EP0638510A1 - Arrangement for damping actively the oscillations of/and positioning suspended loads - Google Patents

Abstract

A damping and positioning arrangement for actively damping the oscillations of suspended loads during traversing movements of the suspension point, having guide ropes, running between a crane or suspension-rail conveying system and the load, for damping the oscillating movement of the load. According to the invention, it is proposed that at least two guide ropes (6a-6h) be provided for each pendular oscillation plane, and that the guide-rope drums (5) be arranged on a frame (3, 14) hung on the crane or the suspension-rail conveying system and that they be subjected to a tensile force which always acts against the oscillation of the load. The tensile force is produced via a drive unit, the output force or moment of which is controlled independently of the rotational speed of the guide-rope drums. The length of the guide ropes (6a-6h) can be varied independently of one another and also during the operation of the crane or the suspension-rail conveying system. <IMAGE>

Description

The invention relates to a positioning and damping device for damping the pendulum movement of pendulum suspended loads during movement of the suspension point according to the preamble of the main claim.

From AS 12 37 283 a device for preventing vibratory movements of a mounting part for a load, which is suspended from a crane by means of hoisting ropes, is known. In this device, in addition to the supporting cables, cable drums are running out Guide ropes provided. The rope drums have winding springs and friction brakes. The springs ensure that the guide cables are wound up when lifting, the friction brakes increase the cable force in the cable, which becomes longer during a pendulum process. When the rope gets shorter, the friction brakes are rendered ineffective by freewheels. Due to the diagonally positioned rope drums, damping in both pendulum vibration levels is achieved with four ropes. A disadvantage of the design is that the friction brakes do not allow any change in the force in the guide rope. The result is permanent pendulum deflections.

In addition, a system consisting of obliquely braced additional guide ropes is known from DE OS 15 06 534. Two ropes each run from drums with a common axis. The shafts of these drums are connected to each other via a differential gear and freewheels. When the load is oscillating, the pendulum effect is dampened with the help of a band brake on the web of the planetary gear. The bridge is then brought out of motion when the other two shafts have uneven speeds due to the pendulum motion. In this solution, it is disadvantageous that, due to the one-way clutches which are dependent on the direction of rotation, the damping force can only be generated via the brake when the guide rope becomes longer. The pendulum damping is therefore limited during the lifting movements.

Other devices are known which avoid the swinging of a load suspended on a crane. These devices are mostly fixed rope tensions. However, these are characterized by considerable mechanical effort. They also usually have the peculiarity that some of the ropes become slack when certain horizontal accelerations are reached. This severely limits the dynamics when starting and braking. These rope tensions are generally resistant to the effects of wind within the limits set by the elasticity of the ropes. Such devices with fixed rope tension are known, for example, from DE OS 19 25 849, DE PS 55 82 63 or DE PS 29 17 588.

Further mechanical solutions for damping the pendulum movement of a load suspended from a crane are known, for example, from AS 12 73 155 or AS 11 184 053 and AS 12 07 578. The first-mentioned document describes the possibility of pendulum compensation by switching a travel drive on and off depending on the pendulum angle. The suspension cable, which swings with the load, actuates switches that switch the drive motor on and off. When starting off, the engine is temporarily switched off or its drive torque is reduced if the initially remaining load is deflected too much. When braking, the projecting load causes the traction motor to be switched on again. AS 1 184 053 describes a system in which only the maximum pendulum angle is reduced. In the system described there, a missing bearing in the hoist detects the weight load due to the attached load. The spring travel is converted into an increase in the pressing force of a friction clutch on the traction motor, so that the acceleration of the crane is automatically reduced at low loads. The last-mentioned document, AS 12 07 578, describes a switching angle-dependent switching on and off of drive motors. When moving off, the pendulum deflection is recorded with the aid of a pendulum angle measuring device and the traction motor is switched off at a certain moment while the brake is still ventilated. If the load is exactly perpendicular under the trolley during its subsequent vibration in the direction of travel, the drive motor is switched on again. This is said to be during the Ride a calm commute arise.

