GRIPPER DEVICE AND METHOD FOR OPERATING A GRIPPER DEVICE

Description

[0001] The invention relates to a method for operating a gripper device with a carrier device and a rope gripper arranged thereon, which has a gripper frame which is held on the carrier device via a holding rope, at least two gripper blades which are pivotally mounted at a lower end of the gripper frame between a closed position and an open position, and an actuating device with an actuating rope for pivoting the gripper blades, wherein an actuating rope is guided from the carrier device to the actuating device and the carrier device has a driven first rope winch for the holding rope and a driven second rope winch for the actuating rope, wherein the carrier device has an undercarriage and an upper carriage mounted thereon rotatably about a vertical axis with a boom arm on which the rope gripper is mounted vertically adjustable,wherein, to form a slot in the ground in a removal step, the rope grab with open grab buckets is lowered into the ground by means of the holding rope, to remove and pick up soil material, the grab buckets are closed, the rope grab is pulled out of the ground by means of the holding rope and / or the actuating rope and is pivoted by rotating the superstructure to an emptying position, at which the grab buckets are opened to discharge the picked up soil material, and then the rope grab is moved back into the ground slot to repeat the removal step, according to the preamble of claim 1.

[0002] The invention further relates to a gripper device with a carrier device and a rope gripper arranged thereon, which has a gripper frame which is held on the carrier device via a holding rope, at least two gripper blades which are pivotally mounted at a lower end of the gripper frame between a closed position and an open position, and an actuating device with an actuating rope for pivoting the gripper blades, wherein an actuating rope is guided from the carrier device to the actuating device and the carrier device has a driven first rope winch for the holding rope and a driven second rope winch for the actuating rope, wherein the carrier device has an undercarriage and an upper carriage mounted thereon so as to be rotatable about a vertical axis and having a boom arm on which the rope gripper is suspended in a vertically adjustable manner, according to the preamble of claim 8.

[0003] Grab devices are used in specialized foundation engineering to create trenches in the ground. Diaphragm walls can be constructed in these trenches to support and / or seal excavations.

[0004] Grabber devices primarily comprise a grab with grab buckets, whereby the grab is suspended from a carrier device, typically a jib crane, via a holding cable. Using the holding cable, a grab can be lowered into the ground. By closing the grab buckets, soil material can be removed and collected in the grab. The grab is then retracted from the ground via the holding cable and / or actuation cable and pivoted with the carrier device to an emptying position, where the grab buckets are opened to discharge the soil material. The grab is then pivoted back into the working position and inserted into the slot in the ground for another grab operation.

[0005] There are two different types of grippers used on such gripper devices: hydraulic grippers and rope grippers. A so-called hydraulic gripper is known, for example, from EP 3 798 367 A1. In a hydraulic gripper, the movement for opening and closing the gripper blades is generated by a hydraulic cylinder mounted on the gripper frame.

[0006] Such hydraulic grabs, such as those known from EP 0 533 558, are relatively easy to operate and control thanks to their hydraulic system. However, the supply and discharge of hydraulic fluid requires appropriate hydraulic lines, which run parallel to the support cable. Appropriate cable reels for the hydraulic lines with appropriate winch drives, as well as a suitably designed hydraulic system, must be provided on the carrier device. This makes the grab device larger and more expensive. The hydraulic system also requires additional maintenance.

[0007] In contrast, so-called rope grabs offer a significantly simplified design. One such rope grab is known, for example, from GB 2 126 981 A. In a rope grab, the opening and closing movement of the grab buckets is controlled by an actuating cable. The actuating cable runs essentially parallel to the retaining cable from the actuating device of the grab buckets to the carrier device. Using a separate winch for the actuating cable, the grab buckets can be opened or closed by unwinding or winding the actuating cable onto the winches.

[0008] With a rope grab, the complex supply of hydraulic lines to the grab is eliminated. All that's required is an additional operating cable with a corresponding winch. Such an operating cable is also considerably less maintenance-intensive than hydraulic lines with a corresponding hydraulic system.

