GB2170835A - Fish plate for connecting lengths of rolled steel joist end to end to form an arch - Google Patents

Abstract

A fish plate 14 for connecting lengths of rolled steel joist end to end to form an arch, the fish plate being pre-shaped complementary to the cross sectional shape of the particular R.S.J. section, having a central section with bolt holes 18 through which, in use, bolts will extend to pass through similar holes in the webs of the adjacent ends of the R.S.J. sections, and having substantially U-shaped configurations (26 Fig. 5) at each side of said central section forming parallel flange slots in which the flanges of the R.S.J. sections can be located. So that the effective depth of section of the material of the fish plate is increased in the region of the return bend portions forming the flange slots, the return bend portions are formed with ripples or corrugations 30 Fig. 4. <IMAGE>

Description

SPECIFICATION Fish plate for connecting lengths of rolled steel joist end to end to form an arch The invention relates to fish plates for connecting lengths of rolled steel joist end to end to form an arch, in particular a mine roadway support arch.

When constructing a mine roadway support arch it is usual to use so-called wrap-around fish plates to connect together adjacent lengths of rolled steel joint sections of which the arch is composed, that is to say fish plates which are pre-shaped to the cross sectional shape of the particular R.S.J. section being used. Each fish plate has a central section having bolt holes through which bolts will extend to pass through similar holes in the webs of the adjacent ends of the R.S.J. sections which are to be connected together, and substantially U-shaped configurations at each side of said central section forming parallel flange slots in which the flanges of the R.S.J.

sections can be located. The wrap-around fish plates are used in oppositely disposed pairs with the adjacent ends of the R.S.J. sections to be connected together clamped between them.

When a mine roadway is being advanced, for speed and convenience of installation of the support arches it is generally required to place them in position in an already assembled condition, that is to say with the several lengths of rolled steel joist sections of which each arch is composed connected together end to end by the pairs of fish plates and by the nuts and bolts which extend through the fish plates and through the webs of the respective rolled steel joists. To enable them to be placed in position in the already assembled form, however, the bolts are left slack until the arch is in the required position and the fish plates are formed with slightly splayed outer portions so that the arch is to some extent manipulable into the required position.

The bolts can then subsequently be tightened to produce a strong and rigid arch. However, when the weight of the mine roof later subsides onto the arch, the forces imposed on the fish plates are tremendous and it is found that their outer portions tend to be deformed so that they are even further splayed out and the connection then fails. It is a particular problem that the need to form the fish plates with slightly splayed outer portions for the reasons stated above tend to give the straining ends of the R.S.J. sections a mechanical advantage in splaying the outer portions even further, this being compounded by the fact that the return bend portions of the fish plates forming the flange slots may well have been thinned down to some extent during the manufacturing process.

It is the object of the invention to provide a wrap-around fish plate for use in the manner described which will be very strong in the region of the bends around the flange slots but which can be producer at a competitive price.

According to one aspect of the invention, there is provided a wrap-around fish plate for connecting lengths of R.S.J. end to end, the fish plate having a central section and substantially U-shaped configurations at each side of said central section forming parallel flange slots in which the flanges of the R.S.J. sections can be located, outer portions of said Ushaped configurations being splayed out and return bend portions forming the flange slots having been formed with ripples or corrugations which have the effect of increasing the depth of section of the material of the fish plate in those regions, the ripples or corrugations running out where the return bends merge with said outer portions so that the latter are straight and free from ripples or corrugations.The fish plate may be such that not only is the effective depth of section increased in the regions of the return bends of the flange slots but also in the regions of the bends at the opposite sides of the flat central section by the presence of similar ripples or corrugations.

According to another aspect of the invention, there is provided a mine roadway support arch including a plurality of R.S.J. sections connected together end to end, each connection between adjacent lengths of R.S.J.

sections including a pair of wrap-around fish plates as described above clamped in oppositely disposed relation with portions of the adjacent lengths of R.S.J. sections between them.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is an exploded perspective view of a connection between adjacent lengths of R.S.J. section, the joint being formed using wrap-around fish plates embodying the invention, Figure 2 is a plan view of a wrap-around fish plate embodying the invention, Figure 3 is an end view, Figure 4 is a sectional view on the line 4-4 in Figure 3, and Figures 5 to 7 are views illustrating possible modifications which will be referred to.