The object of the present invention is to provide a device for damping the oscillation of loads suspended in an oscillating manner during movements of the suspension point, which the above-mentioned. Avoids disadvantages of the known solutions. In addition, the device should allow fine positioning of the load.

This object is achieved by the features specified in the main claim. The subclaims represent advantageous developments.

The basic idea of the invention is based on the fact that e.g. a crane or a monorail is generally permitted to swing the load - and by means of additional guiding elements attached to it (in the following the processes are described using a crane), e.g. a crane or a cat, the load is damped and the load is independent of the exact position of the suspension point is positioned exactly relative to the transfer position. The device has at least two guide cables provided for each pendulum vibration level, each of which runs from a cable drum and is attached either to the crane hook or to an attached load suspension device.

The guide rope drums are located on a frame suspended from the crane or crane trolley. They are permanently loaded with a tensile force that always acts against the oscillation of the load and is regulated by a drive unit, the output force or torque of which is independent of the guide rope drum speed. The size of the maximum guide rope force or the tensile force loading the guide rope depends on the geometric conditions on the crane, such as: distance of the force generators and lifting height, the acceleration behavior of the crane drives and the mechanical load capacity of the trolley and can therefore be individually determined for each crane. The device acts in such a way that on the drive unit from which the load moves away, the tractive force is increased in a precisely defined manner. In the simplest case, the maximum tractive force is set during this movement phase. Improvements are achieved by taking into account several movement variables such as pendulum angle, pendulum speed and acceleration as well as a jerk-minimized force curve. By increasing the tensile force in one of the two guide ropes belonging to a vibration level, a force is transmitted to the oscillating load via the guide ropes, which counteracts the oscillation and thereby dampens it. The size of the pulling force, in addition to the current rope length of the suspension ropes and the horizontal distance between the drive units on the pedestal under the cat, has a decisive influence on the size of the damping. With a large guide rope force there is a smaller maximum pendulum angle than with a small guide rope force. Accordingly, after a crane or trolley acceleration with a high pulling force in the guide ropes, there are fewer pendulum deflections until the pendulum is completely relaxed than with a small guide rope force.

At least two guide ropes are required for each of the two levels of pendulum vibration (e.g. trolley and bridge travel direction). Even slight tolerance deviations when fastening the guide ropes, but also eccentric loads would cause torsional vibrations of the load. It is particularly advantageous if a total of four guide ropes run from the platform under the trolley to the load handler in one of the two pendulum vibration levels. This effectively prevents the load from rotating due to the above-mentioned forces. In addition, the reaction moment of a slewing gear arranged in the travery can be supported by different forces in the guide ropes of a common rope drum. With increased demands on the A two-strand cable drive with a total of four cables resting on two drums can also be used to stabilize the rotational position for the other pendulum vibration level. With the same control forces, this corresponds to a doubling of the permissible external torque. A particular advantage of the invention is that this optimally adjusted setting can be used both to prevent the rotation of the load and to dampen the vibration of the load or to fine-position the load with respect to a transfer position even during the operation of the crane. The specifications therefore do not have to be made at the start of the movement, they can be adjusted as required during the operation of the crane. For example, only the minimum control force in the two double-stranded guide rope drives is increased during the turning operations during the actual rotation. Since turning processes can often be placed in the stroke time or in the time of constant travel speed, a worsening of the pendulum damping can be avoided. Basically, a minimum pulling force always remains set, so that slack rope is prevented in the guide ropes when the crane hoist moves upwards, ie the guide ropes are wound up.

In each of the guide rope drums, for example, an angle encoder is attached to measure the length of the guide rope. The pendulum angle of the load relative to the vertical can be determined by comparing the angles of rotation of two drums, the guide cables of which lie in a vibration plane. If these angles of rotation are constantly the same, the load hangs underneath the hoist without swinging. This applies regardless of whether the hoist is at rest or switched on. With the help of both rope lengths, the current lifting height can also be calculated. If the angles of rotation of the guide rope drums of a vibration level are not the same, then lies a pendulum deflection before and the tensile force in the guide ropes is set appropriately.

