GB2324152A

GB2324152A - Bore hole measuring device

Info

Publication number: GB2324152A
Application number: GB9807584A
Authority: GB
Inventors: Kevin Marshall Heywood
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-04-10
Filing date: 1998-04-08
Publication date: 1998-10-14
Anticipated expiration: 2018-04-08
Also published as: GB9807584D0; GB9707292D0; GB2324152B

Abstract

A device for measuring the bearing and inclination of a bore hole for use in quarrying comprises a tube 11 which is adapted to be fitted into the top of a bore hole 3 in a quarry face 1 with an upper part projecting from the bore hole. An illumination device in the form of a torch 27 is lowered down the bore hole 3 by a tape 26 and a unit 45 is then fitted to the top of the tube 11. The unit includes a clinometer 25 which is aligned with a beam of light from the torch, a device for measuring the angle of inclination of the bore hole 3, a compass for indicating the direction of the bore hole and a level for indicating when the compass is level. The device enables the amount of explosive needed for quarrying to be accurately determined because the angle of inclination and direction of the bore hole can be accurately measured. Means may be provided for adjusting the angle of inclination of the unit 45 with respect to the tube 11.

Description

Title: BORE HOLE MEASURING DEVICE This invention relates to improvements in quarrying and is particularly concerned with the drilling of bore holes for blasting rock from the rock face of a quarry.

When stone is to be quarried, it is necessary to drill bore holes, usually 105mm in diameter, from the top of the face to just below floor level, some three to four metres back from the crest of the rock face and parallel to it. Quarry face height and therefore bore hole depth varies, most commonly, between 15 metres and 25 metres. If the axis of the bore hole deviates from the parallel, or off to one side, and this is not detected, the result can prove extremely hazardous. For example, a bore hole drilled 3.5 metres back from the crest of a rock face could finish up with as little as 0.5 metres of cover at the toe. Should the explosives to be used be calculated for the burden at the top of the hole, and if no allowance is made for the area of reduced cover at the bottom of the hole, then this could result in the bore hole being seriously overcharged. If fired, there is every likelihood of flyrock shooting up into the air and possibly causing injury and damage.

The present invention aims to provide a solution to the above-described problem.

According to the invention, there is provided a device for measuring the bearing and inclination of a bore hole, said device comprising a tube adapted to be fitted into the top of a bore hole and to extend substantially parallel to the axis of the bore hole with an upper part projecting from the bore hole, an illumination device and means for lowering the said illumination device down the bore hole, a unit adapted to be mounted on the upper part of the tube for measuring the angle of inclination of the bore hole, a compass for measuring the direction of the bore hole and a level for indicating when the compass is substantially horizontal.

According to one embodiment of the invention, the unit for measuring the angle of inclination is mounted on a casing which is adapted to be rotatably mounted in or on the upper part of the tube. The casing may be mounted in the upper part of the tube by means of a tubular member in the form of a spigot.

Alternatively, the casing may take the form of a cap which is rotatably mounted in a ring which in turn is adjustably mounted at the upper part of the tube.

Preferably, the ring is provided with a chamfered edge which is engageable with a similar chamfered edge of a tube section, said tube section being adapted to be received in the upper part of the tube.

Adjustment means are desirably provided for adjusting the angle of inclination of the ring with respect to the tube section. Preferably, the adjustment means comprise a plurality of plates secured to the tube section and a corresponding number of screw adjusters mounted on the ring, each screw adjuster being provided with means which are engageable with a respective one of the plates.

Each screw adjuster may be engageable with a corresponding screw-thread provided in a respective bracket secured to the ring and may extend through an aperture in the associated plate, terminating in a ball which is engageable with the said associated plate. Further, each screw adjuster may be provided with a hand wheel for turning the adjuster.

The plates are desirably equi-spaced around the tube and the screw adjusters are desirably equi-spaced around the ring. Preferably three plates and three screw adjusters are provided.

The casing is preferably equipped with a handle to facilitate rotation of the casing with respect to the tube.

According to a preferred embodiment of the invention, the level and compass are mounted on a bracket which is pivotally mounted on the casing. Preferably, the bracket is substantially L-shaped with the level and compass being mounted on one limb while the other limb incorporates the unit for measuring the angle of inclination in the form of a protractor which is pivotally mounted on the casing by means of a pin. A line is desirably engraved or otherwise marked on the casing by means of which angles can be read from the protractor.

In addition, the unit for measuring the angle of inclination may comprise a clinometer mounted on the casing.

