WO1998051904A1

WO1998051904A1 - Apparatus for bending and cutting cable in rock bolting equipment

Info

Publication number: WO1998051904A1
Application number: PCT/FI1998/000396
Authority: WO
Inventors: Ossi Tienari
Original assignee: Sandvik Tamrock Oy
Priority date: 1997-05-14
Filing date: 1998-05-11
Publication date: 1998-11-19
Also published as: FI972071A0; FI106645B; CA2289642A1; DE69818859D1; AU7433298A; CA2289642C; EP1027529A1; ZA983950B; FI972071A; EP1027529B1

Abstract

An apparatus for bending and cutting a cable in a rock bolting equipment. The apparatus of the invention comprises a pressure fluid-driven bending piston (2) movable in the transverse direction of the cable, and on both sides of the bending piston (2) in the longitudinal direction of the cable (9) successive counter surfaces against which the cable (9) is pressed by the bending piston (2) to form a bend in the cable on both sides of the bending piston.

Description

APPARATUS FOR BENDING AND CUTTING CABLE IN ROCK BOLTING EQUIPMENT

The invention relates to an apparatus for bending and cutting cable in a rock bolting equipment comprising a frame with a conduit through which the cable is adapted to pass during the cutting; a cutting piston for cutting the cable, adapted to move in the transverse direction of the cable; in the travel direction of the cutting piston, on the opposite side of said conduit, a counter blade, against which the cutting piston presses the cable at the cutting stage to cut it; and pressure fluid spaces for moving the cutting piston in directions opposite to its travel direction.

In tunnel and mining jobs, the rock surface occasionally has to be reinforced to avoid collapsing. This is carried out by bolting the rock, a hole being first drilled into the rock, and a rock bolt then being fed into the hole and fastened by grouting with concrete or resin. In some cases short rigid bolts cannot be used, the holes being long, and consequently a suitably shaped steel cable, what is known as a cable bolt, is employed. Such a steel cable is pushed into the hole either by hand or nowadays by employing a separate cable feeding device. A problem in using cable bolts is that cable is usually supplied in spools and has to be cut in a suitable length on site. Furthermore, if the cable is pushed into an upwards extending hole, it tends to slip out of the hole before the grout has set. Although it is possible to cut the cable in a variety of ways, it is very cumbersome and the use of different hand tools causes stress and accident risks. Furthermore, keeping the cable in the hole requires either some kind of separate fastener or the use of a rapidly setting resin grout to make the cable lock into the hole at some point until the more generally used concrete has set.

Finnish patent application 831 ,481 teaches a rock bolting equipment with a pressure medium cylinder-driven cutting device provided with a fixed counter piece and a moving pressure medium cylinder-driven blade, and used for cutting a bolt by pressing the blade against the counter piece until the bolt is cut. Said publication further discloses a cable feeding device for bending a rigid bolt by pressing the feeding rollers of the feeding mechanism against one another to provide a bend in the bolt. However, this solution is not usable for cable bolts since cable is flexible and consequently no permanent change in shape is formed therein.

It is known to bend a cable by using crank arms which are moved by a pressure fluid cylinder and make the cable bend and stay in the hole by means of friction. However, in practice this has not proved to be very useful and in addition it is cumbersome to operate the separate bending and cutting devices which are located at a distance from one another. It is an object of the present invention to provide an apparatus for bending and cutting cable bolts by which the cable can be suitably bent so as to make it stay in the hole after insertion therein, by means of the friction achieved by the bending. It is a further object of the invention to provide an apparatus for bending and cutting by which cable fed from a spool can be cut at a suitable stage to achieve a cable bolt of the desired length.

