GB2236780A

GB2236780A - Strata coring device

Info

Publication number: GB2236780A
Application number: GB8920814A
Authority: GB
Inventors: Brian George Davidson Smart
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1989-09-14
Filing date: 1989-09-14
Publication date: 1991-04-17
Also published as: GB8920814D0

Abstract

A strata coring device for coring weak material has a core barrel (20) with a cutting tool at one end (23). A core holder (26) is inserted into the barrel (20) and after coring takes place the holder is advanced in the barrel so that fingers (28) at the end of the body of the holder close in over the core by driving the fingers against an internal shoulder (37) of the core holder. <IMAGE>

Description

STRATA CORING DEVICE This invention relates to a coring device having a support frame carrying an advancing device having releasable means for connecting it to a core barrel which is arranged to be driven into the strata to extract a sample from the strata.

In mining and geological exploration it is necessary to be able physically to examine samples of strata and this is done by driving a hollow tube into the strata to extract a core which can be then physically examined either at the site or remotely, for example, in the laboratory.

Normal coring devices are very satisfactory for solid and stable strata but they have a disadvantage when weak, fluid or friable strata is being cored in as much as the strata will not easily be able to be retained in the core barrel or will move so that the particles being cored rearrange themselves in position.

It is an object of the present invention to provide an improved strata coring device which is suitable for use when obtaining core samples of weak strata.

According to the present invention a strata coring device has a support frame carrying an advancing device, the advancing device having releasable means for connecting it to a core barrel arranged to be driven into strata to extract a sample thereof. The core barrel includes an internal core holder into which the core is driven and retained.

The core barrel preferably carries at its distal end an annular cutting tool and at its proximal end releasable securing means for securing it to the advancing device.

The core barrel preferably includes closing means for closing or partially closing one end of the core holder. The barrel may include a shoulder internally at its distal end and this shoulder may be arranged to be engaged by a split end of the core holder so that as the core holder is pushed against the shoulder, the end of the holder is engaged by the closing means to close or partially close the end of the core holder. The releasable means connecting the core barrel to the advancing device may include means for enabling the core barrel to be connected to the device in one of two positions, the first position in which the end of the core holder is open and the second position in which the distal end of the core holder is held in a closed or partially closed position.

The support frame may include clamping means for securing the frame to local supports, such as arch supports. The support frame itself may have a vertical support and the clamping means and the vertical support may both be adjustable.

The e advancing device is preferably hand screwed but hydraulic operating means may be incorporated to advance the core barrel into the strata.

The outside of the core barrel may be provided with a spiral to enable it to clear wet and sticky cuttings.

In order that the invention may be fully understood one example of a strata coring device in accordance therewith will now be described with reference to the four figures of the accompanying drawings. In the drawings figure 1 shows a front elevation and figure 2 a top elevation of the frame of the device and figure 3 shows a core barrel for fitting to the frame, while figure 4 shows a core holder.

Referring first to figures 1 and 2 of the drawings, this shows generally the support frame 1 which comprises two horizontal stays 2 and 3 joined by an adjustable transverse stay 4. A vertical stand 5 having a base plate 6 is adjustably clamped to the transverse stay 4 by a suitable clamping device as shown at 7 and the clamping device enables the stays 2, 3 and 4 to be moved vertically to a suitable position relative to the stand 5.

The clamping device 7 also carries a holder 8 for a feeding device 9 which is basically a feed screw which passes through a threaded bush 10 and is able to be rotated manually by a handle 11. The end of the feeding device 9 has two holes 12 and 13 drilled in it at its free end.

The ends of the stays 2 and 3 which are not connected to the transverse stay 4 are provided with clamping devices 15 and 16 respectively which enable the stays 2 and 3 to be secured to a convenient support such as mine arch supports. The clamping devices 15 and 16 may be of any suitable nature depending on the type of support or other device to which the coring device is to be attached.

Referring now to figure 3, this shows the core barrel which is to be driven into the strata. The core barrel 20 is of a general tubular nature having a slightly reduced end 21 and having along its main outer length a coarse spiral 22. This spiral is made of brass while the body of the barrel 20 is made of steel.

One end of the barrel 20 which in use is the distal end has a cutting tool 23 comprising a series of tungsten carbide inserts 24 which when rotated cut into the strata. The outer diameter of the cutting tool is slightly larger than the outer diameter of the spiral 22.

The reduced end of the 21 of the barrel 20 is provided with a through hole 25 through which locking pins are inserted to engage in holes 12 or 13 of the feeding device 9.

