GB2213183A

GB2213183A - Fish-plates

Info

Publication number: GB2213183A
Application number: GB8823357A
Authority: GB
Inventors: Rex Barker; Gordon Mcfarlane Russell
Original assignee: Tool & Steel Products Ltd
Current assignee: Tool & Steel Products Ltd
Priority date: 1987-12-07
Filing date: 1988-10-05
Publication date: 1989-08-09
Anticipated expiration: 2008-10-05
Also published as: GB2213183B; GB8728539D0; GB8823357D0

Abstract

A fish-plate (14) for connecting together the adjacent ends of lengths of rolled steel joists (10,12) at an angle to each other, has adjoining portions at angles to each other for reception between the flanges of the respective R.S.J. sections, said portions having U-shaped configurations at opposite sides of a central section so that, in use of the fish-plate, the mutually remote side walls of the U-shaped configurations contact the internal surfaces of the flanges of the R.S.J. section whereby as the connection comes under load the fish-plate takes the stress and saves the bolts (16) from shear stresses. <IMAGE>

Description

Fish-plates.

The invention relates to fish-plates for connecting lengths of rolled steel joists together end to end to form an arch, in particular for connecting the rolled steel joists in a three piece flat or cambered top arch for a mine roadway support of the type generally used in profile cut roadways when using so-called retreat mining techniques.

When constructing a mine roadway support arch it is usual to use fish-plates to connect together adjacent lengths of rolled steel joist sections of which the arch is composed, that is to say fishplates which are pre-shaped to fit the particular R.S.J. section being used. The fish-plates are generally used in oppositely disposed pairs, each fish-plate 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.

Fish-plates as described above have been used to connect the lengths of rolled steel joists together in abutting end to end relationship. Consequently, the fish-plates have each been formed from a rectangular metal blank shaped by a pressing operation so that the finished plate has a flat central section, through which the bolt holes extend, and substantially U-shaped configurations at opposite sides of said central section.

The object of the invention is to provide a form of fish-plate which can be used for connecting together the adjacent ends of lengths of rolled steel joists which are to be connected together in a non-continuous manner, that is to say at an angle to each other as in the case of a mine roof support arch which is to be formed by three sections of R.S.J. comprising a pair of upstanding side supports and a horizontal length connected at its opposite ends to the respective side supports.

According to one aspect of the invention, there is provided a fish-plate for connecting adjacent lengths of R.S.J. sections at an angle to each other, the fish-plate having adjoining portions at angles to each other for reception between the flanges of the respective R.S.J. sections, each portion having a flat central section, through which extend holes for the reception of bolts which, in use of the fish-plate, will extend also through clearance holes in the webs of the R.S.J.

sections, and substantially U-shaped configurations at opposite sides of said central section the arrangement being such that, in use of the fishplate, the mutually remote side walls of the Ushaped configurations contact the internal surfaces of the flanges of the R.S.J. section whereby as the connection comes under load the fish-plate takes the stress and prevents the imposition of shear stresses on the bolts. The cross sectional shapes of the two portions at angles to each other may be the same for connecting together adjacent lengths of R.S.J. of like cross section. On the other hand, the cross sectional shapes of the two portions at angles to each other may be different for connecting together adjacent lengths of R.S.J.

of dissimilar cross section.

According to another aspect of the invention, there is provided a method of forming a fish-plate for connecting adjacent lengths of R.S.J. sections at an angle to each other, the method including the step of cutting an area of steel plate to form a suitable blank having adjoining portions at an angle to each other equal to the angle which is to be formed between the lengths of R.S;J. section which are to be joined together, and the subsequent step of pressing the blank to shape in suitable dies whereby the adjoining portions at an angle to each other are brought to a cross sectional shape to suit the shape of the R.S.J. section within which they are to be received, each having a flat central portion through which bolt holes extend and substantially U-shaped configurations at the opposite sides of said central section.

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 partsectional view of a connection between adjacent lengths of R.S.J. section, the joint being formed using fish-plates embodying the invention, Figure 2 is a perspective view of a fish-plate embodying the invention, and Figure 3 is a plan view of a metal blank from which the fish-plate has been pressed.

Referring now to Figure 1, 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, the - section 12 being one of a spaced pair of upstanding side Supports at the opposite sides of the roadway and the section 10 being a horizontal length connected at its opposite ends to the respective side supports.

