WO1997045647A1

WO1997045647A1 - Connector

Info

Publication number: WO1997045647A1
Application number: PCT/GB1997/001463
Authority: WO
Inventors: Luke Richard John Whale; Julian Philip Marcroft
Original assignee: Gang-Nail Systems Limited
Priority date: 1996-05-29
Filing date: 1997-05-29
Publication date: 1997-12-04
Also published as: GB9611135D0; ZA974731B; AU2969997A

Abstract

The invention relates to a connector, particularly but not exclusively to connectors used in the construction of wooden trusses or laminated wooden beams for use in the construction industry. The invention provides a connector (10) for joining timber components comprising two nail plates (1, 3), each nail plate (1, 3) having a plate member (2, 4) and a plurality of nail members (6, 8) pressed from the plate member (2, 4) so as to extend generally outwardly therefrom and extending through a plurality of holes (16, 18) present in the other respective plate member (2, 4). At least one protrusion (22, 24) is provided on a plurality of the nail members (6, 8) for retaining the nail plates (1, 3) together in an interlocking manner. The or each protrusion (22, 24) is shaped so as to allow the nail members (6, 8) to pass through the holes (16, 18) without any significant deformation occuring and to allow the or each protrusion (22, 24) to overlie a part of the other respective plate member (2, 4) when the nail plates (1, 3) are translated with respect to one another.

Description

Connector

The invention relates to a connector, particularly but not exclusively to a connector used in the construction of wooden trusses or laminated wooden beams for use in the construction industry.

Wooden trusses are constructed from a plurality of timber components which are connected so as to form a rigid structure. It is well known that the individual timber components may be connected together using bolts or nails. However, the construction of wooden trusses in this manner is relatively time consuming and expensive. For this reason, a more economical method of construction is now widely used which provides a rigid connection between abutting timber components through the use of nail plate connectors. These connectors are substantially planar plates of metal out of which have been pressed a plurality of nail-like projections such that the projections extend substantially perpendicular to the plane of the plate itself. Commonly, the projections extend over substantially the entire area of the plate and are arranged in rows. A rigid connection between the timber components is made by pressing nail plate connectors into opposite sides of the timber components so as to bridge the interface therebetween. The connection thereby made is extremely effective at transmitting shear and axial forces because of the large number of nail members penetrating each timber component. The connection is also made relatively quickly and inexpensively because a plurality of nail members may be pressed into the timber components in a single automated action using readily available pressing machinery. Furthermore, the nail plate connectors are themselves relatively quick and inexpensive to manufacture because the nail members are pressed out of the metal plates from which they extend by means of a simple pressing action.

However, individual bolts or nails have one principal advantage over nail plate connectors. In the former case, each bolt or nail is located almost entirely within the wood of the truss. Only the ends of each bolt or nail are generally exposed and are often recessed so as to be unobtrusive The resulting w ooden truss comprises connections between umber components vv hich aie both aesthetically pleasing and relatively resistant to fire damage Howev er. the connections made by nail plate connectors are generally unattractive and susceptible to fire damage This is because the metal plates ot such connectors he on the extenoi surtace ot the connected timber components Buildings containing wooden trusses constructed using nail plate connectors generally only satisfy standard fire safety requirements provided that the metal plates of the connectors are protected from exposure to fire Such protection is often afforded by the ceiling construction of a building However, in certain circumstances it can be desirable to omit the ceiling panels of a building so as to expose the roof structure of the building The wooden trusses composing such a roof structure thereby become an aesthetic architectural feature The poor aesthetic and fire resisting characteristics of wooden trusses constructed with nail plate connectors generally prevent such trusses from being exposed in this manner The aesthetic and fire resistmg characteristics of connections made with nail plate connectors can be improved by covering the metal plate of each connector with a suitable material, however, this is expensive

