NO338167B1 - Method and apparatus for roughing - Google Patents

Abstract

Trenching apparatus comprises a cutting device (23), preferably an endless chain cutter, mounted on a prime mover (21) for positioning the cutting device in a trench (18) with the prime mover movable on the ground surface (22) above the level of the trench. Where the cutting device is a chain cutter, the boom projects forwardly and downwardly relative to the direction of cutting the trench, and drive means are arranged to drive the chain in a direction to carry the cutting elements upwardly around the distal end of the boom and rearwardly along the upper run (30) of the endless chain cutter (23). In operation the distal end of the chain cutter (23) is positioned against the end face of the trench at the bottom of the trench (18); the prime mover (21) moves the chain cutter forwardly in the trench while operating the chain cutter, so as to produce an undercut (55) in the end face (54) of the trench; and the lifting means (25) lifts the cutting device (23) upwardly from the undercut through the material of the end face so as to cut material from the end face of the trench.

Description

The present invention relates to a method for trenching, and a trench arrangement, both of which are particularly, but not exclusively, applicable to cutting a trench in rock.

Many trenching machines are known for digging trenches in the earth using a drive motor, such as a crawler tractor, or a conventional tractor for pulling a trailer, where a cutting device is positioned in the trench on a boom. The main examples are a cutting rotor rotating about an axis that is across the trench, known as a rip cutter, or one or more cutting rotors rotating about an axis aligned along the length of the boom, generally known as a milling cutter, or a cutter which has an elongated, endless carrier which carries a plurality of cutting elements, and which moves in series along the upper and lower runs of the boom, known as a chain cutting device. Where a cutting rotor is used, it is mounted on the distal end of a boom which projects forwards and downwards from the drive motor, relative to the direction of trench digging. Where a chain cutting device is used, this is usually mounted on a boom which extends downwards and backwards from the drive motor in relation to the cutting direction of the ditch. In such an arrangement, the elongate support member moves in a direction such that the cutting elements move downwardly around the distal end of the boom, and up and forward along the lower course of the movable elongate support member. In all these forms of trenching machines, a positioning device is usually provided for raising and lowering the distal end of the cutting boom to vary the height of the trench. Examples of such trenching machines can be found, for example, in CH-A-239498 (Enterprise de Grands Travaux SA), and WO 95/13433 (Mastenbroek 6Company Limited).

All these types of trenching machines are generally satisfactory for cutting trenches under conditions of normal soil, but are not suitable for cutting trenches in rock or other hard base materials. For cutting trenches in hard rock, labour-intensive methods are usually used where impact tools and explosives are used.

In another field, which is not connected with trenching, there are known tunnel construction machines for the construction of tunnels in mountains, where a cutting rotor known as a ball cutting device projects forward on a boom from a drive motor, and is movable in a vertical plane by turning the boom on the drive motor. In use, the cutting rotor is lowered to the bottom of the tunnel and the drive motor is advanced with the cutting rotor to engage the end face of the tunnel at the bottom level to produce an undercut. The cutting boom is then turned in an upward direction by hydraulic pressure pistons, so that the cutting rotor or rotors are lifted upwards to cut a slice of the material from the end face of the tunnel. The shear boom is raised by applying a force between the shear boom and the bottom of the tunnel. In a variant of such a device, a form of a chain cutting device is provided which is moved in a row along the upper and lower runs along the cutting boom and around the distal end of the cutting boom for use, for example, in mining in connection with coal or soft rock. In such a machine, the endless movable supports which carry the cutting means are driven in one direction so that the cutting means move upwards around the distal end of the boom and move backwards along the upper course of the movable support member. Examples of both forms of tunneling equipment can be found in brochures published in 1982 by Hawker Sidley Dosco Overseas Engineering Limited entitled DOSCO 1982 "The Twin Boom TB600" and DOSCO 1982 "Mark II Heavy Duty Dint-header".

In addition to this known technique, EP-A-0080802 (Wallace) describes a machine for cutting a trench in rock using a rip-off cutting device. EP-A-0080802 also recognizes as prior art a known ditch cutting machine comprising a giant chain saw mounted on a belt-type earring chassis and equipped with tungsten carbide teeth which literally saws away the rock. However, this machine is confirmed to have the disadvantage that considerable jumping is produced along the saw, particularly when cutting hard rock, and this reduces the cutting efficiency. This problem occurs primarily due to the long unsupported length of the cutting arm. In EP-A-0080802 there is also a mention of ball cutting machines, such as those described above in connection with tunnel construction, and it is said that other rock cutting machines for surface mining operations are known, and that these comprises a rotatable cutting head carried at the end of a boom pivotally attached to a tracked vehicle chassis. However, it is said that these known machines cannot be used for cutting trenches, and that they are further confirmed to have a similar vibration problem because they also have a long unsupported boom that carries the cutting head.

In EP-A-0080802 it is said that these difficulties are overcome by providing a machine for cutting a trench in rock having a pivotable boom with a rotatable cutting head at the distal end, and a telescopic control arm extending between a mobile work platform and the end of the boom at the cutting head, the telescopic control arm being a hydraulically operable pressure piston which serves to move the cutting head in an arc-shaped path around the axis of rotation of the boom. The machine is operated by the hydraulic pressure piston applying a force to the cutting head with a large vertical component. In operation, the machine is positioned on both sides of the line in the trench, and the boom is lowered into contact with the ground. The cutting head is rotated under application of force by the hydraulic ram to move the cutting head in an arcuate downward path and to remove rock from the front end of the trench. A conveyor is positioned at the bottom of the trench, and the excavated mass is carried away. The boom is then raised, and the machine is moved forward, and the process is repeated.

