GB2054791A - Structural jointing system - Google Patents

Abstract

Apparatus for joining two struts (10, 11) comprises an inner adaptor (13) mounted e.g. by bolt 14 on one strut (10) and an outer member (12) carried by, being preferably integral with, the other strut (11), the outer member (12) being shaped to fit around the adaptor (13) so that portions (31A, 35A) of elongate slots (31, 35) respectively formed in the adaptor (13) and outer member (12) are aligned. The slots (31, 35) extend at an angle to each other and to the intended longitudinal direction of said other strut (11). A barrel nut (36) is located in the aligned slot portions (31A, 35A) and a tightening screw 33 is screwed into the barrel nut (36) via aligned access holes (32, 34) in the adaptor (13) and outer member (12). Tightening of the screw (33) causes sliding movement of the barrel nut (36) along both slots (31, 35) in a direction so as to draw the struts (10, 11) tightly together at said joint. If the strut (10) to which the adapter (13) is bolted is tubular, a spring loaded insert (15 and 16) is located inside the strut (10) to provide an anchor for the bolt (14). <IMAGE>

Description

SPECIFICATION Structural jointing system, particularly for joining tubular members This invention relates to a structural jointing system which is useful in the construction of, for example, furniture, shelving or partitioning, and is particularly, but not exclusively suitable for joining together two tubular structural elements.

According to the invention, there is provided apparatus for joining together two structural elements, comprising an inner member which is adapted to be carried by one structural element so as to project therefrom in a predetermined direction and which is formed with a first elongate slot longitudinally orientated at an angle to said predetermined direction; an outer hollow member which is adapted to be carried by the other structural element, which is shaped so that it can fit around the inner member, and which is formed with a second elongate slot disposed so that, when the outer member fits around the inner member, the second slot is longitudinally orientated at an angle to both said predetermined direction and the longitudinal direction of the first slot with respective portions of the first and second slots in registration to form an elongate recess extending perpendicular to said predetermined direction, and with a hole in the outer member in registration with a hole in the inner member to constitute a screw access hole extending through the outer and inner members into the recess; a barrel nut shaped for accommodation in said recess once formed so as to extend through the first and second slots; and a screw which when inserted through said screw access hole and into a correspondingly located, threaded bore in the barrel nut in the recess and subsequently tightened causes sliding movement of said barrel nut along both the first and second slots, the relative dispositions of the first and second slots and the screw access hole being such that said sliding movement of the barrel nut results in movement of the inner member further into said outer member in said predetermined direction.

Conveniently, the longitudinal direction of the first slot is oblique to said predetermined direction and the longitudinal direction of the second slot is perpendicular to said predetermined direction.

Where the inner member is to be bolted to a tubular element or slot, the apparatus preferably includes an insert which is locatable inside the tubular structural element to provide an anchor for the bolt securing the inner member to said tubular structural element. The insert is preferably a substantially U-shaped member of which the arms are resiliently biassed outwardly so as, in use, to force the arms of the insert against the internal walls of a tubular structural member. Conveniently the insert comprises two parailel blocks connected by a generally U-shaped steel strip spring.

Where the insert is to be located at the lower end of a structural element which is to carry a structural foot, the insert may include a plate to which the foot can be fitted.

Reference will now be made to the accompanying drawings which illustrate, by way of example, one embodiment of the invention, and of which: Figure 1 shows an exploded, part cut-away view of a structural joint between a vertical and a horizontal tubular strut, located at the lower end of the vertical strut; Figure 2 shows an exploded part-cut away view of part of a similar structural joint located at the top of the vertical strut, illustrating one embodiment of the mounting of the adaptor on the vertical strut; and Figure 3 shows an exploded view of the insert of the joint shown in Figure 1.

In the drawings, like parts are identified by like reference numerals.

Figure 1 shows a right-angled joint between a vertical tubular strut 10 and a horizontal tubular strut 11.The open end 12 of the strut 11 fits snugly over and is supported by an adaptor 13 which is mounted on the strut 10 so as to project at right angles therefrom i.e. at the angle of the finished joint. In this embodiment, the adaptor 13 is bolted to the strut 10, and, due to the tubular construction of the strut 10, the shouldered bolt 14 securing the adaptor 1 3 to strut 10 requires some additional anchorage. This is provided by a spring loaded insert 1 5 which is located inside the strut 10 adjacent the joint.

As best shown in Figure 3, the insert 1 5 includes a pair of identical parailel rectangular blocks 1 6 made of common unhardened material, which may be machined from metal, diecast in zinc or aluminium alloys or alternatively moulded in plastics material. The blocks 1 6 are connected by a substantially U-shaped steel strip spring 1 7 of which the arms are connected to the respective blocks 16 by means of fasteners 18 located in holes 1 9 in the blocks 16, the fasteners 1 8 being, for example, drive rivets, peened over spigots if the blocks 1 6 are of metal, or heat-formed spigot heads if the blocks 1 6 are made of plastics.The spring 1 7 acts to urge the blocks 1 6 apart so that when the insert is located in the strut 10, the insert limbs, i.e. the blocks 1 6 are forced into intimate contact with the walls of the strut 10.

