EP0150977A2

EP0150977A2 - Earth drill

Info

Publication number: EP0150977A2
Application number: EP85300424A
Authority: EP
Inventors: Anthony Keith Edward Jessup
Original assignee: BSP International Foundations Ltd
Current assignee: BSP International Foundations Ltd
Priority date: 1984-01-27
Filing date: 1985-01-23
Publication date: 1985-08-07
Also published as: GB8402147D0; EP0150977A3

Abstract

The present invention provides an earth drill in which a rotatable drill table and a support mast are carried at the front of a motive unit which can be rotated by an operator about a substantially vertical axis to slew the drill table into and out of register with the hole to be made by a drill auger driven by the drill table by means of a drill kelly characterised in that the operator is to be located offset to one side of the centre line of the mast, in that the drill table 3 is carried offset to that side of the support mast 2 with the axis of rotation of the drill kelly 10 mounted in the drill table 3 lying substantially on the circumference of a circle having its centre as the axis of rotation of the motive unit 1; thus providing the operator with an unobstructed view of the drill tip so as to aid location of the drill in the ground. Preferably, there are provided means 4 for supporting one or more tubes for lining the hole drilled by the auger, the support means 4 being located substantially symmetrically to the side of the mast 4 opposed to the drill table 3 whereby the axis of the tubes supported by the support means 4 are located substantially on the circumference of the same circle as the axis of the drill kelly 10.

