WO1994003707A1

WO1994003707A1 - Apparatus for retaining a rock-breaking device in a hole

Info

Publication number: WO1994003707A1
Application number: PCT/GB1993/001613
Authority: WO
Inventors: George Henry Webb
Original assignee: George Henry Webb
Priority date: 1992-07-31
Filing date: 1993-07-30
Publication date: 1994-02-17
Also published as: ZA935472B; GB9216355D0; CN1090234A; AU4718993A

Abstract

Apparatus for retaining a device for breaking a mass of material in a hole in the material on activation comprises a tube (2) which houses retaining members comprising blocks (5) and hardened bits (6) and a wedge (14). The apparatus is connected to the device by a screw-threaded tube (4) which also serves to advance the wedge (14) in the housing once the tube has been fully screwed into the device. The advancing wedge (14) pushes the blocks (5) and bits (6) into contact with the mass of material to return the apparatus and device in that mass. Means may be provided for equalizing the lateral forces on the blocks in the event that the tube (2) is not centrally located in the hole in the mass of material.

Description

Apparatus for retaining a rock-breaking device in a hole

The present invention relates to apparatus for retaining a device for breaking a mass of material such as rock, coal, concrete and the like.

Such devices are well known. In use, a hole is formed in the mass of material to accommodate the device. When activated, carbon dioxide gas is released from the device and expands to break the mass of material in which the device is located. The device should be retained in the hole. Various methods of preventing the device from being propelled from the hole have been tried but none with complete success. An object of the present invention is to overcome or mitigate this problem.

According to the present invention there is provided apparatus for retaining a device for breaking a mass of material within an aperture in the mass of material comprising a housing, retaining members disposed to be advanced from the housing into the mass of material, means disposed in the housing for advancing the retaining members into the mass of material and means for connecting the housing to the device for breaking.

In a preferred embodiment of the invention, the means for advancing comprises a wedge which may be moved longitudinally within the housing. The retaining members comprise a pair of blocks which define holes into which respective carbide rock-drilling bits fit. As the wedge advances longitudinally, the blocks ride up respective sloping faces of the wedge advancing the bits into the walls of the aperture in the mass of material in which the apparatus is in use disposed, thus retaining the apparatus and any breaking device connected to it in the mass of material. The means for connecting the housing to the device comprises an externally screwthreaded tube which is screwed into a complementary internally screwthreaded aperture in the housing. This tube is screwed at its other end into a complementary internally screwthreaded aperture in the breaking device. When fully screwed into the breaking device rotation of the device advances the tube into the apparatus advancing in turn the wedge. In a modification, the wedge may be arranged to equalize the forces imposed by the retaining members in the event that the apparatus is not centrally located within the aperture in the mass of material. For this purpose the wedge is disposed on a spindle and connected to it by means of a grub screw. The spindle extends into an aperture in the externally screwthreaded tube and may move laterally within the aperture so that the wedge may centralise in response to the imbalanced lateral forces imposed on it. An anti-friction washer is disposed between the wedge and the tube and is held between the two by means of a spring concentrically surrounding the spindle and constrained to act between a stop on the spindle and a washer. The washer is variably fixed in position by means of a grub screw.

In order that the invention may be more clearly understood, embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:-

Figure 1 shows apparatus according to the invention disposed in a hole drilled in rock ready for use.

Figure 2 is a longitudinal cross-section of part of the apparatus of Figure 1,

Figure 3 is a plan view of the apparatus of Figure 2,

Figure 4 is an end elevational view of the apparatus of Figure 2 seen from the left-hand side.

Figures 5 - 11 show details of components of the apparatus of Figures 1 to 4.

Figure 12 is a sectional view of a modification of the apparatus of Figures 1 to 11, Figure 13 is a part sectional view of the modification of Figure 12 showing it in an operative position, and

Figure 14 is a cross sectional view taken along the line B-B in Figure 12.

Referring to Figure 1, an assembly comprising a device for breaking an apparatus for retaining the device is shown disposed in a hole drilled in the rock to be broken. The device comprises a Cardox (Registered Trade Mark) tube 3 and the apparatus a tube 2 joined by an externally screwthreaded tube 4 screwed at opposite ends respectively into complementary screwthreaded apertures in the tubes 2 and 3.

Referring to Figure 2 the end of the Cardox (Registered Trade Mark) tube 3 is shown in section. Liquified carbon dioxide CO- under pressure is contained by diaphragm 8 within the cavity 9. Diaphragm 8 is clamped in place by means of the threaded tube 4, which engages in threads provided in the end of the tube 3. The tube 2 is internally threaded at 12 into which the other end of tube 4 freely screws. In the cylindrical bore of tube 2 slides piston 10, to which is fixed a wedge 14. Two blocks 5 engage the opposite faces of the wedge 14 and protrude through diametrically opposite slots 15 provided in tube 2. Fitted in holes on the blocks 5 are carbide rock-drilling bits 6. Two are illustrated, but more may be used.

In operation tube 4 is first screwed tightly into internally screwthreaded aperture 13 in tube 3 against diaphragm 8, and its other end screwed a short way into tube 2 so that piston 10, resting against the end of tube 4, is in the position shown in Figure 2. Blocks 5 rest against the thin end of wedge 14 (their hatched positions) , and the points of bits 6 lie withift the diameter of tube 2. This assembly is then inserted into a hole drilled into the rock as shown in Figure 1 and tube 3 rotated as indicated by arrow A. Tube 4 is thus screwed into tube 2, pushing piston 10 and wedge 14 to position 14B in the direction of arrow B as shown in Figure 2. Thus blocks 5 ride up the wedge 14 and are expanded through the slots 15 in tube 2 in the direction of arrows C, until the points of bits 6 are forced into the rock, and the outer edges of blocks 5 are also clamped firmly against the rock. When the Cardox tube is fired gas bursts diaphragm 8 and emerges from tube 4 via holes 7. Some gas escapes through hole D and impinges on piston 10, its energy helping to force the wedge 14 still harder between blocks 5 thus increasing the clamping force. The diameter of D can be altered to vary the gas pressure on piston 10 as required.

