Rotary crane and method for rotary crane

Abstract

A rotary crane including a vertical axis; an jib that extends from the vertical axis; a drive for rotating the jib about the vertical axis; a condition monitoring which determines wind loading, namely internal force variables, tensions, strains, transverse forces, tilting and torsion torques of the rotary crane; and a computing unit which computes a preferred direction for locking the jib from the wind loading. The invention also relates to a method for orienting the rotary crane. In order to improve the orientation of the jib of a shut down rotary crane it is proposed that the rotary crane includes measuring elements for capturing local measuring local values of the wind loading.

Claims

1. A rotary crane, comprising: a vertical axis; a jib that extends from the vertical axis; a drive for rotating the jib about the vertical axis; a condition monitor configured to determine wind loading from a wind, the wind loading represented by local measuring values of internal force variables, tensions, strains, transverse forces, tilting and torsion torques of the rotary crane; a computing unit configured to compute a preferred direction for locking the jib from the local measuring values of internal force variables, tensions, strains, transverse forces, tilting and torsion torques of the rotary crane wherein the preferred direction minimizes the wind loading based on the local measuring values and coincides with a direction of the wind or deviates from the direction of the wind; measuring elements configured to capture the local measuring values; and a locking brake capable of locking the jib in the preferred direction that deviates from the direction of the wind.

2. The rotary crane according to claim 1, further comprising a signal unit configured to transmit a signal for locking the jib in the preferred direction to the drive.

3. A method for orienting a rotary crane including a vertically extending vertical axis and a jib extending from the vertical axis and rotatable about the vertical axis, the method comprising the steps: measuring at the rotary crane a wind loading represented by local measuring values of internal force variables, tensions, strains, transverse forces, tilting and torsion torques of the rotary crane; computing a preferred direction for locking the jib from the local measuring values of internal force variables, tensions, strains, transverse forces, tilting and torsion torques of the rotary crane wherein the preferred direction minimizes the wind loading based on the local measuring values and coincides with a direction of the wind or deviates from the direction of the wind; and locking the jib in the preferred direction.

4. The method according to claim 3, wherein the jib is rotated into the preferred direction motor driven.

5. The method according to claims 3, wherein a wind direction is monitored and considered when computing the preferred direction.

6. The method according to claim 5, wherein the wind loading is stored as a function of an incident flow direction of the jib and a direction of the jib is selected as a function of the wind direction as the preferred direction where the wind loading is at a minimum.

7. The method according to claim 6, wherein a direction of rotation is selected so that a maximum wind loading is at a minimum when the jib is rotated into the preferred direction.

8. The method according to claim 3, wherein maximum threshold values of the local measuring values are monitored and considered when computing the preferred direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is subsequently described based on embodiments with reference to drawing figures, wherein:

(2) FIG. 1 illustrates a schematic view of a first rotary crane according to the invention;

(3) FIG. 2A illustrates the utilization of the rotary crane for a non-interfered incident flow; and

(4) FIG. 2B illustrates the actual utilization at a construction site.

(5) The rotary crane 1 according to the invention that is illustrated in FIG. 1 is a top rotating turret rotary crane and includes a concrete foundation 2, a turret 3 that is based therein torque proof and an upper crane 6 that is rotatably supported by a stewing ring 4 on the turret 3 about a vertical axis 5.

(6) The upper crane 6 includes a cab 7 for an operator of the rotary crane 1 and above the cab 7 a jib 8, herein a trolley jib for carrying a non-illustrated load and a counter jib 9 with ballast 10. The jib 8 and the counter jib 9 are supported at a turret tip 11 arranged in the vertical axis 5 using tension links 12.

(7) On the jib 8, the counter jib 9 and on the turret tip 11, three combined wind measuring devices 13 are arranged respectively for measuring a local wind speed (anemometer) and a wind direction (anemoscope) and three measuring elements 14, namely strain gauges are arranged at a top of the turret 3 and at the bottom of the turret 3 and at three locations at an even distance 15 from the foundation 2 to the cab 7 measuring elements 16 namely accelerometers are arranged.

(8) Down below on the foundation 2 there is a non-illustrated control arrangement for the rotary crane 1 with condition monitoring. The condition monitoring monitors the measuring values of the measuring elements 14 and 16 and derives there from internal force variables, tensions and strains and transverse forces, tilting and torsion torques which are combined to loading (in the sense of EN 1990) of the rotary crane 1.

(9) Furthermore the condition monitoring determines the portion of the wind loading from the loading of the crane in that the condition monitoring subtracts the influence of the load suspended at the jib 8 that is known from the jib position, hook load and trolley or elevation position of the jib and continuously stores the wind loading as a function of a wind direction that is computed as an arithmetic mean from the measured wind directions.

(10) The rotary crane 1 is configured to be set up in a non-illustrated construction site presuming a free incident flowing in the local meteorological main wind direction. FIG. 2A illustrates a sine shaped profile of the torque 17 impacting the upper crane 6 about the vertical axis 5 plotted over a relative angle 18 of the jib 8 versus a non-illustrated longitudinal axis of the foundation 2. The angular offset 19 of the torque 17 corresponds to an orientation of the longitudinal axis of the foundation 2 of approximately 45 counter clockwise relative to the main wind direction that is inherent to the construction site.

