach, where an insert is used as described above, the spacer may form part of the insert.

Further, the spacer could be formed by a suitably shaped washer or the like to allow adhesive to pass through or around via channels, pores or the like.

In some cases a spacer is not required. Thus in accordance with a third aspect of the present invention, a method of joining members comprises inserting an elongate member of a fastener into aligned bores of the members, the fastener allowing limited movement of the members away from one another; and injecting material between the members.

Typical materials for the fastener include aluminum alloys as well as other metals, plastics, composites etc.

The materials to be joined could be of any appropriate material including metal, fibre reinforced composite, plastic, wood etc.

Injection of the material could be facilitated in a number of ways including hand gun, compressed air assisted machinery or robotic equipment or other well known methods.

Some examples of fasteners in accordance with the present invention will now be described with reference to the accompanying drawings, in which:- Figure 1 is an exploded view of a first example of a fastener; Figures 2A-2C are cross-sections through a modified form of the first example shown in Figure 1; Figure 3 is a schematic cross-section through part of a modified form of the fastener shown in Figure 2; Figure 4 is a cross-section and a section on a line A-A of a second example; Figures 5A and 5B are a cross-section and exploded view of a modified form of the second example; Figure 6 is a cross-section through a further modified form of the Figure 4 example; Figure 7 is a view similar to Figure 4 but of a third example; Figures 8A and 8B are cross-sections through a modified form of the Figure 8 example; Figure 9 is a view similar to Figure 4 but of a fourth example; Figure 10 illustrates a fifth example with a floating spacer washer;

Figure 11 illustrates a sixth example; Figures 12A-12D illustrate different types of washer for use in the Figure 10 or Figure 11 examples; and, Figures 13A and 13B illustrate a seventh example in two different conditions.

Figure 1 illustrates in exploded form a first example of a fastener for joining two substrates 1,2. The fastener is in four parts, including an elongate, central member 3 having a first section 4 which is externally screw threaded at 5 and a second section 6 which is externally screw threaded at 7. Four radially extending flanges 8 (only two shown in Figure 1) are integrally formed with the central member 3 and extend laterally between the substrates 1,2.

The central member 3 also has an internally screw threaded blind bore 9 extending through the first section 4 and communicating with a number of apertures 10 extending through the wall of the central member 3. The apertures 10 are aligned with spaces between the flanges 8.

The fastener shown in Figure 1 also includes a lower insert 11 having an internally screw threaded spigot 12 and an integral, laterally extending flange 13. The spigot 12 defines an internal blind bore 14.

An upper insert 16 is similar to the insert 11 and has an internally screw threaded spigot 17 integrally formed with a laterally outwardly extending flange 18. In this case, however, the bore 19 defined by the spigot 17 is open at both ends.

Finally, an externally screw threaded bolt 19 is provided to close the bore 9.

In use, a pair of recesses 20,21 are machined in the substrates 2,1 respectively of a size to receive the flanges 13,18 of the inserts 11,16. Bores 22,23 are then drilled through the substrates 1,2.

The spigot 12 of the insert 11 is pushed into the bore 23 of the substrate 2 where it can either be bonded or be held in place as an interference fit or simply by hand.

The central member 3 is then located between the substrates 1,2 and the lower section 6 is screwed into the bore 14 of the spigot 12. The flanges 8 come to lie against a surface 24 of the substrate 2 while the flange 13 is locked into engagement with a surface 25 of the recess 20.

The insert 16 is then located in the bore 22 of the substrate 1 and is screwed onto the upper section 4 of the central member 3. The substrate 1 is thus clamped between the flange 18 and the flanges 8.

At this stage, liquid adhesive is injected through the bore 9 and out through the apertures 10 into the space between the substrates 1,2, the space having a thickness corresponding to that of the flanges 8. Following injection of the adhesive, the bolt 19 is screwed into the bore 9 to close it and the adhesive allowed to cure so as to bond the substrates 1,2 together.

Figures 2A-2C illustrate a second example of a fastener which has a very similar construction to that shown in Figure 1. Each of Figures 2A-2C are longitudinal sections taken at different circumferential positions about the central axis. Those components corresponding to components shown in Figure 1 are given the same reference numeral but with the addition of a"'". In contrast to Figure 1, the spigots 12', 17'do not extend fully through the respective bores 23,22 leaving spaces 30,31 at their axially inner ends. Furthermore, the central member 3', as well as having four laterally extending fins 8'has eight apertures extending through its wall, four of which can be seen in Figures 2B and 2C at 32,33. It will be seen that the apertures 32 are axially offset towards the substrate 1 while the apertures 33 are axially offset towards the substrate 2. However, due to the presence of the spaces 30,31, adhesive injected into the bore 9'can pass out through the apertures 32,33 into the space 34 between the substrates 1,2.

