GB2064623A - Apparatus for Working - Google Patents

Abstract

The invention relates to apparatus for working, e.g. for consolidating or making holes in the ground. The apparatus comprises a tool to work the surface, means for monitoring the movement of said tool when the apparatus is in use in such a way as to provide data indicative of the position of said tool relative to a predetermined point on said surface, processing means for processing said data in accordance with pre-set relationships and means for producing a display and/or a readable record from the processed data. The apparatus can comprise, for example, an elongate flexible element which passes around a wheel, one end of the flexible element being fixed to move with the tool in a manner such that rotational movement of the wheel provides a indication of the movement of the tool. <IMAGE>

Description

SPECIFICATION Apparatus for Working The present invention relates to apparatus for working for example for consolidating or for making holes in the ground in the course of preparing the ground to accept building foundations.

According to the present invention there is provide apparatus for working the surface of a medium comprising a tool to work said surface, means for monitoring the movement of said tool when the apparatus is in use in such a way as to provide data indicative of the position of said tool relative to a predetermined point on said surface, processing means for processing said data in accordance with pre-set relationships and means for producing a display and/or a readable record from the processed data.

It will be obvious from the ensuing description that the term "position" as herein used is intended to include within its scope angular orientation as well as linear distance.

The tool may be a boring tool such as an auger for penetrating the ground, a mass for impacting the ground or a vibrator or grab, or any combination thereof.

It will be seen that apparatus according to the present invention can be constructed so as to monitor and provide information concerning operational parameters associated with work performed by the tool such as height, speed of movement, energy, power and force amongst others. Any or all of these operational parameters may be displayed, for example on a digital display in an operators cabin, so that an operator may be continuously presented with data defining the performance of the tool at any time. It will be appreciated that this is particularly advantageous when the tool is under the ground or otherwise out of sight of the operator.

In a particular embodiment of the invention, the tool is a rotatable boring tool and the apparatus is operable to monitor the rate of rotation of the tool. Parameters such as "depth or cut per edge" or "penetration per revolution" can be calculated by the processing means by combining rate of rotation with depth measurements. These parameters help an operator to ptimise the performance and endurance of the boring tool and in particular of the cutting edges thereof.

Such cutting edges are commonly abraded in operation, the degree of abrasion often being related to the depth of cut taken by each edge, and to the speed at which the cut is made. In general abrasion will diminish with increasing depth of cut up to a limit beyond which cutting forces reach values likely to fracture or otherwise damage the cutting edges.

The apparatus can be constructed to be able to store values of parameters such as penetration per revolution measured during previous operations and/or manually entered and to display such values for an operator to compare with values being calculated during an operation. This is particularly helpful to the operator when the optimum value of the parameter in question is dependent upon the nature and strength of the medium being worked (as is the case of penetration per revolution).

Apparatus according to the present invention may also be constructed so that automatic control of certain operations such as positioning driving and powering the tool is effected in dependence upon monitored values of operational parameters.

For example, an impacting mass may be released automatically when it has been lifted to a particular height, i.e. when it has a particular potential energy.

As another example apparatus according to the invention may be adapted to be used to measure and record the angle to which a support such as a hoist for the tool may be slewed in order either to move the tool to a new operating location or, in the case of excavating tools, to discharge debris contained therein at a safe distance from the excavation. In such cyclical operations much time may be saved by use of the preseent invention which enables rapid and precise re-location of the tool as it is returned to the excavation or of an impacting mass as it is returned to a location from which it may have deviated during fall or impact.

The slewing measurement may be used in conjunction with a height or depth measurement to prevent slewing during hoisting or lowering being carried out prematurely, for example slewing before a tool is out of the ground or iowering before a tool is properly located above a hole. The two measurements may be processed together in relation to time and be applied in order automatically to control the process.

Yet another example of this use of the invention occurs in boring equipment where an extensible bar known as a kelly bar is commonly used to maintain the direction of the tool in a bore hole. The kelly bar is usually attached by its lower end to the tool and guided at its upper end by hoisting equipment comprised by a tiltable mast.

A common problem is encountered in present practice because the kelly bar tends to deflect under gravitational and operational loading allowing a boring tool to deviate from a specified rake. This deviation tends to vary with depth.