Adjacent the base of the U-shaped spring 17, each block is formed with a threaded bore 20 into which the end of a shouldered bolt 14 can be screwed so that each block can form an anchorage for a respective adaptor in the case where two horizontal struts are to be joined to the vertical strut 10, one on either side. In the illustrated case, only one joint is formed, and so the bore 20 in one of the blocks 1 6 is redundant, and may be omitted if no further joint at this location along the strut 10 is contemplated.

Adjacent the bore 20 in each block there is provided a locating projection 29 in the form of the head of a drive rivet, or a moulded or cast rounded pip.

The insert 1 5 is pushed into the open end of the tubular strut 10 and slid therealong using a suitably shaped mandrel (not shown) until the insert is correctly located inside strut 10 at the location of the joint to be constructed, with the bore 20 in the respective block 1 6 in registration with a bolt clearance hole 22 preformed in the side of strut 10, at which time the locating projection 21 on each block engages with a snap fit in a corresponding location hole 23 preformed in the side of the strut 10.

Clearly, the blocks 1 6 are suitably chamfered and/or grooved to clear the radiused inner corners of strut 10 and/or any weld beads projecting inwardly of the walls of strut 10.

To assist in the correct location of the insert 1 5 in strut 10, the mandrel may be provided with stops which halt the sliding of the mandrel and hence the insert into the strut 10 when the correct location for the insert is reached. This is particularly useful where several joints are to be constructed at spaced locations along the strut 10 requiring the insertion of several inserts.

If, as is the case for the joint shown in Figure 1, the joint is located at the lowermost end of strut 10, at a position in the structure, of which the struts 10 and 11 are to form a part, requiring the provision of a foot 24 to support the structure. the insert 1 5 may be provided with means for mounting the foot 24. Such means here take the form of a plate 25 which is accommodated in aligned grooves 26 in the blocks 16, and formed with a threaded bore 26A for threaded engagement by the threaded shank 24A of the foot 24, so that the effective length of the foot 24 can be readily adjusted. In a joint higher up the strut 10, such as that shown in Figure 2 which is actually located at the upper end of strut 10 which in this instance is closed, the grooves 26 in the insert blocks 1 6 are of course redundant and may be omitted.

The manner in which the adjustor 13 is mounted on strut 10 is best illustrated in Figure 2.

The adjustor 13, which constitutes the inner member of the joint, may be machined from metal, diecast in aluminium zinc alloys or moulded in plastics materials. Its cross-sectional shape corresponds to the internal shape of the tubular strut 11, being in this instance generally rectangular, and is suitably chamfered as at 27 and/or grooved, so as to clear the radiused inner corners of the cross-section of strut 11 and/or any protruding weld bead in strut 11. The face of the adaptor 13 which is to fit against strut 10 is provided with a spring pin 28, which is either mounted thereon as a tight fit in a corresponding aperture after maching, cast on or moulded in as a spigot if the adaptor is diecast or moulded as mentioned above.The spring pin 28 is inserted into a correspondingly dimensioned location hole 29 in the side of strut 10 adjacent the bolt clearance hole 22 therein, and serves to locate the adaptor 13 on the strut 10 and hold it square to the vertical axis. The shouldered bolt 14 is then inserted through a bolt clearance hole 30 in the adaptor 1 3, through the bolt clearance hole 22 in the strut 10 and screwed into threaded bore 20 in the respective insert block 16, drawing the adaptor tightly against strut 10 by the engagement by the bolt head of a suitable abutment (not visible) at the end of the clearance hole 30.

Extending from one side of the adaptor to the opposite side thereof in an elongate slot 31 which is longitudinally orientated at an angle, conveniently 450, to the intended longitudinal orientation of strut 11. A slightly countersunk hole 32 in the top of the adaptor 1 3 provides access from above to the slot 31 for a screw 33 used to secure the strut 11 to the adaptor 13 in a manner to be described later. The countersinking of hole 32 permitting both easy location of screw 33 and the use of different tube gauges for strut 11.

The end portion 1 2 of the strut 11, constituting the outer member for the joint, is then slid over the end of the projecting adaptor 13, until the end edge of the strut 11 is substantially located against one side of strut 10, and a countersunk screw access hole 34 in the top wall of strut 11 in substantial registration with hole 32 in the adaptor 13. At this point the lower end 31 A of slot 31 in the adaptor 13 is in registration with the lower end 35A of an elongate slot 35 which is formed in the corresponding side walls of the end portion 1 2 of strut 11, to form an elongate recess extending through both strut 11 and adaptor 13 perpendicular to the longitudinal axis of strut 11.

