FI125656B - Method for controlling a crane - Google Patents

Description

Procedure for controlling a lifting crane

Technical area

The present invention relates to a method according to the preamble of claim 1. According to such a method, the aim is to minimize the commuting of a load transported by a lifting crane.

The invention also relates to a device according to the preamble of claim 7, with which this minimization of the commuting of the load can be obtained.

It is common to use lifting cranes of different sizes and power in industrial and workshop premises to move especially heavy objects between production or work points. A traverse crane, or traverse, is a type of lifting crane which exhibits a supporting structure consisting of a main boom which advantageously rests on fixed parallel support beams along which the main boom can be displaced. These beams are usually located at each end of the main beam, but there are also traverse cranes where the beams lie above each other, the main beam projecting between the beams. A lifting crane has a trolley that can be moved along its main boom. An example of such a trolley is a teller, which can be moved on rails or directly on the lower flanges of a traverse's main boom. The trolley includes, among other things, a driving motor to drive it along the main boom as well as a machine-driven line, wire or chain-mounted lifting block.

Often, the efficiency of the work is determined by how quickly a movement of a load can be carried out with a lifting crane. Due to the inertia of the objects to be moved with the lifting crane, the load generally comes in a more or less strong pendulum movement. If the load is not too heavy, the commutes can be dampened by hand, but often a special maneuvering of the movements of the trolley and the main boom is still required to maintain a safe and stable transport of the load. The operation requires great skill and experience of the crane operator, properties that are not always available in a stressful work situation.

To facilitate the use of the cranes, over the years, various more or less automatic control systems have therefore been developed, with which attempts have been made to reduce the commuting that occurs at the object or cargo when transported in a direction parallel to the floor of the industrial or workshop premises. However, many of these solutions have proven to be both ineffective and costly in use and maintenance. Few of these known solutions can also be used to upgrade older lifting cranes with simple and quick means.

Examples of such control systems can be found in, for example, patent specification GB 1,183,126. Here, it can be read that the oscillation damping is effected by changing the flow rate of the load with two equally long and symmetrical acceleration periods that lie with a half oscillation period's phase shift from each other. In this way, a floating movement is achieved where the load of the crane is in a non-oscillating state before a new speed setpoint is given. The solution described relates to an electromechanical device which is based on a number of measurements to clarify, for example, the cargo transport times and displacement relative to the crane. The measurements are difficult to perform quickly and reliably enough to be able to regulate the load of the load even during short transport intervals.

On the other hand, in a solution according to publication US 5 219 420, the aim is to regulate the commuting of the load at any random time during the cargo transport. Also in this solution is described a device based on a number of measurements to continuously clarify, for example, the cargo transport times and displacement relative to the crane. As in the older solution, the measurements are difficult to perform quickly and reliably enough to be able to control the load's commuting even during short transport intervals. Similar solutions can also be found in publications US 3,850,308 and WO 03/95352.

Finally, a solution according to WO 103/041770 can be mentioned as it also teaches us that in addition to a number of measurements to continuously clarify, for example, the cargo transport times and displacement relative to the crane, use measurements to clarify the lifting line orientation. The idea with this solution is to be able to minimize the commuting of the load and also strive for a transport sequence to always start with as veritcal lifting line as possible.

Issue

With the present invention, the problems with known solutions can be substantially avoided. The object of the present invention is to provide an easy-to-handle method and apparatus for controlling a lifting crane with high operational safety. This task is solved in accordance with the invention in that the method of controlling a lifting crane according to the invention is given the characteristics of claim 1, while the device for controlling a lifting crane is given the characteristics of claim 7. The following independent claims specify suitable further developments and variants of the invention which further improve its function.

The invention is based on the idea of being able to offer one as simple as possible for its construction and use. This solution should be applicable both to new cranes and to cranes that have been in use for a shorter or longer period.

