METHOD OF MANUFACTURE

FIELD OF THE INVENTION

This invention relates to an expandable rock bolt arrangement and related method of manufacture, and in particular to an integral, self-drilling rock bolt.

BACKGROUND TO THE INVENTION

Expandable rock bolts, such as the Swellex™ or HydroBolt™ rock bolt systems, are widely used in the mining and tunnelling industries. The Swellex™ rock bolt, for example, comprises a welded tube folded on itself and sealed at one extremity, which is expandable within a drilled hole using a high-pressure water flow provided by a pump. The expansion of the bolt inside the drilled hole creates a friction and interlocking anchor. In use, an operator drills a hole in the rock, inserts the bolt and then inflates it to a pre-determined pressure using the pump. One of the main shortcomings with this traditional rock bolt system is that it involves a 2-step procedure, namely the drilling of a hole, and then the subsequent insertion of the rock bolt.

The broad idea of providing an integral, self-drilling rock bolt, in which the rock bolt itself is used to drill into rock, thus defining a 1 -step procedure, is not new. However, there are several practical difficulties that need to be addressed, which have not been properly addressed to date, and which the present invention aims to address.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided an expandable rock bolt arrangement comprising: an expandable elongate tube defining a leading end and a trailing end; a first tube portion extending from the leading end of the elongate tube, with a cutting bit being fittable to the first tube portion, so that upon rotation of the elongate tube, the rock bolt arrangement can be drilled into rock; and an outlet valve fitted within or to the first tube portion, the outlet valve comprising a valve body, a valve seal and a valve seat, so that during the drilling of the rock bolt arrangement into rock, liquid can enter the expandable elongate tube through the trailing end and exit through the outlet valve to flush cuttings and cool the cutting bit, under relatively low pressure in which case the outlet valve is in an open position, with the valve seat being spaced apart from the valve seal, and once drilled to the required depth into the rock, the pressure of the liquid can be increased, which in turn causes the valve to move to a closed position, in which the valve seat sealingly abuts against the valve seal, thereby enabling the pressure of the liquid within the expandable elongate tube to increase accordingly, so as to cause the expandable elongate tube to expand so as to grippingly engage the drilled hole.

In an embodiment, a first reinforcing sleeve is fitted over the interface between the first tube portion extending from the leading end of the elongate tube, so as to cover at least a portion of the first tube portion and a portion of the leading end of the elongate tube.

In an embodiment, the first reinforcing sleeve defines at least one elongate seam, but preferably two elongate seams spaced 180 degrees apart, which gets welded to the inner/underlying first tube portion and adjacent elongate tube. In addition, the ends of the first reinforcing sleeve are also welded to the inner/underlying first tube portion and adjacent elongate tube.

In an embodiment, the first tube portion comprises a spiral tube to which the cutting bit can be fitted.

In an embodiment, the expandable rock bolt arrangement comprises a second tube portion extending from the trailing end of the elongate tube.

In one version, but only if and when required, an inlet valve can be fitted within or to the second tube portion, with a hose coupling adaptor being fitted to the inlet valve to enable liquid to be pumped into the expandable elongate tube. ln an embodiment, a second reinforcing sleeve is fitted over the interface between the second tube portion extending from the trailing end of the elongate tube, so as to cover at least a portion of the second tube portion and a portion of the trailing end of the elongate tube.

In an embodiment, the second reinforcing sleeve defines at least one elongate seam, but preferably two elongate seams spaced 180 degrees apart, which gets welded to the inner/underlying second tube portion and adjacent elongate tube. In addition, the ends of the second reinforcing sleeve are also welded to the inner/underlying second tube portion and adjacent elongate tube.

In an embodiment, the second tube portion comprises a spiral tube to enable the second tube portion, and thus the expandable rock bolt arrangement, to be secured to a drilling machine so as to rotatingly drill rock bolt arrangement into rock.

In an embodiment, the valve seal is made from a polyurethane material, or any other synthetic material, to enable the valve seal to act as both a spring and a seal as the valve moves between the open and closed positions.