[0009] However, operating a rope grab is not as easy as operating a hydraulic grab, requiring an experienced operator. One reason for this is that the dual arrangement of a non-rotation-resistant rope—namely, the holding rope and the actuating rope—generates torques in various operating states, causing a certain degree of twisting of the rope grab around its longitudinal axis.

[0010] However, an exact rotational position of the rope grab is essential in order to be able to move the rope grab safely between the emptying position and a working position in which the rope grab is retracted into the ground to create a slot.

[0011] A machine operator can rotate the rope grab around its longitudinal axis by applying specific tensile forces to the holding rope and the actuating rope. This requires relatively sensitive operation of the corresponding rope winches. This requires a certain level of experience from the machine operator and also a high level of concentration during the process. Furthermore, rope winches are often operated using foot pedals, making sensitive operation of the rope winches for several hours very strenuous for a machine operator.

[0012] A gripper device according to the preamble of claim 1 and claim 8 is also known from JP 2001 064993.

[0013] The invention is based on the TaskThe aim is to provide a method for operating the gripper device and a gripper device which furthermore has a simple structure for the gripper device and at the same time enables simple operation.

[0014] The object is achieved, on the one hand, by a method having the features of claim 1 and, on the other hand, by a gripper device having the features of claim 8. Preferred embodiments of the invention are specified in the respective dependent claims.

[0015] The method according to the invention is characterized in that a control device is provided with which the rotation of the superstructure to the emptying position and the opening of the grapple buckets for discharging the soil material and / or the rotation of the superstructure from the emptying position back to the soil slot are automatically controlled. In this case, the grapple device can be rotated about its vertical axis.

[0016] A basic idea of ​​the invention is to provide a control device by which, on the one hand, a rotary drive for the superstructure and, on the other hand, at least one cable winch for the actuating cable are controlled in a coordinated manner. This enables fast and efficient movement of the cable grab and emptying at the emptying position to be achieved. Complex manual control by a machine operator and the coordination of controlling the rotation of the superstructure and / or the grab device with the actuation of the cable winch for the actuating cable and the cable winch for the holding cable using the conventionally provided foot pedals can be eliminated. This represents a considerable relief for a machine operator both in terms of physical and coordination requirements, especially since a simply constructed cable grab is easily prone to oscillation, i.e., swinging and / or twisting.The invention allows safe and efficient operation of a rope grab even by a less experienced machine operator.

[0017] Alternatively or additionally, the invention allows the upper carriage to be rotated from the emptying position back to the floor slot. Thus, the control device can perform the repetitive movement of the rope grab from the working position at the floor slot to the emptying position and back completely, almost completely, or at least partially automatically. A first operation can be performed manually by a machine operator, while a corresponding automatic program is created by the control device using a teach-in process. Once the automatic program has been saved, it can be executed repeatedly automatically, thus significantly reducing the workload for the machine operator.

[0018] According to one variant of the invention, particularly efficient emptying is achieved in that the control device opens the grab buckets while the rope grab is still in a pendulum motion due to the rotation of the upper carriage. In this way, a dynamic emptying process can be achieved in which there is no need for the rope grab to swing out above the emptying point. This means a considerable acceleration of the work process. The pendulum motion of the rope grab can be caused not only by the rotation of the upper carriage, but also by the operation of the cable winches. The pendulum motion can comprise not only swinging in an approximately horizontal direction but also rotating or torsional swinging in an approximately vertical direction.The control system can be used to control both the cable winch for the operating cable and the cable winch for the holding cable in such a way that any pendulum movement of the cable-suspended rope grab is counteracted. This promotes occupational safety.