The present invention is described in the following by illustrating a lifting crane with a so-called traverse crane. However, this is not intended to limit the invention only to this field of application, but the method and apparatus for controlling a lifting crane can be used equally well in other forms of cranes such as building cranes - so-called tower cranes - as various types of container cranes, portal cranes, box cranes and so on. .

In the present invention, "lifting line" is also meant the tool with which the trolley's lifting block regulates the height of the load, which may be a wire, a chain or any other suitable tool known to be used for this purpose.

In the following description, the terms "up", "down", "above", "below" and so on are referred to in relation to a device for controlling a lifting crane or its structural details as shown in the attached figures.

With the device and method described in the present invention, several significant advantages are achieved over the prior art. Thus, transport of cargo in a crane can be controlled by simple means that sufficiently prevent a cumbersome or even dangerous commuting of the cargo. The device can be installed both in new and in existing cranes without major hassle and at a reasonable cost. The use of the crane also does not entail any new control commands, but the crane can continue to be used in the already learned way.

Further advantages and details of the invention will become more apparent from the description below.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention is described in greater detail with reference to the drawing, in which figure 1 shows a lifting crane movable along rails and provided with a transverse trolley with lifting hook, figure 2 shows in a graphical view the respective movements of the trolley and the cargo handled thereof, figure 3 Figure 4 illustrates the control of the lifting crane, Figure 4 shows the control's influence on the lifting crane's trolley, Figure 5 shows a flow chart of the lifting crane routing routine, and Figure 6 shows a flowchart of the lifting crane's alternative control routine.

Preferred embodiment

The above-mentioned figures do not show a device for controlling a lifting crane or its use in scale, but only serve to illustrate the constructive solutions of the preferred embodiment and the function of the embodiment. In this connection, the respective structural parts shown in the figures and marked with reference numerals correspond to the structural solutions presented in this description presented below and at the same time indicated by a reference numeral.

A lifting crane 1 is thus illustrated in the present description and figures of a so-called traverse crane, the construction of which is shown in particular in Figures 1 and 4. However, the solutions described hereinafter can also be applied to other types of lifting cranes and lifting devices in which it is desired to limit the commute. which occurs in a load when it is moved with the lifting crane.

The lifting crane 1 hereby exhibits a main boom 2 advantageously arranged to be displaceable in relation to its surroundings. Thus, the traverse crane according to the attached figures is arranged on support means 3, such as beams, which according to Figure 1 are arranged, for example, along parallel walls in an industrial room. Such support means may also be arranged one above the other in a manner known per se. In other known solutions, the support means may comprise a turntable which makes the main boom of a tower crane rotatable relative to its vertical tower. Furthermore, the support means may comprise, for example, a wheeled portal which can be driven along horizontal tracks or freely along a substantially flat surface.

The lifting crane 1 further has at least one trolley 4 arranged to the main boom 2 where it can be moved along the main boom by means of at least one driving motor 5 which advantageously comprises an inverter controlled steplessly functioning electric motor. This trolley, in turn, has a machine-driven lifting block 6 with which a lifting line 7 and an additional lifting hook 8 are arranged in a substantially vertical direction. Furthermore, if the main boom is slidable relative to its surroundings, it has drive means 9 for moving the main boom along its supporting means 3.

In order to be able to control both the movements of the trolley 4 along the main boom 2 as well as the movements of the main boom along its supporting means 3, a number of measuring means such as at least one speedometer is needed to measure the speed of the lifting block 6 relative to its surroundings. The speed of the lifting block can hereby comprise only the movement of the trolley along the main boom, a movement of the main boom along the support members or a combination of movements of the main boom along the support members and the movement of the trolley along the main boom, the latter alternative being shown in Figure 1 and illustrated by arrows B-F and L-R in the figure. These measuring means are of a generally known kind and are not part of the present solution and are therefore not shown in more detail in the figures.

