GB2106953A - Improvements relating to auger equipment - Google Patents

Abstract

A mobile auger rig has a mast assembly (10) which supports, for rotation, an elongate drilling bar (23) for mounting an auger (27). The mast assembly (10) has a drilling bar steady (25) for supporting the upper end of the drilling bar (23) in use, and a hydraulic ram (26) connected between the drilling bar steady (25) and the mast assembly (10) in order to load the drilling bar (23). <IMAGE>

Description

SPECIFICATION Improvements relating to auger equipment The present invention relates to auger equipment for use in the installation of concrete cast in-situ piles, and more particularly to such auger equipment which also includes means for placing temporary casings within the bores into which such piles are to be cast.

Conventionally, auger equipment for boring holes in the ground into which concrete piles are cast comprises a screw or bucket auger which is attached to the lower end of an elongate drilling bar which is supported in a mast assembly and which can be lowered or raised by a winch rope, the mast assembly being supported on a tractor unit. The mast assembly is supported at the front of the unit and can be pivoted in a vertical longitudinal plane of the unit. The drilling bar is supported towards the bottom of the mast assembly in a drilling table which has a drive for rotating the drilling bar. At its top end the drilling bar is supported in a bar-steady which is slidable along the mast assembly.In order to apply pressure to the auger when the equipment is in use the drilling table has a bearing and friction clamp and a pair of crowd rams which act through the clamp and bearing to apply force downwardly to the auger as it is being rotated.

To enable the insertion or extraction of temporary casings in to or out of the bores produced by the auger, the head of the mast assembly has two head pieces, one of which supports the drilling bar and the other of which carries a secondary winch rope for supporting sections of temporary casing.

In use, the crowd rams and bearing and friction clamp are actuated in discrete steps as the crowd rams operate only over a short length, so that in order to force the auger into the ground as it is rotated the rams and clamp have to be actuated and released several times. A further problem with existing equipment is that in order to rotate the second head piece into a position in which it can lower or raise a casing into a pre-bored hole, the equipment has to be rotated about the central pivot axis of the tractor unit and this inevitably imposes eccentric loadings on the mast which restrict the maximum load that can be carried on the secondary winch rope which supports the temporary casing sections.Furthermore, although the mast assembly can be pivoted in a longitudinal vertical plane of the unit to enable a vertical position in that plane to be achieved prior to drilling, in order to obtain a vertical position in the transverse plane the ground beneath the tractor unit usually has to be pre-leveled or else the tracks of the tractor unit have to be packed underneath with timbers of varying thickness. When moving the equipment round the site the mast assembly can normally be lowered to a horizontal position by a hydraulic ram, but lowering the mast assembly to the horizontal position also entails pivoting the drilling table as well since the whole assembly has to be pivoted.This rotation of the drilling table causes the equipment to have an unacceptably large height even when in the collapsed position so that for movement between work sites the mast assembly usually has to be removed to meet height restrictions imposed by the Road Traffic Acts.

The present invention sets out to overcome these problems and, in accordance with a first aspect of the invention a mobile auger rig has a mast assembly which supports, for rotation, an elongate drilling bar for mounting an auger, the assembly having a drilling bar steady for supporting the upper end of the drilling bar in use, and a hydraulic ram connected between the drilling bar steady and the mast assembly in order to load the drilling bar.

Preferably, the drilling bar steady is formed at the upper end of a tubular casing through which the drilling bar can slide, under the action of a winch rope, the drilling bar casing locating at its bottom end in a drilling bar table having means for rotating the drilling bar.

Advantageously, the drilling bar and drilling bar casing can be withdrawn from the drilling bar table and rotated with the mast assembly from a substantially upright position to a substantially horizontal position on top of the tractor unit.

Loading the drilling bar steady by means of a single ram, thus doing away with the conventional crowd rams and bearing and friction clamp provides for much longer biasing or crowd stroke.

The ram could be located internally of the mast if desired to provide additional protection from damage during operation.

A screw or bucket auger can be filled with a single stroke of the ram rather than with two or more strokes as was previously necessary with the conventional crowd ram construction, such crowd rams having a stroke length of approximately only 500 mm, due to their being mounted on the drilling table.

By enabling the drilling bar casing and drilling bar to be removable from the drilling table and rotatable from a generally upright position to a substantially horizontal position on top of the tractor unit the overall height of the rig can be significantly reduced as the drilling table can remain in its usual, substantially horizontally extending, position during transportation.

The mast assembly and the drilling table may be mounted for pivotal rotation about an upright axis adjacent the forward end of the rig and separate from the main axis of rotation of the rig (as described and claimed in our copending application Ref. GJE 5181/094). This allows the secondary winch rope to be positioned directly over the axis of any bored hole without rotation of the main body of the tractor unit and without retraction of the usual mast foot. Thus, location of the secondary winch rope over the drilling hole can be much more positive and accurate than has previously been possible and can be affected in a single operation. Furthermore, excessive loadings on the mast assembly can also be reduced.

Preferably, the pivot axis of the mast assembly is aligned with the axis of the mast foot in a frame mounted on the front of the tractor unit. In order to rotate the mast assembly about the upright pivot or axis, a hydraulic ram can connect a part of the frame with a part of the mast assembly, the ram being pivotally connected at each end to enable such movement.

Preferably the mast assembly and drilling table are supported on a tractor unit for limited pivotal movement about a generally horizontal axis extending substantially parallel to the longitudinal axis of the tractor unit, whereby the mast assembly can be plumbed to the vertical about such pivot axis. Previously, the mast assembly could only be plumbed to the vertical in the longitudinal plane, as mentioned above, but with equipment according to this aspect of the present invention it can be plumbed about two transverse axes thus enabling the rig to operate on uneven ground without pre-leveling.

