This function allows to turn construction cranes with different acceleration and deceleration levels. As a result, it helps ensure a soft movement without creating a high force against the construction of the crane.
When starting a slewing (rotation) movement of the jib on a tower or self-erecting crane, it is necessary to overcome the inertia of the jib. There is always a chance of an over-torque (during start) or over-speed (during stop) condition. To help prevent this over-torque or over-speed condition, it is necessary to control the acceleration and deceleration ramps.
This specification explains two different solutions for smooth slewing:
oType 1 : Speed based
oType 2 : Torque based
This function influences acceleration and deceleration of the slewing drive:
oIn Type 1: Speed based
The acceleration and deceleration time is adjusted based on the varying speed level during the acceleration and deceleration.
oIn Type 2: Torque based
The acceleration and deceleration time is adjusted based on the varying torque level during the acceleration and deceleration.
The smooth slewing solution is applicable to:
oTower cranes
oSelf erecting cranes
Why Use the SmoothSlewingTrq or SmoothSlewingSpd Function Block?
The function blocks allow to create a soft turn of a tower or self-erecting crane based on the different levels of torque or speed movement reached. This helps protect the mechanism of the crane from high forces and allows a better stable movement of the load.
This function block is intended to have significant influence on the physical movement of the crane and its load. The application of this function block requires accurate and correct input parameters in order to make its movement calculations valid and to avoid hazardous situations. If invalid or otherwise incorrect input information is provided by the application, the results may be undesirable.
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UNINTENDED EQUIPMENT OPERATION |
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Validate all function block input values before and while the function block is enabled. |
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Failure to follow these instructions can result in death, serious injury, or equipment damage. |
Solution with the SmoothSlewingTrq or SmoothSlewingSpd Function Block
The function blocks use information about torque or speed out of the drive. The function block is changing depending on the level of torque/speed and the acceleration or deceleration rate of the drive. This creates a flexible ramp which allows the drive to lead the crane structure into a gentle rotation (Smooth slewing).