[0019] According to a further development of the invention, it is advantageous that the control device automatically controls the movement of the rope grab into the ground slot and / or the retraction of the rope grab from the ground slot. In principle, the insertion and extension of the diaphragm wall grab can also be carried out automatically. The increasing depth of the slot can also be taken into account. The machine operator preferably has the option of carrying out these process steps or other process steps at any time by directly intervening in the control device. In particular, when inserting the diaphragm wall grab into a slot in the ground, this can be done under the direct control of the machine operator.The control device can carry out a program step beforehand which results in a stabilization of the movement of the rope gripper around a vertical axis (twisting) as well as transversely to the vertical axis (swinging) immediately before it enters the created slot.

[0020] Furthermore, it is preferred that the control device is connected to and controls the first cable winch and the second cable winch. This allows for coordinated actuation of the holding and actuating cables to limit or completely prevent unwanted rotational and pendulum movements of the cable gripper.

[0021] A particularly expedient operation of the gripper device is achieved according to a further development of the invention by providing a sensor device with which a pendulum movement of the rope gripper is detected when the uppercarriage is rotated. The sensor device can be camera-based or comprise other contact-based or contactless sensors with which a pendulum movement transverse to the vertical and / or a twisting pendulum movement about a vertical axis is detected. The movement data thus detected can be used by the control device, in particular, to control one or both rope winches in order to counteract the undesired or excessive pendulum movement.

[0022] For efficient grapple operation, according to a further embodiment of the invention, it is advantageous for the control device to open the grapple blades at the emptying position at a time when the oscillating rope grab is still in a vertically deflected position. This leads to an overall acceleration of the entire process. Furthermore, the targeted emptying of the rope grab in a deflected position can counteract the pendulum movement, since the resulting reduction in the pendulum mass has a calming effect on the pendulum movement.

[0023] A further efficient process sequence can be achieved by retracting the oscillating rope grab into the ground slot via the control device, whereby the oscillating movement is stabilized by contact with the ground. Once a certain reduction in the oscillating movement has been achieved, the oscillating movement can be completely stabilized by deliberately retracting the rope grab into the ground slot.

[0024] With regard to the grapple device according to the invention, the invention is characterized in that a control device is provided which is designed to automatically control the rotation of the upper carriage to an emptying position and the opening of the grapple buckets for discharging soil material and / or the rotation of the upper carriage from the emptying position back to the soil slot. The advantages described above can be achieved in this way.

[0025] It is particularly preferred in the gripper device according to the invention that it is designed to carry out the method according to the invention described above.

[0026] Furthermore, in one embodiment of the gripper device according to the invention, it is preferred that a first detection device for detecting a first cable force on the holding cable and a second detection device for detecting a second cable force on the actuating cable are provided, and that the control device is connected to the first detection device, the second detection device of the first cable winch and the second cable winch and is designed to control the first cable winch and / or the second cable winch in accordance with a control program specification depending on the detected first cable force on the holding cable and the detected second cable force on the actuating cable.

[0027] One aspect of the invention is based on the realization that a torque on a rope gripper about its longitudinal axis depends on the rope forces in the holding rope and the actuating rope. Detection devices are provided with which a rope force on the holding rope and a rope force on the actuating rope are detected. The respectively detected force values ​​can be fed to a control device which controls a first rope winch for the holding rope and a second rope winch for the actuating rope in accordance with inputs and specifications from the machine operator. The control device can thus coordinate the forces in the holding rope and in the actuating rope by appropriately controlling the respective rope winch (winding up / unwinding) so that, for a given or desired rotational position of the rope gripper, in particular no torque about the longitudinal axis is generated by the holding rope and the actuating rope.The control device can also be used to generate a defined, variable torque for a desired twist by appropriately influencing the respective cable forces. This can counteract a pendulum motion.

