GB2225401A - Structural connectors - Google Patents

Abstract

A structural connector replaces plain pins customarily used in pinning together beams and stays or props. The connector comprises a pin 10 surrounded by a collar 11 that is expanded as the pin is driven into the collar. The connector is inserted into registering holes in the parts to be interconnected and lugs 27 on the collar engage the outermost surface of one of the parts to limit insertion of the connector as the pin is driven into the collar to expand it. The pin has a head 12 a constant diameter portion 19, a tapered portion 18, a constant diameter portion 17, a tapered portion 16, a constant diameter portion 15, and an end flange 14. Collar 11, which comprises three or more segments urged radially inwardly into contact by springs received in end grooves 22a, 22b, has an internal bore having a constant diameter surface 23 having the same diameter and length as surface 17, a frusto-conical surface 24 having the same length and cone angle as tapered portion 18, a constant diameter portion 25 having the same diameter but lesser length than portion 19 and a second frusto-conical portion 26 having the same cone angle as portion 18 of pin. A diametrical hole adjacent flange 14 of pin 10 receives a retaining wire or pin to prevent movement of collar 11 after it has been expanded. <IMAGE>

Description

STRUCTURAL CONNECTORS The invention relates to structural connectors for use, for example, in the interconnection of structural members.

There are a number of applications in which it is desired to form joints between structural members. For example, shoring is often supported by vertical beams which are themselves supported by props with connections between the beams and the props. Other frameworks such as formwork and composite beams can require similar connections.

It has heretofor been customary to use plain pins of cylindrical outer shape (perhaps with an end bevel) to form such connections. Such pins have the disadvantage that they are seldom a sufficiently tight fit to prevent relative movement between the two connected members. In addition, they have traditionally been of small diameter and so unable to withstand the substantial loads which they are now required to bear.

According to the invention, there is provided a structural connector comprising a pin having a head and a body, and a radially expandable collar surrounding the body, the body and the collar being relatively movable axially, the external surface of the body and the internal surface of the collar being such that, when the collar is at a po-sition on the pin remote from the head, relative axial movement of the head towards the collar causes radial expansion of the collar, so allowing the collar, when received in aligned holes of two structural members, to inter- connect said members.

In this way, the connector can provide a joint between structural members that is play-free. In addition the connector can be sized to carry substantial loads. The pin can readily be moved to expand the collar by hitting the head of the pin. The connector can be released by hitting the end of the pin opposite the head.

The collar may be radially expandable by being formed in two or more segments. For example there may be three segments.

The collar may include spring means tending to urge the segments radially inwardly to a position in which adjacent edges of the segments are in contact.

To cause the radial expansion of the collar by movement of the pin, the external surface of the pin body may be formed with a surface portion which is of increasing diameter in an axial direction towards the head, the interior surface of the collar having a portion that co-operates with said pin surface to expand the collar on said movement of the pin.

The pin may be provided with two such surface portions at axially spaced locations therealong, the collar having two such co-operating surfaces.

Preferably each pin and collar surface portion is of frusto-conical shape.

Each pin and collar surface portion may have associated therewith a portion of constant diameter in an axial direction and at an end closer to the head of the pin than the associated portion of increasing diameter, the constant diameter portions of the pin and collar engaging when the collar is in the expanded position.

The following is a more detailed description of one embodiment of the invention by way of example, reference being made to the accompanying drawings in which: Figure 1 is an elevation of a pin of a structural connector; Figure 2 is an elevation of a collar of the structural connector of Figure 1; Figure 3 shows side and end elevations of the structural member in a contracted position; Figure 4 shows side and end elevations of the structural member in an expanded position; Figure 5 shows a composite beam including structural members interconnected using structural connections of the kind shown in Figures 1 to 4, and Figure 6 is a view of a part of the composite beam of Figure 5 showing the structural connector in more detail.

Referring first to Figures 1 and 2, the structural connector comprises a pin 10 carrying a collar .11 (see also Figure 3).

The pin 10, as best seen in Figure 1 comprises a head 12 and a body 13. The end of the body 13 opposite the head 12 is provided with a flange 14. The body 13 has an exterior surface which is divided into five surfaces portions 15,16,17,18 and 19. Starting from the flange 14 there is, in an axial direction, a portion 15 of constant minimum diameter along its length. This leads to a frusto-conical portion 16 whose diameter increases along its length. Next there is a second portion 17 of a constant diameter along its length that is greater than the diameter of the first portion 15. Then there is a second frusto-conical portion 18 whose diameter increases along its length. Finally, there is a third portion 19 which is of constant diameter along its length and which terminates at the head 12.

A hollow bore 20 extends along the length of the pin to save weight.

The collar 11 is split into three segments lla,llb and llc (Figures 3 and 4) bound together by coil springs 21a,21b received in respective grooves 22a,22b located towards respective ends of the collar 11. The springs, 21a,21b, tend to urge the segments lla,llb,llc radially inwardly to a contracted position in which the side edges are in contact, as seen in Figures 3 and 4.

In the contracted position, the interior surfaces of the segments lla,llb,llc form a continuous surface divided into four axially successive portions 23,24,25,26. Starting from the end of the collar adjacent the flange 14, the first surface 23 is of constant diameter along its length, the diameter and the axial length being the same as the axial length and diameter of the second constant diameter portion 17 of the pin. Next there is a first frusto-conical portion 24 of the same axial length and cone angle as the second frusto-conical portion 15 of the pin. Then there is a second constant diameter portion 25 having the same diameter as the third constant diameter portion 19 of the pin but being of shorter axial length. Finally, there is a second frusto-conical portion 26, which has the same cone angle as the second frusto-conical portion 18 of the pin 11.