To remove the tube from the hole after firing, tube

3 is rotated in the opposite direction to arrow A, thus withdrawing the wedge 14 and allowing blocks 5 to retract. Springs (not shown) engage with the blocks 5 and urge them to remain in contact with the wedge 14 at all times. The springs act in a direction opposite to arrows C. There is provision made (not shown) to pivotally connect tube 4 with piston 10, so that by unscrewing tube

4 from tube 2 the wedge 14 is drawn positively in a direction opposite to arrow B (Figure 2) .

In the above described apparatus, blocks 5 emerge equally from the slots in tube 2 as wedge 14 moves in the direction of arrow B, the bits 6 engaging opposite sides of the hole in the rock at the same instant providing the retaining apparatus is concentric with the hole. However should tube 2 be held to one side of the hole (because of a bent tube or a curved hole) then one tip will engage the rock first and impose a lateral force on the wedge 14, which is undesirable.

To obviate this a modification of the apparatus is described below with reference to Figures 12 to 14. Wedge 14 has drilled in it a hole to receive a spindle 26, this being held therein by a grub screw D located between flanges 24 and 25. Mounted freely on spindle 26 is an anti-friction washer 16 and spool 17 having a large internal diameter 18. A compression spring 19 exerts pressure between washer 16 and a stop 20. A grub screw 21 serves to lock spool 17 into a hole 22 drilled in tube 4. An anti-friction thrust washer 23 is disposed between wedge 14 and tube 4 which are held firmly together, but still pivotally connected, under the action of spring 19.

In operation, should wedge 14 be subjected to a side force, it will move in the direction of arrow E, whilst also being moved in the direction of arrow F by the rotation of tube 4, as described above.

Any other similar modification may be used to achieve the same object.

It will be appreciated that the above embodiments have been described by way of example only and that many variations are possible without departing from the scope of the invention.

Claims

1. Apparatus for retaining a device for breaking a mass of material within an aperture in the mass of material comprising a housing (2) , retaining members (5) disposed to be advanced from the housing into the mass of material, means disposed in the housing for advancing

(14) the retaining members (5) into the mass of material and means for connecting (4) the housing (2) to the device for breaking.

2. Apparatus as claimed in claim 1, in which the means for advancing comprises a wedge (14) disposed for longitudinal movement within the housing (2) .

3. Apparatus as claimed in claim 2, in which the retaining members comprise blocks (5) disposed to slide on the faces of the wedge (14) so that as the wedge advances the blocks are pushed outwardly towards the mass of material.

4. Apparatus as claimed in claim 3, in which the retaining members comprises bits (6) disposed in respective blocks (5) .

5. Apparatus as claimed in claim 4, in which the bits (6) are made of a hardened material.

6. Apparatus as claimed in any preceding claim, in which the means for connecting comprises an externally screwthreaded tube (4) which screws into an internally screwthreaded aperture in the housing (2) .

7. Apparatus as claimed in claim 6, in which the externally screwthreaded tube (4) is adapted to be screwed into a complementary internally screwthreaded aperture in the device and when screwed into that aperture to enable the tube (4) to be advanced in the housing (2) and to in turn advance the means (L4) for advancing.

8. Apparatus as claimed in any preceding claim, in which means (26) are provided for enabling the means for advancing (14) to move laterally with respect to the means for connecting (4) to enable lateral forces on the retaining members (5) to be equalized.

9. Apparatus as claimed in claim 8, in which resilient means are provided for urging the means for advancing against the means for connecting.

10. Apparatus as claimed in claim 8 or 9, in which the means for enabling comprises a spindle (26) which is disposed in the means for advancing and which is connected to the means for connecting but is laterally movable therein.

AMENDED CLAIMS

[received by the International Bureau on 24 January 1994 (24.01.94) original claim 5 deleted ; remaining claims amended and renumbered as claims 1-9 (2 pages)]

(14) the retaining members (5) into the mass of material and means for connecting (4) the housing (2) to the device for breaking, characterised in that the retaining members comprises bits (6) of hardened material.

4. Apparatus as claimed in claim 3, in which the bits (6) are disposed in respective blocks (5) .

5. Apparatus as claimed in any preceding claim, in which the means for connecting comprises an externally screwthreaded tube (4) which screws into an internally screwthreaded aperture in the housing (2) .

6. Apparatus as claimed in claim 5, in which the externally screwthreaded tube (4) is adapted to be screwed into a complementary internally screwthreaded aperture in the device and when screwed into that aperture to enable the tube (4) to be advanced in the housing (2) and to in turn advance the means (14) for advancing.

7. Apparatus as claimed in any preceding claim, in which means (26) are provided for enabling the means for advancing (14) to move laterally with respect to the means for connecting (4) to enable lateral forces on the retaining members (5) to be equalized.

8. Apparatus as claimed in claim 7, in which resilient means are provided for urging the means for advancing against the means for connecting.

9. Apparatus as claimed in claim 7 or 8, in which the means for enabling comprises a spindle (26) which is disposed in the means for advancing and which is connected to the means for connecting but is laterally movable therein.