[0028] A preferred embodiment of the invention is that a defined ratio between the first cable force in the holding cable and the second cable force in the actuating cable is specified and adjustable by the control program specification of the control device. The control program specification can accordingly take into account identical or different designs of the holding cable and actuating cable. With a preferably identical design of the holding cable and actuating cable, but with opposite cable lay, torque compensation can be achieved by setting largely equal tensile forces in the cables. With a different design of the cables due to a different cable structure, this can be taken into account and preset accordingly in the control program specification.When specifying the control program, additional geometric conditions on the rope gripper can also be preset and taken into account, for example with regard to different attachment points of the ropes on the gripper frame.

[0029] A further preferred embodiment of the invention consists in that the control device is designed with a compensation mode in which the cable winches are controlled such that the first cable force on the holding cable and the second cable force on the actuating cable are equalized. In particular, the cable winches can be controlled such that the torques in the actuating cable and the holding cable compensate or weaken each other. This can stabilize the rotational position of the cable gripper about its longitudinal axis. Undesired rotation of the cable gripper about its longitudinal axis during operation can thus be largely avoided.

[0030] In particular, according to a further development of the invention, it is advantageous for the control device to be designed with a rotation mode in which the cable winches are controlled in such a way that a targeted rotation of the cable gripper about a vertical longitudinal axis can be generated. Starting from a stable rotational position, a machine operator can effect a desired change in the rotational position. The control device can also be designed such that a value or a measure for a desired rotation is specified by the machine operator via an input device, whereby the control device actuates the winches according to the program logic so that the desired changed rotational position is established.

[0031] A further preferred embodiment of the invention consists in the control device being designed with a mode for opening and / or closing the grab buckets at a predetermined height. This means that during opening and / or closing, the two cable winches can be coordinated so that the lowest point of the grab buckets preferably remains at the same height or a specific height change is achieved. For example, during closing, it is possible to control whether the teeth or tooth tips of the grab buckets move in a circular path, a straight path, or a defined path curve in between. This can be adjusted, particularly depending on the soil type.

[0032] Preferably, the grab can be held freely suspended with closed grab buckets on the operating rope and holding rope, whereby the rope force in the operating rope and holding rope is approximately the same, for example corresponding to approx. + / - 1 t. Triggered by a control command from the machine operator, the winch on which the operating rope is wound is automatically actuated in the unwinding direction, which occurs either in free fall or with a force fit. At the same time, the winch on which the holding rope is wound is automatically actuated in the winding direction. This causes a carriage in the grab body to move upwards and open the grab buckets via the push rods. By controlling the ratio of unwinding of the operating rope and winding of the holding rope, it can be achieved that vertical movement of the grab body against the subgrade or the ground during opening is avoided or minimized.Without this control, the gripper body would otherwise move significantly downwards when the gripper blades were opened.

[0033] Accordingly, the control device can be designed with a mode for closing the grab buckets. This means that during opening and / or closing, the two cable winches can be coordinated so that the lowest point of the grab buckets preferably remains at the same height. Accordingly, during closing, it can be controlled whether the teeth or tooth tips of the grab buckets move in a circular path, a straight path, or a path in between, which can be adjusted, particularly depending on the soil type.

[0034] Preferably, the grapple can be suspended freely with the grapple bucket open by the operating cable and holding cable. The cable force in the holding cable corresponds almost to the entire grapple weight, and the cable force in the operating cable is in the range of approximately 1 t to 2 t. Triggered by a control command from the operator, the winch on which the operating cable is wound is automatically actuated in the winding direction, and simultaneously, the winch on which the holding cable is wound is automatically actuated in the unwinding direction, either in free fall or by force. This causes the carriage in the grapple body to move downwards and close the grapple bucket via the push rods.

[0035] By controlling the winding of the closing rope and the unwinding of the holding rope, the vertical movement of the grab body against the subgrade or ground during closing can be prevented or minimized. Without this control, the grab body would otherwise move significantly upward when the grab buckets close.

[0036] A further preferred embodiment of the invention further consists in that the control device is designed with a mode for automatically opening and immediately closing the gripper blades.

[0037] Preferably, the grab can be held freely suspended with the closed, filled grab bucket on the actuating rope and holding rope, wherein the rope force in the actuating rope and holding rope is approximately the same, in particular corresponding to approximately + / - 1 t.

