GB2105763A - A strut - Google Patents

Abstract

A strut comprising a hollow- section metal bar (1). The opposite ends of the bar are flattened to form end sections (3, 4) each section being bent to extend substantially at right angles to the centre line of the bar and to project beyond the bar thickness. Each end section is formed with a hole (5 and 6) extending through the thickness thereof. <IMAGE>

Description

SPECIFICATION A strut This invention relates to a strut.

Many different types of strut are in use in various locations. In the erection of colliery arches the uprights of adjacent arch members are usually joined by struts extending transversely to the uprights and capable of acting both in compression and in tension. The most common form of strut for use in this field comprises a central element having end plates welded one to each end thereof, the end plates each being formed with a bolt hole whereby it can be bolted to the upright of the arch. Although generally adequate the weld does represent a potential point of weakness in such struts and of course the welding operation during manufacture of the strut is time consuming.

The object of the present invention is to provide a strut that is particularly suited for use in the support of colliery arches, but which nevertheless is capable of more general use, and that avoids the afore-mentioned disadvantages.

According to the invention a strut comprises a hollow-section metal bar, the opposite ends of which have been flattened to form end sections, each end section being bent to extend substantially at right angles to the centre line of the bar and to project beyond the bar thickness and each end section being formed with a hole extending through the thickness thereof.

The invention thus provides a one-piece strut made by a simple forming operation without the need for welding at the ends thereof. Because of the integral structure of the strut weak points which may be associated with welding are avoided, and manufacture may be effected more rapidly. In addition, the bend between the body and each end of the bar gives to the strut a desirable degree of elasticity both in tension and compression so catering for small amounts of relevant movement between members supported by the strut without detracting from the support function.

Preferably both end sections extend to the same side of the bar, although in some cases it may be desirable for the end sections to project beyond different sides of the bar. While bars of various different cross-sections may be used in the invention it is presently preferred that the bar be of square cross-section. Conveniently each end section is then flattened by inwardly pinching two opposed walls of the bars substantially at their mid-sections and compressing the other two opposed walls towards each other. In this way the end is flattened to have substantially the same width as the width of the bar, which is generally advantageous in end use. However, where end sections wider than the main body of the bar can be tolerated alternative methods of flattening the end sections can be used.

The metal chosen for the bar will usually be steel of appropriate gauge. For some purposes it may be desired to reinforce the end sections and such reinforcement may conveniently be effected by inserting a reinforcing member into the interior of the end section before flattening and bending this section. The reinforcement may, for example, be a short length of tube having the same crosssection as the bar and being a close fit within the bar. Alternatively the reinforcement may be a flat length of metal of appropriate dimension.

In order that the invention may be better understood specific embodiments of struts in accordance therewith will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is an isometric view of a first embodiment of strut; Figure 2 shows schematically the strut of Figure 1 in use; Figures 3 to 5 are cross-sectional views illustrating formation of end sections of the strut of Figure 1; Figure 6 is a view corresponding to Figure 5 of a second embodiment of strut; Figure 7 is a longitudinal cross-section through one end of the strut of Figure 6; and Figures 8 and 9 are views corresponding to Figure 5 of the ends of two further embodiments of strut.

Referring to Figure 1 there is shown a strut 1 comprising a hollow section metal bar. The strut includes a centre section 2 having the crosssection of the bar and two opposite end sections 3 and 4, each end section being bent to extend substantially at right angles to the centre line of the bar, the two sections projecting beyond the bar thickness to the same side of the bar. Each end section is formed with a hole, 5, 6, respectively extending through the thickness thereof.

Referring to Figures 3 to 5, the bar from which the strut is formed is a metal bar having a hollow square cross-section as shown in Figure 3. Each end is formed by inwardly pinching two opposed walls 7 and 8 of the end of the bar substantially at their mid-lines, while simultaneously compressing the other two opposed walls 9 and 10 towards each other. The cross-section of the bar at an intermediate stage of this flattening process is shown in Figure 4, which also indicates by arrows the directions of application of force to the bar.

The cross-section of the finally flattened end is shown in Figure 5, from which it will be seen that by adopting this particular method of flattening, the end section 3 is of substantially the same width as the centre part 2 of the strut. After flattening, each end is bent into the position shown in Figure 1 using an appropriate former.

The hole through the thickness of the end section may be formed either before or after the bending operation.

From the forgoing description it will be appreciated that the strut shown in Figure 1 is an integral structure formed from a single length of hollow-section metal bar. The strut may, for example, be used as shown in Figure 2 as a strut extending between adjacent uprights 11 and 12 of colliery arches, each upright being in the form of an I-section girder. Each end section is secured to the central web 1 3 of the upright by a bolt (not shown) passed through the hole such as 5 of the end section and through a corresponding hole in the upright, the bolt being secured by a nut. Struts used in this way, because of their integral structure, exhibit excellent strength property, both in tension and in compression.They also have the advantage that a limited degree of elasticity is allowed in the region of the bends, so accommodating small relative movement between adjacent uprights.

For certain uses it may be desirable to reinforce the ends of the strut, and a method of effecting such reinforcement is shown in Figures 6 and 7. A short length of hollow square-section tube 14 is inserted into the appropriate end of the bar 1 before the flattening process is commenced. The tube 1 4 is selected to be a close fit within the end of the bar. During the flattening process both the end section of the bar and the internal tube are simultaneously deformed and flattened so locking the tube within the bar to provide the required reinforcement to the end of the bar.As an alternative to using the square-section tube, reinforcement could be effected by inserting into the end of the bar a tube of circular or oval crosssection or one or more flat metal strips of appropriate dimension which are caused to become captive in the end of the bar during the flattening and bending process.

