Vibration monitoring of screens / feeders
What are the challenges in monitoring the vibration of screens / feeders?
- This amazing machine normally runs at 3 to 7 G of acceleration. There is no doubt that protection against excessive vibration is very important.
- Motors and gearboxes are subjected to extreme conditions due to the excessive movement of the screen itself. Therefore, measuring the temperature of this equipment is essential for smooth operation and historical trending.
- Unbalance, misalignment, gear mesh frequency, bearing, peak acceleration (generated by the feeder) and also the angle of the screens are critical and require online monitoring.
Vibration monitoring of screens / feeders
How to ensure a safe operation without excessive structural displacement?
A vibrating screen is used to sort rocks of different sizes or other products. The force is generated by using eccentric weights or eccentric bearing set to create an angular orbital motion. When using weights, they are mounted on the motor shaft for small screens and on gearbox shafts for larger screens. In case of a catastrophic failure, the machine can be automatically switched off to prevent safety hazards to other equipment and people nearby. To monitor the trend of the screen movement, it is necessary to detect the displacement in the horizontal and vertical axis. ifm’s VSE diagnostic electronics are capable of detecting tenths of a millimeter and retransmitting the data via different platforms.
How to protect the screen from a sudden increase in temperature?
Efficiency can be assessed by monitoring the temperature change in the motors and / or gearboxes. Process quality can only be achieved if vibration and temperature are measured at every point and transmitted in a timely manner. In addition to temperature measurement, the ifm temperature sensors are able to send internal sensor diagnostic information from each measurement point, creating a reliable system based on self-testing. To perform the diagnostic functions, ifm provides an IO-Link master-to-fieldbus protocol for connecting analogue devices and PT100 temperature sensors.
Process quality can only be achieved by ensuring the correct vibration level, but how to implement a cost-effective monitoring solution?
Due to the high stress on the metal, the screen frames sometimes crack or break or the rubber or spring mounts fail. If the cracks or defects are detected before excessive damage is sustained, repair can be scheduled before a catastrophic failure occurs. With the VSA / VSP sensor, machine vibration can be measured even in inaccessible places. Up to 4 measurement points can be monitored and documented per VSE diagnostic electronics. The Ethernet and fieldbus interfaces simplify networking and remote diagnostics. The overall vibration velocity is used in industry standards to evaluate the status of the entire machine. ISO 10816 categorises machines and defines the general level of protection, but the system also allows specific problems to be identified using: - speed monitoring sensors - motor vibration sensors - gearbox vibration sensors - angular position sensors etc.