The tube is desirably provided, intermediate its ends, with stops to prevent the tube from falling down a bore hole. The tube may further be provided with one or more handles to facilitate handling and positioning of the tube in a bore hole.

The illumination device preferably takes the form of a torch and the means for lowering the torch down a bore hole may comprise a tape or line.

The invention will now be described in detail, by way of example, with reference to the drawings, in which: Fig. 1 is a side elevation of one embodiment of a measuring device according to the invention; Fig. 2 is a plan view of the device shown in Fig. 1 to an enlarged scale; Fig. 3 is a front view of the upper end of the device shown in Figs. 1 and 2; Fig. 4 is a diagrammatic representation showing the device illustrated in Figs. 1 to 3 in use; Fig. 5 is a diagrammatic representation of a second embodiment of a device according to the invention in use; Fig. 6 is a part-disassembled side elevation of the device shown in Fig. 5; Fig. 7 is a front view, to an enlarged scale, of the upper part of the device shown in Fig. 6; Fig. 8 is a vertical section taken on the line Vill-Vin in Fig. 7 in the direction of the arrows; and Fig. 9 is a plan view of one of the plates secured to a tube section of the device shown in Figs. 5 to 8.

In the drawings, like parts are denoted by like reference numerals.

Reference will first be made to Figs. 1-3 of the drawings in which a measuring device according to the present invention comprises a tube 11 which is adapted to be fitted in and to extend down into a bore hole 3 in a quarry face 1. The tube has a diameter which is only slightly less than that of the bore hole so that it is a close fit in the hole. A pair of stops 12 are provided on the tube 11, intermediate the ends thereof, to prevent the tube from slipping down the hole.

The stops are arranged in use to rest on the top 2 of the quarry when the tube 11 is inserted in a bore hole 3 as shown in Fig. 4 of the drawings.

A pair of handles 13 are mounted on the tube 11 adjacent to one end thereof which, in use, is intended to be at the upper end of the device. A tubular member in the form of a spigot 14 extending from a casing 15 is adapted to be inserted into the upper end of the tube 11 and to be a fairly close fit therein. A handle 16 extends from one side of the casing 15 and an L-shaped bracket 17 is pivotally mounted on the other side of the casing by means of a screw-threaded pin 18 which passes through a bore in the casing and is secured in position by a nut 19. One arm of the bracket 17 constitutes a platform on which a level bubble 21 and a compass 22 are mounted. The other arm takes the form of a protractor 23 and a line 24 is engraved on the casing with which the protractor 23 can be aligned. A clinometer 25 is also mounted on the casing 15 on the same side as the bracket 17.

A tape 26 extends through the tube 11 and an illuminating device such as a torch 27 is secured to one end of the tape.

After a bore hole 3 has been drilled, the torch is lit and lowered by the tape 26 into the bore hole as shown in Fig. 4 of the drawings. The tape is then secured, for example by winding it round one of the handles 13. The tube 11 is then fitted into the top of the bore hole until the stops 12 rest on the quarry top 2. The spigot 14 is then fitted into the top of the tube 11 and the alignment of the bore hole 3 to the quarry face 1 can then be measured.

The torch is then viewed through the casing 15, spigot 14, tube 11 and the bore hole 3 and the clinometer 25 is adjusted to ensure that the device is correctly aligned with the axis of the bore hole 3. The casing 15 is then rotated by means of the handle 16 and the bracket 17 is pivoted about the pin 18 until the level bubble 21 indicates that the platform of the bracket 17 is level. The bearing angle on the protractor 23 aligned with the line 24 engraved on the side of the casing 15 can then be read and this angle should coincide with the reading of the clinometer. It should be noted that the casing is only correctly lined up when the clinometer shows the biggest possible angle. At the same time, the bearing of the compass 22 can be read and in this way the inclination and direction of the axis of the bore hole 3 with respect to the quarry face 1 and quarry top 2 can be accurately determined.

The tube 11 is desirably made of aluminium or aluminium alloy or other nonferrous material and should have a relatively thin wall thickness in order not to obscure observation of the torch through the tube. According to a preferred embodiment, the tube has a length of approximately 2 metres, ideally 1900mm, and the stops 12 are preferably located at about 900mm from the lower end of the tube. The stops may take the form of short bars or rods having a width of approximately 40mm and extending radially from the wall of the tube for approximately 40mm. Preferably, two stops are provided but more than two stops may be provided if desired. The handles 13 desirably take the form of bars or rods extending radially from the wall of the tube 11 and are spaced by about 120mm from the upper end of the tube. Again, two handles 13 are preferably provided but more than two handles may be provided if desired. Alternatively, a single handle may be provided but this is not preferred because it would then be difficult to manipulate the tube in order to lower it into a bore hole.