It is also known that certain types of connector may be located between the mating surfaces of timber components The connector is thereby concealed, thus providing a connection with good aesthetic and fire resistmg characteristics Sev eral types of concealed connector are currently known A first type of concealed connector composes a plurality of metal tooth members disposed around the circumference of a metal plate The tooth members may extend from both sides of the metal plate so as to form a double-sided toothed-plate connector or from one side of the metal plate so as to form a single sided toothed-plate connector The principal problem with this type of connector is mat the tooth members are only disposed around the circumference of the metal plate and not across the central area thereof The number of tooth members extending from the metal plate is therefore small and, consequently, the ability of the connector to transmit shear forces is relatively poor The tooth members also have a tendency to distort if the connector is not aligned accurately A second type of known concealed connector comprises a plurality of double- ended metal nail members which are held in an array by a plastics member. The connector is manufactured by pushing individual metal nail members through the plastics member so that one half of each nail member extends from each face of the member. The pπncipal problem with this type of connector is that the nail members are not rigidly attached to the plastics member and are free to move along their longitudinal axes. Consequently, the nail members tend to penetrate further into the timber component made of the softer material rather than penetrate each timber component equally This results in relatively weak and unreliable connections being provided.

Further types of concealed connector are the spht-πng connector and the shear- plate connector. Both these connectors have the ability to transmit high shear forces though this can be limited for shear planes needing more than one connector by onerous spacing rules. However, both connectors also have the disadvantage of requiring a recess or groove in the mating surfaces of the timber components to be connected. This groove must be cut into each mating surface prior to the connecting of the timber components which is time-consuming and expensive.

It has also been proposed to provide nail plates having nail members projecting from both sides of the plate member. This can be achieved by pressing nails in opposite directions from the same plate, but manufacture of such a connector is difficult or expensive. Single-sided nail plates can be welded together "back to back", but there is some πsk that the plates will come apart under loading which should be carried. Also, the welding process would affect the galvanising of the individual nail plates and necessitate a second galvanisation process.

UK patent No. 1287739 and US patent No. 44861 15 each disclose a double- sided nail plate made up of two single-sided nail plates having additional slots provided so mat the nails of each plate can pass through the slots of the other plate and project beyond mat other plate. This arrangement provides a strong connector, but has the disadvantage that the array of nails must be sufficiently spaced to allow the slots to be provided between the nails. The density of nails is therefore limited.

This disadvantage is overcome by the connector disclosed in EP 0481941 A in which the nail members of one plate pass through the openings in the second plate left by the punching ol the nails therefrom In this arrangement, the nail plates are held together by friction alter the nails hav e been forced through the openings How ev er. this inevitably means that there is a risk of the plates bemg torn apart if sufficient force is applied Furthermore, the openings mav be deformed duπng the introduction of the nails into the openmgs which may distoπ the connector

It is an object of the present inv ention to prov ide a connector which overcomes the disadvantages mentioned above and still allows the connection of timber components in a quick and inexpensiv e manner

It is also an object of the present inv ention to provide a connector capable of making a v erv πgid and reliable connection between timber components

The invention prov ides a connector as set out in claim 1 Further and advantageous features are set out in the subsidiary claims

The connector of the present invention has a number of advantages over the relevant pπor an The invention provides a connector which allows a reliable connection between umber components to be made more quickly and with less expense than is possible with conventional bolts, nails or connectors The connector of the present invention may also be manufactured both quickly and inexpensively usmg similar production techniques to those used m the manufacture of conventional nail plate connectors Furthermore, the connections made by the method of the present invention also have the ability to transmit high shear and axial forces as well as to withstand tension forces

Embodiments of the present inv ention will now be descπbed with reference to the accompanying drawings in which

Figure 1 is a side view of a connector according to a first embodiment of the invention.

Figure 2 is a plan view of the connector of Figure 1 ,

Figure 3 is an exploded view of a portion of the connector of Figure 1.