It is said that the problem of vibration and jumping with the relatively long boom is avoided because the position where the pressure piston is connected to the boom at the cutting head increases the stability of the cutting head, eliminating the vibration and jumping problems that would be expected if the pressure piston was omitted and the cutting force was applied by the long the boom. It is said that because the control arm applies the necessary load to the cutting head, and because of the relatively short distance between the cutting head and the fulcrum, the problem of the cutting head jumping is largely avoided.

However, a disadvantage arises with this form of machine, which is admitted in EP-A-0080802, in that the force applied at the cutting head has a tendency to lift the machine out of contact with the ground. It is suggested that additional ballast may be carried, but it is nevertheless inevitable that there is a limit to the amount of force that can be applied to move the cutting head in its arcuate path without lifting surface mounted components of the device from the ground surface.

In DE-A-4213523, a trenching device is described which comprises a distal milling head which is arranged on a rotary arm and which is arranged to cut the material by rotation around an axis of rotation which stands across the axis of the arm. The arm is connected to a drive motor via a boom which is rotatably mounted at the drive motor and at the connection with the arm. Rotary movement of the boom and arm is carried out with hydraulic cylinders. The operation of the device takes place by positioning the milling head at the base of the trench, and an undercut is produced by moving the milling head forward in relation to the direction of cutting the trench. The milling head is then raised to the top of the trench by the operation of the hydraulic cylinders which control the rotation of the arm and boom. The milling head is then lowered to the bottom of the trench, and the procedure is repeated.

The mobile milling-loading device has a receiving container for receiving the milled material. Plate-shaped support elements can swing out at the sides of the arm or receiving container, and can be supported laterally against the wall in the excavation. The support elements can be swung out sideways using a double-acting hydraulic cylinder. It is said that the support elements serve for lateral support and can be arranged on the work head or on the arm. It is said that lateral support and lateral control of the working head is possible during use by means of the outward-swinging support elements. It is said that lateral support and lateral control of the working head or the arm that carries the working head is possible against the wall in the excavation during use of the milling-loading device.

GB 0025899 (NO20031795) shows a ditching device comprising a cutting device, preferably a cutting device with an endless chain.

It is an aim of the present invention to provide a trench cutting device where the problems outlined above are avoided or reduced.

In accordance with the present invention, there is provided a method for trenching, comprising positioning a cutting device in a trench, which cutting device is mounted on a drive motor which is movable on the surface of the ground above the trench, which cutting device includes a rotatable cutting boom; positioning the cutting device against the end face of the trench below the level of the ground surface, bringing the end face of the trench into engagement with the cutting device, and moving the cutting device forward in the trench during operation of the cutting device to produce an undercut in the end face of the trench; and lifting the boom upward in a substantially vertical plane from the undercut up to the top of the trench by exerting a lifting force between the boom and the surface of the ground above the trench, and operating the cutting means during the upward movement to cut the material from the end face of the trench; wherein the method includes bringing the sides of the trench into engagement with side components of the device during the upward movement of the boom, and exerting a further upward force on the boom, which acts between the side components and the boom during the upward cutting movement of the cutting device, while the side components are engaged with sides of the ditch.

It should be understood that where features of the invention are described here with regard to a method according to the invention, such features can also be provided with regard to devices according to the invention and vice versa.

In accordance with the invention, a ditching device comprising a drive motor is particularly provided; a cutting device including a rotatable cutting boom; mounting means for mounting the cutting device on the drive motor and for positioning the cutting device in a trench with the drive motor movable on the surface of the ground above the level of the trench, the cutting device being arranged to engage an end face of the trench to cut the material from the end face of the trench; lifting means arranged to lift the boom in a substantially vertical plane from an undercut in an end surface at the bottom of the trench up to the top of the trench, during operation of the cutting device in cutting engagement with the end surface of the trench, by exerting an upward force between the boom and the surface of the ground over the ditch; the device including side components which are adapted to engage the sides of the trench during the upward movement of the boom, and a driven link connecting the side components and the cutter boom, and which is arranged to exert a further upward force on the cutter boom, which acts between the side components and the boom during the upward movement of the cutting device while the side components are engaged with the sides of the ditch.

The method according to the invention offers the advantage that during the upward cutting stroke, the force exerted between the cutting device and the surface of the ground is only limited by the force that is generated and applied, and is not limited by components in the ditching device potentially rising from the ground, as in known techniques where the cutting performed on a downward stroke of the cutting device. It is not necessary to provide significant weight in the part of the device on which the lifting means are mounted, as would be the case if the lifting means were pressed downwards on the cutting device during the cutting stroke.