Description

The present invention relates to an earth drill, notably to one having an off-set drilling table.
Hitherto, earth drills have typically comprised a drilling mast carried on a support frame at the front of a crawler unit which houses the power unit and which acts as the transport unit for the drill on site. The drilling is achieved by means of a drill bit or auger which is mounted on the end of a drill kelly which passes through the drive hole in the centre of a drilling table driven from the power unit of the crawler unit. The drill table is mounted substantially centrally in front of the crawler unit on a support frame which also supports the drill mast which carries the upper portion of the kelly.
As the hole is drilled, it is usually necessary to remove the drill auger from the hole to discharge soil from the hole and also to insert lining tubes into the hole to prevent the hole from caving in. To do this, the drill is withdrawn from the hole and the drill and mast traversed to one side by swinging the whole unit about the axis of rotation of the crawler unit. Whilst the drill can be readily re-centred on the hole by reversing the traverse of the rig, problems are often encountered in accurately aligning the lining tubes with the hole into which they are to be inserted. Accurate positioning of the tubes, which are supported from the mast and lowered into the hole, is required if the tubes are to seat truly into the hole. This alignment is achieved by not only slewing the rig about the axis of rotation of the crawler, but also by actual manoeuvring of the crawler unit on its tracks. Once the tubes are in place it is then necessary to re-align the drill with the hole to continue drilling. All this takes time which might otherwise have been spent drilling and requires considerable skill from the drill operator.
It has been proposed in US Patent No for example, to mount the drill table offset from the mast to enable a pile driver hammer to be mounted on the other side of the mast or to mount the drill table on a mast which can be pivotted to bring the hammer into line with a hole drilled by the drill. However, the table has been offset to the side opposed to the operator and this has aggravated the problems of poor visibility.
We have now devised a form of construction for an earth drill which not only reduces the above problems, but also reduces the stresses on the mast present in conventional designs of earth drill. In such designs, the lines used for supporting the drill kelly or for lifting casings out of the drilled holes have been run from the top of the mast using sheaves. These sheaves have had to be offset considerably to either side of the mast in order that the lines should clear the drilling table. As a result, considerable transverse bending moments have been applied to the mast during operation. With the present invention the sheaves for the lines can be mounted close to the centre line of the mast and thus reduce any bending moment on the mast as loads are applied to the lines.
Accordingly, the present invention provides an earth drill in which a rotatable drill table and a support mast are carried at the front of a motive unit which can be rotated by an operator about a substantially vertical axis to slew the drill table into and out of register with the hole to be made by a drill auger driven by the drill table by means of a drill kelly characterised in that the operator is to be located offset to one side of the centre line of the mast, in that the drill table is carried offset to that side of the support mast with the axis of rotation of the drill kelly mounted in the drill table lying substantially on the circumference of a circle having it centre as the axis of rotation of the motive unit.
Preferably means are provided for supporting one or more tubes for lining the hole drilled by the auger, the support means being located substantially symmetrically to the side of the mast opposed the the drill table whereby the axis of the tubes supported by the support means are located substantially on the circumference of the same circle as the axis of the drill kelly.
The earth drill is essentially of the same design and construction as a conventional earth drill, except that the drill table is mounted offset to the same side of the drill mast as the position of the operator. This offset gives the operator of the drill a better and less obstructed view of the drill and kelly during drilling, thus aiding accurate placement of the drill auger during the start of drilling and re-alignment of the auger with the hole after the auger has been removed from the hole to discharge earth. Where, the mast also carries the lining tube supports, accurate alignment of these with the hole is simplified by virtue of the fact that they will automatically align with the hole merely by swivelling the motive unit about its axis. Virtually no manoeuvring of the motive unit is required, thus simplifying the operation of the earth drill and cutting down on the time lost. As indicated above, the offset of the drilling table allows the lines supporting the kelly and the lining tubes to be run close to the centre line of the mast. This reduces the bending moments on the mast due to the large offset hitherto considered necessary for the mounting of the sheaves.
To aid understanding of the invention, it will be described with respect to a preferred form thereof as shown diagrammatically in elevation in Figure 1. Figure 2 is a plan view of the drill shown in Figure 1.
The drill comprises a motive unit 1. This is conventionally a crane unit mounted on a crawler or tracked base member on which the unit can be manoeuvred. However, other forms of motive unit can be use if desired, eg. one having wheels rather than catterpillar tracks. The unit is characterised in that the motive unit is rotatably mounted on the base member, preferably so that the crane can be rotated through up to 360°. The crane unit typically houses the main power unit, eg. a diesel engine or diesel pump driving one or more hydraulic motors, the control cabin at the front thereof and offset to one side of the mast, and the cable winding mechanisms for lifting and lowering the drilling mast, the kelly and the lining tubes. Typically the control cabin lies adjacent the edge of the crane unit. The operator is thus offset from the mast by from 20 to 40% of the width of the crane unit. The motive unit can be of conventional design and many suitable forms are commercially available to suit the loads imposed by the drilling operation.
At the front of the motive unit 1 is mounted a mast 2 which serves to support the drill table 3 to one side and the tube location supports 4 to the other side. The mast is typically carried by a support frame 5 attached to the front of the motive unit. Preferably, at least part of the weight of the mast is carried by an extensible foot 6 provided at the base of the mast and extended by an hydraulic ram or other means to bear against the earth when the drill is set up on site for drilling. Preferably, the support frame 5 incorporates means whereby the angle of the mast can be varied both fore and aft and from side to side so that the drill can drill holes at an angle into the ground. Typically, this is achieved by mounting the mast on the support frame 5 by a generally horizontal pivot pin 7, to give the side to side movement; and by other pivots (not shown) at right angles to give the fore and aft movement. The movement of the mast is preferably controlled by one or more hydraulic rams carried by the support frame 5. It is also preferred that the mast can be lowered into the substantially horizontal position for transport by the use of the fore and aft pivot system.
Whilst the drill table 3 and the lining tube location supports 4 can be mounted independently of one another and either upon the mast 2 or upon the support frame 5, it is preferred to mount them upon a common carrier yoke 8 which is moveable up and down the mast 2 by means of an hydraulic ram or other means (not shown). The yoke 8 conveniently comprises a sleeve which is journalled as a sliding fit on the mast 2. If desired, the sleeve can be provided with guide rollers or the like to maintain the alignment of the sleeve on the mast as it travels axially on the mast.
To one side of the mast, the yoke has the drill table 3 mounted thereon by any suitable means, eg. by forming part of the side member of the drill table integral with the sleeve wall. The table 3 can be of conventional design and typically has a substantially square axial aperture to receive the kelly 10 for the drill auger. The kelly is supported by ropes or lines from a winding drum of the unit 1 passing under pulleys or sheaves 9 at the foot of the mast and pulleys or sheaves 11 at the mast head. The sheaves 11 are located within the transverse width of the mast, preferably close to the centre line of the mast, so that the thrust on the mast by the loads carried by the sheaves is carried directly on the mast and not laterally offset therefrom, thus reducing any bending moment on the mast.
The axis of the kelly aperture in the table lies at an arbitrary distance from the axis of the rotation of the motive unit body on its base unit. This distance may be larger or greater than the distance that the mast centre is from that same axis. Thus, the table can be mounted ahead of or behind the centre line of the mast and the optimum position will depend upon many factors, eg. the size of the drill auger (to achieve the necessary clearances from the other parts of the machine) and the method of driving the drill table (which may be powered by its own motor rather than from the motive unit engine), and can be readily determined for any given case. However, it will usually be preferred to mount the drill table so that it and the mast centre lie on substantially the same circle of rotation about the axis of rotation of the motive unit, to reduce unnecessary stresses.
To the other side of the mast, the tube location supports 4 are mounted on the yoke 8. Typically, the supports comprise V or semi-circular plan view brackets into which the tubes seat as they are supported by lines or ropes from the mast head. The supports 4 lie upon substantially the same circle of rotation as the drill kelly so that mere rotation of the motive unit will bring either the drill kelly or the tubes in the supports 4 into alignment with the hole formed by the drill auger, with the minimum of other manoeuvring by the motive unit. It is therefore particularly preferred to have the axis of the drill table kelly aperture and the axis of the lining tubes mounted in the supports 4 located substantially symmetrically to either side of the mast centre line.
The supports 4 can incorporate a mechanism for locking the tubes thereinto, eg. a pivotted front closure to form a jaw to the supports 4. It is also preferred to have two or more sets of supports 4 axially spaced upon the mast by up to 3 metres to impart greater stability to the tube during alignment with the hole. It is also preferred to form the supports 4 with a solid underface which can bear against the rim of a tube once it has been inserted into the hole in order that the support can be used to drive the tube into the hole using the hydraulic ram which raises or lowers the drilling table on the mast. Preferably, the under face of the lowest support 4 has an upstanding shoulder or rib which serves to aid location of the support 4 on thwe rim of the tube.
As indicated above, the weight of the drill kelly and of the linig tubes is carried by ropes or lines from the winding drums of the motive unit. These ropes or lines run under sheaves 9 at the foot of the mast, up the back face of the mast to sheaves 11 at or adjacent the top of the mast and down the front face of the mast. It is preferred to stand the sheaves 9 at the foot of the mast away from the mast by approximately the same distance as the kelly and the lining tubes stand off from the front of the mast, so as to reduce any fore and aft bending moment that the load on the ropes or lines would have on the mast. It is also preferred to carry the sheaves 9 on an extension to the fore and aft pivot pin 7 by which the mast is carried by the suport frame 5, so that the geometry of the ropes or lines relative to one another and to the mast remain substantially constant during any side to side inclination of the mast.
The earth drill of the invention is operated in a manner similar to a conventional drill. However, by having the kelly aperture in the drill table and the axis of the lining tubes in supports 4 substantially on the same circle of rotation, removal of the drill auger, insertion of a lining tube and re-alignment of the auger with the drilled hole are all simplified. With the drill of the invention, it may be possible to reduce the lost time spent in clearing earth from the drill auger and in fitting lining tubes into the hole by as much as 10 %, thus clearly reducing the overall time taken for a drilling operation.