One example of a mobile auger rib according to the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a partially diagrammatic side elevation of the rig; and, Figure 2 is a plan view of the rig.

The rig comprises a tractor unit 1 which has a pair of endless tracks 2 on which the rig can be moved and a body 3 which is rotatable about a vertical axis 4 relative to the tracks 2.

At the front of the body there is mounted a support frame 5, the support frame being mounted for pivotal movement about an axis 6 which is substantially horizontal and transverse to the body 3. The frame 5 is movable about the pivot axis 6 by a pair of hydraulic rams 7.

At the front end of the frame 5 there is pivotally mounted by means of a bearing plate 8 a subframe 5' which in turn supports the lower end of a mast assembly 10.

The mast assembly has, at its lower end 9, a foot 11 which is adjustable in height telescopically to support the lower end 9 of the mast assembly 10 and which is pivotally mounted to the lower end of the mast assembly by means of a ball and socket connection 12. By means of the bearing plate 8 and a generally horizontally disposed hydraulic ram 8' the subframe 5' can be pivoted about a generally horizontal axis parallel to the longitudinal axis of the body 3.

The sub-frame 5' supports a further sub-frame 5" which in turn supports a drilling rod table 13 and the whole of the mast assembly and drilling table can be pivoted, with the sub-frame 5" about a pivot axis 14 co-axial with the centre-line of the mast by means of a hydraulic ram 15, so that the mast assembly 10 can be rotated about a generally upright axis independently of the rotational position of the body 3 about the axis 4.

The drilling rod table 13 has a variable displacement hydraulic motor 13' which is driven by a fixed displacement hydraulic pump to rotate the drilling rod 23. The pump in turn is driven by the prime mover of the tractor unit. The upper mast 16 is pivotally supported on an axis 17 and is movable in a generally vertical longitudinal plane between the collapsed position shown in dotted lines and the upright position shown in solid lines in Figure 1. A pair of hydraulic ram assemblies 18 are provided to enable the mast assembly 10 to be collapsed into a generally horizontal collapsed position as shown. The upper mast 1 6 has a cross-head 20 having a pair of pulleys 21 around which a first winch rope 22 passes from a winch drum 22' within the body 3 of the tractor unit 1.

The free end of the rope 22 is pivotally connected with the upper end of the drilling rod 23 so that the drilling rod can rotate without twisting the rope. The drilling rod 23 is housed within a rotary casing 24, the upper end of which is carried within a drilling bar steady 25 which is movable along the upper mast 1 6 under the action of a hydraulic ram 26. When the mast assembly is collapsed the casing 24 is removed from the drilling table 13 and is nested in a support 1 9 formed at the lower end of the upper mast, the members 19 are disconnected and the rams 1 8 are retracted to lower the mast assembly 1 0.

The lower end of the casing 24 and rod 23 are movable through the table 1 3 and the casing 24 bears against the drilling rod 23 by frictional coupling during rotation of the casing to rotate the rod. Movement of the bar steady 25 downwards under the action of the ram 26 moves the casing 24 which in turn, by means of the frictional coupling drives the drilling rod downwards. An auger 27 mounted on the lower end of the drilling bar 23 is driven into the ground as the casing is rotated under the action of the motor 13'.

At its upper end the mast assembly includes further pulleys 28 around which passes a second pulley rope 29 for supporting a temporary casing for a pile which is to be formed in the bore drilled by the auger 27. To rotate the mast between the two positions shown in Figure 2, the ram 1 5 is actuated to rotate the whole of the mast assembly without requiring the body 3 to be rotated relative to the tracks 2. Thus, the free end of the second pulley rope 29 and thus the temporary casing can be aligned with the bore.

In order to plum the mast assembly so that the bore to be drilled is vertical, the hydraulic rams 7 and 8' are actuated so as to rotate the mast assembly in two upright planes transverse to one another.

Preferably, all the hydraulic rams and other machine functions of the rig are powered hydraulically from a single prime mover/hydraulic power pack in the body of the tractor unit. A considerable fuel saving can be achieved compared with conventional equipment which usually contains two prime movers, one operating the tracks of the unit and the other operating the various drilling functions.

It is conventional to use a torque convertor for driving the drilling bar, but by replacing this by a direct hydrostatic drive as discussed above the efficiency of power transmission to the drilling bar can be significantly increased.

Claims (7)

1. A mobile auger rig having a mast assembly which supports, for rotation, an elongate drilling bar for mounting an auger, the assembly having a drilling bar steady for supporting the upper end of the drilling bar in use, and a hydraulic ram connected between the drilling bar steady and the mast assembly in order to load the drilling bar.

2. A rig according to claim 1, in which the drilling bar steady is formed at the upper end of a tubular casing through which the drilling bar can slide, under the action of a winch rope, the drilling bar casing locating at its bottom end in a drilling bar table having means for rotating the drilling bar.

3. A rig according to any of the preceding claims, in which the drilling bar and drilling bar casing can be withdrawn from the drilling bar table and rotated with the mast assembly from a substantially upright position to a substantially horizontal position on top of the tractor unit.

4. A rig according to any of the preceding claims, in which the mast assembly and the drilling table are mounted for pivotal rotation about an upright axis adjacent the forward end of the rig and separate from the main axis of rotation of the rig.

5. A rig according to claim 4, in which the pivot axis of the mast assembly is aligned with the axis of the mast foot in a frame mounted on the front of the tractor unit.

6. A rig according to any of the preceding claims, in which the mast assembly and drilling table are supported on a tractor unit for limited pivotal movement about a generally horizontal axis extending substantially parallel to the longitudinal axis of the tractor unit, whereby the mast assembly can be plumbed to the vertical about such pivot axis.

7. A rig according to claim 1, substantially as described with reference to the accompanying drawings.