A number of preferred features of the invention will now be described. In the step of producing the undercut, the cutting device is preferably positioned to engage with the end surface mainly at the bottom of the trench. It is also preferred that the cutting device is mounted on a rotatable boom that extends forwards in relation to the direction of cutting the trench, and that the lifting step is performed by moving the cutting device along an arc-shaped path defined by the turning movement of the boom. In such an arrangement, the preferred step of lifting the cutting device upwards is carried out by exerting a force between the cutting device and an area of the ground surface which is located at a distance from the axis of rotation of the boom in a direction forward along the trench. It is also preferred that the step of lifting the cutting device upwards is carried out by exerting a force between the cutting device and the surface of the ground in a direction which is substantially perpendicular to the axis of the boom, and that the step of lifting the cutting device upwards is carried out by exerting a force of the distal end of the boom. The step of lifting the cutting device upwards is preferably carried out by exerting a force in a direction which is inclined in relation to the vertical in a direction above in relation to the direction of cutting the trench. Such arrangements increase the stability of the device and enable the most efficient use of the upward force applied to the cutting device.

Although a number of different cutting devices may be used in embodiments of the invention, it is particularly preferred that the step of cutting the material from the end face of the trench is performed by moving a plurality of cutting elements along the upper and lower runs of an elongated, endless support means which is moved along the boom, the cutting elements being driven in such a way that the elements at the distal end of the cutting boom move in an upward direction around the end of the cutting boom and backwards along the upper course in relation to the direction of cutting the trench. Such an arrangement is particularly advantageous because the cutting elements engage the undercut in an upward and rearward direction at the distal end of the boom to cooperate with the lifting force to bring the cutting teeth into cutting engagement with the underlying material. In the case of hard rock, this allows an efficient cutting action where the movement of the cutting elements cooperates with the upward movement of the lifting means and the forward movement of the drive motor during cutting. The upper run of the elongate endless carrier means may also be effective in carrying excavated mass away, so that there is no need to provide a separate endless conveyor, or other means, to remove the excavated mass from the trench, although in some cases such an additional conveyor can be arranged behind the chain cutting device.

In alternative arrangements, the cutting device may comprise a cutting rotor mounted at the end of the boom, and the step of cutting the material from the end face of the trench is performed by rotating the cutting rotor about an axis aligned across the length of the trench or by rotating the cutting rotor about an axis which is aligned generally along the length of the boom.

In preferred forms, it can be arranged so that the lifting means are designed to provide a power stroke in the upward direction and a return stroke in the downward direction, and to provide a greater force in the power stroke than in the return stroke.

It is preferred that the device includes a mobile base unit which is located at a distance forward from a drive motor and is connected to this for movement together with the drive motor, the lifting means being mounted so that they exert the lifting force between the cutting device and the drive motor and/or the mobile base. In a particularly preferred form, the mobile base unit is connected to the drive motor by means of a framework, and the lifting means include a pivotable arm which is pivotable relative to the drive motor and which extends forward relative to it, a pivotable articulated arm which at one end is connected to a front end of the pivotable arm and at the other end to the beam of the cutting device, and a source of lifting force which is connected between the arm at a position located between the two ends thereof and the framework at a position located between the two ends of this. The lifting means preferably include a hydraulic pressure piston.

In accordance with a particularly preferred feature of the invention, the device may include control means which are programmed to perform a predetermined cycle of operation, where: (i) the mounting means positions the cutting device against the end surface of the trench at the bottom of the trench; (ii) the drive motor moves the cutting device forward a predetermined distance in the trench during operation of the cutting device to produce an undercut in the end face of the trench; (iii) the lifting means lift the cutting device upwards from the undercut through the end face material during operation of the cutting device; (iv) the drive motor moves the cutting device backward a predetermined distance;

(v) the lifting means lowers the cutting device to the bottom of the trench; and

(vi) the preceding steps are repeated.

The base unit consists of a structure mounted on a screed that slides over the ground when propelled forward by the drive motor. In other arrangements, the base may be mounted on wheels, or it may in some cases be mounted on another drive motor which is arranged to cooperate with the first drive motor to move the cutting device along the ditch.

Embodiments of the invention will now be described as examples with reference to the accompanying drawings, where: Figures 1 and 2 show perspective views of known trench cutting devices described in EP-A-0080802, Figure 2 shows details of the cutting device in the device; Figure 3 is a schematic side view of a trench cutting device which gives the present invention concrete form, and which uses a chain cutting device; Figure 3a is a side view of the distal end of a chain cutting device suitable for use in the embodiment of Figure 3, omitting for clarity a side cutting wheel shown in Figure 3; Figure 3b shows the front end of the device in Figure 3, at another operational stage, where the cutting boom is raised; Figure 3c is a rear view of a side clamp assembly in the device of Figure 3, viewed in direction C of Figure 3; Figure 4 is a schematic end view of the front of the device shown in Figure 3, viewed in the direction A of Figure 3; Figure 5 is a schematic side view of details of the chain cutting device shown in Figure 3, and Figure 5a is part of a plan view seen in a direction B in Figure 5 and shows the lower end of the sheath cutting device in Figure 5; Figure 6a is a block diagram of the control means programmed to perform a predetermined operation cycle of the device, and Figure 6b is a flow chart of the operation cycle; Figures 7a to 7g are schematic illustrations showing a series of steps in the operation of an embodiment of the invention shown in Figures 3 to 6; and Figure 8 shows a schematic side view of yet another alternative embodiment of the invention, where the cutting device comprises a milling-cutting device. Figures 1 and 2 show a known trench cutting device which is described in EP-A-0080802 for cutting a trench in rock. Two tracked vehicle chassis 3 and 5 are connected by connecting rods 7, the rear tracked vehicle 3 having a cutting boom 2 which is rotatably mounted at 6. The front end of the boom 2 has a cutting rotor 7 which is driven in rotation about an axis which stands across the trench to be cut. The distal end of the boom 2 is connected to the front tracked vehicle 5 with a telescopic control arm 8 comprising a hydraulic pressure piston and telescopically extending sleeves which are connected to the boom 2 with a coupling 9.1 operation the machine is positioned on both sides of the line for the ditch, and boom 2 is lowered into contact with the ground. The cutting head 7 is rotated