Adjacent the first constant diameter surface 23 is an annular recess 37.

In its contracted position, the collar 11 is positioned on the pin 10 with the collar 11 abutting the flange 14. In this position, the flange 14 is received in the recess 37 and engages with the collar 11 to prevent the collar 11 falling off the pin 10. The first constant diameter portion 23 of the collar overlies the first constant diameter portion 15 of the pin, the first frusto- conical portion 24 of the collar 11 overlies the first frusto-conical portion 16 of the pin, the second constant diameter portion 25 of the collar 11 overlies the second constant diameter portion 17 of the pin 11 and the second frusto-conical portion 26 of the collar 11 overlies part of the second frusto-conical portion 18 of the pin 10.

Each segment lla,llb,llc carries, at an end adjacent the head 12, a projecting lug 27 for a purpose to be described below.

In use, connecions of the kind described above with reference to the drawings are used to connect together structural members and one example of this is the composite beam shown in Figures 5 and 6.

The structural members comprise beams 28 and struts 29. Each beam 28 is hollow and is provided with a series of larger holes 30 and smaller holes 31 centrally arranged along the beam 28. Each larger hole 30 has a diameter equal to the expanded diameter of a connector. Each strut 29 comprises a tube 32 whose ends receive plates 33 with end pieces 34 formed with holes 35 of the same diameter as the larger holes 30 in the beam 28.

The composite beam is formed by two parallel but spaced beams 28 (or series of beams 28 connected by fish plates 36) interconnected by struts 29 arranged in alternately facing V-configuration (see Figure 5) with the end pieces 34 of successive struts (29) overlapping. As seen in Figure 6, the two overlapping end pieces 34 are arranged with their holes 35 in register and in register with a larger hole 30 in the associated beam 28. A connector in the contracted condition (Figure 3) is inserted through the holes 30,35. The lugs 27 engage the face of the outermost end piece 34 to limit the insertion of the connector into the holes.

The pin 10 is then forced into the collar 11, by, for example, hitting the head 12 with a hammer, the reaction force being taken by the beam via the lugs 27. The frusto-conical portions 16,18 of the pin 10 act against the frusto-conical portions 24,26 of the collar 11 to expand the segments lla,llb,llc radially until the first and second constant diameter portions 23,25 of the collar 11 engage the second and third constant diameter portions 17,19 of the pin 10 as the end of the collar 11 engates the head 12. The segments lla,llb,llc are thus urged into contact with the holes 30,35 to form a pinned joint.

The tightness of the joint is determined by the relative diameters of the expanded connector and the holes 30,35. Generally, these will be dimensioned so that the expanded connector is an interference fit in the holes 30,35.

The remaining joints are pinned in the same way to form a composite beam. In this beam, the connections are play-free The connector may be provided with a diametrically extending hole through the end of the pin 10 adjacent the flange 14 to receive a pin or wire when the collar 11 is expanded to prevent movement of the collar. The connector can be readily removed by removing any pin/wire and then hitting the flanged end of the pin 11 to drive the pin 10 out of the collar 11 so allowing the collar 11 to collapse under the force of the springs 21a,21b.

Of course, the connector described above with reference to the drawings may be used to connect other structural members. For example, shoring is often supported by vertical beams which are supported by props. The connections between the beams and props may be by use of such connectors.

It will be appreciated that the pin body 13 may be formed with more or less constant diameter and frusto-conical surfaces, with the collar 11 being correspondingly arranged. There may be more or less than three segments on the collar 11.

The connector may be made out of a metal such as steel or may be part plastics and part steel or all of plastics.

Claims (8)

1. A structural connector comprising a pin having a head and a body, and a radially expandable collar surrounding the body, the body and the collar being relatively movable axially, the external surface of the body and the internal surface of the collar being such that, when the collar is at a position on the pin remote from the head, relative axial movement of the head towards the collar causes radial expansion of the collar, so allowing the collar, when received in aligned holes of two structural members, to interconnect said members.

2. A connector according to claim 1 wherein the collar is radially expandable by being formed in two or more segments.

3. A connector according to claim 1 wherein there are three segments.

4. A connector according to claim 2 or claim 3 wherein the collar includes spring means tending to urge the segments radially inwardly to a position in which adjacent edges of the segments are in contact.

4. A connector according to any one of claims 1 to 3 wherein, to cause the radial expansion of the collar by movement of the pin, the external surface of the pin body is formed with a surface portion which is of increasing diameter in an axial direction towards the head, the interior surface of the collar having a portion that co-operates with said pin surface to expand the collar on said movement of the pin.

5 A connector according to claim 4 wherein the pin is provided with two such surface portions at axially spaced locations therealong, the collar having two such co-operating surfaces.

6. A connector according to claim 5 wherein each pin and collar surface portion is of frusto-conical shape.

7. A connector according to any one of claims 4 to 6 wherein each pin and collar surface portion has associated therewith a portion of constant diameter in an axial direction and at an end closer to the head of the pin than the associated portion of increasing diameter, the constant diameter portions of the pin and collar engaging when the collar is in the expanded position.

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