What is the reason why the friction marks on the sealed end face are larger than the width of the sealing surface?
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The widths of the two sealing surfaces that make up the friction pair are not equal. Generally, the hard-sealed surface is wider, while the soft surface is narrower. After operating for a period of time, clear friction marks appear on the hard-sealed surface, and the cause of the fault can be determined based on the width of these marks. The reason why the friction marks on the sealing surface are larger than the width of the soft ring is as follows: 1) The pump operates with significant vibration, which causes the rotating ring to experience radial and axial oscillations; as a result, the thickness of the liquid film changes greatly, and sometimes the sealing surfaces are pushed apart, leading to an increase in leakage. 2) The stationary and rotating rings are out of alignment. In conventional rotary seals, the stationary ring is mounted on the gland. There is a \"stop shoulder\" when the gland and the sealing chamber are fitted together, to ensure their concentricity. In fact, the clearance at the stop often exceeds the appropriate value, causing the stationary ring to \"sink\" and resulting in a misalignment between the stationary and rotating rings. In static bellows sealing, the weight of the stationary ring assembly causes it to \"sink\", which in turn results in a misalignment between the stationary and moving rings. Furthermore, excessive clearance in the bearing housing and shaft bending can both cause the friction marks to be too wide. A method to overcome the above defects is to first eliminate the vibration of the pump. Find the dynamic balance of the rotor ； Use couplings that are less likely to cause vibration (such as spring plate couplings and gear couplings, etc.) ； Correct the concentricity of the pump and motor ； Check whether the clearances at various flanges of the pump are too large; in stationary bellows, a support is placed below the static ring to prevent \"sinking\".
The friction marks on the sealed end face being larger than the width of the sealing surface are mainly due to misalignment of the stationary and rotating rings or excessive vibration during pump operation. 1. The vibration generated during pump operation causes the moving ring to move axially and radially, resulting in uneven variations in the thickness of the liquid film; this sometimes separates the sealing surfaces and increases leakage. 2. The misalignment of the stationary and rotating rings may be caused by improper installation or excessive gaps between the components; for example, the stationary ring may sink due to its weight or there may be excessive gaps at the sealing surfaces, leading to such misalignment. Solutions to these problems include eliminating pump vibration, ensuring mechanical leveling, using high-quality couplings, correcting the alignment accuracy of the pump and motor, as well as checking and adjusting component clearances; if necessary, adding support under the static ring to prevent it from sinking. .