The flattening method illustrated with reference to Figures 3 to 5 is advantageous in that an end section is produced that is substantially of the same width as the main body of the strut. If, however this is not an important requirement then alternative flattening methods can be used, for example as illustrated in Figures 8 and 9. As shown in Figure 8 a bar of square cross-section is flattened by compressing the end of the bar along one diagonal of the bar as indicated by the arrows, allowing the points 15, 1 6 at the extremities of the other diagonal to move away from each other during such compression.In the method illustrated in Figure 9 a bar of square cross-section is flattened by compressing two opposed walls 17, 18 directly towards each other as indicated by the arrows, while allowing the other two opposed walls 19, 20 to bow outwardly away from each other.

It will be understood that hollow bars of crosssections other than square cross-section can also be used in the manufacture of struts according to the invention, the particular flattening process that is used being adopted to suit the crosssection selected.

Claims (Filed on 23 Aug 1982) 1. A strut comprising a hollow-section metal bar, the opposite ends of which have been flattened to form end sections, each end section being bent to extend substantially at right angles to the centre line of the bar and to project beyond the bar thickness and each end section being formed with a hole extending through the thickness thereof.

2. A strut according to claim 1 in which both end sections extend to the same side of the bar.

3. A strut according to claim 1 or claim 2 in which the bar is of square cross-section.

4. A strut according to claim 3 in which each end section is flattened by inwardly pinching two opposed walls of the bar substantially at their midsections and compressing the other two opposed walls towards each other.

5. A strut according to any one of the preceding claims having a reinforced end section.

6. A strut according to claim 5 insofar as dependent on claim 4 in which the reinforced end section is formed by inserting a reinforcing member into the interior of the end section before flattening and bending this section.

7. A strut according to claim 6 in which the reinforcement is a short length of tube having a cross-section similar to that of the bar and being a close fit within the bar.

8. A strut substantially as herein described with reference to Figures 1 to 5 of the accompanying drawings, or to these Figures as modified by Figures 6 and 7 or Figure 8 or 9 of the accompanying drawings.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. extending between adjacent uprights 11 and 12 of colliery arches, each upright being in the form of an I-section girder. Each end section is secured to the central web 1 3 of the upright by a bolt (not shown) passed through the hole such as 5 of the end section and through a corresponding hole in the upright, the bolt being secured by a nut. Struts used in this way, because of their integral structure, exhibit excellent strength property, both in tension and in compression. They also have the advantage that a limited degree of elasticity is allowed in the region of the bends, so accommodating small relative movement between adjacent uprights. For certain uses it may be desirable to reinforce the ends of the strut, and a method of effecting such reinforcement is shown in Figures 6 and 7. A short length of hollow square-section tube 14 is inserted into the appropriate end of the bar 1 before the flattening process is commenced. The tube 1 4 is selected to be a close fit within the end of the bar. During the flattening process both the end section of the bar and the internal tube are simultaneously deformed and flattened so locking the tube within the bar to provide the required reinforcement to the end of the bar.As an alternative to using the square-section tube, reinforcement could be effected by inserting into the end of the bar a tube of circular or oval crosssection or one or more flat metal strips of appropriate dimension which are caused to become captive in the end of the bar during the flattening and bending process. The flattening method illustrated with reference to Figures 3 to 5 is advantageous in that an end section is produced that is substantially of the same width as the main body of the strut. If, however this is not an important requirement then alternative flattening methods can be used, for example as illustrated in Figures 8 and 9. As shown in Figure 8 a bar of square cross-section is flattened by compressing the end of the bar along one diagonal of the bar as indicated by the arrows, allowing the points 15, 1 6 at the extremities of the other diagonal to move away from each other during such compression.In the method illustrated in Figure 9 a bar of square cross-section is flattened by compressing two opposed walls 17, 18 directly towards each other as indicated by the arrows, while allowing the other two opposed walls 19, 20 to bow outwardly away from each other. It will be understood that hollow bars of crosssections other than square cross-section can also be used in the manufacture of struts according to the invention, the particular flattening process that is used being adopted to suit the crosssection selected. Claims (Filed on 23 Aug 1982)

1. A strut comprising a hollow-section metal bar, the opposite ends of which have been flattened to form end sections, each end section being bent to extend substantially at right angles to the centre line of the bar and to project beyond the bar thickness and each end section being formed with a hole extending through the thickness thereof.

2. A strut according to claim 1 in which both end sections extend to the same side of the bar.

3. A strut according to claim 1 or claim 2 in which the bar is of square cross-section.

4. A strut according to claim 3 in which each end section is flattened by inwardly pinching two opposed walls of the bar substantially at their midsections and compressing the other two opposed walls towards each other.

5. A strut according to any one of the preceding claims having a reinforced end section.

6. A strut according to claim 5 insofar as dependent on claim 4 in which the reinforced end section is formed by inserting a reinforcing member into the interior of the end section before flattening and bending this section.

7. A strut according to claim 6 in which the reinforcement is a short length of tube having a cross-section similar to that of the bar and being a close fit within the bar.

8. A strut substantially as herein described with reference to Figures 1 to 5 of the accompanying drawings, or to these Figures as modified by Figures 6 and 7 or Figure 8 or 9 of the accompanying drawings.