GB2038441A - Improvements in or relating to ladders - Google Patents

Abstract

A joint between a hollow metal rung and a metal stile of a ladder comprises a metal ferrule inserted into the end portion of the rung, and expanded into tight engagement therewith. The ferrule extends through a hole in the stile, and has a flange in engagement with a face of the stile remote from the rung. The ferrule and rung may be expanded into a frustoconical configuration. The rung, ferrule and stile are preferably of extruded aluminium. <IMAGE>

Description

SPECIFICATION Improvements in or relating to ladders The present invention relates to ladders, and more particularly to a joint arrangement for securing the rungs of the ladder to the stiles.

According to one aspect of the present invention, there is provided a method of forming a joint between a hollow metal rung, and a metal stile of a ladder, said method comprising inserting a metal ferrule into the end portion of the rung so that the ferrule extends from the rung through a hole in the stile, and expanding the ferrule, by applying internal pressure into tight engagement with the internal surface of the rung.

According to another aspect of the present invention, there is provided a joint between a hollow metal rung and a metal stile of a ladder, said joint comprising a metal ferrule inserted into the end portion of the rung, and expanded into tight engagement therewith, said ferrule extending through a hole in the stile, and having a flange in engagement with a face of the stile remote from the rung.

The invention will now be described by way of example only with reference to the accompanying diagrammatic drawing in which: Figure 1 is a cross-section through a rung/stile joint with the components loosely assembled; Figure 2 is a cross-section showing the completed joint; and Figure 3 is a cross-section similar to Figure 2 but showing a modified configuration.

There is shown in Figures 1 and 2 a rung/stile joint of a ladder consisting of metal stiles and hollow metal rungs, both preferably of extruded aluminium. Each stile comprises a central web with a transverse flange at each side of the web, with the rungs extending between the opposed inner faces of the webs of the two stiles without actually passing through the webs.

In order to secure the end of each rung to the adjacent stile, a ferrule, which is also preferably of extruded aluminium, is inserted into the end of the hollow rung through a hole formed in the central web of the stile as illustrated in Figure 1, the ferrule and the hole being of similar cross-section to that of the interior of the rung. At this stage the ferrule is a relatively loose fit within the hole and the end of the rung.

The ferrule is then expanded internally as indicated diagrammatically by the arrows A in Figure 2 into tight engagement with the internal surface of the rung, and the outer end portion of the ferrule, which projected from the outer face of the central web as illustrated in Figure 1, is pressed over as diagrammaticaily indicated by the arrow B in Figure 2 to form an outwardly-directed radial flange which extends around the edge of the hole in the central web.

The above arrangement provides a strong and reliable joint between the end of the rung and the stile without involving the necessity for relatively expensive machining operations. The operations for piercing the stiles to form the hole therein and for cutting the rungs and ferrules to length can readily be automated as can the subsequent joining operation. This latter operation may be effected by using an expanding mandrei for expanding the ferrule in the direction of the arrows A whilst a part of the same tool, or another tool, produces the outer flange on the ferrule.

In the modified arrangement shown in Figure 3, the ferrule is expanded into a divergent configuration as is the adjacent part of the rung.

This effect will be achieved by using an expanding mandrel of appropriate cross-sectional configuration.

1. A method of forming a joint between a hollow rung, and a stile of a ladder, said method comprising inserting a ferrule of ductile material into the end portion of the rung so that the ferrule extends from the rung through a hole in the stile, and expanding the ferrule, by applying internal pressure, into tight engagement with the lateral surface of the rung.

2. A method as claimed in claim 1, in which the hollow rung is made of ductile material.

3. A method as claimed in claim 1, which further comprises forming a flange on the ferrule for engagement with a face of the stile remote from the rung, by pressing axially the outer end portion of the ferrule after insertion of the ferrule into the rung.

4. A joint between a hollow rung and a stile of a ladder, said joint comprising a ferrule of ductile material inserted into the end portion of the rung, and expanded into tight engagement therewith, said ferrule extending through a hole in the stile, and having a flange in engagement with a face of the stile remote from the rung.

5. A joint as claimed in claim 4 in which the ferrule, hollow rung, and stile are of extruded aluminium.

6. A joint as claimed in claim 4 or claim 5 in which the ferrule and the portion of the hollow rung surrounding it are expanded into tight engagement.

7. A joint as claimed in claim 6 in which the ferrule and the portion of the hollow rung surrounding it are expanded into frusto-conical configuration narrowing towards the stile.

8. A method as claimed in claim 1, and substantially as hereinbefore described with reference to the accompanying drawings.