(11) In the first zero crossing 20 of the torque 17 the jib 8 is pointing with the wind. The rotary crane 1 is without torque in this position, thus in equilibrium with respect to the wind loading. The equilibrium is stable because for each rotation of the upper crane 6 from this position the wind forces generate a torque 17 that counteracts the rotation.

(12) For a further rotation of the upper crane 6 counter clockwise and an increase of the angle of attack by up to 90, the wind generates an increasing torque 17 with negative prefix, thus against the direction of rotation wherein the absolute value of the torque reaches a maximum of 21 when the jib 8 is oriented transversal to the wind. During a counter clock wise rotation the torque 17 decreases towards the second zero crossing 22 where the jib 8 points into the wind. Also in this position the rotary crane 1 is in a torque equilibrium, however the equilibrium is instable because the wind forces generate a torque 17 that supports the rotation for each rotation from this position.

(13) A further counter clock wise rotation yields an increasing torque 17 again with a positive prefix, thus supporting the rotation up to the second maximum 23 when the jib 8 is transversal to the wind again.

(14) FIG. 2A furthermore illustrates a qualitative diagram of the utilization 24 of the rotary crane 1 with respect to a tilting torque at the crane base that is generated by the wind loading. The utilization 24 increases from an absolute minimum 25 in the first zero crossing 20 of the torque 17, thus when the jib is oriented with the wind, when rotated beyond a position transversal to the wind the torque increases to a maximum 26 and decreases to a local minimum 27 until the jib 8 is oriented into the wind. When the jib 8 is rotated further counter clockwise the utilization 24 is a mirror image down to the absolute minimum 25.

(15) FIG. 2B illustrates diagrams for the torque 28 and the utilization 29 for the same wind direction determined from measurements at the construction site by the condition monitoring, wherein torque and utilization are significantly distorted by a building with rectangular plan form that is arranged in the main wind direction laterally in front of the rotary crane 1. At the absolute minimum 30 of the utilization 29 a zero crossing 31 of the torque 28, thus an equilibrium is provided, but this equilibrium is stable.

(16) For a small random displacement of the upper crane 6 in counter clock wise direction, thus with increasing angle of attack 32 this rotation is supported by a small positive torque 28 up to a first zero crossing 33 of the torque 28. In this position the rotary crane 1 is in a stable equilibrium, however it is loaded by more than twice the amount compared to the minimum 30.

(17) For a small random displacement of the upper crane 6 in clock wise direction, thus with a decreasing angle of attack 32, this rotation is not only supported slightly, but significantly accelerated by a quickly increasing torque 28. When the wind load is maintained, then the upper crane 6 due to the acceleration will not only pass through a position with maximum utilization 29 without braking but also through the unstable equilibrium position in the second zero crossing 34 of the torque 28 when the jib 8 is oriented into the wind. Since the torque 28 braking the rotation with a negative prefix has a significantly smaller absolute value in the adjoining portion there is an increased risk that also the stable equilibrium is transitioned and the upper crane 6 moves into auto rotation.

(18) Accordingly diagrams of torques 28 and utilization 29 for all wind directions that can occur at the construction site are stored in the condition monitoring. When the rotary crane 1 according to the invention is shut down due to exceeding a maximum wind velocity v.sub.smax and a preset threshold value of the utilization 29 is exceeded, the condition monitoring determines from these diagrams angles of attack 32 of the upper crane 6 where the wind loading and thus the utilization 29 of the rotary crane 1 is at a minimum for the respective prevailing wind direction and the direction of rotation where the maximum wind loading is minimal when the upper crane 6 is rotated in this preferred direction and transmits both values to the control arrangement.

(19) The control arrangement of the first rotary crane 1 according to the invention generates an acoustic alarm and signals to the operator a direction of rotation and a preferred direction of the jib 8. The operator steers into this direction using the drive at the slewing ring 4 and locks the jib 8 in this direction using the parking brake of the slewing ring.

(20) In another embodiment of the rotary crane 1 that is otherwise identical the control device monitors the wind induced rotation of the upper crane that is turned with the wind brakes the upper crane automatically using the motor drive at the slewing ring when the preferred direction is being approached and in turn activates the locking brake.

(21) In another rotary crane according to the invention that is otherwise identical the control device actively steers into the preferred direction through the drive at the slewing ring.

(22) In another otherwise identical rotary crane according to the invention the condition monitoring captures meteorological wind data, wind velocity and direction, through remote data transmission and initiates a steering into a preferred direction also independently from exceeding a threshold value of the utilization in a precautionary manner wherein the wind loading is minimal in the preferred direction.

(23) In another otherwise identical rotary crane according to the invention the condition monitoring is configured redundant.

(24) TABLE-US-00001 REFERENCE NUMERALS AND DESIGNATIONS 1 rotary crane 2 foundation 3 turret 4 slewing ring 5 vertical axis 6 upper crane 7 cab 8 jib 9 counterjib 10 ballast 11 turret tip 12 tension member 13 wind measuring device 14 measuring element (strain gauge) 15 distance 16 measuring element (acceleration sensor) 17 torque 18 angle of attack 19 angular offset 20 zero crossing 21 maximum 22 zero crossing 23 maximum 24 utilization 25 maximum 26 maximum 27 minimum 28 torque 29 utilization 30 minimum 31 zero crossing 32 angle of attack 33 zero crossing 34 zero crossing