Auger cleaner

The present invention relates to an auger cleaner and to a helical blade for use therewith.

When a hole is drilled in the ground using a continuous-flight auger, the soil is cut by the leading edge of the auger and transported upwards by the auger flighting which acts as an Archimedean screw conveyor. In sticky clay soils for example, this soil may be carried up to a height above the ground where it represents a serious danger to site personnel as it may become dislodged and fall and thereby cause injury or even death. Further, it is necessary to remove soil compacted on the auger flights from the auger before the auger can be used again.

Traditionally, augers have been cleaned by hand using a hoe or shovel. This has been only partially satisfactory, and is in any event labour intensive.

Various attempts have been made to mechanise the cleaning of augers which mostly involve providing means for inserting a scraper at will between adjacent flights of the auger thereby to dislodge the spoil adhering thereto. These devices require the auger to be rotating before they can operate since they have no means of motive power.

Recently it has become necessary to provide means whereby a scraper be utilised to clean an auger independently of the rotation of the auger since it is necessary in modern civil engineering operations to be able to withdraw the auger from a bore that it has just drilled without necessarily rotating the auger.

This problem has been addressed in GB-A-2 158130, which provides an auger cleaner comprising a scraper blade interposable between adjacent flights of an auger, motor means for rotating the scraper about the axis of the auger to remove debris retained between the flights, and control means to match the speed of axial movement of the auger with rotational movement of the cleaner.

There is a number of problems however with this arrangement. The scraper described in that specification comprises a plate which may be swung from an inoperative to an operative position. In the operative position the plate extends between adjacent flights of the auger. The scraper is formed upon a body which is rotated about the axis of the auger thereby to force the spoil or debris adhering to the auger flights out of adhesion therewith, thereby to clean the flights on a progressive basis.

In the first place, because the scraper blade extends generally perpendicular to the path of the auger flighting, power requirements for removing sticky clay, for example, from the auger flighting by means of the scraper can be high. Furthermore it is a regular occurrence that the flighting becomes deformed over a period of time. Generally the deformations on the auger flighting are such that the auger flighting plates are bent downwardly because of the drilling action in demanding conditions. Further, this deformation need not be regular, but can comprise irregular deformations as a result of the action of particular stones, blocks of concrete, etc. With the scraper arrangement in accordance with the above-identified disclosure, deformation of the auger flights almost inevitably causes the scraper to jam unless the scraper blade is made small enough to accommodate likely deformations; in which case, of course, the efficiency of cleaning is much reduced. This effect is exacerbated because the lateral edges of the scraper are intended to slide against the upper and lower faces of opposed portions of auger flighting so that the scraper will tend to jam if either of the flights are deformed.

Further inefficiencies lie in the fact that each section of the auger is jointed to the other at the auger axis, Thus, a complete auger may be formed of a number of different sections, all co-axially arranged and interengaged by means of suitable male and female interengagements. This means that it is not possible for the scraper of the prior art to rest against the central axis of the auger in use since if it does, it would become periodically jammed against an annular flange forming part of the auger axis. Accordingly, it is necessary to shorten the scraper blade so as to be well clear of the auger axis and again this reduces the efficiency of operation.

In SU-A-7050999 there is described a static auger cleaner also provided with a scraper which can be rotated at will into or out of engagement with the auger flights. The static cleaner rests on two rollers which ride on the cleaned auger flights above the scraper. The cleaner is held in the vertical sense so that rotation of the auger also cleans the auger flight. The cleaner cannot be operated if the auger is stationary.

In order to overcome or alleviate the foregoing problems, the present invention is characterised in that the scraper blade has a helical configuration which generally conforms to, or has a greater angle of attack than, the angle of the flights of the auger thereby to displace debris and/or spoil by applying thereto a lifting force in the direction of the axis of the auger.

In a preferred form of the invention, the scraper blade is in permanent interengagement with the auger flights and is retained in its desired orientation between the flights of the auger by means of a roller riding on a portion of the auger flights superior to the cutting edge of the scraper blade. The roller may be of a readily replaceable type so that it may be replaced by a roller of a different diameter thereby to adjust the gap between the face of the auger flight and the adjacent cutting edge of the scraper blade. This arrangement allows the auger cleaner to move up and down the length of the auger at will.

The scraper blade is preferably retained in an annular body which is a clearance fit about the auger flights, and wherein the annular body is operatively connected to the means for rotating the scraper about the axis of the auger. The annular body may be provided with a debris-discharging aperture adjacent the scraper blade. Means for rotating the scraper is preferably positioned above the said discharge aperture, and is preferably slidingly secured to a parallel rig member.

In a second aspect of the invention there is provided a scraper blade for an auger cleaner, said scraper blade being interposable between adjacent flights of an auger, characterised in that the scraper blade has a helical shape extending from its cutting edge, said helical shape having an angle to its intended common axis of rotation about the auger, which angle generally conforms to, or is greater than, the angle of attack of the flight of the auger with which it is intended to be used. In a preferred form of blade of this type, a weir is provided at or toward the end of the scraper remote from the cutting edge, said weir acting to urge the debris and/or spoil away from the axis of the auger.