Referring now to figure 4, this shows the core holder which is comprised of a tubular body 26 made of pvc having at one end, which in use is the distal end, a series of splits 27 which enable the body to have a plurality of fingers 28 which are flexible. The other, or proximal, end of the holder is sealed with a closure device 29 which is screwed into the end of the holder and has a small aperture for air to escape from it.

An end cap shown generally at 30 comprises a tubular part 31 into one end of which is screwed a plug member 32 having a longitudinal hole 33 into which the end of the feeding device 9 projects. A spring 34 is positioned to seat within the collar 31 and against the head of the closure device 29. The tubular part 31 has indents 35 to receive the locking pins and the plug 32 has a hole 36 for the locking pin.

In use the clamping devices 15 and 16 are secured to arch struts in the mine when a sample is to be taken through a horizontal strata. The clamping device 7 is adjusted so that the stays 2 and 3 are at the correct height on the stand 5 with the base of the stand on the floor. The core holder has the tubular body 26 inserted into the core barrel 20 to a position where the fingers 28 just engage with a conical section 37 in the internal bore of the barrel 20. The closure 29 fits against the internal bore wall of the barrel 20 and the end cap 30 is positioned in the bore with the spring 34 spacing the closure from the end cap.

The core barrel 21 is then connected to the feeding device 9 by inserting the reduced end 21 of the barrel into a tubular end of the device 9 and inserting locking pins (not shown) through the holes 12 and the holes 25 into the indents 35.

The handle 11 is then rotated to cause the feeding device to advance and present the tungsten carbide inserts 24 of the cutting tool 23 to the face of the strata to be cut. As the handle is rotated the inserts bite into the face and produce a tubular core which is fed into the body 26 of the core holder. When the body 26 has sufficient material in the holder the feeding device is stopped and the pin is withdrawn from the hole 12 and the feed screw is then advanced by acting on the plug 36 and the spring 34 to drive the body 26 along the barrel so that the fingers 28 engage with the shoulder 37 and force them inwards over the core to trap the core within the body. The barrel 20 does not rotate during this operation and when the fingers 28 are sufficiently closed the locking pin is able to be inserted through hole 13 of the feeding device and holes 32 of the end cap respectively.

The handle 11 is then rotated in the opposite direction so that the feeding device withdraws the barrel with the holder and the core contained therein from the strata. When it is fully withdrawn the locking pin is removed and the holder with its contents can be carefully removed and dispatched to a remote location for analysis. This means that a weak core can be transported with the minimum of disturbance.

To take a further core a fresh holder is placed in the barrel and the whole process is repeated.

The use of the coarse brass spiral 22 on the outside of the barrel has the advantage that where a sticky strata such as clay is being cored the movement of the barrel during cutting is assisted.

The device can be adapted for inclined or vertical coring with the necessary modifications to the frame structure.

With vertical coring in an upward direction the device will be able to be used quite easily. However modification may be necessary with vertical coring in a downward direction where the closure of the core holder may have to be modified so that the fingers 28 are deformed substantially to close over the whole of the end of the core rather than only partially to close over as in the example described.

Claims

1. A strata coring device having a support frame carrying an advancing device, the advancing device having releasable means for connecting it to a core barrel arranged to be driven into strata to extract a sample therefrom, the core barrel including an internal core holder into which the core is driven and retained.

2. A device as claimed in claim 1 in which the core barrel carries at it distal end an annular cutting tool and at its proximal end releasable securing means for securing it to the advancing device.

3. A device as claimed in claim 1 or claim 2 in which the core barrel includes closure means for closing or partially closing one end of the core holder.

4. A device as claimed in claim 3 in which the closure means comprise a shoulder at the internal distal end of the core barrel, the shoulder being arranged to be engaged by the distal end of the core holder.

5. A device as claimed in claim 3 or claim 4 in which the distal end of the core holder is split to form fingers at the end, the fingers being arranged to be closed in on themselves when engaged by the closure means.

6. A device as claimed in any preceding claim in which releasable means are provided for connecting the advancing device to the core barrel in one of two positions, the first position in which the end of the core holder is opened and the second position in which the core holder has its distal end held closed or partially closed.

7. A device as claimed in any preceding claim in which the support frame includes clamping means for securing the frame to adjacent supports.

8. A device as claimed in any preceding claim and including vertical support means for the support frame.

9. A device as claimed in claim 7 or claim 8 in which the clamping means and the vertical support means are adjustable.

10. A device as claimed in any preceding claim in which the advancing device is screw operated.

11. A device as claimed in any one of claims 1 to 9 in which the advancing device is hydraulically operated.

12. A device as claimed in any preceding claim in which the core barrel has an outer spiral surface.

13. A strata coring device substantially as hereinbefore described and with reference to the accompanying drawings.