EP3725951B1 - Slotted wall gripper and method for creating a slot in the ground - Google Patents

Description

The invention relates to a diaphragm wall gripping device for creating a trench in the ground, with a carrier device and a diaphragm wall gripper, which is mounted on the carrier device in a substantially vertically adjustable manner, the diaphragm wall gripper having a gripper frame, at the lower end of which two gripper shovels are arranged, which are activated by means of an actuating device are adjustable between an open position for receiving soil material and a closed position for discharging received soil material from the slot, according to the preamble of claim 1.

The invention also relates to a method for creating a trench in the ground, with a trench wall grab having a grab frame at the lower end of which two grab shovels are arranged which, by means of an actuating device, can be moved between an open position for picking up soil material and a closed position for removing picked soil material are displaceable from the slot, the diaphragm wall grab is introduced essentially vertically into a soil with open grab shovels, the grab shovels are closed to grab and take up soil material and the diaphragm wall grab with the picked up soil material is pulled out of the soil to form the slot, according to the preamble of claim 7.

A generic diaphragm wall grab is from the EP 1 950 353 B1 out. Such devices are used to dig recesses or slots in the ground, which are primarily required to create so-called slotted or sealing walls in the ground. The diaphragm wall grab is usually lowered into the ground with the grab buckets open, penetrating the top of the soil. By closing the grab shovels, soil material is grabbed and picked up in the diaphragm wall grab with the grab shovels then closed. The filled trench wall grab is then pulled out of the trench and moved to a dumping site. A new gripping process is then carried out until the desired final depth of the slot is reached.

Slots for diaphragm or sealing walls can reach depths of up to 50 meters or more. The cross-section of the trench created with the diaphragm wall grab is around one meter wide and between 1.5 and 3 meters long. Due to this slot cross-section and the usual slot depths, there is often no way for a grab operator to visually check whether and to what extent a trench wall grab is filled during a grab operation.

In order to create a slot economically, the aim is to carry out the specified slot depth with as few gripping and emptying processes as possible. Particularly when working in relatively deep trenches, the process of pulling the trench wall grab out of the trench and moving it to a dumping position and then lowering it back into working position is particularly time consuming.

From the EP 3 144 260 B1 a method for moving a diaphragm wall grab up and down is known, in which two cable winches are used to accelerate the lifting process. A controller is provided with which one of the cable winches can be switched to free-fall mode for lowering the cable for a diaphragm wall grab.

the JP H03 241 118 A discloses a trench wall grab according to the preamble of claim 1 and a method according to the preamble of claim 7. The actual degree of filling is determined by a measuring transducer on the boom tip. In the case of insufficient filling or overfilling, appropriate measures are initiated. In the event of underfilling, an automatic grab is initiated, which takes place from a specified drop height of between approx. 0.5 - 1 m. The filling quantity is determined between the individual follow-up strokes. As soon as a certain filling level is reached, the diaphragm wall grab is pulled out of the ground and the grab filling is emptied into a transport vehicle.

The invention is based on the object of specifying a trench wall gripping device and a method for creating a trench in the ground, with which a trench can be created particularly efficiently.

According to the invention, the object is achieved on the one hand by a diaphragm wall gripping device having the features of claim 1 and on the other hand by a method the features of claim 7 solved. Preferred embodiments of the invention are specified in the respective dependent claims.

The diaphragm wall grabbing device according to the invention is characterized in that a determination device is provided which is designed to determine an actual amount of soil material which is picked up by the grab shovels in the closed position, that a control unit is provided which is connected to the determination device and in which stores a target quantity of soil material to be picked up by the slurry wall grab, and that the control unit is designed to compare the recorded actual quantity with the stored target quantity and to emit a signal to repeat a gripping process if the recorded actual quantity of deviates from the stored target quantity.