To control the tensile force, it is possible to set it to a calculable value and to keep it constant during a half-vibration. In this way, the load remains exactly perpendicular under the trolley if, when this position is reached, the pulling force is immediately reduced to the minimum value that is set in the other guide rope. The tensile forces required for this type of control in the guide ropes are always calculated with the current values for the parameters influencing the vibration. These parameters are essentially the length of the suspension cables, the pendulum angle at the beginning of the half-vibration and the bracing angle of the guide cables. In this case it is necessary that the actual pulling force corresponds very precisely with the calculated target value.

According to claim 6, it is advantageous if the high accuracy in setting the guide rope force is dispensed with. In addition, relatively slow changes in the guide rope force can be used to minimize jerk and, depending on the pendulum angle and pendulum speed, the rope force can be continuously readjusted until the desired position of the load is reached. Inaccuracies in the adjustment of the rope force are compensated for by the control itself and generally do not lead to a residual oscillation or a noticeable increase in the damping time.

It is particularly advantageous that the device according to the invention can be used in addition to the pendulum damping also for fine positioning of the load-carrying means relative to a fixed transfer position, such as a machine or a transfer place. The control of the Lead rope forces performed depending on the path difference between the target and actual position of the load handler. The path difference is detected, for example, by an encoder on the load suspension device, an encoder on the transfer station or by an image sensor system. Corresponding to the deviation from the target value, the relevant guide ropes are then shortened or lengthened in such a way that the actual position comes as close to the target value as the resolution of the measuring systems used (displacement or rotary encoder) allow. The crane's trolley or bridge drives are therefore not used for fine positioning. After such a process of absolute fine positioning, the load no longer hangs vertically to the crane trolley. The different forces of the activated guide ropes keep the load in a stable balance. In the area of the destination, the control is carried out by a signal generated by an encoder on the load handler, a sensor at the transfer point or by an image sensor via the path difference between the actual position of the load handler and the target position of the load handler.

In order to achieve high positioning accuracy on the one hand and high damping on the other hand, the distance between the drive units for the guide cables should be large. As a result, short damping times and high positioning accuracy can be achieved with small control forces. It is envisaged that if there is insufficient space directly under the crane trolley, the support frame with the guide rope drums should be arranged below the bridge girders. It is particularly advantageous if the distance between the two guide rope drums can be adjusted to one another. It is then possible to avoid a reduction in approach dimension. The pendulum damping is not adversely affected by the one-sided retraction of the adjustment frame, that when approaching an edge of the hall predominantly lies the one behind in the direction of travel Guide rope is required for damping and the rope drum is in the rearmost position. The asymmetrical operating position of the frame is sketched in Fig. 1.

The guide rope drums of the other vibration level can also be arranged on adjustment frames in order to be able to adapt their bracing angle to the requirements.

Another concept variant is not to generate the horizontal forces required for the pendulum damping by means of additional guide ropes, but to deflect the lifting ropes directly at the level of the substructure. This can be done using linear drives of any type. The power transmission can e.g. by means of rollers in order to decouple the vertical movements of the cable drive from the horizontal force transmission to the pendulum damping when the hoist is switched on.

The horizontal force is generated via 2 pairs of rollers offset by 90 °, which are mounted on linear guides and can be moved horizontally using any force generator.

The horizontal distance between two rollers corresponds to the diameter of the suspension cable, so that the displacement path of the rollers corresponds to an equally large displacement path of the suspension cable.

A horizontal force is applied to the suspension cable according to the same principles as the setting of the tensile forces in the inclined guide cables of the device described above. Accordingly, the horizontal force is always set so that its direction of action is directed against the direction of the pendulum angular velocity.

The structure of the pendulum angle from the rest position corresponds to a movement of the corresponding displacement plate, the drive of which then builds up a force which counteracts this displacement.

The direct detection of the pendulum angle is not necessary since the sliding plates, which support the roller arrangement, are equipped with a measuring device for the linear sliding path.

