Condition Based Maintenance (CBM)Condition-based maintenance of machine drives
CBM was developed for monitoring the status of machine components (ball bearings, rinsing airs and temperatures.), thus allowing the customer to draw up an optimum plan of the requisite maintenance measures, but is also in a position to prevent consequential damage to the machine.
Principle of operationTotal machine vibrations
The total vibration value, also known as the effective vibration value, is detected by a vibration sensor and transmitted to the PLC unit in the form of an analogue signal (0-10 V or 4-20 mA). The effective value includes all vibrations occurring in the machine in the range from 10 to 1000 Hz. It can be used as a diagnostic tool for the unbalance of the machine. The limit values are configured in the PLC unit and signalise the condition in the form of a set of traffic lights on the visualisation system.
Diagnosis of the bearing is also performed by the vibration sensor. At present, the envelope curve and acceleration value of the inner race, outer race and rolling elements, as well as the envelope curve and acceleration of the entire bearing are monitored for this diagnosis, all in all eight measured values. The parameters for the ball bearing type and system component will be exactly assigned in the sensor.
The sensor transmits the collective alarm (switching contact) of the parameterised values to the PLC. The visualisation system generates the respective messages and displays them. The alarm factor is selected such that enough time remains to react without having to fear a sudden standstill of the system caused by bearing failure.
The temperatures of the fixed and floating bearings are detected by two PT100 temperature sensors. The analogue temperature signal (3-wire RTD sensor) is transmitted to the PLC unit. The limit values are configured in the PLC unit and signalise the condition in the form of a set of traffic lights on the visualisation system.
The flow rates of the classifying wheel gap rinsing air and the bearing rinsing air are detected by means of suitable flowmeters. The analogue air flow rate signal (4-20 mA) is transmitted to the PLC unit.
The limit values are configured in the PLC unit and signalise the condition in the form of a set of traffic lights on the visualisation system.