A basic idea of the invention can be seen in using a control unit to monitor the degree of filling of the gripper scoops in the closed position in order to open the gripper scoops in the slot if they are insufficiently or excessively filled and to repeat the gripping process. In this way, inefficient lifting processes with an insufficiently or excessively filled diaphragm wall grab can be avoided, thereby avoiding time-consuming displacement movements of the insufficiently or excessively filled diaphragm wall grab to an emptying position from the trench.

According to one finding of the invention, it is more economical at a certain degree of filling to empty an insufficiently filled diaphragm wall grab while it is still in the cut trench and to repeat the gripping process to achieve a higher degree of filling.

In the case of cohesive soils, it can happen that the soil in the grab is so compressed when it is closed that it wedges itself in the grab shovels and no longer falls out on its own when it is opened and has to be removed from the grab shovels in a laborious process, especially manually. It is therefore more economical to determine the fill quantity before the grab shovels are completely closed and, if the target quantity is exceeded, to empty the grab shovels again in the cut trench in order to then achieve the desired fill level with a reduced fall height and thus correspondingly reduced penetration depth.

The stored target quantity can represent an individual value, in particular a lower limit value, or a quantity range with a lower and upper limit value. In principle, the control unit can only issue a warning signal to a machine operator, who then decides to open the grab buckets himself.

The actual amount of soil material in the slurry wall grab is automatically determined by the control unit in an automatic mode using a determination device. An actual quantity can be determined with a high degree of reliability by a determination device even in the case of relatively deep slits. This automatic determination and automatic checking of a recorded actual quantity with a predetermined target quantity of soil material to be picked up can ensure that only diaphragm wall grabs with a minimum filling, which can be between 50% and 100% of the maximum grab filling, are pulled out of the slot will.

In principle, it is possible for the specified and stored value of the target quantity to change depending on the slot depth reached, in accordance with software in the control unit, in particular to increase as the slot depth increases. The number of repeated gripping processes can also have an influence on the specified target quantity, with the target quantity being able to decrease with the number of repeated gripping processes before the diaphragm wall grab is emptied again.

In principle, the signal can be used by the control unit to indicate to a machine operator that the grab shovels are to be opened in order to ensure an efficient lifting process. According to a further development of the invention, it is particularly advantageous that the grab shovels can be opened automatically when a signal is output by the control unit. The further process of repeating the gripping process can also be initiated automatically by the control unit in this automatic mode.

A preferred development of the invention is that the diaphragm wall grab is mounted on the carrier device with a cable or a rod and that the determination device has a force measuring element in which a weight force acting on the cable or the rod is used as a measure of the actual quantity taken up Soil material can be detected. By means of a force measuring element can in particular when lifting the diaphragm wall grab after closing the grab shovels and picking up the soil material, a reliable determination can be made of how much filling the diaphragm wall grab has picked up. If this actual amount of soil material taken up is equal to the specified target amount, the trench wall grab is moved out of the trench to the emptying position.

According to a further development of the invention, it is preferred that the determination device has a path measuring element, with which a penetration depth of the trench wall grab into the ground before the grab shovels close can be detected. The penetration depth recorded in this way can be forwarded to the control unit, with the penetration depth being able to influence the control. The penetration depth allows conclusions to be drawn about the (expected) fill level of the grab buckets.

According to the invention, the control unit is designed such that, for repeating a gripping process, the trench wall grab is automatically raised by means of a lifting device to a predeterminable height above a base of the trench and lowered from the predeterminable height with open grab shovels back into the ground. According to the invention, the height of the re-lifting of the diaphragm wall grab is made dependent on the detected actual quantity and/or the penetration depth during the previous grab process by the control unit. With an increasing height and a subsequent lowering of the trench wall grab, preferably in a free-fall mode, a stronger penetration of the open grab shovels into the ground and thus a higher degree of filling can be achieved. Lowering the height decreases the degree of filling.

For efficient operation of the diaphragm wall gripping device, it is preferred according to a further development that the control unit is designed to switch from an automatic mode for carrying out a gripping process to a manual operating mode if the actual quantity recorded in the diaphragm wall gripper corresponds to the stored target quantity. In this embodiment, therefore, only the gripping operation is carried out automatically, while the subsequent operation of extracting the diaphragm wall grab from the ground and emptying it are carried out manually.

