GRIPPER DEVICE AND METHOD FOR OPERATING A GRIPPER DEVICE

Description

[0001] The invention relates to a gripper device with a carrier device and a cable gripper arranged thereon, which has a gripper frame which is held on the carrier device via a holding cable, 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 cable for pivoting the gripper blades, wherein the actuating cable is guided from the carrier device to the actuating device, and the carrier device has a driven first cable winch for the holding cable and a driven second cable winch for the actuating cable, according to the preamble of claim 1.

[0002] The invention further relates to a method for operating a gripper device according to the preamble of claim 13.

[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. The grab is suspended from a carrier device, typically a jib crane, via a tether. The tether allows the grab to 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 tether 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 its working position and inserted into the slot in the ground for another grabbing 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 are relatively easy to operate and control thanks to the 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, and 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 winch.

[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, and requires an experienced operator. One reason for this is that the dual configuration of the rope—namely, the holding rope and the actuating rope—generates torques in various operating states, causing a certain degree of rotation of the rope grab around its longitudinal axis. However, a precise rotational position of the rope grab is essential for reinserting the rope grab into a previously created slot in the ground when returning it from the emptying position.

[0010] JP 2001 064993 shows a typical rope grab in which a visual and acoustic assistance system facilitates the operator's manual positioning and alignment for underwater use of the rope grab.

[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] The invention is based on the Task The aim of the invention is to provide a gripper device and a method for operating the gripper device, which furthermore provide a simple structure for the gripper device and at the same time enable simple operation.

[0013] The object is achieved, on the one hand, by a gripper device having the features of claim 1 and, on the other hand, by a method having the features of claim 13. Particular embodiments of the invention are specified in the respective dependent claims.

[0014] The gripper device according to the invention is characterized in 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 a control device is provided which is connected to the first detection device, the second detection device, the first cable winch and the second cable winch and is designed to control the first cable winch and / or the second cable winch according to a control program specification as a function of the detected first cable force on the holding cable and the detected second cable force on the actuating cable.

[0015] The invention is based on the finding that a torque on a cable gripper about its longitudinal axis depends on the cable forces in the holding cable and the actuating cable. According to one aspect of the invention, detection devices are therefore provided with which a cable force on the holding cable and a cable force on the actuating cable are detected. The respectively detected force values ​​can be fed to a control device, which controls a first cable winch for the holding cable and a second cable winch for the actuating cable according to inputs and specifications from the machine operator.The control device can thus coordinate the forces in the holding cable and the actuating cable by appropriately controlling the respective cable winch (cable winding / unwinding), so that, for a given or desired rotational position of the cable gripper, no torque is generated around the longitudinal axis by the holding cable and the actuating cable. The control device can also be used to generate a defined (variable) torque for a desired twist by appropriately influencing the respective cable forces.

[0016] The invention is further based on the finding that, particularly in the conventional use of steel cables made of wound steel wires or strands, a so-called cable lay occurs, which, in the case of steel cables that are not rotation-resistant or rotation-free, leads to a torque about the cable's longitudinal axis when corresponding tensile forces are applied to the steel cable. Provided that the holding cable and the actuating cable have an opposite lay direction, compensation for these torques generated by the cables can be achieved by coordinating the tensile forces in the holding cable and the actuating cable. This can preferably be achieved in a particularly simple manner if cables of the same or similar construction are used, but which have an opposite lay direction.By using two ropes with opposing lays attached to a body, a torque balance, a counterclockwise or clockwise torque, can be generated on the body with an appropriate tensile force distribution. The holding rope can preferably be attached to an upper or lower area of ​​the gripper frame or the actuating device.

[0017] 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.

[0018] 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 and cancel each other out. 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.

[0019] 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 then bring about a desired change in the rotational position by appropriately actuating the cable winches, preferably via an input device such as a thumbwheel on a joystick. 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, wherein the control device actuates the winches in accordance with the program logic such that the desired changed rotational position is established.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] In principle, the actuating cable can be directly linked to the grab buckets. To achieve the highest possible closing forces, according to a further development of the invention, it is advantageous for the actuating device to have an actuating carriage connected to the grab buckets via a linkage mechanism, and for the actuating carriage to be displaceable along the grab frame for pivoting the grab buckets. The actuating carriage is preferably mounted on the grab frame so that it can be displaced in a longitudinal or vertical direction. The linkage mechanism can comprise joints, linkage rods, or linkage cables. An actuating carriage can, in particular, ensure the most uniform opening and closing movement of the grab buckets. This is advantageous for stabilizing the position of the rope grab.

[0026] Particularly high closing forces can preferably be achieved by providing a pulley assembly on the actuating carriage, with which an increase in force for closing and / or opening the grab buckets can be generated. By means of a pulley assembly, the force on the actuating cable for opening and closing the grab buckets can be multiplied depending on the number of pulls. The pulley assembly is positioned in particular between the actuating carriage and the lower end of the grab frame. The pulley assembly, which is mounted on the actuating carriage on the one hand and on the grab frame on the other, can be wrapped by the actuating cable, the lower end of which is attached to the grab frame. This results in a corresponding extension of the cable path for actuating the actuating carriage with the desired increase in force.

[0027] 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.