The spigot 14 and casing 15 are also desirably made of aluminium, an aluminium alloy, brass or other non-ferrous material. The spigot is arranged to be a fairly close fit in the upper end of the tube 11 so that it can rotate with little play. The handle 16, which should also be made of a non-ferrous material, may take the form of a short bar or rod projecting from a side of the casing 15. Likewise, the bracket 17 and pin 18 should be made of non-ferrous material.

Quarry drilling equipment is fairly basic and this, coupled with other factors such as unfavourable geology or operator error, can affect drilling accuracy. For safe blasting to occur, it is vital that the angle of inclination and the bearing of all shot holes is accurately measured. It is also important that a shot hole is straight to within a tolerance of one diameter. Frequently a shot hole can wander at the setting up stage, as the drill bit cuts into the surface layers of rock. Remedial measures to get the drill back on line often result in a slight bend at the very top of the shot hole.

The device according to the invention relies on there being a fairly tight fit of the tube 11 in the shot hole. If there is a bend at the top of the shot hole, the tube may be wedged at the collar of the shot hole, out of line with the lower part of the shot hole. Since the clinometer 25 is originally fixed in line with the tube 11, any measurements carried out under these conditions will apply only to the top of the shot hole and may not be representative of the full length of the shot hole.

The known systems fail because of this. With the device according to the invention, on the other hand, provided that the clinometer is lined up on the torch, all of the measurements accurately relate to the full length of the shot hole, not just the collar area.

However, in the event of a secure bend at the collar area of a shot hole, it may not be possible to adjust the clinometer sufficiently to align it with the torch in the shot hole. The present invention also seeks to solve this problem by means of the embodiment shown in Figs. 5 to 9 of the drawings.

As shown more particularly in Figs. 6-8 of the drawings, the spigot 14 of the previous embodiment is replaced by a tubular member in the form of a tube section 31 which has a reduced diameter region 32 at one end which is adapted to fit into the top of the tube 11 and to be secured therein by locking screws 34.

Three L-shaped plates 35 are secured to the outside of the tube section 31, said plates being equi-spaced around the tube section by 120" and each being provided with a keyhole shaped slot 36 as shown in Fig. 9. A chamfered edge 33 is provided at the upper end of the tube section 31 which is arranged to mate with a similar chamfered edge 38 provided at the lower end of a ring 37. Mounted on the ring 37 are three equi-spaced brackets 40 each having a screw-threaded bore which is adapted to receive a respective adjusting screw 41. Each adjusting screw 41 carries a hand wheel 42, by means of which the screw can be turned and terminates in a ball 43. Each ball 43 is of such a size that it can be passed through the circular end of a keyhole-shaped slot 36 in a respective plate 35 but cannot pass through the narrower section of the slot. The ring 37 is thus secured to the tube section 31 by the adjusting screws 41 but its angular disposition can be adjusted by means of the screws, the chamfered edges 33 and 38 permitting adjustments to be made.

The ring 37 has a stepped bore and the lower end of a spigot 44 extending from a casing in the form of a rotatable cap 45 rests on a shoulder 39 formed by the stepped bore of the ring 37. A handle 16 projects from one side of the cap 45 and the cap is provided, on the opposite side from the handle 16, with a flattened surface to which a clinometer 25 is secured by screws 46. An L-shaped bracket 17 is pivotally mounted on the ring 37 by means of a screw-threaded pin 18 which is secured in position by a nut 19. A level bubble 21 and a compass 22 are mounted on one arm of the bracket 17, as with the previous embodiment, and the other arm of the bracket takes the form of a protractor 23, a line 24 being engraved on the cap 45 with which the protractor can be aligned. A tape 26 extends through the tube 11 and a torch 27 is secured to the end of the tape as with the previous embodiment.

The operation of the device shown in Figs. 5-9 of the drawings is essentially the same as for the embodiment shown in Figs. 1-4 of the drawings except that the ring 37, and hence the cap 45, can be adjusted by means of the adjusting screws in case it is not possible to align the clinometer with the torch in the hole. This may prove necessary if, as above discussed, it is not possible to adjust the clinometer sufficiently because of a bend in the shot hole particularly in the collar region.