Alternatively, according to one embodiment of the invention, the control unit is designed to automatically pull the diaphragm wall grab out of the slot in the ground and move it to an emptying position in an automatic mode for carrying out a grab process after the target quantity has been reached. In the same way, a return into the slot for a further gripping process can also take place in the automatic mode. This results in an efficient automatic operation of the diaphragm wall gripping device.

The method according to the invention is characterized in that a determination device is used to determine an actual quantity of soil material which is picked up by the grab shovels in the closed position, that the determination device is connected to a control unit which compares the detected actual quantity with a predetermined target - Compares the amount of soil material to be picked up by the slurry wall grab, and that the control unit outputs a signal to repeat a grabbing process if the actual amount detected differs from the stored target amount.

The method according to the invention can be carried out in particular with the diaphragm wall gripping device described above. The advantages described above can be achieved in this way.

According to a further development of the method according to the invention, it is preferred that the gripper shovels are automatically opened by the control unit if the detected actual quantity deviates from the stored target quantity. This avoids unnecessary lifting operations. The further process of repeating the gripping can preferably also be carried out in automatic mode.

According to the invention, a preferred variant of the method consists in the control unit for repeating a gripping process lifting the trench wall grab by means of a lifting device up to a predeterminable height above a bottom of the trench and from there lowering it back into the ground with the grab shovels open. The lowering can take place in particular in a free-fall mode of the lifting device. Depending on the degree of filling achieved, the control unit can vary the height up to which the diaphragm wall grab is lifted again.

A further advantageous embodiment of the method according to the invention is that the control unit switches from an automatic mode for carrying out a gripping operation to a manual operation mode when the actual quantity recorded in the diaphragm wall grab corresponds to the stored target quantity. In this case, a semi-automatic system is implemented, with a differentiated emptying of the gripper still being made possible by an operator.

Alternatively, according to a further variant of the invention, it is advantageous for the control unit to automatically pull the diaphragm wall gripper out of the slot in the ground and move it to an emptying position when the target quantity is reached in an automatic mode for carrying out a gripping process. This enables full automatic operation, which supports efficient operation of the diaphragm wall gripping device.

A further preferred variant is that the trench wall grab is introduced into the ground in a free-fall module. At a certain height of the diaphragm wall grab above the base, a holding device, such as the cable winch of a retaining cable, can be released so that the diaphragm wall grab accelerates due to its weight and can penetrate the ground.

According to another variant of the method, in particular in the case of firmer soils, it is advantageous for the diaphragm wall grab to be introduced into the soil with a predetermined force. For this purpose, the diaphragm wall gripping device is provided with a linear element, in particular a hydraulic cylinder, with which the diaphragm wall gripper can be moved downwards with a predetermined force.

According to a further embodiment of the method according to the invention, it is preferred that the slot is filled with a suspension during construction or subsequently, and that the suspension hardens in the slot and a slot wall segment is thus produced. By carrying out the method according to the invention multiple times, a large number of diaphragm wall segments can be formed, which together form a diaphragm wall in the ground. The slit wall can have a sealing and/or support function.

The invention is explained below using a preferred exemplary embodiment, which is shown schematically in the single drawing figure. The drawing shows a side view of a trench wall gripping device 10 according to the invention in a partially created trench 7 in the ground 5.

The trench wall grab device 10 has a trench wall grab 12 with a scaffold-like grab frame 14 . At a lower end of the gripper frame 14 two gripper scoops 16 are mounted by means of swivel joints 17 . The two gripper scoops 16 are in an open position in the illustration shown, with teeth 18 arranged on the gripper scoops 16 pointing downwards. In this open position, the trench wall grab 12 is lowered into the ground 5, with the teeth 18 penetrating into the ground 5.

An actuating device 20 with a hydraulic cylinder 22 which extends in a longitudinal direction of the gripper frame 14 is arranged on the gripper frame 14 . In the position shown, a piston rod 24 is retracted into the hydraulic cylinder 22 .

