Practical case of mechanical inspection - intervention during factory shutdown
The situation
A DMC - Iberian Engineering and Systems, Lda. effected, a supervision of fan assembly and leveling, of the alignments of the roller drive and assembly and tightening of new bearings in the combustion air fans during the factory shutdown, for maintenance. This intervention came after, under the program predictive maintenance, and with measuring vibrations, common vibration analyzer laptop, have been detected through vibration analysiss, the need to make some improvements to the machines.
Leveling two fans
The recorded leveling values are shown in Figure 1. As can be seen, the deviations recorded are within the specified tolerance.
Figure 1 - Final leveling condition of the fans
Roller drive
The gearbox was replaced, DMC having performed the alignment of the reducer / roller and motor / reducer. The final alignment values are as follows:
Figure 2 - Final alignment condition, reducer / roller and motor / reducer of Roller drive
Combustion air blower
Have been replaced the bearings, bearings, seals and transmission belts.
The positioning and tightening of the bearings was monitored. After adjusting the tapered bush to the shaft and bearing, the clamping nut rotated 90º.
The alignment of the engine gornes drums and the shaft was checked. The tension of the belts was checked.
Note: The fan shaft in the bearing area is knocked due to the previously incorrect bearing tightening.
Figure 3 - Condition of the shaft in the bearing tightening zone.
Bearing support base
It is verified that the bearings tighten directly on the structure with an uneven support surface. The bearing must be supported on a flat surface, which is a steel sheet of 10 mm welded to the frame and machined.
Figure 4 - Fan structure where the bearings tighten, shows the absence of a planned surface for the bearing to support
Figure 5 - Bearing base. The contact points of the bearing to the base are visible.
Combustion air blower
Bearings have been replaced, bearings and seals and rims.
The positioning and tightening of the bearings was monitored. After adjusting the tapered bush to the shaft and bearing, the clamping nut rotated 90º.
Note: The fan shaft in the bearing area is knocked due to the previously incorrect bearing tightening.
The bearings that were replaced were unscrewed The bearings were knocked out having been replaced.
Figure 6 - Image of the beaten bearing.