In addition to said speedometer, the lifting crane 1 of the lifting crane 1 has an angle meter 10 arranged to assess the position of the lifting line 7 relative to its vertical rest position shown with the vertical line 11, compare figure 4. The angle meter advantageously measures the angle α of the lifting line and the vertical line in a more or less continuous. This measurement data is delivered to a control unit 12 which can process said data and from this assess the angular velocity ω of the lift line relative to its vertical rest position and the direction of movement of the lift line. The angle meter works with advantage in a three-dimensional measuring space, but the angle meter can also comprise one or more measuring devices, to detect deviations in different geometric directions.

The control unit 12 cooperates with at least one control unit 13 arranged to actuate the driving means 9 and the driving motor 5, respectively, according to information it receives from the control unit. In this case, the same control unit may be arranged to operate either the driving means or the driving motor, or both the driving means and the driving motor.

The control unit 12, shown by the lifting crane 1, with the angular meter 10 connected thereto, makes it possible to easily and reliably minimize the commuting that most often occurs in a load 14 when it is to be transported in a direction which differs from the vertical. The procedure utilizing this control works as follows. See also Figure 5.

When a transport command 15 is given by a crane user 16 via a control box 17, this means that the angle meter 10 shown by the trolley 4 first assesses the position of the lifting line 7 which exits from the trolley and which can handle loads 14 of different kinds via the lifting hook 8 arranged therewith. . The angular measurement data 18 regarding the actual position of the lift line relative to its vertical rest position, compared with the vertical line 11, is transmitted to the control unit 12 which further assesses the angular velocity ω and the direction of movement relative to its vertical rest position. If the control unit judges that the lifting line occupies the substantially vertical rest position, a first control signal 19 is provided to at least one control unit 13 which transmits the control signal to control only the movement of the trolley 4 along the main boom 2, the movements of the main boom 2 along the support members 3 and a combination of the main boom movements. movement along the main boom. The actuation signal results in a substantially stepless acceleration cycle of the driving means and the driving motor, respectively, where the lifting block obtains a speed corresponding to half the maximum speed, which is illustrated by phase I in Figure 2.

At the same time, observations of the direction of movement of the lifting line 7 and the angular position which are continuously forwarded to the control unit 12. continue when the half-speed of the lifting block 8 has been reached, the measured values are recorded for this moment. The control unit now orders the acceleration to cease and the achieved speed is maintained, which is in turn illustrated by phase II in Figure 2. Thereafter, the continuous observation of the direction of movement and the angular position of the lifting line continues. When the lifting line again occupies the same angular position but exhibits an opposite direction of movement, compared with the measured values above, the control unit 13 is allowed to transmit a second operating signal to the driving means and the driving motor respectively. The actuation signal results in a second substantially stepless acceleration cycle at a speed corresponding to the entire maximum speed of the lifting block, as illustrated by phase III of Figure 2. When this maximum speed is reached, the control unit again orders the acceleration to cease and the achieved speed is maintained again. transport command is received, compare phase IV in figure 2.

Depending on the nature of the movement and transport command 15, the controller 13 manages either the drive means 9 or the drive motor 5, or both the drive means and the drive motor.

Thus, the type of operation of a lift block 8 described above occurs when a load 14 at the commencement of the movement is stationary. Often, however, the load already exhibits a commute when the transport command 15 reaches the control unit 12. Alternatively, the load may be stationary, but thus offset that the lifting line 7 has an angle relative to its vertical position. In order to prevent problems that may arise in such situations, the operating procedure can be slightly modified. This modification can be seen in Figure 6 and works as follows.

When the transport command 15 is given by a crane user 16, the angle meter 10 first assesses the position of the lifting line 7 in relation to the vertical line 11.

If the lifting line already has an angle α vis-à-vis its vertical position, the control unit 13 is allowed to transmit the first transport control signal to the driving means 9 and the driving motor 5 only when the load 14 (the lifting line) exhibits a direction of movement which essentially coincides with a direction of movement indicated in the transport command.