while applying force by means of the hydraulic pressure piston 8 to move the cutting head 7 in an arc-shaped path downwards, and to remove rock from the front end of the trench. A conveyor 5 with an endless chain is positioned behind the cutting rotor 7, and excavated mass is carried away. Boom 2 is then raised and the machine is moved forward, and the process is repeated.

In such a machine, a disadvantage arises in that the force applied to the cutting head 7 has a tendency to lift the front tracked vehicle 5 out of contact with the ground. In an attempt to counteract this problem, firstly, the hydraulic pressure piston 8 is mounted on a heavy independent tracked vehicle chassis 5, and secondly, additional ballast can be carried by one or both of the front rear tracked vehicles 5 and 3 .

Figures 3 to 4 show a ditch cutting device which gives the present invention concrete form. The components in the execution of the invention which are known in the field can generally be as indicated in the previously mentioned document EP-A.-0080802, modified as necessary in light of the features of the invention which have been given concrete form in the device shown. One should first refer to figure 3, where the trenching device for cutting a trench in rock or the like has a first drive motor 21 which has a cab 35, and a movable base unit 26 which consists of another drive motor without a cab. Each drive motor comprises a tracked vehicle chassis for movement over the ground surface 22. A cutting device generally indicated at 23 is mounted on the drive motor 21 by means of mounting means generally indicated at 24. A lifting means generally indicated at 25 is connected to the cutting device 23 in the region of its distal end. The mobile base unit 26 is connected to the first drive motor 21 by means of a framework 27. The entire operation of the machine is controlled by control means schematically indicated by 34, located in a cab 35 for the drive motor 21.

Considering the detailed construction of the embodiment shown in Figure 3, the cutting device 23 includes an endless chain cutting device, which comprises an elongated, endless carrier means 28, such as a chain, having cutting teeth

29 shown in more detail in Figure 3a. The chain 28 is moved along upper and lower runs 30 and 31 on a boom 32. The cutting teeth 29 pass at the end of the boom 32 around a pulley 33. The elements 29 are driven by an upper pulley 49 in such a way that the cutting elements at the distal end of the boom 32 moves upwards around the distal end of the boom and backwards along the upper race 30 in relation to the intended direction of forward movement of the drive motor 21, which is indicated by the direction X in Figure 3. Figure 3a shows the distal end of the boom 32 and details of the mounting of the teeth 29 on the endless carrier 28. The chain cutting device 23 is driven by drive means which include, for example, a hydraulic drive motor mounted in or on the drive motor 21 and the upper driven pulley 49. The cutting device 23 may generally be a chain cutting device as shown in the previously published patent application WO 95/13433, although the chain cutting device in this publication is driven to move in the opposite way to that which is shown in the present embodiment, so that the orientation of the teeth is reversed in the aforementioned earlier publication.

In the embodiment shown in figure 3, the mounting means 24 for mounting the boom 32 on the drive motor 21 comprise a pivot shaft 33A which is mounted between the two mounting elements, mounted on the main frame for the drive motor 21. The lifting means 25 include a pivotable arm 59 which is rotatable in relation to the drive motor 21 at a pivot point 61, and which extends forward in relation to this. A pivotable joint arm 59A is connected at one end to a front end of the pivotable arm 59, and at the other end to the beam 32 of the cutting device 23. A source of lifting force consisting of a hydraulic pressure piston 40 is connected between the arm 59 and the framework 27 The pressure piston 40 is connected to the arm 59 at a position between its two ends, and to the framework 27 at a position between its two ends. A drive piston 43 (Figure 3b) extends downwards from the pressure piston 40 and is connected to the framework 27 at the pivot point 44. The cutting device 23 is shown in a lower position at the base of the trench in Figure 3, and in a raised position in Figure 3b.

Figures 3 and 3 c show examples of side components according to the invention for stabilizing the rotation of the cutting boom 32. A side clamp assembly is attached to the cutting boom 32, generally denoted by 80. The main component is a transverse hydraulic pressure piston, which is generally denoted by 81 , which extends over the trench perpendicular to the direction of movement of the drive motor 21. At each end of the hydraulic pressure piston 81 there is a circular pressure plate 83 which rests against the inside of the trench. During the lifting step in the cutting cycle, the hydraulic pressure piston 81 is advanced, and the clamping plates 83 are pressed outwards towards the sides of the trench.

