GRAB DEVICE AND METHOD FOR OPERATING A GRAB DEVICE

Abstract

The invention relates to a method for operating a grab system, comprising a carrier device and a cable grab arranged thereon, which cable grab comprises a grab frame, which is held by a retaining cable on the carrier device, at least two grab buckets, which are mounted on a lower end of the grab frame, so as to be able to swivel between a closed position and an open position, and an actuating device with an actuating cable for swivelling the grab buckets, wherein an actuating cable is guided from the carrier device to the actuating device, and the carrier device has a driven first cable winch for the retaining cable and a driven second cable winch for the actuating cable, wherein the carrier device has an undercarriage and an upper carriage, which is mounted thereon for rotation about a vertical axis and has a cantilever arm on which the cable grab is vertically adjustably mounted, wherein in a removal step, in order to form a trench in the ground, the cable grab is lowered into the ground by the retaining cable with the grab buckets open, the grab buckets are closed to remove and collect soil material, the cable grab is pulled out of the ground by the retaining cable and swiveled to an emptying position, in which the grab buckets are opened to discharge the collected soil material, by rotating the upper carriage, and then the cable grab is moved back into the ground trench to repeat the removal step. In accordance with the invention, a control device is provided with which a rotation of the upper carriage to the emptying position and an opening and closing of the grab buckets to discharge the soil material or a rotation of the upper carriage from the emptying position back to the ground trench are controlled automatically.

Claims

1.-20. (canceled)

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

22. The method according to claim 21, wherein the control device opens the grab buckets while the cable grab is still oscillating, as a consequence of the rotation of the upper carriage.

23. The method according to claim 21, wherein an introduction of the cable grab into the ground trench and/or a retraction of the cable grab out of the ground trench is controlled automatically by the control device.

24. The method according to claim 21, wherein the control device is connected to and controls the first cable winch and the second cable winch.

25. The method according to claim 22, wherein a sensor device is provided with which an oscillating movement of the cable grab during rotation of the upper carriage is detected.

26. The method according to claim 22, wherein the grab buckets are opened by the control device at the position at a time when the oscillating cable grab is still in a position deflected out of the vertical position.

27. The method according to claim 22, wherein the oscillating cable grab is introduced by the control device into the ground trench, wherein the oscillating movement is damped by contact with the ground.

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

29. The grab device according to claim 28, wherein it is designed to carry out the method according to claim 21.

30. The grab device according to claim 28, wherein a first detection device for detecting a first cable force on the retaining cable and a second detection device for detecting a second cable force on the actuating cable are provided, the control device 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 in accordance with a control program specification, depending on the detected first cable force on the retaining cable and the detected second cable force on the actuating cable.

31. The grab device according to claim 28, wherein the control device is designed with a compensation mode in which the cable winches are controlled in such a way that the first cable force on the retaining cable and the cable force on the actuating cable are matched to each another.

32. The grab device according to claim 28, wherein the control device is designed with a rotation mode in which the cable winches are controlled in such a way that a deliberate rotation of the cable grab around a vertical longitudinal axis can be generated.

33. The grab device according to claim 28, wherein at least one third detection device for detecting a rotational position of the cable grab and/or a change in the rotational position is provided.

34. The grab device according to claim 21, wherein at least one further detection device is provided, in particular for detecting a vertical position of the cable grab, a distance and/or an angular position of the cable grab relative to the carrier device.

35. The grab device according to claim 28, wherein the retaining cable on the first cable winch has a first lay direction which is opposite to a second lay direction of the actuating cable on the second cable winch.

36. The grab device according to claim 28, wherein the control device is designed with a mode for opening and/or closing the grab buckets at a predefined height.

37. The grab device according to claim 28, wherein the cable grab can be held freely suspended from the actuating cable and retaining cable, with closed grab buckets, wherein the cable force in the actuating cable and retaining cable is approximately the same, preferably appropriately approximately +/1 t.

38. The grab device according to claim 28, wherein the cable grab can be held freely suspended from the actuating cable and retaining cable, with open grab buckets, wherein the cable force in the retaining cable corresponds to almost the entire grab weight and the cable force in the actuating cable is in the range from appropriately approximately 1 t to 2 t.

39. The grab device according to claim 28, wherein the control device is designed with a mode for automatically opening the grab buckets and closing them immediately afterwards.

40. The grab device according to claim 28, wherein the degree of opening of the grab buckets can be detected by the control device and this degree is displayed to the operator.

Description

[0048] The invention is described in more detail below by reference to a preferred exemplary embodiment, which is illustrated schematically in the drawings. In the drawings show:

[0049] FIG. 1 a perspective view of a grab device according to the invention;

[0050] FIG. 2 a front view of the cable grab of the grab device of FIG. 1 with closed grab buckets; and

[0051] FIG. 3 a front view of the cable grab corresponding to FIG. 2 with open grab buckets.

[0052] A grab system 10 according to the invention, as shown in FIG. 1, comprises a mobile carrier device 12 with a caterpillar track as an undercarriage 14. An upper carriage 16 with an operator's cab 17 is mounted on the undercarriage 14 for rotation around a vertical rotary axis. Inside the operator's cab 17 there is a control device including an input device for a machine operator.