[0038] By operating a control element, the operator automatically opens and closes the grab buckets in one sequence. The goal is to complete this process in the shortest possible time, since the rope force in the holding rope is significantly higher than in the actuating rope when the grab bucket is open. This can lead to the grab twisting around its longitudinal axis. To counteract this twisting, a rotational impulse in the opposite direction can be applied before the automatic opening / closing process is executed, particularly by automatically and briefly increasing the rope force in the actuating rope.

[0039] A further preferred embodiment of the invention is that the control device can detect the degree of opening of the grab buckets and this is visualized to the operator.

[0040] By recording the ratio of the depth or unwinding length of the holding cable and the operating cable, it is possible to determine the degree of opening of the grab bucket via the device control system and, in particular, to visualize it on a screen for the operator. This can be done by displaying a numerical value, such as 50% opening, and / or a graphical representation, such as the grab buckets with an opening angle or as a bar chart. Without this display, the degree of opening of the buckets and thus the condition of the grab in the slot are not visually apparent to the operator.

[0041] According to a further development of the invention, it is preferred that at least one third detection device is provided for detecting a rotational position of the cable gripper and / or a change in the rotational position. This can be achieved by an optical detection device, a rotary encoder, a gyroscope on the cable gripper, or in another suitable manner. Thus, feedback regarding the rotational position or rotation of the gripper can be provided when controlled by the control device, so that the rotational position or rotation can be regulated. This enables particularly precise adjustment of the rotational position of the cable gripper.

[0042] A further improvement in operability is achieved according to a further embodiment of the invention in that at least one additional detection device is provided, in particular for detecting a vertical position of the cable gripper, a distance, and / or an angular position of the cable gripper relative to the carrier device. The additional parameters thus detected can be directly displayed to a machine operator and / or processed by the control device for controlling the gripper.

[0043] A further advantageous embodiment of the invention consists in the provision of a control panel for manual control for actuating the rope gripper and / or the rope winches. The control panel as an input device is designed in particular such that a machine operator can enter a desired rotation or movement of the rope gripper, for example as a numerical value or angular measurement, preferably using corresponding operating elements such as a cursor, a rotary wheel, switches or keys, in particular in combination with a display. The machine operator therefore no longer has to directly enter the winches and a rotation of the winches. Instead, in accordance with the operator input regarding the position of the gripper, the machine with the individual motors and actuators is controlled via the control device with the program logic in such a way that the desired position is achieved largely without undesired rotations.

[0044] According to one embodiment of the invention, it is particularly preferred that the control device is designed with an automatic program by which the cable grab can be automatically moved to an emptying position and / or to an excavation site. An automatic program can be permanently stored or, for repetitive processes, can be individually defined and saved by a machine operator. In this way, larger movement sequences of the grab can be carried out automatically, in particular a movement to the emptying position and / or back to an excavation site. Such travel paths of the cable grab occur with a high repetition frequency, particularly when creating deep slots in the ground.

[0045] In principle, the individual cables can be designed identically or differently. According to one embodiment of the invention, it is particularly advantageous that the holding cable on the first cable winch has a first winding that is opposite to a second winding of the actuating cable on the second cable winch. In particular, the holding cable and the actuating cable have an opposite lay direction, or what is known as a cable lay. When a tensile force is applied, opposing torques are thus produced on the cables. This facilitates compensation of the torques to stabilize the position of the cable gripper during operation.

[0046] According to a further embodiment of the invention, it is particularly advantageous that a display screen is provided for the control device for operation. The display screen can be designed, in particular, as a touchscreen on which at least some of the operating elements for a machine operator are implemented. Furthermore, the position of the rope gripper can be displayed in various representations on the display screen to further facilitate operation for a machine operator.