A carriage element 26 is mounted in a linearly displaceable manner along a longitudinally directed guide 15 on the gripper frame 14 . An eye of the piston rod 24 and, on the other hand, upper ends of two levers 28 are articulated on the carriage element 20 . The lower ends of the levers 28 are connected in an articulated manner to a grab bucket 16 in each case.

By extending the piston rod 24 downwards out of the hydraulic cylinder 22 , the slide element 26 is moved downwards along the linear guide 15 . In doing so, the levers 28 exert a compressive force downwards on the gripper scoops 16 . These are thereby moved about their respective pivot joints 17 on the gripper frame 14 from the open position shown into a closed position in which the two gripper scoops 16 rest against one another. During this closing movement, the gripper scoops 16 penetrate the soil 5 with their teeth 18 and thus pick up soil material between the gripper scoops 16 .

After closing, the diaphragm wall grab 12 is pulled up by a carrier device (not shown) by means of a rope 32 . The rope 32 stands with the Trench wall grab 12 via a suspension device 30 which is attached to an upper end of the grab frame 14. A determination device 40 can be arranged in the area of the suspension device 30, which is designed, for example, as a force-measuring element, in particular a so-called load cell. In this way, a suspension load, which is caused by the trench wall grab 12, can be determined. A weight of the soil material picked up by the grab buckets 16 can be determined as a value for the actual quantity by simply comparing the suspension load before and after closing.

The measured value determined is preferably forwarded wirelessly by the determination device 40 to a control unit, which is preferably located on the carrier device (not shown).

According to the invention, the value of the detected actual quantity is compared in the control unit with a stored value of a target quantity, which represents a measure of the minimum amount of soil material to be picked up by the diaphragm wall grab. If the actual amount taken is less than the intended target amount, the trench wall grab 12 is not pulled up out of the slot 7 and the grab shovels 16 are opened again from the closed position to the open position shown in the figure. The grab shovels 16 are still emptying in the slot 7.

From a predetermined height of the trench wall grab 12 in the trench 7 , the trench wall grab 12 can be moved downwards again, preferably in a free-fall mode, for further penetration of the grab shovels 16 with the teeth 18 into the soil 5 . The grab shovels 16 are then closed again and, as previously described, the trench wall grab 12 is raised further with a determination of the actual amount of soil material picked up and a comparison with the target amount. If the actual quantity is still less than the target quantity, the process is repeated, optionally with a different, in particular larger, specified gripper height. As soon as the specified target quantity is exceeded, the trench wall grab 12 is pulled completely out of the trench 7 and moved to an emptying position. The trench wall grab 12 can then be moved back into the slot 7 for another grab operation.

Claims (13)

1. Trench wall grab apparatus for producing a trench (7) in the ground (5), having:

   - a support device and

   - a trench wall grab (12) which is mounted on the support device so as to be substantially vertically adjustable, wherein the trench wall grab (12) has a grab frame (14) at the lower end of which there are arranged two grab buckets (16) which are adjustable by means of an actuating device (20) between an open position for receiving ground material and a closed position for conveying away received ground material out of the trench (7),

   - wherein there is provided a determination device (40) which is configured to determine an actual quantity of ground material which has been received by the grab buckets (16) in the closed position,

   - wherein there is provided a control unit which communicates with the determination device (40) and in which a target quantity of ground material to be received by the trench wall grab (12) is stored, and

