Questions about the friction between the moving and stationary rings of ordinary mechanical seals?
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As in the question, an ordinary mechanical seal has a friction pair of a moving ring and a stationary ring in the radial direction. Is there direct contact during operation? In the flushing plan plan01, does the flushing oil pass through the contact surfaces of the two friction pairs? If ① passes, how to form a seal in the axial direction to ensure no leakage? If ② is not passed, the self-flushing liquid only passes through the friction pair to take away the heat generated by friction and has a cooling effect. Moreover, the friction pairs of the moving and stationary rings are in direct contact. Is it a dry grinding problem?
From a microscopic perspective, any mechanical seal has two friction pairs that are in contact. The liquid film on the sealing surface is used to protect the sealing surface and play a role in lubrication and cooling.
Thanks, I have another question: If there is no contact, the sealing cavity medium will still leak through the gap between the friction pairs. I mainly don't understand why it can function as a seal without contact?
Thanks, I have another question: If there is no contact, the sealing cavity medium will still leak through the gap between the friction pairs. I mainly don't understand why it can function as a seal without contact?
This involves the issue of the contact design width of the mechanical seal sealing surface. If the design width is too large, the mechanical seal will burn, and if the design is too small, there will be problems such as leakage.
Thanks for the guidance. I saw a big spring inside the moving ring sleeve. Isn’t the function of this spring to tightly press the friction pair of the moving ring against the friction pair of the static ring? If there is no external pressure to balance the pressure of the spring, the two friction pairs will fit together, that is, they will rub directly during operation?
So what I am saying is that from a micro perspective, there is no contact, but from a macro perspective, there is contact. It can be understood that the mechanical seal bubble runs in the liquid, and the liquid takes away the heat of the friction pair.
I understand a little bit, that is to say, the friction pair is also lossy. I saw that the API682 standard stipulates that the sealing life is 3 years. Does it mean that the loss of the friction pair under normal working conditions must meet the 3 years? The function of the spring is that no matter how much the friction pair is lost, the spring can give an axial force to the friction pair of the moving ring, so that it always fits the friction pair of the static ring?