As with the previous embodiment, the tube section 31 and the ring 37 are desirably made of a non-ferrous metal such as aluminium, an aluminium alloy or brass. The plates 34 and brackets 39 are desirably made of similar materials as are the adjusting screws 41. The cap 45 is desirably made of a plastics material such as "DELRIN" (Registered Trade Mark) as are the hand wheels 42.

It will be seen that the devices according to the present invention can be used to measure and determine the precise location of a bore hole in a quarry face. The clinometer indicates that the casing or cap is fully lined up on the torch and is also lined up in the direction of greatest inclination and is exactly in line with the bearing of the bore hole.

The invention is not restricted to the above-described embodiments but variations and modifications may be made without departing from the scope of the invention.

For example, a series of tubes of different diameter may be provided for use with bore holes of different diameter. In this case the spigot or tube section will be provided with stepped regions each step having a diameter substantially coinciding with that of a corresponding tube in which the spigot or tube section is intended to fit. The tube may also be formed in sections or articulated and hinged to facilitate transport between sites.

Claims

1. A device for measuring the bearing and inclination of a bore hole, said device comprising a tube adapted to be fitted into the top of a bore hole and to extend substantially parallel to the axis of the bore hole with an upper part projecting from the bore hole, an illumination device and means for lowering the said illumination device down the bore hole, a unit adapted to be mounted on the upper part of the tube for measuring the angle of inclination of the bore hole, a compass for indicating the direction of the bore hole and a level for indicating when the compass is substantially level.

2. A device according to claim 1, wherein the unit for measuring the angle of inclination is mounted on a casing which is adapted to be rotatably mounted in or on the upper part of the tube.

3. A device according to claim 2, wherein the casing is mounted in the upper part of the tube by means of a spigot which extends into the tube and which is secured to or formed integrally with the casing.

4. A device according to claim 2, wherein the casing takes the form of a cap which is rotatably mounted in a ring which in turn is adjustably mounted at the upper part of the tube.

5. A device according to claim 4, wherein the ring is provided with a chamfered edge which is engageable with a similar chamfered edge of a tube section, said tube section being adapted to be received in the upper part of the tube.

6. A device according to claim 5, wherein adjustment means are provided for adjusting the angle of inclination of the ring with respect to the tube section.

7. A device according to claim 6, wherein the adjustment means comprise a plurality of plates secured to the tube section and a corresponding number of screw adjusters mounted on the ring, each screw adjuster being provided with means which are engageable with a respective one of the plates.

8. A device according to claim 7, wherein each screw adjuster is engageable with a corresponding screw-thread provided in a respective bracket secured to the ring.

9. A device according to claim 7 or claim 8, wherein each screw adjuster extends through an aperture in the associated plate and terminates in a ball which is engageable with the said associated plate.

10. A device according to any one of claims 7 to 9, wherein each screw adjuster is provided with a hand wheel for turning the adjuster.

11. A device according to any one of claims 7 to 10, wherein the plates are equi-spaced around the tube section and the screw adjusters are equi-spaced around the ring.

12. A device according to any one of claims 7 to 11, wherein three plates and three screw adjusters are provided.

13. A device according to any one of claims 2 to 12, wherein the casing is provided with a handle to facilitate rotation of the casing with respect to the tube.

14. A device according to any one of claims 2 to 13, wherein the level and compass are mounted on a bracket which is pivotally mounted on the casing.

15. A device according to claim 14, wherein the bracket is substantially Lshaped, the level and compass being mounted on one limb and the other limb incorporating said unit for measuring the angle of inclination of the bore hole.

16. A device according to claim 15, wherein the said other limb of the bracket comprises a protractor which is pivotally mounted on the casing by means of a pin.

17. A device according to claim 16, wherein a line is marked on the casing by means of which angles can be read from the protractor.

18. A device according to any one of claims 2 to 17, wherein a clinometer is mounted on the casing.

19. A device according to any one of the preceding claims, wherein the tube is provided, intermediate its ends, with stops to prevent the tube from falling down a bore hole.

20. A device according to any one of the preceding claims, wherein the tube is provided with at least one handle to facilitate handling and positioning of the tube in a bore hole.

21. A device according to any one of the preceding claims, wherein the illumination device comprises a torch.

22. A device according to any one of the preceding claims, wherein the means for lowering the illumination device down a bore hole comprise a tape or line.

23. A device for measuring the bearing and inclination of a bore hole substantially as described herein with reference to Figs. 14 of the drawings.

24. A device for measuring the bearing and inclination of a bore hole substantially as described herein with reference to Figs. 5-9 of the drawings.