According to a second aspect of the invention there is provided a method of assembling an expandable rock bolt arrangement, the method comprising: providing an expandable elongate tube defining a leading end and a trailing end; securing a first tube portion to the leading end of the elongate tube, to which a cutting bit can be fitted, so that upon rotation of the elongate tube, in use, the rock bolt arrangement can be drilled into rock; and fitting an outlet valve within or to the first tube portion, the outlet valve comprising a valve body, a valve seal and a valve seat, so that during the drilling of the rock bolt arrangement into rock, liquid can enter the expandable elongate tube through the trailing end and exit through the outlet valve to flush cuttings and cool the cutting bit, under relatively low pressure in which case the outlet valve is in an open position, with the valve seat being spaced apart from the valve seal, and once drilled to the required depth into the rock, the pressure of the liquid can be increased, which in turn causes the valve to move to a closed position, in which the valve seat sealingly abuts against the valve seal, thereby enabling the pressure of the liquid within the expandable elongate tube to increase accordingly, so as to cause the expandable elongate tube to expand so as to grippingly engage the drilled hole.

In an embodiment, the method comprises fitting a first reinforcing sleeve over the interface between the first tube portion extending from the leading end of the elongate tube, so as to cover at least a portion of the first tube portion and a portion of the leading end of the elongate tube.

In an embodiment, the first reinforcing sleeve defines at least one elongate seam, but preferably two elongate seams spaced 180 degrees apart, which gets welded to the inner/underlying first tube portion and adjacent elongate tube. In addition, the ends of the first reinforcing sleeve are also welded to the inner/underlying first tube portion and adjacent elongate tube.

In an embodiment, the method comprises fitting a second tube portion to the trailing end of the elongate tube.

In one version, but only if and when required, the method comprises fitting an inlet valve within or to the second tube portion. In use, a hose coupling adaptor may be fitted to the inlet valve to enable liquid to be pumped into the expandable elongate tube.

In an embodiment, the method comprises fitting a second reinforcing sleeve over the interface between the second tube portion extending from the trailing end of the elongate tube, so as to cover at least a portion of the second tube portion and a portion of the trailing end of the elongate tube.

In an embodiment, the second reinforcing sleeve defines at least one elongate seam, but preferably two elongate seams spaced 180 degrees apart, which gets welded to the inner/underlying second tube portion and adjacent elongate tube. In addition, the ends of the second reinforcing sleeve are also welded to the inner/underlying second tube portion and adjacent elongate tube.

In an embodiment, the second tube portion comprises a spiral tube to enable the second tube portion, and thus the expandable rock bolt arrangement, to be secured to a drilling machine so as to rotatingly drill rock bolt arrangement into rock. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a side view of an expandable rock bolt arrangement according to a first version the present invention;

Figure 2 shows a cross-sectional side view of the expandable rock bolt arrangement shown in Figure 1 ;

Figure 3A shows a detailed view of a leading end of the expandable rock bolt arrangement shown in Figure 2;

Figure 3B shows a detailed view of a trailing end of the expandable rock bolt arrangement shown in Figure 2;

Figure 4 shows a top view of a reinforcing sleeve for use at both a leading end and a trailing end of an expandable elongate tube used in the expandable rock bolt arrangement of the invention;

Figure 5 shows a side view of an expandable rock bolt arrangement according to a second version the present invention;

Figure 6 shows a cross-sectional view of an expandable elongate tube of the rock bolt arrangement shown in Figures 1 and 5, taken along line A-A of the rock bolt arrangement shown in Figure 5;

Figure 7 shows a perspective view of an outlet or leading end portion of the rock bolt arrangement shown in Figure 5;

Figure 8 shows a cross-sectional, detailed side view of the outlet end of the expandable rock bolt arrangement shown in Figure 5; and

Figure 9 shows detailed views of an outlet valve used in the outlet end of the expandable rock bolt arrangement shown in Figure 5, and in particular three different seal designs that may be used. DET AILED DESCRIPTION OF THE DRAWINGS

Referring first to Figures 1 to 4 of the accompanying drawings, an expandable rock bolt arrangement 10 is shown, the arrangement 10 comprising an expandable elongate tube 12, made from a ductile material, the tube 12 defining a leading end 14 and a trailing end 16. The elongate tube 12 comprises a welded tube folded on itself, of the type shown in Figures 6 and 7. As described above and in more detail further below, the tube 12 is arranged to expand or inflate within a drilled hole, to create a friction and interlocking anchor.

A first tube portion 18, typically in the form of a spiral tube, as best shown in Figure 1 , extends from the leading end 14 of the elongate tube 12. Typically, the spiral tube 18 is welded to the leading end of the elongate tube 12, as indicated by weld line 20 in Figure 3A. In use, a cutting bit (not shown) is secured to the first tube portion 18, so that upon rotation of the elongate tube 12, the rock bolt arrangement 10 can be drilled into rock, as will be described in more detail further below. This arrangement ensures that the rock bolt arrangement 10 is self-drilling, thus providing a 1 -step procedure.

