GB2118877A - Joining a first member to a second member - Google Patents

Abstract

A method of joining a hollow section metal ladder rung (5) to a ladder stile member (2) comprises punching a hole (1) in the member (2), placing a drawing die (3) having a die cavity (4) on one surface of the member (2), forcing the rung (5) partly through the hole (1) so as to draw the part of the member (2) bounding the hole (1) into the die cavity (4), thereby forming a circumferential flange (7), removing the drawing die (3) and forming a mechanical joint between the protruding end (8) of the rung (5), the flange (7) and the member (2) by bending the end (8) and the flange (7) into contact with the member (2), for example by hammering. The rung (5) may be provided with an additional flange (6) which abuts the stile member (2) in the completed ladder. <IMAGE>

Description

SPECIFICATION Improvements in or relating to joining a first member to a second member This invention relates to improvements in or relating to joining a first member to a second member and, in particular, to a method suitable for fixing a hollow section ladder rung to a stile member for a ladder.

In a previously proposed method assembling a metal ladder, a hole is formed in a stile member using a die and punch having matching profiles. A hollow metal section rung is then slidably inserted through the hole so that an end thereof protrudes through the hole. The protruding end is then formed into a mechanical joint with the stile member by radial rivetting, that is, folding the end back into contact with that part of the stile member bounding the hole, for example by hammering. The hole is formed with a crosssection corresponding to that of the rung, so that a close fit can be obtained.

In an alternative prior proposal, a hole is formed in a ladder stile using a drawing punch and die, the die profile having a larger cross-section than the punch. Thus, that part of the stile bounding the hole formed is drawn into the die cavity to form a circumferential flange. A hollow section rung is then slidably inserted through the hole so that an end thereof protrudes slightly from the stile member surface having the flange and the protruding end, together with the flange, is folded back into contact with the stile member, for example by hammering.

It has been found that there is a tendency for the rung to rotate slightly with respect to the stile member, thus causing a reduction in torsional rigidity of a ladder incorporating such a ladder stile.

It is an object of the present invention to provide a method of joining a rung to a ladder stile member, whereby the above disadvantage may be overcome or at least mitigated.

Accordingly, the present invention provides a method of joining a first member to a second member, which method comprises forming a hole through the second member, placing a drawing die on one surface of the second member so that the hole is located substantially centrally of a cavity of the drawing die, the cavity having a cross-section greater than the cross-section of the first member, and forcing a portion of the first member through the hole into the cavity so as to draw a part of the second member bounding the hole into the cavity, thereby forming a flange circumferential of the hole.

For a better understanding of the present invention, and to show how the same may be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 shows a sectional view of a rung, a ladder stile member and a drawing die during a first stage of a method according to the invention, and Figure 2 shows the rung, stile member and drawing die of Figure 1 during a second stage of the method.

Referring now to the drawings, a hole 1 is formed in a ladder stile member 2 by means of a punch and die (not shown) having matching profiles. A drawing die 3 having a cavity 4 is placed behind the hole 1, the cavity 4 being concentric with the hoie 1. A rung 5 is provided with a flange 6 and has a cross-section slightly smaller than that of the die cavity 4 and substantially larger than that of the hole 1. As shown in Figure 2, the rung 5 is forced through the hole 1, thereby drawing that part of the member 2 bounding the hole 1 into the cavity 4 to form a circumferential flange 7, which grips the rung 5.

The flange 6 formed on the rung 1 abuts the surface of the member 2 opposite the drawing die.

The drawing die is then removed and the protruding end 8 of the rung, together with the circumferential flange 7, is bent back into contact with the member 2, for example by hammering.

Thus, a relatively secure fit is obtained between the rung 5 and the member 2, and the torsional rigidity of a ladder made with such a stile member and rung construction is improved compared with the prior art proposals discussed hereinbefore.

1. A method of joining a first member to a second member, which method comprises forming a hole through the second member, placing a drawing die on one surface of the second member so that the hole is located substantially centrally of a cavity of the drawing die, the cavity having a cross-section greater than the crosssection of the first member, and forcing a portion of the first member through the hole into the cavity so as to draw a part of the second member bounding the hole into the cavity, thereby forming a flange circumferential of the hole.

2. A method according to Claim 1, wherein the first member is of hollow cross-section.

3. A method according to Claim 2, which further comprises removing the drawing die and forming a joint between the part of the first member which extended into the cavity, the circumferential flange and the second member by bending the said part and the flange into contact with the second member.