Apparatus according to the present invention can enable processing of measurements of tool direction in relation to depth and in relation to pre-determined kelly bar deflections in order to yield parameters indicating the required adjustment of the direction of the kelly bar guiding equipment to compensate for deflection.

Apparatus of the present invention may also be used to provide means, additional to and associated with those already described, for monitoring the condition and performance of auxiliary mechanical, electrical or hydraulic power and control systems used to direct and orientate the tools as required in order to facilitate the operation and endurance of the equipment as a whole. For example, hoists or cranes employed to raise or lower impacting, vibrating, or penetrating tools may be monitored for loading so that safe working loads are not exceeded and load parameters may be controlled and applied to hoists in order to prevent the operator applying excessive loading.Alternatively, measurements of tool direction may be adapted for use during travelling of the equipment from one location to another in order to warn the operator of inclinations or tilts arising on rough ground sufficient to endanger the stability of the equipment. The working time of the equipment or components thereof may be recorded for maintenance purposes.

It can be seen that apparatus can be constructed according to the present invention which is readily adaptable to provide information for a variety of operations, e.g. vibration, impacting, grabbing or boring, and to provide such a store and display of information that an operator of the apparatus can readily optimise the efficiency of the apparatus in use.

By way of example, the invention will now be described in relation to the accompanying drawings, in which: Figure 1 is a view of an excavating machine mounted upon a travelling chassis and provided with rotatable tools for the purpose of boring holes in the ground which are subsequently filled with concrete in order to make pile foundations; Figure 2 is a diagrammatic view of means for translating rotational movement of a drum, shaft, wheel, pulley, or gear, into coded electronic signals; Figure 3 contains diagrammatic views, in elevation and plan, of means for detecting and measuring tilt of a mast forming part of an excavating machine such as that illustrated in Figure 1; Figure 4 is a diagrammatic view of equipment used in a process for consolidating the ground by dropping a weight upon it;; Figure 5 is a block diagram of digital electronic processing, computing, indicating, and recording equipment; and Figure 6 is a diagrammatic view of equipment used in a process for making piles by grouting an augered hole.

Referring to Figure 1 a pile boring machine 1 is slewably mounted upon a tracked chassis 2 and is equipped with a boring tool 3, which in this example is an auger, attached to the lower end of an extensible and rotatable kelly bar 4. The lower portion of the kelly bar 4 passes through a rotatable ring 5 which drives it via sliding keys (not shown). The upper end of the kelly bar 4 carries a bracket 6 able to slide up and down a mast 7. The combination of the sliding bracket 6 and the ring 5 guides and directs the kelly bar 4 which in turn guides, directs and rotates the tool 3. The mast 7 may be set vertical or inclined according to the direction required of the bored hole. The mast 7 is propped and tilted by the hydraulic rams 8.

The kelly bar 4 may be lowered or raised, in order to direct the tool 3 into or out of the ground, by the hoist rope 9 which passes over sheaves 10 and 11 and thence to a hoist drum 12.

That part of the excavating machine so far described is slewably mounted upon the tracked chassis 2 by way of a large rotary bearing 13 located between the two. The slewing action, which is required in order to facilitate alignment of the boring tool 3 with the axis of the hole in the ground or in order to permit the boring tool 3, when out of the ground, to be swung away from the hole whilst debris is being discharged or whilst other operations such as casing of the hole are in progress, is achieved by rotating a pinion 14 which is in engagement with a gear ring 1 5.

The gear ring 1 5 is in fact attached to the vehicular chassis 2 whilst the pinion 14 is carried by the slewing portion of the excavator, hence rotation of the pinion 14 will cause the slewing parts to rotate as a whole relative to the vehicular chassis. The pinion-gear combination 14, 1 5 may in certain configurations be replaced with a sprocket and chain combination or a system of links and rams in order to suit the space available for the slewing drive.

The chassis 2 is tracked in order to facilitate movement over rough ground. In machines operating on prepared sites, wheels might be used in place of tracks. The chassis may be equipped with stabilising rams 1 6 bearing against the surface of the ground and used to lift the chassis, to stabilise it, to level it, or to prevent it sinking into soft ground. When such rams are provided they may be linked with and controlled by the instrumentation and control system of the excavator in accordance with this invention.