Figure 4 is a perspective view of a portion of the connector of Figure 1 ,

Figure 5 is a perspective view of a portion of a connector according to a second embodiment of the invention, Figure 6 is a side v lew of a joint in which two connectors according to the first embodiment of the invention hav e been used to connect three timber components;

Figure 7 is an end v lew of the joint of Figure 6; and

Figure 8 is a side v iew of a lapped joint in which one connector according to the first embodiment of the inv ention has been used to connect two timber components.

Figures 1. 2. 3. and 4 show a first embodiment of a connector according to the present inv enuon which composes an upper plate member 2 and a lower plate member 4 from each of which a plurality of nail members 6.8 are respectively pressed. Upper plate member 2 and nail members 6 define a first nail plate 1 and lower plate member 4 and mail members 8 define a second nail plate 3. The first and second nail plates 1 ,3 collectively define a double-sided nail plate connector 10

The nail plates 1.3 of the connector 10 are manufactured separately and have substantially the same geometry. Figures 1 and 2 show that the nail members 6,8 are arranged in rows and columns disposed across the faces 30.32 of the respective plate members 2.4. Figure 3 shows on an enlarged scale one of each of the nail members 6.8. Each of the nail members 6.8 is pressed so as to be of the same general shape and size, and so as to extend from the respective faces 12, 14 at approximately the same angle Each nail member 6.8 has opposing protrusions 22.24 extending outwardly therefrom and are formed dunng the pressing action by which the nails 6,8 are formed. The nail members 6.8 of the first embodiment are pressed so that they extend substantially perpendicularly from the respective faces 12.14. The precise shape, size and density of the nail members 6.8 can be made dependent upon the nature of the connection to be made. The pressing of the plurality of nail members 6,8 defines a plurality of holes 16.18 respectively. The holes. 16, 18 in each plate member 2,4 are of the same general shape and size and will be dictated by the shape of the nail members 6.8.

Figure 3 shows that the similarity between the nail plates 1.3 allows the nail members 6,8 of one nail plate to extend through the holes 16, 18 of the other respective nail plate. The connector 10 is assembled by pressing together ϋhe upper nail plate 1 and the lower nail plate 3 so that the faces 12.14 abut each other and each nail member 6,8 extends through a hole 18.16 in the opposite plate member so as to project beyond the face 32.30 opposite plate member. The resultant connector is then made up of a central member (formed from the two plate members) with nail members extending from both faces. The plate members 2.4 are rigidly retained adjacent one another by locating the nail members 6.8 in a non-retractable position. Figure 4 shows on an enlarged scale one of each of the nail members 6.8 located in the non-retractable position.

Figure 3 illustrates the assembly of the connector 10. The nail members 6.8 are first pressed through the broader portions 26.28 of the respective holes 16, 18 formed by the pressing of the protrusions 22.24 so that the faces 12.14 abut each other. The plate members 2.4 are then slid relative to one another so as to locate the nail members 6.8 in their non-retractable position, see arrow A. This method does not deform the plate members 2.4 or projections 22.24 and. therefore, provides a rigid attachment. The plate members 2.4 locate adjacent one another so as to define a central member 20. One or more bolt holes may also be prov ided in the central member 20 as necessary. These bolt holes may receive suitable bolts so as to reinforce the connection made by the connector 10. However, the use of such bolts is not essential to the formation of a strong connection.

The means for retaining the plate members 2.4 adjacent one another is provided by the protrusions 22.24 located on the nail members 6,8 respectively. The protrusions 22.24 provide an interference fit between the nail members 6,8 and the sides of the holes 18.16 respectiv ely.

The plate members 2.4 may also be retained adjacent one another by protrusions of a different nature to those shown in Figures 3 and 4. Figure 5 shows a second embodiment of the present invention which differs from the first embodiment in respect of the shape of the protrusions 22.24 located on the nail members 6,8. In each case the protrusions abut the faces 30.32 of the plate members 2,4 respectively so as to prevent the plate members 2.4 from separating.