Claims

1. An earth drill in which a rotatable drill table and a support mast are carried at the front of a motive unit which can be rotated by an operator about a substantially vertical axis to slew the drill table into and out of register with the locus of a hole to be made by a drill auger driven by the drill table by means of a drill kelly characterised in that the operator is to be located offset to one side of the support mast 2 and in that the drill table 3 is carried offset to that side of the support mast 2 with the axis of rotation of the drill kelly 10 mounted in the drill table 3 lying substantially on the circumference of a circle having it centre as the axis of rotation of the motive unit 1.

2. An earth drill as claimed in claim 1 characterised in that there is provided means 4 for supporting one or more tubes for lining the hole drilled by the auger, the tube support means 4 being located substantially symmetrically on the support mast 2 to but opposed to the drill table 3, whereby the axis of the tubes supported by the support means 4 are located substantially on the circumference of the same circle as the axis of the drill kelly 10.

3. An earth drill as claimed in claim 1 characterised in that at least part of the weight of the support mast 2 is carried by an extensible foot 6 mounted at or adjacent the base of the support mast 2 and capable of being extended by an hydraulic ram or other means to bear against the earth when the drill is set up for drilling.

4. An earth drill as claimed in claim 1 characterised in that the support mast 2 is mounted on the motive unit 1 by means of a support frame 5 which incorporates means 7 whereby the angle of the support mast 2 can be varied both fore and aft and from side to side so that the drill can drill holes at an angle into the ground.

5. An earth drill as claimed in claim 4 characterised in that the movement of the support mast 2 is achieved by one or more hydraulic rams carried by the support frame 5.

6. An earth drill as claimed in claim 2 characterised in that the drill table 3 and the tube support means 4 are mounted upon a common carrier yoke 8 which is moveable up and down the support mast 2 by means of an hydraulic ram or other means.

7. An earth drill as claimed in claim 2 characterised in that the tube supports 4 are provided with means which can bear against the rim of a tube once it has been inserted into the hole made by the drill in order that the support can be used to drive the tube into the hole using the means which raises or lowers the drilling table 3 on the support mast 2.

8. An earth drill as claimed in claim 1 characterised in that the kelly 10 is supported by ropes or lines from the motive unit 1 which run under pulleys or sheaves 9 at the foot of the support mast 2, up the back face of the support mast 2 to pulleys or sheaves 11 at or adjacent the top of the support mast 2 and down the front face of the support mast 2, the pulleys or sheaves 11 being located within the transverse width of the support mast 2 so as to reduce lateral bending moments on the mast due to loads caried by the ropes or lines.

9. An earth drill as claimed in claim 8 characterised in that the pulleys or sheaves 9 at the foot of the support mast 2 are located away from the rear of the support mast 2 by approximately the same distance as the kelly 10 is located away from the front of the support mast 2.

10. An earth drill as claimed in claim 9 characterised in that the pulleys or sheaves 9 are carried on an extension to a generally horizontal pivot pin 7 by which the support mast 2 is mounted on the support frame 5 carried by the motive unit 1, so that the geometry of the ropes or lines relative to one another and to the support mast 2 remain substantially constant during any side to side inclination of the support mast 2.