In contrast to the stay cable arrangement, this variant does not require any design changes or additions to the load suspension device or to a crossbar.

Just as with the device with inclined guide ropes, a position correction can be carried out as fine positioning in the variant of the suspension cable displacement when the travel drives of the crane are at a standstill. This creates a permanent suspension cable displacement or a static horizontal force, which keeps the suspension cable in a fixed horizontal deflection.

When driving, it is important to generate the pendulum angle zero. This happens through the horizontal forces until there is no change in the roll position and at the same time the horizontal force disappears. The position correction is carried out in such a way that the respective position of the displacement plate is shifted exactly by the size of the associated initial position error and the horizontal force no longer changes after the fine positioning has been completed.

In one of the two vibration levels, the end position of the rollers is fixed by the construction dimensions of the hoist and the trolley. There is only a small travel distance.

On the other level, the rope migration on the lifting drum changes the position of the sliding plate. The travel range must be correspondingly larger.

From the knowledge of the stationary, horizontal holding force after the position correction and the displacement during the correction process, the size of the attached load can be calculated directly.

With the device according to the invention, almost any crane, preferably in a bridge or portal construction, can be retrofitted. A particular advantage of the device according to the invention is the possibility of active fine positioning of the load suspension device, which is decoupled from the crane or the trolley, or also a stable load suspension of eccentric loads within defined limits without any horizontal movement due to rope elasticities.

Fig. 1:

Eine perspektivische Darstellung der Positionier- und Dämpfungseinrichtung;

Fig. 2a:

Draufsicht auf die räumliche Anordnung der Führungsseile

Fig. 2b:

Ansicht der Darstellung der Fig. 2a in Brückenfahrtrichtung;

Fig. 2c:

Ansicht der Darstellung der Fig. 2a in Katzfahrtrichtung;

Fig. 3:

Seitenansicht einer Variante der Tragseilverschiebung;

Fig. 4:

Draufsicht auf die Darstellung der Fig. 3;

Fig. 5:

Darstellung der Wirkungsweise der Tragseilverschiebung.

The invention is illustrated by the following drawings. Show it:

Fig. 1:

A perspective view of the positioning and damping device;

Fig. 2a:

Top view of the spatial arrangement of the guide ropes

Fig. 2b:

2a in the direction of bridge travel;

Fig. 2c:

View of the representation of Figure 2a in trolley travel direction.

Fig. 3:

Side view of a variant of the suspension cable displacement;

Fig. 4:

Top view of the representation of Fig. 3;

Fig. 5:

Presentation of the mode of operation of the suspension cable displacement.

Fig. 1 shows an overview of the structural design of the damping and positioning device. The standard components of a gantry crane, e.g. Hoist and suspension cables are not shown for reasons of clarity.

The damping and positioning device has a movable crane trolley 1, connection carrier 2, a support frame 3 and adjustment frame 4a, b. The supporting frame 3 is attached to the supporting structure of the crane trolley 1 which can be moved on the crane bridge 9 by means of the connecting supports 2. The two linearly displaceable adjustment frames 4a, b are attached to the frame 3. The adjustment frame 4a is shown retracted, while the adjustment frame 4b is shown in the extended position. Each of these adjustment frames 4a, b carries two guide rope drums 5, which are mechanically coupled by a shaft 8. On the support frame 3 there are four further guide rope drums 5, which are arranged offset by 90 °. The control cables 6, which each run in pairs and in parallel from coupled cable drums 5, are guided to a cross member 7 and articulated there. With the help of the control cables 6a-6d, the oscillation or fine positioning of the crossbeam 7 with the attached load is influenced in the direction of bridge travel, the control cables 6e-6h are used to influence the Pendulum or fine positioning in the direction of trolley travel. The drive motors of the cable drums 5 are not shown for simplification.

FIGS. 2a-2c illustrate the spatial arrangement of the guide ropes 6. The choice of different cable distances and the arrangement of the articulation points 10 on the cross member 7 ensure that the guide ropes 6 do not touch one another.