The clamping plates 83 are connected to the boom 32 by means of another clamping pressure piston 85 and a support comprising a pressure piston 84. The support 84 is rotatably connected between the first clamping pressure piston 81 and a pivot point 86 on the boom 32. The second clamping pressure piston 85 is rotatably connected between a pivot point 87 located between the ends of the support 84, and a pivot point 88 on the boom 32. During the driven upward stroke of the main pressure piston 40, the pinch pressure piston 84 is advanced to stabilize the movement and to assist in cutting the upward arc. It will be understood that although the main pressure piston 40 exerts an upward force between the boom 32 and the ground level 22, the clamping pressure piston 84 exerts an upward force on the boom 32, which acts between the boom 32 and the stationary position of the side clamping plates 83, which are held in place by the advanced pressure piston 81.

As shown in Figure 4, the cutting device 23 suitably has, in addition to the cutting chain 28, expansion drums 46 and 47 which extend laterally from the pulley 33 at the distal end of the cutting boom to widen the channel cut by the cutting chain. The expansion drums are removable and interchangeable to make it possible to vary the width of the trench by using drums of different widths. Figure 5a shows a detailed view of the cutting device 23. Behind the distal end of the boom 32, a deflection plate assembly 48 is positioned for collecting loose material that has been cut by the cutting chain 28 and the extension drums 46, 47. The deflection plate assembly 48 guides the loose material inwards towards a central area where the loose mass is carried upwards and backwards by the chain cutting device 23. As shown in figures 5 and 5a, the chain cutting device 28 at the top of the cutting boom 32 goes around the upper pulley 49 and deposits the loose mass on a side discharge conveyor 50 by means of a boom discharge funnel 51.

The operation of the embodiment will now be described, particularly with reference to Figures 7a to 7g, but also with reference to Figures 3 to 5b. Figures 7a to 7g show schematic representations of the different steps in the operation cycles. Figures 7a and 7b show an initial step with the start of the trench. This can be done as shown, or can alternatively be cut out by hand with explosives, impact tools or any other means. With reference to Figures 7a and 7b, however, the cutting device 23 is first lowered to the ground level 22, and the cutting device is operated while it is pressed downwards. This can conveniently be done by reverse operation of the lifting device 25, which has been described with reference to Figures 3 to 5a. As shown in Figure 7b, the result is cutting out the beginning of a trench with an arc-shaped end surface 54. During the step shown in Figures 7a and 7b, the cutting device 23 is operated in the manner described for the known machine in EP-A-080802, i.e. .cutting on the downward stroke. Alternatively, a starting hole can be provided by other conventional means, such as drilling or blasting, or by means of a rock hammer.

As shown in figure 7c, the next step is that the cutting device 23 is operated while the drive motor 21 is driven forward to produce an undercut 55 in the end face 54 of the trench. The next step is that the lifting means 25, as shown for example in Figure 3, is operated to rotate the cutting device 23 upwards from the undercut 55, while the cutting device 23 is operated to cut the material from the end face of the trench 54. This cutting operation is shown in detail. in Figure 5, which shows the material 56 being cut from the end surface 54 during upward movement of the cutting device 23 by means of lifting means 25. This produces the new end surface 54 of the trench, as shown in Figure 7d. when this is completed, the cutting device 23 is lowered to the bottom 19 of the trench 18, as shown in figure 7e. The process is then repeated by operating the cutting device and by moving the drive motor forward, as shown in Figure 7f, to produce a new undercut 55. Finally, the cutting device 23 is again raised upwards from the undercut 55 to cut a new end face 54, as shown in Figure 7g.

The main advantage of this embodiment of the invention that has been described is that the force exerted between the cutting device 23 and the ground surface 22, by means of the mobile base 26 during the upward cutting stroke of the cutting device 23, is only limited by the force produced by the lifting means 25, and is not limited by the potential floating of the base 25 up from the ground, as in the device shown in Figures 1 and 2 (where cutting is performed by the downward stroke of the cutting device). It is not necessary to provide significant weight in the part of the device where the lifting means is mounted, which would be the case if the lifting means pressed downwards on the cutting device on the cutting stroke.

Further advantages arise in connection with the cutting of the undercut 55. Because the cutting area at the distal end of the cutting device 23 is relatively limited, and because the drive motor 21 moves forward during the cutting of the undercut, the problem of penetration force in hard rock is significantly reduced, compared to the difficulty of penetration from above during a downward cutting stroke. The advantage arises because the number of cutting tools or teeth in contact with the hard rock is limited to those located at the distal end of the beam. In the embodiment according to the present invention, the available power can be concentrated in a few work tools, which results in the use of more power per tool.