An outlet valve 22 is fitted within the first tube portion 18, the outlet valve 22 comprising a valve body 24, a valve seal 26 and a valve seat 28 (typically in the form of a pin). In use, during the drilling of the rock bolt arrangement 10 into rock, water can enter the expandable elongate tube 12 through the trailing end 16 and exit through the outlet valve 22 to flush cuttings and cool the cutting bit. This is typically done under relatively low pressure, with the outlet valve 22 staying in an open position, with the valve seat 28 being spaced apart from the valve seal 26.

Once the rock bolt arrangement 10 has been drilled to the required depth into the rock, the pressure of the water can be increased, which in turn causes the outlet valve 22 to move to a closed position. In the closed position, the valve seat 28 sealingly abuts against the valve seal 26, thereby enabling the pressure of the water within the expandable elongate tube 12 to increase accordingly. This increase in pressure in turn causes the expandable elongate tube 12 to expand radially so as to grippingly engage the drilled hole.

In an embodiment, the valve seal 26 is made from a polyurethane material (or any other synthetic material) to enable the valve seal 26 to act as both a spring and a seal as the valve 22 moves between the open and closed positions. To provide the necessary strength and support, the rock bolt arrangement 10 comprises a first reinforcing sleeve 30 fitted over the interface between the first tube portion 18 extending from the leading end 14 of the elongate tube 12, so as to cover at least a portion of the first tube portion 18 and a portion of the leading end 14 of the elongate tube 12, as best shown in Figure 3A.

As best shown in Figures 1 and 4, the first reinforcing sleeve 30 defines at least one elongate seam 32, but preferably two elongate seams spaced 180 degrees apart. These seams 32 get welded to the inner/underlying first tube portion 18 and adjacent elongate tube 12. In addition, the ends of the first reinforcing sleeve 30 are also welded to the inner/underlying first tube portion 18 and adjacent elongate tube 12, as indicated by transversely extending weld lines 34 and 36.

Turning now to the trailing end 16 of the expandable elongate tube 12, the expandable rock bolt arrangement 10 comprises a second tube portion 50 extending from the trailing end 16 of the elongate tube 12. The second tube portion 50 also takes the form of a spiral tube, as best shown in Figure 1 , which gets welded to the trailing end 16 of the elongate tube 12, as indicated by weld line 52 in Figure 3B.

In one version, but only if and when required, an inlet valve 54 (typically, a one-way inlet valve) can be fitted within or to the second tube portion 50. A hose coupling adaptor (not shown) may be fitted to the inlet valve 54 to enable water to be pumped into the expandable elongate tube 12, as described above. In use, once the elongate tube 12 has been sufficiently radially expanded, the supply of pressurised water is stopped, with the one-way inlet valve 54 in turn ensuring that the elongate tube 12 remains in its expanded/inflated state.

In one version, the inlet valve 54 is substantially similar in construction to the outlet valve 22. In particular, the inlet valve 54 may comprise a valve body 70, a valve seal 72 and a valve seat 74 (typically also in the form of a pin). In use, water can enter the inlet valve 54, with the valve seat 74 being urged away from the valve seal 72, but prevents water from exiting as a result of the valve seat 72 sealingly abutting against the valve seal 72.

As with valve seal 26, the valve seal 72 is made from a polyurethane material (or any other synthetic material) to enable the valve seal 72 to act as both a spring and a seal as the valve 54 moves between the open and closed positions. A second reinforcing sleeve 56 is fitted (welded, typically) over the interface between the second tube portion 50 extending from the trailing end 16 of the elongate tube 12, so as to cover at least a portion of the second tube portion 50 and a portion of the trailing end 16 of the elongate tube 12. This is best shown in Figure 3B.

As with the first reinforcing sleeve 30, the second reinforcing sleeve 56 defines at least one elongate seam 58, but preferably two elongate seams spaced 180 degrees apart, which gets welded to the inner/underlying second tube portion 50 and adjacent elongate tube 12. In addition, the ends of the second reinforcing sleeve 56 are also welded to the inner/underlying second tube portion 50 and adjacent elongate tube 12, as indicated by transversely extending weld lines 60 and 62.

The spiral second tube portion 50 is in use secured to a drilling machine so as to rotatingly drill the rock bolt arrangement 10 into rock.

Turning now to Figures 5 to 9, another version of an expandable rock bolt arrangement 100 is shown. The arrangement 100 comprises an expandable elongate tube 12, which is substantially similar to the elongate tube 12 described above with reference to Figures 1 to 4. The elongate tube 12 is made from a ductile material, and defines an outlet or leading end 102 and an inlet or trailing end 104. The elongate tube 12 comprises a welded tube folded on itself, to define a substantially C-shaped body, as best shown in Figures 6 and 7; this tube 12 is known in the field as a Swellex™ tube.