The apparatus of the invention is characterized in that it comprises a bending piston arranged to move in the transverse direction of the cable to bend the cable, and pressure fluid spaces for moving the bending piston in directions opposite to the travel direction, and that in the longitudinal direction of the cable, at the opposite side of said conduit, both sides of the bending piston comprise successive counter surfaces against which the cable is pressed when being pressed by means of the bending piston so as to provide the cable with a bend on both sides of the bending piston between the counter surfaces and the surface of the bending piston pushing the cable. It is an essential idea of the invention that the same apparatus provides separately usable cutting and bending pistons which can be used independently of one another to achieve the desired function. Another essential idea of the invention is that it comprises a lead-through conduit through which the bolt cable is adapted to pass in such a way that during the entire feeding of the bolt the cable is located at the cutting piston and at the bending piston. It is an advantage of the apparatus of the invention that with the cable located at the right position for both cutting and bending, the desired procedure can be carried out by merely coupling a sufficient pressure fluid pressure to act on the desired piston. It is a further advantage of the invention that in addition to cable handling being simple and easy, the apparatus is also small and easily installable into the desired place. It is still a further advantage of the invention that implemented in this manner, the feeding hose for grout, e.g. concrete, can be fed through the apparatus via the same controls, the bolting end of the rock bolting apparatus not having to be moved from its posi- tion or turned to different positions during different bolting stages, but once it has been positioned at a hole, the whole grouting process can be carried out in the same position.

In the following the invention will be described in greater detail in the accompanying drawings, wherein

Figures 1a to 1 c show a schematic cross-section of an apparatus of the invention in a normal position and in a bending and cutting position, respectively, and

Figures 2a to 2c show a schematic cross-section of another apparatus of the invention in a normal position and in a bending and cutting position, respectively. Figure 1a shows schematically an apparatus for bending a cable bolt and cutting it in the desired length in the normal position of the apparatus. The apparatus comprises a frame 1 with a bending piston 2 and a cutting piston 3 moving therein. There is a separate first cylinder space 4 for the bending piston 2 and similarly a second cylinder space 5 for the cutting piston 3. In the travel direction of the cable, the pistons 2 and 3 are disposed movably in succession in a transverse direction with respect to the cable. A part 1a of the frame surrounding the bending piston 2 is provided with lead-through holes 6, through which the cable can be fed. The bending piston 2 further comprises an opening 2a which, the bending piston being in its rest position, i.e. the position shown in Figure 1a, is in alignment with the holes 6 and forms a conduit through which the cable can be fed, and, when no cable is present, through which e.g. the concrete feeding hose can pass. The upper edges of the holes 6 are bevelled towards the bending piston 2 and, correspondingly, the edges of the opening 2a in the bending piston 2 are bevelled and expand towards the outer surface of the piston. As to a more detail explanation of this, reference is made to Figure 1 b. A part 1 b of the frame surrounding the cutting piston 3 comprises similar holes 7, which are in alignment with the holes 6 in such a way that, with the pistons in their normal position as shown in Figure 1a, an almost continuous conduit is provided through the entire apparatus, through which even the cable, or when required, a concrete hose, can be pushed at a given stage of the bolting. In the present embodiment, the edge of the frame part 1 b facing the bending piston 2 comprises a counter blade 8 with a sharp cutting edge in the travel direction of the cutting piston 3. The end of the cutting piston 3, in turn, comprises a second cutting blade 3a, shaped such that, with the cutting piston 3 projecting upwards from the position shown in Figure 1 a, it leads a cable 9 suitably against the counter blade 8 and, with the move- ment advancing in this way, causes the cable 9 to be cut.