[0047] The grab device can be used for a variety of tasks. A preferred method variant involves removing soil using the rope grab, particularly to create a trench in the ground. The rope grab can be designed, in particular, as a so-called diaphragm wall grab, with which a trench can be created for a sealing and / or retaining wall in the ground, for example, for an excavation enclosure.

[0048] The invention will be further described below with reference to a preferred embodiment, which is schematically illustrated in the drawings. In the drawings: Fig. 1 is a perspective view of a gripper device according to the invention; Fig. 2 is a front view of the rope gripper of the gripper device of Fig. 1 with closed grab buckets; and Fig.3 a front view of the rope grab according Fig. 2 with open grab buckets.

[0049] A gripper device 10 according to the invention according to Fig. 1 has a mobile carrier 12 with a crawler track as the undercarriage 14. A superstructure 16 with an operator's cabin 17 is mounted on the undercarriage 14, rotatable about a vertical axis of rotation. Within the operator's cabin 17 is a control device including an input device for a machine operator.

[0050] A boom arm 18 is pivotally mounted on the superstructure 16 about a horizontal axis. A holding cable 24 is guided on a head 20 of the boom arm 18 with deflection pulleys, to the end of which a rope grab 30 with a grab frame 32 and lower grab buckets 34 is attached. The holding cable 24 can be actuated to raise and lower the rope grab 30 via a first cable winch 21 on the carrier device 12. Furthermore, a second cable winch 22 for an actuating cable 44 is located on the carrier device 12, which is also guided via the head 20 to the rope grab 30 for actuating the grab buckets 34 at the lower end of the grab frame 32.

[0051] The operation of the gripper device 10 according to the invention is explained below in connection with the Figures 2 and 3 explained in more detail.

[0052] In a central region of the gripper frame 32, an actuating carriage 42 of an actuating device 40 for actuating the gripper blades 34 is mounted so as to be displaceable in a vertical longitudinal direction. The end of the holding cable 24 is attached to the upper end of the actuating carriage 42, so that the cable gripper 30 is held by the actuating carriage 42.

[0053] At a lower end of the actuating carriage 42, a linkage mechanism 46 with linkage rods 47 is arranged. The linkage rods 47 are connected in an articulated manner to the actuating carriage 42 on the one hand and to one of the gripper blades 34 on the other. The gripper blades 34 are themselves pivotally mounted on the lower end of the gripper frame 32 via pivot bearings 35. By a relative displacement of the actuating carriage 42 with respect to the gripper frame 32, the gripper blades 34 can be opened and closed. By a relative displacement of the actuating carriage 42 upwards, the linkage rods 47 are pulled upwards, whereby the gripper blades 34 are pivoted about their pivot axes 35 into their opening position, which is clearly shown in Fig. 3 is shown.

[0054] Below the actuating carriage 42, a pulley assembly 50 is provided for the actuating cable 44. The pulley assembly 50 has at least one upper roller 52, which is rotatably mounted on the actuating carriage 42, and at least one lower roller 54, which is rotatably mounted on a lower region of the gripper frame 32. The actuating cable 44, supplied from above, wraps around the rollers 52, 54, forming loops 56 or pulleys, with the lower end of the actuating cable 44 being firmly connected to the gripper frame 32. The actuating carriage 42 is thus adjustably connected or coupled to the gripper frame 32 via the actuating cable 44.

[0055] Starting from the opening position according to Fig. 3By pulling the actuating cable 44 upwards by the second cable winch 22, the actuating carriage 42 is pulled downwards by the pulley arrangement 50 relative to the gripper frame 32. The linkage rods 47 press the gripper blades 34 downwards with an increased closing force, whereby the gripper blades 34 are pivoted about their pivot bearings 35 into the closed position according to Fig. 2 be swiveled.

[0056] When used in a slot in the ground, soil material can be gripped and enclosed between the grab buckets 34 with a closing force that is higher than the tensile force on the actuating cable 44.

