Fan exhaust fan maintenance records, with illustrations

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Induction Fan Maintenance Record Equipment Name: Induction Fan; Location Code: -------; Type: Cantilevered centrifugal fan. Maintenance Date: -----------; Person performing maintenance: ------------------------; Equipment fault: Damage to the bearing at the impeller end； Treatment 1: Perform dynamic balancing of the impeller ； 2. The axial straightness deviation is large; machine a new shaft ； 3. The inner diameter of the bearing seat at the impeller end has increased; it needs to be repainted and plated ； Consumption of accessories – Self-aligning roller bearings: 22224 CAME4 C3 (large clearance) / 22224 CAME4. Cause analysis: During the last major maintenance, while servicing the fan, the locking plate of the front bearing failed to secure the lock nut. After the fan operated for some time, the lock nut loosened, preventing proper positioning of the inner ring of the bearing. As a result of axial forces, relative movement occurred between the shaft and the inner ring of the bearing, leading to unstable operation of the bearing. On -- year -- month -- night, the situation suddenly worsened; the temperature of the bearing increased sharply, which in turn raised the temperature of the lubricating oil. Due to aging and the high temperature, the sight glass fell off, and most of the lubricating oil flowed out through it. This further damaged the bearing, causing friction between the outer ring of the bearing and the inner hole of the bearing housing. Vibration of the fan increased significantly, so the maintenance staff was promptly informed to stop the fan for repairs. Note 1: For the first repair, the bearing housing is machined; there is an interference fit between the inner hole of the bearing housing and the outer ring of the bearing (0.04 mm) ； 2. For the second repair, machine the bearing housing; the fit between the inner hole of the bearing housing and the outer ring of the bearing should be an interference fit (0.005 mm) ； 3. Third maintenance: Machine the bearing housing; the fit between the inner hole of the bearing housing and the outer ring of the bearing should be a clearance fit (0.04 mm) ； Inspection photos: 1. For the impeller end bearing housing, after removing the bearing cover, it was found that the bearing lock nut had not secured the inner ring of the bearing, resulting in axial movement of the rotor, as shown in the figure below ； Self-aligning roller bearings rely on positioning sleeves, lock plates, and lock nuts to prevent relative sliding between the inner ring of the bearing and the shaft. 1. Measurements showed that the lengths of the parts of the bearing outer rings that are positioned by the four bearing caps vary – two are short and two are long. The previous maintenance team installed the bearing seats with one long part and one short part each; as a result, the fan did not operate smoothly. Therefore, a positioning ring (14 mm) was added to the bearing cap at the rear end to help position the bearings ； 2. Through analysis and measurement of the depth from the end face of the bearing housing to the outer ring of the bearing, it was found that when installed in the order mentioned above, the gland sleeves of both bearing housings were unable to fully position the bearings; as a result, the rotor could not be positioned axially, and abnormal movement of the rotor occurred during operation. Therefore, the maintenance team later installed a positioning ring at the gland sleeve of the rear bearing housing to help position the rear bearing ； During reinstallation, the order of the gland caps was adjusted, with the gland caps of bearings 2 and 3 being swapped. The rear bearing is the positioning end, while the front bearing is the sliding end ； 3. Relative sliding occurred between the outer ring of the bearing and the inner hole of the bearing housing, resulting in wear of the inner hole of the bearing housing and an increase in its diameter. Machining was carried out; after researching relevant information and contacting the manufacturer, it was finally determined that the fit between the outer ring of the bearing and the inner hole of the bearing housing should be a clearance fit, with a clearance of 0.04 mm. (As the front bearings are subjected to greater stress and load, their temperature is higher than that of the rear bearings. The clearance fit ensures that an increase in temperature does not affect the bearing’s clearance (0.20–0.30 mm). It also allows the outer ring of the bearing and the inner hole of the bearing housing to undergo a certain amount of axial sliding under the action of the rotor’s axial force.) ； ) 4. After the bearing has been reinstalled, use a dial indicator to measure the runout at the shaft end; it should be 0.02 mm ； The impeller was dynamically balanced and adjusted; the correction mass (1) had its weight increased by 118 grams.