4. A method according to any one of the preceding claims, wherein the first member is a metal rung for a ladder and the second member is a metal stile member for a ladder.

5. A method of joining a first member to a second member, substantially as hereinbefore described with reference to the accompanying drawings.

6. A joint whenever produced using the method of any one of the preceding claims.

7. A joint between a first member and a second member, substantially as hereinbefore described

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

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to joining a first member to a second member This invention relates to improvements in or relating to joining a first member to a second member and, in particular, to a method suitable for fixing a hollow section ladder rung to a stile member for a ladder. In a previously proposed method assembling a metal ladder, a hole is formed in a stile member using a die and punch having matching profiles. A hollow metal section rung is then slidably inserted through the hole so that an end thereof protrudes through the hole. The protruding end is then formed into a mechanical joint with the stile member by radial rivetting, that is, folding the end back into contact with that part of the stile member bounding the hole, for example by hammering. The hole is formed with a crosssection corresponding to that of the rung, so that a close fit can be obtained. In an alternative prior proposal, a hole is formed in a ladder stile using a drawing punch and die, the die profile having a larger cross-section than the punch. Thus, that part of the stile bounding the hole formed is drawn into the die cavity to form a circumferential flange. A hollow section rung is then slidably inserted through the hole so that an end thereof protrudes slightly from the stile member surface having the flange and the protruding end, together with the flange, is folded back into contact with the stile member, for example by hammering. It has been found that there is a tendency for the rung to rotate slightly with respect to the stile member, thus causing a reduction in torsional rigidity of a ladder incorporating such a ladder stile. It is an object of the present invention to provide a method of joining a rung to a ladder stile member, whereby the above disadvantage may be overcome or at least mitigated. Accordingly, the present invention provides a method of joining a first member to a second member, which method comprises forming a hole through the second member, placing a drawing die on one surface of the second member so that the hole is located substantially centrally of a cavity of the drawing die, the cavity having a cross-section greater than the cross-section of the first member, and forcing a portion of the first member through the hole into the cavity so as to draw a part of the second member bounding the hole into the cavity, thereby forming a flange circumferential of the hole. For a better understanding of the present invention, and to show how the same may be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 shows a sectional view of a rung, a ladder stile member and a drawing die during a first stage of a method according to the invention, and Figure 2 shows the rung, stile member and drawing die of Figure 1 during a second stage of the method. Referring now to the drawings, a hole 1 is formed in a ladder stile member 2 by means of a punch and die (not shown) having matching profiles. A drawing die 3 having a cavity 4 is placed behind the hole 1, the cavity 4 being concentric with the hoie 1. A rung 5 is provided with a flange 6 and has a cross-section slightly smaller than that of the die cavity 4 and substantially larger than that of the hole 1. As shown in Figure 2, the rung 5 is forced through the hole 1, thereby drawing that part of the member 2 bounding the hole 1 into the cavity 4 to form a circumferential flange 7, which grips the rung 5. The flange 6 formed on the rung 1 abuts the surface of the member 2 opposite the drawing die. The drawing die is then removed and the protruding end 8 of the rung, together with the circumferential flange 7, is bent back into contact with the member 2, for example by hammering. Thus, a relatively secure fit is obtained between the rung 5 and the member 2, and the torsional rigidity of a ladder made with such a stile member and rung construction is improved compared with the prior art proposals discussed hereinbefore. CLAIMS

1. A method of joining a first member to a second member, which method comprises forming a hole through the second member, placing a drawing die on one surface of the second member so that the hole is located substantially centrally of a cavity of the drawing die, the cavity having a cross-section greater than the crosssection of the first member, and forcing a portion of the first member through the hole into the cavity so as to draw a part of the second member bounding the hole into the cavity, thereby forming a flange circumferential of the hole.

2. A method according to Claim 1, wherein the first member is of hollow cross-section.

3. A method according to Claim 2, which further comprises removing the drawing die and forming a joint between the part of the first member which extended into the cavity, the circumferential flange and the second member by bending the said part and the flange into contact with the second member.

4. A method according to any one of the preceding claims, wherein the first member is a metal rung for a ladder and the second member is a metal stile member for a ladder.

5. A method of joining a first member to a second member, substantially as hereinbefore described with reference to the accompanying drawings.

6. A joint whenever produced using the method of any one of the preceding claims.

7. A joint between a first member and a second member, substantially as hereinbefore described with reference to the accompanying drawings.

8. A ladder comprising a joint according to Claim 6 or 7.

9. Any novel feature or combination of features described herein.