Problems with radial bearing force in centrifugal compressor units
Thread Content
This post was last edited by A pot of fragrant tea on 2011-10-19 09:40. During a routine inspection of the shaft bearings in the synthetic gas compressor, it was found that the radial bearings lacked sufficient tension (there was no interference on the back side of the bearings), and there was a gap of 0.09 mm (measured using the lead compression method). The bearing gap is within the normal range; please share your thoughts, fellow sailors – how would you handle such a situation?
Add adjustment shims. 1. Some units require a gap. 2. Some units require an interference fit (0.03~0.07mm)
Yes, some bearing backs have a clearance fit. The turbine I just serviced requires a clearance of 0.05–0.07 mm between the bearing backs; this value should be determined based on available data. If the shaft bearing clearance is appropriate, and it’s necessary to change the bearing back to an interference fit, it’s best to grind away an equivalent amount from the upper bearing seat
As a supplementary note, the prerequisite for grinding the tile seat is that there are no adjustment shims originally; if shims are present, simply replace them with thinner ones
Pay attention to the method for measuring the back pressure of the tile: equal-thickness shims should be placed on both sides of the mid-plane of the tile housing, and lead wires should be used for backing the tile. (The choice of wire should be based on the thickness of the mid-surface gasket; after compression, the amount of compression of the wire should not exceed 40% of its diameter.) The result obtained by subtracting the thickness of the mid-surface gasket from the thickness of the wire: a positive value indicates a gap, while a negative value indicates interference (tightness). Whether there should be a tight fit or a gap between the back surfaces depends on the design requirements; in the absence of specific requirements, it is usually adjusted to an interference of 0.02–0.04 mm.
The term \"lead pressing\" is quite accurate; it mentions the selection of the diameter of the lead wire. So, how should the length of the lead wire be chosen? Thank you
This interference amount is what we usually call clamping force. The interference amount is generally 3 to 5 threads. Additionally, I’ve heard that in some units, when installing the bearing shells, the positioning pins at the top of those shells are forgotten to be installed. As a result, the bearing shells rotate and block the oil inlet holes, which leads to bearing damage.