A first tube portion 106, typically in the form of a spiral tube, as best shown in Figures 5 and 7, extends from the leading end 102 of the elongate tube 12. Typically, the spiral tube 106 is welded to the leading end 102 of the elongate tube 12, as indicated by weld line 108 in Figure 8. In use, a cutting bit (not shown) is secured to the first tube portion 106, so that upon rotation of the elongate tube 12, the rock bolt arrangement 100 can be drilled into rock, as described above.

An outlet valve 1 10 is fitted within the first tube portion 106, and is typically welded to the end of the first tube portion 106. As best shown in Figures 8 and 9, the outlet valve 1 10 comprises a valve body or housing 1 12, defining a working chamber 1 14 and an opening 1 15 for receiving water under pressure, in use. The valve body 1 12 has an internally threaded end 1 16 to receive a corresponding threaded top screw component 1 18 having a protruding end member 120. The valve body 1 12 houses a valve seat 122 (typically in the form of a pin), having a support base 124, a circular locator 126 extending from the support base 124 and an elongate, triangular pin element 128. The circular locator 126 supports any one of three possible valve seals 130.1 , 130.2 and 130.3.

Valve seal 130.1 is a circular valve seal, valve seal 130.2 is also a circular valve seal but with a pair of opposite flat faces, and a valve seal 130.3 is a substantially triangular valve seal with flattened faces at each of its three apexes.

The protruding end member 120 has notches 132 to enable the threaded top screw component 1 18 to be screwed into the internally threaded end 1 16 of the valve body 1 12.

The operation of the rock bolt arrangement 100 is substantially the same as the rock bolt arrangement 10 as described above, and will thus not be repeated here. However, Figure 9 shows notches 134 on the upper edges of the valve seals 130.1 , 130.2 and 130.3. In use, when the valve seals 130.1 , 130.2 and 130.3 are pressed up against the top screw component 1 18 under pressure, these notches allow water to bypass at lower pressures, but to seal at relatively higher pressures. In this regard, the valve seals 130.1 , 130.2 and 130.3 are made from a polyurethane material (or any other synthetic material) to enable them to act as both a spring (at lower pressures) and a seal (at higher pressures) as the valve 1 10 moves between opened and closed positions.

To provide the necessary strength and support, the rock bolt arrangement 100 comprises a first reinforcing sleeve 140 fitted over the interface between the first tube portion 106 extending from the leading end 102 of the elongate tube 12, so as to cover at least a portion of the first tube portion 106 and a portion of the leading end 102 of the elongate tube 12, as best shown in Figure 8. In one version, the portion of the first reinforcing sleeve 140 over the elongate tube 12 is substantially cylindrical, whereas the portion of the first reinforcing sleeve 140 over the first tube portion 106 tapers slightly towards the first tube portion 106.

The first reinforcing sleeve 140 defines at least one elongate seam 142, but preferably two elongate seams spaced 180 degrees apart. These seams 142 get welded to the inner/underlying first tube portion 106 and adjacent elongate tube 12, along weld line 144. In addition, the ends of the first reinforcing sleeve 140 are also welded to the inner/underlying first tube portion 106 and adjacent elongate tube 12, as indicated by transversely extending weld lines 146 and 148, respectively.

Turning now to the trailing end 104 of the expandable elongate tube 12, as shown in Figure 5, the expandable rock bolt arrangement 100 comprises a second tube portion 150 extending from the trailing end 104 of the elongate tube 12. The second tube portion 150 also takes the form of a spiral tube, which gets welded to the trailing end 104 of the elongate tube 12, at the interface indicated by arrow 152. A second reinforcing sleeve 154 is fitted (welded, typically) over the interface 152 between the second tube portion 150 extending from the trailing end 104 of the elongate tube 12, so as to cover at least a portion of the second tube portion 150 and a portion of the trailing end 104 of the elongate tube 12. As with the first reinforcing sleeve 140, the second reinforcing sleeve 154 defines at least one elongate seam 156, but preferably two elongate seams spaced 180 degrees apart, which gets welded to the inner/underlying second tube portion 150 and adjacent elongate tube 12, along weld line 158. In addition, the ends of the second reinforcing sleeve 154 are also welded to the inner/underlying second tube portion 150 and adjacent elongate tube 12, as indicated by transversely extending weld lines 160 and 162, respectively.