Figure 1 b shows schematically how a cable is bent by means of the bending piston 2. In Figure 1 b the bending is complete, whereby the cable 9 passing through the openings of the apparatus is pressed by the bending pis- ton 2 against bevelled counter surfaces 6a disposed at the upper edges of the openings 6 in the frame part 1a. Similarly the cable 9 is bent against the bevelled edges of the opening 2a in the bending piston 2, resulting in a permanent bend in the cable 9 by means of sufficient pressing force. The pressing is achieved by feeding into the cylinder space 4 of the bending piston 2 pressure liquid which forces the bending piston from the position shown in Figure 1a to the position shown in Figure 1 b. To restore the bending piston 2 to the position shown in Figure 1a, a shaft 4b is fixedly disposed in the cylinder space 4 with respect to the frame part 1 a and extends inside the bending piston 2, a piston with a dedicated cylinder space inside the bending piston 2 being arranged inside the bending cylinder 2. Pressure fluid can be fed into said cylinder space to push the bending piston 2 back downwards from the position shown in Figure 1 b. With the bending piston 2 back in the position shown in Figure 1a, the cable 9 can be moved forwards, fed into a hole in the rock, and the bending of the cable 9 can be repeated at suitable intervals. Figure 1c in turn shows a case where the bending piston 2 is in its normal position, corresponding to Figure 1 a, and the cable 9 can pass freely through the holes 6 and the opening 2a. For cutting the cable, pressure fluid has been fed into the cylinder space 5 of the cutting piston 3, into the space 5a between the piston part 3b of the cutting piston and the frame part 1 b, and in the figure the pressure fluid has pushed the cutting piston 3 upwards with respect to the position shown in Figure 1a. In this case the second cutting blade 3a at the upper end of the cutting piston 3 has pushed the cable 9 against the counter blade 8 forcing it to be cut. After cutting the cable, the cutting piston can be restored by supplying pressure fluid to the cylinder space part 5b above the piston part 3b in the figure, the pressure fluid moving the cutting piston 3 back to the position shown in Figure 1a.

Figures 2a to 2c in turn show another embodiment of the invention, resulting in a very compact structure requiring little space. In this embodiment the bending piston 2 and the cutting piston 3 are arranged one within the other and move coaxially in their longitudinal direction. The bending piston 2 is sleeve-like, its upper end being open in the middle and its lower end compris- ing a base 2b. Inside the bending piston 2, at its upper end is further a cutting piston 3 whose upper end comprises a cutting blade 3a on the side of the piston.

A fixed auxiliary piston 11 is further attached to the tubular frame 1 coaxially with the bending piston 2 and the cutting piston 3, an arm 11a of the auxiliary piston passing through the bottom 2b of the bending piston 2, leaving a first pressure fluid space 12 between the auxiliary piston 11 and the bending piston 2. Furthermore, an arm 11b on the other side of the auxiliary piston 11 extends inside the cutting piston 3, leaving a second pressure fluid space 13 between the cutting piston 3 and the auxiliary piston 11 , a pressure fluid conduit 13a passing from the second pressure fluid space through the auxiliary piston 11 and its arm 11a to the outside of the apparatus. A third pressure fluid space 14 is further disposed between the bending piston 2 and the cutting piston 3. The frame 1 has openings 6 and the bending piston 2 has corre- sponding openings 2c which, when the pistons are in the position shown in Figure 2a, form a continuous conduit through the apparatus for feeding a cable, or if desired, a concrete hose through the apparatus. The figure shows the upper edges of the openings 6 acting as the counter surfaces 6a and, similarly, the lower edges of the openings 2c of the bending piston 2, the edges being bevelled to make the cable bend reliably and without damage in the manner described in Figure 2b.

Figure 2b shows schematically how a cable is bent. For this purpose, pressure fluid has been led into the third cylinder space 14 between the bending piston 2 and the cutting piston 3 or the conduit leading thereto has been closed. Pressure fluid is similarly supplied to the second pressure fluid space 13. From the first pressure fluid space 12 the pressure fluid is allowed to be discharged to the pressure fluid container in a manner known per se. This makes the bending piston 2 move to the position shown in Figure 2b, wherein the cable 9 is pressed against the openings 2c of the bending piston 2 and the counter surfaces 6a of the openings 6 in the frame 1 , a permanent change in shape, i.e. a bend, being formed thereto. Once the bending is complete, the bending piston 2 is moved back to the position shown in Figure 2a by feeding pressure fluid into the first pressure fluid space 12 and letting the pressure fluid be discharged from the third pressure fluid space 13 to the pressure fluid container in a manner known per se.

