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Entry type: Application example Entry ID: 60162652, Entry date: 01/28/2016
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SIMOCRANE: Straight-run controller CeNIT

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Purpose Avoiding wear of crane track wheels and rails.

Task

Avoiding wear of crane track wheels and rails
The most frequent cause of excessive wear of crane track wheels and rails is caused by off-tracking. This can have various causes, for instance excessive off-center loads or rail tracks that have subsided or uneven driving forces. The actual cause for significant wear of a crane can frequently not be determined or resolved. When using the straight-run controller, it is possible to control the crane so that off-tracking is prevented. It maintains the crane alignment parallel to the rail track – therefore significantly reducing the wear.

Solution

Electronic straight-run control
The task of the straight-run control is to specifically align the crane to the rail center line by applying different drive torques – and thus keep the crane at this center position. Contactless sensors mounted on one of the two head beams measure the transverse offset between the track wheel and rail. Using this sensor data and the travel signals, the controller calculates the setpoint velocity for both drive sides. If the crane travels too far to the left, then it is controlled to the right – if it is centered, then it travels straight ahead. In most applications, the controller ensures that the crane moves along the reference line (track center line) in a corridor tolerance of ± 5 mm. The wheel flange does not come into contact with the rail.

Application conditions
The straight-run controller is primarily suited for EOT cranes where increased wear of track wheels and rails has been observed or is to be expected. Both drive sides of the crane must be equipped with a drive that can be continuously controlled (converter drive). It must be possible to mount sensors at both ends of a head beam. This controller has already been successfully used on applications involving coil handling cranes, scrap cranes and paper roll handling cranes.

Feature
Depending on the travel direction (forward/backward), the sensor pair for each travel direction measures the centered run of the wheel on the rail. These analog signals are transmitted to the S7-1200 controller.

Depending on the position of the wheel with respect to the rail, the control manipulates the travel speed of the crane’s drives so as to direct the crane in the direction to correct any misalignment.

Using the integrated web server of the S7-1200, a variety of parameters can now be set. For example, the speeds for each speed step or a general offset can now be set. On top of that, using the function "Recording", you can display the sensor data in a diagram and thus analyze the crane travel path much better.

The application consists of:

  • a control unit mounted on a DIN rail (TS35) based on S7-1200 components
  • an integrated web server for diagnosis and parameterization
  • 4 inductive sensors monitoring the alignment of the crane

Advantages

  • Drive technology-based electronic control to avoid off-tracking and axial offset on bridge cranes.
  • Controls and maintains the crane permanently in the track center
  • Reduction of wear and tear of wheel flanges, guide rollers and rails
  • Avoids jamming of the crane gantry

Benefits
Using the SIMOCRANE straight-run controller CeNIT, you can extend the life-cycle of crane wheels and rails by reducing wear and tear.

Note
If interested, please contact the respective sales contact.
Contacts worldwide

Download
  60162652_Flyer_straight-run_controller_SIMOCRANE_CeNIT_EN.pdf (494,6 KB) 

Additional Keywords
motioncontrol_apc_applications


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