[0053] A cantilever arm 18 is linked on the upper carriage 16, so as to be able to swivel around a horizontal axis. At a head 20 of the cantilever arm 18, a retaining cable 24 is guided by deflection rollers, from the end of which retaining cable is suspended a cable grab 30 having a grab frame 32 and lower grab buckets 34. The retaining cable 24 can be actuated by means of a first cable winch 21 on the carrier device 12 to raise and lower the cable grab 30. In addition, there is a second cable winch 22 on the carrier device 12 for an actuating cable 44, which is likewise guided via the head 20 to the cable grab 30 to actuate the grab buckets 34 on the lower end of the grab frame 32.

[0054] The mode of operation of the grab device 10 according to the invention is explained in more detail below in conjunction with FIGS. 2 and 3.

[0055] An actuating slide 42 of an actuating device 40 for actuating the grab buckets 34 is mounted in a central region of the grab frame 32 for displacement in a vertical longitudinal direction. The end of the retaining cable 24 is attached to the upper end of the actuating slide 42 so that the cable grab 30 is retained by the actuating slide 42.

[0056] A linkage mechanism 46 having linkage rods 47 is arranged on a lower end of the actuating slide 42. The linkage rods 47 are hinged at one side to the actuating slide 42 and at the other side to one of the grab buckets 34. The grab buckets 34 are themselves swivel-mounted on the lower end of the grab frame 32 by means of pivot bearings 35. The grab buckets 34 can be opened and closed by a relative displacement of the actuating slide 42 in relation to the grab frame 32. A relative displacement of the actuating slide 42 upwards causes the linkage rods 47 to be drawn upwards, wherein the grab buckets 34 are swiveled around their swivel axes 35 into their opening position, as is clearly shown in FIG. 3.

[0057] Underneath the actuating slide 42, a pulley arrangement 50 is provided for the actuating cable 44. The pulley arrangement 50 comprises at least one top roller 52, which is rotatably mounted on the actuating slide 42, and at least one bottom roller 54, which is rotatably mounted on a lower region of the grab frame 32. The actuating cable 44 loops around the rollers 52, 54 and is feeded from above to form loops 56 or lines, wherein the lower end of the actuating cable 44 is firmly connected to the grab frame 32. The actuating slide 42 is thus adjustably connected or coupled to the grab frame 32 by the actuating cable 44.

[0058] Starting from the open position as shown in FIG. 3, the actuating slide 42 is pulled downwards relative to the grab frame 32, using the pulley arrangement 50, by pulling the actuating cable 44 upwards with the second cable winch 22. The linkage rods 47 push the grab buckets 34 downwards with an elevated closing force, wherein the grab buckets 34 are swiveled around their pivot bearings 35 into the closed position as shown in FIG. 2.

[0059] When used in a trench in the ground, soil material can be grabbed and enclosed between the grab buckets 34 with an elevated closing force as compared with the tensile force on the actuating cable 44.

[0060] After pulling the cable grab 30 out of a trench in the ground and moving it to an emptying position, the tensile force on the actuating cable 44 can be reduced. The weight of the grab frame 32 causes it to move downwards relative to the actuating slide 42, so that the grab buckets 34 are swiveled back into their opening position by the linkage rods 47, as shown in FIG. 3.

[0061] This arrangement described is intended as an example only. In principle, other pulley arrangements with different cable linkages and a different linkage mechanism, which allow for a comparable grab bucket actuation, can also be chosen.

[0062] When the grab buckets 34 are full, the upper carriage 16 is automatically swiveled out of the position shown in FIG. 1 about 90 around the vertical axis to an emptying position. The cantilever arm 18 can also be adjusted. In the emptying position, the grab buckets 34 are opened to discharge the soil material, even if the cable grab 30 is still oscillating. The cable grab 30 can also be rotated around its longitudinal axis, in order to align it with the skip on a lorry, for example. The upper carriage 16 can then be automatically swiveled back into the position shown in FIG. 1.

[0063] From there, the cable grab 30 is lowered into a trench in the ground with the grab buckets 34 open to pick up new soil material. It is then pulled back to the position shown in FIG. 1 with the grab buckets 34 closed and it is emptied again.

[0064] When actuating the cable grab 30, it is necessary to coordinate the forces and movements between the retaining cable 24 and the actuating cable 44, in particular to control the torques in the individual cables and hence the torques of the suspended cable grab 30 around its longitudinal axis owing to a so-called lay direction in wound cables.

[0065] In accordance with the invention, appropriate detection devices, which can be arranged for example on the cable winches 21, 22 or on the deflection rollers on the head 20 of the cantilever arm 18, are used to detect forces in the retaining cable 24 and the actuating cable 44. Using a control device, which is preferably arranged in the operator's cab 17 on the carrier device 12, the winches 21, 22 can be controlled depending to the detected cable forces so that either a stabilization of the oscillating movement relative to the longitudinal axis or the rotational position of the cable grab 30 around its longitudinal axis or a specific rotation desired by the machine operator is achieved. The machine operator can enter appropriate inputs into the control device to a desired automatic movement, a compensation mode for position stabilizing, or inputs relating to a desired rotational position of the cable grab 30. On the basis thereof, the control device of the upper carriage 16 can control the cantilever arm 18 or the cable winches 21, 22 accordingly, in order to bring about the desired positioning and opening/closing of the cable grab 30. The control of a simple designed cable grab 30 can be considerably simplified and facilitated for a machine operator in this way.