With reference to Figures 6a and 6b, the block diagram on Figure 6a and the flowchart on Figure 6b will now be described. In Figure 6a, the control means 34 are shown consisting of a microprocessor 90 which receives information from a series of sensors, schematically shown as a clamp sensor 91 (to sense when the clamp assembly 80 is held firmly in position against the side walls of the trench); a clamp movement sensor 92 (for sensing the degree of movement of the clamp pressure pistons 81 and 85); an engine load control sensor 93 (to sense the load placed on the engine at various stages of the cycles); a depth of cut sensor 94 (for sensing the depth of cut of the cutting means 23); a depth of cut reference sensor 95 (for sensing the maximum depth of the device's cut relative to a required reference plane); and a sensor 96 for forward/reverse movement (to detect direction of movement of the two tracked vehicle chassis for the drive motors 21 and 26). The microprocessor is also connected to an operator control unit 97 which enables the operator to set requirements for seven functions from the device, for example seven functions as follows:

1. Forward movement.

2. Reverse movement.

3. Maximum cutting depth. cutting to the required depth, h

4. Minimum cutting depth.

5. Trench clamping on/off.

6. System on/off.

7. Manual/automatic.

The operation of the device in a predetermined automatic operation cycle incorporates the program flow chart of Figure 6b and operates in normal use as follows. First, the machine is maneuvered manually into place. Then, to cut a first part of the trench in the untouched rock, the cutting boom 32 is lowered into the surface below which is determined either manually or from a reference signal generated for example with a laser, as in the previously published patent application No. WO 95/13433 . Automatic operation is then selected. In steps 1 and 2, the device is moved forward a preset distance. The speed of forward movement is automatically controlled and balanced by the load control between the cutting power required and the engine power available to ensure maximum performance. When the preset distance has been achieved, forward movement will stop and a signal will automatically be sent to the lifting cylinder 40.1 steps 3 and 4, the lifting cylinder 40 will push the cutting device upwards while cutting the front surface of the trench. The speed of upward movement will be controlled automatically by the load control, and will balance out the cutting power required and the motor power available until the cutting device reaches a preset distance (minimum cutting depth, set with reference to the reference plane). In steps 5 and 6, the machine is moved in reverse over a preset distance. Then, in steps 7 and 8, the lift cylinder 40 will lower the cutting device down to the previously preset depth. If the operator then wishes to stop, a manual decision to stop will be entered in step 9. If not, the cycle will be repeated starting from step 1.

For increased stability during cutting into the surface of the trench, the clamping assembly 80 is added, which clamps between the side surfaces of the trench. The clone wizards 34 can be extended to also control the operation of the clamp assembly. This will be released and retracted during lowering of the cutting boom and reverse movement of the machine, but will clamp and assist during the forward movement and the upward cutting with the cutting mechanism. It will also operate automatically within the machine's operating sequence. The control of the machine can either be done manually or automatically using signals from, for example, a preset cable, wire or laser. The vertical position of the trench can be adjusted with the help of a lateral tilting system built into the machine's belt frames.

An alternative embodiment of the present invention will now be described with reference to figure 8, where the components which were previously described with reference to figures 1 to 6 are indicated with the same reference numbers. In the embodiment of Figure 8, the cutting device 23 a cutting boom 32 which has a milling cutting device 71 which is mounted at its distal end. Behind the milling cutting device 71, an endless conveyor belt 73 is mounted to remove loose material that has been cut by the milling cutting device 71. In the embodiment shown, the mobile base 26 runs in the device on belts 72. The general construction and operation of the milling cutting device 71 and the conveyor 73 for removing loose material is set forth in the earlier patent specification EP-A-0080802. The general construction and operation of the lifting means 25 in Figure 8, and the overall operation of the ditching device, is as described with reference to Figures 3 to 7 in the present application. In other arrangements, the conveyor 73 in the embodiment of Figure 8 can be used together with the chain cutting device of Figures 3 to 5b.

Accordingly, with reference to the drawings, there has been described a method of trenching which includes stabilizing the upward cutting motion of the cutting device by bringing the sides of the trench into engagement with side components of the device, and by exerting an upward force on the cutting action, which acts between the side components and the cutting device during the upward cutting movement of the cutting device. The described method includes pushing the side components outwards against the sides of the trench during the upward cutting motion of the cutting device.

With reference to the drawings, there has also been described a trenching device which includes a stabilization assembly extending rearwardly from the cutting device to stabilize the upward cutting motion of the cutting device, the stabilization assembly comprising side components adapted to engage the sides of the trench during the upward cutting motion of the cutting device, and a driven joint connecting the side components of the cutting device, and which is arranged to exert an upward force on the cutting action, which acts between the side components and the cutting device during the upward movement of the cutting device. The stabilization assembly shown includes a driven transverse component which extends between the side components and which is arranged to urge the side components outwardly against the sides of the trench during the upward cutting motion of the cutting device.

Claims (40)