[0028] The invention further comprises a method for operating a gripper device, wherein the gripper device according to the invention described above is used, wherein a first cable force on the holding cable is detected by means of a first detection device and a second cable force on the actuating cable is detected by means of a second detection device, and that the first detection device, the second detection device, the first cable winch and the second cable winch are connected to a control device by which the first cable winch and / or the second cable winch are controlled according to a control program specification as a function of the detected first cable force on the holding cable and the detected second cable force on the actuating cable.

[0029] The method enables the previously described advantages to be achieved in the gripper device according to the invention.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Below the actuating carriage 42, a pulley assembly 50 is provided for the actuating cable 44. The pulley assembly 50 has an upper roller 52, which is rotatably mounted on the actuating carriage 42, and a lower roller 54, which is rotatably mounted on a lower region of the gripper frame 32. The actuating cable 44, fed from above, wraps around the rollers 52, 54 several times, 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.

[0038] 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. In this case, 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.

[0039] 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.

[0040] 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.

[0041] This described arrangement is only an example. In principle, other pulley arrangements with different rope linkages and a different linkage mechanism can also be selected, enabling comparable grapple bucket operation.

[0042] When operating the rope grab 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 grab 30 about its longitudinal axis, particularly due to a so-called lay direction in wound ropes, so that a desired rotation of the rope grab 30 only occurs when this is necessary for the construction process.

[0043] 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 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 only needs to provide appropriate inputs regarding a possibly desired compensation mode for position stabilization or inputs regarding a desired rotational position of the vertical gripper 30. Based on this, the control device can control the cable winches 21, 22 accordingly to achieve the desired rotational position of the cable gripper 30.

[0044] This makes the control of a simply constructed rope gripper 30 considerably easier and simpler for a machine operator.

Claims

1. Grab device with a carrier implement (12) and a rope grab (30) arranged thereon which has - a grab frame (32) which is held on the carrier implement (12) via a holding rope (24), - at least two grab shovels (34) which are pivotably supported on a lower end of the grab frame (32) between a closed position and an open position, and - an actuating means (40) with an actuating rope (44) for pivoting the grab shovels (34), - wherein an actuating rope (44) is guided from the carrier implement (12) to the actuating means (40) and - the carrier implement (12) has a driven first rope winch (21) for the holding rope (24) and a driven second rope winch (22) for the actuating rope (44), - wherein a first detection means for detecting a first rope force on the holding rope (24) and a second detection means for detecting a second rope force on the actuating rope (44) are provided, characterized in that - a control means is provided which is connected to the first detection means, the second detection means, the first rope winch (21) and the second rope winch (22) and which, depending on the detected first rope force on the holding rope (24) and the detected second rope force on the actuating rope (44), is designed to activate the first rope winch (21) and / or the second rope winch (22) according to a control program specification.

2. Grab device according to claim 1, characterized in that by the control program specification of the control means a defined ratio between the first rope force in the holding rope (24) and the second rope force in the actuating rope (44) is specified and can be set.

3. Grab device according to claim 1 or 2, characterized in that the control means is designed with a compensation mode, in which the rope winches (21, 22) are activated such that the first rope force on the holding rope (24) and the second rope force on the actuating rope (44) are matched to each other.

4. Grab device according to any one of claims 1 to 3, characterized in that the control means is designed with a turning mode, in which the rope winches (21, 22) are activated such that a targeted turning of the rope grab (30) about a vertical longitudinal axis can be generated.

5. Grab device according to any one of claims 1 to 4, characterized in that at least a third detection means for detecting a rotational position of the rope grab (30) and / or a change of the rotational position is provided.

6. Grab device according to any one of claims 1 to 5, characterized in that at least one further detection means is provided, in particular for detecting a vertical position of the rope grab (30), a distance and / or an angular position of the rope grab (30) with respect to the carrier implement (12).

7. Grab device according to any one of claims 1 to 6, characterized in that the control means is designed with an automatic program, through which the rope grab (30) can be moved automatically to an emptying position and / or to a removal location.

8. Grab device according to any one of claims 1 to 7, characterized in that the holding rope (24) on the first rope winch (21) has a first winding which is opposed to a second winding of the actuating rope (44) on the second rope winch (22).

9. Grab device according to any one of claims 1 to 8, characterized in that the actuating means has an actuating carriage (42) which is connected to the grab shovels (34) via a linkage mechanism (46), and in that the actuating carriage (42) is displaceable along the grab frame (32) for pivoting the grab shovels (34).

10. Grab device according to claim 9, characterized in that on the actuating carriage (42) a pulley block arrangement (50) is provided, with which a force increase for closing and / or opening the grab shovels (34) can be generated.

11. Grab device according to any one of claims 1 to 10, characterized in that an operating panel for manual control to actuate the rope grab (30) and / or the rope winches (21, 22) is provided.

12. Grab device according to any one of claims 1 to 11, characterized in that for operation a display screen for the control means is provided.

13. Method for operating a grab device, characterized in that a grab device (10) according to any one of claims 1 to 12 is employed, wherein a first rope force on the holding rope (24) is detected by means of a first detection means and a second rope force on the actuating rope (44) is detected by means of a second detection means, and in that the first detection means, the second detection means, the first rope winch (21) and the second rope winch (22) are connected to a control means, by which, depending on the detected first rope force on the holding rope (24) and the detected second rope force on the actuating rope (44), the first rope winch (21) and / or the second rope winch (22) are activated according to a control program specification.

14. Method according to claim 13, characterized in that by means of the rope grab (30) ground is removed and, in particular, a trench is produced in the ground.