It will be noted in Figures 1 and 2 that in order to locate the fastener in position, it is necessary to have access to both sides of the substrates 1,2. This is not essential, however, since a modified form of central member 35 could be used (Figure 3). This member 35 has an upper, externally and internally screw threaded section 36 (as before) and four laterally extending flanges 37. However, the member 35 is also open ended at its lower end 38 and a plug 39 is located in the lower end 38 as an interference fit. The plug is connected to a pulling member 40. The member 35 can be inserted into the bore 23 of the second substrate 2 from the side of the first substrate without access being needed to the other side of the substrate 2.

Once inserted, the member 40 is pulled upwardly causing corresponding upward movement of the plug 39 which in turn forces the lower wall of the member 35 outwardly and into engagement with the surrounding bore into which it is then locked. The member 40 is then detached from the plug 39 (e. g. by shearing) and removed.

In another modification (not shown) the insert 11 could be omitted if a self-tapping screw thread is provided on the lower section of the central member 3 and the substrate 2 is of a material suitable for receiving such a screw thread.

Figure 4 illustrates a fastener which minimizes the use of screw threads. In this case, a wide bore 50 is first drilled in the substrate 1 and an insert 51 is pushed into the bore 50 from the underside of the substrate 1.

The insert 51 has four laterally extending fins 52 integrally formed with it. The insert 51 is typically an interference fit in the bore 50 and is fully inserted to bring the fins 52 into engagement with the underside of the substrate 1.

The two substrates 1,2 are then brought together, the fins 52 defining a space 59 between the substrate, a drill is inserted through a bore 53 defined by the insert 51, and a bore 54 is drilled in the lower substrate 2.

An internally screw threaded central member 55 is then inserted through the bore 53 and the bore 54, the central member having a flange 56 which rests against an outer surface 57 of the substrate 1. The central member 55 also has a set of four laterally extending apertures 58 which communicate with the space 59 defined between the substrates 1,2.

A bolt 63 is then screwed to a lower section 60 of the central member 55, a washer 61 being provided between the bolt head and the lower surface of the substrate 2. The substrate 2 is thus clamped in place without the need for a lower insert as in the first example.

Adhesive is then supplied through a central bore 62 of the central member 55, the adhesive passing out through the apertures 58 into the space 59 as before.

Finally, the bolt 64 is screwed into the upper section of the central member 55 to retain the adhesive in place while it cures.

It will be readily apparent that a number of variations of this fastener are possible. For example, the fins 52 could be bonded to the upper surface of the substrate 2.

Figures 5A and 5B illustrate a further modification of the Figure 4 example. In this case, an internally screw threaded upper insert 70 having laterally extending upper and lower flanges 71,72 is located in a bore 73 of the first member 1. Either the insert 70 or the substrate 1 will need to be deformable by a sufficient amount to allow the insert 70 to be inserted. A lower insert 74 having a flange 75 is inserted in to a bore 76 having the same diameter as the bore 73. Both inserts 70,74 are internally screw threaded and receive an externally screw threaded central member 77 having a blind bore 78. The central member 77 has four apertures 79 aligned with spaces between the flanges 72.

Figure 6 illustrates a modification of the Figure 5 embodiment in which the central member 80 has an upper

section 81 which has a larger radial dimension than its lower section 82. This is assembled by first drilling the bore 73 in the substrate 1 and inserting the insert 70.

The lower bore 76 is then drilled and fitted with the insert 74 following which the central section 80 is inserted.

Figure 7 illustrates a further embodiment of a fastener. In this case, a bore 90 is drilled in the upper substrate 1 and a bore 91 having a narrower diameter in the lower substrate 2. This could be achieved using a special drill bit or in separate drilling stages. An insert 92 is then located in the bore 90 either as an interference fit or by bonding (or by using an external self-tapping screw thread if appropriate) and a central member 93 is screwed into the insert 92. The central member 93 has an upper section 94 with a relatively wide diameter and a lower section 95 having a narrower diameter corresponding to that of the bore 91. The step 96 is formed between the upper and lower sections 94,95 which engages against an upper surface 98 of the substrate 2. It will be seen therefore that the amount by which the central member 93 is screwed into the insert 92 will determine the spacing 59 between the substrates 1,2.