[0057] After pulling the rope grab 30 out of a slot in the ground and moving it to an emptying position, the pulling force on the actuating rope 44 can be reduced. In this way, the grab frame 32 moves downwards relative to the actuating carriage 42 due to its weight, so that the grab blades 34 are pivoted back into their opening position via the linkage rods 47, as shown in Fig. 3 is shown.

[0058] This described arrangement is only an example. In principle, other pulley arrangements with different rope linkages and a different linkage mechanism can be selected, enabling comparable grapple bucket operation.

[0059] When the grab buckets 34 are filled, the upper carriage 16 is moved from the Fig. 1The boom arm 18 can also be adjusted in this case. At the emptying position, the grab buckets 34 are opened to discharge the soil material, even if the rope grab 30 is still performing a pendulum movement. The rope grab 30 can also be rotated about its longitudinal axis in order to align it, for example, with the body of a truck. The upper carriage 16 can then automatically return to the position shown in Fig. 1 be swung back.

[0060] From there, the rope grab 30 is lowered into a slot in the ground to pick up new soil material with the grab buckets 34 open. It is then retracted with the grab buckets 34 closed to the position according to Fig. 1 and another emptying process.

[0061] When operating the rope gripper 30, it is necessary to coordinate the forces and movements between the holding rope 24 and the actuating rope 44 in order to control the torques in the individual ropes and thus the torques of the attached rope gripper 30 about its longitudinal axis, particularly due to a so-called lay direction in wound ropes.

[0062] According to the invention, forces in the holding cable 24 and the actuating cable 44 are detected via corresponding detection devices, which can be arranged, for example, on the cable winches 21, 22 or on the deflection pulleys on the head 20 of the boom arm 18. A control device, which is preferably arranged in the operator's cabin 17 on the carrier device 12, can control the winches 21, 22 depending on the detected cable forces in such a way that either a stabilization of the pendulum movement relative to the longitudinal axis or the rotational position of the cable gripper 30 about its longitudinal axis or a targeted rotation desired by the machine operator is achieved. The machine operator can make corresponding inputs to the control device for a desired automatic movement, a compensation mode for position stabilization, or inputs regarding a desired rotational position of the vertical gripper 30.Based on this, the control system of the superstructure 16 can control the boom arm 18 or the cable winches 21, 22 accordingly to effect the desired positioning and opening / closing of the cable grab 30. This significantly simplifies and facilitates the control of a simply constructed cable grab 30 for a machine operator.

Claims

1. A method for operating a grab device (10) comprising a carrier device (12) and a cable grab (30) arranged thereon, which comprises - a grab frame (32), which is held by a retaining cable (24) on the carrier device (12), - at least two grab buckets (34), which are mounted on a lower end of the grab frame (32), so as to be able to swivel between a closed position and an open position, and - an actuating device (40) with an actuating cable (44) for swivelling the grab buckets (34), - wherein an actuating cable (44) is guided from the carrier device (12) to the actuating device (40), and - the carrier device (12) has a driven first cable winch (21) for the retaining cable (24) and a driven second cable winch (22) for the actuating cable (44), - wherein the carrier device (12) has an undercarriage (14) and an upper carriage (16), which is mounted thereon for rotation about a vertical axis and has a cantilever arm (18) on which the cable grab (30) is vertically adjustably mounted, wherein - in a removal step, in order to form a trench in the ground, the cable grab (30) is lowered into the ground by the retaining cable (24) with the grab buckets (34) open, - the grab buckets (34) are closed to remove and collect soil material, - the cable grab (30) is pulled out of the ground by the retaining cable (24) and / or the actuating cable (44) and is swiveled into an emptying position, in which the grab buckets (34) are opened to discharge the collected soil material, by rotating the upper carriage (16), and - then the cable grab (30) is moved back into the ground trench to repeat the removal step, characterized in that a control device is provided with which a rotation of the upper carriage (16) to the emptying position and an opening and closing of the grab buckets (34) to discharge the soil material and / or a rotation of the upper carriage (16) from the emptying position back to the ground trench are controlled automatically.