In this example upward or downward motion of the boring tool 3 is monitored in terms of rotation of the rope sheave 10 which, in the absence of slip, is directly related to movement of the rope 9 which in turn is equivalent to movement of the tool 3. In appropriate circumstances movement of the tool 3 may be monitored in terms of rotation of the hoist drum 12 but the relationship between rope movement and rum rotation becomes complicated if more than one layer of rope is wound on the drum.

In either case rotational movement of the drum 12 or the sheave 10 is translated into electronic digital coded signals by the encoder now to be described with reference to Figure 2.

The encoder comprises essentially a toothed wheel 17 and two electromagnetic proximity detectors 1 8 and 1 9 which signal the passage nearby of a tooth. The sequence of signals from the two detectors 18, 19 indicates the direction in which the tooth is moving and hence the direction, up or down, in which the boring tool 3 is going.

Each detector 1 8 or 1 9 comprises a small coil excited by an alternating electric current which produces an alternating magnetic field in and external to the detector. When this field is invaded by metal, or when the amount of metal within range of the field changes, the consequential change in magnetic induction of the system causes a change in voltage induced in detector coils also incorporated in the detectors. There is commonly an increase in the induced voltage as a tooth approaches, followed by a decrease as the tooth retreats. Each detector thus produces a signal during the passage of a tooth which when rectified approximates to a square wave and is amenable to electronic shaping into a digital pulse. The lag or lead of pulses from one detector relative to the other may be used to indicate direction of movement of the teeth.One revolution of the toothed wheel 1 7 will therefore produce a number of pulses from each detector equal to the number of teeth on the wheel. If then the tooth wheel is attached to and rotates with either the sheave wheel 10 or the hoist drum 1 2 that number of pulses will represent the passage over the drum or sheave of a particular length of hoist rope 9 the length in question being determined by the geometry of the drum or sheaves and of the rope 9. That length is directly related to the movement of the tool 3.

In an alternative embodiment electrical pulses may be generated by light passing through slots in a disc, geared to or attached to the drum or sheave, and faliing upon a photo-sensitive cell.

The pulses so generated may be utilised in the manner described for the electromagnetic encoder.

In this example the direction of the boring tool 3 and hence the axis of the hole which it is being used to make, is monitored in terms of the direction of the mast 7 to which the kelly bar 4 is slideably attached and guided by the bracket 6.

The kelly bar 4 is also guided by the rotatable ring 5 which is attached to the mast 7. The boring tool 3 is firmly attached to the lower end of the kelly bar 4 and is therefore aligned with it, the kelly bar 4 is in turn aligned with the mast 7 by the attachments described.

The measurement of mast direction will now be described with reference to Figure 3.

Two commercially-available spirit levels 20 and 21 are attached to the mast 7 and disposed at right angles to one another in a plane at right angles to the axis of the mast. The plane is therefore horizontal when the mast 7 is vertical and the spirit levels would be set to read zero in that condition. The axis of one spirit level say 20 would conveniently be aligned with the general forward-rearward axis of the excavating machine as it is comprehended by the operator and the other 21 would conveniently be aligned with what would generally be accepted as the transverse direction. Each spirit level is filled with an electrically conducting liquid and equipped with three electrodes a, b and c immersed in the liquid, one electrode b being located at the centre of the level and a and c at opposite ends.As is well known, tilting of the spirit level from the horizontal would cause the bubble in the fluid to move from its central position towards electrode a or c according to the direction of tilt. This would produce corresponding changes in electrical resistance measured between electrode b and either a or c. These changes are normally measured and amplified electrically and used directly to influence a voltmeter or ammeter used to display the magnitude and direction of tilt. They may however be converted by conventional circuitry into digital electronic signals for use in digital display, recording or processing.In the present invention the signals are displayed in order to assist the operator in setting-up the excavating machine level on the stabilising jacks 1 6 and in adjusting the direction of the mast 7 by means of the mast propping rams 8 in order to set and maintain the required direction of boring. The signals are also processed and printed in order to confirm the correctness of that setting. The signals may also be processed in relation to signals from the slewing monitor already described and applied to operate the valves operating the rams 8 and 1 6 in order automatically to maintain a chosen direction of boring.When boring non-vertical or raked holes signals from the depth indicator already described might be taken into account in processing signals from the direction monitoring equipment so that additional adjustments might be made to the mast direction in order to eliminate error arising from deflection under load or gravity of the kelly bar 4. It will be understood that the magnitude of such adjustments would be affected by the depth of the hole and would be determined according to processing instructions previously established.