Figure 5 shows a protrusion defining a key tooth 36. The key tooth 36 is shaped so as to easily pass through the broader portion 26 of the hole 16. The embodiment shown in Figure 5 is assembled by pressing the nail members 6,8 into their non- retractable positions as indicated by arrow B. Both of the embodiments descπbed above may be manufactured from metallic mateπals using production techniques such as pressing that will be known to a reader skilled in the an The nail members of a connector according to the invention may be pressed so that they extend from the central member of the connector at an angle other than ninety degrees However, it is preferable that the nail members extend from each face of the central member in opposing directions such that their longitudinal axes he parallel to one another This arrangement allows a connection between timber components to be made in a single action by simply pushing the timber components together in a direction parallel to the longitudinal axes of the nail members

Figures 6 and 7 show a joint 44 composing timber components 40.42,43 and two double-sided nail plate connectors 10.10' according to the first embodiment of the invention The connector 10 lies between matmg surfaces 48,46 of the timber components 40.42 respectively The connector 10' lies between matmg surfaces 47,45 of the timber components 40.43 respectively The connectors 10, 10' lie between the pairs of timber components 40.42 and 40,43 respectively so that they are each concealed within the joint 44 The plurality of nail members 6,8 and 6'.8' penetrate the timber components 40,42 and 40.43 respectively A joint capable of transmitting high shear and axial forces is thereby provided A bolt 50 extends through bolt holes in the timber components 40,42.43 and a bolt hole in the connectors 10, 10' The bolt 50 prov ides an additional safeguard against the timber components 40.42.43 being pulled apart and also gives the joint 44 the pleasing and reassuring appearance of a joint constructed usmg conventional techniques However, the inclusion of the bolt 50 is not essential to the construction of the joint 44

In the construction of a wooden truss, jomts compnsing three timber components will be made with the most frequency However, jomts compnsing two timber components will also be made Figure 8 shows a double-sided nail plate connector 10 according to the first embodiment of the invention connecting timber components 52,54 to form a lapped joint 55 The connector 10 lies between matmg surfaces 56,58 of the timber components 52.54 and provides a connection therebetween as descπbed above with regard to the joint 44 The connectors and methods of connecting timber components descπbed above are applicable to the construction of wooden lammated beams as well as to the construction of wooden trusses.

The present invention is not limited to the specific embodiments or method described above. Alternative arrangements and suitable materials will be apparent to a reader skilled in the art.

Claims

1 A connector for joining timber components comprising two nail plates, each nail plate having a plate member and a plurality of nail members pressed from the plate member so as to extend generally outwardly therefrom, die nail members of each nail plate extending through a plurality of holes formed by the pressing of the nail members from the other respective plate member, and at least one protrusion being provided on a plurality of the nail members for retaining the nail plates together in an interlocking manner, wherein the or each protrusion is shaped so as to allow the nail members to pass through the holes without any significant deformation occurring and to allow the or each protrusion to overlie a pan of the other respective plate member when the nail plates are translated with respect to one another.

2. A connector as claimed in claim 1. wherein the nail members extend substantially perpendicularly from each plate member.

3. A connector as claimed in claims I or 2, wherein each nail member has two opposing protrusions spaced from the proximal end of the respective nail member by a distance substantially equal to the thickness of the plate member.

4. A connector as claimed in any one of the preceding claims, wherein the or each protrusion is undercut so as to provide a substantially planar surface which contacts the other respective plate member.

5. A connector as claimed in any one of the preceding claims, manufactured by passing the nail members of each nail plate through the holes present in the other respective nail plate and translating the nail plates with respect to one another so that the or each protrusion is caused to retain the nail plates together in an interlocking manner.

6. A connector as claimed in any one of the preceding claims, wherein the plate members include a bolt hole for receiving a bolt.

7. A connector substantially as hereinbefore described with reference to the accompanying drawings.