The invention will now be described, by way of illustration only, with reference to the accompanying drawings, wherein:

• Figure 1 shows a front elevation of an auger cleaner in accordance with the present invention positioned upon an auger,
• Figure 2 shows a side elevation of the auger cleaner of Figure 1 in a similar position, and
• Figure 3 shows a plan view from above of a blade according to the invention. In accordance with standard practice in the art, an auger B is provided with an auger axis 9 about which auger flighting 3 is disposed in a standard fashion. The auger axis 9 is rotated by drive means (not shown) in standard fashion and is supported on an auger rig mast 12.

In accordance with standard practice in the art, the auger B is rotated by means of a drive thereby boring a hole in the soil which can then be filled with concrete, for example. The mast 12 extends parallel to the auger B in standard fashion.

In accordance with the present invention, the auger cleaner A is supported for free sliding movement on the mast 12 by means of guides 6 which ride upon the mast 12 in the upward or downward direction. The guides 6 are generally elongate and support a support apron 11 which supports in turn a motor 7 which, in this instance, is a hydraulic motor but may be electric or powered by other means. This motor in turn drives a crown wheel interengaged with a pinion extending about the upper periphery of a rotary shell 4 of a generally annular configuration. The internal diameter of the shell 4 is a clearance fit over the auger flighting 3. It will be appreciated that actuation of the motor 7 rotates a crown wheel (not shown) which interengages a pinion (not shown) shrouded by pinion shroud 8. The pinion is accordingly driven in response to the crown wheel and thereby rotates the rotary shell 4. Since the motor 7 is reversible, the rotary shell 4 may be driven in either direction.

Located within the rotary shell 4 is a helical scraper 1 which generally conforms to the configuration of the auger flighting 3. The helical scraper 1, as is shown in Figure 3, extends over most of a single turn of the auger flighting and terminates at its cutting edge in a specially hardened steel portion 13 which provides initial contact between the helical scraper blade 1 and the spoil impacted upon the auger flighting 3. The upper surface of the helical scraper blade 1 passes by a generally rectangular discharge aperture 5 formed in the shell 4. Adjacent the end of the helical scraper blade 1 remote from the cutting tip is a weir 14 which is upstanding from the upper surface of the helical scraper blade adjacent the lateral edge of the discharge aperture 5. The weir 14 acts to urge the debris forced up the inclined plane of the helical scraper 1 out of the discharge aperture 5. The lower rim 10 of the rotary shell 4 is provided with an out-turned section adapted to assist in impelling the spoil and debris away from the auger in use.

The internal face of the shell 4 remote from the aperture 5 and opposed thereto is provided with a suitably positioned roller which carries the shell, and hence the scraper blade integrally formed therewith, upon the auger flighting. It will be appreciated that the relative positions of the cutting edge of the scraper blade and the upper surface of the auger flighting can be adjusted by adjusting the external diameter of the roller so as to get the maximum cleaning as is commensurate with allowing for deformations of the auger flighting in use. By use of this roller rather than the previously utilised static edge to auger flighting interengagement, power requirements are kept to a minimum allowing the rotary shell and attendant scraper blade to be rapidly moved up and down the stationary auger flighting merely by utilisation of the motor 7.

In use, the auger cleaner A is controlled by means of the supply of hydraulic fluid to the motor 7 allowing it to be driven in either direction by the operator of the auger rig. Initially, the auger cleaner A is moved toward the top of the auger B and retained there during the drilling operation. Obviously, as the auger is wound down into the ground the auger cleaner A will descend with it, but this may be counteracted at intervals by operating the motor 7 to drive the auger cleaner upwards again. It is in any event occasionally necessary to stop the auger in order to interengage further sections of auger flights.

At the end of the drilling operation, the auger is withdrawn in the usual way. This may be done either by merely withdrawing the auger without rotation, or by gentle rotation in either the clockwise or anti-clockwise direction as seems appropriate to the operator in view of the stratum through which the hole is being bored. However the auger is withdrawn, it may be cleaned either as, or after, it has been withdrawn from the bore. In either condition, power is supplied to the motor 7 to drive the auger cleaner A in a downward direction thereby causing the helical scraper blade 1 to contact the impacted spoil on the auger flights 3 and discharge it either directed downwardly or via the discharge aperture 5. Deformations in the auger flighting do not cause jamming of the auger cleaner as in the prior art since the lifting motion of the helical scraper dislodges the spoil from the helical flights by a cutting displacement rather than by mere force. It will be appreciated that by means of the present invention the auger can be cleaned to its very tip by virtue of the interaction of the roller 2 with the auger flighting on the turn above the cutting edge.

Accordingly, the invention relates to an auger cleaner, and a helical blade for use therewith.