In this example of an excavator employed to bore holes in the ground it is necessary in certain kinds of ground carefully to regulate the speed of rotation of the boring tool and the rate at which it is advanced so as to obtain optimum performance and endurance of the tool. For example in boring certain types of clay using an auger type tool 3 it is often beneficial to employ a high speed of rotation coupled with a substantial rate of advance, whereas in boring rock slow rotation and advance may be necessary in order to avoid damage to the boring tool 3.

For these purposes it is necessary to add to the instrumentation already described means for monitoring the rotation of the rool 3. This is conveniently achieved by the use of an encoder of the type already described in connection with the measurement of depth. In this case it would be attached to and rotate with the drive ring 5 or to some convenient shaft or wheel engaged in the transmission of drive to the ring 5. Digital output from this instrument would either be processed in relation to time and displayed or recorded as a rate of rotation of the boring tool 3, or for more direct control purposes it would be processed in relation to the measurement of depth in order to derive a parameter representing penetration per revolution for comparison with pre-determined values know to be appropriate to prevailing ground conditions. That comparison would be employed normally to regulate movement of the hoist 1 2 governing advance of the tool 3 in order to maintain the optimum rate of advance.

Separate control of speed of rotation in order to maintain appropriate rates at depths corresponding to particular properties of material in the ground might also be imposed in accordance with a predetermined programme.

In another embodiment of the invention it is applied to measurement and indication of the height above the ground of a weight suspended from a conventional crane. The weight is then dropped by the crane in order to impact and compact the ground. The process is repeated until satisfactory consolidation is achieved. The execution of such a process is greatly facilitated if the operator of the crane is presented with a display of height so that he may determine the proper moment to release the weight in order to comply with his instructions. Alternatively an automatic release mechanism may be provided, set to operate at a pre-determined height.

Additionally, in order to satisfy contract conditions imposed upon such an operation, it may be necessary to provide printed evidence of the amount of dynamic energy available in the weight as it encounters the ground or of the total of such energy provided in repeated impacts. In one such embodiment illustrated in Figure 4 an ordinary crane 22 suspends a mass or weight 23.

The rope sheave 24 around which the hoist rope 25 passes is provided with an encoder substantially as heretofore described in connection with Figure 2. The encoder generates electronic digital coded signals related to rotation of the rope sheave 24 and hence to the movement of the rope 25. If a datum signal is noted with the weight 23 touching the ground 26, it may be subtracted from a signal given when the weight is suspended in order to obtain a measure of the height of the weight above the ground. In order precisely to determine the point at which the weight is touching the ground, tension in the rope 25 may be detected by a force measuring transducer, a load-related electronic signal from the transducer being employed to mark the takeup of load by the rope 25.In this particular application the said signal is obtained from strain gauges mounted on one of the pins 27 securing the jib 28 to the crane 22. These pins are subjected to a shearing stress roughly proportional to the load carried by the jib 28, this stress is measured by the aforementioned strain gauges producing a proportional electronic signal which may be converted to a digital signal for use in the central processing unit.

Referring now to Figure 5, a central processing unit 29 incorporating a microprocessor receives signals from the encoder associated with the sheave 24 and from the strain gauge load transducers associated with the pin 27. It is provided with circuits for converting these signals into digital form and is programmed so as: 1. To memorize the encoder signal corresponding with a signal from the load transducer indicating the onset of tension in the rope 25 and to subtract it from subsequent signals emanating from the encoder.

2. To convert the difference signal obtained under 1 above into a numerical meausure of height (e.g. metres) and display it on the illuminated display 30.

3. To compare the encoder signal with a value pre-set into the central processor 29 via a manual keyboard 31 and to operate an audible warning device 32 when the two signals are equivalent, thus indicating to the operator that a specified height has been reached by the weight 23.