3 and 4, an embodiment variant of the suspension cable displacement is shown. In this variant, the frame 15 is suspended from a crane trolley 11, which drives on a trolley rail 12 of the crane bridge 13, by means of the connecting supports 14. The lifting cable 16 runs from a lifting cable drum 17 through the center of the frame 15. A lower displacement plate 18 supported in linear guides 17 is supported on the frame 15. The lower displacement drive 20 is used for their linear adjustment. On the lower sliding plate 19, an upper sliding plate 21 is also rotated by 90 ° and is mounted in linear guides 18. The upper displacement drive 22 is used to displace them. Shift rollers 23 and 24 serve to actively displace the suspension cable. They are set so that their horizontal distance corresponds to the cable diameter. A displacement of one or both displacement plates 19, 21 thus causes a horizontal displacement of the suspension cable in one or both directions. The design size of the respective adjustment path depends on the specific application. In one of the two directions, however, the adjustment path is fundamentally larger, since the hook migration must be compensated for by the cable drum due to the change in the run-off point of the suspension cable.

In Fig. 5, the operation of the positioning and damping device in the variant of the suspension cable displacement is shown in more detail. The pendulum angle is denoted by φ, the pendulum angular velocity is denoted by φ '. A horizontal force is preferably applied to the supporting rope via a roller arrangement constructed according to FIG. 3, 4 below the trolley or the lifting mechanism. The size of the force depends on the current size, direction and rate of change of the pendulum angle or the position deviation of the load at the target point. The pendulum movement of the load is dampened, or any positional deviation of the load remaining after the crane or trolley travel has been compensated. The adjustment path can be increased in one of the two vibration directions in order to allow the rope to move on the lifting drum without influencing the pendulum damping.

Claims (9)

A damping and positioning device for the active damping of the oscillation of a pendulum suspended loads during traversing of the suspension, in particular extending between a crane and a crane trolley or of a monorail and the load guide ropes for damping the pendulum movement of the load and wherein the guide ropes of guide drums proceed, characterized characterized in that at least two guide ropes (6a-6h) are provided for each pendulum vibration level and the guide rope drums (5) are arranged on a frame (3, 14) suspended from the crane or from the crane trolley (1, 10) or the overhead conveyor, and that the guide ropes (6a-6h) are loaded with a tensile force that always acts against the oscillation of the load and that is generated by a drive unit, the output force or torque of which is regulated independently of the guide drum speed, and that the length of the guide ropes (6a -6h) independently of one another and also during operation s of the crane or the overhead conveyor is changeable. Damping and positioning device according to claim 1, characterized in that at least in one of the two levels of pendulum vibration, four guide ropes (6) run from the frame to the load-carrying means, two in each case being arranged in parallel. Damping and positioning device according to claim 1 or 2, characterized in that the tensile force present in the guide ropes (6) is adapted to the pendulum movements of the load, but that the guide ropes (6) are always loaded with a minimal tensile force. Damping and positioning device according to one of claims 1 to 3, characterized in that a sensor is arranged on each rope drum (5) for detecting the rope length and thus also the pendulum angle and the pendulum angle speed of the load. Damping and positioning device according to one of claims 1 to 4, characterized in that the guide cables are loaded with a constant tensile force during that phase of oscillation of the load in which the guide cable or cables (6) are unwound from the cable drum (5). Damping and positioning device according to one of the preceding claims, characterized in that the guide ropes (6) are loaded at all times with the pulling force which is set as a function of the current movement quantities of the pendulum movement, and thus variable. Damping and positioning device according to claim 6, characterized in that sensors are present which have a path difference between the actual load suspension device target position and the load suspension device position measure and that the position of the load handler is then changed accordingly by changing the guide rope lengths. Damping and positioning device according to one of the preceding claims, characterized in that the horizontal position of the guide cable drums (5) for both drives of an oscillation plane (4a, 4b) can be set independently of one another. Device according to one of the preceding claims, characterized in that the frame (3, 4) on which the guide rope drums (5) are arranged has larger dimensions than the crane trolley.

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