Excessive axial vibration in the Roots blower
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For the Japanese Daikyo Roots blower (exact model unknown), the total clearance between the front and rear wall panels and the rotor is 100 mu. There are radial inlets and outlets; those who are familiar with this model would know what it is :) It would be helpful to have Daikyo’s clearance table or manual available. 1. Due to excessive radial vibration, this blower was taken apart for inspection, and it was found that there was scraping between the rotor and the casing (no scraping with the wall panels). The impeller and shaft were polished, and the support and positioning bearings were replaced. After reassembly, it was operated without load (with the outlet pipe disconnected) for 30 minutes, with no significant changes observed (vibration, noise, and temperature were all within acceptable limits). 3. The axial vibration under load increases from 4 mm/s at no load to 12 mm/s. (The drive shaft and the driven shaft are both large); only the non-drive end is large. The measurement location is on the positioning bearing cover. 4. After 3 adjustments of the gap between the rotor end face and the wall panel, there was no significant change in vibration. The gaps after those 3 adjustments were: (25 mm at the front + 75 mm at the back, 35 mm at the front + 65 mm at the back, 45 mm at the front + 55 mm at the back). 5. The vibration of the machine body is within the normal range. 6. The connecting bolts were tightened again; there is no looseness or insufficient tightening. 7. Upon rechecking alignment, the distance between the two pulleys of the coupling was found to be greater than the thickness of the diaphragm; this was resolved by tapping the pulleys of the motor to reduce the distance between them to the thickness of the diaphragm. 8. After the final adjustment of the gaps and correction of the pulley distances, the axial vibration under load was 7 mm/s; however, today it was around 12 mm/s again. 9. There is no significant change in current, and the outlet pressure and temperature are within the normal range. 10. The rotor is unbalanced. Please help analyze this situation: dizzy:. An inspection diagram will be prepared tomorrow!
If alignment is not correct, check whether there are any issues with the motor’s edges
Isn’t misalignment the main reason for large radial vibrations? If you open your mouth, isn’t the vibration greater at the driven end compared to the undriven end?
Could it be that the axial clearance difference between the two rotor positioning bearings is too large?
The gland is pressed against the outer ring of the positioning bearing, with no allowance
Are synchronous gears helical gears? Adjust the angular gap between the two rotors; try making the contact area between the driving wheel and the driven wheel 5 to 8 teeth larger.
Mismatching of centers leads to large axial vibrations, while mechanical looseness causes large radial vibrations
This fan must have been in operation for quite some time. Please check whether the gear mesh clearance is too large, which is causing the impeller collision issue.
I’d like to recommend a new product to you: a magnetic levitation centrifugal blower. When the equipment is in operation, the shaft and impeller remain suspended in mid-air, resulting in no vibration or noise. And it has no bearings, no gearbox, no need for oil or water – it’s maintenance-free! Also, the bearings and gearboxes are no longer there, so the operating resistance is reduced, which means energy savings. In fact, the energy savings amount to around 20%~30%. Do you think it’s worth replacing your equipment with this new one? ? ?
Is there a solution? Our unit’s fans are also experiencing this problem: two of the fans have axial vibration levels of 13 in their positioning bearings, while another fan has a level of 50. Replacing the bearings hasn’t resolved the issue; we hope to get suggestions on how to fix it
Others need to buy your products as well, right?... Besides, what you say doesn’t mean they can necessarily use them; and even if they could, their boss would have to give permission...