The slot 35 is longitudinally orientated at an angle - to the longitudinal orientation of slot 31 and also at an angle, here a right angle, to the longitudinal axis of strut 11.

A barrel nut 36, which is either made of turned metal, a diecast aluminium or zinc alloy or moulded plastics material, is located in the recess thus formed with a threaded bore 37 in the barrel nut 35 aligned with the aligned holes 32 and 34 in adaptor 1 3 and strut 11 respectively. The screw 33 is then screwed into bore 37 through holes 32, 34, subsequent tightening of the screw 33 causing the barrel nut 36 to slide along both slots 31,35 and thus resulting in relative movement between the strut 11 and adaptor 13. The relative dispositions of the slots 31, 35 and the screw 33 are such that the barrel nut 36 follows an inclined path directed upwardly and towards strut 10 so that the strut 11 is drawn tightly against strut 10, the angular disposition of slot 31 in this case dictating the extent of this movement. Clearly if the other end of strut 11 is fixed, possibly by a similar joint to another structural element, this tightening of screw 33 could be used to apply a present tension to strut 11.

It will be apparent that, instead of being integral with the strut 11, the end portion 12 may be mounted on the end of strut 11 by other suitable means e.g. by bolts, particularly if the strut 11 is not tubular. Similarly, instead of being bolted to strut 10, the adaptor 1 3 may be integral therewith, particularly if the strut 10 is not tubular but is instead solid, or connected thereto by other suitable means. It is also possible that the adaptor 1 3 may be fitted to the horizontal strut 11 and the outer member 1 2 be fitted to the vertical strut 10.

Claims (13)

1. Apparatus for joining together two structural elements, comprising an inner member which is adapted to be carried by one structural element so as to project therefrom in a predetermined direction and which is formed with a first elongate slot longitudinally orientated at an angle to said predetermined direction; an outer hollow member which is adapted to be carried by the other structural element, which is shaped so that it can fit around the inner member, and which is formed with a second elongate slot disposed so that, when the outer member fits around the inner member, the second slot is longitudinally orientated at an angle to both said predetermined direction and the longitudinal direction of the first slot with respective portions of the first and second slots in registration to form an elongate recess extending perpendicular to said predetermined direction, and with a hole in the outer member in registration with a hole in the inner member to constitute a screw access hole extending through the outer and inner members into the recess; a barrel nut shaped for accommodation in said recess once formed so as to extend through the first and second slots; and a screw which when inserted through said screw access hole and into a correspondingly located, threaded bore in the barrel nut in the recess and subsequently tightened causes sliding movement of said barrel nut along both the first and second slots, the relative dispositions of the first and second slots and the screw access hole being such that said sliding movement of the barrel nut results in movement of the inner member further into said outer member in said predetermined direction.

2. Apparatus as claimed in claim 1 , in which the longitudinal direction of the first slot is oblique to said predetermined direction and the longitudinal direction of the second slo.t is perpendicular to said predetermined direction.

3. Apparatus as claimed in claim 1 or claim 2, in which the inner member is constituted by an adaptor which is arranged to be bolted to said one structural element.

4. A structural joint comprising two structural elements and apparatus as claimed in any of claims 1 to 3, in which the inner member is mounted on one structural member, the outer member is mounted on the other structural member, with the barrel nut located in said recess and said screw inserted into said screw access hole and tightened as aforesaid so as to draw the structural members tightly together.

5. Apparatus as claimed in claim 3, suitable for use in joining two structural elements in which the structural element to which the inner member is to be bolted is tubular, the apparatus further comprising an insert which is locatable inside the tubular structural element to provide an anchor for.

the bolt securing the inner member to said tubular structural element.

6. Apparatus as claimed in claim 5, in which said insert comprises a substantially U-shaped member of which the arms are resiliently biassed outwardly so as, in use, to force the arms of the insert against the internal walls of a tubular structural member.

7. Apparatus as claimed in claim 6, in which the insert comprises two paraliel blocks connected by a generally U-shaped steel strip Spring.

8. Apparatus as claimed in any of claims 5 to 7, in which the insert incorporates means for supporting a structural foot.

9. Apparatus for joining together two structural members, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

10. A structural joint comprising two structural elements, a first one of said two structural elements incorporates a tubular strut, and apparatus as claimed in any of claims 5 to 9, in which said insert is located inside said tubular strut, said inner member is bolted to said tubular strut, the bolt being anchored in said insert, said outer member is mounted on the other structural member with the barrel nut located in said recess and said screw inserted in said screw access hole and tightened as aforesaid so as to draw tightly together said tubular strut and said other structural member.

11. A structural joint as claimed in claim 10, comprising complementary engaging means on said insert and the tubular strut of said one structural element for accurately locating the insert within said tubular strut.

12. A structural joint as claimed in claim 10 or claim 11, in which said other structural element incorporates a respective tubular strut, the free end of which constitutes said outer member.

13. A structural joint substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.