   - wherein the control unit is configured to compare the detected actual quantity with the stored target quantity and to output a signal for repetition of a grab operation if the detected actual quantity differs from the stored target quantity,

   characterised in that

   for the repetition of a grab operation, the control unit is configured automatically to lift the trench wall grab (12) to a specifiable height above a bottom of the trench (7) by means of a lifting device and to lower it into the ground (5) again from the specifiable height with the grab buckets (16) open, and

   in that the control unit makes the specifiable height to which the trench wall grab (12) is lifted again dependent upon the detected actual quantity and/or upon the penetration depth in the preceding grab operation.
2. Trench wall grab apparatus according to claim 1,
   characterised in that
   the grab buckets (16) can be opened automatically when a signal is outputted by the control unit.
3. Trench wall grab apparatus according to claim 1 or 2,
   characterised in that

   the trench wall grab (12) is mounted on the support device by a cable (32) or a rod, and

   in that the determination device (40) has a force-measuring element with which a weight force acting on the cable (32) or on the rod can be detected as a measure of the actual quantity of ground material received.
4. Trench wall grab apparatus according to any one of claims 1 to 3,
   characterised in that
   the determination device (40) has a displacement-measuring element with which can be detected a penetration depth of the trench wall grab (12) into the ground (5) before the grab buckets are closed.
5. Trench wall grab apparatus according to any one of claims 1 to 4,
   characterised in that
   the control unit is configured to switch from an automatic mode for carrying out a grab operation into a manual operating mode when the detected actual quantity in the trench wall grab (12) corresponds to the stored target quantity.
6. Trench wall grab apparatus according to any one of claims 1 to 4,
   characterised in that
   in an automatic mode for carrying out a grab operation, the control unit is configured automatically to withdraw the trench wall grab (12) from the trench (7) in the ground (5) and move it to an emptying position when the target quantity has been reached.
7. Method for producing a trench (7) in the ground (5), in particular using a trench wall grab apparatus (10) according to any one of claims 1 to 6,
   wherein

   - a trench wall grab (12) which has a grab frame (14) at the lower end of which there are arranged two grab buckets (16) which are adjustable by means of an actuating device (20) between an open position for receiving ground material and a closed position for conveying away received ground material out of the trench (7),

   - the trench wall grab (12) is introduced substantially vertically into a ground (5) with its grab buckets (16) open,

   - the grab buckets (16) are closed in order to grab and hold ground material, and

   - the trench wall grab (12) with the received ground material is withdrawn from the ground (5) in order to form the trench (7),

   - wherein an actual quantity of ground material which has been received by the grab buckets (16) in the closed position is determined by means of a determination device (40),

   - wherein the determination device (40) communicates with a control unit which compares the detected actual quantity with a specified target quantity of ground material to be received by the trench wall grab (12), and

   - wherein a signal for repetition of a grab operation is outputted by the control unit if the detected actual quantity differs from the stored target quantity,

   characterised in that

   by means of the control unit, for the repetition of a grab operation, the trench wall grab (12) is lifted to a specified height above a bottom of the trench (7) by means of a lifting device and, from there, is lowered into the ground (5) again with the grab buckets (16) open, and

   in that the control unit makes the specifiable height to which the trench wall grab (12) is lifted again dependent upon the detected actual quantity and/or upon the penetration depth in the preceding grab operation.
8. Method according to claim 7,
   characterised in that
   the grab buckets (16) are opened automatically by the control unit if the detected actual quantity differs from the stored target quantity.
9. Method according to either claim 7 or claim 8,
   characterised in that
   the control unit switches from an automatic mode for carrying out a grab operation into a manual operating mode when the detected actual quantity in the trench wall grab (12) corresponds to the stored target quantity.
10. Method according to either claim 7 or claim 8,
    characterised in that
    by means of the control unit, in an automatic mode for carrying out a grab operation, the trench wall grab (10) is automatically withdrawn from the trench (7) in the ground (5) and moved to an emptying position when the target quantity has been reached.
11. Method according to any one of claims 7 to 10,
    characterised in that
    the trench wall grab (12) is introduced into the ground (5) in a free-fall mode.
12. Method according to any one of claims 7 to 11,
    characterised in that
    the trench wall grab (12) is introduced into the ground (5) with a specified force.
13. Method according to any one of claims 7 to 12,
    characterised in that

    the trench (7) is filled with a suspension while it is being produced or thereafter, and

    in that the suspension hardens in the trench (7) and a trench wall segment is produced.

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