Referring now to Figure 1 of the drawings, the connection there illustrated is shown to connect together adjacent lengths of R.S.J.

section 10 and 12 forming a part of a mine roadway support arch. As shown, the connection includes a pair of wrap-around fish plates, generally indicated 14,14, and four nut and bolt fastenings the bolts 16 of which extend through holes 18 in the fish plates and holes 20 in the webs 22 of the adjacent R.S.J. sections.

Referring now in particular to Figures 2 to 4, these illustrate the shape to which each of the wrap-around fish plates is pre-shaped.

Each fish plate has a flat central section 24, through which the holes 18 extend, and substantially U-shaped configurations generally indicated 26 at each side of said central section forming parallel flange slots 28 in which the flanges of the R.S.J. sections can be located.

However, as shown, the outer portions of said U-shaped configurations are slightly splayed out instead of being located in planes perpendicular to a plane containing the central section 24.

In Figure 4 it will be seen that, in the region of the return bend portions forming the flange slots, there have been formed a plurality of ripples or corrugations 30. These extend around the outside surfaces of the return bends and have the effect of significantly increasing the depth of section of the materral in those regions. However, it will be seen that the ripples or corrugations run out as the return bend portions merge with the straight but splayed portions which define the side walls of the flange slots. It is important that the outer portions although splayed out as shown, are straight and free from ripples or corrugations.

It has been found that, by virtue of the increased depth of section referred to, wraparound fish plates of the shape just described are significantly stronger in the region of the return bends of the flange slots than similar fish plates made from the same gauge material but without the ripples or corrugations.

Consequently, it has been found possible to produce the inventive fish plates from a lighter gauge of material than hitherto without any significant decrease in strength, this then re sulting in a substantial saving in manufacturing costs. As previously stated, it is, however, important that the outer portions, although splayed out, are straight and free from ripples or corrugations since it will be understood that when a connection has been made and the arch concerned is under load each fish plate will be under tension on one side and under compression on the other. The pres ence of ripples or corrugations along the out ermost edges would therefore weaken the connection.

In Figure 5 there is illustrated a possible modification of the wrap-around fish plate de scribed above, the modification residing in the fact that not only has the effective depth of section been increased in the region of the return bends of the flange slots but also in the regions of the bends at the opposite sides of the flat central section by the presence of similar ripples or corrugations. It will be seen that in this instance these similar ripples or corrugations are shown to run out in the regions where the bends merge with the flat portions at either side of them. However, in Figures 6 and 7, which are views similar to Figure 3, it will be seen that in further possible modifications the ripples or corrugations may gradually run out down the flat portions to either side of the return bends (as shown in Figure 6) or in fact can extend across the central section of the fish plate (as shown in Figure 7) ideally midway between the holes 18. In both cases of course the ripples or corrugations run out where the return bends merge with the outer portions so that the latter are straight and free from ripples or corrugations.

Claims (4)

1. A wrap-around fish plate for connecting lengths of R.S.J. end to end, the fish plate having a central section and substantially Ushaped configurations at each side of said central section forming parallel flange slots in which the flanges of the R.S.J. sections can be located, outer portions of said U-shaped configurations being splayed out and return bend portions forming the flange slots having been formed with ripples or corrugations which have the effect of increasing the depth of section of the material of the fish plate in those regions, the ripples or corrugations running out where the return bends merge with said outer portions so that the latter are straight and free from ripples or corrugations.

2. A wrap-around fish plate according to claim 1, in which not only is the effective depth of section increased in the regions of the return bends of the flange slots but also in the regions of the bends at the opposite sides of the flat central section by the presence of similar ripples or corrugations.

3. A mine roadway support arch including a plurality of R.S.J. sections connected together end to end, each connection between adjacent lengths of R.S.J. sections including a pair of wrap-around fish plates, each according to either one of the preceding claims, in oppositely disposed relation with portions of the adjacent lengths of R.S.J. sections between them.

4. A wrap-around fish plate for connecting lengths of R.S.J. end to end, the fish plate being formed substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.