This first operating signal, as before, results in a substantially stepless acceleration cycle which manages the movement of the trolley 4 along the main boom 2, the movements of the main boom along the support members 3 or a combination of movements of the main boom along the support members and the movement of the trolley along the main boom, where the lift block 6 receives a maximum speed of speed (phase I). At the same time, the control unit's 12 observations of the lifting line's direction of movement and angular position continue to measure the time T it takes for the load to receive a direction of movement which is opposite to the direction of movement specified in the transport command 15 after the first actuated signal.

When the lift block 6 reaches its half maximum speed, the measurement values for the direction of movement of the lift line 7 and the angular position a are recorded again. The control unit 12 now orders that the acceleration cease and the achieved speed is maintained (phase II). Thereafter, a continuous observation of the direction of movement and angular position of the lifting line continues, so that when the lifting line occupies an opposite direction of movement in the direction of the transport command 15, the control unit waits for a position of the lifting line corresponding to the angle when half the maximum speed is reached multiplied by time (T). the angular velocity of the lift line.

Now, a second operating signal can be transmitted to the drive means 9 and the driving motor 5, respectively, which results in a second substantially stepless acceleration cycle at a speed corresponding to the entire maximum speed of the lift block 6 (phase III). When this maximum speed is reached, the control unit again orders the acceleration to cease and the achieved speed is maintained until a new transport command is received (phase IV).

The description above and the figures therein are intended only to illustrate the present solution for the construction of a device for controlling a lifting crane or its use. Thus, the solution is not limited only to the embodiment described above or in the appended claims, but a variety of variations or alternative embodiments are possible within the idea described in the appended claims.

Claims (5)

A method of controlling a lifting crane (1) which has a main boom (2), at least one trolley (4) arranged to the main boom, said trolley comprising a driving motor (5) driving the trolley along the main boom, the trolley having a machine-driven lifting block ( 6) operating a lifting line (7) and a lifting hook (8) arranged therein in a vertical direction, and at least one speedometer measures the speed of the lifting block relative to its surroundings, an angle meter (10) which assesses the position of the lifting line (7) relative to its vertical rest position (11). ), such that the angular meter's measurement data is transmitted to a control unit (12) which assesses the angular speed (ω) of the lifting line and the direction of movement relative to its vertical rest position, at least one control unit (13) manages the driving motor (5) according to information it receives from the control unit, a given transport command (15) determines the control unit (12) the direction of movement of the lifting line (7) so that if the lifting line n exhibits a position that deviates from its vertical position at the vertical line (11) to allow the control unit (13) to transmit a first operating signal to the driving motor (5) only when the load (14) exhibits a direction of movement substantially coinciding with a direction of movement specified in the transport command, which first operating signal entails a substantially stepless acceleration cycle which manages the lifting block (6) at a speed corresponding to half its maximum speed, characterized in that the control unit (12) measures the time (T) it takes for the load (14) to receive a transmitted first operating signal. direction of movement which is opposite to the direction of movement stated in the transport command (15) so that when the lifting line (7) re-occupies an opposite direction of movement in the direction of the conveying command (15), the control unit waits for a position of the lifting line (7) corresponding to the angle when half the max. speed achieved decreased by time (T) multiplied by lifting line Ans angular velocity (ω), after which a second operating signal is transmitted to the driving motor (5) which results in a second substantially stepless acceleration cycle at a speed corresponding to the maximum speed of the entire lift block (6). Method for controlling a lifting crane (1) according to claim 1, characterized in that the main boom (2) is arranged to be movable relative to supporting means (3) with drive means (9), the control unit (13) actuating the driving means (9) and the driving motor respectively. (5) according to information it receives from the control unit (12). Method for controlling a lifting crane (1) according to claim 2, characterized in that the control unit (13) manages either the driving means (9) or the driving motor (5). 4th Method for controlling a lifting crane (1) according to claim 2, characterized in that the control unit (13) manages both the driving means (9) and the driving motor (5).