Figure 2c in turn shows how a cable is cut. In this embodiment the first pressure fluid space is closed with no pressure fluid being led thereto or therefrom. As a result, the second pressure fluid space 13, when being fed with pressure fluid, tends to push the cutting piston 3 into the position shown in Figure 2c. At the same time, the pressure fluid is discharged from the third pressure fluid space 14 to the pressure fluid container in a manner known per se.

As the cutting piston 3 is pushed from the situation shown in Figure 2a upwards, it forces the cable 9 to be pressed between the cutting blade 3a and the counter blade 8, thus cutting the cable 9. The cutting piston 3 can be restored to the position shown in Figure 2a by feeding pressure fluid into the third pressure liquid space 14 and by similarly letting it be discharged to the pressure fluid container from the second pressure fluid space 13.

The invention has been described in the above description and the drawings only by way of example and is in no way restricted thereto. It is es- sential that the cutting and bending pistons are disposed in the same apparatus and the bending and cutting can be carried out in the desired manner.

Claims

CLAIMS:

1. An apparatus for bending and cutting cable in a rock bolting equipment comprising a frame (1) with a conduit through which the cable is adapted to pass during the cutting; a cutting piston (3) for cutting the cable, adapted to move in the transverse direction of the cable; in the travel direction of the cutting piston (3), on the opposite side of said conduit, a counter blade, against which the cutting piston presses the cable at the cutting stage to cut it; and pressure fluid spaces for moving the cutting piston (3) in directions opposite to its travel direction, characterized in that it comprises a bending piston (2) arranged to move in the transverse direction of the cable to bend the cable (9), and pressure fluid spaces for moving the bending piston in directions opposite to the travel direction, and that in the longitudinal direction of the cable (9), at the opposite side of said conduit, both sides of the bending piston comprise successive counter surfaces against which the cable is pressed when being pressed by means of the bending piston (2) so as to provide the cable with a bend on both sides of the bending piston (2) between the counter surfaces and the surface of the bending piston pushing the cable.

2. An apparatus as claimed in claim 1, characterized in that the bending piston (2) is provided with an opening parallel to said conduit, the opening being substantially concentric with said conduit when the bending piston is in its normal position.

3. An apparatus as claimed in claim 1 or 2, characterized in that the bending piston (2) and the cutting piston (3) are disposed side by side and move substantially in the same direction, and that both of them have dedi- cated separate cylinder spaces into which the pressure fluid spaces are formed.

4. An apparatus as claimed in claim 2, characterized in that the bending piston (2) and the cutting piston (3) are arranged one within the other and move coaxially with respect to one another.

5. An apparatus as claimed in claim 4, characterized in that the bending piston (2) is disposed in the cylinder space in the frame (1) and, correspondingly, the cutting piston (3) is disposed inside the bending piston (2), that is comprises inside the bending piston (2) an auxiliary piston, arranged by an arm through the bottom of the bending piston (2) to the frame (1) immobile with respect to the frame (1), the arm of the auxiliary piston extend- ing inside the cutting piston, and that it is provided with a first pressure liquid space between the auxiliary piston and the bottom of the bending piston (2), a second pressure fluid space in the space between the cutting piston (3) and the bending piston (2), and a third pressure fluid space in the space confined by the cutting piston (3) and the auxiliary piston and the bending piston and the arm of the auxiliary piston.

6. An apparatus as claimed in claim 4 or 5, characterized in that a cutting blade is fastened to the surface of the opening of the bending piston (2) opposite to the cutting piston (3), and, similarly, a second cutting blade is provided at the end of the cutting piston (3), the blades cutting the cable as it is pressed between them as the cutting piston (3) is pressed towards the upper end of the bending piston by means of pressure fluid.

7. An apparatus as claimed in any one of the preceding claims, characterized in that the diameter of said conduit is such that a feed- ing hose for grout, such as concrete, can be pushed through it when no cable is present in said conduit.