1. Method of trenching, comprising: positioning a cutting device (23) in a trench, which cutting device is mounted on a drive motor (21) which is movable on the surface of the ground (22) above the trench, the cutting device (23) including a rotatable cutting boom (32) ); positioning the cutting device against the end face of the trench below the level of the ground surface, bringing the end face (54) of the trench into engagement with the cutting device, and moving the cutting device (23) forward in the trench during operation of the cutting device to produce an undercut (55) in the end face of the ditch; and lifting the boom (32) upward in a substantially vertical plane from the undercut up to the top of the trench by applying a lifting force between the boom (32) and the surface of the ground above the trench, and operating the cutting device during the upward movement to cut material from the end surface of the trench; characterized in that the method includes bringing the sides of the trench into engagement with side components (83) of the device during the upward movement of the boom (32), and exerting a further upward force on the boom (32), which acts between the side components ( 83) and the boom (32) during the upward cutting movement of the cutting device (23) while the side components (83) are engaged with the sides of the trench. 2. Method as stated in claim 1, characterized in that it includes pressing the side components (83) outwards towards the sides in the trench at a stationary position during the upward cutting movement of the cutting device (23). 3. Method according to claim 1 or 2, characterized in that it includes cutting the material from the end surface of the trench with movement of a plurality of cutting elements (29) along the upper and lower runs (30, 31) of an elongated, endless support means (28) which is moved along the rotatable boom (32), the boom projecting forwards and downwards in relation to the intended direction for cutting the trench, and in that the cutting elements (29) are driven in such a way that the elements at the distal end of the cutting boom (32) move in an upward direction around the end of the cutting boom and backwards along the upper course (30) in relation to the direction (X) of cutting the trench. 4. Method according to claim 3, characterized in that it includes cutting the trench wider than the endless support means 828) with additional cutting elements in the cutting device (23). 5. A method according to claim 4, characterized in that it includes: cutting the trench wider than the endless support means (828) by operation of a pair of cutting drums (46, 47) extending laterally from the distal end of the cutting boom (32). 6. Method according to one of the preceding claims, characterized in that it includes application of the lifting force on the cutting boom (32) below ground level. 7. Method according to one of the preceding claims, characterized in that it includes application of the lifting force next to the cutting boom (32). 8. Method according to one of the preceding claims, characterized in that the step of producing the undercut (55) is performed by driving the drive motor (21) forward over the surface of the ground during operation of the cutting device (23). 9. Method according to claim 8, characterized in that the lifting step is performed by rotating the cutting boom (32) around a pivot axis (33A) of the drive motor (21), and that the undercut (55) is produced by driving the drive motor (21) forward over the ground with driving contact with the surface of the ground (229) at a position behind the pivot axis of the boom (33A). 10. Method according to claim 7, characterized in that the undercut is produced by driving contact with the surface of the ground (22), both in a position behind the boom's axis of rotation (33A) and in a position in front of the boom's axis of rotation (33A). 11. Method according to one of the preceding claims, characterized in that the cutting device (23) in the step of producing the undercut is positioned to engage with the end surface (54) mainly at the bottom (19) in the trench. 12. Method according to one of the preceding claims, characterized in that the lifting step is carried out by moving the cutting device (23) along an arc-shaped path defined by turning movement of the boom (32). 13. Method according to one of the preceding claims, characterized in that it includes the application of a force between the cutting device (23) and an area of the surface of the ground which is located at a distance from the axis of rotation of the boom (32) in a forward direction (X) along the ditch. 14. Method according to one of the preceding claims, characterized in that it includes the application of a force between the cutting device (23) and the surface of the ground (22) in a direction essentially perpendicular to the axis of the boom. 15. Method according to one of the preceding claims, characterized in that it includes the exercise of a lifting force on the cutting device in the area of the distal end of the boom (32). 16. Method according to one of the preceding claims, characterized in that it includes the exercise of a lifting force on the cutting device in a direction inclined relative to the vertical in a direction forward relative to the direction (X) for cutting the trench. 17. Method according to one of the preceding claims, characterized in that it has a predetermined cycle of operation comprising: (i) positioning the cutting device (23) against the end face (54) of the trench in the bottom of the trench; (ii) moving the cutting device (23) forward a predetermined distance in the trench during operation of the cutting device (23) to produce the undercut in the end surface of the trench, by moving the drive motor (21) forward over the ground surface (22); (iii) pressing the side components (83) outwards against the sides of the trench at a stationary position with the cutting device (23) positioned against the end face (54) of the trench; (iv) lifting the cutting device (23) upwards from the undercut through the material (56) in the end surface during operation of the cutting device (23); (v) detachment and withdrawal of the lateral components from the sides of the trench; (vi) moving the cutting device (23) backward a predetermined distance by moving the drive motor (21) backward over the ground surface (22); (vii) lowering the cutting device (23); and (viii) repeating the previous steps. 18. Trenching device, comprising: a drive motor (21); a cutting device (23) including a rotatable cutting boom (32); mounting means (24) for mounting the cutting device (23) on the drive motor (21) and for positioning the cutting device in a ditch with the drive motor movable on the ground surface (22) above the level of the ditch, the cutting device (23) being arranged to be brought into engagement with an end face (54) of the trench for cutting material from the end face of the trench; and lifting means (25) arranged to lift the boom (32) in a substantially vertical plane from an undercut (55) in an end face (54) at the bottom of the trench, upwards to the top of the trench, during operation of the cutting device in cutting engagement with the end face of the trench, by the application of an upward force between the boom (32) and the surface of the ground (22) above the trench; characterized in that the device includes side components (83) adapted to engage with the sides of the trench during the upward movement of the boom, and a driven joint connection ( 84, 85, 86, 87, 88) which connect the side components (83) to the cutting boom (32), and which are arranged to exert a further upward force on the cutting boom (32), which acts between the side components (83) and the boom (32) ) during the upward movement of the cutting device (23) while the side components (83) are engaged with the sides of the trench. 