9. A joint as claimed in claim 3, and substantially as hereinbefore described with reference to the accompanying drawings.

10. A joint formed by a method in accordance with any one of claims 1 to 3 or claim 8.

11. A ladder having a plurality of rung/stile joints in accordance with any one of claims 4 to 7, 9 or 10.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to ladders The present invention relates to ladders, and more particularly to a joint arrangement for securing the rungs of the ladder to the stiles. According to one aspect of the present invention, there is provided a method of forming a joint between a hollow metal rung, and a metal stile of a ladder, said method comprising inserting a metal ferrule into the end portion of the rung so that the ferrule extends from the rung through a hole in the stile, and expanding the ferrule, by applying internal pressure into tight engagement with the internal surface of the rung. According to another aspect of the present invention, there is provided a joint between a hollow metal rung and a metal stile of a ladder, said joint comprising a metal ferrule inserted into the end portion of the rung, and expanded into tight engagement therewith, said ferrule extending through a hole in the stile, and having a flange in engagement with a face of the stile remote from the rung. The invention will now be described by way of example only with reference to the accompanying diagrammatic drawing in which: Figure 1 is a cross-section through a rung/stile joint with the components loosely assembled; Figure 2 is a cross-section showing the completed joint; and Figure 3 is a cross-section similar to Figure 2 but showing a modified configuration. There is shown in Figures 1 and 2 a rung/stile joint of a ladder consisting of metal stiles and hollow metal rungs, both preferably of extruded aluminium. Each stile comprises a central web with a transverse flange at each side of the web, with the rungs extending between the opposed inner faces of the webs of the two stiles without actually passing through the webs. In order to secure the end of each rung to the adjacent stile, a ferrule, which is also preferably of extruded aluminium, is inserted into the end of the hollow rung through a hole formed in the central web of the stile as illustrated in Figure 1, the ferrule and the hole being of similar cross-section to that of the interior of the rung. At this stage the ferrule is a relatively loose fit within the hole and the end of the rung. The ferrule is then expanded internally as indicated diagrammatically by the arrows A in Figure 2 into tight engagement with the internal surface of the rung, and the outer end portion of the ferrule, which projected from the outer face of the central web as illustrated in Figure 1, is pressed over as diagrammaticaily indicated by the arrow B in Figure 2 to form an outwardly-directed radial flange which extends around the edge of the hole in the central web. The above arrangement provides a strong and reliable joint between the end of the rung and the stile without involving the necessity for relatively expensive machining operations. The operations for piercing the stiles to form the hole therein and for cutting the rungs and ferrules to length can readily be automated as can the subsequent joining operation. This latter operation may be effected by using an expanding mandrei for expanding the ferrule in the direction of the arrows A whilst a part of the same tool, or another tool, produces the outer flange on the ferrule. In the modified arrangement shown in Figure 3, the ferrule is expanded into a divergent configuration as is the adjacent part of the rung. This effect will be achieved by using an expanding mandrel of appropriate cross-sectional configuration. CLAIMS

1. A method of forming a joint between a hollow rung, and a stile of a ladder, said method comprising inserting a ferrule of ductile material into the end portion of the rung so that the ferrule extends from the rung through a hole in the stile, and expanding the ferrule, by applying internal pressure, into tight engagement with the lateral surface of the rung.

2. A method as claimed in claim 1, in which the hollow rung is made of ductile material.

3. A method as claimed in claim 1, which further comprises forming a flange on the ferrule for engagement with a face of the stile remote from the rung, by pressing axially the outer end portion of the ferrule after insertion of the ferrule into the rung.

4. A joint between a hollow rung and a stile of a ladder, said joint comprising a ferrule of ductile material inserted into the end portion of the rung, and expanded into tight engagement therewith, said ferrule extending through a hole in the stile, and having a flange in engagement with a face of the stile remote from the rung.

5. A joint as claimed in claim 4 in which the ferrule, hollow rung, and stile are of extruded aluminium.

6. A joint as claimed in claim 4 or claim 5 in which the ferrule and the portion of the hollow rung surrounding it are expanded into tight engagement.

7. A joint as claimed in claim 6 in which the ferrule and the portion of the hollow rung surrounding it are expanded into frusto-conical configuration narrowing towards the stile.

8. A method as claimed in claim 1, and substantially as hereinbefore described with reference to the accompanying drawings.

9. A joint as claimed in claim 3, and substantially as hereinbefore described with reference to the accompanying drawings.

10. A joint formed by a method in accordance with any one of claims 1 to 3 or claim 8.

11. A ladder having a plurality of rung/stile joints in accordance with any one of claims 4 to 7, 9 or 10.