4. To multiply the difference signal obtained in 2 above by a pre-set value (also inserted via the keyboard 31) corresponding to the mass of weight 23 in order to obtain a product equivalent to the potential energy of the weight 23 at the height from which it is dropped. The product is also equivalent to the kinetic energy of the said weight as it hits the ground.

5. To memorize the energy-value obtained in 4 above for recording on command by the printer 33 together with information as to time and date, provided by the electonic clock incorporated in the central processor 29 and information identifying the location of the impact and the contract on which it took place.

6. To summate successive energy-values obtained as in 5 above for printing as a total on command.

In advanced form of this embodiment the signal employed to activate the audible warning device 32 is also employed to initiate the fall of the weight 23, and signals from the encoder may be further utilised to operate brakes and clutches of the crane 22 in order a to regulate the release of tension in the rope 25 (as the weight begins to fall) in a manner intended to avoid excessive recoil of the jib 28 and b to arrest movement of the rope 25 as the weight 23 hits the ground 26, in a manner intended to avoid excessive slackness in the rope 25.

In a further embodiment of the invention, as illustrated by Figure 6, a hole is bored in the ground by a rotating auger 34 suspended from a conventional crane. The crane is equipped with a rope sheave 35 provided with a rotational encoder substantially as heretofore described. In the process to which this embodiment is applied, a grout, usually but not exclusively cement or concrete, is pumped via a hose 36 to a central duct 37 in the auger 34 as it is slowly raised after having bored to a designated depth. The grout fills the hole as it is vacated by the auger, in order to form a pile, and it is important that the rate of raising the auger should correspond with the rate of flow of the grout in order to avoid either cavitation or overfilling of the hole.Accordingly a flow meter 37 is incorporated in the line of the hose supplying the grout and is adapted to provide electronic signals representative of the grout flow rate. These signals together with those emanating from the rotational encoder are fed to a central processing unit substantially as heretofore described, conveniently located in the cab of the crane, but in this embodient circuited and programmed to: 1) Digitalize and convert the flow meter signals into a rate of rise of the surface of the grout in the hole, expressed in such units as metres per second, by dividing the flow rate by a pre-set number related to the cross-sectional area of the hole.

2) Convert the rotational encoder signals into a rate of rise of the auger by dividing the said signals by time and expressing the result in the same units as used in 1) above.

3) Subtract the rate obtained in 2) above from that obtained in 1) and present the positive or negative difference as an illuminated display so that the operator may know whether he is raising the auger too fast or too slow.

Alternatively, or additionally, the central processing unit may be circuited and programmed to: 1) Integrate the flow meter readings in order to determine the volume of grout supplied to the hole, and divide the sum thus obtained by a preset number related to the cross-sectional are of the depth of the surface of the grout in the hole at intevals of, say, one second.

2) Convert the rotational encoder readings into a representation of the depth of the auger in the hole, expressed in the same units as in 1) above, such as metres.

3) Subtract the depth obtained in 1) above from that obtained in 2) above in order to obtain a measure of either the gap between the bottom of the auger and the surface of the grout or the extent to which the auger is immersed in the grout. The difference is presented as an illuminated display for the information of the operator.

The central processing unit may additionally be programmed to display on command the depth of the auger during boring, to memorize the maximum dpeth reached and to print it, on command, together with time, date, and other numbers identifying the location of the hole.

Claims (27)

Claims

1. Apparatus for working the surface of a medium comprising a tool to work said surface, means for monitoring the movement of said tool when the apparatus is in use in such a way as to provide data indicative of the position of said tool relative to a predetermined point on said surface, processing means for processing said data in accordance with pre-set relationships and means for producing a display and/or a readable record from the processed data.

2. Apparatus according to claim 1 comprising a support member fixed to move with the tool and fixed to move with an elongate flexible element which passes round a wheel wherein said monitoring means comprises means for measuring the rotational movement of the wheel.

3. Apparatus according to claim 2 comprising a strain gauge arranged for monitoring the tension in the elongate flexible element to determine a starting position of said tool at which the tool just touches the surface to be worked, and said processing means is operable to store data representing this starting position as said predetermined point.