19. Device according to claim 18, characterized in that it includes a driven transverse component (81) which extends between the side components (83), and which is arranged to press the side components (83) outwards against the sides of the trench during the upward cutting movement of the cutting device (23) . 20. Device according to claim 18 or 19, characterized in that the side components (83) are positioned behind the cutting device (23). 21. Device according to one of claims 18 to 20, characterized in that the cutting device (23) comprises an elongated, endless carrier (28) which carries a plurality of cutting elements (29) and which is moved along the upper and lower runs (30, 31) of the boom , the boom (32) being mounted to project forwards and downwards in relation to the intended direction (X) for cutting the trench, the device including drive means (49) arranged to drive the endless support means (28) in such a direction that it leads the cutting elements (29) over around the distal end of the boom (32) and backwards along the upper course (30) of the endless support means. 22. Device according to claim 21, characterized in that the cutting device (23) includes further cutting elements to widen the channel cut by the cutting elements on the endless support means (28). 23. Device according to claim 22, characterized in that the additional cutting elements are mounted on cutting drums (46, 47) which extend laterally from the distal end of the cutting boom (32). 24. Device according to one of claims 18 to 23, characterized in that the lifting means (25) are connected to the boom (32) at a position to apply the lifting force to the cutting boom (32) below ground level during normal operation. 25. Device according to one of claims 18 to 24, characterized in that the lifting means (25) are connected to the boom (32) at the sides of the boom by means of a rotatable articulated arm (59A). 26. Device according to one of claims 18 to 25, characterized in that the cutting boom (32) is mounted on the drive motor (21) for rotational movement around a rotational axis (33A) to produce the upward movement of the cutting device (23), and that the drive motor (21) is its own to produce the undercut (55) at the bottom (19) of the trench by driving the drive motor forward over the ground by driving contact with the ground surface (22) in a position behind the boom's axis of rotation (33A). 27. Device according to one of claims 18 to 25, characterized in that the lifting means (25) are mounted in such a way that they exert the lifting force in a direction which is inclined in relation to the vertical, in use in a direction directed forward in relation to the direction (X) for cutting of the ditch. 28. Device according to one of claims 18 to 27, characterized in that the lifting means (25) are arranged to move the cutting device (23) along an arc-shaped path defined by turning movement of the boom (32). 29. Device according to one of claims 18 to 28, characterized in that the lifting means (25) are mounted in such a way that they exert the lifting force between the cutting device (23) and the surface of the ground (22) in a direction which is mainly perpendicular to the axis of the boom. 30. Device according to one of claims 18 to 29, characterized in that the lifting means (25) are connected to the boom (32) in the area of the distal end of the boom. 31. Device according to one of claims 18 to 30, characterized in that the drive motor (21) includes a rear tracked vehicle chassis (39) positioned behind the boom's axis of rotation (33A). 32. Device according to claim 31, characterized in that it includes a mobile base (26) which is placed at a distance in front of the axis of rotation of the boom (3 3 A) and is connected to this for movement together with this. 33. Device according to claim 32, characterized in that the mobile base unit (26) is connected to the rear tracked vehicle chassis (39) by means of a framework (27), and in that the lifting means (25) includes a pivotable arm (59) which is pivotable in relation to the framework (27) and extending forward in relation to this, a rotatable articulated arm (59A) which is connected at one end to a front end of the rotatable arm (59) and at the other end is connected to the beam (32) in the cutting device (23), and a source (40) for lifting force which is connected between the arm (59) at a position between the two ends thereof and the framework (27) at a position between the two ends thereof. 34. Device according to claim 32 or 33, characterized in that the mobile base unit (26) comprises a front tracked vehicle chassis (26). 35. Device according to claims 18 to 34, characterized in that the lifting means (25) include a hydraulic pressure piston (40). 36. Device according to one of claims 19 to 34, characterized in that the driven joint connection includes a hydraulic pressure piston (84). 37. Device according to one of claims 18 to 36, characterized in that it includes control means (34) arranged to operate the lifting means (25) and the cutting device (23) at the same time. 38. Apparatus according to claim 19 or any one of claims 20 to 37 when they include the features of claim 19, including control means (34) programmed to perform a predetermined cycle of operation, wherein: (i) the mounting means positions the cutting means (23) against the end face (54) of the ditch at the bottom of the ditch; (ii) the drive motor (21) moves the cutting device (23) forward a predetermined distance in the trench during operation of the cutting device (23), to produce the undercut in the end face of the trench, by moving the drive motor (21) forward over the ground surface (22) ; (iii) the driven transverse component (81) pushes the side components (83) outwards against the sides of the trench at a stationary position with the cutting device (23) positioned against the end face (54) of the trench; (iv) the lifting means (25) lift the cutting device (23) upwards from the undercut through the material (56) in the end surface during operation of the cutting device (23) while the driven joint connection (84, 85, 86, 87, 88) exerts the further upward force on the cutting device (23); (v) the driven transverse component (21) disengages and retracts the lateral components from the sides of the trench; (vi) the drive motor (21) moves the cutting device (23) backwards a predetermined distance by moving the drive motor (21) backwards over the ground surface (22); (vii) the lifting means (25) lower the cutting device (23) to the bottom of the trench; and (viii) the previous steps are repeated. 39. Device according to claim 18, 19 or 20, characterized in that the cutting device comprises a cutting rotor which is mounted at the distal end of a boom for rotation around an axis which is aligned across the length of the boom. 40. Device according to claim 18, 19, 20, characterized in that the cutting device comprises a cutting rotor which is mounted at the distal end of a boom for rotation around an axis aligned generally in the direction of the length of the boom.