2. The method according to claim 1, characterized in that the control device opens the grab buckets (34) while the cable grab (30) is still in an oscillating movement, as a consequence of the rotation of the upper carriage (16).

3. The method according to claim 1 or 2, characterized in that an introduction of the cable grab (30) into the ground trench and / or a retraction of the cable grab (30) out of the ground trench is controlled automatically by the control device.

4. The method according to one of claims 1 to 3, characterized in that the control device is connected to and controls the first cable winch (21) and the second cable winch (22).

5. The method according to one of claims 2 to 4, characterized in that a sensor device is provided with which an oscillating movement of the cable grab (30) during rotation of the upper carriage (16) is detected.

6. The method according to one of claims 2 to 5, characterized in that the grab buckets (34) are opened by the control device at the position at a time when the oscillating cable grab (30) is still in a position deflected out of the vertical position.

7. The method according to one of claims 2 to 6, characterized in that the oscillating cable grab (30) is introduced by the control device into the ground trench, wherein the oscillating movement is damped by contact with the ground.

8. A grab device comprising a carrier device (12) and a cable grab (30) arranged thereon, which comprises - a grab frame (32), which is held by a retaining cable (24) on the carrier device (12), - at least two grab buckets (34), which are mounted on a lower end of the grab frame (32), so as to be able to swivel between a closed position and an open position, and - an actuating device (40) with an actuating cable (44) for swivelling the grab buckets (34), - wherein an actuating cable (44) is guided from the carrier device (12) to the actuating device (40), and - the carrier device (12) has a driven first cable winch (21) for the retaining cable (24) and a driven second cable winch (22) for the actuating cable (44), - wherein the carrier device (12) has an undercarriage (14) and an upper carriage (16), which is mounted on the undercarriage for rotation about a vertical axis and has a cantilever arm (18) from which the cable grab (30) is vertically adjustably suspended, characterized in that a control device is provided, which is designed to automatically control a rotation of the upper carriage (16) to an emptying position and an opening and closing of the grab buckets (34) to discharge soil material and / or a rotation of the upper carriage (16) from the emptying position back to the ground trench, wherein an opening and closing of the grab buckets (34) preferably takes place automatically.

9. The grab device according to claim 8, characterized in that it is designed to carry out the method according to one of claims 1 to 7.

10. The grab device according to claim 8 or 9, characterized in that - a first detection device for detecting a first cable force on the retaining cable (24) and a second detection device for detecting a second cable force on the actuating cable (44) are provided, - in that the control device is connected to the first detection device, the second detection device, the first cable winch (21) and the second cable winch (22) and is designed to control the first cable winch (21) and / or the second cable winch (22) in accordance with a control program specification, depending on the detected first cable force on the retaining cable (24) and the detected second cable force on the actuating cable (44).

11. The grab device according to claim 8 to 10, characterized in that the control device is designed with a compensation mode in which the cable winches (21, 22) are controlled in such a way that the first cable force on the retaining cable (24) and the cable force on the actuating cable (44) are matched to each another.

12. The grab device according to one of claims 8 to 11, characterized in that the control device is designed with a rotation mode in which the cable winches (21, 22) are controlled in such a way that a deliberate rotation of the cable grab (30) around a vertical longitudinal axis can be generated.

13. The grab device according to one of claims 8 to 12, characterized in that at least one third detection device for detecting a rotational position of the cable grab (30) and / or a change in the rotational position is provided.

14. The grab device according to one of claims 1 to 13, characterized in that at least one further detection device is provided, in particular for detecting a vertical position of the cable grab (30), a distance and / or an angular position of the cable grab (30) relative to the carrier device (12).

15. The grab device according to one of claims 8 to 14, characterized in that the retaining cable (24) on the first cable winch (21) has a first lay direction which is opposite to a second lay direction of the actuating cable (44) on the second cable winch (22).