4. Apparatus according to claim 2 or claim 3 wherein said monitoring means comprises a toothed wheel arranged to rotate with the first wheel and at least one electromagnetic detector arranged to generate a voltage pulse on each occasion that a tooth of the toothed wheel passes the detector, so that the number of pulses generated is dependent upon the distance moved by the tool.

5. Apparatus according to claim 2 or claim 3 comprising a slotted disc arranged to rotate with said first wheel so as periodically to interrupt a light path between a light emitter and a photosensitive detector which detector is arranged to generate a number of electric pulses which number depends on the distance moved by the tool.

6. Apparatus according to claim 4 or claim 5 comprising two of said detectors arranged adjacent to one another around the perimeter of the toothed or slotted wheel, and means for determining the direction of movement of the tool in dependence upon the sequence of the pulses generated by the two detectors.

7. Apparatus according to any preceding claim wherein said monitoring means comprises a spirit level mounted on a platform fixedly attached to said tool, the spirit level being operable to provide, and to supply to the processing means, angular positional data in electrical format.

8. Apparatus according to claim 6 comprising a second spirit level arranged substantially perpendicular to the first spirit level.

9. Apparatus according to claim 6 or claim 7 wherein the or each spirit level comprises an electrically conductive liquid and a plurality of electrodes immersed in the liquid and spaced along the length of the or each spirit level.

10. Apparatus according to any one of the preceding claims wherein said tool is a rotatable boring tool and the monitoring means is operable to measure the depth of a bore hole made by the boring tool.

11. Apparatus according to claim 10 comprising means to measure the rate of rotation of the boring tool in use.

1 2. Apparatus according to claim 11 wherein said processing means is operable to calculate the depth of penetration per revolution of the boring tool.

1 3. Apparatus according to claim 12 comprising storage means containing, or operable to receive, tabular information representing predetermined values of penetration per revolution, and said processing means is operable to compare a calculated value with the tabulated values and to effect regulation of the rotation and/or penetration of the tool in dependence upon the results of the comparison.

14. Apparatus according to any one of claims 10 to 12 wherein said processing means is operable to provide data indicative of the differential with respect to time of depth measurements to produce data indicative of the speed at which the boring tool is penetrating a medium.

1 5. Apparatus according to any one of the preceding claims wherein said tool is a hollow elongate tube and means are provided which are operable to measure the rate of flow of a medium through the region within the tube.

1 6. Apparatus according to claim 1 5 when used for boring a hole and then filling it with a substance, wherein said processing means is perable to calculate from rate of flow measurements and depth positional measurements, the distance separating the boring tool from the surface of the filler substance in the bored hole.

17. Apparatus according to claim 1 6 wherein said processing means is further operable to calculate the difference between the rate of rise of the filling substance in the hole and the rate of rise of the boring tool in the hole.

1 8. Apparatus according to claim 1 7 wherein feedback means are provided to control the rate of flow of the substance and/or the rate of rise of the boring tool in dependence upon the results of the difference calculations.

1 9. Apparatus according to any one of claims 1 to 9 wherein said tool is an impacting mass and said apparatus is operable to determine the height of the mass from the surface to be impacted.

20. Apparatus according to claim 1 9 wherein said processing means is operable to calculate the potential energy of the mass in dependence upon its height and pre-set data representing the weight of the mass.

21. Apparatus according to claim 20 comprising storage means for storing a pre-set value of potential energy, comparator means for continuously comparing the stored value with calculated values and automatic control means for releasing the mass for impacting when correspondence is found between the stored value and a calculated value.

22. Apparatus according to any preceding claim comprising electronic clock means and means for entering into said processing means data identifying one or more fixed operating parameters, and wherein the display means is operable to display processed data in conjunction with time information derived from said clock means and one or more of said fixed operating parameters.

23. Apparatus according to any preceding claim wherein said display means comprises a digital display.

24. Apparatus according to any preceding claim wherein said display means comprises means for providing a printed record.

25. Apparatus accordingly to any preceding claim comprising storage means for accumulating processed data.

26. Apparatus substantially as hereinbefore described with reference to Figures 1,4 or 6, optionally as modified by Figures 2,3 or 5, of the accompanying drawings.

27. A method of working a surface of a medium, in which there is used apparatus according to any preceding claim.