The central member 93 has a set of four laterally extending apertures 99 which communicate with the space 59 and with a central bore 100. The lower end of the central bore 100 is closed by a bolt 101 engaging against a washer 102 which in turn engages against a lower surface 103 of the substrate 2.

Adhesive is supplied into the bore 100 and out through the apertures 99 into the space 59 and then the bore 100 is closed by a further bolt 104.

In the Figure 7 example, access is needed to both sides of the substrates 1,2 to locate the fastener. Figure 8 illustrates a modified form of the Figure 7 example in which access is only required to the upper surface of the substrate 1. In this case, the central member 93'has a

lower section 95'which can be bent laterally outwardly to lock into the bore 91. Initially, the bores 90,91 are drilled and an insert 92 is located in the bore 90, in this case with the outer flange flush with the outer surface of the substrate 1. The central member 93'together with a plug 105 coupled to a pulling member 106 is inserted into the insert 92 with its lower portion entering the bore 91.

At this stage, the substrates 1,2 will be in contact with one another as shown in Figure 8A. Continued rotation of the insert 93'will then cause the substrates 1,2 to separate. Once the required degree of separation is achieved (Figure 8B), the plug 105 is pulled via the pulling member 106 into the bore 100 of the central member 93'causing the lower section 95'to splay outwardly and lock into the bore 91. The plug 105 remains in place as a plug so that adhesive is forced laterally outwardly through apertures 99 into the space 59.

The fasteners described up to now have had three functions, namely to prevent the members separating, to hold the members in a spaced apart condition, and to provide a means for conveying adhesive into the space between the members.

The invention is also applicable to a dual function fastener as shown, for example, in Figure 9. In this case, the fastener comprises a central member 110 which is inserted into aligned bores 111,112 in the members 1,2. A plug 113 is located in one end of a bore 114 of the member 110 and once the member 110 has been inserted into the bore 112, the plug is drawn upwardly causing the wall of the member 110 to expand into engagement with the wall of the bore 112 so as to hold the member in place. Under this condition, it will be seen that a flange 115 of the member 110 is spaced from the top surface of the member 1.

The edges of the junction between the members 1,2 may be sealed by means (not shown) which allows movement of the member 1 relative to the member 2.

Adhesive or sealant is then injected through the bore 114 and out through apertures 116 between the members 1,2 and this will cause the members to separate. In particular, the member 1 rising up until it engages the underside of the flange 115.

The bore 114 can be sealed as in the previous examples.

Figure 10 illustrates an example of a fastener having an elongate, externally screw-threaded member 150 along the centre of which extends a blind bore 155. A nut 160 is threaded onto the screw-thread of the member 150. A floating spacer washer 165 is mounted loosely about the member 150. In use, the member 150 is inserted through a bore of a first substrate (not shown), the washer 165 is then threaded onto the member 150 followed by the second substrate and finally the nut 160. The substrates will be held together by virtue of their engagement with a shoulder 170 at one end of the member 150 and the nut 160 and will be maintained spaced apart by means of the washer 165. The blind bore 155 communicates with a number of radially outwardly extending bores 175 in the wall of the member 150 which, in use, will be aligned with the space defined by the washer 165 so that adhesive or sealant can be injected through the opening of the bore 155 and then out through the bores 175.

Figure 11 illustrates a modification of the Figure 10 example in which the bore 155 opens at 157 into four circumferentially spaced grooves 180 extending along the surface of the member 150 so that adhesive will pass immediately out from the bore 155 into the grooves 180 and then down into the space between the two substrates held apart by the spacer 185. In this case, the spacer 185 has a number of radially outwardly extending grooves 190 for conveying adhesive into the space between the substrates.

Figure 12A illustrates the spacer 185 in more detail while Figure 12B illustrates the spacer washer 165 in more detail and as can be seen this has a number of axially

extending stubs 195. Further alternatives for the spacer or washer are shown in Figure 12C where the spacer has a wave profile and in Figure 12D where it is in the form of a porous sponge.

Finally, in Figure 13, a collapsible form of fastener is shown. In this case, the fastener comprises an elongate member 200 having a collapsible section 205 formed by four relatively thin, elongate sections 210 hinged at their mid- points 211. The end 212 of the member 200 is screw- threaded and receives a nut 213. As before, the fastener is inserted through aligned bores in the substrates to be joined while in the condition shown in Figure 13A. The nut 213 is then tightened causing the portions 210 to bend about the hinges 211 so as to form a set of four radially extending vanes 215 (Figure 13B) which act as spacers.

Adhesive is then injected through a blind bore 155 and exits through vent ports 220.