Pусский
Selecting appropriate structure for mechanical seals can effectively strengthen lubrication conditions between rotary faces and stationary seats, thereby ensuring stable operation of and prolonging service life of the mechanical seals. This article is intended to discuss two structure forms.
1.end face eccentricity：
In general mechanical seals, center of rotary face, center of stationary seat and center line of shaft are all on a straight line. If center of one of friction pairs end faces is offset from center line of shaft by a certain distance , the eccentric ring can continuously bring lubricating fluid to the sliding surface when it rotates.
It should be pointed out that eccentric amount should not be too large, especially for high pressure conditions, for eccentricity will cause uneven pressure on the end face, resulting in uneven wear. For high-speed mechanical seals, it is not advisable to use rotary face as an eccentric ring, otherwise the machine will vibrate due to the imbalance of centrifugal force.
2. engrooving on end face:
It is difficult for high-pressure and high-speed machinery to maintain liquid film between friction surfaces, because liquid film is often destroyed by frictional heat generated by high pressure and high speed. In this case, it is very effective to take form of opening slots to intensify lubrication.Both rotary face and stationary seat can be engrooved, generally on more wear-resistant materials. Rotary face and stationary seat should not be engrooved both as this will reduce lubrication effect.
In order to prevent dirt or wear debris from entering friction surface as much as possible, for outflow type mechanical seal which means the liquid flows in the same direction of centrifugal force, groove should be opened on stationary sea to avoid action of centrifugal force to introduce dirt into friction surface.On the contrary, when liquid flows in direction of reverse centrifugal force (internal flow type mechanical seal), groove should be opened on rotary face, so that centrifugal force will help to throw dirt out of the groove.
The small grooves on friction surface are rectangular, wedge-shaped, or other shapes. The grooves should not be too many or too deep, otherwise the leakage will increase.
1.end face eccentricity：
In general mechanical seals, center of rotary face, center of stationary seat and center line of shaft are all on a straight line. If center of one of friction pairs end faces is offset from center line of shaft by a certain distance , the eccentric ring can continuously bring lubricating fluid to the sliding surface when it rotates.
It should be pointed out that eccentric amount should not be too large, especially for high pressure conditions, for eccentricity will cause uneven pressure on the end face, resulting in uneven wear. For high-speed mechanical seals, it is not advisable to use rotary face as an eccentric ring, otherwise the machine will vibrate due to the imbalance of centrifugal force.
2. engrooving on end face:
It is difficult for high-pressure and high-speed machinery to maintain liquid film between friction surfaces, because liquid film is often destroyed by frictional heat generated by high pressure and high speed. In this case, it is very effective to take form of opening slots to intensify lubrication.Both rotary face and stationary seat can be engrooved, generally on more wear-resistant materials. Rotary face and stationary seat should not be engrooved both as this will reduce lubrication effect.
In order to prevent dirt or wear debris from entering friction surface as much as possible, for outflow type mechanical seal which means the liquid flows in the same direction of centrifugal force, groove should be opened on stationary sea to avoid action of centrifugal force to introduce dirt into friction surface.On the contrary, when liquid flows in direction of reverse centrifugal force (internal flow type mechanical seal), groove should be opened on rotary face, so that centrifugal force will help to throw dirt out of the groove.
The small grooves on friction surface are rectangular, wedge-shaped, or other shapes. The grooves should not be too many or too deep, otherwise the leakage will increase.