As shown, the connection includes a pair of 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 clearance holes 20 in the webs 22 of the adjacent R.S.J.

sections.

Referring now in particular to Figures 2 and 3, these illustrate the shape to which each of the fish-plates is pre-shaped. Each fish-plate has been pressed from a blank of the shape shown in Figure 3, that is to say a flat plate of microalloyed steel having adjoining portions 11 and 13 at angles to each other equal to the angle which is to be formed between the lengths of R.S.J. section which are to be joined together by the fish-plate.

The adjoining portions of each blank have the holes 18 which in the finished fish-plate accommodate the bolts 16.

In being pressed to shape in suitable dies, the portions 11 and 13 of the blank are brought to the cross sectional shape shown in Figure 1, each portion having a flat central portion, through which the bolt holes 18 extend, and substantially U-shaped configurations at the opposite sides of said central section, the arrangement being such that, in use of the fish-plate, the mutually remote side walls of the U-shaped configurations contact the internal surfaces of the flanges of the R.S.J. section whereby, as the connection comes under load, the fish-plate takes the stress and prevents the imposition of shear stresses on the bolts. It is in fact preferable for a wedging action to take place as the bolts are tightened and the mutually remote side walls of the U-shaped configurations are clamped against the converging internal surfaces of the flanges of the R.S.J.

sections. However, even if this is not the case, by virtue of the fact that the bolt holes in the webs of the R.S.J. sections are clearance holes, movement of the fish-plate relative to the R.S.J.

section to which it is clamped will cause a jamming action to occur at the outer corners of the fishplate so that the imposition of shear stresses on the bolts will be prevented.

Thus there is provided a form of fish-plate which can be used for connecting together the adjacent ends of lengths of rolled steel joists which are to be connected together in a noncontinuous manner, that is to say at an angle to each other as shown in Figure 1. Such a .fishplate, being formed in a pressing operation, can be produced at lower cost than the more conventional forms of connectors produced by forging or made from rolled and fabricated sections. It is of lighter weight and can therefore be used with relative ease by a workman making a connection in the region of a mine roof when he will be working at arms length.

The angle at which the lengths of R.S.J. sections are to be joined together in the manner described will generally be somewhat greater than a right angle, that is to say in the region of 120 degrees to 135 degrees. The lengths of R.S.J. will generally be cut at an angle to form what may be termed a mitred connection and not at right angles as shown in Figure 1.

Claims

CLAIMS:

1. A fish-plate for connecting adjacent lengths of R.S.J. sections at an angle to each other, the fish-plate having adjoining portions at angles to each other for reception between the flanges of the respective R.S.J. sections, each portion having a flat central section, through which extend holes for the reception of bolts which, in use of the fish-plate, will extend also through clearance holes in the webs of the R.S.J. sections, and substantially U-shaped configurations at opposite sides of said central section the arrangement being such that, in use of the fish-plate, the mutually remote side walls of the U-shaped configurations contact the internal surfaces of the flanges of the R.S.J section whereby as the connection comes under load the fish-plate takes the stress and prevents the imposition of shear stresses on the bolts.

2. A fish-plate according to claim 1, in which the cross sectional shapes of the two portions at angles to each other are the same for connecting together adjacent lengths of R.S.J. of like cross section.

3. A fish-plate according to claim 1, in which the cross sectional shapes of the two portions at angles to each other are different for connecting together adjacent lengths of R.S.J. of dissimilar cross section.

4. A method of forming a fish-plate for connecting adjacent-lengths of R.S.J. sections at an angle to each other, the method including the step of cutting an area of steel plate to form a suitable blank having adjoining portions at an angle to each other equal to the angle which is to be formed between the lengths of R.S.J section which are to be joined together, and the subsequent step of pressing the blank to shape in suitable dies whereby the adjoining portions at an angle to each other are brought to a cross sectional shape to suit the shape of the R.S.J. -section within which they are to be received, each having a flat central portion through which bolt holes extend and substantially U-shaped configurations at the opposite sides of said central section.

5. A fish-plate for connecting adjacent lengths of R.S.J. sections at an angle to each other, the fish-plate being constructed and arranged, and adapted to be used, substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

6. A method of forming a fish-plate for connecting adjacent lengths of R.S.J. sections at an angle to each other, substantially as hereinbefore described.